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Table of Content

    20 December 2019 Volume 46 Issue 6
      
    Method for comprehensive evaluation of effectiveness of radar emitter signals recognition
    LIU Mingqian,MENG Yan,ZHANG Weidong
    Journal of Xidian University. 2019, 46(6):  1-8.  doi:10.19665/j.issn1001-2400.2019.06.001
    Abstract ( 813 )   HTML ( 365 )   PDF (922KB) ( 274 )   Save
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    Aiming at the problems of the existing evaluation methods, such as unscientific index weight setting and unreasonable evaluation method, a method for comprehensive evaluation of the radar radiation source signal identification efficiency is proposed. The performance evaluation index system based on the effect of radar radiation source signal recognition is first established. And then, under the evaluation criteria, an intuitionistic fuzzy network analysis method is used to analyze the indexes with the characteristics of relevance to solve the index weight. Finally, on the basis of the interval-valued hesitant fuzzy idea, the ranking priority relation is established by combining the elimination and selection conversion method and approximate ideal ranking method to realize the comprehensive evaluation of the effectiveness of radar radiation source signal identification. Simulation results show that the method proposed can obtain a reasonable evaluation order of the effectiveness of the radar source signal identification method. Compared with the existing methods, the proposed method can reasonably and effectively solve the problem of index correlation, and avoid the error evaluation caused by the defects of the evaluation method.

    Urban sound event classification with the N-order dense convolutional network
    CAO Yi,HUANG Zilong,ZHANG Wei,LIU Chen,LI Wei
    Journal of Xidian University. 2019, 46(6):  9-16.  doi:10.19665/j.issn1001-2400.2019.06.002
    Abstract ( 384 )   HTML ( 174 )   PDF (1484KB) ( 187 )   Save
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    An urban sound event classification model based on the N-order Dense Convolutional Network (abbreviated to N-DenseNet) is proposed for the problems of insufficient classification accuracy and generalization ability of existing models. First, the network structure of the DenseNet is briefly introduced. Then, dense connection in the DenseNet is improved by N-order state-dependent connection based on the N-order Markov model. Furthermore, combining advantages of both the DenseNet and N-order Markov, a novel network architecture, i.e., the N-DenseNet, is proposed in this paper. Theoretically, the N-DenseNet satisfying the premise of alleviating vanishing-gradient, can not only produce efficient integration of feature information from the layers, but also accelerate the convergence speed. Finally, in order to validate advantages of the new model, 1-DenseNet and 2-DenseNet are respectively exploited in the urban sound event classification based on the UrbanSound8K and Dcase2016 dataset. Experimental results show that the accuracy of the two above-mentioned models is respectively 83.63% and 81.03%, which also demonstrates a higher classification accuracy and a better generalization performance of the N-DenseNet.

    Approach to FPGA placement using resource negotiation
    WANG Dekui
    Journal of Xidian University. 2019, 46(6):  17-22.  doi:10.19665/j.issn1001-2400.2019.06.003
    Abstract ( 360 )   HTML ( 105 )   PDF (805KB) ( 97 )   Save
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    Placement is one of the most time-consuming steps of the Field Programmable Gate Array (FPGA) computer aided design flow. In order to accelerate the placement step, a novel approach to FPGA placement is proposed. First, circuit logic blocks choose to use the lowest cost physical resources, and it is allowed that multiple logic blocks share the same resource. Second, the logic blocks using the overused physical resources are re-placed iteratively; the cost of the overused resources is gradually increased, thus eliminating the overuse of the physical resources progressively. Finally, the low-temperature simulated annealing algorithm is applied to optimize the placement result. Experimental results show that the proposed approach reduces the placement runtime by 52% compared with the state-of-the art placement tool, with a reduction of critical path delay and total wirelength by 4.8% and 1.9%, respectively. The proposed approach significantly accelerates the FPGA placement and hence shortens the compile-debug cycle of circuits, which is helpful to improving the efficiency of the developers.

