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1998 Vol. 24, No. 1

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Study of the Simulated Test for the Intergranular Corrosion of LY12cz Al Alloy
Li Di, Zhang Qi, Wang Dizhen, Guo Baolan, Zhang Yumei
1998, 24(1): 1-4.
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The intermetallic compounds of θ(CuAl2)、S(Al2CuMg)、MnAl6 and the pure Al(L1)were used to consist a multiple electrode system．This system was employed to simulate the grain boundary area of the LY12cz alloy．The mechanism of the intergranular corrosion of LY12cz alloy was studied by the electrochemical measurements,the SEM observation and the energy spectrum analysis with the simulate system．This paper confirmed the general believing that intergranular corrosion of the LY12cz alloy is caused by the formation of a multiple electrode system,which consist of the segregation of strengthening phases and the Cu-lack zone ,and locate along the grain boundaries．Besides,it is clear that in a Cl- containing neutral solution,the S phase is the main anode which results in intergranular corrosion．Firstly,the anodic S phase dissolves,secondly the Cu-lack zone and MnAl6 dissolve gradually with the S phase still acts as a main anode．In this way,an anodic dissolution path forms along grain boundaries,causing intergranular corrosion．
Miss Distance Analysis in APN Guided Radar Homing Missiles
Ding Chibiao, Mao Shiyi
1998, 24(1): 5-8.
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The miss distance formulas under a deterministic step target maneuver and initial heading angle error are derived when augmented proportional navigation guidance (APN) is used.And the formulas of rms miss distances caused by different radar measurement noise sources are derived with adjoint theory.The performance of APN is compared with that of PN.
Approximate Solution and Slotted Antenna for a Conformal Waveguide
Lü Shanwei, Gao Wenjun, Ying Jie
1998, 24(1): 9-12.
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A new waveguide made of changing a wide wall of a rectangular waveguide to a uniform curved wall is called conformal waveguide.A kind of expression of approximate solution for domain mode of the new waveguide,including symmetric,unsymmetric arc,parabolic arch,hyperbolic arch,elliptic arch,etc.,is constructed by using boundary condition of mental waveguide,variational method and boundary element method.By using the equivalence principle,an approximate calculating formula for equivalent resonant conductance of a narrow longitudinal half wavelength slot cut in the curved wall of the unsymmetric arc rectangular waveguide is derived,and the result is shown.Although this solution is approximate,it can solve the problem in designing the slotted antenna of such conformal waveguide.
Method to Distinguish the Stronger Scattering Area by Using A 3 D Distribution Analysis
Su Donglin, Li Jianhui, Han Xuewen, Li Qing
1998, 24(1): 13-15.
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The complicated target is approximated by amounts of patches.By discreting integral equations of physical optics,the scattering fields on each patch can be calculated.Thereafter the 3 D scattering property of a complicated target versus the contour of the target can be analyzed with the knowledge of the scattering fields.By combining the visual electromagnetics and computer graphics,the method to distinguish the stronger scattering area based on the 3 D distribution of scattering energy caused by a complicated target is developed.Some results have been obtained by using this method.
Control and Performance of a Turbosupercharged Piston Engine
Chen Yan, Wang Hongming
1998, 24(1): 16-20.
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The principle of control of a turbosupercharged piston engine wih Turbo Control Unit(TCU) is described.The parameters:ambient air pressure,engine speed and the throttle position(Tp) are detected and processed by TCU,which controls the waste gate of turbosupercharger.The charged air pressure and temperature are fed back.The Tp is setting by the pilot.TCU maintains the power of engine under critical altitude and keeps turbo speed beyond it.The engine performance can be calculated under standard and nonstandard atomosphere condition.The results coincide with the datum from the production corp.Bombardier Rotax,Austria,and the performance above critical altitude can be calculated either.
Creep Test Study of Single Crystal Turbine Blade Material
Meng Chunling, Wu Bin, Rao Shouqi
1998, 24(1): 21-23.
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he creep test of DD3 single crystal material which is made in China is carried out in order to meet the needs of creep calculation and analysis of the turbine blade made of DD3,and giving out the method of fitting creep curves according to the test's results.The creep constants,that are more exact and accord with the test curves,A,n and p of Norton formula are obtained by fitting the test creep curves and modified by finite element analysis of blade of single crystal.
Influence of Gas Injector Geometry on Atomization Performance of Horizontally Injecting Effervescent Atomizers
Liang Xueping, Guo Zhihui, Xu Hang, Gu Shanjian
1998, 24(1): 24-27.
