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A FPC-ROOT Algorithm for 2D-DOA Estimation in Sparse Array

INTERNATIONAL JOURNAL OF ANTENNAS AND PROPAGATION 2016年第6-28期2016卷 1-6页

作者： Zeng, Wenhao Li, Hongtao Zhu, Xiaohua Wang, Chaoyu Nanjing Univ Sci & Technol Nanjing 210094 Jiangsu Peoples R China China Shipbldg 724 Res Inst Nanjing 210003 Jiangsu Peoples R China

To improve the performance of two-dimensional direction-of-arrival (2D DOA) estimation in sparse array, this paper presents a Fixed Point Continuation Polynomial Roots (FPC-ROOT) algorithm. Firstly, a signal model for DOA estimation is established based on matrix completion and it can be proved that the proposed model meets Null Space Property (NSP). Secondly, left and right singular vectors of received signals matrix are achieved using the matrix completion algorithm. Finally, 2D DOA estimation can be acquired through solving the polynomial roots. The proposed algorithm can achieve high accuracy of 2D DOA estimation in sparse array, without solving autocorrelation matrix of received signals and scanning of two-dimensional spectral peak. Besides, it decreases the number of antennas and lowers computational complexity and meanwhile avoids the angle ambiguity problem. computer simulations demonstrate that the proposed FPC-ROOT algorithm can obtain the 2D DOA estimation precisely in sparse array.

关键词： Fixed point theory Direction of arrival estimation (Signal processing) Sparse matrices computer simulation computer algorithms

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Research on HILS Technology Applied on Aircraft Electric Braking System

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JOURNAL OF ELECTRICAL AND computer ENGINEERING 2017年第1期2017卷 1-14页

作者： Zhou, Suying Lin, Hui Li, Bingqiang Northwest Polytech Univ Sch Automat Xian Shaanxi Peoples R China

On the basis of analyzing the real-time feature of hardware-in-the-loop simulation of aircraft braking system, a new simulation method based on MATLAB/RTW (Real-Time Workshop) and DSP is introduced. The purpose of this research is to develop a digital control unit with antilock brake system control algorithm for aircraft braking system using HILS. DSP is used as simulator. Using this method, a detailed mathematical modeling of system is proposed first. Studies on reducing sampling time with model simplification and modeling for applying to I/O interface of DSP and HILS are conducted. Compared with other methods, this method is low cost and convenient to implement. By using these methods, we can complete HIL simulation of aircraft braking under various experimental conditions, modify its control laws, and test its braking performance. The results have demonstrated that this platform has high reliability. The algorithm is verified by real-time closed loop test with HILS system and the results are presented.

关键词： AIRPLANE brakes TECHNOLOGICAL innovations in the aircraft industry HARDWARE-in-the-loop simulation ENGINEERING systems -- computer simulation computer algorithms

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Time-Frequency Analysis Based on Improved Variational Mode Decomposition and Teager Energy Operator for Rotor System Fault Diagnosis

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MATHEMATICAL PROBLEMS IN ENGINEERING 2016年第1期2016卷 1-9页

作者： Liu, Shangkun Tang, Guiji Wang, Xiaolong He, Yuling North China Elect Power Univ Sch Energy Power & Mech Engn Baoding 071000 Peoples R China

A time-frequency analysis method based on improved variational mode decomposition and Teager energy operator (IVMD-TEO) is proposed for fault diagnosis of turbine rotor. Variational mode decomposition (VMD) can decompose a multicomponent signal into a number of band-limited monocomponent signals and can effectively avoid model mixing. To determine the number of monocomponents adaptively, VMD is improved using the correlation coefficient criterion. Firstly, IVMD algorithm is used to decompose a multicomponent signal into a number of monocompositions adaptively. Second, all the monocomponent signals' instantaneous amplitude and instantaneous frequency are demodulated via TEO, respectively, because TEO has fast and high precision demodulation advantages to monocomponent signal. Finally, the time-frequency representation of original signal is exhibited by superposing the time-frequency representations of all the monocomponents. The analysis results of simulation signal and experimental turbine rotor in rising speed condition demonstrate that the proposed method has perfect multicomponent signal decomposition capacity and good time-frequency expression. It is a promising time-frequency analysis method for rotor fault diagnosis.