    Analysis of sensitivity uncertainty of the MEMS microphone based on Latin hypercube Monte Carlo simulation
    LIU Lei,JIA Renxu
    Journal of Xidian University. 2019, 46(6):  23-29.  doi:10.19665/j.issn1001-2400.2019.06.004
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    Due to the diaphragm uncertainties from manufacturing processes, the MEMS microphone may exhibit significant variations in their performance compared to the nominal design. In order to reduce calculation time and improve simulation efficiency, this paper presents the Latin hypercube Monte Carlo Simulation (LHMCS) based on artificial neural networks (ANNs), which is used to analyze the sensitivity uncertainty of the polysilicon circular clamped diaphragm microphone. Experimental results show that the simulated qualified rate of the MEMS microphone is 92.9% and the time-consuming is less than 10 seconds and that compared with the traditional Monte Carlo simulation based on random sampling, LHMCS needs only 11% of the sampling number at the same accuracy. This paper also analyzes the effects of nominal design values of the diaphragm on the probability distributions of microphone sensitivities. The mean values and standard deviations of the sensitivity distributions are obtained by fitting the simulation results with normal distribution. The results show that three main factors affecting the distribution in the order from strength to weakness are radius, thickness, and young modulus. Young modulus only affects the mean value, but does not affect the standard deviation. The presented LHMCS with high accuracy and efficiency is an alternative to the traditional methods.

    Analysis of targeted sentiment by the attention gated convolutional network model
    CAO Weidong,LI Jiaqi,WANG Huaichao
    Journal of Xidian University. 2019, 46(6):  30-36.  doi:10.19665/j.issn1001-2400.2019.06.005
    Abstract ( 427 )   HTML ( 22 )   PDF (1108KB) ( 104 )   Save
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    The recurrent neural networks are used for traditional targeted sentiment analysis and usually lead to a long training time. And other alternative models are unable to make a good interaction between context and target words. An attention gated convolutional network model for targeted sentiment analysis is proposed. First, context and target words are processed by the multiple attention mechanism to enhance their interactions. Second, the gated convolution mechanism is used to selectively generate emotional features. Finally, the emotional features are classified by the Softmax classifier to output the emotional polarity. Experimental results show that compared with the Recurrent Attention Network model, which has the highest accuracy rate in the recurrent neural network models, the proposed model improves the accuracy rate by 1.29% and 0.12% respectively on the Restaurant and Laptop datasets of SemEval 2014 Task4. Compared with the Attention-based Long Short-Term Memory Network model, which has a faster convergence rate in the recurrent neural network model, the convergence time is reduced by 29.17 s.

    Hardware Trojan detection algorithm based on deep learning
    LIU Zhiqiang,ZHANG Mingjin,CHI Yuan,LI Yunsong
    Journal of Xidian University. 2019, 46(6):  37-45.  doi:10.19665/j.issn1001-2400.2019.06.006
    Abstract ( 565 )   HTML ( 37 )   PDF (2535KB) ( 112 )   Save
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    The traditional way of hardware trojan detection based on electrical signal detection has problems of low positive rate, low efficiency and high cost. To solve these problems, we propose a new way of hardware trojan detection based on deep learning which is not electrical signal detection. First, the algorithm changes chip microscopic images of low resolution into chip microscopic images of high resolution by using an enhanced residual network. Then these chip microscopic images of high resolution will generate another chip microscopic images which are similar to those of the golden model. The algorithm for image enhancement distinguishes between target area and background area by combining with the algorithm of image segmentation. Finally, we use the change detection algorithm to detect the hardware trojans existing in the chip after removing minor interference due to industrial noise. Through the experiments on the micrograph dataset of the chip, the positive detection rate of the hardware trojan detection method based on deep learning is as high as 92.4%. Compared with the traditional electrical signal detection method, our algorithm has the advantages of higher precision, faster speed, and easier operation.