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The atomizing performance of effervescent atomizers are examined with special emphasis on the influence of gas injector geometry on spray characteristics.A particle dynamic analyzer (2D PDA) is used to measure mean drop size,drop size distribution and velocity distribution.All tests are carried out at normal atmospheric pressure and temperature.Water injection pressures are varied from 0.20 to 0.60 MPa and air/liquid ratios from 0.04 to 0.12 by mass.Three different gas injectors are used,one having 4 holes,each of 2.2 mm diameters and the others 20 holes of 0.7 and 1.0 diameters.They are used in conjunction with three mixing tubes of different lengths.The results obtained show that the changes in the number and size of the gas injection holes have significant influence on atomization qualities of horizontally ejecting effervescent atomizers.Moreover,there is an optimum length of the mixing tube leading to higher atomization quality.However,when swirling the liquid,atomization quality appears to be slightly improved.
Application of Semi Rigid Trailing to Ram Air Turbine Performance Calculating
Zhang Jianfeng, Liu Siyong
1998, 24(1): 28-30.
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Rigid trailing vortex model consistent with Goldstein hypothesis is often employed in propelles lifting line (lift surface) calculation on the condition of light load,but presents certain errors on the condition of heavy load.Semi rigid trailing vortex model consistent with Theodorsen hypothesis extents Goldstein trailing vortex to heavy load condition.Application of Theodorsen trailing vortex model to ram air turbine lifting line calculation is discussed.A model ram air turbine has been employed to calculate.The results show reasonable distributions of trailing vortex pitch,induced velocities,circulations and blade element wind power utilization coefficient.Wind power utilization coefficient agrees well with experiments.
Reviews and Prospects in Turbulent Drag Reduction over Riblets Surface
Wang Jinjun
1998, 24(1): 31-34.
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The experimental investigations of turbulent boundary layer flow,turbulent coherent structures,turbulent drag reduction and its mechanism have been reviewed.The experimental velocities cover subsonic,transonic and supersonic flows,and the content includes: (1) flow over flat plate,revolution body and wing with riblets surface at zero angle of attack;(2) the effect of pressure gradient,angle of attack and slide angle;(3) the burst characteristics,characteristics of turbulence,the streak structure in the near wall region and the drag reduction mechanism.In order to reduce the skin friction efficiently,more research works should be done on the characteristics of turbulent boundary layer,turbulent coherent structures and the mechanism of turbulent drag reduction for flow over riblets surfaces.
Solution of Euler Equations on the Two Dimentional Unstructured Grids
Yin Xingyu, Wu Zhilei, Zhu Ziqiang
1998, 24(1): 35-38.
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Both Delaunay triangulation method and advancing layers method for generation of unstructured grid are discussed.A combination of both methods to form an unique method,i.e.,the background grid is generated by using Delaunay method and space computational grid over the whole flow field is generated by advancing front method,is suggested in the present paper.The new approach improves the quality of grid and efficiency of the computation.The Euler equations on unstructured grid are solved by cell center scheme of finite volume method.Numerical examples show that the corelation of the computational results with experimental data is favorable and the needs of N S equation solver is obvious for both case of airfoil in transonic flow and multi element airfoil in subsonic flow.
Transient Analysis of Nonlinear Elastic Impact between Two Rods
Xing Yufeng, Zhu Dechao
1998, 24(1): 39-42.
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The two rods in colliding are treated to be an integrated rod system of vibration, so this nonlinear elastic impact problem is dealt with as a problem of conventional dynamic response analysis of the system under the initial condition that the impacting rod is subjected to a given velocity distribution. The basic equation, the boudary conditions and the initial conditions of the problem are given, the analytical solution without contact deformation and with linear contact deformation are derived, and the new linearization method and the practical procedure of the linearization method with nonlinear contact deformation of the problem are presented.Finally, numerical results show that the above methods and the approaching procedures are feasible and correct.
Dynamic Model of Human Spine to Impact Loading
Zhang Jinzhi, Zhu Dongming, Mai Hanchao, Huang Zhizhong
1998, 24(1): 43-45.
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Establishing an human spine dynamic model is an significan event to study spine injured biomechanics of pilot's ejective injury,parachute opening,landing and study the endurance to impact loading on human spine.In this paper,the Huston's method of Kane's equations is developed so that it can be applied to the multi body system including translation between the bodyies.The dynamic model of human spine is provided basing on these theories,while the big movement of spine is considered.The deformation of vetebra is far smaller comparing with the intervetebra disc,so the spine is considered into multi body system including rigid bodies (vetebra) and the flexible bodies (intervetebra disc).The computer solution correspond with the results of the large scale human impact test.The rigid coefficient factors and the damping factor of intervetebra joints are obtained.
