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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Operations management perspectives on expert services

Santos, Juliana January 2013 (has links)
Expert Services like consulting, legal advisory and software design play a significant and growing role in the developed economies. In operations management (OM), the term “Professional Services” is frequently used to refer to these offerings. The literature on Expert Services proposes that these services are different from other types of services and require a different OM approach. However, recent empirical research calls into question some of the OM assumptions about Expert Services and their delivery processes. Some empirical and theoretical studies also suggest that individuals’ expertise is fundamental to making these delivery processes more efficient and effective. For these reasons, operations management researchers are calling for more robust models to explain the nature of Expert Services. This thesis therefore focuses on understanding Expert Services delivery processes and explores in detail the role individuals’ expertise plays in them. To reach its goals, this PhD by publication uses evidence from three Expert Service providers to compose three papers that contribute towards a better understanding of these service delivery processes. The three papers deal, respectively, with the characteristics of Expert Services delivery processes, with the nature and implications of customer involvement in the delivery process and with the development of new expert services. Combined, the insights from the three papers draw attention to the managerial implications of having expertise as a key productive resource. The outcomes of the papers also create means to refine and revisit OM concepts in relation to how Expert Services are developed and delivered. This research therefore contributes to the OM knowledge of Expert Services, addressing some of the recent calls for research in the area. This thesis also sets out an agenda for future research that can further increase our understanding of these offerings and create means to improve their delivery processes.
2

Global optimisation for modular process design

Balendra, Sujan January 2007 (has links)
The aim of this thesis is to investigate methods for allowing modular process design and simulation systems to rigorously find globally optimal solutions. Sequential Modular Flowsheets are still used by many companies for process design even though they do not use global optimisation. Applying global optimisation to a process flowsheet in the early stages of the design will have significant positive impacts on profitability. In order to maintain a competitive edge in the practical business world it is critical to optimise new designs and operations in manufacturing plants. Significant improvements in finding the global optimum are shown using basic interval contraction when solving mathematical problems with equality constraints. Developments were made to fixed point type contractors to further improve computational efficiency to a set of mathematical test problems containing constraints. The idea and development of contraction was taken forward to modular flowsheets. Global optimisation algorithms have been developed for solving modular flowsheets to involve contractors. The Algorithm was tested to draw conclusions about the computational efficiency with and without the basic contractors. A global optimisation algorithm to find all the global solutions to modular flowsheeting problem was devised and tested. Different interval model formulation of flowsheeting problems were constructed to investigate the computational efficiency for interval global optimisation algorithms and the interval contraction techniques were investigated for every type of formulation.
3

Cost modelling of rapid manufacturing based mass customisation system for fabrication of custom foot orthoses

Jumani, Muhammad Saleh January 2013 (has links)
Solid freeform fabrication (SFF) or Additive manufacturing (AM) techniques have emerged in recent years as advanced manufacturing techniques. These techniques have demonstrated advantages particularly in situations where the demands for unique geometrical structured customer-specific products are high and the time to market is very short. Applications of these techniques in the medical sector in combination with the latest medical digital imaging technologies are growing quickly. The techniques have inherent advantages of compatibility with the output information of medical digitising techniques. Foot orthoses are medical devices used as shoe inserts in the treatment of foot disorders, injuries and diseases such as diabetes, rheumatoid arthritis, congenital defects and other foot related injuries. Currently custom foot orthoses are fabricated through manufacturing techniques which involve costly and based on lengthy trial and error manufacturing process. These techniques have limitations in terms of fabricating required geometries and incorporating complex design features in the custom-made orthoses. The novelty of this research is to explore the commercial scale application of rapid manufacturing techniques and to assess a rapid manufacturing based design and fabrication system for production of custom foot orthoses. The developed system is aimed at delivering the custom made orthoses at mass scale with improved fit, consistency, accuracy and increased product quality. The traditional design and fabrication process for production of custom foot orthoses was investigated and modelled with IDEF0 modelling methodology. The developed IDEF0 model was re-modelled and then the rapid manufacturing approach was integrated in the design and fabrication process. The main functions of foot geometry capture, orthoses design and manufacture of orthoses were modelled and evaluated individually with respect to time and cost and quality of the final product. Different well-established rapid manufacturing techniques were integrated in the current design and fabrication process. The results showed that the techniques have significant impacts on the overall design and fabrication process in terms of increased process efficiency, low lead-time, increased productivity and improved quality of the final product. An orthosis model was fabricated on an experimental basis using different well established rapid manufacturing techniques. The techniques were separately investigated and analysed in terms of orthoses fabrication cost and build time. The cost and lead-time in different techniques were modelled, analysed and evaluated for evaluation of commercial scale applications. The analysis and evaluation of the cost and lead-time modelled for different rapid manufacturing techniques showed that selective laser sintering technique is the better option for integrating the technique in fabrication of custom foot orthoses and that it has the potential to compete with conventional techniques.
4

