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Wyszukujesz frazę "loss model" wg kryterium: Temat


Tytuł:
Characterization of Propagation Models in Wireless Communications for 4G Network
Autorzy:
Al-Aamri, Nawal
Nadir, Zia
Al-Lawati, Hassan
Suwailam, Mohammed Bait
Powiązania:
https://bibliotekanauki.pl/articles/2055256.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
path loss model
prediction
4G
RMSE
Opis:
Estimating the pathloss and signal strength of the transmitted signal at specific distances is one of the main objectives of network designers. This paper aims to provide generalized pathloss models appropriate for urban areas in Muscat the capital city of the Sultanate of Oman environment. The research includes studying different models of pathloss for the 4G cellular network at Muttrah Business District (MBD) at Muscat. Different models (Free Space model, Okumura Hata, Extended Sakagami, Cost231 Hata, ECC-33 Hata – Okumura extended, Ericsson, Egli, and SUI) are used with 800MHz. The results of the prediction models are compared with real measured data by calculating RMSE. The generalized models are created by modified original models to get accepted RMSE values. Different cells at MBD are tested by modified models. The RMSE values are then calculated for verification purposes. To validate the modified pathloss models of 4G, they are also applied at different cells in a different city in the capital. It has approximately the same environment as MBD. The modified pathloss models provided accepted predictions in new locations.
Źródło:
International Journal of Electronics and Telecommunications; 2022, 68, 1; 137--143
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Call-level Analysis of a Two-Link Multirate Loss Model based on a Convolution Algorithm
Autorzy:
Sagkriotis, S. G.
Pantelis, S. K.
Moscholios, I. D.
Vassilakis, V. G.
Powiązania:
https://bibliotekanauki.pl/articles/309118.pdf
Data publikacji:
2018
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
call blocking
convolution
loss model
offoading
product form
Opis:
We consider a two-link system that accommodates Poisson arriving calls from different service-classes and propose a multirate teletraffic loss model for its analysis. Each link has two thresholds, which refer to the number of in-service calls in the link. The lowest threshold, named support threshold, defines up to which point the link can support calls offloaded from the other link. The highest threshold, named offloading threshold, defines the point where the link starts offloading calls to the other link. The adopted bandwidth sharing policy is the complete sharing policy, in which a call can be accepted in a link if there exist enough available bandwidth units. The model does not have a product form solution for the steady state probabilities. However, we propose approximate formulas, based on a convolution algorithm, for the calculation of call blocking probabilities. The accuracy of the formulas is verified through simulation and found to be quite satisfactory.
Źródło:
Journal of Telecommunications and Information Technology; 2018, 1; 3-10
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The off-design performance prediction of axial compressor based on a 2D approach
Autorzy:
Zhu, X. C.
Hu, J. F.
Ou-Yang, H.
Tian, J.
Qiang, X. Q.
Du, Z. H.
Powiązania:
https://bibliotekanauki.pl/articles/281612.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
two-dimensional
compressor
streamline curvature
deviation
loss model
Opis:
The two-dimensional compressor flow simulation approach has always been a very valuable tool in compressor preliminary design studies, as well as performance predictions. In this context, a general development of the streamline curvature (SLC) method is elucidated firstly. Then a numerical method based on SLC is developed to simulate the internal flow of the compressor according to the development analysis and conclusion. Two certain transonic axial compressors are calculated by this 2D method. The speed lines and span-wise aerodynamic parameters are compared with the experiment data in order to demonstrate the method presented in this paper.
Źródło:
Journal of Theoretical and Applied Mechanics; 2013, 51, 3; 523-531
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance metrics in OFDM wireless networks supporting quasi-random traffic
Autorzy:
Panagoulias, P.
Moscholios, I.
Sarigiannidis, P.
Piechowiak, M.
Logothetis, M.