Bending Effects Analysis of Disk Springs
Wu Hehua, Zhang Xing
1998, 24(1): 46-49.
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The linear moment theory of shells is applied to the analysis of bending displacements and stresses in disks with the membrane displacements and stresses obtained from the non linear membrane theory of shells as the initial states.According to the results of analysis,it can be confirmed that,the bending stresses in the disks play important role in disk selection but the bending displacements are negligible in comparison with the membrane ones.Hence in disk analysis,it is reasonable to determine the displacement field by nonlinear membrane theory and it is also both feasible and necessary to solve the bending stress firlds with linear moment theory.
Conservative Integral Photoelastic Method for Determination of Stress Intensity Factors in Fractures Mechanics
Guo Mingjie, Ruan Mengguang, Zhang Xing
1998, 24(1): 50-53.
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A conservation integral photoelasticity method is provided for determination of stress intensity factors in fracture mechanics.The displacement gradients in the expression of the concervative integral are expressed in terms of stress components.Then,the conservative integral can be evaluated by the interference fringe patterns in photoelastic experiments.Finally,the stress intensity factor will be determined by the J K-Ⅰ relation in fracture mechanics.Due to the path independent property of conservative integral,the difficuties encountered in the methods of mono parameter,bi parameter and multi parameter can be overcomed by this one.The agreements between the results given by this method and those obtained from the boundary collocation method are satisfactory.
Mechanical Analysis for Debonding Problem of Honeycomb Sandwich Beams
Miao Changqing, Zhang Xing
1998, 24(1): 54-57.
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A state decomposition analytical method is proposed for analysis of additional displacements,additional internal forces and energy release rate produced by debonding between face plate and core material of a honeycomb sandwich beam.Then the influences to the odditional displacement and energy release rate given by the core deformation of the undebonded beam segment are discussed.Finally,a simplified mechanical model is prosvided for debonding analysis.
Algorithm to Minimize Total Spanding Time on Parallel machine
Jing Ling, Huang Decai, Yang Wannian
1998, 24(1): 58-59.
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The problem of scheduling of a set of jobs on parallel machines is discussed.An algorithm to minimize the total spanding time (processing time plus waiting time) is described,in which processing time of a job can be different on different machines.The mathematical model of this problem is set up.The scheduling problem can be transformed into assignment problem,and the optimization solution can be obtained by Hungarian algorithm.The time complexity of the presented method is a polynomial bound scheduling algorithm.In the end a numerical example is given to explain the solution process.
Research on Drawing Wedge Test for Sheet Strips
Wang Xiufeng, Peng Weihua, Lou Jia
1998, 24(1): 60-63.
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From the theoretical analysis and numierical calculation on the drawing wedge processes of sheet strips,the law of the stress and strain distribution on the fan shaped deformation region,the change of the axial tension force,and the coefficient of the limit drawing are studied in this paper.Menwhile,the setup for the drawing wedge test is developed,and the drawing wedge processes of sheet strips are investigated experimentally.The analytical and numerical results are in basical agreement with experiment.Based on the above analyses,it is shown that the simple drawing wedge test of sheet strips can be used for replacing the cylindrical cup drawing test.
Algorithm for Rapid Codebook Generating Based on Fast Search
Liu Ping, Zhu Xinxiong
1998, 24(1): 64-67.
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Given a finite subset　Wand a vector x both in k-dimension space R\+k,the method to fast locate the vector in W closest to x is of great value in various applications,and would speed up the encoding for vector quantization and the iterative process of generating codebook based on SOFM algorithm. This paper analyzes the properties of SOFM algorithm and the existed fast encoding algorithms,and presents a new method to speed up the codebook generating. The advantages of the new method are in high searching efficiency and less memory requirement. The experiment shows that the running time of the new algorithm is only about 42% of the existing one's. The new algorithm proposed in this paper is of applied value in many fields such as pattern recognition and computer graphics.
Decision Problem in the Context of Delegated Implementation
Tian Kelu, Hui Yimin
1998, 24(1): 68-70.
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With analytic tools from agency theory,the decision problem in the context of delegated implementation is analyzed.First,assumptions about the specific context of the problem are made in compliance with agency theory,on the basis of which a general model is built.Then,the general model is decomposed into two correlated sub-problems:one is a pure-implementation problem,and the other is a decision problem.By doing so,the essence of the problem is observed directly. Later,attempts are made to further simplify the problem by trying to separate the n-agent-pure-implementation problem into n single-agent-pure-implementation problems; the possibilities of doing this and the relationship between these two kinds of problems are analyzed.Finally,possible research lines are directed in conclusion.
