9,416 research outputs found

    AI and OR in management of operations: history and trends

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    The last decade has seen a considerable growth in the use of Artificial Intelligence (AI) for operations management with the aim of finding solutions to problems that are increasing in complexity and scale. This paper begins by setting the context for the survey through a historical perspective of OR and AI. An extensive survey of applications of AI techniques for operations management, covering a total of over 1200 papers published from 1995 to 2004 is then presented. The survey utilizes Elsevier's ScienceDirect database as a source. Hence, the survey may not cover all the relevant journals but includes a sufficiently wide range of publications to make it representative of the research in the field. The papers are categorized into four areas of operations management: (a) design, (b) scheduling, (c) process planning and control and (d) quality, maintenance and fault diagnosis. Each of the four areas is categorized in terms of the AI techniques used: genetic algorithms, case-based reasoning, knowledge-based systems, fuzzy logic and hybrid techniques. The trends over the last decade are identified, discussed with respect to expected trends and directions for future work suggested

    Risk of employing an evolvable production system

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    Nowadays manufacturing companies are facing a more challenging environment due to the unpredictability of the markets in order to survive. Enterprises need to keep innovating and deliver products with new internal or external characteristics. There are strategies and solutions, to different organisational level from strategic to operational, when technology is growing faster in operational level, more specifically in manufacturing system. This means that companies have to deal with the changes of the emergent manufacturing systems while it can be expensive and not easy to be implement. An agile manufacturing system can help to cope with the markets changeability. Evolvable Production Systems (EPS) is an emergent paradigm which aims to bring new solutions to deal with changeability. The proposed paradigm is characterised by modularity and intends to introduce high flexibility and dynamism at shop floor level through the use of the evolution of new computational devices and technology. This new approach brings to enterprises the ability to plug and unplug new devices and allowing fast reformulation of the production line without reprogramming. There is no doubt about the advantages and benefits of this emerging technology but the feasibility and applicability is still under questioned. Most researches in this area are focused on technical side, explaining the advantages of those systems while there are no sufficient works discussing the implementation risks from different perspective, including business owner. The main objective of this work is to propose a methodology and model to identify, classify and measure potential risk associated with an implementation of this emergent paradigm. To quantify the proposed comprehensive risk model, an Intelligent Decision system is developed employing Fuzzy Inference System to deal with the knowledge of experts, as there are no historical data and sufficient research on this area. The result can be the vulnerability assessment of implementing EPS technology in manufacturing companies when the focus is more on SMEs. The present dissertation used the experts’ knowledge and experiences, who were involved in FP7 project IDEAS, which is one of the leading projects in this area

    Research on key techniques of flexible workflow based approach to supporting dynamic engineering design process

