Abstract:Numerical analysis is made for the unsteady and steady, two-dimensional laminar natural convection in an enclosure caused simultaneously by the external heating and a local internal heat source. The velocities and temperature profiles are given, the average and local Nusselt numbers for the hot and cold surfaces obtained, and the equivalent relative intensity of the internal heat source, the critical equivalent relative intensity of the internal heat source and the transient control regime defined. The results show that there exist five flow patterns with changing the external or internal Rayleigh number, and the heat transfer performance for each flow pattern region is different.

Abstract:Based on the experiment, magnetizing characteristic and its mathematical model of iron for the reactance transformer DKB has been studied in this paper. Its simulating calculation model has been achieved and implemented by program. The result of the simulation is satisfactory compared with that of the experiment.

Abstract:This paper presents a transient mathematical model of the HVDC converters-Equivalent Circuit Method(ECM), which can describe all possible states of converter valves in a simple and explicit way. With the converter model, programs have been implemented for single and double bridge HVDC systems. The results of simulation to the normal and fault operation of HVDC system show that the method is flexible and reliable, and has the advantages of small calculation amount and less computer storage requirments. The programs based on this paper provide convenient, inexpensive and feasible tools for computer dynamic or transient analysis of the HVDC systems.

Abstract:In this paper, on the base of idealizing the asperities of discontinuity by statistical methods, the yield rule of discontinuity is considered as more practical nonlinear model from the other way(which is different from refcrence[1]. and set up the physical equatation by using the physical meanings of the model. Then the obvious equatations of yield rule and clilatancy of discontinuity is given, in order to evaluate the practical shear strength of discontinuity. In addition, the destroy state of discontinuity during shearing is described

Abstract:In this paper, the permeability of coal, porous rock (sandstone), fractured rock(limestone) varifies with different confining pressure is discussed. Exponential functions between permeability and confining pressure are concluded. As a primary exploratiotion of permeability, it is significant to study coal and rock seepage characteristics and methane emission prediction. It is also useful in mine methane drainage system design.

Abstract:A practical technique of smooth blasting in the formation rocks at qinjina coal mine in this paper is introduced. Based on the principal of smooth blasting, the relation between charge concentration, charge structure, spacing, discoincidence coefficient and coefficient of closely holes is respectively discussed. According to the theory of rock mechanics, the applied condilions is analysed.

Abstract:The products and kinetics of intermediate transfo atien early stlage in Fe-C-Mo alleys are studied with optical micrography and electron transmision mierography. it has been found that the bainite transformation carried out through formation of bainitic 1 asic unit.and its growth evolution. The overall kinetics and structural morphology showedthc diffusion charactcraslic of the process.

Abstract:In this paper, the dissolving condition of iron and vandium solidified in iron and the collecting method of the second phase vandium compounds in alloy steel are studied, the existing possibility of spreading phase vandium compounds in steel is discussed, which provide the possible conditions for concentration and electrochemical separation of the second phase vandium compounds. Using this method, quite reliable results in measuring vandium solidified in iron can be obtained.

Abstract:In this paper, a-method using the complex modal theory to identify physical parameters of system with viscous damping is discussed. A procedure is present to calculate the mass, clamping, and stiffness matrices from the measured data in time and frequency domains. The double least squares approach is used to identify modal parameters. In identification of physical parameters, the data of different measured point is used in calculation for more accurate results.

Abstract:The model for forecasting the development of the Science and Technology Development Zones(STDZ) and the High Technology Industry Developrhedt Zones (HTIDZ) is created with the help, of the forecasting theory and technology in system engineering, A scheme for handling the dynamic variables in the model is proposed. The development targets of the Chongqing Shapingba Science and Technology Development Zone in the coming six years are forecasted .by using the model. The model can be used widely to forecast the development of STDZ and HTIDZ and other similar social and economical systems.

Abstract:In this paper, based on the actual need of production, a new technic method-ZS method on duple fact dynamic balance of machine rigid rotators is presented for small-scale production. The unbalanced weight and direction are obtained by adding duple test weight and measuring the bearing amplitude to the rotator system. The primary principle is developed in detail and the rightness of the new method is proved out by the simulant test and the applied real example. The outstanding advantage of the new method is that the investment cost is low and the adaptability is strong. There is a spacial application value for the great dajority of the mid and small enterprises that produce rotators in small-scale but usually the rotator standards need to be changed.

Abstract:A new aggregation method for order reduction of linear continuous or discrete systems is proposed in this paper. This method is easy for system design and it makes the structure of the controller and the state observer simple. It also reduces the computation of the system design.

Abstract:A controller employing self-tuning control and feedforward technique for high precision control of high temperature electric furnaces is presented in this paper. The mathematical model of these furnaces and the whole control algorithms are discussed. Experimental results have proved the effectiveness of ibis controller.

Abstract:In this paper, the mathematical model and the three-dimensional finite clement formulation of inverse problem in electrocardiography (ECG) under a general inhomogcneous and anisotropic configuration of the torso conductor is focused on. The following points are especially considered: 1. The mathamatical model is described by a differential equation instead of the Fredholm integral equation. 2. A kind of special boundary value problem is defined as ill-posed boundary value problem. 3. A group of finite element formulation, in which the method that treats anisotropic medium, is built up. 4. The calculating method of ill-posed boundary value problem is discussed.

Abstract:本文对色散方程μ_t=aμ_(xxx)构造了一类带参数的三层显式八点格式,其局部截断误差为0(τh+h~2),稳定条件为│aτ/h~3│≤3.1099。在目前尚未看到更好的结果。

Abstract:In this paper,we study the approximation of involute profile by moor-shaped ring section. By using the minimax method, we find parameter of the best approximation moon-shaped ring section of invelute piofile. The error of approximation is 35% - 70% that of [1] and [2]. Thus the approximation precision of dressing a wheel for involute gear forming-grinding by approximating method has been greatly improved. In order to simplify calculation, the error function is defined according to the implicit equation of curve and its rationalization is proved.