4,881 research outputs found

    Selective electroplating of etched circuits

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    Selective electroplating of etched circuit

    Performance Back-deduction from a Loading to Flow Coefficient Map: Application to Radial Turbine

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    Radial turbine stages are often used for applications requiring off-design operation, as turbocharging for instance. The off-design ability of such stages is commonly analyzed through the traditional turbine map, plotting the reduced mass-flow against the pressure-ratio, for reduced-speed lines. However, some alternatives are possible, such as the flow-coefficient (ĪØ ) to loading-coefficient (Ļ†) diagram where the pressure-ratio lines are actually straight lines, very convenient property to perform prediction. A robust method re-creating this map from a predicted ĪØāˆ’Ļ† diagram is needed. Recent work has shown that this back-deduction quality, without the use of any loss models, depends on the knowledge of an intermediate pressure-ratio. A modelization of this parameter is then proposed. The comparison with both experimental and CFD results is presented, with quite good agreement for mass flow rate and rotational speed, and for the intermediate pressure ratio. The last part of the paper is dedicated to the application of the intermediate pressure-ratio knowledge to the improvement of the deduction of the pressure ratio lines in the ĪØāˆ’Ļ† diagram. Beside this improvement, the back-deduction method of the classical map is structured, applied and evaluated

    A multi-agent based system to enable strategic and operational design coordination

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    This paper presents two systems which individually focus on different aspects of design coordination, namely strategic and operational. The systems were developed in parallel and individually contain related models that represent specific frames from a Design Coordination Framework developed by Andreasen et al. [1]. The focus of the strategic design management system is the management of design tasks, decisions, information, goals and rationale within the design process, whereas the focus of the operational design coordination system is the coordination of tasks and activities with respect to the near-optimal utilisation of available resources. A common interface exists which enables the two systems to be integrated and used as a single system with the aim of managing both strategicand operational design coordination. Hence, the objective of this work is to enable the design process to be conducted in a timely and appropriate manner

    Coordination approaches and systems - part II : an operational perspective

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    This is the second of two papers surveying research in coordination approaches and systems. This paper is concerned with operational coordination, which is aimed at coordinating activities such that the design process can be performed in a near optimal manner with respect to time, and the allocation and utilisation of resources. Aspects of coordination categorised as operational include resource management, scheduling and planning. The first of these two papers presents a review of coordination from a strategic perspective, which is concerned with the decision management aspects of coordination. Greater emphasis is now being placed on the significance of organising the design process as this affects time to market, product quality, cost, and consequently product success. The aim of this paper is to present a fundamental review of operational coordination approaches and systems. The 1990s has seen much progress being made towards a greater understanding and appreciation of coordination in various disciplines through the development of a wide range of approaches and systems. However, there remains a requirement to formally identify the key issues involved in coordination such that a widely accepted representation can be agreed upon. Consequently, research should continue to be supported in the exploration for a unified approach to coordination which will permit a broader and greater understanding of those aspects involved

    A system for co-ordinating concurrent engineering

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    Design of large made-to-order products invariably involves design activities which are increasingly being distributed globally in order to reduce costs, gain competitive advantage and utilise external expertise and resources. Designers specialise within their domain producing solutions to design problems using the tools and techniques with which they are familiar. They possess a relatively local perception of where their expertise and actions are consumed within the design process. This is further compounded when design activities are geographically distributed, resulting with the increased disassociation between an individual designer's activities and the overall design process. The tools and techniques used by designers rarely facilitate concurrency, producing solutions within a particular discipline without using or sharing information from other disciplines, and seldom considering stages within the product's life-cycle other than conceptual, embodiment or detail [1, 2]. Conventional management and maintenance of consistency throughout the product model can subsequently become difficult to achieve since there are many factors that need to be simultaneously considered whilst making achange to the product model

    Intelligent design guidance

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    This paper presents results from an investigation regarding the use of the Design Structure Matrix (DSM) as a means to guide a designer through the calculation of numerical relationships within the early design system Designer. Characteristics, relationships and goals are used within Designer to enable the evaluation and approximation of the design model and are represented within the system as a digraph. Despite being a useful representation of the interactions within the design model, the digraph does not aid the designer in identifying a sequence of activities that need to be performed in order to evaluate the model. The DSM system was used to represent the characteristics and the dependencies obtained through the relationships. The sequence of characteristics within the DSM was optimised and used to produce a design process to guide the designer in model evaluation. The objective of the optimisation was to minimise the amount of iteration within the design process. The process enabled a designer who is unfamiliar with the model to evaluate it and satisfy the design goals and requirements. Both the DSM system and the Designer system are generic in nature andmay be applied to any design problem

    Towards an understanding of the impact of resources on the design process

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    Considerable effort has been devoted within the design research community to understanding the structure of design processes and their development for different design problems. Whilst much work has examined the impact of design goals upon the structure of a design process, less attention has been paid to the role that design resources can play. This paper describes an experiment directed towards gaining an understanding of the impact that both active resources (which perform design tasks) and passive resources (which are used by active resources) can have upon design process structure. Main outcomes from the experiment were the conclusive identification that resources can significantly impact design process structure and a number of examples of how these impacts manifest themselves. The main conclusion of the paper is that given the sizeable impact resources can have upon process structure, there is a considerable need to obtain a greater understanding of these impacts to facilitate the development of techniques that can support design process definition based upon an understanding of the design resources being used to solve a design problem

    Coordination approaches and systems - part I : a strategic perspective

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    This is the first part of a two-part paper presenting a fundamental review and summary of research of design coordination and cooperation technologies. The theme of this review is aimed at the research conducted within the decision management aspect of design coordination. The focus is therefore on the strategies involved in making decisions and how these strategies are used to satisfy design requirements. The paper reviews research within collaborative and coordinated design, project and workflow management, and, task and organization models. The research reviewed has attempted to identify fundamental coordination mechanisms from different domains, however it is concluded that domain independent mechanisms need to be augmented with domain specific mechanisms to facilitate coordination. Part II is a review of design coordination from an operational perspective
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