- Email: [email protected]
01917 Effect of milling on the electrochemical performance of natural graphite as an anode material for lithium-ion battery
06 Electrical power generation and utilization (scientific, technical)
aluminium. The aluminium substitution gave rise to the increase of irreversible capacity at the first cycle. The X-ray diffraction study indicates that this was due to the decrease of the lithium occupancy of the 3a site in [Lit.,,-(Ni, Co, AI),,]s,,[(Ni, Co, Al)] 3h02. The improved synthesis condition for 2=0.03 increases the occupancy of lithium at the 3a site. Li(Nio.saCO,~,,,),,,,,,AI,,.,,~O~ obtained by the improved synthesis condition proved to have a high capacity density of 185 mAh/g, small irreversible capacity of 25 mAh/g at the first cycle, excellent cycle life and improved thermal stability.
contingency class using a modified BP algorithm. The screened critical contingencies are passed to the ranking module (four-layered feed-forward ANN) for their further ranking. The effectiveness of the proposed method is demonstrated by applying it for contingency screening and ranking at different loading conditions for IEEE 30-bus system and a practical 75-bus Indian system. Once trained, the cascade neural network gives fast and accurate screening and ranking for unknown patterns and will be suitable for on-line applications at energy management centre.
00/01915
00101921 Feasibility of fuel cell using dimethyl ether fuel
Direct methanol-air fuel cells for road transportation
McNicol, B. D. J. fonw Sorwr~cs. 1999. X3. ( I- 2). If; -3I. The direct methanol-air fuel cell is reviewed with special attention to its use in road transportation applications. The history of the technology is discussed and the various problems associated with its commercial development are assessed, in particular the mechanisms of the electrode reactions, the development of effective catalysts and the possible electrolytes which can be used. The barriers to successful commercialization are reviewed and suggestions for future work are given.
Effect of gas channel height on gas flow and gas diffusion In a molten carbonate fuel cell stack
00101916
Hirata, H. J. Porrer .Sourc~e,s.1999. 83. (l-2). 41-49. This paper reports on an investigation of the relationships between the gas channel height, the gas-flow characteristics and the gas-diffusion characteristics in a plate heat-exchanger type molten carbonate fuel cell stack. Effects of the gas channel height on the uniformity and pressure loss of the gas flow are evaluated by numerical analysis using a computational fluid dynamics code. The effects of the gas channel height on the distribution of the reactive gas concentration in the direction perpendicular to the channel flow are evaluated by an analytical solution of the two-dimensional concentration transport equation. Considering the results for uniformity and pressure loss of the gas flow and for distribution of the reactive gas concentration, the appropriate gas channel height in the molten carbonate fuel cell stack is investigated.
00/01917 Effect of milling on the electrochemical performance of natural graphite as an anode material for lithium-ion battery Wang, H. J. P~II~ SOWU~.~. 1999. 83. (1-~2). I41 147. Both jet milling and turbo milling can improve the electrochemical performance of natural graphite as the anode material for lithium-ion batteries. The effect of milling on electrochemical performance of natural graphite was discussed in terms of morphological change in graphite. A study is also included on the correlations between some aspects of morphology and electrochemical performance of natural graphite.
00101916 Effect of mlxin sequences on the electrode characteristics of lithium-Bon rechargeable batteries Kwang, M. K. J. Porrer .Sourcc~.r. 1999. 83, (I-2). 108-l 13. Measurements are made of the viscosity of a liquid-phase slurry by varying the mixing sequences, during the preparation of a positive electrode for a lithium-ion rechargeable battery. The slurry consisted of active material powder, conductive agent powder, polymer binder solution, and liquid solvent. The slurry viscosities are analysed through consideration of the suspension rheology. The half-cell characteristics of a positive electrode prepared from the slurry are also investigated. Although the same materials and the same contents are used, the slurries show different scales of viscosity that reflects different dispersion states of the solid particles. Accordingly, the half-cell exhibits different discharge characteristics. The best discharge capacity, in terms of stability during repeated cycle, is obtained by dry-mixing the powders and then adding binder solution and solvent in sequence.
