The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
Ehud Heyman - One of the best experts on this subject based on the ideXlab platform.
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A Beam Summation Representation for 3-D Radiation From a Line Source Distribution
IEEE Transactions on Antennas and Propagation, 2008Co-Authors: M. Katsav, Ehud HeymanAbstract:We introduce a Gaussian beams summation (GBS) scheme for radiation from a Source Distribution along a line in a 3-D configuration. The expansion is based on a discrete phase-space decomposition of the Source Distribution along the Source axis, thus describing the field as a sum of Gaussian beams (GBs) emerging from a discrete set of points along the axis, at a discrete set of directions in a polar coordinate system. Applications to GBS representation of fields diffracted by edges is 3-D configurations are discussed.
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time dependent plane wave spectrum representations for radiation from volume Source Distributions
Journal of Mathematical Physics, 1996Co-Authors: Ehud HeymanAbstract:A new time‐domain spectral theory for radiation from a time‐dependent Source Distribution, is presented. The full spectral representation is based on a Radon transform of the Source Distribution in the four‐dimensional space‐time domain and consists of time‐dependent plane waves that propagate in all space directions and with all (spectral) propagation speeds vκ. This operation, termed the slant stack transform, involves projection of the time‐dependent Source Distribution along planes normal to the spectral propagation direction and stacking them with a progressive delay corresponding to the spectral propagation speed vκ along this direction. Outside the Source domain, this three‐fold representation may be contracted into a two‐fold representation consisting of time‐dependent plane waves that satisfy the spectral constraint vκ=c with c being the medium velocity. In the two‐fold representation, however, the complete spectral representation involves both propagating time‐dependent plane waves and evanescen...
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Time‐dependent multipoles and their application for radiation from volume Source Distributions
Journal of Mathematical Physics, 1996Co-Authors: Ehud Heyman, Anthony J. DevaneyAbstract:The radiation from a pulsed Source Distribution is expressed directly in the time‐domain using a sum of time‐dependent spherical (multipole) wave functions. Two alternative expressions for the time‐dependent multipole moments (the excitation pulses) are derived. It is shown how they are related to the time‐dependent plane‐wave spectrum of the Source (obtained via a Radon transform of the Source Distribution in the four space‐time coordinates). Furthermore, the time‐dependent multipole moments, and thereby the total time‐dependent field outside the Source region, are completely determined by the time‐dependent radiation pattern. The series convergence is addressed by showing that the high order multipole moments tend to the quasistatic extension of the static multipole moments. This also puts an upper limit on the spatial resolution that can be achieved by a Source Distribution with specified size and pulse length.
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Time‐dependent plane‐wave spectrum representations for radiation from volume Source Distributions
Journal of Mathematical Physics, 1996Co-Authors: Ehud HeymanAbstract:A new time‐domain spectral theory for radiation from a time‐dependent Source Distribution, is presented. The full spectral representation is based on a Radon transform of the Source Distribution in the four‐dimensional space‐time domain and consists of time‐dependent plane waves that propagate in all space directions and with all (spectral) propagation speeds vκ. This operation, termed the slant stack transform, involves projection of the time‐dependent Source Distribution along planes normal to the spectral propagation direction and stacking them with a progressive delay corresponding to the spectral propagation speed vκ along this direction. Outside the Source domain, this three‐fold representation may be contracted into a two‐fold representation consisting of time‐dependent plane waves that satisfy the spectral constraint vκ=c with c being the medium velocity. In the two‐fold representation, however, the complete spectral representation involves both propagating time‐dependent plane waves and evanescen...
Yogesh Singh - One of the best experts on this subject based on the ideXlab platform.
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Source Distribution models for blind Source separation
Neurocomputing, 2004Co-Authors: Chandra Shekhar Rai, Yogesh SinghAbstract:Abstract Various methods have been proposed to separate mixtures of sub- and super-Gaussian signals. Effectiveness of a blind Source separation algorithm depends upon the Source Distribution model used for deriving the weight update rule. Different hypothesized Source Distribution models are used for representing sub- and super-Gaussian Sources. In this paper, a more justifiable approach is considered for characterizing the Source Distributions. For a given density model of super- or sub-Gaussian Sources, a symmetric probability density function around a Gaussian Distribution is used for representing sub- or super-Gaussian Sources. Hence, corresponding to a long tail sharper density function for super-Gaussian signals, a short-tail flatter density function for sub-Gaussian signals is obtained. Optimization of the objective function leads to two different nonlinear functions. This approach leads to appropriate handling of both kinds of signals simultaneously. Simulations results with audio signals have been presented.
