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Wyświetlanie 1-15 z 136
Tytuł:
Noise spectroscopy of resistive components at elevated temperature
Autorzy:
Stadler, A.W.
Zawiślak, Z.
Dziedzic, A.
Nowak, D.
Powiązania:
https://bibliotekanauki.pl/articles/221348.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
noise spectroscopy
low-frequency noise
resistance noise
low-frequency noise measurements
thick-film resistors
Opis:
Studies of electrical properties, including noise properties, of thick-film resistors prepared from various resistive and conductive materials on LTCC substrates have been described. Experiments have been carried out in the temperature range from 300 K up to 650 K using two methods, i.e. measuring (i) spectra of voltage fluctuations observed on the studied samples and (ii) the current noise index by a standard meter, both at constant temperature and during a temperature sweep with a slow rate. The 1/f noise component caused by resistance fluctuations occurred to be dominant in the entire range of temperature. The dependence of the noise intensity on temperature revealed that a temperature change from 300 K to 650 K causes a rise in magnitude of the noise intensity approximately one order of magnitude. Using the experimental data, the parameters describing noise properties of the used materials have been calculated and compared to the properties of other previously studied thick-film materials.
Źródło:
Metrology and Measurement Systems; 2014, 21, 1; 15-26
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Study of Annoyance Caused by Low-Frequency Noise During Mental Work
Autorzy:
Kaczmarska, A.
Łuczak, A.
Powiązania:
https://bibliotekanauki.pl/articles/89879.pdf
Data publikacji:
2007
Wydawca:
Centralny Instytut Ochrony Pracy
Tematy:
low-frequency noise
annoyance
working environments
Opis:
This article presents the results of an analysis of annoyance caused by low-frequency noise (including infrasonic noise) that occurs at work stations located in offices. The tests covered measurements of acoustic parameters specific for this type of noise and a survey conducted in the working environment and in laboratory conditions at a model of a work station.
Źródło:
International Journal of Occupational Safety and Ergonomics; 2007, 13, 2; 117-125
1080-3548
Pojawia się w:
International Journal of Occupational Safety and Ergonomics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reflection of low-frequency long-range sound in the ocean
Autorzy:
Didenkulov, I.
Powiązania:
https://bibliotekanauki.pl/articles/332043.pdf
Data publikacji:
2003
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
low frequency
long-range
sound
ocean
underwater
Opis:
Experimental results on energetic characteristics of low frequency (about 200 Hz) underwater channel sound reflection by ocean mountains and islands are presented. lt is investigated also sound penetration into shallow water. Transformation of vertical structure of sound field over continental slope is considered. Continental slope and shelf-wedge reflection coefficients of law frequency sound propagating in the underwater waveguide were measured. Results of the work show that low-frequency sound reflections from large-scale bottom irregularities can be important in ocean acoustics.
Źródło:
Hydroacoustics; 2003, 6; 117-124
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analiza termowizyjna zmian temperatury kończyn dolnych pod wpływem drgań ogólnych niskiej częstotliwości
Thermovision analysis of temperature changes in lower extremities after exposing to general low frequency vibrations
Autorzy:
Krzyworzeka, P.
Uhryński, A.
