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02099 Power system probabilistic security assessment using bayes classifier
06 Electrical power supply and utilization (scientific, technical) electrolyte and a Mg foil as the anode. The e.m.f, values of the cells ranged from 1.62 to 1.94 V, their specific energies from 4.34 to 8.88 Wh/kg and their energy densities from 3.10 to 6.34 mWh/cm3 for cathodes containing 10 50% in zeolite. The parameter r, which characterizes the aging rate of the polyaniline/zeolite cathode ranges between 70 and 320 h. The higher r is, the slower is the aging of the sample. The best combination of high conductivity, slow aging of the cathode and high specific energy of the cells was obtained between 25 and 35% of zeolite content. Moreover, surface examination of the polyaniline/zeolite samples, was performed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques.
05•02098 Power generation using a mesoscale fuel cell integrated with a microscale fuel processor Holladay, J. D. et al. Journa[ of Power Sources, 2004, 130, (1 2), 111 118. An integrated fuel reformer and fuel cell system for microscale (10 500 mW) power generation is being developed and demonstrated as an alternative to conventional batteries. In this system, thermal energy is transformed to electricity by stripping the hydrogen from the hydrocarbon fuel (reforming) and converting the hydrogen to electricity in a proton exchange membrane (PEM) fuel cell. The fabrication and operation of a mesoscale fuel cell based on phosphoric acid doped polybenzimidazole (PBI) technology is discussed, along with tests integrating the methanol processor with the fuel cell. The PBI membrane had high ionic conductivity at high temperatures (> 150c'C), and sustained the high conductivity at low relative humidity at these temperatures. This high-temperature stability and high ionic conductivity enabled the membrane to tolerate extremely high levels of carbon monoxide up to 10% without significant degradation in performance. The combined fuel cell/reformer system was successfully operated to enable the production of 23 mW of electrical power.
05•02099 Power system probabilistic security assessment using Bayes classifier Kim, H. and Singh, C. Electric Power Systems Research, 2005, 74, (1), 157 165. This paper presents a method for power system security assessment based on the Bayes classifier. This method can be applied to calculate probabilistic security indices as well as on-line security assessment. In general, the determination of security breach is a cumbersome and time-consuming process due to dynamic and steady-state effects. These effects can be incorporated by considering transient stability, satisfaction of system load without violation of constraints, and voltage stability studies. The variation of the system load, as well as contingencies, may cause system transition to a different operating state. It is impractical if not impossible to evaluate all these situations, such as contingencies resulting from load variation. The straightforward Monte Carlo simulation, one of the possible methods in power system reliability analysis, requires the evaluation of a system operating state for each sampled state and is computation-intensive. In the proposed method, first the joint probability density of feature vectors has been obtained by using some training data. Once this joint distribution is obtained, the Bayes classifier provides the assessment of system security without complicated contingency analyses and can reduce the computational burden. Security status of a given feature vector can be determined by a posteriori probability rule called Bayes rule, which can be implemented in on-line security assessment or power system reliability studies.
05•02100 Quick testing of batteries in lithium-ion battery packs with impedance-measuring technology Takeno, K. et al. Journal of Power Sources, 2004, 128, (1), 67 75. This paper discusses a rapid testing of capacity in Li-ion battery packs with impedance-measuring technology to evaluate their capability in mobile phones. The measurements of the capacity and impedance at 1 kHz for various kinds of battery packs conclusively proved that there is a strong correlation between capacity and impedance. It can be applied even when the pack consists of not only a Li-ion battery but also a Positive Temperature Coefficient (PTC) device and a protection circuit in-series, and this correlation is largely unaffected by the degree of charge. The results obtained from measuring impedance revealed the possibility of quickly assessing degradation in Li-ion battery packs.
