Skocz do pozycji: 1.

Tytuł:

Resource allocation in MIMO systems specific to radio communication

Autorzy:

Ghaderi, Bahar
Parhizgar, Naser

Powiązania:

https://bibliotekanauki.pl/articles/140794.pdf

Data publikacji:

2019

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

spatial modulation
multi quadrature amplitude modulation
modulation
Huffman coding
MIMO systems

Opis:

The performance of the multi-input multi-output (MIMO) systems can be improved by spatial modulation. By using spatial modulation, the transmitter can select the best transmit antenna based on the channel variations using channel state information (CSI). Also, the modulation helps the transmitter to select the best modulation level such that the system has the best performance in all situations. Hence, in this paper, two issues are considered including spatial modulation and information modulation selection. For the spatial modulation, an optimal solution for obtaining the probability of selecting antenna is calculated and then Huffman coding is used such that the transmitter can select the best transmit antenna to maximize the channel capacity. For the information modulation, a multi quadrature amplitude modulation (MQAM) strategy is used. In this modulation, the modulation size is changed based on the channel state variations; therefore, the best modulation index is used for transmitting data in all channel situations. In simulation results, the optimal method is compared with Huffman mapping. In addition, the effect of modulation on channel capacity and a bit error rate (BER) is shown.

Źródło:

Archives of Electrical Engineering; 2019, 68, 1; 91-100
1427-4221
2300-2506

Pojawia się w:

Archives of Electrical Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 2.

Tytuł:

Analog-based duobinary-4-PAM for electrical bandwidth limited optical fiber links

Autorzy:

Suhr, L.F.
Madsen, P.
Monroy, I. T.
Olmos, J. J. V.

Powiązania:

https://bibliotekanauki.pl/articles/173933.pdf

Data publikacji:

2016

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

optical communications
advanced modulation formats
multilevel modulation

Opis:

This paper presents a demonstration of a seven level duobinary-4-PAM signal operating at 10.16 Gbit/s. The polybinary generation is achieved by a simple electrical Bessel filter of 5th order, with a frequency cut-off of 1.8 GHz. We assess the impact of the filter placement, either at the transmitter or the receiver, and find the impact is minimal in terms of bit error rate performance in transmissions of up to 40 km of single mode fiber.

Źródło:

Optica Applicata; 2016, 46, 1; 71-78
0078-5466
1899-7015

Pojawia się w:

Optica Applicata

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 3.

Tytuł:

Binaural masking of amplitude modulation

Autorzy:

Kordus, M.
Sęk, A.
Kociński, J.

Powiązania:

https://bibliotekanauki.pl/articles/177557.pdf

Data publikacji:

2005

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

masking
masking in the modulation domain
modulation filterbank

Opis:

A new concept concerned with the transformation of acoustic stimuli in the auditory system postulates the existence of a form of spectral analysis applied to the amplitude changes of the stimuli. It is assumed that this analysis takes place in the so-called modulation filters, i.e. bandpass linear filters tuned to different rates of the amplitude changes. The most striking argument supporting this idea is an effect of masking in the amplitude modulation domain whose nature can be easily explained basing on this concept. As the modulation filters are situated on the higher levels of the auditory system, it is also assumed that this form of masking is entirely a central process. However, most of the studies concerned with masking in the modulation domain used monaural listening only. Therefore, the main purpose of the presented here experiments was to investigate whether this type of masking is entirely a central process. Using a Three-Alternative Forced-Choice (3AFC) procedure the binaural and monaural masked thresholds of amplitude modulation were determined. A sinusoidal carrier at a frequency of 4 kHz was amplitude modulated by a specially designed band of noise characterized by a very low value of the crest factor, which was used as a masking signals. Different bandwidths of the modulating masking signals were used as well as different center frequencies to investigate whether the masking patterns in the modulation domain depend on the masker bandwidth and its center frequency. The modulating target (masked) signal was a pure tone at a frequency range from 2 to 256 Hz. Both modulating signals were applied to the same sinusoidal carrier signal. The most effective masking was noticed when the rate of the sinusoidal modulation was close to the center frequency of the masking signal or when it was in its spectral range and decreased outside of this range. The character of this dependence confirms the existence of some form of a frequency selectivity in the modulation rate domain similarly to the audible frequency domain. The thresholds for monaural and binaural listening were very close to each other. This implies that masking in the modulation domain is a central process.

Źródło:

Archives of Acoustics; 2005, 30, 1; 5-17
0137-5075

Pojawia się w:

Archives of Acoustics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 4.

Tytuł:

Adaptive procedure for automatic modulation recognition

Autorzy:

Liedtke, F.

Powiązania:

https://bibliotekanauki.pl/articles/308334.pdf

Data publikacji:

2004

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

modulation recognition
modulation classification
signal analysis
radio monitoring

Opis:

An adaptive procedure for automatic modulation recognition is described. With it the automatic modulation classification and recognition of radio communication signals with a priori unknown parameters is possible effectively. The results of modulation recognition are important in the context of radio monitoring or electronic support measurements. The special features of the procedure are the possibility to adapt it dynamically to nearly all modulation types, and the capability to recognize continuous phase modulation (CPM) signals like Gaussian minimum-shift keying (GMSK) too. A time synchronization to the symbol rate is not necessary.

Źródło:

Journal of Telecommunications and Information Technology; 2004, 4; 91-97
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 5.

Tytuł:

Analytical Models for Distribution of the Envelope and Phase of Linearly Modulated Signals in AWGN Channel

Autorzy:

Moazzeni, T
Jiang, Y.
Selvaraj, H.
Chen, T.

Powiązania:

https://bibliotekanauki.pl/articles/226459.pdf

Data publikacji:

2014

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

digital modulation
linear modulation
probability density function
phase
AWGN

Opis:

In this paper, analytical expressions for the distribution of the envelope and phase of linearly modulated signals such as BPSK, M-PSK, and M-QAM in AWGN are presented. We perform numerical simulations for different orders of signal constellations. The results show that the proposed theoretical models are in excellent agreement with the estimated distributions from various numerical experiments.

Źródło:

International Journal of Electronics and Telecommunications; 2014, 60, 1; 79-82
2300-1933

Pojawia się w:

International Journal of Electronics and Telecommunications

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 6.

Tytuł:

Transmission Perspective on the Mechanism of Coarse and Fine Crackle Sounds

Autorzy:

Lu, Bing-Yuh
Hsueh, Meng-Lun
Wu, Huey-Dong

Powiązania:

https://bibliotekanauki.pl/articles/1953484.pdf

Data publikacji:

2021

Wydawca:

Polska Akademia Nauk. Czasopisma i Monografie PAN

Tematy:

crackles
computer simulation
lung sound
respiration
amplitude modulation
frequency modulation

Opis:

The possibility of a normal distribution indicates that few particles are in the same phase during a breath and their reflections can be observed on the chest wall, then a few explosive waves with relatively large power occurr occasionally. Therefore, the one-cycle sine wave which is simulated as a single burst of the explosive effect phenomenon penetrates through the chest wall and was analysed to explore the reason of the crackle sounds. The results explain the differences between the definitions of crackle proposed by Sovijärvi et al. (2000a). The crackles in the lungs were synthesised by a computer simulation. When the coarse crackles occur, the results indicate that higher burst frequency carriers (greater than 100 Hz) directly penetrate the bandpass filter to simulate the chest wall. The simulated coarse crackle sounds were low pitched, with a high amplitude and long duration. The total duration was greater than 10 ms. However, for a lower frequency carrier (approximately 50 Hz), the fundamental frequency component was filtered out. Therefore, the second harmonic component of the lower frequency carrier, i.e., the fine crackle, penetrated the chest wall. Consequently, it is very possible that the normal lung sounds may contain many crackle-shaped waves with very small amplitudes because of the filtering effects of the chest wall, environment noises, electric devices, stethoscopes, and human ears, the small crackles disappear in the auscultations. In addition, our study pointed out that some unknown crackles of the very low frequency under the bandwidth of the human ears cannot penetrate the airways and be detected by medical doctors. Therefore, it might be necessary to focus advanced electronic instrumentation on them in order to analyse their possible characteristics for diagnosis and treatment of the respiration system.

Źródło:

Archives of Acoustics; 2021, 46, 2; 289-300
0137-5075

Pojawia się w:

Archives of Acoustics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 7.

Tytuł:

Pilot Based MMSE Channel Estimation for Spatial Modulated OFDM Systems

Autorzy:

Soman, Anetha Mary
Nakkeeran, R.
Shinu, Mathew John

Powiązania:

https://bibliotekanauki.pl/articles/2055222.pdf

Data publikacji:

2021

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

MIMO
multicarrier modulation
spatial modulation
channel estimation
channel model
interpolation

Opis:

Due to the multifold growth in demands of multimedia services and mobile data, the request for increased channel capacity in mobile and wireless communication has been quickly increasing. Developing a wireless system with more spectral efficiency under varying channel condition is a key challenge to provide more bit rates with limited spectrum. Multiple Input Multiple Output(MIMO) system with Orthogonal Frequency Division Multiplexing (OFDM) gives higher gain by using the direct and the reflected signals, thus facilitating the transmission at high data rate. An integration of Spatial Modulation (SM) with OFDM (SM OFDM) is a newly evolved transmission technique and has been suggested as a replacement for MIMO -OFDM transmission. In practical scenarios, channel estimation is significant for detecting transmitted data coherently. This paper proposes pilot based, Minimum Mean Square Error (MMSE) channel estimation for the SM OFDM communication system. We have focused on analyzing Symbol Error Rate (SER) and Mean Square error (MSE) under Rayleigh channel employing International Telecommunication Union (ITU) specified Vehicular model of Pilot based MMSE channel estimator using windowed Discrete Fourier Transform (DFT) and MMSE weighting function. Simulation output shows that proposed estimator’s SER performance lies close to that of the MMSE optimal estimator in minimizing aliasing error and suppressing channel noise by using frequency domain data windowing and time domain weighting function. Usage of the Hanning window eliminates error floor and has a compact side lobe level compared to Hamming window and Rectangular window. Hanning window has a larger MSE at low Signal to Noise Ratio (SNR) values and decreases with high SNR values. It is concluded that data windowing technique can minimize the side lobe level and accordingly minimize channel estimation error when interpolation is done. MMSE weighting suppresses channel noise and improves estimation performance. Since Inverse Discrete Fourier Transform(IDFT)/DFT transforms can be implemented with fast algorithms Inverse Fast Fourier Transform( IFFT)/Fast Fourier Transform(FFT) computational complexity can be remarkably reduced.

Źródło:

International Journal of Electronics and Telecommunications; 2021, 67, 4; 685--691
2300-1933

Pojawia się w:

International Journal of Electronics and Telecommunications

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 8.

Tytuł:

Digital vector modulator with diagnostic circuit for particle accelerator

Autorzy:

Tarnowski, S.
Piotrowski, A.

Powiązania:

https://bibliotekanauki.pl/articles/397924.pdf

Data publikacji:

2010

Wydawca:

Politechnika Łódzka. Wydział Mikroelektroniki i Informatyki

Tematy:

modulacja wektorowa
modulacja cyfrowa
diagnostyka
vector modulation
digital modulation
diagnostics

Opis:

Modern particle accelerators[8] have very strict requirements for controlling signal. To generate signal controlling field in cavities there is a possibility to use digital vector modulator and analog upconverter[6]. Hardware circuit consists of FPGA device, digital to analog converter and low pass filter. For experiments there is also a need to design and develop measurement circuit. Same circuit could be used in final application as diagnostics module. This enables an option for constant long term measurement and fault detection. This paper presents construction of such module.

Źródło:

International Journal of Microelectronics and Computer Science; 2010, 1, 1; 85-88
2080-8755
2353-9607

Pojawia się w:

International Journal of Microelectronics and Computer Science

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 9.

Tytuł:

Experimental research of the AMWG algorithm for assessing amplitude modulation in wind turbine noise

Autorzy:

Czapla, Marcjanna
Wszołek, Tadeusz

Powiązania:

https://bibliotekanauki.pl/articles/24202008.pdf

Data publikacji:

2022

Wydawca:

Politechnika Poznańska. Instytut Mechaniki Stosowanej

Tematy:

wind turbine noise
amplitude modulation
modulation depth
modulation frequency
hałas turbin wiatrowych
modulacja amplitudy
głębokość modulacji
częstotliwość modulacji

Opis:

The operation of a wind turbine (WT) is characterized by fluctuations in sound pressure amplitude associated with the passage of the propeller blade through the tower. Amplitude Modulation (AM) is one of the factors that contributes to the increased annoyance of wind turbine noise. The phenomenon of AM is currently the subject of research in many research centers around the world in the context of a parametric assessment of its impact on annoyance. Despite the development of many methods to measure the AM of a WT noise, there is no commonly accepted method. This paper discusses the most crucial factors that stimulate the phenomenon of AM and the implementation in the MATLAB environment of the algorithm to find the frequency and depth of AM proposed by the Amplitude Modulation Working Group (AMWG). The results of verification of the developed algorithm as well as the measurement results of the frequency and depth of modulation for two measurement samples of a 2 MW wind turbine are presented.

Źródło:

Vibrations in Physical Systems; 2022, 33, 3; art. no. 2022317
0860-6897

Pojawia się w:

Vibrations in Physical Systems

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 10.

Tytuł:

The diagnosis of onboard generators (alternators)

Autorzy:

Gębura, A.
Radoń, T.

Powiązania:

https://bibliotekanauki.pl/articles/258804.pdf

Data publikacji:

2009

Wydawca:

Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa

Tematy:

technical diagnostics
frequency modulation

Opis:

In the paper selected problems related to diagnostics of onboard generators and alternators fitted with control systems are discussed. Problems refer to commutator generators and synchronous single- and threephase alternators. Special attention is paid to commutation effects. Results of incorrectness and possibility to detect them are discussed. There are also discussed effects associated with changes in a character of pulsation, which occur during shortings or insulation clearances in rotor or stator wiring. Possibility of diagnosis of generator’s or alternator’s parts by means of analysis of pulsation component parameters is indicated. In the case of alternators a number of diagnostic methods based on observation of changes in shape of voltage or frequency modulation, is discussed. This allows to detect many mechanical or electrical faults of generators, alternators or their control systems.

Źródło:

Polish Maritime Research; 2009, 3; 36-40
1233-2585

Pojawia się w:

Polish Maritime Research

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 11.

Tytuł:

Recognition of narrowband radio signals using autoregressive models and pattern comparison approach

Autorzy:

Łopatka, J.

Powiązania:

https://bibliotekanauki.pl/articles/308156.pdf

Data publikacji:

2002

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

signal models
modulation recognition

Opis:

This paper presents an improved spectral recognition method for digitally modulated radio signals. It is based on a signal autoregressive (AR) model. Model poles are used as signal features for neural network based on recognition process. To reduce an influence of the signal noise and distortions introduced by the digital receiver, a nonlinear Z plane transformation is proposed.

Źródło:

Journal of Telecommunications and Information Technology; 2002, 1; 56-59
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 12.

Tytuł:

Fuzzy logic classifier for radio signals recognition

Autorzy:

Łopatka, J.
Pędzisz, M.

Powiązania:

https://bibliotekanauki.pl/articles/308362.pdf

Data publikacji:

2001

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

modulation recognition
fuzzy logic

Opis:

This paper presents a new digital modulation recognition algorithm for classifying baseband signals in the presence of additive white Gaussian noise. Elaborated classification technique uses various statistical moments of the signal amplitude, phase and frequency applied to the fuzzy classifier. Classification results are given and it is found that the technique performs well at low SNR. The benefits of this technique are that it is simple to implement, has generalization property and requires no apriori knowledge of the SNR, carrier phase or baud rate of the signal for classification.

Źródło:

Journal of Telecommunications and Information Technology; 2001, 2; 31-34
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 13.

Tytuł:

Mодуляция как переводческая трансформация
Modulation as a translation transformation

Autorzy:

Гочев (Gochev), Гочо (Gocho)

Powiązania:

https://bibliotekanauki.pl/articles/967812.pdf

Data publikacji:

2012

Wydawca:

Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego

Tematy:

translation
modulation
translation transformation

Opis:

Modulation is a process which involves changing the informative parameters of the source language word. The concrete manifestation of this transformation is the act of replacing the source language words with equivalents unrelated to the systematic regularities of lexis and as such they might a) have relevance to these regularities, i.e. the equivalent exhibits a semantic or associative link with the source language word, or b) not have relevance to these regularities, i.e. the equivalent does not exhibit a semantic or associative link with the source language word, but its use is justified by extralinguistic factors (e.g. logical reasoning or a concrete situation).

Źródło:

Acta Universitatis Lodziensis. Folia Linguistica Rossica; 2012, 08; 43-49
1731-8025
2353-9623

Pojawia się w:

Acta Universitatis Lodziensis. Folia Linguistica Rossica

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 14.

