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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:
On the Noise Hazard Assessment within the Intermediate Range of the High Audible and the Low Ultrasonic Frequencies
Autorzy:
Śliwiński, A.
Powiązania:
https://bibliotekanauki.pl/articles/177315.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ultrasonic noise assessment
high frequency audiometry
Opis:
In parallel to the ultrasonic noise assessment procedures and research activity in the field there have appeared several papers in the domain of so called high-frequency audiometry which covers the range of frequencies 8–20 kHz. They are important for recognizing the harmfulness and hazard of the audible high frequency sound components in the same range as the one of the low frequency ultrasonic noise. On the other hand there exists a certain inconsequent situation in the general approach to the problem of ultrasonic noise hazard assessment in work places environment which concerns the convention to include the frequency range of 10–20 kHz to the domain of ultrasonics. The range consists of one third octave bands of central frequencies: 10, 12.5, 16, 20 kHz and conventionally is called low frequency ultrasonic noise though at least the components of the two lowest bands are naturally audible by a majority of population (mainly young people).The paper presents a discussion related to some achievements of the two domains and some conclusions which could be useful for a more consequent description of the subject and could be taken into account in the future regulations for the ultrasonic noise assessment in work places environment.
Źródło:
Archives of Acoustics; 2016, 41, 2; 331-338
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
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:
Comparative analysis of methods for hourly electricity demand forecasting in the absence of data - a case study
Analiza porównawcza metod prognozowania godzinnego zapotrzebowania na energię elektryczną przy brakach w danych - studium przypadku
Autorzy:
Zawadzki, Jan
Powiązania:
https://bibliotekanauki.pl/articles/2194900.pdf
Data publikacji:
2023
Wydawca:
Akademia Bialska Nauk Stosowanych im. Jana Pawła II w Białej Podlaskiej
Tematy:
forecasting
missing data
time series
high frequency
Opis:
Scope and purpose of work: This paper examines the impact of the number of gaps in data, the analytical form, and the model type selection criterion on the accuracy of interpolation and extrapolation forecasts for hourly data. Materials and methods: Forecasts were developed on the basis of predictors that are based on: classical time series forecasting models and regression time series forecasting models, hybrid time series forecasting models and hybrid regression forecasting models for uncleared series, and exponential smoothing models for cleared series of two or three types of seasonal fluctuations, with minimum estimates of errors in interpolation or extrapolation forecasts. Results: Adaptive and hybrid regression models have proved to have the most favorable predictive properties. Most hybrid time series models for systematic and non-systematic gaps and for both analytical forms are single models that generally describe fluctuations within a 24-hour cycle. Conclusions: The lowest estimators of prediction errors involving interpolation were obtained for exponential smoothing models, followed by hybrid regression models. A reverse sequence was obtained for extrapolative forecasting.
Źródło:
Economic and Regional Studies; 2023, 16, 1; 34-50
2083-3725
2451-182X
Pojawia się w:
Economic and Regional Studies
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative investigation of SiC and Si power electronic devices operating at high switching frequency
Autorzy:
Zymmer, K.
Mazurek, P.
Powiązania:
https://bibliotekanauki.pl/articles/200057.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
semiconductor devices
silicon carbide
high frequency converters
Opis:
The paper presents results of measurements of the reverse recovery current and dynamic forward voltage of the silicon carbide (SiC) Schottky diodes operating at a 500 A/ěs current slope. These data were compared with the corresponding parameters determined for ultrafast silicon (Si) diodes. Results of power losses measurement in SiC Schottky diodes operating at switching frequency range of (10–200) kHz are presented and compared with corresponding data of ultrafast Si diodes. Also, results of power losses measurements in transistors of dc voltage switch are shown. Investigations were conducted with a SiC and the ultrafast Si freewheeling diode at the transistor switching frequency of 100 kHz. The results of measuring power losses dissipated in the dc converter with a SiC Schottky diode and the ultrafast silicon diode are also presented.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2011, 59, 4; 555-559
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An analysis of the performance of genetic programming for realised volatility forecasting
Autorzy:
Yin, Z.
O’Sullivan, C.
Brabazon, A.
