Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

English (EN)·Polski (PL)·Yкраїнський (UK)
Przejdź do strony domowej biblioteki Centralna Biblioteka Wojskowa Link otwiera się w nowym oknie Logo biblioteki Prolib Integro - strona głównaCentralna Biblioteka Wojskowa

Wyszukujesz frazę "high-frequency" wg kryterium: Wszystkie pola

  Lista filtrów
Wyrównaj
Wyświetlanie 1-100 z 237
Tytuł:
Gigacycle fatigue at high-frequency loading
Autorzy:
Bokůvka, O.
Nový, F.
Chalupová, M.
Nicoletto, G.
Powiązania:
https://bibliotekanauki.pl/articles/329118.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Tematy:
materiał strukturalny
zmęczenie materiału
właściwości
gigacycle fatigue
high-frequency loading
structural material
Opis:
In this work there are information about an experimental high-frequency testing apparatus and specimens enable to determine the fatigue properties in the ultra-high-cycles region (gigacycle fatigue) and the rates of long fatigue cracks growth in near-threshold areas. The selected characteristic examples about fatigue resistance of various structural materials are presented. The results are utilizable in the field of material engineering and threshold states of material.
Źródło:
Diagnostyka; 2008, 4(48); 53-56
1641-6414
2449-5220
Pojawia się w:
Diagnostyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Laboratory model of high frequency sonar
Autorzy:
Buszman, K.
Szymczak, W.
Powiązania:
https://bibliotekanauki.pl/articles/331519.pdf
Data publikacji:
2008
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
laboratory model
sonars
hydroacoustic
Opis:
This article contains the construction and laboratory application of high frequency sonar model. In view of working in laboratory conditions, they must be fulfilled succeeding parametric cases: very narrow beam, low level of side lobes and low acoustic power of transmitted impulse sounding. When all of these conditions are fulfilled, it makes possible the explanation to students some terms like depth, angular resolution and making clear, that water is the best environment to acoustic waves transmission. Furthermore, there is used automatic component, namely rotary antenna, which make possibility to precision area scanning.
Źródło:
Hydroacoustics; 2008, 11; 39-46
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-Frequency Susceptibilities of Inhomogeneous Magnetoelastic Medium
Autorzy:
Ignatchenko, V. A.
Erementchouk, M. V.
Powiązania:
https://bibliotekanauki.pl/articles/1964778.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.30.+d
75.80.+q
61.43.Er
Opis:
A response of an inhomogeneous magnetoelastic medium with the zero-mean magnetostriction to high-frequency elastic and electromagnetic fields is studied. It is shown that diagonal susceptibilities have the resonance anomalies in the vicinity of the frequency of the magnetoelastic resonance, while the coefficients of crossing excitations are equal to zero.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 415-418
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-Frequency Noise Sources in Quantum Wells
Autorzy:
Ardaravičius, L.
Liberis, J.
Matulionis, A.
Powiązania:
https://bibliotekanauki.pl/articles/2035523.pdf
Data publikacji:
2002-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.Ht
72.70.+m
73.40.Kp
Opis:
Hot-electron noise is investigated for InGaAs and InAs quantum wells containing a two-dimensional electron gas channel in a pulsed electric field applied parallel to the interfaces. Noise sources resulting from hot-electron "thermal" motion, electron temperature fluctuations, and real-space transfer are observed. The experimental results on hot-electron "thermal" noise are used to estimate energy relaxation time in the field range where other sources do not play any important role. Measurements of noise anisotropy in the plane of electron confinement are used to discuss real-space-transfer noise. High-frequency noise technique is used to study hot-electron trapping, and trap location in InAlAs/InGaAs/InAlAs heterostructure channels is determined.
Źródło:
Acta Physica Polonica A; 2002, 102, 2; 329-335
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Overheat protection circuit for high frequency processors
Autorzy:
Frankiewicz, M.
Kos, A.
Powiązania:
https://bibliotekanauki.pl/articles/200992.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
PTAT
overheat
CMOS
VLSI
full-custom design
Opis:
The paper describes design and structure of the overheat protection circuit based on the PTAT sensors. The digital core of the system is driven by a 3-bit information generated by the structure. As a result, behaviour of the core differs for each temperature. The circuit was designed in LF CMOS 0.15 ěm technology using full-custom technique. The presented paper focuses especially on the structure of the overheat protection circuit and simulations results of the functional blocks of the system. Layout and some parameters of the circuit are also considered.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2012, 60, 1; 55-59
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of low and high frequency fatigue tests
Autorzy:
Vasko, A.
Belan, J.
Kucharikova, L.
Powiązania:
https://bibliotekanauki.pl/articles/111844.pdf
Data publikacji:
2017
Wydawca:
Stowarzyszenie Menedżerów Jakości i Produkcji
Tematy:
fatigue test
low frequency cyclic loading
high frequency cyclic loading
nodular cast iron
test zmęczeniowy
cykliczne obciążenie niskoczęstotliwościowe
cykliczne obciążenie o wysokiej częstotliwości
żeliwo sferoidalne
Opis:
The paper presents the results of low and high frequency fatigue tests carried out on nodular cast iron. The specimens of synthetic nodular cast irons from three different melts were studied in the high cycle fatigue region (from 105 to 108 cycles) using fatigue experimental equipments for low and high frequency cyclic loading. Low frequency fatigue tests were carried out at frequency f ≈ 120 Hz using the fatigue experimental machine Zwick/Roell Amsler 150HFP 5100; high frequency fatigue tests were carried out at frequency f ≈ 20 kHz using the ultrasonic fatigue testing device KAUP-ZU. Both fatigue tests were realised at sinusoidal cyclic push-pull loading (stress ratio R = –1) at ambient temperature (T = 20 ± 5 °C).
Źródło:
Production Engineering Archives; 2017, 17; 15-18
2353-5156
2353-7779
Pojawia się w:
Production Engineering Archives
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High frequency ship radiated noise in shallow water
Autorzy:
Carbó, R.
Molero, A. C.
Powiązania:
https://bibliotekanauki.pl/articles/332483.pdf
Data publikacji:
1999
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The stationary acoustic field in a two pIane parallel medium, sea surface and sea boftom, when a source near to the sea surface radiates, is characterized by the thickness of the medium and the reflectivity of the boundary surfaces. It is known that the maxima and minima of pressure are produced at same given depths depending on the radiated frequency and distance. Considering the ship noise as an acoustical source, the frequency spectrum of the acoustic pressure at certain depth, is nof only the spectrum of the acoustic ship noise but it is also modified by the wave field originated by consecutive reflections at the boundary surfaces. As a consequence, over the free field spectrum of (he ship noise, a series of minima appears. The corresponding frequencies are those for which the receiver is located at the nodes of the stationary wave field.
Źródło:
Hydroacoustics; 1999, 2; 213-218
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thick Film Transducers for High Frequency Coded Ultrasonography
Autorzy:
Nowicki, A.
Lewandowski, M.
Wójcik, J.
Tymkiewicz, R.
Lou-Moller, R.
Wolny, W.
Zawada, T.
Powiązania:
https://bibliotekanauki.pl/articles/176939.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
transducers
thick film
high frequency ultrasound
pulse compression
Golay codes
Opis:
Recently a new technology of piezoelectric transducers based on PZT thick film has been developed as a response to a call for devices working at higher frequencies suitable for production in large numbers at low cost. Eight PZT thick film based focused transducers with resonant frequency close to 40 MHz were fabricated and experimentally investigated. The PZT thick films were deposited on acoustically engineered ceramic substrates by pad printing. Considering high frequency and nonlinear propagation it has been decided to evaluate the axial pressure field emitted (and reflected by thick metal plate) by each of concave transducer differing in radius of curvature – 11 mm, 12 mm, 15 mm, 16 mm. All transducers were activated using AVTEC AVG-3A-PS transmitter and Ritec diplexer connected directly to Agilent 54641D oscilloscope. As anticipated, in all cases the focal distance was up to 10% closer to the transducer face than the one related to the curvature radius. Axial pressure distributions were also compared to the calculated ones (with the experimentally determined boundary conditions) using the angular spectrum method including nonlinear propagation in water. The computed results are in a very good agreement with the experimental ones. The trans- ducers were excited with Golay coded sequences at 35–40 MHz. Introducing the coded excitation allowed replacing the short-burst transmission at 20 MHz with the same peak amplitude pressure, but with almost double center frequency, resulting in considerably better axial resolution. The thick films exhibited at least 30% bandwidth broadening comparing to the standard PZ 27 transducer, resulting in an increase in matching filtering output by a factor of 1.4–1.5 and finally resulting in a SNR gain of the same order.
Źródło:
Archives of Acoustics; 2011, 36, 4; 945-954
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal Characterization of High-Frequency Flyback Power Transformer
Autorzy:
Kasikowski, R.
Gołaszewski, J.
Więcek, B.
Farrer, M.
Powiązania:
https://bibliotekanauki.pl/articles/114581.pdf
Data publikacji:
2015
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
IR thermography
power losses
H-F flyback transformer
thermal impedance
Opis:
This paper presents preliminary thermographic measurements and a simple thermal analysis of power losses in high-frequency (H-F) transformers used in AC-DC power converters. The analysis is based on complex thermal impedance and time constant distribution. The main aim of this research was to consider quantitatively the contribution of different power losses in the H-F transformer, including fringing flux effect.
Źródło:
Measurement Automation Monitoring; 2015, 61, 6; 237-241
2450-2855
Pojawia się w:
Measurement Automation Monitoring
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High Frequency Traders - destrukcyjna czy poprawiająca funkcjonowanie innowacja rynku finansowego?
High Frequency Traders - Destructive or Improving Innovation of Capital Market?
Autorzy:
Gorczyńska, Alina
Powiązania:
https://bibliotekanauki.pl/articles/593602.pdf
Data publikacji:
2014
Wydawca:
Uniwersytet Ekonomiczny w Katowicach
Tematy:
Innowacje
Inwestor giełdowy
Programy komputerowe
Rynki finansowe
Computer programs
Financial markets
Innovations
Stock exchange investor
Opis:
Technological advances and legal conditions in investments in the financial market have created many innovations at the turn of the century. One of the innovations in the financial market are High Frequency Traders (HFT) that have existed since 2005, and since then rapidly have developed its activity, affecting functioning of financial market. As the positive effects of their activities is acknowledged: possibility to increase liquidity and transparency of financial market, as well as enhancing competition between trading venues, which in turn can lead to lower transaction costs. However, the functioning HFT is also connected with dangers associated with the possibility of a decrease in liquidity on the market (in terms of variation), the collapse of the market as a result of a failure or an error on the handling of orders and restriction of competition among financial market investors.
Źródło:
Studia Ekonomiczne; 2014, 186 cz 2; 188-187
2083-8611
Pojawia się w:
Studia Ekonomiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An accurate prediction of high-frequency circuit behaviour
Autorzy:
Yoshitomi, S.
Kimijima, H.
Kojima, K.
Kokatsu, H.
Powiązania:
https://bibliotekanauki.pl/articles/308807.pdf
Data publikacji:
2005
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
electro-magnetic simulation
SPICE
circuit test structure
RF CMOS
EKV2.6-MOS model
spiral inductor
CMOS VCO
Opis:
An accurate way to predict the behaviour of an RF analogue circuit is presented. A lot of effort is required to eliminate the inaccuracies that may generate the deviation between simulation and measurement. Efficient use of computer-aided design and incorporation of as many physical effects as possible overcomes this problem. Improvement of transistor modelling is essential, but there are many other unsolved problems affecting the accuracy of RF analogue circuit modelling. In this paper, the way of selection of accurate transistor model and the extraction of parasitic elements from the physical layout, as well as implementation to the circuit simulation will be presented using two CMOS circuit examples: an amplifier and a voltage controlled oscillator (VCO). New simulation technique, electro-magnetic (EM)-co-simulation is introduced.
Źródło:
Journal of Telecommunications and Information Technology; 2005, 1; 47-62
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High frequency metrology for intracardiac ablation: in-vivo results
Autorzy:
Rouane, A.
Bru, P.
Powiązania:
https://bibliotekanauki.pl/articles/221888.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
impedance matching
voltage measurement cell
current measurement cell
high frequency energy
Opis:
Cardiac Radiofrequency (RF) ablation is a commonly used clinical procedure for treating many cardiac arrhythmias. However, the efficacy of RF ablation may be limited by two factors: small ventricular lesions and impedance rise, leading to coagulum formation and desiccation of tissue. In this paper, a high frequency (HF) energy ablation system operating at 27.12 MHz based on an automated load matching system was developed. A HF energy matched probe associated to the automated impedance matching device ensures optimal transfer of the energy to the load. The aim of this study was to evaluate this energy for catheter ablation of the atrioventricular junction. In vivo studies were performed using 10 sheep to characterize the lesions created with the impedance matching system. No cardiac perforation was noted. No thrombus was observed at the catheter tip. Acute lesions ranged from 3 to 45 mm in diameter (mean šSD = 10.3š10) and from 1 to 15 mm in depth (6.7š3.9), exhibiting a close relationship between HF delivered power level and lesion size. Catheter ablation using HF current is feasible and appears effective in producing a stable AV block when applied at the AV junction and large myocardial lesions at ventricular sites.
Źródło:
Metrology and Measurement Systems; 2012, 19, 3; 603-610
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of high frequency vibration of tram monobloc wheel
Autorzy:
Sowiński, B.
Powiązania:
https://bibliotekanauki.pl/articles/224110.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
noise
tram wheel
FEM analysis
hałas
koła
tramwaj
analiza MES
Opis:
European Environmental Agency estimates that about 120 million people in the EU (over 30% of the total population) are exposed to traffic noise above 55 Ldn dB. It is estimated that 10% of the EU population is exposed to noise associated with the rail traffic. The two main sources of traffic noise comes from vehicles engines and the noise generated in the contact between the wheel and the road. In the latter the considerable part the noise is due to phenomena occurring in a wheel tram – rail system. Therefore, the problem of reducing the noise generated by railway vehicles is the subject of many studies, both experimental and theoretical. Commonly used wheel trams so called "resilient wheels" are equipped with layer made of a resilient material, e.g. rubber, between the tread and the wheel disc. But the monobloc tram wheel is the standard design against which should be carried out the studies on reduction of noise in wheel-rail system. This paper presents the results of calculations related to eigenforms, eigenfrequencies and Frequency Response Function of a three-dimensional model of a monobloc tram wheel. The calculations were carried out using the finite element method. Vibration analysis was performed for the range to 5 kHz. Analysis carried out has shown that the wheel tread plays a more important role in the generation of high-frequency vibrations.
Źródło:
Archives of Transport; 2016, 39, 3; 65-75
0866-9546
2300-8830
Pojawia się w:
Archives of Transport
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
PC-based high frequency imaging system with coded excitation
Autorzy:
Lewandowski, M.
Nowicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/331588.pdf
Data publikacji:
2008
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
coded transmission
SNR
FPGA
Opis:
Coded transmission is a technique that gives significant improvement in SNR and enables higher contrast imaging without sacrificing the resolution. A novel HF (20-35 MHz) ultrasound real-time imaging system for research and evaluation of the coded transmission was developed. The digital programmable coder-digitizer module based on the field programmable gate array (FPGA) chip supports arbitrary waveform coded transmission and RF echoes sampling up to 200 MSPS. A novel balanced software architecture supports real-time RF processing and display at rates up to 30 frames/sec. The system was used to gather data for sine burst and 16-bit Golay code excitation using a single element scanning head with thick film focused spherical transducer 25 MHz center frequency and 56% system bandwidth. SNR gain for the Golay codes (referenced to single burst) of 15 dB for 20 MHz and 16 dB for 35 MHz were obtained. In water the axial resolution for both single burst and the Golay codes was the same FWMH=20 ns at 20 MHz and FWMH=15 ns at 35 MHz. The presented system is a practical and low cost implementation of coded excitation technique in HF ultrasound imaging.
Źródło:
Hydroacoustics; 2008, 11; 239-247
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tinnitus Therapy Based on High-Frequency Linearization Principles - Preliminary Results
Autorzy:
Poremski, T.
Kostek, B.
Powiązania:
https://bibliotekanauki.pl/articles/177726.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
tinnitus
sensorineural hearing loss
tinnitus masking
Tinnitus Retraining Therapy (TRT)
signal quantization
dithering technique
high-frequency linearization
ultrasound dither noise
Opis:
The aim of this work is to present problems related to tinnitus symptoms, its pathogenesis, hypothe- ses on tinnitus causes, and therapy treatment to reduce or mask the phantom noise. In addition, the hypothesis on the existence of parasitic quantization that accompanies hearing loss has been recalled. Moreover, the paper describes a study carried out by the Authors with the application of high-frequency dither having specially formed spectral characteristics. Discussion on preliminary results obtained and conclusions are also contained.
