73,331 research outputs found

    A hyperbolic system and the cost of null controllability for the Stokes system

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    This paper is devoted to study the cost of the null controllability for the Stokes system. Using the control transmutation method we show that the cost of driving the Stokes system to rest at time T is of order e^C/T when T -->0^+,i.e., the same order as for the heat equation. For this to be possible, we are led to study the exact controllability of one hyperbolic system with a resistance term, which will be done under assumptions on the control region.Comment: 17 page

    A framework to evaluate the impact of ICT usage on collaborative product development performance in manufacturing firms : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Engineering at Massey University, Auckland, New Zealand

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    Manufacturers are increasingly adopting collaborative product development (CPD) to achieve competitive advantage through joint synergies. Information and communication technology (ICT) is the major enabler of communication, collaboration, product designing, development, knowledge and information management, project management, and market research activities involved in CPD. Most ICT implementations incur a significant cost for firms, thus a deeper understanding of the impact of ICT usage on CPD performance would be immensely useful for managing ICT resources effectively in innovation programmes. However, existing evidence for the direct relationships between ICT usage and performance dimensions are counterintuitive (negative or insignificant). Not considering the different aspects of ICT usage was identified as a key reason for the lack of strong empirical evidence. Furthermore, the impact of ICT usage on collaboration-based product development performance and indirect impact through this collaboration performance on new product performance, as well as moderating effects of project characteristics on the direct and indirect ICT impact have largely been ignored in the literature. Therefore, drawing on relational resource-based view and organizational information processing theory, this study develops and utilizes a model including multidimensional ICT usage and CPD performance measurements, and possible moderating project characteristics, for better evaluating the impact of ICT usage on CPD performance. Initially, product development professionals from manufacturing firms and knowledgeable managers from ICT vendor firms were interviewed for a preliminary qualitative evaluation of the suggested model with industry perspectives. In addition, a quantitative investigation of secondary data obtained from the PDMA’s (Product Development and Management Association) 2012 comparative performance assessment study was conducted prior to the main survey in order to assess the significance of the proposed model with a different source of data. In the final main quantitative study, data collected from 244 CPD projects via an online global survey were used to test the research hypotheses. The study contributes to the current body of knowledge by revealing a positive direct impact of ICT usage on new product performance in terms of quality, commercial success, and time performance, and collaboration performance, which also in turn increases new product performance. In addition, moderating effects of project characteristics (complexity and uncertainty) on these associations have been explored. The study implies that manufacturers need to value not only the direct project benefits of ICT use, but also the collaboration-related outcomes that significantly increase the likelihood of achieving higher performance in their present and future CPD projects. Adequate attention must be paid to individual ICT usage dimensions as well. Particularly, other than frequency of ICT use, manufacturing firms need to improve the utilization of available features and functionalities of the tools (intensity) and the ICT proficiency of R&D staff, to gain the desired results in CPD projects

    A uniform controllability result for the Keller-Segel system

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    In this paper we study the controllability of the Keller-Segel system approximating its parabolic-elliptic version. We show that this parabolic system is locally uniform controllable around a constant solution of the parabolic-elliptic system when the control is acting on the component of the chemical
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