00101919 Evaluation of transient switching over-voltages in Kuwait EHV network using EMTP Al-Hasawi, W. E/a. Pmwr .S.mr. Rrc..2000. 54. (I). I ~10. Switching surges are of primary importance in insulation co-ordination of EHV lines, as well as in designing insulation of systems different apparatus. This paper concerns determining switching over-voltages (surges) resulted from various switching conditions applied on Kuwait EHV (275 kV) transmission system network. The study is based on computer transient simulation using the EMTP program. Details of the system modelling are outlined. Switching representing different types of faults (L-G, LL-G, L-L, 3L-G), whether at the instant of fault inception or fault clearing, feeder energization and successful feeder reclosure are included. Switching under different loading conditions are considered. The influence of surge arresters on the switching surges is also investigated through conventional modelling. Results are assessed and the worst switching conditions are reported.
00/01920 Fast voltage contingency screening and rankfng using cascade neural network
Singh. S. N. Elwrric four SLFICI~ R~wtrrcl~. 2000. 53. (3).197-205. Voltage contingency selection and ranking is performed to choose the contingencies that cause the worst voltage problems. In this paper, a cascade neural network based approach is proposed for fast voltage contingency screening and ranking. The developed cascade neural network is a combination of a filter module and a ranking module. All the selected contingency cases are applied to the filter module, which is trained to classify them either in critical contingency class or in non-critical
Yasuvuki. T. .4(/r,. .4/&o/ FI,c~/.\ U’ru./tl. frm Iut.SIW/I.A/coh/ Fw/F, /.?r/r. 1998:403-40X. Discussed in this paper is the first feasibility study on fuel cell systems that use di-Me ether fDME) fuel. A direct DME fuel cell of 6 x 6 cm’ is demonstrated u&g a ‘polymer electrolyte fuel cell. The ceil almost performed as equally to that of a direct methanol fuel cell, however, I.5 times more steam had to be injected to the DME compared to the methanol. Technological improvements to the direct DME fuel cell indicate that it may become more attractive than the direct methanol fuel cell in the future owing to the low toxicity and high energy density of the direct DME fuel cell.
00/01922 High-speed transmission line relaying using artificial neural networks
Zahra. F. Ekc/vic Power .S~:F/WI.Y RescY/rd~. 2000. 53. (3).I73- I7Y. A novel feedforward neural network that indicates whether a fault is within or outside the protection zone (fault indicator) of a transmission line is presented. The same technique has been extended to locate the distance of the fault (fault locator). The proposed scheme utilizes the frequency spectrum of the voltages and currents to make a decision. Data obtained from the electromagnetic transient program for single-line-to-ground faults and three-phase faults have been tested and the results are found to be accurate. Using this neural network the relaying decision is obtained within a cycle after the fault inception. The performance of the trained neural network shows promise and has the potential for implementation in a digital relay for transmission line protection,
00/01923 Implementation of coordinated multiple facts controllers for damping oscillators Li, G. J. et al. E/w. Power. Syr. Rev..2000. 22. (2).79-92. A linear optimal controller ts designed to implement multiple Variable Series Compensations (VSCs) devices in transmission network of interconnected power systems. The proposed controller is utilized to damp inter-area oscillations and enhance power system damping during large disturbances. The effectiveness of the linear optimal controller to properly control such devices is demonstrated for a two-machine power system. Results from (i) digital simulation studies using a PSCADIEMTDC software package, and (ii) real-time digital simulation studies using a PSCADIRTDS, are discussed. The simulation results show that the controller contributes significantly to the damping of inter-area oscillations and the enhancement of power system damping. Moreover. the results of these different simulation studies agree quite well showing little discrepancies between them.