Źródło:
Archives of Acoustics; 2012, 37, 2; 161-170
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-Frequency Power Amplitude Modulators with Class-E Tuned Amplifiers
Autorzy:
Modzelewski, J.
Mikołajewski, M.
Powiązania:
https://bibliotekanauki.pl/articles/307948.pdf
Data publikacji:
2008
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
high-efficiency amplitude modulators
non-ZVS operation
optimum operation
PSpice simulations
suboptimum operation
Opis:
A high-frequency power amplifier used in a drain amplitude modulator must have linear dependence of output HF voltage Vo versus its supply voltage VDD. This condition essential for obtaining low-level envelope distortions is met by a theoretical class-E amplifier with a linear shunt capacitance of the switch. In this paper the influence of non-linear output capacitance of the transistor in the class-E amplifier on its Vo(VDD) characteristic is analyzed using PSPICE simulations of the amplifiers operating at frequencies 0.5 MHz, 5 MHz and 7 MHz. These simulations have proven that distortions of theVo(VDD) characteristic caused by non-linear output capacitance of the transistor are only slight for all analyzed amplifiers, even for the 7 MHz amplifier without the external (linear) shunt capacitance. In contrast, the decrease of power efficiency of the class-E amplifier resulting from this effect can be significant even by 40%
Źródło:
Journal of Telecommunications and Information Technology; 2008, 4; 79-86
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bayesian optimization for solving high-frequency passive component design problems
Autorzy:
Baranowski, Michal
Fotyga, Grzegorz
Lamecki, Adam
Mrozowski, Michal
Powiązania:
https://bibliotekanauki.pl/articles/2173688.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
high-frequency design
machine learning
Bayesian optimization
optymalizacja bayesowska
konstrukcja o wysokiej częstotliwości
nauczanie maszynowe
Opis:
In this paper, the performance of the Bayesian Optimization (BO) technique applied to various problems of microwave engineering is studied. Bayesian optimization is a novel, non-deterministic, global optimization scheme that uses machine learning to solve complex optimization problems. However, each new optimization scheme needs to be evaluated to find its best application niche, as there is no universal technique that suits all problems. Here, BO was applied to different types of microwave and antenna engineering problems, including matching circuit design, multiband antenna and antenna array design, or microwave filter design. Since each of the presented problems has a different nature and characteristics such as different scales (i.e. number of design variables), we try to address the question about the generality of BO and identify the problem areas for which the technique is or is not recommended.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2022, 70, 4; art. no. e141595
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High frequency of doubled haploid plant production in spelt wheat
Autorzy:
Lantos, C.
Jenes, B.
Bona, L.
Cserhati, M.
Pauk, J.
Powiązania:
https://bibliotekanauki.pl/articles/19813.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Opis:
This is the first study to report an efficient anther culture (AC) method for spelt wheat, which has an increasing importance not only in applied research but also in organic farming and changing nutritional standards. In this study, an efficient AC protocol has been described for ‘GK Fehér’ spelt wheat. The number of AC-derived embryolike structures (ELS) was 62.2/100 anthers, from which we were able to regenerate 30.6 green plantlets per 100 anthers. The percentage of green plantlets production was 89.0% among the regenerated plantlets, while the phenomenon of albinism was restricted (3.8/100 anthers). Altogether, from AC of ‘GK Fehér’ 306 green plantlets were produced in vitro and 241 plants were acclimatized to the greenhouse conditions. Based on ploidy level analyses, 83 spontaneous doubled haploid (DH) plants were produced (8.3 DH plants/100 anthers), so the percentage of spontaneous rediploidization was 34.4%. The spontaneous DH plants produced fertile spikes, while a few seeds were harvested from seven partially fertile plants.
Źródło:
Acta Biologica Cracoviensia. Series Botanica; 2016, 58, 2
0001-5296
Pojawia się w:
Acta Biologica Cracoviensia. Series Botanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wysokoczęstotliwościowy falownik napięcia badania symulacyjne
High frequency inverter simulation research
Autorzy:
Judek, S.
Karwowski, K.
Korycki, K.
Soczyński, D.
Powiązania:
https://bibliotekanauki.pl/articles/268280.pdf
Data publikacji:
2005
Wydawca:
Politechnika Gdańska. Wydział Elektrotechniki i Automatyki
Opis:
W opracowaniu przeprowadzono analizę układu bezstykowego przesyłania energii elektrycznej dla stanu ustalonego przy wymuszeniu sinusoidalnym. Obliczenia te oparto na transformatorowym schemacie zastępczym układu cewek powietrznych sprzężonych magnetycznie. Analiza ta umożliwiła określenie struktury i obszaru pracy układu charakteryzującej się maksymalną sprawnością. Następnie przedstawiono wyniki symulacji układu przy zasilaniu przekształtnikowym, z uwzględnieniem modeli rzeczywistych elementów energoelektronicznych. Przedstawione rezultaty wskazują na to, że układ jest w stanie przekazywać energię elektryczną o określonych parametrach również w przypadku dynamicznie zmieniających się jego parametrach, w szczególności współczynnika sprzężenia magnetycznego.
This paper describes a technique, the contactless electrical energy transfer system (CEETS), by which electrical energy may be transmitted, without electrical connection or physical contact, through the large air gap. CEETS is becoming more and more attractive especially for automatic battery charging stations and for energy supply of inductively powered electric vehicles and other movable consumers. Authors presented theoretical and simulation analysis of transformer equivalent circuit with capacitors series and parallel connected to windings. The analysis includes supply via AC voltage source and power electronics converter with invariable and with variable frequency. The calculations are oriented in order to show compensation topology which is characterized greatest efficiency.
Źródło:
Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej; 2005, 21; 125-130
1425-5766
2353-1290
Pojawia się w:
Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Estimation of radial artery reactive response using high frequency ultrasound
Autorzy:
Nowicki, A.
Secomski, W.
Trawiński, Z.
Lewandowski, M.
Trots, I.
Szubielski, M.
Olszewski, R.
Powiązania:
https://bibliotekanauki.pl/articles/332584.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
thick film transducers
atherosclerosis
flow mediated vasodilation
Opis:
Background: There is a growing interest in the application of non-invasive clinical tools allowing one to assess the endothelial function, preceding atherosclerosis. The precision in estimating of the artery Flow Mediated Vasodilation (FMD) using standard 10-12 MHz linear array probes does not exceed 0.2 mm, far beyond that required. Methods: We have introduced a wide-band, high frequency 25-30 MHz, Golay encoded wobbling type imaging to measure dilation of the radial artery instead of the brachial one. 18 young volunteers, and 4 volunteers with cardiac events history, were examined. In the second approach 20 MHz linear scanning combined with 20 MHz pulsed Doppler attached to the linear array was used. The radial artery FMD was normalized using shear rate at the radial artery wall. Results and Conclusions: For the “healthy” group, the FMD resulting from reactive hyperemia response was over 20%; while in the “atherosclerotic” group, the FMD was at least twice as small, not exceeding 10%. The shear rate (SR) normalized FMDSR was in the range from 7.8 to 9.9 in arbitrary units, while in patients with minor cardiac history FMDSR was clearly lower, 6.8 to 7.6. The normalized FMDSR of radial artery RARR can be an alternative to the brachial FMD where the precision of measurements is lower and the diameter dilation does not exceed 7-10%.
Źródło:
Hydroacoustics; 2016, 19; 297-306
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of high-frequency ZVS (zero voltage switched) multiresonant converters
Autorzy:
Szychta, E.
Szychta, L.
Powiązania:
https://bibliotekanauki.pl/articles/393509.pdf
Data publikacji:
2014
Wydawca:
Polskie Stowarzyszenie Telematyki Transportu
Tematy:
resonant circuit
zero voltage switching
multiresonant DC/DC converter
obwód rezonansowy
przełączanie przy zerowym napięciu
wielorezonansowa przetwornica DC/DC
Opis:
The paper presents chosen issues of multiresonant ZVS DC/DC converters for use in transport devices. It provides results of mathematical analysis, simulation and experimental testing of selected multiresonant ZVS DC/DC conversion circuits. The paper explores the theory of the multiresonant DC/DC conversion circuits in consideration of single-transistor topologies. In the end conclusions are presented.
Źródło:
Archives of Transport System Telematics; 2014, 7, 3; 57-63
1899-8208
Pojawia się w:
Archives of Transport System Telematics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Adaptively Selecting Working Frequency to Reduce Disturbances in High Frequency Radar
Autorzy:
Gui, R.
Powiązania:
https://bibliotekanauki.pl/articles/1505197.pdf
Data publikacji:
2011-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
84.40.Xb
Opis:
In high frequency radar, we should avoid noise disturbances in the radar's working-frequency segment. Moreover, the sidelobes of strong targets interfere with the detection of weak targets. A new method based on an adaptive selecting working-frequency is proposed. Frequency spectrum monitor is designed for selecting quiet frequency segment for the radar. Frequency spectrum monitor and the receiver of the radar are arranged to work according to special time periods respectively. So the radar can work in the frequency segments with lower noise disturbances. Moreover, there is no correlation between the noise and the useful echo signal, though the correlation between noises over very short time periods is strong, the noise data produced by frequency spectrum monitor can be exploited effectively. Adjusting system parameters in real-time by adaptive methods can be utilized to reduce noise disturbances. Algorithm based on the properties of crosscorrelation between noise and target is exploited for suppressing sidelobe disturbances of strong targets. Lastly, the feasibility of the methods is verified by processing actual radar data.
Źródło:
Acta Physica Polonica A; 2011, 119, 4; 473-478
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Extended High Frequency Hearing Thresholds in Tinnitus Patients with Normal Hearing
Autorzy:
Ristovska, Lidija
Jachova, Zora
Powiązania:
https://bibliotekanauki.pl/articles/31339952.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
extended high frequency
hearing loss
tinnitus
Opis:
The aim of the study was to compare the extended high-frequency (EHF) hearing thresholds (10–16 kHz) in tinnitus and non-tinnitus ears, in a group of 98 patients with unilateral tinnitus and normal hearing at standard audiometric frequencies, in a 0.125–8 kHz range. It was found that a total of 65 patients (66%) had a hearing loss (a threshold shift >20 dB HL) in the EHF range and the EHF hearing loss occurred more frequently in the tinnitus ear than in the non-tinnitus ear. The data also indicate that the EHF thresholds increased with the patient’s age and were in most patients higher in the tinnitus ear than in the non-tinnitus ear.
Źródło:
Archives of Acoustics; 2022, 47, 4; 449-455
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Predictive speed control of induction drive with high-frequency torsional oscillation
Autorzy:
Serkies, P. J.
Szabat, K.
Dybkowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/97503.pdf
Data publikacji:
2010
Wydawca:
Politechnika Poznańska. Wydawnictwo Politechniki Poznańskiej
Tematy:
induction motor
driveline
two-mass drive system
MPC
Opis:
In the paper issues related to the use of model predictive control (MPC) of the drive system with an elastic coupling and an induction motor are presented. After a short introduction the mathematical model of the driving motor with a vector control structure and the two-mass drive system are described. Then, the idea of the MPC is introduced. Next the exact formulation of the MPC for a two-mass drive system is shown. In the MPC algorithm the constraints of the inner and control variables are taken into consideration. The results obtained in the simulation study confirm the correct work of the investigated structure.
Źródło:
Computer Applications in Electrical Engineering; 2010, 8; 120-131
1508-4248
Pojawia się w:
Computer Applications in Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improving sensitivity of residual current transformers to high frequency earth fault currents
Autorzy:
Czapp, S.
Dobrzyński, K.
Klucznik, J.
Lubosny, Z.
Kowalak, R.
Powiązania:
https://bibliotekanauki.pl/articles/141169.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
current transformers
earth fault currents
electric devices
electromagnetic couplings
high frequency
Opis:
For protection against electric shock in low voltage systems residual current devices are commonly used. However, their proper operation can be interfered when high frequency earth fault current occurs. Serious hazard of electrocution exists then. In order to detect such a current, it is necessary to modify parameters of residual current devices, especially the operating point of their current transformer. The authors proposed the modification in the structure of residual current devices. This modification improves sensitivity of residual current devices when high frequency earth fault current occurs. The test of the modified residual current device proved that the authors’ proposition is appropriate.
Źródło:
Archives of Electrical Engineering; 2017, 66, 3; 485-494
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High frequency vibration monitoring and diagnostics of high-speed pump rolling bearings
Autorzy:
Litvinov, D.
Rudzitis, J.
Powiązania:
https://bibliotekanauki.pl/articles/386219.pdf
Data publikacji:
2008
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
łożysko toczne
analiza drgań
rolling bearing
vibration analysis
Opis:
Evolution of modern industry makes great demands to reliable work of pump equipment with large revolutions number of rotating parts. Under special supervision must be the centrifugal high-speed pumps. One of the major and hardly loaded units of high-speed pump equipment are rolling bearings, therefore it is very important to conduct monitoring and early diagnostics works to find out defects in them. For the high-frequency vibration detection and analysis it is possible to use both stationary and portable systems of monitoring and diagnostics. This diagnostics advantage is early detection of aberration from normal operation of rolling bearings and transition from equipment service and repair on-schedule to real situation service and repair, which is determined on periodic diagnostics results.
Źródło:
Acta Mechanica et Automatica; 2008, 2, 3; 76-79
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Applicability of Different SAW Oscillators Topologies for High Frequency Gas Sensors Construction
Autorzy:
Pasternak, M.
Powiązania:
https://bibliotekanauki.pl/articles/1506822.pdf
Data publikacji:
2010-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
46.35.+z
68.35.Ja
Opis:
In general, there are three possible kinds of surface acoustic wave devices that may be applied for high frequency gas sensor construction: delay lines, one- and two-port resonators. Choice among them depends on individual preferences and sometimes it is the matter of chance. In the paper the key differences among the surface acoustic wave devices important from the gas sensors technology point of view are described.
Źródło:
Acta Physica Polonica A; 2010, 118, 6; 1232-1234
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Statistics of envelope of high frequency ultrasound signal backscattered in human dermis
Autorzy:
Piotrzkowska, H.
Litniewski, J.
Szymańska, E.
Lewandowski, M.
Nowicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/331987.pdf
Data publikacji:
2010
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The scattering of ultrasonic waves depends on the size, shape, acoustical properties and concentration of scatterers in tissue. In these study K distribution of the ultrasound backscatter envelope was used to assess the structural properties of the skin tissue. The custom-designed high frequency ultrasonic scanner was applied to obtain RF B-scans of the skin in vivo at the frequency of 20 ÷ 30MHz. The results are encouraging. The K distribution models the envelope statistics very well. The parameters of the K-distribution, namely, the effective number of scatterers may be useful for the skin characterization.
Źródło:
Hydroacoustics; 2010, 13; 205-214
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-Frequency Trading of agricultural commodities as a source of additional income in agriculture
High Frequency Trading w handlu towarami pochodzenia rolniczego jako źródło dodatkowego dochodu w rolnictwie
Autorzy:
Sporysz, M.
Godula, Ł.
Tabor, S.
Kuboń, M.
Szczuka, M.
Powiązania:
https://bibliotekanauki.pl/articles/94019.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Inżynierii Rolniczej
Tematy:
statistical arbitrage
High Frequency Trading
commodity stock exchange
algorithmic trading
arbitraż statystyczny
giełda towarowa
handel algorytmiczny
Opis:
The paper verifies usefulness of the high frequency trading model developed by Marco Avellaneda and Sasha Stoikov, used in simulation of turnover with futures contract securities of one of agricultural commodities on the selected commodity stock exchange. Accuracy of provided signals of purchase and sale signals was verified on authentic quotations – the futures contract for coffee prices of the London Stock Exchange. Results of ten subsequent session days was analysed in detail. Quality of the assumed investment algorithm was determined with the use of stock exchange ratios: Information Ratio and Maximum Drawdown. A short discussion was conducted, which compared a standard investing method and the analysed model of algorithmic trading. In conclusion, all most important statements and conclusions were made, which confirmed usefulness of the HFT model developed by Marco Avellaneda and Sasha Stoikov for turnover of futures contract securities for agricultural commodities.