Investment, R&D and credit constraints

Santos, Carlos Daniel January 2008 (has links)
This thesis develops a dynamic industry equilibrium framework to be employed in situations where firms compete in a complex environment with either several firms in the industry or large state spaces. This model is employed to analyze the problems of Investment, R and D and Credit Constraints in situations where the 'curse of dimensionality' occurs. Chapter 1 introduces the problem and applications. Chapter 2 describes the model, assumptions and main results. Chapter 3 considers the problem of estimating production functions in a manner which is consistent with the model. Chapter 4 contains an application to estimate the Sunk Costs of R and D in the Portuguese Moulds Industry and estimate them to be about 2.6 million euros (1.7 times the average firm sales level). Finally Chapter 5 incorporates an application to the US Steel Industry to estimate the costs of external finance. We find that the average sunk cost of R and D for this industry is on the order of $194m and the costs of external finance are about 35 cents per dollar raised. In the second application (in joint work with John Van Reenen), we use a similar framework and introduce financial constraints which can affect investment and R and D decisions. By specifying a dynamic structural model and solving through numerical simulation we model adjustment costs, R and D decisions and financial constraints simultaneously. Applying the model to 35 years of firm-level panel data from the US iron and steel industry we provide evidence that costs of external finance are substantial, consistent with asymmetric information, even in a developed financial market like the US. The average sunk cost of R and D is on the order of $194m - consistent with industry estimates of the typical costs of building an R&D lab.
5

A comparative study of the use and effectiveness of production management systems in the UK and Libya

Sameda, Ahmed Ali January 2004 (has links)
Production management systems (PMSs) are techniques or philosophies by which manufacturing enterprises manage their production. These include not only such highly sophisticated, fully integrated computer-based systems as Enterprise Resource Planning (ERP) packages, but also more `culture-based' systems such as Just-in-Time (JIT). This thesis compares the PMSs of a sample of four UK manufacturing companies with those of a similar number of Libyan enterprises, with the aim of making recommendations for the improvement of Libyan PMSs. The economic, cultural and political background of Libya is presented, followed by a comprehensive review of academic studies of PMSs and related areas, including work on the implementation of various types of PMS in different economic and cultural settings. The appropriate research methodology for the comparative work is established as being the case study technique, with qualitative data collected by means of structured interviews. The empirical findings are that the Libyan PMSs investigated are inefficient and unsophisticated when compared to the UK sample, where ERP and similar IT-based systems are favoured. It is argued that Libyan practice needs to be improved, but that implementation of ERP or similar systems would be inappropriate in the short to medium term because of infrastructural, educational and other barriers. JIT, on the other hand, is appropriate for an immediate programme of implementation in Libya and a framework is proposed by which such an implementation could be planned and executed. Recommendations are also made for further study, including into the question of eventual adoption of ERP in Libyan industry in the longer term.
6

Sustainability claims on FMCGs : consumers' perceptions and company practice in the UK and in Greece