Tytuł:

Symulacyjna aproksymacja charakterystyki przetwarzania flickermetru dla modulacji amplitudy i częstotliwości
Simulation approximation of flickermeter conversion characteristic for amplitude and frequency modulation

Autorzy:

Majchrzak, J.
Wiczyński, G.

Powiązania:

https://bibliotekanauki.pl/articles/156720.pdf

Data publikacji:

2007

Wydawca:

Stowarzyszenie Inżynierów i Techników Mechaników Polskich

Tematy:

flikermetr
wskaźnik Pst
modulacja AM
modulacja FM
flickermeter
Pst indicator
FM modulation
AM modulation

Opis:

Flickermetr jest potoczną nazwą układu pomiarowego przeznaczonego do oceny odczuwania migotania światła wywołanego wahaniami napięcia. Normatywna charakterystyka przetwarzania flickermetru jest określona mało licznym zestawem par wartości głębokości modulacji i częstotliwości harmonicznego lub prostokątnego sygnału modulującego dla modulacji amplitudy napięcia wejściowego. Wielkością wyjściową jest wskaźnik krótkookresowego migotania światła Pst. W celu dokładniejszego odtworzenia charakterystyki przeprowadzono badania symulacyjne dla modulacji amplitudy i częstotliwości napięcia wejściowego. Zamodelowano elementy toru normatywnego flickermetru, tj. filtry o stałych parametrach zapisane w postaci operatorowej wraz z multiplikatorami, narzędzie do wyznaczania wartości Pst, źródło sygnału testowego oraz narzędzia do prezentacji i archiwizacji wyników badań. W artykule przedstawiono wyniki badań symulacyjnych zrealizowanych przy pomocy standardowych przebiegów testowych dla modulacji amplitudy AM oraz częstotliwości FM. Zamieszczono specyficzne fragmenty wyznaczonych charakterystyk oraz przykład wpływu ograniczenia pasma napięcia wejściowego na wynik pomiaru flickermetrem dla modulacji FM. Wyniki symulacji porównano z nielicznymi punktami normatywnymi. Sformułowano uwagi przydatne w diagnostyce flickermetru.
Flickermeter is a measurement system for estimation of the disturbances coming from flickering of light caused by the fluctuations of voltage. The disturbances are described on the basis of values of short-term coefficient Pst and long-term coefficient Plt of light flickers. The flickermeter system considered in the paper consists of two main components: a signal channel simulating perception processes in the chain: light source-eye-brain and a statistics module. Signal chains action is a map for bounded number of standard points of characteristic conversion. The simulation works with realization interpolation and extrapolation standard points was advisable. Presented results come from tests for AM and FM modulation.Before using the results, the verification was necessary. The conclusions formulated are useful in flickermeter's diagnostic.

Źródło:

Pomiary Automatyka Kontrola; 2007, R. 53, nr 9 bis, 9 bis; 629-632
0032-4140

Pojawia się w:

Pomiary Automatyka Kontrola

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 15.

Tytuł:

Chaotic-based Orthogonal Frequency Division Multiplexing with Index Modulation

Autorzy:

Hussien, Sura H.
Abdullah, Hamsa A.

Powiązania:

https://bibliotekanauki.pl/articles/2174449.pdf

Data publikacji:

2022

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

AWGN
chaos communications
DCSK
index modulation

Opis:

Orthogonal frequency division multiplexing with index modulation (OFDM-IM), stands out among conventional communication technologies, as it uses the indices of the available transmit entities. Thanks to such an approach, it offers a novel method for the transmission of extra data bits. Recent years have seen a great interest in chaos-based communications. The spectrum-spreading signals used in chaotic signal modulation technologies are orthogonal to the existing mixed signals. This paper presents how well a non-coherent differential chaos shift keying communication system performs across an AWGN. Different types of detection methods are simulated, bit error rate and power spectral density are calculated and then compared with standard OFDM with index modulation. The results of simulations concerning the performance of a DCSK system, adding to the security of the proposed solution and offering a comparable bit error rate performance, are presented in the paper as well.

Źródło:

Journal of Telecommunications and Information Technology; 2022, 4; 33--38
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 16.

Tytuł:

Modified Topology and Modulation Technique for Z-Source Neutral-Point Clamped Inverter

Autorzy:

Akbari, Ehsan
Zishan, Farhad

Powiązania:

https://bibliotekanauki.pl/articles/2175930.pdf

Data publikacji:

2022

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

modulation
optimization
multilevel inverter
MZS-NPC

Opis:

The impedance network makes it possible to increase and decrease the voltage, which is not available in normal inverters (voltage and current sources).This paper presents a modified topology and modulation technique for a three-phase Modified Z-Source Neutral-Point Clamped (MZS-NPC) inverter. A modulation scheme for the proposed topology is designed based on maximum gain control method to achieve the maximum voltage gain by simple implementation and balancing the neutral point voltage of the dc link. In order to supply the desired voltage to the critical load in an islanded micro-grid, a closed-loop ac voltage controller is realized in fuel cell or photovoltaic applications based on the proposed inverter. The ability to reinforce and validity of topology operations and modulation techniques has been demonstrated by simulation. It should be noted that the simulations are implemented in MATLAB / Simulink software.

Źródło:

Power Electronics and Drives; 2022, 7, 42; 210--226
2451-0262
2543-4292

Pojawia się w:

Power Electronics and Drives

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 17.

Tytuł:

Proposed Methodology for the Annoyance Penalty of Amplitude Modulated Wind Turbine Noise

Autorzy:

Makarewicz, Rufin

Powiązania:

https://bibliotekanauki.pl/articles/2141682.pdf

Data publikacji:

2022

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

annoyance
wind turbine noise
amplitude modulation.

Opis:

Amplitude modulation increases the annoyance caused by wind turbine noise. One gets the improved annoyance when a penalty is added to the measured or calculated time-average sound level. The amplitude modulated wind turbine noise consists of pulses. Each of them could be characterized by the short time-average sound level and the modulation depth. The latter determines the pulse penalty. This paper shows how to calculate the improved annoyance of amplitude modulated wind turbine noise, when the short time-average sound level and the penalty for each pulse are known. A special case of identical pulses is discussed. The proposed methodology needs to be tested by research.

Źródło:

Archives of Acoustics; 2022, 47, 1; 125-128
0137-5075

Pojawia się w:

Archives of Acoustics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 18.

Tytuł:

PLD we wspomaganiu demodulacji drgań maszyn
PLD aided demodulation of machine vibrations

Autorzy:

Krzyworzeka, P.
Cioch, W.

Powiązania:

https://bibliotekanauki.pl/articles/327694.pdf

Data publikacji:

2006

Wydawca:

Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN

Tematy:

diagnostyka
modulacja
synchronizm
diagnostic
modulation
synchronism

Opis:

W diagnozowaniu maszyn, dla których realizacja celu podstawowego obejmuje powtarzanie sekwencji zdarzeń podobnych, można wykorzystać PLD dla wspomagania demodulacji sygnału drganiowego w niestacjonarnych stanach pracy maszyny. Zastosowana transformacja skali czasu powoduje wyrównanie długości dyskretnej reprezentacji kolejnych cykli i zbliża rezultat do sygnału stacjonarnego zachowując modulacje AM i PM. Nawet zastosowanie demodulatorów asynchronicznych prowadzi wówczas do wyraźnego zmniejszenia uchybu obciążenia rezultatu. zmniejszenia obciążeń wyników. Przedstawiono rezultaty badań dla sygnałów modelowych i rzeczywistych.
This paper is concerned with the PLD (Procedure of Linear Decimation) aided output biasing elimination which takes into account some particularities of rotating machinery signal modulation. Rotating speed fluctuations or trend affect demodulation procedure due to nonlinear trend of carrier frequency. The proposed time scale transformation, denoted as PLD, aims to reduce demodulation error by employing linear approximation of carrier cycle short-term changes. Some examples of simulated and real signal asynchronous demodulations are also discussed hereby.

Źródło:

Diagnostyka; 2006, 2(38); 199-210
1641-6414
2449-5220

Pojawia się w:

Diagnostyka

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 19.

Tytuł:

Decreasing of error probability in telecommunication access networks by using amplitude modulation of many components

Autorzy:

Klymash, M.
Gorbatyy, I.

Powiązania:

https://bibliotekanauki.pl/articles/411412.pdf

Data publikacji:

2014

Wydawca:

Polska Akademia Nauk. Oddział w Lublinie PAN

Tematy:

telecommunication access network
data transmission
bit error rate
quadrature amplitude modulation
amplitude modulation of many components

Opis:

The paper addresses the research of data transmission technologies in telecommunication access networks. These networks are characterized by limited bandwidth and are suitable for high speed data transmission. Particular attention is paid on the data transmission technologies in telecommunication access networks based on symmetrical telecommunication lines. Paper proposes the method of adaptive data transmission in telecommunication access networks using amplitude modulation of many components. The results of mathematical modeling are presented, which allows estimating the bit error rate decrease in telecommunication access networks using this method.

Źródło:

ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes; 2014, 3, 1; 55-60
2084-5715

Pojawia się w:

ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 20.

Tytuł:

The effect of space vector modulation algorithm on characteristics of three-phase voltage inverter for drives of optical telescopes

Autorzy:

Tomasov, V.
Usoltsev, A.
Zolov, P.
Gribanov, P.

Powiązania:

https://bibliotekanauki.pl/articles/200303.pdf

Data publikacji:

2017

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

multilevel inverter
space vector modulation
modulation algorithm
current ripple
precision AC drive
inwerter
modulacja
napęd AC

Opis:

The effect of space vector modulation algorithm on magnitude of current vector ripples was considered on the mathematical model of a three-level three-phase voltage inverter with symmetric active inductive load. Limitations on the use of such inverters as a power supply for precision drive of optical telescopes were specified.

Źródło:

Bulletin of the Polish Academy of Sciences. Technical Sciences; 2017, 65, 5; 629-637
0239-7528

Pojawia się w:

Bulletin of the Polish Academy of Sciences. Technical Sciences

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 21.

Tytuł:

Modulation of Doxorubicin Cytotoxicity by Isoliquiritin and Cynarin Combination on Different Cancer Cell Lines

Autorzy:

Al-AdamI, Salat G.
Al-Khateeb, EKBAL H.
NUMAN, NAWFAL A.
ABBAS, Mannal M.
Tawfiq, FATIMA A.
Shakya, Ashok K.

Powiązania:

https://bibliotekanauki.pl/articles/895633.pdf

Data publikacji:

2020-06-29

Wydawca:

Polskie Towarzystwo Farmaceutyczne

Tematy:

cytotoxicity
doxorubicin
cancer cells
Modulation
Cynarin
Isoliquiritin

Opis:

Natural polyphenolic compounds produced by plant exhibit many pharmacological effects including antioxidant, chemopreventive as well as anticancer properties. This study was conducted to investigate the effect of cynarin ( from Artichoke, Cynara scolymus) and isoliquiritin (from Licorice, Glycyrrhiza uralensis) on doxorubicin (positive control) cytotoxicity in different cell lines including normal (Fibroblasts MCR-5 and Myoblasts H9c2) and cancer (colorectal HCT-116 and hepatocellular HEP-G2) cell lines. The cytotoxic effect of doxorubicin, isoliquiritin and cynarin alone or in different combination was studied on cancer cell lines as well as normal cell lines. The results obtained indicated that both cynarin and isoliquiritin enhance the cytotoxicity of doxorubicin. Both cynarin and isoliquiritin also reduce the cardiotoxicity of doxorubicin on normal cardiac cell lines. The combination of the three compounds (cynarin, isoliquiritin and doxorubicin) result in decrease the cytotoxicity of doxorubicin, which may indicate the presence of interaction and/or antagonism effect between cynarin and isoliquiritin. Cynarin was found to enhance the growth of (HCT-116 and HEP-G2) this might suggest avoiding use of Artichoke in subjects’ susceptibility for these cancers. All results were evaluated using statistical path and showed significant findings. The mechanism of enhanced doxorubicin’s cytotoxicity by cynarin or isoliquiritin also require further investigation to explain the increasing and/or the decreasing effect of these polyphenolic compounds on cytotoxicity of doxorubicin. The current finding can help to start with safe minimum dose of two or three combination of compounds in the context of clinical trials and practice.

Źródło:

Acta Poloniae Pharmaceutica - Drug Research; 2020, 77, 3; 475-484
0001-6837
2353-5288

Pojawia się w:

Acta Poloniae Pharmaceutica - Drug Research

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 22.

Tytuł:

Performance of Non-Binary LDPC Codes for Next Generation Mobile Systems

Autorzy:

Gierszal, H.
Hołubowicz, W.
Kiedrowski, Ł.
Flizikowski, A.

Powiązania:

https://bibliotekanauki.pl/articles/226906.pdf

Data publikacji:

2010

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

LDPC
mobile systems
modulation schemes
non-binary

Opis:

A new family of non-binary LDPC is presented that are based on a finite field GF(64). They may be successfully implemented in single-carrier and OFDM transmission system. Results prove that DAVINCI codes allow for improving the system performance and may be considered to be applied in the future mobile system.

Źródło:

International Journal of Electronics and Telecommunications; 2010, 56, 2; 111-116
2300-1933

Pojawia się w:

International Journal of Electronics and Telecommunications

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 23.

Tytuł:

An Energy Efficient QAM Modulation with Multidimensional Signal Constellation

Autorzy:

Markiewicz, T. G.

Powiązania:

https://bibliotekanauki.pl/articles/227049.pdf

Data publikacji:

2016

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

communication system
QAM modulation
lattice
multidimensional constellations

Opis:

Packing constellations points in higher dimensions, the concept of multidimensional modulation exploits the idea drawn from geometry for searching dense sphere packings in a given dimension, utilising it to minimise the average energy of the underlying constellations. The following work analyses the impact of spherical shaping of the constellations bound instead of the traditional, hyper-cubical bound. Balanced constellation schemes are obtained with the N-dimensional simplex merging algorithm. The performance of constellations of dimensions 2, 4 and 6 is compared to the performance of QAM modulations of equivalent throughputs in the sense of bits transmitted per complex (twodimensional) symbols. The considered constellations give an approximately 0.7 dB to 1 dB gain in terms of BER over a standard QAM modulation.

Źródło:

International Journal of Electronics and Telecommunications; 2016, 62, 2; 159-165
2300-1933

Pojawia się w:

International Journal of Electronics and Telecommunications

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 24.

Tytuł:

Modeling of the inverse base width modulation effect in HBT transistor with graded SiGe base

Autorzy:

Zaręba, A.
Łukasiak, L.
Jakubowski, A.

Powiązania:

https://bibliotekanauki.pl/articles/308625.pdf

Data publikacji:

2007

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

heterojunction bipolar transistor
SiGe
base width modulation

Opis:

A model of the position of the edge of emitter-base junction in the base and collector current pre-exponential ideality factor in HBT transistor with a SiGe base is presented. The model is valid for transistors with nonuniform profiles of doping and Ge content. The importance of taking into account the dependence of the effective density of states in SiGe on local Ge content and that of electron diffusion coefficient in SiGe on drift field for modeling accuracy is studied.

Źródło:

Journal of Telecommunications and Information Technology; 2007, 3; 88-92
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 25.

Tytuł:

The simple analysis method of nonlinear frequency distortions in FMCW radar

Autorzy:

Kulpa, K. S.
Wojtkiewicz, A.
Nałęcz, M.
Misiurewicz, J.

Powiązania:

https://bibliotekanauki.pl/articles/309080.pdf

Data publikacji:

2001

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

radar
nonlinear frequency distortions
linear frequency modulation

Opis:

The paper presents a simple method for estimating nonlinear frequency distortions of linear frequency modulated (LFM) signals used in FMCW radars. This method, derived from the polynomial model of the nonlinear FM signal phase, is based on finding the maximum of two-dimensional chirp-like transform of the IF video signal. The IF signal is obtained by mixing transmitted FM signal with its delayed copy. Using suggested transform we show that the presented method is able to detect and classify signal distortions.

Źródło:

Journal of Telecommunications and Information Technology; 2001, 4; 26-29
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 26.

Tytuł:

Evaluation of potential dangers of Mobile Telecommunication frequencies and modulations

Autorzy:

Bamisaye, A. J.

Powiązania:

https://bibliotekanauki.pl/articles/307594.pdf

Data publikacji:

2013

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

electromagnetic fields
frequency
health
mobile communication
modulation

Opis:

Mobile Telecommunication is one of the fastest growing technologies in the world. The effects of its high frequencies and complex modulations to the exposed population are considered in this paper. Experimental studies examining a variety of effects on all levels of the organism, ranging from effects on single cells to effects which manifest themselves as reactions of the entire body, there have been a number of epidemiological studies in order to establish the possible causal correlations between higher exposures to HF EMFs. Recommendations on the reduction of the effects of EMFs of Mobile Telecommunication on humans was presented.

