The Elastic-Plastic Analysis of Collinear JointsLoaded by Shearing-Compressive Stresses

In this paper the problem of collinear multi-joint in rockmass loaded by shearing-compressive stresses is simplified as that of a joint in finite rockmass. The basic equations with Mohr-Coulomb criterion are solved by the line field analysis method near the joint line in an elastic-perfectly plastic materials. Through a reasonable boundary condition on the joint surface and matching conditions at the elastic-plastic boundary, the relation between length of the plastic region on the joint line and the shearing-compressive stresses is obtained. The failure laws of the rockmass contained collinear joints are also obtained.     

风电齿轮箱传动误差分析及振动噪声预估

针对一级行星两级平行轴风电齿轮传动系统，综合考虑齿轮时变啮合刚度、啮合阻尼、传递误差等因素，建立31个自由度的弯扭轴耦合集中参数动力学模型，采用变步长Runge-Kutta法对系统动力学微分方程进行求解，得出齿轮传动系统各级传动误差；借助软件建立风电齿轮箱刚柔耦合动力学模型，并导入传动误差，采用模态叠加法求得齿轮箱轴承支反力，并将其作为声振耦合模型的边界条件，采用声学有限元法对风电齿轮箱进行振动噪声预估，并与试验结果对比分析，两者吻合良好。     

Lightning Shielding Simulation Model of Transmission Line

Transmission lines are easily hit by lightning, and lightning shielding failure is an important reason of lightning accidents of transmission line. So researches on lightning shielding of transmission line should be strengthened. On the basis of the abundant understand to known lightning shielding models of transmission line, a new lightning shielding simulation model of transmission line is presented in the paper. In this model, the effect of attracting lightning of upward leader is considered reasonably, and the method of variable descending step is adopted to simulate the descending process of lightning leader. The simulation calculating results show that the model is in good agreement with field experience of transmission line. It can guide lightning shielding design of transmission line and estimate the performance of lightning shielding of transmission line.     

An Unsteady Flow Analysis in Gas Transmission Pipeline Based on Theory of Functional Analysis

Branch -like pipeline is a common structure in gas transmission pipeline. In the light of the constituent properties of natural gas branch - like pipeline system, the system can be divided into fundamental constituent units. This paper presents a realistic unsteady flow model consisting of simple models of pipeline units and connecting conditions, boundary conditions and initial condition associated with units by using system analysis method. The solutions in wide sense are obtained by theory of functional analysis and operator series method, Such a method has the properties of both analytical solution and numerical solution methods. When the divided pipeline unit is larger, an intuitive approximate analytical solution may be obtained; while the one is smaller, a more accurate numerical solution may be acquired. Based on this, a general computer program has been developed for this model and solutions have been used successfully in a local natural gas transmission network in Sichuan. It is proved that the model and algorithm proposed in this paper are of the advantages of convenient calculation, high precision, time saving and wide application range by way of analysis and application.     

General Phasor Diagram and Power-angle Characteristic Equations of Extra High Voltage Long Distance Transmission Line

Installing compensation equipments is a good manner to improve line transmission capacity and maintain power system stability in the extra high voltage(EHV) long distance transmission line.It is of benefit to analysis and control by describing the effect of compensation equipment correctly.At present,for predigesting analysis or increasing real-time calculating speed,concentrated parameter circuit model is widely used to analyze 500 kV EHV long distance transmission line which may cause bigger error.So it is necessary to get a more reasonable model.On the basic of voltage and current distributed equations of even distributed long distance line,this paper deduces phasor diagram and power-angle character equations of uncompensated long line.Then the authors analyze the effect of compensators and define two characteristic parameters,namely,equivalent impedance x_(eq) and voltage coefficient K_V.Any compensating states of EHV long distance transmission line,example installing the compensators in the line or not or which type of compensators,is described by the general phasor diagram and power-angle characteristic equations.Furthermore,increment calculation(equations) of two characteristic parameters is presented by the compensator parameters which may make the concepts clear and predigests analysis easily.     

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.     

