814 resultados para Calculus of operations.
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This dissertation studies the process of operations systems design within the context of the manufacturing organization. Using the DRAMA (Design Routine for Adopting Modular Assembly) model as developed by a team from the IDOM Research Unit at Aston University as a starting point, the research employed empirically based fieldwork and a survey to investigate the process of production systems design and implementation within four UK manufacturing industries: electronics assembly, electrical engineering, mechanical engineering and carpet manufacturing. The intention was to validate the basic DRAMA model as a framework for research enquiry within the electronics industry, where the initial IDOM work was conducted, and then to test its generic applicability, further developing the model where appropriate, within the other industries selected. The thesis contains a review of production systems design theory and practice prior to presenting thirteen industrial case studies of production systems design from the four industry sectors. The results and analysis of the postal survey into production systems design are then presented. The strategic decisions of manufacturing and their relationship to production systems design, and the detailed process of production systems design and operation are then discussed. These analyses are used to develop the generic model of production systems design entitled DRAMA II (Decision Rules for Analysing Manufacturing Activities). The model contains three main constituent parts: the basic DRAMA model, the extended DRAMA II model showing the imperatives and relationships within the design process, and a benchmark generic approach for the design and analysis of each component in the design process. DRAMA II is primarily intended for use by researchers as an analytical framework of enquiry, but is also seen as having application for manufacturing practitioners.
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This study is concerned with labour productivity in traditional house building in Scotland. Productivity is a measure of the effective use of resources and provides vital benefits that can be combined in a number of ways. The introduction gives the background to two Scottish house building sites (Blantyre and Greenfield) that were surveyed by the Building Research Establishment (BEE) activity sampling method to provide the data for the study. The study had two main objectives; (1) summary data analysis in average manhours per house between all the houses on the site, and (2) detailed data analysis in average manhours for each house block on the site. The introduction also provides a literature review related to the objectives. The method is outlined in Chapter 2, the sites are discussed in Chapter 3, and Chapter 4 covers the method application on each site and a method development made in the study. The summary data analysis (Chapter 5) compares Blantyre and Greenfield, and two previous BEE surveys in England. The main detailed data analysis consisted of three forms, (Chapters 6, 7 and 8) each applied to a set of operations. The three forms of analysis were variations in average manhours per house for each house block on the site compared with; (1) block construction order, (2) average number of separate visits per house made by operatives to each block to complete an operation, and (3) average number of different operatives per house employed on an operation in each block. Three miscellaneous items of detail data analysis are discussed in Chapter 9. The conclusions to the whole study state that considerable variations in manhours for repeated operations were discovered, that the numbers of visits by operatives to complete operations were large and that the numbers of different operatives employed in some operations were a factor related to productivity. A critique of the activity sampling method suggests that the data produced is reliable in summary form and can give a good context for more detailed data collection. For future work, this could take the form of selected operations, with the context of an activity sampling survey, that wuld be intensively surveyed by other methods.
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Analysis of the use of ICT in the aerospace industry has prompted the detailed investigation of an inventory-planning problem. There is a special class of inventory, consisting of expensive repairable spares for use in support of aircraft operations. These items, called rotables, are not well served by conventional theory and systems for inventory management. The context of the problem, the aircraft maintenance industry sector, is described in order to convey some of its special characteristics in the context of operations management. A literature review is carried out to seek existing theory that can be applied to rotable inventory and to identify a potential gap into which newly developed theory could contribute. Current techniques for rotable planning are identified in industry and the literature: these methods are modelled and tested using inventory and operational data obtained in the field. In the expectation that current practice leaves much scope for improvement, several new models are proposed. These are developed and tested on the field data for comparison with current practice. The new models are revised following testing to give improved versions. The best model developed and tested here comprises a linear programming optimisation, which finds an optimal level of inventory for multiple test cases, reflecting changing operating conditions. The new model offers an inventory plan that is up to 40% less expensive than that determined by current practice, while maintaining required performance.
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This paper outlines, using evidence from several case studies, the use of alternative forms of manufacturing strategy processes. Our investigation shows that the manufacturing strategy development practices of manufacturers are evolving in many directions; we found several alternatives to the formal top-down planning process. Manufacturers use one or more of the following alternatives with or without the top-down manufacturing strategy process: a coherent pattern of actions; manufacturing/process improvement programs; or the pursuit of core manufacturing capabilities. It appears that the various manufacturing strategy development processes may be tied to the strategic role of manufacturing in a company. This paper offers a framework that captures the relationship between the strategic role of manufacturing and the process of manufacturing strategy development. An in-depth case from a UK company illustrates the evolving forms of manufacturing strategy development processes.