Źródło:

Journal of Telecommunications and Information Technology; 2013, 2; 30-34
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 27.

Tytuł:

The sensitivity of vegetation in the lower Tigris basin landscapes to regional and global climate variability

Autorzy:

Alhumaima, Ali S.
Abdullaev, Sanjar M.

Powiązania:

https://bibliotekanauki.pl/articles/35516789.pdf

Data publikacji:

2021

Wydawca:

Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie

Tematy:

climate variability
vegetation
global modulation
precipitation
temperature

Opis:

This study investigates the lower Tigris basin’s the normalized difference vegetation index (NDVI) sensitivity in 2000–2016 to regional climate variability reflected by the monthly precipitation and temperature time series of seven global datasets as well as to four global circulation indices. To examine the effect of climate variability on the different ecosystems, the study area has been classified into 10 smaller natural and anthropogenic landscapes based on landforms and land cover patterns. The preliminary analysis showed that the maximum biological productivity reflected by the NDVI of March and April has the highest correlation (0.5–0.8) to the same cumulative amounts of October–March period total precipitation and January–March period mean temperatures according to all datasets. In addition, this article showed there is a correlation between landscapes’ NDVI and global modulation represented by the September–February state of El Nińo-Southern Oscillation (ENSO) (0.55–0.70) and December state of the dipole mode index (DMI) (0.35–0.72). The significant differences in the original precipitation and temperature levels according to the different datasets have urged the use of normalized time series: z-score of temperatures and analogous six-months the standardized precipitation index (SPI). However, the multiple correlation analysis showed that using ERA-

Źródło:

Scientific Review Engineering and Environmental Sciences; 2021, 30, 1; 159-170
1732-9353

Pojawia się w:

Scientific Review Engineering and Environmental Sciences

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 28.

Tytuł:

Uniwersalny modulator wektorowy syntezowalny do układu FPGA
Universal vector modulator for FPGA device

Autorzy:

Tarnowski, S.
Piotrowski, A.

Powiązania:

https://bibliotekanauki.pl/articles/156310.pdf

Data publikacji:

2008

Wydawca:

Stowarzyszenie Inżynierów i Techników Mechaników Polskich

Tematy:

modulacja wektorowa
transformata Fouriera
FPGA
vector modulation
FFT

Opis:

Przedstawiony artykuł prezentuje wykorzystanie syntezowalnego modulatora wektorowego opisanego w języku wysokiego poziomu. Zastosowanie reprogramowalnego układu logicznego w miejsce układu analogowego umożliwia poprawienie jakości sygnału przez wyeliminowanie wad rozwiązania analogowego. Przykładowym zastosowaniem prezentowanego rozwiązania jest sterowanie polem przyśpieszającym akceleratorów liniowych, jednak może być on wykorzystane w telekomunikacji jako modulator wektorowy.
Using typical analog vector modulator (Fig. 1) in particle accelerator control emphases technical inaccuracies (Fig. 2). There is a possibility of using FPGA device to calculate samples of signal for digital-to-analog converter from vector value. Using this solution is possible to replace analog vector modulator with digital circuit, or even integrate it with controlling device inside one FPGA. FPGAs have not enough speed efficiency for direct calculation of samples. This paper presents solution for sample switching and precalculation of sample values based on inverse Fourier transform. Shown solution consists of multiple parallel shifters (Fig. 3, 4) which can operate at very high frequency.

Źródło:

Pomiary Automatyka Kontrola; 2008, R. 54, nr 8, 8; 582-584
0032-4140

Pojawia się w:

Pomiary Automatyka Kontrola

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 29.

Tytuł:

Phase Shifted Pulse Height Modulated Motor Control for Multiply Actuated Joints to Optimize Operating Characteristics

Autorzy:

Siedel, T.
Bethge, S.
Hild, M.

Powiązania:

https://bibliotekanauki.pl/articles/385220.pdf

Data publikacji:

2016

Wydawca:

Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów

Tematy:

multiple actuators
model-free
frictrion compensation
pulse modulation

Opis:

In this article, we propose two model free control schemes that are based on pulse height modulation using low frequencies with the goal to compensate normal friction effects in drive trains that negatively influence the performance of e.g. a standard PID controller. The first control scheme uses pulse height modulation to especially compensate stick slip effects but increases vibration and noise in the drive train. To reduce such side effects a modified phase shifed pulse height control scheme based on multiple actuated joints is introduced. Both control schemes are compared with a standard linear controller as reference and evaluated by using six quality criteria.

Źródło:

Journal of Automation Mobile Robotics and Intelligent Systems; 2016, 10, 2; 15-24
1897-8649
2080-2145

Pojawia się w:

Journal of Automation Mobile Robotics and Intelligent Systems

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 30.

Tytuł:

Broadband power electronics controlled current source with analogue control section and output stage based on GaN transistors

Autorzy:

Gwóźdź, M.

Powiązania:

https://bibliotekanauki.pl/articles/377021.pdf

Data publikacji:

2017

Wydawca:

Politechnika Poznańska. Wydawnictwo Politechniki Poznańskiej

Tematy:

converter control
GaN transistor
interleaved technique
pulse modulation

Opis:

The paper presents the conception of the power electronics controlled current source based on the sigma–delta modulator (SDM). Due to very high frequency of the SDM output bit stream, in the power stage of inverter the gallium-nitride (GaN) transistors are used. In these circumstances even efficient DSPs are unable, due to limitation of its pass–band of the control path, to obtain right parameters of the output current regulator. So, the regulator is done in the fully analogue manner. As result of these the value of distortions of the inverter output current is much lower, compared to the typical, PWM based, solutions. This benefit is not paid significantly by increase in the system complexity. In work the converter operation basics and results of its simulation model studies are presented.

Źródło:

Poznan University of Technology Academic Journals. Electrical Engineering; 2017, 91; 55-61
1897-0737

Pojawia się w:

Poznan University of Technology Academic Journals. Electrical Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 31.

Tytuł:

A model of OFDM based maritime VHF communication system for data exchange

Autorzy:

Valčić, S.
Pogány, T.
Mrak, Z.

Powiązania:

https://bibliotekanauki.pl/articles/260386.pdf

Data publikacji:

2018

Wydawca:

Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa

Tematy:

maritime VHF communications
OFDM modulation
AWGN
SNR
BER

Opis:

In the maritime Very High Frequency (VHF) band, there are no systems for transmitting large amounts of data. Therefore, it is necessary to develop new systems that would modernize the Global Maritime Distress and Safety System (GMDSS), significantly relieve the Automatic Identification System’s (AIS) communication channels, and set guidelines for the development of communication infrastructure of the e-Navigation. In line with this, analytical and simulation models of the maritime VHF data transmission communication system using Orthogonal Frequency Division Multiplexing (OFDM) modulation are worked out in this paper. The achieved data rate, the spectral efficiency and the bit error rate (BER) represent validation parameters on which the results of the analytical and simulation models are evaluated. It is concluded that the application of the digital OFDM modulation in the maritime VHF band may improve the GMDSS system by achieving higher data rates compared to the current terrestrial mandatory systems for data exchange, i.e. Digital Selective Calling (DSC) and AIS.

Źródło:

Polish Maritime Research; 2018, 2; 27-36
1233-2585

Pojawia się w:

Polish Maritime Research

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 32.

Tytuł:

Laser frequency counting and frequency modulation width measurement from a FFT signal

Autorzy:

Křen, P.

Powiązania:

https://bibliotekanauki.pl/articles/221880.pdf

Data publikacji:

2012

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

laser
modulation width
frequency measurement
optical frequency synthesizer

Opis:

A new method of optical frequency beat counting based on fast Fourier transform (FFT) analysis is described. Signals with a worse signal-to-noise ratio can be counted correctly comparing to the conventional counting method of detecting each period separately. The systematic error of FFT counting below 10 Hz is demonstrated and can be decreased. Additionally the modulation width of a frequency-stabilized laser with high frequency modulation index can be simultaneously measured during a carrier frequency measurement against an optical frequency synthesizer or other laser.

Źródło:

Metrology and Measurement Systems; 2012, 19, 3; 565-572
0860-8229

Pojawia się w:

Metrology and Measurement Systems

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 33.

Tytuł:

Optical gradient force of cosh-Gaussian with sine-azimuthal and half-space phase modulation

Autorzy:

Fu, R.
Gao, X.
Shen, H.
Xin, Q
Lu, X.
Guo, L.

Powiązania:

https://bibliotekanauki.pl/articles/173789.pdf

Data publikacji:

2013

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

optical gradient force
cosh-Gaussian beams
wavefront modulation

Opis:

The optical gradient force distributions in focal plane of cosh-Gaussian beams with sine-azimuthal variation wavefront and half space phase modulation were investigated. Results show that optical gradient force distributions can be affected considerably by the phase retardation of half-space phase modulation, of a phase parameter that indicates the phase change frequency on an increasing azimuthal angle, and beam parameters in cosh terms of the incident beams. Many gradient force patterns occur, including cross-shape, multiple optical trap arrays, multiple-trap wheel, and many kinds of gradient force lines and curves. Symmetry of the whole gradient force pattern can also be altered remarkably. Above results may find wide applications in optical trapping systems.

Źródło:

Optica Applicata; 2013, 43, 4; 719-730
0078-5466
1899-7015

Pojawia się w:

Optica Applicata

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 34.

Tytuł:

Focus shaping of the radially polarized Bessel–Gauss beam with a sine-azimuthal variation wavefront

Autorzy:

Gao, X
Zhang, D.
Mei, T.
Fu, R.
Zhuang, S.

Powiązania:

https://bibliotekanauki.pl/articles/174283.pdf

Data publikacji:

2013

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

Bessel-Gauss beam
wavefront modulation
vector diffraction theory

Opis:

Focusing properties of the radially polarized Bessel–Gauss beam with a sine-azimuthal variation wavefront was investigated by the vector diffraction theory. The wavefront distribution is the sine function of the azimuthal angle with one phase parameter that indicates the phase change frequency. Results show that the focal pattern can be altered by the phase parameter, and many novel focal patterns may occur, such as multiple dark-foci focal pattern, crescent shape, and wheel shape. For case of a higher phase beam, the whole focal pattern turns on a symmetric wheel shape with multiple reduplicate intensity elements. When the phase parameter is an odd number, the number of reduplicate elements equals the phase parameter, while when the phase parameter is an even number, the number of reduplicate elements is two times the phase parameter. In addition, the effect of the phase parameter on the focal pattern is more considerable than that of the beam parameter under low numerical aperture. Under higher numerical aperture, the effect of the beam parameter on the focal pattern gets stronger.

Źródło:

Optica Applicata; 2013, 43, 3; 567-582
0078-5466
1899-7015

Pojawia się w:

Optica Applicata

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 35.

Tytuł:

Performance Enhancement of Chaotic Error Correction Coding Using Consecutive Sequences

Autorzy:

Sahar, Asaad H.
Abdullah, Hikmat N.
Saed, Thamir R.

Powiązania:

https://bibliotekanauki.pl/articles/24200739.pdf

Data publikacji:

2023

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

chaos communication
DCSK modulation
error correction
suboptimal receiver

Opis:

The use of chaotic dynamics for error correction is the subject of extensive research, as the approach allows to avoid the use of redundant data. This work proposes a new technique for non-coherent chaos communications for modifying error-correction depending on chaotic dynamics. In the proposed system, there are two consecutive sequences created from a comparable chaotic map, with the second series being created as the latest value of the initial one. Generation of a sequential chaotic sequence with a comparable chaotic dynamic delivers additional information to the receiver, allowing it to appropriately recover information and, hence, facilitate the receiver’s bit-error performance. For error correction and for detecting the symbol that is transmitted, a suboptimal technique based on the nearest distance between chaotic map trajectories over the n-dimensional sequence received is utilized. Simulation results show that the proposed error correction approach improves Eb/N0 as the dimension of the trajectory map increases, indicating that the method improves overall error correction performance. With the dimension of 4, a gain of 0.8 dB in Eb/N0 is achieved compared with an approach without any error-correcting schemes, at the bit-error probability of 10−3.

Źródło:

Journal of Telecommunications and Information Technology; 2023, 2; 10--16
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 36.

Tytuł:

Study of all-optical logic XOR gate based on linear optical amplifier cross-gain modulation

Autorzy:

Li, X
Jin, J
Li, H
Zhang, Q

Powiązania:

https://bibliotekanauki.pl/articles/174514.pdf

Data publikacji:

2015

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

linear optical amplifier
cross-gain modulation
XOR gate

Opis:

All-optical logic is the key to future high speed and large capacity optical transmission, the realization of optical packet switching and optical computing, and it has a very profound influence on the development of future optical communication. A linear optical amplifier as a new type of semiconductor optical amplifier, which has a good gain characteristic, has better signal performance than a traditional semiconductor optical amplifier in the wavelength conversion. This article presents a numerical simulation model of all-optical logic XOR gate and its logic operation based on cross-gain modulation of linear optical amplifier, and has also completed some of the basic logic operations, including AND, OR, NOT operations.

Źródło:

Optica Applicata; 2015, 45, 4; 447-457
0078-5466
1899-7015

Pojawia się w:

Optica Applicata

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 37.

Tytuł:

Modulation index optimization for wavelength modulation spectroscopy

Autorzy:

Mohammadi, M. J.
Khorsandi, A.
Ghavami, S. S.

Powiązania:

https://bibliotekanauki.pl/articles/949416.pdf

Data publikacji:

2016

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

wavelength modulation spectroscopy
NIR laser spectroscopy
molecular spectroscopy

Opis:

In this work, the second-harmonic component of wavelength modulation spectroscopy is simulated for R(22) CO2 absorption line to investigate the effect of gas temperature and pressure on the modulation index. We found that the optimum value of modulation index, that is 2.2, is not affected by temperature but gas pressure will change the optimized modulation index. Specifically, when the gas pressure decreased to lower pressures of less than 100 mbar, the modulation index is also decreased and tended exponentially to about two. Accordingly, the optimum value of modulation index is recalculated for a range of CO2 gas pressures to establish a nearly zero pressure deviation in the spectroscopy of very low pressure samples.

Źródło:

Optica Applicata; 2016, 46, 4; 639-650
0078-5466
1899-7015

Pojawia się w:

Optica Applicata

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 38.

Tytuł:

An improved space vector modulation strategy for common-mode voltage reduction in matrix rectifier

Autorzy:

Liu, X.
Zhang, Q.
Hou, D.

Powiązania:

https://bibliotekanauki.pl/articles/950664.pdf

Data publikacji:

2014

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

matrix converter
space vector modulation
common-mode voltage

Opis:

The matrix rectifier modulated by the classical space vector modulation (SVM) strategy generates common-mode voltage (CMV). The high magnitude and high du/dt of the CMV causes serious problems such as motor damage, electromagnetic noise and many others. In this paper, an improved SVM strategy is proposed by replacing the zero vectors with suitable couple of active ones that substantially eliminate the CMV. Theoretical analysis proves that the proposed strategy can reduce the amplitude of the CMV to half of the original value. In addition, the quality of the input and output waveforms is not affected by extra active vectors. Simulation and experimental results demonstrate the feasibility and effectiveness of the proposed strategy are shown.

Źródło:

Archives of Electrical Engineering; 2014, 63, 1; 93-106
1427-4221
2300-2506

Pojawia się w:

Archives of Electrical Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 39.

Tytuł:

New Synchronization Method for Transmission Systems with Variable Length of Bits

Autorzy:

Godek, J.
Golański, R.
Kołodziej, J.
Stępień, J.

Powiązania:

https://bibliotekanauki.pl/articles/226590.pdf

Data publikacji:

2015

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

delta modulation
adaptation
non-uniform sampling
synchronization
codec

Opis:

Based on the Spartan 3E evaluation module, a flexible platform for the implementation of different algorithms for A/D conversion was developed. The aim of presented work was to improve the concept of the sampling rate adaptation to the input signal rate of change in terms of practical issues including synchronization of delta codecs. The new, original synchronization method, useful in systems dedicated for transmission of variable duration of bits was proposed and experimentally verified. Performed measures and observations have shown elimination of the synchronization lose phenomenon.

Źródło:

International Journal of Electronics and Telecommunications; 2015, 61, 1; 31-36
2300-1933

Pojawia się w:

International Journal of Electronics and Telecommunications

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 40.

Tytuł:

Impacts of modulation for direct payments in Hungary
Wpływ modulacji na bezposrednie płace na Węgrzech

Autorzy:

Vasary, M.
Molnar, J.
Zsolt, B.

