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Zhou J.,Chinese Naval Aeronautical Engineering Academy | Chen J.,Chinese Naval Aeronautical Engineering Academy
2017 IEEE 7th Annual Computing and Communication Workshop and Conference, CCWC 2017 | Year: 2017

Characteristics of diverse wireless communication technologies for the underwater applications are discussed. Compared with traditional magnetic induction communication, the effectiveness and feasibility of magnetic field communication are analyzed. To extend the communication distance of the underwater magnetic field communication, the far-field model of the magnetic field communication is proposed based on magnetic dipole. The maximum communication distance equation is derived, and the numerical analysis of maximum communication distance testifies the applicability of the far-field model. The result shows that the communication distance of the magnetic field communication can be extended to thousands of meters in an ideal noiseless situation. © 2017 IEEE.

Li L.,Unit 91872 of PLA | Li G.-L.,Chinese Naval Aeronautical Engineering Academy
Beijing Ligong Daxue Xuebao/Transaction of Beijing Institute of Technology | Year: 2017

In order to improve the accuracy of direction of arrival (DOA) estimation and decrease calculation capacity with low SNR, a new real-valued propagator method (PM) for 2-D DOA estimation algorithm using cross-correlation matrix (UC-PM) was proposed. Instead of array received data, cross-correlation matrix was constructed to suppress the effect of noise, and eigen-decomposition was replaced by a linear operator with low calculation capacity. Meanwhile, for reducing the complexity further, a new real-valued rotational invariance matrix was constructed to change eigen-decomposition and total least problems into real ones by unitary transformation. The simulation results showed that, being similar performance with 2-D ESPRIT algorithm, the performance of UC-PM is better than conventional PM algorithm with low SNR, and it has much lower calculation capacity than 2-D ESPRIT algorithm, which made the proposed algorithm of high practical value. © 2017, Editorial Department of Transaction of Beijing Institute of Technology. All right reserved.

Li X.-D.,Tsinghua University | Li X.-D.,Chinese Naval Aeronautical Engineering Academy | Wang X.-S.,Tsinghua University | Ren H.-H.,Tsinghua University | And 2 more authors.
Corrosion Science | Year: 2012

The purpose of this paper was to estimate the reliable effect of prior corrosion state on fatigue micro crack initiation and early stage propagation behaviour of aluminum alloy based on scanning electron microscopy (SEM) in situ observation. Results indicated that multi-cracks initiation occurred almost at the corrosion pits and the early stage of fatigue micro crack propagation behaviour can be described by K I/K II-mixed mode. The importance of crack-face interaction via crack-face corrosion pits interlocking/bridging was emphasised in the mixed mode. The fatigue crack growth rate in the corrosion states can be empirically expressed by the term of kσmaxna. © 2011 Elsevier Ltd.

Li X.D.,Chinese Naval Aeronautical Engineering Academy | Mu Z.T.,Chinese Naval Aeronautical Engineering Academy | Sun W.S.,Chinese Naval Aeronautical Engineering Academy
Advanced Materials Research | Year: 2014

Considering the degradation effect of corrosion damage on fatigue behavior of aero aluminum alloy, the present thesis made a research on corrosion fatigue crack growth rate. Taking into account the effect of load frequency on fatigue crack growth, a concept of corrosion fatigue frequency factor is proposed. Based on the fact that low frequency will lead to high corrosion fatigue crack growth rate, and frequency higher enough will make little difference between corrosion fatigue and pure mechanical fatigue behavior, an exponential expression of corrosion fatigue frequency factor is proposed. The crack growth rate prediction from proposed formula is proved to be in good agreement with experimental results for steadily extended corrosion fatigue crack. © (2014) Trans Tech Publications, Switzerland.

Sun S.S.,Qingdao University of Science and Technology | Jiang X.C.,Chinese Naval Aeronautical Engineering Academy
Applied Mechanics and Materials | Year: 2013

The NiTi shape memory alloy (SMA) composite film with Si substrate subjected to thermal loads was modeled by the method of mechanics of materials. The governing equation was obtained by combining static equilibrium equations, geometric and physical equations. Both the material nonlinearity of SMA and the geometric nonlinearity of bending deformation of SMA composite film were considered. By simulating the actuation performance of the SMA composite film during a cooling-heating thermal cycle, it is found that the final cooling temperature and the thickness of SMA film have significant effects on the actuation performance of the SMA composite film. Besides, the maximum deflection of the SMA composite film is affected obviously by the geometric nonlinearity of bending deformation when the thickness of SMA film is very large. © (2013) Trans Tech Publications, Switzerland.

