检索结果-南通市图书馆

Influence of Coolant on Cutting Tool Performance

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 Materials Science & Technology 1997年第3期13卷 199-205页

作者： K.H.W.Seah and X.Li(Dept. of Mechanical and Production Engineering, national university of singapore, 10 Kent Ridge Crescent,singapore 1.9260) Dept. of Mechanical and Production Engineering National University of Singapore 10 Kent Ridge Crescent Singapore 119260 Singapore

This paper reports a Study carried out to substantiate or refute the belief that when coolant is applied, the cutting performance is actually improved. Experiments on cutting forces and chip geometry were conducted in which AISI 1050 Steel was machined by turning using P3. uncoated tungsten carbide tools. Experiments were performed on a CNC Okuma LH3.-N lathe undermachining conditions commonly used in workshops in singapore and many other parts of the world.

关键词： Tool Influence of Coolant on Cutting Tool Performance

Two optimization algorithms for solving robotics inverse kinematics with redundancy

在线全文

学校读者我要写书评

暂无评论

控制理论与应用（英文版） 2010年第2期8卷 166-175页

作者： Jianxin XU, Wei WANG, Yuanguang SUN (Department of Electrical and Computer Engineering, national university of singapore, singapore 117576) Department of Electrical and Computer Engineering National University of Singapore Singapore Singapore

The kinematic redundancy in a robot leads to an infinite number of solutions for inverse kinematics, which implies the possibility to select a 'best' solution according to an optimization criterion. In this paper, two optimization objective functions are proposed, aiming at either minimizing extra degrees of freedom (DOFs) or minimizing the total potential energy of a multilink redundant robot. Physical constraints of either equality or inequality types are taken into consideration in the objective functions. Since the closed-form solutions do not exist in general for highly nonlinear and constrained optimization problems, we adopt and develop two numerical methods, which are verified to be effective and precise in solving the two optimization problems associated with the redundant inverse kinematics. We first verify that the well established trajectory following method can precisely solve the two optimization problems, but is computation intensive. To reduce the computation time, a sequential approach that combines the sequential quadratic programming and iterative Newton-Raphson algorithm is developed. A 4-DOF Fujitsu Hoap-1 humanoid robot arm is used as a prototype to validate the effectiveness of the proposed optimization solutions.

关键词： Inverse kinematics Redundant robot Objective function Optimization Numerical approach

Lasers in Ophthalmology

在线全文

学校读者我要写书评

暂无评论

眼科学报 1992年第3期8卷 143-144页

作者： Ronald Yeoh singapore national Eye Centre national {{3. Hospital,singapore 0511 singapore national Eye Centre National University Hospital.

In recent years,lasers have entered every fieldof medicine and especially so in *** scientific basis of lasers in ophthal-mology is based on three mechanisms:*** effectLasers:argon,krypton,dye and diodeA thermal effec... 详细信息

关键词： Lasers in Ophthalmology

CONVERGENCE OF CASCADE ALGORITHMS AND SMOOTHNESS OF REFINABLE DISTRIBUTIONS

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 2003年第3期24卷 367-386页

作者： SUN QIYU Department of Mathematics, university of Houston, Houston, TX 77204, USA. Department of Mathematics, national university of singapore, 10 Kent Ridge Crescent, 1.9260, {{3.. Univ Houston Dept Math Houston TX 77204 USA Natl Univ singapore Dept Math Singapore 119260 Singapore

In this paper, the author at first develops a method to study convergence of the cascadealgorithm in a Banach space without stable assumption on the initial (see Theorem 2.1), andthen applies the previous result on the convergence to characterizing compactly supportedrefinable distributions in fractional Sobolev spaces and Holder continuous spaces (see Theorems3.1, 3.3. and 3.4). Finally the author applies the above characterization to choosing appropriateinitial to guarantee the convergence of the cascade algorithm (see Theorem 4.2).

关键词： Cascade algorithm Cascade operator Refinable distribution Shift-invariant space Linear independent shifts Stable shifts Fractional Sobolev space

Decay of geometry for unimodal maps:The C^2 case

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2009年第11期54卷 1859-1862页

作者： SHEN WeiXiao1,2 1 Department of Mathematics, university of Science and Technology of China, Hefei 23.026, China 2 Department of Mathematics, national university of singapore, {3. 117543. {3. Department of Mathematics University of Science and Technology of China Hefei 230026 China Department of Mathematics National University of Singapore Singapore 117543 Singapore

We prove that a C2 unimodal interval map with critical order not greater than 2 has the decay of geometry property, by showing that all the cross-ratio estimates needed in the previous proof for the C3.case remain true.

