检索结果-南通市图书馆

Automated Dimensioning Method of Engineering Drawings for Mechanical Products Based on Curve Chain

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2020年第10期65卷 847-863页

作者： Gui Li Peng Yang Key Laboratory of Metallurgical Equipment and Control Technology Ministry of EducationWuhan University of Science and TechnologyWuhan430081China Hubei Key Laboratory of Mechanical Transmission and Manufacturing Engineering Wuhan University of Science and TechnologyWuhan430081China

An automated method based on the curve chain was proposed for dimensioning of engineering drawings for the mechanical *** to the internal relation between the features of 3D model feature and elements of 2D drawing,the curve chain was established to reflect the geometric topological structure between the *** divides the dimensions into the absolute dimensions within the cure chain and the relative dimensions between the curve *** parallel and lengthy relationship between the drawing elements of the constructed X and Y parallel matrix was solved to remove redundant elements in the curve chain and labeled the absolute dimensions of the remaining valid *** average minimum weight coefficient was introduced to judge the dependence on the relative dimensions between curve *** the analysis of the overlap between the circular rectangular areas,including all the absolute dimensions of the curve chains,overlapping curve chains were merged,and their dimensions were rearranged to avoid the cross interference between *** method was seamlessly integrated into the drafting module of product design software NX,and it developed an automated dimensioning *** examples show that the system has excellent interactivity and robustness in the dimensioning of product engineering *** dimension information is complete,accurate and reliable.

关键词： Automated dimensioning engineering drawing curve chain mechanical product weight coefficient

APPLICATION OF GEOGRAPHICAL PARAMETER DATABASE TO ESTABLISHMENT OF UNIT POPULATION DATABASE

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Geographical Science 2003年第1期13卷 34-38页

作者： WUXi-zhi DONGChun ZHAORong LIUJi-ping WANGGui-xin StatisticsDepartment RenminUniversityofChinaBeijing100872P.R.China GovernmentGISResearchCenter ChineseAcademyofSurveyingandMappingBeijing100039P.R.China InstituteofPopulationResearch FudanUniversitySchanghia200433P.R.China

Now GIS is turning into a good tool in handling geographical, economical, and population data, so we can obtain more and more information from these data. On the other hand, in some cases, for a calamity, such as hurricane, earthquake, flood, drought etc., or a decision-making, such as setting up a broadcasting transmitter, building a chemical plant etc., we have to evaluate the total population in the region influenced by a calamity or a project. In this paper, a method is put forward to evaluate the population in such special region. Through exploring the correlation of geographical parameters and the distribution of people in the same region by means of quantitative analysis and qualitative analysis, unit population database (1km× 1km) is established. In this way, estimating the number of people in a special region is capable by adding up the population in every grid involved in this region boundary. The geographical parameters are obtained from topographic database and DEM database on the scale of 1: 250 000. The fundamental geographical parameter database covering county administrative boundaries and 1km × 1km grid is set up and the population database at county level is set up as well. Both geographical parameter database and unit population database are able to oiler sufficient conditions for quantitative analysis. They will have important role in the research fields of data mining (DM), Decision-making Support Systems (DSS), and regional sustainable development.

关键词： geographical parameter database unit population database quantitative analysis weight coefficient standardized weight coefficient

Continuous weight Attack on Complex Network

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2008年第3期49卷 797-800页

作者： YIN Yan-Ping ZHANG Duan-Ming TAN Jin PAN Gui-Jun HE Min-Hua Department of Physics Huazhong University of Science and Technology Wuhan 430074 China Faculty of Physics and Electronic Technology Hubei University Wuhan 430062 China

We introduce a continuous weight attack strategy and numerically investigate the effect of continuous weight attack strategy on the Barabasi-Albert （BA） scale-free network and the Erdos-Rdnyi （ER） random network. We use a weight coefficient ω to define the attack intensity. The weight coefficient ω increases continuously from 1 to infinity, where 1 represents no attack and infinity represents complete destructive attack. Our results show that the continuous weight attack on two selected nodes with small ω （ω≈ 3） could achieve the same damage of complete elimination of a single selected node on both BA and ER networks. It is found that the continuous weight attack on a single selected edge with small ω （ω≈ 2） can reach the same effect of complete elimination of a single edge on BA network, but on ER network the damage of the continuous weight attack on a single edge is c/ose to but always smaller than that of complete elimination of edge even if ω is very large.