Chu X.,Chinese Naval Aeronautical Engineering Academy
Xitong Fangzhen Xuebao / Journal of System Simulation | Year: 2015

Three are two bottlenecks during training: irregular form display simulation of weather target and display simulation of electromagnetic interference in AEW radar training simulator. The weather target display was realized by building weather controlling model and irregular form of weather target based on Bezier Curve and path developed was simulated by VC++. Interference display of AEW radar was realized by building model of various interference patterns and rejecting operation was simulated by building operating model. A lot of difficulties of PPI for AEW radar training simulator were settled: such as random distribution of weather target, irregular form of weather target, adjusting of parameters of weather target display, interference setting and display randomness. Simulation results are effective in practice, which could provide realistic display of weather target, interference for radar operator and good effect in battle ©, 2015, Chinese Association for System Simulation. All right reserved.

Ren L.,Chinese Naval Aeronautical Engineering Academy | Lv W.,Chinese Naval Aeronautical Engineering Academy
IEEE Transactions on Semiconductor Manufacturing | Year: 2014

Metal etching process is considered to be a bottleneck step in semiconductor manufacturing, and many parameters of etchers can be monitored with sensor systems. So, an effective fault detection algorithm for the etching process is particularly important. Recently, some classification methods that only need positive samples such as principal component analysis-based methods and k-nearest neighbor rule based methods have been used for fault detection and achieved some meaningful results. But the requirement that the distribution of the monitored parameters obeys certain structure is hard to satisfy due to product mix. Our method - fault detection via sparse representation is based on the assumption that there exists a similar pattern to the testing sample in the training set, while the fault is exotic to the training set. So, normal samples can be linearly represented well (a low representation error) using few training samples while the fault cannot reach the same error precision, which is independent of the distribution of the samples. Once the representation of the testing sample is determined using sparse representation model, the distance between the original sample and its representation using few high-weighted basis can be used to detect the fault. The illustrative and industry experiments have verified the efficiency of our method. © 1988-2012 IEEE.

Guo M.,Chinese Naval Aeronautical Engineering Academy | Wang X.-W.,Chinese Naval Aeronautical Engineering Academy
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2010

The implementation of the dynamic IR image simulation on space target/star and space environment was introduced. Firstly, by establishing 3D model of the space target, the heated condition of space target was analyzed, and the infrared heat radiation model of the target outer surface was built. The calculation results were quantized into gray-scale value, and the IR image of the space target was generated. Then, a new hybrid method, which combined traditional theory-model method with the method of eliminating targets in the IR image of real scene, was used in the IR image simulation on star and space environment. At last, the generated IR image of space target with the IR image of star and space environment were synthesized by gray scale normalizing in the gray level. And, the images were synthesized according to the optical axis direction of the IR sensor in the space level. Meanwhile, the whole dynamic image of space target/star and space environment was synthesized.

Cai Z.J.,Chinese Naval Aeronautical Engineering Academy | Li X.D.,Chinese Naval Aeronautical Engineering Academy | Jia M.M.,Chinese Naval Aeronautical Engineering Academy
Advanced Materials Research | Year: 2013

Experimental investigations of fatigue cracking behavior of LC9 aluminum alloy (AA LC9) subjected to elevated temperature were conducted with scanning electron microscope (SEM). Results indicate elevated temperature is important for the fatigue crack growth of AA LC9. Based on small crack growth, crack growth rate for AA LC9 is characterized. © (2014) Trans Tech Publications, Switzerland.

Shao X.,Chinese Naval Aeronautical Engineering Academy
Jisuanji Fuzhu Sheji Yu Tuxingxue Xuebao/Journal of Computer-Aided Design and Computer Graphics | Year: 2015

This paper we put forward an orientation histogram based algorithm for estimating local orientation angles after summarizing the existing orientation estimation methods and pointing out the problems of quadrature filters. The method computes the vector sum of all neighboring ball voting vectors for an object image pixel to get its orientation angle's histogram and search out the peak value of the histogram as its orientation angle. These orientation angles are used for later tensor voting process as orientation information. Four groups of experiments are performed on typical contours to compare the contour inpainting effect and the precision. Experimental results on edge map of city road and noisy images show that the proposed algorithm works well as basic orientation estimation method for more intact contour, less clutter pixels and robust to noises. ©, 2015, Institute of Computing Technology. All right reserved.

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