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Tytuł:
The Acoustics of the Catacombs
Autorzy:
Iannace, G.
Trematerra, A.
Qandil, A.
Powiązania:
https://bibliotekanauki.pl/articles/950219.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
catacombs
acoustic measurements
reverberation time
impulse response
Opis:
The catacombs are underground places. This paper reports the results of acoustic measurements carried out inside the catacombs of “San Gennaro” (Naples) and in those one of “San Callisto” (Rome). Originally the catacombs were also used to perform sacred functions, although we don’t know the type of these functions i.e. if they were spoken, sung or performed as psalms. This paper presents acoustic measurements carried out in catacombs using the impulse response method, and by the analysis of the monaural acoustic parameters, (T30, EDT, C80, D50 and STI), the authors intend to understand the type of religious ceremony performed in the catacombs. If the catacombs had been reverberant places, they could not have been used for prayers because the echoes would have created difficulties in concentration and meditation for the devotees due to the poor speech comprehension.
Źródło:
Archives of Acoustics; 2014, 39, 4; 583-590
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The relationship between information and communication technologies and female labour force participation in Turkey
Autorzy:
Tüzemen, Samet
Barış-Tüzemen, Özge
Çelik, Ali Kemal
Powiązania:
https://bibliotekanauki.pl/articles/1891419.pdf
Data publikacji:
2021-12-17
Wydawca:
Uniwersytet Ekonomiczny w Poznaniu
Tematy:
women employment
ICTs
ARDL
impulse response function
Opis:
The elimination of all forms of discrimination between the sexes is not only a fundamental human right but it also is very important to support all other areas of development, particularly sustainable development. The aim of this study is to empirically investigate the role of information and communication technologies on employment inequality in Turkey. Therefore, the relationship between ICT applications and female labour force participation is investigated with the auto regressive distributed lag (ARDL) model and impulse response analysis. The results showed that there is no association between information and communication technologies and the female labour force participation rate for the period 1988–2018. These findings may suggest that developing countries also need to have a certain level of development in other areas such as democracy, fundamental rights and freedoms and the rule of law to benefit from the opportunities that information and communication technologies offer to empower the whole society including women.
Źródło:
Economics and Business Review; 2021, 7, 4; 121-145
2392-1641
Pojawia się w:
Economics and Business Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characteristics of the indoor propagation channel in 1.9 GHz band
Autorzy:
Kurek, K.
Janusek, D.
Kosiło, T.
Modelski, J.
Powiązania:
https://bibliotekanauki.pl/articles/309156.pdf
Data publikacji:
2001
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
indoor propagation channel
channel impulse response
time dispersion
Opis:
This paper presents results of propagation measurement carried out in the frequency range 1.8-2.0 GHz inside a building, using network analyser. Wideband properties of the channel, described through mean delay and delay spread, and a narrowband local statistics of the received power have been presented. For each transmitter and receiver antennas location two propagation cases have been considered, line of sight (LOS) and obstructed line of sight (NLOS) - the direct path component was attenuated by radio absorbing mat near the receiver.
Źródło:
Journal of Telecommunications and Information Technology; 2001, 4; 56-59
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Adaptive identification of time-varying impulse response of underwater acoustic communication channel
Autorzy:
Kochańska, I.
Powiązania:
https://bibliotekanauki.pl/articles/332081.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
transmission properties
time-varying impulse response
Kalman filter
Opis:
The transmission properties of underwater acoustic communication channel can change dynamically due to the movement of acoustic system transmitter and receiver or underwater objects reflecting transmitted signal. The time-varying impulse response measurement and estimation are necessary to match the physical layer of data transmission to instantaneous channel propagation conditions. Using the correlative measurement method, impulse response estimate can be obtained no more than the duration of the measurement sequence. The paper proposes a joint correlative measurement and adaptive filtration approach, applying the Kalman filter algorithm to increase the time-domain resolution of the time-varying impulse response estimation.
Źródło:
Hydroacoustics; 2015, 18; 87-94
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An analysis of the relationships among NASDAQ Baltic stock exchanges: VAR approach
Autorzy:
Zięba, Łukasz
Powiązania:
https://bibliotekanauki.pl/articles/16729733.pdf
Data publikacji:
2021
Wydawca:
Instytut Naukowo-Wydawniczy "SPATIUM"
Tematy:
stock exchanges
VAR model;
impulse response analysis
variance decomposition
Opis:
The author examines the relationships among three stock exchanges of selected Baltic countries: Latvia, Estonia, and Lithuania. The respective stock exchange indexes are used as variables, OMXR for Latvia, OMXT for Estonia, and OMXV for Lithuania. The regression equations are estimated with the use of Vector Autoregressive (VAR) model. The author employs 80 observations for the sample period from2002 Q1 to 2021 Q4. After determining the optimal lag order, the impulse response function is calculated. The variance decomposition is carried out subsequently. A causality among the stock exchanges in question is determined.