W pracy sprawdzono przydatność modelu szybkiego kupna i sprzedaży (High Frequency Trading) Marco Avellanedy i Sashy Stoikov'a, użytego w symulacji obrotu walorami kontraktu terminowego na towar pochodzenia rolniczego na wybranej giełdzie towarowej. Zbadano trafność podawanych sygnałów transakcji kupna i sprzedaży na autentycznych notowaniach - kontrakt terminowy na ceny kawy londyńskiej giełdy papierów wartościowych (London Stock Exchange). Szczegółowo zanalizowano wyniki dziesięciu kolejnych dni sesyjnych. Jakość przyjętego algorytmu inwestycyjnego określono za pomocą wskaźników giełdowych: Information Ratio oraz Maximum Drawdown. Przeprowadzono krótką dyskusję porównującą standardową metodę inwestowania oraz analizowany model handlu algorytmicznego. Na zakończenie zebrano najważniejsze stwierdzenia i wyciągnięto wnioski potwierdzające przydatność modelu HFT Marco Avellanedy i Sashy Stoikov'a do obrotu walorami kontraktów terminowych na towary pochodzenia rolniczego o dużej płynności oraz możliwość jego praktycznego zastosowania.
Źródło:
Agricultural Engineering; 2014, 18, 4; 221-231
2083-1587
Pojawia się w:
Agricultural Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analytical and experimental determination of the parasitic parameters in high-frequency inductor
Autorzy:
Zdanowski, M.
Barlik, R.
Powiązania:
https://bibliotekanauki.pl/articles/200393.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
model of inductor circuit
interlayer capacitance
parallel resonance
litz wire
inductor winding
skin effect
pojemność pośrednia
rezonans równoległy
cewka indukcyjna
Opis:
The paper presents the results of calculations, simulations, and measurements of parasitic capacitance of winding in ferrite inductor suitable for cooperating with 2 kW DC-DC boost converter built using SiC JFET transistors, operating with a switching frequency of 100 kHz. The inductor winding is made of litz wire in a two-layer configuration. The lumped model of inductor winding was adopted. The results of analytical calculations have been compared with the results obtained from experimental investigations based on the resonance effect.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2017, 65, 1; 107-112
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-Frequency Absorbing Performances of Carbonyl Iron/MnZn Ferrite/PVC Polymer Composites
Autorzy:
Dosoudil, R.
Ušáková, M.
Powiązania:
https://bibliotekanauki.pl/articles/1032831.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Gg
75.50.Bb
76.50.+g
75.78.-n
72.80.Tm
78.20.Ci
41.20.Jb
Opis:
We have prepared composite materials with a mixture of carbonyl iron (CI) and manganese-zinc ferrite (MnZn) as filler and polyvinylchloride (PVC) as polymer matrix, and then electromagnetic wave absorption properties of CI/MnZn/PVC composites have been studied in the frequency range from 10 MHz to 6.5 GHz. Increasing carbonyl iron loading (to the detriment of MnZn ferrite) results in the rise of permeability and magnetic resonance loss (especially in GHz frequency range) which leads to the shift of absorption peak towards lower frequency and to the decrease of matching thickness. On the contrary, increasing MnZn ferrite loading (to the detriment of carbonyl iron) results in higher absorption bandwidth. The obtained results indicate that the prepared flexible composites may be useful as thin and/or wideband microwave absorbers.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 687-689
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High Frequency Rule Synthesis in a Large Scale Multiple Database with MapReduce
Autorzy:
Bisoyi, Sudhanshu Shekhar
Mishra, Pragnyaban
Mishra, Saroja Nanda
Powiązania:
https://bibliotekanauki.pl/articles/2055260.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
multiple database
frequent itemset
association rule
rule synthesis
MapReduce
HDFS
Opis:
Increasing development in information and communication technology leads to the generation of large amount of data from various sources. These collected data from multiple sources grows exponentially and may not be structurally uniform. In general, these are heterogeneous and distributed in multiple databases. Because of large volume, high velocity and variety of data mining knowledge in this environment becomes a big data challenge. Distributed Association Rule Mining(DARM) in these circumstances becomes a tedious task for an effective global Decision Support System(DSS). The DARM algorithms generate a large number of association rules and frequent itemset in the big data environment. In this situation synthesizing highfrequency rules from the big database becomes more challenging. Many algorithms for synthesizing association rule have been proposed in multiple database mining environments. These are facing enormous challenges in terms of high availability, scalability, efficiency, high cost for the storage and processing of large intermediate results and multiple redundant rules. In this paper, we have proposed a model to collect data from multiple sources into a big data storage framework based on HDFS. Secondly, a weighted multi-partitioned method for synthesizing high-frequency rules using MapReduce programming paradigm has been proposed. Experiments have been conducted in a parallel and distributed environment by using commodity hardware. We ensure the efficiency, scalability, high availability and costeffectiveness of our proposed method.
Źródło:
International Journal of Electronics and Telecommunications; 2022, 68, 2; 177--186
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low-voltage overhead lines topology identification method based on high-frequency signal injection
Autorzy:
Ge, Haotian
Xu, Bingyin
Zhang, Xinhui
Bi, Yongjian
Powiązania:
https://bibliotekanauki.pl/articles/1955180.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
high-frequency signal injection
low voltage overhead lines
topology identification
wtrysk sygnału wysokiej częstotliwości
linie napowietrzne niskiego napięcia
identyfikacja topologii
Opis:
The topology of low-voltage distribution systems changes with the load or the on/off position of the circuit switch. This will affect power flows, losses, and so on. This paper submits a new method to identify the topology of a low-voltage feeder using the injection high-frequency signal. An inductor can block the high-frequency signal. It can change the propagation direction of the injected high-frequency signal to make it propagate unidirectionally along the low-voltage feeder. By injecting a 5 MHz sinusoidal signal from the upstream direction of the low-voltage feeder, all the line segments and devices on the feeder can be identified. The wavelength of the high-frequency signal is short. The wavelength of the 5 MHz signal is 60 meters. Through the delay of different observation points on the feeder, the length of the line section can be roughly calculated. The high- frequency signal has an obvious reflection on the feeder. Using this feature, we can roughly calculate the length of the line segment. The correctness of the method is demonstrated by MATLAB simulation verification.
Źródło:
Archives of Electrical Engineering; 2021, 70, 4; 791-800
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Statistics of Envelope of High-Frequency Ultrasonic Backscatter from Trabecular Bone: Simulation Study
Autorzy:
Litniewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/177928.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
trabecular bone
Rayleigh distribution
scattering
simulation
Opis:
The paper considers the application of statistical properties of backscattered ultrasonic signal for assessment of the trabecular bone status. Computer simulations were conducted to investigate the properties of the ultrasound pulse-echo signal, as it is received on the transducer surface after scattering in trabecular bone. The micro-architecture of trabecular bone was modeled by a random distribution of long and thin cylindrical scatterers of randomly varying diameters and mechanical properties, oriented perpendicular to the ultrasound beam axis. The received echo signal was calculated as a superposition of echoes from all the scatterers present in the scattering volume. The simulated signal envelope was used for statistical processing to compute various parameters like the mean amplitude, the amplitude MSR defined as the ratio of the mean to the standard deviation and the amplitude histogram. Results indicated that while for the well-defined trabeculae properties within the simulated bone structure the signal envelope values are Rayleigh distributed the significant departures from Rayleigh statistics may be expected as the thickness of trabeculae become random. The influence of the variation of mechanical properties of the bone tissue building the trabeculae on the bone backscattered signal parameters was not observed.
Źródło:
Archives of Acoustics; 2010, 35, 3; 349-360
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling of Mechanical Behaviour of High-Frequency Piezoelectric Actuators Using Bouc-Wen Model
Autorzy:
Kędra, R.
Rucka, M.
Powiązania:
https://bibliotekanauki.pl/articles/221301.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
piezoelectric actuators
Bouc-Wen model
parameters identification
Opis:
The paper presents application of a modified, symmetrical Bouc-Wen model to simulate the mechanical behaviour of high-frequency piezoelectric actuators (PAs). In order to identify parameters of the model, a two-step algorithm was developed. In its first stage, the mechanical parameters were identified by taking into account their bilinear variability and using a square input voltage waveform. In the second step, the hysteresis parameters were determined based on a periodic excitation. Additionally, in order to reduce the influence of measurement errors in determination of selected derivatives the continuum wavelet transform (CWT) and translation-rotation transformation (TRT) methods were applied. The results proved that the modified symmetrical Bouc-Wen model is able to describe the mechanical behaviour of PAs across a wide frequency range.
Źródło:
Metrology and Measurement Systems; 2017, 24, 2; 413-424
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Analysis Of Mixing Under Low And High Frequency Pulsations At Serpentine Micromixers
Autorzy:
Malecha, Z. M.
Malecha, K.
Powiązania:
https://bibliotekanauki.pl/articles/185164.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
aktywne mieszanie
symulacja numeryczna
technologia LTCC
serpentine micromixer
active mixing
numerical simulations
LTCC technology
Opis:
The numerical investigation of the mixing process in complex geometry micromixers, as a function of various inlet conditions and various micromixer vibrations, was performed. The examined devices were two-dimensional (2D) and three-dimensional (3D) types of serpentine micromixers with two inlets. Entering fluids were perturbed with a wide range of the frequency (0 – 50 Hz) of pulsations. Additionally, mixing fluids also entered in the same or opposite phase of pulsations. The performed numerical calculations were 3D to capture the proximity of all the walls, which has a substantial influence on microchannel flow. The geometry of the 3D type serpentine micromixer corresponded to the physically existing device, characterised by excellent mixing properties but also a challenging production process (Malecha et al., 2009). It was shown that low-frequency perturbations could improve the average mixing efficiency of the 2D micromixer by only about 2% and additionally led to a disadvantageously non-uniform mixture quality in time. It was also shown that high-frequency mixing could level these fluctuations and more significantly improve the mixing quality. In the second part of the paper a faster and simplified method of evaluation of mixing quality was introduced. This method was based on calculating the length of the contact interface between mixing fluids. It was used to evaluate the 2D type serpentine micromixer performance under various types of vibrations and under a wide range of vibration frequencies.
Źródło:
Chemical and Process Engineering; 2014, 35, 3; 369-385
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High Frequency Interaction-Induced Anisotropic Rototranslational Light Scattering Spectra of Gaseous Carbon Dioxide
Autorzy:
El-Kader, M.
Bancewicz, T.
Maroulis, G.
Powiązania:
https://bibliotekanauki.pl/articles/1505092.pdf
Data publikacji:
2011-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.47.je
34.20.Gj
Opis:
The anisotropic rototranslational scattering of carbon dioxide gas is studied theoretically at 294.5 K, in the frequency range 10-470 $cm^{-1}$, at a density of 1.026254 mole/litre. The anisotropic double differential cross-section for scattered light is calculated theoretically using new site-site Morse-Morse-Morse-spline-van der Waals intermolecular potentials with the parameters fitted to the different thermophysical and transport properties. Our theoretical calculations take into account multipole contributions from the first- and second-order dipole-induced dipole, first-order dipole-induced octopole and first-order dipole-dipole-quadrupole light scattering mechanisms as well as their cross contributions. The irreducible spherical form for the induced operator of these light scattering mechanisms was determined. The high frequency wings are discussed in terms of the collision-induced rotational Rayleigh effect and estimates for the dipole-octopole polarizability $E_4$, is obtained and checked with the ab initio theoretical value. Good agreement is obtained at moderate frequencies between the theoretical and experimental spectra. When an exponential contribution $exp(-ν//ν_{0})$, with $ν_0 = 115 cm^{-1}$ is considered to model very short-range light scattering mechanism, good agreement is found over the whole frequency range.
Źródło:
Acta Physica Polonica A; 2011, 119, 6; 838-845
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Price duration versus trading volume in high-frequency data for selected DAX companies
Autorzy:
Gurgul, H.
Syrek, R.
Mitterer, C.
Powiązania:
https://bibliotekanauki.pl/articles/1201243.pdf
Data publikacji:
2016
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Frankfurt Stock Exchange
intraday data
duration models
copulas
Opis:
The main goal of this paper is to gain insights into the dependence structure between the duration and trading volume of selected stocks listed on the Frankfurt Stock Exchange. We demonstrate the usefulness of the copula function to describe the dependence of specific unevenly spaced time series. The properties of the time series of price durations and trading volumes under study are in line with common observations from other empirical studies. We observe clustering, overdispersion, and diurnality. For most of the stocks, the seminal model (linear parametrization with exponential or Weibull distribution) can be replaced by a logarithmic specification with more-flexible conditional distributions. The price duration and trading volume associated with this duration exhibit dependence in the tails of distribution. We may conclude that high cumulative trading volumes are associated with long duration. However, changes of price over short times are related to low cumulative volume.
Źródło:
Managerial Economics; 2016, 17, 2; 241-260
1898-1143
Pojawia się w:
Managerial Economics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mitigation measures of electromagnetic field exposure in the vicinity of high frequency welders
Autorzy:
Zubrzak, Bartłomiej
Bieńkowski, Paweł
Cała, Paweł
Powiązania:
https://bibliotekanauki.pl/articles/2164007.pdf
Data publikacji:
2017-10-17
Wydawca:
Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Tematy:
electromagnetic field
work safety in electromagnetic fields
occupational safety and health
EMF
dielectric welders
EMC
Opis:
Background Presented information about the welding process and equipment, focusing on the emission of electromagnetic field (EMF) with levels significant in terms of the labor safety regulations in force in Poland – the ordinances of the Minister of Family, Labour and Social Policy that came into force on June 27, 2016 and June 29, 2016 – emerged due to harmonization with European Union directive 2013/35/EU of 26 June 2013 of the European Parliament and the Council. They presented methods of determination of the EMF distribution in the welding machine surroundings and analyzed the background knowledge from the available literature. Material and Methods The subject of the analysis included popular high frequency welders widely used in the industry. Electromagnetic field measurements were performed in the welder operating place (in situ) during machine normal operations, using measurement methods accordant with labor safety regulations in force in Poland and according to the same guidelines, the EMF distributions and parameters having been described. Results They presented various scenarios of particular, real examples of excessive exposure to EMF in the dielectric welder surroundings and showed solutions, ranging from simple and costless and ending on dedicated electromagnetic shielding systems, which allowed to reduce EMF exposure in some cases of more than 80% (protection zone ranges) or eliminate dangerous zone presence. Conclusions It has shown that in the dielectric welders surrounding, significant EMF strength levels may be the result of errors or omissions which often occur during development, installation, operation or modification of welding machines. It has allowed to present the measures that may significantly reduce the exposure to EMF of workers in the welder surroundings. The role of accredited laboratories in helping in such cases was underlined. Med Pr 2017;68(6):693–703
Źródło:
Medycyna Pracy; 2017, 68, 6; 693-703
0465-5893
2353-1339
Pojawia się w:
Medycyna Pracy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling Foreign Exchange Realized Volatility Using High Frequency Data: Long Memory versus Structural Breaks
Autorzy:
Maatoug, Abderrazak Ben
Lamouchi, Rim
Davidson, Russell
Fatnassi, Ibrahim
Powiązania:
https://bibliotekanauki.pl/articles/2076275.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
foreign exchange markets
realized volatility
high-frequency data,long memory
structural change
Opis:
In this study, we model realized volatility constructed from intra-day highfrequency data. We explore the possibility of confusing long memory and structural breaks in the realized volatility of the following spot exchange rates: EUR/USD, EUR/JPY, EUR/CHF, EUR/GBP, and EUR/AUD. The results show evidence for the presence of long memory in the exchange rates’ realized volatility. From the Bai–Perron test, we found structural breakpoints that match significant events in financial markets. Furthermore, the findings provide strong evidence in favour of the presence of long memory.
Źródło:
Central European Journal of Economic Modelling and Econometrics; 2018, 1; 1-25
2080-0886
2080-119X
Pojawia się w:
Central European Journal of Economic Modelling and Econometrics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measuring Exposure to High-Frequency Electromagnetic Fields Experienced by a Helicopter Crew During Flight
Autorzy:
Michałowska, Joanna
Puzio, Łukasz
Tofil, Arkadiusz
Pytka, Jarosław
Powiązania:
https://bibliotekanauki.pl/articles/36453924.pdf
Data publikacji:
2022
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
Tematy:
electromagnetic
helicopter
exposure
high-frequency
Opis:
High-frequency electromagnetic fields (EMF) can have a negative effect on both the human body and electronic devices. Monitoring and measurement of the electromagnetic field generated by devices is important from the point of view of environmental protection, the human body and electromagnetic compatibility. In this study, we tested the value of the electromagnetic field strength determined by the NHT3DL by Microrad with measurement probes during flights in the Robinson R44 helicopter. The reference point for the results obtained were the normative limits of the electromagnetic field permitted to affect the crew and passengers during flight. The maximum RMS values recorded during the measurements were E = 4.399 V/m in the 100 kHz-6.5 GHz frequency band and for the magnetic component H = 2.829 A/m in the 300 kHz-30 MHz frequency band. These results were passed to the Statistica 13.3 software for a detailed stochastic analysis of the values tested.