关键词：衰变几何图案件几何性质比率估计证明

Formation, Structure and Properties of Bulk Metallic Glasses

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 1999年第2期15卷 97-110页

作者： Y. Li(Department of Materials Science, Faculty of Science, national university of singapore, Lower Kent Ridge Road,singapore 1.9260 E-mail:masliy@nus.edu.sg) Department of Materials Science Faculty of Science National University of Singapore Lower Kent Ridge Road Singapore 119260 Singapore

Bulk metallic glasses with up to 72 mm critical section thickness have been obtained by conventional casting techniques and the properties of these materials, particularly the mechanical and magnetic properties have been studied. These materials have been demonstrated to have novel properties which are fundamentally different from their crystalline counterparts. The recent status of research and development in formation, structure and properties of bulk metallic glasses is reviewed. The techniques to produce such bulk glasses are summarized and the glass forming ability and the critical cooling rate of these materials are discussed. Further consideration of the development and application of this new class of materiaIs will be proposed.

关键词： Ni Zr Structure and Properties of Bulk Metallic Glasses Formation OK Cu Figure

Efficiency Improvement of Heterojunction Polymer Photovoltaic Cells through Controlling the Morphology of the Polymer Film

在线全文

学校读者我要写书评

暂无评论

复旦学报（自然科学版） 2007年第5期46卷 655-页

作者： Jian-yong Ouyang(Department of Materials Science and Engineering, national university of singapore, singapore 117576) Department of Materials Science and Engineering National University of Singapore Singapore 117576

1 Results Polymer photovoltaic cells, which provide clean and renewable energy sources, have gained more and more attention. Polymer photovoltaic cells have the advantage of low fabrication cost and high mechanical flexibility. Polymers can be processed through a solution process, so that a homogeneous polymer film could be readily prepared in a large area. Recently, the light-to-electricity conversion efficiency of the polymer photovoltaic cells was improved significantly[1-2]. Polymer donor and organi...

关键词： polymer photovoltaic cell morphology temperature solvent

Effect of rock mass structure and block size on the slope stability——Physical modeling and discrete element simulation

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2005年第z1期48卷 1-17页

作者： LI Shihai1, LIAN Zhenzhong1,2 & J. G. Wang3.1. Institute of Mechanics, Chinese Academy of Sciences, Beijing 100080, China 2. Graduate School, Chinese Academy of Sciences, Beijing 100060, China 3. Tropical Marine Science Institute, national university of singapore,{3. Chinese Acad Sci Inst Mech Beijing 100080 Peoples R China Chinese Acad Sci Grad Sch Beijing 100060 Peoples R China Natl Univ singapore Trop Marine Sci Inst Singapore 119260 Singapore

This paper studies the stability of jointed rock slopes by using our improved three-dimensional discrete element methods (DEM) and physical modeling. Results show that the DEM can simulate all failure modes of rock slopes with different joint configurations. The stress in each rock block is not homogeneous and blocks rotate in failure development. Failure modes depend on the configuration of joints. Toppling failure is observed for the slope with straight joints and sliding failure is observed for the slope with staged joints. The DEM results are also compared with those of limit equilibrium method (LEM). Without considering the joints in rock masses, the LEM predicts much higher factor of safety than physical modeling and DEM. The failure mode and factor of safety predicted by the DEM are in good agreement with laboratory tests for any jointed rock slope.

关键词： rock masses, slope stability, DEM simulation, block size effect, joints configuration effect, limit equilibrium method.

Saddlepoint approximations for studentized compound Poisson sums with no moment conditions in audit sampling

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2010年第12期53卷 3131-3138页

作者： ZHOU GuoLiang 1 & ZHOU Wang 2, 1 Institute of Accounting and Finance, Shanghai university of Finance and Economics, Shanghai 20043., China 2 Department of Statistics and Applied Probability, national university of singapore, {3. 117546, {3. 1. Institute of Accounting and Finance Shanghai University of Finance and Economics Shanghai 200433 China2. Department of Statistics and Applied Probability National University of Singapore Singapore 117546 Singapore

Saddlepoint approximations for the studentized compound Poisson sums with no moment conditions in audit sampling are derived. This result not only provides a very accurate approximation for studentized compound Poisson sums, but also can be applied much more widely in statistical inference of the error amount in an audit population of accounts to check the validity of financial statements of a firm. Some numerical illustrations and comparison with the normal approximation method are presented.

关键词： saddlepoint approximation Laplace approximation self-normalized compound Poisson sum stu- dentized compound Poisson sum