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Evaluating the effect of dislocation on the photovoltaic performance of metamorphic tandem solar cells

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中国科学：技术科学英文版 2010年第9期53卷 2569-2574页

作者： ZHANG Han1,CHEN NuoFu2,3,WANG Yu1,ZHANG XingWang1,YIN ZhiGang1,SHI HuiWei1,WANG YanSuo1,HUANG TianMao1,BAI YiMing2 & FU Zhen11 Key Laboratory of Semiconductor Materials Science,Institute of Semiconductors,Chinese Academy of Sciences,P.O.Box 912,beijing 100083,china 2 school of renewable energy engineering,north china electric power university,beijing 102206,china 3 State Key Laboratory of Silicon Materials,Zhejiang university,Hangzhou 310027,china 1. Key Laboratory of Semiconductor Materials Science Institute of Semiconductors Chinese Academy of Sciences P.O. Box 912 Beijing 100083 China2. School of Renewable Energy Engineering North China Electric Power University Beijing 102206 China3. State Key Laboratory of Silicon Materials Zhejiang University Hangzhou 310027 China

The photovoltaic conversion efficiency for monolithic GaInP/GaInAs/Ge triple-junction cell with various bandgap combination (300 suns,AM1.5d) was theoretically *** impressive improvement on conversion efficiency was observed for a bandgap combination of 1.708,1.194,and 0.67 eV.A theoretical investigation was carried out on the effect of dislocation on the metamorphic structure’s efficiency by regarding dislocation as minority-carrier recombination *** results showed that only when dislocation density was less than 1.6×106 cm-2,can this metamorphic combination exhibit its efficiency advantage over the fully-matched *** addition,we also briefly evaluated the lattice misfit dependence of the dislocation density for a group of metamorphic triple-junction system,and used it as guidance for the choice of the proper cell structure.

关键词： tandem solar cell theoretical efficiency dislocation buffer layers

Numerical simulation of ski-jump jet motion using lattice Boltzmann method

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Science china(Technological Sciences) 2011年第S1期54卷 72-75页

作者： ZHANG Hua 1 &ZHANG XiaoDong 2 1 school of renewable energy,north china electric power university,beijing 102206,china 2 school of energy power and Mechanical engineering,north china electric power university,beijing 102206,china 1. school of renewable energy North China Electric Power University Beijing 102206 China 2. school of energy power and Mechanical engineering North China Electric Power University Beijing 102206 China

Based on the lattice Boltzmann method,a lattice Boltzmann(LB) model of the ski-jump jet two-phase flow is developed first and the corresponding boundary conditions are studied.A simple case study of a droplet horizontal movement calculation is carried out to test and verify the model,where level set method is used to track and reconstruct the moving droplet free surface. Then,we numerically simulate a two dimensional flow field of the ski-jump jet with the LB model,derive the moving surface and velocity vector field of the jet *** simulation results are very consistent with the physical *** effectiveness and reliability of the model are demonstrated by the numerical examples.

关键词： ski-jump jet droplet lattice Boltzmann method interface numerical simulation

Reduced analysis and confirmatory research on co-adaptability theoretical solution to conflicting events in construction engineering projects

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Science china(Technological Sciences) 2010年第2期53卷 480-485页

作者： HOU XueLiang1 , LU Mei2 & WANG Kai3 1 school of Business Administration, north china electric power university, beijing 102206, china 2 Department of Construction Management, Tsinghua university, beijing 100084, china 3 College of Management, beijing Jiaotong university, beijing 100084, china 1. school of Business Administration North China Electric Power University Beijing 102206 China2. Department of Construction Management Tsinghua University Beijing 100084 China3. College of Management Beijing Jiaotong University Beijing 100084 China

The co-adaptability theoretical solution to conflicting events in construction engineering projects has three problems. First, the transformation of constraint conditions of theoretical solution is very difficult in practical engineering applications; second, some coefficients are difficult to be determined; third, there are overfull circular arithmetic operations involved in it. To resolve these problems, a new method to reduce the theoretical solution complications is proposed. By analyzing the operating mechanism of theoretical solution model, redundancies in the theoretical solution can be eliminated, and the ISM mapping with the co-adaptability solution can be set up. Based on this approach, a procedure to solve practical conflicting events in construction projects is established by replacing characteristic variables with mathematic variables. The research results show that the procedure can replace the co-adaptability theoretical solution effectively and solve practical conflicting events in construction projects.

