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SELF-ORGANIZING MAP OF COMPLEX NETWORKS FOR COMMUNITY DETECTION

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Journal of Systems Science & Complexity 2010年第5期23卷 931-941页

作者： zhenping li Ruisheng WANG Xiang-Sun ZHANG Luonan CHEN School of Information Beijing Wuzi University Beijing 101149 China School of Information Renmin University of China Beijing 100872 China Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China Department of Electrical Engineering and Electronics Osaka Sangyo University Osaka 574-8530 Japan

Detecting communities from complex networks is an important issue and has attracted attention of researchers in many fields. It is relevant to social tasks, biological inquiries, and technological problems since various networks exist in these systems. This paper proposes a new self-organizing map （SOM） based approach to community detection. By adopting a new operation and a new weightupdating scheme, a complex network can be organized into dense subgraphs according to the topological connection of each node by the SOM algorithm. Extensive numerical experiments show that the performance of the SOM algorithm is good. It can identify communities more accurately than existing methods. This method can be used to detect communities not only in undirected networks, but also in directed networks and bipartite networks.

关键词： Community detection complex network neural networks self-organizing map.

Exploit latent Dirichlet allocation for collaborative filtering

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Frontiers of Computer Science 2018年第3期12卷 571-581页

作者： Zhoujun li Haijun ZHANG Senzhang WANG Feiran HUANG zhenping li Jianshe ZHOU State Key Laboratory of Software Development Environment Beihang University Beijing 100191 China School of Information Beijing Wuzi University Beijing 101149 China College of Computer Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 211106 China Collaborative Innovation Center of Novel Software Technology and Industrialization Nanjing 211106 China Beijing Advanced Innovation Center for Imaging Technology Capital Normal University Beijing 100048 China

Previous work on the one-class collaborative filtering （OCCF） problem can be roughly categorized into pointwise methods, pairwise methods, and content-based methods. A fundamental assumption of these approaches is that all missing values in the user-item rating matrix are considered negative. However, this assumption may not hold because the missing values may contain negative and positive examples. For example, a user who fails to give positive feedback about an item may not necessarily dislike it; he may simply be unfamiliar with it. Meanwhile, content-based methods, e.g. collaborative topic regression （CTR）, usually require textual content information of the items, and thus their applicability is largely limited when the text information is not available. In this paper, we propose to apply the latent Dirichlet allocation （LDA） model on OCCF to address the above-mentioned problems. The basic idea of this approach is that items are regarded as words, users are considered as documents, and the user-item feedback matrix constitutes the corpus. Our model drops the strong assumption that missing values are all negative and only utilizes the observed data to predict a user＇s interest. Additionally, the proposed model does not need content information of the items. Experimental results indicate that the proposed method outperforms previous methods on various ranking-oriented evaluation *** further combine this method with a matrix factorizationbased method to tackle the multi-class collaborative filtering （MCCF） problem, which also achieves better performance on predicting user ratings.

关键词： latent Dirichlet allocation one-class collaborative filtering multi-class collaborative filtering

Torsional vibration suppression and electromechanical coupling characteristics of electric drive system considering misalignment

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Applied Mathematics and Mechanics(English Edition) 2024年第11期45卷 1987-2010页

作者： Jinxin DOU zhenping li Hongliang YAO Muchuan DING Guochong WEI School of Mechanical Engineering and Automation Northeastern UniversityShenyang110819China China North Vehicle Research Institute Beijing100072China

The torque ripples resulting from external electromagnetic excitation and mechanical internal excitation contribute to significant torsional vibration issues within electromechanical coupling *** mitigate these fluctuations,a passive control strategy centered around a multi-stable nonlinear energy sink(MNES)is ***,models for electromagnetic torque,gear nonlinear meshing torque,and misalignment torque are *** upon this foundation,an electromechanical coupling dynamic model of the electric drive system is *** analysis is conducted to determine the sensitive nodes of each mode and to provide guidance for the installation of the *** structure of the MNES is introduced,and an electromechanical coupling dynamic model with the MNES is *** on this model,the influence of the misaligned angle on the electromechanical coupling characteristics is *** addition,the vibration suppression performance of the MNES is studied under both speed and uniform speed ***,experimental testing is conducted to verify the vibration suppression performance of the *** results indicate that misalignment triggers the emergence of its characteristic frequencies and associated ***,the MNES effectively mitigates the torsional vibrations in the coupled system,demonstrating suppression rates of 52.69%in simulations and 63.3%in experiments.

关键词： electric drive system electromechanical coupling nonlinear energy sink(NES) misalignment

Preparation of modified liMn_(2)O_(4) by solid-state reaction

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Rare Metals 2006年第z1期25卷 71-76页

作者： LU Shigang CAI zhenping JIN Weihua li Mingxun HUANG Songtao Division of Mineral Resources Metallurgy&MaterialsGeneral Research Institute for Nonferrous MetalsBeijing 100088China

Modified lithium manganese oxides were prepared by solid-state reaction of liMn_(2)O_(4)and liCoO_(2)as raw materials.A study was carried out by TG-DSC,XRD,DSC and electrochemical to analyse the reaction process and structural characterization of *** results show that the liMn_(2)O_(4)reacts chemically with liCoO_(2)at high *** of li and partial Co atoms can insert into the liMn_(2)O_(4)crystal lattice and a newly formed spinel phase-modified liMn_(2)O_(4)was *** distribution of Co content is even in modified liMn_(2)O_(4)*** modified liMn_(2)O_(4)compound exhibits improved cycling stability at room and elevated temperature in comparison with the pure liMn_(2)O_(4).