    Wideband high-gain ring circularly polarized microstrip antenna
    CHEN Qingqing,LI Jianying,DING Yuxin,ZHANG Lingkai,FENG Yao,XIE Jing
    Journal of Xidian University. 2019, 46(6):  46-51.  doi:10.19665/j.issn1001-2400.2019.06.007
    Abstract ( 854 )   HTML ( 55 )   PDF (2063KB) ( 212 )   Save
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    Two novel single-fed ring circularly polarized microstrip antenna with an enhancing bandwidth are designed to broaden the axial ratio bandwidth of the cut ring patch antenna. Since the lateral slot perturbs the surface current of the ring patch, two equal-amplitude radiation modes with a phase difference of 90° are excited to radiate circular polarization. The measured results show that good circularly polarized characteristics of the annular-ring and the square-ring antennas have been obtained respectively from 3.74 to 3.98 GHz and from 3.80 to 4.04 GHz. The axial ratios (ARs) are less than 3 dB and the voltage standing wave ratios (VSWR) are less than 2. In addition, the antenna peak gains are higher than 10.0 dB for annular-ring and square-ring microstrip antennas over the operating bandwidth.

    Algorithm for segmentation of smoke using the improved DeeplabV3 network
    WANG Ziyi,SU Yuting,LIU Yanyan,ZHANG Wei
    Journal of Xidian University. 2019, 46(6):  52-59.  doi:10.19665/j.issn1001-2400.2019.06.008
    Abstract ( 550 )   HTML ( 66 )   PDF (1730KB) ( 96 )   Save
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    Existing smoke detection methods depend mostly on features which are selected manually and the smoke areas in video images often cannot be segmented accurately. This paper proposes an improved DeeplabV3 smoke segmentation algorithm based on this. A feature refinement module is added after the basic encoder network to weaken the gridding effects caused by dilated convolutions. For the non-rigid objects such as smoke with variable scales and postures, the Atrous Spatial Pyramid Pooling module is combined with the deformable convolution to better adapt to the smoke deformation. And a channel attention decoder module is proposed to further restore the spatial details of smoke images. According to the test of the smoke image data set, the proposed model has a faster average prediction speed of 71.73ms per image. Besides, compared with the DeeplabV3 network, this algorithm can lead to a higher MPA (Mean Pixel Accuracy) of 97.78% and a higher MIoU (Mean Intersection over Union) of 91.21%, thus improving the performance by 0.56% and 2.17% respectively, and making it more suitable for smoke segmentation. Public smoke video test results show that this model outperforms other video-based smoke detection methods for the detection rate, and that it is of certain research significance and practical value.

    Method for suppressing clutters with the joint low-rank and sparse model
    HUANG Chen,LIU Hongqing,LUO Zhen,ZHOU Yi
    Journal of Xidian University. 2019, 46(6):  60-66.  doi:10.19665/j.issn1001-2400.2019.06.009
    Abstract ( 309 )   HTML ( 22 )   PDF (1291KB) ( 73 )   Save
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    The existing method for suppression of clutters of the through-the-wall radar system requires full size data, which may increase the complexity of the system. To this end, a wall clutter suppression method with the joint low-rank and sparse model is developed in this paper. In the proposed method, the task of separating wall clutters and target returns is transformed into a low-rank and sparse constrained optimization model requiring less data. To solve this optimization, the alternating direction method for multipliers is adopted. After clutter suppression, the return signals are used for the image formation. Experimental results demonstrate that the proposed method is significantly effective on clutter suppression in different scenes. Compared with the existing methods such as singular value decomposition and iterative soft thresholding, the proposed method has a higher target-to-clutter ratio in the radar imaging results.

    Scheduling of active/passive sensors for radiation control
    ZHANG Yunpu,SHAN Ganlin,DUAN Xiusheng,WANG Meng
    Journal of Xidian University. 2019, 46(6):  67-74.  doi:10.19665/j.issn1001-2400.2019.06.010
    Abstract ( 246 )   HTML ( 15 )   PDF (1049KB) ( 38 )   Save
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    In order to reduce the radiation risk of the sensor system during target tracking, the scheduling problem of active/passive sensors is studied. By establishing a sensor scheduling model based on the Partially Observable Markov Decision Process, the prediction formulas for target tracking accuracy and system radiation cost are given, the target function is established to meet the tracking accuracy constraint and the system radiation cost is minimized. An improved distributed auction algorithm is designed to solve the problem. Simulation experiments show that the method proposed in this paper can reduce the system radiation risk without sacrificing the tracking accuracy by reasonably scheduling the active/passive sensors on each platform.