Fuzzy Analysis Approach to Project Risk
Yang Jianping, Du Duanfu
1998, 24(1): 71-74.
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Because there are lots of uncertain factors to influence a project,experts usually have to use some fuzzy words when they evaluate risks of a project.To evaluate quantitatively uncertainties of a project,this paper presents a new method of analyzing project risks.First,we can quantify these fuzzy words by using the fuzzy set theory,that is to say,we can express the project risks by using a kind of simple fuzzy number\_\_triangular fuzzy number;then we can judge the degree of the project risks by comparing the triangular fuzzy numbers,and the dominant project can be selected by comparing the risks of various projects.Finally,we also consider that how to quantify accurately uncertainties of a project is a very attractive problem,and we will make further researches on it.
Job Shop Scheduling by Simulated AnnealingAlgorithm Combined with Tabu Search
Han Limin, Huang Hongxuan, Feng Yuncheng
1998, 24(1): 75-78.
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This paper describes an approximation algorithm for the problem of finding the minimum makespan in a job shop.The algorithm is based on simulated annealing algorithm and tabu search,two generalizations of the well known iterative improvement approach to combinatorial optimization problems.First a start solution is found by the simulated annealing algorithm,then tabu search is used to seek the better solution in order to compensate the disadvantage of large running times by single simulated annealing algorithm.The algorithm in this paper is proved effective and efficient both in computation and convergence by analyzing the results of some experiments on it.
Grey Model of Calamity Forecast and its Application to the Calamity Forecast
Chen Yehua, Qiu Wanhua
1998, 24(1): 79-82.
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The grey system is a incomplete system of information.A new concept of \!grey number\" etc.is developed.A new analysis method is provided for the research of information and incomplete data.It is dealing with discrete raw data by using iteration addition generator method and converting to ordered sequence of number,namely grey method.A grey forecasting model for the calamity forecast is established in this paper by using duplex difference,and the application of this model is expounded by the forecast of drought and flood.At last,the fitting precision ofgrey for ecasting model is discussed.
New Scheduling Heuristic for the Permutation Flowshop Problem
Shen Yingjun, Huang Haijun, Wu Sa, Wu Jing
1998, 24(1): 83-87.
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The permutation flowshop problem,which is a class of NP problems that are often encountered in scheduling of manufacturing systems,has not been completely solved either in theory or in application. A new heuristic method,named WSH,is proposed in this paper to solve the permutation flowshop problem. This heuristic aims to minimize the total process time of all jobs. The comparison between this method and others reported in literature until now,is presented on the basis of results from many numerical examples. The results show that WSH,simple in structure and excellent in computational efficiency,is a good method to solve small-size and medium-size problems.
Deterministic Algorithm for Global Optimization
Liang Zhixin, Wang Rishuang
1998, 24(1): 88-94.
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A deterministic algorithm for global optimization is presented.The algorithm is one of covering methods which find the global minimum with required degree of accuracy.The principle of the algorithm is region cutting.The regions which the global minimum is not included are found and cut from deeply research.When we research some special functions,we can make a consistent net covering on the region.By calculating the function evaluations of the nodes,the regions in which function evaluation is larger are successively cut and the regions in which function evaluation is smaller are remained.At last,the global minimum is known to the required degree of accuracy.The algorithm requires the bound of the eigenvalues of the Hessian can be estimated and uses the bound to determine the stopping rule.Several numerical examples are presented at the end of the paper.
New Associative Memory System and Its Learning Convergence
Xing Chunfeng, Liu Zhongkan, Xu Ningshou
1998, 24(1): 95-99.
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A new high order Associative Memory System based on Newton forword interpolation formula (NFI AMS) used for implementing hign precision approximation to multi variable polynomial functions with arbitrarily given order is proposed.The learning algorithm of NFI AMS is designed.Moreover,it is proved that the NFI AMS learning always converges to a given multivariable continuous function with arbitrary accuracy under a wide condition.The AMS possesses the advantages over conventional CMAS type AMS less learning sample points,high precision of learning and much less required memory size,and also the advantages over multi layer BP neural networks in much less computational effort for training and fast convergence rate.The systems of NFI AMS has great potential in the application areas of intelligent control and signal processing,process modelling and pattern recognition.
Microlocalizations of Modules with Regular Singularities over Filtered Rings
Zhou Meng
1998, 24(1): 100-103.
