Abstract:Prognostics and health management technology, more advanced than the traditional fault diagnosis technology, is about fault diagnosis, prognostic and health management. It is of great significance in cutting down failure rate and maintenance cost. More and more attention is paid to the reliability of electronic system, especially avionics system. Applying PHM technology to electronic system has been one of the most important trends of PHM technology. Based on the analysis of current research, the four implementation methods of prognostics and health management technology of electronics are summarized. They are monitoring precursors, using canary structures, monitoring environmental and usage loads and integration. Then, the key technologies related to PHM technology of electronics are presented, and the future problems and challenges for PHM technology of electronics in the field of precursors capture, physical degradation model and quality of electronic component are discussed. Finally, several suggestions, about design for testability, standard and estimation of PHM technology, are given for future development of PHM technology of electronics.

Abstract:To solve the lack of rationality in the aircraft survivability evaluation index system, the method of solving the potential correlation among the evaluation indices is proposed. Taking the survivability data in the literature for example, under different confidence level we use fuzzy cluster method to classify again the original 10 original evaluation indices, according to the efficient index defined, the best number of the cluster is 4. Then the 4 new evaluation indices are analyzed by factor analysis to prove the result of fuzzy cluster, thus the relation between the new indices and the original indices is acquired. The result shows that the new index system is simple and effective, compared with the old one, its fuzzy cluster method is rational and its effect is good, so the method can be applied in the establishment of evaluation index system for aircraft survivability.

Abstract:A simplified equivalent strain model is presented to predict the disk Low Cycle Fatigue (LCF) life aimed at unsymmetrical loads and the main life regions. Using this model, the LCF life of the first high-pressure compressor disk is predicted. A series of axial strain-controlled LCF tests of 1Cr11Ni2W2MoV bar specimens are conducted. Then an experimental disk is designed, and the LCF test of the rotor is carried out on the spin test rig. The average LCF test life of three disks, 4 280 test cycles, is obtained. Compared with the test life, the prediction error of equivalent strain model is 41.8%, and that of Manson-Coffin model is 99.2% .The result indicates that the disk LCF life prediction method based on the equivalent strain is effective, and is higher than the Manson-Coffin method in accuracy of life prediction.

Abstract:A design of РСБН/SINS integrated navigation is presented. The error model of РСБН is established. The states equation of РСБН/SINS integrated navigation is establish. The relations between inertial navigation position error and azimuth error and distance error are explicated based on the analysis of spherical surface triangle relation principle, theРСБН/SINS integrated navigation system filter measure equation is presented . The method of indirect filter output emendation is adopted in the design of kalman filter. The simulation results show that the filter is capable of well realizing the integration of the two systems, which can increase the navigation accuracy to a great extent, and simultaneously it also can restrain the accumulation of errors.

Abstract:In the near space communication system, the atmosphere, rain, flash will cause the open space link channel quality deterioration. In this paper, near space airship is taken as a communications platform, the Ka-band near space communication channel propagation characteristics of radio waves are analyzed, the focal point is put on analyzing the impact of rainfall on the signal fading. Based on this, the channel model and simulation model of Ka-band near space communication channel are established, and the simulation of the BER performance in Matlab environment is conducted, which provide a theoretical basis for the analysis of close spatial link and the resistance to Rain Fade.

Abstract:Because of the advantage in target detecting, target identifying and anti-jamming, the UWB radar technology has been applied to more fields. It is very important to apply the UWB radar technology to the aerial defence missile for military aim. How to gain bigger cooperative efficiency between fuze and warhead of missile is a pivotal technology problem. The problem can be solved if we can make use of the information of target echo and the relative speed of target and missile well. With the information of target echo in the encountering course of target and missile, the distance value and angle value of target can be estimated. The time domain characteristics of short range target body echo of UWB array are analyzed based on the Gaussian impulse. The mathematical relations between the pulse duration and the most radiation direction of UWB array, the angle of target position are brought forward. A way for angle estimation using pulse duration of target echo is proposed. And the method of improving the cooperation efficiency of fuze and warhead of missile is educed based on the echo information of UWB array and the relative speed between target and missile. So the best explosion location of warhead of missile for killing target can be calculated. Through simulation and calculation, the feasibility of the new method is verified.