Alevizou, Panayiota January 2011 (has links)
Eco labels and green claims by definition and ideally are meant to be connected with sustainable production and motivate sustainable consumption. Companies are faced with many labelling decisions and consumers are faced with many labelling choices. Both parties complain about misleading claims. Companies argue that consumers claim they want greener products but their purchase behaviour indicates otherwise. Consumers claim that companies use misleading claims on their products and thus, confuse them. There seems to be a communication gap between companies and consumers as well as a gap in the literature exploring this miscommunication. This research takes a different holistic approach by exploring both consumers and company claim perceptions by using a qualitative research methodology. Focus groups are used to explore consumers' perceptions and interviews are used to examine company labelling practice. Other stakeholders such as governments, NGOs, retailers, media and other organisations seem to play an important role in the area of production and consumption of green claims and thus are explored as part of the theoretical framework used in this study. The findings indicate that a new wave of claims has emerged. Sustainability claims are used by companies as an on-pack link to their environmental and/or social considerations. The company claim practice is a complex interaction of internal initiators and external influencers. Consumers decode claims with little guidance from stakeholders and companies and thus, scepticism characterises their perceptions. In both cases issues and perceptions connected to trust and literacy seem to gain importance. The main theoretical contributions of this study are a company perception typology and a consumer perception typology. The most important methodological contribution is the detailed and well documented qualitative methodology used. The findings from both parts of the research present implications for both marketers and policy makers. Consumers should be able to make informed purchase decisions and thus policy makers may interfere and offer guidance and support. In a similar manner policy makers can support companies during the claims encoding process.
7

Characterisation of candidate human embryonic stem cell processing methods to determine amenability to controllable manufacturing for product supply

Guijarro-Leach, Juan-Jose January 2013 (has links)
Human embryonic stem cells (hESCs) hold great promise for cell-based therapies and drug screening applications given their capability to self-renew and their potential to differentiate into all major lineages of somatic cells in the human body. However, for hESCs to be successfully commercialised well-defined, robust, reproducible and scalable manufacturing processes need to be developed. Moreover, unlike pharmaceuticals where the final product is distinct from the host organisms responsible for its generation, hESC-based products represent the final product and hence, careful attention needs to be taken throughout the entire bioprocess to ensure the integrity of the manufactured cell populations. This study investigated the expansion of hESCs under different culture formats conferring varying degrees of process control. Initial studies focused on the development of a systematic methodology for the in-depth characterisation of the processes involved in the manufacture of cellular products to allow for the identification, description and risk assessment of critical manufacturing variables capable of affecting processing outputs. A lack of knowledge regarding the required product specification necessary to confirm the generation of high quality cell populations was identified. To address this, several studies were performed to investigate the baseline levels at which several quality markers are expressed during the routine expansion of hESCs under different culture conditions. Feeder-free colony cultures using a defined medium were found to yield higher cell numbers per surface area available for growth. However, this culture format resulted in less reproducible processing outcomes when compared to two single cell dissociation culture formats. These results represent a data set from which product specifications can be drawn iv for the large-scale production of hESCs. To this end, and due to the limitations of growing hESCs on flat surfaces, the expansion of hESCs in a microcarrier-based culture was investigated. Preliminary microcarrier screen studies identified Hillex II as the optimal microcarrier for hESC expansion given the high cell yields obtained. Further analysis of this microcarrier identified the interactions between three culture parameters (seeding density, microcarrier mass and media volume) and allowed for the determination of the initial culture conditions to be used in agitated experiments. A novel automated microbioreactor was used for the expansion of hESCs under stirring conditions. However, the hydrodynamic environment within the microbioreactors necessary to just suspend the microcarriers was found to be detrimental for the growth of hESCs but not for the maintenance of pluripotency.
8

