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International Journal of Database Theory and Application 2014年第5期7卷 1-16页

作者： Wan, Jian Hong, Xiaolong Zhang, Jinlin School of Computer Science and Technology Hangzhou Dianzi University Hangzhou China Key Laboratory of Complex System Modeling and Simulation Ministry of Education Hangzhou China Electric Engineering School Zhejiang University Hangzhou China

Data generated by various fields are increasing exponentially and thus results in challenges for data performances in both scales of diversity and complexity. The problem how to solve the bottlenecks of low-bandwidth networks has been of fatal significance for all kinds of network status. We present a new approach on improved optimization for data disaster recovery system (DDRS) over low-bandwidth networks that not only aims to improve the defects and deficiencies of mainstream DDRS but also helps ensure the reliable network resources for operators to conduct multi-services. A novel bandwidth self-adaptive approach (BSAA) for data packing replication was essentially established to make contribution to the integral performance improvement. A Hidden Markov Model (HMM) for predicting network status was also built to ensure system availability and stability. Experiments showed that the DDRS over low-bandwidth networks named InfoDr can effectively optimize the workload with better performance and better application self-adaptability for multi-services.

关键词： Hidden Markov models

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Predictions of a supersonic jet-in-crossflow: Comparisons among CFD solvers and with experiment 32

Predictions of a supersonic jet-in-crossflow: Comparisons am...

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32nd AIAA Applied Aerodynamics Conference 2014

作者： DeSpirito, James Kennedy, Kevin D. Mikkelsen, Clark D. Chaplin, Ross A. U.S. Army Research Laboratory Aberdeen Proving Ground RDRL-WML-E Weapons and Materials Resarch Directorate MD 21005 United States U.S. Army Aviation and Missile Research Development and Engineering Center RDMR-SSM-A System Simulation and Development Directorate Redstone Arsenal AL 35898 United States Defence Science and Technology Laboratory Air and Weapons Systems Fareham Hampshire PO17 6AD United Kingdom

ISBN: (数字)9781624102882

ISBN: (纸本)9781624102882

A supersonic jet interaction flowfield with pressure ratios of 2.8-16.7 exhausting into subsonic and transonic crossflows (Mach 0.5-0.8) was simulated using computational fluid dynamics and compared to experimental particle image velocimetry data. Three independent studies using different Reynolds-averaged Navier-Stokes flow solvers and a variety of turbulence models were used to assess the accuracy level of the predicted downsteam flow physics of the jet interaction problem. Evaluation of the prediction of the downstream flow structure was made via comparisons of the three components of velcocity and turbulent kinetic energy. In general, the predicted jet interaction flowfield was highly sensitive to the turbulence model used, with performance of the turbulence model being dependent on the flow solver, and relatively insensitive to crossflow Mach number in the range investigated.

关键词： Turbulence models

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Thermo-physical performance prediction of the KSC Ground Operation Demonstration Unit for liquid hydrogen

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IOP Conference Series: Materials science and Engineering 2015年第1期101卷

作者： J H Baik W U Notardonato S W Karng I Oh Florida Solar Energy Center University of Central Florida Cocoa FL 32922 USA Cryogenics Test Laboratory Kennedy Space Center FL 32899 USA Center for Urban Energy System Research Korea Institute of Science Technology Seoul 136791 Republic of Korea Green City Technology Institute Korea Institute of Science Technology Seoul 136791 Republic of Korea

NASA Kennedy space Center (KSC) researchers have been working on enhanced and modernized cryogenic liquid propellant handling techniques to reduce life cycle costs of propellant management system for the unique KSC application. The KSC Ground Operation Demonstration Unit (GODU) for liquid hydrogen (LH2) plans to demonstrate integrated refrigeration, zero-loss flexible term storage of LH2, and densified hydrogen handling techniques. The Florida Solar Energy Center (FSEC) has partnered with the KSC researchers to develop thermal performance prediction model of the GODU for LH2. The model includes integrated refrigeration cooling performance, thermal losses in the tank and distribution lines, transient system characteristics during chilling and loading, and long term steady-state propellant storage. This paper will discuss recent experimental data of the GODU for LH2 system and modeling results.

