检索结果-南通市图书馆

Boundary conditions for the bending of a piezoelectric beam

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(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 {2., beijing 100083, china 2.College of engineering, Ocean {2. of china, Qingdao 2.6071, china 3 school of Mechanical engineering, {2. of science and Technology Liaoning, Anshan 114044, 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

A New Genetic Algorithm Based on Niche Technique and Local Search Method

在线全文

学校读者我要写书评

暂无评论

Journal of university of science and Technology {2. 2001年第1期8卷 63-68页

作者： Jinwu Xu, Jiwen Liu Mechanical engineering school, {2. of science and Technology beijing, beijing 100083, china Univ Sci & Technol beijing Sch Mech Engn Beijing 100083 Peoples R China

The genetic algorithm has been widely used in many fields as an easy robust global search and optimization method. In this paper, a new generic algorithm based on niche technique and local search method is presented under the consideration of inadequacies of the simple genetic algorithm. In order to prove the adaptability and validity of the improved genetic algorithm, optimization problems of multimodal functions with equal peaks, unequal peaks and complicated peak distribution are discussed. The simulation results show that compared to other niching methods, this improved genetic algorithm has obvious potential on many respects, such as convergence speed, solution accuracy, ability of global optimization, etc.

关键词： genetic algorithm (GA) niche technique local search method

Microstructural Features During Strain Induced Ferrite Transformation in 08 and 2.Mn Steels

在线全文

学校读者我要写书评

暂无评论

Journal of university of science and Technology {2. 2001年第2期8卷 105-110页

作者： Ping Yang, Feng-e Cui, Fuming Wang (Materials science and engineering {2., university of science and Technology beijing, beijing 100083, china) (Metallurgy {2., university of science and Technology beijing, beijing 100083, china) Univ Sci & Technol beijing Mat Sci & Engn Sch Beijing 100083 Peoples R China Univ Sci & Technol beijing Met Sch Beijing 100083 Peoples R China

The microstructure evolution during strain induced ferrite transformation was followed in thermal-simulation tests of clean 08 and 2.Mn steels. The influences of carbon equivalence and initial austenite grain size on ferrite grain refinement and the volume fraction of ferrite during straining were inspected. The results revealed that the accelerating effect of ferrite transformation by strain was increased as the carbon equivalence decreased. However, finer ferrite grains were obtained at higher carbon content. At strain of similar to1.5 ferrite grains less than 3 mum and 2.mum can be obtained in 08 and 2.Mn steels respectively. Whereas the ferrite grain refinement in 08 steel was due to both effects of strain induced transformation and ferrite dynamic recrystallization, that in 2.Mn was mainly due to strain induced transformation. Heavy strain can produce fine ferrite grains in coarse austenite grained 08 steel, but it would lead to band microstructure in coarse austenite grained 2.Mn.

关键词： clean carbon steel strain induced transformation grain refinement ferrite dynamic recrystallization

Relationship between Low Temperature Toughness and Microstructure in Low Activation Fe-Cr-Mn(W,V)Steel for Fusion Reactors

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 1999年第2期13卷 111-115页

作者： Benfu Hu Chengchang jia(Material science and engineering {2., university of science and Technology beijing, beijing 100083, china) Material science and engineering {2. University of Science and Technology Beijing Beijing 100083 China

Fe-Cr-Mn (W, V) austenite steel was researched in order to supply a theory base for the first wall materials of fusion *** included vacuum melting, forging, annealing, solution treatment, Charpy impact tests and microstructure observation. Theresults show that the imped value decreases with the test temperature decreasing. In this system, there is ductile/brittle transition. Themechanism of this decrease of the impact value is considered to be due to γ - ε transformation in sub-stable austenite steel and stoppingoverlapping sacking fault by grain boundaries in stable austenite steel.

关键词： fusion reactor first wall materials low temperature toughness Fe-Cr-Mn system

Synchronization of Digital Chaos in Secure Communication Systems

在线全文

学校读者我要写书评

暂无评论

Journal of university of science and Technology {2. 2001年第4期8卷 299-305页

作者： Geng Zhao, Deling Zheng, ShaojunHuang 1)College of Electric science and Technology beijing. beijing 100070, china 2.Information engineering school, university of science and Technology beijing. beijing 100083, china Coll Elect Sci & Technol beijing Beijing 100070 Peoples R China Univ Sci & Technol beijing Informat Engn Sch Beijing 100083 Peoples R China

The theories of synchronization based on secure communications using digital chaos are presented. A new synchronous method-cycles-interval Pulse drive is developed and realized. Experimental results show it is available, and in order to reduce synchronous noise, a method using model references solves the ratio of signal power to noise power, so the secure communication system can be realized.

关键词： digital chaotic synchronization cycles-interval pulses drive synchronous noise model reference

Selection of unitary operations in quantum secret sharing without entanglement

在线全文

学校读者我要写书评

暂无评论

science china(Information sciences) 2011年第9期54卷 1837-1842页

作者： XU Juan 1,CHEN HanWu 1,LIU WenJie 1,2.& LIU ZhiHao 1 1 school of computer {2. and engineering,Southeast university,Nanjing 2.0096,china 2.school of computer and Software,Nanjing university of Information {2. and Technology,Nanjing 2.0044,china 1. school of computer {2. and engineering Southeast University Nanjing 210096 China2. School of Computer and Software Nanjing University of Information Science and Technology Nanjing 210044 China

We propose a substitute-Bell-state attack strategy for quantum secret sharing schemes without entanglement,as well as a definition of the minimum failure probability of such attack strategy.A quantitative analysis of security degrees corresponding to different unitary operations is also provided,when the secret sharing schemes without entanglement are stricken by substitute-Bell-state *** a result,the relation between the selection of unitary operations and the effect of substitute-Bell-state attack is shown,which can serve as an important guidance for the selection of unitary operations in designing and implementing quantum secret sharing schemes.