关键词： network efficiency weight coefficient weak attack complex networks

The Best Constants of Hardy Type Inequalities for p = -1

在线全文

学校读者我要写书评

暂无评论

Journal of Mathematical Research and Exposition 2008年第2期28卷 316-322页

作者： WEN Jia Jin GAO Chao Bang College of Mathematics and Information Science Chengdu University Sichuan 610106 China

For p ：〉 1, many improved or generalized results of the well-known Hardy＇s inequality have been established： In this paper, by means of the weight coefficient method, we establish the following Hardy type inequality for p = -1：∑^n i=1（1/i∑^i j=1 aj）^-1〈∑^n i=1（1-π^2-9/3i）ai^-1,where ai 〉 0, i = 1,2,... ,n. For any fixed positive integer n 〉 2, we study the best constant Cn such that the inequality ∑^ni=1（1/i∑^ij=1aj）^-1≤cn∑^ni=1ai^-1holds. Moreover, by means ofthe Mathematica software, we givesome examples.

关键词： Hardy type inequalities weight coefficient the best constant.

On an Extension of Hibert's Inequality and Applications

在线全文

学校读者我要写书评

暂无评论

Chinese Quarterly Journal of Mathematics 2006年第1期21卷 96-102页

作者： YANG Bi-cheng Department of Mathematics Guangdong Institute of Education Guangzhou 510303 China

This paper gives a new generalization of Hilbert＇s inequality with a best constant factor involving the β function. An applications, we consider the equivalent form and some particular results.

关键词： Hilbert's inequality weight coefficient β function Holder's inequality

On an Extension and a Refinement of Van der Corput's Inequality

在线全文

学校读者我要写书评

暂无评论

Chinese Quarterly Journal of Mathematics 2007年第1期22卷 94-98页

作者： YANG Bi-cheng Department of Mathematics Guangdong Institute of Education Guangzhou 510303 China

By introducing a parameter α, we give an extension of Van der Corput＇s inequality. Also a new strengthened version of it is considered.

关键词： Van der Corput's inequality weight coefficient Euler-Maclaurin's formula

Model predictive flux control of permanent magnet synchronous motor driven by three-level inverter based on fine-division strategy

在线全文

学校读者我要写书评

暂无评论

Journal of Measurement Science and Instrumentation 2022年第4期13卷 439-450页

作者： MIAO Zhongcui LI Haiyuan HE Yangyang WANG Yunkun School of Automation&Electrical Engineering Lanzhou Jiaotong UniversityLanzhou 730070China

Aiming at the difficulty of setting the weight coefficient in the value function of model predictive torque control(MPTC)for permanent magnet synchronous motor(PMSM)driven by three-level inverter,a fine-division model predictive flux control(MPFC)method is ***,establish a mathematical model between the motor torque and the stator flux linkage according to the mathematical equations of ***,the control of the motor torque and stator flux linkage in the MPTC is transformed into the control of a single stator flux linkage vector,omitting the cumbersome weight setting process in the traditional *** midpoint potential control strategy is proposed,which uses the characteristics of redundant small vectors to balance the midpoint *** that,a fine-division strategy is proposed,which effectively reduces the number of candidate vectors and the computational burden of the ***,the proposed MPFC is compared with MPTC by *** results show that the proposed fine-division MPFC effectively reduces the system calculation,and has the advantages of simple principle and better dynamic and steady-state control *** feasibility of the control strategy is verified.

关键词： permanent magnet synchronous motor(PMSM) three-level inverter model predictive flux control(MPFC) weight coefficient midpoint potential

Research of Combination Rule Based on Evidence Distance and Local Conflict Distribution

在线全文

学校读者我要写书评

暂无评论

Research of Combination Rule Based on Evidence Distance and ...

On a Refinement of Hardy-Hilbert's Inequality and Its Applications

2010 Chinese Control and Decision Conference

作者： Jun-wei Li,Yong-mei Cheng,Shao-wu Zhang,Yan Liang School of Automation,Northwestern Polytechnical University,Xi''an,710072

＜正＞Dempster-Shafer Theory（DST） is an effective method for dealing with multi-sensor ***, the results may be contrary to intuition when dealing with the highly conflicting *** order to efficiently overcome the shortcomings of DST,a new improved DST combination rule based on evidence distance and local conflict distribution strategy is ***,the mutual support degree of every evidence is obtained by the evidence distance,and normalize the support degree to the relative credibility of the evidence;the generate reason of local conflict is analyzed,the conflicting information is only distributed to those focal elements which contribute to the *** through calculating local conflict,and the distributed value depends on the credibility and similarity degree of the focal elements between the *** results of numerical examples prove that the new combination rule enhances the reliability and rationality of the evidence combination results,and effectively solves the combination of highly conflicting evidence.

关键词： Dempster’s Rule Evidence Distance Local Conflict Information Fusion weight coefficient

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Northeastern Mathematical Journal 2000年第3期16卷 279-286页

作者：杨必成 Cuangdong Education College

In this paper, by introducting a weight coefficient of the form: π/sin(π/r)-1/10(2n+1)1+1/r (r＞1, n∈N0), Hardy-Hilbert's inequality is refined. As its applications, an equivalent Hard y-Hilbert's type inequa... 详细信息

关键词： Hardy-Hilbert's inequality weight coefficient Hardy- Littlewood's inequality