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Adaptive backstepping sliding mode controller for flight simulator based on RBFNN

Adaptive backstepping sliding mode controller for flight sim...

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作者： Wu, Yunjie Liu, Baiting Zhang, Wulong Liu, Xiaodong School of Automation Science and Electrical Engineering Beihang University Beijing 100191 China Science and Technology on Space System Simulation Laboratory Beijing 100854 China

For flight simulator system, a kind of Adaptive Backstepping Sliding Mode Controller (ABSMC) based on Radial Base Function Neural Network (RBFNN) observer is presented. The sliding mode control theory is famous by its characteristic that it is insensitive to the external disturbances and parameters uncertainties. Combining this characteristic with Backstepping method can simplifies the controller design. And the addition of the terminal attractor can make the arrival time shorten greatly. However, too large external disturbances and parameters uncertainties are still not allowed to the system, and the design process of ABSMC does not have the upper bound information of disturbance until a RBFNN observer is designed to solve the problems. The simulation results show that the proposed scheme can improve the tracking precision and reduce the chattering of the control input, and the system has a higher robustness. © 2013 World Scientific Publishing Company.

关键词： Backstepping

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Nanopowder production by gas-embedded electrical explosion of wire

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Chinese Physics B 2013年第4期22卷 350-353页

作者：邹晓兵毛志国王新新江伟华 State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Department of Physics and Chemistry College of Science North China University of Technology

A small electrical explosion of wire （EEW） setup for nanopowder production is constructed. It consists of a low inductance capacitor bank of 2 μF–4 μF typically charged to 8 kV–30 kV, a triggered gas switch, and a production chamber housing the exploding wire load and ambient gas. With the EEW device, nanosize powders of titanium oxides, titanium nitrides, copper oxides, and zinc oxides are successfully synthesized. The average particle size of synthesized powders under different experimental conditions is in a range of 20nm–80nm. The pressure of ambient gas or wire vapor can strongly affect the average particle size. The lower the pressure, the smaller the particle size is. For wire material with relatively high resistivity, such as titanium, whose deposited energy Wd is often less than sublimation energy W s due to the flashover breakdown along the wire prematurely ending the Joule heating process, the synthesized particle size of titanium oxides or titanium nitrides increases with overheat coefficient k （k = W d /Ws ） increasing.

关键词： electrical explosion of wire nanosized powders particle size

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An adaptive image decompression algorithm based on the flight velocity

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Journal of Computational Information systems 2013年第24期9卷 10085-10093页

作者： Bian, Yanshan Zou, Peng Yang, Chao Yu, Ronghuan Graduation School of the Academy of Equipment Beijing 101416 China Science and Technology on Complex Electronic System Simulation Laboratory The Academy of Equipment Beijing 101416 China

This paper presents an adaptive image decompression algorithm based on the changing flight velocity of aircrafts in aerial applications with limited bandwidth, for instance visual navigation systems of helicopters. Based on the observation that there is much visual redundancy for fast-moving viewpoint, our approach dynamically truncates the initially compressed bitstream of an original image tile in an image pyramid to reconstruct the image with different resolutions when real-time flying through the large terrain data. To achieve this, a relationship function between bits per pixel of a reconstructed image tile and the flight velocity of an aircraft is established and then verified by experiments. Also, a lifting wavelet transform based compression algorithm is introduced to meet the requirements of the aforementioned relationship function, accordingly an image compression and decompression framework is designed. Experimental results demonstrate that the proposed algorithm meets the high speed requirement of aerial applications and is very easy of implementation. At the same time, good image quality is evaluated by mean opinion score, which is used to score the decompression images with fast-moving viewpoint. Copyright © 2013 Binary Information Press.

关键词： Redundancy

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Parallel modeling and simulation environment for C4ISR system

Parallel modeling and simulation environment for C4ISR syste...

