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Wyświetlanie 1-15 z 39
Tytuł:
Pilot Based MMSE Channel Estimation for Spatial Modulated OFDM Systems
Autorzy:
Soman, Anetha Mary
Nakkeeran, R.
Shinu, Mathew John
Powiązania:
https://bibliotekanauki.pl/articles/2055222.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
MIMO
multicarrier modulation
spatial modulation
channel estimation
channel model
interpolation
Opis:
Due to the multifold growth in demands of multimedia services and mobile data, the request for increased channel capacity in mobile and wireless communication has been quickly increasing. Developing a wireless system with more spectral efficiency under varying channel condition is a key challenge to provide more bit rates with limited spectrum. Multiple Input Multiple Output(MIMO) system with Orthogonal Frequency Division Multiplexing (OFDM) gives higher gain by using the direct and the reflected signals, thus facilitating the transmission at high data rate. An integration of Spatial Modulation (SM) with OFDM (SM OFDM) is a newly evolved transmission technique and has been suggested as a replacement for MIMO -OFDM transmission. In practical scenarios, channel estimation is significant for detecting transmitted data coherently. This paper proposes pilot based, Minimum Mean Square Error (MMSE) channel estimation for the SM OFDM communication system. We have focused on analyzing Symbol Error Rate (SER) and Mean Square error (MSE) under Rayleigh channel employing International Telecommunication Union (ITU) specified Vehicular model of Pilot based MMSE channel estimator using windowed Discrete Fourier Transform (DFT) and MMSE weighting function. Simulation output shows that proposed estimator’s SER performance lies close to that of the MMSE optimal estimator in minimizing aliasing error and suppressing channel noise by using frequency domain data windowing and time domain weighting function. Usage of the Hanning window eliminates error floor and has a compact side lobe level compared to Hamming window and Rectangular window. Hanning window has a larger MSE at low Signal to Noise Ratio (SNR) values and decreases with high SNR values. It is concluded that data windowing technique can minimize the side lobe level and accordingly minimize channel estimation error when interpolation is done. MMSE weighting suppresses channel noise and improves estimation performance. Since Inverse Discrete Fourier Transform(IDFT)/DFT transforms can be implemented with fast algorithms Inverse Fast Fourier Transform( IFFT)/Fast Fourier Transform(FFT) computational complexity can be remarkably reduced.
Źródło:
International Journal of Electronics and Telecommunications; 2021, 67, 4; 685--691
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
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:
Performance Evaluation of 60-GHz-WPAN System Distributed Over Multi-Mode Fiber
Autorzy:
El Yahyaoui, M.
El Moussati, A.
Haddadi, K.
Powiązania:
https://bibliotekanauki.pl/articles/226089.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
60GHz
MMF
OCS
Ro
wireless channel model TSV
Opis:
The manuscript deals with the assessment of Radio over Fiber (RoF) system including pure electrical baseband, pure radio frequency band centered around 60 GHz, and hybrid radiooptical system at the same RF band using a global simulation. In this work we focus on RoF solution to improve the low coverage of the 60 GHz channel caused by high free-space attenuation. A realistic co-simulation of the Wireless Personal Area Network (WPAN) IEEE802.15.3c-RoF was performed in a residential environment for Line-Of-Sight (LOS) and Non-Line-Of-Sight (NLOS). In this work, we demonstrated a 60 GHz radio on Multi-Mode Fiber (MMF) using Optical Carrier Suppression (OCS) modulation. The BER (Bit Error Ratio) performance of this system is measured by varying the following parameters: optical launched power, fiber length, modulation format, Channel coding and Signal to Noise Ratio. We show that the RoF at 60 GHz can reach a minimum of 300 m of MMF without optical amplifiers followed by a 5 m wireless transmission with BER less than 10⁻³ in the LOS and NLOS environments.
Źródło:
International Journal of Electronics and Telecommunications; 2017, 63, 4; 381-387
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A wavelet-based model for foveal detection of spatial contrast with frequency dependent aperture effect
Autorzy:
Hooshangnejad, H.
Gharibzadeh, S.
Towhidkhah, F.
Powiązania:
https://bibliotekanauki.pl/articles/101948.pdf
Data publikacji:
2016
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
visual system modeling
spatial vision
contrast detection
wavelet filter bank
multi-channel model
ModelFest
frequency dependent aperture effect
Opis:
The main purpose of this study is to build a Computational model based on ModelFest dataset which is able to predict contrast sensitivity while it benefits from simplicity, efficiency and accuracy, which makes it suitable for hardware implementation, practical uses, online tests, real-time processes, an improved Standard Observer and retina prostheses. It encompasses several components, and in particular, frequency dependent aperture effect (FDAE) which is used for the first time on this dataset, which made the model more accurate and closer to reality. Shortcomings of previous models and the necessity of existence of FDAE for more accuracy led us to develop a new model based on Wavelet Transform that gives us the advantage of speed and the capability to process each frequency channels output. Considering our goal for building an efficient model, we introduce a new formula for modeling contrast sensitivity function, which generates fewer errors and better timing performance. Eventually, this new model leads to having as yet lowest RMS error and solving the problem of long execution time of prior models and reduces them by almost a factor of twenty.
