Controlling general multi-echelon distribution supply chains with improved reorder decision policy utilizing real-time shared stock information

The objective of this paper is to introduce an improved reorder decision policy for controlling general multi-echelon distribution systems utilizing shared stock information. Since traditional reorder policies sometimes show poor performances when applied to distribution systems, the order risk policy, which utilizes shared stock information more accurately, was developed for the two-echelon distribution system in the previous research. In this paper, the order risk policy is extended to general multi-echelon systems. Since the calculation of the exact order risk for general multi-echelon systems is complex, a practical approximation method is developed. Through computational experiments, the superior performance of the order risk policy, compared to the existing reorder policies, is shown and the value of shared stock information varying with the characteristics of the supply chain is analyzed.     

Expert systems for inventory control management

An expert system for inventory management is presented in this paper. The focus is on the development of a simple, user friendly tool that can be used by managers to increase the effectiveness of their inventory control systems. The expert system is capable of deriving input parameters by performing necessary analysis on databases, implementing a set of rules for the selection of inventory models, and present the output through tables. plots, or graphs. The scope of this paper is limited to the single item, single location problem.     

Time delay systems with distribution dependent dynamics

General delay dynamical systems in which uncertainty is present in the form of probability measure dependent dynamics are considered. Several motivating examples arising in biology are discussed. A functional analytic framework for investigating well-posedness (existence, uniqueness and continuous dependence of solutions), inverse problems, sensitivity analysis and approximations of the measures for computational purposes is surveyed.     

DRP分销管理系统的设计与实现

DRP是管理企业的分销网络系统,目的是使企业具有对订单和供货具有快速反应和持续补充库存的能力。通过互联网将供应商与经销商有机地联系在一起,DRP为企业的业务经营及与贸易伙伴的合作提供了一种全新的模式。该文使用Java作为开发语言,采用Struts2框架技术搭建整个系统,数据库采用SQL2000,Eclipse5．11作为开发工具,设计并实现了DRP分销管理系统。     

Analyzing information-enabled stockout management under vendor-managed inventory

We develop a mechanism under vendor-managed inventory (VMI) by which a manufacturer provides an incentive contract to a retailer to convert lost sales stockouts into backorders. An incentive contract is required since the retailer’s efforts are not directly observable. We first show that when there are no limits on order quantities or inventory levels imposed on the manufacturer, the manufacturer will push inventory onto the retailer. The manufacturer minimizes the possibility for lost sales stockouts by maintaining high inventory levels at the retailer rather than by paying incentives to the retailer. However, modern information systems (IS), such as radio frequency identification (RFID), allow the retailer to monitor inventory at its premises and to enforce limits on order quantities. With strict limits on order quantities, the manufacturer will provide incentives to the retailer to convert lost sales stockouts to backorders. We analyze the conditions under which these incentive payments are likely to be highest.     

Efficient tag detection in RFID systems

Recent technological advances have motivated large-scale deployment of RFID systems. However, a number of critical design issues relating to efficient detection of tags remain unresolved. In this paper, we address three important problems associated with tag detection in RFID systems: (i) accurately detecting RFID tags in the presence of reader interference (reader collision avoidance problem); (ii) eliminating redundant tag reports by multiple readers (optimal tag reporting problem); and (iii) minimizing redundant reports from multiple readers by identifying a minimal set of readers that cover all tags present in the system (optimal tag coverage problem). The underlying difficulties associated with these problems arise from the lack of collision detection mechanisms, the potential inability of RFID readers to relay packets generated by other readers, and severe resource constraints on RFID tags. In this paper we present a randomized, distributed and localized Reader Collision Avoidance (RCA) algorithm and provide detailed probabilistic analysis to establish the accuracy and the efficiency of this algorithm. Then, we prove that the optimal tag coverage problem is NP-hard even with global knowledge of reader and tag locations. We develop a distributed and localized Redundant Reader Elimination (RRE) algorithm, that efficiently identifies redundant readers and avoids redundant reporting by multiple readers. In addition to rigorous analysis of performance and accuracy, we provide results from elaborate simulations for a wide range of system parameters, demonstrating the correctness and efficiency of the proposed algorithms under various scenarios.     

Data management in executive information systems

Data management is important in developing and maintaining executive information systems (EISs). An EIS can fail due to the lack of an adequate data infrastructure for this `data intensive' application. From the literature, discussions with developers, consulting experiences, and eight case studies, a set of key data management issues were identified. Three – data security, ownership, and standards – were further studied, using survey data collected from 85 organizations. Canonical correlation analysis was used to investigate the relationship between these issues and potentially related variables. The breadth and depth of information provided were found to be correlated with the difficulty of the issues. The degree of support from key individuals was also found to be correlated with the level of difficulty.     

Limiting zero distribution of sampled systems

In this paper, we consider the sampling of a continuous time system with possibly a non-rational transfer function. Limiting zero distribution of the sampled system represented by an FIR model is derived. It is shown that the zeros of the FIR sampled system converge evenly to the unit circle or to the unit disk plus unstable roots of the reciprocal polynomials depending on assumptions.     

