Abstract:This paper gives a general solution for solving elastic bending problem of rectangular thin plates，and then the intergral constants are determined by means of boundary conditions，This method is simpler and easier than superposition method.

Abstract:In the paper，the influence of erosion at the surface of nozzle throat on ballistic behavious for"761"sustainer is emphatically analysed. The author has derived equations，relating to the change of the pressure and thrust of sustainers caused by erosion as time goes on. The pressure and thrust values，calculated by the obtained equations，are compared with the results of experiments and discussed.

Abstract:This paper states the app1icalion of stale-space method to the analysis of the dynamic characteristics of a variable thrust liquid propellant rocket engine and presents a set of state equations for describing the dynamic process of the engine. An efficient numerical method for solving these system equations is developed. The theoretical solutions agree well with the experimental data. The analysis leads to the following conc1usion: the set coefficient of the impulse width，the working frequency of the solenoid valves and the deviation of the critical working points of these valves are important parameters for determining the dynamic response time and the control precision of this engine. The methods developed in this paper may be used effectively in the analysis of dynamic characteristics of variable thrust liquid propellant rocket engines.

Abstract:This article discusses implication of middle category by means of concept of category. Features and effects of middle category are expounded in view of interactions.

Abstract:An integral expansion theorem is derived in this paper. On the basis of the theorem，a defining function in closed interval with condition of expansion in Taylor Series can be expanded in basis eigenfuction. And that expansion coefficient always contains i-integral of the function in the closed interval. Then an example on applying the theorem for guidance is given.

Abstract:When a high velocity vehicle reenters the atmosphere，its surface is Surrounded by a plasma sheath with high temperature. In the region of a certain altitude，the communication between the vehicle and the ground will be discontinued，which is the problem of communication discontinuity in reentry. Some methods to diminish discontinuity have been tested abroad; each of them has its advantages and disadvantages.This paper discusses the possibility to，diminish electronic density in the plasma sheath by using electric field. It is expected to be a simpler physic method for overcoming the communication discontinuity in reentry.

Abstract:In this paper，a new method for writing the state equations is developed. The advantage of the method is that one need not write any differential equations. Especially，the procedures of e1iminating unstate variables can be avoided. A method is a1so presented for checking the results.

Abstract:This article explores interpolation methods for range readings of P.D. radar. Two methods，difference interpolation and ratio interpolation are given; quantized interpolation method is also discussed. The effect of finite duration of sampling pulse and the influence of noise to the interpolation are analyzed and estimated.

Abstract:An aided analysis of Interferometer by means of computer simulative calculation is presented here. A mathematical model of Interferometer angle measurement system and a method of computer simulation are introduced in this paper. Finally，an example of system simulation and analysis of results are given.

Abstract:In this paper，in view of equilibrium，we consider the concepts of solutions of game theory，and give a survey of its developments ever since theorm. Specially，we discussed the advances about v N-M solution.

Abstract:The minimum Spanning tree problem in which a given vertex is required to have a fixed number of incident edges was solved by F. Glover and D. Klingman. This paper give a simple algorithm finding the second spanning tree with a fixed number of edges at a vertex，and extend this algorithm to finding the second order-constrained base of Matroid.

Abstract:In this paper，we have given a concept of greatest common factor and least common multiple in the nonempty set of integers with the nature of usual greatest common factor and least common multiple. Applying this concept，we incorpoate the characteristic number of a group's element and the characteristic numbers of a ring and field. Besides，We have proved that the greatest common factor and the least common muliple are existential for every nonempty set of integers and，unique for definite nonempty set of integers.