Powiązania:
https://bibliotekanauki.pl/articles/200360.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
congestion
quasi random
OFDM
reservation
loss model
recursive
Opis:
We consider the downlink of an orthogonal frequency division multiplexing (OFDM) based cell that accommodates calls from different service-classes with different resource requirements. We assume that calls arrive in the cell according to a quasi-random process, i.e., calls are generated by a finite number of sources. To calculate the most important performance metrics in this OFDM-based cell, i.e., congestion probabilities and resource utilization, we model it as a multirate loss model, show that the steady-state probabilities have a product form solution (PFS) and propose recursive formulas which reduce the complexity of the calculations. In addition, we study the bandwidth reservation (BR) policy which can be used in order to reserve subcarriers in favor of calls with high subcarrier requirements. The existence of the BR policy destroys the PFS of the steady-state probabilities. However, it is shown that there are recursive formulas for the determination of the various performance measures. The accuracy of the proposed formulas is verified via simulation and found to be satisfactory.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2020, 68, 2; 215-223
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Review of loss models for high pressure turbines
Autorzy:
Back da Trindade, D.
Bugała, P.
Simone, D.
Powiązania:
https://bibliotekanauki.pl/articles/244992.pdf
Data publikacji:
2018
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
turbomachinery
gas turbines
high-pressure turbine
HPT
loss model
Opis:
This article presents a literature review about the physical analysis of the loss models, which are used in offdesign procedure for high-pressure turbines. A high-pressure turbine is designed to have maximum performance at design point. However, engines are operating in different conditions, and the comprehension of off-design conditions is very important. The loss mechanisms are very complex and predictions considering empirical methods are a good approach to have preliminary results. Based on these results, different researches have proposed theories about the loss mechanisms, and over the time, these models have been modified to describe better the phenomena involved between blades and flow. Once the physical mechanisms behind the loss models are known, it is possible to compare them and understand the reason why the results given for some methods present a higher agreement to experimental or numerical data. In this framework, 2D numerical simulations of the flow around the blades of an axial high pressure turbine with different off design conditions have been realized, by using ANSYS FLUENT® code, to show the losses described by some of these models. Using these simulations a loss model has been selected and implemented in Matlab® to compare its results with the experimental data found in literature.
Źródło:
Journal of KONES; 2018, 25, 2; 38-44
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transient approach for iron loss separation of non-grain-oriented electrical steels considering the impact of cut edge effect
Autorzy:
Mülder, Christoph
Elfgen, Silas
Hameyer, Kay
Powiązania:
https://bibliotekanauki.pl/articles/140851.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
cut edge effect
hysteresis losses
iron losses
transient loss model
Opis:
The purpose of this paper is to focus on the loss separation of non-grain-oriented electrical steels used for speed-variable rotating electrical machines. The impact of laser-cutting, used in prototype manufacturing and of flux density harmonics, occurring locally in the lamination, on the loss distribution is studied in detail. Iron losses occurring under operation can physically be separated in different loss components. In this paper, a frequency-based loss model with parameters identified for single-sheet tester specimens, cut in strips of different widths, is therefore used. Moreover, a time-domain approach considers loss distributions occurring from higher harmonics. Hysteresis losses having high sensitivity to cut edge effects are calculated by the well-known Jiles-Atherton model adapting the frequency-based loss parameters. The model is validated by free-curve measurements at a single-sheet tester. It has been shown that the studied elliptical hysteresis model becomes inaccurate particularly for specimens with small strip widths with similar dimensions as teeth of electrical machine laminations. The incorrect mapping of losses occurring from minor hysteresis loops due to higher harmonics is concluded. The results showconsequently that both, the impact of a cut edge effect and local distributions of flux density harmonics need to be considered in terms of accurate iron loss prediction of electrical machine design.
Źródło:
Archives of Electrical Engineering; 2019, 68, 2; 237-244
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Statistical Calibration Method of Propagation Prediction Model Based on Measurement Results
Autorzy:
Kelner, Jan M.
