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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

Techniques for the efficient solution of Large-scale production scheduling & planning problems in the process industries

Kopanos, Georgios 14 April 2011 (has links)
Nowadays, every company seeks to optimize its Supply Chain (SC) in response to competitive pressures or to acquire advantage of new flexibility in the restrictions on world trade. The process systems engineering research community has been aware of this change and is playing a key role in expanding the system boundaries from chemical process systems to business process systems. The global optimization of a SC network is an extremely complex task. For this reason, SC decisions are typically divided into three decision levels: the operational (scheduling), the tactical (planning), and the strategic (design). Since most academic developments are too distant from industrial environments, the aim of this thesis is to be a step forward in narrowing the gap between planning and scheduling theory and practice by devising efficient mathematical approaches for solving real-life industrial scheduling and planning problems. An overview of production planning and scheduling, an analysis of existing approaches, methods and tools used throughout this study are first presented. The second part of this thesis is focused on the development of mathematical models for production processes with continuous parallel units. In this part, a novel mathematical programming framework is developed based on elegant modeling of the underlying problem. This work addresses challenging problems in a highly complex real-life bottling facility. The proposed framework addresses appropriately important changeover aspects such as changeover carryover and crossover, thereby leading to solutions with resulting in higher utilization of resources. The third part is focused on semicontinuous industries, which combine continuous and batch operation modes. First, a mathematical programming framework and a solution strategy are presented for the optimal production scheduling of multiproduct multistage semicontinuous process industries. A problem in an ice-cream production line has been considered; and it has been successfully solved. Second, a general mathematical programming approach is developed for the resource-constrained production planning problem in semicontinuous processes. This work has been motivated by a challenging problem in food processing industries related to yogurt production lines, where labor constitutes the limited resource constraint. Third, a novel mathematical formulation for the simultaneous optimization of production and logistics operations planning in large-scale single- or multi-site semicontinuous process industries is proposed. Alternative transportation modes are considered. Two industrial-size case studies for a real-life dairy industry have been solved. The forth part of the thesis deals with scheduling in batch processes. First, a real-life multiproduct multistage pharmaceuticals production facility is considered. A systematic two-stage iterative solution strategy, based on mathematical programming, has been developed to address this problem. Additionally, a new precedence concept have been developed in order to cope with objectives containing changeover issues. A salient feature of the proposed approach is that the scheduler can maintain the number of decisions at a reasonable level, thus reducing the solution search space. This often ensures a more stable and predictable optimization model behavior. Finally, a preliminary two-layered decomposition method to the batch process scheduling problem in multipurpose production plants is developed. The procedure is tested on several instances of a benchmark scheduling problem that considers a polymers production plant. / Hoy en día, debido a que las condiciones económicas y políticas cambian rápidamente, las empresas globales se enfrentan a un desafío continuo para reevaluar constantemente y configurar de forma óptima las operaciones de su cadena de suministro (CS) para alcanzar los índices de rendimiento clave, tales como la reducción de costes de rentabilidad y servicio al cliente. Las empresas buscan optimizar sus CSs en respuesta a presiones de la competencia o para adquirir ventaja de una mayor flexibilidad en las restricciones sobre todo en el comercio mundial. Las industrias de proceso también siguen esta tendencia. La comunidad que investiga la ingeniería de los sistemas de procesos ha sido consciente de este cambio y, hoy en día, está jugando un papel clave en la expansión de los límites de los sistemas más allá de los procesos químicos para incluir también los sistemas de negocio. La optimización global de una red CS es una tarea extremadamente compleja. Por esta razón, las decisiones CS por lo general contemplan tres niveles de decisión: operativo (programación de operaciones), táctico (planificación de la producción) y estratégico (diseño). La planificación de la producción y la programación de operaciones constituyen una parte crucial de los niveles de decisión jerarquizados de la CS completa. Las actividades de planificación y programación tratan de la asignación en el tiempo de los recursos escasos entre actividades que compiten para satisfacer de forma eficiente dichas necesidades. Más concretamente, la función de planificación tiene como objetivo optimizar el rendimiento económico de la empresa, ya que debe hacer coincidir la producción con la demanda de la mejor manera posible. El componente de programación de la producción es de vital importancia ya que es la capa que traduce los imperativos económicos del plan en una secuencia de acciones a ser ejecutadas en la planta, con el fin de ofrecer el rendimiento económico optimizado previsto por el plan de alto nivel. En general, las investigaciones recientes se dirigen a la búsqueda de soluciones que permitan un manejo eficiente y preciso de problemas de gran tamaño y de complejidad cada vez mayor. Sin embargo, queda mucho trabajo por hacer tanto en las mejoras del modelo como en las mejoras en los algoritmos de solución del problema, cuando se trata de abordar de manera rutinaria problemas relevantes para la industria, donde el software producido debe ser utilizado de manera regular por los profesionales en el campo. Además, los nuevos desarrollos académicos son en su mayoría de cierta complejidad, pero relativamente de pequeño tamaño comparados con los problemas industriales incluso de mediano tamaño. Por lo tanto, la aplicación de nuevas estrategias de producción y nuevos enfoques de programación en los estudios industriales en la vida real constituye un reto difícil. Como la mayoría de los desarrollos académicos están demasiado lejos del entorno de aplicabilidad industrial, el objetivo de esta tesis es dar un paso significativo en la reducción del salto existente entre la teoría y la práctica de la planificación y programación mediante la elaboración de enfoques eficaces de programación matemática para la solución
2

