STATE VARIABLE METHOD FOR DYNAMIC SIMULATION OF HVDC SYSTEMS

A flexible mathematical model used for dynamic simulation studies of HVDC systems which is based on the stale variable method is presented, and the correspongding computer program has been implemented. Generality, easy to use, and suitable to run on microcomputers are the main features of the model and the computer program. Therefore the model is easy to be extended for application. An example is given in the paper to verily the coneclness of the model and the program.     

Optimum Design for Pile Group Foundation and ItsApplication in Factory Building

On the basis of discussing the damage mechanism of cushion cap, a method of optimum design for pile group foundation is put forward in this paper.The piles are decorated on the cushion cap which makes the area of cushion cap minimum.The object function of optimum design for cushion cap is its volume and the binding functions are the requirements of shear, column die cutting, corner-pile die cutting and settlement for cushion cap.The optimum design has been done by a computer program. This method is used to design a factory building. The final result suggests that this method is highly effective and practical. A fair-scale economic efficiency can be obtained in ifs practical use.     

Optimal Load Curtailment in Bulk Power System Reliability Evaluation

This paper studies the question for considering optimal load curtailment in bulk power system adequacy evaluation. A minimization model of load curtailment is utilized for the contingency states which may have load curtailment. In order to calculate realistic bus indexes, two practical load curtailment philosophies are incorporated in the minimization model of load curtailment, which is achieved in computer program developed for bulk power system reliability evaluation. The minimization model of load curtailment, correlated algorithms, and flow chart of program are given in this paper. The effectiveness and availability of the model are verified from two case studies.     

THE QUASI-FULL LOAD METHOD FOR OPTIMUM STRUCTURAL DESIGN

This paper presents the quasi-full load method, which has many advantages. Its thinking is simple and direct. Its program is easily carried out, its convergence rate is fast and the optimal result is safe, reliable, economical and practical. This paper gives the mathematical model of the space trusses optimum design in practical project, and points out the shortcomings of optimum method often applied by engineers. The method and the peculiarity of quasi-full load structural design are gone into details.     

COMPUTER-AIDED ANALYSIS AND DESIGN FOR THE BASE STRUCTURE OF A MOVABLE TOWER CRANE

This paper is one of the achievements of the researchitem for computer-aided design of tower crane's steel structure.In thepaper,taking the well-base structure as an example,first the method establishing the mechanical model is explained for the base structure ofa movable tower crane.Then the math model of its optimal design andthe N-S figures for the computer program is described and calculatedusing discrete optimal technology.Finally the problems related to thedesign for the base structure of a movable tower crane are briefly illu-strated.     

A NONLINEAR PROGRAMMING MODEL AND ITS ALGORITHM FOR TRANSMISSION NETWORK PLANNING

The problem of transmission network planning is studied thoroughly by applying the mathmatical optimal tecqhniue in this paper. A novel approach is put forward for computer aided transmission network planning, which is quite different from what is based on D.C. load flow equations. A nonlinear transmission planning model is set up by regarding A.C. load flow equations as the system model. A practical model which can be solved more easily, and an united algorithm are obtained by applying the SUMT to the nonlinear model. The results of some practical examples indicate that this method can not only make the planning results more accurate, but also provide the voltage qualities and produce planning plans autometically and seek the plans optimally and fast.     

Application of Fractals in Architectural Shape Design

A computer aided method for architectural shape design was developed based on the L systems algorithm, the shape grammar and the space surface equation theory. Various 3D entities such as building grounds, building walls and building domes with fractal characteristics could be generated in a short time by using the computer program. These generative 3D entities were saved in a component database which could help to accumulate design knowledge through continuous expansion. A building could successfully be formed by the designers through selecting proper building grounds, walls and domes from this database. The effectiveness of the proposed method was approved with a case study.     

A MODEL SYSTEM OF A LONG-TERM PROGRAM OF EDUSATION DEVELOPMENT AND ITS APPLICATION

This paper studies a long-term program of education development in the light of the theory and method of system engineering.A complete mathematical-Simulant model system is used to describe the internal regularity of an edu-cation system inside a social-economic tystem,and to put forward a set of efficient method for education development programming.The mathematical-simulant model system dis-cussed in the paper is put to practical use in a regional education programming.     

Coupled Thermo-Elastic Contact Finite Element Method and It''s Application in Gearing

A new finite element method is presented in this paper to analyze the thermo- elastic contact problem with heat input on meshing tooth faces. The computational model of meshing gear has been established and the frictional heat input on meshing tooth faces is estimated. In addition, 2-D finite element analysis program for this kind of problem is listed. The test and practical examples are given to show the validity and versatility of this method.     

A New Method of Piece-Wise Solution in Faulted Power Systems with Variable Configurations

A new model and its algorithm are presented in this paper to simulate calculating the electric values of short circuit fault in large-scale power systems with variable configurations. The method proposed herein reduces the computer storage requirements compared with the available approaches. And it completely avoids the modification computation of nodal impedance (or admittance) matrices of the original networks and the repeated calculations for each type of faults.     