Powiązania:
https://bibliotekanauki.pl/articles/261640.pdf
Data publikacji:
2009
Wydawca:
Politechnika Wrocławska. Wydział Podstawowych Problemów Techniki. Katedra Inżynierii Biomedycznej
Tematy:
drgania niskoczęstotliwościowe
termowizja
thermovision
low-frequency vibrations
Opis:
W pracy przedstawiono wpływ drgań niskiej częstotliwości na zmianę temperatury w obrębie kończyn dolnych. Badania odbyły się w lipcu 2006 r. w Krynicy-Zdroju. Eksperyment polegał na przeprowadzeniu 19 dwudziestominutowych treningów z wykorzystaniem drgań ogólnych niskiej częstotliwości (pozycja stojąca), o stałej porze dnia. Przed i po ekspozycji rejestrowano zdjęcia termowizyjne kończyn dolnych. Amplituda drgań niskoczęstotliwościowych wynosiła 4 mm, częstotliwość 3,5 Hz. W eksperymencie uczestniczyło 28 osób. Otrzymane wyniki poddano analizom statystycznym w środowisku Statistica. W analizach statystycznych przyjęto poziom istotności p = 0,05, zastosowano nieparametryczny test Wilcoxona oraz parametryczny test t-studenta dla dwóch grup zmiennych zależnych. Po przeprowadzeniu badań i analiz można stwierdzić, iż po 20 minutach drgań niskiej częstotliwości obserwowane są istotne zmiany temperatur kończyn dolnych.
The influence of low frequency vibrations on temperature variations in lower extremities, is analyzed. The examination was conducted in Krynica-Zdrój in July 2006. The experiment included 19 training sessions, each lasting 20 minutes. The low frequency vibration was applied to each participant in standing position at the same time each day. Before and after the session thermal images were recorded. The low frequency vibration amplitude was 4 mm, while the frequency was 3,5 Hz. 28 participants were examined. The results were analyzed by means of Statistica software. The significance level p = 0,05 was chosen, the non-parametric Wilcoxon test and the parametric t-student test were applied for two groups of dependent variables. It was stated that 20 minutes exposure to low frequency vibrations resulted in significant changes temperature distribution within lower extremities.
Źródło:
Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna; 2009, 15, 1; 23-26
1234-5563
Pojawia się w:
Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of current noise in MOSFET-based charge-transfer device
Autorzy:
Inokawa, H.
Singh, V.
Satoh, H.
Powiązania:
https://bibliotekanauki.pl/articles/385224.pdf
Data publikacji:
2009
Wydawca:
Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
Tematy:
low-frequency noise
MOSFET
charge-transfer device
Opis:
Low-frequency current noise in the MOSFET-based charge-transfer devices was evaluated at room and cryogenic temperatures. Excessive noise, whose power was 25-50 times larger than that of room temperature, was observed at 20 K, and this hindered the accurate transfer of charge. Interestingly, the noise power was proportional to the square of the pulse frequency that drove the gates in these devices, and an expression for the noise was proposed to correlate it with the frequency, gate capacitance and fluctuation of the threshold voltage at the gate.
Źródło:
Journal of Automation Mobile Robotics and Intelligent Systems; 2009, 3, 4; 72-75
1897-8649
2080-2145
Pojawia się w:
Journal of Automation Mobile Robotics and Intelligent Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low Frequency Noise and Its Assessment and Evaluation
Autorzy:
Žiaran, S.
Powiązania:
https://bibliotekanauki.pl/articles/176925.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
low frequency sound
human being
health
evaluation
Opis:
The main aim of this paper is to present recent knowledge about the assessment and evaluation of low frequency noise and infrasound close to the threshold of hearing and the potential effects on human health. Low frequency noise generated by air flowing over a moving car with the open window is chosen as a source of noise. The noise within the interior of the car and its effects on a driver’s comfort at different velocities is analyzed. An open window at high velocity behaves as a source of specifically strong tonal low frequency noise which is annoying. The interior noise of a passenger car was measured under different conditions; while driving on normal highway and roadways. First, an octave-band analysis was used to assess the noise level and its impact on the driver’s comfort. Second, a Fast Fourier Transform (FFT) analysis was used for the detection of tonal low frequency noise. Finally, the paper suggests possibilities for scientifically assessing and evaluating low frequency noise but not only for the presented source of the sound.
