检索结果-南通市图书馆

Suspended sediment flux of river:Wavelet analysis in the Panlong basin of the Upper Red River (Honghe River),China

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2007年第A02期52卷 172-179页

作者： DING WenRong~(1,2+) ZHOU Yue~(1,3) L XiXi~4 1 The Faculty of Environment Science and Engineering,Kunming university of Science and Technology,Kunming 650093,China 2 College of Tourism and geography Science,Yunnan Normal university,Kunming 650092,China 3 Yunnan university of Finance and Economics,Kunming 650221,China 4.department of geography,national university of singapore 1192.0,singapore Univ Sci and Technol Kumasi Fac Environm Sci and Engn Kunming 650093 Peoples R China.

这份报纸把小浪分析用于检验变化趋势，多时间规模变化，在上面的红河的 Panlong 盆的推迟的沉积流动(SSF ) 的周期、突然的变化特征，中国。结果显示 SSF 从 1951 ～ 1997 增加了，但是自从 1998，衰退了。SSF 的变化把多时间规模特征... 详细信息

这份报纸把小浪分析用于检验变化趋势，多时间规模变化，在上面的红河的 Panlong 盆的推迟的沉积流动(SSF ) 的周期、突然的变化特征，中国。结果显示 SSF 从 1951 ～ 1997 增加了，但是自从 1998，衰退了。SSF 的变化把多时间规模特征和变化在不同时间时期改变了。三周期的时间规模， 4， 7 和 22 年，被决定。22 年的周期的时间规模，是在三次规模之中的最明显的，通过整个研究时期延长了，而第 4-a 7 年的时间规模在某些时间时期仅仅是明显的。分别地有 27 次越过 4 年的时间规模，越过 7 年的时间规模的 16 次和越过 22 年的时间规模的 5 次的突然的变化。根据统计的聚会和气候数据分析，我们断定人的活动是导致了多时间规模的 SSF，而是特征的变化趋势的主要原因，周期、突然的变化被气候变化主要影响。

关键词：河流中国红河微波分析

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, 1192.0, singapore. 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

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

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 230026, China 2 department of Mathematics, national university of singapore, singapore 117543, singapore 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

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

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 1192.0 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

NUMERICAL MODEL FOR FLOW MOTION WITH VEGETATION

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2008年第2期20卷 172-178页

作者： ZHANG Jian-tao SU Xiao-hui department of Civil and Hydraulic Engineering Dalian University of Technology Dalian 116023 China department of Civil Engineering National University of Singapore Singapore 119260 Singapore

A set of governing equations for turbulent flows in vegetated area were derived with the assumption that vegetation is of straight and rigid cylinder. The effect of vegetation on flow motion was represented by additional inertial and drag forces. The new model was validated by available experimental data for open channel flows passing through vegetated areas with different vegetation size, density and distribution. Numerical results are in good agreement with the experimental data. Finally, the flow around a supposed isolated vegetated pile was simulated and the effects of vegetation density on the wake flow were discussed. It is found that the presence of vegetation, even at a very low density, has the pronounced influence on the dissipation of flow energy, both inside the vegetation domain and outside it in the wake flow region.

关键词： numerical simulation vegetation open channel

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 200433, China 2 department of Statistics and Applied Probability, national university of singapore, singapore 117546, singapore 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

Respiratory Metabolism of Orchid Flower

在线全文

学校读者我要写书评

暂无评论

植物生理与分子生物学 1990年第1期 86-89页

作者： HEW Choy-Sin(department of Botany, national university of singapore, singapore 0511, Repubhc of singapore)

In general, relatively few studies were made on the respiratory metabolism of flowers as compared to leaves and fruits. Understanding respiration as an internal metabolic control of floral senescence is important to proper postharwest handling of cut flowers(Coorts 1973, Rogers 1973, Halevy and Mayak 1979). The first extensive review of respiratory metabolism of cut flowers was done by Coorts(1973). The review, however, covered primarily roses, carnations, chrysanthemums and other temperate

关键词： HW