We take the contribution of all valence electrons into consideration and propose a new valence electrons equilibration method to calculate the equalized electronegativity including molecular electronegativity, group e...We take the contribution of all valence electrons into consideration and propose a new valence electrons equilibration method to calculate the equalized electronegativity including molecular electronegativity, group electronegativity, and atomic charge. The ionization potential of alkanes and mono-substituted alkanes, the chemical shift of 1H NMR, and the gas phase proton affinity of aliphatic amines, alcohols, and ethers were estimated. All the expressions have good correlations. Moreover, the Sanderson method and Bratsch method were modified on the basis of the valence electrons equilibration theory. The modified Sanderson method and modified Bratsch method are more effective than their original methods to estimate these properties.展开更多
The electro-elastic interaction between a piezoelectric screw dislocation and an elliptical piezoelectric inhomogeneity, which contains an electrically conductive confocal elliptical rigid core under remote anti-plane...The electro-elastic interaction between a piezoelectric screw dislocation and an elliptical piezoelectric inhomogeneity, which contains an electrically conductive confocal elliptical rigid core under remote anti-plane shear stresses and in-plane electrical load is dealt with. The anaJytical solutions to the elastic field and the electric field, the interracial stress fields of inhomogeneity and matrix under longitudinal shear and the image force acting on the dislocation are derived by means of complex method. The effect of material properties and geometric configurations of the rigid core on interracial stresses generated by a remote uniform load, rigid core and material electroelastic properties on the image force is discussed.展开更多
The first fluorine-substituted hexabenzocoronene has been synthesized and its electronic structure and optical properties have been reported [Q. Zhang, et al., Org. Lett. 7 （2005） 5019]. In this letter, the electron...The first fluorine-substituted hexabenzocoronene has been synthesized and its electronic structure and optical properties have been reported [Q. Zhang, et al., Org. Lett. 7 （2005） 5019]. In this letter, the electronic structure and excited state properties of the fluorine-substituted hexabenzocoronene are studied with quantum chemistry method as well as the transition and the charge difference densities. The transition densities show the orientations and strength of the dipole moments and the charge difference densities reveal the orientation and results of the intramolecular charge transfer. The calculated transition energies and oscillator strengths are consistent with the experimental data, and the theoretical results of transition and charge difference densities are valuable to understanding the excited state properties of the fluorine-substituted hexabenzocoronene.展开更多
Since distribution sector is inherent into high amount of failures, distribution companies (DISCOs) are responsible of attaining an acceptable value for the reliability indices and otherwise they will face up to compl...Since distribution sector is inherent into high amount of failures, distribution companies (DISCOs) are responsible of attaining an acceptable value for the reliability indices and otherwise they will face up to complaints. So they are usually obligated by regulators to invest on reliability improvement of network. But this investment on reliability is usually from the DISCO’s viewpoint and is also irrespective of customer satisfaction level. In other words, customers are not at the same level of sensitivity to interruptions but DISCO improves the reliability of network without considering the differences in importance degree of loads and their level of reliability requirement. On the other hand DISCOs attempt to reduce their investment costs as much as possible. This paper introduces a novel approach in the field of joint switch placement that can reduce the switch cost from the perspective of asset management policies. To this end, two switch placement plannings in different types of strategies are performed to compare their results. Firstly as witch placement is performed based on reducing the total energy not supplied (ENS) of the system. Then by revising the strategy, a fuzzy switch placement is performed from the DISCO’s point of view which just considers the total ENS of load points most sensitive to interruptions known as important or critical loads. Furthermore, by meeting the related constraints, the reliability of low sensitive customers is disregarded. This is a load importance based planning which can result in switch cost reduction relative to the amount achieved in previous strategy and implies the management of risks associated with reliability and respective constraint. Fuzzy method and new switching mechanism in fuzzy environment of network are implemented to modeling and controlling the risks associated to ENS of critical loads and also the ENS of system.展开更多
Recently, urban high temperature phenomenon has become a problem which results from human activities, the increase in energy consumption, and land-cover change in urban areas. As extremely hot weather caused by urban ...Recently, urban high temperature phenomenon has become a problem which results from human activities, the increase in energy consumption, and land-cover change in urban areas. As extremely hot weather caused by urban high temperature continues, demand for power is increased and results in the degradation of electricity reserves. The current trend in climate change, regardless of the summer and winter power demand, is likely to have much effect on the power demand. Thus, sensitivity to electricity consumption in urban areas due to climate change was researched. The results show that, 1） the basic unit of the sensitivity to electricity consumption in the target areas is 1.25-1.58W/（m2.℃）; 2） The maximum sensitivity is recorded at around 8：00 pm in the area crowded with commercial and business area. And in the business area, electricity consumption load is even from 9：00 am to 6：00 pm.展开更多
This paper performs an experimental study for inverse load reconstruction. By measuring and analyzing the load characteristics of different home and office electric devices, the author shows that a reconstruction of t...This paper performs an experimental study for inverse load reconstruction. By measuring and analyzing the load characteristics of different home and office electric devices, the author shows that a reconstruction of the individual power consumption of different loads from the total measurement of a single power meter is possible.展开更多
