31 resultados para lean implementation time

em Aston University Research Archive


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Purpose - Despite many Maintenance Repair and Overhaul (MRO) organisations alluding their positive business performances to the adoption Lean initiatives, there is a paucity of direct literature that validates this assertion. Thus, the purpose of this paper is to study empirically via the use of an industry-wide survey to establish and extent of Lean adoption and to verify its suitability in mitigating prevalent MRO challenges. Design/methodology/approach - The empirical study contained in this paper is facilitated by an industry-wide survey to collect data from several firms across the MRO spectrum. The analysed responses from industry leaders, professionals and executives synthesised with existing literature was used in ascertaining the extent of Lean adoption within the operational framework of the industry. Findings - The empirical study helped in validating the suitability of Lean in MRO context. However, it was also observed that the focus of its application was skewed towards its production-orientated functions more than its service-orientated functions. Nonetheless, this paper presents results of the positive influence of Lean in MRO context. Research limitations/implications - This empirical study presented in this paper was carried out within a framework of key characteristics of operation. Although this approach is sufficient in assessing the industry's Lean status, further assessment can also be achieved within the context of relevant performance metrics which was not included in this paper. Practical implications - By exploring the industry's Lean status within the context of operational characteristics of operation, this study provides MRO practitioners with more awareness into some of the critical factors required for successful holistic Lean realisation. Social implications - The state-of-the-art of Lean within the aviation MRO context established through this research also contributes to the wider product-centric service environment by providing a platform that facilitates strategy development which ensures Lean success within this environment. Originality/value - Apart from validating the suitability of Lean in MRO contexts, by establishing the extent of Lean adoption within the context of the operational framework, this paper provides a clearer insight as to how successful Lean implementation can be achieved via a holistic implementation strategy balanced between the product-centric and service-centric aspects of the industry.

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This paper presents results from the first use of neural networks for the real-time feedback control of high temperature plasmas in a Tokamak fusion experiment. The Tokamak is currently the principal experimental device for research into the magnetic confinement approach to controlled fusion. In the Tokamak, hydrogen plasmas, at temperatures of up to 100 Million K, are confined by strong magnetic fields. Accurate control of the position and shape of the plasma boundary requires real-time feedback control of the magnetic field structure on a time-scale of a few tens of microseconds. Software simulations have demonstrated that a neural network approach can give significantly better performance than the linear technique currently used on most Tokamak experiments. The practical application of the neural network approach requires high-speed hardware, for which a fully parallel implementation of the multi-layer perceptron, using a hybrid of digital and analogue technology, has been developed.

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Public policy becomes managerial practice through a process of implementation. There is an established literature within Implementation Studies which explains the variables and some of the processes involved in implementation, but less attention has been focused upon how public service managers convert new policy initiatives into practice. The research proposes that managers and their organisations have to go through a process of learning in order to achieve the implementation of public policy. Data was collected over a five year period from four case studies of capital investment appraisal in the British National Health Service. Further data was collected from taped interviews by key actors within the case studies. The findings suggest that managers do learn to implement policy and four factors are important in this learning process. These are; (i) the nature of bureaucratic responsibility; (ii) the motivation of actors towards learning; (iii) the passage of time which allows for the development of competence and (iv) the use of project team structures. The research has demonstrated that the conversion of policy into practice occurs through the operationalisation of solutions to policy problems via job tasks. As such it suggests that in understanding how policy is implemented, technical learning is more important than cultural learning, in this context. In conclusion, a "Model of Learned Implementation" is presented, together with a discussion of some of the implications of the research. These are the possible use of more pilot projects for new policy initiatives and the more systematic diffusion of knowledge about implementation solutions.

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Purpose - The purpose of this paper is to act as a meticulous conceptual paper probing the contemporary view towards lean and illustrate that, despite its discernible benefits, the implementation record suffers as the prevailing opinion fails to encapsulate that an aspiring lean enterprise shall only succeed if it views lean as a philosophy rather than another strategy. Design/methodology/approach - The paper is based on a thorough literature search concerning the success and failure of lean implementations and acts as a precursor for one of the authors utilising a combination of methodologies; namely, interviewing, survey questionnaire and participant observation in attempting to prove his PhD hypothesis. Findings - Evidently, a cocktail of factors are needed for lean success; not only is it necessary to implement most of the technical tools but an organisation's culture needs transforming too. Furthermore, the alterations need to be implemented throughout an organisation's value chain. Lean has a major strategic significance, though its implementation procedure, HRM implications, general approach to the supplier base coupled with the overall universal conviction of viewing lean as a set of tactics rather than embracing it as a philosophy advocates that this contributes to the relatively low number of successful lean initiatives. Originality/value - The paper would prove invaluable to lean practitioners through its summation of the intricacies towards lean enterprise success and academic researchers by focusing their attention towards the necessary cultural implications. © Emerald Group Publishing Limited.

