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A New Topological Description Method of Kinematic chain

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机械设计与研究 2004年第Z1期20卷 161-164页

作者： Ding Huafeng Huang Zhen Cao Yi Yanshan University Qinhuangdao Hebei 066004China Yanshan University Qinhuangdao Hebei 066004China Yanshan University Qinhuangdao Hebei 066004China

This paper presents a novel method for the description of kinematic chains, namely the canonical description of kinematic chains including the synthetic degree-sequences and the canonical adjacency matrices sets of kinematic chains. The most important characteristic of this new description method is its uniqueness. Based on the new principle the isomorphism identification becomes easy and the structures of all kinds of kinematic chains can be stored in computer for the benefits of the realization of automation and intelligence of machine design.

关键词： kinematic chain, topological description, topological graph

Magnetization of a Gapped Spin 1/2 Antiferromagnetic Ising chain near the Critical External Field

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Communications in Theoretical Physics 2001年第12期36卷 733-736页

作者： LIU Yi-Chang CHEN Yu-Guan LOU Ji-Zhong QIN Shao-Jin CHEN Hong Institute of Theoretical Physics P.O. Box 2735 Beijing 100080 China Department of Physics Tongji University Shanghai 200092 China Department of Physics University of Nevada Las Vegas NV 89154 USA Institute of Theoretical Physics P.O. Box 2735 Beijing 100080 China Department of Physics Kyushu University Hakozaki Higashi-ku Fukuoka 812-8581 Japan Department of Physics Tongji University Shanghai 200092 China

We study the magnetization of gapped spin 1/2 XXZ Heisenberg Ising chains and calculate the scattering length among massive spinons. We obtain the magnetization close to the critical external magnetic field. The leading correction term determined by the scattering length among massive spinons is given. Our results are in agreement with exact results and with experimental results. We show that the deviation from the massive free hard core boson picture can be accounted very well by the leading correction term due to the spinon-spinon interaction. We show that the deviation increases along with the increasing of the Ising term.

关键词： magnetization, XXZ spin 1/2 chain, spinon-spinon scattering length

Power-Law Behavior in Signal Scattering Process in Vertical Granular chain with Light Impurities

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Communications in Theoretical Physics 2001年第12期36卷 699-704页

作者： XU Ai-Guo Department of Physics and Center for Strongly Correlated Materials Research Seoul National University Seoul 151-742.Korea

We investigate the scattering process of impulse in vertical granular chain with light impurities. When the perturbation is weak, the quantities describing the reflection rate exhibit power-law behavior with the impurity depth. The exponent is nearly independent of vi. When the perturbation is very strong, the vertical chain shows similar behavior to that of the horizontal chain, so the exponent is nearly zero. Our numerical investigation begins from the weak perturbation region and extends to the nonlinear region and found a peak of the exponent. The difficulty in extending the numerical investigation to a stronger perturbation region is *** numbers: 45.70.-n, 43.25.+y, 46.40.

关键词： granular chain, scattering process, power-law behavior, reflection rate

Ergodic degrees for continuous-time Markov chains

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Science China Mathematics 2004年第2期47卷 161-174页

作者： MAO Yonghua Department of Mathematics Beijing Normal University Beijing 100875China

This paper studies the existence of the higher orders deviation matrices for continuous time Markov chains by the moments for the hitting times. An estimate of the polynomial convergence rates for the transition matri... 详细信息

关键词： Markov chain, ergodic degree, hitting time, convergence to stationary.

Algebraic convergence for discrete-time ergodic Markov chains

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Science China Mathematics 2003年第5期46卷 621-630页

作者：毛永华 Department of Mathematics Beijing Normal University Beijing 100875 China

This paper studies the lergodicity for discrete-time recurrent Markov chains. It proves that thel-order deviation matrix exists and is finite if and only if the chain is (l+ 2)-ergodic, and then the algebraic decay rates of then-step transition probability to the stationary distribution are obtained. The criteria forl-ergodicity are given in terms of existence of solution to an equation. The main results are illustrated by some examples.

关键词： Markov chain, ergodicity, algebraic convergence, deviation matrix.