Źródło:
Transactions on Aerospace Research; 2022, 1 (266); 59-65
0509-6669
2545-2835
Pojawia się w:
Transactions on Aerospace Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simulation of the electromagnetic vector field in the high-frequency components with dispersive materials
Autorzy:
Butryło, Bogusław
Powiązania:
https://bibliotekanauki.pl/articles/764719.pdf
Data publikacji:
2009
Wydawca:
Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej
Źródło:
Annales Universitatis Mariae Curie-Skłodowska. Sectio AI, Informatica; 2009, 9, 1
1732-1360
2083-3628
Pojawia się w:
Annales Universitatis Mariae Curie-Skłodowska. Sectio AI, Informatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Morphologic changes in the nodular goitre induced by the ligasure high frequency current generator
Autorzy:
Yermakova, T.
Powiązania:
https://bibliotekanauki.pl/articles/2052371.pdf
Data publikacji:
2015
Wydawca:
Akademia Bialska Nauk Stosowanych im. Jana Pawła II w Białej Podlaskiej
Tematy:
nodular goitre
thyroid gland
LigaSure
Opis:
Today, surgical dissection and tissue coagulation with both monopolar and bipolar coagulation as well as LigaSure high frequency current generator (HFCG) are the surgical modalities of choice in the treatment of thyroid pathology. However, the question of the high frequency current effect on the morphofunctional condition of the posthemithyroidectomic parenchyma is still disputable. The goal of the research is a thorough histological analysis of the surgically removed thyroid tissue specimen. The nodular goitre of 50 patients was subject to the histological study. The surgery was performed with the LigaSure HFCG. The 1.0x0.5 thyroid tissue specimens were excised from three areas. Hemithyroidectomy lasted for 40-50 min and thyroidectomy – 120 ± 4.2 min. In both procedures, the blood loss was within 70-150 ml, no haemorrhage being observed in both intra-and postoperative period. The zonal effect of high frequency current on the thyroid structure was determined morphologically, namely coagulation necrosis in the site of direct action, intensified secretory response of the thyroid tissue to the extremal factor in the perifocal area, and typical structure of the nodular goitre with the signs of impaired microcirculation in the remote area. Morphologic changes of the thyroid gland, with high frequency current used as a dissector, are distance-dependent.
Źródło:
Health Problems of Civilization; 2015, 09, 3; 20-23
2353-6942
2354-0265
Pojawia się w:
Health Problems of Civilization
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental evaluation of high frequency side scan sonar as object search and identification tool
Autorzy:
Łukaszewicz, D.
Rowiński, L.
Powiązania:
https://bibliotekanauki.pl/articles/332364.pdf
Data publikacji:
2006
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Paper presents initial results o laboratory tests of the sonar selected as a short range tool for an underwater vehicle. It is intended for bottom located object search and identification. To evaluate sonar imaging capability expressed by its resolution, several parameters were investigated. First group of parameters regards the sonar itself, while the second regards an object material and dimensions and shape. Their cross-influence was investigated for different distances from hydrophone to an object of interest and different hydrophone elevation angles. Experiments were performed in a shallow water laboratory tank.
Źródło:
Hydroacoustics; 2006, 9; 109-118
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Protection against high-frequency radiation of aviation electronic support systems used in air transport
Autorzy:
Dzunda, M.
Cekanova, D.
Cobirka, L.
Zak, P.
Dzurovcin, P.
Powiązania:
https://bibliotekanauki.pl/articles/116582.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
air transport
aviation electronic support systems
high-frequency radiation
radiation
electromagnetic radiation
arport radars
air electronic safety technology
radar electric field
Opis:
The aim of the article is to analyze the impact of electromagnetic radiation of aviation electronic support systems on environmental segments and a human organism. We were looking for effects of electromagnetic radiation on inhabitants and environment in the vicinity of airport radars. We accomplished measuring and found out the level of radiation harmfulness of electromagnetic radiation sources. In the conclusion we suggest to eliminate the negative impact of electromagnetic radiation on the human organism. At the same time we present the ways how workers, performing their jobs in the vicinity of strong electromagnetic radiation source, can protect themselves in compliance with legislative of the Slovak Republic. We have proposed some possibilities of protection for workers who work close to a strong source of electromagnetic radiation.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2018, 12, 1; 183-186
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-frequency adventitious shoot organogenesis from in vitro stem explants of Scutellaria araxensis Grossh
Autorzy:
Gharari, Zahra
Bagheri, Khadijeh
Sharari, Ali
Powiązania:
https://bibliotekanauki.pl/articles/16648097.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
6-benzylaminopurine
direct organogenesis
Scutellaria araxensis
thidiazuron
Opis:
The present study introduced an in vitro shoot organogenesis protocol for the medicinal plant Scutellaria araxensis (Lamiaceae). Stem, leaf, and petiole explants were cultured in half-strength Murashige and Skoog (MS) medium containing different concentrations of 6-benzylaminopurine (BAP) alone or in combination with thidiazuron (TDZ), indole-3-butyric acid (IBA), or α-naphthalene acetic acid. Callus formation occurred from stem and petiole explants in most cultures; however, in leaf explants, it was observed only in cultures containing 0.5 mg/l BAP supplemented with TDZ at all concentrations. The highest frequency of indirect shoot induction (100 and 90%) with an average of 20.33 and 12 shoots per explant was observed in stem-derived calli cultured on halfstrength MS medium containing 2.0 mg/l BAP plus 0.5 and 1.5 mg/l TDZ, respectively. The best direct shoot organogenesis (40%) was observed in stem explants cultured on half-strength MS medium containing 0.5 mg/l BAP and 0.5 mg/l IBA with a mean of 18 shoots per stem explant. The regenerated micro-shoots were elongated on a medium fortified with 0.5 mg/l gibberellic acid and then successfully rooted in half-strength MS medium supplemented with 0.5 mg/l IBA. The obtained plantlets were acclimatized in a growth chamber with a survival rate of 100%. This study is the first report of a simple and efficient in vitro shoot organogenesis and regeneration protocol for S. araxensis by using stem explants, which could be useful for the conservation, genetic manipulation, and exploitation of biological molecules of this valuable genetic source.
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2022, 103, 2; 143-151
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Detection of wavy sea surface oil-derivative contamination with forward specular high-frequency scattering
Autorzy:
Pogorzelski, Stanisław
Rochowski, Paweł
Grzegorczyk, Maciej
Linde, Bogumił B. J.
Skrodzka, Ewa
Bielasiewicz, Łukasz
Powiązania:
https://bibliotekanauki.pl/articles/260616.pdf
Data publikacji:
2020
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
crude oil contamination
capillary wave damping
acoustic surface scattering
statistical-frequency analyses
at-sea pollution detection
Opis:
A spectrum of low-frequency (20‒30 Hz) amplitude fluctuations of the ultrasonic (10 MHz) signal specularly scattered from water surfaces covered with monomolecular and thicker crude oil origin films of well-defined, oceanographically relevant viscoelastic properties was examined in laboratory and at-sea conditions. The relationship between the Surface water wave (30 Hz) damping coefficient and the oil layer thickness was established, and compared to the one predicted by the classical Stokes theory. The depression of the spectral energy density of wind-driven waves by surface films was inferred from the ratio of acoustic signal fluctuations spectra with/without films, and compared to that resulting from the Marangoni damping theory applicable to monolayers of particular surface viscoelasticity. The agreement between the theory and experimental data was satisfactory. As shown in at-sea experiments performed with a free-floating, buoy-like acoustic system, and an artificial oil slick spread over the Baltic Sea surface, the film’s rheological Surface properties can be recovered from acoustic surface probing, as well as oil spill edge detection. Simultaneous statistical analyses of the scattered signal amplitude distribution parameters turned out to be unequivocally related to the oil substance fraction weight, oil layer thickness, and the form of oil contamination.
Źródło:
Polish Maritime Research; 2020, 1; 173-179
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Regarding the Influence of High Frequency Combustion Instabilities on Operation of Solid Rocket Motors
Autorzy:
Safta, D.
Vasile, T.
Ion, I.
Powiązania:
https://bibliotekanauki.pl/articles/403482.pdf
Data publikacji:
2011
Wydawca:
Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
Tematy:
thermodynamics of rocket propulsion
unsteady solid propellant combustion
combustion instabilities
pressure-coupled response
rocket motor
operation stability
Opis:
High frequency combustion instabilities imply a major risk for the solid rocket motor's stable operation and they are directly linked to the response of the solid propellant to the pressure coupling. Our paper aims at defining a linearized onedimensional flow study model of the solid propellant rocket motors' disturbed functioning analysis. Experimental researches were done with an adequate setup, built and improved in our lab, functioning on the basis of the nozzle throat intermittent modulating technique developed by ONERA researchers, able to evaluate the propellant response by the interpretation of the pressure oscillations damping in terms of propellant response.
Źródło:
Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa; 2011, 2, 1 (3); 7-24
2081-5891
Pojawia się w:
Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Monte Carlo Calculation of High Frequency Mobility and Diffusion Noise in Nitride-Based Semiconductors
Autorzy:
Starikov, E.
Shiktorov, P.
Gružinskis, V.
Varani, L.
Vaissière, J. C.
Palermo, C.
Reggiani, L.
Powiązania:
https://bibliotekanauki.pl/articles/2041806.pdf
Data publikacji:
2005-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.Ht
72.30.+q
72.70.+m
Opis:
Monte Carlo simulations of high-field transport in semiconductor nitrides, GaN and InN, is used to calculate the velocity-field characteristics and the high-frequency behavior of the differential mobility, spectral density of velocity fluctuations, and noise temperature. It is found that due to very short relaxation time scales of nitrides, the characteristic frequencies associated with extrema and cutoff decay of the negative differential mobility, etc. are shifted to higher frequency range with respect to the case of standard A$\text{}_{3}$B$\text{}_{5}$ compounds. This property is favorable for applications of nitrides in the THz frequency range.
Źródło:
Acta Physica Polonica A; 2005, 107, 2; 408-411
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Estimation of power losses in a high-frequency planar transformer using a thermal camera
Autorzy:
Barlik, R.
Nowak, M.
Grzejszczak, P.
Zdanowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/140759.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
power losses estimation
thermal camera
thermal calibration
planar transformer
Dowell’s and Steinmetz’s equations
Opis:
This paper presents the implementation of a thermal camera for the quantitative estimation of power losses in a high frequency planar transformer (100 kHz/ 5600 VA). The methodology is based on the observation of the transient temperature rise and determination of the power losses by means of curves representing the derivative of temperature as a function of power losses dissipated in the transformer. First, the thermal calibration characteristics had to be obtained from a simple experiment, where power losses are generated by DC current in the ferrite core and windings. Next, experimental investigations focused on the determination of the transformer power losses for a short circuit and no load, with a resistive load and with the rectifier as a load were carried out. Finally, to verify the obtained results, analytical calculations based on Dowell’s and modified Steinmetz’s equations were additionally made, which showed a good convergence. The proposed method is easy to implement and can be used as an alternative to the calorimetric method which is time-consuming and requires a complicated measurement setup.
Źródło:
Archives of Electrical Engineering; 2016, 65, 3; 613-627
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of positioning error and its impact on high frequency properties of differential signal coupler
Autorzy:
Zmuda, M.
Szczepański, S.
Kozieł, S.
Powiązania:
https://bibliotekanauki.pl/articles/200709.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
high speed data transmission monitoring
coupler positioning accuracy
manufacturing of coupling structures
monitoring wysokiej prędkości transmisji danych
dokładność pozycjonowania
produkcja konstrukcji sprzęgła
Opis:
This paper presents the analysis of the effect of differential signal coupler positioning accuracy on its high frequency performance parameters for contact-less high speed chip-to-chip data transmission on PCB application. Our considerations are continuation of the previous works on differential signal coupler concept, design methodology and analysis for high speed data transmission monitoring. The theoretical analysis of possible coupler positioning innaccuracies is extended for representative design cases by simulations carried out using EM simulator. The results reported here confirm that the concept of contactless monitoring of high speed chip-to-chip data transmission in a pair of coupled microstrip lines is of practically usefulness without applying the expensive and precise positioning system.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2015, 63, 2; 549-553
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of extremely high frequency electromagnetic fields on the microbiological community in rhizosphere of plants
Autorzy:
Ratushnyak, A.A.
Andreeva, M.G.
Morozova, O.V.
Morozov, G.A.
Trushin, M.V.
Powiązania:
https://bibliotekanauki.pl/articles/25966.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Źródło:
International Agrophysics; 2008, 22, 1; 71-74
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Electromagnetic Shield on the High Frequency Electromagnetic Field Penetration through the Building Material
Autorzy:
Kolcunová, I.
Pavlík, M.
Beňa, L'.
Čonka, Z.
Ilenin, S.
Kanálik, M.
Kolcun, M.
Mészáros, A.
Medveď, D.
Zbojovský, J.
Powiązania:
https://bibliotekanauki.pl/articles/1032736.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
41.20.Gz
Opis:
This paper studies how to protect people against electromagnetic radiation inside a building. Widespread usage of the mobile communication led to building of more and more new GSM base-station antennas. These antennas are often placed in the areas with high population density. These antennas emit electromagnetic radiation in standard mobile operator frequencies, i.e. 0.9, 1.8 and 2.1 GHz. Many studies have shown potential biological and thermal effects of GSM electromagnetic fields, therefore people are concerned about their health. Electromagnetic wave does not penetrate the wall of the building as a whole. A small part of the wave is reflected and a small part is absorbed by the building material. In this paper the penetration of electromagnetic waves through the commercially available building materials is measured with specific focus on frequencies of 0.9, 1.8, and 2.1 GHz. Next, the surface of the chosen building material was coated with a magnetic conductive paint in order to improve the shielding effect of the building material. The results of experiment show how the electromagnetic shield reduces the penetration of electromagnetic waves through the building wall.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1135-1137
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New Results in Chaotic Time-Reversed Electromagnetics: High Frequency One-Recording-Channel Time-Reversal Mirror
Autorzy:
Anlage, S. M.
Rodgers, J.
Hemmady, S.
Hart, J.
Antonsen, T. M.
Ott, E.
Powiązania:
https://bibliotekanauki.pl/articles/2047818.pdf
Data publikacji:
2007-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
03.50.De
05.45.Mt
41.20.Jb
42.65.Hw
Opis:
We experimentally demonstrate a new electromagnetic one-recording-channel time-reversal mirror that can operate at high frequencies and high bandwidths. The experiments are carried out in a 1 m$\text{}^{3}$ ray-chaotic enclosure using two simple antennas. The input is a 7.0 GHz signal that is amplitude modulated with a 60 ns long pulse. The time-reversal focused signal has a peak-signal-to-noise ratio of about 9 dB, and is very sensitive to small perturbations to the ray-chaotic enclosure. The results are consistent with expectations for single-recording-channel time-reversal mirrors, and establish a new platform for study of fundamental issues in time-domain wave chaos, as well as novel applications.
Źródło:
Acta Physica Polonica A; 2007, 112, 4; 569-574
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurement and Analysis of Partial Discharge using an Ultra-High Frequency Sensor for Gas Insulated Structures
Autorzy:
Wang, G.
Kil, G.-S.
Powiązania:
https://bibliotekanauki.pl/articles/221519.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
gas insulated structures
partial discharge
ultra-high frequency sensor
conversion
Opis:
Although the gas insulated structures have a high degree of reliability, the unavoidable defects are primary reason of their failures. Partial discharge (PD) has been regarded as an effective indication for condition monitoring and diagnosis of gas insulated switchgears (GISs) to ensure their reliable and stable operation. Among various PD detection methods, the ultra-high frequency (UHF) technique has the advantages of on-line motoring and defect classification. In this paper, there are presented 7 types of artificial electrode systems fabricated for simulation of real insulation defects in gas insulated structures. A real-time measurement system was developed to acquire defect patterns in a form of phase-resolve partial discharge (PRPD) intensity graph, using a UHF sensor. Further, the discharge distribution and statistical characteristics were extracted for defect identification using a neural network algorithm. In addition, a conversion experiment was proposed by detecting the PD pulse simultaneously using a non-induction resistor and a UHF sensor. A relationship between the magnitude of UHF signal and the amplitude of apparent charge was established, which was used for evaluation of PD using the UHF sensor.
Źródło:
Metrology and Measurement Systems; 2017, 24, 3; 515-524
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Distribution and discrimination of anchovy, and sprat in the Black Sea from high frequency sound records
Autorzy:
Mutlu, E.