Źródło:
Archives of Acoustics; 2013, 38, 2; 265-270
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Brain’s Frequency Following Responses to Low-Frequency and Infrasound
Autorzy:
Jurado, Carlos
Marquardt, Torsten
Powiązania:
https://bibliotekanauki.pl/articles/176507.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
low-frequency hearing
frequency-following response
infrasound
auditory brain
Opis:
Complaints and awareness about environmental low-frequency (LF) noise and infrasound (IS) have increased in recent years, but knowledge about perceptual mechanisms is limited. To evaluate the use of the brain’s frequency-following response (FFR) as an objective correlate of individual sensitivity to IS and LF, we recorded the FFR to monaurally presented IS (11 Hz) and LF (38 Hz) tones over a 30-phon range for 11 subjects. It was found that 11-Hz FFRs were often significant already at ~0 phon, steeply grew to 20 phon, and saturated above. In contrast, the 38-Hz FFR growth was relatively shallow and continued to 60 phon. Furthermore, at the same loudness level (30 phon), the 11-Hz FFR strength was significantly larger (4.5 dB) than for 38 Hz, possibly reflecting a higher phase synchronization across the auditory pathway. Overall, unexpected inter-individual variability as well as qualitative differences between the measured FFR growth functions and typical loudness growth make interpretation of the FFR as objective correlate of IS and LF sensitivity difficult.
Źródło:
Archives of Acoustics; 2020, 45, 2; 313-319
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Progress in stellarator research at IPP-Kharkov
Autorzy:
Moiseenko, V. E.
Lozin, O. V.
Shapoval, A. M.
Dreval, M. B.
Kulyk, Y. S.
Mironov, Y. K.
Romanov, V. S.
Pashnev, V. K.
Sorokovoy, E. L.
Petrushenya, A. A.
Ozherel’ev, F. I.
Kozulya, M. M.
Konovalov, V. G.
Maznichenko, S. M.
Garkusha, I. E.
Powiązania:
https://bibliotekanauki.pl/articles/146173.pdf
Data publikacji:
2016
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
stellarator
radio-frequency heating
low frequency modes
magnetic diagnostics
Opis:
A new antenna of ‘crankshaft’ type has been installed in the Uragan-2M device in order to increase the plasma density and heating below the ion cyclotron frequency. Antenna operation is modelled by 1D code, which solves boundary problem for time-harmonic Maxwell’s equations in radially non-uniform plasma cylinder. In recent experiments with this antenna, the SXR, CV, OV and OII emission measurements indicate that the light impurity radiation barrier is overcame at this device. Plasma with a temperature of ~50 eV exists during a short period of a few milliseconds. Then the radiation collapse comes owing to strong infl ux of impurities to the plasma column. A new magnetic diagnostics has been installed at Uragan-3M. Using it the poloidal magnetic fi eld is measured and the shift of toroidal current in major radius is registered. A miniature pinhole camera array for spatially and temporally resolved measurements of soft X-ray (SXR) plasma emission has been recently installed on the U-3M. Different shapes of the SXR emission profi le has been observed in different discharge conditions.
Źródło:
Nukleonika; 2016, 61, 2; 91-97
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Efficiency of the constant interaction force vibroisolation (WoSSO)
Autorzy:
Dobry, M. W.
Powiązania:
https://bibliotekanauki.pl/articles/279381.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
low-frequency passive vibroisolation
efficiency of force vibroisolation
Opis:
In this paper, the force efficiency of the WoSSO vibroisolation in reducing forces transferred into the base by machines and the equipment working at low operating frequencies has been discussed. To assess that efficiency, a strongly non-linear mathematical model using Lagrange equations of the second kind has been developed. That model takes into account the specific design of the vibroisolator. The mathematical model has been solved using s digital simulation method, by developing a special computer program in the MATLAB/simulink environment. The efficiency of the force vibroisolation has been determined for a specific application of the WoSSO vibroisolator. The calculated force vibroisolation efficiency exceeds 32.
Źródło:
Journal of Theoretical and Applied Mechanics; 2014, 52, 4; 1083-1091
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Sound Radiation From a Circular Hatchway
Autorzy:
Arenas, J. P.