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Conventional project management techniques are not always sufficient to ensure time, cost and quality achievement of large-scale construction projects due to complexity in planning, design and implementation processes. The main reasons for project non-achievement are changes in scope and design, changes in government policies and regulations, unforeseen inflation, underestimation and improper estimation. Projects that are exposed to such an uncertain environment can be effectively managed with the application of risk management throughout the project's life cycle. However, the effectiveness of risk management depends on the technique through which the effects of risk factors are analysed/quantified. This study proposes the Analytic Hierarchy Process (AHP), a multiple attribute decision making technique, as a tool for risk analysis because it can handle subjective as well as objective factors in a decision model that are conflicting in nature. This provides a decision support system (DSS) to project management for making the right decision at the right time for ensuring project success in line with organisation policy, project objectives and a competitive business environment. The whole methodology is explained through a case application of a cross-country petroleum pipeline project in India and its effectiveness in project management is demonstrated.

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We present an implementation of the domain-theoretic Picard method for solving initial value problems (IVPs) introduced by Edalat and Pattinson [1]. Compared to Edalat and Pattinson's implementation, our algorithm uses a more efficient arithmetic based on an arbitrary precision floating-point library. Despite the additional overestimations due to floating-point rounding, we obtain a similar bound on the convergence rate of the produced approximations. Moreover, our convergence analysis is detailed enough to allow a static optimisation in the growth of the precision used in successive Picard iterations. Such optimisation greatly improves the efficiency of the solving process. Although a similar optimisation could be performed dynamically without our analysis, a static one gives us a significant advantage: we are able to predict the time it will take the solver to obtain an approximation of a certain (arbitrarily high) quality.

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The role of technology management in achieving improved manufacturing performance has been receiving increased attention as enterprises are becoming more exposed to competition from around the world. In the modern market for manufactured goods the demand is now for more product variety, better quality, shorter delivery and greater flexibility, while the financial and environmental cost of resources has become an urgent concern to manufacturing managers. This issue of the International Journal of Technology Management addresses the question of how the diffusion, implementation and management of technology can improve the performance of manufacturing industries. The authors come from a large number of different countries and their contributions cover a wide range of topics within this general theme. Some papers are conceptual, others report on research carried out in a range of different industries including steel production, iron founding, electronics, robotics, machinery, precision engineering, metal working and motor manufacture. In some cases they describe situations in specific countries. Several are based on presentations made at the UK Operations Management Association's Sixth International Conference held at Aston University at which the conference theme was 'Achieving Competitive Edge: Getting Ahead Through Technology and People'. The first two papers deal with questions of advanced manufacturing technology implementation and management. Firstly Beatty describes a three year longitudinal field study carried out in ten Canadian manufacturing companies using CADICAM and CIM systems. Her findings relate to speed of implementation, choice of system type, the role of individuals in implementation, organization and job design. This is followed by a paper by Bessant in which he argues that a more a strategic approach should be taken towards the management of technology in the 1990s and beyond. Also considered in this paper are the capabilities necessary in order to deploy advanced manufacturing technology as a strategic resource and the way such capabilities might be developed within the firm. These two papers, which deal largely with the implementation of hardware, are supplemented by Samson and Sohal's contribution in which they argue that a much wider perspective should be adopted based on a new approach to manufacturing strategy formulation. Technology transfer is the topic of the following two papers. Pohlen again takes the case of advanced manufacturing technology and reports on his research which considers the factors contributing to successful realisation of AMT transfer. The paper by Lee then provides a more detailed account of technology transfer in the foundry industry. Using a case study based on a firm which has implemented a number of transferred innovations a model is illustrated in which the 'performance gap' can be identified and closed. The diffusion of technology is addressed in the next two papers. In the first of these, by Lowe and Sim, the managerial technologies of 'Just in Time' and 'Manufacturing Resource Planning' (or MRP 11) are examined. A study is described from which a number of factors are found to influence the adoption process including, rate of diffusion and size. Dahlin then considers the case of a specific item of hardware technology, the industrial robot. Her paper reviews the history of robot diffusion since the early 1960s and then tries to predict how the industry will develop in the future. The following two papers deal with the future of manufacturing in a more general sense. The future implementation of advanced manufacturing technology is the subject explored by de Haan and Peters who describe the results of their Dutch Delphi forecasting study conducted among a panel of experts including scientists, consultants, users and suppliers of AMT. Busby and Fan then consider a type of organisational model, 'the extended manufacturing enterprise', which would represent a distinct alternative pure market-led and command structures by exploiting the shared knowledge of suppliers and customers. The three country-based papers consider some strategic issues relating manufacturing technology. In a paper based on investigations conducted in China He, Liff and Steward report their findings from strategy analyses carried out in the steel and watch industries with a view to assessing technology needs and organizational change requirements. This is followed by Tang and Nam's paper which examines the case of machinery industry in Korea and its emerging importance as a key sector in the Korean economy. In his paper which focuses on Venezuela, Ernst then considers the particular problem of how this country can address the problem of falling oil revenues. He sees manufacturing as being an important contributor to Venezuela's future economy and proposes a means whereby government and private enterprise can co-operate in development of the manufacturing sector. The last six papers all deal with specific topics relating to the management manufacturing. Firstly Youssef looks at the question of manufacturing flexibility, introducing and testing a conceptual model that relates computer based technologies flexibility. Dangerfield's paper which follows is based on research conducted in the steel industry. He considers the question of scale and proposes a modelling approach determining the plant configuration necessary to meet market demand. Engstrom presents the results of a detailed investigation into the need for reorganising material flow where group assembly of products has been adopted. Sherwood, Guerrier and Dale then report the findings of a study into the effectiveness of Quality Circle implementation. Stillwagon and Burns, consider how manufacturing competitiveness can be improved individual firms by describing how the application of 'human performance engineering' can be used to motivate individual performance as well as to integrate organizational goals. Finally Sohal, Lewis and Samson describe, using a case study example, how just-in-time control can be applied within the context of computer numerically controlled flexible machining lines. The papers in this issue of the International Journal of Technology Management cover a wide range of topics relating to the general question of improving manufacturing performance through the dissemination, implementation and management of technology. Although they differ markedly in content and approach, they have the collective aim addressing the concepts, principles and practices which provide a better understanding the technology of manufacturing and assist in achieving and maintaining a competitive edge.

