Lot-sizing decisions for material requirements planning with hybrid uncertainties in a smart factory

Material requirements planning (MRP) is a kind of medium-term production planning, which aims to plan the end item requirements of the master production schedule over a finite planning horizon. In a smart factory, the customer requirements and the production status are varying in time, which increases the uncertainties in making lot-sizing decisions for MRP. In this study, a hybrid chance-constrained programming (HCCP) model is developed for solving an MRP problem with hybrid uncertainties, in which both randomness and fuzziness exist in a lot-sizing decision process. The objective of the HCCP model is to determine the lot sizes of all items while satisfying the stochastic demands and the fuzzy capacity constraints. The credibility and probability are incorporated into the proposed model to measure the fuzziness and randomness, respectively. In order to solve the model, relevant approaches for converting the probability-based and credibility-based constraints into the equivalent deterministic forms are proposed. Decision makers can set different confidence levels according to their own risk preferences to get different results. Finally, an example is presented to verify that the approach proposed in this paper is feasible for solving MRP problems with hybrid uncertainties.     

Reactive power planning using a new hybrid technique

Voltage deviation and stability constrained VAr planning or reactive power planning (RPP) is an important challenging issue in power systems. This paper presents a new hybrid technique for modeling and solving RPP problem taking into account the static voltage stability constraint. First, the uncertain fuzzy clustering theory is employed to select new candidate VAr source locations. Then, modified gray code is applied and used to represent a series of non-uniform VAr capacity intervals at different candidate buses. Based on the new ordering of the VAr capacity intervals, a simplified piecewise linear function between the total transfer capability and new VAr capacity is derived and applied as static voltage stability constraint in RPP problem. Last, the RPP optimization problem is solved by a self adaptive fuzzy chaotic interactive honey bee mating optimization (FCIHBMO) technique taking advantage of the modified gray code. In the FCIHBMO algorithm, a modified definition of the updating factors on generation solution is proposed. In the case study, uncertain fuzzy clustering mechanism, the modified gray code, and the modified HBMO are applied to the IEEE 118-bus and IEEE 300-bus systems. Test results conclude that the proposed hybrid technique is a simplified and effective approach for voltage stability constrained VAr planning with contingency considered.     

Quality assurance systems information requirements planning

The rapid development of Computer Integrated Manufacturing (CIM) is causing significant difficulties for planning the information requirements for the technical managers of quality assurance systems. This paper examines the general model of information requirements planning for quality assurances with emphasis on the problems of structuring and adapting to a CIM environment.     

柔性能力需求计划算法研究与设计

能力需求计划是企业资源规划中的一个重要的子系统,为实现企业的生产任务提供能力上的保证,是连接计划和生产的桥梁.分析了企业资源规划中现有的能力需求计划算法,发现了在柔性方面现有的能力需求计划算法存在着问题,并且对存在的问题进行了详细的研究,解决了算法中的多工艺路线问题,并针对计算过程中提前期不足的问题提出了提前期不足计划,这些方法使得能力需求计划能够适应我国大多数企业的需求,具有较好的柔性.     

A transform technique for time-varying linear hybrid systems

A computationally oriented transform technique for the analysis of time-varying linear systems involving both discrete-time (i.e., sampled-data) variables and continuous-time variables is presented in this paper. Finite-dimensional representations are described for the various linear operators involved, and methods for obtaining singular-value decompositions of these operators are given. The three parts of the singular-value decomposition are analogous to the direct transform, transfer function, and inverse transform of Laplace and Fourier transforms, and offer analogous insights into analysis and synthesis problems. An example is included to illustrate the analysis procedures.     