Źródło:
Central European Review of Economics & Finance; 2021, 34, 3; 51-65
2082-8500
2083-4314
Pojawia się w:
Central European Review of Economics & Finance
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Approach to Design Broadband Air Backed Piezoelectric Sensor
Autorzy:
Ali, M. G. S.
Elsayed, N. Z.
Eid, E. A.
Powiązania:
https://bibliotekanauki.pl/articles/176360.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
piezoelectric
equivalent circuits
impulse response
frequency response
matching layers
z-transform
Opis:
In this work, an approach to the design of broadband thickness-mode piezoelectric transducer is presented. In this approach, simulation of discrete time model of the impulse response of matched and backed piezoelectric transducer is used to design high sensitivity, broad bandwidth, and short-duration impulse response transducers. The effect of matching the performance of transmitting and receiving air backed PZT-5A transducer working into water load is studied. The optimum acoustical characteristics of the quarter wavelength matching layers are determined by a compromise between sensitivity and pulse duration. The thickness of bonding layers is smaller than that of the quarter wavelength matching layers so that they do not change the resonance peak significantly. Our calculations show that the −3 dB air backed transducer bandwidth can be improved considerably by using quarter wavelength matching layers. The computer model developed in this work to predict the behavior of multilayer structures driven by a transient waveform agrees well with measured results. Furthermore, the advantage of this this model over other approaches is that the time signal for optimum set of matching layers can be predicted rapidly.
Źródło:
Archives of Acoustics; 2015, 40, 1; 3-10
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Novel Method for Determining Optimum Dimension Ratios for Small Rectangular Rooms
Autorzy:
Meissner, M.
Powiązania:
https://bibliotekanauki.pl/articles/177897.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
room acoustics
small room
optimum dimension ratios
room impulse response
frequency room response
Opis:
A new method for determining optimum dimension ratios for small rectangular rooms has been presented. In a theoretical model, an exact description of the room impulse response was used. Based on the impulse response, a frequency response of a room was calculated to find changes in the sound pressure level over the frequency range 20-200 Hz. These changes depend on the source and receiver positions, thus, a new metric equivalent to an average frequency response was introduced to quantify the overall sound pressure variation within the room for a selected source position. A numerical procedure was employed to seek a minimum value of the deviation of the sound pressure level response from a smooth fitted response determined by the quadratic polynomial regression. The most smooth frequency responses were obtained when the source was located at one of the eight corners of a room. Thus, to find the best possible dimension ratios, in the numerical procedure the optimal source position was assumed. Calculation results have shown that optimum dimension ratios depend on the room volume and the sound damping inside a room, and for small and medium volumes these ratios are roughly 1 : 1.48 : 2.12, 1 : 1.4 : 1.89 and 1 : 1.2 : 1.45. When the room volume was suitably large, the ratio 1 : 1.2 : 1.44 was found to be the best one.
Źródło:
Archives of Acoustics; 2018, 43, 2; 217-225
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Identification of financial and macroeconomic shocks in a VAR model of the Polish economy. A stability analysis
Autorzy:
Ulrichs, Magdalena
Powiązania:
https://bibliotekanauki.pl/articles/943099.pdf
Data publikacji:
2018-03-30
Wydawca:
Uniwersytet Ekonomiczny w Poznaniu
Tematy:
VAR models
impulse response functions
Markov‑Switching VAR models
structural changes
Opis:
Dynamic macroeconomic models (both VAR and DSGE) currently play a very significant role in macroeconomic modelling. But these types of models rarely take into account the impact of financial markets on the behaviour of economies, they are rather more focused on the monetary transmission mechanism. The financial crisis of 2007-2008 highlighted the impact of the financial market on the macroeconomy. In this context macroprudential policy and financial stability analysis has gained a stronger meaning. The main aim of the paper is to estimate a model that simultaneously explains the dynamics of macroeconomic and financial variables and to assess whether the identified relationships are stable over time. Therefore, based on the estimated empirical structural vector autoregression model explaining the interactions between the real economy, the financial system and monetary policy in Poland, financial and macroeconomic shocks were identified. It was shown that the impulse reaction functions changed after the financial crisis. On the basis of Markov‑Switching vector autoregression model probabilities of transitions between states of the economy and the regime-dependent impulse reaction functions were estimated.
