Markov chain representations of discrete distributions applied to queueing models

We present applications of Markov chain based representations of discrete renewal distributions to queueing models, and extend the notion of that representation to some non-renewal discrete distributions. Two representations are considered; one based on remaining time, the other on elapsed time. These representations make it easier to use matrix-analytic methods for several stochastic models, especially queueing models, thereby allowing us to develop better algorithmically tractable procedures for their analysis. Specifically, they allow us to capitalize on the resulting special structures. We first discuss some key measures of these distributions using phase type distribution results, including some time reversibility relations between the elapsed and remaining time representations. We then show applications to the MAP/G/1, the GI/MSP/1 and the GI/G/1 systems, and briefly explain how the representations of the non-renewal types of discrete distributions can be used for the MRP/SMP/1 system. The emphasis of this paper is about efficient procedures for the R and G matrices associated with these queueing models.     

The stopped distributions of a controlled Markov chain with discrete time

A characterization is given, in terms of excessive functions, of possible stopped distributions of a controlled Markov chain with given initial distribution. Control here is understood as a mixing of a given finite number of Markov chains. It is an extension of results of Rost for more than one Markov kernel.     

Large deviations for distributions of sums of random variables: Markov chain method

Let {ξ _k } _k=0^∞ be a sequence of i.i.d. real-valued random variables, and let g(x) be a continuous positive function. Under rather general conditions, we prove results on sharp asymptotics of the probabilities $ P\left\{ {\frac{1} {n}\sum\limits_{k = 0}^{n - 1} {g\left( {\xi _k } \right) < d} } \right\} $ P\left\{ {\frac{1} {n}\sum\limits_{k = 0}^{n - 1} {g\left( {\xi _k } \right) < d} } \right\} , n → ∞, and also of their conditional versions. The results are obtained using a new method developed in the paper, namely, the Laplace method for sojourn times of discrete-time Markov chains. We consider two examples: standard Gaussian random variables with g(x) = |x| ^p , p > 0, and exponential random variables with g(x) = x for x ≥ 0.     

Measurement of low energy secondary electron distributions using a double-pass cylindrical mirror analyzer

A commercial double-pass cylindrical mirror analyzer (CMA) and standard Auger electron spectroscopy electronics have been adapted to measure the low energy portion (< 100 eV) of the secondary electron distribution. Under normal operating conditions for the CMA, the presence of stray electric and magnetic fields within the CMA plus the poor electron multiplier response at low energy prevent measurements in the region where the secondary electron distribution reaches its maximum (< 5 eV). To circumvent this problem, we apply an accelerating potential (70 V) to the “retarding” grid at the entrance of the CMA. The accelerating potential translates the secondary electron distribution to high enough energies that the theoretical response of the CMA (E·N (E)) is valid, but low enough to give reasonable resolution. Moreover, we are able to separate the small tertiary electron peak due to the outer (grounded) grid by applying a small accelerating potential to the sample. This use of the CMA for measuring secondary electron distributions allows the surface to be characterized by AES before and after measurement. We present results for clean copper and silver. In the log N(E) versus log E format, we observe the linearized cascade with Auger peaks clearly visible.     

Stepwise design of real-time systems

The joint action approach to modeling of reactive systems is presented and augmented with real time. This leads to a stepwise design method where temporal logic of actions can be used for formal reasoning, superposition is the key mechanism for transformations, the advantages of closed-system modularity are utilized, logical properties are addressed before real-time properties, and real-time properties are enforced without any specific assumptions on scheduling. As a result, real-time modeling is made possible already at early stages of specification, and increased insensitivity is achieved with respect to properties imposed by implementation environments     

以智慧能源服务平台为载体打造能源服务产业链

我国提出“双碳”、“产业生态化”与“数字化发展”的政策方向。南方电网提出向“三商转型”与打造平台型企业的战略目标。广东电网提出以客户代维为切入口构建能源服务生态圈的规划。广东电网能源投资有限公司践行南方电网战略与广东电网规划,以云计算、大数据、物联网、移动互联网、人工智能、区块链等新一代数字技术为核心驱动力搭建“粤能投”智慧能源服务平台,以数据为关键生产要素推动客户管理、营销推广、业务应用、创新孵化、决策管控等多项专业高效协同,以产业链上下游合作伙伴、代维服务商、设备供应商、综合能源服务商的聚合打造一个共享、开放、共赢的能源服务生态,从而实现数据为公司的业务赋能与管理赋能,并促进公司向能源价值链整合商转型。     