Calculated results of inertia moment of turbo-generator rotor can be quite different by methods used in load rejection tests. In view of fluctuation features of rotor speed rise curve during load rejection tests, the ...Calculated results of inertia moment of turbo-generator rotor can be quite different by methods used in load rejection tests. In view of fluctuation features of rotor speed rise curve during load rejection tests, the measurement principle of rotor inertia moment was expounded. Based on the measured data in load rejection tests for an imported type of domestic 300-MW generating unit, the rotor speed rise curve was fitted with three kinds of functions to get initial runup rate, but the obtained results differed a lot from each other. According to analysis on the mechanism of rotor speed rise, m=2 consecutive points averaging or FFT (Fast Fourier Transform) smoothing technology was introduced to process test data, and then the initial runup rate was determined by the method of linear fitting of rotor speed in the range of governing valve closing time. Although the obtained curves had a fluctuating shape, the results of rotor inertia moment for 50% and 100% load rejection tests were of good consistency.展开更多
The reasonability of the adopted capacity load ratio numerical value in urban power grid planning determines the economy of planning level yearly power grid.Too large capacity load ratio will result in the increasing ...The reasonability of the adopted capacity load ratio numerical value in urban power grid planning determines the economy of planning level yearly power grid.Too large capacity load ratio will result in the increasing investment in the early period of power grid construction, however, too small capacity load ratio will make the power grid have poor adaptability, affecting the power supply. Reasonably determining the adopted regional power grid capacity load ratio quantitative numerical value in planning has a strong guiding significance for constructing reliable and economic power grid and preventing power grid from excessive advance or lagging behind the load development. This paper, through the statistics and analysis of a certain regional power grid 2010-2012 three years＇ power grid daily load characteristics and the investment benefit evaluation of three years＇ 220KV power grid individual project, makes a preliminary analysis and puts forwards the specific advice on the reasonable values of power ~rid 35-220KV power transformation capacity load ratio.展开更多
ELD （economic load dispatch） problem is one of the essential issues in power system operation. The objective of solving ELD problem is to allocate the generation output of the committed generating units. The main co...ELD （economic load dispatch） problem is one of the essential issues in power system operation. The objective of solving ELD problem is to allocate the generation output of the committed generating units. The main contribution of this work is to solve the ELD problem concerned with daily load pattern. The proposed solution technique, developed based PSO （particle swarm optimization） algorithm, is applied to search for the optimal schedule of all generations units that can supply the required load demand at minimum fuel cost while satisfying all unit and system operational constraints. The performance of the developed methodology is demonstrated by case studies in test system of six-generation units. The results obtained from the PSO are compared to those achieved from other approaches, such as QP （quadratic programming）, and GA （genetic algorithm）.展开更多
A cogeneration plant can run at off-design due to change of load demand or ambient conditions. The cogeneration considered for this study is gas turbine based engine consists of variable stator vanes （VSVs） compress...A cogeneration plant can run at off-design due to change of load demand or ambient conditions. The cogeneration considered for this study is gas turbine based engine consists of variable stator vanes （VSVs） compressor that are re-staggered for loads greater than 50% to maintain the gas turbine exhaust gas temperature at the set value. In order to evaluate the exergetic performance of the cogeneration, exergy model of each cogeneration component is formulated. A 4.2 MW gas turbine based cogeneration plant is analysed for a wide range of part load operations including the effect of VSVs modulation. For loads less than 50%, the major exergy destruction contributors are the combustor and the loss with the stack gas. At full load, the exergy destructions in the combustor, turbine, heat recovery, compressor and the exergy loss with stack gas are 63.7, 14.1, 11.5, 5.7, and 4.9%, respectively. The corresponding first and second law cogeneration efficiencies are 78.5 and 45%, respectively. For comparison purpose both the first and second law efticiencies of each component are represented together. This analysis would help to identify the equipment where the potential for performance improvement is high, and trends which may aid in the design of future plants.展开更多
The induction motor system with fluctuating potential loads is a non-linear complex electro-mechanical system.With beam pumping motors as an example,this paper proposes a multiple factor non-linear mathematical model ...The induction motor system with fluctuating potential loads is a non-linear complex electro-mechanical system.With beam pumping motors as an example,this paper proposes a multiple factor non-linear mathematical model to study the operating performance of the induction motor system.This model consists of non-linear time varying electromagnetic field equations,mechanical wave equations of sucker rods and non-linear coupling equation of reducer and four-bar linkage.The equations are numerically solved by combining time-step finite element method(TS-FEM),finite difference method(FDM),a linear dimension reduction method and the Newton-Raphson method.Simulation results,which are validated by experiments,reveal the influence of the fluctuating potential load on magnetic field distributions,stator and rotor currents,the input power and the power factor.The model and simulation results provide theoretical and technical supports for subsequent researches on model simplification and energy saving technologies.展开更多
文摘We take the contribution of all valence electrons into consideration and propose a new valence electrons equilibration method to calculate the equalized electronegativity including molecular electronegativity, group electronegativity, and atomic charge. The ionization potential of alkanes and mono-substituted alkanes, the chemical shift of 1H NMR, and the gas phase proton affinity of aliphatic amines, alcohols, and ethers were estimated. All the expressions have good correlations. Moreover, the Sanderson method and Bratsch method were modified on the basis of the valence electrons equilibration theory. The modified Sanderson method and modified Bratsch method are more effective than their original methods to estimate these properties.
