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- Abdelzaher, Tarek, et al.
(författare)
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Practical Application of Control Theory to Web Services
- 2004
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Ingår i: Proceedings of the American Control Conference. - 0743-1619. ; 3, s. 1992-1997
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Konferensbidrag (refereegranskat)abstract
- This tutorial describes experiences with applying a control theoretical approach to achieving performance guarantees in Web servers, with emphasis on delay control. A model for the server is formulated and translated into a control problem formulation. Limitations of the control theoretic approach are identified that arise due to system non-linearities and modeling inaccuracies. Solutions are proposed that augment the feedback control framework with elements of scheduling and queuing theory. The theoretical results and QoS control loops presented by the authors are implemented in a middleware package, called ControlWare, which provides the software mechanisms and interfaces that allow control of real server performance. Implementation and performance of ControlWare is described.
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| 2. |
- Wang, Lihui, et al.
(författare)
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An Approach to Tripod Optimization and Remote Manipulation
- 2003
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Ingår i: Transactions of the North American Manufacturing Research Institution of SME, volume 31. - : Society of Manufacturing Engineers, North American Manufacturing Research Institution. - 9781618394781 ; , s. 321-328
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Konferensbidrag (refereegranskat)abstract
- The Tripod is one type of parallel kinematic machine having three degrees of freedom. The sliding-leg tripod presented in this paper is designed as a programmable add-on device for manufacturing and shop floor automation. It can be used as a toolhead for machine tools, or as a work stage for coordinate measuring machines. The purpose is to enhance the capability of a machine by providing it with a more flexible range of motion and controllability from any distance. As decentralization of manufacturing grows, shop floor equipment like this is required to become networkable and remotely accessible. This paper focuses on two separate issues: tripod design optimization and remote real-time monitoring and control of the tripod. A web-based prototype is developed to verify the feasibility of the approach as well as the tripod accessibility in a distributed environment. It is shown that the proposed approach can improve the tripod design and its controllability. A large application potential of this approach is also predicted.
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| 6. |
- Xu, Hongqi, et al.
(författare)
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Reflection phase of scattering electrons in a single-channel atomic wire
- 2003
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 68:24
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Tidskriftsartikel (refereegranskat)abstract
- A theoretical study of the phase property of the reflection coefficient of a single-channel quantum system is presented. This reflection phase information is required for a complete characterization of the scattering problem in the system. It is found that the phase of the reflection coefficient of the system shifts abruptly by pi when the reflection probability passes through a zero. It is also found that in certain systems this phase discontinuity can appear even when no zero and no phase discontinuity are present in the transmission coefficient. Possible experiments for the observation of the reflection phase discontinuity are discussed.
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| 7. |
- Zhang, Dan, et al.
(författare)
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An Integrated Virtual Validation System for Parallel Kinematic Machine Analysis and Design
- 2003
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Ingår i: Proceedings of the ASME Design Engineering Technical Conference. ; , s. 1149-1158
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Konferensbidrag (refereegranskat)abstract
- Selecting a configuration for a machine tool that will best suit the needs of a forecast set of requirements can be a difficulty and costly exercise. This problem can now be addressed using an integrated virtual validation system. The system includes kinematic/dynamic analysis, kinetostatic model, CAD module, FEM module, CAM module, optimization module and visual environment for simulation and collision detection of the machining and deburring. It is an integration of the parallel kinematic machines (PKM) design, analysis, optimization and simulation. In this paper, the integrated virtual system is described in a detail, a prototype of a 3-dof PKM is modeled, analyzed, optimized and remote controlled with the proposed system. Some results and simulations are also given. Its effectiveness is shown with the results obtained by NRC-IMTI during the design of the 3-dof NRC PKM.
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| 8. |
- Zhang, Dan, et al.
(författare)
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Modelling and Control of PKM in an Integrated Environment
- 2003
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Ingår i: Proceedings of the ASME Design Engineering Technical Conference. - : ASME Press. ; , s. 67-76
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Konferensbidrag (refereegranskat)abstract
- This paper introduces an integrated validation system that consists of the following modular components: kinematic/dynamic analysis module, kinetostatic model, CAD module, FEM module, CAM module, optimization module and visual environment for remote control. In this paper, authors focus mainly on the modules of kinetostatic modeling, dynamic modeling, PKM design optimization, and remote control realization. The prototype of a 3-dof PKM developed at NRC-IMTI is used as an example throughout this paper.
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