基于复线性最小二乘法的谐波责任定量划分

定量划分各主要谐波源在特定母线上的谐波责任是电能质量管理的一项重要任务。该文提出一种基于复线性最小二乘原理的等效谐波阻抗和背景谐波电压计算方法,由此可定量划分谐波源对关注母线谐波责任。不同于传统的将复数实部和虚部分开计算方法,复线性最小二乘法通过直接在复数域内求解误差模的平方和最小值,得到了真实的最小二乘解。在此基础上,利用基于内积理论推导谐波责任定量划分的计算公式,量化了谐波源对关注母线的谐波责任。对IEEE14节点系统进行仿真计算,并与现有方法相比,证明了所提方法计算更简单,结果更准确,易于在工程中实现。

基于谐波功率分解的奖惩性电能计量方法

为了合理地计量谐波电能,提出了一种基于谐波功率分解的奖惩性电能计量方法。根据谐波电压、电流采样数据采用复线性最小二乘法估算谐波等值电路参数,然后通过谐波功率分解求解系统谐波功率和用户谐波功率,基于奖惩性计量模型即可得到奖惩性谐波功率。该方法考虑了公共连接点处谐波功率的分解,能够更合理地计量典型工况下的谐波功率。最后以IEEE14节点系统为例进行仿真分析,结果验证了所提方法的合理性和实用性。

基于改进复线性回归的谐波发射水平评估方法

为了表征电力系统谐波源的谐波贡献,提出了一种基于改进复线性回归的谐波发射水平评估方法。在系统公共耦合点(PCC)测量电压与电流,经过傅立叶分析,采用改进复线性最小二乘法估算系统谐波阻抗,并以此评估PCC两侧的谐波发射水平。仿真分析验证了该方法的有效性与改进效果。与普通复线性回归法以绝对残差的平方和最小为优化目标的不同之处是,改进方法以相对残差为基准,对测量样本进行优化,并构造新的优化目标,可有效去除最小二乘法自带的加权效应,减小异常值的影响,适合工程应用。

RSA算法在数字签名中的应用

从公开密钥加密工作中获得的最重要的进展是数字签名,数字签名提供了任何其它方式难以实现的安全能力,本文主要介绍RSA算法如何应用于数字签名。

浅谈数学中的美

数学本身具有许多美的特性,它们是形象、生动而具体的,数学中的符号美、统一美、和谐美和奇异美均展现着数学自身的美。

OTA MACROMODEL AND QUARTER-SQUARE MULTIPLIER

This paper presents a new kind of macromodel of OTA,which can be used to solve the problem in which the two port macromodel couldnt reflect some functions of the OTA.The new model also opens up a new way for the simulation of the OTA circuit.This paper discusses the way of designing this model and simulating it in SPICE.The result proves its reasonable design and its simplicity in structure.In the application of this model,we design a complete symmetric double differential quarter square OTA multiplying unit by using four three port OTA macromodels.It successfully solved the problem of the unsymmetry of two input ports in an OTA multiplying unit.This result fully agrees with the experiment.

WEIGHTED LEAST SQUARE METHOD FOR S-N CURVE FITTING

An S-N curve fitting approach is proposed based on the weighted least square method, and the weights are inversely proportional to the length of mean confidence intervals of experimental data sets. The assumption coincides with the physical characteristics of the fatigue life scatter. Two examples demonstrate the method. It is shown that the method has better accuracy and reasonableness compared with the usual least square method.

Application of nonlinear partial least square in catalyst modeling

The neural network partial least square (NNPLS) method was used to establish a robust reaction model for a multi-component catalyst of methane oxidative coupling. The details, including the learning algorithm, the number of hidden units of the inner network, activation function, initialization of the network weights and the principal components, are discussed. The results show that the structural organizations of inner neural network are 1-10-5-1, 1-8-4-1, 1-8-5-1, 1-7-4-1, 1-8-4-1, 1-8-6-1, respectively. The Levenberg-Marquardt method was used in the learning algorithm, and the central sigmoidal function is the activation function. Calculation results show that four principal components are convenient in the use of the multi-component catalyst modeling of methane oxidative coupling. Therefore a robust reaction model expressed by NNPLS succeeds in correlating the relations between elements in catalyst and catalytic reaction results. Compared with the direct network modeling, NNPLS model can be adjusted by experimental data and the calculation of the model is simpler and faster than that of the direct network model.

Parallel Computation of Disjoint Products Approach

In this paper, extracting parallelizatio n from the sum of disjoint products approach is discussed. A general framework of parallelizing disjoint products approach is presented. And a parallel version of the newest disjoint products algorithm is implemented. The results of testing s how the effect is so good to get linear speedups.

Mixed-Weights Least-Squares Stable Predictive Control Algorithm with Soft and Hard Constraints

Mixed-weight least-squares (MWLS) predictive control algorithm, compared with quadratic programming (QP) method, has the advantages of reducing the computer burden, quick calculation speed and dealing with the case in which the optimization is infeasible. But it can only deal with soft constraints. In order to deal with hard constraints and guarantee feasibility, an improved algorithm is proposed by recalculating the setpoint according to the hard constraints before calculating the manipulated variable and MWLS algorithm is used to satisfy the requirement of soft constraints for the system with the input constraints and output constraints. The algorithm can not only guarantee stability of the system and zero steady state error, but also satisfy the hard constraints of input and output variables. The simulation results show the improved algorithm is feasible and effective.