Powiązania:
https://bibliotekanauki.pl/articles/332447.pdf
Data publikacji:
1999
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
High frequency (200 kHz) was used to identify anchovy, and sprat schools from over the entire trackline of broad-scale acoustical survey over a period of 4 years (1991-1994) in the Bleak Sea. Analysis of color enhanced echograms as well as trawl catches provided detailed morphological descriptions to discriminate aggregations of anchovy, and sprat together with characteristics of their habitat. Sprat showed fish school scattered in relatively, a thin layer near the bottom like semi-pelagic fish made up. Anatomy of the aggregation did not change between day and night, and there was 110 diet shift in the habitat. Anchovy formed the pole shaped schools as well as compact aggregation arising from bottom around the shelf break area to that as much high up as 30-70 m, during the day. Additionally, a striking point is that the anchovy in an appearance, of what looked to be pole shape school, stand ready on top of submarine steep cliff to escape down immediately in case of any disturbance to the school. There is a sharp discrimination between the schools of sprat and anchovy.
Źródło:
Hydroacoustics; 1999, 2; 27-31
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A novel method for separability of signal components to estimate radiation from a high-frequency subsystem
Autorzy:
Daneshvar, Milad
Parhizgar, Naser
Oraizi, Homayoon
Powiązania:
https://bibliotekanauki.pl/articles/140523.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
electromagnetic interference
electromagnetic radiation
parameter estimation
multi-component signals
frequency response
radio frequency
Opis:
Specific requirements are designed and implemented in electronic and telecommunication systems for received signals, especially high-frequency ones, to examine and control the signal radiation. However, as a serious drawback, no special requirements are considered for the transmitted signals from a subsystem. Different industries have always been struggling with electromagnetic interferences affecting their electronic and telecommunication systems and imposing significant costs. It is thus necessary to specifically investigate this problem as every device is continuously exposed to interferences. Signal processing allows for the decomposition of a signal to its different components to simulate each component. Radiation control has its specific complexities in systems, requiring necessary measures from the very beginning of the design. This study attempted to determine the highest radiation from a subsystem by estimating the radiation fields. The study goal was to investigate the level of radiations received and transmitted from the adjacent systems, respectively, and present methods for control and eliminate the existing radiations. The proposed approach employs an algorithm which is based on multi-component signals, defect, and the radiation shield used in the subsystem. The algorithm flowchart focuses on the separation and of signal components and electromagnetic interference reduction. In this algorithm, the detection process is carried out at the bounds of each component, after which the separation process is performed in the vicinity of the different bounds. The proposed method works based on the Fourier transform of impulse functions for signal components decomposition that was employed to develop an algorithm for separation of the components of the signals input to the subsystem.
Źródło:
Archives of Electrical Engineering; 2019, 68, 3; 497-510
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optically Driven Domain Instability and High-Frequency Current Oscillations in Photoexcited GaAs under Nonuniform Electron Heating
Autorzy:
Subačius, L.
Kašalynas, I.
Powiązania:
https://bibliotekanauki.pl/articles/1179478.pdf
Data publikacji:
2005-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Eq
72.20.Ht
Opis:
Fast domain instabilities induced by light-interference pattern in dc-biased semi-insulating GaAs are investigated. Current oscillations in GHz-frequency range are observed due to nonuniform electron heating and domains formation in light-induced grating. Characteristic features of the oscillations under various experimental conditions are presented. Numerical calculations based on the hot-electron hydrodynamic model are used to explain the observed nonlinear features under various external bias and periods of the grating.
Źródło:
Acta Physica Polonica A; 2005, 107, 2; 275-279
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ocena uziemień odgromowych metodami: udarową i wysokoczęstotliwościową
Lightning earthing evaluation by impulse and high frequency methods
Autorzy:
Wojtas, S.
Powiązania:
https://bibliotekanauki.pl/articles/154029.pdf
Data publikacji:
2007
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
uziemienia odgromowe
pomiary uziemień
lightning protection earthings
earthing tests
Opis:
Uziemienia odgromowe przeznaczone do odprowadzania do ziemi prądów piorunowych pracują w zakresie znacznie szybszych przebiegów (žs) niż uziemienia robocze (ms), a więc wymagają innych metod badań, zwłaszcza uwzględniających spadki indukcyjne w systemie uziemiającym. Wyniki uzyskane metodami udarową i wysokoczęstotliwościową są zbieżne i pozwalają na dobrą ocenę przydatności uziemień do celów ochrony odgromowej. Pomiary takie mogą być przeprowadzane bez konieczności rozłączania zacisków kontrolnych.
A safety earthing designed for short circuit currents is not always good enough to carry away lightning current. For lightning protection purposes impedance of earthing, instead of its resistance, should be taken into account. Dynamic changes of these groups are very different. The duration of an instantaneous state is in the order of milliseconds and the duration of lightning is in microseconds. Because the times of these phenomena differ so much, technical protection means and methods for tests of the means must be properly chosen for a given situation. The impulse and high frequency methods allow for evaluation of lightning protection installations. Impulse impedances of eartings measured in the time domain by an impulse meter are comparable to those measured by a high frequency meter in the frequency domain (Fig. 3 and 4). The impulse and high frequency methods allow for evaluation of lightning protection installations of different objects without disconnections of testing terminals of the installation (Fig. 8).
Źródło:
Pomiary Automatyka Kontrola; 2007, R. 53, nr 4, 4; 106-109
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effects of Relativistic Warm Plasma Waveguide and High Frequency Electrical Field on Beam-Plasma Interaction
Autorzy:
El-Shorbagy, Kh. H.
Powiązania:
https://bibliotekanauki.pl/articles/2047358.pdf
Data publikacji:
2007-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.27.Ny
52.35.-g
94.20.wf
Opis:
The paper is concerned with investigation of the influence of an intense high frequency electric field and relativistic warm plasma waveguide on electrostatic oscillations of nonuniform bounded plasma. The stabilizing effect of a strong high frequency (pump) electrical field on beam-plasma interaction in a cylindrical relativistic warm plasma waveguide is discussed. A new mathematical technique "separation method" was applied to the two-fluid plasma model to separate the equations, which describe the system, into two parts, time and space parts. Plasma electrons are considered to have a relativistic, thermal velocity. It is shown that a high frequency electric field has no essential influence on dispersion characteristics of unstable surface waves excited in a relativistic warm plasma waveguide by a low-density electron beam. The region of instability is only slightly narrowing and the growth rate decreases by a small parameter and this result was reduced comparing to cold, nonrelativistic plasma. Also, it is found that the plasma electrons did not affect the solution of the space part of the problem.
Źródło:
Acta Physica Polonica A; 2007, 112, 1; 41-48
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Przekształtnik wysokiej częstotliwości z wykorzystaniem nowoczesnych tranzystorów GaN
High-frequency power converter using modern GaN transistors
Autorzy:
Swadowski, M.
Zygoń, K.
Jąderko, A.
Powiązania:
https://bibliotekanauki.pl/articles/1817901.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
tranzystory GaN
straty łączeniowe
wysoka częstotliwość
grzanie indukcyjne
termografia
Opis:
Modern transistors made with gallium nitride in the application of induction heater voltage converter are described in this paper. Advantages of modern GaN transistors in comparison to the MOSFETs are shown. Total power losses and maximum junctions temperature are significantly reduced.
Źródło:
Prace Naukowe Instytutu Maszyn, Napędów i Pomiarów Elektrycznych Politechniki Wrocławskiej. Studia i Materiały; 2015, 71, 35; 29--39
1733-0718
Pojawia się w:
Prace Naukowe Instytutu Maszyn, Napędów i Pomiarów Elektrycznych Politechniki Wrocławskiej. Studia i Materiały
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An approach to suppress high-frequency resonance using model predictive and selective harmonic elimination combined strategy
Autorzy:
Chen, Sitong
Chen, Xiaoqiang
Wang, Ying
Xiong, Ye
Powiązania:
https://bibliotekanauki.pl/articles/1841300.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
CRH5 EMUs and traction power supply coupled system
high-frequency oscillation
high speed railway
model predictive control (MPC)
selective harmonic elimination pulse-width modulation (SHEPWM)
CRH5 EMU i system sprzężony z zasilaniem trakcyjnym
oscylacja wysokiej częstotliwości
kolej dużych prędkości
kontrola predykcyjna modelu (MPC)
selektywna eliminacja harmoniczna modulacja szerokości impulsu (SHEPWM)
Opis:
High-frequency resonance is a prominent phenomenon which affects the normal operation of the high-speed railway in China. Aiming at this problem, the resonance mechanism is analyzed first. Then, model predictive control and selective harmonic elimination pulse-width modulation (MPC-SHEPWM) combined control strategy is proposed, where the harmonics which cause the resonance can be eliminated at the harmonic source. Besides, the MPC is combined to make the current track the reference in transients. The proposed control has the ability to suppress the resonance while has a faster dynamic performance comparing with SHEPWM. Finally, the proposed MPC-SHEPWM is tested in a simulation model of CRH5 (Chinese Railway High-speed), EMUs (electric multiple units) and a traction power supply coupled system, which shows that the proposed MPC-SHEPWM approach can achieve the resonance suppression and shows a better dynamic performance.
Źródło:
Archives of Electrical Engineering; 2021, 70, 2; 415-430
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Protuberance-mediated high frequency of adventitious shoot regeneration from sweetpotato leaf explants [Ipomoea batatas (L.) Lam.]
Autorzy:
Ashok Kumar, H.G.
Ku, A.T.
Agrawal, P.
Mahesh, S.
Yeh, K.-W.
Powiązania:
https://bibliotekanauki.pl/articles/80764.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
adventitious shoot
organogenesis
sweet potato
Ipomoea batatas
plant regeneration
leaf explant
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2013, 94, 4
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Możliwości terapeutyczne promieniowania elektromagnetycznego bardzo wielkiej częstotliwości
Therapeutic possibilities of electromagnetic radiation of very high frequency
Autorzy:
Chwaleba, A.
Jatsunenko, A.
Kamkov, V.
Szczurko, J.
Szmitkowski, J.
Yatsunenko, S.
Wilczkowski, S.
Powiązania:
https://bibliotekanauki.pl/articles/372882.pdf
Data publikacji:
2012
Wydawca:
Centrum Naukowo-Badawcze Ochrony Przeciwpożarowej im. Józefa Tuliszkowskiego
Tematy:
leczenie bezinwazyjne
normalizacja stanu funkcjonalnego
nowe technologie medyczne
functional status
new medical technologies
non-invasive treatment
normalization of patient's
Opis:
Praktycznie całe widmo promieniowania elektromagnetycznego ma zastosowanie w medycynie. Z tym, że promieniowanie w pasmie częstotliwościowym od 30 GHz do 300 GHz wykorzystywane jest od niedawna. Zespół autorski opracował (i nadal doskonali) metodę terapeutyczną wykorzystującą pole elektromagnetyczne bardzo wielkiej częstotliwości (b.w.cz.) w pasmie od 40 GHz do 70 GHz i subniskiej intensywności - gęstość strumienia mocy nie przekracza 1 [my]W / cm[^2]. Pole to oddziaływuje informacyjnie na komórki , wywołując procesy reaktywacyjne w orgazmie - normalizując właściwe stany narządów i układów. Dzięki subniskiemu poziomowi gęstości strumienia mocy promieniowanie to nie wpływa na struktury atomowe i molekularne, jak również na makrocząsteczki biologiczne - stymuluje jedynie energię ich obrotów. Aby zapewnić dostarczanie przydatnych informacji zawartych w sygnale terapeutycznym - aparatura terapeutyczna powinna mieć następujące właściwości: - gęstość strumienia mocy promieniowania elektromagnetycznego emitowanego przez promienniki nie powinna przekraczać 1 [my]W / cm[^2]; - częstotliwość promieniowania elektromagnetycznego otrzymanego z aparatury terapeutycznej musi odpowiadać jednej z biologicznie aktywnych częstotliwości rezonansowych; - w urządzeniach do terapii b.w.cz. powinna być możliwość modulacji częstotliwościowej jak i modulacji amplitudowej; - dewiacja częstotliwości (przy modulacji częstotliwościowej) musi być równa lub szersza od pasma biologicznie aktywnych własnych częstotliwości organizmu; - oddziaływanie powinno się odbywać w wąskich pasmach nie szerszych niż [plus lub minus] 100 MHz wokół określonych biologicznie aktywnych częstotliwości rezonansowych; - w trakcie sesji terapeutycznych powinna być możliwość ukierunkowania promieniowania na obszary głównych stawów oraz punkty biologicznie aktywne. Praktycznie wszystkie te właściwości ma wielokanałowa aparatura terapeutyczna, która była poddana wieloletnim badaniom klinicznym - pod kątem skuteczności korzystnego oddziaływania regulacyjnego pola elektromagnetycznego b.w.cz. na dynamikę procesów metabolicznych organizmu. Zestaw terapeutyczny "RAMED EXPERT-08" (z dziewięcioma promiennikami) jest przeznaczony głównie do użytku w neurologii, a zestaw "RAMED EXPERT-09" (z dwunastoma promiennikami) w endokrynologii, Ten ostatni zestaw terapeutyczny w roku 2010 był badany pod kątem wykorzystania go w leczeniu cukrzycy. Biorąc pod uwagę wysoką czułość organizmów żywych na promieniowanie elektromagnetyczne b.w.cz. i subniskiej intensywności należy sądzić, że w metodzie i aparaturze tkwi jeszcze wiele potencjalnych (dotychczas niezbadanych i niezrealizowanych) możliwości korekcyjnych systemu bioenergoinformacyjnego człowieka.
Virtually the entire spectrum of electromagnetic radiation is applied in medicine, with the fact that the radiation in the frequency band from 30 GHz to 300 GHz has been used recently. The authors developed (and continue to improve) the therapeutic method that uses electromagnetic fields of very high frequency (vhf) in the band from 40 GHz to 70 GHz and sublow intensity - the power flux density does not exceed 1 [mu]W / cm[^2]. This field acts informationally on cells, causing the reactivation processes in orgasm - normalizing the relevant states of organs and systems. Thanks to sublow power flux density level the radiation does not affect the atomic and molecular structures, as well as biological macromolecules - it stimulates only the energy of their turnover. To ensure the provision of useful information contained in the therapy signal - therapeutic apparatus should have the following properties: - Power flux density of electromagnetic radiation emitted by the emitters should not exceed 1 [mu]W / cm[^2]; - The frequency of electromagnetic radiation received from a therapeutic equipment must conform to one of the biologically active resonant frequencies; - In devices for vhf therapy should there be an ability for frequency and amplitude modulation; - Frequency deviation (at modulation frequency) must be equal to or wider than the band's biologically active own frequencies of organism; - The impact should take place in narrow bands no wider than [plus or minus] 100 MHz around a set of biologically active resonant frequencies; - During therapy sessions should there be an ablility to focus the radiation on areas of major joints and biologically active points. Practically all of these features are included in the multi-therapeutic apparatus company, which was subjected to many years of clinical trials - in terms of effectiveness of positive impact of regulatory electromagnetic field - RF & Microwave. the dynamics of the body's metabolic processes. A therapeutic set "RAMED EXPERT-08" (with nine radiators) is intended primarily for use in neurology, "RAMED EXPERT-09" (with twelve radiators) in endocrinology,, this last therapeutic set was studied for its use in the treatment of diabetes in 2010. Given the high sensitivity of living organisms to electromagnetic radiation of RF & Microwave and sublow intensity it is believed that in the method and apparatus lies a lot of potential (yet unexplored and not realized) correction possibilities of human bioenergetic information system.
Źródło:
Bezpieczeństwo i Technika Pożarnicza; 2012, 3; 47-52
1895-8443
Pojawia się w:
Bezpieczeństwo i Technika Pożarnicza
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Short Utterance Speaker Recognition Based on Speech High Frequency Information Compensation and Dynamic Feature Enhancement Methods
Autorzy:
Zi, Yunfei
Xiong, Shengwu
Powiązania:
https://bibliotekanauki.pl/articles/31339765.pdf
Data publikacji:
2024
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
Bark-scaled Gauss
linear filter
filter bank superposition
multi-dimensional central difference
speaker recognition
Opis:
This work aims to further compensate for the weaknesses of feature sparsity and insufficient discriminative acoustic features in existing short-duration speaker recognition. To address this issue, we propose the Bark-scaled Gauss and the linear filter bank superposition cepstral coefficients (BGLCC), and the multidimensional central difference (MDCD) acoustic feature extracted method. The Bark-scaled Gauss filter bank focuses on low-frequency information, while linear filtering is uniformly distributed, therefore, the filter superposition can obtain more discriminative and richer acoustic features of short-duration audio signals. In addition, the multi-dimensional central difference method captures better dynamics features of speakers for improving the performance of short utterance speaker verification. Extensive experiments are conducted on short-duration text-independent speaker verification datasets generated from the VoxCeleb, SITW, and NIST SRE corpora, respectively, which contain speech samples of diverse lengths, and different scenarios. The results demonstrate that the proposed method outperforms the existing acoustic feature extraction approach by at least 10% in the test set. The ablation experiments further illustrate that our proposed approaches can achieve substantial improvement over prior methods.
