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02332 A solution of the neutron diffusion equation for a hemisphere containing a uniform source
16 Fuel science and technology (fundamental science, analysis, instrumentation) 05•02332 A solution of the neutron diffusion equation for a hemisphere containing a uniform source
05/02337 Approximate local mathematical descriptions of turbulent Bunsen flames in the flamelet regime
Williams, M. M. R. and Eaton, M. Annals of Nuclear Energy, 2004, 31, (18), 2169 2184. A n analytic solution of the diffusion equation for a h e m i s p h e r e of fissile or non-fissile m a t e r i a l is p r e s e n t e d which contains a spatially uniform n e u t r o n source. N u m e r i c a l results are given for the flux distribution for one-speed fast neutrons in 235U and also for a nonfissile e l e m e n t of similar scattering properties. These results are used to check the accuracy of the finite e l e m e n t code E V E N T . The p r o c e d u r e is also developed for multi-group calculations. The p r o c e d u r e required w h e n the h e m i s p h e r e contains a source and is also irradiated by an external current of neutrons is outlined in an appendix.
Williams, F. A. and Furukawa, J. Combustion andFlame, 2004, 138, (1 2), 108 113. Simplified conservation equations are p r e s e n t e d for describing properties of t u r b u l e n t premixed Bunsen b u r n e r flames m e a s u r e d at local points in the flame brush, in the flamelet regime. These equations enable velocity changes across flamelets to be addressed and facilitate m a t h e m a t i c a l analyses of local gas motions before and after flamelet passage. Different simplified models are pursued in efforts to d e t e r m i n e w h e t h e r buoyancy or hydrodynamic adjustments are more i m p o r t a n t in affecting burnt-gas velocity fluctuations. D e d u c t i o n s drawn from analysis of these equations are shown to be consistent with experimental results. It is suggested that further, more detailed analyses may d e m o n s t r a t e the d o m i n a n c e of hydrodynamic adjustments in the b u r n t gas.
05/02333 A study of the variation of synchronous machine parameters due to saturation: a numerical approach Escarela-Perez, R. et al. Electric Power Systems Research, 2004, 72, (1), 1 11. This p a p e r shows the variation of the f u n d a m e n t a l p a r a m e t e r s of synchronous machine two-axis equivalent circuits due to magnetic saturation. The different magnetic states of the machine are obtained using finite-element magnetostatic solutions. This way the permeability patterns of the saturable parts of the machine can be stored and used in a specially designed finite-element program that outputs the standstill frequency response (SSFR) of the machine. A hybrid genetic algorithm, capable of finding global extrema is then applied to obtain the p a r a m e t e r s of two equivalent circuit structures for the d-axis. The process is repeated for each magnetic state, so that the variation of p a r a m e t e r s can be seen. The magnetic states of the machine are validated by c o m p a r i n g the measured open-circuit characteristic with the one calculated from the finite-element model. In order to validate the d-axis equivalent circuit p a r a m e t e r s identified, they have been adopted in the simulation of a synchronous machine short-circuit and the results obtained have been c o m p a r e d to those calculated by a transient finite-element program.
05/02334 A two-dimensional computational model of a PEMFC with liquid water transport Siegel, N. P. et al. Journal of Power Sources, 2004, 128, (2), 173 184. A comprehensive, steady-state, c o m p u t a t i o n a l model of a proton exchange m e m b r a n e fuel cell ( P E M F C ) derived from first principles is presented. The model is two-dimensional and includes the t r a n s p o r t of liquid water within the porous electrodes as well as the t r a n s p o r t of gaseous species, protons, energy, and water dissolved in the ion conducting polymer. E l e c t r o c h e m i c a l kinetics are modelled with standard rate equations a d a p t e d to an a g g l o m e r a t e catalyst layer structure. Some of the physical properties used in constructing the m o d e l are d e t e r m i n e d experimentally for an in-house m e m b r a n e electrode assembly ( M E A ) and are p r e s e n t e d herein. E x p e r i m e n t a l results obtained for the M E A are used to validate the c o m p u t a t i o n a l model. Modelling results are p r e s e n t e d that illustrate the i m p o r t a n c e of the t r a n s p o r t of water within the porous sections of the cell and in the polymer regions of the MEA.
05/02335
Adaptive neural network control of active filters
Tey, L. H. et al. Electric Power Systems Research, 2005, 74, (1), 37 56. This paper presents a new control design of shunt and series active filters for harmonic c o m p e n s a t i o n in a power distribution system. The topology of the active filter is based on a 3-phase pulse width m o d u l a t e d ( P W M ) voltage source inverter (VSI) and a control circuit. The control circuit using two neural network controllers is proposed. One adaptive neural network (NN) controller is designed to estimate the harmonic c o m p o n e n t s of the distorted load current and supply voltage. A n o t h e r neural network controller that uses Levenberg M a r q u a r d t b a c k p r o p a g a t i o n (LMBP) for its training is designed to generate accurate switch control signals for the P W M VSI. The resultant series active filter also has the capability to c o m p e n s a t e for voltage sags in the distorted supply voltage. A power factor correction function is incorporated in the shunt active filter to achieve a power factor that is near to unity. Simulation results show that the active filters with n e u r a l network control can significantly reduce harmonic distortion in the load current and supply voltage and can a d a p t to variations in system operating conditions.
