An integrated model for the design of end-of-aisle order picking system and the determination of unit load sizes of AGVs

In this paper, we deal with an assembly line production system in which an automated guided vehicle (AGV) delivers parts to each workstation of assembly lines from a miniload automated storage/retrieval system (AS/RS). Each assembly production line is characterized by a sequence of workstations linked together for the production of a given type of product. We consider simultaneously the design problem of miniload AS/RS and the problem of determining a unit load size of the AGV. First, a non-linear mathematical model is formulated under a proposed AGV dispatching policy. And then, we determine an appropriate sequence of lines of the vehicle visits. Finally, based on the characteristics of the objective function and feasible region of the decision variables, a heuristic solution procedure is developed to find a near optimal solution. To examine the validity of the model, an example problem is solved.     

基于进程代数的网络体系结构形式化模型

首先用形式化方法给出了网络实体、网络连接件和网络体系结构框架模型的定义,然后利用进程代数理论定义了网络体系结构上的网络实体运算,进而建立了网络体系结构的代数模型,为进一步研究网络体系结构打下了坚实的理论基础。     

A simulation methodology for a system of product life cycle systems

To realize environmental sustainability, the flow of natural resources into industrial systems must be reduced and stabilized at a suitable level. One way to reduce resource flows in society is to establish resource-circulating manufacturing systems. To foster the circulation of resources in industry, life cycle simulation (LCS) technologies, which are based on discrete-event modeling, have been developed to dynamically evaluate the life cycles of products from resource extraction to end of life from both environmental and economic aspects. In reality, various industrial products interact with each other in unanticipated ways, and then these interactions affect the material flows in product life cycles. This type of complex system is called a system of systems (SoS). Focusing on this issue, we expand the evaluation's system boundary to include a system of multiple product life cycle systems. To handle an SoS quantitatively, we introduce typical types of interactions between product life cycle systems. The purpose of this study was to propose a new LCS methodology, called “LCS4SoS,” that focuses on an SoS consisting of different kinds of product life cycle systems. A prototype system of LCS4SoS was implemented based on this proposed methodology. Through a case study, it was found that the proposed methodology is useful for evaluating an SoS consisting of multi-product life cycle systems.     

基于进程代数的安全软件体系结构建模

分析了基于进程代数的软件体系结构模型的安全性,将相容性检查和互操作性检查从单个软件体系结构推广到不同风格的体系结构风格,扩展基于进程代数的软件体系结构描述语言,通过顺序进程代数项族和预定义的体系结构类型调用对软件体系结构安全建模。通过一个例子介绍了这种建模方法。     

A process algebra to formalize the Lyee methodology

Over the last years, various methodologies and techniques have been elaborated and proposed to improve one or many aspects related to the software development life cycle. However, despite the great effort in this research field, the production of clearly understood and modifiable systems still an ambitious goal and far from reached. This is due, on one hand, to the complexity and the subtlety of software themselves and, on the other hand, to the limitations of the current methodologies. Recently, a new and very promising methodology, called Lyee, has been proposed. Intended to deal efficiently with a wide range of software problems related to different field, Lyee allows the development of software by simply defining their requirements.

Nevertheless, since both the semantics of Lyee generated software together with the process of automatic generation of software from requirements are described using informal language, difficulties and confusions may arise when trying to understand and study this methodology.

The main purpose of this paper is to formalize, using a process algebra, the process of automatic generation of softwares together with the semantics of Lyee generated softwares. Actually, process algebra naturally supports many concepts of the Lyee methodology and consequently formalize them simply and elegantly. It offers to the Lyee methodology an abstract machine more suitable than the Von-Newman one. In fact, this new abstract machine consider a program as chemical solution when molecules (different vectors of the lyee methodology) interact together to reach a collective goal.     

Equivalences for a biological process algebra

This paper investigates Bio-PEPA, the stochastic process algebra for biological modelling developed by Ciocchetta and Hillston. It focuses on Bio-PEPA with levels where molecular counts are grouped or concentrations are discretised into a finite number of levels. Basic properties of well-defined Bio-PEPA systems are established after which equivalences used for the stochastic process algebra PEPA are considered for Bio-PEPA, and are shown to be identical for well-defined Bio-PEPA systems. Two new semantic equivalences parameterised by functions, called g-bisimilarity and weak g-bisimilarity are introduced. Different functions lead to different equivalences for Bio-PEPA. Congruence is shown for both forms of g-bisimilarity under certain reasonable conditions on the function and the use of these equivalences are demonstrated with a biologically-motivated example where two similar species are treated as a single species, and modelling of alternative pathways in the MAPK kinase signalling cascade.     

