962 resultados para 010206 Operations Research
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The applications of micro-end-milling operations have increased recently. A Micro-End-Milling Operation Guide and Research Tool (MOGART) package has been developed for the study and monitoring of micro-end-milling operations. It includes an analytical cutting force model, neural network based data mapping and forecasting processes, and genetic algorithms based optimization routines. MOGART uses neural networks to estimate tool machinability and forecast tool wear from the experimental cutting force data, and genetic algorithms with the analytical model to monitor tool wear, breakage, run-out, cutting conditions from the cutting force profiles. The performance of MOGART has been tested on the experimental data of over 800 experimental cases and very good agreement has been observed between the theoretical and experimental results. The MOGART package has been applied to the micro-end-milling operation study of Engineering Prototype Center of Radio Technology Division of Motorola Inc.
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The exploration and development of oil and gas reserves located in harsh offshore environments are characterized with high risk. Some of these reserves would be uneconomical if produced using conventional drilling technology due to increased drilling problems and prolonged non-productive time. Seeking new ways to reduce drilling cost and minimize risks has led to the development of Managed Pressure Drilling techniques. Managed pressure drilling methods address the drawbacks of conventional overbalanced and underbalanced drilling techniques. As managed pressure drilling techniques are evolving, there are many unanswered questions related to safety and operating pressure regimes. Quantitative risk assessment techniques are often used to answer these questions. Quantitative risk assessment is conducted for the various stages of drilling operations – drilling ahead, tripping operation, casing and cementing. A diagnostic model for analyzing the rotating control device, the main component of managed pressure drilling techniques, is also studied. The logic concept of Noisy-OR is explored to capture the unique relationship between casing and cementing operations in leading to well integrity failure as well as its usage to model the critical components of constant bottom-hole pressure drilling technique of managed pressure drilling during tripping operation. Relevant safety functions and inherent safety principles are utilized to improve well integrity operations. Loss function modelling approach to enable dynamic consequence analysis is adopted to study blowout risk for real-time decision making. The aggregation of the blowout loss categories, comprising: production, asset, human health, environmental response and reputation losses leads to risk estimation using dynamically determined probability of occurrence. Lastly, various sub-models developed for the stages/sub-operations of drilling operations and the consequence modelling approach are integrated for a holistic risk analysis of drilling operations.
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Acknowledgements This article is based on a doctoral research project of the first author which was sponsored by an international drilling rig operator. The views presented are those of the authors and should not be taken to represent the position or policy of the sponsor. The authors wish to thank the industrial supervisor and the drilling experts for their contribution and patience, as well as Aberdeen Drilling School for allowing the first author to attend one of their well control courses.
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Recent debate on the quality of arts events has concentrated on the requirement to deliver against a complex range of political, social, and cultural criteria with an emphasis on the external partnerships that are forged. Yet those aspects of quality over which event organizers have more direct control have been accorded minor examination. The authors believe that operational effectiveness is key to service quality in the cultural context, and seek to demonstrate that a balanced consideration of both process and product is vital to fully deliver quality arts events. This article identifies areas of emergent research and practice and focuses on issues in the front-of-house environment where the breakdown of service quality is a real concern, using the experience of one UK not-for-profit arts organization as a case study to illustrate potential management responses.
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Increased complexity in large design and manufacturing organisations requires improvements at the operations management (OM)–applied service (AS) interface areas to improve project effectiveness. The aim of this paper is explore the role of Lean in improving the longitudinal efficiency of the OM–AS interface within a large aerospace organisation using Lean principles and boundary spanning theory. The methodology was an exploratory longitudinal case approach including exploratory interviews (n = 21), focus groups (n = 2), facilitated action-research workshops (n = 2) and two trials or experiments using longitudinal data involving both OM and AS personnel working at the interface. The findings draw upon Lean principles and boundary spanning theory to guide and interpret the findings. It was found that misinterpretation, and forced implementation, of OM-based Lean terminology and practice in the OM–AS interface space led to delays and misplaced resources. Rather both OM and AS staff were challenged to develop a cross boundary understanding of Lean-based boundary (knowledge) objects in interpreting OM requests. The longitudinal findings from the experiments showed that the development of Lean Performance measurements and lean Value Stream constructs was more successful when these Lean constructs were treated as boundary (knowledge) objects requiring transformation over time to orchestrate improved effectiveness and in leading to consistent terminology and understanding between the OM–AS boundary spanning team.