05/02336 An experimental study on linear differential scattering coefficients of the radioactive compounds UO2 (C2H302)2 • 2H20 and Th(NO3)4 • 5H20 at 60 keV I'qelli, O. Annals of Nuclear Energy, 2004, 31, (18), 2157 2168. The linear differential scattering coefficients at 60 k e V have been m e a s u r e d for UO2 (C2H302)2 • 2 H 2 0 (uranyl-acetate) and Th(NO3)4 ¢5fl 5 H 2 0 (thorium-nitrate) radioactive c o m p o u n d s at seven angles ranging from 60 c' to 120 c' at intervals 10 ~'. The obtained results have been c o m p a r e d with relativistic and non-relativistic theoretical values.
340
Fuel and Energy Abstracts
September 2005
05/02338 Computation of practical flow problems with release of latent heat Y a m a m o t o , S. Energy, 2005, 30, (2 4), 197 208. Practical flow problems with condensation due to phase change from water v a p o u r to water liquid are numerically investigated. F u n d a m e n t a l equations solved in this study consist of conservation laws of mixed gas, water vapour, water liquid, and the n u m b e r density of w a t e r droplets, coupled with the m o m e n t u m equations and the energy equation. The classical condensation theory is employed for m o d e l l i n g h o m o g e n e o u s nucleation and non-equilibrium condensation. H e t e r o g e n e o u s nucleation is approximately m o d e l l e d by assuming a constant radius and a constant n u m b e r density of droplets. These equations are solved by a high-order high-resolution finite-difference method. As external flows, condensate transonic flows a r o u n d NACA0012 airfoil in atmospheric flow conditions are calculated, and as internal flows, steady and u n s t e a d y transonic wet-steam flows through a steam turbine cascade channel are also calculated.
05/02339 Genetic based algorithm for active power filter allocation and sizing Keypour, R. et al. Electric Power Systems Research, 2004, 71, (1), 41 49. Active power filters (APF) can be employed for harmonic compensation in power systems. In this p a p e r two algorithms are proposed for o p t i m u m allocation and sizing of APFs. In the first algorithm, the aim is to minimize the voltage harmonic distortion while in the second; the aim is to m e e t the harmonic standard levels by m i n i m u m injection of A P F currents. Both algorithms are solved using genetic algorithm (GA) as the optimization tool. The performance of the proposed approaches are assessed and appreciated by various case studies on an 18-bus test system.
05/02340 Harmonic modeling of linear and nonlinear loads based on Kalman filtering algorithm Soliman, S. A. and A l a m m a r i , R. A. Electric Power Systems Research, 2004, 72, (2), 147 155. Most harmonic non-linear load m o d e l l i n g techniques developed in the last two decades, assume that the load connected to the load bus has a constant admittance, inductive or capacitive, which depends on the m o d e of operation of the load (constant R, L, and C). This is not true, since the loads in most cases are non-linear and they inject harmonics into the system. This paper presents a new application of K a l m a n filtering (KF) to non-linear load modelling in the presence or absence of harmonics. The proposed technique uses directly available samples of the load voltage and current to estimate, and track the variation of load parameters. The proposed algorithm can be used directly on-line for harmonics load modelling, as well as, to track the load power active and reactive. The effects of the critical p a r a m e t e r s on the b e h a v i o u r of the proposed a l g o r i t h m are discussed. Results for different simulated examples and practical examples from field measurements are reported in the paper. The conclusion drawn from these examples is that the a l g o r i t h m is successful in estimating the load parameters.
