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Size Model of Critical Temperature for Grain Growth in Nano V and Au

Chinese Physics Letters 2011年第8期28卷 24-27页

作者： LU Yun-Bin LIAO Shu-Zhi PENG Hao-Jun ZHANG Chun ZHOU Hui-Ying XIE Hao-Wen OUYANG Yi-Fang ZHANG Bang-Wei Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Education Department of PhysicsHunan Normal UniversityChangsha 410081 College of Mathematics and Physics University of South ChinaHengyang 421001 College of Mathematics and Computer Science Hunan Normal UniversityChangsha 410081 Computer and Information Engineering School Central South University of Forestry and TechnologyChangsha 410004 Department of Physics Guangxi UniversityNanning 530004 Department of Applied Physics Hunan UniversityChangsha 410082 International Centre for Materials Physics Chinese Academy of SciencesShenyang 110015

The intrinsic thermodynamical factors that dominate the stability of nanocrystallines are investigated through the microcosmic process of grain *** results suggest that nanocrystallines grows at a certain temperature and the critical temperature is determined by the vacancy formation energy and diffusion activation energy of the *** on the hypothesis,a simple model is proposed to predict the size-dependent critical temperature of grain *** this model,we investigate the thermal stability of nanocrystallines V and Au,compared with the results *** is shown that the critical temperature decreases with decreasing size,showing an evident size *** research reveals that the thermal stability is dependent on the energetic state of the nanocrystallines and the mobility of the inner atoms.

关键词： grain stability size

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Hybrid Optimal control for Aircraft Trajectory Design with a Variable Sequence of Modes

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IFAC Proceedings Volumes 2011年第1期44卷 7238-7243页

作者： Maryam Kamgarpour Manuel Soler Claire J. Tomlin Alberto Olivares John Lygeros Department of Mechanical Engineering University of California at Berkeley USA Department of Statistics and Operations Research URJC 28933 Madrid Spain Department of Electrical Engineering and Computer Sciences University of California at Berkeley USA Automatic Control Laboratory ETH Zurich CH-8092 Switzerland

Abstract The problem of aircraft trajectory planning is formulated as a hybrid optimal control problem. The aircraft is modeled as a switched system, that is, a class of hybrid dynamical systems. The sequence of modes, the switching times, and the inputs for each mode are the control variables. An iterative bi-level optimization algorithm is employed to solve the optimal control problem. At the lower level, given a pre-defined sequence of flight modes, the optimal switching times and the input for each mode are determined. This is achieved by extending the continuous state to include the switching times and then solving a conventional optimal control problem for the extended state. At the higher level, the algorithm modifies the mode sequence in order to decrease the value of the cost function. We illustrate the utility of the problem formulation and the solution approach with two case studies in which short horizon aircraft trajectories are optimized in order to reduce fuel burn while avoiding hazardous weather.

关键词： Optimal control Hybrid Systems Aircraft Operations Aircraft Trajectory Design

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Exploiting Free LUT Entries to Mitigate Soft Errors in SRAM-based FPGAs

Exploiting Free LUT Entries to Mitigate Soft Errors in SRAM-...

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Asian Test Symposium (ATS)

作者： Keheng Huang Yu Hu Xiaowei Li Gengxin Hua Hongjin Liu Bo Liu State Key Laboratory of Computer Architecture Institute of Computing Technology Chinese Academy of Sciences China Beijing Institute of Control Engineering China

As the feature size of FPGA shrinks to nanometers, SRAM-based FPGAs are more vulnerable to soft errors. During logic synthesis, reliability of the design can be improved by introducing logic masking effect. In this work, we observe that there are a lot of not-fully occupied look-up tables (LUTs) after logic synthesis. Hence, we propose a functional equivalent class based soft error mitigation scheme to exploit free LUT entries in the circuit. The proposed technique replaces not fully-occupied LUTs with corresponding functional equivalent classes, which can improve the reliability while preserve the functionality of the design. Experimental results show that, compared with the baseline ABC mapper, the proposed technique can reduce the soft error rate by 21%, and the critical-path delay increase is only 4.25%.

