检索结果-南通市图书馆

The optical near-field speckles and their first order statistics on the basis of the integral equations of electromagnetic field

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2004年第3期47卷 365-380页

作者： CHENG Chuanfu1, 2. SONG Hongsheng2. LIU Chunxiang2. REN Xiaorong2. ZHANG Ningyu3, TENG Shuyun1 & XU Zhizhan1 1. Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P. O. Box 800-2.1, Shanghai 2.1800, china 2. Department of Physics, shandong Normal {2., jinan 2.0014, china 3. shandong Institute of Architecture and Engineering, jinan 2.0014, china 1. Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences P. O. Box 800-211 201800 Shanghai China 2. Department of Physics Shandong Normal University 250014 Jinan China 3. shandong Institute of Architecture and Engineering 250014 Jinan China

From Helmholtz equation of the harmonic electromagnetic waves, the integral equations of the light field at the medium boundaries are obtained by use of the Green's theorem and are discretized into linear equation set with the values of the light field and its derivative as the unknowns. On solving the linear equation set, we realize the rigorous computations of the light fields at the boundaries. Then the intensities of the light waves scattered by the random self-affine fractal surfaces in the optical near-field are calculated, and the propagation characteristics, the evolutions of the contrast and the intensity probability density function of the near-field speckles are studied in detail. The near-field speckles are much different from the conventional speckles in the diffraction regions and in the imaging systems. There are obvious local fluctuations in the intensity distributions of the near-field speckles and such fluctuations disappear after propagating a distance of one wavelength from the medium surfaces. For the random surfaces with smaller lateral correlation lengths, the speckle contrasts approach the saturation values and the speckle fields approach Gaussian distribution within the near-field, while for the random surfaces with larger lateral correlation lengths, such evolutions become comparatively slow.

关键词： speckle, near-field optics, first order statistics, Green's function.

Demagnetization Process and Coercivity for Anisotropic HDDR NdFeB Bonded Magnets

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2000年第4期16卷 445-446页

作者： Ruwei GAO and Jiancheng ZHANG (Physics Department, shandong university, {2., china) Xianhong DENG and Yongjun ZHANG (shandong Metallurgical research Institute, jinan 2.0014, china) Physics Department Shandong University Jinan 250100 China shandong Metallurgical research Institute Jinan 250014 China

The demagnetization process and the coercivity mechanism for amsotropic HDDR Nd(Fe,Co)B bonded magnets were studied by comparing the dependence of coercivity on the alignment field applied while the powders were pressed. The results showed that both the remanence and the coercivity of magnet increased with increasing alignment field. The demagnetization process of the magnet can be classified as the nucleation process inside the grains and the domain-wall motion between the grains. The combined effect of two processes determines the coercivity of HDDR NdFeB bonded magnets.

关键词： NdFeB HDDR Demagnetization Process and Coercivity for Anisotropic HDDR NdFeB Bonded Magnets

Analysis of the carbon source for diamond crystal growth

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2008年第6期53卷 937-942页

作者： LI Li1,2. XU Bin2.3 & LI MuSen1,2.1 School of Materials Science & Engineering, shandong university, {2. 2.0061, china 2.shandong Engineering research Center for Super Hard Materials, Zoucheng 2.3500, china 3 School of Materials Science & Engineering, shandong Jianzhu university, {2. 2.0101, china School of Materials Science & Engineering Shandong University Jinan China shandong Engineering research Center for Super Hard Materials Zoucheng China School of Materials Science & Engineering Shandong Jianzhu University Jinan China

The lattice constants of diamond and graphite at high pressure and high temperature (HPHT) were calculated on the basis of linear expansion coefficient and elastic constant. According to the empirical electron theory of solids and molecules (EET), the valence electron structures (VESs) of diamond, graphite crystal and their common planes were calculated. The relationship between diamond and graphite structure was analyzed based on the boundary condition of the improved Thomas-Fermi-Dirac theory by Cheng (TFDC). It was found that the electron densities of common planes in graphite were not continuous with those of planes in diamond at the first order of approximation. The results show that during the course of diamond single crystal growth at HPHT with metal catalyst, the carbon sources forming diamond structure do not come from the graphite structure directly. The diamond growth mechanism was discussed from the viewpoint of valence electron structure.

关键词：钻石晶体生长石墨碳源价电子结构

Powder Forging of a Motorcycle Connecting Rod

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2002年第6期18卷 544-548页

作者： Guangchun WANG and Guoqun ZHAOMold & Die Engineering Technology research Center, shandong {2. (Southern campus), jinan 2.0061, china Die Eng. Technol. Res. Cent. Shandong Univ. Ji'nan 250061 China

A motorcycle connecting rod is one of the major moving parts affecting the engine performance. The traditional manufacturing process results in material waste and excessive machining. A new method of hot forging P/M has been proposed and studied experimentally. In order to achieve uniform density, the punch was divided into three parts to consolidate the loose powder. The multistage movement of the three parts of the punch, called synchronous compaction, results in the desired uniform density. Powder flow during consolidation was illustrated and the density distribution of the compacts was measured. A set of forging dies with flash was used to produce densification and deformation of the sintered compact. Then a set of flashless forging dies was designed to obtain the desired shape and dimensions of the connecting rod. The effects of forging temperature and initial compact density on densification were evaluated through hot forging experiments. Based on properties achieved, Fe-C-Cu-Mo was selected as the

