具有可控与不可控因素系统的可靠性维持方法

为了研究系统或元件可靠性维持方法,提出一种基于SFT的可靠性维持方法。在SFT框架下提出了可控与不可控因素的概念。目前SFT中的不可控因素指时间,其余为可控因素。给出了分析并制定系统或元件可靠性维持方法的步骤。分析表明在SFT内必须设定故障概率才能实施该方法。列举了一例进行分析,考虑的不可控因素为时间t,可控因素为温度c。分别将故障概率设置为10%、20%、30%、40%,50%,求出了元件更换周期,及其温度控制曲线和函数。与已有文献相比所得元件更换周期更为经济,方法更精确且可操作增强性。     

Model order reduction of second-order systems with nonlinear stiffness using Krylov subspace methods and their symmetric transfer functions

In this investigation, Model Order Reduction (MOR) of second-order systems having cubic nonlinearity in stiffness is developed for the first time using Krylov subspace methods and the associated symmetric transfer functions. In doing so, new second-order Krylov subspaces will be defined for MOR procedure which avoids the need to transform the second-order system to its state space form and thus the main characteristics of the second-order system such as symmetry and positive definiteness of mass and stiffness matrices will be preserved. To show the efficacy of the presented method, three examples will be considered as practical case studies. The first example is a nonlinear shear-beam building model subjected to a seismic disturbance. The second and third examples are nonlinear longitudinal vibration of a rod and vibration of a cantilever beam resting on a nonlinear elastic foundation, respectively. Simulation results in all cases show good accuracy of the vibrational response of the reduced order models when compared with the original ones while reducing the computational load.     

基于分块核主元分析的人脸识别方法研究

传统的基于数据二阶统计矩的主元分析法（PCA）是一种有效的数据特征提取方法,是基于原始特征的一种线性变换。但是,当原始数据中存在非线性属性时,用主元分析法后留下的显著成分就可能不再反映这种非线性属性。而核主元分析则是基于原始数据的高阶统计量,是一种非线性变换,在图像识别中它可以描述多个像素之间的相关性。而KPCA方法只考虑了人脸图像的整体信息,没有考虑到局部特征信息。文章提出了分块核主元分析（MKPCA）的方法进行人脸识别,取得了很好的效果。     

差分方程的不变子空间

研究了差分方程的不变子空间,讨论了多项式形式的子空间及三角函数型的子空间,并将这两类不变子空间运用到了拟线性演化方程和方程组。得到了以下结果：若已有的微分算子允许某一类不变子空间,则对应的差分方程也允许相应的不变子空间,且其系数满足一样的动力系统。     

Geometric Methods for Invariant‐Zero Cancellation in Linear Multivariable Systems with Application to Signal Rejection with Preview

This work deals with zero cancellation in linear multivariable systems with possible feedthrough terms from the inputs to the outputs. A methodology for the synthesis of a minimal‐order feedforward compensator preserving key properties of the original system while cancelling minimum‐phase invariant zeros is derived by means of the basic tools of the geometric approach. The properties maintained in the feedforward compensation scheme are stabilizability and right‐invertibility. Duality arguments show how to modify the devised method so as to achieve zero cancellation with a cascade filter retaining detectability and left‐invertibility. Continuous and discrete‐time systems are considered in a unified framework exploiting the common structural features. An original application of zero cancellation to signal rejection with preview is presented. A novel feedforward control scheme is devised, avoiding the steering along minimum‐phase zero techniques that are at the basis of well‐settled solutions.     

Single CNC machine scheduling with controllable processing times to minimize total weighted tardiness

Advanced manufacturing technologies, such as CNC machines, require significant investments, but also offer new capabilities to the manufacturers. One of the important capabilities of a CNC machine is the controllable processing times. By using this capability, the due date requirements of customers can be satisfied much more effectively. Processing times of the jobs on a CNC machine can be easily controlled via machining conditions such that they can be increased or decreased at the expense of tooling cost. Since scheduling decisions are very sensitive to the processing times, we solve the process planning and scheduling problems simultaneously. In this study, we consider the problem of scheduling a set of jobs on a single CNC machine to minimize the sum of total weighted tardiness, tooling and machining costs. We formulated the joint problem, which is NP-hard since the total weighted tardiness problem (with fixed processing times) is strongly NP-hard alone, as a nonlinear mixed integer program. We proposed a DP-based heuristic to solve the problem for a given sequence and designed a local search algorithm that uses it as a base heuristic.     

电气化铁路动态无功补偿(SVC)方案探讨及可控电抗器的应用

为了改善电力机车运行时对电网的冲击干扰,提高机车的运行效率和电网质量,通过对我国电气化铁路运行的功率因数和谐波状况进行分析,介绍了采用动态无功补偿(SVC)并结合谐波治理的两种初步方案。并提出了优先采用交流可控电抗器的建议。     

紫外固化胶黏剂的折射率及其影响因素

对用于光通信系统中的紫外光固化胶黏剂的折射率及其影响因素进行了综述,重点介绍了折射率的设计原则,详细说明了折射率的控制方法,最后对UV-胶折射率的研究提出了概述性的展望。     

基于向量空间不同访问群体的门限方案

针对具有不同访问权限的群体的秘密共享是难于处理的问题,在有限域上引入内积向量空间的概念,研究子空间的直和及其正交补结构中基向量的组成形式;利用Gram-Schmidt算法和最近向量定理设计了一个基于向量空间的（s+r, m+n）门限方案,并将此方案推广到有限多个不同访问群体的情形。结果表明,基于向量空间的不同访问群体的门限方案满足秘密共享的重构和安全性要求,是一个完备的秘密共享方案。