基于单亲遗传算法的拣选作业优化研究

针对自动化立体仓库高存储、高速度、高效率的特点,对拣选作业的运行过程进行分析,建立了相应的拣选作业优化模型,并设计一种高效的单亲遗传算法用于求解。通过仿真验证,结果表明该算法具有很好的全局搜索能力,并能很好地兼顾优化时间和优化效果两个方面,满足实际作业运行要求,适合在实际工程中使用。     

CSP-CASL—A new integration of process algebra and algebraic specification

CSP–CASL integrates the process algebra CSP [T. Hoare, Communicating Sequential Processes, Prentice-Hall, Englewood cliffs, NJ, 1985; A.W. Roscoe, The Theory and Practice of Concurrency, Prentice-Hall, Englewood cliffs, NJ, 1998] with the algebraic specification language CASL [P.D. Mosses (Ed.), CASL Reference Manual, Lecture Notes in Computer Science, Vol. 2960, Springer, Berlin, 2004; E. Astesiano, M. Bidoit, B. Krieg-Brückner, H. Kirchner, P.D. Mosses, D. Sannella, A. Tarlecki, CASL—the common algebraic specification language, Theoret. Comput. Sci. 286 (2002) 153–196]. Its novel aspects include the combination of denotational semantics in the process part and, in particular, loose semantics for the data types covering both concepts of partiality and sub-sorting. Technically, this integration involves the development of a new so-called data-logic formulated as an institution. This data-logic serves as a link between the institution underlying CASL and the alphabet of communications necessary for the CSP semantics. Besides being generic in the various denotational CSP semantics, this construction leads also to an appropriate notion of refinement with clear relations to both data refinement in CASL and process refinement in CSP.     

基于过程模型随机仿真的TDD模块选取建模方法研究*

为了帮助项目经理合理选择TDD实施模块,基于进程代数方法对测试驱动软件开发过程和非测试驱动软件开发过程建立过程仿真模型。通过用例度量软件模块的复杂性来获取随机变量参数对模型调参,并采用该模型得到仿真结果。提出TDD模块选取算法来分析仿真结果并得出最佳TDD实施策略,最终为项目经理提供合理的决策。     

A performance evaluation model for order picking warehouse design

This paper is concerned with a performance evaluation model for the order picking facility for warehouse design in a supply center (SC) by reducing the travel distance of transporters. This study includes important detail aspects of warehouse design and operational parameters such as warehouse size, rack size, number of transporters, and the system performance. In this study, we develop both mathematical and simulation modes considering probabilistic demand and picking frequency, and using simulation S/W, AutoMod. The results are compared and validated via simulation methods using AutoMod simulator. Finally, we developed a systematic and practical computer program and it was known that the proposed method is potentially efficient and useful in performance analysis for order picking warehouse problems.     

Design and simulation based validation of the control architecture of a stacker crane based on an innovative wire-driven robot

Automated Storage/Retrieval Systems (AS/RS) have an important role in the improvement of the performance of automated manufacturing systems, warehouses and distribution centers. Existing AS/R systems are usually based on Cartesian Storage/Retrieval Manipulators (SRM). Such systems have reached their maximum performance due to the limitations of their underlying mechanical design and associated control architecture. Going beyond the limits of existing systems requires structural innovation and breakthrough solutions to enhance their design and performance. In this study, we introduce the design and simulation based evaluation of a stacker crane based on an innovative wire-driven SRM. We describe the basic components and provide an overview of the mechanical design of the system. We design the high-level control architecture that allows handling mini-load operations. We develop the equations that determine the single and dual command cycle times for the wire-driven SRM in case of random and class-based storage policies. We validate the suggested control architecture using a simulation software specifically developed for this purpose. We benchmark the wire-driven SRM against an equivalent Cartesian SRM. Results show that the new wire-driven SRM design and control architecture are more competitive than Cartesian SRM in terms of travel cycle times, and more suitable for buildings growing in height.     

概率逻辑系统是与集合代数同态的布尔代数

联结词的本质是命题的运算,只有对所有命题都适用的真值函数才能用于定义联结词.概率逻辑中由于命题的内涵相关性,任何[0,1]上的函数都不能完全适用于任意命题的运算,概率逻辑的联结词不能定义成真值函数.各种算子可以作为一种计算方法使用和研究,但不能代表一个逻辑系统研究系统的性质.概率逻辑系统是概率空间的逻辑表示,是与概率空间中的事件域(集合代数)同态的布尔代数.用事件域上的集合函数精确定义各种联结词,与经典二值逻辑相容,与事实相符,能够在经典逻辑框架内实现概率命题演算.     