Powiązania:

https://bibliotekanauki.pl/articles/868774.pdf

Data publikacji:

2013

Wydawca:

The Polish Association of Agricultural and Agribusiness Economists

Tematy:

modulation
direct payment
payment
subsidy redeployment
calculation
Hungary

Opis:

The redeployment of subsidies through modulation was a new element in the system of Hungarian agricultural support in the premium year of 2012. In harmony with EU principles, it has become possible (within Hungarian implementation) to create a system which enables the radical moderation of actual volumes of subsidy redeployment resulting from modulation. The basis of model calculations was created by the finalized data of ARDA about payments in the premium year of 2011. Following the running of calculations, it can be confirmed that the implementation of the Hungarian method has resulted in reduced payments only in the case of 2% of all farmers eligible for direct subsidies, and about 10% of those who are actually involved in payment reduction.
Nową częścią węgierskiego systemu wsparcia rolnictwa w roku składkowym 2012 było przegrupowanie dotacji poprzez modulację. Na Węgrzech możliwe stało się stworzenie systemu, który zgodnie z zasadami UE umożliwiał radykalne obniżenie aktualnej wysokości przegrupowania dotacji będącej wynikiem modulacji. Podstawą do obliczenia modelu były dane ARDA na temat wpłat za rok składkowy 2011. Można potwierdzić, że wprowadzenie węgierskiej metody skutkowało zmniejszeniem składek tylko w przypadku 2% wszystkich rolników, którym przysługują bezpośrednie dotacje i ok. 10% w przypadku tych, którzy rzeczywiście przyczyniają się do zmniejszenia składek.

Źródło:

Roczniki Naukowe Stowarzyszenia Ekonomistów Rolnictwa i Agrobiznesu; 2013, 15, 4
1508-3535
2450-7296

Pojawia się w:

Roczniki Naukowe Stowarzyszenia Ekonomistów Rolnictwa i Agrobiznesu

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 41.

Tytuł:

Impulsive Sound Detection Directly in Sigma-Delta Domain

Autorzy:

Miranda, I. D. dos S.
Lima, A. C. de C.

Powiązania:

https://bibliotekanauki.pl/articles/176966.pdf

Data publikacji:

2017

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

impulsive signal detection
sigma-delta modulation
discrete cosine transform

Opis:

Recent implementations of Sigma-Delta (ΣΔ) converters have achieved low cost, low power consumption, and high integration while maintaining resolution as high as in Nyquist-rate converters. However, its usage implies demodulating the source signal delivered from ΣΔ modulation to Pulse-Code Modulation (PCM) on a pre-processing stage. This work proposes an algorithm based on Discrete Cosine Transform for impulsive signal detection to be applied directly on a modulated ΣΔ bitstream, targeting to reduce computational cost in acoustic event detection applications such as gunshot recognition systems. From pre-recorded impulsive sounds in ΣΔ format, it has been shown that the new method presents a similar error rate in comparison with traditional energy-based approaches in PCM, meanwhile, it reduces significantly the number of operations per unit time.

Źródło:

Archives of Acoustics; 2017, 42, 2; 255-261
0137-5075

Pojawia się w:

Archives of Acoustics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 42.

Tytuł:

Conducted EMI mitigation in switched mode dc-dc converters by spread spectrum techniques

Autorzy:

Knitter, A.
Łuszcz, J.
Chrzan, P. J.

Powiązania:

https://bibliotekanauki.pl/articles/262735.pdf

Data publikacji:

2005

Wydawca:

Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

Tematy:

spread spectrum
carrier frequency modulation
EMI suppression
electromagnetic compatibility

Opis:

In this paper effectiveness of spread spectrum modulation techniques to the electromagnetic interference (EMI) suppression is investigated. Comparative evaluation of spread spectrum methods is reviewed and demonstrated with the aid of function generator and EMI receiver. Obtained results indicate advantageous features of random carrier frequency modulation (CFM), which results in more steady spectral distribution. For a switch mode dc-dc converter, random and periodical sinusoidal CFM is systematically tested. Based on disturbance voltage measurements using Line Impedance Stabilization Network (LISN) and EMI receiver, conducted emission spectra are evaluated in function of the defined randomness index R and frequency range. For the acceptable range of R variations up the 20dB EMI suppression level was reached.

Źródło:

Electrical Power Quality and Utilisation. Journal; 2005, 11, 2; 49-55
1896-4672

Pojawia się w:

Electrical Power Quality and Utilisation. Journal

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 43.

Tytuł:

Fuzzy Model of 16PSK and 16QAM Modulation

Autorzy:

Butkiewicz, B. S.

Powiązania:

https://bibliotekanauki.pl/articles/227079.pdf

Data publikacji:

2011

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

fuzzy modulation
BER
possibility
probability
PSK
QAM
noise
signal

Opis:

In the paper, a concept of Additive Fuzzy Noise (AFN) channel is introduced. The theoretical equations are derived for Bit Error Rate (BER) and Symbol Error Rate (SER) with some digital modulation scheme in the AFN channel. Following modulations are considered: Phase Shift Keying (16PSK), Quadrature Amplitude Modulation (16QAM). The fuzzy approach to these modulations is presented. The BER and SER values are calculated using possibility theory. The results obtained by fuzzy noise model are compared with conventional approach, where probability models of the noise are used.

Źródło:

International Journal of Electronics and Telecommunications; 2011, 57, 4; 437-442
2300-1933

Pojawia się w:

International Journal of Electronics and Telecommunications

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 44.

Tytuł:

Diagnosis and Therapy of Respiratory and Phonatory Disorders in Dysartrhia. Case Studies
Diagnoza i terapia zaburzeń oddechowo-fonacyjnych w dyzartrii. Studia indywidualnych przypadków

Autorzy:

Szewczyk, Beata

Powiązania:

https://bibliotekanauki.pl/articles/667489.pdf

Data publikacji:

2019

Wydawca:

Wydawnictwo Uniwersytetu Śląskiego

Tematy:

dysarthria
respiration
phonation
voice modulation
neurologopaedic diagnosis and therapy

Opis:

This article presents the exemplary types of dysarthria with its characteristic respiration, phonation, and prosody disorders. The author examined the voice capabilities of three patients, aged 52, 74 and 81, respectively, described them, and composed short session programmes in voice therapy (comprised of three meetings) adapted to their individual needs. The author carried out the part of the therapy and then listed tendencies resurfacing during the exercises performed by the patients. Finally, the expected effects of further exercises (following previously applied methods) were presented.

Źródło:

Logopedia Silesiana; 2019, 8; 400-434
2300-5246
2391-4297

Pojawia się w:

Logopedia Silesiana

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 45.

Tytuł:

Modeling and simulation of novel stepped DC coupled quasi Z-Multilevel Inverter for single phase systems

Autorzy:

Meenakshi, T.
Suthanthira Vanitha, N.

Powiązania:

https://bibliotekanauki.pl/articles/140968.pdf

Data publikacji:

2016

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

multilevel inverter
shoot through
quasi Z-Source
modulation index

Opis:

This paper presents the modeling and simulation of a novel topology of quasi Z-Multilevel Inverter with stepped DC input. The proposed inverter incorporates a simple switching technique with reduced component count and is aimed at producing boosted multilevel output AC voltage. The inverter consists of two stages and the buck /boost operation is obtained by varying the shoot through period of the pulses obtained by maximum constant boost control with third harmonic injection. With all the advantages of the quasi Z-network, the proposed inverter eliminates the fly back diodes and capacitors present in a conventional Z-Multilevel Inverter. Further the stress on the devices is less which leads to reduction in component value and hence the cost. The novel stepped DC coupled Single Phase quasi Z-Multilevel Inverter is modeled and simulated in the MATLAB – SIMULINK environment and its performance is analyzed for varying input and switching conditions. The voltage and current waveforms across each stage of the inverter is analyzed and the results are presented for different levels of input.

Źródło:

Archives of Electrical Engineering; 2016, 65, 3; 437-448
1427-4221
2300-2506

Pojawia się w:

Archives of Electrical Engineering

Dostawca treści:

Biblioteka Nauki

/5

Artykuł

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Skocz do pozycji: 46.

Tytuł:

Performance analysis of variable speed multiphase induction motor with pole phase modulation

Autorzy:

Liu, H.
Wang, J.
Zhang, Z.

Powiązania:

https://bibliotekanauki.pl/articles/140991.pdf

Data publikacji:

2016

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

induction motor (IM)
pole phase modulation (PPM)
efficiency
FEM

Opis:

The pole phase modulation (PPM) technique is an effective method to extend speed range and torque capabilities for an integrated starter and hybrid electric vehicles applications. In this paper, the five pole-phase combination types of a multiphase induction motor (IM) with 36 stator slots and 36 stator conductors are presented and compared quantitatively by using the time-stepping finite element method (TS-FEM). The 36 stator conductors of the proposed multiphase IM are fed by a 36 leg inverter and the current phase angle and amplitude of each stator conductor can be controlled independently. This paper focuses on the winding connection, the PPM technique and the performance comparative analysis of each pole-phase combination types of the proposed multiphase IM. The flux distribution, air-gap flux density, output torque, core losses and efficiency of five pole-phase combination types have been investigated.

Źródło:

Archives of Electrical Engineering; 2016, 65, 3; 425-436
1427-4221
2300-2506

Pojawia się w:

Archives of Electrical Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 47.

Tytuł:

Effect of viscosity on the far-field diffraction pattern of spatial self-phase modulation

Autorzy:

Nibu, A. G.
Silpa, S. S.
Ardra, S. N.
Anisha, M. M.
Ambika, D.

Powiązania:

https://bibliotekanauki.pl/articles/174699.pdf

Data publikacji:

2017

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

self-phase modulation
nonlinear refractive index
chlorophyll
engine oil

Opis:

Effect of viscosity of a liquid on the far-field diffraction pattern due to spatial self-phase modulation is investigated. Chlorophyll extract in acetone at different concentrations is used as the low viscous nonlinear samples and commercial engine oils, synthetic and natural. It is also used as high viscous media. In the case of chlorophyll solution, the self-induced diffraction ring pattern in the far-field is a series of circular rings at the beginning; but later it is transformed to half circular symmetry. But for the high viscous engine oils we have observed circular fringes and there is no time dependent structural variation in the pattern. The coefficient of the intensity dependent nonlinear refractive index for all the liquid samples is evaluated.

Źródło:

Optica Applicata; 2017, 47, 4; 591-599
0078-5466
1899-7015

Pojawia się w:

Optica Applicata

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 48.

Tytuł:

Power transfer analysis in a single phase dual active bridge

Autorzy:

Barlik, R.
Nowak, M.
Grzejszczak, P.

Powiązania:

https://bibliotekanauki.pl/articles/201137.pdf

Data publikacji:

2013

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

bidirectional active bridge - DAB
power losses
shift phase modulation

Opis:

This paper presents an analysis of the power transfer between two DC circuit by use a single phase galvanically isolated dual active bridge - DAB. The analytical description of instantaneous values of the currents in both DC and in AC circuits of the DAB is done. The influence of the dead time as well as voltage drops across the transistors and diodes of the bridges is examined. The different relations between voltages of the DC circuits coupled through DAB and various phase shift ratios are considered. The analytical relations describing the average values of the currents in DC circuits are derived. These currents can be used to predict the power in both DC circuits and power losses generated in semiconductor devices of the converter. It is assumed that the voltage drops across these devices in conduction states are constant. The calculation of the transferred power as well as power losses and energy efficiency for the DAB converter power rated 5600 VA which is used to energy transfer between DC circuits 280 V and 51 V±20% is presented. The proposed relations and calculation results can be useful for preliminary evaluation of power losses generated in semiconductor devices and for design of the cooling system. Due to the high switching frequency of 100 kHz, the phase shift modulation for the control of DAB is used. To validate the theoretical investigations a few experimental results are presented.

Źródło:

Bulletin of the Polish Academy of Sciences. Technical Sciences; 2013, 61, 4; 809-828
0239-7528

Pojawia się w:

Bulletin of the Polish Academy of Sciences. Technical Sciences

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 49.

Tytuł:

A comparison of different modulation techniques performances in an underground multiuser communications scenario

Autorzy:

Badescu, A.-M.

Powiązania:

https://bibliotekanauki.pl/articles/106166.pdf

Data publikacji:

2012

Wydawca:

Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej

Tematy:

modulation techniques
commercial communication systems
CDMA
16-QAM
QPSK

Opis:

The potential use of typical commercial communication systems with ultra high frequencies for the underground emergency/military situations will be investigated, as commercial systems have already a fully developed market that makes them cheap and reliable. The possible usage of broadband techniques like CDMA in the direct sequence will be studied because most commercial communication systems have already been designed to support multiple users, as the underground propagation has many possible applications. The performances of both modulation techniques are evaluated from the point of view of the quality of the signals, power spectral density and the effect that the propagation medium has on the transmitted signals such that the best modulation technique is determined. The 16QAM and QPSK modulations (two of the most popular modulation techniques in the terrestrial wireless system) are compared in a scenario where a number of underground sources share the same physical channel (and antenna) - the receiver is placed at the ground level so the generated signals must propagate through the dielectric layer in order to reach it. The transmitted power, electric and magnetic fields as well as occupied bandwidth are also calculated.

Źródło:

Annales Universitatis Mariae Curie-Skłodowska. Sectio AI, Informatica; 2012, 12, 2; 73-85
1732-1360
2083-3628

Pojawia się w:

Annales Universitatis Mariae Curie-Skłodowska. Sectio AI, Informatica

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 50.

Tytuł:

Torque ripple reduction in BLDC motor based ona PWM technique for open-end winding

Autorzy:

Baszyński, Marcin

Powiązania:

https://bibliotekanauki.pl/articles/1841368.pdf

Data publikacji:

2021

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

BLDC motor
open-end winding
PWM technique
unipolar modulation

Opis:

The article presents a modulation method for BLDC motors with unconnected windings. This method uses two full bridges (or three 12-switch H-bridges). The useof the described modulation enables reducing the motor current variable and increasing (fourfold in relation to the switching frequency) the motor current ripple frequency. Themost important benefit of using a 12-switch inverter is the twofold reduction of the dc-linkvoltage while maintaining the rated rpm (voltage reduction in comparison to a typical supplymethod). A voltage reduction causes a reduction in losses on semi-conductor elements. Thearticle also demonstrates that the proposed modulation technique significantly shortens thetime of current commutation between windings.

Źródło:

Archives of Electrical Engineering; 2021, 70, 1; 5-23
1427-4221
2300-2506

Pojawia się w:

Archives of Electrical Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 51.

Tytuł:

An Improved M-ary Modulation Scheme Based on Chaotic Dynamics

Autorzy:

Abdullah, Hikmat N.
Sahar, Asaad H.
Saeed, Thamir R.

Powiązania:

https://bibliotekanauki.pl/articles/958105.pdf

Data publikacji:

2019

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

chaos
M-ary modulation
non-coherent detection
zigzag map

Opis:

This paper proposes an improved chaos-based M-ary modulation system. It reproduces deterministic chaotic dynamics to create M-ary non-coherent modulation. The proposed modulation system transmits data using autonomous chaotic sequences. It separates the chaotic dynamics through the use of interleavers and realigns them through the use deinterleavers. The simulation results show that the improved scheme overperforms its traditional counterpart. The degree of improvement grows as the M-ary order is increased, with a penalty of increased system complexity.

Źródło:

Journal of Telecommunications and Information Technology; 2019, 4; 13-19
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 52.

Tytuł:

Window of Visibility in the Display and Capture Process

Autorzy:

Xiong, F.
Zhai, G.
Zhang, Y.

Powiązania:

https://bibliotekanauki.pl/articles/227288.pdf

Data publikacji:

2018

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

window of visibility
WoV
DLP
temporal psychovisual modulation
TPVM

Opis:

In normal conditions, the Critical Flicker Frequency is usually 60Hz. But in some special conditions, such as low spatial frequency and high contrast between frames, these special conditions have high probability to occur in some TPVM-based applications. So it’s extremely important to verify if a visual signal with a combination of temporal and spatial frequency can be recognize by human eyes. Based on the research in the last paper ’ ’Window of Visibility’ inspired security lighting system’, this paper introduces the measuring method of WoV of human eyes. In this paper we will measure critical flicker frequency in low spatial frequency and high contrast conditions, and we can witness a different conclusion from the normal conditions.

Źródło:

International Journal of Electronics and Telecommunications; 2018, 64, 3; 315-320
2300-1933

Pojawia się w:

International Journal of Electronics and Telecommunications

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 53.