Hierarchical mobility prediction in the future heterogeneous networks for the tradeoff between accuracy and complexity

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The Journal of China Universities of Posts and Telecommunications 2019年第3期26卷 15-24页

作者： Liu Zhenya Li Xi Ji Hong Zhang Heli Key Laboratory of Universal Wireless Communications Beijing University of Posts and Telecommunications Beijing 100876 China School of Information and Communication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China

Mobility prediction is one of the promising technologies for improving quality of service(QoS) and network resource utilization. In future heterogeneous networks(HetNets), the network topology will become extremely complicated due to the widespread deployment of different types of small-cell base stations(SBSs). For this complex network topology, traditional mobility prediction methods may cost unacceptable overhead to maintain high prediction accuracy. This problem is studied in this paper, and the hierarchical mobility prediction scheme(HMPS) is proposed for the future HetNets. By dividing the entire process into two prediction stages with different granularity, the tradeoff between prediction accuracy and computational complexity is investigated. Before performing prediction of user mobility, some frequently visited locations are identified from the user’s trajectory, and each location represents an important geographic area(IGA). In the coarse-grained prediction phase, the next most possible location to be visited is predicted at the level of the possible geographic areas by using a second-order Markov chain with fallback. Then, the fine-grained prediction of user position is performed based on hidden Markov model(HMM) from temporal and spacial dimensions. Simulation results demonstrate that, compared with the existing prediction methods, the proposed HMPS can achieve a good compromise between prediction accuracy and complexity.

关键词： mobility prediction heterogeneous networks prediction accuracy and complexity Markov chain, HMM

The Roper-Suffridge extension operator and classes of biholomorphic mappings Dedicated to Professor Sheng GONG on the occasion of his 75th birthday

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Science China Mathematics 2006年第11期49卷 1539-1552页

作者： GRAHAM Ian KOHR Gabriela Department of Mathematics University of Toronto TorontoOntario M5S 2E4Canada Faculty of Mathematics and Computer Science Babes-Bolyai University 1 M. Kogǎlniceanu Str. 400084 Cluj-NapocaRomania

In this paper we give a survey about the Roper-Suffridge extension operator and the developments in the theory of univalent mappings in several variables to which it has led. We begin with the basic geometric properties (most of which now have a number of different proofs)and discuss relations with the theory of Loewner chains and generalizations and modifications of the operator, some of which are very recent.

关键词： convex mapping, starlike mapping, Roper-Suffridge operator, growth theorem, distortion theorem, covering theorem, Loewner chain, parametric representation,extreme points, linear invariant family.

An approach to error elimination for multi-axis CNC machining and robot manipulation

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Science China(Technological Sciences) 2007年第5期50卷 560-574页

作者： XIONG CaiHua School of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China

The geometrical accuracy of a machined feature on a workpiece during machining processes is mainly affected by the kinematic chain errors of multi-axis CNC ma- chines and robots, locating precision of fixtures, and datum errors on the work- piece. It is necessary to find a way to minimize the feature errors on the workpiece. In this paper, the kinematic chain errors are transformed into the displacements of the workpiece. The relationship between the kinematic chain errors and the dis- placements of the position and orientation of the workpiece is developed. A map- ping model between the displacements of workpieces and the datum errors, and adjustments of fixtures is established. The suitable sets of unit basis twists for each of the commonly encountered types of feature and the corresponding locating di- rections are analyzed, and an error elimination (EE) method of the machined feature is formulated. A case study is given to verify the EE method.

关键词： error elimination, multi-axis machine, robot manipulation, kinematic chain, twist

Effects of China＇s Structural Change on the Exports of East Asian Economies

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China & World Economy 2017年第3期25卷 1-30页

作者： Hyun-Hoon Lee Donghyun Park Kwanho Shin Professor International Trade and Business Kangwon National UniversityKorea Principal Economist Economic Research and Regional Cooperation Department Asian Development Bank. Professor Economics Department Korea University

The Chinese economy is slowing down and is in the midst of a structural transJormattonfrom export-led and investment-led growth to domestic demand-led and consumption-ledgrowth. While there are widespread concerns among China＇s trading partners about theeffect of the slowdown in China＇s growth on their exports, China＇s structural changes arealso likely to have a significant impact：for example, China will import fewer machinesand more cosmetics. The central objective of the present paper is to empirically examinethe effect of China＇s structural transformation on the exports of East Asian economies,which have close trade linkages with China. We find that economies that have failed toincrease the share of consumption goods in their exports to China have suffered largerdeclines in their quantities of exports to China. In addition, economies that have sufferedlosses in their shares of China＇s parts and components imports have faced reductions intheir shares in China ＂s total imports.

关键词： China, East Asia, export, global value chain, structural change