RSEDP: an effective hybrid data placement algorithm for large-scale storage systems

The reliability and scalability of large-scale network storage systems are confronted with big challenges, which require designing a reliable, scalable, and efficient data placement algorithm. Previous techniques can only partially satisfy these requirements. In this work, we develop an effective hybrid approach, RSEDP, which combines reliable replication data placement (RRDP) with scalable and efficient data placement (SEDP) to achieve the requirements mentioned above. RRDP distributes replicated data over large-scale heterogeneous network storage systems in which the same replica is distributed to different devices and not inclined to consecutive devices, achieving high redundancy degree and failure resilience. SEDP assigns data evenly among devices according to their weight and scales well to the expansions or curtailments of the systems. In order to take the advantages of both RRDP and SEDP, RSEDP integrates them by categorizing data into hot and cold data based on their access frequency, placing hot data by RRDP, and distributing the remainder by SEDP. The theoretical analysis and the experimental study show that the combined RSEDP can increase redundancy degree and failure resilience, and has a good scalability and time efficiency with small memory overhead.     

HAT: an efficient buffer management method for flash-based hybrid storage systems

Flash solid-state drives (SSDs) provide much faster access to data compared with traditional hard disk drives (HDDs). The current price and performance of SSD suggest it can be adopted as a data buffer between main memory and HDD, and buffer management policy in such hybrid systems has attracted more and more interest from research community recently. In this paper, we propose a novel approach to manage the buffer in flash-based hybrid storage systems, named hotness aware hit (HAT). HAT exploits a page reference queue to record the access history as well as the status of accessed pages, i.e., hot, warm, and cold. Additionally, the page reference queue is further split into hot and warm regions which correspond to the memory and flash in general. The HAT approach updates the page status and deals with the page migration in the memory hierarchy according to the current page status and hit position in the page reference queue. Compared with the existing hybrid storage approaches, the proposed HAT can manage the memory and flash cache layers more effectively. Our empirical evaluation on benchmark traces demonstrates the superiority of the proposed strategy against the state-of-the-art competitors.     

An evaluation of lot-sizing heuristics for deteriorating inventory in material requirements planning systems

In this paper, we consider the effects of deteriorating inventory on lot-sizing in material requirements planning systems. Five existing heuristics were extended to address the single-level lot-sizing problem with deteriorating inventory and evaluated via a large-scale simulation study. Three factors were taken into consideration for the simulation study, namely, rate of inventory deterioration, percentage of periods with zero demand, and setup cost. Our computational results, undertaken within a wide range of experimental conditions, indicate that one of the modified heuristics exhibits the best overall cost performance. We also provide insights in regard to the cost performance behavior of the five modified heuristics.     

Integrated planning information systems: Context, design requirements, and prospects

This research contributes to the theoretical basis for appropriate design of computer-based, integrated planning information systems. The research provides a framework for integrating relevant knowledge, theory, methods, and technology. Criteria for appropriate system design are clarified. The requirements for a conceptual system design are developed based on “diffusion of innovation” theory, lessons learned in the adoption and use of existing planning information systems, current information-processing technology (including expert system technology), and methodology for evaluation of mitigation strategies for disaster events. Research findings focus on the assessment of new information systems technology. Chief among these findings is the utility of case-based reasoning for discovering and formalizing the meta rules needed by expert systems, the role of the “diffusion of innovation” theory in establishing design criteria, and the definition of client interests served by integrated planning information systems. The work concludes with the selection of a prototyping exercise. The prototype is developed in a forthcoming technical paper (Masri & Moore, 1994).     

Distributed planning and control systems for the virtual enterprise: organizational requirements and development life-cycle

This paper describes the requirements analysis and system specification of an Order Promise module to be used as part of a broader Decision Support System for production and operations planning of a Virtual Enterprise. This work is part of a broader project with a particular focus on the microelectronics industry which is a good example of Virtual Enterprise, and where a quick response to the customers needs and to unpredictable changes in production conditions is considered a major factor for success. First, the analysis and specification are presented within a development framework that involves the study of organizational issues of semiconductor enterprises. The use of ontological engineering for supporting the communication and shared understanding of the system concepts is explained and a virtual enterprise ontology is outlined. Following the clarification of the concept of virtual enterprise, the generic techno-organizational requirements for the information system are derived. Finally, a specification of the global planning module and a more detailed one regarding the order promise module is presented.     

