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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.
11

Making Sense of Rework Causation in Offshore Hydrocarbon projects

Love, P.E.D., Ackerman, F., Smith, J., Irani, Zahir, Edwards, D.J. January 2016 (has links)
No / Retrospective sensemaking is used to determine how and why rework in offshore hydrocarbon projects occurred. Staff from organizations operating at the blunt end (e.g., clients/design engineers providing finance and information) and those at the sharp end (e.g., contractors at the “coalface”) of a project's supply chain were interviewed to make sense of the rework that occurred. The analysis identified the need for managers to de-emphasize an environment that prioritizes production over other considerations and instead systematically examine mechanisms and factors that shape people's performance. Limitations of the research and the implications for managerial practice are also identified.
12

Causes of rework on building construction projects in Nigeria

Aiyetan, A.O. January 2013 (has links)
Published Article / Construction projects all over the world involve many challenges, particularly for large public projects. The emerging complex nature of construction activities has brought with it characteristic features, such as, cost increases, delay in the delivery of project, to which rework (carrying out an activity more than one time) has a high contributing factor, stemming from imperfection. This study identified the sources of rework on construction projects in Nigeria from three perspectives: the client, contractor, and consultant. The study was concentrated on the South West part of Nigeria. The quantitative research method was adopted. Random sampling technique was employed in the selection of sample size. A total of one hundred and twenty (120) questionnaires were analysed using inferential statistics. The following are the findings of this study: the contributions of the client leading to rework are in the form of poor communication, inadequate construction planning and poor management practices. From the consultant, they are: lack of understanding and correct interpretation of customer requirements, constraints in carrying out activities and inexperience of personnel and on the part of the contractor they are: wrongly laying of forming course, poor quality concrete, and poor plastering. Based on the conclusions reached, the following recommendations were drawn. They are: the development of a standard information gathering format relative to clients 'by designers and clients' writing down their intentions before visiting designers; formal technical training should be given to foremen on permanent appointments with organisations, attention should be given for adequate supervision, and construction methods should be analysed before selection and their use.
13

Implementation and Certification of ISO/IEC 29110 in an IT Startup in Peru

García Paucar, Luis Hernán, Laporte, Claude Y, Arteaga, Yaylli, Bruggmann, Marco 18 March 2015 (has links)
This article presents the implementation of ISO/IEC 29110 in a four-person IT startup company in Peru. After completing the implementation of the ISO/IEC 29110 project management and software implementation processes using an agile approach, the next step was to execute these processes in a project with an actual customer: software that facilitates communication between clients and legal consultants at the second-largest insurance companies in Peru. Managing the project and developing the software took about 900 hours. Using ISO/ IEC 29110 software engineering practices enabled the startup to plan and execute the project while expending only 18 percent of the total project effort on rework (i.e., wasted effort). In this article, the authors also describe the steps and the effort required by the VSE to be granted an ISO/IEC 29110 certificate of conformity. The startup became the first Peruvian VSE to obtain an ISO/IEC 29110 certification. The ISO/IEC 29110 certification facilitated access to new clients and larger projects.
14

Caracterizações microestruturais e avaliações das propriedades mecânicas das juntas em aço inoxidável AISI 301 L soldadas por MIG e submetidas ao reparo pelo processo TIG / Microstructural characterization and evaluation of mechanical properties of joints in steel AISI 301 L welded by MIG and submitted to repair by TIG process

Souza, Edvaldo Roberto de 27 April 2012 (has links)
A soldagem tem grande importância no setor metroferroviário, pois é empregada na fabricação de componentes estruturais e no acabamento de vagões de passageiros, que em sua maior parte são de aço inoxidável. As juntas soldadas podem apresentar descontinuidades que são interrupções que afetam as propriedades mecânicas e metalúrgicas da junta soldada. A presença destas descontinuidades, dependendo do seu tamanho, natureza ou efeito combinado, pode ocasionar a reprovação da junta soldada, quer pela redução de propriedades mecânicas ou pela não aceitação, segundo critérios estabelecidos em normas. Uma estrutura que tenha uma solda reprovada durante sua qualificação ou inspeção, pela presença de descontinuidades pode ser recuperada, por meio de um retrabalho a ser realizado nesta junta. A refusão do cordão de solda por meio do processo TIG (Tungsten Inert Gas), sem a utilização do material de adição, é uma técnica de retrabalho que pode ser empregada, em especial pela viabilidade técnica e econômica do processo. Neste estudo analisou-se a influência que o processo de reparo por soldagem TIG exerceu no comportamento mecânico e microestrutural das juntas soldadas pelo processo MIG, por meio de: ensaios mecânicos (tração, fadiga e microdureza Vickers), ensaios não destrutivos (inspeção visual e líquidos penetrantes) e caracterização microestrutural do cordão de solda. Resultados das amostras de ensaio de tração e fadiga indicaram que o reparo dos cordões de solda não alterou o comportamento mecânico das juntas. As juntas submetidas ao reparo nas quais foram retirados os reforços dos cordões apresentaram modificações nas propriedades mecânicas, mas também apresentaram resultados satisfatórios. / The welding has great importance in manufacture of subway cars because it is used in the manufacture of structural components and finishing in passenger cars which are mostly stainless steel. Joints may show the presence of discontinuities. The discontinuities are interruptions that affect the mechanical and metallurgical properties of the weld. The presence of these discontinuities, depending on their size, nature or the combined effect may lead to failure of the weld either by reduction of mechanical properties or non-acceptance criteria established in standards. A structure that has a weld failed during its qualification or inspection by the presence of discontinuities can be retrieved through a rework to be done in this joint. The remelting of the weld using the TIG process without the use of additional material, rework is a technique that can be employed in particular the technical and economic feasibility of the process. This study analyzes the influence that the process of TIG welding rework has on mechanical behavior and microstructure of welded joints by means of: mechanical tests (tensile and Vickers hardness), non-destructive testing (visual inspection and liquid penetrant) and characterization microstructure of the weld. Results of tensile test specimens and fatigue indicated that the repair of the weld beads did not change the mechanical behavior of joints. The joints subjected to repair in which they were removed the ribs of the beads showed changes in the mechanical properties, but also had satisfactory results.
15