关键词： Table lookup Circuit faults Forward error correction Field programmable gate arrays Vectors Reliability engineering

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Discrete Time Stochastic Hybrid Dynamical Games: Verification & controller Synthesis

Discrete Time Stochastic Hybrid Dynamical Games: Verificatio...

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IEEE Conference on Decision and control

作者： Maryam Kamgarpour Jerry Ding Sean Summers Alessandro Abate John Lygeros Claire Tomlin Department of Mechanical Engineering University of California at Berkeley USA Department of Electrical Engineering and Computer Sciences University of California at Berkeley USA Automatic Control Labratory ETH Zurich Switzerland Delft Center for Systems and Control Delft University of Technology The Netherlands

ISBN: (纸本)9781612848006

This paper presents a framework for analyzing probabilistic safety and reachability problems for discrete time stochastic hybrid systems in scenarios where system dynamics are affected by rational competing agents. In particular, we consider a zero-sum game formulation of the probabilistic reach-avoid problem, in which the control objective is to maximize the probability of reaching a desired subset of the hybrid state space, while avoiding an unsafe set, subject to the worst-case behavior of a rational adversary. Theoretical results are provided on a dynamic programming algorithm for computing the maximal reach-avoid probability under the worst-case adversary strategy, as well as the existence of a maxmin control policy which achieves this probability. The modeling framework and computational algorithm are demonstrated using an example derived from a robust motion planning application.

关键词： state space discrete-time dynamic programming algorithm Unsafe hybrid systems Stochastic System dynamics Frameworks Rational number

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A novel effective ICI self-cancellation method

A novel effective ICI self-cancellation method

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54th Annual IEEE Global Telecommunications Conference: "Energizing Global Communications", GLOBECOM 2011

作者： Wen, Miao-Wen Cheng, Xiang Wei, Xing Ai, Bo Jiao, Bing-Li School of Electronics Engineering and Computer Science Peking University Beijing 100871 China State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong University Beijing 100044 China Key Laboratory of Wireless Sensor Network and Communication Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences 865 Changning Road Shanghai 200050 China School of Information and Electronics Beijing Institute of Technology Beijing 100081 China

ISBN: (纸本)9781424492688

Orthogonal Frequency Division Multiplexing (OFDM) systems may suffer from both carrier frequency offset (CFO) and in-phase/quadrature-phase (I/Q) imbalance at the receiver front end. In this paper, a novel type of intercarrier interference (ICI) self-cancellation method using mirror mapping is proposed to combat these impairment. Based on the proposed novel method and by adopting two widely used mapping operations, we altogether derive two different mirror mapping schemes. Analysis and simulation results verify that the proposed mirror mapping schemes not only inherit the efficiency of the existing self-cancellation schemes in suppressing ICI caused by CFO but also have the ability of compressing or even eliminating IQ imbalance. © 2011 IEEE.

关键词： Mirrors

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Feature referenced tip localization enhanced by probability motion model for AFM based nanomanipulations

Feature referenced tip localization enhanced by probability ...

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2011 IEEE International Conference on Robotics and Biomimetics, ROBIO 2011

作者： Yuan, Shuai Liu, Lianqing Wang, Zhidong Xi, Ning Wang, Yuechao Dong, Zaili Wang, Zhiyu Wang, Zhibo State Key Laboratory of Robotics Shenyang Institute of Automation Chinese Academy of Sciences Shenyang Liaoning Province 110016 China College of Information and Control Engineering Shenyang Jianzhu University Shenyang 110168 China Graduate School of Chinese Academy of Sciences Beijing 100001 China Department of Electrical and Computer Engineering Michigan State University East Lansing MI 48823 United States Department of Advanced Robotics Chiba Institute of Technology Chiba Japan