Tytuł:

The influence of ODM technique on the radiation dose received by patients during head CT scan

Autorzy:

Sobczyk, Joanna
Pusz-Sapa, Aleksandra
Wojtasik, Aneta
Gaweł, Greta
Truszkiewicz, Adrian
Guz, Wiesław

Powiązania:

https://bibliotekanauki.pl/articles/454704.pdf

Data publikacji:

2018

Wydawca:

Uniwersytet Rzeszowski. Wydawnictwo Uniwersytetu Rzeszowskiego

Tematy:

organ dose modulation
computed tomography
protection against ionizing radiation

Opis:

Introduction. Computed tomography (CT) is inexpensive radiological examination of high diagnostic effectiveness. However, common use of CT tests has led to increased exposure to ionizing radiation in the population. Aim. To assess the effect of organ dose modulation (ODM) technique on the radiation dose received by patients during head CT scan. Material and methods. A retrospective analysis of 120 tests in two groups of patients who had CT scans without and with ODM. Every group consisted of 60 people (30 women and 30 men in each). The ability to perform tests in two algorithms (without and with ODM) resulted from the fact that after installing the apparatus, tests were carried out using standard technique, and only then the ODM function was launched. Results. We found that during examinations with ODM, patients received a reduced dose of ionizing radiation. The mean DLP value with ODM is 9.4% lower than the mean DLP value without ODM by comparing the tests with and without contrasting agent. The mean DLP value obtained in men using ODM was 11.9% lower than the mean dose without ODM, and in women this difference was 6.6%. Conclusion. The mean DLP value received by men with ODM was by 11.9% lower than the mean dose without ODM, and in women this difference was 6.6%. Patients receive a lower dose both in tests with and without a contrasting agent compared to the tests where ODM was not used. A statistical significance of the obtained results was found.

Źródło:

European Journal of Clinical and Experimental Medicine; 2018, 3; 198-203
2544-2406
2544-1361

Pojawia się w:

European Journal of Clinical and Experimental Medicine

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 54.

Tytuł:

Space remote sensing systems transmission capabilities modeling

Autorzy:

Burshtynska, K.
Dolynska, I.

Powiązania:

https://bibliotekanauki.pl/articles/100711.pdf

Data publikacji:

2013

Wydawca:

Uniwersytet Rolniczy im. Hugona Kołłątaja w Krakowie

Tematy:

space image
modulation transfer function
resolution
przestrzeń obrazowa
MTF

Opis:

Space information, or information obtained by means of space remote sensing, is widely and effectively used by many countries to solve a lot of scientific, technical and applied problems. Most manufacturers of space remote sensing systems declared the high resolution values of their systems. However, these values are computed theoretically, without considering the various factors affected them. To determine the real resolution of the system, we have considered mathematical modeling which describes the influence of different factors on the satellite images resolution. Some of these factors are: atmosphere turbulence, image shift, residual defocusing, and diffraction. One of the most important characteristic of the images resolution is the modulation transfer function (MTF) which allows the estimation of different factors affected on the image resolution. The modulation transfer function (MTF) is a fundamental tool for assessing the performance of imaging systems. Various authors [Zhang et al. 2012, Hwang et al. 2008, Ryan et al. 2003] investigate diferent MTF assessment methods of high resolution satellite images: a slant-edge method, a knife-edge method, a sine wave method and a grill pattern. We propose a generalized approach for MTF assessment based on theoretical assumptions which allows to determine the inluence of diferent factors. A comparative analysis of the modulation transfer function(s) for different space imaging systems shows that the image resolution depends mainly on the atmosphere turbulence and size of a sensor element. Additionally, we established that atmospheric turbulence significantly reduces the transmitting possibility of images. The parameters which describe the influence of turbu¬lence required additional studies. The main goal of our researches is to show that real spatial image(s) resolution is much "inferior" than the value provided by the manufacturers of space remote sensing systems.

Źródło:

Geomatics, Landmanagement and Landscape; 2013, 3; 27-35
2300-1496

Pojawia się w:

Geomatics, Landmanagement and Landscape

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 55.

Tytuł:

Using of Golden Code Orthogonal Super-Symbol in Media-Based Modulation for Single-Input Multiple-Output Schemes

Autorzy:

Bamisaye, Ayodeji James
Quazi, Tahmid

Powiązania:

https://bibliotekanauki.pl/articles/2142306.pdf

Data publikacji:

2022

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

golden code
media-based modulation
radio RF mirrors
SIMO

Opis:

The media-based modulation (MBM) scheme is capable of providing high throughput, increasing spectrum efficiency, and enhancing bit error rate (BER) performance of communication systems. In this paper, an MBM employing radio frequency (RF) mirrors and golden code is investigated in a single-input multiple-output (GC-SIMO) application. The aim is to reduce complexity of the system, maximize linear relationships between RF mirrors and improve spectral efficiency of MBM to in order to obtain a high data rate with the use of less hardware. Orthogonal pairs of the super-symbol in the GC scheme’s encoder are employed, transmitted via different RF mirrors at different time slots in order to achieve the full data rate and high diversity. In the results having BER of 10−5 , the GC-SIMO, MBM exhibits better performance than GD-SIMO, with the gain of approximately 7 dB and 6.5 dB SNR for 4 b/s/Hz and 6 b/s/Hz, respectively. The derived theoretical average error probability of the proposed scheme is validated with the use of the Monte Carlo simulation.

Źródło:

Journal of Telecommunications and Information Technology; 2022, 2; 43--48
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 56.

Tytuł:

Improving Strapdown Inertial Navigation System Performance by Self-Compensation of Inertial Sensor Errors

Autorzy:

Chernyak, Mycola
Kolesnyk, Vadym

Powiązania:

https://bibliotekanauki.pl/articles/36832242.pdf

Data publikacji:

2023

Wydawca:

Sieć Badawcza Łukasiewicz - Instytut Lotnictwa

Tematy:

MEMS IMU
autonomous INS
MEMS self-compensation
rotation modulation

Opis:

Microelectromechanical systems (MEMS)-based strapdown navigation systems offer advantages such as small size, low cost and minimal power consumption. However, MEMS sensors are prone to significant low-frequency noise and poor bias repeatability, which can lead to navigational errors over time. These errors make them unsuitable for autonomous navigation applications, even with frequent recalibration. One way in which to solve this problem is by using the rotation modulation (RM) method. This approach is widely recognised but has only been successful with precise laser and fiber optic gyroscopes equipped with precise rotating platforms. This article focuses on the potential of adapting the RM method for the case of inexpensive MEMS sensors that can significantly improve navigation performance, while maintaining the benefits of microelectromechanical technologies. Potential issues of implementation were discussed, and corresponding requirements were formulated. The proposed optimal computation scheme was verified during static tests of the developed inertial measurement unit (IMU). Further steps in studying the adaptation of the RM method for MEMS sensors have also been outlined.

Źródło:

Transactions on Aerospace Research; 2023, 4 (273); 41-51
0509-6669
2545-2835

Pojawia się w:

Transactions on Aerospace Research

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 57.

Tytuł:

Analysis of the Usefulness of Measurement on a Board at Ground Level for Assessing the Noise Level from a Wind Turbine

Autorzy:

Wszołek, Tadeusz
Pawlik, Paweł
Mleczko, Dominik
Chronowska, Jagna

Powiązania:

https://bibliotekanauki.pl/articles/176301.pdf

Data publikacji:

2020

Wydawca:

Polska Akademia Nauk. Czasopisma i Monografie PAN

Tematy:

wind turbine noise
amplitude modulation
acoustical measurements
environmental acoustics

Opis:

The specific working conditions of the wind turbine in strong wind cause a number of problems in the measurement of noise indicators used in its short and long-term assessment. The wind is a natural working environment of the turbine, but it also affects the measurement system, moreover, it can be a secondary source of other sounds that interfere with the measurement. One of the effective methods of eliminating the direct impact of wind on the measurement system is placing the microphone on the measurement board at ground level. However, the obtained result can not be directly compared with the admissible values, as it has to be converted to a result at a height of 4 m. The results of previous studies show that this relation depends, inter alia, on the speed and direction of the wind. The paper contains the results of measurements on the measurement board, according to EN 61400-11:2013, and at a height of 4 m above ground made simultaneously in three points around the 2 MW turbine at various instantaneous speeds and changing wind directions. Analysis of the impact of measuring point location on the measurement result of noise indicators and the occurrence of additional features affecting the relationship between the values measured on the board and at the height of 4 m, and especially the tonality, amplitude modulation and content of low frequency content, was made.

Źródło:

Archives of Acoustics; 2020, 45, 1; 165-175
0137-5075

Pojawia się w:

Archives of Acoustics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 58.

Tytuł:

A Soft-Output STBC Decoder for Aeronautical Telemetry

Autorzy:

Louёt, Yves
Othman, Rami
Skrzypczak, Alexandre

Powiązania:

https://bibliotekanauki.pl/articles/309130.pdf

Data publikacji:

2020

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

continuous-phase modulation
CPM
pulse amplitude modulation
PAM
shaped offset quadrature phase shift keying
SOQPSK
space-time block coding
STBC
ternary symbol

Opis:

Alamouti encoding is a well-known space time block encoding technique used to improve the received signal quality in Rayleigh fading channels. In aeronautical telemetry, this encoding technique is applied to shaped offset quadrature phase shift keying tier generation (SOQPSK-TG) modulation in order to handle the two-antenna issue. It is provided for in telemetry-related IRIG standards. In this paper, we propose a unique decoding architecture for Alamouti-encoded SOQPSK-TG signals, taking advantage of pulse amplitude modulation decomposition with soft and hard outputs. We exploit this result to obtain a Viterbi algorithm (VA) for hard decoding and a soft output Viterbi algorithm (SOVA) for soft and hard decoding, with a twofold benefit: operation using one trellis structure, unlike decoders that are based on the 8-waveforms cross-correlated trellis-coded quadrature modulation (XTCQM) approximation, and very attractive bit error rate performance, as well as a complexity trade-off.

Źródło:

Journal of Telecommunications and Information Technology; 2020, 1; 13-20
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 59.

Tytuł:

Evolutionary optimization of Sigma-Delta modulated analog stimulus

Autorzy:

Golonek, T.

Powiązania:

https://bibliotekanauki.pl/articles/397702.pdf

Data publikacji:

2015

Wydawca:

Politechnika Łódzka. Wydział Mikroelektroniki i Informatyki

Tematy:

analog electronic circuits testing
evolutionary optimization
sigma-delta modulation
pulse density modulation
analogowy układ elektroniczny
optymalizacja ewolucyjna
modulacja sigma-delta
modulacja gęstości impulsów

Opis:

This paper proposes the evolutionary technique of the stimulus signal optimization for the analog electronic circuit testing purpose. The obtained signal is coded with Sigma-Delta modulation usage that allows to generate it easily by simple microcontrollers without the necessity of expensive D/A peripherals applying. The signal with the controlled impulses density may be obtained on the external output terminal of the typical timer and finally, it defines the analog signal that can be reconstructed after low pass filtering.

Źródło:

International Journal of Microelectronics and Computer Science; 2015, 6, 4; 130-135
2080-8755
2353-9607

Pojawia się w:

International Journal of Microelectronics and Computer Science

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 60.

Tytuł:

Farnesyl diphosphate synthase; regulation of product specificity.

Autorzy:

Szkopińska, Anna
Płochocka, Danuta

Powiązania:

https://bibliotekanauki.pl/articles/1041460.pdf

Data publikacji:

2005

Wydawca:

Polskie Towarzystwo Biochemiczne

Tematy:

modulation of enzyme activity
dimer structure
gene family
FPP synthase

Opis:

Farnesyl diphosphate synthase (FPPS) is a key enzyme in isoprenoid biosynthesis which supplies sesquiterpene precursors for several classes of essential metabolites including sterols, dolichols, ubiquinones and carotenoids as well as substrates for farnesylation and geranylgeranylation of proteins. It catalyzes the sequential head-to-tail condensation of two molecules of isopentenyl diphosphate with dimethylallyl diphosphate. The enzyme is a homodimer of subunits, typically having two aspartate-rich motifs with two sets of substrate binding sites for an allylic diphosphate and isopentenyl diphosphate per homodimer. The synthase amino-acid residues at the 4th and 5th positions before the first aspartate rich motif mainly determine product specificity. Hypothetically, type I (eukaryotic) and type II (eubacterial) FPPSs evolved from archeal geranylgeranyl diphosphate synthase by substitutions in the chain length determination region. FPPS belongs to enzymes encoded by gene families. In plants this offers the possibility of differential regulation in response to environmental changes or to herbivore or pathogen attack.

Źródło:

Acta Biochimica Polonica; 2005, 52, 1; 45-55
0001-527X

Pojawia się w:

Acta Biochimica Polonica

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 61.

Tytuł:

Permutation Coding with Injections for Modified PAM System

Autorzy:

Ogunyanda, Opeyemi O.
Shongwe, Thokozani
Swart, Theo G.

Powiązania:

https://bibliotekanauki.pl/articles/226518.pdf

Data publikacji:

2020

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

injection
permutation codes
power line communications
pulse amplitude modulation
jitter

Opis:

Arriving at a good combination of coding and modulation schemes that can achieve good error correction constitutes a challenge in digital communication systems. In this work, we explore the combination of permutation coding (PC) and pulse amplitude modulation (PAM) for mitigating channel errors in the presence of background noise and jitter. Since PAM is characterised with bi-polar constellations, Euclidean distance is a good choice for predicting the performance of such coded modulation setup. In order to address certain challenges facing PCs, we therefore introduce injections in the coding system, together with a modified form of PAM system. This modification entails constraining the PAM constellations to the size of the codeword’s symbol. The results obtained demonstrate the strength of the modified coded PAM system over the conventional PC coded PAM system.

Źródło:

International Journal of Electronics and Telecommunications; 2020, 66, 3; 399-404
2300-1933

Pojawia się w:

International Journal of Electronics and Telecommunications

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 62.

Tytuł:

Dynamic RSA Problem for Time-Varying Traffic in Spectrum Sliced Elastic Optical Path Network

Autorzy:

Olszewski, I.

Powiązania:

https://bibliotekanauki.pl/articles/226545.pdf

Data publikacji:

2015

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

time-varying traffic
dynamic RSA problem
optical path
OFDM modulation

Opis:

Service time-varying traffic flexible optical networks require a dynamic bandwidth allocation in order to follow the source transmission rate. The problem of service time-varying traffic, assuming that the set of connection requests is not known in advance, is considered in this work. Connection requests arrive randomly and have random durations. The considered dynamic RSA problem involves minimizing the probability of future connections blocking while maintaining spectrum continuity constraints and non-overlapping spectrum assignment constraints between spectrum-adjacent connections on the network links. The proposed algorithm determines the path with the required number of slots around the reference frequency for a connection request. An analysis of the network with time-varying traffic on the network connections was carried out on the basis of spectrum expansion/contraction schemes which allow to determine average blocking probability of the additional slot requests on these connections. The obtained results have been compared with those obtained by a well known algorithm that solves the dynamic RSA problem.

Źródło:

International Journal of Electronics and Telecommunications; 2015, 61, 2; 179-184
2300-1933

Pojawia się w:

International Journal of Electronics and Telecommunications

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 63.

Tytuł:

Performance Analysis of SPSK with Dual Polarized Transmit Antennas over Rayleigh Fading Channel

Autorzy:

Subramani, M.
Neduncheran, A. V.
Ponnusamy, V.

Powiązania:

https://bibliotekanauki.pl/articles/307739.pdf

Data publikacji:

2018

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

ABER
dual polarized antenna
Rayleigh fading
spatial modulation
SPSK
SSK

Opis:

In this paper, the Space Polarization Shift Keying (SPSK) system, which is an extended version of Space Shift Keying (SSK) and includes both space and polarization dimensions with dual polarized antennas, is studied. The capacity and error probability analysis of SPSK for different polarization configurations are dealt with over the Rayleigh fading channel with a rich scattering environment. The analysis conducted shows that the SPSK with a dual polarized antenna (DP) offers better results than SPSK with a single orthogonal polarized antenna SPSK(SP), under non-LOS conditions. SPSK(DP) outperforms SSK by 4.2 dB over the correlated Rayleigh fading channel at 3 bits/s/Hz.

Źródło:

Journal of Telecommunications and Information Technology; 2018, 1; 58-61
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 64.

Tytuł:

Utilization of the SOA Deep Saturation and Power Averaging Effect to Counteract Intra-Channel Crosstalk in DWDM System

Autorzy:

Dyc, F. M.
Mazurek, P.
Turkiewicz, J. P.

Powiązania:

https://bibliotekanauki.pl/articles/308974.pdf

Data publikacji:

2014

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

cross-gain modulation
Dense Wavelength Division Multiplexing
Semiconductor Optical Amplifier

Opis:

The Semiconductor Optical Amplifier (SOA) is a key component of cost-effective short/medium range transmission systems. However it can introduce signal distortions. In this paper the authors investigate the possibility to reduce the signal distortions in SOA operating with the multiple wavelength channels. Using numerical simulations the negative influence of the nonlinear effects, namely cross-gain modulation (XGM) and the patterning effect can be reduced in deep SOA saturation regime. The self-healing effect is pronounced for the 4 or more wavelength channels and the transmitted symbol length longer than double of the SOA recovery time.