基金Supported by the Science Fund of State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body under Grant No.60870005the National Natural Science Foundation of China under Grant No.10872065
文摘The electro-elastic interaction between a piezoelectric screw dislocation and an elliptical piezoelectric inhomogeneity, which contains an electrically conductive confocal elliptical rigid core under remote anti-plane shear stresses and in-plane electrical load is dealt with. The anaJytical solutions to the elastic field and the electric field, the interracial stress fields of inhomogeneity and matrix under longitudinal shear and the image force acting on the dislocation are derived by means of complex method. The effect of material properties and geometric configurations of the rigid core on interracial stresses generated by a remote uniform load, rigid core and material electroelastic properties on the image force is discussed.
基金The project supported by National Natural Science Foundation of China under Grant No. 10374040. The authors thank Dr. Meng-Tao Sun （Department of Chemical Physics, Lund University, Sweden） for stimulating discussions.
文摘The first fluorine-substituted hexabenzocoronene has been synthesized and its electronic structure and optical properties have been reported [Q. Zhang, et al., Org. Lett. 7 （2005） 5019]. In this letter, the electronic structure and excited state properties of the fluorine-substituted hexabenzocoronene are studied with quantum chemistry method as well as the transition and the charge difference densities. The transition densities show the orientations and strength of the dipole moments and the charge difference densities reveal the orientation and results of the intramolecular charge transfer. The calculated transition energies and oscillator strengths are consistent with the experimental data, and the theoretical results of transition and charge difference densities are valuable to understanding the excited state properties of the fluorine-substituted hexabenzocoronene.
文摘Since distribution sector is inherent into high amount of failures, distribution companies (DISCOs) are responsible of attaining an acceptable value for the reliability indices and otherwise they will face up to complaints. So they are usually obligated by regulators to invest on reliability improvement of network. But this investment on reliability is usually from the DISCO’s viewpoint and is also irrespective of customer satisfaction level. In other words, customers are not at the same level of sensitivity to interruptions but DISCO improves the reliability of network without considering the differences in importance degree of loads and their level of reliability requirement. On the other hand DISCOs attempt to reduce their investment costs as much as possible. This paper introduces a novel approach in the field of joint switch placement that can reduce the switch cost from the perspective of asset management policies. To this end, two switch placement plannings in different types of strategies are performed to compare their results. Firstly as witch placement is performed based on reducing the total energy not supplied (ENS) of the system. Then by revising the strategy, a fuzzy switch placement is performed from the DISCO’s point of view which just considers the total ENS of load points most sensitive to interruptions known as important or critical loads. Furthermore, by meeting the related constraints, the reliability of low sensitive customers is disregarded. This is a load importance based planning which can result in switch cost reduction relative to the amount achieved in previous strategy and implies the management of risks associated with reliability and respective constraint. Fuzzy method and new switching mechanism in fuzzy environment of network are implemented to modeling and controlling the risks associated to ENS of critical loads and also the ENS of system.
基金Project(NRF-20110030631) supported by the National Research Foundation of Korea Grant funded by the Korean Government
文摘Recently, urban high temperature phenomenon has become a problem which results from human activities, the increase in energy consumption, and land-cover change in urban areas. As extremely hot weather caused by urban high temperature continues, demand for power is increased and results in the degradation of electricity reserves. The current trend in climate change, regardless of the summer and winter power demand, is likely to have much effect on the power demand. Thus, sensitivity to electricity consumption in urban areas due to climate change was researched. The results show that, 1） the basic unit of the sensitivity to electricity consumption in the target areas is 1.25-1.58W/（m2.℃）; 2） The maximum sensitivity is recorded at around 8：00 pm in the area crowded with commercial and business area. And in the business area, electricity consumption load is even from 9：00 am to 6：00 pm.