05/02341 Krylov sub-space methods for K-eigenvalue problem in 3-D neutron transport Gupta, A. and Modak, R. S. Annals of Nuclear Energy, 2004, 31, (18), 2113 2125. The K-eigenvalue problem in nuclear reactor physics is often formulated in the f r a m e w o r k of N e u t r o n T r a n s p o r t Theory. The f u n d a m e n t a l mode solution of this problem is usually o b t a i n e d by the power iteration method. Here, the study is concerned with the use of a Krylov sub-space method, called O R T H O M I N ( 1 ) , to obtain a more efficient solution of the K-eigenvalue problem. A matrix-free a p p r o a c h is proposed which can be easily implemented by using a transport code that can perform fixed source calculations. The power iteration and O R T H O M I N ( 1 ) schemes are compared for two realistic three-dimensional multi-group cases with isotropic scattering: an L W R b e n c h m a r k and a heavy water reactor problem. In both the schemes, within-group
05/02337 Approximate local mathematical descriptions of turbulent Bunsen flames in the flamelet regime
Williams, M. M. R. and Eaton, M. Annals of Nuclear Energy, 2004, 31, (18), 2169 2184. A n analytic solution of the diffusion equation for a h e m i s p h e r e of fissile or non-fissile m a t e r i a l is p r e s e n t e d which contains a spatially uniform n e u t r o n source. N u m e r i c a l results are given for the flux distribution for one-speed fast neutrons in 235U and also for a nonfissile e l e m e n t of similar scattering properties. These results are used to check the accuracy of the finite e l e m e n t code E V E N T . The p r o c e d u r e is also developed for multi-group calculations. The p r o c e d u r e required w h e n the h e m i s p h e r e contains a source and is also irradiated by an external current of neutrons is outlined in an appendix.
Williams, F. A. and Furukawa, J. Combustion andFlame, 2004, 138, (1 2), 108 113. Simplified conservation equations are p r e s e n t e d for describing properties of t u r b u l e n t premixed Bunsen b u r n e r flames m e a s u r e d at local points in the flame brush, in the flamelet regime. These equations enable velocity changes across flamelets to be addressed and facilitate m a t h e m a t i c a l analyses of local gas motions before and after flamelet passage. Different simplified models are pursued in efforts to d e t e r m i n e w h e t h e r buoyancy or hydrodynamic adjustments are more i m p o r t a n t in affecting burnt-gas velocity fluctuations. D e d u c t i o n s drawn from analysis of these equations are shown to be consistent with experimental results. It is suggested that further, more detailed analyses may d e m o n s t r a t e the d o m i n a n c e of hydrodynamic adjustments in the b u r n t gas.
05/02333 A study of the variation of synchronous machine parameters due to saturation: a numerical approach Escarela-Perez, R. et al. Electric Power Systems Research, 2004, 72, (1), 1 11. This p a p e r shows the variation of the f u n d a m e n t a l p a r a m e t e r s of synchronous machine two-axis equivalent circuits due to magnetic saturation. The different magnetic states of the machine are obtained using finite-element magnetostatic solutions. This way the permeability patterns of the saturable parts of the machine can be stored and used in a specially designed finite-element program that outputs the standstill frequency response (SSFR) of the machine. A hybrid genetic algorithm, capable of finding global extrema is then applied to obtain the p a r a m e t e r s of two equivalent circuit structures for the d-axis. The process is repeated for each magnetic state, so that the variation of p a r a m e t e r s can be seen. The magnetic states of the machine are validated by c o m p a r i n g the measured open-circuit characteristic with the one calculated from the finite-element model. In order to validate the d-axis equivalent circuit p a r a m e t e r s identified, they have been adopted in the simulation of a synchronous machine short-circuit and the results obtained have been c o m p a r e d to those calculated by a transient finite-element program.
05/02334 A two-dimensional computational model of a PEMFC with liquid water transport Siegel, N. P. et al. Journal of Power Sources, 2004, 128, (2), 173 184. A comprehensive, steady-state, c o m p u t a t i o n a l model of a proton exchange m e m b r a n e fuel cell ( P E M F C ) derived from first principles is presented. The model is two-dimensional and includes the t r a n s p o r t of liquid water within the porous electrodes as well as the t r a n s p o r t of gaseous species, protons, energy, and water dissolved in the ion conducting polymer. E l e c t r o c h e m i c a l kinetics are modelled with standard rate equations a d a p t e d to an a g g l o m e r a t e catalyst layer structure. Some of the physical properties used in constructing the m o d e l are d e t e r m i n e d experimentally for an in-house m e m b r a n e electrode assembly ( M E A ) and are p r e s e n t e d herein. E x p e r i m e n t a l results obtained for the M E A are used to validate the c o m p u t a t i o n a l model. Modelling results are p r e s e n t e d that illustrate the i m p o r t a n c e of the t r a n s p o r t of water within the porous sections of the cell and in the polymer regions of the MEA.
05/02335
Adaptive neural network control of active filters
Tey, L. H. et al. Electric Power Systems Research, 2005, 74, (1), 37 56. This paper presents a new control design of shunt and series active filters for harmonic c o m p e n s a t i o n in a power distribution system. The topology of the active filter is based on a 3-phase pulse width m o d u l a t e d ( P W M ) voltage source inverter (VSI) and a control circuit. The control circuit using two neural network controllers is proposed. One adaptive neural network (NN) controller is designed to estimate the harmonic c o m p o n e n t s of the distorted load current and supply voltage. A n o t h e r neural network controller that uses Levenberg M a r q u a r d t b a c k p r o p a g a t i o n (LMBP) for its training is designed to generate accurate switch control signals for the P W M VSI. The resultant series active filter also has the capability to c o m p e n s a t e for voltage sags in the distorted supply voltage. A power factor correction function is incorporated in the shunt active filter to achieve a power factor that is near to unity. Simulation results show that the active filters with n e u r a l network control can significantly reduce harmonic distortion in the load current and supply voltage and can a d a p t to variations in system operating conditions.
