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2004 Vol. 30, No. 07

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Requirement pattern
Sun Zian, Zhou Bosheng
2004, 30(07): 583-587.
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In order to resolve the problem of requirement reuse during software development process, activity graph in unified modeling language(UML) was extended to be applied to modeling for software requirement capturing and describing. Description language of requirement pattern based on process model was presented by referring to the usual describing mode of pattern. Definition of the language included name of pattern, domain, context, problem, forces, solution, implementation, examples and related patterns. Descriptions of context, solution and related patterns were defined, and guidelines for development and implement of requirement patterns were given. The description language of requirement pattern implements reuse of software requirements and its application can increase efficiency of software development.
Optimization design of brushless DC motor for flight control
Wang Ziqiang, Zhang Long, Huang Y
2004, 30(07): 588-592.
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Development of electromechanical actuation system for flight control is one of the most important technologies in the path to all-electric airplane. Brushless DC motor of high speed and high power density is the key in the system. In order to solve the problem of non-liner optimization, the genetic algorithm was adopted. The method of compond target function variable weighting was adopted for solving compond target optimization problem, and compond target was put into single target . In order to optimize all fields in calculation, the method of discrete group with random, random cross operation and variation operation was adopted. Because the optimization result is discrete, excellent individual protect plan was adopted to quicken constringency. Satisfied with the technical request, the volume and weight of the motor, moment of inertia of rotor , electromechanical time cost were reduced, and power density of brushless DC motor was improved by means of calculation.
Measurement of horizontal load subjected to aeroplane undercarriage tyre
Shi Haiwen, Xing Yufeng, Fu Yonghong, Zhang Daqian
2004, 30(07): 593-596.
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　　The mathematic model of predicting the horizontal load subjected to aeroplane undercarriage tyre based on the drop-tests was built by analyzing dynamic loads acting on drop-test platform which is supported by three-poles, and the coefficients in the mathematic model were determined by means of the least-square method according to the results of static tests. Then the horizontal load to aeroplane undercarriage tyre can be obtained more accurately by making use of the proposed model and results of drop-test simultaneously. The practical usesof the proposed method shows that it is more reasonable and more reliable than the method used in former Russia.
Computational analysis of two fluidic thrust-vectoring concepts on nozzle flow field
Luo Jing, Wang Qiang, Eriqitai
2004, 30(07): 597-601.
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Two-dimensional internal flow field of thrust-vectoring nozzles was calculated at two fluidic thrust-vectoring concepts of shock vector control and fluidic throat skewing. Base on the partition method of quadrangular structured meshes which were densified partly, the Navier-Stokes equation was solved by means of second order upwind disperse schemes and two-equation turbulent model, and the thrust-vectoring performance of fluidic thrust-vectoring nozzle was got through numerical simulation of internal flow field. The results indicate that for shock vector control, small nozzle pressure ratio and large inject mass flow rate would result in larger vector angle; for fluidic throat skewing, smaller flap injector angles would result in larger vector angle without thrust loss; fluidic throat skewing concept is prospective for its smaller thrust loss, lower nozzle weight and cost.
Processing model of rake and flank faces of ball-end cutters with a virtual axis grinding machine
Pei Baoqing, Luo Xueke, Chen Wuyi
2004, 30(07): 602-605.
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　　The process to grind ball-end cutter is the most complex in all the tool grinding processes, especial for the rake faces and flank faces of the cutter. They are the research hotspot now. The structure of the virtual axis machine is different from the conventional machine. So its movement control characteristic is different. These characteristic must be taken into account. Two machining models were researched,which were the Archimedes spiral curve and the circle path curve of the ball end cutter rake faces. The position control parameters were calculated when grinding these two curve models. Based on the machining curve model the processing technology was presented according to its special features of the 6UPS machine. The processing technology proposed can simplify the machining model and increase machining efficiency and precision.
Computer simulation of residual stress for cold rolling prestrectching board
Zhao Lili, Zhang Yidu
2004, 30(07): 606-609.
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To eliminate the residual stress formed during the process of Al board cold rolling, the distribution of stress in the deformation region was stimulated by elas-plastics large deformation finite element analysis. Analyzing the effects towards residual stress from different rolling loadcase, the value of cold rolling residual stress caused by different compress was gotten; Analyzing parameters stretching toward different rolling loadcase board, the effect of the residual stress elimination influenced by stretching force and stretching deformation was figured out. The simulative results show that the method of the proper stretching (about 2%) can evenly and partly eliminate the residual stress, reduce the effect toward the following manufacture induced by the residual stress.
Design and implementation of materialized cubes genetic algorithm
Sun Huiqin, Xiong Zhang
2004, 30(07): 610-613.