    Sparsity-induced resonance demodulation method for blade crack detection
    HE Wangpeng,HU Jie,CHEN Binqiang,LI Cheng,GUO Baolong
    Journal of Xidian University. 2019, 46(6):  75-80.  doi:10.19665/j.issn1001-2400.2019.06.011
    Abstract ( 257 )   HTML ( 14 )   PDF (1443KB) ( 38 )   Save
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    In order to extract incipient features caused by bladed machinery in the presence of coherent noises, a novel diagnostic approach using sparse demodulation operator is proposed. First, the recorded vibration signal from the bladed machinery is decomposed by the centralized multiresolution analyzing method and each subspace is reconstructed in the time domain. Second, the Hilbert demodulation method is performed on the reconstructed signals and some specific subspaces within which the harmonic tones of fault frequencies are dominant are selected. Third, comb filters are employed to separate the harmonic tones of fault frequencies such that a referential model for the fault features can be obtained. Finally, the reconstructed signals of the selected subspaces are denoised, via the wavelet threshold strategy combined with the referential model, to retrieve fault induced incipient features. The proposed method is applied to a fault diagnosis case study of a booster fan with blade cracks. It is found that the periodic impulsive features cannot be directly extracted in the time domain by merely using multiscale decomposition. However, with the proposed method, the actual fault features can be significantly enhanced after suppressing noises of strong coherence.

    Method of cancer biomarker prediction in the gene regulatory network
    QIN Guimin,LIU Jiayan,YIN Yu,YANG Luqiong
    Journal of Xidian University. 2019, 46(6):  81-87.  doi:10.19665/j.issn1001-2400.2019.06.012
    Abstract ( 303 )   HTML ( 21 )   PDF (1413KB) ( 47 )   Save
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    Cancer biomarkers identification based on multi-omics data is of great significance for the study of molecular mechanisms of cancer, while most of the current work is based on protein-protein interaction data. Therefore, a new method based on the gene regulatory network and multi-omic data is proposed to analyze cancer molecular mechanisms and predict cancer biomarkers. Taking stomach adenocarcinoma (STAD) and esophageal carcinoma (ESCA) for example, first we integrate multi-omics data to construct cancer-specific networks for STAD and ESCA respectively. Then, analysis of weighted co-expression gene networks is carried out on the two networks, and hierarchical clustering modules are used to calculate the relationship between the first principal component of the module and all known cancer biomarkers. Furthermore, cancer-specific modules are screened out. Finally, disease-specific biological pathways are extracted, and potential cancer biomarkers are prioritized using similarity assessment methods. Experimental results show that the specific module predicted has functional characteristics, and that the Pearson correlation coefficient method is more accurate.

    Tailoring method for triaxial vibration load spectrum preserving pattern
    BAI Jin,QIU Yuanying,LI Jing,WANG Zhaoqian,LI Guilin,WANG Haidong,WANG Zhaoxi
    Journal of Xidian University. 2019, 46(6):  88-94.  doi:10.19665/j.issn1001-2400.2019.06.013
    Abstract ( 312 )   HTML ( 14 )   PDF (1803KB) ( 31 )   Save
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    Because the multi-axial simultaneous vibration cannot be simply equivalent to single-axis sequential vibration, a load spectrum tailoring method is proposed to maintain the equivalence of the random vibration stress of triaxial vibration and single-axis vibration in the key parts of the structure. A method of root mean square value clipping of triaxial load spectrum is proposed by deducing the transformation relation between triaxial random vibration load and the response of key points of the structure. And based on the presupposition that the ratio of the equivalent stress of the key parts of the specimen under triaxial loads to the maximum equivalent stress under uniaxial loads should be equal to the ratio of the root mean square value of the stress response of the point before tailoring to that after tailoring, then considering the importance of different parts and the strength of materials, triaxial load spectrum root-mean-square value clipping criteria are defined. In order to avoid the uncertainty of the test caused by the diversity of spectral pattern tailoring, the pattern-preserving tailoring rules of the triaxial load spectrum are formulated. Finally, the effectiveness of the triaxial load spectrum tailoring method is verified by taking a typical cabin circuit board as an example. The triaxial load spectrum obtained by this method can not only avoid the over-test or under-test of important parts of the structure, but also ensure the equivalence of stress of key points and the certainty of the cut spectrum type.

