A 75-meter-long, 3-phase and 10.5kV/ 1.5kA high temperature superconducting power cable, a brainchild of researchers from the CAS Institute of Electrical Engineering, has been operating stably and reliably for 7,000 h...A 75-meter-long, 3-phase and 10.5kV/ 1.5kA high temperature superconducting power cable, a brainchild of researchers from the CAS Institute of Electrical Engineering, has been operating stably and reliably for 7,000 hours in a power distribution grid.展开更多
The newly revised and enlarged main contents of the Law of Prevention and Control of Atmospheric Pollution are described, The macro impacts of the law on the power industry development are analyzed mainly in respects ...The newly revised and enlarged main contents of the Law of Prevention and Control of Atmospheric Pollution are described, The macro impacts of the law on the power industry development are analyzed mainly in respects to power demand and readjustment of power structure and layout. clean production and pollution control level, scientific management of environmental protection, in accordance with law as well as changes of construction and operation costs. And finally, several questions worthy to be noted in course of implementation of the new law are enumerated.展开更多
Energy regeneration during braking is an important technique for hybrid electric vehicle (HEV) to improve their fuel economy and extend their driving range. Due to the effect of regenerative braking torque which is ad...Energy regeneration during braking is an important technique for hybrid electric vehicle (HEV) to improve their fuel economy and extend their driving range. Due to the effect of regenerative braking torque which is added by electric motor, the braking torque distribution between front and rear axles should be changed and the control logic of anti-lock braking system (ABS) ought to be adjusted according to the regenerative braking torque. This paper put forward a braking control strategy for hybrid electric vehicle; the control strategy is implemented with eight DOFs (Degree-of-Freedom) nonlinear vehicle forward simulation model which is built under the environment of Matlab/Simulink. Based on target wheel slip ratio, a fuzzy logic approach was applied to maintain the optimal target slip ratio so that best compromise between hydraulic torque and regenerative torque can be obtained for the vehicle.展开更多
Firstly,the concepts of the traveling wave entropy and the feature function of traveling wave entropy were defined.Then the statistic characters of the traveling wave entropy feature function,mean value and variance w...Firstly,the concepts of the traveling wave entropy and the feature function of traveling wave entropy were defined.Then the statistic characters of the traveling wave entropy feature function,mean value and variance were analyzed after the zero-order component of the traveling wave of online cable was selected to serve as the observed object.Finally,the new recognition algorithm of minimum risk neural network was pre- sented.The simulation experiments show that the recognitions of the early fault states can be completed correctly by using the proposed recognition algorithm.The classes of cable faults include in 1-phase ground faults,and the 2-phase short circuit faults or ground faults and the 3-phase short circuit faults or ground faults,open circuit.The fault resistance range is 1×10^(-1)～1×10~9Ω.展开更多
The paper aims to demonstrate the system of SANYI biogas power generation by two-step method which can produce methane and generate electricity effectively and stably.So it can be stable synchronization meshwork energ...The paper aims to demonstrate the system of SANYI biogas power generation by two-step method which can produce methane and generate electricity effectively and stably.So it can be stable synchronization meshwork energy source establishment and provide references to develop an effective and stable project of producing methane and generating electricity.展开更多
This paper focuses on the state space modeling approach and output torques prediction of torsional vibrations for variable speed wind turbines. The multi-body system model under study is mainly comprised of a wind tur...This paper focuses on the state space modeling approach and output torques prediction of torsional vibrations for variable speed wind turbines. The multi-body system model under study is mainly comprised of a wind turbine, a three stage planetary gear box and an induction generator. The masses-springs approach of shaft system differential equations is developed from Newton＇s law and Lagrange formulas. For an easy comprehension for electrical engineers and tutorial purpose, an electrical equivalent circuit of the system is proposed by using mechanical and electrical components similarities. Extensive numerical simulations are performed to investigate system mechanical resonances and impacts of damping factors on the system dynamic and stability.展开更多
