Thesis (Master)--İzmir Institute of Technology, İzmir, 2006. / Keywords: Concurrent design, industrial design. Includes bibliographical references (leaves. 63-69).

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Concurrent computations have been modeled using partial orders in both event based and state based domains. We give necessary and sufficient conditions on partial orders for them to be valid state based or event based models of concurrent computations. In particular, we define notions of width-extensibility and interleaving-consistency of partial orders, and show that a partial order can be valid state based model of a concurrent computation iff it is width-extensible. Distributed computations that involve asynchronous message passing are a subset of concurrent computations. For asynchronous distributed computations, a partial order can be a valid state based model iff it is width-extensible and interleaving-consistent. We show a duality between the event based and state based models of concurrent computations, and give algorithms to convert partial orders from the event based domain to state based domain and vice-versa. / text

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Global competitiveness challenges manufacturing industry to bring to market well designed and manufactured new products at competitive prices, in as short a lead time as possible. To achieve this, inputs are needed from experts in a multitude of disciplines as well as from customers and suppliers. The overall design must be well orchestrated and integrated which has led to the evolution of the philosophy of Concurrent Engineering where the decisions about different aspects related to the product's life cycle, must be considered simultaneously. While the use of design teams is achieving some success there is a need for modern software tools which support the design process to be radically improved. Typically design for manufacture software systems provide only support for a single process e.g. design for assembly, design for machining, design for fixturing etc. However, when the full breadth of design for manufacture is considered there are many aspects that must be addressed. This leads to the need for information systems to be able to support multiple views of a product, where each view provides the appropriate representation to support at least one manufacturing perspective. This research has investigated the potential of product model based systems to support multiple viewpoints in Design for Manufacture. The research has focused on the design for manufacture of plastic injection moulded products and has explored the particular viewpoints of mouldability, mould design and mould manufacturing. The approach taken has been to explore particular information structures to support each Design for Manufacture application. Subsequently, the relationships between these information structures have been investigated and sets of translating mechanisms to convert information from one view to another have been designed. An experimental Product Model has been implemented using an object-oriented database. This contains a mouldability view, cavity and core design views and cavity and core machining views. Translation mechanisms between views have been implemented using Visual C++ language. The concept and implementation of this research have been tested through experiments using both rotational and prismatic products. This research has therefore shown that multiple viewpoint design for manufacturing can be supported by a combination of product model data structures and specific sets of translation mechanisms.

Concurrent construction, in which multiple construction activities are carried out concurrently or overlapping, is a method developed to reduce time-to-market and increase the value of the project to the owner or user. When overlapping activities, the additional cost for overlap is affected by the interaction between overlapped activities which is affected by the construction work methods used. Thus concurrent planning of construction projects can lead to a benefit for the owner through investigating the interactions between work methods under overlap and finding the best degrees of overlap. However, the determination of the best solution from all the possible combinations of multiple methods and degrees of overlap is affected by the decisionmaking approach: by a centralized decision-maker (e.g., the project manager) with less accurate information about cost estimates or by a decentralized decision-maker(s) (e.g., subcontractors) with a myopic viewpoint. The objective of this dissertation is to compare the solutions from the two decision-making approaches and to identify the conditions in which one approach is preferred to the other. Thus project owners can benefit from choosing a better approach for concurrent planning under their own conditions. A Monte Carlo simulation model for each decision-making approach was developed: an algorithm for finding the best solution was developed by heuristic methods. Several parameters were incorporated into the models to reflect different conditions for the decision-making approaches: number of activities, number of methods, the project manager’s solution capacity, the uncertainty in the project manager’s knowledge and attitudes towards risk. The comparison of the two approaches was implemented with random cost under different conditions. Furthermore, the model was applied to a hypothetical construction project. From the simulations the major conclusions include: (1) The decentralized approach becomes preferred with more activities; (2) Considering more methods provides more potential for higher benefit to the owner in the decentralized approach; (3) The decentralized approach is recommended under risk-averse attitude and high uncertainty in the project manager’s knowledge.