    Low resolution face recognition method based on wavelet and recursive neural networks
    OUYANG Ning,WANG Xian’ao,CAI Xiaodong,LIN Leping
    Journal of Xidian University. 2019, 46(6):  95-101.  doi:10.19665/j.issn1001-2400.2019.06.014
    Abstract ( 290 )   HTML ( 26 )   PDF (1562KB) ( 74 )   Save
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    To improve the accuracy of low-resolution face recognition with limited information, a method based on the Haar wavelet and recurrent neural network is proposed. First, the wavelet coefficients are directly predicted through the deep neural network. High-resolution face images with high-frequency information can be reconstructed by the inverse wavelet transform. Second, a recursive module is added to the convolutional neural network to increase the depth of the network, which can reduce the redundancy of parameters effectively. Finally, a fusion loss method is utilized, in which the loss of wavelet coefficients reconstruction and the perceptual are weighted and fusioned to generate images for recognition. Based on open dataset, the image reconstruction quality and recognition performance are compared, respectively. Experimental results show that sharper face images can be reconstructed even with extremely low resolutions (8×8, 16×16), and that its recognition ability outperforms that of state-of-the-art face super resolution algorithms.

    Pulse sorting and pairing based on the constrained extended TDOA histogram
    LIU Zhixin,ZHAO Yongjun
    Journal of Xidian University. 2019, 46(6):  102-111.  doi:10.19665/j.issn1001-2400.2019.06.015
    Abstract ( 277 )   HTML ( 15 )   PDF (1603KB) ( 38 )   Save
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    In multi-station electronic reconnaissance systems, pulse sorting and pairing are the premise of accurate emitter localization. Considering the problem of a high false alarm rate and a high missing alarm rate for sorting the pulse with an ultra-low pulse repetition frequency in conventional time difference of arrival (TDOA)-based sorting methods, this paper proposes a pulse sorting and pairing method based on the constrained extended TDOA histogram. In this method, a constraint condition with respect to pulse parameters is first introduced to obtain the valid TDOA distribution. Then, the extended iteration operation is used to complete the pulse sorting and pairing of each emitter. After reducing the chance of irrelevant pulse pairing by the constraint condition, the proposed method fundamentally decreases the number of false TDOA and noise TDOA, and effectively suppresses the generation of false emitters. Numerical experiments indicate that compared with the existing methods, the proposed method can significantly improve the performance of TDOA sorting and can achieve the accurate sorting and pairing for extremely few pulses with an ultra-low pulse repetition frequency, even for single pulses.

    Video deblurring using the generative adversarial network
    SHEN Haijie,BIAN Qian,CHEN Xiaofan,WANG Zhenduo,TIAN Xinzhi
    Journal of Xidian University. 2019, 46(6):  112-117.  doi:10.19665/j.issn1001-2400.2019.06.016
    Abstract ( 356 )   HTML ( 23 )   PDF (1315KB) ( 63 )   Save
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    A video deblurring network based on the generative adversarial network and the Markovian discriminator is proposed to solve the video deblurring problem, which is caused by camera shaking or object movement. In this paper, we combine the pixel-space and feature-space loss, and design a discriminator based on the Markovian discriminator, which promotes the learning of image texture details and improves the quality of the generated image. The proposed method and the state-of-the-art methods are compared qualitatively and quantitatively on the test set and real video set, respectively. Experimental results indicate that the image deblurred by the proposed method has a higher peak signal-to-noise ratio and richer details.

