检索结果-南通市图书馆

Research on dual-stator winding multi-phase high-speed induction generator with rectifier load

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2008年第6期51卷 683-692页

作者： WANG XiangHeng1.& WU XinZhen2 1.Department of Electrical engineering, Tsinghua {1., Beijing 1.0084, china 2 Department of Electrical engineering, qingdao {1., qingdao 266071, china 1. Department of Electrical engineering Tsinghua University Beijing 100084 China 2. Department of Electrical engineering Qingdao University Qingdao 266071 China

Based on analysis and calculation of the relation between current harmonics and MMF harmonics in the dual-stator winding multi-phase high-speed induction gen-erator with a rectifier load, a new idea, which divides the generator system into two sub-systems to be analyzed individually, is presented. For the sub-system of the 1.-phase power winding with a rectifier load, the loop current method is used to establish network equation set in terms of the network graph theory. The numerical stability problem is solved by alternating use of fixed time-step and varied time-step, and the voltage and current with their fundamental components of the power winding are obtained. For the other sub-system of the induction generator with dual-stator winding and solid cage rotor, the electromagnetic field analysis method and the multi-variable optimization approach are combined to get the con-trol winding current and stator frequency. Calculated results well match experiment results, indicating that the new proposed method is of effectiveness and high ac-curacy.

关键词： dual-stator winding induction generator rectifier load MMF analysis loop current method finite element method optimization approach

A thin-layer spectroelectrochemical study of 3,3',5,5'-tetramethylbenzidine at SnO_2:F film optically transparent electrode

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2004年第4期47卷 267-275页

作者： JIAO Kui1. YANG Tao2 & NIU Shuyan1.2 1. College of Chemistry and Molecular engineering, {1. university of Science and Technology, {1. 266042, china 2. College of Chemistry and Chemical engineering, ocean university of china, {1. 266003, china Correspondence should be addressed to Jiao Kui 1. College of Chemistry and Molecular engineering Qingdao University of Science and Technology 266042 Qingdao China 2. College of Chemistry and Chemical engineering Ocean University of China 266003 Qingdao China

The electrooxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) is dependent on the pH value of Britton-Robinson (B-R) buffer solution. In this work, the electrooxidation behavior of TMB was investigated with a SnO2:F film optically transparent thin-layer spectroelectrochemical cell. TMB underwent one two-electron electrooxidation process in the pH range from 2.0 to < 4.0, and two successive one-electron electrooxidation processes in the pH range from 4.0 to < 7.0 in the B-R buffer solution. At pH 6.5, the electrooxidative product of TMB generated a subsequent chemical reaction to yield an azo compound. Several spectroelectrochemical techniques, such as thin-layer cyclic voltammetry, thin-layer cyclic voltabsorptometry, thin-layer potential-controlled electrolysis absorptometry, thin-layer single-potential-step chronoabsorptometry, thin-layer dou-ble-potential-step chronoabsorptometry, thin-layer single-potential-step open-circuit relaxation chronoabsorptometry, were applied to this investigation. The formal potential E0’ and the electron transfer number corresponding to the electrooxidation of TMB in B-R buffer solution, and the reaction rate constant of the subsequent chemical reaction were determined.

关键词： 3,3′,5,5′-tetramethylbenzidine tin oxide film optically transparent electrode thin-layer spectroelectro-chemistry electrooxidation

Analysis on cohesive crack opening displacement considering the strain softening effect

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2006年第1期49卷 88-101页

作者： WANG Limin1. XU Shilang2 & ZHAO Xiqiang3 1. Mechanics Department, Shandong university of Technology, Zibo 255049, {1. 2. Civil engineering Department, Dalian university of Technology, Dalian 1.6024, {1. 3. Mathematics Department, ocean university of china, qingdao 266071, {1. Mechanics Department Shandong University of Technology Zibo 255049 China Civil engineering Department Dalian University of Technology Dalian 116024 China Mathematics Department Ocean University of China Qingdao 266071 China

In order to investigate the crack propagation in quasi-brittle materials like rock, ceramic and concrete, Hillerborg and his co-researchers abstracted the fracture process zone in front of a stress free crack in terms of a “fictitious crack zone”. On the fictitious crack zone, cohesive stresses distribute following a given softening relationship of stress vs. crack opening. Based on the polynomial or power series expression of cohesive crack opening displacement, the relationship of the cohesive stress vs. the crack opening displacement is established using elastic theory and integral equation, and some unknown physics variables are obtained using variation approach. The calculation results gained in this paper are close to the experimentally test ones.

关键词： cohesive crack, softening, dissipation work, variation approach.