A new method of electrical discharge machining （EDM） in air-mixed medium--air-mixed EDM was presented, and comparative experiments were carried out to compare the machining characteristics of air-mixed EDM with conv...A new method of electrical discharge machining （EDM） in air-mixed medium--air-mixed EDM was presented, and comparative experiments were carried out to compare the machining characteristics of air-mixed EDM with conventional EDM. The experimental results showed that better machining performances were obtained with tool electrode as the cathode and workpieee as the anode. It was found that the material removal rate （MRR） was higher, the tool electrode relative wear ratio （TWR） was lower and the surface roughness （SR） quality was better in the case of air-mixed EDM than that of conventional EDM, and the reasons bringing out the results were analyzed.展开更多
There are learners who cannot solve practical problems in spite of mastering basic scientific knowledge and formula necessary for the solution. One of the reasons might be attributed to the lack in metacognitive abili...There are learners who cannot solve practical problems in spite of mastering basic scientific knowledge and formula necessary for the solution. One of the reasons might be attributed to the lack in metacognitive abilities. The aim of this study was to compare the metacognitive characteristics between non-major and major students in electric engineering and clarify the difference of metacognitive process between these two groups when solving basic problems of electronic circuit. In the experiment, the solving process was compared between non-major and major students in electric engineering using five basic problems. We found that the scores on prediction of result and confidence of own answer differed significantly between non-major and major students, and inferred that the difference of performance was due to the lack in metacognitive ability, especially the plan and the execution abilities. Both prediction of results and confidence of own answer were also found to play a significant role in effective problem solving as important components （subsystems） of metacognition.展开更多
Business Directory defines economic power as ＂conditions of having sufficient productive resources at command that give the capacity to make and enforce economic decisions, such as allocation of resources and apporti...Business Directory defines economic power as ＂conditions of having sufficient productive resources at command that give the capacity to make and enforce economic decisions, such as allocation of resources and apportioning of goods and services＂. This qualitative definition may be sufficient for general discussions, but it does not offer any quantitative measurements for management and control. Is there a way to measure economic power for analysis and synthesis of economic systems in this 21st century？ This paper answers this question by introducing a set of quantitative terms from the field of electrical engineering, used in power measurement and control of electrical systems. Circuit theory concepts are introduced to show how the relationship between cash and cash flow in finance is analogous to that of electric charge and electric current and how education level, as economic potential, is analogous to electrical potential that causes current to flow in a circuit. An individual is identified as the basic cash flow source in the economy. Circuit models for an individual as well as a typical production facility are developed and demonstrated with an example. Equations for the measurement of economic power, losses, efficiency, and power factor are presented. It is shown that the individuals are the basic cash flow sources and producers of economic power.展开更多
文摘A 75-meter-long, 3-phase and 10.5kV/ 1.5kA high temperature superconducting power cable, a brainchild of researchers from the CAS Institute of Electrical Engineering, has been operating stably and reliably for 7,000 hours in a power distribution grid.
文摘The newly revised and enlarged main contents of the Law of Prevention and Control of Atmospheric Pollution are described, The macro impacts of the law on the power industry development are analyzed mainly in respects to power demand and readjustment of power structure and layout. clean production and pollution control level, scientific management of environmental protection, in accordance with law as well as changes of construction and operation costs. And finally, several questions worthy to be noted in course of implementation of the new law are enumerated.
基金863 National Project EQ7200HEV hybridelectric vehicle (2001AA501200,2003AA501200)
文摘Energy regeneration during braking is an important technique for hybrid electric vehicle (HEV) to improve their fuel economy and extend their driving range. Due to the effect of regenerative braking torque which is added by electric motor, the braking torque distribution between front and rear axles should be changed and the control logic of anti-lock braking system (ABS) ought to be adjusted according to the regenerative braking torque. This paper put forward a braking control strategy for hybrid electric vehicle; the control strategy is implemented with eight DOFs (Degree-of-Freedom) nonlinear vehicle forward simulation model which is built under the environment of Matlab/Simulink. Based on target wheel slip ratio, a fuzzy logic approach was applied to maintain the optimal target slip ratio so that best compromise between hydraulic torque and regenerative torque can be obtained for the vehicle.
