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Multi-path routing scheme integrated with network coding in low earth orbit satellite networks

Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) 2007年第5期38卷 950-955页

作者： Yang, Lin Zheng, Gang School of Electronic Science and Engineering National University of Defense Technology Changsha 410073 China National Key Laboratory of Integrated Information System Technology Institute of Software Chinese Academy of Sciences Beijing 100080 China

Inter-satellite links have characters of time-varying, unreliability and intermittent-connecting, so that applying the multi-path routing in the low earth orbit (LEO) satellite networks can make message disorder and message loss. A multi-path routing scheme integrated with network coding was proposed to solve this problem. It is proved that with the same multi-path number and path message loss rate, the scheme outperforms the traditional multi-path routing in terms of message delivery rate. Moreover, the performances of both schemes were evaluated by the extended ns-2 software in terms of message delivery rate under the conditions of different multi-path numbers, link message loss rates and redundancy factors. The result validates the theory analysis and shows that the scheme can efficiently improve the reliability and save the onboard communication resources as well as enhance the error control of multi-path routing with certain ranges of message loss.

关键词： Satellite links

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BLOOD FLOW AND MACROMOLECULAR TRANSPORT IN CURVED BLOOD VESSELS

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Applied Mathematics and Mechanics(English Edition) 2006年第9期27卷 1223-1231页

作者：魏兰温功碧谭文长 Department of Mechanics and Engineering Science State Key Laboratory for Turbulence and Complex System Peking University Beijing 100871 P. R. China Institute of Applied Physics and Computational Mathematics Beijing 100088 P. R. China Department of Mechanics and Engineering Science State Key Laboratory for Turbulence and Complex System Peking University Beijing 100871 P. R. China

A numerical analysis of the steady/pulsatile flow and macromolecular （such as LDL and Albumin） transport in curved blood vessels was carried out. The computational results predict that the vortex of the secondary flow is time-dependent in the aortic arch. The concentration of macromolecule concentrates at the region of sharp curve, and the wall concentration at the outer part is higher than that at the inner part. Atherosclerosis and thrombosis are prone to develop in such regions with sharp flow.

关键词： curved blood vessels blood flow macromolecular transport atherosclerosis

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Collaborative filtering recommendation algorithm based on cloud model

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Ruan Jian Xue Bao/Journal of software 2007年第10期18卷 2403-2411页

作者： Zhang, Guang-Wei Li, De-Yi Li, Peng Kang, Jian-Chu Chen, Gui-Sheng State Key Laboratory of Software Development Environment Beihang University Beijing 100083 China Institute of Electronic System Engineering Beijing 100840 China Information Security Center Shenzhen Graduate School Harbin Institute of Technology Shenzhen 518055 China School of Computer Science and Technology Shandong Jianzhu University Ji'nan 250101 China

Recommendation system is one of the most important technologies applied in e-commerce. Similarity measuring method is fundamental to collaborative filtering algorithm, and traditional methods are inefficient especially when the user rating data are extremely sparse. Based on the outstanding characteristics of Cloud Model on the process of transforming a qualitative concept to a set of quantitative numerical values, a novel similarity measuring method, namely the likeness comparing method based on cloud model (LICM) is proposed in this paper. LICM compares the similarity of two users on knowledge level, which can overcome the drawback of attributes' strictly matching. This work analysis traditional methods throughly and puts forward a novel collaborative filtering algorithm, which is based on the LICM method. Experiments on typical data set show the excellent performance of the present collaborative filtering algorithm based on LICM, even with extremely sparsity of data.

