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Wyszukujesz frazę "modulation" wg kryterium: Temat


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
Artykuł
Tytuł:
Impact of Finite-Sized Aperture on the Performance of Differential Multihop DF-FSO Network
Autorzy:
Agarwal, Deepti
Yadav, Poonam
Powiązania:
https://bibliotekanauki.pl/articles/2200711.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
differencial modulation
K-distribution
Free space optics (FSO)
Average bit error rate (BER)
Decode and forward relaying
pointing error
Opis:
This paper investigates the differential binary modulation for decode-and-forward (DF) based relay-assisted free space optical (FSO) network under the effect of strong atmospheric turbulence together with misalignment error (ME). The atmospheric fading links experience K-distributed turbulence. First we derive novel closed form expression for average bit error rate (BER) and outage probability (OP) in terms of Meijer’s G function. Further, the OP of differential DF-FSO system with multiple relays is derived. We also analyze the asymptotic performance for the sake of getting the order of diversity and the coding gain. The power allotment term is utilized to examine the effect of different power allotment techniques on BER and OP. The simulation results have been used to validate the derived analytical results.
Źródło:
International Journal of Electronics and Telecommunications; 2022, 68, 4; 807--813
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
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
Artykuł
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
Artykuł
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
Artykuł
Tytuł:
Generalized space vector control for current source inverters and rectifiers
Autorzy:
Anitha Roseline, J.
Senthil Kumaran, M.
Rajini, V.
Powiązania:
https://bibliotekanauki.pl/articles/140525.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
current source rectifiers (CSR)
current source inverters (CSI)
current source multilevel inverter (CSMLI)
space vector pulse width modulation (SVPWM)
Opis:
Current source inverters (CSI) is one of the widely used converter topology in medium voltage drive applications due to its simplicity, motor friendly waveforms and reliable short circuit protection. The current source inverters are usually fed by controlled current source rectifiers (CSR) with a large inductor to provide a constant supply current. A generalized control applicable for both CSI and CSR and their extension namely current source multilevel inverters (CSMLI) are dealt in this paper. As space vector pulse width modulation (SVPWM) features the advantages of flexible control, faster dynamic response, better DC utilization and easy digital implementation it is considered for this work. This paper generalizes SVPWM that could be applied for CSI, CSR and CSMLI. The intense computation involved in framing a generalized space vector control are discussed in detail. The algorithm includes determination of band, region, subregions and vectors. The algorithm is validated by simulation using MATLAB /SIMULINK for CSR 5, 7, 13 level CSMLI and for CSR fed CSI.
Źródło:
Archives of Electrical Engineering; 2016, 65, 2; 235-248
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Implementation of PID on PIC24F series microcontroller for speed control of a DC motor using MPLAB and Proteus
Autorzy:
Aslam, S.
Hannan, S.
Sajjad, U.
Zafar, W.
Powiązania:
https://bibliotekanauki.pl/articles/102984.pdf
Data publikacji:
2016
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
proportional integral derivative controller
pulse width modulation (PWM)
linear quadratic regulator
peripheral interface controller
MPLAB
proteus
duty cycle
Opis:
Speed control of a DC motor is critical in most industrial systems where accuracy and protection are of essence. This paper presents simulations of Proportional Integral Derivative Controller (PID) on a 16-bit PIC 24F series microcontroller for speed control of a DC motor in the presence of load torque. The PID gains have been tuned by Linear Quadratic Regulator (LQR) technique and then it is implemented on a microcontroller using MPLAB, and finally simulated for speed control of a DC motor in Proteus Virtual System Modeling (VSM) software. Proteus has built in feature to add load torque to a DC motor so simulation results have been presented in three cases speed of DC motor is controlled without load torque, with 25% load torque and with 50% load torque. In all three cases PID effectively controls the speed of DC motor with minimum steady state error.
Źródło:
Advances in Science and Technology. Research Journal; 2016, 10, 31; 40-50
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
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
Artykuł
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
Artykuł
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
Artykuł
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
Artykuł
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
Artykuł
Tytuł:
Increasing the specific rate of continuous phase modulation signals
Zwiększenie prędkości właściwej sygnałów o modulacji częstotliwościowej z ciągłą fazą
Autorzy:
Banket, Victor
Manakov, Sergei
Powiązania:
https://bibliotekanauki.pl/articles/407692.pdf
Data publikacji:
2019
Wydawca:
Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
Tematy:
continuous-phase modulation
specific rate
Walsh-Barker composite sequence
performance indicators of a transmission system
modulacja częstotliwościowa z ciągłą fazą
prędkość właściwa
sekwencja złożona Walsha-Barkera
wskaźnik wydajności systemu przesyłowego
Opis:
A method has been developed for increasing the specific rate of frequency modulation signals with a continuous phase based on the use of the properties of composite Walsh-Barker sequences. The proposed method is applicable for multi-position signals. Simultaneously, the tasks of synchronization and registration of processing results are solved. The increase in the efficiency of digital signal transmission systems is theoretically justified.
Opracowano i zbadano eksperymentalnie metodę zwiększania prędkości właściwej sygnałów modulacji częstotliwościowej z ciągłą fazą opartą na wykorzystaniu właściwości sekwencji złożonych Walsha-Barkera. Zaproponowana metoda może być zastosowana do sygnałów wielopozycyjnych. Jednocześnie rozwiązywane są zadania synchronizacji i rejestracji wyników przetwarzania. Wzrost wskaźników wydajności systemów cyfrowego przesyłania sygnałów jest teoretycznie uzasadniony.
Źródło:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska; 2019, 9, 1; 57-60
2083-0157
2391-6761
Pojawia się w:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska
Dostawca treści:
Biblioteka Nauki
Artykuł
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
Artykuł
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
Artykuł

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