Abstract:Using fuzzy chance constrained programming, the paper does some research on the problem of optimal distribution of ground-to-air radar jamming resource under air-defense background. Firstly, based on the model of radar menace grade assessment, using jamming oppressive area, the model of radar jamming effect evaluation is built. Secondly, considering uncertain factors existent in the process of distribution, the bilevel fuzzy chance constrained mixed integer programming for jamming resource optimization assignment is presented. Finally, the bilevel mixed integer programming is obtained by the theory of possibility estimation. Then the optimal solution can be obtained by using the algorithm of mixed integer linear programming. The example indicates that the application of the optimal distribution model can not only deal with uncertain information but also achieve overall optimization when all comes to all. The algorithm of the model is of more pertinence.

Abstract:In order to improve spectrum utilization ratio, it is very necessary to enhance the practicability and veracity of the cooperation spectrum sensing. This paper analyzes and discusses the key technology of cooperation spectrum sensing and data transmission reliability by using the way of multipath data to increase the reliability and practicability during the data transmission process. By this means the data in every perceptive node can be transmitted to the central node more exactly, reliably and practically to make a quick and accurate judgment. And using this method the influences caused by interference and noises during the data transmission process can be overcome. Simulation results show that the method is feasible and lays a foundation for practical application of cooperation spectrum detection technology.

Abstract:Under the fuzzy random environment and aimed at the properties of multi-objective programming, this paper gains many important conclusions. Based on the fuzzy random theory, the expected value model of fuzzy random multi-objective programming is presented which transforms the uncertainties of practical problems into the certainties and provides the theoretical foundation for solving the real-life world problem. As we known, the convexity of programming problem plays an important part in optimization theory, this paper strictly proves the convexity of the model presented above by the properties of expectation of fuzzy random variable. Furthermore, this paper defines the concepts of expected-value non-inferior i.e. the expected-value absolutely optimal solution, the expected-value efficient solution and the expected-value wake efficient solution, and also investigates their properties. To solve the model of fuzzy random programming established by the real problem in practice, the conclusions obtained in this paper provide a theoretical foundation for designing algorithms and making the optimal decisions.

Abstract:By designing the prime frame of equipment fault diagnosis system and using equipment fault records of large screen system as a sample data, this article demonstrates and analyzes the application of Rough Set in the equipment fault diagnosis system. The following work has been done: by the method of combining the Rough Set theory with the Statistical theory, the datasets with missing values of records can be recovered; the algorithm of knowledge acquisition of Rough Set based on Granular Computing can be used to transform the attribute in decision sheet into matrix objects, then the complex knowledge simplification is transformed into matrix operation, thus the time consuming can be deducted, and the knowledge of fault diagnosis can be acquired automatically and more effectively.

Abstract:A novel fractal curve is proposed by using the Iterated Function System, and the expression of the similarity dimension is presented for the fractal curve. The one-order novel fractal curve is applied in the design of miniaturization of printed dipole, and then the miniaturized printed dipole is simulated and optimized by Anosft HFSS. The simulation results show that the length of novel fractal printed dipole is 81.5% smaller than that of a conventional printed dipole when the features of the radiation patterns are not changed. So the novel fractal curve is of an important research value in compact printed dipole field.

Abstract:To overcome the shortcomings such as the existence of over-segmentation in and the great influence of noise on the traditional watershed segmentation, an improved novel watershed image segmentation method is proposed. Firstly, the open-close reconstruction filter is adopted to remove the image noise. Secondly, multi-scale structure elements are used to calculate morphological gradient which can overcome the shortcomings of other conventional gradient operators and produce a gradient map suitable for watershed segmentation. Furthermore, the morphological gradient is modified by viscous morphological operators to remove the most irregular local minimums. After the standard watershed transforming, the region merging method based on neighbor regions edge value is employed to improve the segmentation result. Experiments show that this method can not only effectively remove the noise but also avoid the over-segmentation of watershed and preserve the positions of regional contours.