关键词： construction project conflict theoretical solution reduced analysis ISM confirmatory research

Resonance suppression and electromagnetic shielding effectiveness improvement of an apertured rectangular cavity by using wall losses

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Chinese Physics B 2013年第8期22卷 404-409页

作者：焦重庆朱弘钊 State Key Laboratory of Alternate electrical power System with renewable energy Sources North China Electric Power University

The cavity-mode resonance effect could result in significant degradation of the shielding effectiveness （SE） of a shielding enclosure around its resonance frequencies. In this paper, the influence of coated wall loss on the suppression of the resonance effect is investigated. For this purpose, an equivalent circuit model is employed to analyze the SE of an apertured rectangular cavity coated with an inside layer of resistive material. The model is developed by extending Robinson＇s equivalent circuit model through incorporating the effect of the wall loss into both the propagation constant and the characteristic impedance of the waveguide. Calculation results show that the wall loss could lead to great improvement on the SE for frequencies near the resonance but almost no effect on the SE for frequencies far away from the resonance.

关键词： electromagnetic shielding rectangular cavity wall losses resonance effect

Ecological hydraulic radius model to calculate instream flow requirements for transporting sediment in the western water transfer region

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Science china(Technological Sciences) 2009年第11期52卷 3401-3405页

作者： MEN BaoHui1 & LIU ChangMing2 1 renewable energy Institute, north china electric power university, beijing 102206, china 2 Key Laboratory of Water Cycle and Related Land Surface Process, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, beijing 100101, china 1. renewable energy Institute North China Electric Power University Beijing 102206 China 2. Key Laboratory of Water Cycle and Related Land Surface Process Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China

Transporting sediment is a natural function of the river. To maintain the normal evolution of the river certain amount of water flow is required, which is called the instream flow requirements for transporting sediment (IFRTS). We defined the permitting flow velocity by the conception of IFRTS, and also put forward the ecological hydraulic radius model (EHRM) to estimate IFRTS. The calculating process of EHRM is explained by the example of Daofu Hydrological Station on Xianshui branch of Yalong River in the west line first-stage construction of South-north Water Transfer Project. The result shows that the IFRTS occupied 29.7%―59.5% of annual mean discharge in flood season, the average of IFRTS was about 100.2 m3/s during 1966―1987, it is close to the IFRTS 90 m3/s calculated by IFRTS conception. Hence, it is feasible to use EHRM to calculate IFRTS.

关键词： ecological hydraulic radius model (EHRM) instream flow requirements for transporting sediment (IFRTS) permitting flow velocity ecological hydraulic radius for transporting sediment

Mission planning of the flying robot for powerline inspection

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Progress in Natural Science:Materials International 2009年第10期19卷 1357-1363页

作者： Chang’an Liu,Lei Wang,Chunyang Liu school of Computer Science and Technology,north china electric power university,beijing 102206,china [a]school of Computer Science and Technology North China Electric Power University Beijing 102206 China

Mission planning is an important step in the powerline inspection flying *** deal with the tasks of powerline flying robots,a flying robot mission-planning system is established based on the unmanned mini-helicopter model described in this *** can deter-mine the best checking order,the optimal space path and the best flight *** objective function and the constraints are described by establishing the mathematical model,and the mission-planning system is decomposed by using the tiered ***-agent technology is chosen to solve the mission-planning ***,simulation is conducted to verify that the mission-planning system is feasible and efficient.

