Yu Li

National University of Defense Technology, Ch’ang-sha-shih, Hunan, China

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Publications (7)1.36 Total impact

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    ABSTRACT: Due to weather-and illumination-independent characteristics, synthetic aperture radar SAR has become an important tool for target recognition. Using analysis of existing methods, a new feature of SAR imagery and a valid target recognition strategy are proposed. We first extract the gradient ratio pattern for each pixel based on Weber’s law and the local gradient ratio pattern histogram LGRPH is then computed. Next, multiscale LGRPH is constructed for dimensionality reduction. Finally, the similarity is obtained by utilizing K–L discrepancy to measure the distance of MLGRPH. The proposed method is theoretically proven to be insensitive to speckle noise, and the adaptability to local gradient variation is also discussed. Experimental results show that the proposed approach is robust in regard to local gradient variation and speckle noise.
    International Journal of Remote Sensing 02/2014; 35(3):857-870. · 1.36 Impact Factor
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    ABSTRACT: Circular cylinders are important classes of environmental and engineering targets which act as depolarizing features, such as pipes, cables, rebar and tree roots. Two-dimensional plan survey using the linearly polarized Ground Penetrating Radar (GPR) is verified as an effective method to obtain the full-resolution image of subsurface objects and architecture. Compared to the regular measurement, a circular measurement using bow-tie antenna is proposed and shown its obvious advantage to map subsurface crossing cylinders with unknown orientations. The configuration of circular measurement is also an important index for obtaining a high-quality image; meanwhile, the proper spatial sampling interval can reduce the data acquisition time which is very important factor in field survey. A field measurement using 500MHz bow-tie antenna was carried out in the sandpit and validated the effectiveness and feasibility of the proposed circular measurement.
    IGARSS 2013 - 2013 IEEE International Geoscience and Remote Sensing Symposium; 07/2013
  • Han Zhang, Yu Li, Yi Su
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    ABSTRACT: Synthetic Aperture Radar (SAR) image quality parameters attained from the images are always different from system specification in resolution and side lobe intensity. It is difficult to locate effective point targets for calculating of SAR image quality parameters of impulse response function (IRF) characterization. In this paper, an objective image quality assessment method is proposed based on image region information. Spatial resolution (SR), peak side lobe ratio (PSLR) and integrated side lobe ratio (ISLR) are calculated using the coherent correlation function (CCF) of complex SAR images.
    2012 5th International Congress on Image and Signal Processing (CISP); 10/2012
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    ABSTRACT: Aiming at the classification problem of Synthetic aperture radar (SAR) images, a classifier based on image intensity and structure is constructed. To overcome the disadvantages of conventional template matching algorithms, similarity between two images is calculated by Hausdorff function, which can handle the distortions and pixel perturbations. The function is then fed into Support vector machines to eventually accomplish the task of image classification. Experiment results corresponding to field and simulated data show that this method characterizes target structure information well.
    Image and Signal Processing (CISP), 2012 5th International Congress on; 01/2012
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    ABSTRACT: High radiating efficiency of antenna is very crucial for GPR applications. However, the bow-tie antenna, which is widely used in impulse GPR, has very low radiating efficiency because remarkable energy fed into antenna is radiated as the form of end reflection. In this paper, we study how to design bow-tie antenna with high radiating efficiency for impulse GPR. We find that, if the bow-tie antenna is excited by a bipolar pulse, the radiation efficiency can be significantly improved by utilizing the energy in end reflections. And the improvement is implemented by optimizing the antenna length to superpose the main pulse with the end reflection of a radiated pulse.
    Geoscience and Remote Sensing Symposium (IGARSS), 2012 IEEE International; 01/2012
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    ABSTRACT: Maximum average correlation height (MACH) filter is formulated by linearly combining the training data, which is statistically optimum and fairly robust to for finding targets in clutter when the Gaussian assumption holds. This paper proposes a nonlinear extension to the MACH filter by correntropy function which can induce a new feature space. Thus it is possible to construct linear filter equations in the new space, and the proposed filter has an improved performance due to the nonlinear relation between the feature space and input space. The algorithm is applied to synthetic aperture radar image recognition and exhibits better performance under peak-sidelobe-ratio (PSR) and receiver-operating-characteristic (ROC) criteria.
    Image and Signal Processing (CISP), 2012 5th International Congress on; 01/2012
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    ABSTRACT: This paper firstly analyzes the property of the low frequency electromagnetic wave, which can penetrate many types of non-metallic materials, and the ability of Ultra-Wide Band (UWB) impulse signal which has high range resolution. Then the methods are discussed for conducting surveillance through walls, detecting and locating the moving persons behind the partitions. The schematic diagram of Through-Wall Detecting Radar (TWDR) and the models of moving target are shown and the principle of detecting the moving target is also provided with coherent superimposing technique on a range gate. Finally an algorithm for estimating the location of targets is given. The performance of TWDR is validated by the experiments of penetrating a wood block, a red brick wall and a reinforced concrete wall.
    Journal of Electronics (China) 04/2005; 22(3):241-247.