Powiązania:
https://bibliotekanauki.pl/articles/89797.pdf
Data publikacji:
2009
Wydawca:
Centralny Instytut Ochrony Pracy
Tematy:
low-frequency noise
sound radiation
circular plate
hatchway
Opis:
Low-frequency sound radiation from vibrating plates is a practical problem often found in engineering applications. In this article, the sound radiation from a circular hatchway is examined using a discrete approach based in the acoustic resistance matrix. Since this matrix can be combined with the volume velocity vector on the discretized vibrating circular surface, the sound radiation efficiency can be estimated through matrix approaches. The limitation of the approach is discussed by using benchmark results presented in previous works. The method produces acceptable results in low frequencies when the response of the plate is dominated by one low structural mode. When the response of more than one mode is significant, the method gives good estimation of the total sound power just for frequencies up to the first resonance. However, the method can be applied to complex and irregular vibrating plane surfaces.
Źródło:
International Journal of Occupational Safety and Ergonomics; 2009, 15, 4; 401-407
1080-3548
Pojawia się w:
International Journal of Occupational Safety and Ergonomics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Modal Low Frequency Noise of an Elastically Supported Circular Plate
Autorzy:
Rdzanek, W. P.
Rdzanek, W. J.
Engel, Z.
Szemela, K.
Powiązania:
https://bibliotekanauki.pl/articles/89877.pdf
Data publikacji:
2007
Wydawca:
Centralny Instytut Ochrony Pracy
Tematy:
low frequency noise
radiation efficiency
circular plate
hatchway
Opis:
The modal low frequency noise generated by a vibrating elastically supported circular plate embedded into a flat infinite baffle has been examined. The main aim of this study is the analysis of the radiation efficiency. Low frequency approximated formulas have been presented. They are valid for all the limiting boundary conditions of the plate with its edge clamped, guided, simply supported or free as well as for all the intermediate axisymmetric boundary configurations. The formulas are expressed in the elementary form, useful for numerical computations. They are a generalization of some earlier published results. First, they are valid for axisymmetric and asymmetric modes since both kinds of modes play an important role in the low frequency range. Second, a single formula for the radiation efficiency, valid for all the axisymmetric boundary configurations, has been proposed. A numerical example for the sound power radiation has been given for some hatchway covers mounted on a ship deck.
Źródło:
International Journal of Occupational Safety and Ergonomics; 2007, 13, 2; 147-157
1080-3548
Pojawia się w:
International Journal of Occupational Safety and Ergonomics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis and measure of novel stereo-garage driven by linear induction motor
Autorzy:
Lu, Q.
Ye, Y.
Shen, J.
Powiązania:
https://bibliotekanauki.pl/articles/140630.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
FEM
linear induction motors
low frequency
stereo-garage
Opis:
The car access time is a key parameter, especially in a huge stereo-garage, where this one should be decreased as much as possible. This paper proposes a novel stereo-garage. Adopting the linear induction motors (LIMs), the system has a simple structure and rapid response capability. In the stereo-garage, several LIMs are installed below the crossbeam on a lifting platform, and several LIMs are fixed on the top of a moving frame. During the operation of LIMs, the moving frame moves forward and backward to reach the required parking place, whereas the crossbeam moves horizontally in order to take or store the vehicle rapidly. All these LIMs are the same and should be designed at a low frequency. The influences of key structure parameters and dynamic performances are investigated, based on FEM. The predicted results are validated by a prototype. Finally, the designed LIMs are successfully applied in two 8-layer stereo-garages.
Źródło:
Archives of Electrical Engineering; 2015, 64, 4; 669-678
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Observation of an Inverted Type U Solar Burst Due to AR1429 Active Region
Autorzy:
Hamidi, Z. S.
Shariff, N. N. M.
Monstein, C.