关键词： Electronic commerce

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Intermediate processes and critical phenomena: Theory, method and progress of fractional operators and their applications to modern mechanics

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Science China(Physics,Mechanics & Astronomy) 2006年第3期49卷 257-272页

作者： XU Mingyu1 & TAN Wenchang2 1. Institute of Applied Mathematics, School of Math & system Science, Shandong University, Jinan 250100, China 2. State key laboratory of Turbulence and complex systems & Department of Mechanics and engineering Science, Peking University, Beijing 100871, China Institute of Applied Mathematics School of Math & System Science Shandong University Jinan 250100 China State Key Laboratory of Turbulence Complex Systems & Department of Mechanics Engineering Science Peking University Beijing 100871 China

From point of view of physics, especially of mechanics, we briefly introduce fractional operators (with emphasis on fractional calculus and fractional differential equa- tions) used for describing intermediate processes and critical phenomena in physics and mechanics, their progress in theory and methods and their applications to modern me- chanics. Some authors’ researches in this area in recent years are included. Finally, prospects and evaluation for this subject are made.

关键词： fractional operators,intermediate processes,critical phenomena,modern mechanics

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PIV observation of instantaneous velocity structure of lock release gravity currents in the slumping phase

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Communications in Nonlinear Science and Numerical Simulation 2006年第2期11卷 262-270页

作者： Zhu, J.B. Lee, C.B. Chen, G.Q. Lee, J.H.W. Department of Mechanics and Engineering Science State key Laboratory for Turbulence and Complex System Peking University Beijing 100871 China Deparment of Civil Enginering University of Hong Kong Hong Kong Hong Kong

The experiments of lock release gravity currents were performed in a rectangular channel with salt water and fresh water. The spreading law of the salt water is validated by using a digital video to record the progress of the current. Detailed instantaneous velocity structure of lock release gravity currents in the slumping phase was studied experimentally with particle image velocimetry (PIV). The time variation of the spatial distribution of velocity and vorticity is obtained, which shows some qualitative characters of the current as well as the effects of the bottom boundary layer and upper mixing layer. © 2004 Elsevier B.V. All rights reserved.

关键词： Gravitation

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Speed sensorless control with neuron MARS estimator of an induction machine

Speed sensorless control with neuron MARS estimator of an in...

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2006 2nd International Conference on Power Electronics systems and Applications, ICPESA

作者： Lei, Dong Dong, Yang Xiaozhong, Liao Department of Automatic Control Engineering Beijing Institute of Technology Beijing China Key Laboratory of Complex System Intelligent Control and Decision Ministry of Education Beijing China

ISBN: (纸本)9623675445

In the high speed range, vector control of rotor flux orientation of an induction machine implements good perfornance. However, the perfornance in low speed rang deteriorates because of the inaccurate estimation of rotor flux and speed. In this paper, modified voltage model for rotor flux estimation and neuron model-reference adaptive system (MARS) for speed estimation are used to improve the perfornance of speed sensorless vector control. To improve the accuracy of rotor flux estimation, the stator resistance is identified on-line. The experimental results show that the proposed scheme yields improved perfornance in low speed range.

关键词： Induction machine

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Transformation cyclic damage of near-equiatomic Ni-Ti

Transformation cyclic damage of near-equiatomic Ni-Ti

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作者： Liu, Yinong Zheng, Yufeng Mahmud, Abdus Laeng, Jamaluddin School of Mechanical Engineering University of Western Australia Crawley WA 6009 Australia State Key Laboratory for Turbulence and Complex System Department of Mechanics and Engineering Science Peking University Beijing 100871 China

Near-equiatomic Ni-Ti alloys are known to exhibit shape memory effect associated with a B2↔B19' martensitic transformation. These alloys are often used in various cyclic modes in application, typically as actuators and sensors. The B2↔B19' martensitic transformation in Ni-Ti is accompanied with a large lattice distortion. Cycling through this transformation, induced thermally, mechanically or by the combination of the two, is found to cause structural damage to the alloys, hence changes their functional properties. This study investigates the effect of transformation cycling and heat treatment on the property stability of near-equiatomic Ti-Ni. It was found that in the case of thermally induced transformation cycling, incomplete transformation cycles caused less structural damage to the matrix than full transformation cycles whereas in the case of mechanically induced transformation cycling via pseudoelasticity in tension, partial or full transformation cycling caused similar property changes. The indifference of the case of pseudoelastic cycling is attributed to the localisation of the deformation, commonly known as the Lüders-type deformation.

关键词： Intermetallics

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Modeling based on MOGA and the dynamic Ε -SVM for fermentation process

Modeling based on MOGA and the dynamic Ε -SVM for fermentat...