Powiązania:
https://bibliotekanauki.pl/articles/91765.pdf
Data publikacji:
2016
Wydawca:
Społeczna Akademia Nauk w Łodzi. Polskie Towarzystwo Sieci Neuronowych
Tematy:
realised volatility
genetic programming
high frequency data
Opis:
Traditionally, the volatility of daily returns in financial markets is modeled autoregressively using a time-series of lagged information. These autoregressive models exploit stylised empirical properties of volatility such as strong persistence, mean reversion and asymmetric dependence on lagged returns. While these methods can produce good forecasts, the approach is in essence atheoretical as it provides no insight into the nature of the causal factors and how they affect volatility. Many plausible explanatory variables relating market conditions and volatility have been identified in various studies but despite the volume of research, we lack a clear theoretical framework that links these factors together. This setting of a theory-weak environment suggests a useful role for powerful model induction methodologies such as Genetic Programming (GP). This study forecasts one-day ahead realised volatility (RV) using a GP methodology that incorporates information on market conditions including trading volume, number of transactions, bid-ask spread, average trading duration (waiting time between trades) and implied volatility. The forecasting performance from the evolved GP models is found to be significantly better than those numbers of benchmark forecasting models drawn from the finance literature, namely, the heterogeneous autoregressive (HAR) model, the generalized autoregressive conditional heteroscedasticity (GARCH) model, and a stepwise linear regression model (SR). Given the practical importance of improved forecasting performance for realised volatility this result is of significance for practitioners in financial markets.
Źródło:
Journal of Artificial Intelligence and Soft Computing Research; 2016, 6, 3; 155-172
2083-2567
2449-6499
Pojawia się w:
Journal of Artificial Intelligence and Soft Computing Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A High-Efficient Low-Voltage Rectifier for CMOS Technology
Autorzy:
Jendernalik, W.
Jakusz, J.
Blakiewicz, G.
Kłosowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/220356.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
CMOS rectifier
high frequency rectifier
wireless power transmission
Opis:
A new configuration of rectifier suiting CMOS technology is presented. The rectifier consists of only two n-channel MOS transistors, two capacitors and two resistors; for this reason it is very favourable in manufacturing in CMOS technology. With these features the rectifier is easy to design and cheap in production. Despite its simplicity, the rectifier has relatively good characteristics, the voltage and power efficiency, and bandwidth greater than 89%, 87%, and 1 GHz, respectively. The performed simulations and measurements of a prototype circuit fully confirmed its correct operation and advantages.
Źródło:
Metrology and Measurement Systems; 2016, 23, 2; 261-268
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modele hierarchiczne w prognozowaniu zmiennych o wysokiej częstotliwości obserwowania w warunkach braku pełnej informacji
Hierarchical models in forecasting of the high-frequency variables in the conditions of lack of full information
Autorzy:
Szmuksta-Zawadzka, Maria
Zawadzki, Jan
Powiązania:
https://bibliotekanauki.pl/articles/425235.pdf
Data publikacji:
2014
Wydawca:
Wydawnictwo Uniwersytetu Ekonomicznego we Wrocławiu
Tematy:
high-frequency data
hierarchical models
incomplete time series
Opis:
The paper presents a procedure of application of regular hierarchical models in forecasting missing data in high-frequency time series with cyclical fluctuations. Annual, weekly and daily cycles of seasonal fluctuation have additive character. Separately regular hierarchical models have been built for even length cycles.Theoretical considerations are illustrated with an empirical example.
Źródło:
Econometrics. Ekonometria. Advances in Applied Data Analytics; 2014, 4(46); 72-84
1507-3866
Pojawia się w:
Econometrics. Ekonometria. Advances in Applied Data Analytics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental Study of Identifying Emission Sources of Acoustic Signals on the Cylinder Body of a Two-Stroke Marine Diesel Engine
Autorzy:
Dong, Xuan Thin
Nguyen, Manh Hung
Powiązania:
https://bibliotekanauki.pl/articles/1953513.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
acoustic emission
two-stroke marine diesel engine
experimental method
low-to-high frequency ranges
medium-to-high frequency ranges
vibration
Opis:
In this paper, an experimental method was utilized to investigate acoustic emission (AE) characteristics and to identify emission sources of the nonlinear AE signal on the cylinder body of a large low-speed two-stroke marine diesel engine in real-working conditions on the sea in misfiring and normal firing modes. Measurements focused on the AE signal acquired in a transverse direction in low-frequency (20-80 kHz), medium-frequency (100-400 kHz) and high-frequency (400-900 kHz) ranges. The collected signals were analyzed on the crank angle and crank angle-frequency domains. The results showed that all potential sources of the nonlinear AE signal could be mapped in the low-frequency range. However, only the AE signal caused by the combustion process at around the top dead center could be well-observed in the medium-to-high-frequency range. The findings also revealed that in normal firing conditions, the AE energy radiated by friction in the down-stroke period was smaller than in the up-stroke process due to gas-sealing forces. Moreover, the AE energy in the misfiring condition was higher than in the normal firing state. These outcomes considerably contributed understandings to characteristics of friction and wear around the mid-stroke area of the cylinder on a two-stroke marine diesel engine.
Źródło:
Archives of Acoustics; 2021, 46, 1; 105-119
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
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:
Trading volume and volatility patterns across selected Central European stock markets from microstructural perspective
Autorzy:
Gurgul, H.
Syrek, R.