关键词： Powder metallurgy Connecting rod Powder forging

Study on sea water intrusion into palaeochannels on south coastal plain of the Laizhou Bay by the Bohai Sea

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2003年第1期22卷 69-74页

作者： Han Mei Geography Department, shandong Normal university, {2. 2.0014, china shandong Normal Univ Dept Geog Jinan 250014 Peoples R China

The palaeochannel evolution in the study region is divided into four stages by such methods as 14C dating. Sea water intrusion through palaeochannels has been studied as a focal point. Palaeochannels are the main passageways through which the sea water intrudes at a higher speed, through many means and in a changeable dynamic state.

关键词： Palaeochannel sea water intrusion south coastal plain of Laizhou Bay

H∞ control of a class of nonlinear Hamiltonian descriptor systems

在线全文

学校读者我要写书评

暂无评论

Science china(Information Sciences) 2010年第11期53卷 2195-2204页

作者： SUN LiYing1,2.& WANG YuZhen1 1School of Control Science and Engineering, shandong university, {2. 2.0061, china 2.chool of Science, university of {2., {2. 2.002., china 1. School of Control Science and Engineering Shandong University Jinan 250061 China2. School of Science University of Jinan Jinan 250022 China

This paper studies the stabilization and H∞ control of a class of nonlinear Hamiltonian descriptor systems. Firstly, based on the structural characteristic of the nonlinear Hamiltonian descriptor system, an equivalent nonlinear dissipative Hamiltonian differential-algebraic system is obtained by using restricted system equivalent theory. With the dissipative form, the stabilization problem is then discussed for the nonlinear Hamiltonian descriptor systems, and an H∞ controller is designed. Finally, simulations on a nonlinear circuit system are given.

关键词： nonlinear Hamiltonian descriptor systems stabilization H∞ control

LEAST-SQUARES MIXED FINITE ELEMENT METHODS FOR NONLINEAR PARABOLIC PROBLEMS

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2002年第2期20卷 153-164页

作者： Dan-ping Yang (School of Mathematics and System Science, shandong university, {2., china) School of Mathematics and System Science Shandong University Jinan 250100

Focuses on the formulation of a number of least-squares mixed finite element schemes to solve the initial boundary value problem of a nonlinear parabolic partial differential equation. Convergence analysis; Informatio... 详细信息

关键词： least-squares algorithm mixed finite element nonlinear parabolic problems convergence analysis

Study on mechanical parameters of fractured rock masses

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2011年第S1期54卷 140-146页

作者： CHEN WeiZhong 1,2.YANG JianPing 1,TAN XianJun 1 &YU HongDan 1 1 State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan 430071,china 2.research Center of Geotechnical and Structural Engineering,{2. university,jinan 2.0061,china 1. State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil Mechanics Chinese Academy of Sciences Wuhan 430071 China2. Research Center of Geotechnical and Structural Engineering Shandong University Jinan 250061 China

The equivalent strength parameters of fractured rock masses are prerequisite for stability analysis of geotechnical engineering projects constructed in fractured rock masses which are encountered frequently in western *** on generated mesh of fractured rock masses,combined with statistic damage constitutive model of intact rock and damage model of structural plane,progressive failure of fractured rock masses is studied using finite element method(FEM) .Furthermore,Scale effect and anisotropy of compressive strength of fractured rock masses are *** results show that the strength decreases and tend towards stability rapidly from intact rock to fractured rock masses,and the anisotropy of strength of fractured rock masses is not *** last,based on numerical simulation conducted on 10 m scale rock masses under different confining pressures,the equivalent strength parameters of fractured rock masses are gained and the results are compared with Hoek-Brown *** method developed is helpful for determination of strength parameters of fractured rock masses.

关键词： rock mechanics fractured rock masses equivalent strength parameters finite element method scale effect anisotropy

Formation and Evolution of Ancient Lakes on South Coast Plain of Laizhou Bay

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Population,Resources and Environment 2005年第4期3卷 26-32页

作者： Han Mei 1, Zhou Baohua 2. Yang Peilin 1,Gao Guiqin 1 & Zhang Weiying 1 1. Department of Geography, shandong Normal university, {2. 2.0014, china 2. Department of Geography, {2. university, {2. 2.0001, china Department of Geography Shandong Normal University Jinan 250014 China Department of Geography Jlnan University Jinan 250001 China

Based on the data of historical geography, the analysis of the stratigraphic section, and the textual research of place names and satellite photographic interpretations, the authors study the formation and evolution of ancient lakes on the south coast plain of Laizhou Bay where there were once three lakes: Judian Lake, Qingshuibo Lake and Biehua Lake. All the lakes formed 6000 years ago evolved from the lagoons near the estuary and went through two periods, the golden age in the Middle Holocene and the shrinking age in the Late Holocene. The disappearance of the lakes resulted from the drying climate, the migration of the river courses and the activities of human beings. Among the three reasons, the migration of the river courses is the main one.

关键词： ancient lake cause historical evolution south coast plain of Laizhou Bay