Źródło:
Archives of Acoustics; 2024, 49, 1; 37-48
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
LTCC glass-ceramics based on diopside/cordierite/Al2O3 for ultra-high frequency applications
Autorzy:
Synkiewicz-Musialska, Beata
Powiązania:
https://bibliotekanauki.pl/articles/35138346.pdf
Data publikacji:
2023
Wydawca:
Radomskie Towarzystwo Naukowe
Tematy:
glass-ceramics
diopside
cordierite
Al2O3
LTCC technology
THz dielectric properties
tworzywo szklano-ceramiczne
diopsyd
kordieryt
technologia LTCC
właściwości dielektryczne
Opis:
In this work, three glass-ceramic composites based on a commercial SiO2-B2O3-Al2O3-CaO-MgO glass and cordierite, diopside or Al2O3 were used for preparation of green tapes and low temperature cofired ceramics (LTCC) substrates. The thermal behavior, phase composition, microstructure and dielectric properties of the fabricated glass-ceramics were characterized using a heating microscope, thermal analysis, X-ray diffraction, scanning electron microscopy and time domain spectroscopy. The applicability of the developed materials for LTCC technology was demonstrated by the preparation of test multilayer substrates. The glass-ceramic substrates exhibit advantageous properties for ultra-high frequency LTCC applications, including low sintering temperatures of 900-980°C, good compatibility with commercial Ag and AgPd conductive pastes and a low dielectric permittivity of 3.5-7 at 1 THz.
Źródło:
Scientiae Radices; 2023, 2, 2; 190-201
2956-4808
Pojawia się w:
Scientiae Radices
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Noise Hazard Assessment within the Intermediate Range of the High Audible and the Low Ultrasonic Frequencies
Autorzy:
Śliwiński, A.
Powiązania:
https://bibliotekanauki.pl/articles/177315.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ultrasonic noise assessment
high frequency audiometry
Opis:
In parallel to the ultrasonic noise assessment procedures and research activity in the field there have appeared several papers in the domain of so called high-frequency audiometry which covers the range of frequencies 8–20 kHz. They are important for recognizing the harmfulness and hazard of the audible high frequency sound components in the same range as the one of the low frequency ultrasonic noise. On the other hand there exists a certain inconsequent situation in the general approach to the problem of ultrasonic noise hazard assessment in work places environment which concerns the convention to include the frequency range of 10–20 kHz to the domain of ultrasonics. The range consists of one third octave bands of central frequencies: 10, 12.5, 16, 20 kHz and conventionally is called low frequency ultrasonic noise though at least the components of the two lowest bands are naturally audible by a majority of population (mainly young people).The paper presents a discussion related to some achievements of the two domains and some conclusions which could be useful for a more consequent description of the subject and could be taken into account in the future regulations for the ultrasonic noise assessment in work places environment.
Źródło:
Archives of Acoustics; 2016, 41, 2; 331-338
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Insight into Coherent Backscattering Evaluation Techniques of Prospective Use in High Frequency Polarimetric Radar Image Processing
Autorzy:
Kapelewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1506794.pdf
Data publikacji:
2010-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
41.20.Jb
03.50.De
Opis:
Coherence in multiple scattering is important as it applies to imaging and detection of object in multiple scattering environments. These phenomena may also be used to investigate images of objects obscured by them. The scattering observations using very rough surfaces can provide useful insight into their statistic as they lie outside the range of validity of the standard theories. Recently, there has been growing interest in the phenomenon of backscattering enhancement in the reflection of electromagnetic waves of mm wave range from both atmospheric hydrometeors (rain, snow and precipitation) as well as very rough surfaces (including that of sea and terrain sea). Strong backscattering enhancement of mm waves incident at different incident angles, both in the TE and TM polarizations, was observed experimentally. In the paper a short description of specific techniques used for treating image processing of strongly irregular media is shortly presented. An emphasis is placed on the phenomena of interest in advanced polarimetric radar especially in mm wave range.
Źródło:
Acta Physica Polonica A; 2010, 118, 6; 1161-1167
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Parametry uziemień przy przebiegach udarowych i wysokoczęstotliwościowych
Parameters of earthings measured using impulse and high frequency methods
Autorzy:
Domaradzki, M.
Powiązania:
https://bibliotekanauki.pl/articles/267164.pdf
Data publikacji:
2014
Wydawca:
Politechnika Gdańska. Wydział Elektrotechniki i Automatyki
Tematy:
ochrona odgromowa
uziemienie
uziomy
rezystywność
lighting protection
earthground
earth
resistivity
Opis:
W artykule skupiono się na porównaniu dwóch metod badania impedancji uziemienia odgromowego: udarowej z wysoką częstotliwościową. Zestawiono wyniki pomiarów istniejących uziemień z wynikami komputerowych obliczeń symulacyjnych przeprowadzonych w środowisku programu PSIM. Uzyskane wyniki wskazują na poprawność przyjętego toku modelowania, a uzyskane w ten sposób dane mogą być przydatne w fazie projektowania do szacowania spodziewanych wartości impedancji uziemień. Duże znaczenie ma konfiguracja i rozmieszczenie poszczególnych elementów systemu uziemień z uwzględnieniem pojęcia długości efektywnej uziomu. Zaprezentowane w pracy wyniki z obliczeń symulacyjnych oraz pomiarów na rzeczywistych uziomach wskazują, że impedancja udarowa uziomu wyznaczana w dziedzinie czasu jest jednoznacznie związana z charakterystyką uziomu rejestrowaną w dziedzinie częstotliwości.
The article focuses on a comparison of two methods for testing impedance earthing lightning: impulse impedance earthing and high frequency. Summarizes the results of measurements of the real earthing with the results of computer simulation calculations carried out in the environment PSIM program. The results indicate the correctness of the adopted course of modeling, and obtained in this way data can be useful in the design phase to estimate.
Źródło:
Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej; 2014, 39; 17-21
1425-5766
2353-1290
Pojawia się w:
Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-Frequency Noise in Modern FET/HEMT Channels Caused by the Excitation of 2D-Plasma Waves
Autorzy:
Shiktorov, P.
Starikov, E.
Gružinskis, V.
Varani, L.
Reggiani, L.
Powiązania:
https://bibliotekanauki.pl/articles/1505464.pdf
Data publikacji:
2011-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.Ht
72.30.+q
72.70.+m
Opis:
The problems related with the intrinsic noise in FET/HEMT channels induced by continuous branching of the total current between channel and gate are considered in the framework of a simple analytical model and its predictions on the current-noise spectra. Main branching-induced effects such as the appearance of an additional noise related to the excitation of plasma waves, its dependence on FET/HEMT embedding circuits, interference properties, etc. are analysed.
Źródło:
Acta Physica Polonica A; 2011, 119, 2; 117-120
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of very high-frequency sound and low-frequency ultrasound on people – the current state of the art
Autorzy:
Pawlaczyk-Łuszczyńska, Małgorzata
Dudarewicz, Adam
Powiązania:
https://bibliotekanauki.pl/articles/2116587.pdf
Data publikacji:
2020-06-16
Wydawca:
Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Tematy:
low-frequency airborne ultrasound
high-frequency sound
occupational exposure
impact on humans
auditory effects
non-auditory effects
Opis:
For several decades, low-frequency ultrasound (<100 kHz) has been widely used in industry, medicine, commerce, military service and the home. The objective of the study was to present the current state of the art on the harmful effects of low-frequency airborne ultrasound on people, especially in occupational settings. The scientific literature search was performed using accessible medical and other databases (WOS, BCI, CCC, DRCI, DIIDW, KJD, MEDLINE, RSCI, SCIELO and ZOOREC), and the obtained results were then hand-searched to eliminate non-relevant papers. This review includes papers published in 1948–2018. The potential effects of the low-frequency airborne ultrasound have been classified as auditory and non-auditory effects, including subjective, physiological, and thermal effects. In particular, already in the 1960–1970s, it was demonstrated that ultrasonic exposure, when sufficiently intense, appeared to result in a syndrome involving nausea, headache, vomiting, disturbance of coordination, dizziness, and fatigue, and might cause a temporary or permanent hearing impairment. However, since that time, not too much work has been done. Further studies are needed before any firm conclusions can be drawn about the auditory and non-auditory effects of low-frequency airborne ultrasound.
Źródło:
International Journal of Occupational Medicine and Environmental Health; 2020, 33, 4; 389-408
1232-1087
1896-494X
Pojawia się w:
International Journal of Occupational Medicine and Environmental Health
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative investigation of SiC and Si power electronic devices operating at high switching frequency
Autorzy:
Zymmer, K.
Mazurek, P.
Powiązania:
https://bibliotekanauki.pl/articles/200057.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
semiconductor devices
silicon carbide
high frequency converters
Opis:
The paper presents results of measurements of the reverse recovery current and dynamic forward voltage of the silicon carbide (SiC) Schottky diodes operating at a 500 A/ěs current slope. These data were compared with the corresponding parameters determined for ultrafast silicon (Si) diodes. Results of power losses measurement in SiC Schottky diodes operating at switching frequency range of (10–200) kHz are presented and compared with corresponding data of ultrafast Si diodes. Also, results of power losses measurements in transistors of dc voltage switch are shown. Investigations were conducted with a SiC and the ultrafast Si freewheeling diode at the transistor switching frequency of 100 kHz. The results of measuring power losses dissipated in the dc converter with a SiC Schottky diode and the ultrafast silicon diode are also presented.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2011, 59, 4; 555-559
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wykorzystanie sonaru skanującego wysokiej częstotliwości w pozyskiwaniu danych obrazowych
Using high-frequency scanning sonar for acquiring image data
Autorzy:
Stateczny, A.
Powiązania:
https://bibliotekanauki.pl/articles/210744.pdf
Data publikacji:
2010
Wydawca:
Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
Tematy:
geoinformatyka
informacja obrazowa
sonar skanujący
geoinformatics
image information
scanning sonar
Opis:
Głównym elementem systemu obrazowania podwodnego jest sonar nawigacyjny. W artykule przedstawiono unikalne w skali kraju rozwiązanie wdrożenia systemu sonarowego wysokiej częstotliwości pracującego w dwóch wariantach statycznych i w wariancie dynamicznym. Przedstawiono przykłady pozyskanych obrazów sonarowych wysokiej rozdzielczości.
Navigational sonar is the main element of an underwater imaging system. In the article there has been presented a solution, unique on the national scale, of implementing a high-frequency sonar system working in two variants, a static and a dynamic one. There have been presented examples of obtained high-resolution sonar images.
Źródło:
Biuletyn Wojskowej Akademii Technicznej; 2010, 59, 2; 339-347
1234-5865
Pojawia się w:
Biuletyn Wojskowej Akademii Technicznej
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zastosowanie przetwarzania równoległego do analizy pola elektromagnetycznego wielkiej częstotliwości
Parallel processing applied to high frequency electromagnetic field analysis
Autorzy:
Walendziuk, W.
Powiązania:
https://bibliotekanauki.pl/articles/157259.pdf
Data publikacji:
2010
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
metoda FDTD
klaster
obliczenia równoległe
FDTD method
cluster system
parallel computing
Opis:
W artykule przedstawiono algorytmy równoległe, mające zastosowanie w metodzie FDTD (ang. Finite-Differences Time-Domain), będącej jedną z najpopularniejszych metod analizy pola elektromagnetycznego wielkiej częstotliwości. W pracy przedstawiono metodę dekompozycji analizowanej przestrzeni, jak również algorytmy dekompozycji programu na zespół współbieżnych wątków. Ze względu na szczególne zainteresowanie autora algorytmami mającymi zastosowanie w klastrach komputerowych, przedstawione będą wyniki doświadczeń, uzyskanych w czasie testów wydajności programu równoległego, opartego na dekompozycji przestrzeni w wersji podziału "plastrowego". Zdecydowano się na przedstawienie algorytmów zaimplementowanych w klastrze homogenicznym, jak również w heterogenicznym - przy wykorzystaniu dodatkowego algorytmu dynamicznego podziału obszaru analizy.
The paper contains parallel algorithms applied in the FDTD method, which is one of more popular ways of electromagnetic field of high frequency analysis. The work shows algorithms which decompose a program into a group of parallel threads, and a method of the analyzed area decomposition. The first type of algorithms enables achieving good speedups and makes it possible to use e.g. graphic cards in computations conducted with the use of the FDTD method. Whereas space decomposing algorithms help enlarge the analyzed area represented by a grid of elements built of electromagnetic field components presented in a differential form. Thanks to that it is possible to compute areas of great capacity, greater than the com-putational abilities of a single PC unit. The work focuses on presenting the results of efficiency examination of the parallel program based on this method. The author decided to show algorithms implemented on a homogeneous cluster, as well as in a heterogeneous one-with the use of an additional dynamic decomposition of the analyzed area.
Źródło:
Pomiary Automatyka Kontrola; 2010, R. 56, nr 2, 2; 111-114
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determining the Distribution of Stochastic Impulses Acting on a High Frequency System through an Analysis of Its Vibrations
Autorzy:
Jabłoński, M.
Ozga, A.
Korbiel, T.
Pawlik, P.
Powiązania:
https://bibliotekanauki.pl/articles/1504209.pdf
Data publikacji:
2011-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
45.10.-b
45.30.+s
Opis:
The motion of an oscillator with damping excited by impulses has the form $ξ_t = \frac{1}{\sqrt{a^2 - b^2}} \sum_{0
Źródło:
Acta Physica Polonica A; 2011, 119, 6A; 977-980
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An analysis of the performance of genetic programming for realised volatility forecasting
Autorzy:
Yin, Z.
O’Sullivan, C.
Brabazon, A.
Powiązania:
https://bibliotekanauki.pl/articles/91765.pdf
Data publikacji:
2016
Wydawca:
Społeczna Akademia Nauk w Łodzi. Polskie Towarzystwo Sieci Neuronowych
Tematy:
realised volatility
genetic programming
high frequency data
Opis:
Traditionally, the volatility of daily returns in financial markets is modeled autoregressively using a time-series of lagged information. These autoregressive models exploit stylised empirical properties of volatility such as strong persistence, mean reversion and asymmetric dependence on lagged returns. While these methods can produce good forecasts, the approach is in essence atheoretical as it provides no insight into the nature of the causal factors and how they affect volatility. Many plausible explanatory variables relating market conditions and volatility have been identified in various studies but despite the volume of research, we lack a clear theoretical framework that links these factors together. This setting of a theory-weak environment suggests a useful role for powerful model induction methodologies such as Genetic Programming (GP). This study forecasts one-day ahead realised volatility (RV) using a GP methodology that incorporates information on market conditions including trading volume, number of transactions, bid-ask spread, average trading duration (waiting time between trades) and implied volatility. The forecasting performance from the evolved GP models is found to be significantly better than those numbers of benchmark forecasting models drawn from the finance literature, namely, the heterogeneous autoregressive (HAR) model, the generalized autoregressive conditional heteroscedasticity (GARCH) model, and a stepwise linear regression model (SR). Given the practical importance of improved forecasting performance for realised volatility this result is of significance for practitioners in financial markets.
Źródło:
Journal of Artificial Intelligence and Soft Computing Research; 2016, 6, 3; 155-172
2083-2567
2449-6499
Pojawia się w:
Journal of Artificial Intelligence and Soft Computing Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative analysis of methods for hourly electricity demand forecasting in the absence of data - a case study
Analiza porównawcza metod prognozowania godzinnego zapotrzebowania na energię elektryczną przy brakach w danych - studium przypadku
Autorzy:
Zawadzki, Jan
Powiązania:
https://bibliotekanauki.pl/articles/2194900.pdf
Data publikacji:
2023
Wydawca:
Akademia Bialska Nauk Stosowanych im. Jana Pawła II w Białej Podlaskiej
Tematy:
forecasting
missing data
time series
high frequency
Opis:
Scope and purpose of work: This paper examines the impact of the number of gaps in data, the analytical form, and the model type selection criterion on the accuracy of interpolation and extrapolation forecasts for hourly data. Materials and methods: Forecasts were developed on the basis of predictors that are based on: classical time series forecasting models and regression time series forecasting models, hybrid time series forecasting models and hybrid regression forecasting models for uncleared series, and exponential smoothing models for cleared series of two or three types of seasonal fluctuations, with minimum estimates of errors in interpolation or extrapolation forecasts. Results: Adaptive and hybrid regression models have proved to have the most favorable predictive properties. Most hybrid time series models for systematic and non-systematic gaps and for both analytical forms are single models that generally describe fluctuations within a 24-hour cycle. Conclusions: The lowest estimators of prediction errors involving interpolation were obtained for exponential smoothing models, followed by hybrid regression models. A reverse sequence was obtained for extrapolative forecasting.
