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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:
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 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:
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:
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:
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:
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:
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:
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:
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:
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:
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:
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
Wyświetlanie 1-50 z 237

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