关键词： TIME-frequency analysis DECOMPOSITION (Mathematics) ROTOR testing computer algorithms computer simulation DEMODULATION (Electronics) CORRELATION (Statistics)

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Simultaneous enhancement and noise reduction of a single low-light image

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IET IMAGE PROCESSING 2016年第11期10卷 840-847页

作者： Zhang, Liang Shen, Peiyi Peng, Xilu Zhu, Guangming Song, Juan Wei, Wei Song, Houbing Xidian Univ Sch Software Xian 710071 Peoples R China Xian Univ Technol Dept Comp Sci & Engn Xian 710048 Peoples R China West Virginia Univ Dept Elect & Comp Engn Montgomery WV 25136 USA

Images obtained under low-light conditions tend to have the characteristics of low-grey levels, high-noise levels, and indistinguishable details. Image degradation not only affects the recognition of images, but also influences the performance of the computer vision system. The low-light image enhancement algorithm based on the dark channel prior de-hazing technique can enhance the contrast of images effectively and can highlight the details of images. However, the dark channel prior dehazing technique ignores the effects of noise, which leads to significant noise amplification after the enhancement process. In this study, a de-hazing-based simultaneous enhancement and noise reduction algorithm of are proposed by analysing the essence of the dark channel prior de-hazing technique and bilateral filter. First, the authors estimate the values of the initial parameters of the hazy image model by de-hazing technique. Then, they correct the parameters of the hazy image model alternately with the iterative joint bilateral filter. Experimental results indicate that the proposed algorithm can simultaneously enhance the low-light images and reduce noise effectively. The proposed algorithm could also perform quite well compared with the current common image enhancement and noise reduction algorithms in terms of the subjective visual effects and objective quality assessments.

关键词： IMAGE intensifiers NOISE control DIGITAL image processing computer vision computer algorithms

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ART2 Clustering of Multiple Web Objects for Qualitative Web Prefetching

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APPLIED ARTIFICIAL INTELLIGENCE 2016年第5期30卷 475-493页

作者： Gracia, Chithra D. Sudha, S. Natl Inst Technol Dept Comp Sci & Engn Tiruchirappalli Tamil Nadu India Natl Inst Technol Dept Elect & Elect Engn Tiruchirappalli 620015 Tamil Nadu India

The web resources in the World Wide Web are rising, to large extent due to the services and applications provided by it. Because web traffic is large, gaining access to these resources incurs user-perceived latency. Although the latency can never be avoided, it can be minimized to a larger extent. Web prefetching is identified as a technique that anticipates the user's future requests and fetches them into the cache prior to an explicit request made. Because web objects are of various types, a new algorithm is proposed that concentrates on prefetching embedded objects, including audio and video files. Further, clustering is employed using adaptive resonance theory (ART) 2 in order to prefetch embedded objects as clusters. For comparative study, the web objects are clustered using ART2, ART1, and other statistical techniques. The clustering results confirm the supremacy of ART2 and, thereby, prefetching web objects in clusters is observed to produce a high hit rate.

关键词： World Wide Web Neural networks (computer science) computer algorithms Internet traffic Browsers (computer programs) Document clustering Cache memory

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CARTESIAN PRODUCT PARTITIONING OF MULTI-DIMENSIONAL REACHABLE STATE SPACES

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PROBABILITY IN THE ENGINEERING AND INFORMATIONAL SCIENCES 2016年第3期30卷 413-430页

作者： Dayar, Tugrul Orhan, M. Can Bilkent Univ Dept Comp Engn TR-06800 Ankara Turkey