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Letters Source Distribution models for blind Source separation
2004Co-Authors: Chandra Shekhar Rai, Yogesh SinghAbstract:Various methods have been proposed to separate mixtures of sub- and super-Gaussian signals. E,ectiveness of a blind Source separation algorithm depends upon the Source Distribution model used for deriving the weight update rule. Di,erent hypothesized Source Distribution models are used for representing sub- and super-Gaussian Sources. In this paper, a more justi2able approach is considered for characterizing the Source Distributions. For a given density model of super- or sub-Gaussian Sources, a symmetric probability density function around a Gaussian Distribution is used for representing sub- or super-Gaussian Sources. Hence, corresponding to a long tail sharper density function for super-Gaussian signals, a short-tail 5atter density function for sub-Gaussian signals is obtained. Optimization of the objective function leads to two different nonlinear functions. This approach leads to appropriate handling of both kinds of signals simultaneously. Simulations results with audio signals have been presented. c
Paul G. Maropoulos - One of the best experts on this subject based on the ideXlab platform.
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effects of welding speed energy input and heat Source Distribution on temperature variations in butt joint welding
Journal of Materials Processing Technology, 2005Co-Authors: Ducatel Gery, H. Long, Paul G. MaropoulosAbstract:In this paper, a moving heat Source model based on Goldak's double-ellipsoid heat flux Distribution is presented. A C++ programme was developed in order to implement heat inputs into finite element thermal simulation of the plate butt joint welding. The transient temperature Distributions and temperature variations of the welded plates during welding were predicted and the fusion zone and heat affected zone were obtained. Effects of the heat Source Distribution, energy input and welding speed on temperature changes were further investigated.
J L Gardner - One of the best experts on this subject based on the ideXlab platform.
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Uncertainties in Source Distribution temperature and correlated colour temperature
Metrologia, 2006Co-Authors: J L GardnerAbstract:Uncertainties in the Distribution temperature (DT) and correlated colour temperature are estimated for common Sources and typical measurement uncertainties of a spectral transfer from a reference lamp. Uncertainty sensitivity coefficients for both parameters in terms of measured values of spectral irradiance are derived using a generalized matrix inverse. The uncertainty values are compared with differences in the Source temperature parameters. DT is calculated using the CIE definition; shifts in DT due to the alternative of a direct fit of Planck's Distribution, and to including weights in the process, are compared with the estimated uncertainties.
Bogdán Yamaji - One of the best experts on this subject based on the ideXlab platform.
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Analysis of heat Source Distribution in internal circulating surface heat transfer molten salt reactor
Progress in Nuclear Energy, 2016Co-Authors: Péter German, Sándor Fehér, Szabolcs Czifrus, Bogdán YamajiAbstract:Abstract The Molten Salt Reactor (MSR) is one of the Generation IV nuclear reactor concepts that were selected by the Generation IV International Forum in 2000. The concept is based on liquid fuel instead of solid fuel assemblies. Besides the advantages, there are several aspects of operation that can hinder the realization of this reactor concept. In this paper, the authors investigate the neutronics behaviour of a new sub-concept that offers solutions for many of the technical problems. The analysis was performed using the particle transport code MCNPX 2.7. The paper focuses on the short-term and steady state heat Source Distribution in the fuel salt and in the graphite moderator. Accordingly, neither burn-up effects nor reactivity transients are considered. The sensitivity of the effective multiplication factor on different geometrical and material parameters was studied. The results obtained indicate that the main region of heat deposition is in the internal and external channels of the graphite moderator. Only a few percent of the total heat power is released in the graphite moderator, where the gamma and neutron related heat deposition is on the same scale. The results also prove that the heat Source Distribution does not change drastically upon the actuation of the control rods.
