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An Adaptive Channel Estimation Technique in MIMO OFDM Systems

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Journal of Electronic science and Techno.ogy of China 2008年第3期6卷 313-316页

作者： Pei-Sheng Pan Bao-Yu Zheng School of Communication ＆ Information Engineering University of Nanjing University of Posts and Telecommunications Nanjing 210003 China

In this paper, an adaptive channel estimation for MIMO OFDM is proposed. A set of pilot tones first are placed in each OFDM block, then the channel frequency response of these pilot tones are adaptively estimated by reeursive least squares （RLS） directly in frequency domain no. in time domain. Then after the estimation of the channel frequency response of pilot tones, to obtain the channel frequency response of data tones, a new interpolation method based on DFT different from traditional linear interpolation method according to adjacent pilot tones is proposed. Simulation results show good performance of the technique.

关键词： Adaptive frequency domain MIMO squares. channel estimation OFDM recursive least

Tree Expressions for Information Systems

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Journal of Computer science & Techno.ogy 2007年第2期22卷 297-307页

作者：赵岷韩素青王珏 NEC Research China Beijing 100080 China Department of Mathematics Taiyuan Normal University Taiyuan 030012 China Institute of Automation Chinese Academy of Sciences Beijing 100080 China

The discernibility matrix is one of the most important approaches to computing positive region, reduct, core and value reduct in rough sets. The subject of this paper is to develop a parallel approach of it, called ＂tree expression＂. Its computational complexity for positive region and reduct is O（m^2 × n） instead of O（m × n^2） in discernibility-matrix-based approach, and is no. over O（n^2） for other concepts in rough sets, where rn and n are the numbers of attributes and objects respectively in a given dataset （also called an ＂information system＂ in rough sets）. This approach suits information systems with n ≥ m and containing over one million objects.

关键词： algorithms tree expression reduct theory

PARALLEL SIMULTANEOUS STABILIZATION OF A SET OF PORT-CONTROLLED HAMILTONIAN SYSTEMS SUBJECT TO ACTUATOR SATURATION

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Journal of Systems science & Complexity 2011年第1期24卷 120-139页

作者： Airong WEI Yuzhen WANG Xiaoming HU School of Control science and Engineering Shandong University Jinan 250061 ChinaOptimization and Systems Theory Royal Institute of Technology SE-10044 Stockholm Sweden School of Control science and Engineering Shandong University Jinan 250061 China Optimization and Systems Theory Royal Institute of Technology SE-100 44 Stockholm Sweden ACCESS Linnaeus Center Royal Institute of Technology SE-100 44 Stockholm Sweden

This paper investigates parallel simultaneous stabilization （PSS） of a set of multi-input no.linear Port-Controlled Hamiltonian （PCH） systems subject to actuator saturation （AS）, and proposes a number of results on the design of PSS controllers for the PCH systems with AS. Firstly, the case of two PCH systems with AS is studied. Exploring the special property of the saturation no.linearity and the structural properties of dissipative Hamiltonian system, the two systems are combined to generate an augmented PCH system, with which some results on the control design are then obtained. When there are external disturbances in the two systems, a robust PSS controller is designed for the systems. Secondly, the case of more than two PCH systems with AS is investigated, and several new results are proposed for the PSS problem. Finally, two illustrative examples are presented to show that the stabilization controllers obtained in this paper work very well.

关键词： Actuator saturation PCH system robust parallel simultaneous stabilization

Birkhoffian Symplectic Scheme for a Quantum System

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Communications in Theoretical Physics 2010年第3期53卷 476-480页

作者：苏红玲 Department of Mathematics Renmin University of China

In this paper, a classical system of ordinary differential equations is built to describe a kind of n-dimensional quantum systems. The absorption spectrum and the density of the states for the system are defined from the points of quantum view and classical view. From the Birkhoffian form of the equations, a Birkhoffian symplectic scheme is derived for solving n-dimensional equations by using the generating function method. Besides the Birkhoffian structure- preserving, the new scheme is proven to preserve the discrete local energy conservation law of the system with zero vector f . Some numerical experiments for a 3-dimensional example show that the new scheme can simulate the general Birkhoffian system better than the implicit midpoint scheme, which is well kno.n to be symplectic scheme for Hamiltonian system.

关键词： quantum system Birkhoffian symplectic scheme local energy conservation law perturbed Hamiltonian system

MORAL HAZARD STRATEGY AND QUALITY CONTRACT DESIGN IN A TWO-ECHELON SUPPLY CHAIN

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Journal of Systems science and Systems Engineering 2011年第1期20卷 70-86页

作者： Lilong ZHU Jianxin YOU School of Econo.ics and Management Tongji University Shanghai 200092 China i University Shanghai 200092 China