Źródło:
Advances in Science and Technology. Research Journal; 2016, 10, 30; 51-68
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance analysis of MPPM FSO transmission over Gamma–Chi-square strong atmospheric turbulence
Autorzy:
Todorovic, Jelena
Spalevic, Petar
Panic, Stefan
Abdullah, Majid Hamid
Pantelic, Ivan
Powiązania:
https://bibliotekanauki.pl/articles/2202766.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
FSO
free space optics
ABER
average bit error rate
MPPM
multi-pulse pulse-position
novel Gamma-Chi-square distribution
channel model
strong atmospheric turbulence
Opis:
In this paper, performance analysis of free space optical (FSO) system operating in conditions of strong atmospheric turbulence over Gamma–Chi-square turbulence model, has been carried out. We have observed reception over multi-pulse pulse-position (MPPM) modulation format for the case of strong atmospheric turbulence conditions modeled with Gamma–Chi-square turbulence model and have compared it with turbulence modeling distributions such are: Gamma–Gamma distribution, K-distribution, negative exponential distribution, log–normal distribution. First, we have provided closed-form analytical expressions for average bit error rate (ABER) at the reception for each observed case and then based on them, we have obtained numerical and Monte Carlo simulation results in order to observe turbulence level impact on system performance.
Źródło:
Optica Applicata; 2023, 53, 1; 111--126
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Selection of an appropriate distribution channel for high-value stone
Autorzy:
Mikušová, Nikoleta
Tomková, Eva
Hrdlý, David
Průša, Petr
Kampf, Rudolf
Powiązania:
https://bibliotekanauki.pl/articles/103204.pdf
Data publikacji:
2018
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
distribution
channel
model
Opis:
Selection of distribution channel type is an important decision of every manufacturing company and also for production engineering. Appropriate choice of distribution channel can save considerable costs while maintaining a high level of customer service. Determination of an appropriate strategy for the management of enterprise distribution channel. In this article, the selection of the type of distribution channel is proposed using ANP method to determine the strength of influence of input factors on the target set of potential options. Submitted model is very clear, understandable and according to the proposed methodology easy to implement, while also providing clear and understandable results during the selection of the type of distribution channel. The proposed model is primarily targeting for distribution of high-value stone which needs to decide which distribution strategy should be chosen or if to switch to another distribution strategy more suitable for the company needs.
Źródło:
Advances in Science and Technology. Research Journal; 2018, 12, 2; 298-306
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Peculiarities of use of speech acoustic environment while embedding into it of hidden message codes
Autorzy:
Korostil, Y.
Afanasyeva, O.
Powiązania:
https://bibliotekanauki.pl/articles/360624.pdf
Data publikacji:
2013
Wydawca:
Akademia Morska w Szczecinie. Wydawnictwo AMSz
Tematy:
communication channel
model
message
hidden message
acoustic message
Opis:
The problems of embedding of message codes into Acoustic environment of speech are researched. The peculiarities of speech perception by human hearing are analyzed. As an example of acoustic Messager environment and codes of hidden messages embedded into it is reviewed a channel of mobile Communications in the part of transformations which are implemented with acoustic signals. Approach to build a model of process of transmission of speech via non-linear channel basing on imagination about speech signals spectrum is developed. The proposals on methods of use of such models for analysis and interpretation of distortions of signals made by transformations, implemented in example channel are presented.
Źródło:
Zeszyty Naukowe Akademii Morskiej w Szczecinie; 2013, 33 (105); 46-50
1733-8670
2392-0378
Pojawia się w:
Zeszyty Naukowe Akademii Morskiej w Szczecinie
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lagrangian Model for a Single Saltating Grain in the Near-Wall Region of an Open-Channel Flow
Autorzy:
Czernuszenko, W.