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This research is concerned with the development of distributed real-time systems, in which software is used for the control of concurrent physical processes. These distributed control systems are required to periodically coordinate the operation of several autonomous physical processes, with the property of an atomic action. The implementation of this coordination must be fault-tolerant if the integrity of the system is to be maintained in the presence of processor or communication failures. Commit protocols have been widely used to provide this type of atomicity and ensure consistency in distributed computer systems. The objective of this research is the development of a class of robust commit protocols, applicable to the coordination of distributed real-time control systems. Extended forms of the standard two phase commit protocol, that provides fault-tolerant and real-time behaviour, were developed. Petri nets are used for the design of the distributed controllers, and to embed the commit protocol models within these controller designs. This composition of controller and protocol model allows the analysis of the complete system in a unified manner. A common problem for Petri net based techniques is that of state space explosion, a modular approach to both the design and analysis would help cope with this problem. Although extensions to Petri nets that allow module construction exist, generally the modularisation is restricted to the specification, and analysis must be performed on the (flat) detailed net. The Petri net designs for the type of distributed systems considered in this research are both large and complex. The top down, bottom up and hybrid synthesis techniques that are used to model large systems in Petri nets are considered. A hybrid approach to Petri net design for a restricted class of communicating processes is developed. Designs produced using this hybrid approach are modular and allow re-use of verified modules. In order to use this form of modular analysis, it is necessary to project an equivalent but reduced behaviour on the modules used. These projections conceal events local to modules that are not essential for the purpose of analysis. To generate the external behaviour, each firing sequence of the subnet is replaced by an atomic transition internal to the module, and the firing of these transitions transforms the input and output markings of the module. Thus local events are concealed through the projection of the external behaviour of modules. This hybrid design approach preserves properties of interest, such as boundedness and liveness, while the systematic concealment of local events allows the management of state space. The approach presented in this research is particularly suited to distributed systems, as the underlying communication model is used as the basis for the interconnection of modules in the design procedure. This hybrid approach is applied to Petri net based design and analysis of distributed controllers for two industrial applications that incorporate the robust, real-time commit protocols developed. Temporal Petri nets, which combine Petri nets and temporal logic, are used to capture and verify causal and temporal aspects of the designs in a unified manner.

