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Post-processing algorithm based on total differential method for multi-axis machine tools with arbitrary configuration

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Jixie Gongcheng Xuebao/Journal of Mechanical Engineering 2012年第13期48卷 121-126页

作者： Peng, Fangyu Ma, Jiyang Wang, Li Yan, Rong Li, Bin State Key Lab. of Digital Manufacturing Equipment and Technology Huazhong University of Science and Technology Wuhan 430074 China National Numerical Control System Engineering Research Center Huazhong University of Science and Technology Wuhan 430074 China

Due to existing post-processing algorithm, which is only suitable for a specific type of multi-axis NC machine tool, a generalized method that fits arbitrary configuration is presented. It derives a general kinematic model from multi-body kinematics, and describes the spatial relationship between adjacent CL-data as total differential. The complicated reverse kinematics problem is transformed into solving linear equations. The initial machine control data is solved with the combination of numerical method and total differential method to ensure solving accuracy of subsequent CL-data. In comparison with conventional methods, experiments on a specific machine tool show that the total differential method has attributes of being better generalized, more accurate, and with faster computing speed. © 2012 Journal of Mechanical Engineering.

关键词： Machine tools

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Electrical performance of 330-kV composite insulators under icing conditions

Electrical performance of 330-kV composite insulators under ...

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2012 International Conference on High Voltage Engineering and Application, ICHVE 2012

作者： Yin, F. Jiang, X. Farzaneh, M. Hu, J. State Key Lab. of Power Transmission Equipment and System Security and New Technology Chongqing Chongqing University Chongqing 400044 China Université du Québec à Chicoutimi Chicoutimi QC Canada Université du Québec à Chicoutimi Chicoutimi QC Canada

ISBN: (纸本)9781467347464

Composite insulators have been widely used in high voltage transmission lines more than 20 years in China due to their hydrophobic properties, relatively low weight and maintenance costs, and high mechanical strength. Shed configuration is a key factor that influences flashover voltage of composite insulators under icing conditions. In order to study the effect of shed configuration on the flashover performance of composite insulators under icing conditions, the electrical performance of five types of 330-kV composite insulators with different shed designs were compared under artificial icing conditions. Experiments were carried out in the multi-function climate chamber in Chongqing University. In order to explain the influence of shed configuration, electric field and potential distributions along each insulator type were calculated numerically using the finite element method (FEM). The numerical simulation results were found to be in agreement with the lab.ratory experimental ones. © 2012 IEEE.

关键词： Flashover

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A Survey of RE-specific Wikis for Distributed Requirements Engineering

A Survey of RE-specific Wikis for Distributed Requirements E...

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International Conference on Semantics, Knowledge and Grid (SKG)

作者： Han Lai Rong Peng Dong Sun Fei Shao Yousong Liu Chongqing Key Lab. of Electronic Commerce & Supply Chain System Chongqing Technology and Business University Chongqing China State Key Lab. of Software Engineering Wuhan University Wuhan China

Wiki, as one of the Web 2.0 technology, has received considerable interest due to its capability to support collab.ratively online contents' creation in a flexible and simple manner. Lots of researchers and practitioners committed themselves to enhancing wiki's capability to support Requirements Engineering (RE). The main goal of this study is to discover all the availab.e tools that use the wiki way or extend the wiki technology to support RE (called as RE-specific wikis), how these RE-specific wikis have been applied, and identify future research directions. We performed a survey through a thorough search for literature and tools that answer our research questions. After data synthesis, we found 12 availab.e RE-specific wikis. And then, we drew out their features, evaluated their RE adaptability. Based on the above findings, we discussed future research directions on how to promote RE-specific wikis to support the collab.rative requirements activities from representation, agreement and specification dimensions.