Powiązania:
https://bibliotekanauki.pl/articles/1201257.pdf
Data publikacji:
2017
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
high frequency data
flexible Fourier form regression
intraday patterns
Opis:
In this paper, the intraday patterns of trading volumes and volatilities as well as autocorrelations are investigated using high-frequency data. The analysis is performed for companies listed in the main German, Austrian, and Polish indices with the aid of Flexible Fourier Form regression. We have found some similarities to prior investigations in light of stylized facts about intraday patterns. We noted the differences in intraday patterns and autocorrelations across markets, which depend on the maturity level of the market. The most-regular patterns are observed for DAX companies. Additionally, using day-of-the-week dummies, we discover some peaks that can be associated with macroeconomic announcements in Germany and the US. This leads to conclusions that the day of the week and announcements should be taken into account in modeling volatilities (returns) and volumes from high-frequency data.
Źródło:
Managerial Economics; 2017, 18, 1; 87-101
1898-1143
Pojawia się w:
Managerial Economics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of acoustical and optical zooplankton measurements using an acoustic scattering model: A case study from the Arctic frontal zone
Autorzy:
Szczucka, Joanna
Błachowiak-Samołyk, Katarzyna
Trudnowska, Emilia
Hoppe, Łukasz
Powiązania:
https://bibliotekanauki.pl/articles/2046858.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Arctic
Svalbard
zooplankton
high−frequency echosounding
sound scattering model
Źródło:
Polish Polar Research; 2016, 37, 1; 67-88
0138-0338
2081-8262
Pojawia się w:
Polish Polar Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Palatalization as a Non-Uniform Process Affecting Grammatical Words: A Comparison of Data from Dialectally Identified and Unidentified Late Middle English Texts
Autorzy:
Kocel, Agnieszka
Powiązania:
https://bibliotekanauki.pl/articles/888650.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Warszawski. Wydawnictwa Uniwersytetu Warszawskiego
Tematy:
palatalization
high frequency lemmas
Middle English
dialects
lexical diffusion
Opis:
The process of palatalization has exerted much influence on the forms of four highfrequency lemmas, EACH, MUCH, SUCH, WHICH, revealing significant heterogeneity in terms of palatalized and non-palatalized variants being used in the close vicinity of each other both in the Northern and Southern dialects as well as in the texts of unknown origin. Such unpredictability of the process, accounted for by the operation of lexical diffusion, raises questions concerning the manner of how palatalization, being one of the major phonological changes, affected the lexis and phonological system of Middle English, proving to be much less consistent than expected.
Źródło:
Anglica. An International Journal of English Studies; 2013, 22/2; 5-25
0860-5734
Pojawia się w:
Anglica. An International Journal of English Studies
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dehydration of no flotation size coal's slimes on the deck of high-frequency screen with multislopes area's working surface
Оbezvozhivanie ugolnogo shlama na site vysokochastotnogo vibracionnogo grokhota s raznonaklonnymi uchastkami rabochejj poverkhnosti
Autorzy:
Eremejev, I.
Polulyakh, A.
Polulyakh, D.
Grachyov, O.
Powiązania:
https://bibliotekanauki.pl/articles/791890.pdf
Data publikacji:
2014
Wydawca:
Komisja Motoryzacji i Energetyki Rolnictwa
Tematy:
coal
dehydration
physical model
working surface
high-frequency screen
Źródło:
Teka Komisji Motoryzacji i Energetyki Rolnictwa; 2014, 14, 2
1641-7739
Pojawia się w:
Teka Komisji Motoryzacji i Energetyki Rolnictwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High power microwave for knocking out programmable suicide drones
Autorzy:
Chaari, Mohamed Zied
Powiązania:
https://bibliotekanauki.pl/articles/1311126.pdf
Data publikacji:
2021
Wydawca:
Akademia Sztuki Wojennej
Tematy:
high power microwave
conical horn antenna
errant drone
kill drone
high frequency
Opis:
The primary research objective is to reduce the dangers of rogue drones in our lives and the consequences of extremist groups, drug dealers, and organised criminals using them. The growing number of incidents involving modified drones proves the weakness of existing technology in stopping and neutralising errant drones such as the hand-held gun jammer, trained eagle, R.F. jammer, and others. This technology is not very likely to able to knock out a rogue drone and is incapable of stopping programmable drones. This article aims to examine the directed energy of HPM (high power microwaves) in using the electromagnetic field strength energy to damage the drone’s structure or burn its PCB board electronics. It goes on to analyse electronic attack using microwave power with high frequency to immediately switch off drones. The effectiveness of high microwave power for disrupting drones at different distances and in different weather conditions is evaluated. A study of the conical horn antenna of the magnetron coupling system, which has an operating frequency of 2.45 GHz, is also included.
Źródło:
Security and Defence Quarterly; 2021, 34, 2; 68-84
2300-8741
2544-994X
Pojawia się w:
Security and Defence Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 100

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