Kryk, Michał
Łopatka, Jerzy
Gajewski, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/226022.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
calibration of propagation model
empirical measurements
path loss model
propagation
parabolic equation method
radio environment maps
Opis:
Radio environment maps (REMs) are beginning to be an integral part of modern mobile radiocommunication systems and networks, especially for ad-hoc, cognitive, and dynamic spectrum access networks. The REMs will use emerging military systems of tactical communications. The REM is a kind of database used at the stage of planning and management of the radio resources and networks, which considers the geographical features of an area, environmental propagation properties, as well as the parameters of radio network elements and available services. At the REM, for spatial management of network nodes, various methods of propagation modeling for determining the attenuation and capacity of wireless links and radio ranges are used. One method of propagation prediction is based on a numerical solution of the wave equation in a parabolic form, which allows considering, i.a., atmospheric refraction, terrain shape, and soil electrical parameters. However, the determination of a current altitudinal profile of atmospheric refraction may be a problem. If the propagation-prediction model uses a fixed refraction profile, then the calibration of this model based on empirical measurements is required. We propose a methodology for calibrating the analyzed model based on an example empirical research scenario. The paper presents descriptions of the propagation model, test-bed and scenario used in measurements, and obtained signal attenuation results, which are used for the initial calibration of the model.
Źródło:
International Journal of Electronics and Telecommunications; 2020, 66, 1; 11-16
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Call Blocking Probabilities of Multirate Elastic and Adaptive Traffic under the Threshold and Bandwidth Reservation Policies
Autorzy:
Moscholios, I. D.
Logothetis, M. D.
Boucouvalas, A. C.
Vassilakis, V. G.
Powiązania:
https://bibliotekanauki.pl/articles/308771.pdf
Data publikacji:
2016
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
adaptive trac policy
Call Blocking Probabilities
Multirate Loss Model
threshold and bandwidth reservation policy
Opis:
This paper proposes multirate teletraffic loss models of a link that accommodates different service-classes of elastic and adaptive calls. Calls follow a Poisson process, can tolerate bandwidth compression and have an exponentially distributed service time. When bandwidth compression occurs, the service time of new and in-service elastic calls increases. Adaptive calls do not alter their service time. All calls compete for the available link bandwidth under the combination of the Threshold (TH) and the Bandwidth Reservation (BR) policies. The TH policy can provide different QoS among service-classes by limiting the number of calls of a service-class up to a predefined threshold, which can be different for each service-class. The BR policy reserves part of the available link bandwidth to benefit calls of high bandwidth requirements. The analysis of the proposed models is based on approximate but recursive formulas, whereby authors determine call blocking probabilities and link utilization. The accuracy of the proposed formulas is verified through simulation and found to be very satisfactory.
Źródło:
Journal of Telecommunications and Information Technology; 2016, 1; 44-52
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tłumienia łącza kierunkowego w zakresie fal milimetrowych na bazie modyfikacji modelu empirycznego
Directional link attenuation in millimeter-wave range based on empirical model modification
Autorzy:
Pawlak, Dawid
Kelner, Jan M.
Powiązania:
https://bibliotekanauki.pl/articles/24065010.pdf
Data publikacji:
2022
Wydawca:
Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
Tematy:
łączność bezprzewodowa
propagacja fal radiowych
modele tłumienia
wielo-eliptyczny model propagacyjny
anteny kierunkowe
kierunkowe łącze radiowe
fale milimetrowe
systemy 5G
badania symulacyjne
wireless communication
radio wave propagation
path loss model
multi-elliptical propagation model
directional antennas
directional radio link
millimeter waves
5G systems
simulation studies
Opis:
Systemy telefonii komórkowej piątej i następnych generacji będą wykorzystywały nie tylko zakresy częstotliwości poniżej 6 GHz, lecz także pasma w zakresie fal milimetrowych oraz terahercowych. Z praktycznego punktu widzenia podejście to wymaga stosowania anten kierunkowych lub systemów z formowaniem wiązki. w celu zapewnienia większej efektywności energetycznej łącza bezprzewodowego istotne jest, aby wiązki radiowe po stronie nadawczej i odbiorczej były współosiowe. Modele tłumienia są powszechnie wykorzystywane przy projektowaniu systemów i sieci łączności radiowej. należy jednak podkreślić, że w literaturze nie ma dostępnych odpowiednich metod modelowania tłumienia dla przypadków braku współosiowości wiązek antenowych. w artykule zaproponowano sposób modyfikacji modelu tłumienia bazujący na wieloeliptycznym modelu propagacyjnym. w tym celu opracowano specjalne oprogramowanie w środowisku MATLAB, które posłużyło do przeprowadzenia badań symulacyjnych. w dalszej części przedstawiono przykładowe wyniki adaptacji empirycznych modeli tłumienia w zakresie fal milimetrowych, które otrzymano, wykorzystując opracowany program.