关键词： powerline inspection flying robot Mission planning Multi-agent technology

Current distribution and stability of LTS/HTS hybrid superconducting conductors

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Science china(Technological Sciences) 2010年第7期53卷 2000-2007页

作者： GUAN XiaoJin1,2, WANG YinShun1 & ZHOU WeiWei3 1 Key Laboratory of HV and EMC beijing, north china electric power university, beijing 102206, china 2 Department of Physics, Baoding university, Baoding 071000, china 3 Institute of electrical engineering, Chinese Academy of Sciences, beijing 100190, china 1. Key Laboratory of HV and EMC beijing North China Electric Power University Beijing 102206 China2. Department of Physics Baoding University Baoding 071000 China3. Institute of Electrical Engineering Chinese Academy of Sciences Beijing 100190 China

Current distribution and stability of a hybrid LTS/HTS superconductor, consisting of multifilamentary NbTi/Cu and Bi2223/Ag tapes, were numerically analyzed according to power-law models. The results showed that most of current passed through the LTS and the current increased in the HTS with temperature rise when the transport current was below the critical current of the hybrid conductor. The quench propagation velocity of the hybrid conductor was smaller but its minimum quench energy was larger than those of LTS conductors, indicating that the stability of the hybrid superconducting conductor was effectively improved and a high engineering current density was simultaneously achieved. Finally, a hybrid sample, made by soldering Bi2223/Ag tape onto NbTi/Cu conductor, was prepared and tested successfully at helium temperature. The experimental results qualitatively agreed with the simulated ones.

关键词： distribution hybrid conductor minimum quench energy quench propagation velocity n value stability

Application of polynomial chaos on numerical simulation of stochastic cavity flow

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Science china(Technological Sciences) 2010年第10期53卷 2853-2861页

作者： WANG XiaoDong1,2 & KANG Shun1 1 Key Laboratory of Condition Monitoring and Control for power Plant Equipment, Ministry of Education, school of energy power and Mechanical engineering, north china electric power university, beijing 102206, china 2 Department of Mechanical engineering, Vrije Universiteit Brussel, Brussels 1050, Belgium 1. Key Laboratory of Condition Monitoring and Control for power Plant Equipment Ministry of Education School of Energy Power and Mechanical Engineering North China Electric Power University Beijing 102206 China2. Department of Mechanical Engineering Vrije Universiteit Brussel Brussels 1050 Belgium

In present paper,the mathematic background of intrusive polynomial chaos (IPC) method and coupling process with one dimension Euler equation were introduced. The IPC method was implemented for the 2D compressible stochastic Navier-Stokes equations to simulate the non-deterministic behavior of a lid driven cavity flow under the influence of uncertainties. The driven velocity and fluid viscosity were supposed respectively to be the uncertain variable which has Gaussian probability distribution. Based on the validation with benchmark results,discussions were mainly focused on the statistic properties of velocity distribution. The results indicated the effect of IPC method on the simulation of propagation of uncertainty in the flow field. For the simulated results of 2D cavity flow,influence of the driven velocity uncertainty is larger than that of viscosity.

关键词： non-deterministic polynomial chaos numerical simulation lid driven cavity flow

A cross-association model for CO_2-methanol and CO_2-ethanol mixtures

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Science china Chemistry 2010年第6期53卷 1438-1444页

作者： FU Dong,YANG Zhuang,LU JianYi & LIU JianMin school of Environmental Science and engineering,north china electric power university,Baoding 071003,china 1. school of Environmental Science and engineering North China Electric Power University Baoding 071003 China

A cross-association model was proposed for CO2-alcohol mixtures based on the statistical associating fluid theory (SAFT).CO2 was treated as a pseudo-associating molecule and both the self-association between alcohol hydroxyls and the cross-association between CO2 and alcohol hydroxyls were *** equilibrium properties from low temperature-pressure to high temperature-pressure were investigated using this *** calculated p-x and p-p diagrams of CO2-methanol and CO2-ethanol mixtures agreed with the experimental *** results showed that when the cross-association was taken into account for Helmholtz free energy,the calculated equilibrium properties could be significantly improved,and the error prediction of the three phase equilibria and triple points in low temperature regions could be avoided.

关键词： CO2-methanol CO2-ethanol cross-association SAFT phase equilibria