Based on game theory and principal-agent theory, this paper focuses on how to control product quality and design quality contract in supply chain when moral hazard exists. We set up the supplier and buyer＇s expected profits function model, in which the supplier makes production process investment-level decision and decides on the product quality prevention level, whereas the buyer makes quality evaluation decision and decides on the product quality inspection level. The supplier with a moral hazard of reducing investment level may lack investment in the production process; thus, the buyer will pay the information rent to incentivize the supplier to improve the investment level. The buyer creates the moral hazard of exaggerating the product quality defective rate, who may overinvest in the inspection process. We use the optimal condition to solve supplier＇s first-best investment level, product quality prevention level, and buyer＇s first-best quality inspection level, internal penalty, and apportionment ratio of external failure cost. We also conduct a simulation test that shows the following： When the supplier improves its investment level, its product quality prevention level will increase, and the buyer＇s quality inspection level will decrease. With the improvement in the buyer＇s product quality inspection level, its internal penalty will increase, and the supplier＇s external failure cost will also increase while its expected profits will decrease. Hence, the buyer will design an incentive contract, the expected profits of which will increase, and the whole supply chain＇s joint expected profits function may become an inverse U shape. Finally, we develop a simulation example and propose suggestions for quality control strategy and contract design in the supply chain under the conditions of asymmetric information.

关键词： Supply chain moral hazard quality control contract design principal-agent relationship

Analysis of Infrared Divergence in OZI-Forbidden Decays of Orthoquarkonia

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Communications in Theoretical Physics 2009年第6期51卷 1101-1106页

作者： ZHAO Shu-Min PANG Xue-Xia LIU Li-Quan LI Yong-Hui Department of Physics and Techno.ogy Hebei University Baoding 071002 China Basic Department North China Institute of Aerospace Engineering Langfang 065000 China

It is interesting to investigate the OZI-forbidden decays of orthoquarkoknium, J/ψ→γπ^0（γη,γη′）, J/ψ→π^＋π^-（π^0π^0）. At first glance, there is infrared divergence in the above processes. In this work, to clear the mist we use the factorization method with the light cone wavefunction of the final state light meson. We prove straightforwardly that the infrared divergence can be eliminated completely.

关键词： OZI-forbidden infrared divergence factorization

Application of the VOF method based on unstructured quadrilateral mesh

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Journal of Marine science and Application 2008年第1期7卷 24-32页

作者：及春宁师颖 Tianjin Key Laboratory of Harbor & Ocean Engineering Tianjin University Huahui Architectural Design & Engineering Co. Ltd.

To simulate two-dimensional free-surface flows with complex boundaries directly and accurately, a no.el VOF (Volume-of-fluid) method based on unstructured quadrilateral mesh is presented. Without introducing any complicated boundary treatment or artificial diffusion, this method treated curved boundaries directly by utilizing the inherent merit of unstructured mesh in fitting curves. The PLIC (Piecewise Linear Interface Calculation) method was adopted to obtain a second-order accurate linearized reconstruction approximation and the MLER (Modified Lagrangian-Eulerian Re-map) method was introduced to advect fluid volumes on unstructured mesh. Moreover, an analytical relation for the interface’s line constant vs. the volume clipped by the interface was developed so as to improve the method’s efficiency. To validate this method, a comprehensive series of large straining advection tests were performed. Numerical results provide convincing evidences for the method’s high volume conservative accuracy and second-order shape error convergence rate. Also, a dramatic improvement on computational accuracy over its unstructured triangular mesh counterpart is checked.

关键词： VOF unstructured quadrilateral mesh PLIC MLER

A Portable Fall Detection and Alerting System Based on k-NN Algorithm and Remote Medicine

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China Communications 2015年第4期12卷 23-31页

作者： HE Jian HU Chen School of Software Engineering Beijing University of Technology

This paper presents information on a portable fall detection and alerting system mainly consisting of a custom vest and a mobile smart phone. A wearable motion detection sensor integrated with tri-axial accelerometer, gyroscope and Bluetooth is built into a custom vest worn by elderly. The vest can capture the reluctant acceleration and angular velocity about the activities of daily living(ADLs) of elderly in real time. The data via Bluetooth is then sent to a mobile smart phone running a fall detection program based on k-NN algorithm. When a fall occurs the phone can alert a family member or health care center through a call or emergent text message using a built in Global Positioning System. The experimental results show that the system discriminates falls from ADLs with a sensitivity of 95%, and a specificity of 96.67%. This system can provide remote monitoring and timely help for the elderly.

关键词： telemedicine fall detection k-NN smart phone bluetooth

Modes competition in a birefringence cavity laser with optical feedback

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Chinese Optics Letters 2005年第12期3卷 694-697页

作者：刘刚张书练徐亭万新军 State Key Laboratory of Precision Measurement Techno.ogy and Instruments Department of Precision InstrumentsTsinghua UniversityBeijing 100084

The modes competition characteristics in birefringence cavity laser are studied in different regions of the gain curve. The mode＇s intensity modulation depth with modes competition is much deeper than that without modes competition. When the average intensities of the two modes are comparable, the intensity modulation depth of either mode reaches its maximum. Modes competition can do more contribution to the mode＇s modulation depth than the percentage of light reflected back into the laser cavity does. These characteristics can be used to improve the sensitivity of an optical feedback system. A modes competition factor is introduced to either mode＇s intensity expression which describes the laser intensity more precisely.

关键词： Birefringence Feedback Laser modes Modulation