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[Author] Xingzhao LIU(6hit)

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  • A Modified Genetic Channel Router

    Akio SAKAMOTO  Xingzhao LIU  Takashi SHIMAMOTO  

     
    PAPER

      Vol:
    E77-A No:12
      Page(s):
    2076-2084

    Genetic algorithms have been shown to be very useful in a variety of search and optimization problems. In this paper, we propose a modified genetic channel router. We adopt the compatible crossover operator and newly designed compatible mutation operator in order to search solution space more effectively, where vertical constraints are integrated. By carefully selected fitness function forms and optimized genetic parameters, the current version speeds up benchmarks on average about 5.83 times faster than that of our previous version. Moreover the total convergence to optimal solutions for benchmarks can be always obtained.

  • A Genetic Approach for Maximum Independent Set Problems

    Akio SAKAMOTO  Xingzhao LIU  Takashi SHIMAMOTO  

     
    PAPER

      Vol:
    E80-A No:3
      Page(s):
    551-556

    Genetic algorithms have been shown to be very useful in a variety of search and optimization problems. In this paper we present a genetic algorithm for maximum independent set problem. We adopt a permutation encoding with a greedy decoding to solve the problem. The DIMACS benchmark graphs are used to test our algorithm. For most graphs solutions found by our algorithm are optimal, and there are also a few exceptions that solutions found by the algorithm are almost as large as maximum clique sizes. We also compare our algorithm with a hybrid genetic algorithm, called GMCA, and one of the best existing maximum clique algorithms, called CBH. The exiperimental results show that our algorithm outperformed two of the best approaches by GMCA and CBH in final solutions.

  • Ground Moving Target Indication for HRWS-SAR Systems via Symmetric Reconstruction

    Hongchao ZHENG  Junfeng WANG  Xingzhao LIU  Wentao LV  

     
    PAPER-Digital Signal Processing

      Vol:
    E99-A No:8
      Page(s):
    1576-1583

    In this paper, a new scheme is presented for ground moving target indication for multichannel high-resolution wide-swath (HRWS) SAR systems with modified reconstruction filters. The conventional steering vector is generalized for moving targets through taking into account the additional Doppler centroid shift caused by the across-track velocity. Two modified steering vectors with symmetric velocity information are utilized to produce two images for the same scene. Due to the unmatched steering vectors, the stationary backgrounds are defocused but they still hold the same intensities in both images but moving targets are blurred to different extents. The ambiguous components of the moving targets can also be suppressed due to the beamforming in the reconstruction procedure. Therefore, ground moving target indication can be carried out via intensity comparison between the two images. The effectiveness of the proposed method is verified by both simulated and real airborne SAR data.

  • Restrictive Channel Routing with Evolution Programs

    Xingzhao LIU  Akio SAKAMOTO  Takashi SHIMAMOTO  

     
    PAPER

      Vol:
    E76-A No:10
      Page(s):
    1738-1745

    Evolution programs have been shown to be very useful in a variety of search and optimization problems, however, until now, there has been little attempt to apply evolution programs to channel routing problem. In this paper, we present an exolution program and identify the key points which are essential to successfully applying evolution programs to channel routing problem. We also indicate how integrating heuristic information related to the problem under consideration helps in convergence on final solutions and illustrate the validity of out approach by providing experimental results obtained for the benchmark tests. compared with the optimal solutions.

  • Genetic Channel Router

    Xingzhao LIU  Akio SAKAMOTO  Takashi SHIMAMOTO  

     
    PAPER-Computer Aided Design (CAD)

      Vol:
    E77-A No:3
      Page(s):
    492-501

    Genetic algorithms have been shown to be very useful in a variety of search and optimization problems. In this paper, we describe the implementation of genetic algorithms for channel routing problems and identify the key points which are essential to making full use of the population of potential solutions, that is one of the characteristics of genetic algorithms. Three efficient crossover techniques which can be divided further into 13 kinds of crossover operators have been compared. We also extend our previous work with ability to deal with dogleg case by simply splitting multi-terminal nets into a series of 2-terminal subnets. It routes the Deutsch's difficult example with 21 tracks without any detours.

  • A Realization of Signal-Model-Based SAR Imaging via Atomic Decomposition

    Yesheng GAO  Hui SHENG  Kaizhi WANG  Xingzhao LIU  

     
    PAPER-Digital Signal Processing

      Vol:
    E98-A No:9
      Page(s):
    1906-1913

    A signal-model-based SAR image formation algorithm is proposed in this paper. A model is used to describe the received signal, and each scatterer can be characterized by a set of its parameters. Two parameter estimation methods via atomic decomposition are presented: (1) applying 1-D matching pursuit to azimuthal projection data; (2) applying 2-D matching pursuit to raw data. The estimated parameters are mapped to form a SAR image, and the mapping procedure can be implemented under application guidelines. This algorithm requires no prior information about the relative motion between the platform and the target. The Cramer-Rao bounds of parameter estimation are derived, and the root mean square errors of the estimates are close to the bounds. Experimental results are given to validate the algorithm and indicate its potential applications.