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According to researchers and managers, there is a lack of agreement between marketing and manufacturing managers on critical strategic issues. However, most of the literature on the subject is anecdotal and little formal empirical research has been done. Three companies are investigated to study the extent of agreement/disagreement between manufacturing and marketing managers on strategy content and process. A novel method permits the study of agreement between the two different functional managers on the process of developing strategy. The findings consistently show that manufacturing managers operate under a wider range of strategic priorities than marketing managers, and that manufacturing managers participate less than marketing managers in the strategy development process. Further, both marketing and manufacturing managers show higher involvement in the strategy development process in the latter stages of the Hayes and Wheelwright four-stage model of manufacturing’s strategic role.
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Purpose: The purpose of this paper is to focus on investigating and benchmarking green operations initiatives in the automotive industry documented in the environmental reports of selected companies. The investigation roadmaps the main environmental initiatives taken by the world's three major car manufacturers and benchmarks them against each other. The categorisation of green operations initiatives that is provided in the paper can also help companies in other sectors to evaluate their green practices. Design/methodology/approach: The first part of the paper is based on existing literature on the topic of green and sustainable operations and the "unsustainable" context of automotive production. The second part relates to the roadmap and benchmarking of green operations initiatives based on an analysis of secondary data from the automotive industry. Findings: The findings show that the world's three major car manufacturers are pursuing various environmental initiatives involving the following green operations practices: green buildings, eco-design, green supply chains, green manufacturing, reverse logistics and innovation. Research limitations/implications: The limitations of this paper start from its selection of the companies, which was made using production volume and country of origin as the principal criteria. There is ample evidence that other, smaller, companies are pursuing more sophisticated and original environmental initiatives. Also, there might be a gap between what companies say they do in their environmental reports and what they actually do. Practical implications: This paper helps practitioners in the automotive industry to benchmark themselves against the major volume manufacturers in three different continents. Practitioners from other industries will also find it valuable to discover how the automotive industry is pursuing environmental initiatives beyond manufacturing, apart from the green operations practices covering broadly all the activities of operations function. Originality/value: The originality of the paper is in its up-to-date analysis of environmental reports of automotive companies. The paper offers value for researchers and practitioners due to its contribution to the green operations literature. For instance, the inclusion of green buildings as part of green operations practices has so far been neglected by most researchers and authors in the field of green and sustainable operations. © Emerald Group Publishing Limited.
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A view has emerged within manufacturing and service organizations that the operations management function can hold the key to achieving competitive edge. This has recently been emphasized by the demands for greater variety and higher quality which must be set against a background of increasing cost of resources. As nations' trade barriers are progressively lowered and removed, so producers of goods and service products are becoming more exposed to competition that may come from virtually anywhere around the world. To simply survive in this climate many organizations have found it necessary to improve their manufacturing or service delivery systems. To become real ''winners'' some have adopted a strategic approach to operations and completely reviewed and restructured their approach to production system design and operations planning and control. The articles in this issue of the International journal of Operations & Production Management have been selected to illustrate current thinking and practice in relation to this situation. They are all based on papers presented to the Sixth International Conference of the Operations Management Association-UK which was held at Aston University in June 1991. The theme of the conference was "Achieving Competitive Edge" and authors from 15 countries around the world contributed to more than 80 presented papers. Within this special issue five topic areas are addressed with two articles relating to each. The topics are: strategic management of operations; managing change; production system design; production control; and service operations. Under strategic management of operations De Toni, Filippini and Forza propose a conceptual model which considers the performance of an operating system as a source of competitive advantage through the ''operation value chain'' of design, purchasing, production and distribution. Their model is set within the context of the tendency towards globalization. New's article is somewhat in contrast to the more fashionable literature on operations strategy. It challenges the validity of the current idea of ''world-class manufacturing'' and, instead, urges a reconsideration of the view that strategic ''trade-offs'' are necessary to achieve a competitive edge. The importance of managing change has for some time been recognized within the field of organization studies but its relevance in operations management is now being realized. Berger considers the use of "organization design", ''sociotechnical systems'' and change strategies and contrasts these with the more recent idea of the ''dialogue perspective''. A tentative model is suggested to improve the analysis of different strategies in a situation specific context. Neely and Wilson look at an essential prerequisite if change is to be effected in an