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2004 Vol. 30, No. 12

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Equivalent time-variable availability analysis based on individual sub fault tree
Wang Shaoping, Tao Jianfeng, Cui Mingshan, Jiao Zongxia
2004, 30(12): 1137-1141.
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With depth-first left-most ergonic algorithm, the complex dynamic fault tree can be decomposed into several ISFT (individual sub fault tree) in availability analysis of complex system. In order to calculate its availability in time-variable filed, the equivalent time-variable availability parameters are presented and proved to ISFT. Transferring ISFT into corresponding Markov chain, the differential equation of sub-Markov chain in falling dimension can be calculated with time-variable availability parameters easily. From bottom to up, the availability analysis for complex system can be realized with recursion algorithm, which not only solve the problem that the computing enhances exponential with the number of states increases in availability calculation of complex system but also improve the calculation precision with time-variable parameters. Application indicates that the equivalent time-variable availability analysis based on ISFT is content under the effective decomposition.
Application of hybrid genetic algorithm in aeroelastic multidisciplinary optimization
Wan Zhiqiang, Yang Chao, Li Zhengneng
2004, 30(12): 1142-1146.
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The genetic/sensitivity-based hybrid algorithm was used for the design studies of aeroelastic tailoring of a forward-swept composite airplane. The design objective is to minimize the weight of skin. The ply-thicknesses of wing skin were selected as design variables. The constraints were strength, displacement, lifting efficiency, aileron efficiency, divergence speed and flutter speed. The studies demonstrate that it is difficult to meet design requirements in preliminary design of aircraft structure when sensitivity-based algorithm is used along. The genetic/sensitivity-based hybrid algorithm could outperform sensitivity-based algorithm operating alone. The hybrid algorithm is suitable for preliminary design of aircraft structure. The effect of ply-orientation on optimized weight while satisfying the above multiple constraints was discussed. The results indicate that the optimized weight of the forward-swept composite wing is relatively insensitive to ply-orientation of skin when skin lay-up consists of 0°, 90° and ±45° fiber directions and wing is subjected to multiple constraints on static constraints, static aeroelastic constraints.
Realization method of moving target detection based on along-track interferometry
Sun Na, Zhou Yinqing, Li Jingwen
2004, 30(12): 1147-1150.
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An algorithm of moving target detection, radial velocity estimation and relocation based on ATI(along-track interferometry) with dual-aperture antenna was proposed. Compared with DPCA (displaced phase center antenna) technique, this method need not satisfy the strict constraint between platform velocity and pulse repetition frequency. Meanwhile, it overcame the shortcoming of decreased slow moving target detection ability because of moving target amplitude cancellation varying with radial velocity according to sinusoid rule generated by DPCA and CSI (clutter suppression interferometry) techniques. On the basis of ATI principle analysis, the realization method of moving target detection, radial velocity estimation and relocation using interferometric phase information was presented. This method can perform the detection, radial velocity estimation and relocation of moving targets masked by ground clutters. Computer simulation results show the effectiveness.
Fuzzy control of aircraft environmental control system
He Jun, Zhao Jingquan, Yuan Xiugan
2004, 30(12): 1151-1154.
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Ground-tests proved that aircraft ECS(environmental control system) with conventional PID(proportional-integral-differential) controlling means could not refrigerate the electronic equipment and cabin satisfactorily. A new fuzzy control model is proposed which consists of some membership functions expressed by triangle function or trapezoid function. According to ECS operation tasks, two different fuzzy control rule bases are adopted in system process control. Genetic algorithm is utilized for tuning the parameters of the membership functions of the antecedent and the consequent. Compared computer simulation with ground-tests, the aircraft ECS with new fuzzy controller could satisfy aircraft system design demands. And it is demonstrated that the new fuzzy controlling means based on genetic algorithm is more stable and faster than PID controlling means in the existing system.
Numerical simulation on gas dynamic resonance heating effect
Tong Xiaoyan, Liang Guozhu, Zhang Guozhou, An Lian
2004, 30(12): 1155-1158.
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To study the interior flow of the resonance tube, the model of the nozzle-cylindrical resonance tube system was established, and the gas dynamic resonance heating effect was simulated. The explicit second-order NND scheme was used to solve the 2-D axisymmetric Reynolds averaged N-S equations. The heat transfer effects of the resonance tube were considered by heat transfer equations. The pressure and temperature oscillation curves at the resonance tube end were obtained and the computational data were in good agreement with the experimental data. The results show that gas dynamic resonance heating is performed in about twenty milliseconds, and the heat transfer effects of the resonance tube affect the temperature of gas dynamic resonance heating highly and should be considered in computation and application.