Powiązania:
https://bibliotekanauki.pl/articles/241181.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
Lagrangian model
open-channel flow
particle-particle interaction
Opis:
A mathematical model for the continuous saltation of a particle near the granular bed in an open-channel flow is developed in detail. The model is based on the Lagrangian equations governing particle motion, and it takes into account the following forces: drag, lift, gravitation, virtual mass and the force responsible for particle-particle interactions. A model of particle-particle collisions is developed and used to determine the mean impulsive force acting upon a particle flowing and rebounding from the channel bed. The model can simulate the continuous saltation trajectories of a single particle in the near-bed region of turbulent flows, in which particle motion is controlled by collisions. The model has been calibrated and verified with available published data in a rather wide range of grain sizes from 0.53 mm to 15 mm. All parameters, such as lift, drag, restitution, friction coefficients and roughness height, have been set on the basis of a reanalysis of these published data.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2013, 60, 1-4; 31-50
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A turbulence model for 3-d flows with anisotropic structure of turbulence
Autorzy:
Czernuszenko, W.
Rylov, A.
Powiązania:
https://bibliotekanauki.pl/articles/241364.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
3D flow
mathematical model
numerical simulation
open channel flow
turbulence model
Opis:
A new turbulence model for flows in open channels with compound cross-sections is presented. The structure of turbulence in these channels can be anisotropic. This structure is described by the turbulent stress tensor that is presented here as the sum of two tensors, namely, normal and shear stress tensors. The normal and shear turbulent stresses are expressed by the turbulence intensities and the mixing length tensor (MLT), respectively. The turbulence intensities can be learned from measurements or another suitable approaches. One such approach that allows calculating the main component of the normal stresses is presented in the paper. The components of MLT are defined based on a new concept of generic mixing length (GML). The generic mixing length is assumed to depend on both distances; from the nearest wall and from the water surface. To demonstrate how the new model works the basic hydrodynamic equations (parabolic approximation of Reynolds equations) together with the turbulence model are solved. The well-known Patankar and Spalding (1972) algorithm was used when solving these equations. A series of numerical simulations were performed for different components of MLT and different channel geometries.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2005, 52, 4; 303-320
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An analytical model for water profile calculations in free surface flows through rockfills
Autorzy:
Soualmia, A.
Jouini, M.
Masbernat, L.
Dartus, D.
Powiązania:
https://bibliotekanauki.pl/articles/281999.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
analytical model
experimental channel
rockfill
simulations
Stephenson’s formula
Opis:
In this study, an analytical model to resolve the water profiles equation of free surface flows through riprap has been developed. This model is based on Stephenson’s relation to determine the head loss for different flow states in order to see its ability to reproduce the water profiles. This analytical model has been applied to experimental series realized in a rectangular channel built at the National Agronomic Institute of Tunisia (INAT) in collaboration with engineering consultants of the firm MECATER and in partnership with the INP Toulouse. MECATER is interested in these flows within the framework of a project with the nickel company SLN of ERAMET group in New Caledonia, concerning the protection of mining sterols against water flows at high mountains.
Źródło:
Journal of Theoretical and Applied Mechanics; 2015, 53, 1; 209-215
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical modeling of hydrodynamic and sediment siltation due to typhoon in estuary channel regulation
Autorzy:
Zhao, H.
Zhang, Q.
Xie, M.
Powiązania:
https://bibliotekanauki.pl/articles/259087.pdf
Data publikacji:
2015
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
Oujiang Estuary
numerical model
channel regulation
sediment siltation
typhoon
Opis:
Oujiang Estuary is a complex tidal estuary with many channels and shoals in the East China Sea, which was affected by typhoon frequently. The navigation channel of Wenzhou Port is located in the north branch of Oujiang Estuary, which happened serious sediment siltation in many times due to typhoon impact. The regulation is considered to decrease siltaion of the channel and protect shoals as well. According to the site survey data, the mathematic model is established and validated, which simulates the hydrodynamic, sediment transport and channel siltation due to typhoon in Oujiang Estuary. The channel regulation scenario is studied by the model simulation after analysis of the silation character. It indicates that the high concentration sediment from shoals north of channel is main sediment source caused siltation in the channel, which can be prevented into the channel by the regulation scenario and decrease siltation efficiently.
Źródło:
Polish Maritime Research; 2015, S 1; 61-66
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Modelling of Fish Passage with Turning Pools
Autorzy:
Maniecki, Ł.
Powiązania:
https://bibliotekanauki.pl/articles/241474.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
open channel flow
fishway
turbulence
numerical model
turning pool
Opis:
An assessment of operating conditions in a baffled fish passage with pool dimensions of 2:2 3:0 m, and 180 horizontally turning pools, was carried out using numerical computations and a site survey of water flow velocity distribution. Velocity was measured with a PMS electromagnetic flowmeter and a hydrometric current meter in representative cross-sections of the fish passage in the pool centres and in the baffle barrier cross-section area. Numerical computations were also performed for two alternative baffle locations in the fishway. One reflected the actual conditions, and the other was an alternative arrangement designed to improve hydraulic conditions for fish migration. The numerical model used the Large Eddy Simulation (LES) method, which makes it possible to detect large vortexes. The study pays close attention to the velocity field analysis as well as the distribution and sizes of vortexes in the turning pool of the culvert. The results of numerical computations and the site survey show high consistency, and the proposed baffle placement modification significantly improves flow conditions, especially in the entry section of the passage.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2018, 65, 1; 41-66
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling and performance analysis of dual-channel switched reluctance motor
Autorzy:
Bogusz, P.