00101924 Influence of A as alloy additive on the oxygen evolution reaction on PbBPbOz electrode
Monahov, B. J. of'fowrr Souw~~. 2000, 85. (1).59-62. When a Pb/PbOz electrode is polarized in the PbOz potential region (02 I.0 V versus Hg/HgzSOj reference electrode), oxygen is evolved in parallel to PbOz formation. The rate of oxygen evolution depends on potential, temperature and alloying additives. In this investigation, the influence of Ag as alloying additive on the oxygen evolution reaction is studied using linear sweep voltammetry. Based on Tafel and Arrhenius plots, the influence of Ag on the oxygen over-voltage and on the activation energy of the process is determined. It was found that Ag from the metal surface is oxidized and Ag ions are incorporated into the PhOz layer where they decrease both the activation energy and the oxygen over-voltage of the process. Ag also changes the o/;+PbOz ratio and the structure of the PhO: layer.
00101925 Lithium insertion and extractfon kinetics of LI,+,V30e Kawakita, J. J. fowr Sowws. 1999. X3. (I-2). 79-83. Lithium insertion and extraction kinetics of lithium trivanadate, Li,+,V,O,. was investigated by using the electrochemical measurements at various temperatures and current densities. The results showed that the reaction rates of both insertion and extraction were limited by the small diffusivity of phase formed for v > I.5 upon lithiation. Li ’ ions in the Li.,VxOx Extraction reaction was also dependent on the thermodynamic factor on the basis of the incomplete reversibility of transformation from the Li,V,O, phase to the original LiVlO, one.
00101926 Lithium ion conduction In PEO-salt electrolytes gelled with PAN Choi. B. K. Solid Stcrre lonic.r. lY98. 113. 115. 123-127. Examinations of hybrid solid electrolyte films consisting of poly(ethylene oxide) (PEO), LiCIOI, a mixture of ethylene carbonate (EC) and -,butyrolactone (BL) and polyacrylonitrile (PAN) were carried out in order to obtain the best compromise between high conductivity, homogeneity and dimensional stability. Measurements of electric conductivity and differen-
Fuel and Energy Abstracts
July 2000
215
aluminium. The aluminium substitution gave rise to the increase of irreversible capacity at the first cycle. The X-ray diffraction study indicates that this was due to the decrease of the lithium occupancy of the 3a site in [Lit.,,-(Ni, Co, AI),,]s,,[(Ni, Co, Al)] 3h02. The improved synthesis condition for 2=0.03 increases the occupancy of lithium at the 3a site. Li(Nio.saCO,~,,,),,,,,,AI,,.,,~O~ obtained by the improved synthesis condition proved to have a high capacity density of 185 mAh/g, small irreversible capacity of 25 mAh/g at the first cycle, excellent cycle life and improved thermal stability.
contingency class using a modified BP algorithm. The screened critical contingencies are passed to the ranking module (four-layered feed-forward ANN) for their further ranking. The effectiveness of the proposed method is demonstrated by applying it for contingency screening and ranking at different loading conditions for IEEE 30-bus system and a practical 75-bus Indian system. Once trained, the cascade neural network gives fast and accurate screening and ranking for unknown patterns and will be suitable for on-line applications at energy management centre.
00/01915
00101921 Feasibility of fuel cell using dimethyl ether fuel
Direct methanol-air fuel cells for road transportation
McNicol, B. D. J. fonw Sorwr~cs. 1999. X3. ( I- 2). If; -3I. The direct methanol-air fuel cell is reviewed with special attention to its use in road transportation applications. The history of the technology is discussed and the various problems associated with its commercial development are assessed, in particular the mechanisms of the electrode reactions, the development of effective catalysts and the possible electrolytes which can be used. The barriers to successful commercialization are reviewed and suggestions for future work are given.