05•02101 Research and development on HTGR fuel in the HTTR project Sawa, K. and Ueta, S. Nuclear Engineering andDesign, 2004, 233, (1 3), 163 172. In the high temperature gas-cooled reactors (HTGRs), refractory coated fuel particles are employed as fuel to permit high outlet coolant temperature. The high temperature engineering test reactor (HTTR) employs tri-isotropic (TRISO)-coated fuel particles in the prismatic fuel assembly. Research and development on the HTTR fuel has been carried out spread over about 30 years, in fuel fabrication technologies, fuel performance, and so on. Furthermore, for upgrading of HTGR
310
Fuel and Energy Abstracts
September 2005
technologies, an extended burnup TRISO-coated fuel particle and an advanced type of coated fuel particle, ZrC-coated fuel particle in order to keep the integrity at higher operating temperatures has been developed. The present paper provides experiences and current status of research and development works for the HTGR fuel in the HTTR Project.
05•02102 Study of electrical treeing phenomena in XLPE cable samples using acoustic techniques Sarathi, R. and Raju, P. G. Electric Power Systems Research, 2005, 73, (2), 159 168. Electrical trees were generated experimentally in the actual 33 kV underground XLPE cable insulation material under the AC voltages. A tree-like structure and a bush type of tree structure can form from the point of defect site under the AC voltages. Acoustic emission technique was adopted to identify the point of inception, propagation and termination of electrical trees. A variation in the dominant frequency content of the acoustic signal was observed as and when the tree propagates in the insulation structure. The characteristic variation in the magnitude of the acoustic emission signal with time, indicates that tree propagation as an intermittent growth process. The energy content of the acoustic signal characterizes that the energy released due to partial discharges, at every step growth of the tree structure is not the same. The partial power measurement in the present study provides an indication to the growth process of electrical trees and to the near point of failure of polymer insulation material due to electrical treeing.
05•02103 Surface properties of inorganic fillers for application in composite membranes-direct methanol fuel cells Aric6, A. S. et al. Journal of Power Sources, 2004, 128, (2), 113 118. The surface properties of inorganic fillers employed in composite membranes have been investigated by X-ray photoelectron spectroscopy (XPS), BET surface area and acid~ase characterizations. The adsorption density of hydroxyl hydrogen ions and the pH of slurry varied with the amount and strength of acid~ase surface functionalities. A shift towards higher binding energies was observed for the O ls photoelectron peak as a function of the increase of the filler acidic behaviour. The conductivity of the membranes and the maximum power density at 145c'C for direct methanol fuel cells (DMFCs) increased with the filler surface acidity.
05•02104 The effect of transformer maintenance parameters on reliability and cost: a probabilistic model Jirutitijaroen, P. and Singh, C. Electric Power Systems Research, 2004, 72, (3), 213 224. A transformer is a piece of equipment common to most power systems. Preventive maintenance is performed to extend the equipment lifetime. Models relating probability of failure to maintenance activity are proposed in earlier studies. The model parameters, which are mean time in each stage, inspection rate of each stage, and probabilities of transition from one stage to others, have an effect on reliability and cost of maintenance. In order to establish a cost-effective maintenance process, analysis of model parameters should be conducted thoroughly. This paper develops detailed models relating maintenance parameters to reliability and cost and then investigates the effect of varying model parameters. Simulation results from the proposed model are shown and corroborated by mathematical analysis of a simpler equivalent model. The analysis covers mean time to the first failure, maintenance cost, inspection cost, and failure cost.
05•02105 The magnetic field and induced current arising from a cylindrical shell loop with an unbalanced current Xu, L. eta[. Electric Power Systems Research, 2004, 71, (1), 21 26. This paper addresses the magnetic field and induced current associated with a cylindrical shell loop under the excitation of an unbalance current source. An equivalent circuit theory is introduced to describe the coupling effect when the cylindrical shell loop is formed. Closeform expressions of the circuit component parameters are derived, as well as the induced current and magnetic field. An experimental validation of the theory is presented. It is demonstrated that an electrically 'isolated' cylindrical shell has no shielding effect, and effective shielding results if an opposite electric current flows along the cylindrical shell. Any additional resistance introduced in the loop will degrade the shielding performance.