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    Error on title page - correct year of award is 2015 not 2013.Engineering design process (EDP) is a highly dynamic and creative process, and the capability in managing an EDP is considered as a major differentiating factor between competing enterprises. The most important prerequisite to establish an engineering design process excellence is a proper management of all the design process activities and the associated information. The most important impact in recent years on the EDP and on the activities of designers has come from computer-based data processing. Workflow, the automation of a business processes in whole or part, is a useful tool for modelling and managing a business process which can be reprensented by a workflow model (computerized process definition). By considering the dynamic characteristics of EDP, an EDP management system must be flexible enough to support the creative and dynamic EDP. After the introduction of engineering design process and its new trend, as well as flexible workflow technology, reviews of both engineering design process and its supporting flexible workflow technology shows that there is a need for a holistic framework to automate and coordinate design activities in the creative and dynamic EDP, and the flexible workflow technology should also be improved comprehensively in flexibility and intelligence in order to support better engineering design management. By introducing the relations between the EDP and flexible workflow, a virtual workflow and an autonomic flexible workflow built upon autonomic computing is investigated, and an innovative engineering design process management framework based on multi-autonomic objects flexible workflow is proposed. For the flexible workflow modelling in the framework, a dynamic instance-based flexible workflow modelling method is proposed for multi-autonomic objects flexible workflow. In order to improve the intelligence of flexible workflow, after examining the principle of flexible workflow intelligence in flexible workflow, a new flexible workflow autonomic object intelligence algorithm based on both extended Mamdani fuzzy reasoning and neural network is proposed, weighted fuzzy reasoning algorithm, as well as precise and fuzzy hybrid knowledge reasoning algorithm is designed; a bionic flexible workflow adaptation algorithm is proposed to improve the intelligence of autonomic object flexible workflow further. According to the characteristic of EDP, such as cross-enterprises and geographical distribution, and in order to realize the flexible execution of distributed flexible workflow engine, a distributed flexible workflow engine architecture based on web service is proposed and a flexible workflow model description method based on extended WSDL (Web Service Description Language) and BPEL4WS (Business Process Execution Language for Web Services) is proposed. A flexible workflow prototype system supporting engineering design process is implemented according to the proposed EDP management framework in Microsoft VS.Net 2005 environment. The framework is demonstrated by the application in an EDP of a MTO company, and it shows that the proposed framework can support the creative and dynamic process in an efficient way. Finally, the strengths and weakness of the framework as well as the prototype system is discussed based on the results of the evaluation, and the proposed areas of future work are given.Engineering design process (EDP) is a highly dynamic and creative process, and the capability in managing an EDP is considered as a major differentiating factor between competing enterprises. The most important prerequisite to establish an engineering design process excellence is a proper management of all the design process activities and the associated information. The most important impact in recent years on the EDP and on the activities of designers has come from computer-based data processing. Workflow, the automation of a business processes in whole or part, is a useful tool for modelling and managing a business process which can be reprensented by a workflow model (computerized process definition). By considering the dynamic characteristics of EDP, an EDP management system must be flexible enough to support the creative and dynamic EDP. After the introduction of engineering design process and its new trend, as well as flexible workflow technology, reviews of both engineering design process and its supporting flexible workflow technology shows that there is a need for a holistic framework to automate and coordinate design activities in the creative and dynamic EDP, and the flexible workflow technology should also be improved comprehensively in flexibility and intelligence in order to support better engineering design management. By introducing the relations between the EDP and flexible workflow, a virtual workflow and an autonomic flexible workflow built upon autonomic computing is investigated, and an innovative engineering design process management framework based on multi-autonomic objects flexible workflow is proposed. For the flexible workflow modelling in the framework, a dynamic instance-based flexible workflow modelling method is proposed for multi-autonomic objects flexible workflow. In order to improve the intelligence of flexible workflow, after examining the principle of flexible workflow intelligence in flexible workflow, a new flexible workflow autonomic object intelligence algorithm based on both extended Mamdani fuzzy reasoning and neural network is proposed, weighted fuzzy reasoning algorithm, as well as precise and fuzzy hybrid knowledge reasoning algorithm is designed; a bionic flexible workflow adaptation algorithm is proposed to improve the intelligence of autonomic object flexible workflow further. According to the characteristic of EDP, such as cross-enterprises and geographical distribution, and in order to realize the flexible execution of distributed flexible workflow engine, a distributed flexible workflow engine architecture based on web service is proposed and a flexible workflow model description method based on extended WSDL (Web Service Description Language) and BPEL4WS (Business Process Execution Language for Web Services) is proposed. A flexible workflow prototype system supporting engineering design process is implemented according to the proposed EDP management framework in Microsoft VS.Net 2005 environment. The framework is demonstrated by the application in an EDP of a MTO company, and it shows that the proposed framework can support the creative and dynamic process in an efficient way. Finally, the strengths and weakness of the framework as well as the prototype system is discussed based on the results of the evaluation, and the proposed areas of future work are given

    Reliability assessment of manufacturing systems: A comprehensive overview, challenges and opportunities

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    Reliability assessment refers to the process of evaluating reliability of components or systems during their lifespan or prior to their implementation. In the manufacturing industry, the reliability of systems is directly linked to production efficiency, product quality, energy consumption, and other crucial performance indicators. Therefore, reliability plays a critical role in every aspect of manufacturing. In this review, we provide a comprehensive overview of the most significant advancements and trends in the assessment of manufacturing system reliability. For this, we also consider the three main facets of reliability analysis of cyber–physical systems, i.e., hardware, software, and human-related reliability. Beyond the overview of literature, we derive challenges and opportunities for reliability assessment of manufacturing systems based on the reviewed literature. Identified challenges encompass aspects like failure data availability and quality, fast-paced technological advancements, and the increasing complexity of manufacturing systems. In turn, the opportunities include the potential for integrating various assessment methods, and leveraging data to automate the assessment process and to increase accuracy of derived reliability models