Proposta de método de controle integrado entre produção e qualidade com mensuração de perdas por making-do e pacotes informais

Fireman, Marcus Costa Tenorio January 2012 (has links)
O controle de perdas tem sido apontado como uma das principais estratégias para melhoria do desempenho e para redução de custos de sistemas de produção. Entretanto, apesar de sua importância, este é um tema pouco abordado na literatura sobre gestão da construção, principalmente no que se refere a sistemas de controle da produção. Alguns estudos recentes chamaram a atenção para a existência de uma perda típica do setor, denominada de making-do, a qual pode ser definida como a redução de desempenho do sistema produtivo devido à execução de atividades em condições subótimas. Este tipo de perda ainda tem sido apontada como uma das causas fundamentais de problemas da qualidade, e de outras perdas, tais como retrabalho e trabalho em progresso. Falhas na análise de restrições realizadas no planejamento de médio prazo têm sido apontadas como a principal razão para o surgimento de perdas por making-do, pois na ausência dos requisitos necessários para execução das atividades normalmente as equipes realizam improvisações, que podem afetar o desempenho da produção. O presente trabalho propõe um método de controle integrado produção e qualidade que permita mensurar perdas por making-do e também a ocorrência de pacotes de trabalho informais. Este método está dividido em três módulos: (a) identificação de perdas por making-do; (b) identificação de pacotes informais; e (c) controle integrado produção e qualidade. O desenvolvimento da pesquisa foi dividido nas seguintes etapas: (a) compreensão do problema; (b) estruturação do método; (c) consolidação do método; (d) avaliação dos resultados e proposição do método final. Como principais contribuições do trabalho, além do próprio método proposto, o estudo propõe uma conceitualização de perdas por making-do, retrabalho e falta de terminalidade. Ainda, os resultados demonstram a existência de uma forte relação entre as perdas por making-do, a execução de pacotes informais e o aumento do trabalho em progresso. / Waste control has been pointed out as one of the key strategies for improving the performance and reducing costs of production systems. However, despite its importance, this is a topic poorly discussed in the construction management literature, especially in relation to production control systems. Some recent studies have called the attention for a type of waste that is typical of the construction sector, named making-do, which can be defined as a loss in performance due to the execution of activities in sub-optimal conditions. It has been suggested that this type of waste is one of the root causes of quality failures, and also of other types of waste, such as rework and work in progress. Failures in constraint analysis at the medium term planning level have been pointed out a major cause of makingdo waste, as the crews tend to improvise when faced with the lack of prerequisites for the execution of tasks, which may affect the production performance. This research work proposes a method for integrated production and quality control, which enables the measurement making-do waste and also the occurrence of informal work packages This method is divided into three modules: (a) identification of making-do waste; (b) identification of informal work packages; and (c) integrated and production and quality control. The development of this research work was divided into the following stages: (a) understanding the problem; (b) structuring the method; (c) consolidating the method; (d) evaluation of results and proposition of the final version of the method. As main contributions, besides the integrated control method, this investigation proposes a conceptualization for three categories of waste: making-do, rework, and unfinished work. Moreover, the results indicate that there is a strong relationship making-do waste, the execution of informal packages and the increase of work in progress.
16

Improved Schedule Analysis Considering Rework Impact and Optimum Delay Mitigation