Method of updating LBTS passively for HLA time management
Hu Yahai, Xu Yongbo, Peng Xiaoyuan
2004, 30(12): 1159-1162.
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The LBTS (lower bound time stamp) quarry is key problem for TM (time management) performance. An optimized method will be proposed for improve the TM performance in HLA(high level architecture). It can reduce the frequency of LBTS transfer, and time-constrained federates will be notified LBTS only when LBTS is changed rather than they quarry LBTS actively. Reliable multicast services are applied to reduce the communication cost. These algorithms have been used in TM in self-developed AST-RTI (advanced simulation technology-run time infrastructure), and application systems showed that RTI real time performance has been improved. Then the simulation application problems in RTI TM mechanism and solutions will be discussed.
Theoretical study on lightweight design of thin-walled beam structure for automobile body
Sun Lingyu, Yao Yingxian
2004, 30(12): 1163-1167.
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The main load-supporting elements for an automobile framework are thin-walled beams. To study the effectiveness of lightweighting on the body stiffness, the analytical formulae describing static bending and torsional stiffness of a beam with fixed-fixed supporters were derived firstly. To get a light thin-walled beam structure with optimum section, the influence of every sectional geometry parameter on the stiffness-mass ratio was discussed respectively. After replacing the steel by the lightweight material, the corresponding variations in structural stiffness and size were analyzed. The stiffness-mass ratios of beams with open and close loop sections were also compared with each other. Finally, a few geometrical and material parameters, which can greatly influence the bending or torsional stiffness of these thin-walled beams, were found out. For a typical thin-walled beam applied in an automobile body, the design guideline achieving both lightweight and high stiffness is presented.
Study on iterative availability algorithm of Markov renewal equation
Wang Shaoping, Tao Jianfeng, Cui Mingshan, Jiao Zongxia
2004, 30(12): 1168-1172.
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Dynamic structure variance of cool spare system requires the dynamic availability analysis with transient solution. The traditional calculation method of Markov renewal equation based on Laplace transform and inverse Laplace transform makes many difficulties to complex system. The iterative availability algorithm based on Valterra series is presented in time domain to cool spare system with two units, and its uniqueness and convergence are proved. Comparing the iterative algorithm with the algorithm based on Laplace transform, it indicates that the iterative error is small and acceptable. Application results show that the iterative availability algorithm can easy realize the resolution for Markov renewal equation when the life distribution and repair time distribution are bounded function.
Modified Woodward synthesis method and application to design the feed of large aperture antennas
Han Yanju, Lü Shanwei, Wang Jie, Nan Rendong
2004, 30(12): 1173-1177.
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A new method of antenna directional pattern synthesis using least-squares or pseudoinverses is presented here ,which is based on the analysis of traditional Woodward-Lawson synthesis method and other modified methods. This new method combined with array beamforming technology is used to design the elementary directional pattern of large aperture antenna/FAST(five-hundred meter aperture spherical telescope). The number of samples can be either equal to or larger than the dimension of antenna arrays in this presented method.And there is no constraints in the synthesis areas.So the synthesized beamforming is much more flexible, and has much wider application situations.
Analysis of data compression algorithm and its improvement in ATN
Yang Chenglei, Zhang Jun, Liu Feng
2004, 30(12): 1178-1181.
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To solve the data compression problem and improve the transmission efficiency in the ATN(aeronautical telecommunication network) mobile communication network, the data packets headers compression algorithm of CLNP(connectionless network layer protocol) is discussed in detail. The relationships of transmission efficiency, compression rate and packet length are given by analyzing compression procedure and capability. Combining ESIS(end system to intermediate system) protocol, an improved header compression algorithm of CLNP data packet is presented in the IDRP(inter-domain routing protocol) routing algorithm. The impression efficiency of packets headers is analyzed and the correlation between impression efficiency and packet length is given. The simulation results showed that the new algorithm could promote the compression efficiency of data packets and transmission efficiency of the network.
Multi-fractal and its application in terrain character analysis
Cao Hanqiang, Zhu Guangxi, Li Xutao, Xia Wenfang
2004, 30(12): 1182-1185.