The politics of the European social dimension : a comparative view of trade union demands in Britain and Germany

Weber, T. January 2000 (has links)
This thesis provides an assessment of the factors influencing the politics of the European social dimension. In recent years the debate on European social legislation has often assumed centre stage on the transnational and national policy agendas of many member states. However, compared with the rapid implementation of the measures aimed at bringing about the creation of the internal market, there has been little progress in the creation of a floor of European social rights which Jacques Delors had called for in 1989. This research seeks to highlight the determining factors behind the slow progress of the European social dimension. As the member state, through their representation at the European Council/Council of Ministers remain the prime decision-making powers, this study focused on the factors shaping decision-making in two member states, Britain and Germany. These two countries are held to represent different welfare state regime types (Esping-Andersen, 1990), divergent industrial relations systems and different styles of policy making. All the above factors have been held to shape policy outcomes in the social state and would therefore lead us to expect different approaches to the EC social dimension. The study equally seeks to assess claims that "trade union failure" is partly to blame for the lack of progress in European social policy making. Different authors have stressed their failure to adapt their organisational structures to the challenges of European integration. Different views represented between national affiliates and structural weakness of the trade unions were also considered to be important factors. Britain and Germany represent very different positions within the European Communities and towards the social dimension in particular. This is to some extent conditioned by their industrial relations and welfare state systems, but this cannot fully explain why certain positions are adopted in the Council. In Germany the economic challenges arising form the world recession and German unification have led to substantial changes in social policy making.
3

A map of transition in the South Wales Valleys

Lloyd-Jones, S. January 2005 (has links)
This thesis maps the education, training and employment experiences of fifty-four young adults in the South Wales Valleys. Over three years, at the turn of the twentieth century, it chronicled fifty-four school careers that led to no, or few qualifications; one hundred and twenty-three experiences of post-school learning programmes that had similarly poor outcomes; and one hundred and twenty-six jobs found and lost. The thesis looks at what happened to the young people through these experiences and uses their narratives to try and explore why it happened. Using theories of social and cultural capital it explores how, within a disadvantaged community, these young people are particularly disadvantaged. The study found that their experiences of education, training and employment promoted and reinforced a personal agency that prioritised the immediate over the planned, the tangible over the prospective and the known over the unknown. It also further embedded a localism that relied on social networks and shared cultural perspectives to provide support but that also confined them to an impoverished sub-section of the local labour market. The thesis concludes that learning can play a crucial role in securing a sustainable route out of poverty for these young people, and the forty children they had between them by the end of the study. However, to do so, the opportunities provided, and expectations of those providing them, will need considerable development. Learning has to find a way of working with, and not against, the cultural and social norms that have shaped these young people.
4