关键词： lithium-ion battery spinel liMn_(2)O_(4) modification process

Study on Modification Mechanism of Rare Earth in ZA27 Cast Alloy with Electronic Theory and Molecular Dynamics Method

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Journal of Materials Science & Technology 2004年第5期20卷 586-588页

作者： Guili liU, Rongde li and zhenping ZHOUSchool of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110023, China Sch. of Mat. Sci. and Eng. Shenyang Univ. of Technol. Shenyang 110023 China

A model of liquid ZA27 cast alloy is established according to molecular dynamics theory and an atomic structural model of co-existent a phase and liquid is also presented by means of computer programming. Recursion method is adopted to calculate the electronic structure of RE (rare earth) in grains and around phase boundaries respectively. The calculation shows that RE is more stable around phase boundaries than in grains, which explains the fact that the solution of RE in a phase is less, and RE mainly aggregates in front of phase boundary. The calculations of bonding order integrals also show that RE in front of phases hardly solidify onto the grain surfaces as active element so as to prevent grains growth and refine the grains. As a result, the modification mechanism of RE may be explained from the view of electronic structure.

关键词： Atomic structural model Recursion method Electronic structure Modification mechanism Rare easth

Research on Model and Algorithm of Task Allocation and Path Planning for Multi-Robot

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Open Journal of Applied Sciences 2017年第10期7卷 511-519页

作者： zhenping li Xueting li School of Information Beijing Wuzi University Beijing China

Based on the modeling of robot working environment, the shortest distance matrix between points is solved by Floyd algorithm. With the objective of minimizing the sum of the fixed cost of robot and the cost of robot operation, an integer programming model is established and a genetic algorithm for solving the model is designed. In order to make coordination to accomplish their respective tasks for each robot with high efficiency, this paper uses natural number encoding way. The objective function is based on penalty term constructed with the total number of collisions in the running path of robots. The fitness function is constructed by using the objective function with penalty term. Based on elitist retention strategy, a genetic algorithm with collision detection is designed. Using this algorithm for task allocation and path planning of multi-robot, it can effectively avoid or reduce the number of collisions in the process of multi-robot performing tasks. Finally, an example is used to validate the method.

关键词： Path Planning Task Allocation Collision Detection Mathematical Model Genetic Algorithm

Transonic flow of moist air around an NACA 0012 airfoil with non-equilibrium condensation

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Progress in Natural Science:Materials International 2005年第9期15卷 838-842页

作者： li liang**, SUN Xiuling, FENG zhenping and li Guojun(School of Energy & Power Engineering, Xi’an Jiao Tong University, Xi’an 710049, China) School of Energy & Power Engineering Xi'' an Jiao Tong University Xi'' an 710049 China

The classical condensation model of water vapor is coupled with the Euler equations to calculate transonic flows of moist air with non-equilibrium condensation. By means of this model, numerical computations are implemented to investigate the aerodynamic characteristics of an NACA 0012 airfoil in transonic flows of moist air at various angles of attack and relative humidities, and the results are compared with those in dry air flows. For different angles of attack considered at 50% relative humidity, the lift decreases 30%—40%. The pressure drag increases when the angle of attack is smaller than 1.4° and decreases when higher than 1.4°. At zero angle of attack, with the relative humidity rising from zero to 90%, the pressure drag increases exponentially. At 90% relative humidity, the pressure drag increases 160%, and self-oscillation takes place periodically and alternately over the upper and lower surfaces of the airfoil. The oscillation is caused by the interactions of local supersonic flow and heat release in the condensation process.

关键词： NACA 0012 airfoil moist air non-equilibrium condensation.

Study on Location of Wuhan Steel Logistics Distribution Center

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Open Journal of Applied Sciences 2016年第13期6卷 938-943页

作者： Mengyue Yang zhenping li School of Information Beijing Wuzi University Beijing China

This paper studies the location of Wuhan steel logistics distribution center. First of all, according to Wuhan Iron and Steel Plant sales in Hunan Province and the relative position of the city, the transport costs are calculated from Wuhan Iron and Steel Plant to the demand point. We further analyze the necessity of establishing steel logistics distribution center, using the precise center of gravity to determine the actual location of the distribution center. After the establishment of distribution center, the total freight is reduced by 15.46 million yuan from Wuhan Iron and Steel Plant to each city in Hunan province via distribution center each year. The results of this paper can provide theoretical basis for the logistics node planning of related enterprises.

关键词： Steel Logistics Distribution Center Location Precise Center of Gravity Method

Study on the Inventory Routing Problem of Refined Oil Distribution Based on Working Time Equilibrium

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American Journal of Operations Research 2016年第1期6卷 17-24页

作者： zhenping li Zhiguo Wu School of Information Beijing Wuzi University Beijing China

Taking the distribution route optimization of refined oil as background, this paper studies the inventory routing problem of refined oil distribution based on working time equilibrium. In consideration of the constraints of vehicle capacity, time window for unloading oil, service time and demand of each gas station, we take the working time equilibrium of each vehicle as goal and establish an integer programming model for the vehicle routing problem of refined oil distribution, the objective function of the model is to minimize the maximum working time of vehicles. To solve this model, a lingo program was written and a heuristic algorithm was designed. We further use the random generation method to produce an example with 10 gas stations. The local optimal solution and approximate optimal solution are obtained by using lingo software and heuristic algorithm respectively. By comparing the approximate optimal solution obtained by heuristic algorithm with the local optimal solution obtained by lingo software, the feasibility of the model and the effectiveness of the heuristic algorithm are verified. The results of this paper provide a theoretical basis for the scheduling department to formulate the oil distribution plan.

关键词： Working Time Equilibrium Hard Time Window Inventory Routing Problem Mathematical Model Heuristic Algorithm