Multi-site capacity planning and business optimisation for process industries

Levis, Aaron January 2005 (has links)
Changing market conditions, volatile customer demand, intense competition and tightness of capital are some of the primary characteristics of the global economy that affect process industries nowadays. The main objective of the thesis is to facilitate business decision-making in today's increasingly complex and highly uncertain market environment by applying mathematical programming techniques for multi-site capacity planning and business optimisation in process industries. In the first part of the thesis, the problem of multi-site capacity planning under uncertainty in the pharmaceutical industry is addressed. A comprehensive two-stage, multi-scenario mixed-integer linear programming (MILP) model is proposed able to determine an optimal product portfolio and multi-site investment plan in the face of clinical trials uncertainty. A hierarchical algorithm is also developed in order to reduce the computational effort needed for the solution of the resulting large-scale MILP model. The applicability of the proposed solution methodology is demonstrated by a number of illustrative examples. The second part addresses the problem of business optimisation for customer demand management in process industries. A customer demand forecasting approach is developed based on support vector regression analysis. The proposed three-step algorithm is able to extract the underlying customer demand patterns from historical sales data and derive an accurate forecast as demonstrated through a number of illustrative examples. An active demand management approach for close substitute products is also developed based on price optimisation. The proposed methodology is able to determine optimal pricing policies as well as output levels, while taking into consideration manufacturing costs, resource availability, customer demand elasticity, outsourcing and market competition. An iterative algorithm is developed able to determine Nash equilibrium in prices for competing companies as demonstrated by the illustrative examples.
9

An investigation of computer integrated batch manufacturing processes in small and medium-sized enterprises (SMEs)

Si, Thu January 2000 (has links)
Global competition and improved manufacturing technologies have resulted in shorter product life cycles and smaller batch production with increasing product variations. Traditional batch manufacturing can never cater efficiently and effectively to the needs of ever changing markets. These changes and problems force small and medium-sized enterprises (SMEs) to look for adaptations and improvements in their manufacturing processes. Larger companies have resources to adapt to these changes, however SMEs face major obstacles such as a lack of finance, technology know-how and expertise. These difficulties are heightened by the fact that current technologies and research are tailored towards larger companies and pay little attention to the demands of SMEs. This research presents an integrated methodology intended specifically to assist SMEs in the design and selection of the most viable batch manufacturing system. The motivation for the research was twofold, firstly there was a need to transfer the advanced batch manufacturing technologies to SMEs through the applications of analytical hierarchy technique (AHP) and computer simulation which are generally used in larger companies, and utilise them effectively in their manufacturing processes. Secondly, the lack of a comprehensive and integrated methodology to deal with the major concerns faced by SMEs in adopting these technologies needed to be addressed. Unlike previous investigations, this study uses an approach which considers all facets of an SME including organisational, tactical, operational and financial issues. It attempts to address the complex problems of manufacturing system design by integrating a decision framework with the group technology concept and powerful computer tools. This is accomplished by the use of multi-criteria decision making, Group Technology, computer simulation and costs modelling tools and techniques. To validate the suitability of the methodology, an industrial case study with an SME engaged in discrete batch manufacturing was used. The results indicate that the research methodology is effective and useful for a number of reasons. Firstly, it is a generic system and can be tailored to fit the uniqueness of any SME. Also, it will assist in helping SMEs to understand the advanced technologies, ease the decision making process, facilitate the effective integration of information and the decision making process, reduce investment risks, and eventually achieve the introduction of a much needed "low cost system" to improve the competitiveness of manufacturing companies.
10

Workload control (WLC) : success in practice

Huang, Yuan January 2010 (has links)
Workload Control (WLC) is one of few Production Planning & Control (PPC) solutions appropriate for Make- To-Order (MTO) companies and Small & Medium sized Enterprises (SMEs), yet its successful implementation remains an enduring challenge. Much research attention has focused on developing the concept in a theoretical or simulation context; relatively little has focused on implementing the concept in practice, and more empirical evidence is needed on successful implementations. Of the few successful WLC implementations which have been published previously, the focus has been on the result of implementation while the process of implementation itself is still a 'black box'. Where more detail on the implementation process has been given in previous studies, evidence of effectiveness in practice has not been provided. To address this research gap, this thesis presents a successful implementation of a comprehensive WLC approach through action research; this is the first study which demonstrates the impact of WLC on performance in practice alongside a detailed account of the implementation process. Performance improvements observed include: reduced lead times; improvements in lateness and tardiness; reduced costs; improved internal and external co-ordination; and higher quality. In addition to details of this successful implementation, a wider body of evidence on the characteristics of MTO SMEs that affect WLC implementation has been obtained through a survey of 41 companies using semi-structured face-to-face interviews. This compensates for the limitation of a single case and adds an element of generality to the research findings. Thus, a generalised set of WLC specific implementation issues and an implementation strategy for the widespread adoption of WLC in practice has been developed.

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