Stepwise estimation of common principal components

The standard common principal components (CPCs) may not always be useful for simultaneous dimensionality reduction in k groups. Moreover, the original FG algorithm finds the CPCs in arbitrary order, which does not reflect their importance with respect to the explained variance. A possible alternative is to find an approximate common subspace for all k groups. A new stepwise estimation procedure for obtaining CPCs is proposed, which imitates standard PCA. The stepwise CPCs facilitate simultaneous dimensionality reduction, as their variances are decreasing at least approximately in all k groups. Thus, they can be a better alternative for dimensionality reduction than the standard CPCs. The stepwise CPCs are found sequentially by a very simple algorithm, based on the well-known power method for a single covariance/correlation matrix. Numerical illustrations on well-known data are considered.     

Stepwise development of fair distributed systems

A theory of fairness which supports the specification and development of a wide variety of “fair” systems is developed. The definition of fairness presented is much more general than the standard forms of weak and strong fairness, allowing the uniform treatment of many different kinds of fairness within the same formalism, such as probabilistic behaviour, for example. The semantic definition of fairness consists of a safety condition on finite sequences of actions and a liveness or termination condition on the fair infinite sequences of actions. The definition of the predicate transformer of a fair action system permits the use of the existing framework for program development, including the existing definitions of refinement and data refinement, thus avoiding an ad hoc treatment of fairness. The theory includes results that support the modular development of fair action systems, like monotonicity, adding skips, and data refinement. The weakest precondition and the weakest errorfree precondition are unified, so that in particular a standard action system is a special case of a fair action system. The results are illustrated with the development from specification of an unreliable buffer. Received: 3 January 2000 / 17 November 2002     

一种基于逼近理论的曲面重构方法

从离散点列构造一条曲线出发,提出了一种可以处理散乱数据点的曲面重构方法,其主要思想是逐步逼近,即分别用平面三角形和三角Bezier曲面片逼近。详细介绍了空间点的三角划分、离散点的参数化、三角Bezier曲面片逼近以及两曲面片的拼接等算法;最后,给出了几个应用实现。     

条码技术在成车装配车间的应用

在介绍条码技术的基础,根据企业的实际情况,选择了一维纸质条码作为条码系统的基础。在分析装配生产线的业务流程的基础上,设计了成车条码系统的硬件拓扑结构和软件结构。通过和企业ERP系统集成,实现了数据共享,提高了生产计划的执行能力和产品下线合格率。     

链路预测下能源供应链网络合作演化机制研究

应用供应链网络结构或节点的属性信息预测未产生链接的节点企业合作的可能性是链路预测应用供应链网络合作演化分析的关键,利用链路预测的理论框架和评价方法,借助5种相似性指标对能源供应链网络合作连边演化进行预测。研究结果表明:当使用供应链网络结构属性作为单一相似性指标时,RWR指标的预测效果最好;耦合指标预测精确度要比单独考虑单一指标时有显著提高;RWR指标和Katz指标耦合效果要优于和CN指标、PA指标、LP指标耦合效果,且RWR指标在耦合算法中起到主导性作用;与直接建立网络演化模型相比,链路预测在分析供应链网络合作演化机制上更为有效。     

基于半马尔科夫链的无线网络能耗模型的研究

在分析无线传感网络能量消耗特征的基础上,根据无线通信环境和节点的状态转换关系,建立了基于半马尔科夫链的无线传感网络的能耗模型,并通过仿真实验验证得出传感节点实际能耗剩余值与所建模型能耗预估值基本相同,从而说明所建立的能耗模型准确有效,为改变传感节点工作状态、延长传感网络使用寿命提供了可靠的节点能量数据.     