Simulation modelling of a narrow aisle automated storage and retrieval system (AS/RS) serviced by rail-guided vehicles

A computer simulation model of an Automatic Storage and Retrieval System (AS/RS) consisting of 5 storage conveyors, 5 retrieval conveyors, 2 bi-directional conveyors, 2 order-picking stations, 7 narrow-aisle cranes and 9,310 storage locations, was created in ARENA^TM version 1.1. Rail-guided vehicles move material to and from the storage racks. The computer simulation model of the AS/RS was used to examine the operational logic of the entire system in order to determine the operational deployment strategy that yields the optimal number of rail-guided vehicles (RGVs), the utilisation of the narrow-aisle crane and also the maximum throughput of the system. This paper reports on the results of running the simulation model. For example, increasing the capacity of the storage and retrieval conveyor from 1 to 2 effectively reduces the number of RGV deadlocks by about 94%. A change of the topology of the RGVs' from 1-zone to 2-zone yielded a slightly better part retrieval time and also a reduction in the optimal number of RGVs from 5 to 4. Under these conditions, the number of storages/retrievals is about 430. The maximum throughput of AS/RS is estimated to be about 33 items per hour. The best retrieval time per part is almost 1205 seconds. As it stands, the system could do with less retrieval stations and narrow-aisle cranes which are under-utilised.     

Encoding a process algebra using the Event B method

This paper presents the use of the B technique in its event based definition. We show that it is possible to encode, using Event B, the models (i.e., transition systems) associated to a process algebra with asynchronous semantics. The obtained Event B models consider that the Event B model associated to the left hand side of a BNF rule defining the algebra expressions is refined by a model corresponding to the right hand side of the same rule. The translation rules of each operator of a basic process algebra are given. Then, an example illustrating each translation rule is given. This approach is based on a proof technique and therefore it does not suffer from the state number explosion problem occurring in classical model checking. The interest of this work is the capability to validate user tasks or scenarios when using a given system and particularly a critical system. Finally, we discuss the application of this approach for validating user interfaces tasks in the human–computer interaction area.     

A simulation model of a sulphuric acid production process as an integrated part of an energy system

Power plant process simulation software is well-suited for the modelling of energy systems and more importantly, tools for analysing the energy efficiency are often built into the software. This work presents the development of a simulation model for a sulphuric acid plant using a commercial software package for power plant process simulation. This will be of value to for instance small consultant and engineering companies involved with audits and analysis of energy systems. For small sized companies the cost of acquiring and maintaining many different specialised software packages will be noticeable. However, companies involved with audits and analysis of energy systems will in most cases have access to at least one software package for power plant process calculations. The use of this kind of software for also modelling chemical plants would be valuable to these companies. The results of this work shows that it is possible to use an inexpensive but powerful power plant process simulation software for modelling a common chemical process as a part of a large energy system.     

面向TSP的软件过程仿真模型

描述了一种面向小组软件过程TSP(Team Software process)的仿真模型,根据TSP的特点,采用将离散和连续建模思想结合的一种混合模型。这种模型分为两层建立,外层体现软件开发过程的阶段性,内层体现软件开发过程的连续性,从两个层次上详细说明模型的结构和原理;给出了模型的形式化描述;并用一个例子来说明模型的执行过程及结果。此模型能够从不同角度模拟软件的开发过程,并能够对软件开发过程进行监督和预测。     

Building an organizational decision support system for Korea Telecom: A process redesign approach

Organizational decision support systems (ODSSs) are a new type of decision support systems (DSSs) focusing on organization-wide issues rather than individual, group, or departmental issues. Because of its organization-wide scope, a typical ODSS cuts across organizational functions or hierarchical layers. Thus, seamless integration with organization's diverse IS applications running on heterogeneous platforms becomes a critical issue for building a successful ODSS. In this paper, we analyzed the Korea Telecom's (KT) Operations > Maintenance (O&M) division focusing on its investment strategies. We developed a conceptual framework through process redesign, which links O&M investment decisions to performance of its operational branches across the nation. To support the above framework, we also developed a prototype for the KTOM-ODSS with an EIS-like user-friendly interface. When a complete ODSS is implemented on top of various KT transaction processing systems, it will become a critical component of the O > M Integrated Decision Support Environment (IDSE).