Asymptotic stability in distribution of stochastic systems with semi-Markovian switching

This paper investigates the asymptotic stability in distribution of stochastic systems with semi-Markovian switching whose transition rates are time varying, which are more general than stochastic systems with Markovian switching. Some sufficient conditions for the asymptotic stability in distribution of stochastic systems with semi-Markovian switching are established and those conditions are employed to design the state-feedback controllers in terms of linear matrix inequalities. Finally, several examples are given to illustrate the effectiveness of the theoretical results.     

Peaking demand factor-based reliability analysis of water distribution systems

Water demands vary and consideration of the probabilistic nature of the variations should lead to more instructive assessments of the performance of water distribution systems. Water consumption data for several households were analysed using the chi-square technique and it was found that distributions worth considering under certain circumstances include the normal and lognormal.Reliability values were calculated for a range of critical demand values and the corresponding confidence levels determined from the probability distributions. Water consumption was assumed to be pressure dependent and the modelling of the water distribution system was carried out accordingly. This peaking factor approach coupled with the statistical modelling of demands provides a more realistic way of incorporating variations in demands in the evaluation and reporting of system performance than the traditional single demand value approach in that the extent to which a network can satisfy any demand and the probability that the demand will occur can be recognized explicitly. The method is illustrated by an example.     

DRP分销管理系统的设计与实现

DRP是管理企业的分销网络系统,目的是使企业具有对订单和供货具有快速反应和持续补充库存的能力。通过互联网将供应商与经销商有机地联系在一起,DRP为企业的业务经营及与贸易伙伴的合作提供了一种全新的模式。该文使用Java作为开发语言,采用Struts2框架技术搭建整个系统,数据库采用SQL2000,Eclipse5.1[1]作为开发工具,设计并实现了DRP分销管理系统。     

Parameters of cache systems based on a Zipf-like distribution

The object of this paper is to explain a system of Internet traffic caching. The task is to create an analytical model of a cache system linking its size with other parameters by boundary conditions. A definition of a dynamic cache model is introduced. The parameters of a cache system are calculated using the Zipf's first law and Zipf-like distribution. The correspondence between size of a cache system and aggregated bandwidth of external links is derived.     

A delay-range-partition approach to analyse stability of linear systems with time-varying delays

In this paper, the stability analysis of linear systems with an interval time-varying delay is investigated. First, augmented Lyapunov–Krasovskii functionals are constructed, which include more information of the delay's range and the delay's derivative. Second, two improved integral inequalities, which are less conservative than Jensen's integral inequalities, and delay-range-partition approach are utilised to estimate the upper bounds of the derivatives of the augmented Lyapunov–Krasovskii functionals. Then, less conservative stability criteria are proposed no matter whether the lower bound of delay is zero or not. Finally, to illustrate the effectiveness of the stability criteria proposed in this paper, two numerical examples are given and their results are compared with the existing results.     

On developing an inventory management system in the client/server environment

It is reported that client/server technology can make it easier for users to access information, to use and to develop applications, and to manage a distributed computing environment. This paper describes the implementation of client/server technology to an inventory management system. Methodology developed and barriers faced in this study are useful for practitioners in building client/server applications.     

Robust fault detection filter design for networked control systems with delay distribution characterisation

In this article, robust fault detection (RFD) is investigated for networked control systems with delay distribution characterisation. By utilising an observer-based fault detection filter as a residual generator, the RFD of networked control systems with non-uniformly distributed network‐induced time-varying delay is formulated as an H _∞ model-matching problem. Delay-interval-dependent and delay-interval-occurrence-rate-dependent sufficient conditions are obtained by employing the Lyapunov–Krasovskii functional approach. Especially, the robust fault detection filters guarantee strong robustness from residual signal to disturbance as well as high sensitivity to faults. A numerical example is given to illustrate the effectiveness of the proposed design techniques.     

基于知识管理的信息系统项目管理研究

以构建基于知识管理的信息系统项目管理模式为目的，提出了以知识管理为中心的信息系统项目管理领域模型、以知识管理为主导的信息系统项目管理过程模型、以知识为基础的信息系统项目管理组织发展层次模型以及以知识和知识管理为纽带的信息系统项目管理总体框架，用于指导信息系统项目管理实践。     

The distribution free continuous review inventory system with a service level constraint

The stochastic inventory models require the information on the lead time demand. However, the distributional information of the lead time demand is often limited in practice. We relax the assumption that the cumulative distribution function, say F, of the lead time demand is completely known and merely assume that the first two moments of F are known and finite. The distribution free approach for the inventory model consists of finding the most unfavorable distribution for each decision variable and then minimizing over the decision variable. We apply the distribution free approach to the continuous review inventory system with a service level constraint. We develop an iterative procedure to find the optimal order quantity and reorder level.     

Efficient and scalable scheduling for performance heterogeneous multicore systems

Performance heterogeneous multicore processors (HMP for brevity) consisting of multiple cores with the same instruction set but different performance characteristics (e.g., clock speed, issue width), are of great concern since they are able to deliver higher performance per watt and area for programs with diverse architectural requirements than comparable homogeneous ones. However, such power and area efficiencies of performance heterogeneous multicore systems can only be achieved when workloads are matched with cores according to both the properties of the workload and the features of the cores.