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National meteorological offices are largely concerned with synoptic-scale forecasting where weather predictions are produced for a whole country for 24 hours ahead. In practice, many local organisations (such as emergency services, construction industries, forestry, farming, and sports) require only local short-term, bespoke, weather predictions and warnings. This thesis shows that the less-demanding requirements do not require exceptional computing power and can be met by a modern, desk-top system which monitors site-specific ground conditions (such as temperature, pressure, wind speed and direction, etc) augmented with above ground information from satellite images to produce `nowcasts'. The emphasis in this thesis has been towards the design of such a real-time system for nowcasting. Local site-specific conditions are monitored using a custom-built, stand alone, Motorola 6809 based sub-system. Above ground information is received from the METEOSAT 4 geo-stationary satellite using a sub-system based on a commercially available equipment. The information is ephemeral and must be captured in real-time. The real-time nowcasting system for localised weather handles the data as a transparent task using the limited capabilities of the PC system. Ground data produces a time series of measurements at a specific location which represents the past-to-present atmospheric conditions of the particular site from which much information can be extracted. The novel approach adopted in this thesis is one of constructing stochastic models based on the AutoRegressive Integrated Moving Average (ARIMA) technique. The satellite images contain features (such as cloud formations) which evolve dynamically and may be subject to movement, growth, distortion, bifurcation, superposition, or elimination between images. The process of extracting a weather feature, following its motion and predicting its future evolution involves algorithms for normalisation, partitioning, filtering, image enhancement, and correlation of multi-dimensional signals in different domains. To limit the processing requirements, the analysis in this thesis concentrates on an `area of interest'. By this rationale, only a small fraction of the total image needs to be processed, leading to a major saving in time. The thesis also proposes an extention to an existing manual cloud classification technique for its implementation in automatically classifying a cloud feature over the `area of interest' for nowcasting using the multi-dimensional signals.

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The aim of this research paper is to explore and evaluate previous work focussing on the relationship and links between Lean and Green supply chain management practices. Several explanatory frameworks are explored and discussed. It is intended that evidence and insights can be developed and used: (a) to assist our understanding of where Lean practices are synergistic for Green; (b) to clarify if Green practices are synergistic for Lean; and (c) to identify opportunities for companies to use their Lean framework as a catalyst to making their processes Green. The paper provides evidence suggesting that Lean is beneficial for Green practices and the implementation of Green practices in turn also has a positive influence on existing Lean business practices. © 2010 Elsevier Ltd. All rights reserved.

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Deep hole drilling is one of the most complicated metal cutting processes and one of the most difficult to perform on CNC machine-tools or machining centres under conditions of limited manpower or unmanned operation. This research work investigates aspects of the deep hole drilling process with small diameter twist drills and presents a prototype system for real time process monitoring and adaptive control; two main research objectives are fulfilled in particular : First objective is the experimental investigation of the mechanics of the deep hole drilling process, using twist drills without internal coolant supply, in the range of diarneters Ø 2.4 to Ø4.5 mm and working length up to 40 diameters. The definition of the problems associated with the low strength of these tools and the study of mechanisms of catastrophic failure which manifest themselves well before and along with the classic mechanism of tool wear. The relationships between drilling thrust and torque with the depth of penetration and the various machining conditions are also investigated and the experimental evidence suggests that the process is inherently unstable at depths beyond a few diameters. Second objective is the design and implementation of a system for intelligent CNC deep hole drilling, the main task of which is to ensure integrity of the process and the safety of the tool and the workpiece. This task is achieved by means of interfacing the CNC system of the machine tool to an external computer which performs the following functions: On-line monitoring of the drilling thrust and torque, adaptive control of feed rate, spindle speed and tool penetration (Z-axis), indirect monitoring of tool wear by pattern recognition of variations of the drilling thrust with cumulative cutting time and drilled depth, operation as a data base for tools and workpieces and finally issuing of alarms and diagnostic messages.

