Dispersion of the mechanical parts performance indicators based on the concept of random vector

To solve the precision and reliability problem of various machinery equipments and military vehicles,some military organisations,the industrial sector and the academia at home and abroad begin to pay attention to the statistical distribution of machining dimensions,material properties and service loads,and the system reliability optimization design with constraints and reliability optimization design of various mechanical parts is studied in this way.However,the above researches focus on solving the strength and the life problem,and no studies have been done on the discrete degree and discrete pattern of other performance indicators.The concept of using a random vector to describe the mechanical parts performance indicators is presented;characteristics between the value of the vector variance matrix determinant and the sum of the diagonal covariance matrix in describing the performance indicators of vector dispersion are studied and compared.A clutch diaphragm spring is set as an example,the geometric dimension indicator is described with random vector,and the applicability of using variance matrix determinant and variance matrix trace of geometric dimension vector to describe discrete degree of random vector is studied by using Monte-Carlo simulation method and component discrete degree perturbation method.Also,the effects of different components of diaphragm spring geometric dimension vector on the value of covariance matrix determinant and the sum of covariance matrix diagonal of diaphragm spring performance indicators vector are analyzed.The present study shows that the impacts of the dispersion of diaphragm spring cone angle on every performance dispersion are all ranked first,and far exceed that of other dimension dispersion.So it must be strictly controlled in the production process.The result of the research work provides a reference for the design of diaphragm spring,and also it presents a proper method for researching the performance of other mechanical parts.     

基于CEEMDAN SVM的液压泵故障诊断方法研究

由于液压泵故障振动信号微弱和不平稳的特性,造成特征向量提取和故障诊断困难。针对这些问题,提出一种CEEMDAN与支持向量机结合的故障诊断方法。将传感器测得的液压泵故障振动信号进行CEEMDAN分解,得到多个固有模态函数（IMF）,并计算其样本熵作为支持向量机的输入特征向量,以诊断液压泵的故障类型。液压泵故障诊断实验结果证明了该方法的有效性和优越性。     

Misaligned journal effects in liquid hydrostatic non-recessed journal bearings

The performance characteristics of a capillary-compensated hole-entry hybrid misaligned journal bearing have been studied theoretically. The journal of the bearing is allowed to tilt on an axial plane containing the load vector and on a plane perpendicular to an axial plane containing the load vector. The journal misalignment has been accounted for by defining a pair of misalignment parameters σ and δ. The finite element method has been used to solve Reynold's equation governing the lubricant flow field in the clearance space of the journal bearing. Static and dynamic performance characteristics are presented for the different representative values of the journal misalignment parameters for both hydrostatic and hybrid modes of operation of the bearing. The bearing performance characteristics are also compared for the two hole-entry bearing configurations so as to facilitate the selection of a suitable bearing configuration by the designer. The study suggests that the journal misalignment significantly affects the performance of the hole-entry journal bearing, and for a more accurate prediction of the bearing performance it must be considered in the analysis.     

一种用于设计型专家系统的模糊知识表示与推理模型

根据设计领域模糊知识的特点，提出一种用模糊变量来表示模糊知识的新方法，每个模糊变量包括一系列模糊子集和一个模糊向量，这个模型向量用来描述这一系列模糊子集的隶属函数。在此基础上，提出一种模糊推理模型。该知识表示方法采用了统一的范式，并且具有很强的灵活性，通用性和易实现性，为设计型专家系统工具中模糊知识的处理提供了一种很好的途径。     

基于无速度传感器异步电机的风力机模拟研究

风力机模拟系统使在实验室内开展风力发电技术的各项研究成为可能。分析了风力机特性,建立了风力机模型。通过对异步电机间接磁场定向矢量控制技术的研究,考虑到安装速度传感器具有诸多缺陷,提出基于模型参考自适应（MRAS）转速辨识理论的无速度传感器异步电机的风力机模拟控制方法,并且考虑到转子时间常数对矢量控制系统的影响,采用同时辨识电机转速和转子时间常数,使系统辨识转速同时,对电机参数变化具有较强的鲁棒性。利用MATLAB/SIMULINK搭建了基于无速度传感器异步电机的风力机模拟系统,通过对风力机特性,最大风能捕获和电机参数对矢量控制系统影响的仿真,证明了系统的可行性。     

Vibration filter using vector channel periodic lattice

This paper considered identification of vibration characteristics of flexible structure with vector channel periodic lattice filter. We present an algorithm for AR coefficients for the vector-channel lattice filters, and characteristic equation and transfer function are derived from these coefficients. Vibration lattice filter is then constructed from the vector channel lattice filter, and performance of this vibration filter is tested with a test signal which is a combination of many sine waves to compare the performance of scalar and vector channel lattice. Also it is applied to the cantilever data to identify properties of the system, such as natural frequencies and damping ratios, to show its performance.     