    An intelligent knowledge based cost modelling system for innovative product development

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    This research work aims to develop an intelligent knowledge-based system for product cost modelling and design for automation at an early design stage of the product development cycle, that would enable designers/manufacturing planners to make more accurate estimates of the product cost. Consequently, a quicker response to customers’ expectations. The main objectives of the research are to: (1) develop a prototype system that assists an inexperienced designer to estimate the manufacturing cost of the product, (2) advise designers on how to eliminate design and manufacturing related conflicts that may arise during the product development process, (3) recommend the most economic assembly technique for the product in order to consider this technique during the design process and provide design improvement suggestions to simplify the assembly operations (i.e. to provide an opportunity for designers to design for assembly (DFA)), (4) apply a fuzzy logic approach to certain cases, and (5) evaluate the developed prototype system through five case studies. The developed system for cost modelling comprises of a CAD solid modelling system, a material selection module, knowledge-based system (KBS), process optimisation module, design for assembly module, cost estimation technique module, and a user interface. In addition, the system encompasses two types of databases, permanent (static) and temporary (dynamic). These databases are categorised into five separate groups of database, Feature database, Material database, Machinability database, Machine database, and Mould database. The system development process has passed through four major steps: firstly, constructing the knowledge-based and process optimisation system, secondly developing a design for assembly module. Thirdly, integrating the KBS with both material selection database and a CAD system. Finally, developing and implementing a ii fuzzy logic approach to generate reliable estimation of cost and to handle the uncertainty in cost estimation model that cannot be addressed by traditional analytical methods. The developed system has, besides estimating the total cost of a product, the capability to: (1) select a material as well as the machining processes, their sequence and machining parameters based on a set of design and production parameters that the user provides to the system, and (2) recommend the most economic assembly technique for a product and provide design improvement suggestion, in the early stages of the design process, based on a design feasibility technique. It provides recommendations when a design cannot be manufactured with the available manufacturing resources and capabilities. In addition, a feature-by-feature cost estimation report was generated using the system to highlight the features of high manufacturing cost. The system can be applied without the need for detailed design information, so that it can be implemented at an early design stage and consequently cost redesign, and longer lead-time can be avoided. One of the tangible advantages of this system is that it warns users of features that are costly and difficult to manufacture. In addition, the system is developed in such a way that, users can modify the product design at any stage of the design processes. This research dealt with cost modelling of both machined components and injection moulded components. The developed cost effective design environment was evaluated on real products, including a scientific calculator, a telephone handset, and two machined components. Conclusions drawn from the system indicated that the developed prototype system could help companies reducing product cost and lead time by estimating the total product cost throughout the entire product development cycle including assembly cost. Case studies demonstrated that designing a product using the developed system is more cost effective than using traditional systems. The cost estimated for a number of products used in the case studies was almost 10 to 15% less than cost estimated by the traditional system since the latter does not take into consideration process optimisation, design alternatives, nor design for assembly issue

    Hierarchical Control of Production Flow based on Capacity Allocation for Real-Time Scheduling of Manufacturing System

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    8International audienceThis paper considers the modelling and simulation of a hierarchical production-flow control system. It uses a continuous control approach for machine capacity allocation at the design level and real time scheduling at the shop-floor level. Particularly, at the design level, the control of machine throughput has been addressed by a set of distributed and supervised fuzzy controllers. The objective is to adjust the machine's production rates in such a way that satisfies the demand while maintaining the overall performances within acceptable limits. At the shop-floor level, the problem of scheduling of jobs is considered. In this case, the priority of jobs (actual dispatching times) is determined from the continuous production rates through a discretization procedure. A case study demonstrates the efficiency of the proposed methodology through a simulation case study
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