Markov chains (MCs) are widely used to model systems which evolve by visiting the states in their state spaces following the available transitions. When such systems are composed of interacting subsystems, they can be mapped to a multi-dimensional MC in which each subsystem normally corresponds to a different dimension. Usually the reachable state space of the multi-dimensional MC is a proper subset of its product state space, that is, Cartesian product of its subsystem state spaces. Compact storage of the matrix underlying such a MC and efficient implementation of analysis methods using Kronecker operations require the set of reachable states to be represented as a union of Cartesian products of subsets of subsystem state spaces. The problem of partitioning the reachable state space of a three or higher dimensional system with a minimum number of partitions into Cartesian products of subsets of subsystem state spaces is shown to be NP-complete. Two algorithms, one merge based the other refinement based, that yield possibly non-optimal partitionings are presented. Results of experiments on a set of problems from the literature and those that are randomly generated indicate that, although it may be more time and memory consuming, the refinement based algorithm almost always computes partitionings with a smaller number of partitions than the merge-based algorithm. The refinement based algorithm is insensitive to the order in which the states in the reachable state space are processed, and in many cases it computes partitionings that are optimal.

关键词： MARKOV processes CARTESIAN coordinates DISCRETE systems computer algorithms MATRIX multiplications

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Identification of Coupled Map Lattice Based on Compressed Sensing

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MATHEMATICAL PROBLEMS IN ENGINEERING 2016年第1期2016卷 1-9页

作者： Xie, Dong Li, Lixiang Niu, Xinxin Yang, Yixian Beijing Univ Posts & Telecommun State Key Lab Networking & Switching Technol Informat Secur Ctr Beijing 100876 Peoples R China Beijing Univ Posts & Telecommun Natl Engn Lab Disaster Backup & Recovery Beijing 100876 Peoples R China

A novel approach for the parameter identification of coupled map lattice (CML) based on compressed sensing is presented in this paper. We establish a meaningful connection between these two seemingly unrelated study topics and identify the weighted parameters using the relevant recovery algorithms in compressed sensing. Specifically, we first transform the parameter identification problem of CML into the sparse recovery problem of underdetermined linear system. In fact, compressed sensing provides a feasible method to solve underdetermined linear system if the sensing matrix satisfies some suitable conditions, such as restricted isometry property (RIP) and mutual coherence. Then we give a low bound on the mutual coherence of the coefficient matrix generated by the observed values of CML and also prove that it satisfies the RIP from a theoretical point of view. If the weighted vector of each element is sparse in the CML system, our proposed approach can recover all the weighted parameters using only about M samplings, which is far less than the number of the lattice elements N. Another important and significant advantage is that if the observed data are contaminated with some types of noises, our approach is still effective. In the simulations, we mainly show the effects of coupling parameter and noise on the recovery rate.

关键词： COUPLED map lattices COMPRESSED sensing (Signal processing) PARAMETER identification computer algorithms LINEAR systems

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Improvement in Laser-Irradiation Efficiency of Robot-Assisted Laser Hair Removal Through Pose Measurement of Skin Surface

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PHOTOMEDICINE AND LASER SURGERY 2016年第1期34卷 42-49页

作者： Park, Sungwoo Lim, Hyoung-woo Cho, Minwoo Lee, Dong-Hun Koh, Wooseok Kim, Youdan Chung, Jin Ho Kim, Sungwan Seoul Natl Univ Coll Engn Interdisciplinary Program Bioengn Seoul 110799 South Korea Seoul Natl Univ Coll Med Dept Dermatol Inst Human Environm Interface Biol Seoul 110799 South Korea JMO Dermatol Seoul South Korea Seoul Natl Univ Coll Engn Inst Adv Aerosp Technol Dept Mech & Aerosp Engn Seoul 110799 South Korea Seoul Natl Univ Coll Med Dept Biomed Engn Seoul 110799 South Korea Seoul Natl Univ Inst Med & Biol Engn Seoul 110799 South Korea