Źródło:

Journal of Telecommunications and Information Technology; 2014, 2; 22-28
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 65.

Tytuł:

Optical self-phase modulation using a new photonic crystal coupled-cavity waveguide

Autorzy:

Bahadori-Haghighi, S
Ghayour, R

Powiązania:

https://bibliotekanauki.pl/articles/173977.pdf

Data publikacji:

2014

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

photonic crystal
slow light
coupled-cavity waveguide
self-phase modulation

Opis:

In this paper, self-phase modulation of an optical pulse using a new photonic crystal coupled-cavity waveguide is simulated and analyzed. The structure of the new coupled-cavity waveguide is introduced and its advantage over the previous type of coupled-cavity waveguide is discussed. In order to obtain a high group index over a large bandwidth and benefit from the slow light phenomenon, the group index and group velocity dispersion parameter curves of the guided mode are calculated. Finally, the transient simulation of the structure is performed using a finite-difference time-domain method. The calculated required length of the coupled-cavity waveguide for a maximum phase shift of π is about 31 μm. Spectral broadening of the optical pulse as a result of self-phase modulation is also presented and discussed.

Źródło:

Optica Applicata; 2014, 44, 1; 29-38
0078-5466
1899-7015

Pojawia się w:

Optica Applicata

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 66.

Tytuł:

Influence of glistening and calcium deposits in artificial intraocular lenses on retinal image quality – numerical model

Autorzy:

Geniusz, M.
Zajac, M.

Powiązania:

https://bibliotekanauki.pl/articles/173584.pdf

Data publikacji:

2017

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

intraocular lens (IOL)
glistenings
modulation transfer function
MTF
calcium deposits

Opis:

In modern ophthalmology the natural eye lens is sometimes replaced with an artificial implant – intraocular lens which remains in the eye for a long time. This can lead to the formation of numerous microdefects occurring on the intraocular lens surface or inside its volume. The most common include calcium deposits or microvacuoles referred to as glistenings. The presence of those defects causes deterioration of retinal image thus lowering the quality of vision. The purpose of this research is to develop a numerical model of human eye with intraocular lens burden with defects useful to predict the impact of calcium deposits and glistenings on the retinal image quality. The calculations made in accordance with this model suggest that the quality of retinal image deteriorates when the density of defects increases, but the degree of image deterioration does not depend on the location of the defects and transmittance of individual particles. The main deterioration effect is observed for low spatial frequencies (< 12 cycles/deg) both in case of calcium deposits and glistenings while for the spatial frequency of 30 cycles/deg the changes in modulation transfer function are insignificant. The presence of microvacuoles in the intraocular lens influences the worsening of modulation transfer function parameters only for the diameter of microvacuoles greater than 10 μm.

Źródło:

Optica Applicata; 2017, 47, 3; 341-350
0078-5466
1899-7015

Pojawia się w:

Optica Applicata

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 67.

Tytuł:

Wpływ kształtu modulowanego promieniowania optycznego na czułość napięciową detektora piroelektrycznego
Influence of modulated optical radiation shape on pyroelectric detector voltage responsivity

Autorzy:

Odon, A.

Powiązania:

https://bibliotekanauki.pl/articles/152155.pdf

Data publikacji:

2012

Wydawca:

Stowarzyszenie Inżynierów i Techników Mechaników Polskich

Tematy:

czułość detektora piroelektrycznego
optyczny modulator
pyroelectric sensor
responsivity
optical modulation

Opis:

Badania zależności czułości detektora piroelektrycznego od częstotliwości powinny być przeprowadzane przy zastosowaniu sinusoidalnie modulowanego promieniowania pobudzającego detektor. W praktyce eksperymentalnej często stosowane są elektromechaniczne modulatory, które zapewniają wytworzenie quasi-prostokątnego lub quasi-trapezowego kształtu przebiegu mocy promieniowania. Wyznaczona w ten sposób wartość czułości napięciowej detektora może być obarczona dużym błędem. W artykule przedstawiono rezultaty badań symulacyjnych, których celem jest wyznaczenie zależności czułości napięciowej od częstotliwości dla modelu detektora piroelektrycznego zaimplementowanego w programie MATLAB-Simulink i dokonanie oceny błędu pomiaru czułości spowodowanego zastosowaniem niesinusoidalnych przebiegów mocy promieniowania pobudzających detektor piroelektryczny.
The voltage responsivity of a pyroelectric detector is one of the most important parameters characterizing its measuring properties. Sinusoidally modulated optical radiation should be used for experimental measuring of the pyroelectric detector responsivity. In practice rotating disk choppers are commonly used as a source of modulated optical signals in experimental setups. A disadvantage of using optical choppers is that the produced radiation may have a square or trapezoidal waveform. In the paper the results of simulation studies of the pyroelectric detector frequency response for sinusoidal, square and trapezoidal shape of the modulated radiation are presented. The simulation studies were carried out for the pyroelectric detektor model with use of program MATLAB-Simulink. Values of the main parameters of this detector were precisely specified. The frequency dependence of the pyroelectric detector voltage responsivity for different shapes of the absorbed radiation waveform is shown in Fig. 2. The simulation results show that the responsivity of the detector excited by a square wave of radiation has a much higher value (up to several hundred percent) in comparison to that obtained with sinusoidal modulation of radiation, especially at low frequencies. Trapezoidal modulation produces a much smaller error than the square wave modulation.

Źródło:

Pomiary Automatyka Kontrola; 2012, R. 58, nr 11, 11; 997-999
0032-4140

Pojawia się w:

Pomiary Automatyka Kontrola

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 68.

Tytuł:

Trellis Coded 4-ary PAM using Distance-Preserving Mapping

Autorzy:

Shongwe, T.

Powiązania:

https://bibliotekanauki.pl/articles/226278.pdf

Data publikacji:

2018

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

distance-preserving mappings
hamming distance
euclidean distance
pulse amplitude modulation

Opis:

A trellis coded 4-ary Pulse Amplitude Modulation (4-PAM) is presented, where the encoding algorithm is derived from Distance Preserving Mapping (DPM) algorithm. In this work, we modify the DPM algorithm for 4-PAM and obtain a new construction for mapping binary sequences to permutation sequences, where the permutation sequences are obtained by permuting symbols of a 4-PAM constellation. The resulting codebook of permutation sequences formed this way are termed mappings. We also present several metrics for assessing the performance of the mappings from our construction, and we show that a metric called the Sum of Product of Distances (SOPD) is the best metric to use when judging the performance of the mappings. Finally, performance results are presented, where the mappings from our construction are compared against each other and also against the conventional mappings in the literature.

Źródło:

International Journal of Electronics and Telecommunications; 2018, 64, 4; 527-533
2300-1933

Pojawia się w:

International Journal of Electronics and Telecommunications

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 69.

Tytuł:

One more conception of an embedded acoustic chirp modem for underwater communication

Autorzy:

Kurowski, A.
Solarska, P.
Dąbrowski, D.
Loch, M.

Powiązania:

https://bibliotekanauki.pl/articles/332703.pdf

Data publikacji:

2015

Wydawca:

Polskie Towarzystwo Akustyczne

Tematy:

chirp signals
Raspberry Pi
modulation
synchronisation
frames forming
and symbol mapping

Opis:

In this paper we present a conception of an embedded acoustic modem dedicated to the underwater communication. The Raspberry Pi is used as a low cost hardware platform. The solution of the physical layer consists in modulation, synchronisation, frames forming, symbol mapping, etc. Specifically, the modulation is based upon linear and hyperbolic chirp signal generation. The synchronisation is based upon the correlation of received and transmitted signals. The performance of the communication is tested by the computer simulation. The simulation is realized by USB sound cards and a wire. In the simulation, transmitted signals are intentionally degradated by the additive white gaussian noise.

Źródło:

Hydroacoustics; 2015, 18; 103-112
1642-1817

Pojawia się w:

Hydroacoustics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 70.

Tytuł:

A new closed loop speed control strategy for a vector controlled three-phase induction motor drive

Autorzy:

Tripathi, A.
Dey, A.
Dwivedi, B.
Singh, B.
Chandra, D.

Powiązania:

https://bibliotekanauki.pl/articles/262777.pdf

Data publikacji:

2008

Wydawca:

Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

Tematy:

space vector modulation
VSI
induction motor model
transients
steady state value

Opis:

This paper presents a completely mathematical equations based model on control of torque and speed of a three-phase indirect vector controlled VSI fed cage induction motor drive that is controlled through the space vector modulated method. This enables a wide range of acceptability of the model for various values of load and for various types and ratings of induction motors. The uniqueness of the model lies in the fact that the deviations in the torque and speed on sudden application of reference step change in speed values are minimum i.e. when any sudden change in the speed reference is desired, the speed and torque waveforms reveal that the time taken in coming back to their final steady state values is very less and the motor overcomes the perturbation with negligible transients. The same is verified through the simulated results.

Źródło:

Electrical Power Quality and Utilisation. Journal; 2008, 14, 1; 67-72
1896-4672

Pojawia się w:

Electrical Power Quality and Utilisation. Journal

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 71.

Tytuł:

A method of reducing switch count in three-level NPC inverter – analysis in steady states

Autorzy:

Beniak, R.
Rogowski, K.

Powiązania:

https://bibliotekanauki.pl/articles/1193464.pdf

Data publikacji:

2017

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

reduction of switch count
three-level NPC inverter
space vector modulation

Opis:

The proof of a concept for a new method of modulation has been presented which reduce switch count in a three-level neutral point clamped (3L-NPC) inverter. The method is an implementation of space vector modulation (SVM) by means of a prediction algorithm and sequences of transistors, which are not common in use. Those sequences make active use of clamping diodes of the inverter. The prediction algorithm analyzes possible sequences of transistors’ states and choose those which offers smaller switch count. Measurements of steady states were taken on prototype 3L-NPC.

Źródło:

Power Electronics and Drives; 2017, 2, 37/2; 117-126
2451-0262
2543-4292

Pojawia się w:

Power Electronics and Drives

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 72.

Tytuł:

OFDM for Cognitive Radio Systems : Novel Power Allocation and Bit Loading Algorithms

Autorzy:

Razmi, Shirin
Parhizgar, Naser

Powiązania:

https://bibliotekanauki.pl/articles/227256.pdf

Data publikacji:

2019

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

cognitive radio
OFDM
interference constraints
power allocation
adaptive modulation
bit loading

Opis:

A novel method to improve the performance of the frequency band is cognitive radio that was introduced in 1999. Due to a lot of advantages of the OFDM, adaptive OFDM method, this technique is used in cognitive radio (CR) systems, widely. In adaptive OFDM, transmission rate and power of subcarriers are allocated based on the channel variations to improve the system performance. This paper investigates adaptive resource allocation in the CR systems that are used OFDM technique to transmit data. The aim of this paper is to maximize the achievable transmission rate for the CR system by considering the interference constraint. Although secondary users can be aware form channel information between each other, but in some wireless standards, it is impossible for secondary user to be aware from channel information between itself and a primary user. Therefore, due to practical limitation, statistical interference channel is considered in this paper. This paper introduces a novel suboptimal power allocation algorithm. Also, this paper introduces a novel bit loading algorithm. In the numerical results sections, the performance of our algorithm is compared by optimal and conventional algorithms. Numerical results indicate our algorithm has better performance than conventional algorithms while its complexity is less than optimal algorithm.

Źródło:

International Journal of Electronics and Telecommunications; 2019, 65, 1; 139-145
2300-1933

Pojawia się w:

International Journal of Electronics and Telecommunications

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 73.

Tytuł:

THREE PHASE WARSAW BOOST RECTIFIER FOR HIGH POWER VARIABLE SPEED POWER GENERATION
Trójfazowy „Warsaw Rectifier” w układzie wytwarzania energii dużej mocy o regulowanej prędkości generatora

Autorzy:

Bałkowiec, T.

Powiązania:

https://bibliotekanauki.pl/articles/1817906.pdf

Data publikacji:

2015

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

Warsaw rectifier
delta-switch rectifier
high power
PWM modulation
Vienna rectifier

Opis:

Artykuł przedstawia topologię prostownika „Warsaw Rectifier”, jego zasadę działania oraz wyniki symulacyjne, w których prostownik zasilany był ze źródła napięcia o zmiennej amplitudzie i częstotliwości, np. generatora z magnesami trwałymi. Wyniki symulacyjne potwierdzają poprawność opracowanego układu sterowania, opartego na modulacji szerokości impulsów o stałej częstotliwości łączeń. Przedstawione wyniki w tabeli 3 również potwierdzają, że topologia umożliwia pobór sinusoidalnego prądu oraz stabilizację napięcia wyjściowego prostownika w układach o dużej mocy, w których częstotliwość łączeń jest ograniczona. Układ prostownika umożliwia zapewnia małe pulsacje mocy, które w generatorze przekładają się na małe pulsacji momentu. Topologia Warsaw Rectifier jest podobna do topologii Vienna Rectifier, natomiast różni się sposobem połączeń. Co więcej, rozważany prostownik Warsaw Rectifier wytwarza dwupoziomowe napięcie wyjściowe, podczas gdy prostownik Vienna wytwarza stałe, trójpoziomowe napięcie.

Źródło:

Prace Naukowe Instytutu Maszyn, Napędów i Pomiarów Elektrycznych Politechniki Wrocławskiej. Studia i Materiały; 2015, 71, 35; 3--15
1733-0718

Pojawia się w:

Prace Naukowe Instytutu Maszyn, Napędów i Pomiarów Elektrycznych Politechniki Wrocławskiej. Studia i Materiały

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 74.

Tytuł:

Comparison of Wavelet Decomposition Coefficients Transmission Systems Using Splines and Classical Types of Modulation

Autorzy:

Kutin, A. I.

Powiązania:

https://bibliotekanauki.pl/articles/309261.pdf

Data publikacji:

2015

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

multi-speed channels
spline-modulation
spline Savitzky-Golay filter
wavelet decomposition

Opis:

Wavelets are becoming increasingly used as a tool for the analysis of non-stationary data. To transmit the coefficients resulting from the signal decomposition traditionally their combination into a single data packet is used, without including unequal energy contribution of each factor and impact of the decomposition level. This paper analyzes (at different transmission speeds) the signals properties produced by classical modulation methods and spline modulation for wavelet coefficients transmission proposed by the author. For all signal types the additive Gaussian noise is used as a noise disturbance.

Źródło:

Journal of Telecommunications and Information Technology; 2015, 3; 25-31
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 75.

Tytuł:

Magnetospectroscopy of CdTe/Cd₁-xMgxTe modulation-doped quantum wells in THz and visible range

Autorzy:

Łusakowski, Jerzy
Zaremba, Maciej
Siemaszko, Adam
Karpierz, Krzysztof
Adamus, Zbigniew
Wojtowicz, Tomasz

Powiązania:

https://bibliotekanauki.pl/articles/2204169.pdf

Data publikacji:

2023

Wydawca:

Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich

Tematy:

terahertz spectroscopy
optically detected cyclotron resonance
modulation-doped CdTe quantum wells

Opis:

Transport, photoluminescence, THz transmission, and optically detected cyclotron resonance studies were carried out on samples with a single modulation-doped CdTe/Cd1-xMgxTe quantum well. THz experiments were performed at liquid helium temperatures for photon energies between about 0.5 meV and 3.5 meV. An effective mass of electron was determined to be (0.1020 ± 0.0003)m₀. Observed photoluminescence and optically detected cyclotron resonance spectra cannot be explained within the simple model of Landau quantization of parabolic bands.

Źródło:

Opto-Electronics Review; 2023, 31, 2; art. no. e144597
1230-3402

Pojawia się w:

Opto-Electronics Review

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 76.

Tytuł:

Delayed differential detection for absorption spectroscopy recovery

Autorzy:

Cong, Menglong
Sun, Dandan

Powiązania:

https://bibliotekanauki.pl/articles/173211.pdf

Data publikacji:

2019

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

wavelength modulation spectroscopy
WMS
absorption
derivative spectrum
harmonic detection
laser diode

Opis:

An elaborately designed system has been devoted to the recovery of the line shape function of absorption spectrum. Laser power passing through trace gas has been divided into the real-time and delayed components, and their difference, i.e. the equivalent of the first-order derivative spectrum, is recorded and integrated to reconstruct the absorption line profile. Since the real-time and delayed signals are derived from the only gas cell and photodetector, the elimination of background is more effective, relative to the general used double beam detection that involves two gas cells and photodetectors. Compared with the 1st harmonic detection used in the wavelength modulation spectroscopy, here the generation of derivative spectrum is achieved without modulating the injection current of laser. Additionally, the expensive lock-in amplifier working for wavelength modulation spectroscopy is replaced by a homemade device, which is made of an all-pass filter and an instrumentation amplifier. Therefore, the complexity and cost are significantly reduced, and the stability is improved. For the purpose of validation, recovering of the absorption spectroscopy is carried out using a methane sample at its R(3) absorption line of the 2ν₃ overtone, and the obtained data are found to be in a high agreement with theoretical deductions.