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This thesis introduces and develops a novel real-time predictive maintenance system to estimate the machine system parameters using the motion current signature. Recently, motion current signature analysis has been addressed as an alternative to the use of sensors for monitoring internal faults of a motor. A maintenance system based upon the analysis of motion current signature avoids the need for the implementation and maintenance of expensive motion sensing technology. By developing nonlinear dynamical analysis for motion current signature, the research described in this thesis implements a novel real-time predictive maintenance system for current and future manufacturing machine systems. A crucial concept underpinning this project is that the motion current signature contains infor­mation relating to the machine system parameters and that this information can be extracted using nonlinear mapping techniques, such as neural networks. Towards this end, a proof of con­cept procedure is performed, which substantiates this concept. A simulation model, TuneLearn, is developed to simulate the large amount of training data required by the neural network ap­proach. Statistical validation and verification of the model is performed to ascertain confidence in the simulated motion current signature. Validation experiment concludes that, although, the simulation model generates a good macro-dynamical mapping of the motion current signature, it fails to accurately map the micro-dynamical structure due to the lack of knowledge regarding performance of higher order and nonlinear factors, such as backlash and compliance. Failure of the simulation model to determine the micro-dynamical structure suggests the pres­ence of nonlinearity in the motion current signature. This motivated us to perform surrogate data testing for nonlinearity in the motion current signature. Results confirm the presence of nonlinearity in the motion current signature, thereby, motivating the use of nonlinear tech­niques for further analysis. Outcomes of the experiment show that nonlinear noise reduction combined with the linear reverse algorithm offers precise machine system parameter estimation using the motion current signature for the implementation of the real-time predictive maintenance system. Finally, a linear reverse algorithm, BJEST, is developed and applied to the motion current signature to estimate the machine system parameters.

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Communication and portability are the two main problems facing the user. An operating system, called PORTOS, was developed to solve these problems for users on dedicated microcomputer systems. Firstly, an interface language was defined, according to the anticipated requirements and behaviour of its potential users. Secondly, the PORTOS operating system was developed as a processor for this language. The system is currently running on two minicomputers of highly different architectures. PORTOS achieves its portability through its high-level design, and implementation in CORAL66. The interface language consists of a set of user cotnmands and system responses. Although only a subset has been implemented, owing to time and manpower constraints, promising results were achieved regarding the usability of the language, and its portability.

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Warehouse is an essential component in the supply chain, linking the chain partners and providing them with functions of product storage, inbound and outbound operations along with value-added processes. Allocation of warehouse resources should be efficient and effective to achieve optimum productivity and reduce operational costs. Radio frequency identification (RFID) is a technology capable of providing real-time information about supply chain operations. It has been used by warehousing and logistic enterprises to achieve reduced shrinkage, improved material handling and tracking as well as increased accuracy of data collection. However, both academics and practitioners express concerns about challenges to RFID adoption in the supply chain. This paper provides a comprehensive analysis of the problems encountered in RFID implementation at warehouses, discussing the theoretical and practical adoption barriers and causes of not achieving full potential of the technology. Lack of foreseeable return on investment (ROI) and high costs are the most commonly reported obstacles. Variety of standards and radio wave frequencies are identified as source of concern for decision makers. Inaccurate performance of the RFID within the warehouse environment is examined. Description of integration challenges between warehouse management system and RFID technology is given. The paper discusses the existing solutions to technological, investment and performance RFID adoption barriers. Factors to consider when implementing the RFID technology are given to help alleviate implementation problems. By illustrating the challenges of RFID in the warehouse environment and discussing possible solutions the paper aims to help both academics and practitioners to focus on key areas constituting an obstacle to the technology growth. As more studies will address these challenges, the realisation of RFID benefits for warehouses and supply chain will become a reality.

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There were three principal research aims: primarily, Lean is and always should be regarded as a business model as depicted by Toyota who is dedicated towards finding better ways of producing cars; consequently an investigation of whether organisations embracing Lean as a philosophy were indeed more triumphant. An adapted balanced scorecard was used which embraced strategic, operation and indices focused towards the future prospects of an organisation. Secondly, it was obligatory to explicitly and precisely determine whether an organisation espoused Lean as a philosophy as opposed to another process or strategy. Thirdly, since Lean has to be envisaged as a never-ending journey; it was important to map out the Lean journey and to be able to categorize the juncture an organisation occupies at any particular phase of its overall implementation. This affords an opportunity to advise an organisation of specific requirements it needs to satisfy should it wish to embrace Lean as a philosophy. The methodological approach focused on the effective deployment of survey questionnaires in sixty-eight organisations and seven extensive case studies in manufacturing organisations of varying sizes. The CIMA organisational classification, the Puttick grid and the Product-Process matrix were used to analyse the range of organisations used in this investigation. Whilst there was a requirement to investigate whether Lean indeed equates to success, pertinent performance measurement was considered decisive; the DMP Model (Maltz et al., 2003) was modified to perform this role. An unremitting theme both in literature concerning the implementation of Lean and in the research evolves around the notion of corporate cultures. Its relevance is explored further within the analysis. In accepting the premise that Lean incorporates a journey, it was fundamental to identify the voyage. Prevalent frameworks are deficient in identifying the sustainability and ideological facets of Lean. Consequently, an extensive Lean audit was developed and piloted in twenty disparate organisations.