Źródło:
Economic and Regional Studies; 2023, 16, 1; 34-50
2083-3725
2451-182X
Pojawia się w:
Economic and Regional Studies
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wyznaczanie właściwości uziemień metodami statycznymi, wysokoczęstotliwościowymi i udarowymi
Determination of earthing properties using static, high frequency and impulse methods
Autorzy:
Wołoszyk, M.
Wojtas, S.
Powiązania:
https://bibliotekanauki.pl/articles/157090.pdf
Data publikacji:
2008
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
uziemienie
metoda udarowa
rezystancja
metoda wysokoczęstotliwościowa
earthing
resistance
impulse method
high frequency method
Opis:
Podstawowym parametrem charakteryzującym skuteczność działania uziemienia jest jego rezystancja, a niekiedy rezystancja udarowa lub impedancja. Parametry te stosowane są często zamiennie chociaż wyznacza się je różnymi metodami i często mają one różne wartości liczbowe dla tego samego uziemienia. W artykule przedstawiono różne metody pomiaru tych parametrów oraz zaprezentowano wyniki badań porównawczych wykonanych przy użyciu metody statycznej, wysokoczęstotliwościowej oraz udarowej. Omówiono obszary zastosowań oraz ograniczenia omawianych metod, a także typowe błędy związane z interpretacją wyników i błędy w dobrze metody.
The basic parameter for evaluating the earthing is usually its resistance. Sometimes the earthing properties are described by means of its impulse resistance or impedance. These parameters are determined by different methods and they often have different numerical values for the same earthing. The paper presents different methods for measuring the earthing parameters mentioned above and the results of comparative investigations obtained from the static, high frequency and impulse procedures. The aplication areas and limitations of all the described measurement methods as well as typical mistakes are described. The main reasons for the mistakes are usually wrong interpretations of the obtained results and wrong choice of the measurement method.
Źródło:
Pomiary Automatyka Kontrola; 2008, R. 54, nr 12, 12; 836-838
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of High Frequency Imaging and Doppler System for the Measurements of the Radial Artery Flow-Mediated Dilation
Autorzy:
Nowicki, Andrzej
Gambin, Barbara
Secomski, Wojciech
Trawiński, Zbigniew
Szubielski, Michał
Tymkiewicz, Ryszard
Olszewski, Robert
Powiązania:
https://bibliotekanauki.pl/articles/176847.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
flow mediated dilation
shear rate
axial resolution
elevation resolution
pulsed Doppler
ultrasonic imaging
Opis:
Objectives: In the article we describe the new, high frequency, 20 MHz scanning/Doppler probe designed to measure the flow mediated dilation (FMD) and shear rate (SR) close to the radial artery wall. Methods: We compare two US scanning systems, standard vascular modality working below 12 MHz and high frequency 20 MHz system designed for FMD and SR measurements. Axial resolutions of both systems were compared by imaging of two closely spaced food plastic foils immersed in water and by measuring systolic/diastolic diameter changes in the radial artery. The sensitivities of Doppler modalities were also determined. The diagnostic potential of a high frequency system in measurements of FMD and SR was studied in vivo, in two groups of subjects, 12 healthy volunteers and 14 patients with stable coronary artery disease (CAD). Results: Over three times better axial resolution was demonstrated for a high frequency system. Also, the sensitivity of the external single transducer 20 MHz pulse Doppler proved to be over 20 dB better (in terms of a signal-to-noise ratio) than the pulse Doppler incorporated into the linear array. Statistically significant differences in FMD and FMD/SR values for healthy volunteers and CAD patients were confirmed, p-values < 0:05. The areas under Receiver Operating Characteristic (ROC) curves for FMD and FMD/SR for the prediction CAD had the values of 0.99 and 0.97, respectively. Conclusions: These results justify the usefulness of the designed high-frequency scanning system to determine the FMD and SR in the radial artery as predictors of coronary arterial disease.
Źródło:
Archives of Acoustics; 2019, 44, 4; 637-644
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The potential for real-time testing of high-frequency trading strategies through a developed tool during volatile market conditions
Autorzy:
Vaitonis, Mantas
Korovkinas, Konstantinas
Powiązania:
https://bibliotekanauki.pl/articles/30148245.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Promocji Wiedzy
Tematy:
high frequency trading
cryptocurrencies
algorithmic trading
multidimensional matrice
parallelization
simulation
Opis:
This study presents a method for testing high-frequency trading (HFT) for algorithms on GPUs using kernel parallelization, code vectorization, and multidimensional matrices. The research evaluates HFT strategies within algorithmic cryptocurrency trading in volatile market conditions, particularly during the COVID-19 pandemic. The study's objective is to provide an efficient and comprehensive approach to assessing the efficiency and profitability of HFT strategies. The results show that the method effectively evaluates the efficiency and profitability of HFT strategies, as demonstrated by the Sharp ratio of 2.29 and the Sortino ratio of 2.88. The authors suggest that further study on HFT testing methods could be conducted using a tool that directly connects to electronic marketplaces, enabling real-time receipt of high-frequency trading data and simulation of trade decisions. Finally, the study introduces a novel method for testing HFT algorithms on GPUs, offering promising results in assessing the efficiency and profitability of HFT strategies during volatile market conditions.
Źródło:
Applied Computer Science; 2023, 19, 2; 63-81
1895-3735
2353-6977
Pojawia się w:
Applied Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zastosowanie ultrasonografii wysokich częstotliwości w zamykaniu drobnych naczyń krwionośnych
Application of high-frequency ultrasonography in closing small blood vessels
Autorzy:
Mlosek, Robert Krzysztof
Malinowska, Sylwia
Powiązania:
https://bibliotekanauki.pl/articles/1057939.pdf
Data publikacji:
2014
Wydawca:
Medical Communications
Tematy:
esthetic medicine
high-frequency ultrasonography
laser closing of vessels
phlebology
sclerotherapy
skin ultrasound examination
ultrasonography
flebologia
laserowe zamykanie naczyń
medycyna estetyczna
skleroterapia
ultrasonografia
ultrasonografia skóry
ultrasonografia wysokich częstotliwości
Opis:
One of the most common treatments performed in phlebological and aesthetic medicine clinics is closing small blood vessels in the lower extremities, so-called telangiectasias and reticular vessels. Currently, there are several methods that allow for closing the dilated vessels and obtaining desirable effects, both therapeutic and aesthetic. Unfortunately, despite applying various methods and instruments, the effects of treatments are frequently not satisfactory. The factor that largely contributes to decreasing the efficacy of such procedures is complicated anatomy of the venous system and the lack of a method to precisely specify the vessel’s course, its diameter, location in the skin etc. High-frequency ultrasonography is a method enabling accurate determination of the vessels’ course as well as the measurement of their basic parameters, such as diameter, depth in the skin and presence or absence of perfusion. Thanks to ultrasound imaging with the use of high-frequency transducers, an adequate treatment method and procedure parameters may be selected, which entails enhancing the efficacy of the procedure itself. Ultrasonography may be also used for monitoring the performed procedures.
Jednym z najczęściej wykonywanych zabiegów w gabinetach flebologicznych lub medycyny estetycznej jest zamykanie drobnych naczyń krwionośnych na kończynach dolnych, tj. teleangiektazji i naczyń siatkowatych. Obecnie dysponujemy kilkoma metodami, które pozwalają na zamknięcie poszerzonych naczyń krwionośnych i uzyskanie pożądanego efektu zarówno terapeutycznego, jak i estetycznego. Niestety, mimo stosowania różnych metod i urządzeń bardzo często efekty prowadzonych zabiegów nie są zadowalające. Czynnikiem, który w dużym stopniu przyczynia się do obniżenia skuteczności zabiegów, jest skomplikowana anatomia układu żylnego i brak metody pozwalającej na dokładne określenie przebiegu naczynia, jego średnicy, położenia w skórze etc. Metodą umożliwiającą precyzyjne określenie przebiegu naczyń, a także pomiar podstawowych parametrów, takich jak średnica naczynia, głębokość położenia w skórze, brak lub obecność przepływu w naczyniu, jest ultrasonografia wysokich częstotliwości. Dzięki ultrasonograficznemu obrazowaniu naczyń za pomocą głowic wysokich częstotliwości można dobrać odpowiednią metodę leczenia, parametry zabiegowe, a tym samym zwiększyć jego skuteczność. Ultrasonografia służy również do monitorowania wykonywanych zabiegów.
Źródło:
Journal of Ultrasonography; 2014, 14, 58; 320-327
2451-070X
Pojawia się w:
Journal of Ultrasonography
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A High-Efficient Low-Voltage Rectifier for CMOS Technology
Autorzy:
Jendernalik, W.
Jakusz, J.
Blakiewicz, G.
Kłosowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/220356.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
CMOS rectifier
high frequency rectifier
wireless power transmission
Opis:
A new configuration of rectifier suiting CMOS technology is presented. The rectifier consists of only two n-channel MOS transistors, two capacitors and two resistors; for this reason it is very favourable in manufacturing in CMOS technology. With these features the rectifier is easy to design and cheap in production. Despite its simplicity, the rectifier has relatively good characteristics, the voltage and power efficiency, and bandwidth greater than 89%, 87%, and 1 GHz, respectively. The performed simulations and measurements of a prototype circuit fully confirmed its correct operation and advantages.
Źródło:
Metrology and Measurement Systems; 2016, 23, 2; 261-268
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low- and high-frequency elastic scattering analysis of fluid-filled, flat-endcapped cylindrical shells proud on a sandy seabed
Autorzy:
Tesei, A.
Groen, J.
Powiązania:
https://bibliotekanauki.pl/articles/331639.pdf
Data publikacji:
2008
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
sandy seabed
at-sea scattering data
hydroacoustics
Opis:
This work presents the analysis of at-sea scattering data by a man-made target which supports the excitation of strong structural waves or resonances, not only at low but even at high frequency (ka>100). The object is a water-filled, flat-endcapped, 2m-long, steel cylindrical shell, measured both at low frequency (2-10 kHz) and at high frequency (120 kHz), where different elastic phenomena are supported and identified. In particular, in the high-frequency sonar images obtained with an AUV-mounted synthetic aperture sonar, significant elastic effects clearly appear, which are interpreted as echoes of a shear wave travelling axially along the cylindrical shell. For interpretation of sonar images it is crucial to understand and predict these supplementary scattering mechanisms.
Źródło:
Hydroacoustics; 2008, 11; 388-400
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modele hierarchiczne w prognozowaniu zmiennych o wysokiej częstotliwości obserwowania w warunkach braku pełnej informacji
Hierarchical models in forecasting of the high-frequency variables in the conditions of lack of full information
Autorzy:
Szmuksta-Zawadzka, Maria
Zawadzki, Jan
Powiązania:
https://bibliotekanauki.pl/articles/425235.pdf
Data publikacji:
2014
Wydawca:
Wydawnictwo Uniwersytetu Ekonomicznego we Wrocławiu
Tematy:
high-frequency data
hierarchical models
incomplete time series
Opis:
The paper presents a procedure of application of regular hierarchical models in forecasting missing data in high-frequency time series with cyclical fluctuations. Annual, weekly and daily cycles of seasonal fluctuation have additive character. Separately regular hierarchical models have been built for even length cycles.Theoretical considerations are illustrated with an empirical example.
Źródło:
Econometrics. Ekonometria. Advances in Applied Data Analytics; 2014, 4(46); 72-84
1507-3866
Pojawia się w:
Econometrics. Ekonometria. Advances in Applied Data Analytics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wysokoczęstotliwościowy indukcyjny piec rurowy do wyznaczania temperatury topliwości popiołu
High Frequency Induction Tube Furnace for Determining Ash Melting Temperature
Autorzy:
Kurytnik, Igor Piotr
Lis, Stanisław
Tomasik, Marcin
Nawara, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/277357.pdf
Data publikacji:
2020
Wydawca:
Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
Tematy:
topliwość popiołu
pomiar temperatury
wysokotemperaturowy piec indukcyjny
cyfrowa analiza obrazu
ash melting
temperature measurement
high temperature induction furnace
digital image analysis
Opis:
Praca opisuje problematykę wyznaczania temperatury topliwości popiołu za pomocą indukcyjnego pieca rurowego wykonanego wg autorskiego projektu, realizującego proces spalania (stapiania) próbek popiołu zgodnie z normą z PN-ISO-540:2001. Proces ten jest kontrolowany przez sterownik PLC z zaprogramowanym algorytmem regulacji i stabilizacji temperatury PID, urządzenie wyposażone jest w termoparę typu S oraz system cyfrowej rejestracji i analizy obrazu. Rejestracja obrazu jest niezbędna do wyznaczenia temperatury płynięcia popiołu, wartość ta jest identyfikowana przy zmianie stanu skupienia z stałego w ciekły, próbka popiołu przechodzi z walcowatego kształtu w płynną postać. Prowadzone badania są niezwykle ważne w kontekście spalania biomasy w kotłach, dobór optymalnej temperatury spalania pozwoli przeciwdziałać powstawaniu ceramicznej warstwy na ściankach kotła, która pogarsza jego właściwości eksploatacyjne i w szerszej perspektywie czasu doprowadzi do jego wyłączenia z eksploatacji. Wybrane elektrociepłownie są zobligowane do spalania biomasy w ramach realizacji polityki wzrostu udziału energii odnawialnej w ogólnym bilansie energetycznym, m.in. przez wykorzystanie biomasy. Ponieważ pochodzenie biomasy jest zróżnicowane, stąd również jej skład fizyko-chemiczny jako paliwo jest niejednorodny, dlatego elektrociepłownie muszą określać temperaturę płynięcia popiołu dla poszczególnych partii tego paliwa.
The work describes the problem of determining the fusibility of ash using an induction tube furnace made according to the author’s project, carrying out the process of burning (melting) ash samples in accordance with the PN-ISO-540: 2001 standard. This process is controlled by a PLC with a programmed PID temperature regulation and stabilization algorithm, the device is equipped with a S-type thermocouple and a digital image recording and analysis system. Image registration is necessary to determine the ash flow temperature, this value is identified when the state of aggregation changes from solid to liquid, the ash sample passes from a cylindrical shape to a liquid form. The conducted research is extremely important in the context of biomass combustion in boilers, the selection of the optimal combustion temperature will prevent the formation of a ceramic layer on the boiler walls, which deteriorates its operational properties and in the longer term will lead to its decommissioning. Selected combined heat and power plants are obliged to burn biomass as part of the policy of increasing the share of renewable energy in the overall energy balance, including by using biomass. Because the origin of biomass is varied, hence its physico-chemical composition as a fuel is heterogeneous, therefore CHP plants must determine the ash flow temperature for individual batches of this fuel.
Źródło:
Pomiary Automatyka Robotyka; 2020, 24, 2; 45-50
1427-9126
Pojawia się w:
Pomiary Automatyka Robotyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Symulacja numeryczna rzeczywistej baterii kondensatorowej pracującej w układach wielkiej częstotliwości w zastosowaniu do falowników. Część I. Kondensatory dla baterii wielkiej częstotliwości
Numerical simulation of the actual capacitor bank working in high frequency systems for use in inverters. Part I. Capacitors for high frequency banks
Autorzy:
Gąsiorski, A.
Posyłek, Z.
Roman, A.
Powiązania:
https://bibliotekanauki.pl/articles/103791.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Humanistyczno-Przyrodniczy im. Jana Długosza w Częstochowie. Wydawnictwo Uczelniane
Tematy:
kondensator
wielka częstotliwość
układ rezonansowy falowników
capacitors
high frequency
resonant systems of inverters
Opis:
W części I pracy pokazano rzeczywiste problemy związane z zastosowaniem kondensatorów wielkiej częstotliwości w układach rezonansowych falowników oraz przedstawiono kondensator jako element obwodu. Pokazano historyczne początki budowy pierwszych kondensatorów oraz pierwsze ich zastosowania w Częstochowie. Omówiono również sposób budowy i wielkości materiałowe stosowane do produkcji pojedynczych kondensatorów, zwłaszcza wykonanych z tworzyw, łączonych w baterie dla układów wielkiej częstotliwości stosowanych w wykonawczych (roboczych) układach rezonansowych falowników.