Źródło:

Optica Applicata; 2019, 49, 2; 303-315
0078-5466
1899-7015

Pojawia się w:

Optica Applicata

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 77.

Tytuł:

Research on a scheme of generating ultra-wideband doublet signal based on the cross-gain modulation in a semiconductor optical amplifier

Autorzy:

Zhang, K.
Shao, J.

Powiązania:

https://bibliotekanauki.pl/articles/173646.pdf

Data publikacji:

2018

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

ultra-wideband
UWB
semiconductor optical amplifier
SOA
cross-gain modulation
XGM

Opis:

We propose a novel scheme for generating ultra-wideband doublet signal based on the cross-gain modulation effect in a semiconductor optical amplifier. This scheme requires only a semiconductor optical amplifier and an optical source. By using OptiSystem software, we simulate and analyze the effect of the input signal light power and wavelength, the pulse width and injection current on the generated doublet pulse. In addition, the optimal range of parameters are also given in the simulation process.

Źródło:

Optica Applicata; 2018, 48, 1; 127-135
0078-5466
1899-7015

Pojawia się w:

Optica Applicata

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 78.

Tytuł:

A method of reducing switching losses in three-level NPC inverter

Autorzy:

Beniak, R.
Rogowski, K.

Powiązania:

https://bibliotekanauki.pl/articles/1193262.pdf

Data publikacji:

2016

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

reduction of switching losses
three-level NPC inverter
space vector modulation

Opis:

The aim of the paper is to present a concept of implementation of a space vector modulation (SVM) algorithm, which is used to create alternating current waveforms of changing amplitude and frequency in power inverters. The main goal of the method is to decrease the number of state changes in power transistors. It is realized by utilizing a prediction algorithm and sequences of transistors, which are not common in use. The method requires measurement of inverter output current flow. The prediction algorithm analyzes possible sequences of transistors’ states and choose those which offers smaller switch count. A decrease of about 20% was obtained for the cases tested. This paper presents simulation result for selected driving scenario. The described method decreases the number of state changes in power transistors and therefore it is a potentially good method to considerably decrease energy losses of multilevel inverter-powered drive.

Źródło:

Power Electronics and Drives; 2016, 1, 36/2; 55-63
2451-0262
2543-4292

Pojawia się w:

Power Electronics and Drives

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 79.

Tytuł:

Vertical cavity surface emitting lasers in radio over fiber applications

Autorzy:

Marozsák, T.
Udvary, E.

Powiązania:

https://bibliotekanauki.pl/articles/309233.pdf

Data publikacji:

2003

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

modulacja analogowa
zniekształcenia
VCSEL
analog modulation
nonlinear distortion
radio over fiber

Opis:

Theoretical and experimental study of using direct modulated vertical cavity surface emitting lasers in radio over fiber applications is presented. The nonlinear distortion and signal to noise ratio are investigated and evaluated in case of short-range multi-carrier transmission. Nonlinear characterization and comparison of the different kind of semiconductor lasers are also presented.

Źródło:

Journal of Telecommunications and Information Technology; 2003, 1; 36-40
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 80.

Tytuł:

Epigenetic modulation of the activity of transgen and endogenous gene based on the example of chalcone synthase in flax

Autorzy:

Zuk, M.
Dzialo, M.
Szopa, J.

Powiązania:

https://bibliotekanauki.pl/articles/951257.pdf

Data publikacji:

2015

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

epigenetic modulation
mutagenesis
genetic modification
chalcone synthase
flax
transgenic plant
phenylpropanoid

Źródło:

BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2015, 96, 1
0860-7796

Pojawia się w:

BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 81.

Tytuł:

Model flickermetru dla modulacji częstotliwości napięcia wejściowego
A model of the flickermeter for frequency modulation of input voltage

Autorzy:

Wiczyński, G.

Powiązania:

https://bibliotekanauki.pl/articles/153232.pdf

Data publikacji:

2007

Wydawca:

Stowarzyszenie Inżynierów i Techników Mechaników Polskich

Tematy:

flickermetr
model
wskaźnik Pst
modulacja FM
flickermeter
Ps
indicator
frequency modulation

Opis:

Flickermetr jest potoczną nazwą układu do pomiaru uciążliwości odczuwania migotania światła wywołanego wahaniami napięcia. Przetwarzanie toru sygnałowego tego układu jest na tyle złożone, że analityczne wyznaczenie wartości wyjściowych nie jest proste. Założonym celem prac opisanych w artykule jest budowa prostego modelu dla modulacji częstotliwości FM sygnału wejściowego. Obecnie brak specyfikacji normatywnej flickermetru do modulacji FM. W artykule zaproponowano model flickermetru dla modulacji FM sygnałami wolnozmiennymi i w zakresie od 1Hz do 100 Hz. Dokonano ocenę prawidłowości aproksymacji charakterystyk dla modulacji FM przebiegami harmonicznym i prostokątnym, bazując na wynikach symulacji numerycznych. Prezentowany model ułatwia zrozumienie działania badanego toru sygnałowego flickermetru i weryfikację prawidłowości działania rzeczywistych układów pomiarowych w rozpatrywanym zakresie częstotliwości sygnału modulującego FM.
The aim of studies presented in the paper is a structure of the simple model for FM frequency modulation of the input signal. There is a lack of the flickermeter standard specification in this subject. Based on results of numerical simulations, evaluation of approximation correctness of characteristics for FM modulation with harmonic as well as rectangular waveforms has been made. The equations for FM modulation using slowly varying signals and signals in the frequency range from 1 Hz to 100 Hz are proposed. The presented model facilitates understanding the operation of the tested flickermeter signal chain and verification of the operation correctness of real measuring systems in the considered frequency range.

Źródło:

Pomiary Automatyka Kontrola; 2007, R. 53, nr 9 bis, 9 bis; 633-636
0032-4140

Pojawia się w:

Pomiary Automatyka Kontrola

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 82.

Tytuł:

Chaotic convection of viscoelastic fluid in porous medium under G-jitter

Autorzy:

Bhadauria, B. S.
Singh, A.
Singh, M. K.

Powiązania:

https://bibliotekanauki.pl/articles/265559.pdf

Data publikacji:

2019

Wydawca:

Uniwersytet Zielonogórski. Oficyna Wydawnicza

Tematy:

teoria nieliniowa
grawitacja
konwekcja
non-linear theory
gravity modulation
chaotic convection

Opis:

The present article aims at investigating the effect of gravity modulation on chaotic convection of a viscoelastic fluid in porous media. For this, the problem is reduced into Lorenz system (non-autonomous) by employing the truncated Galerkin expansion method. The system shows transitions from periodic to chaotic behavior on increasing the scaled Rayleigh number R. The amplitude of modulation advances the chaotic nature in the system while the frequency of modulation has a tendency to delay the chaotic behavior which is in good agreement with the results due to [1]. The behavior of the scaled relaxation and retardation parameter on the system is also studied. The phase portrait and time domain diagrams of the Lorenz system for suitable parameter values have been used to analyze the system.

Źródło:

International Journal of Applied Mechanics and Engineering; 2019, 24, 1; 37-51
1734-4492
2353-9003

Pojawia się w:

International Journal of Applied Mechanics and Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 83.

Tytuł:

Growth and properties of ZnO films grown using pa-movpe with DMZn and N2O

Autorzy:

Nakano, T.
Nishimoto, K.
Sumiya, M.
Fuke, S.

Powiązania:

https://bibliotekanauki.pl/articles/385163.pdf

Data publikacji:

2009

Wydawca:

Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów

Tematy:

ZnO
PA-MOVPE
epitaxial growth
DMZn
N2O
temperature modulation growth

Opis:

ZnO films were grown by plasma-assisted metal organic vapor phase epitaxy (PA-MOVPE) using dimethylzinc (DMZn) and N O gases. The crystallinity and surface morphology of ZnO films were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The crystallinity of ZnO improved (a) when the N2O flow rate was increased, because vapor phase reaction was suppressed while surface migration was enhanced, and (b) when the growth temperature was increased, because surface diffusion was enhanced. In the PA-MOVPE method with N2O gases and DMZn, both the N2O flow rate and crystal growth temperature strongly affected the crystallinity of ZnO films.

Źródło:

Journal of Automation Mobile Robotics and Intelligent Systems; 2009, 3, 4; 124-126
1897-8649
2080-2145

Pojawia się w:

Journal of Automation Mobile Robotics and Intelligent Systems

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 84.

Tytuł:

Localization of Copy-Move Forgery in Speech Signals Through Watermarking Using DCT-QIM

Autorzy:

Lalitha, N.V.
Rao, Ch. Srinivasa
Jaya-Sree, P.V.Y.

Powiązania:

https://bibliotekanauki.pl/articles/227242.pdf

Data publikacji:

2019

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

watermarking
copy-move forgery
discrete Cosine
transform
quantization index modulation
hash bits

Opis:

Digital speech copyright protection and forgery identification are the prevalent issues in our advancing digital world. In speech forgery, voiced part of the speech signal is copied and pasted to a specific location which alters the meaning of the speech signal. Watermarking can be used to safe guard the copyrights of the owner. To detect copy-move forgeries a transform domain watermarking method is proposed. In the proposed method, watermarking is achieved through Discrete Cosine Transform (DCT) and Quantization Index Modulation (QIM) rule. Hash bits are also inserted in watermarked voice segments to detect Copy-Move Forgery (CMF) in speech signals. Proposed method is evaluated on two databases and achieved good imperceptibility. It exhibits robustness in detecting the watermark and forgeries against signal processing attacks such as resample, low-pass filtering, jittering, compression and cropping. The proposed work contributes for forensics analysis in speech signals. This proposed work also compared with the some of the state-of-art methods.

Źródło:

International Journal of Electronics and Telecommunications; 2019, 65, 3; 527-532
2300-1933

Pojawia się w:

International Journal of Electronics and Telecommunications

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 85.

Tytuł:

Radio Photonic Systems for Measurement of Instantaneous Radio Frequency with Amplitude-phase Modulation of Optical Carrier

Autorzy:

Morozov, O. G.
Nasybullin, A. R.
Vedenkin, D. A.
Agliullin, T. A.

Powiązania:

https://bibliotekanauki.pl/articles/958054.pdf

Data publikacji:

2016

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

amplitude-phase modulation
transformation
fiber Bragg grating (FBG)
instantaneous frequency
radio photonics

Opis:

In this article questions related to the development instantaneous radio frequency measurement system based on application in them original ways of the amplitude-phase modulation transformation of single-frequency optical carrier by a radio signal in symmetric two-frequency and measuring “frequency-amplitude” transformation in fiber Bragg grating with special profile are considered. Such systems have broad prospects for use in telecommunications, military systems and for environmental monitoring.

Źródło:

Journal of Telecommunications and Information Technology; 2016, 2; 103-107
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

Artykuł

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Skocz do pozycji: 86.

Tytuł:

Hydrogen Detection With a Gas Sensor Array – Processing and Recognition of Dynamic Responses Using Neural Networks

Autorzy:

Gwiżdż, P.
Brudnik, A.
Zakrzewska, K.

Powiązania:

https://bibliotekanauki.pl/articles/221723.pdf

Data publikacji:

2015

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

gas sensor
sensor array
temperature modulation
dynamic response
feature extraction
neural networks

Opis:

An array consisting of four commercial gas sensors with target specifications for hydrocarbons, ammonia, alcohol, explosive gases has been constructed and tested. The sensors in the array operate in the dynamic mode upon the temperature modulation from 350°C to 500°C. Changes in the sensor operating temperature lead to distinct resistance responses affected by the gas type, its concentration and the humidity level. The measurements are performed upon various hydrogen (17-3000 ppm), methane (167-3000 ppm) and propane (167-3000 ppm) concentrations at relative humidity levels of 0-75%RH. The measured dynamic response signals are further processed with the Discrete Fourier Transform. Absolute values of the dc component and the first five harmonics of each sensor are analysed by a feed-forward back-propagation neural network. The ultimate aim of this research is to achieve a reliable hydrogen detection despite an interference of the humidity and residual gases.

Źródło:

Metrology and Measurement Systems; 2015, 22, 1; 3-12
0860-8229

Pojawia się w:

Metrology and Measurement Systems

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 87.

Tytuł:

Averaged models of pulse-modulated DC-DC power converters. Part II. Models based on the separation of variables

Autorzy:

Janke, W.

Powiązania:

https://bibliotekanauki.pl/articles/140855.pdf

Data publikacji:

2012

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

power converters
pulse width modulation (PWM)
BUCK
buck-boost
BOOST
averaged models

Opis:

The separation of variables approach to formulate the averaged models of DC-DC switch-mode power converters is presented in the paper. The proposed method is applied to basic converters such as BUCK, BOOST and BUCK-BOOST. The ideal converters or converters with parasitic resistances, working in CCM and in DCM mode are considered. The models are presented in the form of equation systems for large signal, steady-state and small-signal case. It is shown, that the models obtained by separation of variables approach differ in some situations from standard models based on switch averaging method.

Źródło:

Archives of Electrical Engineering; 2012, 61, 4; 633-654
1427-4221
2300-2506

Pojawia się w:

Archives of Electrical Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 88.

Tytuł:

Averaged models of pulse-modulated DC-DC power converters. Part I. Discussion of standard methods

Autorzy:

Janke, W.

Powiązania:

https://bibliotekanauki.pl/articles/140859.pdf

Data publikacji:

2012

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

power converters
pulse width modulation (PWM)
BUCK
BOOST
buck-boost
averaged models

Opis:

The averaged models of switch-mode DC-DC power converters are discussed. Two methods of averaged model derivation are considered - the first, based on statespace averaging and the second, on the switch averaging approach. The simplest converters: BUCK, BOOST and BUCK-BOOST working in CCM (continuous conduction mode) or DCM are taken as examples in detailed considerations. Apart from the ideal converters, the more realistic case of converters with parasitic resistances is analyzed. The switch averaging approach is used more frequently than the other and is believed to be more convenient in practical applications. It is shown however, that in the deriving the averaged models based on the switch-averaging approach, some informalities have been made, which may be the source of errors in the case of converters with parasitic resistances, or working in DCM mode.

Źródło:

Archives of Electrical Engineering; 2012, 61, 4; 609-631
1427-4221
2300-2506

Pojawia się w:

Archives of Electrical Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 89.

Tytuł:

Design of a Class-D Audio Amplifier With Analog Volume Control for Mobile Applications

Autorzy:

El Khadiri, K.
Qjidaa, H.

Powiązania:

https://bibliotekanauki.pl/articles/226924.pdf

Data publikacji:

2016

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

class D amplifier
analog volume control
pulse width modulation (PWM)
ramp generator

Opis:

A class-D audio amplifier with analog volume control (AVC) for portable applications is proposed in this paper. The proposed class-D consist of two sections. First section is an analog volume control which consists of an integrator, an analog MUX and a programmable gain amplifier (PGA). The AVC is implemented with three analog inputs (Audio, Voice, FM). Second section is a driver which consists of a ramp generator, a comparator, a level shifter and a gate driver. The driver is designed to obtain a low distortion and a high efficiency. Designed with 0.18 um 1P6M CMOS technology, the class-D audio amplifier with AVC achieves a total root-mean-square (RMS) output power of 0.5W, a total harmonic distortion plus noise (THD+N) at the 8-Ω load less than 0.06% and a power efficiency of 90% with a total area of 1.74 mm2.

Źródło:

International Journal of Electronics and Telecommunications; 2016, 62, 2; 187-198
2300-1933

Pojawia się w:

International Journal of Electronics and Telecommunications

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 90.

Tytuł:

Control of the DTC-FSVM based induction motor drive in a wide speed range

Autorzy:

Nguyen Thac, K.
Orlowska-Kowalska, T.

Powiązania:

https://bibliotekanauki.pl/articles/1817721.pdf

Data publikacji:

2014

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

induction motor
direct torque control
Flux-Space-Vector Modulation
field weakening control

Opis:

In this paper the direct flux and torque control structure based on Flux-error Space Vector Modulation (DTC-FSVM) has been analyzed and compared to a classical DTC-SVM system. The control structures have been tested in a wide speed range including field weakening algorithm based on the voltage and current limits of the voltage inverter and the induction motor. The proposed control strategies are verified through simulation with a 3 kW induction motor drive.