Learning disability staff and aggression from clients

Ivens, Mary January 1993 (has links)
This study was designed to investigate whether provision of information, in the form of a leaflet, about issues surrounding aggression and violence at work would lower anxiety about aggression and increase confidence in dealing with aggression, in care staff working in learning disability. A brief evaluation of the leaflet was carried out, and measures taken to establish whether information was assimilated from the leaflet. Also investigated were other feelings that care staff had about aggression at work. An information leaflet entitled "Preventing and coping with an aggressive incident involving a client in your care", and a questionnaire entitled "Aggressive incidents involving a client at work" were constructed. The questionnaire incorporated a scale for measuring 'Confidence in dealing with aggression'. 53 care staff, working in residential homes for people with learning disabilities, completed pre and post-intervention Spielberger State-Trait Form Y-1 questionnaires, and "Aggressive incidents involving a client at work" questionnaires. Results were analysed using analysis of variance, t-tests and Pearson's product moment correlation. No differences were found in levels of anxiety or confidence in dealing with aggression between two experimental groups and a control group, pre and post-intervention, but a significant difference was found in levels of anxiety within the groups pre and post-intervention. The leaflet was evaluated positively, but information was not assimilated. These and other findings are discussed in relation to present practice and implications for future research.
5

Participation and common-ownership : a study of employee participation in a common-ownership firm

Hadley, R. D. January 1971 (has links)
Employee participation in a itish oOtXI!non. OWnerShip firm is e the light of some of the major criticiams of workers' se1f-managemt. Thi'eG aspects of participation are isolated: employee involvement, the purposes of I involvement, arid, the control or influence exercised as a result of involvement. videnca on the nature and extent of participation is drawn from a study of the history of the first nine yeara of the common-ownership experiment, and from a field survey carried out in the firm at the end of te period. This evidence suggests that only a small minority of employees took an active part in the participative system of the organisa'tiori, that there was litti. unity of purpose amongst the nployees in their use of the system, aid that a relatively small degree of irifluenoe or control 'was exereised b,r employees over top mamagemente A model is outlined of the main factors hypothesised. to afjct involvement. These factors include employees' perceived needs, the perceived relevance of participative activities to the satisfaotioi of these needs, arid the perceived I costs of undertaking the activities in question. The low level of involvement identified in the firm studied is related. to a situation in which it appeare4 that the Imrticiative activities concerned were of united, relevance to many of the employees, and. that the participative system was likely to be seen as a 'high cost' one. Charges in the structure and leadership of the partic1pativ system are proposed to maxiuiise the relevance of involvement and mininise its costs, and. so provide the conditions for a more realistic exploration of the potential of self'management. Pinafly, an action research project is described which was carried out subsequently in the firm on the basis of this analysis. The findings of this project tend, to support the hypothesis advanced on tha factors effecting involvement. -
6

How could top-down and bottom-up approaches be used to explain recruitment and recognition of commercial bank staff in Barbados, from 1997 to present?