Abstract:Aimed at the anisotropic characteristic of metamaterials, the propagation modes and the propagation conditions of metamaterials are analyzed. Through superposing the vector coordinate axis and the physical space coordinate axis, and introducing the parameter of the wave propagation angle, the dispersion relation of biaxial anisotropic metamaterial is derived. Based on the wave propagation angle, four classes of medium are identified as:①kz-cutoff type;②kx-cutoff type;③Never-cutoff type;④Always-cutoff type. This classification makes the propagation mode of electromagnetic wave take on more intuitionistic effect. The characteristics of refraction and reflection of metamaterials are analyzed by the wave vector curve, simulated and verified by using the dispersive finite difference time domain method. The numerical results well conform to the theoretic analysis.

Abstract:Through simulating the process of image construction we propose a new image degradation model in this paper, and mutual effect from adjacent pixels, not well-proportioned illumination, as well as the decline of medium transfer ratio are taken into account in the new model. Based on the research on human visual system, including contrast sensitivity, bright- ness adapting ability and side restraint, a vision adaptability solution for the model is proposed. There three processes are included in the solution: a de-convolution process to eliminate the adjacent pixels' mutual effect and provide people with more details; an intensity adjustment process to provide the cone cells with a suitable working condition (the intensity adjustment function is proposed according to cone cells brightness adapting ability) and the contrast upgrade process proposed through simulating the side constraint thesis. Compared with some existing image enhancement algorithms, it can be found in the experimental results that the applications of the proposed algorithm yield some promising results in getting more details, upgrading the contrast, and increasing the visual pleasing characters.

Abstract:This paper, in order to improve the front wave of the horn antenna and to get the higher gain, presents a three-layered metallic grid meta-material structure. Both the theory analysis and the retrieved effective refraction show that the zero index refraction occurs at about 7.1 GHz. A prism experiment is carried out to verify the properties of this zero refraction. When this structure is used as the superstratum of a horn antenna, the front wave phase of the antenna is changed from spherical wave to plane wave, the angle of the beam-width becomes narrower and the gain of the antenna is increased by 2.6 dB. The effect of zero-index metamaterial can improve the front wave of the antenna, which provides a method for realizing the higher gain of horn antennas. This metamaterial will have some applications in practice.

Abstract:GM(1,1) model is widely applied in the uncertainty prediction of less data and poor information, but it is often limited in true application because it is established with equal interval, then the grey prediction model with unequal interval performs a more important realistic function. Currently, the traditional unequal interval grey model (UGM(1,1)) and its amendatory model are established based on exponential model, which could not fit on linear series prediction. In order to overcome the drawbacks of the traditional unequal interval grey model (UGM(1,1)) and its amendatory model, a new amendatory unequal interval grey model (AUGM(1,1)) is proposed by adding linear ingredient and adopting the metabolism theory. The result of simulation and the comparative analysis show that the amendatory model is better than the UGM(1,1) model in accuracy and practicality, and overcomes the shortage that the traditional one could not be used in linear series, in this way, the application field of the grey model is expanded.

Abstract:The electron emission of a carbon nanotube-field emission display mainly depends on the electric field intensity of carbon nanotubes tip. So the accurate calculation of the electric field intensity of carbon nanotubes tip is very important for the development of carbon nanotube-field emission display. In calculating the electric field intensity in a carbon nanotube-field emission display, the field emission model of carbon nanotubes cathode have been simplified as 2D model in many reports for increasing the computation efficiency. To compare and analyze the differences between the calculated results obtained by using 2D and 3D models, single carbon nanotube 2D model, single carbon nanotube and single carbon nano-wall 3D models are constructed respectively, and the finite element simulation software Ansoft Maxwell is used. The calculated results indicate that 2D model field emission of carbon nanotubes cathode expresses the actual field emission of carbon nano-wall cathode, not the actual field emission of carbon nanotubes cathode. The electric field intensity of single carbon nanotube tip calculated by 2D model is only about 1/4 of actual electric field intensity of 3D carbon nanotube tip.