Model and Numerical Analysis of Radiation Field Created by Lightning Overvoltage Wave on Transmission Lines

The radiation field created by the transmission line stroked by lightning far from the lightning channel has been analyzed by the FDTD method.The authors we establish the calculation model and FDTD calculation method of transmission line,and discusses the import of lightning excitation source.The simulation of lightning stroked on a single transmission line in free space or stroked on three-phase high voltage transmission lines in actual environments has been done,and gives the distribution of transient radiation field around the transmission lines when lightning overvoltage wave transmits along the transmission line.The simulation result shows that: the effect of the transient radiation field caused by lightning over voltage wave done with environment is obvious,and the high frequency component of transient radiation field may disturb or do harm to the electronic facility or communication facility around the transmission lines.     

The on line monitoring method of power transmission line fault basednon linear frequency response function

A novel method for power transmission line monitoring and fault diagnosis is proposed based on non linear frequency response analysis. The power line carrier signal has been used for on line monitoring of power transmission line. As the non linear frequency response function describes the system inherent characterization, different frequency response patterns corresponding to different operation states of transmission line can be established. Based on the analysis of transmission line characteristics of fault modes, various fault features can be extracted, thereby achieve online monitoring and fault diagnosis on transmission line. Simulation experiments show the effectiveness of the proposed method.     

Method of Computing Sinusoidal Steady-state Solutions of Lossy Uniform Transmission Lines

There is no universal method of finding the analytic solutions to transmission lines discribed by partial differential equations,so many researchers are studying and developing transmission line theories.Computing steady-state solutions of uniform transmission lines is one part of the study.The paper introduces another method of computing sinsoidal steady-state solutions of lossy uniform transmission lines.First,the complex expressions of voltage and current with zero initial state are obtained from the complex frequency-domain model of lossy uniform tansmission lines.The network functions,which are the ratios of voltage and current's image functions to the excitation's image function,can be found from the complex expressions.Sinusoidal steady-state solutions can be obtained by using the relation between network function and system's frequency characteristic.Finally,the method is demonstrated to be effective by an example.     

Descending Dimension Algorithm for Convex Nonlinear Programming Problem with Equality Constraints

This paper deals with the nonlinear system of equations algorithm for convex nonlinear programming problems with equality constraints.We use the optimatily conditions for programming problem with equality constraints and then estabish a nonlinear system of equations.Finally we solve these to get optimal solution of nonlinear programming problems.     

Computerized Simulation of the Transmission Line in High-speed PCB

With the rapid development in logic circuit,the effect of transmission line in PCB becomes a confined factor.In the design of high-speed PCB,the factors which affect the integrity of signal can be found by computerized simulation of the transmission line,simultaneously the signal quality could be optimized.The capacitance matrices of transmission line in high-speed PCB have been computed with this method that is the total charge Green's functions with method of matrix,then the time-domain model is built.Connected to IBIS model of the I/O buffer these models can be used in computerized simulation of the transmission line.The result of simulation is equal with the result produced by EDA software-Specctraquest of cadence Co.and the efficiency of simulation is advanced.     

Elastoplastic Analysis of Discrete Jointin Rockmass Loaded by Compress_shear

In this paper the elastoplastic stress fields near joint line in rockmass loaded by compress- shear are analyesd by the line field method in fracture mechanics with Mokr- Coulomb criterion. Through the matching conditions of the elastoplastic fields on their boundary, the relations between the length of plastic zone on the joint line and the compress- shear loads are found, and the fracture criterion of the discrete joint is also obtained     

Tooth contact analysis of helical beveloid gear with parallel axis

The study object of this paper is helical beveloid gears with parallel axis. Based on the gear Mshing Principles and the tooth-surface equations of pinion and gear,the mathematical model of tooth contact is developed under standard installation and installations with center distance error,axis error and multiple error respectively. The MATLAB solver is used to obtain the contact trace and the transmission error under different installing conditions and the comparative analysis is made. The results indicate that this gear drive is sensitive to axis installation errors,it forms the edge contact and cause the periodic transmission error. It can provide the foundation for designs and analysis of this gear transmission.     