Babb, Jasmine Ianthi January 2013 (has links)
Top-down and bottom-up approaches for trade union organising have become popular debates in industrial relations and critical considerations for unions hoping for a renewed status. This study investigated recruitment and recognition of white-collar workers in commercial banks in Barbados during the period 1997 to present in terms of centralised/top-down and workplace/bottom-up union approaches. Case study design was used to examine this phenomenon in five commercial banks by conducting 32 face-to-face interviews with shop stewards, union officials and bank managers involved in the recruitment and recognition processes. Five focus groups were held with shop stewards and documents and archival information were also used. This thesis shows that the Barbados Workers’ Union had initially used a top-down approach to gain recognition in the commercial banks but was initially unsuccessful; however, organisational contexts such as restructuring/reorganising, mergers/acquisitions and a lack of grievance resolution resulted in employee grievances. These grievances included job security, pay equity, and a need for grievance resolution procedure and employee voice which were used by the rank-and-file activists in their bottom-up mobilisation. Evidence from the study showed that the top-down approach was supported by the bottom-up approach once the grievances were framed by activists at the workplace. The findings have shown that when management’s actions create conditions conducive to mobilisation and grievances result which are common to most staff, mobilisation is likely once rank-and-file activists are willing to agitate for unionisation. Further, that once this bottom-up approach supports the top-down approach in a multidimensional way that top-down and bottom-up could contribute to successful recruitment and recognition campaigns. Evidence from this research suggests that rank-and-file mobilisation should be considered along with top-down strategies to increase the chance of recognition. The study contributes to research on top-down and bottom-up approaches and particularly to understanding the workplace dimensions for mobilisation.
7

Noncompetitive labour markets, severance payments and unemployment

Fella, Giulio January 2000 (has links)
The dissertation analyses the possible welfare-enhancing role of severance payments when labour markets are non-competitive. Chapter 1 introduces the material in the thesis. Chapter 2 presents a short survey of the results of the existing literature on dismissal costs. Chapter 3 uses a strategic bargaining model to show that, once dismissal costs are correctly modelled as a payment which takes place only in case firms sever the relationship, firing costs cannot affect the separation rate in models featuring voluntary severance in the absence of restrictions. Firms will always find it profitable to induce workers to quit whenever separation is efficient. Only if some other source of inefficiency prevents firms and workers to split the rents from continuation can firing costs result in a reduced number of separations. In this case they may be efficient. Chapter 4 analyses non-contractible firms' investment in general training in the presence of frictional unemployment. It argues that consensual layoff measures and other institutions that oblige firms to share the total separation payoff result in higher training. Since general training is vested in the worker on separation, in the absence of such measures, the firm would not capture any return to training in case of separation. Chapter 5 shows that in a dynamic efficiency wage model the time-inconsistency of firing decisions implies that severance payments increase aggregate employment and are second-best Pareto optimal as they induce firms to internalise the negative externality, in the form of foregone rents, that they impose on workers on severance. Chapter 6 concludes.
8

The effects of competitive pressures on labour market institutions and economic performance : a cross-country comparative study

Kang, Tae Young January 1992 (has links)
Traditionally, industrial relations have been studied with relation to three fundamental theories: pluralism, unitarism and marxism. However, over the past decade there has been an increasing contribution to industrial relations emanating from the boundaries of other disciplines: principally economics, organizational behaviour and business strategy. Among economists, and to a lesser extent, business strategists, there has been a growing concern about the relationship between macro-economic performance across several countries and labour market institutions. This has manifested itself in discussion of how specific wage bargaining structures influence unemployment and inflation. In these discussions industrial relations specialists appear to lag behind their economist colleagues, tending to favour analysis of the intrinsic relations between employers and employees. An important advantage, however, of these studies in employee relations has been in their ability to explain the conduct of an industrial relations system. This has not led to any consensus and few of the studies conducted in the past decade have investigated the strategic behaviour of both employers and employees. None have attempted to examine the macroeconomic implications of behaviourial changes and wage bargaining. This thesis builds on work already in train in a number of disciplines: principally industrial relations, business strategy, organizational behaviour and labour economics. Cognisant of the work in these areas, the study develops a theory which explains how perceived and actual increases in international competition influence the choice which employers and employees make and which eventually shape their institutions. By departing from the traditional theoretical constructs used in industrial relations, our "new" theory provides a basis for cross-country comparisons of macro-economic effects of labour relations behaviour. From our theory we devise testable propositions and draw a wide variety of time series data over a period of some twenty years, from seventeen O.E.C.D. economies to test these. These data, which lend themselves to econometric analysis, are augmented by qualitative evidence from case studies. Findings support our theory. The thesis makes three distinct contributions. Firstly, it suggests a "new" theoretical approach to the study of industrial relations which combines work from several disciplines. In this regard, it contributes a theory which explains labour market changes by recourse to macro-economic performance. Secondly, it makes a contribution, albeit modest, to policy, suggesting that some current Western policies for labour relations are inadequate since they do not clearly show employers and employees the actual implications of macro-economic performance. Thirdly, the thesis highlights some of the shortcomings of econometric studies which focus on a relatively narrow set of variables at the exclusion of qualitative data which is difficult to quantify.
9