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One of the pioneer firms in the leisure cruise industry embarked on a bold idea in 2000 to offer an unregimented experience unlike most cruises. Despite the appeal of the concept from a marketing perspective, the service innovation posed operational challenges, many of which continue to undermine the firm’s competitive position. Using a multi-method empirical approach and interdisciplinary views that draw on research from marketing and operations management, the authors analyze this business case to identify challenges that service firms face when services are developed and managed from siloed functional perspectives. Based on their research findings and guided by the literature, the authors derive a service-systems model to aid service planning and management. The authors further highlight a new organizational form and function for services under the domain of service experience management that is positioned as a means to unify service operations and marketing for delivering on service promises. The authors offer direction for further research on service operations systems and service experience management.
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Stainless steels were developed in the early 20th century and are used where both the mechanical properties of steels and corrosion resistance are required. There is continuous research to allow stainless steel components to be produced in a more economical way and be used in more harsh environments. A necessary component in this effort is to correlate the service performance with the production processes. The central theme of this thesis is the mechanical grinding process. This is commonly used for producing stainless steel components, and results in varied surface properties that will strongly affect their service life. The influence of grinding parameters including abrasive grit size, machine power and grinding lubricant were studied for 304L austenitic stainless steel (Paper II) and 2304 duplex stainless steel (Paper I). Surface integrity was proved to vary significantly with different grinding parameters. Abrasive grit size was found to have the largest influence. Surface defects (deep grooves, smearing, adhesive/cold welding chips and indentations), a highly deformed surface layer up to a few microns in thickness and the generation of high level tensile residual stresses in the surface layer along the grinding direction were observed as the main types of damage when grinding stainless steels. A large degree of residual stress anisotropy is interpreted as being due to mechanical effects dominating over thermal effects. The effect of grinding on stress corrosion cracking behaviour of 304L austenitic stainless steel in a chloride environment was also investigated (Paper III). Depending on the surface conditions, the actual loading by four-point bend was found to deviate from the calculated value using the formula according to ASTM G39 by different amounts. Grinding-induced surface tensile residual stress was suggested as the main factor to cause micro-cracks initiation on the ground surfaces. Grinding along the loading direction was proved to increase the susceptibility to chloride-induced SCC, while grinding perpendicular to the loading direction improved SCC resistance. The knowledge obtained from this work can provide a reference for choosing appropriate grinding parameters when fabricating stainless steel components; and can also be used to help understanding the failure mechanism of ground stainless steel components during service.
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Research on strategic management of resources for small consulting firms which are international or planning to operate internationally is scarce or not existing at all. It is however important to start generating the theories that will support managers in their decision making and planning. This thesis investigates how do small management consulting firms manage their internal and external resources while operating in international markets. Throughout the study, aspects related to internal and external resources management as well as management strategies in these firms have been examined in relations to firm’s internationalisation activities. A qualitative analysis was carried out whereby four small consulting firms in Export Management Consulting, Integration Services Consulting-, Software Development Consulting- and Business Solutions Consulting companies were interviewed. In order to generate the holistic understanding of the study, the thesis writer selected Value Enhanced Collaborative Working (VECW) model as an analysis framework. The model focuses on people, processes and tools as key elements that small consulting firms consider when thinking about managing their international operations. The findings of the thesis reveal that, internal and external resources in the interviewed consulting firms are viewed similarly, but managed differently depending on the nature and size of the firm. Firm’s management strategies concentrate on the adequate utilisation of the employees' motivation and experiences, effective stakeholders' management, various administrative evaluation processes and tools, the ability to realise useful networks, constant improvement through employee trainings, employees and customers’ feedbacks as well as enhanced freedom in order to support employees’ creativity. Further research to examine functional administrative tools and tools that small consulting firms could use to assess their resource capabilities when planning to become international would benefit the smaller businesses in terms of resources management and certainty in planning.
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This chapter establishes a framework for the governance of intermodal terminals throughout their life cycle, based on the product life cycle. The framework covers the initial planning by the public sector, the public/private split in funding and ownership, the selection of an operator, ensuring fair access to all users, and finally reconcessioning the terminal to a new operator, managing the handover and maintaining the terminal throughout its life cycle. This last point is especially important as industry conditions change and the terminal's role in the transport network comes under threat, either by a lack of demand or by increased demand requiring expansion, redesign and reinvestment. Each stage of the life cycle framework is operationalised based on empirical examples drawn from research by the authors on intermodal terminal planning and funding, the tender process and concession and operation contracts. In future the framework can be applied in additional international contexts to form a basis for transport cost analysis, logistics planning and government policy.