    Design of a broadband high-efficiency power amplifier using the artificial neural network
    ZHANG Mingzhe,WU Haifeng,WEI Shizhe
    Journal of Xidian University. 2019, 46(6):  118-124.  doi:10.19665/j.issn1001-2400.2019.06.017
    Abstract ( 303 )   HTML ( 18 )   PDF (1973KB) ( 36 )   Save
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    The artificial neural network modeling approach to designing matching networks for the broadband high efficiency power amplifiers (PAs) is proposed for the first time. The effects of input and output matching networks on the performance of PAs are analyzed. The neural network model is exploited to represent the relationship between matching networks and the optimal impedances, and the design process is combined with the optimization method. The developed ANN model allows the RF amplifier designers to realize specified matching networks conveniently and effectively. Circuit examples are used to demonstrate our proposed method. Simulation results show that a broadband high-efficiency PA is realized from 0.2 to 1.6 GHz (fractional bandwidth = 156%) with the simulated drain efficiency of 64.5%~80.5% and the output power of 40.4~41.6 dBm (10~14.5W).

    Satellite RCS anomaly detection using the GRU model
    HU Mengxiao,LU Wang,XU Can,LAI Jiazhe
    Journal of Xidian University. 2019, 46(6):  125-130.  doi:10.19665/j.issn1001-2400.2019.06.018
    Abstract ( 270 )   HTML ( 19 )   PDF (1120KB) ( 50 )   Save
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    Aiming at the problem that the traditional target image anomaly detection method based on radar cross-section extracts effective features with difficulty and the recognition effect is poor, an anomaly detection method gated recurrent unit deep neural network model is proposed. First, the method uses the sliding window method to divide the dynamic radar cross-sectional sequence. Then, to complete the adaptive feature learning of the input sequence, the gated recurrent unit deep neural network is used. Finally, the full connection layer is used to realize the satellite attitude anomaly detection. Simulation results show that the proposed method can achieve a high feature discrimination degree, that it can effectively detect the unstable rolling satellite compared with the traditional method, and that it has strong noise robustness.

    Combined multi-features method for the detection of SAR man-made weak trace
    WANG Zhihao,ZHANG Jinsong,SUN Guangcai,LI Jun,XING Mengdao
    Journal of Xidian University. 2019, 46(6):  131-139.  doi:10.19665/j.issn1001-2400.2019.06.019
    Abstract ( 314 )   HTML ( 15 )   PDF (3415KB) ( 88 )   Save
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    When detecting the man-made weak trace like the footprints and wheel prints, a large number of false alarm areas caused by natural scenes appear in the detection results due to their low correlation, such as the vegetation and rivers. To solve this problem, this paper first gets the preliminary detection results with the Coherent Change Detection (CCD). Then by analyzing the Radar Cross Section (RCS) model of the natural scenes, it is found that the vegetation region varies much on image intensity while the river region gets a lower image intensity compared to the man-made weak trace. Based on this research, the differential and the sum of the image-pair intensity are taken as two test statistics to eliminate the vegetation and river regions from the preliminary detection results, and then a combined multi-feature method is proposed for man-made weak trace detection. The proposed method can reduce the false alarm rate and lead to fine detection results by multi-features. Finally, the processing results of the millimeter wave Synthetic Aperture Radar (SAR) real data verify the efficiency of the proposed method.

    Analysis of dynamic characteristics of random FG-CNTRC structures
    LI Lin,XU Yalan
    Journal of Xidian University. 2019, 46(6):  140-146.  doi:10.19665/j.issn1001-2400.2019.06.020
    Abstract ( 195 )   HTML ( 13 )   PDF (767KB) ( 52 )   Save
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    In order to investigate the influences of the randomness of physical parameters of constituent materials and constituent distribution on natural frequencies of a functionally graded carbon nanotube reinforced composite structure, a finite element dynamics model is developed for a beam structure with different arrangements of carbon nanotube by using the high-order shear deformation theory and generalized mixture law. The first-order perturbation method is used to introduce the random variables and the stochastic finite element model is established. The numerical characteristics relationships between natural frequencies and the randomness of physical parameters of constituent materials as well as constituent distribution are derived. The results show that the contribution of the randomness of physical parameters of constituent materials to the scattering of natural frequencies is much greater than the constituent distribution. The dispersion of natural frequencies for the carbon nanotube X-type decreases with the increase in volume fraction at the very beginning, and then turns to increase rapidly. However, O-type natural frequencies dispersion is still in the attenuated state.

