Stochastic optimization model for order acceptance with multiple demand classes and uncertain demand/supply

This article considers an order acceptance problem in a make-to-stock manufacturing system with multiple demand classes in a finite time horizon. Demands in different periods are random variables and are independent of one another, and replenishments of inventory deviate from the scheduled quantities. The objective of this work is to maximize the expected net profit over the planning horizon by deciding the fraction of the demand that is going to be fulfilled. This article presents a stochastic order acceptance optimization model and analyses the existence of the optimal promising policies. An example of a discrete problem is used to illustrate the policies by applying the dynamic programming method. In order to solve the continuous problems, a heuristic algorithm based on stochastic approximation (HASA) is developed. Finally, the computational results of a case example illustrate the effectiveness and efficiency of the HASA approach, and make the application of the proposed model readily acceptable.     

环境激励下基于信号降噪的模态参数识别研究

提出一种环境激励下基于测试信号降噪的模态参数识别方法。该方法首先对测试的随机响应数据采用自然激励技术(NEx T)获得互相关函数,进而基于结构矩阵低秩逼近(SLRA)方法得到降噪后的信号,最后通过复指数(Prony)方法识别结构的模态参数。数值算例和模型实验结果表明,该方法对测量信号有很好的降噪作用,识别精度高。     

圆弧型柔性球铰柔度设计计算

 通过研究圆弧型柔性球铰的柔度性能,使该柔性球铰可代替传统的双轴柔性铰链应用于空间多自由度柔顺机构.根据《材料力学》中的卡氏第二定理,圆弧型柔性球铰柔度的解析公式被推导出,然后利用ANSYS12.0软件对其进行有限元分析, 结果表明有限元分析与解析式的计算结果基本一致.通过改变圆弧型柔性球铰的各结构参数来分析其性能,得出各结构参数对其柔度的影响大小依次为：最小截面直径 t、圆弧的圆心角θ^_m、圆弧半径R、杨氏模量E. 此设计计算和特性分析为柔性球铰在柔顺机构的应用提供了依据.     

On generalized logistic equations with a non-homogeneous differential operator

We consider a generalized logistic equation of superdiffusive type, driven by a non-homogeneous nonlinear differential operator, which incorporates the p-Laplacian, the (p, q)-differential operator and the generalized p-mean curvature differential operator. Using variational methods coupled with truncation and comparison techniques, we prove a bifurcation-type theorem describing the dependence of positive solutions on the parameter λ > 0.     

Conservative Approximation–Based Full‐Search Block Matching Algorithm Architecture for QCIF Digital Video Employing Systolic Array Architecture

This paper presents a power‐efficient hardware realization for a motion estimation technique that is based on the full‐search block matching algorithm (FSBMA). The considered input is the quarter common intermediate format of digital video. The mean of absolute difference (MAD) is the distortion criteria employed for the block matching process. The conventional architecture considered for the hardware realization of FSBMA is that of the shift register–based 2‐D systolic array. For this architecture, a conservative approximation technique is adapted to eliminate unnecessary MAD computations involved in the block matching process. Upon introducing the technique to the conventional architecture, the power and complexity of its implantation is reduced, while the accuracy of the motion vector extracted from the block matching process is preserved. The proposed architecture is verified for its functional specifications. A performance evaluation of the proposed architecture is carried out using parameters such as power, area, operating frequency, and efficiency.     

Capacity of SSTS for downlink‐distributed antenna systems in multicell environment

We put forward a novel single selection transmission scheme based on maximum desired signal criterion and investigate the capacity of distributed antenna systems in multicell environment. However, for most of the recent literatures, the interference plus noise is treated as Gaussian random variable with fixed variance by the central limit theorem, which ignores the effect of the short‐term fading on interference. To avoid it, non‐central limit theorem is adopted in which the variance of interference plus noise is considered as a random variable with changeable variance influenced by the short‐term fading. Moreover, channels are assumed to suffer from independent identical Rayleigh fading together with propagation path loss, and the closed‐form expression of capacity for distributed antenna systems is derived. Finally, extensive simulations are carried out to validate the theoretical analysis. Copyright © 2015 John Wiley & Sons, Ltd.     

Blind Source Separation of Instantaneous Mixture of Delayed Sources Using High‐Order Taylor Approximation

This paper deals with the problem of blind source separation (BSS), where observed signals are a mixture of delayed sources. In reference to a previous work, when the delay time is small such that the first‐order Taylor approximation holds, delayed observations are transformed into an instantaneous mixture of original sources and their derivatives, for which an extended second‐order blind identification (SOBI) approach is used to recover sources. Inspired by the results of this previous work, we propose to generalize its first‐order Taylor approximation to suit higher‐order approximations in the case of a large delay time based on a similar version of its extended SOBI. Compared to SOBI and its extended version for a first‐order Taylor approximation, our method is more efficient in terms of separation quality when the delay time is large. Simulation results verify the performance of our approach under different time delays and signal‐to‐noise ratio conditions, respectively.     

基于统计技术改进PVC材料均匀性研究

材料均匀性会直接影响PVC挤出加工和注塑加工的一致性。不均匀材料会造成制品表面粒点、流线和花纹等缺陷。改进材料均匀性可以提高顾客满意度和过程效率。选择材料均匀性评价指标、调查材料均匀性和改进材料均匀性是本文研究的三个方面。利用方差分析对材料均匀性的评价指标进行分析,通过方差分析,确定将灰分作为材料均匀性的评价指标。利用假设检验对材料生产的均匀性进行分析。通过假设检验,证明材料在不同时间的均匀性是不稳定的。利用TRIZ和中心极限定理,对改性PVC材料生产流程进行改进,确定将增加均质化过程以改进材料均匀性。     

应用精细积分法的结构MBC状态方程求解

基于市场机制控制(Market-Based Control,MBC)属于分散控制,以往求解状态方程都采用差分类的近似,有时由于计算存在较大误差,不能得到结构真实状态的精确响应。精细积分法以其高精度、无条件稳定等优点被广泛的应用。文中引入两种精细积分方法,将精细积分的思想运用到基于市场机制(MBC)控制算法的求解中,推导了两种基于MBC控制状态方程的精细递推格式,大大提高了计算的精度及算法的稳定性,并且比较了两种精细积分方法的优缺点。最后通过算例,说明了采用精细积分方法计算MBC控制的必要性及有效性。