Effect of gas channel height on gas flow and gas diffusion In a molten carbonate fuel cell stack
00101916
Hirata, H. J. Porrer .Sourc~e,s.1999. 83. (l-2). 41-49. This paper reports on an investigation of the relationships between the gas channel height, the gas-flow characteristics and the gas-diffusion characteristics in a plate heat-exchanger type molten carbonate fuel cell stack. Effects of the gas channel height on the uniformity and pressure loss of the gas flow are evaluated by numerical analysis using a computational fluid dynamics code. The effects of the gas channel height on the distribution of the reactive gas concentration in the direction perpendicular to the channel flow are evaluated by an analytical solution of the two-dimensional concentration transport equation. Considering the results for uniformity and pressure loss of the gas flow and for distribution of the reactive gas concentration, the appropriate gas channel height in the molten carbonate fuel cell stack is investigated.
00/01917 Effect of milling on the electrochemical performance of natural graphite as an anode material for lithium-ion battery Wang, H. J. P~II~ SOWU~.~. 1999. 83. (1-~2). I41 147. Both jet milling and turbo milling can improve the electrochemical performance of natural graphite as the anode material for lithium-ion batteries. The effect of milling on electrochemical performance of natural graphite was discussed in terms of morphological change in graphite. A study is also included on the correlations between some aspects of morphology and electrochemical performance of natural graphite.
00101916 Effect of mlxin sequences on the electrode characteristics of lithium-Bon rechargeable batteries Kwang, M. K. J. Porrer .Sourcc~.r. 1999. 83, (I-2). 108-l 13. Measurements are made of the viscosity of a liquid-phase slurry by varying the mixing sequences, during the preparation of a positive electrode for a lithium-ion rechargeable battery. The slurry consisted of active material powder, conductive agent powder, polymer binder solution, and liquid solvent. The slurry viscosities are analysed through consideration of the suspension rheology. The half-cell characteristics of a positive electrode prepared from the slurry are also investigated. Although the same materials and the same contents are used, the slurries show different scales of viscosity that reflects different dispersion states of the solid particles. Accordingly, the half-cell exhibits different discharge characteristics. The best discharge capacity, in terms of stability during repeated cycle, is obtained by dry-mixing the powders and then adding binder solution and solvent in sequence.
00101919 Evaluation of transient switching over-voltages in Kuwait EHV network using EMTP Al-Hasawi, W. E/a. Pmwr .S.mr. Rrc..2000. 54. (I). I ~10. Switching surges are of primary importance in insulation co-ordination of EHV lines, as well as in designing insulation of systems different apparatus. This paper concerns determining switching over-voltages (surges) resulted from various switching conditions applied on Kuwait EHV (275 kV) transmission system network. The study is based on computer transient simulation using the EMTP program. Details of the system modelling are outlined. Switching representing different types of faults (L-G, LL-G, L-L, 3L-G), whether at the instant of fault inception or fault clearing, feeder energization and successful feeder reclosure are included. Switching under different loading conditions are considered. The influence of surge arresters on the switching surges is also investigated through conventional modelling. Results are assessed and the worst switching conditions are reported.
00/01920 Fast voltage contingency screening and rankfng using cascade neural network
Singh. S. N. Elwrric four SLFICI~ R~wtrrcl~. 2000. 53. (3).197-205. Voltage contingency selection and ranking is performed to choose the contingencies that cause the worst voltage problems. In this paper, a cascade neural network based approach is proposed for fast voltage contingency screening and ranking. The developed cascade neural network is a combination of a filter module and a ranking module. All the selected contingency cases are applied to the filter module, which is trained to classify them either in critical contingency class or in non-critical
Yasuvuki. T. .4(/r,. .4/&o/ FI,c~/.\ U’ru./tl. frm Iut.SIW/I.A/coh/ Fw/F, /.?r/r. 1998:403-40X. Discussed in this paper is the first feasibility study on fuel cell systems that use di-Me ether fDME) fuel. A direct DME fuel cell of 6 x 6 cm’ is demonstrated u&g a ‘polymer electrolyte fuel cell. The ceil almost performed as equally to that of a direct methanol fuel cell, however, I.5 times more steam had to be injected to the DME compared to the methanol. Technological improvements to the direct DME fuel cell indicate that it may become more attractive than the direct methanol fuel cell in the future owing to the low toxicity and high energy density of the direct DME fuel cell.