    Security risk scenarios and solutions in automatic program repair
    HUANG Yuming,MA Jianfeng,LIU Zhiquan,WEI Kaimin,FENG Bingwen
    Journal of Xidian University. 2019, 46(6):  147-154.  doi:10.19665/j.issn1001-2400.2019.06.021
    Abstract ( 257 )   HTML ( 13 )   PDF (1222KB) ( 33 )   Save
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    To improve the quality of the Automatic Program Repair (APR) method, this research points out two scenarios, namely tainted patch sources and error test suites, which may lead to security risks in the APR-based software defect fix. Moreover, the research proposes the corresponding solutions, namely the patch verification schema and the test suite verification schema, respectively. Experimental results demonstrate that the patch verification schema can enable the APR to obtain a more secure patch, and that the test suite verification scheme can accurately locate the error test cases in the test suite with a false positive rate of 7.20%.

    Multi-beam tracking scheduling strategy for phased array radar based on the cost-effectiveness ratio
    LIU Yiming,SHENG Wen,SHI Duanyang
    Journal of Xidian University. 2019, 46(6):  155-162.  doi:10.19665/j.issn1001-2400.2019.06.022
    Abstract ( 431 )   HTML ( 15 )   PDF (1011KB) ( 44 )   Save
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    The phased array radar tracking mode occupies most of its resources. In order to solve the problem of contradiction between improving target tracking accuracy and capacity, a beam waveform scheduling strategy considering both the tracking accuracy and radar time resources was proposed. First, the target tracking model is given. Furthermore, the beam scheduling cost-effectiveness ratio and scheduling function are defined. Under the constraints of detection probability and tracking accuracy, the scheduling function values of all current targets are predicted, and schedule target sequence is selected according to the scheduling function values under the constraint of the tracking resource and multi-beam tracking method. Finally, compared with methods of conventional beam waveform scheduling and single-beam scheduling, simulation verifies the effectiveness and superiority of the scheduling function and the multi-beam tracking method under the condition that the number of tracking targets is constant. The scheduling strategy effectively improves the average tracking accuracy and the average sampling interval time of the target, and reduces the loss rate.

    Self-attention generative adversarial network with the conditional constraint
    JIA Yufeng,MA Li
    Journal of Xidian University. 2019, 46(6):  163-171.  doi:10.19665/j.issn1001-2400.2019.06.023
    Abstract ( 224 )   HTML ( 18 )   PDF (2862KB) ( 42 )   Save
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    In order to solve the problem that the feature information of the generated image against the network is insufficient, so that the generated effect characteristic is not obvious, and the key feature information of the image is blurred, this paper proposes an image generating method for a conditional self-attention generative adversarial network. The network combines the advantages of the self-attention generative adversarial network, and adds additional conditional features to the generator and the discriminator. It is explicitly indicated that the model can generate corresponding iconic category information. The specific dimensions of the data are related to the semantic features. In this way, the generation model is extracted, so that the feature representations of the images of a particular type are more closely matched to the original data distribution. Experimental results show that the FID values of the proposed method on the CelebA and MNIST data sets are increased by 1.26 and 2.47, respectively, compared with the self-attention generative confrontation network. It is verified that compared with other supervised class generation models, the proposed method can effectively improve the image quality and diversity, and can make the network converge faster.

    Optimization of the low coherence and high robustness observation matrix
    ZHAO Hui,ZHANG Le,LIU Yingli,ZHANG Jing,ZHANG Tianqi
    Journal of Xidian University. 2019, 46(6):  171-178.  doi:10.19665/j.issn1001-2400.2019.06.024
    Abstract ( 229 )   HTML ( 13 )   PDF (1230KB) ( 38 )   Save
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    An observation matrix optimization algorithm based on the tight frame and sparse representation error is proposed. First, the average mutual coherence of the sensing matrix is reduced by the Glam matrix which approximates the unit matrix and the constructed tight frame. Second, the sparse representation error as a regularization term is added to the conventional optimization model to improve the robustness of the observation matrix. Finally,the analytical method is applied to solve the observation matrix to ensure the convergence of the algorithm. Experimental results show that, compared with the contrast optimization matrix, the average mutual coherence of the proposed sensing matrix can be reduced by at least 0.03 with more robustness.