Źródło:

Prace Naukowe Instytutu Maszyn, Napędów i Pomiarów Elektrycznych Politechniki Wrocławskiej. Studia i Materiały; 2014, 70, 34; 3--15
1733-0718

Pojawia się w:

Prace Naukowe Instytutu Maszyn, Napędów i Pomiarów Elektrycznych Politechniki Wrocławskiej. Studia i Materiały

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 91.

Tytuł:

Wpływ metody akwizycji sygnałów częstotliwościowych na dokładność pomiaru
Effect of the method of frequency signal acquisition on the measurement accuracy

Autorzy:

Świsulski, D.
Pawłowski, E.

Powiązania:

https://bibliotekanauki.pl/articles/155228.pdf

Data publikacji:

2013

Wydawca:

Stowarzyszenie Inżynierów i Techników Mechaników Polskich

Tematy:

akwizycja sygnałów
sygnał impulsowy modulowany częstotliwościowo
signal acquisition
pulse frequency modulation signal

Opis:

W artykule przedstawiono metody przetwarzania impulsowego sygnału częstotliwościowego. Opisane metody pozwalają na odtworzenie wartości wielkości mierzonej w stałych odstępach czasu w trybie on-line i off-line. Przeprowadzono symulację pomiaru prędkości obrotowej przetwornikiem obrotowo-impulsowym, wyznaczając wartości błędu pomiaru i efektywnej liczby bitów. Wykazano mniejszą wartość błędu i większą wartość efektywnej liczby bitów dla metody wykorzystującej dwa przedziały między-impulsowe.
Methods for processing a frequency-modulated pulse signal are presented in this paper. The methods allow acquiring information about the frequency of a pulse signal with constant sampling frequency. These methods, depending on the time instant for which the measurement result is determined, can be divided into two groups. In measurements on-line the measured value is determined based only on the position of pulses preceding the moment of measurement. The method in which the measured value is determined from the last period and that in which the measured value is determined from extrapolation of two last periods (Fig. 1) are described. In measurements off-line, first there is saved the location of all pulses in the time of recording, and after there is determined the value measured in the assumed moments of the measurement. Therefore, in this case the measured value is determined not only by the position of pulses before the moment of measurement, but also those occurring after this time. The method in which the measured value is determined from the current period and that in which the measured value is determined from interpolation of two periods (Fig. 2) are described in the paper. The accuracy of conversion is determined by a relative error or the number of bits, and thus by the resolution. The noise added to the useful signal has a significant impact on the processing accuracy in real measurements. Therefore the ENOB (Effective Number of Bits), the number of digital signal bits above the noise, is more useful than the resolution. The paper presents examples of simulation results for speed measurements (Tables 1, 2). As it can be seen from the results, increase in the standard generator frequency allows increasing the effective number of bits only to a certain limit. Further increase in the frequency does not increase the ENOB value due to the noise being a result of the method used.

Źródło:

Pomiary Automatyka Kontrola; 2013, R. 59, nr 4, 4; 357-359
0032-4140

Pojawia się w:

Pomiary Automatyka Kontrola

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 92.

Tytuł:

Noise Annoyance Caused by Amplitude Modulated Sounds Resembling the Main Characteristics of Temporal Wind Turbine Noise

Autorzy:

Hafke-Dys, H.
Preis, A.
Kaczmarek, T.
Biniakowski, A.
Kleka, P.

Powiązania:

https://bibliotekanauki.pl/articles/177437.pdf

Data publikacji:

2016

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

wind turbines amplitude modulation
noise annoyance
modulacja amplitudy turbin wiatrowych
uciążliwości hałasu

Opis:

Annoyance ratings for artificially created noises, resembling the main characteristics of temporal wind turbine noise, were studied by means of a listening experiment involving 21 participants with normal hearing. Three types of stimuli were examined: broadband noise (−4 dB/octave), noise generated by moving cars, and narrowband noise. All stimuli had the sound level fluctuations typical for wind turbine noise. The magnitude of the sound level fluctuations was measured in a quantitative way, by using the characteristics of amplitude modulated sound: modulation rate and modulation depth. Our aim was to examine how the modulation rate and the modulation depth influence the noise annoyance assessment of broadband and narrowband amplitude modulated noises. Three different modulation rates, 1, 2 and 4 Hz, and sound level fluctuations (a measure of the modulation depth), 3, 6, 9 dB, were applied to each type of stimuli (with exception of noise generated by the moving cars) and investigated. The participants in the listening experiment were presented with sound stimuli in laboratory conditions and asked to rate their annoyance on a numerical scale. The results have shown a significant difference between the investigated conditions. The effect was particularly strong between the annoyance judgments of different types of noise (narrow and broadband), and modulated versus unmodulated noises. Temporal fluctuations occurring in wind turbine noise are very pertinent to the perception of annoyance and could be responsible for its being a relatively annoying noise source. The obtained results were discussed and compared to the typical modulation rates and level changes that occur in recordings of real wind turbine noise.

Źródło:

Archives of Acoustics; 2016, 41, 2; 221-232
0137-5075

Pojawia się w:

Archives of Acoustics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 93.

Tytuł:

Quasi-analytic multidimensional signals

Autorzy:

Hahn, S. L.
Snopek, K. M.

Powiązania:

https://bibliotekanauki.pl/articles/201583.pdf

Data publikacji:

2013

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

analytic complex and hypercomplex signals
polar representation
modulation techniques
lower rank signals

Opis:

In a recent paper, the authors have presented the unified theory of n-dimensional (n-D) complex and hypercomplex analytic signals with single-orthant spectra. This paper describes a specific form of these signals called quasi-analytic. A quasi-analytic signal is a product of a n-D low-pass (base-band) real (in general non-separable) signal and a n-D complex or hypercomplex carrier. By a suitable choice of the carrier frequency, the spectrum of a low-pass signal is shifted into a single orthant of the Fourier frequency space with a negligible leakage into other orthants. A measure of this leakage is defined. Properties of quasi-analytic signals are studied. Problems of polar representation of quasi-analytic signals and of its lower rank representation are discussed.

Źródło:

Bulletin of the Polish Academy of Sciences. Technical Sciences; 2013, 61, 4; 1017-1024
0239-7528

Pojawia się w:

Bulletin of the Polish Academy of Sciences. Technical Sciences

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 94.

Tytuł:

Single-source three-phase switched-capacitor-based MLI

Autorzy:

Jena, Kasinath
Gupta, Krishna Kumar
Bhatnagar, Pallavee
Jain, Sanjay K.
Stala, Robert
Waradzyn, Zbigniew
Piróg, Stanisław
Penczek, Adam
Mondzik, Andrzej
Skała, Aleksander

Powiązania:

https://bibliotekanauki.pl/articles/2175942.pdf

Data publikacji:

2022

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

multilevel inverter
switched capacitor
multicarrier pulse width modulation
cost function
ANPC inverter

Opis:

This article proposes a novel three-phase inverter based on the concept of switched capacitors (SCs), which uses a single DC source. A three-phase, seven-level line-to-line output voltage waveform is synthesised by the proposed topology, which includes eight switches, two capacitors, and one diode per phase leg. The proposed topology offers advantages in terms of inherent voltage gain, lower voltage stresses on power switches, and a reduced number of switching components. Additionally, the switched capacitors are self-balanced, thereby eliminating the need for a separate balancing circuit. The proposed structure and its operating principle, the self-balancing mechanism of the capacitors, and the control strategy are all thoroughly explained in the article. The proposed topology has also been compared with some recent SC topologies. Lastly, the proposed topology has been shown to be feasible through simulation and experimentation.

Źródło:

Power Electronics and Drives; 2022, 7, 42; 197--209
2451-0262
2543-4292

Pojawia się w:

Power Electronics and Drives

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 95.

Tytuł:

Precyzyjny, konfigurowalny przetwornik analogowo-cyfrowy implementowany w układzie FPGA
Precision, configurable A/D converter implemented in FPGA device

Autorzy:

Radomski, T.
Pełka, R.

Powiązania:

https://bibliotekanauki.pl/articles/155696.pdf

Data publikacji:

2007

Wydawca:

Stowarzyszenie Inżynierów i Techników Mechaników Polskich

Tematy:

modulacja delta-sigma
FPGA
przetwornik A/C
delta-sigma modulation
A/D converter

Opis:

W artykule przedstawiono konstrukcję przetwornika analogowo-cyfrowego zaprogramowanego w układzie FPGA Virtex-4. Przetwornik zbudowano w oparciu o modulator delta-sigma pierwszego rzędu i kompa-rator typu LVDS (ang. low voltage differential signaling). Po przebadaniu przetwornika w celu określenia możliwych błędów zostały zaproponowane metody i układy jego korekcji. Zmodyfikowany przetwornik został przedstawiony w artykule. Przedstawiony projekt przetwornika z powodzeniem można zastosować w dowolnym układzie programowalnym wyposażonym w wejścia różnicowe typu LVDS. W artykule podano parametry przetwornika, takie jak rozdzielczość, liniowość, ilość zajmowanych zasobów, przedstawiono zakres zastosowań. Niniejsza publikacja przedstawia szczegółową analizę przetwornika pod kątem osiągnięcia jak największej dokładności i jednocześnie przedstawia w jaki sposób praktycznie go wykorzystać.
In the article we present the architecture of A/D converter implemented in FPGA Virtex-4 device. The converter was built upon of the first order delta-sigma modulator and LVDS (low voltage differential signaling) comparator and examined about possible errors. After analysis of the methods and correction blocks of converter the modified converter was presented. There is a great possibility to use investigated converter in every type of programmable devices with LVDS inputs. The parameters of the examined converter, for example resolution, linearity, used recourses and the range of application was presented. This publication presents the converter analysis in the possibility to achieve the biggest accuracy and in the same time how to use it in practice.

Źródło:

Pomiary Automatyka Kontrola; 2007, R. 53, nr 7, 7; 9-11
0032-4140

Pojawia się w:

Pomiary Automatyka Kontrola

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 96.

Tytuł:

Stanowisko do badania i pomiarów parametrów transmicji wielonośnej z prekomensacją przeników zdalnych
Measurement system for parameters evaluation of multi tone modulation with far-end crosstalk precompensation

Autorzy:

Turcza, P.

Powiązania:

https://bibliotekanauki.pl/articles/156182.pdf

Data publikacji:

2007

Wydawca:

Stowarzyszenie Inżynierów i Techników Mechaników Polskich

Tematy:

modulacja wielonośna
modem ADSL
przeniki zdalne
multicarrier modulation
ADSL modem
far-end crosstalk

Opis:

Artykuł prezentuje wykonane stanowisko do badania i pomiarów parametrów transmisji wektorowej w systemie ADSL. Pozwala ono na sprzętową realizację transmisji wektorowej w kierunku od centrali do abonenta z użyciem 4 linii ADSL. Taki typ transmisji pozwala na prekompensację przeników występujących podczas transmisji w kablu wieloparowym.
The paper describes system for evaluation and parameters measurement of vectorized ADSL transmission. Downstream transmission using 4 lines in vectored mode in ADSL standart is supported. Vectored transmission enables precompensation of crosstalk occuring between neighboring pairs in data cable.

Źródło:

Pomiary Automatyka Kontrola; 2007, R. 53, nr 9 bis, 9 bis; 146-149
0032-4140

Pojawia się w:

Pomiary Automatyka Kontrola

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 97.

Tytuł:

Application of the FPAA to Sample Input Signal for Laboratory Exercise: Pulse Amplitude Modulation

Autorzy:

Grzechca, Damian
Chruszczyk, Lukas

Powiązania:

https://bibliotekanauki.pl/articles/227335.pdf

Data publikacji:

2020

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

field programmable analog array (FPAA)
signal processing
pulse amplitude modulation (PAM)
student laboratory

Opis:

This paper presents exemplary exercise on the fundamentals of signal processing course which is offered for second year bachelor level students. Application of Field Programmable Analog Array (FPAA) for pulse amplitude modulation (PAM) exercise is described with signal processing laboratory. There are presented two methods for implementing PAM modulation and demodulation technique in FPAA module. Example configuration files are available form Authors’ web site.

Źródło:

International Journal of Electronics and Telecommunications; 2020, 66, 1; 25-28
2300-1933

Pojawia się w:

International Journal of Electronics and Telecommunications

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 98.

Tytuł:

Ergodic Channel Capacity of PPM-Coded Optical MIMO Communications Under Combined Effects

Autorzy:

Cao, Minghua
Zhang, Yue
Kang, Zhongjiang
Wang, Huiqin

Powiązania:

https://bibliotekanauki.pl/articles/1844525.pdf

Data publikacji:

2021

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

atmospheric channel
ergodic channel capacity
pulse position modulation
spatial correlation
optical wireless communication

Opis:

The ergodic channel capacity of wireless optical multiple-input multiple-output (MIMO) system with pulse position modulation (PPM) is investigated. The combined effects of atmospheric turbulence, atmospheric attenuation, pointing error and channel spatial correlation are taken into consideration. The expression of ergodic channel capacity is derived, and is further performed by Wilkinson approximation method for simplicity. The simulation results indicated that the strong spatial correlation has the greatest influence on the ergodic channel capacity, followed by pointing errors and atmospheric turbulence. Moreover, the ergodic channel capacity growth brought by space diversity only performs well under independent and weakly correlated channels. Properly increasing the size and spacing of the receiving apertures is an effective means of effectively increasing the ergodic channel capacity.

Źródło:

International Journal of Electronics and Telecommunications; 2021, 67, 3; 431-436
2300-1933

Pojawia się w:

International Journal of Electronics and Telecommunications

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 99.

Tytuł:

Dimming control schemes combining IEEE 802.15.7 and SC-LPPM modulation schemes with an adaptive M-QAM OFDM for indoor LOS VLC systems

Autorzy:

Mohammed, Nazmi A.
Badawi, Kareem A.
Khalaf, Ashraf A. M.
El-Rabaie, S.

Powiązania:

https://bibliotekanauki.pl/articles/1818236.pdf

Data publikacji:

2020

Wydawca:

Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich

Tematy:

visible light communication
sub-carrier pulse position modulation
lightning topologies
bit error rate

Opis:

The presented work proposes a new dimming control schemes for indoor visible light communication which combines variable pulse-position modulation, colour shift keying as key schemes of IEEE 802.15.7 standard, and sub carrier-pulse-position modulation as a pulse-position modulation variant with orthogonal frequency division multiplexing. These schemes are then compared with traditional merging schemes utilizing pulse-width modulation and multiple pulse-position modulation with m-ary quadrature amplitude modulation OFDM. The proposed schemes are investigated in a typical room with a different lighting layout (i.e., distinctive and uniform lighting layout), followed by an illumination investigation to evaluate the performance of the proposed schemes, especially the enhanced achieved data rates, and to determine their limitations as reliable visible light communication systems that can satisfy both communication and illumination requirements.

Źródło:

Opto-Electronics Review; 2020, 28, 4; 203--212
1230-3402

Pojawia się w:

Opto-Electronics Review

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 100.

Tytuł:

Terahertz response of CdTe/Cd1-xMgxTe modulation-doped multiple quantum wells

Autorzy:

Łusakowski, Jerzy
Frączak, Andrzej
Grymuza, Mikołaj
Imos, Eryk
Siemaszko, Adam
Solarska, Wiktoria
Woyciechowska, Aniela
Zaremba, Maciej
Zdunek, Rafał
Karpierz, Krzysztof
Adamus, Zbigniew
Słupiński, Tomasz
Wojtowicz, Tomasz

Powiązania:

https://bibliotekanauki.pl/articles/2204183.pdf

Data publikacji:

2023

Wydawca:

Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich

Tematy:

terahertz spectroscopy
Shubnikov-de Haas oscillations
modulation-doped multiple CdTe-based quantum wells

Opis:

Terahertz (THz) transmission, photoresistance, and electrical conductivity experiments were carried out at 4.2 K on a sample with modulation-doped CdTe/Cd1-xMgxTe multiple quantum wells. The measurements were carried out as a function of a magnetic field up to 9 T and a radiation frequency between 0.1 and 0.66 THz. A broad minimum in the transmission curve was observed at magnetic fields corresponding to the cyclotron resonance at given THz frequency which was followed at larger fields by an oscillatory signal, periodic in ˉˡ. Shubnikov-de Haas oscillations were observed in magnetoconductivity and in photoresistance. Each of these experimental signals revealed the same electron concentration equal to (1.01 ± 0.03) ∙10ˡ² cmˉ². THz spectroscopy results are compared with data obtained on a single quantum well and are discussed from the point of view of using such multiple quantum wells as THz optical elements.

Źródło:

Opto-Electronics Review; 2023, 31, 2; art. no. e144600
1230-3402

Pojawia się w:

Opto-Electronics Review

Dostawca treści:

Biblioteka Nauki

/5

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