Boundary conditions for the bending of a piezoelectric beam

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2008年第7期51卷 847-856页

作者： GAO Yang1. XU SiPeng2 & ZHAO BaoSheng3 1.College of Science, china Agricultural {1., Beijing 1.0083, china 2 College of engineering, ocean university of china, qingdao 266071, china 3 School of Mechanical engineering, {1. of Science and Technology Liaoning, Anshan 1.4044, china 1. College of Science China Agricultural University Beijing 100083 China 2. College of engineering Ocean University of China Qingdao 266071 China 3. School of Mechanical engineering University of Science and Technology Liaoning Anshan 114044 China

For beam bending in transversely isotropic piezoelectric media, the reciprocal theorem and the general solution of piezoelasticity are applied in a novel way to obtain the appropriate stress and mixed boundary conditions accurate to all orders for the beam of general edge geometry and loadings. By generalizing the method developed by Gregory and Wan, a set of necessary conditions on the edge-data for the existence of a rapidly decaying solution is established. The prescribed edge-data of the beam must satisfy these conditions in order that they could generate a decaying state within the beam. When stress and mixed conditions are imposed on the beam edge, these decaying state conditions for the case of bending deformation of piezoelectric beam are derived explicitly. They are then used for the correct formulation of boundary conditions for the beam theory solution (or the interior solution). Besides, an analytical solution of elastic beam is formulated to verify validity of our boundary conditions. For the stress data, our boundary conditions coincide with those obtained in conventional forms of beam theories. More importantly, the appropriate boundary conditions with two sets of mixed edge-data are obtained for the first time.

关键词： boundary conditions beam bending piezoelectric media decaying states regular states

Mixed boundary conditions for piezoelectric plates

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2009年第5期52卷 755-761页

作者： GAO Yang 1.,XU SiPeng 2 &ZHAO BaoSheng 3 1.ollege of Science,china Agricultural {1.,Beijing 1.0083,china 2College of engineering,ocean university of china,qingdao 266071.china 3 School of Mechanical engineering,{1. of Science and Technology of Liaoning,Anshan 1.4044,china College of Science China Agricultural University Beijing 100083 China College of engineering Ocean University of China Qingdao 266071 China School of Mechanical engineering University of Science and Technology of Liaoning Anshan 114044 China

For plate bending and stretching problems in piezoelectric materials,the reciprocal theorem and the general solution of piezoelasticity are applied in a novel way to obtain the appropriate mixed boundary conditions accurate to all order.A decay analysis technique is used to establish necessary conditions that the prescribed data on the edge of the plate must satisfy in order that it should generate a decaying state within the *** the case of axisymmetric bending and stretching of a circular plate,these decaying state conditions are obtained explicitly for the first time when the mixed conditions are imposed on the plate *** are then used for the correct formulation of boundary conditions for the interior solution.

关键词： boundary conditions piezoelectric plates mixed data bending problems stretching problems

Warming in Arctic intermediate and deep waters around Chukchi Plateau and its adjacent regions in 1.99

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2005年第8期48卷 1312-1320页

作者： ZHAO Jinping1. GAO Guoping2 & JIAO Yutian1.1. First Institute of oceanography, State oceanic Administration, qingdao 266061. china 2. ocean university of china, qingdao 266003, china 1. First Institute of oceanography State Oceanic Administration 266061 Qingdao China 2. ocean university of china 266003 Qingdao China

Based on the data measured during Arctic scientific expedition of china in 1.99, the characteristics of temperature and salinity distributions around the Chukchi Plateau and its ad-jacent regions have been studied. It was found that the intermediate water with temperature higher than 0.5℃ existed in all parts of a 640 km section with a maximum temperature of 0.85℃ indicating a strong signal of the warming in Arctic Intermediate Water in 1.99. Two important phenomena are described in this paper. First, the temperature of warm water was horizontally nonuniform. In the area of Chukchi Plateau, the temperature was higher, the layer of warm water was thicker and the depth of the warm water core was shallower than those in the area of con-tinental slope. The horizontal nonuniformity of the temperature distribution of warming water im-plies that the upward heat flux should also be nonuniform, thus exerting different effects on sea ice thickness, ice extent, and air-sea heat exchange. The mechanism to generate higher tem-perature in the plateau region was the bypassing of current around the plateau area caused by the special local topography, which restricted water exchange across the plateau and conserved heat in the water body. Second, the deep water down to 1.00 m was also warming with a tem-perature increase of 0.2℃. The warming in deep water reflects the occurrence of complicated heat redistribution processes in the intermediate water, which altered the thermal structure in the upper 1.00 m. The warming data embody the obvious impact of global climate change on the Arctic {1. and further studies are wanted.

关键词： Chukchi Plateau, Arctic ocean, warming in intermediate water, warming in deep water.