Said, Mohamed January 2009 (has links)
Rework has been a primary cause of cost and schedule overruns in the construction of heavy industrial projects such as those related to oil and gas. It has been reported that the direct cost of rework is about 5% of total construction costs. Several research studies have analyzed the causes and effects of rework in construction projects, but almost no research exists to support decisions with respect of an effective strategy for mitigating the effects of rework on the cost and schedule of the project. This research introduces a new schedule analysis mechanism that considers the impact of rework on project delays and then optimises corrective actions for mitigating those delays. The proposed mechanism considers rework from three perspectives: (1) a schedule representation of the magnitude of rework as a negative percentage completed with respect to the activities affected, as documented on a specific schedule date, (2) a day-by-day delay analysis for quantifying and apportioning project delays among the parties responsible, and (3) an optimization mechanism for determining the best mitigation strategy for recovering rework at a minimum additional cost. The proposed mechanism can represent and mitigate rework caused by both the Owner and the Contractor. The proposed schedule analysis mechanism has been applied to a case study in order to demonstrate its usefulness and applicability. The resulting mechanism offers a quantitative approach to the consideration of rework in delay analysis and the optimization of corrective action, which are important aspects of effective project control.
17

Improved Schedule Analysis Considering Rework Impact and Optimum Delay Mitigation

Said, Mohamed January 2009 (has links)
Rework has been a primary cause of cost and schedule overruns in the construction of heavy industrial projects such as those related to oil and gas. It has been reported that the direct cost of rework is about 5% of total construction costs. Several research studies have analyzed the causes and effects of rework in construction projects, but almost no research exists to support decisions with respect of an effective strategy for mitigating the effects of rework on the cost and schedule of the project. This research introduces a new schedule analysis mechanism that considers the impact of rework on project delays and then optimises corrective actions for mitigating those delays. The proposed mechanism considers rework from three perspectives: (1) a schedule representation of the magnitude of rework as a negative percentage completed with respect to the activities affected, as documented on a specific schedule date, (2) a day-by-day delay analysis for quantifying and apportioning project delays among the parties responsible, and (3) an optimization mechanism for determining the best mitigation strategy for recovering rework at a minimum additional cost. The proposed mechanism can represent and mitigate rework caused by both the Owner and the Contractor. The proposed schedule analysis mechanism has been applied to a case study in order to demonstrate its usefulness and applicability. The resulting mechanism offers a quantitative approach to the consideration of rework in delay analysis and the optimization of corrective action, which are important aspects of effective project control.
18

A Linear Programming Approach To Quality Improvement Project And Product Mix Selection Under Inspection Error And Rework

Sarbak, Nedret 01 August 2006 (has links) (PDF)
In this study, the effect of inspection error on the product mix and quality projects selection in a manufacturing environment where rework and inspection errors exist is examined. It is assumed that the products (items) for which rework is necessary are reprocessed at a separate work center and 100% inspection is performed for the products both after rework and processing operations. Markov chain approach is used to compute yield and rework rates. In addition, nominal-the-best type of a quality loss function is used in computing quality loss due to products shipped to the customers. A linear programming (LP) model is developed to support the product mix and quality improvement project selection decisions. The use of LP model is demonstrated on an example problem. The results obtained under different experimental conditions are compared with solutions of a naive QI project selection method, improving the least capable process. The analysis shows that developed LP model is relatively better than process capability approach. Besides, according to the results obtained under different experimental conditions, the factors that have significant effect on throughput and QI project selection are being determined.
19

A Decision Matrix Based Method For Determining Priorities Of Quality Improvement Projects In Manufacturing With Inspection Error And Rework

Dolgun, Leman Esra 01 December 2006 (has links) (PDF)
Today&rsquo / s competitive environments and heightened expectation of customers make it necessary to improve quality of products and processes continuously. Therefore, quality improvement is a major concern for companies. Determining improvement priorities for not only long but also short term bottom line results is a key problem in quality improvement management. In this thesis a practical decision matrix based method is developed for selecting quality improvement projects by considering throughput and quality loss in manufacturing environments with inspection error and rework. Performance of the proposed method under different experimental conditions is analyzed and results are discussed.
20

Developing a procedure to optimise cycle time in a manufacturing plant / Venter J.P

Venter, Johannes Petrus January 2011 (has links)
Productivity advances generated from ‘lean manufacturing’ are self–evident. Plants that adopt ‘lean’ are more capable of achieving shorter lead times, less waste in the system and higher quality levels. The goal of this study was to ascertain which ‘lean’ tools and techniques are available for use. A matrix was constructed with a summation of the authors who agree that specific ‘lean’ tools will reduce cycle time. It was found that reduced set–up time and waste elimination are most affected by the implementation of ‘lean’ tools and techniques. An empirical study was conducted to confirm the results of the literature study. The respondents’ knowledge on the ‘lean’ tools was also tested. It was found that respondents have a sound understanding of set–up time; they agree that it must be reduced in the plant. Pre–scientific evidence and the response from the empirical study confirm that there is a substantial amount of waste in the factory. A current state value–stream map was drawn from a single welded part Product X. The value–stream was analysed to reduce the cycle time in the process, with the focus on set–up time reduction and waste elimination. The future state value–stream map was drawn, displaying astonishing results. A continuous improvement (kaizen) programme will help reduce the cycle time even further by making use of the other ‘lean’ tools discussed in this study. This programme forms part of the procedure to optimise cycle time. / Thesis (M.B.A.)--North-West University, Potchefstroom Campus, 2012.

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