A new parallel genetic algorithm for solving multiobjective scheduling problems subjected to special process constraint

This study presents a multiobjective scheduling model on parallel machines (MOSP). Compared with other scheduling problems on parallel machines, the MOSP is distinct for the following characteristics: (1) parallel machines are nonidentical, (2) the type of jobs processed on each machine can be restricted, and (3) the multiobjective scheduling problem includes minimizing the maximum completion time among all the machines (makespan) and minimizing the total earliness/tardiness penalty of all the jobs. To solve the MOSP, a new parallel genetic algorithm (PIGA) based on the vector group encoding method and the immune method is proposed. For PIGA, its three distinct characteristics are as follows: Firstly, individuals are represented by a vector group, which can effectively reflect the virtual scheduling policy. Secondly, an immune operator is adopted and studied in order to guarantee diversity of the population. Finally, a local search algorithm is applied to improve the quality of the population. Numerical results show that it is efficient, can better overcome drawbacks of the general genetic algorithm, and has better parallelism.     

基于分形与支持向量回归的动力装置运行状态预测模型

分析了动力装置运行状态特点和预测要求,依据分形和支持向量回归理论,建立了基于分形与支持向量回归的状态趋势预测模型。其中,以振动烈度作为描述机组状态的特征数据来构建时间序列,对其进行相空间重构,根据最小嵌入维数来确定支持向量机输入节点数,采用支持向量回归算法对机组状态趋势进行预测。应用案例研究和实验对比分析的结果表明,研究的状态预测模型单步预测的平均相对误差为1.7881%, 30步预测的平均相对误差为3.3983%,预测模型能较好地满足动力装置状态趋势预测要求。     

一种基于矢量传感器阵的盲波束形成方法研究

本文针对水声环境和信号的特点，提出了一种基于矢量传感器阵的盲波束形成算法。首先建立了矢量传感器阵列接收信号模型，然后推导了基于矢量传感器阵列的波束形成最优权矢量的表达式。在此基础上，定义了接收信号的四阶累积量，进而盲估计了矢量传感器阵列的方向向量，实现了盲波束形成。该方法利用高阶累积量可消除高斯噪声干扰这一特性，有效地实现了基于矢量传感器阵列的盲波束形成。仿真实验验证了该方法的有效性和正确性。     

A study of the electromagnetic fields that are generated by a coil emitter

Modern computer technology makes it possible to visualize different processes that take place in real time and to limit them to a specific plane using 3D-graphs. This paper describes the distribution of eddy currents and the configurations of the primary and secondary electromagnetic fields generated by a coil located above a half space. These curves make it possible to estimate the field intensity at any point of the center line. All curves are plotted for their vector potential, which is one of the main characteristics of an electromagnetic field. Knowing the value of the vector potential, it is possible to determine all the characteristics of an electromagnetic field, i.e., the intensity and induction of electric and magnetic fields and the density of eddy currents for an electrically conductive material. The developers of eddy-current equipment that is used for inspection purposes need to know these characteristics. In this case, it is possible to determine the optimal geometry of the transducer and select the frequency and amplitude of the field-coil current at the design stage. The aim of this paper is to show the possibility of the representation of electromagnetic fields on the basis of modern computer graphics.     

基于MATLAB/Simulink&SimPowerSystems的永磁同步电机(PMSM)矢量控制系统建模与仿真

介绍了永磁同步电机(PMSM)矢量控制系统的结构、矢量控制原理及空间矢量脉宽调制(SVPWM)算法,并在MATLAB环境下应用Simulink及SimPowerSystems工具箱对系统进行了建模与仿真,仿真结果表明:永磁同步电机矢量控制系统具有较好的动态响应特性和速度控制特性,可达到与直流电机近似的控制效果.     

IMF能量和RBF神经网络相结合在滚动轴承故障诊断中的应用研究

针对滚动轴承的故障特点,提出了一种将IMF能量与RBF神经网络相结合的方法用于故障诊断.该方法首先利用经验模态分解(EMD)方法,把振动信号分解为若干个IMF分量,再用重要的IMF分量求得IMF能量特征向量,最后将特征向量输入RBF神经网络进行故障模式分类.通过对滚动轴承的正常状态、内圈故障、滚动体故障和外圈故障信号的分析结果表明,该方法能够准确、有效地识别这些故障.     

基于有向图的刀轴矢量优化研究

针对球头铣刀的五轴数控加工,提出了一种基于有向图的刀轴矢量优化方法。根据刀轴矢量数据量大的特点,提出了建立刀轴矢量有向图的最小优化模型和算法。该方法能获得全局刀轴矢量变化量最小的刀轴矢量序列,将可行域边界上的刀轴矢量加入到有向图的计算中,提高了算法的计算效率。仿真分析表明,该方法优化了刀轴矢量的连续性和光顺性,对于最佳刀具姿态在可行域边界上的加工具有一定的适用性。     

基于PCA-SVM集成阀门故障诊断方法研究

提出了一种基于主元分析和支持向量多分类器的故障诊断方法.该方法首先对工业故障数据进行主元分析提取数据集特征并降低数据维数,再把故障特征数据通过支持向量多分类器进行模式分类,最后通过特征分类诊断故障.在DAMADICS阀门模型上进行了仿真,并利用Lublin Sugar Factory工业故障数据进行了验证.仿真结果表明该方法可以快速准确地检测与诊断故障.     