居民用电中的谐波电能分配方法

为合理分配居民用电中的谐波电能,提出了一种适用于居民用户的谐波电能分配方法。在居民用户群的公共节点采集谐波电压、电流数据,通过复线性最小二乘法估算谐波等值电路,将谐波功率进行分解,基于修正系数后的奖惩计量模型得到居民用户群谐波功率,并按照居民用户的用电占比分配各户的谐波电能。最后仿真分析了该方法的谐波电能分配效果,验证了所提方法的合理性和有效性。

Adaptive Controller for Vehicle Active Suspension Generated Through LMS Filter Algorithms

The least means squares （LMS） adaptive filter algorithm was used in active suspension system. By adjusting the weight of adaptive filter, the minimum quadratic performance index was obtained. For two-degree-of-freedom vehicle suspension model, LMS adaptive controller was designed. The acceleration of the sprung mass,the dynamic tyre load between wheels and road,and the dynamic deflection between sprung mass and unsprung mass were determined as the evaluation targets of suspension performance. For LMS adaptive control suspension, compared with passive suspension, acceleration power spectral density of sprung mass acceleration under the road input model decreased 8-10 times in high frequency resonance band or low frequency resonance band. The simulation results show that LMS adaptive control is simple and remarkably effective. It further proves that the active control suspension system can improve both the riding comfort and handling safety in various operation conditions, and the method is fit for the active control of the suspension system.

Frictional contact algorithm study on the numerical simulation of large deformations in deep soft rock tunnels

There exist three types of nonlinear problems in large deformation processes of deep softrock engineering, i.e., nonlin- earity caused by material, geometrical and contact boundary. In this paper, the numerical method to tackle the nonlinear eontact and large deformation problem in A Software on Large Deformation Analysis for Soft Rock Engineering at Great Depth was presented. In the software, based on Lagrange multiplier method and Coulomb friction law, kinematic constraints on contact boundaries were introduced in functional function, and the finite element equations was established for two incremental large deformation analyses models, polar decomposition model and additive decomposition model. For every incremental loading step, by searching for the contact points in the potential contact interfaces （the excavation boundaries）, the Lagrange multipliers, i.e., contact forces are cal- culated iteratively by Gauss-Seidel method, and justified through satisfy the inequalities of static constraint on contact boundaries. With the software, large deformation and frictional contact of a transport roadway were analyzed numerically by the two models. The numerical examples demonstrated the efficiency of the method used in the software.

The Sequential Continuity of Multiplication on a Class of Infinite Matrix Algebras

Let λ and μ are sequence spaces and have both the signed_weak gliding hump property, (λ,μ) be the algebra of the infinite matrix operators which transform λ into μ, in this paper, we study the strong? Mackey? weak multiplier sequentially continuous problem of infinite matrix algebras (λ,μ).

Genetic algorithm-based evaluation of spatial straightness error

A genetic algorithm(GA)-based approach is proposed to evaluate the straightness error of spatial lines. According to the mathematical definition of spatial straightness, a verification model is established for straightness error, and the fitness function of GA is then given and the implementation techniques of the proposed algorithm is discussed in detail. The implementation techniques include real number encoding,adaptive variable range choosing, roulette wheel and elitist combination selection strategies,heuristic crossover and single point mutation schemes etc.An applicatin example is quoted to validate the proposed algorithm. The computation result shows that the GA-based approach is a superior nonlinear parallel optimization method. The performance of the evolution population can be improved through genetic operations such as reproduction,crossover and mutation until the optimum goal of the minimum zone solution is obtained. The quality of the solution is better and the efficiency of computation is higher than other methods.

A study of particles penetration in sieving process on a linear vibration screen

This paper presented an investigation of particle collision and penetration using the discrete element method to understand the motion of particles and improve theoretical treatment in the sieving process. The process progressively was divided into looseness, stratification, collision, and penetration. Particle penetration has a direct effect on the screening performance. The penetration probability was defined, and the mathematical relationships between particle penetration and vibration parameters were established using the least squares method. To obtain the ideal penetration probability for materials the amplitude and frequency should preferably be near 3.0 mm and 25 Hz, respectively. The vibration direction angle has only a slight effect on penetration. The stage of the screening process from 0.1 to 0.7 s is the primary region for collision and penetration. This paper focused on the sieving process to more fully understand how particle collision and penetration influence the screening efficiency.

FPGA IMPLEMENTATION OF RSA PUBLIC-KEY CRYPTOGRAPHIC COPROCESSOR BASED ON SYSTOLIC LINEAR ARRAY ARCHITECTURE

In order to make the typical Montgomery’s algorithm suitable for implementation on FPGA, a modified version is proposed and then a high-performance systolic linear array architecture is designed for RSA cryptosystem on the basis of the optimized algorithm. The proposed systolic array architecture has dis- tinctive features, i.e. not only the computation speed is significantly fast but also the hardware overhead is drastically decreased. As a major practical result, the paper shows that it is possible to implement public-key cryptosystem at secure bit lengths on a single commercially available FPGA.

Boundedness of Multiplication Operators on α-Bloch Spaces

In this note we study and give a full characterization of the boundeness of mul-tiplication operators on α-Bloch spaces.

Conservation Law Classification and Integrability of Generalized Nonlinear Second-Order Equation

This paper is concerned with the generalized nonlinear second-order equation.By the direct construction method,all of the first-order multipliers of the equation are obtained,and the corresponding complete conservation laws(CLs) of such equations are provided.Furthermore,the integrability of the equation is considered in terms of the conservation laws.In addition,the relationship of multipliers and symmetries of the equations is investigated.