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The multi-fractal spectrum of natural surfaces was computed and analyzed with the multi-fractal method. The parameters of multi-fractal spectrum were used to describe hierarchically refined structure of terrain and pop out the singularity characters of local area. Thus, the exact characterization of terrain surfaces obtained, the areas that have distinct thumbprint can be selected from complicated terrain. Combining multi-fractal spectrum parameters with the fractal dimension of single fractal, the terrain areas can be classified, and selection of flight path can be done. The results of experiment show that multi-fractal spectrum function is effective and better than single fractal in acquiring terrain character information, the difficulty in classing of terrain when the fractal dimensions are nearly same is solved. Multi-fractal spectrum is more fit for description of complexity and fluctuation of terrain, and can be used effectively in navigation and flight path programming.
Gravity balance technique installed on six-freedom spacecraft docking test table
Zhang Guangyu, Zhang Chongjun, Zhao Xuezeng
2004, 30(12): 1186-1190.
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To balance gravity, a balance set with high respond speed and precision was designed. The set adaptable to high and low temperature was installed in the inside of the docking mechanism. Relative techniques are introduced, such as spherical gemel hoisting mechanism that made the active docking ring rotating in three-dimensional direction, intelligent gravity balance technique that could provide the force with high speed and precision to balance gravity and could automatically follow with the active docking ring, two-dimensional translation wheel technique that ensured balancer following the active docking ring. The friction and inertia resistance were very small by the design of lessening weight. An experiment about the wheel design was done. The results show that the equivalent weight friction coefficient is only 0.004 17. So the respond time of the whole design should be less that 10 ms. The error of simulated weightlessness is about 1%~2% in each direction.
Research of missile random maneuver strategy
Yang Youchao, Jiang Yuxian
2004, 30(12): 1191-1194.
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A kind of random maneuver penetration strategy with unknown maneuver law is studied. The randomicity of the maneuver can ensure the missile's high penetration probability. In analyzing the model of interception-penetration, linearplanar relative movement equation was used. Using the adjoint system method, analytical solutions of interceptor's root-mean-square miss distance are derived from the case where the penetration missile adopt random maneuver strategy. The effect on the interceptor's root-mean-square miss distance for the change of some parameters is analyzed. Using penetration probability as the evaluation criterion, the validity of random maneuver strategy with the flight time in normal distribution is discussed.
Distributed part parametric design system based on COM/DCOM
Li Bo, Wang Rongqiao
2004, 30(12): 1195-1199.
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To implement the distributed part design based on UG(Unigraphics), two application development modes of UG were compared, and a universal parametric design method on the basis of a part library was presented. Through UG external programming, and utilizing COM (component object model), a universal software component for part parametric design was written, and then with the help of DCOM (distributed component object model), the distributed design using this component was achieved. Finally, considering the 3-tier network model, a distributed part parametric design system integrating this component was developed, which implemented the parametric design in a LAN (local area network) environment．
Fatigue damage accumulation model based on stiffness degradation
Qi Hongyu, Wen Weidong, Sun Lianwen
2004, 30(12): 1200-1203.
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Damage of composite materials is very complex under static and fatigue loads. It is important for mechanical behavior to model the damage of composite materials. To simulate fatigue damage and predicate the fatigue life of composite material, a new fatigue model is given according to the strain equivalence principle and considering the deficiency of fatigue damage accumulation. T300/KH-304, which is recently studied, is a high capability composite material for aero-engine. All samples were tested in an SHIMADZ servo-hydraulic fatigue machine under computer control. The load was cycled at a frequency of approximately 4.1Hz. Samples were carried in the constant amplitude fatigue test of the composite materials under different stress levels. This damage model was set up for T300/KH-304 laminate. The result of this model prediction is closer to the test than using S-N cure. The relative error is less than 2.4%. The fatigue damage evolution law of the composites materials could also be described. This model need be studied further.
JCVM resolving optimization design and implementation
Chang Qing, Jin Wei, Li Chunlong, Zhang Qishan
2004, 30(12): 1204-1207.
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To solve complex resolving and slow runtime problems of traditional JCVM(Java card virtual machine), the separate resolving solution was proposed according to the special structure of off-card and on-card JCVM. The static resolving out of card and the dynamic resolving within card was discussed, and the pseudoinstructions were introduced to transmit the middle result. Benchmarks show this special resolution will reduce the quantity of the code, shorten the runtime, and improve the whole capability of JCVM.
Novel method of image compression based on associative memory system
Li Yundong, Zhang Qishan
2004, 30(12): 1208-1211.
