An Empirical Analysis of Manufacturing Overhead Cost Drivers

Empirical validity of the claim that overhead costs are driven not by production volume but by transactions resulting from production complexity is examined using data from 32 manufacturing plants from the electronics, machinery, and automobile components industries. Transactions are measured using number of engineering change orders, number of purchasing and production planning personnel, shop- floor area per part, and number of quality control and improvement personnel. Results indicate a strong positive relation between manufacturing overhead costs and both manufacturing transactions and production volume. Most of the variation in overhead costs, however, is explained by measures of manufacturing transactions, not volume.

Desenvolvimento de um sistema para planeamento e controlo da produção

Atualmente o sector industrial está inserido num mercado cada vez mais competitivo, onde é exigida uma estratégia empresarial que possa garantir a sua permanência e destaque no atual mercado. Por esta razão, um planeamento e controlo da produção adequado torna-se essencial para o bom funcionamento de uma empresa. Através destes sistemas é possível atuar de forma positiva na produção, rentabilizando-se o sector produtivo da empresa que contribui para o aumento da qualidade de serviço e também para o crescimento económico da empresa. Com um planeamento da produção adequado, uma organização dispondo das mesmas capacidades, é capaz de produzir quantidades iguais num menor intervalo de tempo. Por outro lado, um controlo da produção preciso é imprescindível para o fornecimento da informação correta quando necessária. No sentido de otimização, uma empresa apresentou algumas sugestões de melhoria a nível do planeamento e controlo da produção. Este trabalho surge assim com o intuito de dar resposta às propostas apresentadas. Para tal, no desenvolvimento desta dissertação, criou-se uma ferramenta dotada de dois algoritmos e um sistema de controlo para aquisição de informação de forma automatizada. Em suma, o sistema proposto apresenta a capacidade de construção de boas soluções para o planeamento, conciliada com um sistema de aquisição de dados bastante prático e e caz. Mantendo sempre a exibilidade necessária para um sistema deste género.

Modelo para formação dinâmica de rede de fornecedores em empresas estendidas

Supply chains have become an important focus for competitive advantage. The performance of a company increasingly depends on its ability to maintain effective and efficient relationships with its suppliers and customers. The extended enterprise (i.e. composed of several partners) needs to be dynamically formed in order to be agile and adaptable. According to the Digital Manufacturing paradigm, companies have to be able to quickly share and disseminate information regarding planning, designing and manufacturing of products. Additionally, they must be responsive to all technical and business determinants, as well as be assessed and certified for guaranteed performance. The current research intends to present a solution for the dynamic composition of the extended enterprise, formed to take advantage of market opportunities quickly and efficiently. A construction model was developed. This construction model consists of: information model, protocol model and process model. The information model has been defined based on the concepts of Supply Chain Operations Reference model (SCOR®). In this model is defined information for negotiating the participation of candidate companies in the dynamic establishment of a network for responding to a given demand for developing and manufacturing products, in seven steps as follows: request for information; request for qualification; alignment of strategy; request for proposal; request for quotation; compatibility of process; and compatibility of system. The protocol model has been elaborated and inspired in the OSI, this model provides a framework for linking customers and suppliers, indicates a sequence to be followed, in order to selecte companies to become suppliers. The process model has been implemented by means of process modeling according to the BPMN standard and, in turn, implemented as a web-based application that runs the process through its several steps, which uses forms to gather data. An application example in the context of the oil and gas industry is used for demonstrating the solution concept.