Źródło:
Economics and Business Review; 2018, 4(18), 1; 29-43
2392-1641
Pojawia się w:
Economics and Business Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The impact of enterprise markups on changes in the CPI in Poland
Autorzy:
Kosztowniak, Aneta
Powiązania:
https://bibliotekanauki.pl/articles/45432799.pdf
Data publikacji:
2024-09-11
Wydawca:
Szkoła Główna Handlowa w Warszawie. Kolegium Zarządzania i Finansów
Tematy:
inflation expectations
CPI
markups
NFC
VAR
impulse response functions
variance decomposition
Opis:
The aim of the study is to present the impact of enterprise markups by sections on changes in the CPI in Poland in the years 2008–2023. The VAR model was developed to reveal the interdependencies between changes in markups in nine major sections of non-financial corporations and changes in the CPI. The results of the model, the impulse response function and the variance decomposition confirmed the differentiated impact of markups on inflation changes. To the greatest extent, changes in the CPI, as much as 30%, were explained by the markups of enterprises in real estate services (L), and mining and quarrying (B) sections. The least pro-inflationary contribution to the CPI explanation was shown by markups from information and communication (J), water supply, sewage and waste management, reclamation (E), trade and repair of motor vehicles (G) and the generation and supply of electricity, gas, steam, and hot water D (less than 1%). The degree of explanation of the CPI by markups projected in the variance decomposition increased in the short term (to 26% in the 1st year), stabilizing at a higher level (35% in the years 3–5) in the medium and long term.
Źródło:
Journal of Management and Financial Sciences; 2024, 51; 9-35
1899-8968
Pojawia się w:
Journal of Management and Financial Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling the Geometry of an Underwater Channel for Acoustic Communication
Autorzy:
Naman, Hala A.
Abdelkareem, A. E.
Powiązania:
https://bibliotekanauki.pl/articles/2174453.pdf
Data publikacji:
2022
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
channel impulse response
geometry channel model
multipath propagation
underwater acoustic communication
Opis:
The achievement of efficient data transmissions via underwater acoustic channels, while dealing with large data packets and real-time data fed by underwater sensors, requires a high data rate. However, diffraction, refraction, and reflection phenomena, as well as phase and amplitude variations, are common problems experienced in underwater acoustic (UWA) channels. These factors make it difficult to achieve high-speed and long-range underwater acoustic communications. Due to multipath interference caused by surface and ocean floor reflections, the process of modeling acoustic channels under the water’s surface is of key importance. This work proposes a simple geometry-based channel model for underwater communication. The impact that varying numbers of reflections, low water depth values, and distances between the transmitter and the receiver exert on channel impulse response and transmission loss is examined. The high degree of similarity between numerical simulations and actual results demonstrates that the proposed model is suitable for describing shallow underwater acoustic communication environments.
Źródło:
Journal of Telecommunications and Information Technology; 2022, 4; 3--12
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transfer function–based impulse response analysis for a class of hyperbolic systems of balance laws
Autorzy:
Bartecki, K.
Powiązania:
https://bibliotekanauki.pl/articles/206531.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
hyperbolic system
balance law
transfer function
impulse response
Laplace transform
heat exchanger
Opis:
Results of the impulse response analysis for a class of dynamical systems, described by two weakly coupled linear partial differential equations of hyperbolic type, defined on a one-dimensional spatial domain are presented. For the case of two boundary inputs of the Dirichlet type, the analytical expressions for the impulse response functions are derived based on the inverse Laplace trans form of the 2×2 transfer function matrix of the system. The influence of the boundary inputs configuration on the impulse response functions is demonstrated. The considerations are illustrated with a practical example of a thin-walled double-pipe heat exchanger operating in parallel- and countercurrent-flow modes, which correspond to the analyzed boundary conditions.
Źródło:
Control and Cybernetics; 2015, 44, 3; 327-355
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Limitations of WSSUS modeling of stationary underwater acoustic communication channel
Autorzy:
Kochańska, I.
Nissen, I.
Powiązania:
https://bibliotekanauki.pl/articles/331730.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
underwater communications
impulse response
stationary time
stationary bandwidth
adaptive communications
WSSUS modeling
Opis:
Performances of underwater acoustic communication (UAC) systems are strongly related to specific propagation conditions of the underwater channel. Due to their large variability, there is a need for adaptive matching of the UAC systems signaling to the transmission properties of the channel. This requires a knowledge of instantaneous channel characteristics, in terms of the specific parameters of stochastic models. The wide-sense stationary uncorrelated scattering (WSSUS) assumption simplifies the estimation of terrestrial wireless channel transmission properties. Although UAC channels are hardly ever WSSUS, the rationale of such a stochastic modeling is that over a short period of time, and for a limited frequency range, this assumption is reasonably satisfied. The limits of application of the local-sense stationary uncorrelated scattering (LSSUS) model are determined by the stationary time and frequency. This paper presents the results of LSSUS model analysis for UAC channel measurements gathered by the former Research Department for Underwater Acoustics and Marine Geophysics (FWG), now part of the WTD71, during the SIMO experiment in the Bornholm Basin of the Baltic Sea.