The upcoming fifth and next generation mobile phone systems will use not only the frequency bands of sub-6 GHz but also the millimeter-wave and terahertz bands. From a practical viewpoint, this approach requires the use of directional antennas or beamforming systems. To ensure greater energy efficiency of the wireless link, the radio beams on the transmitting and receiving sides should be aligned ones. Path loss models are commonly used for designing the radio communication systems and networks. However, in the literature, there are no adequate methods of attenuation modelling available for the cases of misalignment of antenna beams. in this paper, a method of modifying the path loss model, based on a multi-elliptical propagation model, is proposed. For this purpose, dedicated software was developed in the MATLAB environment, which was used to conduct simulation tests. In the remainder of the paper, exemplary results of the adaptation of empirical path loss models in the range of millimeter-waves are presented, which were obtained using the developed program.
Źródło:
Biuletyn Wojskowej Akademii Technicznej; 2022, 71, 3; 69--92
1234-5865
Pojawia się w:
Biuletyn Wojskowej Akademii Technicznej
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Adaptive and precise peak detection algorithm for fibre Bragg grating using generative adversarial network
Autorzy:
Kumar, Sunil
Sengupta, Somnath
Powiązania:
https://bibliotekanauki.pl/articles/2174853.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
Tematy:
Fibre Bragg grating
generative model
discriminative model
loss function
Opis:
An adaptive and precise peak wavelength detection algorithm for fibre Bragg grating using generative adversarial network is proposed. The algorithm consists of generative model and discriminative model. The generative model generates a synthetic signal and is sampled for training using a deep neural network. The discriminative model predicts the real fibre Bragg grating signal by the calculation of the loss functions. The maxima of loss function of the discriminative signal and the minima of loss function of the generative signal are matched and the desired peak wavelength of fibre Bragg grating is determined. The proposed algorithm is verified theoretically and experimentally for a single fibre Bragg grating peak. The accuracy has been obtained as ±0.2 pm. The proposed algorithm is adaptive in the sense that any random fibre Bragg grating peak can be identified within a short wavelength range.
Źródło:
Opto-Electronics Review; 2022, 30, 4; art. no. e144227
1230-3402
Pojawia się w:
Opto-Electronics Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Optimized Propagation Model based on Measurement Data for Indoor Environments
Autorzy:
Morocho-Yaguana, M.
Ludeňa-González, P.
Sandoval, F.
Poma-Vélez, B.
Erreyes-Dota, A.
Powiązania:
https://bibliotekanauki.pl/articles/308451.pdf
Data publikacji:
2018
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
indoor
ITU model
log-distance model
loss measurement
one-slope model
path loss
propagation measurements
propagation models
radio propagation
Opis:
Propagation is an essential factor ensuring good coverage of wireless communications systems. Propagation models are used to predict losses in the path between transmitter and receiver nodes. They are usually defined for general conditions. Therefore, their results are not always adapted to the behavior of real signals in a specific environment. The main goal of this work is to propose a new model adjusting the loss coefficients based on empirical data, which can be applied in an indoor university campus environment. The Oneslope, Log-distance and ITU models are described to provide a mathematical base. An extensive measurement campaign is performed based on a strict methodology considering different cases in typical indoor scenarios. New loss parameter values are defined to adjust the mathematical model to the behavior of real signals in the campus environment. The experimental results show that the model proposed offers an attenuation average error of 2.5% with respect to the losses measured. In addition, comparison of the proposed model with existing solutions shows that it decreases the average error significantly for all scenarios under evaluation.
Źródło:
Journal of Telecommunications and Information Technology; 2018, 2; 69-75
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the classification of observations in the switching regression
O klasyfikacji obserwacji w regresji przełącznikowej
Autorzy:
Pruska, Krystyna
Powiązania:
https://bibliotekanauki.pl/articles/904610.pdf
Data publikacji:
1997
Wydawca:
Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego
Tematy:
switching regression model
discrimination analysis
loss function
Opis:
The paper discusses the method of determining the sample division indicator for the switching regression model in case of two states generating values of the explained variable, which ensures the least risk of making a mistake, understood as the expected value of relevant loss function. This paper is an attempt to take advantage of the discrimination analysis elements in the switching regression analysis.