关键词： Information services Electronic publishing Internet Collab.ration Semantics Educational institutions Sorting

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Training feed-forward neural networks using the gradient descent method with the optimal stepsize

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Journal of Computational Information systems 2012年第4期8卷 1359-1371页

作者： Gong, Liang Liu, Chengliang Li, Yanming Yuan, Fuqing State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai 200240 China Lab. of Operation Maintenance and Acoustics Lulea University of Technology Sweden

The most widely used algorithm for training multiplayer feedforward networks, Error BackPropagation (EBP), is an iterative gradient descend algorithm by nature. Variable stepsize is the key to fast convergence of BP networks. A new optimal stepsize algorithm is proposed for accelerating the training process. It modifies the objective function to reduce the computational complexity of the Jacobin and consequently that of Hessian matrices, and hereby directly computes the optimal iterative stepsize. The improved backpropagation algorithm helps alleviating the problem of slow convergence and oscillations. The analysis indicates that the backpropagation with optimal stepsize (BPOS) is more efficient when treating large-scale samples. The numerical experiment results on pattern recognition and function approximation problems show that the proposed algorithm possesses the features of fast convergence and less intensive computational complexity. © 2011 by Binary Information Press.

关键词： Computational complexity

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Distributed multi-agent Q-learning for joint channel allocation and power control in cognitive radio networks

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Journal of Computational Information systems 2012年第17期8卷 7071-7078页

作者： Boumediene, Latifa Gao, Zhenguo Liu, Sheng College of Automation Harbin Engineering University Harbin 150001 China Key Laboratory of System Control and Information Processing Ministry of Education Shanghai 200240 China State Key Lab. for Novel Software Technology Nanjing University Nanjing 210093 China

This paper deals with the resource allocation in completely distributed cognitive radio network. We propose a form of real-time multi-agent distributed reinforcement learning, which is known as Q-learning, to allow the cognitive radio to predict its transmit power and channel, in order for achieving a high quality of service without affecting the primary users. Simulation results reveal that the proposed approach is able to significantly reduce the interference to the licensed users while maintaining a high probability of successful transmission in a cognitive radio ad-hoc network. © 2012 Binary Information Press.

关键词： Cognitive radio

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New criteria on robust stability for neural networks of neutral-type with mixed delays and norm-bounded uncertainties

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Journal of Information and Computational Science 2012年第6期9卷 1633-1651页

作者： Liu, Guoquan Zhou, Shumin Pang, Jihong Chai, Yi School of Mechanical and Electronic Engineering East China Institute of Technology Nanchang China College of Mechanical Engineering Wenzhou University Wenzhou China State Key Lab. of Power Transmission Equipment and System Security and New Technology of Engineering Chongqing University Chongqing China

particular, the mixed delays consist of discrete interval and unbounded distributed delays, which are more general than those discussed in the previous literature. Some delay-dependent stability criteria are obtained by using the Lyapunov-Krasovskii approach and employing the Newton-Leibniz formula. In addition, the activation functions may be positive, negative, and zero, and they are more general than those usual Lipschitz conditions. The obtained results have comprised and improved the existing results. Meanwhile, such results are expressed in terms of Linear Matrix Inequalities (LMIs), which can be checked easily using the MATlab.LMI toolbox. Finally, four numerical examples are given to illustrate the availab.lity of the proposed results. © 2012 by Binary Information Press.

关键词： Linear matrix inequalities

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Online path planning for UAV low-altitude penetration based on an improved differential evolution algorithm

Beijing Keji Daxue Xuebao/Journal of University of Science a...

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Beijing Keji Daxue Xuebao/Journal of University of Science and technology Beijing 2012年第1期34卷 96-101页

作者： Peng, Zhi-Hong Sun, Lin Chen, Jie School of Automation Beijing Institute of Technology Beijing 100081 China Key Lab. of the Ministry of Education of China for Complex System Intelligent Control and Decision Beijing Institute of Technology Beijing 100081 China

An improved differential evolution algorithm was proposed for solving the online path planning problem of unmanned aerial vehicle (UAV) low-altitude penetration in partially known hostile environments. The algorithm adopts von Neumann topology and improves its structure to maintain the diversity of the population, prevent the population from falling into local optima in the early evolution and speed up the convergence rate in the later evolution as well. The mutation operator of differential evolution is improved to speed up the convergence rate of the algorithm, so that the optimal solution of the multi-objective optimization problem can be found quickly;the coding method combined the absolute Cartesian coordinates with the relative polar coordinates is used to improve the searching efficiency. The simulation experiment of online path planning for UAV low-altitude penetration shows that the proposed algorithm has a better performance than the unimproved differential evolution algorithm.