Źródło:
Hydroacoustics; 2016, 19; 229-238
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The method of frequency determination of impulse response components based on cross-correlation vs. fast Fourier transform
Metoda ustalania częstotliwości składowych odpowiedzi impulsowej bazująca na funkcji korelacji wzajemnej względem szybkiej transformaty Fouriera
Autorzy:
Kotowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/328416.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Tematy:
impulse response
spectrum
determination
peak frequency
odpowiedź impulsowa
widmo
wyznaczanie
częstotliwość piku
Opis:
The paper presents results of impulse response spectral analysis that has been obtained using a method based on cross-correlation. The impulse response spectrum is achieved by correlating the impulse response and reference single-harmonic signals and using Hilbert transform to obtain an envelope of cross-correlation. Then, surface area under the envelope is calculating and its plot in frequency domain is making. The spectrum obtained this way has its advantage over the fast Fourier transform (FFT) that its spectral resolution does not depend on length of impulse response. At the same time, the spectral resolution can be much greater than spectral resolution resultant from FFT. Obtained results show that presented method gives possibilities to determine frequencies of impulse response components more accurate in comparison to FFT particularly for short-time impulse responses.
Praca przedstawia wyniki analizy widmowej odpowiedzi impulsowej przy użyciu metody opartej o funkcję korelacji wzajemnej. Widmo odpowiedzi impulsowej uzyskiwane jest poprzez korelowanie odpowiedzi impulsowej z harmonicznym sygnałem odniesienia i zastosowaniu transformaty Hilberta w celu uzyskania obwiedni funkcji korelacji wzajemnej. Wówczas wyznaczane jest pole powierzchni pod obwiednią i jej wykres w funkcji częstotliwości. Tak uzyskane widmo posiada tą zaletę ponad szybką transformatę Fouriera (FFT), że jego rozdzielczość widmowa nie zależy od długości odpowiedzi impulsowej. Równocześnie, rozdzielczość widmowa potrafi być znacznie wyższa niż rozdzielczość widmowa wynikająca ze stosowania FFT. Uzyskane wyniki pokazują, że przedstawiona metoda stwarza możliwości aby ustalać częstotliwości składowych odpowiedzi impulsowej dokładniej w porównaniu do FFT.
Źródło:
Diagnostyka; 2016, 17, 1; 59-64
1641-6414
2449-5220
Pojawia się w:
Diagnostyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prediction of Reverberant Properties of Enclosures via a Method Employing a Modal Representation of the Room Impulse Response
Autorzy:
Meissner, M.
Powiązania:
https://bibliotekanauki.pl/articles/177946.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
room acoustics
indoor reverberation
room impulse response
modal expansion method
decay times
Opis:
A theoretical method has been presented to describe sound decay in enclosures and simulate the room impulse response (RIR) employed for prediction of the indoor reverberation characteristics. The method was based on a solution of wave equation with the form of a series whose time-decaying components represent responses of acoustic modes to an impulse sound source. For small sound absorption on room walls this solution was found by means of the method of variation of parameters. A decay function was computed via the time-reverse integration of the squared RIR. Computer simulations carried out for a rectangular enclosure have proved that the RIR function reproduces the structure of a sound field in the initial stage of sound decay sufficiently well. They have also shown that band-limitedness of the RIR has evident influence on the shape of the decay function and predicted decay times.
Źródło:
Archives of Acoustics; 2016, 41, 1; 27-41
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic characteristics measurements of a force transducer against small and short-duration impact forces
Autorzy:
Djamal, M.
Watanabe, K.
Irisa, K.
Prayogi, I. A.
Takita, A.
Yamaguchi, T.
Fujii, Y.
Powiązania:
https://bibliotekanauki.pl/articles/221311.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
dynamic force
impulse response
force transducer
force sensor
inertial force
optical interferometer
Opis:
A method for evaluating the dynamic characteristics of force transducers against small and short-duration impact forces is developed. In this method, a small mass collides with a force transducer and the impact force is measured with high accuracy as the inertial force of the mass. A pneumatic linear bearing is used to achieve linear motion with sufficiently small friction acting on the mass, which is the moving part of the bearing. Small and short-duration impact forces with a maximum impact force of approximately 5 N and minimum half-value width of approximately 1 ms are applied to a force transducer and the impulse responses are evaluated.
Źródło:
Metrology and Measurement Systems; 2014, 21, 1; 59-66
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
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