efficient way, namely product goal congruence. Using a case study as its basis, their article suggests a method of measuring goal congruence as a means of identifying the extent to which key performance criteria relating to quality, time, cost and flexibility are understood within an organization. The two articles on production systems design represent important contributions to the debate on flexible production organization and autonomous group working. Rosander uses the results from cases to test the applicability of ''flow groups'' as the optimal way of organizing batch production. Schuring also examines cases to determine the reasons behind the adoption of ''autonomous work groups'' in The Netherlands and Sweden. Both these contributions help to provide a greater understanding of the production philosophies which have emerged as alternatives to more conventional systems -------for intermittent and continuous production. The production control articles are both concerned with the concepts of ''push'' and ''pull'' which are the two broad approaches to material planning and control. Hirakawa, Hoshino and Katayama have developed a hybrid model, suitable for multistage manufacturing processes, which combines the benefits of both systems. They discuss the theoretical arguments in support of the system and illustrate its performance with numerical studies. Slack and Correa's concern is with the flexibility characteristics of push and pull material planning and control systems. They use the case of two plants using the different systems to compare their performance within a number of predefined flexibility types. The two final contributions on service operations are complementary. The article by Voss really relates to manufacturing but examines the application of service industry concepts within the UK manufacturing sector. His studies in a number of companies support the idea of the ''service factory'' and offer a new perspective for manufacturing. Harvey's contribution by contrast, is concerned with the application of operations management principles in the delivery of professional services. Using the case of social-service provision in Canada, it demonstrates how concepts such as ''just-in-time'' can be used to improve service performance. The ten articles in this special issue of the journal address a wide range of issues and situations. Their common aspect is that, together, they demonstrate the extent to which competitiveness can be improved via the application of operations management concepts and techniques.
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Links the concept of market-driven business strategies with the design of production systems. It draws upon the case of a firm which, during the last decade, changed its strategy from being “technology led” to “market driven”. The research, based on interdisciplinary fieldwork involving long-term participant observation, investigated the factors which contribute to the successful design and implementation of flexible production systems in electronics assembly. These investigations were conducted in collaboration with a major computer manufacturer, with other electronics firms being studied for comparison. The research identified a number of strategies and actions seen as crucial to the development of efficient flexible production systems, namely: effective integration of subsystems, development of appropriate controls and performance measures, compatibility between production system design and organization structure, and the development of a climate conducive to organizational change. Overall, the analysis suggests that in the electronics industry there exists an extremely high degree of environmental complexity and turbulence. This serves to shape the strategic, technical and social structures that are developed to match this complexity, examples of which are niche marketing, flexible manufacturing and employee harmonization.
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Information technology companies are having to broaden their overall strategic view in deference to the premise that it is better to be market-driven than technology-led. Cost and technical performance are no longer the only considerations, as quality and service now demand equal recognition. The production of a high volume single item has given way to that of low volume multiple items, which in turn requires some modification of production systems and brings flexible manufacturing, Just-in-Time production and total quality control into sharper focus for the achievement of corporate objectives.
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Guest editorial Ali Emrouznejad is a Senior Lecturer at the Aston Business School in Birmingham, UK. His areas of research interest include performance measurement and management, efficiency and productivity analysis as well as data mining. He has published widely in various international journals. He is an Associate Editor of IMA Journal of Management Mathematics and Guest Editor to several special issues of journals including Journal of Operational Research Society, Annals of Operations Research, Journal of Medical Systems, and International Journal of Energy Management Sector. He is in the editorial board of several international journals and co-founder of Performance Improvement Management Software. William Ho is a Senior Lecturer at the Aston University Business School. Before joining Aston in 2005, he had worked as a Research Associate in the Department of Industrial and Systems Engineering at the Hong Kong Polytechnic University. His research interests include supply chain management, production and operations management, and operations research. He has published extensively in various international journals like Computers & Operations Research, Engineering Applications of Artificial Intelligence, European Journal of Operational Research, Expert Systems with Applications, International Journal of Production Economics, International Journal of Production Research, Supply Chain Management: An International Journal, and so on. His first authored book was published in 2006. He is an Editorial Board member of the International Journal of Advanced Manufacturing Technology and an Associate Editor of the OR Insight Journal. Currently, he is a Scholar of the Advanced Institute of Management Research. Uses of frontier efficiency methodologies and multi-criteria decision making for