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Multidimensional data cubes are composed of base cube and other cubes aggregating on base cube. Since response time should be small, query optimization is critical. Materializing multidimensional cubes is a good solution. Partial materialization gives some good tradeoffs between the storage space used and the average time to answer a query. In order to materialize an appropriate cube subset, a heuristic genetic algorithm was proposed. The algorithm can converge quickly and has the ability of optimizing globally in the condition of the given space. It can also satisfy the requirement of different query frequency of views. The experimental studies indicate that the genetic algorithm have good performance.
Analysis of time-domain modes in FDTD-diakoptics
Yang Zhengguang, Su Donglin, Li Mei, Lü Shanwei
2004, 30(07): 614-617.
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　　It is very important to choose proper time domain modes when microwave structures were analyzed by time domain Diakoptics. Two dimensional Bessel functions is proper time domain modes in time domain Diakoptics. One dimensional Bessel functions expand theorem was extended to two dimensional, the completeness and orthotropic of two dimensional Bessel functions were proved. Based on analysis of electromagnetic field distributions for such open microwave structures as coplanar strips, the zero and one order Bessel functions were proved to be the proper time domain mode functions. The results of this method and the finite difference time domain (FDTD) were compared and there are good sameness between them.
Multi-access interference suppression in DS/FH communication system
Liu Jicheng, Shao Dingrong
2004, 30(07): 618-622.
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According to the thought of multi-users detection(MUD)used in direct sequence code division multi-access (DS-CDMA) system, partial parallel interference cancellation(PPIC) technology was put forward to suppress multi-access interference(MAI) in direct sequence/frequency hopping spread spectrum multi-access(DS/FH SSMA)after analyzing the effect on system performance by parallel interference cancellation(PIC). Bit error rate(BER) closed expression was deduced and up-limited expression of system performance estimation was also acquired. Simulation results demonstrate that PPIC technology can suppress MAI effectively in DS/FH SSMA, and system capacity can be improved. The simulation was accomplished under AWGN, system performance will deteriorates to some extent under fading channel and low signal noise ratio(SNR)condition.
Negative drag phenomena of aircraft in dynamic pitching process
Guo Hui, Lian Qixiang
2004, 30(07): 623-626.
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Aerodynamic characteristics of a simplified aircraft model pitching with constant pitch rate were studied in a water tunnel. Dynamic force measurement and flow visualization were made simultaneously. The three-component forcemeasurement balance was internal type and fixed to the sting, and the flow over the wing was visualized by hydrogen bubble method. In the pitch-down process with reduced pitch rate k larger than 0.11, negative drag phenomena were detected at certain positive angles of attack. Analysis of the force measurement and corresponding visualization results show that during the pitching down process, the interaction between the attaching flow of higher speed near leading edge and the stagnating fluid in the separation region causes an increase of pressure on upper surface of the wing, which causes the negative drag at a positive angle of attack. The magnitude of negative drag depends on the reduced pitch rate and the start angle of attack.
Performance analysis of linear clustered aerospike nozzles
Wang Changhui, Liu Yu, Qin Lizi
2004, 30(07): 627-630.
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To investigate the performance of optimized aerospike nozzles, the effects of thermal parameters variation in gas flow on aerospike nozzles performance, and to compare the altitude characteristics of bell nozzle and aerospike nozzles with the same area ratio, a numerical program was developed by employing an implicit lower-upper(LU) diagonal decomposition scheme and monotone upstream-centered scheme for conservation laws(MUSCL)-type approach. The control equations were three-dimensional Reynolds averaged Navier-Stokes equations and Euler equations. The performance of round-to-square cell was calculated. The effects of thermal parameters that were frozen or varied on aerospike nozzles performance were presented. The altitude characteristics of aerospike nozzles and bell nozzle were also compared. The results provide reference for the development of aerospike nozzles.
Effect of virtual coupling cell to the haptic system
Luo Yangyu, Wang Dangxiao, Zhang Yuru
2004, 30(07): 631-634.
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The influence of virtual coupling cell on the stability and transparence of force interaction system was discussed, under the information flowing mode of impedance display. According to their special physical character, individual spring or damping cell is in series or in parallel connection with different virtual environment. Concerning a 1-DOF force interaction system, when the driving-point element of the environment is spring, the spring and damping cell is respectively in series connection with the environment as example. Through comparing with the original system, the influence of virtual coupling cell on the system stability and transparence was derived. The simulation results meet well with the analysis. In control design of force interaction system, reasonable choice of virtual coupling cell can effectively improve the system stability.
Interaction between laser and propellant gas
Zhu Dingqiang, Zheng Liming, Cai Guobiao
2004, 30(07): 635-639.