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The aim of this master’s thesis was to map the management accounting processes and reporting of an internal service unit. The research was conducted in energy services in a forest industry company. Research questions and the results of the study are highly specific for the case unit although some generalizable features of management accounting in internal service units under shared services were searched. The research was carried out as a qualitative action research and a single case study. Internal benchmarking was used to find best practices from other units and to get a comprehensive understanding of the financial processes of the case company. Empirical data for the study was collected with participant observation, interviews of experts and by exploring internal company documents. A literature review was conducted to outline the subject and to support the study. Although the management accounting processes of the case unit were found to be on a good level, some improvement ideas were presented. Results of the research show that the needs of the customers are in the key role in the processes of an internal service unit. Management accounting and reporting need to support the company strategy and management decision-making. To evaluate the performance of the service unit both financial and non-financial measures are needed.
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© IMechE 2014. Controlled auto-ignition, also known as homogeneous charge compression ignition, has been the subject of extensive research because of their ability to provide simultaneous reductions in fuel consumption and NOx emissions from a gasoline engine. However, due to its limited operation range, switching between controlled auto-ignition and spark ignition combustion is needed to cover the complete operating range of a gasoline engine for passenger car applications. Previous research has shown that the spark ignition -controlled auto-ignition hybrid combustion (SCHC) has the potential to control the ignition timing and heat release process during the mode transition operations. However, it was found that the SCHC is often characterized with large cycle-to-cycle variations. The cyclic variations in the in-cylinder pressure are particularly noticeable in terms of both their peak values and timings while the coefficient of variation in the indicated mean effective pressure is much less. In this work, the cyclic variations in SCHC operations were analyzed by means of in-cylinder pressure and heat release analysis in a single-cylinder gasoline engine equipped with Variable Valve Actuation (VVA) systems. First, characteristics of the in-cylinder pressure traces during the spark ignition-controlled auto-ignition hybrid combustion operation are presented and their heat release processes analyzed. In order to clarify the contribution to heat release and cyclic variation in SCHC, a new method is introduced to identify the occurrence of auto-ignition combustion and its subsequent heat release process. Based on the new method developed, the characteristics of cyclic variations in the maximum rate of pressure rise and different stages of heat release process have been analyzed and discussed.
Design and Development of a Research Framework for Prototyping Control Tower Augmented Reality Tools
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The purpose of the air traffic management system is to ensure the safe and efficient flow of air traffic. Therefore, while augmenting efficiency, throughput and capacity in airport operations, attention has rightly been placed on doing it in a safe manner. In the control tower, many advances in operational safety have come in the form of visualization tools for tower controllers. However, there is a paradox in developing such systems to increase controllers' situational awareness: by creating additional computer displays, the controller's vision is pulled away from the outside view and the time spent looking down at the monitors is increased. This reduces their situational awareness by forcing them to mentally and physically switch between the head-down equipment and the outside view. This research is based on the idea that augmented reality may be able to address this issue. The augmented reality concept has become increasingly popular over the past decade and is being proficiently used in many fields, such as entertainment, cultural heritage, aviation, military & defense. This know-how could be transferred to air traffic control with a relatively low effort and substantial benefits for controllers’ situation awareness. Research on this topic is consistent with SESAR objectives of increasing air traffic controllers’ situation awareness and enable up to 10 % of additional flights at congested airports while still increasing safety and efficiency. During the Ph.D., a research framework for prototyping augmented reality tools was set up. This framework consists of methodological tools for designing the augmented reality overlays, as well as of hardware and software equipment to test them. Several overlays have been designed and implemented in a simulated tower environment, which is a virtual reconstruction of Bologna airport control tower. The positive impact of such tools was preliminary assessed by means of the proposed methodology.
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Analytics is the technology working with the manipulation of data to produce information able to change the world we live every day. Analytics have been largely used within the last decade to cluster people’s behaviour to predict their preferences of items to buy, music to listen, movies to watch and even electoral preference. The most advanced companies succeded in controlling people’s behaviour using analytics. Despite the evidence of the super-power of analytics, they are rarely applied to the big data collected within supply chain systems (i.e. distribution network, storage systems and production plants). This PhD thesis explores the fourth research paradigm (i.e. the generation of knowledge from data) applied to supply chain system design and operations management. An ontology defining the entities and the metrics of supply chain systems is used to design data structures for data collection in supply chain systems. The consistency of this data is provided by mathematical demonstrations inspired by the factory physics theory. The availability, quantity and quality of the data within these data structures define different decision patterns. Ten decision patterns are identified, and validated on-field, to address ten different class of design and control problems in the field of supply chain systems research.