微电网中混合储能系统的规划运行一体化配置方法

目前针对微电网中储能容量配置的经济优化算法中,大多都是直接以储能系统的全寿命周期成本作为目标函数.然而微电网作为一个整体,不同的能量调度方案会导致不同的储能配置需求,因此微电网的运行目标也会间接影响到储能系统的全寿命周期成本.本文提出的规划运行一体化配置方法,是从微电网的整体经济效益出发,将储能系统全寿命周期成本的直接和间接影响因素都考虑在内,建立了计及微电网经济运行的储能全寿命周期成本复合模型.通过算例验证以及与已有方法优化结果的对比分析,说明了所提方法在提升微电网整体经济效益上的有效性,可以为评估微电网中混合储能系统的配置效果提供更全面的参考依据.     

Dynamic control and motion planning technique for a class of nonlinear systems with drift

The paper addresses the synthesis of a smooth dynamic feedback for a class of nonholonomic systems (nonlinear systems with drift). The proposed technique provides asymptotic stability and convergence to a desired equilibrium manifold. The manifold is a (task) function of the generalized co-ordinates. Applications of the proposed technique to control of two classes of nonholonomic systems are presented.     

KidReporter: a user requirements gathering technique for designing with children

This paper describes a design method, novel to the domain of interaction design, for gathering user requirements from children called the KidReporter method. The KidReporter method was chosen and further refined based on assumptions about User-Centred Design. The method was considered to be suitable and appealing for children in terms of participating in design. Two school classes participated in making a newspaper about a zoo, to gather requirements for the design process of an interactive educational game. The educational game was developed to educate children about animals while walking through a zoo. The KidReporter method's main strengths are that it combines many techniques for eliciting information from children, such as interviews, drawing and making pictures. In this paper we describe how the KidReporter method was applied, in what manner it was successful and what we would do differently next time.     

An efficient planning technique for robotic assemblies and intelligent robotic systems

An efficient planning algorithm for the organization and formulation of complete plans applicable to both robotic assemblies and intelligent robotic systems is proposed. The constraint of task precedence and the concepts of the criticality of tasks-events and valid repetitive orderings are introduced to facilitate and optimize the formulation of every complete plan capable of executing a user-requested job. Two examples demonstrate the applicability of the proposed algorithm to both robotic assemblies and intelligent robotic systems.     

A feedback-based adaptive data migration method for hybrid storage VOD caching systems

Nowadays Video-On-Demand (VOD) caching systems are often equipped with hybrid storage devices, which have been designed to combine the high read speed of Solid State Disks (SSDs) and the large capacity of Hard Disk Drives (HDDs). However, the number of erase cycles of SSDs is limited. So it is important to control the write load of SSDs in real applications. This paper proposes a Feedback-based Adaptive Data Migration (FADM) method, which can utilize the real-time feedback of the write load of SSDs to adjust the rule of moving data between HDDs and SSDs. More specifically, a video in HDDs is allowed to be moved into SSDs when its popularity is higher than that of the least popular video in SSDs by a threshold. This threshold is adaptively adjusted according to the feedback of the write load of SSDs. With FADM, the desired lifetime of SSDs can be well guaranteed even under various user behaviors while good read performance can be maintained. Simulations are done to demonstrate the effectiveness of FADM.     

Reducing object storage requirements in a multi-user environment

Many Smalltalk implementations store objects in a large file called a virtual image. Each user must have a copy of the virtual image to execute. Since the image can exceed a megabyte in size, considerable disk space is required to support such a system in a multi-user environment. In this paper, a method is described which can reduce storage requirements for systems which use generation scavenging as a memory reclamation technique. This method also improves the performance of the checkpoint operation and offline garbage-collection.