Bubble size distribution in surface wave breaking entraining process

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2007年第11期50卷 1754-1760页

作者： HAN Lei1.2 & YUAN YeLi2 1.Department of ocean Environment, {1., qingdao 266003, china 2 The First Institute of oceanography, State ocean Administration, qingdao 266061. china 1. Department of ocean Environment Ocean University of China Qingdao 266003 China 2. The First Institute of oceanography State Ocean Administration Qingdao 266061 China

From the similarity theorem, an expression of bubble population is derived as a function of the air en-trainment rate, the turbulent kinetic energy (TKE) spectrum density and the surface tension. The bubble size spectrum that we obtain has a dependence of a?2.5+nd on the bubble radius, in which nd is positive and dependent on the form of TKE spectrum within the viscous dissipation range. To relate the bubble population with wave parameters, an expression about the air entrainment rate is deduced by intro-ducing two statistical relations to wave breaking. The bubble population vertical distribution is also derived, based on two assumptions from two typical observation results.

关键词： wave breaking,bubble cloud,bubble size spectrum

Study on the two and three-parameter working stability regions of 3Y-TZP suspension

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2006年第5期49卷 547-568页

作者： CHEN Youqiang1. 2, ZHANG Xinni3, CHEN Sha’ou3 & QI Ping3 1. Department of Chemistry, qingdao {1., qingdao 266071, china 2. Department of Chemistry, Tsinghua {1., Beijing 1.0084, china 3. Department of Physics, qingdao {1., qingdao 266071, china 1. Department of Chemistry Qingdao University Qingdao 266071 China 2. Department of Chemistry Tsinghua University Beijing 100084 China 3. Department of Physics Qingdao University Qingdao 266071 China

We determined the variation tendency of viscosity (η) at various solids load- ing (α) for 3Y-TZP suspension as a function of dispersant concentration (Cw) using vis- cosity measurement, measured the diameter of particles as a function of Cw in very dilute suspension using light scattering method, and obtained the surface features of the sedi- ment of suspension with different Cw using SEM. We also discussed the influence of the microstructure of adsorbed polymer layers on particles and their interactions in the dis- persing medium on the stability of suspension. Then two different stable states and two different unstable states for 3Y-TZP suspension were given. Accordingly, the (Cw, η), (Cw, α), and (α, η) two-parameter, and (Cw, α, η) three-parameter stability maps were con- structed. Based on the DLVO theory calculations, the dispersant concentration, particle distance (r), and interparticle potential energy (VT) maps with various solids loading for 3Y-TZP aqueous suspension were also constructed. In (Cw, r) two-parameter coordinate system, the stable motion region map for particles was established. The Cw, α, and VT,max (the highest potential energy) surface of the potential barrier map was obtained through calculation and simulation on the basis of the surfaces of Cw, r, VT maps introduced above. The (Cw, α) two-parameter stability map was then obtained from the Cw, α, VT,max map. The results showed that this theoretical map can qualitatively prove the experimentally obtained results—the existence of different dispersed states of particles in suspension system and the variation tendency of suspension stability with changing each parame- ter—were reasonable.

关键词： 3Y-TZP, suspension, stability, DLVO theory, interparticle potential energy.

Meso-scale circulation at the intermediate-depth east of Mindanao observed by Argo profiling floats

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2010年第3期53卷 432-440页

作者： ZHOU Hui1. YUAN DongLiang1. GUO PeiFang2, SHI MaoChong2 & ZHANG QiLong 1.Key Laboratory of ocean Circulation and Wave Studies, Chinese Academy of Sciences, {1. 266071, china 2 Physical oceanography Laboratory, ocean university of china, {1. 2661.0, china 1. Key Laboratory of ocean Circulation and Wave Studies Chinese Academy of Sciences Qingdao 266071 China2. Physical Oceanography Laboratory Ocean University of China Qingdao 266100 China

The meso-scale circulation at the intermediate depth east of Mindanao is studied using Argo profiling floats observations. The trajectories and the parking-depth velocities of Argo floats show that the intermediate-depth circulation east of Mindanao contains significant meso-scale features that are highly variable both in space and in time. Both cyclonic and anticyclonic eddies at the intermediate depth (1.00–2000 m) are indicated by the trajectories east of Mindanao. The mean tangential velocities of these eddies are about 1. cm/s at 2000 m and over 20 cm/s at 1.00 m, which indicates that the geostrophic calculation may contain large errors due to the vigorous eddy activity at the reference levels. The analyses also suggest that these eddies might play an important role in mass and vorticity balances of the intermediate-depth circulation east of Mindanao.

关键词： Mindanao Current intermediate-depth circulation meso-scale eddy Argo profiling float