Part I of the paper shows the real problems associated with the use of high frequency capacitors in resonance systems of inverters and the capacitor is shown as a circuit element. The historical beginnings of the construction of the first capacitors and the first historical applications in Czestochowa are shown. The method of construction and material sizes used for the production of single capacitors, especially plastic, are combined in banks for high frequency circuits used in executive (working) resonant systems of inverters.
Źródło:
Prace Naukowe Akademii im. Jana Długosza w Częstochowie. Technika, Informatyka, Inżynieria Bezpieczeństwa; 2017, T. 5; 209-222
2300-5343
Pojawia się w:
Prace Naukowe Akademii im. Jana Długosza w Częstochowie. Technika, Informatyka, Inżynieria Bezpieczeństwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental Study of Identifying Emission Sources of Acoustic Signals on the Cylinder Body of a Two-Stroke Marine Diesel Engine
Autorzy:
Dong, Xuan Thin
Nguyen, Manh Hung
Powiązania:
https://bibliotekanauki.pl/articles/1953513.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
acoustic emission
two-stroke marine diesel engine
experimental method
low-to-high frequency ranges
medium-to-high frequency ranges
vibration
Opis:
In this paper, an experimental method was utilized to investigate acoustic emission (AE) characteristics and to identify emission sources of the nonlinear AE signal on the cylinder body of a large low-speed two-stroke marine diesel engine in real-working conditions on the sea in misfiring and normal firing modes. Measurements focused on the AE signal acquired in a transverse direction in low-frequency (20-80 kHz), medium-frequency (100-400 kHz) and high-frequency (400-900 kHz) ranges. The collected signals were analyzed on the crank angle and crank angle-frequency domains. The results showed that all potential sources of the nonlinear AE signal could be mapped in the low-frequency range. However, only the AE signal caused by the combustion process at around the top dead center could be well-observed in the medium-to-high-frequency range. The findings also revealed that in normal firing conditions, the AE energy radiated by friction in the down-stroke period was smaller than in the up-stroke process due to gas-sealing forces. Moreover, the AE energy in the misfiring condition was higher than in the normal firing state. These outcomes considerably contributed understandings to characteristics of friction and wear around the mid-stroke area of the cylinder on a two-stroke marine diesel engine.
Źródło:
Archives of Acoustics; 2021, 46, 1; 105-119
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dehydration of no flotation size coal's slimes on the deck of high-frequency screen with multislopes area's working surface
Оbezvozhivanie ugolnogo shlama na site vysokochastotnogo vibracionnogo grokhota s raznonaklonnymi uchastkami rabochejj poverkhnosti
Autorzy:
Eremejev, I.
Polulyakh, A.
Polulyakh, D.
Grachyov, O.
Powiązania:
https://bibliotekanauki.pl/articles/791890.pdf
Data publikacji:
2014
Wydawca:
Komisja Motoryzacji i Energetyki Rolnictwa
Tematy:
coal
dehydration
physical model
working surface
high-frequency screen
Źródło:
Teka Komisji Motoryzacji i Energetyki Rolnictwa; 2014, 14, 2
1641-7739
Pojawia się w:
Teka Komisji Motoryzacji i Energetyki Rolnictwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Trading volume and volatility patterns across selected Central European stock markets from microstructural perspective
Autorzy:
Gurgul, H.
Syrek, R.
Powiązania:
https://bibliotekanauki.pl/articles/1201257.pdf
Data publikacji:
2017
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
high frequency data
flexible Fourier form regression
intraday patterns
Opis:
In this paper, the intraday patterns of trading volumes and volatilities as well as autocorrelations are investigated using high-frequency data. The analysis is performed for companies listed in the main German, Austrian, and Polish indices with the aid of Flexible Fourier Form regression. We have found some similarities to prior investigations in light of stylized facts about intraday patterns. We noted the differences in intraday patterns and autocorrelations across markets, which depend on the maturity level of the market. The most-regular patterns are observed for DAX companies. Additionally, using day-of-the-week dummies, we discover some peaks that can be associated with macroeconomic announcements in Germany and the US. This leads to conclusions that the day of the week and announcements should be taken into account in modeling volatilities (returns) and volumes from high-frequency data.
Źródło:
Managerial Economics; 2017, 18, 1; 87-101
1898-1143
Pojawia się w:
Managerial Economics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Higher - order field - dependent terms in spin Hamiltonians for transition ions : implications for high - magnetic field and high - frequency EMR measurements
Autorzy:
Rudowicz, Cz.
Powiązania:
https://bibliotekanauki.pl/articles/148384.pdf
Data publikacji:
2013
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
electron magnetic resonance (EMR)
high-magnetic field and high-frequency EMR (HMF-EMR)
generalized spin Hamiltonians (GSH)
higher-order field-dependent (HOFD) terms
zero-field splitting (ZFS) terms
transition ions in crystals
Opis:
An overview of theoretical background of the higher-order field-dependent (HOFD) terms in the generalized spin Hamiltonians for transition ions and current status of experimental studies of the HOFD terms is provided in the nutshell. The terms nonlinear in the magnetic field (B) of the type: B2S2, B3S, B5S or B2I2, B3I, B5I, where S and I is the electronic and nuclear spin, respectively, are of particular importance as compared with the usual linear Zeeman term B.g.S. This is due to the high B values, up to 100 T (pulsed fields), achievable at present in the high-magnetic field and/ or high-frequency electron magnetic resonance (HMF-EMR) measurements of magnetic and spectroscopic properties. A blueprint for future theoretical and experimental studies of the HOFD terms is proposed taking into account their implications for HMF-EMR measurements
Źródło:
Nukleonika; 2013, 58, 3; 341-345
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Palatalization as a Non-Uniform Process Affecting Grammatical Words: A Comparison of Data from Dialectally Identified and Unidentified Late Middle English Texts
Autorzy:
Kocel, Agnieszka
Powiązania:
https://bibliotekanauki.pl/articles/888650.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Warszawski. Wydawnictwa Uniwersytetu Warszawskiego
Tematy:
palatalization
high frequency lemmas
Middle English
dialects
lexical diffusion
Opis:
The process of palatalization has exerted much influence on the forms of four highfrequency lemmas, EACH, MUCH, SUCH, WHICH, revealing significant heterogeneity in terms of palatalized and non-palatalized variants being used in the close vicinity of each other both in the Northern and Southern dialects as well as in the texts of unknown origin. Such unpredictability of the process, accounted for by the operation of lexical diffusion, raises questions concerning the manner of how palatalization, being one of the major phonological changes, affected the lexis and phonological system of Middle English, proving to be much less consistent than expected.
Źródło:
Anglica. An International Journal of English Studies; 2013, 22/2; 5-25
0860-5734
Pojawia się w:
Anglica. An International Journal of English Studies
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of acoustical and optical zooplankton measurements using an acoustic scattering model: A case study from the Arctic frontal zone
Autorzy:
Szczucka, Joanna
Błachowiak-Samołyk, Katarzyna
Trudnowska, Emilia
Hoppe, Łukasz
Powiązania:
https://bibliotekanauki.pl/articles/2046858.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Arctic
Svalbard
zooplankton
high−frequency echosounding
sound scattering model
Źródło:
Polish Polar Research; 2016, 37, 1; 67-88
0138-0338
2081-8262
Pojawia się w:
Polish Polar Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mathematical modelling of the high frequency vibrations during cold rolling process
Matematyczne modelowanie drgań wysokoczęstotliwościowych występujących podczas walcowania blach na zimno
Autorzy:
Świątoniowski, A.
Bar, O.
Powiązania:
https://bibliotekanauki.pl/articles/351698.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
rolling stand
self-excited vibrations
high-frequency vibrations
Timoshenko beam mode
walcowanie blach
drgania samowzbudne
drgania wysokoczęstotliwościowe
model wiązki Timoshenko
Opis:
The study explores the model of high-frequency vibrations during the continuous rolling processes, the underlying assumption being that vibrations are self-excited. The effects of rolling stand and rolling process parameters on the nature and intensity of vibrations are investigated. The appearance of darkened streaks occurring on the metal sheet is explained. The results are compared with the data quoted in literature on the subject.
W pracy przedstawiono model opisujący drgania o wysokiej częstości, występujące w trakcie ciągłego walcowania blach. Model ten jest oparty na założeniu samowzbudności procesu. Zbadano wpływ parametrów klatki oraz procesu walcowania na charakter i intensywność drgań. Wyjaśniono również zjawisko powstawania na powierzchni blachy zaciemnionych pasków. Otrzymane wyniki porównano z wynikami badań.
Źródło:
Archives of Metallurgy and Materials; 2013, 58, 4; 1085-1091
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prognozowanie brakujących danych dla szeregów o wysokiej częstotliwości oczyszczonych z sezonowości
Forecasting missing data for seasonal adjusted high frequency time series
Autorzy:
Szmuksta-Zawadzka, Maria
Zawadzki, Jan
Powiązania:
https://bibliotekanauki.pl/articles/585670.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Ekonomiczny w Katowicach
Tematy:
Dane o wysokiej częstotliwości
Luki w danych
Prognozowanie
Wyrównywanie wykładnicze
Złożona sezonowość
Complex seasonality
Exponential smoothing
Forecasting
High frequency time series
Unsystematic gaps
Opis:
W pracy przedstawione zostało wykorzystanie wybranych modeli adaptacyjnych w prognozowania zmiennych o bardzo wysokiej częstotliwości obserwowania, na podstawie szeregów z lukami niesystematycznymi, z których wyeliminowano dwa lub trzy rodzaje sezonowości. Egzemplifikacją rozważań teoretycznych stanowi przykład empiryczny, dotyczący kształtowania się zapotrzebowania na moc energetyczną w okresach godzinnych w aglomeracji A.
In this paper was presented application of selected exponential smoothing models in forecasting very high frequency variables on the basis of time series with unsystematic gaps, from which two or three types of seasonal fluctuations were eliminated. Exemplification of theoretical considerations will be an empirical example, concerning the power demand in agglomeration A in hourly periods.
Źródło:
Studia Ekonomiczne; 2016, 289; 205-217
2083-8611
Pojawia się w:
Studia Ekonomiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of Low- and High-Frequency Side Bands of Notched Noise on Masking and Auditory Filter Shape at Very High Frequencies
Autorzy:
Kordus, M.
Kowalewski, B.
Powiązania:
https://bibliotekanauki.pl/articles/177387.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
auditory filters
notched noise
Patterson’s method
masking
Opis:
This paper is concerned with the determination of the auditory filter shape using the notched noise method with noise bands symmetrically located above and below a probe frequency of 10 kHz. Unlike in the classical experiments conducted with the use of Patterson method the levels as well as power spectrum densities of the lower and upper component bands of the notched noise masker were not the same and were set such as to produce the same amount of masking at the 10-kHz frequency. The experiment consisted of three conditions in which the following values were determined: (I) the detection threshold for a 10-kHz probe tone in the presence of a noise masker presented below the tone’s frequency; (II) the level of a noise masker presented above the 10-kHz probe tone frequency, at which the masker just masked the probe tone, (III) the detection threshold for a probe tone in the presence of a notched-noise masker. The data show a considerable amount of variability across the subjects, however, the resulting frequency characteristics of the auditory filters are consistent with those presented in the literature so that the Equivalent Rectangular Bandwidth is less than 11% of their centre frequency.
Źródło:
Archives of Acoustics; 2015, 40, 3; 329-336
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Connectivity Solutions in Automated Trading
Autorzy:
Popławski, P.
Powiązania:
https://bibliotekanauki.pl/articles/226896.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
telecommunications
digital systems
systems architecture
automated trading
high frequency trading
Opis:
The study analyzes the architecture and deployment of direct market access (DMA) solutions for automated trading of securities. It provides an overview of automated trading systems including: trading floor architecture, trading environment connectivity, and DMA solutions. Among a range of factors influencing operational capacities, round-trip latency has been recognized as the key quality differentiator of an automated trading floor. The study identifies potential opportunity costs due to latency levels as a major driver of technological progress in trading in highly liquid market conditions.
Źródło:
International Journal of Electronics and Telecommunications; 2015, 61, 4; 403-408
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of a High-efficiency and High-frequency 10-kW/800-V Three-phase PWM Converter with Direct Power Factor Control
Autorzy:
Barlik, Roman
Grzejszczak, Piotr
Leszczyński, Bernard
Szymczak, Marek
Powiązania:
https://bibliotekanauki.pl/articles/226672.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
three-phase PWM rectifier
reactive power compensator
silicon carbide MOSFET
bidirectional power flow
direct power control (DPC)
DC voltage regulation
power factor correction (PFC)
LCL filter
Opis:
The paper presents a concept of a control system for a high-frequency three-phase PWM grid-tied converter (3x400 V / 50 Hz) that performs functions of a 10-kW DC power supply with voltage range of 600÷800 V and of a reactive power compensator. Simulation tests (in PLECS) allowed proper selection of semiconductor switches between fast IGBTs and silicon carbide MOSFETs. As the main criterion minimum amount of power losses in semiconductor devices was adopted. Switching frequency of at least 40 kHz was used with the aim of minimizing size of passive filters (chokes, capacitors) both on the AC side and on the DC side. Simulation results have been confirmed in experimental studies of the PWM converter, the power factor of which (inductive and capacitive) could be regulated in range from 0.7 to 1.0 with THDi of line currents below 5% and energy efficiency of approximately 98.5%. The control system was implemented in Texas Instruments TMS320F28377S microcontroller.
Źródło:
International Journal of Electronics and Telecommunications; 2019, 65, 4; 619-624
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fast Fourier Transform detection and reduction of high-frequency errors from the results of surface topography profile measurements of honed textures
Autorzy:
Podulka, Przemysław
Powiązania:
https://bibliotekanauki.pl/articles/1841821.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
surface topography
measurement
measurement errors
measurement noise
cylinder liner
oil pockets
dimple
valley
texture features
Opis:
In this paper, various type of noise detection procedures with surface topography profile analysis were proposed, compared (studied) and suggested. The honed cylinder liner surface textures with additionally burnished oil pockets were measured with a stylus or optical approaches. Measurement errors, defined as high-frequency measurement noise, were taken into sufficient consideration. It was proposed to select the noise detection methods more with profile (2D) than areal (3D) assessments; some-frequency noise was much easier to observe in profile than surface analysis. Moreover, applications of various type of regular filtration methods, mostly based on Gaussian functions, were compared with Fast Fourier Transform filtration for detection or reduction of some (high) frequency-defined measurement errors.
Źródło:
Eksploatacja i Niezawodność; 2021, 23, 1; 84-93
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Palatalization in Grammatical Words as Reflected in Unclassified Late Middle English Sources
Autorzy:
Kocel, Agnieszka
Powiązania:
https://bibliotekanauki.pl/articles/888843.pdf
Data publikacji:
2012
Wydawca:
Uniwersytet Warszawski. Wydawnictwa Uniwersytetu Warszawskiego
Tematy:
palatalization
Late Middle English
dialects
unclassified
corpora
high-frequency items
Opis:
Although palatalization changing [k] into [tS] was most widespread in Southumbria, the previous examination (Kocel 2009, 2010) has already proved that on no account can it be perceived as a homogeneous process. This lack of consistency is reflected in many instances of palatal forms found in the North alongside many nonpalatal ones encountered in the East Midlands and London. Consequently, the substantial number of such “odd” forms seems to defy the existence of clear-cut boundaries between the above mentioned areas, allowing for an unhindered influx and amalgamation of ostensibly dialect-specific variants. The problem appears even more complex, taking into account the vast collection of dialectally unidentified Middle English texts which, containing both palatal and nonpalatal forms, only corroborate the fact that palatalization could not be dialect or even area specific. The multitude of variants present in those texts, a result of the Scandinavian influence and dialectal borrowing, point to the process of the lexical diffusion of these forms across the whole English territory, affecting in particular such high-frequency items as the grammatical words each, much, such and which. The aim of the study, thus, will be to determine the extent of palatalization affecting these grammatical words, through the analysis of the spelling/phonological discrepancies and the distribution of each, much, such and which in unclassified Late Middle English sources. The data come from the Innsbruck Corpus of Middle English Prose, The Middle English Dictionary and A Linguistic Atlas of Late Mediaeval English.
Źródło:
Anglica. An International Journal of English Studies; 2012, 21/2; 4-15
0860-5734
Pojawia się w:
Anglica. An International Journal of English Studies
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-100 z 237

Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies