Fast multi-pole preconditioned GMRES high order boundary element method for power frequency electric field of multi-medium

In order to improve the computational accuracy and cost for multi-medium power frequency electric field (PFEF) solved by low order boundary element method (BEM) and preconditioned generalized minimal residual (GMRES),a hybrid technique combining the high order BEM and fast multi-pole (FM) method has been introduced to low order BEM. The FM preconditioned GMRES high order BEM is proposed to solve three dimension electric field distribution. The high order BEM model for three dimension electric field distribution is built, and the basic principles and implementation steps of the FM preconditioned GMRES high order BEM are given. The higher accuracy has verified in two medium test models. Part key devices in 500 kV substation is carried out to demonstrate that FM preconditioned GMRES high order BEM is much faster and more efficient than the preconditioned GMRES BEM in the computational cost and the storage of computer. The simulation values of this method are compared with measured values in 500 kV substation. It is found that the max relative error is 8.65%, so this method is suggested for use in large-scale and multi-medium PFEF problems.     

Accelerated Generalized Minimal Residual Algorithm

This paper studies the fundamental theory of the generalized minimal residual algorithm(GMRES(m))in Krylov subspace and specially the relationship between residual vector and Krylov subspace.The relationship of the algorithm convergence and the subspace be selected is further researched according the linear system about residual vector.It is posed that the convergence can be slowed down because there are so many very small eigenvalue in magnitude.And a accelerated method(AGMRES(m)) is proposed to improve the convergence of the GMRES(m).Theoretical analysis and numerical results show the reliability and efficiency of the algorithm.     

A Method to Improve the Decoding Iteration Convergence Performance of Turbo Codes

Turbo codes is an effective method for digital communication systems to get near channel capacity error correcting performance, its iteration convergence performance is the key factor for practicability. Based on the universal decoding method of Turbo codes, a step increment factor was introduced in the paper to improve the iteration convergence performance. The method to generate the step increment factor was also presented as well as its' computer simulations. Simulation results show the method proposed can improve the convergence performance efficiency for Turbo codes with short interleaver.     

Boundary Element Method for Time-dependent Chloride Diffusion and the Chloride Distribution in Concrete

The process of chloride diffusion in concrete is time-dependent.The boundary element method (BEM) with a time-dependent diffusion coefficient is presented for chloride diffusion in concrete based on the suitable transformation of variables.The fundamental solution of the partial differential equation for time-dependent chloride diffusion in concrete is developed,and the compensation length of the diffusion field is defined as well as the compensation coefficient.The scheme of BEM with a time-dependent diffusion coefficient is developed.Two examples are given to demonstrate the accuracy and efficiency of the presented method and the rationality and the importance of the compensation length for the method.     

Simulation of the constant modulus blind equilibrium algorithm with variable step size based on the mean square error

The mathematic models and basic theory of constant modulus algorithm (CMA) for blind channel equalization are introduced. An improved algorithm with variable step size is proposed based on CMA. The improved algorithm uses the mean square error (MSE) to obtain the new variable step size to solve the contradiction between the convergence rate and accuracy in traditional CMA with fixed step. To smooth the MSE learning curve for easy comparison, an ensemble average technique is used to analyze the performance of convergence with different step sizes. The theoretical analysis and the simulation results show that the improved algorithm is superior to the traditional constant modulus(CM) in terms of convergence speed and residual error.     

Research on Load Prediction Model of Air Condition System Based on Elman Neural Network

The load of air condition system is influenced by many factors, and they are variable and nonlinear, The relation between them is dynamic,It is impossible to forecaste the load of air condition syestem accurately by traditional method. But Recurrent Neural Network is able to reflect the dynamic lively and directly. Elman is one of the typical RNN. Based on the analysis as above, prediction model of air-condition system based on Elman neural network is established, and some prediction is done. The prediction accuracy of Elman neural network and BP neural network is compared, and the experiments show that the Elman neural network is efficiency and accuracy , so Elman neural network is a new and reliable method for predicting the load of air-condition system.     

Pile Foundation Analysis Using a Boundary Element Method

Taking the extended Mindlin solution of a vertical point load acting in the interior of a multi layered elastic medium as the basic solution, an indirect boundary element method (BEM) was adopted to analyze pile foundations embedded in a multi layered elastic soil. The numerical analysis was carried out by the compiled program for a pile foundation in an homogeneous soil and a pile foundation in a multi layered soil. Reasonably good agreement is obtained between the present and existing solutions. Compared with the FEM software ABAQUS, the computational speed of BEM is much faster than that of FEM. Applying BEM in practice is convenient. It is pointed out that the exact measurement of elastic modulus is the key factor for applying BEM in geotechnical engineering.     

Application of improved genetic algorithm to locating and sizing of distributed generation

A Prüfer-coded genetic algorithm based on the decimal number of nodes is proposed and it is used to solve collaborative optimization planning of access solution of distributed generation(DG)and structure of distribution network.Using graph theory to generate theoretically feasible topology structureand the access nodes and the installed capacity of distributed generation are coded by the Prüfer number.The coding method makes the distribution network operation structure and the access solution of DG combine into the evolution problem of the same chromosomal gene.The length of the chromosome coding of this method is shorter than binary encoding.This solution takes full advantage of the Prüfer-coded to improve computational efficiency and convergence rateand makes some restrictions and improvements in some key parts of the algorithm to solve the problem illegal solution.Finallyfeasibility and superiority of the algorithm is validated by a case study.     

Analysis of fast optimization algorithm for inverse detecting faulty insulators

In order to improve the computational efficiency of the insulator electric field inverse problem, the fast multi-pole method has been introduced to the traditional simulation charge method. Tikhonov regularization is used to process the ill-posed characteristic of inverse problem solution caused by the interference. Newton method is used to search the optimum solution, and then the actual field source parameters of insulators and the practical voltage distribution on the surface of the insulators can be obtained. The fast optimization algorithm has been verified in point charge model. And 110 kV insulator string is carried out to demonstrate that the fast optimization algorithm is much faster and more efficient than traditional method.     

Application of Symmetric Galerkin Boundary Element Method in Limit Analysis of Plane Problems

Based on Melan's theorem, the symmetric Galerkin boundary element method (SGBEM) is used to discretize two dimensional structures and a computational formulation of structural limit analysis is established. The self equilibrium stress field is constructed by linear combination of several basic vectors, which are the stress differences between different iteration steps at the same increment using the traditional elastoplastic incremental method. Then the complex method is used to solve the nonlinear programming directly, so that the lower bound load multiplier of two dimensional structures is obtained. The validation of the present method has been confirmed by some numerical examples.     

Comparison of Constant and Linear BEM Analysis for Small Viscous Fluid Sloshing

Linear boundary element method is used for the analysis of viscous fluid. The velocity components and the fluid mean pressure are taken as unknown functions. The comparison of linear BEM with constant BEM shows that the former presents much better precision and better convergence.     

Feed-rate-controlled method of iterative algorithm for curve interpolation

In order to maintain a high machining accuracy and a constant speed feed-rate in CNC machining and improve the machining capability of CNC in handing complex part,the complicated interpolation algorithm needs to be used in CNC interpolation,which is time-consuming for large amount of computation,thus the machining speed is influenced. To solve this problem,based on the principle of parametric curve paths CNC interpolating,it is pointed out that Taylor series and iterative algorithm,given curve,using the chord length and the interpolation point,accurately calculate the next interpolation points. In the number of iterations and iterative error are less than the set value when the end of the iteration,next interpolation points can be calculated,and keep the current point and speed,otherwise continue iterative algorithm until they meet the requirements,feed-rate-controlled method based on iterative algorithm for curve real-time interpolation has also been given. The simulation results demonstrate that the proposed algorithm can satisfy the machining of a variety of different parametric curves. Compared with the conventional interpolation algorithm,it features are high university for machining,small computational a mount small feed-rate error and high computational accuracy,thereby greatly shorting the processing efficiency.     

Service Life Prediction of Concrete Structures under Chloride Environment

The problems rendered from the conventional time marching, referring to stepwise time marching scheme (STMS) adopted in boundary element method (BEM) for chloride diffusion in concrete structures, were investigated, and a new time marching, referring to initial time marching scheme (ITMS) in BEM, was developed for evaluation of service life of the concrete structures under chloride environment. Results of the numerical examples show that the ITMS-BEM proposed can eliminate domain integral and simplify the computational model, so that the stability in iteration process can be improved, resulting in better efficiency and accuracy, compared with the STMS-BEM. It can also be concluded that the dimensions of the diffusion of chloride can affect the service life of the concrete structure significantly, which should be taken into account in structural design.     

ANALYSIS OF THE TIME HISTORY RESPONSE FOR LARGE STRUCTURE UNDER THE ACTION OF IMPULSIVE LOADING USING STEP-BY-STEP REDUCED DYNAMIC-STIFFNESS COMPOSITION METHOD

In this paper, a dynamic substructure method for analysing the transient response of the large structure is proposed. The method is based or, the combination of the reduced dynamic-stiffness composition method and the step-by-stop integration method. Its main feature is that the computational effort may be reduced significantly. Several examples are given to prove its reliability, effectiveness and accuracy.     

Traditional mineral resource visualized dynamic estimation and its application in 3D geological space

A new method for traditional mineral resource visualized dynamic estimation in 3D geological space is proposed, which is adaptive to the characteristics of resource exploitation and reserve classification in China. The method follows the daily workflow of mine exploitation, improves the traditional method for resource estimation by 3D visualization technologies, and replaces abstract regular geometries with real 3D geological models. Thus, the traditional method for resource estimation realizes visualization in the whole workflow of mine exploitation. The application results to some real mines show the estimation results are mainly affected by the spatial location, shape and thickness of mineral blocks and goaf. If the resource dynamic estimation is carried out by constructing 3D mineral models in consistent with real exploitation project, the accuracy of the traditional method can be effectively improved.     

Computation method of magnetic field inverse problem on grounding grids fault diagnosis

Grounding grids are the guarantee of substation running safety. The fault of grounding grids is a threat to people and equipment in substations. A method to diagnose the fault of grounding grids based on magnetic field inverse problem. The inverse problem of magnetic field is established by injecting and extracting a low frequency current. The morbid of inverse problem is solved through regularization and Newton iteration method to obtain the distribution of the mesh currents. The approximate distribution of the magnetic field is calculated to diagnose the fault of the grounding grid. A 4×4 substation grounding grids is taken as an example. By comparison of the forward problem result, the error is under 3%, so the prposed method of inverse problem is verified. The selection of measurement point is discussed, and 40% of the number of meshes is accounted to approximate the real distribution of the magnetic field on the grounding grids.     

A Direct Limiting Deformation Equilibrium Method for Wedge Sliding

A simple and direct limiting deformation equilibrium method for wedge sliding considering all the three deformation components of the discontinuity planes is presented. The traditional limiting equilibrium method is based on a statistic system assuming that sliding is resisted only by the sliding resistance parallel to the sliding direction along the line of intersection of the two discontinuity planes. Therefore, we work out the psudo-elastic system to take care of the deformation of the discontinuities and to solve the indeterminate system. Through analysis and experiment, it is illustrated that the result based on traditional method is unsafe. The calculated results are fairly consistent with the experimental ones, while those based on the traditional method are unsafe. The stiffness of the discontinuities should be emphasized.     

Rosenbrock-based coupled time integration method and its convergence analysis

Real-time substructring testing is under rapid development. is a hybrid computational-experimental technique, and its challenge is to ensure that the numerical substructure and the experimental substructure interact in real time, which requires efficient numerical integration methods. With this mind, based on the Rosenbrock real-time integrator, a coupled time integration method is proposed which enables completely parallel computation. By virtue of a Single-DoF split-mass test problem, stability and accuracy analyses are performed theoretically for the coupled method. Moreover, numerical simulations on a Three-DoF split-mass system are conducted to further investigate the convergence and other properties of the coupled method. The theoretical analysis and the numerical simulations reveal that the method exhibits favourable stability and second order accuracy. Compared with direct time integration methods, the proposed method is more suitable for Real-Time Substructuring Tests of complicated structures and relevant hybrid simulations.     

Galerkin Boundary Element Method for Direct Boundary Integral Eqution for Dirichlet Problem of 2-D Laplace Eqation

The direct boundary integral equation of two-dimensional Laplace equation for Dirichlet problem is(con-sidered).It is deduced by Green's formula and the fundamental solution.The most-used numerical method for solving(direct) boundary integral equation is collocation method,and seldom have been used the Galerkin scheme in this case.The direct boundary integral eqution is changed into the variational eqution.Using linear element,it is solved by Galerkin boundary method.In the variational eqution double integrations shall be carried out.The paper presents the analytical formula to calculate the inner integration and the Gaussian quadrature is used for the outer integration. The numerical experimentation proved thefaesibility and the efficiency.     

Asynchronous Parallel Algorithm for Finding All Zeros of a Polynomial

Parallel Halley iteration method, based on circular arithmetic for finding all zeros of a polynomial, avoids troublesome circular extraction operation,and the approximation with error estimation of all zeros of a polynomial can be obtained at the same time with it, and it has higher convergence rate , while it was synchronous parallel algorithm. The asynchronous parallel algorithm was constructed with circular arithmetic in order to find all zeros of a polynomial, and the convergence theory was established under the similar condition of Halley iteration method. The algorithm not only retain the advantage of Halley iteration method, but has better parallelism.