Korkosz, M.
Prokop, J.
Powiązania:
https://bibliotekanauki.pl/articles/950653.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Dual Channel Switched Reluctance Motors
DCSRM
mathematical model
SRM
Opis:
The paper is a presentation of an analysis concerning performance of a 12/8 dual-channel switched reluctance motor (DCSRM). Formulas constituting a base for a non-linear mathematical model of DCSRM are presented. Simulation and laboratory tests were carried out for the motor operating in the dual-channel and single-channel mode. The results of the field theory-based calculations are presented in the form of fluxes in individual phases expressed as functions of currents and a rotor position angle. The results of the computer simulations are shown as the static characteristics of fluxes and the torque as well as voltage, current, and torque waveforms. The results of the laboratory tests are also presented.
Źródło:
Archives of Electrical Engineering; 2015, 64, 1; 89-105
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Inundation controlling practice in urban area: Case study in residential area of Malang, Indonesia
Autorzy:
Harisuseno, Donny
Bisri, Mohammad
Haji, Tunggul S.
Powiązania:
https://bibliotekanauki.pl/articles/946892.pdf
Data publikacji:
2020
Wydawca:
Instytut Technologiczno-Przyrodniczy
Tematy:
channel normalization
inundation
runoff
SIMODAS model
storage well
urban area
Opis:
Flood inundation processes in urban areas are primarily affected by artificial factors such as drainage facilities, local alterations of topography and land uses. The objective of this study is to examine the capability of hydrological model SI-MODAS to estimate runoff and investigating the utilization of storage well in controlling runoff in a residential area. The result of the estimated runoff from the hydrological model was compared with the existing capacity of the drainage channel to identify which channel experienced the problem of inundation. The location of inundation was used to determine the location and number of storage well. The results showed that SIMODAS model could be applied in runoff analyses with 8.09% of relative error compared with runoff depth from field measurement. The existing capacity of the channel could not accommodate runoff Q10yr where the inundation discharge was approximately 0.24 m3·s–1 (at outlet point 1) and 0.12 m3·s–1 (at outlet point 2). The inundation problem was overcome by using a combination system between channel normalization (reduce 35% of total inundation discharge) and storage well system (reduce 65% of total inundation discharge). The storage well was designed at 20 locations (at outlet point 1) and 16 locations (at outlet point 2) which each well had a discharge of 0.0058 m3·s–1. The storage well combined with channel normalization could be used as an alternative way to solve inundation problems in a residential area considering the constraint of land space limitation in the urban area.
Źródło:
Journal of Water and Land Development; 2020, 46; 112-120
1429-7426
2083-4535
Pojawia się w:
Journal of Water and Land Development
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Analysis of Turbulent Flow over a Backward-facing Step in an Open Channel
Autorzy:
Saleem, Bala Kawa M.
Mustafa, Andam
Kareem, Dalshad Ahmed
Yuce, Mehmet Ishak
Szydłowski, Micchał
Al-Ansari, Nadhir
Powiązania:
https://bibliotekanauki.pl/articles/31340451.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
open channel
backward-facing step
reattachment length
expansion ratio
Kɛ- model
Kω- model
Opis:
Computational examinations of the flow field in an open channel having a single Backward- -Facing Step (BFS) with a constant water depth of 1.5 m were performed. The effects of the expansion ratio, and the flow velocity along the reattachment length, were investigated by employing two different expansion ratios of 1.5 and 2, and eight various flow velocities of 0.5, 1, 2, 3, 4, 5, 7.5 and 10 m/sec in the Computational Fluid Dynamic (CFD) simulations. Commercially available CFD software, ANSYS FLUENT, was used for calculations. The simulation outcomes were verified using experimental results. Moreover, analyses were performed by using two equation turbulence closure models, K-ε family (standard, RNG and realizable), and K-ω family (Wilcox’s and SST K-ω). The analyses have revealed that the reattachment length increases with an increase in the expansion ratio, the flow velocity and the Reynolds number. The results obtained for two expansion rates and eight different flow velocities have shown insignificant differences between one turbulence closure model and the others. Furthermore, it was observed that both velocity and expansion ratios have an effect on the reattachment zone size.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2023, 70, 1; 49-69
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 39

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