ISBN: (纸本)9781457721373

The spatial uncertainties of tip positioning due to the nonlinearity of the PZT scanner and thermal drift hinder the further application of the AFM based nanomanipulation. This paper brings forward feature referenced tip localization enhanced by probability motion model to reduce the spatial uncertainties. An improved motion model is probabilistically built by incorporating the PI model, the creep model and the thermal drift model. For calibrating the accurate model parameters, the statistical experiments are designed and performed. Then the tip position is optimally estimated by combining with a local scan based feature sensing method. The simulation and corresponding experiments are performed to illustrate the validity and feasibility of the calibrated parameters and the algorithm. © 2011 IEEE.

关键词： Micromanipulators

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Frequency Domain Time-Space Decomposition for Efficient Near Field Pressure Computations

Frequency Domain Time-Space Decomposition for Efficient Near...

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2011 IEEE Ultrasonics Symposium (IUS 2011)

作者： E.J. Alles K.W.A. van Dongen R.J. McGough Biomedical Ultrasound Engineering Laboratory Department of Electrical and Computer and Engineering Michigan State University East Lansing MI 48824-1226 Laboratory of Acoustical Imaging and Sound Control Faculty of Applied Sciences Delft University of Technology Delft the Netherlands

ISBN: (纸本)9781457712531

Time-Space Decomposition is one of the most efficient transient near-field pressure simulation schemes available for piston transducers, but suffers from two drawbacks. Every signal has to be individually programmed, and not all signals can be rewritten into the desired decomposition. In this work, an extension of the above method is presented in which the excitation signal is first transformed into the frequency domain and each of the frequency components is used as separate excitation signal. Spectral clipping is applied to reduce the number of terms and hence the computation time. By removing energy from the problem, the efficiency increases at the cost of accuracy. The achieved accuracy in the transient pressure field is known a priori and thus can be set prior to the actual simulation. Pressure fields obtained with the proposed method are compared to those obtained with Field II and with reference solutions obtained with an impulse response method. The proposed method reaches relative errors in the transient pressure field as low as 10~(-6) and is significantly more accurate than Field II which has difficulties reaching errors below 10~(-3). The time to reach an error of 10~(-2) using the proposed method is more than 100 × shorter than the time required by Field II to reach that same error.

关键词： Acoustics

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Exploiting motion priors in visual odometry for vehicle-mounted cameras with non-holonomic constraints

Exploiting motion priors in visual odometry for vehicle-moun...

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2011 IEEE/RSJ International Conference on Intelligent Robots and Systems

作者： Davide Scaramuzza Andrea Censi Kostas Daniilidis GRASP laboratory Department of Computer and Information Science School of Engineering and Applied Science University of Pennsylvania Philadelphia USA GRASP laboratory University of Pennsylvania USA Control and Dynamical Systems Department Division of Engineering and Applied Sciences California Institute of Technology Pasadena USA

This paper presents a new method to estimate the relative motion of a vehicle from images of a single camera. The biggest problem in visual motion estimation is data association; matched points contain many outliers that must be detected and removed so that the motion can be estimated accurately. A very established method for robust motion estimation in the presence of outliers is the five-point RANSAC algorithm. Five-point RANSAC operates by generating motion hypotheses from randomly-sampled minimal sets of five-point correspondences. These hypotheses are then tested against all data points and the motion hypothesis that after a given number of iterations returns the largest number of inliers is taken as the solution to the problem. A typical drawback of RANSAC is that the number of iterations required to find a suitable solution grows exponentially with the number of outliers, often requiring thousands of iterations for typical data from urban environments. Another problem is that - due to its random nature - sometimes the found solution is not the “best” solution to the motion estimation problem. In this paper, we describe an algorithm for relative motion estimation in the presence of outliers, which does not rely on RANSAC. Contrary to RANSAC, motion hypotheses are not generated from randomly-sampled point correspondences, but from a “proposal distribution” that is built by exploiting the vehicle non-holonomic constraints. We show that not only is the proposed algorithm significantly faster than RANSAC, but that the returned solution may also be better in that it favors the underlying motion model of the vehicle, thus overcoming the typical limitations of RANSAC. Additionally, the proposed algorithm provides the likelihood of the motion estimate, which can be very useful in all those applications where a probability distribution of the position of the vehicle is required (e.g., SLAM). Finally, the performance of the proposed method is compared to that of the sta