Heurística de programação da produção para uma indústria cerâmica

Atualmente, uma organização industrial com vista a singrar no mercado global é fortemente influenciada por pressões que visam o aumento da eficiência global e consequente redução de custos operacionais. O desafio para as mesmas passa, portanto, por expurgar do produto tudo aquilo que não lhe acrescenta valor percetível pelo cliente e por maximizar a utilização dos vários recursos industriais instalados. No seguimento deste desafio, surge o Problema de Planeamento e Programação da Produção, ao qual é necessário dar uma resposta eficiente. Este projeto tem como objetivo estudar o problema da Programação da Produção numa indústria de pavimentos e revestimentos cerâmicos, desenvolvendo uma heurística construtiva capaz de traduzir com fiabilidade a realidade do processo produtivo da mesma e, se possível, auxiliar na sua resolução. O problema da programação da produção em estudo visa responder às questões: o quê, em que quantidade, quando e em que linha produzir, por forma a satisfazer as necessidades dos clientes num prazo previamente estipulado como admissível, garantindo o enchimento dos fornos ligados. Sem grandes constrangimentos ao normal lavor da Produção, pretende obter-se com a heurística planos de produção viáveis, que minimizem o tempo necessário para a conclusão do conjunto de referências com necessidades produtivas. O problema é também abordado através de um modelo exato como um problema de máquinas paralelas idênticas capacitado, com matriz de compatibilidades, setups de família e de subfamília e com lotes mínimos de produção. Quer a heurística quer o modelo de programação inteira mista desenvolvidos permitem obter planos de produção válidos, equivalentes aos obtidos atualmente pela empresa através dos meios de programação atuais, embora com um dispêndio de tempo muito inferior.

Exact solutions for the agricultural and the two-dimensional packing problems

Objectives and study method: The objective of this study is to develop exact algorithms that can be used as management tools for the agricultural production planning and to obtain exact solutions for two of the most well known twodimensional packing problems: the strip packing problem and the bin packing problem. For the agricultural production planning problem we propose a new hierarchical scheme of three stages to improve the current agricultural practices. The objective of the first stage is to delineate rectangular and homogeneous management zones into the farmer’s plots considering the physical and chemical soil properties. This is an important task because the soil properties directly affect the agricultural production planning. The methodology for this stage is based on a new method called “Positions and Covering” that first generates all the possible positions in which the plot can be delineated. Then, we use a mathematical model of linear programming to obtain the optimal physical and chemical management zone delineation of the plot. In the second stage the objective is to determine the optimal crop pattern that maximizes the farmer’s profit taken into account the previous management zones delineation. In this case, the crop pattern is affected by both management zones delineation, physical and chemical. A mixed integer linear programming is used to solve this stage. The objective of the last stage is to determine in real-time the amount of water to irrigate in each crop. This stage takes as input the solution of the crop planning stage, the atmospheric conditions (temperature, radiation, etc.), the humidity level in plots, and the physical management zones of plots, just to name a few. This procedure is made in real-time during each irrigation period. A linear programming is used to solve this problem. A breakthrough happen when we realize that we could propose some adaptations of the P&C methodology to obtain optimal solutions for the two-dimensional packing problem and the strip packing. We empirically show that our methodologies are efficient on instances based on real data for both problems: agricultural and two-dimensional packing problems. Contributions and conclusions: The exact algorithms showed in this study can be used in the making-decision support for agricultural planning and twodimensional packing problems. For the agricultural planning problem, we show that the implementation of the new hierarchical approach can improve the farmer profit between 5.27% until 8.21% through the optimization of the natural resources. An important characteristic of this problem is that the soil properties (physical and chemical) and the real-time factors (climate, humidity level, evapotranspiration, etc.) are incorporated. With respect to the two-dimensional packing problems, one of the main contributions of this study is the fact that we have demonstrate that many of the best solutions founded in literature by others approaches (heuristics approaches) are the optimal solutions. This is very important because some of these solutions were up to now not guarantee to be the optimal solutions.

Scheduling the repair of aircraft components - a case study

In aircraft components maintenance shops, components are distributed amongst repair groups and their respective technicians based on the type of repair, on the technicians skills and workload, and on the customer required dates. This distribution planning is typically done in an empirical manner based on the group leader’s past experience. Such a procedure does not provide any performance guarantees, leading frequently to undesirable delays on the delivery of the aircraft components. Among others, a fundamental challenge faced by the group leaders is to decide how to distribute the components that arrive without customer required dates. This paper addresses the problems of prioritizing the randomly arriving of aircraft components (with or without pre-assigned customer required dates) and of optimally distributing them amongst the technicians of the repair groups. We proposed a formula for prioritizing the list of repairs, pointing out the importance of selecting good estimators for the interarrival times between repair requests, the turn-around-times and the man hours for repair. In addition, a model for the assignment and scheduling problem is designed and a preliminary algorithm along with a numerical illustration is presented.

