891 research outputs found
フレキシブル生産セルの性能解析に関する研究
本文データは平成22年度国立国会図書館の学位論文(博士)のデジタル化実施により作成された画像ファイルを基にpdf変換したものである京都大学0048新制・課程博士博士(工学)甲第5117号工博第1238号新制||工||869(附属図書館)UT51-92-J164京都大学大学院工学研究科数理工学専攻(主査)教授 長谷川 利治, 教授 茨木 俊秀, 教授 片山 徹学位規則第4条第1項該当Doctor of EngineeringKyoto UniversityDFA
Just-In-Time in high variety / low volume manufacturing environments.
Available from British Library Document Supply Centre-DSC:DXN049763 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo
An investigation into tooling requirements and strategies for FMS operation
A study of the minimum tooling requirements and strategies for efficient
operation of Flexible Manufacturing Systems, FMS's, in Assembly set
Production, ASP, i.e production in sets of parts to completely assemble one or
more product units, is presented in this research work.
The main investigating tool is a simulation model. With this model the tool
groups to be loaded into machines and fixtured pallet requirements were
studied in conjunction with two scheduling rules. One is a FCFS rule and the
other is a new rule, called MRPAS, which schedules work on the basis of the
number of parts still unfinished belonging to an Assembly Set.
The results of the research work show that ASP can be efficiently carried
out in FMS's. However this requires that a good system set-up and adequate
operating strategies are used. In particular appropriate tooling levels and
good tooling configurations,TC's, i.e. combinations of tools in groups to be
loaded into the machines, must be established to achieve high FMS
performance. Tooling combination and duplication heuristic rules and the
simulation model can be used for achieving this aim. The heuristic approach
is shown to be necessary due to the impossibility, in a reasonable time, of
evaluating the performance of FMS's under the large number of alternative
tooling configurations which are possible.
The level of fixtured pallets used can also have a great influence on system
performance. Appropriate levels of these resources to operate FMS's for
given TC's can be established using the methodology developed in this work.
It is also important that good scheduling rules are used. In the cases studied,
the MRPAS rule produces the best performance expressed as the
combination of FMS utilization and production of complete assembly sets.
Moreover a very small assembly set batch size, ASBS, i.e. number of AS
released together into the FMS, is likely to be preferable. In the cases studied
an ASBS of one performed best overall
Flexible Manufacturing Systems: background examples and models
In this paper, we discuss recent innovations in manufacturing technology and their implications on the design and control of manufacturing systems. Recognizing the need to respond properly to rapidly changing market demands, we discuss several types of flexibility that can be incorporated in our production organisation to achieve this goal. We show how the concept of a Flexible Manufacturing System (FMS) naturally arises as an attempt to combine the advantages of traditional Job Shops and dedicated production lines.The main body of the paper is devoted to a classification of FMS problem areas and a review of models developed to understand and solve these problems. For each problem area, a number of important contributions in the literature is indicated. The reader, interested in the applications of Operations Research models but not familiar with the technical background of FMS’s, will find the descriptions of some essential FMS elements useful. Some final remarks and directions for future research conclude the paper.<br/
Shop-floor scheduling as a competitive advantage:A study on the relevance of cyber-physical systems in different manufacturing contexts
The aim of this paper is to analyse the relevance of cyber-physical systems (CPS) in different manufacturing contexts and to study whether CPS could provide companies with competitive advantage by carrying out a better scheduling task. This paper is developed under the umbrella of contingency theory which states that certain technologies and practices are not universally applicable or relevant in every context; thus, only certain companies will benefit from using particular technologies or practices. The conclusion of this paper, developed through deductive reasoning and supported by preliminary simulation experiments and statistical tests, is that factories with an uncertain and demanding market environment as well as a complex production process could benefit the most from implementing a CPS at shop-floor level since a cyber-physical shop-floor will provide all the capabilities needed to carry out the complex scheduling task associated with this type of context. On the other hand, an increase in scheduling performance due to a CPS implementation in factories with simple production flows and stable demand could not be substantial enough to overcome the high cost of installing a fully operational CPS
Enabling flexibility through strategic management of complex engineering systems
”Flexibility is a highly desired attribute of many systems operating in changing or uncertain conditions. It is a common theme in complex systems to identify where flexibility is generated within a system and how to model the processes needed to maintain and sustain flexibility. The key research question that is addressed is: how do we create a new definition of workforce flexibility within a human-technology-artificial intelligence environment?
Workforce flexibility is the management of organizational labor capacities and capabilities in operational environments using a broad and diffuse set of tools and approaches to mitigate system imbalances caused by uncertainties or changes. We establish a baseline reference for managers to use in choosing flexibility methods for specific applications and we determine the scope and effectiveness of these traditional flexibility methods.
The unique contributions of this research are: a) a new definition of workforce flexibility for a human-technology work environment versus traditional definitions; b) using a system of systems (SoS) approach to create and sustain that flexibility; and c) applying a coordinating strategy for optimal workforce flexibility within the human- technology framework. This dissertation research fills the gap of how we can model flexibility using SoS engineering to show where flexibility emerges and what strategies a manager can use to manage flexibility within this technology construct”--Abstract, page iii
Evolutionary methods for the design of dispatching rules for complex and dynamic scheduling problems
Three methods, based on Evolutionary Algorithms (EAs), to support and automate the design
of dispatching rules for complex and dynamic scheduling problems are proposed in this thesis.
The first method employs an EA to search for problem instances on which a given dispatching
rule performs badly. These instances can then be analysed to reveal weaknesses of the
tested rule, thereby providing guidelines for the design of a better rule. The other two methods
are hyper-heuristics, which employ an EA directly to generate effective dispatching rules. In
particular, one hyper-heuristic is based on a specific type of EA, called Genetic Programming
(GP), and generates a single rule from basic job and machine attributes, while the other generates
a set of work centre-specific rules by selecting a (potentially) different rule for each
work centre from a number of existing rules. Each of the three methods is applied to some
complex and dynamic scheduling problem(s), and the resulting dispatching rules are tested
against benchmark rules from the literature. In each case, the benchmark rules are shown to be
outperformed by a rule (set) that results from the application of the respective method, which
demonstrates the effectiveness of the proposed methods
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