基金the Science and Technology Foundation of Shaanxi Province in China(2003K06G19)
文摘Firstly,the concepts of the traveling wave entropy and the feature function of traveling wave entropy were defined.Then the statistic characters of the traveling wave entropy feature function,mean value and variance were analyzed after the zero-order component of the traveling wave of online cable was selected to serve as the observed object.Finally,the new recognition algorithm of minimum risk neural network was pre- sented.The simulation experiments show that the recognitions of the early fault states can be completed correctly by using the proposed recognition algorithm.The classes of cable faults include in 1-phase ground faults,and the 2-phase short circuit faults or ground faults and the 3-phase short circuit faults or ground faults,open circuit.The fault resistance range is 1×10^(-1)～1×10~9Ω.
文摘The paper aims to demonstrate the system of SANYI biogas power generation by two-step method which can produce methane and generate electricity effectively and stably.So it can be stable synchronization meshwork energy source establishment and provide references to develop an effective and stable project of producing methane and generating electricity.
文摘This paper focuses on the state space modeling approach and output torques prediction of torsional vibrations for variable speed wind turbines. The multi-body system model under study is mainly comprised of a wind turbine, a three stage planetary gear box and an induction generator. The masses-springs approach of shaft system differential equations is developed from Newton＇s law and Lagrange formulas. For an easy comprehension for electrical engineers and tutorial purpose, an electrical equivalent circuit of the system is proposed by using mechanical and electrical components similarities. Extensive numerical simulations are performed to investigate system mechanical resonances and impacts of damping factors on the system dynamic and stability.
基金the Post-doctor Foundation of Heilongjiang Province(Grant No.LBH-Z06139).
文摘A new method of electrical discharge machining （EDM） in air-mixed medium--air-mixed EDM was presented, and comparative experiments were carried out to compare the machining characteristics of air-mixed EDM with conventional EDM. The experimental results showed that better machining performances were obtained with tool electrode as the cathode and workpieee as the anode. It was found that the material removal rate （MRR） was higher, the tool electrode relative wear ratio （TWR） was lower and the surface roughness （SR） quality was better in the case of air-mixed EDM than that of conventional EDM, and the reasons bringing out the results were analyzed.
文摘There are learners who cannot solve practical problems in spite of mastering basic scientific knowledge and formula necessary for the solution. One of the reasons might be attributed to the lack in metacognitive abilities. The aim of this study was to compare the metacognitive characteristics between non-major and major students in electric engineering and clarify the difference of metacognitive process between these two groups when solving basic problems of electronic circuit. In the experiment, the solving process was compared between non-major and major students in electric engineering using five basic problems. We found that the scores on prediction of result and confidence of own answer differed significantly between non-major and major students, and inferred that the difference of performance was due to the lack in metacognitive ability, especially the plan and the execution abilities. Both prediction of results and confidence of own answer were also found to play a significant role in effective problem solving as important components （subsystems） of metacognition.
文摘Business Directory defines economic power as ＂conditions of having sufficient productive resources at command that give the capacity to make and enforce economic decisions, such as allocation of resources and apportioning of goods and services＂. This qualitative definition may be sufficient for general discussions, but it does not offer any quantitative measurements for management and control. Is there a way to measure economic power for analysis and synthesis of economic systems in this 21st century？ This paper answers this question by introducing a set of quantitative terms from the field of electrical engineering, used in power measurement and control of electrical systems. Circuit theory concepts are introduced to show how the relationship between cash and cash flow in finance is analogous to that of electric charge and electric current and how education level, as economic potential, is analogous to electrical potential that causes current to flow in a circuit. An individual is identified as the basic cash flow source in the economy. Circuit models for an individual as well as a typical production facility are developed and demonstrated with an example. Equations for the measurement of economic power, losses, efficiency, and power factor are presented. It is shown that the individuals are the basic cash flow sources and producers of economic power.