05•02106 The rational approximation method in the prediction of thermodynamic properties for SOFCs Hern~ndez-Pacheco, E. and Mann, M. D. Journal of Power Sources, 2004, 128, (1), 25 33. The aim of this work is to present the method of rational approximation as an alternative technique for finding empirical models for thermophysical properties of relevant fluids to solid oxide fuel cells (SOFCs). The method of rational approximation is used here for calculating the isobaric heat capacity, the entropy of formation, the
05•02098 Power generation using a mesoscale fuel cell integrated with a microscale fuel processor Holladay, J. D. et al. Journa[ of Power Sources, 2004, 130, (1 2), 111 118. An integrated fuel reformer and fuel cell system for microscale (10 500 mW) power generation is being developed and demonstrated as an alternative to conventional batteries. In this system, thermal energy is transformed to electricity by stripping the hydrogen from the hydrocarbon fuel (reforming) and converting the hydrogen to electricity in a proton exchange membrane (PEM) fuel cell. The fabrication and operation of a mesoscale fuel cell based on phosphoric acid doped polybenzimidazole (PBI) technology is discussed, along with tests integrating the methanol processor with the fuel cell. The PBI membrane had high ionic conductivity at high temperatures (> 150c'C), and sustained the high conductivity at low relative humidity at these temperatures. This high-temperature stability and high ionic conductivity enabled the membrane to tolerate extremely high levels of carbon monoxide up to 10% without significant degradation in performance. The combined fuel cell/reformer system was successfully operated to enable the production of 23 mW of electrical power.
05•02099 Power system probabilistic security assessment using Bayes classifier Kim, H. and Singh, C. Electric Power Systems Research, 2005, 74, (1), 157 165. This paper presents a method for power system security assessment based on the Bayes classifier. This method can be applied to calculate probabilistic security indices as well as on-line security assessment. In general, the determination of security breach is a cumbersome and time-consuming process due to dynamic and steady-state effects. These effects can be incorporated by considering transient stability, satisfaction of system load without violation of constraints, and voltage stability studies. The variation of the system load, as well as contingencies, may cause system transition to a different operating state. It is impractical if not impossible to evaluate all these situations, such as contingencies resulting from load variation. The straightforward Monte Carlo simulation, one of the possible methods in power system reliability analysis, requires the evaluation of a system operating state for each sampled state and is computation-intensive. In the proposed method, first the joint probability density of feature vectors has been obtained by using some training data. Once this joint distribution is obtained, the Bayes classifier provides the assessment of system security without complicated contingency analyses and can reduce the computational burden. Security status of a given feature vector can be determined by a posteriori probability rule called Bayes rule, which can be implemented in on-line security assessment or power system reliability studies.
05•02100 Quick testing of batteries in lithium-ion battery packs with impedance-measuring technology Takeno, K. et al. Journal of Power Sources, 2004, 128, (1), 67 75. This paper discusses a rapid testing of capacity in Li-ion battery packs with impedance-measuring technology to evaluate their capability in mobile phones. The measurements of the capacity and impedance at 1 kHz for various kinds of battery packs conclusively proved that there is a strong correlation between capacity and impedance. It can be applied even when the pack consists of not only a Li-ion battery but also a Positive Temperature Coefficient (PTC) device and a protection circuit in-series, and this correlation is largely unaffected by the degree of charge. The results obtained from measuring impedance revealed the possibility of quickly assessing degradation in Li-ion battery packs.
05•02101 Research and development on HTGR fuel in the HTTR project Sawa, K. and Ueta, S. Nuclear Engineering andDesign, 2004, 233, (1 3), 163 172. In the high temperature gas-cooled reactors (HTGRs), refractory coated fuel particles are employed as fuel to permit high outlet coolant temperature. The high temperature engineering test reactor (HTTR) employs tri-isotropic (TRISO)-coated fuel particles in the prismatic fuel assembly. Research and development on the HTTR fuel has been carried out spread over about 30 years, in fuel fabrication technologies, fuel performance, and so on. Furthermore, for upgrading of HTGR
310
Fuel and Energy Abstracts
September 2005
technologies, an extended burnup TRISO-coated fuel particle and an advanced type of coated fuel particle, ZrC-coated fuel particle in order to keep the integrity at higher operating temperatures has been developed. The present paper provides experiences and current status of research and development works for the HTGR fuel in the HTTR Project.