关键词： Antennas

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A novel control strategy for quadruped robot walking over irregular terrain

A novel control strategy for quadruped robot walking over ir...

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2011 IEEE 5th International Conference on Robotics, Automation and Mechatronics, RAM 2011

作者： Yin, Peng Wang, Pengfei Li, Mantian Sun, Lining State Key Lab. of Robotics and System Harbin Institute of Technology China

ISBN: (纸本)9781612842509

Quadruped robot has great potential in traversing irregular terrains. Normally its performance relies greatly on the accuracy of local terrain data that the onboard sensor system acquired. In order to reduce its reliance on terrain information for locomotion control to the minimum, in this paper we intend to provide a method to intensify its walking adaptability by endowing the robot with blind walking ability. Based on the transfer strategies provided in the paper, the rough terrain walking problem could be simplified as common slope walking condition, and motion planning could be achieved via some basic criteria. Impedance control is implemented to reduce impact when foot stride to ground. On purpose of coping with foot slippage which would cause robot to fall, reflex control strategy is applied and tested. Via simulation we tested the control strategy and the feasibility was verified. © 2011 IEEE.

关键词： Motion planning

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A comparison study of candidate generation for Chinese word segmentation

A comparison study of candidate generation for Chinese word ...

引用

7th International Conference on Natural Language Processing and Knowledge Engineering, NLP-KE 2011

作者： Zhang, Kaixu Sun, Maosong State Key Lab. of Intelligent Technology and Systems Department of Computer Science and Technology Tsinghua University Beijing 100084 China

ISBN: (纸本)9781612847283

Chinese word segmentation can be implemented in a coarse-to-fine schema. In such schema, a candidate set containing multiple segmentations of a sentence (rather than only one segmentation) is used as the output of a coarse-grained CWS model. Then a more sophisticated CWS model or other models of downstream tasks will reconsider all the segmentations in the candidate set to determine the best segmentation. This paper discussed and compared three candidate generation methods, namely boundary level method, word level method and sentence level method, in a unified form. The oracle F1-measures of the candidate sets of these methods were compared. The performances were also compared in a joint CWS and POS-tagging task. The results showed that the word level method has the best performance among these three candidate generation methods. Results also showed that the coarse-to-fine schema outperforms the pipeline schema in which only one segmentation is used for the downstream task and the joint schema in which all possible segmentation is used for the downstream task. Moreover, the speed of the coarse-to-fine schema is closed to the speed of the pipeline schema and much higher than the speed of the joint schema. © 2011 IEEE.

关键词： Pipelines

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Simulation of water spraying lateral distribution in synchronously controlled moving linear move irrigators

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Paiguan Jixie Gongcheng Xuebao/Journal of Drainage and Irrigation Machinery Engineering 2012年第5期30卷 604-608页

作者： Yuan, Yanwei Zhang, Xiaochao Wu, Caicong Fan, Yuntao State Key Lab. of Soil Plant Machinery System Technology Chinese Academy of Agricultural Mechanization Sciences Beijing 100083 China Institute of Remote Sensing and GIS Peking University Beijing 100871 China

Rainfall distribution and water trajectory information was acquired through a single nozzle indoor test. A three-dimensional model of water motion was built by using the virtual reality technology, such as three-dimensional modeling and particle system etc. The optimal driving speed was realized by studying the uniformity of water distribution across the lateral direction when a linear move irrigator is being moved ahead. The configuration of sprinklers was optimized by analyzed effects of the distance between adjacent two sprinklers and the height of sprinklers on the uniformity of lateral distribution of water. According to the water distributions measured by employing a single sprinkler, a water distribution model was built for a linear move irrigator. Field tests and simulation results showed that a variable vertical irrigation could be got by changing the frequency of the motors, while the uniformity of irrigation in the lateral direction depended on the type and pressure of sprinkler. The maximum relative error between field test and simulation is 3.39%, suggesting the simulation model is reliable. This outcome provides a means of investigating effect of irrigation and parameter optimization for a linear move irrigator.

关键词： Virtual reality

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