文摘This paper performs an experimental study for inverse load reconstruction. By measuring and analyzing the load characteristics of different home and office electric devices, the author shows that a reconstruction of the individual power consumption of different loads from the total measurement of a single power meter is possible.
文摘Calculated results of inertia moment of turbo-generator rotor can be quite different by methods used in load rejection tests. In view of fluctuation features of rotor speed rise curve during load rejection tests, the measurement principle of rotor inertia moment was expounded. Based on the measured data in load rejection tests for an imported type of domestic 300-MW generating unit, the rotor speed rise curve was fitted with three kinds of functions to get initial runup rate, but the obtained results differed a lot from each other. According to analysis on the mechanism of rotor speed rise, m=2 consecutive points averaging or FFT (Fast Fourier Transform) smoothing technology was introduced to process test data, and then the initial runup rate was determined by the method of linear fitting of rotor speed in the range of governing valve closing time. Although the obtained curves had a fluctuating shape, the results of rotor inertia moment for 50% and 100% load rejection tests were of good consistency.
文摘The reasonability of the adopted capacity load ratio numerical value in urban power grid planning determines the economy of planning level yearly power grid.Too large capacity load ratio will result in the increasing investment in the early period of power grid construction, however, too small capacity load ratio will make the power grid have poor adaptability, affecting the power supply. Reasonably determining the adopted regional power grid capacity load ratio quantitative numerical value in planning has a strong guiding significance for constructing reliable and economic power grid and preventing power grid from excessive advance or lagging behind the load development. This paper, through the statistics and analysis of a certain regional power grid 2010-2012 three years＇ power grid daily load characteristics and the investment benefit evaluation of three years＇ 220KV power grid individual project, makes a preliminary analysis and puts forwards the specific advice on the reasonable values of power ~rid 35-220KV power transformation capacity load ratio.
文摘ELD （economic load dispatch） problem is one of the essential issues in power system operation. The objective of solving ELD problem is to allocate the generation output of the committed generating units. The main contribution of this work is to solve the ELD problem concerned with daily load pattern. The proposed solution technique, developed based PSO （particle swarm optimization） algorithm, is applied to search for the optimal schedule of all generations units that can supply the required load demand at minimum fuel cost while satisfying all unit and system operational constraints. The performance of the developed methodology is demonstrated by case studies in test system of six-generation units. The results obtained from the PSO are compared to those achieved from other approaches, such as QP （quadratic programming）, and GA （genetic algorithm）.
文摘A cogeneration plant can run at off-design due to change of load demand or ambient conditions. The cogeneration considered for this study is gas turbine based engine consists of variable stator vanes （VSVs） compressor that are re-staggered for loads greater than 50% to maintain the gas turbine exhaust gas temperature at the set value. In order to evaluate the exergetic performance of the cogeneration, exergy model of each cogeneration component is formulated. A 4.2 MW gas turbine based cogeneration plant is analysed for a wide range of part load operations including the effect of VSVs modulation. For loads less than 50%, the major exergy destruction contributors are the combustor and the loss with the stack gas. At full load, the exergy destructions in the combustor, turbine, heat recovery, compressor and the exergy loss with stack gas are 63.7, 14.1, 11.5, 5.7, and 4.9%, respectively. The corresponding first and second law cogeneration efficiencies are 78.5 and 45%, respectively. For comparison purpose both the first and second law efticiencies of each component are represented together. This analysis would help to identify the equipment where the potential for performance improvement is high, and trends which may aid in the design of future plants.
基金supported by the National Natural Science Foundation of China(Grant No.51307050)
文摘The induction motor system with fluctuating potential loads is a non-linear complex electro-mechanical system.With beam pumping motors as an example,this paper proposes a multiple factor non-linear mathematical model to study the operating performance of the induction motor system.This model consists of non-linear time varying electromagnetic field equations,mechanical wave equations of sucker rods and non-linear coupling equation of reducer and four-bar linkage.The equations are numerically solved by combining time-step finite element method(TS-FEM),finite difference method(FDM),a linear dimension reduction method and the Newton-Raphson method.Simulation results,which are validated by experiments,reveal the influence of the fluctuating potential load on magnetic field distributions,stator and rotor currents,the input power and the power factor.The model and simulation results provide theoretical and technical supports for subsequent researches on model simplification and energy saving technologies.