00/01922 High-speed transmission line relaying using artificial neural networks
Zahra. F. Ekc/vic Power .S~:F/WI.Y RescY/rd~. 2000. 53. (3).I73- I7Y. A novel feedforward neural network that indicates whether a fault is within or outside the protection zone (fault indicator) of a transmission line is presented. The same technique has been extended to locate the distance of the fault (fault locator). The proposed scheme utilizes the frequency spectrum of the voltages and currents to make a decision. Data obtained from the electromagnetic transient program for single-line-to-ground faults and three-phase faults have been tested and the results are found to be accurate. Using this neural network the relaying decision is obtained within a cycle after the fault inception. The performance of the trained neural network shows promise and has the potential for implementation in a digital relay for transmission line protection,
00/01923 Implementation of coordinated multiple facts controllers for damping oscillators Li, G. J. et al. E/w. Power. Syr. Rev..2000. 22. (2).79-92. A linear optimal controller ts designed to implement multiple Variable Series Compensations (VSCs) devices in transmission network of interconnected power systems. The proposed controller is utilized to damp inter-area oscillations and enhance power system damping during large disturbances. The effectiveness of the linear optimal controller to properly control such devices is demonstrated for a two-machine power system. Results from (i) digital simulation studies using a PSCADIEMTDC software package, and (ii) real-time digital simulation studies using a PSCADIRTDS, are discussed. The simulation results show that the controller contributes significantly to the damping of inter-area oscillations and the enhancement of power system damping. Moreover. the results of these different simulation studies agree quite well showing little discrepancies between them.
00101924 Influence of A as alloy additive on the oxygen evolution reaction on PbBPbOz electrode
Monahov, B. J. of'fowrr Souw~~. 2000, 85. (1).59-62. When a Pb/PbOz electrode is polarized in the PbOz potential region (02 I.0 V versus Hg/HgzSOj reference electrode), oxygen is evolved in parallel to PbOz formation. The rate of oxygen evolution depends on potential, temperature and alloying additives. In this investigation, the influence of Ag as alloying additive on the oxygen evolution reaction is studied using linear sweep voltammetry. Based on Tafel and Arrhenius plots, the influence of Ag on the oxygen over-voltage and on the activation energy of the process is determined. It was found that Ag from the metal surface is oxidized and Ag ions are incorporated into the PhOz layer where they decrease both the activation energy and the oxygen over-voltage of the process. Ag also changes the o/;+PbOz ratio and the structure of the PhO: layer.
00101925 Lithium insertion and extractfon kinetics of LI,+,V30e Kawakita, J. J. fowr Sowws. 1999. X3. (I-2). 79-83. Lithium insertion and extraction kinetics of lithium trivanadate, Li,+,V,O,. was investigated by using the electrochemical measurements at various temperatures and current densities. The results showed that the reaction rates of both insertion and extraction were limited by the small diffusivity of phase formed for v > I.5 upon lithiation. Li ’ ions in the Li.,VxOx Extraction reaction was also dependent on the thermodynamic factor on the basis of the incomplete reversibility of transformation from the Li,V,O, phase to the original LiVlO, one.
00101926 Lithium ion conduction In PEO-salt electrolytes gelled with PAN Choi. B. K. Solid Stcrre lonic.r. lY98. 113. 115. 123-127. Examinations of hybrid solid electrolyte films consisting of poly(ethylene oxide) (PEO), LiCIOI, a mixture of ethylene carbonate (EC) and -,butyrolactone (BL) and polyacrylonitrile (PAN) were carried out in order to obtain the best compromise between high conductivity, homogeneity and dimensional stability. Measurements of electric conductivity and differen-
Fuel and Energy Abstracts
July 2000
215