关键词： quantum secret sharing substitute-Bell-state attack unitary operation minimum failure probability

Mixed boundary conditions for piezoelectric plates

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

作者： GAO Yang 1 ,XU SiPeng 2.&ZHAO BaoSheng 3 1College of science,china Agricultural {2.,beijing 100083,china 2.ollege of engineering,Ocean {2. of china,Qingdao 2.6071,china 3 school of Mechanical engineering,{2. of science and Technology of Liaoning,Anshan 114044,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

AFM study on the adsorption and aggregation behavior of dissolved humic substances on mica

在线全文

学校读者我要写书评

暂无评论

science china Chemistry 2006年第3期49卷 256-266页

作者： GE Xiaopeng1, ZHOU Yanmei2. Lü Chunhua1 & TANG Hongxiao1 1. State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental sciences, Chinese Academy of sciences, {2. 100085, china 2. school of Civil engineering & Architecture, {2. Jiaotong university, {2. 100044, china 1. State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China 2. school of Civil engineering & Architecture Beijing Jiaotong University Beijing 100044 China

Humic substances constitute the major organic fractions of soils, sediments and natural waters, and play a dominant role in the binding, mobilization, transport and ultimate fate of organic contaminants in subsurface systems. In this paper, two humic acid samples, Guanting and Tianjin, with different origin and chemical compositions have been investigated with AFM imaging for their adsorption and aggregation behaviors on mica. While the Tianjin humic sample is found to form small spheres with 2.0 to 330 nm in diameter at lower concentrations, irregular loop-chain assemblies of hundreds of nanometer in diameter with the chain width of about 40 nm are dominant for the Guanting humic sample, which may attribute to the more polar aliphatic fractions in the chemical composition in the latter. The heterogeneous and polydisperse nature of humic substances with multiple structural features, such as sponge-like structures, perforated sheets, aggregate of spheres, branches and chain-like assemblies etc., is apparent at higher concentrations for both humic samples, showing morphologically new evidence for the dominant view of the humic dual-mode sorption model. With naphthalene introduced, the assemblies of Guanting humic substances clearly become more compact with significantly narrowed branches and less porous the perforated sheet-like structures. It is indica- tive of that smaller nanometer scale rings present along the perforated assemblies could potentially represent hydrophobic domains, which may facilitate the adsorption and aggregation of naphthalene onto the natural particle surfaces and therefore lead to an important role of dissolved humic sub- stances in the sorption of environmental pollutants.

关键词： atomic force microscopy (AFM) dissolved humic substances morphology aggregation adsorption

Effects of the CNTF-collagen gel-controlled delivery system on rat neural stem/progenitor cells behavior

在线全文

学校读者我要写书评

暂无评论

science china(Life sciences) 2010年第4期53卷 504-510页

作者： YANG ZhaoYang1, QIAO Hui2.& LI XiaoGuang1,3 1school of Biological science and Medical {2., beihang university, beijing 100191, china 2.ublic Heath school, Ningxia Medical university, Yinchuan 750004, china 3beijing Institute for Neuroscience, Capital Medical university, beijing 100069, china 1. school of Biological science and Medical {2. Beihang University Beijing 100191 China2. Public Heath School Ningxia Medical University Yinchuan 750004 China3. Beijing Institute for Neuroscience Capital Medical University Beijing 100069 China

The injury of central nervous system (CNS) usually causes the cavity formation. Although transplantation of neural stem/precursor cells (NSPCs) into the lesioned area of CNS has been shown to be implicated in the functional restoration, the therapeutic result is limited by the poor survival of NSPCs as well as their insufficient proliferation and differentiation abilities. Type-1 collagen is considered as a candidate scaffold or drug delivery system to overcome the aforementioned obstacle. This study observed the effects of the CNTF (ciliary neurotrophic factor)-collagen gel-controlled delivery system and daily addition of soluble-form CNTF on the NSPC survival, migration, proliferation and differentiation. The results showed that, within 12.h of the initial co-culture, CNTF was released in a burst pattern, then the CNTF-collagen gel-controlled delivery system stably released CNTF for up to 12.d. The cell viability test, together with immunohistochemistry, RT-PCR and Western blotting, showed that the CNTF-collagen gel-controlled delivery system supported the NSPCs seeded on the surface of collagen gel survival and facilitated their migration and proliferation. The daily addition of soluble-form CNTF to the medium had similar effects to the CNTF-collagen gel-controlled delivery system, but large quantities of soluble-form CNTF were consumed during the entire process. Taken together, the CNTF-collagen gel-controlled delivery system not only provides a physical scaffold for the transplanted NSPCs to adhere and migrate, but also facilitates the NSPC survival, growth and proliferation, simultaneously reducing the consumption of the expensive growth factors. This system may be used to enhance the microenvironment in the lesioned area of CNS.

关键词： spinal cord neural stem/progenitor cells control release type-1 collagen CNTF