Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-12-13 Cooperative journals: 《计算机应用研究》
Abstract: The traditional DOA estimation algorithm based on sparse representation only uses sparse signal in spatial domain, which leads to poor sparse performance at low SNR and affects the effect of sparse signal reconstruction. This paper used block sparse theory to decompose the signal sparsely. With the increase of target and the change of combat mission, DOA estimation often presents the characteristics of target group direction finding. In order to make better use of the structural and statistical characteristics of signals, this paper proposed a block sparse DOA estimation algorithm based on space-time combination (STC-BSBL). This method improves the performance of sparse reconstruction, and thus greatly improves the DOA estimation effect. Simulation results show that the proposed method has better estimation performance compared with the traditional DOA method.
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-10-11 Cooperative journals: 《计算机应用研究》
Abstract: In order to solve the problem of high time complexity in the signal recognition process by using convolution neural network, this paper proposed a new algorithm based on denoising auto-encoder and convolution neural network. Firstly, it performed the STFT on the radar emitter signal to obtain the time frequency image. And it used gray and threshold. It put processed image vectorization into the denoising auto-encoder. Then the denoising auto-encoder extracted the feature data. It put the reconstituted image matrix into the convolution neural network and use Softmax classifier as classification and recognition. The simulation shows that the model using DAE is better than the original model and the time complexity decreases greatly. The recognition rate can reach 80% under SNR=-6dB. Besides, compared with the traditional way , the performance of reducing the dimension is better.
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-07-23 Cooperative journals: 《计算机应用研究》
Abstract: Fuzzing is an effective technique for automatically mining vulnerabilities. The mainstream fuzzing technique uses genetic algorithm to generate cases for testing, but almost there exists a premature phenomenon, which leads to lower ratio of path coverage. Given this problem, this paper proposed a fuzzing test method based on dynamic fitness function. Considering the newness of seed and the depth of the path, designed an improved fitness function of dynamic change with different test phases, by which, implemented the fuzzing testing tool–DynFuzzer. On the test set provided by BegBunch and CGC, devised a experiment. The results show that compared with the existing fuzzing test tools, the DynFuzzer path coverage is 40% higher and 10% more bugs are found. The fuzzing test method based on dynamic fitness function can overcome the problem of prematurity, improve path coverage and find more bugs.
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-07-09 Cooperative journals: 《计算机应用研究》
Abstract: When the interference enters from the direction of the main-lobe of the radar, adopting the adaptive beamforming algorithm will lead to problems such as beam distortion and migration of the main-lobe. Aiming at the problem of interference entering from the radar main-lobe, this paper proposed an anti-jamming method based on the design of the transmitted waveform. When the signal encoded by Frank is transmitted, the matched filter and the blocking filter are constructed by using the orthogonality of the Frank code, and the received data is passed through the two filters to obtain two signals. Then the interference is suppressed by the adaptive cancellation method, thus the main-lobe interference is suppressed. Finally, simulation results show that the method of waveform design can effectively suppress interference from main-lobe entry.
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-05-24 Cooperative journals: 《计算机应用研究》
Abstract: The format string vulnerability is a kind of software vulnerability which has high risk and wide impact. Currently, there are many limitations of vulnerability detection method, such as high degree of artificial dependence, high false positive rate, single detection model and failing爐o consider the characteristics of the format string vulnerability fully. To solve above problems, this paper analyzed the format string vulnerability. Then based on symbolic execution, the paper designed and produced a way to detect formatted string vulnerability and generate test cases automatically. This method could detect the existence of the format string vulnerability in Linux binary program automatically. Then it determined whether it could lead to爃arm, which allowed attackers to read or write arbitrary memory. Meanwhile it generated stable and effective test cases.
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-04-17 Cooperative journals: 《计算机应用研究》
Abstract: Against the background of severe APT attack defense, aiming at the fact that the existing network attack modeling methods can not reflect the attack features of APT attacks, this paper established an APT attack model based on Petri nets. With Petri nets, it first established the basic Petri net model of APT attacks according to the characteristics and life cycle of APT attacks. Then, it designed and implemented the algorithm of generating APTPN (advanced persistent threat petri nets) model to generate its complete attack path against a specific APT attack. Finally, experiments verify the effectiveness and correctness of the algorithm by simulating auroral attacks.