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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:
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:
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:
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 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:
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:
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 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:
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
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