基于Adaboost算法的输电线路舞动预警方法

输电线路舞动是目前尚未被全面准确认识的世界性难题,已严重威胁输电系统的安全稳定运行。文章分析影响舞动的外界气象环境因素,并在此基础上提出一种基于Adaboost集成学习算法的输电线舞动预警方法。采用基于Gini指标的决策桩作为弱分类器,通过对多个弱分类器的训练及加权求和,输出舞动预测结果及其置信度,可为电网运维人员提供决策支撑。最后,使用历史数据进行验证性实验,结果证明了所提方法的有效性。     

Lightning Protection Performance of Transmission Line with High Tower and Great Span

This paper studies lightning protection performance of transmission line with high tower and great span, and puts forward the lightning shielding model of transmission line with high tower and great span. The model simulates the developing process of lightning downward leader, and take the effect of upward leader to downward leader into account. Moreover, the model consider backward lightning , that is even downward leader have developed lower than transmission line, Which will be occur lightning line. Aim at a certain sea transmission line with great span, its lightning performance is calculated with regular method, EGM and the model. The results have been analysed and compared. Because of thinking over backward lightning , the model can be used for calculating lightning shield performance of all kinds of transmission lines.     

The BEM for Elliptic Unilateral Problems

Unilateral problems is a kind of important partial differential problems. It can be solved by treating it as a complementary problem. As the complementary conditions lie in the boundary of the region,it is suitable for BEM. This paper is based on the switching algorithm,which is first used by J. M. Aitchison for the Signorini Problems of Laplace operator,then extends it to the elliptic operator,and conjunct it with the BEM. At last the detail of the algorithm is given. The new algorithm is easy to be implied effectively and quickly. It only needs the minimal change of the BEM programming. The numerical tests show the algorithm is effective and conventional.     

Synchronization of Chaotic Systems Employing the Theory of Application of Linear Time-varying Impulsive Differential Equations

Employing the stability theory of linear non-autonomous impulsive differential equations, some sufficient conditions for the synchronization of unified chaotic systems and Lorenz chaotic systems are derived. This method can be applied to most of chaotic systems. The numerical simulations also demonstrate the efficiency of impulsive control.     

Boundary Element Methods with Overlapping Domain Decomposition for Parabolic Problem

Boundary element method is a numerical method for solving partial differential equations. There are several formulations of boundary element method (BEM) applied to solve a parabolic differential equation.The approach,which employs time- dependent fundamental solution,allows longer time steps in time integration than other approaches,and this can cut down on time for computer implementation with high precision.Domain decomposition method,which decompose the domain that a given problem is to be solved into subdomains,has the advantages of reducing the large problem into smaller ones and reducing the complex problem into simpler ones,and allows parallel computing.An overlapping domain decomposition method is applied combining a boundary element formulation with time-dependent fundamental solution to solve a diffusion equation. Firstly, by domain decomposition, the problem divided into two problems on subdomains, and then the initial-Boundary problems are solved by boundry element method on each subdomain.Some numerical examples are presented to illustrate feasibility and efficiency of the method. The numerical experiments show that the convergence rate of the method is dependent with the overlapping degree of the subdomains.     

THE CALCULATION OF INTERNAL FORCES AND DISPLACEMENTS IN FRAME-SHEARING WALL STRUCTURE UNDER THE HORIZONTAL LOADS

In general,the calculating result of a comparatively regular frame-shearing wall system in tall buildings,a 4-order differential equations are established according to the deformation-coordination of beams,columns and four boundary conditions.Then a series of formulas concerning internal forces and displacement is obtained These formulas are hyperbolic functions.This paper presents a method,which changes 4-order differential equations into 2-order and solves them by the expressions of new homogeneous solutionThen the formulas of internal forces and displacements become exponential functions By this method,the calculation is very convenient The result of suggested method agrees well with the general by comparison This paper is also applicable to buildings with some part of different height of storey or stiffness.     

Analysis on the Lightning Protection Performance of 500 kV Double-circuit Transmission Line

Using double-circuit transmission line is the developing tide for main 500 kV configuration to reduce line holding ground, so analyzing it's lightning protection performance is important to extend double-circuit transmission line in ultra high voltage network. The lightning protection performance of 500 kV double-circuit transmission line is studied with EMTP and EGM. The statistical method is applied to analyzing the lightning protection performance of back stroke by considering the randomness of working voltage's phase when lightning stroked the top tower. The result is that the line lightning protection level is different when the working voltage of conductor is different. It also improved the EGM by considering the effect of wind speed when analyzing the lightning protection performance of shielding failure. Furthermore, the results are given that wind speed has effects on the protection angle and the rate of shielding failure by using the program to calculate it.