Design of Alternating Current Excitation Generators

In this paper,the design feature of Alternating Current Excitation Generators(ACEG) is discussed.The electromagnetic design program of ACEG is established for engineering practice.A PC based software for design has been finished.A sample ACEG is calculated with the software.     

OPTIMAL ACTIVE POWER ADJUSTMEMT OF LARGE HYBRID AC/DC SYSTEMS AFTER OUTAGE CONTINGENCIES WITH THE APPLICATION IN RELIABILITY EVALUATION

An optimal active power adjustment model is deve in this paper for hybrid AC/DC systems after outage contingencies. The objective of the model is to minimize the rejection of load when some elements are out of service, with adjustment strategy approaching practical system operation. A large number of outage contingencies are simulated when the Monte-Carlo Method is emyloyed to evaluate the system reliability, requiring fast calculation of each simulation. The model and computer method proposed in this paper satisfy such a requirment because of the application of concentric relaxation, recursive branch constraint treatment in linear programming and a direct method for B-1 matrix modification. This paper is concerned with the simplified steady state conditions of the system based on DC load-flow, which implies the reliability indices calculated are the measures about static loss of load. The results for a 14-bus hybrid AC/DC system are given.     

A PRACTICAL METHOD FOR SELECTING STEEL USING COMPUTER AIDED DESIGN(CAD)SYSTEM FOR REINFORCED CONCRETE FRAME

How to select automatically the disposition of steel bar in a computer aided design(CAD)system for reinforced concrete frame structure is aproblem relatedt ot he practicality and increasing capacity of the CAD system.This paper suggests a practical method for selecting steel bar of beam in framestructure with the application of knowledge and experience of the experts forreasoning and judging.The method is convenient for calculation.The results ofcalculation are in agreement with detailing requirement and usual engineeringpractice.The method has great practical value.     

Section Optimization Design of Steel-Concrete Continuous Composite Beams Based on the Finite Element Method

This paper introduces the efficient computer aided design method to optimize the section of steel-concrete continuous composite beams by combining FEM for structure analysis with optimization arithmetic and an efficient shearing force link model of steel-concrete composite beams.The authors established a finite element analysis model,optimization parameter model,optimization mathematics model of steel-concrete continuous composite beams and programs analysis file and optimization control file by using the ANSYS parameter design language. The optimum of the steel-concrete continuous composite beams section is obtained after computing and the optimization result indicates that this method is efficient in optimizing the section of steel-concrete continuous composite beams.So it could be applied extensively in the steel-concrete continuous composite beams section optimization design.     

EQUIVALENT CIRCUIT METHOD FOR DYNAMIC DIGITAL SIMULATION OF HVDC CONVERTERS

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.     

试论二次旋转组合设计的多样性及其统一

二次旋转组合设计是目前应用得较为广泛的试验设计方法，但因其设计方案和分析方法的多样性，给实际应用带来了不便。本文试图把握二次旋转组合设计的实质，弄清其各种类型之间的关系，力求使二次旋转组合设计在设计方案，统计分析，计算机程序上得到统一。     

CALCULATION OF AVERAGE SKY LIGHTING

Under the condition of average sky model,this paper studies the luminous flux arriving at the window and suggests the modified daylightingcoefficient method for estimating the area of the window.The method is simpleand easy to be carried out.And according to average sky luminance model,this paper has carried out the calculation of average sky lighting with a computer.The method described above is verified reasonable and applicable in engineering.     

Research on Calculation of the Automobile Air Conditioner's Cooling Load

In this paper a nonsteady heat flux equation for car body is established and the formulationof transmission function coeficient of the cooling load is derived. The composition of the automobile airconditioner's cooling load has been analysed and a computer program for calculating the cooling loadhas been compiled, It has proved to be exact from the example, So these results are of practical value.     

Development and Application of Computer Aided Roll Design System for Thread-steel-bar

Roll pass design is one of the important content of making the rolling technology of section steel.The traditional pass design relies mainly on artificial experience,which brings some tedious calculation and great consumption of raw materials.In order to improve production efficiency,the constitute and the design methods of the roll system for thread-steel-bar are analyzed during stretching,further rolling and finished rolling.The mathematical models and the(experience) formulas used for the roll design in the past are revised.The computer aided roll design system is developed for thread-steelbar based on the structural means of compiling program.The authors adopt Visual Basic6.0 as a visual program tool,and combine the basic design theory of the thread-steel-bar's roll and the practical experience.The system can shorten the design cycle of the new product development,and reduce the energy consumption of the rolling mill and the distribution of production.     

Optimization of Energy Dissipation Braces in Frame Structures

In this paper, the complex method of the nonlinear programming is used to optimize the parameters of energy dissipation bracing in energy dissipation braced frame. This method is realized with computer program and proved to be efficient. A 6-story reinforced concrete frame is used as a demonstrative example.