Źródło:
Acta Universitatis Lodziensis. Folia Oeconomica; 1997, 141
0208-6018
2353-7663
Pojawia się w:
Acta Universitatis Lodziensis. Folia Oeconomica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal dynamics of a building
Autorzy:
Matysko, R.
Dyczkowska, M.
Powiązania:
https://bibliotekanauki.pl/articles/175263.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
transient model
thermal loss
thermal inertia
building
Opis:
The work presents the thermal dynamics of the building. The mathematical model covers the issues of heat exchange and temperature control in the room due to changing environmental conditions. The presented work describes the operation of the control system due to thermal losses and thermal inertia of the building. Mathematical model introduces a new method of thermal loss analysis in the conditions of variable thermal dynamics of the building.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2018, 141; 31-40
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessing the Threat of Erosion to Nature-Based Interventions for Stormwater Management and Flood Control in the Greater Accra Metropolitan Area, Ghana
Autorzy:
Asiedu, J. K.
Powiązania:
https://bibliotekanauki.pl/articles/124600.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
RUSLE model
soil loss
clogging
infiltration
stormwater management
Opis:
Perennial flooding has become a major feature in urban areas in developing economies generating research interest towards finding alternative approaches to stormwater management which could complement the existing systems and help address the challenge of flooding. One of such alternative approaches is nature-based stormwater management and flood control, the implementation of which could be affected by soil erosion. This paper, as part of a wider research, was developed to determine the extent of the threat of soil erosion to stormwater management in an urban area on the example of Greater Accra Metropolitan Area, Accra Ghana as the focus of the research. Landsat 8 images (2014) were used in the research to prepare the Landcover maps. Daily rainfall data from 6 raingauge stations from 1972 to 2014 were utilized to prepare the rainfall erosivity factor maps, whereas DEM was used to prepare the slope and slope length (SL) factor maps. The land cover map with an overall accuracy of 73.6 and Kappa 0.7122 was combined with literature sources to prepare the vegetative cover factor map, and conservation practice factor map. A soil series map, prepared and updated with literature sources and data from the Harmonized World Soil Database on physical parameters, was used to calculate the soil erodibility factor (K factor) for each soil series. These were integrated into RUSLE model as 30 m raster maps to generate a soil loss map at tons/ha/yr. The results produced rainfall erosivity index values based on the modified Fournier index ranging between 0.058 and 23.197 which is classified as low. Low soil erodibility factor (K) ranging between 2.9×10–5 and 8.5×10–2 t ha/MJ mm indicated low susceptibility to erosion, SL factor value showing areas of low to almost flat relief with a few isolated areas of moderate slope length were generated. A soil loss of 69,5918 tons/ha/yr classified the soils as having high potential soil loss. The results showed a very low soil loss threat of 0–5.1853 tons/Ha/yr for more than 90% of the study area. Targeted intervention for source areas with high potential soil loss will contain any threat of erosion and sediment yield to the implementation of an infiltration-based stormwater management and flood control system.
Źródło:
Journal of Ecological Engineering; 2018, 19, 1; 1-13
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Friction in the Continuously Variable Transmission. Test bench and initial test results
Autorzy:
Goszczak, Jarosław
Powiązania:
https://bibliotekanauki.pl/articles/1178412.pdf
Data publikacji:
2017
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
CVT
belt tension
forces
friction
model
power loss
Opis:
The article concerns friction problems in the Continuously Variable Transmission (CVT) with a pushbelt or a chain. A small test bench is prepared with the aim to expand knowledge about friction phenomena which occur in the CVT between steel belt elements and pulleys. The literature explains this problem not sufficiently. After short theoretical introduction, the paper contains a description of the test bench and its correlation to the real CVT gearbox as it is in a car. Afterwards the initial test results are presented and completed with some remarks. At the end, summary and conclusion are defined.
Źródło:
World Scientific News; 2017, 73; 43-50
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł

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