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Base on the characteristic of laser propulsion, an investigation was performed to find out the mechanism of the interaction between laser and propellant gas. The breakdown process of propellant gas was studied, calculation method of breakdown threshold value was obtained, the breakdown threshold value of hydrogen and air were calculated; the inverse bremsstrahlung absorption process was studied, calculation method of inverse bremsstrahlung absorption coefficient was obtained, the inverse bremsstrahlung absorption coefficient of hydrogen and argon were calculated. The result can reasonable explain the "blanch" phenomena and plasma instability in laser propulsion experimentation that is mentioned in some paper.
Lead and lag correction in vehicle navigation system
Zhuang Chaowen, Fu Li, Teng Jitao, Fan Yuezu
2004, 30(07): 640-643.
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The reasons were analyzed ,which caused lead and lag errors in vehicle navigation system. A new method was proposed, which using map matching(MM)to correct lead and lag errors in global positioning system/dead deckoning system(GPS/DRS) integrated navigation system. The method made lead and lag errors boil down to GPS errors, which could be emendated by map data on the basis of the observability of GPS errors along the vertical direction . A general Kalman filtering was constructed to process the information of corrected GPS and DRS later, which decreased lead and lag errors in the integrated navigation system. Experimental results show the effectiveness of the proposed method．
Methods of realization of multilevel intelligent decision-making in CGF
Qu Xingda, Gong Guanghong, Wang Xingren
2004, 30(07): 644-647.
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To model senior commanders’ decision-making, a method based on likelihood ratio was adopted, and for junior commanders, a method based on fuzzy logic was employed to model their decision-making. The method based on likelihood ratio could fuse the information from different sources so as to make a reasonable decision output. The method based on fuzzy logic resulted its decision outputs from the commanders’ personal characters, experience and the environment in the battle field and these outputs were taken as the information sources for the senior commanders’ decision-making model. The application of these methods indesigning the navy force of computer generated forces system shows that they are effective to model multilevel intelligent decision-making.
Parametric correcting method for dynamic mathematical model via dynamical response
Luo Zhangping, Xiang Jinwu
2004, 30(07): 648-651.
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Improvement of structural dynamical model using dynamical response was studied. The approach is correcting physical parameters of given finite element model using experimental steady displacement responses. The mathematical model for model updating was constructed through the constitutive relations error which is an energy norm derived by stress-strain relationship and inertial force in a continuum system. The parameter estimation couples with expansion to uncompleted experimental data, and a perturbation item was introduced to account for the dependence of expansion data on the parameter variation. An optimum iterative process wasemployed to calculate corrected parameters. Numerical example illustrates the presented method to be effective and valid for estimating physical parameters.
Combined house of quality oriented product planning
Wang Meiqing, Tang Xiaoqing
2004, 30(07): 652-656.
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Product planning requires accurate and integrated planning information. A combined house of quality (CHOQ) oriented product planning was presented. The CHOQ consists of quality house of customer requirements (CRs), quality house of product technical characteristics (PTCs) and complex house of quality. The methodology of setting up the CHOQ was put forward. The analytic network process (ANP) method was employed to weight based on the important levels of CRs and PTCs, which considered the interrelationships among the CRs and PTCs. It makes the result of product planning more accurate. The proposed analytic procedure took into account qualitative constraints (feasibility, resource utilization ratio, etc) and quantitative constraints (cost, time to market, etc) in product life cycle. A case was studied by using CHOQ to fulfill product planning.
Computation of cryogenic propellant discharge under zero gravity conditions
Tian Hui, Sun Bing, Gu Hongxia
2004, 30(07): 657-661.
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The discharge research of the residual cryogenic propellant used in the CZ-3A third sub class was studied. The liquid hydrogen and liquid oxygen cryogenic propellant flow inside of the two different discharge pipeline was calculated. The liquid propellant will be vaporized, which attributes to the pressure depression along the pipeline. The gas-solid or the pure gas flow appears at a certain location. According to the each case of the flow, the model and the control equations of pure liquid, gas-liquid, gas-solid and pure gas was used respectively. The results show the pipe 1 is better when the liquid hydrogen is discharged and the pipe 2 is better when the liquid oxygen is discharged. The flow parameter at the pipeline exit through calculation is useful for further study.
Parametric faults detecting with multi-frequency test applied in ATE
Zhang Wei, Shen Shituan, Li Yihua
2004, 30(07): 662-665.
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Assisted with the sensitivity of the linear analog circuits, the feasibility of parametric faults detection was analyzed through the maximum fault errors acquired at the sensitive frequencies, a stimulation matrix and its stimulation expression were put forward on the test points information. A united stimulation acquisition algorithm was designed for detecting the faulty circuits under automatic test equipment in order to decrease the test cost. The fault detection effect illustrated in the simulation result shows that this method can magnify the fault errors, and help discriminate the faulty signals according to their sensitive frequency responses under different test points.