05•02102 Study of electrical treeing phenomena in XLPE cable samples using acoustic techniques Sarathi, R. and Raju, P. G. Electric Power Systems Research, 2005, 73, (2), 159 168. Electrical trees were generated experimentally in the actual 33 kV underground XLPE cable insulation material under the AC voltages. A tree-like structure and a bush type of tree structure can form from the point of defect site under the AC voltages. Acoustic emission technique was adopted to identify the point of inception, propagation and termination of electrical trees. A variation in the dominant frequency content of the acoustic signal was observed as and when the tree propagates in the insulation structure. The characteristic variation in the magnitude of the acoustic emission signal with time, indicates that tree propagation as an intermittent growth process. The energy content of the acoustic signal characterizes that the energy released due to partial discharges, at every step growth of the tree structure is not the same. The partial power measurement in the present study provides an indication to the growth process of electrical trees and to the near point of failure of polymer insulation material due to electrical treeing.
05•02103 Surface properties of inorganic fillers for application in composite membranes-direct methanol fuel cells Aric6, A. S. et al. Journal of Power Sources, 2004, 128, (2), 113 118. The surface properties of inorganic fillers employed in composite membranes have been investigated by X-ray photoelectron spectroscopy (XPS), BET surface area and acid~ase characterizations. The adsorption density of hydroxyl hydrogen ions and the pH of slurry varied with the amount and strength of acid~ase surface functionalities. A shift towards higher binding energies was observed for the O ls photoelectron peak as a function of the increase of the filler acidic behaviour. The conductivity of the membranes and the maximum power density at 145c'C for direct methanol fuel cells (DMFCs) increased with the filler surface acidity.
05•02104 The effect of transformer maintenance parameters on reliability and cost: a probabilistic model Jirutitijaroen, P. and Singh, C. Electric Power Systems Research, 2004, 72, (3), 213 224. A transformer is a piece of equipment common to most power systems. Preventive maintenance is performed to extend the equipment lifetime. Models relating probability of failure to maintenance activity are proposed in earlier studies. The model parameters, which are mean time in each stage, inspection rate of each stage, and probabilities of transition from one stage to others, have an effect on reliability and cost of maintenance. In order to establish a cost-effective maintenance process, analysis of model parameters should be conducted thoroughly. This paper develops detailed models relating maintenance parameters to reliability and cost and then investigates the effect of varying model parameters. Simulation results from the proposed model are shown and corroborated by mathematical analysis of a simpler equivalent model. The analysis covers mean time to the first failure, maintenance cost, inspection cost, and failure cost.
05•02105 The magnetic field and induced current arising from a cylindrical shell loop with an unbalanced current Xu, L. eta[. Electric Power Systems Research, 2004, 71, (1), 21 26. This paper addresses the magnetic field and induced current associated with a cylindrical shell loop under the excitation of an unbalance current source. An equivalent circuit theory is introduced to describe the coupling effect when the cylindrical shell loop is formed. Closeform expressions of the circuit component parameters are derived, as well as the induced current and magnetic field. An experimental validation of the theory is presented. It is demonstrated that an electrically 'isolated' cylindrical shell has no shielding effect, and effective shielding results if an opposite electric current flows along the cylindrical shell. Any additional resistance introduced in the loop will degrade the shielding performance.
05•02106 The rational approximation method in the prediction of thermodynamic properties for SOFCs Hern~ndez-Pacheco, E. and Mann, M. D. Journal of Power Sources, 2004, 128, (1), 25 33. The aim of this work is to present the method of rational approximation as an alternative technique for finding empirical models for thermophysical properties of relevant fluids to solid oxide fuel cells (SOFCs). The method of rational approximation is used here for calculating the isobaric heat capacity, the entropy of formation, the