关键词： Vehicles Cameras Proposals Motion estimation Wheels Urban areas Three dimensional displays

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Energy provisioning in wireless rechargeable sensor networks

Energy provisioning in wireless rechargeable sensor networks

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IEEE Annual Joint Conference: INFOCOM, IEEE computer and Communications Societies

作者： Shibo He Jiming Chen Fachang Jiang David K.Y. Yau Guoliang Xing Youxian Sun State Key Laboratory of Industrial Control Technology University of Zhejiang Hangzhou China Department of Computer Sciences Purdue University West Lafayette IN USA Department of Computer Science and Engineering Michigan State University East Lansing MI USA

ISBN: (纸本)9781424499199

Wireless rechargeable sensor networks (WRSNs) have emerged as an alternative to solving the challenges of size and operation time posed by traditional battery-powered systems. In this paper, we study a WRSN built from the industrial wireless identification and sensing platform (WISP) and commercial off-the-shelf RFID readers. The paper-thin WISP tags serve as sensors and can harvest energy from RF signals transmitted by the readers. This kind of WRSNs is highly desirable for indoor sensing and activity recognition, and is gaining attention in the research community. One fundamental question in WRSN design is how to deploy readers in a network to ensure that the WISP tags can harvest sufficient energy for continuous operation. We refer to this issue as the energy provisioning problem. Based on a practical wireless recharge model supported by experimental data, we investigate two forms of the problem: point provisioning and path provisioning. Point provisioning uses the least number of readers to ensure that a static tag placed in any position of the network will receive a sufficient recharge rate for sustained operation. Path provisioning exploits the potential mobility of tags (e.g., those carried by human users) to further reduce the number of readers necessary: mobile tags can harvest excess energy in power-rich regions and store it for later use in power-deficient regions. Our analysis shows that our deployment methods, by exploiting the physical characteristics of wireless recharging, can greatly reduce the number of readers compared with those assuming traditional coverage models.

关键词： Wireless communication Wireless sensor networks RF signals Mathematical model Radiofrequency identification Antennas

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An ACP-based framework for occupants safety evacuation under fire in high-rise buildings

An ACP-based framework for occupants safety evacuation under...

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IEEE International Conference on Service Operations and Logistics, and Informatics, SOLI

作者： Yu-Ling Hu Ding Wen Xi-Wei Liu School of Electric and Information Engineering Beijing University of Civil Engineering and Architecture Beijing China Beijing Key Laboratory of Automatic Control System School of Automation Beijing Institute of Technology Beijing China Research Center of Military Computational Experiments and Parallel Systems Technology National University of Defense Technology Changsha China Institute of Automation Chinese Academy and Sciences Beijing China

Because the structure and function of a high-rise building is complex and the density of occupants in it is high, fire safety is still a worldwide difficult problem. Safety and timely evacuation is an important issue under fire in the high-rise buildings. Because it is impossible in fact to do experiments about fire safety evacuation in high-rise buildings, in this paper, a research framework based on the artificial system, computational experiments, and parallel excution (ACP) theory is proposed. First, an evacuation process is considered to compose of two stages including pre-evacuation stage and evacuation stage. Second, artifical men with recognition functions based agent technology is proposed. Finally, computational experiments are designed by using an orthogonal experiment table, and experiment procedure of pre-evacuation stage is given. The idea of systimatic research about the influence of fire control facilities to evacuation is also proposed.

关键词： Fires Computational modeling Buildings

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