05/02336 An experimental study on linear differential scattering coefficients of the radioactive compounds UO2 (C2H302)2 • 2H20 and Th(NO3)4 • 5H20 at 60 keV I'qelli, O. Annals of Nuclear Energy, 2004, 31, (18), 2157 2168. The linear differential scattering coefficients at 60 k e V have been m e a s u r e d for UO2 (C2H302)2 • 2 H 2 0 (uranyl-acetate) and Th(NO3)4 ¢5fl 5 H 2 0 (thorium-nitrate) radioactive c o m p o u n d s at seven angles ranging from 60 c' to 120 c' at intervals 10 ~'. The obtained results have been c o m p a r e d with relativistic and non-relativistic theoretical values.
340
Fuel and Energy Abstracts
September 2005
05/02338 Computation of practical flow problems with release of latent heat Y a m a m o t o , S. Energy, 2005, 30, (2 4), 197 208. Practical flow problems with condensation due to phase change from water v a p o u r to water liquid are numerically investigated. F u n d a m e n t a l equations solved in this study consist of conservation laws of mixed gas, water vapour, water liquid, and the n u m b e r density of w a t e r droplets, coupled with the m o m e n t u m equations and the energy equation. The classical condensation theory is employed for m o d e l l i n g h o m o g e n e o u s nucleation and non-equilibrium condensation. H e t e r o g e n e o u s nucleation is approximately m o d e l l e d by assuming a constant radius and a constant n u m b e r density of droplets. These equations are solved by a high-order high-resolution finite-difference method. As external flows, condensate transonic flows a r o u n d NACA0012 airfoil in atmospheric flow conditions are calculated, and as internal flows, steady and u n s t e a d y transonic wet-steam flows through a steam turbine cascade channel are also calculated.
05/02339 Genetic based algorithm for active power filter allocation and sizing Keypour, R. et al. Electric Power Systems Research, 2004, 71, (1), 41 49. Active power filters (APF) can be employed for harmonic compensation in power systems. In this p a p e r two algorithms are proposed for o p t i m u m allocation and sizing of APFs. In the first algorithm, the aim is to minimize the voltage harmonic distortion while in the second; the aim is to m e e t the harmonic standard levels by m i n i m u m injection of A P F currents. Both algorithms are solved using genetic algorithm (GA) as the optimization tool. The performance of the proposed approaches are assessed and appreciated by various case studies on an 18-bus test system.
05/02340 Harmonic modeling of linear and nonlinear loads based on Kalman filtering algorithm Soliman, S. A. and A l a m m a r i , R. A. Electric Power Systems Research, 2004, 72, (2), 147 155. Most harmonic non-linear load m o d e l l i n g techniques developed in the last two decades, assume that the load connected to the load bus has a constant admittance, inductive or capacitive, which depends on the m o d e of operation of the load (constant R, L, and C). This is not true, since the loads in most cases are non-linear and they inject harmonics into the system. This paper presents a new application of K a l m a n filtering (KF) to non-linear load modelling in the presence or absence of harmonics. The proposed technique uses directly available samples of the load voltage and current to estimate, and track the variation of load parameters. The proposed algorithm can be used directly on-line for harmonics load modelling, as well as, to track the load power active and reactive. The effects of the critical p a r a m e t e r s on the b e h a v i o u r of the proposed a l g o r i t h m are discussed. Results for different simulated examples and practical examples from field measurements are reported in the paper. The conclusion drawn from these examples is that the a l g o r i t h m is successful in estimating the load parameters.
05/02341 Krylov sub-space methods for K-eigenvalue problem in 3-D neutron transport Gupta, A. and Modak, R. S. Annals of Nuclear Energy, 2004, 31, (18), 2113 2125. The K-eigenvalue problem in nuclear reactor physics is often formulated in the f r a m e w o r k of N e u t r o n T r a n s p o r t Theory. The f u n d a m e n t a l mode solution of this problem is usually o b t a i n e d by the power iteration method. Here, the study is concerned with the use of a Krylov sub-space method, called O R T H O M I N ( 1 ) , to obtain a more efficient solution of the K-eigenvalue problem. A matrix-free a p p r o a c h is proposed which can be easily implemented by using a transport code that can perform fixed source calculations. The power iteration and O R T H O M I N ( 1 ) schemes are compared for two realistic three-dimensional multi-group cases with isotropic scattering: an L W R b e n c h m a r k and a heavy water reactor problem. In both the schemes, within-group