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The microlocalized properties of a module over a filtered ring R are discussed by many papers in recent years.For example,Essen proved that if M is a module with regular singularities over a Zariski ring R,then its microlocalization Q\+μ\-S(M) is a Q\+μ\-S(R) module with regular singularities.But it is unknown that if Q\+μ\-S(M) is a R module with regular singularities.In this paper the regular singularities of the microlocalization Q\+μ\-S(M) are discussed as an R module while R is a Zariski filtered ring and M is an R module with regular singularities.An answer to the problem in suitable conditions is given.The result is proved that if M is a R module with regular singularities and the localized filtation on M is a good R filtration then the microlocalization Q\+μ\-S(M) of M is a R module with regular singularities.
Acoustic Emission Apparatus for Rubbing Diagnosis of Large Rotating Machinery
Wu Jian, Liang Jiahui, Li Huailing
1998, 24(1): 104-107.
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In large rotating machinery using filmatic bearing (turbogenerator,air compressor,etc.) there is a potential trouble from impefect installation or running conditions,a metals' contact between rotors and shells.The trouble is usully called rubbing.The advantage of AE technologe in the rubbing diagnosis and early detection is showed.Instead of classical AE characteristic parameters (counts,amplitude,energy,duration and the other ones) a new feature extraction by frequency analysis of AE envelop signals is discussed.Both research of AE process and field experements indicate that periodic components in the envelop spectrum related to rotational speed increase evidently at the beginning of rubbing production,hence are highly sensitive to the rubbing fault diagnosis.According to the new design an acoustic emission equipment for the rubbing diagnosis named BUAA AE testing system is developed and described.
Resistance Relexation of NiSiB Amorphous Films
Qi Xianglin, Cheng Xianan, Song Ruan, Gu Qihua
1998, 24(1): 108-111.
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A series of NiSiB films of various thickness were prepared by R.F.sputtering.The films were annealed at different temperature and for different time.The resistance of the annealed films were measured as a function of temperature during two or more heating cooling cycles.Measurements of annealed films showed that there were two forms of resistance versus temperature curves.One was reversible the other was irreversible.The resistance of the thicker films (>1000) increased with increasing temperature and the resistance of thinner films (<400) decreased with an increase in the temperature.The temperature coefficient of resistance may be positive or negative.From the relaxation of amorphous material these behaviours are disscussed based on the activation energy spectra and in terms of extatended Ziman theory for metallic glasses.
Flexible Redundant Robot Dynamic Planning with Suppressing Vibration and Joint Torque Optimization
He Guangping, Lu Zhen
1998, 24(1): 112-115.
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This paper addresses the dynamic planning of flexible redundant robot to depress the vibrations and to optimize the joint torgues.It has been revealed that both vibrations and joint torques are key factors which have to be deal with.If one take one sided approach to the problem,some torques or vibrations would diverg to infonities.The algorithm leveloped in the paper concerns with the two sides.Instead of conventional null spase method,the optinmal control theory has been used.The simulation has verfified the feasibleness of the method.
Wus Method for Forward Displacement Analysis of the Planar Parallel Mechanisms
Han Lin, Zhang Yu, Liang Chonggao
1998, 24(1): 116-119.
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The forward displacement analysis of the planar parallel mechanisms is studied by using Wu's method.Wu's method is a mechanical mathematics method for solving nonlinear equations.It can solve any nonlinear equations in limited steps.On the base of introducing theory of Wu's method,the problem is solved.The original equations of the problem is changed into triangulated equations in which a single unknown polynomial equation has 6th degree.The result shows that the planar parallel mechanism can have 6 different positions and orientations.In the end,a numerical example is studied.All the solutions for the example are listed.The presented method provides a new way for solving the other difficult mechanism problems.
Approximate Solutions of the Optimal AeroassistedCoplanar Transfer of Space Vehicle
Nan Ying, Xiao Yelun, Chen Shilu
1998, 24(1): 120-123.
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Green's theorem is employed to find the quantity relationship among the constraints of heating rate,dynamic pressure and lift in reentry flight.The paper deduced the approximate solution of the optimal aeroassisted coplanar trajectories under the three typical constraints.The performance index to be minimized are either heat input,the total dynamic pressure,time during the atmospheric flight,the time integral of the square of the path inclination;or maximize the time of flight during the atmospheric portion of the trajetory.An important conclusion is firstly obtained:under the three constraints above,the optimal aeroassisted coplanar transfers with the first forth kinds payoffs have the same optimal control laws.

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