performance measurement in the energy sector This special issue aims to focus on holistic, applied research on performance measurement in energy sector management and for publication of relevant applied research to bridge the gap between industry and academia. After a rigorous refereeing process, seven papers were included in this special issue. The volume opens with five data envelopment analysis (DEA)-based papers. Wu et al. apply the DEA-based Malmquist index to evaluate the changes in relative efficiency and the total factor productivity of coal-fired electricity generation of 30 Chinese administrative regions from 1999 to 2007. Factors considered in the model include fuel consumption, labor, capital, sulphur dioxide emissions, and electricity generated. The authors reveal that the east provinces were relatively and technically more efficient, whereas the west provinces had the highest growth rate in the period studied. Ioannis E. Tsolas applies the DEA approach to assess the performance of Greek fossil fuel-fired power stations taking undesirable outputs into consideration, such as carbon dioxide and sulphur dioxide emissions. In addition, the bootstrapping approach is deployed to address the uncertainty surrounding DEA point estimates, and provide bias-corrected estimations and confidence intervals for the point estimates. The author revealed from the sample that the non-lignite-fired stations are on an average more efficient than the lignite-fired stations. Maethee Mekaroonreung and Andrew L. Johnson compare the relative performance of three DEA-based measures, which estimate production frontiers and evaluate the relative efficiency of 113 US petroleum refineries while considering undesirable outputs. Three inputs (capital, energy consumption, and crude oil consumption), two desirable outputs (gasoline and distillate generation), and an undesirable output (toxic release) are considered in the DEA models. The authors discover that refineries in the Rocky Mountain region performed the best, and about 60 percent of oil refineries in the sample could improve their efficiencies further. H. Omrani, A. Azadeh, S. F. Ghaderi, and S. Abdollahzadeh presented an integrated approach, combining DEA, corrected ordinary least squares (COLS), and principal component analysis (PCA) methods, to calculate the relative efficiency scores of 26 Iranian electricity distribution units from 2003 to 2006. Specifically, both DEA and COLS are used to check three internal consistency conditions, whereas PCA is used to verify and validate the final ranking results of either DEA (consistency) or DEA-COLS (non-consistency). Three inputs (network length, transformer capacity, and number of employees) and two outputs (number of customers and total electricity sales) are considered in the model. Virendra Ajodhia applied three DEA-based models to evaluate the relative performance of 20 electricity distribution firms from the UK and the Netherlands. The first model is a traditional DEA model for analyzing cost-only efficiency. The second model includes (inverse) quality by modelling total customer minutes lost as an input data. The third model is based on the idea of using total social costs, including the firm’s private costs and the interruption costs incurred by consumers, as an input. Both energy-delivered and number of consumers are treated as the outputs in the models. After five DEA papers, Stelios Grafakos, Alexandros Flamos, Vlasis Oikonomou, and D. Zevgolis presented a multiple criteria analysis weighting approach to evaluate the energy and climate policy. The proposed approach is akin to the analytic hierarchy process, which consists of pairwise comparisons, consistency verification, and criteria prioritization. In the approach, stakeholders and experts in the energy policy field are incorporated in the evaluation process by providing an interactive mean with verbal, numerical, and visual representation of their preferences. A total of 14 evaluation criteria were considered and classified into four objectives, such as climate change mitigation, energy effectiveness, socioeconomic, and competitiveness and technology. Finally, Borge Hess applied the stochastic frontier analysis approach to analyze the impact of various business strategies, including acquisition, holding structures, and joint ventures, on a firm’s efficiency within a sample of 47 natural gas transmission pipelines in the USA from 1996 to 2005. The author finds that there were no significant changes in the firm’s efficiency by an acquisition, and there is a weak evidence for efficiency improvements caused by the new shareholder. Besides, the author discovers that parent companies appear not to influence a subsidiary’s efficiency positively. In addition, the analysis shows a negative impact of a joint venture on technical efficiency of the pipeline company. To conclude, we are grateful to all the authors for their contribution, and all the reviewers for their constructive comments, which made this special issue possible. We hope that this issue would contribute significantly to performance improvement of the energy sector.
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Operations Management, 3rd Edition provides a clear and accessible introduction to this important area of study, focusing on all key areas of operations in both manufacturing and service industries. Features: Focuses on the subject from a European perspective. Deals with the management of the creation of goods and the delivery of services to the customer. Covers the main areas of operations strategy, the design of operations system and the management of operations over time. Incorporates more strategic and international commentary. Includes a strategy link section consisting of a paragraph relating each chapter topic to operations strategy. Includes more end of chapter and quantitative exercises. Cases have been updated throughout and now include: Service including public sector, international, a mix of mini–cases and a longer case for each chapter. Accompanied by a comprehensive package of online learning support materials including: A robust testbank featuring 1500 questions, PowerPoint slides and a comprehensive instructor's manual An interactive e–Book is included with every new copy of this text, featuring a wealth of embedded media, including: Animated worked examples, simulations, virtual tours, videos, flashcards and practice quizzes.