The persistence of the internal labour market in changing circumstances : the british film production industry during and after the closed shop

Reid, Iain January 2008 (has links)
Internal labour market theory states that the administrative rules and customs that restrict access and regulate the deployment of labour in craft markets will eventually be converted by trade unions into formal collective agreements, preferably enforced by closed shops. However there have been few opportunities to examine what happens when that process is reversed and the protection of those two institutions are removed. The demise of the closed shop in Britain is generally attributed to Mrs Thatcher's Conservative governments whose successive Employment Acts were intended to remove obstacles to the free functioning of the labour market. However, this research will argue, using the example of the British film production industry, that regardless of the political action it is unlikely that the pre-entry closed shop would have survived the technical and social changes of the 1980s. It also shows that many of the constraining practices and principles associated with the industry's internal labour market persist. By tracing the origins of organised labour in the early British film production industry, this research considers whether that closed shop, created by unusual wartime circumstances, merely endorsed the informal rules and customs that characterised an established closed craft community. It will demonstrate that continuity has been possible because internal labour market practices ensure that on-the-job training is only available to those likely to perpetuate the established working practices and demarcation. Furthermore, management are complicit because the efficiencies in screening and training means that a compatible trained workforce is always available. For contrast, it will be shown that in television and video production, seemingly similar sectors, an unrestricted, competitive labour market has been created by the demise of the closed shop, the workers' inability to create a substitute informal network, the unbridled influence of capital and government efforts to assist access to employment.
10

The economics of unfair dismissal in the United Kingdom, and other topics in public policy

Marinescu, Ioana Elena January 2007 (has links)
Workers and firms face substantial uncertainties about their prospects in the labor and product markets. The first three chapters of this thesis analyze how firing costs affect firms' behavior and workers' outcomes in the face of uncertainty about match quality and changing economic conditions. In the final chapter, I show how macroeconomic policy can reduce the risks associated with changing economic conditions. First, I examine a 1999 UK reform that lowered from two years to one year the tenure necessary for a worker to be able to sue their employer for unfair dismissal. After the reform, we observe a significant decrease in the firing hazard for workers with zero to two years tenure relative to the control group, and no overall increase in unemployment. Using a simple model based on the assumption that firms learn about match quality over time, I show that the empirical results are consistent with increased match quality after the reform. Second, I generalize the simple model developed in the first chapter. In particular, I allow for match quality to change over time. The model is useful to understand and predict how firing costs and various forms of uncertainty affect the separation hazard. Thirdly, I analyze the implementation of unfair dismissal legislation by judges in the UK. Judges seem to compromise between workers' and firms' interests. If workers are unemployed, judges decide more often in their favour when unemployment rates are higher. The reverse is true when workers have found a new job. Finally, in work co-authored with Philippe Aghion, we examine whether the government borrowing and spending more in recessions can increase growth by relaxing economic agents' credit constraints. Using a panel data of OECD countries, we find that indeed countercyclical public debt policy is more growth enhancing when private credit is less abundant.

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