Modeling decision processes of a green supply chain with regulation on energy saving level

In this study, we first investigate the impact policy makers have when they set a threshold value of energy saving levels. We examine the impact on energy saving level and price of environmentally friendly products (EFP) decided by green supply chains within two different structures, i.e. vertical integration and a decentralized setting. Then, considering the tradeoff between energy savings and profits made by supply chains, we analyze decisions of the policy makers. In addition, we investigate the coordination of a supply chain by using the common wholesale pricing and profit sharing (WPPS) schemes and a lump sum transfer contract. A numerical example is used to illustrate the related issues. Observations are made, and managerial insights are indicated for the policy maker in setting threshold values of energy saving levels.     

Manufacturing, assembling and packaging of miniaturized neural implants

Implantable medical devices to interface technical aids with muscles, peripheral nerves, and the brain have been developed for many applications over the last decades. They have been investigated in fundamental neuroscientific studies and some of them have been transferred into clinical practice in diagnosis, therapy and rehabilitation, respectively. Success stories of these implants have been written with help of precision mechanics manufacturing techniques. Latest cutting edge research approaches to restore vision in blind persons and to develop an interface with the human brain as motor control interface, however, need more complex systems, larger scales of integration and higher degrees of miniaturization. Microsystems engineering offers adequate tools, methods, and materials but so far, no MEMS based active medical device has been transferred into clinical practice. Here, different designs, manufacturing technologies and packaging paradigms will be presented and assessed in close relation to the envisioned neuroscientific or medical application.     

Fingerprint reference point identification based on chain encoded discrete curvature and bending energy

Reference point identification is important in automatic fingerprint recognition system as it can be used to align fingerprints in a correct orientation in spite of the possibility of different transformations in fingerprint images. It is also used in fingerprint classification, as it is desirable to classify fingerprint images for forensic type applications which require the input image to be verified against a large database. The important feature information useful for classification is centered near the reference point. Most of the current approaches for identifying the reference point either require determining ridge orientation or use some complex filters. These methods either operate on 2D (two dimensional) or are not robust to rotation or cannot be applied to every class of fingerprint image. This paper proposes a method to reliably identify unique reference point that operates in 1D (one dimensional). The method treats the fingerprint ridges as a non-overlapped sequence of chain code segments. A modified k-curvature method has been proposed to find the high-curvature area of fingerprint ridges. The reference point localization is based on the property of the ridge’s bending energy. The proposed method is tested on FVC2002 and FVC2004 standard datasets, and the experimental results show that the proposed algorithm can accurately locate reference point for all types of fingerprint images.     

Problem solution sustenance in XCS: Markov chain analysis of niche support distributions and the impact on computational complexity

Michigan-style learning classifier systems iteratively evolve a distributed solution to a problem in the form of potentially overlapping subsolutions. Each problem niche is covered by subsolutions that are represented by a set of predictive rules, termed classifiers. The genetic algorithm is designed to evolve classifier structures that together cover the whole problem space and represent a complete problem solution. An obvious challenge for such an online evolving, distributed knowledge representation is to continuously sustain all problem subsolutions covering all problem niches, that is, to ensure niche support. Effective niche support depends both on the probability of reproduction and on the probability of deletion of classifiers in a niche. In XCS, reproduction is occurrence-based whereas deletion is support-based. In combination, niche support is assured effectively. In this paper we present a Markov chain analysis of the niche support in XCS, which we validate experimentally. Evaluations in diverse Boolean function settings, which require non-overlapping and overlapping solution structures, support the theoretical derivations. We also consider the effects of mutation and crossover on niche support. With respect to computational complexity, the paper shows that XCS is able to maintain (partially overlapping) niches with a computational effort that is linear in the inverse of the niche occurrence frequency.

期待物流信息化整体推进——自动识别企业在物流业中探索技术应用之路

物流业本身的特点决定了其对信息传输的依赖程度较其他行业更高。所以,物流业发展本身就是一个信息化的过程。随着近几年来国内物流信息化投入力度不断加大,物流业的整体发展速度也在加快。然而与发达国家相比,我国物流业起步较晚,信息化建设水平参差不齐,这已成为国内物流业整体快速发展的重要制约因素。所以,如何解决物流信息化过程中的种种矛盾和问题,成为业界关注的焦点。本刊着重从信息采集的角度,邀请多年研究物流信息化的资深专家、中国物流与采购联合会副会长戴定一,以及自动识别行业的相关企业共同探索物流信息化的发展方向和自动识别技术在此过程中的应用前景。