Planning Urban Food Production into Today’s Cities

If cities are to become more sustainable and resilient to change it is likely that they will have to engage with food at increasingly localised levels, in order to reduce their dependency on global systems. With 87 percent of people in developed regions estimated to be living in cities by 2050 it can be assumed that the majority of this localised production will occur in and around cities. As part of a 12 month engagement, Queen’s University Belfast designed and implemented an elevated aquaponic food system spanning the top internal floor and exterior roof space of a disused mill in Manchester, England. The experimental aquaponic system was developed to explore the possibilities and difficulties associated with integrating food production with existing buildings. This paper utilises empirical research regarding crop growth from the elevated aquaponic system and extrapolates the findings across a whole city. The resulting research enables the agricultural productive capacity of today’s cities to be estimated and a framework of implementation to be proposed.

Planning Urban Food Production into Today's Cities

If cities are to become more sustainable and resilient to change it is likely that they will have to engage with food at increasingly localised levels, in order to reduce their dependancy on global systems. With 87 percent of developed regions estimated to be living in cities by 2050 it can be assumed that the majority of this localised production will occur in and around cities.
As part of a 12 month engagement, Queen’s University Belfast designed and implemented an elevated aquaponic food system spanning the top floor and exterior roof space of a disused mill in Manchester, England. The experimental aquaponic system was developed to explore the possibilities and difficulties associated with containing fish tanks, filtration units, vertical growing systems and roof top growing systems within and upon existing buildings, including the structural considerations needed when undertaking such transformations. Although capable of producing 4000 crops at any one time, the elevated aquaponic system utilised space within the existing building, which could otherwise be used as lettable area, and also located some crop growth within the building where light levels are reduced.
The following paper takes the research collected from the elevated aquaponic system and extrapolates the findings across a whole city. The resulting research enables the agricultural productive capacity of todays cities to be determined and a frame work of implementation to be developed for city wide food production. The research focuses specifically on facade and roof based systems, thus elevating the need to utilise lettable area within cities in addition to locating crops where light levels are highest.

Planning Urban Food Production into Today's Cities

If cities are to become more sustainable and resilient to change it is likely that they will have to engage with food at increasingly localised levels, in order to reduce their dependency on global systems. With 87 percent of people in developed regions estimated to be living in cities by 2050 it can be assumed that the majority of this localised production will occur in and around cities. As part of a 12 month engagement, Queen’s University Belfast designed and implemented an elevated aquaponic food system spanning the top internal floor and exterior roof space of a disused mill in Manchester, England. The experimental aquaponic system was developed to explore the possibilities and difficulties associated with integrating food production with existing buildings. This paper utilises empirical research regarding crop growth from the elevated aquaponic system and extrapolates the findings across a whole city. The resulting research enables the agricultural productive capacity of today’s cities to be estimated and a framework of implementation to be proposed.

Understanding safety and production risks in rail engineering planning and protection

Much of the published human factors work on risk is to do with safety and within this is concerned with prediction and analysis of human error and with human reliability assessment. Less has been published on human factors contributions to understanding and managing project, business, engineering and other forms of risk and still less jointly assessing risk to do with broad issues of ‘safety’ and broad issues of ‘production’ or ‘performance’. This paper contains a general commentary on human factors and assessment of risk of various kinds, in the context of the aims of ergonomics and concerns about being too risk averse. The paper then describes a specific project, in rail engineering, where the notion of a human factors case has been employed to analyse engineering functions and related human factors issues. A human factors issues register for potential system disturbances has been developed, prior to a human factors risk assessment, which jointly covers safety and production (engineering delivery) concerns. The paper concludes with a commentary on the potential relevance of a resilience engineering perspective to understanding rail engineering systems risk. Design, planning and management of complex systems will increasingly have to address the issue of making trade-offs between safety and production, and ergonomics should be central to this. The paper addresses the relevant issues and does so in an under-published domain – rail systems engineering work.

Sticking to the script? The co-production of Neighbourhood Planning in England

Efforts to engage with communities in spatial planning have been criticised as being tokenistic, vehicles for co-option or designed to promote neo-liberal agendas. The introduction of neighbourhood planning (NP) in England under the Localism Act (2011) is claimed by proponents to be a step change in the way that local communities are involved in planning their own areas. However, little empirical evidence has yet emerged to substantiate such claims, or provide details about the practices and experiences of NP. The paper highlights that there are numerous parties involved in the co-production of Neighbourhood Development Plans and there are numerous instances where ideas, policies and priorities that emerge from within neighbourhoods are being ‘rescripted’ to ensure conformity to a bounded form of collaboration.