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6th World Congress on Intelligent Control and Automation, WCICA 2006

作者： Xuejin, Gao Pu, Wang Chongzheng, Sun Yating, Zhang Huiqing, Zhang Yi, Jianqiang College of Electronic Information and Control Engineering Beijing University of Technology Beijing 100022 China Key Laboratory of Complex System and Intelligence Science Chinese Academy of Sciences Beijing 100033 China

ISBN: (纸本)1424403324

To found the suitable models to describe the behavior of biochemistry systems, the dynamic Ε -SVM method was proposed on the basis of SVM. Each training sample uses different error. The existed methods for selecting the parameters of SVM not only consume time, but also are difficult to find the optimal parameters. The optimal parameters were automatically decided by using multi-object Genetic Algorithm (MOGA). A new modeling method that combined MOGA with the dynamic Ε -SVM was presented. The model for penicillin titer preestimate was developed by it in Matlab6.5 with data collected from real plant. The model possesses the strong capability of fitting and generalization. Experiments show that the dynamic Ε -SVM is superior to the standard SVM modeling method. MOGA is very feasible and efficient too. ©2006 IEEE.

关键词： Fermentation

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Correlation between non-Gaussian statistics of a scalar and its dissipation rate in turbulent flows

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Physical Review E 2006年第1期74卷 016301-016301页

作者： Jianchun Mi State Key Laboratory for Turbulence and Complex System College of Engineering Peking University Beijing 100871 People’s Republic of China

This paper reports an experimental study on the correlation between the deviation from Gaussianity of the probability density function (PDF) of a fluctuating scalar and the dependence of the scalar dissipation on the scalar itself in turbulent flows. The study demonstrates that the departure of the scalar PDF from Gaussianity reflects the degree to which the dissipation rate depends statistically on the scalar. Of important significance, present results obtained from wake and jet flows, together with those deduced from previous work on various turbulent flows, appear to point to a generic expression for the total correlation. This expression suggests that the analytical result of O’Brien and Jiang [Phys. Fluids A 3, 3121 (1991)], derived for homogeneous turbulence, should be also valid for inhomogeneous turbulence. That is, the statistical independence of the scalar dissipation and the scalar itself appears to act as the sufficient and necessary condition for the scalar PDF to be Gaussian in any stationary turbulence. It follows that the independence assumption, often used in combustion modeling, is reasonable only in the flow region where the scalar PDF is closely Gaussian.

关键词： PASSIVE SCALAR PROBABILITY-DISTRIBUTIONS HOMOGENEOUS TURBULENCE BENARDCONVECTION JOINT STATISTICS HELIUM-GAS ROUND JET TEMPERATURE FIELD

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REDUCTION APPROACHES FOR VIBRATION CONTROL OF REPETITIVE STRUCTURES

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Applied Mathematics and Mechanics(English Edition) 2006年第5期27卷 637-644页

作者：陈伟民孙东昌王大钧魏建萍仝力勇王泉 State Key Laboratory for Turbulence and Complex System/Department of Mechanics and Engineering Science Peking UniversityBeijing 100871P. R. China Division of Engineering Sciences Institute of MechanicsChinese Academy of SciencesBeijing 100080P. R. China School of Aerospace Mechanical and Mechatronic EngineeringUniversity of SydneySydneyNSW2006Australia Mechanical Materials and Aerospace Engineering DepartmentUniversity of Central FloridaOrlandoFL 32816USA

The reduction approaches are presented for vibration control of symmetric, cyclic periodic and linking structures. The condensation of generalized coordinates, the locations of sensors and actuators, and the relation between system inputs and control forces are assumed to be set in a symmetric way so that the control system posses the same repetition as the structure considered. By employing proper transformations of condensed generalized coordinates and the system inputs, the vibration control of an entire system can be implemented by carrying out the control of a number of sub-structures, and thus the dimension of the control problem can be significantly reduced.

关键词： vibration control of structures repetitive structure symmetric structure cyclic periodic structure linking structure

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