基于矢模糊函数的旋转机械故障诊断方法的研究

结合全矢谱技术与模糊函数,提出了一种矢模糊函数的新概念。定义的矢模糊函数继承了全矢谱技术与模糊函数各自的优点,既能全面地反应机械振动的全面性,又能很好地抑制Wigner分布中的交叉项干扰。阐述了矢模糊函数的定义、算法及其特点,并把矢模糊函数成功地应用到旋转机械故障诊断中。为了对比分析,还通过类似的方法定义了矢Wigner分布。仿真和实验结果表明,提出的矢模糊函数在旋转机械故障诊断中是非常有效的,矢模糊函数优于矢Wigner分布。     

基于焊点形态理论的SMT焊点质量模糊故障诊断技术研究

根据SMT焊点质量与焊点的三维几何形态直接相关的特点，提出了SMT焊点形态理论。以该理论为支持，提出了SMT焊点质量模糊诊断技术。将实际焊点几何形态与合理焊点几何形态对应比较，作为模糊输入向量，以焊点的故障缺陷发生可能度作为模糊输出向量。通过可信度约束的模糊规则与正反向模糊推理，进行焊点质量模糊故障诊断。以四边扁平封装器件(QFP)为例，进行了实例验证。     

基于Rayleigh-Sommerfeld积分的矢量衍射理论的适用范围

以径向偏振的Laguerre-Gaussian光束为例,探讨了基于Rayleigh-Sommerfeld积分的矢量衍射理论的适用范围。经与Richards-Wolf理论计算结果比较发现,在有效数值孔径小于0.4的情况下,Rayleigh-Sommerfeld理论可以适用,并可用于探讨小菲涅耳数的焦移问题。但对于紧聚焦大数值孔径系统,Rayleigh-Sommerfeld理论不再适用,因为这种理论低估了光波的衍射效应和矢量性,使得计算所得的聚焦光斑尺寸偏小。     

交变/旋转磁场下焊接缺陷磁光成像检测与分类

针对任意角度焊接缺陷难以检测的问题,研究在不同磁场激励下焊接缺陷磁光成像无损检测系统。重点介绍了由U形磁轭产生的交变磁场和平面交叉磁轭产生的旋转磁场激励焊件的机理,比较了交变/旋转磁场激励下不同焊接缺陷的磁光成像效果。基于法拉第旋转效应分析磁光成像特性与磁场强度之间的关系,磁光图像的灰度值可以匹配相应的漏磁场强度。采用主成分分析法提取融合图像列像素灰度特征和通过灰度共生矩阵提取磁光图像纹理特征,建立BP神经网络模型和支持向量机模型识别这些缺陷特征。试验结果表明,在旋转磁场激励下,BP神经网络模型和支持向量机模型的分类精度分别为94.1%和98.6%,相比交变磁场,分类精度分别提高了10.7%和8.5%。旋转磁场激励下的磁光成像克服了定向检测的局限性,能够实现对任意角度焊接缺陷的检测及分类。     

全永磁驱动带式输送机控制策略及动力学行为

针对传统异步电机驱动和液压绞车张紧带式输送机存在的传动效率低、运行维护困难、张紧响应慢等问题,设计了一种集永磁电机直驱与永磁张紧于一体的全永磁驱动带式输送机,制定了全永磁驱动系统矢量控制策略与机-电耦合动力学模型;利用Matlab/Simulink建模仿真与煤矿井下现场试验相结合的方法,研究了全永磁驱动带式输送机在空载启动、满载启动、变载运行等工况下的矢量控制策略与机-电耦合动力学行为。结果表明：全永磁驱动带式输送机在多种工况下均能实现转矩与转速的快速响应和动态调节,具有良好的动态特性;多台电机间可维持功率平衡与同步传动,具有较强的抗干扰能力;永磁张紧装置可以实现张紧力动态调节,有利于提高带式输送机驱动效率、张紧响应速度以及整机协调可控性;全永磁驱动系统可实现对带式输送机的智能驱动与动态张紧,在机-电耦合动力学行为仿真试验与现场试验中得到的电机动态特性规律基本一致,表明其可满足煤矿井下带式输送机实际工况需求,具有较高的推广应用价值。     

基于产品特征向量的产品配置研究

在制造行业中,为了提高产品配置对不同产品的适应能力,降低知识表达难度,提出了基于产品特征向量的产品配置方法。文章在产品特征可量化的条件下,建立了产品配置模型,给出了特征的向量表示方法,并根据产品特征向量,定义组件约束。在配置求解过程中,将用户对产品特征的需求转化为产品特征向量,给出配置求解算法。最后提供成功案例。