Powiązania:
https://bibliotekanauki.pl/articles/412209.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
CALLISTO
low frequency
solar burst
type U
Radio Frequency Interference (RFI)
Opis:
A detailed investigation of an inverted type U solar burst in meter region and their associated the solar flare and Coronal Mass Ejections (CMEs) has been reported. Solar type U burst has been observed at the National Space Centre, Banting, Selangor detected by the Compound Low Cost Low Frequency Transportable Observatories (CALLISTO) system in the 150 MHz till 400 MHz at the low frequency band. An inverted U type is occurring on 9th March 2012 between 4:00 UT to 4:15 UT within 1 minute (4:12 − 4:13) UT. From the dynamic spectra of CALLISTO, we have identified metric type U burst with maximum emission near the frequency 385MHz. In specific, the continuum type III burst will soon structure this burst due to our observations. Other types such as type II and IV are only appearing only after type U burst is ejected and appear at the same point of the solar flare event. Since the U burst activity coincides with the peak of the hard X-ray flare at 4:12UT in AR1429, we classified that the event is associated with the injection of the high energetic particles. In conclusion, it is confirmed that an inverted type U burst is initiated after a complex and a group solar radio burst type III.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2014, 10; 81-90
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
ON LOW-FREQUENCY ESTIMATION OF BID-ASK SPREAD IN THE STOCK MARKET
Autorzy:
Kociński, Andrzej Marek
Powiązania:
https://bibliotekanauki.pl/articles/453684.pdf
Data publikacji:
2014
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Katedra Ekonometrii i Statystyki
Tematy:
high-frequency data
low-frequency data
Roll estimator
Corwin-Schultz estimator
Opis:
In the article two popular low-frequency methods od bid-ask spread estimation are presented and applied to the stocks quoted on the Warsaw Stock Exchange (WSE): the Roll method [Roll 1984] and Corwin-Schultz method [Corwin and Schultz 2012]. The widely available data on average spreads published by WSE are used as benchmark and proxy of information, usually received from difficult to access and limited high-frequency financial data
Źródło:
Metody Ilościowe w Badaniach Ekonomicznych; 2014, 15, 2; 135-143
2082-792X
Pojawia się w:
Metody Ilościowe w Badaniach Ekonomicznych
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of the Radio Frequency Interference (RFI) in the Region of Solar Burst Type III Data At Selected CALLISTO Network
Autorzy:
Hamidi, Z. S.
Shariff, N. N. M.
Monstein, C.
Powiązania:
https://bibliotekanauki.pl/articles/412319.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
CALLISTO
low frequency
solar burst type III
Radio Frequency Interference (RFI)
Opis:
Compact Astronomical Low-frequency, Low-cost Instrument for Spectroscopy in Transportable Observatories (CALLISTO) is a global network of spectrometer system with the purpose to observe the Sun’s activities. There are 25 stations that are used for this purpose. Radio Frequency Interference (RFI) is a major obstacle when performing observation with CALLISTO. We have confirmed at least 2 stations out of 10 stations with a complete overview spectral (OVS) made available to us showed clear detection of these consistent types of RFI for each specific region. In Malaysia, these RFI are also clearly detected. The major RFI affecting CALLISTO within radio astronomical windows below 1 GHz are local electronic system specifically radio navigation (at 73.1 MHz and 75.2 MHz), broadcasting (at (i) 151 MHz, (ii) 151.8 MHz and 152 MHz), aeronautical navigation (at (i) 245.5 MHz, (ii) 248.7 MHz and (iii) 249 MHz and fixed mobile at (i) 605 MHz, (ii) 608.3 MHz, (iii) 612.2 MHz, (iv) 613.3 MHz). It is obviously showed that all sites within this region are free from interference at 320-330 MHz and is the best specific region to be considered for solar burst monitoring. We also investigate the effect of RFI on detection of solar burst. We have considered type III solar bursts on 9th March 2012 in order to measure the percentage of RFI level during the solar burst. The RFI level is as low as 6.512 % to 80.769 % above solar burst detection.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2014, 10; 38-45
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 136

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