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Purpose: The servitization of manufacturing is a diverse and complex field of research interest. The purpose of this paper is to provide an integrative and organising lens for viewing the various contributions to knowledge production from those research communities addressing servitization. To achieve this, the paper aims to set out to address two principal questions, namely where are the knowledge stocks and flows amongst the research communities? And what are generic research concerns being addressed by these communities? Design/methodology/approach: Using an evidenced-based approach, the authors have performed a systematic review of the research literature associated with the servitization of manufacturing. This investigation incorporates a descriptive and thematic analysis of 148 academic and scholarly papers from 103 different lead authors in 68 international peer-reviewed journals. Findings: The work proposes support for the existence of distinct researcher communities, namely services marketing, service management, operations management, product-service systems and service science management and engineering, which are contributing to knowledge production in the servitization of manufacturing. Knowledge stocks within all communities associated with research in the servitization of manufacturing have dramatically increased since the mid-1990s. The trends clearly reveal that the operations community is in receipt of the majority of citations relating to the servitization of manufacturing. In terms of knowledge flows, it is apparent that the more mature communities are drawing on more locally produced knowledge stocks, whereas the emergent communities are drawing on a knowledge base more evenly distributed across all the communities. The results are indicative of varying degrees of interdependency amongst the communities. The generic research concerns being addressed within the communities are associated with the concepts of product-service differentiation, competitive strategy, customer value, customer relationships and product-service configuration. Originality/value: This research has further developed and articulated the identities of distinct researcher communities actively contributing to knowledge production in the servitization of manufacturing, and to what extent they are pursuing common research agendas. This study provides an improved descriptive and thematic awareness of the resulting body of knowledge, allowing the field of servitization to progress in a more informed and multidisciplinary fashion. © Emerald Group Publishing Limited.
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The internet's potential impact on supply chain operations is often approached in the literature in a quite generic way due to the complex nature of supply chains and the different levels of operations' integration. Drawing on existing research, this paper proposes an overall framework of supply chain integration and then attempts to provide a categorisation of the internet's role in the supply chain activities, providing insights from various sectors. The purpose of this paper is to describe and present the alternative ways that the internet impacts on the integration of supply chain operations, by comparing four different sectors: the automotive, the computer, the food and the grocery sector. The paper concludes that in the food, grocery and computer sector, internet's impact on supply chain operations has been quite poor, particularly forward integration, while it has been significant, in the backward integration of the automotive sector. Copyright © 2007 Inderscience Enterprises Ltd.
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Purpose – The purpose of this paper is to investigate an underexplored aspect of outsourcing involving a mixed strategy in which parallel production is continued in-house at the same time as outsourcing occurs. Design/methodology/approach – The study applied a multiple case study approach and drew on qualitative data collected through in-depth interviews with wood product manufacturing companies. Findings – The paper posits that there should be a variety of mixed strategies between the two governance forms of “make” or “buy.” In order to address how companies should consider the extent to which they outsource, the analysis was structured around two ends of a continuum: in-house dominance or outsourcing dominance. With an in-house-dominant strategy, outsourcing complements an organization's own production to optimize capacity utilization and outsource less cost-efficient production, or is used as a tool to learn how to outsource. With an outsourcing-dominant strategy, in-house production helps maintain complementary competencies and avoids lock-in risk. Research limitations/implications – This paper takes initial steps toward an exploration of different mixed strategies. Additional research is required to understand the costs of different mixed strategies compared with insourcing and outsourcing, and to study parallel production from a supplier viewpoint. Practical implications – This paper suggests that managers should think twice before rushing to a “me too” outsourcing strategy in which in-house capacities are completely closed. It is important to take a dynamic view of outsourcing that maintains a mixed strategy as an option, particularly in situations that involve an underdeveloped supplier market and/or as a way to develop resources over the long term. Originality/value – The concept of combining both “make” and “buy” is not new. However, little if any research has focussed explicitly on exploring the variety of different types of mixed strategies that exist on the continuum between insourcing and outsourcing.
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A hard combinatorial problem is investigated which has useful application in design of discrete devices: the two-block decomposition of a partial Boolean function. The key task is regarded: finding such a weak partition on the set of arguments, at which the considered function can be decomposed. Solving that task is essentially speeded up by the way of preliminary discovering traces of the sought-for partition. Efficient combinatorial operations are used by that, based on parallel execution of operations above adjacent units in the Boolean space.