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To study the traditional neural networks which were featured as slow convergence and poor generalized capacity in image compression, a novel method of image compression based on associative-memory-system neural network was proposed. Associative memory system was constructed by newton's forward interpolation polynomial, and was used to establish model for image data. First, image data were devided into many blocks. And then each block was utilized to train associative memory system and charecteristic data can be abstracted after training. Charecteristic data's number was less than original data block, most of charecteristic data were limited to a range near to zero. Finally, all the blocks' charecteristic data were ranged by special order and entropy encode was expoited to code these charecteristic data. Experiments show that the method is effective for image compression. Compared with previous neural networks used in image compression, this method is free of training in advance and converges more quickly.
Research on integrated penetration of the anti-ship missile
Wu Qiang, Jiang Yuxian
2004, 30(12): 1212-1215.
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The integrated defence system for the important targets on the sea is composed of multilayer interceptors and soft defence means. In order to attack the targets effectively, the antiship missile must get through the integrated defence system safely. Corresponding penetration maneuver is adopted according to the various defence means used by the ship. Security trajectory or porpoise maneuver is adopted in the penetration process to the long-distance interceptor.To penetrate the short range missile, the snaking type maneuver or a new maneuver method-random maneuver is proposed. To evade the cannon on the warship, trajectory of goat-jump is proposed. Furthermore, Pattern recognition of the point target behavior is used to the soft defence of the warship. For the various penetration strategies and the integrated penetration strategy, the design plan and the parameter selecting principle are given. And finally, the multifarious penetration strategies and the integrated penetration strategy are validated by statistic simulation results.
Research of accelerated corrosion test method of zinc, cadmium plating on high-strength steel
Liu Huicong, Zhu Liqun, Du Yanbin
2004, 30(12): 1216-1220.
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Using three accelerated corrosion tests in the lab, the relativity of accelerated corrosion in the lab and Xiamen marine atmosphere corrosion was studied to the zinc and cadmium plating coatings on the high-strength steel. The three methods selected are the accelerated salt spray test, orthogonal dipping test and resultant seawater dipping test. A linear regression equation is obtained with a correlative coefficient equal to 0.995 2(remarkably correlative) for the zinc plating. The results show that, the accelerating effect is remarkable for the zinc and cadmium plating coatings in the accelerated salt spray test as well as for the cadmium plating in the orthogonal dipping test of the solution without S2-. And the accelerating action of the resultant seawater dipping test is effective to the cadmium plating.
Numerical simulation of separation flow around flaps with varied gap size
Chen Yingchun, Zhang Panfeng, Wang Jinjun
2004, 30(12): 1221-1224.
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The flow around the plate flaps with base vent was studied by numerical simulation. The Reynolds averaged Navier-Stokes equations were solved by SIMPLE method combined with two-layer zonal boundary layer model. The flow structure depends on the interaction of the separated shear layer from the up edge of the flap and the jet from the base vent. The intensity of the jet is caused by the base vent size and affects the flow structure around the flap. There are three kinds of flow patterns occurred with different base vent sizes. They are closedsingle vortex re-circulation region, jet & re-circulation region and the closed two vortices wake of flat plate region. The separate points of these three regions are g/h=0.2, 0.4, here g and h are the sizes of base vent and the flap width, respectively. For the small gap size (0.2<g/h<0.4), the flaps all have a large suction re-circulation region, which is similar to that of the case without vent. Hence, the base vent will not reduce the static efficiency of the flap on the wing.
Research on domain analysis and modeling
Zhang Wen, Huai Jinpeng
2004, 30(12): 1225-1230.
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Based on the communication system model in the Information Theory, a three-dimensional domain concept model is proposed to depict domain exactly. Thefirst dimension is information encoding format; the second one is action of information operation; the third one is atomic goal of information system. A micro-component model, which is the basic unit to construct arbitrary components, is proposed and depicted exactly in the projection on the encoding-action plane of the three-dimension model. Using the method of PAD(projection analysis of domain), a common domain architecture modeling method based on the soft-bus is proposed to resolve the problems in the modeling. The soft-bus can transmit the mixed structure of information flow and control flow in the architecture, divide the collaboration policy from the function services and predigest the control operation for domain architecture. The method above is applied in the e-government domainas an instantiation. SoftProLine, a flexible software produce platform, is given as a customizing tool to develop various e-government applications. It can satisfy the requirements of users with high quality, high flexibility and high efficiency.

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