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2013 International Conference on Vehicle and Mechanical Engineering and Information technology, VMEIT 2013

作者： Liu, De Sheng Guo, Jing Science and Technology on Complex Electronic System Simulation Laboratory The Academy of Equipment Beijing 101416 China

ISBN: (纸本)9783037858202

C4ISR system is the core and base for improving the fight ability of SoS based on information system. Modeling and simulation (M&S) is an efficient method to study on the C4ISR system. In order to meet the requirement for higher simulation performances due to the complexity and incessant development of the C4ISR system, and support parallel modeling and simulation to research on the design, analysis, assessment and application of C4ISR system, a parallel modeling and simulation environment is designed based on high performance computer. The architecture of software and hardware, system constructure and main application pattern are described. Practices proved that the environment solved the problem of complex models and large computing for C4ISR simulation system, and could be used in similar complex simulation system. © (2013) Trans Tech Publications, Switzerland.

关键词： Application programs

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Saturated Scheduling Anti-windup Design: Static Case

Saturated Scheduling Anti-windup Design: Static Case

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第26届中国控制与决策会议

作者： Xiongjun Wu Kun Cai Department of Automation Shanghai Jiao Tong Universityand Key Laboratory of System Control and Information ProcessingMinistry of Education of China The 802 Institute of Shanghai Academy of Space Flight Technology The Eighth Academy of China Aerospace Science and Technology Corporation

A saturation allowed scheduled anti-windup design method is proposed in this paper for the linear systems subject to input saturation. We introduced the scheduled controller design method into the anti-windup scheme, in which a family of controllers are designed. These controllers are activated depending on the response of the system, rather than only considering the worst noise case off-line. Also, the delayed activation scheme is introduced into the scheduled antiwindup mechanism, i.e., the physical actuator is activated when it really need to, and then the most aggressive controller is activated. In this proposed scheme, since the saturation is allowed and no hard constraint is needed to imposed on the controller input, we can makes fuller utilization of the available actuator capacity. The proposed anti-windup scheme provides the system stability and guaranteed peak-to-peak gain. The control strategy is carried out under the scheme of state feedback and the main results are presented in linear matrix inequality forms. The advantage of the proposed saturated allowed scheduling anti-windup scheme against the traditional saturation avoid method is illustrated through a numerical example.

关键词： Actuator saturation,saturated anti-windup,peak-to-peak gain,scheduling control.

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Predicting web service QoS via combining matrix factorization with network location

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International Journal of u- and e- Service, science and technology 2014年第3期7卷 303-318页

作者： Zhou, Li Song, Zhibo Zhai, Suichu Xiao, Tan Yin, Yuyu School of Computer Science and Technology Hangzhou Dianzi University Hangzhou China Key Laboratory of Complex System Modeling and Simulation Ministry of Education China Hangzhou Power Supply Cooperation Hangzhou China Electric Engineering School Zhejiang University Hangzhou China

With the increasing abundance of Web Services across Internet, Quality of Service (QoS)-based service recommendation has become a hot issue. It is necessary to predict the missing values of QoS for service recommendation. Because Web services run on the Internet, their network locations may be anther critical factor for QoS prediction. Although there have existed many works on QoS prediction, few consider the influence of the network locations of users or Web Services. In this paper, we propose a novel collaborative QoS prediction framework with network location-based regularization (NLBR). We first elaborate the popular Matrix Factorization (MF) model for missing values prediction. Then, by taking advantage of the local connectivity between Web services users, we incorporate network location information to identify the neighborhood. We conduct the experiments on a public large-scale real-world QoS dataset, Experiments show that our proposed approaches have the better prediction performance compared with the existed approaches. © 2014 SERSC.

关键词： Web services

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Time-delayed feedback control of a Rossler chaotic dynamical system

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Journal of Information and Computational science 2013年第3期10卷 821-828页

作者： Xu, Changjin Li, Peiluan Guizhou Key Laboratory of Economics System Simulation Guizhou University of Finance and Economics Guiyang 550004 China Department of Mathematics and Statistics Henan University of Science and Technology Luoyang 471003 China

In this paper, the control of Rossler chaotic dynamical system is investigated by time-delayed feedback control method. The controllability and the stability of the equilibriums and local Hopf bifurcation of the system are verified. Some numerical simulations are provided to show the effectiveness of the time-delayed feedback control method. Finally, main conclusions are given. © 2013 by Binary Information Press.

关键词： Hopf bifurcation

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