Non-interference test method of embedded system software
Zhang Jiong, Jin Huihua, Shang Lihong, Chang Sheng
2004, 30(07): 666-669.
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Traditional test methods of embedded system software impose on the object system and the result of the test are not accurate enough as expected. Non-interference test (NIT) method can solve the problem. Not same with the traditional test methods, NIT is completely non-interference to the object software. By analyzing the basic characteristics of NIT, an application model of NIT was set up. There must be three modules in this model, include static analyse module, dynamic analyse module and data gathering subsystem which tracks the object system by hardware. Static analyse module figures out the static characteristics of the object software and tells the other two modulus how to gather the state data of the object system and how to understand the data. In all steps of the test cycle, NIT does not add any instructions executed only within the test round into the object program.
Collision avoidance algorithm based on ANFIS
Xu Aiguo, Gao Feng, Wang Jian, Zhang Liling
2004, 30(07): 670-673.
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A vehicle collision avoidance model was established according to adaptive neuro-fuzzy inference system. In order to improve rapidity of convergence, a hybrid algorithm was proposed. For some linear parameters such as consequent parameters, recursive least square algorithm was used to update it. For other nonlinear parameters such as premise parameters, steepest descent method was used to identify it. To get the teaching data to train the model, an experiment was designed. Global position system(GPS) module was adopted in the experiment to get the headway and velocity difference between lead vehicle and following vehicle. Based on the training data obtained by experiment, the model was trained and a control output was simulated. By comparing the simulation result and the experiment data, it shows that the model can simulate manipulation of driver accurately and even more smoothly.
Web-oriented knowledge description language
Wang Xianghua, He Jian, Qin Zheng, Jia Xiaolin
2004, 30(07): 674-678.
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An XML-based and ontology-supported knowledge description language (KDL) was first presented, which has three-tier structure(core KDL, extended KDL and complex KDL), and takes advantages of strongpoint of ontology, XML, description logics, frame-based systems. The XML-Based syntax of KDL was introduced, and the methods of translating KDL into first order logic (FOL) was given. The implementation of KDL on the Web was described, and the reasoning ability of KDL proved by experiment was illustrated. It is demonstrated by practice that KDL encompasses XML and resource description framework(RDF) model properties, and KDL has powerfully reasoning ability.
Calculation method of source terms in high temperature chemical nonequilibrium flows
Ma Hui, Wang Famin
2004, 30(07): 679-681.
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In the numerical simulation of hypersonic chemical nonequilibrium flows, species density may become negative at the beginning of calculation, chemical stiffness is the main reason that affects the calculation’s stability and convergence. Based on the basic theory of source term’s linearazition, two linearazition methods were chosen. One is based on the physical rules of chemical reaction flows. The method’s advantage is that can improve the calculation’s stability and can avoid the species’ density to become negative during the calculation. The other method is the time preconditioner method, which has the function of diminishing the stiffness of the source term. The method was proved to be well approximates the partial differential equations. The calculation result shows that this method can effectively avoid negative density’s appearance and accelerate the calculation’s convergence. So the method effectively improves the calculation’s efficiency.
Interval analysis method for vibration of composite laminate with uncertain parameters
Qiu Zhiping, Ma Yi, Wang Xiaojun
2004, 30(07): 682-685.
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A new method named interval analysis method, which solves the natural frequencies of composite laminate with uncertain parameters, was presented. Based on interval mathematics and Taylor series expansion, interval analysis method simplifies the uncertain parameters to interval vectors so that it can get the intervals within which the response of structure varies when less information of structure is known. The interval analysis method is efficient under the condition that probability approach cannot work because of small samples and spare statistics characteristics. The formulation of natural frequencies of composite laminate using interval analysis method was formulated. Two numerical examples of comparisons between interval analysis method and convex model were given. The results show that the solutions of interval analysis method are sharper than those of convex model.
Design of solution for network security authentication with EPASS1000
Xiao Mengqiang, Wang Chengjun
2004, 30(07): 686-692.
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Authentication is a very key part for network security. So the solution for network security authentication based on EPASS1000 was put forward. EPASS1000 is a portable device that is connected to computer via USB port and has a built-in MD5 encrypted algorithm, which introduces free-factor in plain text and result in the different cipher texts in different encryption processes. The solution integrates the security of EPASS1000 with the actual application of network perfectly. It depicts the implementation of security authentication process, constructs the logic model for network authentication and also gives an example program written in ASP(Active Server Pages), which solve effectively the problem about the network security authentication.

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