Objective: This study aims to improve the performance of an automatic laser hair removal (LHR) system by applying an algorithm that considers the curve and slant of the skin surface. Background data: In an earlier research, a robot-assisted LHR system has been developed and validated for an almost flat skin or a relatively smooth curved part of the skin. For practical clinical applications, the feature of the robot-assisted LHR system is extended for real curved skins. Methods: A novel pose-measurement algorithm is developed and applied to the LHR system. This system detects a six-degree of freedom (DOF) pose of the skin surface using the pose-measurement algorithm. The main principle of this algorithm is finding the equation of a plane using three noncollinear points, which are obtained by sequential movement of a one dimensional laser sensor. Results: Evaluation of the proposed system was conducted. During the test, we demonstrated that the LHR device automatically and completely contacted the targets along the curved surface. The contact-accuracy test produced satisfactory outcome. The averages of the root mean square (RMS) of the position error and the RMS of the rotation were 1.4437mm and 1.0982 degrees, respectively. The curvature measurement test produced a satisfactory average result of 0.0006mm RMS error. Conclusions: Using the proposed six-DOF pose-measurement algorithm, the performance of the robot-assisted LHR system could be significantly improved from the clinical point of view because most real skins have curved shapes.

关键词： Hair removal Laser beams Robotics in medicine computer algorithms Pose estimation (computer vision) Skin -- Physiology

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HSIP: A Novel Task Scheduling Algorithm for Heterogeneous Computing

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SCIENTIFIC PROGRAMMING 2016年第1期2016卷 1-12页

作者： Wang, Guan Wang, Yuxin Liu, Hui Guo, He Dalian Univ Technol Sch Software Technol Dalian 116620 Peoples R China Liaoning Police Coll Dalian 116036 Peoples R China Dalian Univ Technol Sch Comp Sci & Technol Dalian 116024 Peoples R China

High-performance heterogeneous computing systems are achieved by the use of efficient application scheduling algorithms. However, most of the current algorithms have low efficiency in scheduling. Aiming at solving this problem, we propose a novel task scheduling algorithm for heterogeneous computing named HSIP (heterogeneous scheduling algorithm with improved task priority) whose functionality relies on three pillars: (1) an improved task priority strategy based on standard deviation with improved magnitude as computation weight and communication cost weight to make scheduling priority more reasonable;(2) an entry task duplication selection policy to make the makespan shorter;and (3) an improved idle time slots (ITS) insertion-based optimizing policy to make the task scheduling more efficient. We evaluate our proposed algorithm on randomly generated DAGs, using some real application DAGs by comparison with some classical scheduling algorithms. According to the experimental results, our proposed algorithm appears to perform better than other algorithms in terms of schedule length ratio, efficiency, and frequency of best results.

关键词： computer scheduling HETEROGENEOUS computing computer algorithms PERFORMANCE evaluation MATHEMATICAL optimization

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A Simple Fatigue Life Prediction Algorithm Using the Modified NASGRO Equation

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MATHEMATICAL PROBLEMS IN ENGINEERING 2016年第1期2016卷 1-8页

作者： Zhang, Wei Wang, Qiang Li, Xiaoyang He, Jingjing Beihang Univ Sch Reliabil & Syst Engn Sci & Technol Reliabil & Environm Engn Lab Beijing 100191 Peoples R China

A simple fatigue life prediction algorithm using the modified NASGRO equation is proposed in this paper. The NASGRO equation is modified by introducing the concept of intrinsic effective threshold stress intensity factor (SIF) range (Delta K-eff)(th). One advantage of the proposed method is that the complex growth behavior analysis of small cracks can be avoided, and then the fatigue life can be calculated by directly integrating the crack growth model from the initial defect size to the critical crack size. The fatigue limit and the intrinsic effective threshold SIF range (Delta K-eff)(th) are used to calculate the initial defect size or initial flaw size. The value of (Delta K-eff)(th) is determined by extrapolating the crack propagation rate curves. Instead of using the fatigue limit determined by the fatigue strength at the specific fatigue life, the fatigue limit is selected based on the horizontal tendency of the S-N curve. The calculated fatigue lives are compared to the experimental data of two different alloys. The predicted S-N curves agree with the test data well. Besides, the prediction results are compared with that calculated using the FASTRAN code. Results indicate that the proposed life prediction algorithm is simple and efficient.

关键词： FATIGUE life (Materials science) computer algorithms PREDICTION models STRESS intensity factors (Fracture mechanics) FRACTURE mechanics STRENGTH of materials

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