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Radiation properties modeling for plasma-sprayed-alumina-coated rough surfaces for spacecrafts

MATERIALS SCIENCE And ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY 2006年第1-2期132卷 209-214页

作者： Li, R. M. Joshi, Sunil C. Ng, H. W. Nanyang Technol Univ Div Aerosp Engn Sch Mech & Aerosp Engn Singapore 639798 Singapore Nanyang Technol Univ Sch Mech & Aerosp Engn Div Engn Mech Singapore 639798 Singapore

Spacecraft thermal control materials (TCMs) play a vital role in the entire service life of a spacecraft [NASA Preferred Reliability Practices: Spacecraft Thermal control Coatings design and Application (Practice No. PD-ED- 1239), 1995, pp. 1-6]. Most of the conventional TCMs degrade in the harmful space environment [R.D. Karam, Satellite Thermal control for systems Engineers, AIAA, Virginia, USA, 1998, pp. 147-163]. In the previous study, plasma sprayed alumina (PSA) coating was established as a new and better TCM for spacecrafts, in view of its stability and reliability compared to the traditional TCMs [R.M. Li, S.C. Joshi, H.W. Ng, Presented in 2nd International conference on Materials for Advanced Technologies & IUMRS, Singapore, 2003, pp. 1-4]. During the investigation, the surface roughness of PSA was found important, because the roughness affects the radiative heat exchange between the surface and its surroundings. Parameters such as root-mean-square roughness cannot properly evaluate surface roughness effects on radiative properties of opaque surfaces [M.F. Modest, Radiative Heat Transfer, 2nd ed., Academic Press/Elsevier Science, USA, 2003, pp. 90-92]. Some models have been developed earlier to predict the effects, such as Davies' model [H. Davies, Proceedings of IEEE vol. 101, part IV, 1954, pp. 209-214], Tang and Buckius's statistical geometric optics model [K. Tang, R.O. Buckius, Int. J. Heat Mass Transfer 44 (2001) 4059-4073]. However, they are valid only in their own specific situations. In this paper, an energy absorption geometry model wa developed and applied to investigate the roughness effects with the help of 2D surface profile of PSA coated substrate scanned at micron level. This model predicts effective normal solar absorptance (alpha(ne)) and effective hemispherical infrared emittance (epsilon(he)) of a rough PSA surface. These values, if used in the heat transfer analysis of an equivalent, smooth and optically flat surface, lead to the predic

关键词： plasma processing aluminium oxide satellite thermal control surface roughness solar absorptance infrared emittance

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Rough sets based fuzzy logic control for greenhouse temperature

Rough sets based fuzzy logic control for greenhouse temperat...

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IEEE/ASME International conference on Mechatronic and Embedded systems and Applications

作者： Xu Fang Sheng Junqiang Chen Jiaoliao Zhejiang Univ Technol MOE Key Lab Mech Manufacture & Automat Hangzhou 310032 Zhejiang Peoples R China

ISBN: (纸本)9780780397200

In this paper, a rough sets based fuzzy logic control method was proposed for greenhouse temperature control. The process of system attribute reduct and a normalized processing for the sample data were carried out. Then the discernibility function was applied in the mining of certain and association rules from an incomplete decision table. Two overall thumb rules were generated for the definition of the fuzzy logic rule set. The corresponding fuzzy logic control system for greenhouse temperature was established by using the Simulink tools of MATLAB, including the choosing of variables, grade partition of the universes,. choosing of membership functions. The simulation achieved good performance, which verified the validity of employing rough sets based fuzzy logic control for greenhouse temperature control.

关键词： Fuzzy control Rough sets Temperature control greenhouses Choose Data sampling MATLAB Heuristics process systems

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Robot learning through task identification

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ROBOTICS And AUTONOMOUS systems 2006年第9期54卷 766-778页

作者： Nehmzow, Ulrich Iglesias, Roberto Kyriacou, Theocharis Billings, Stephen A. Univ Essex Dept Comp Sci Colchester CO4 3SQ Essex England Univ Santiago de Compostela Dept Elect & Comp Sci Santiago De Compostela Spain Univ Sheffield Dept Automat Control & Syst Engn Sheffield S Yorkshire England

The operation of an autonomous mobile robot in a semi-structured environment is a complex, usually non-linear and partly unpredictable process. Lacking a theory of robot-environment interaction that allows the design of robot control code based on theoretical analysis, roboticists still have to resort to trial-and-error methods in mobile robotics. The RobotMODIC project aims to develop a theoretical understanding of a robot's interaction with its environment, and uses system identification techniques to identify the system robot-task-environment. In this paper, we present two practical examples of the RobotMODIC process: mobile robot self-localisation and mobile robot training to achieve door traversal. In both examples, a transparent mathematical function is obtained that maps inputs - sensory perception in both cases - to output - location and steering velocity respectively. Analysis of the obtained models reveals further information about the way in which a task is achieved, the relevance of individual sensors, possible ways of obtaining more parsimonious models, etc. (C) 2006 Elsevier B.V. All rights reserved.

关键词： NARMAX modelling mobile robotics robot localisation task identification

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A service-oriented approach to enforce Grid resource allocations

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INTERNATIONAL JOURNAL OF COOPERATIVE INFORMATION systems 2006年第3期15卷 439-459页

作者： Sandholm, Thomas Gardfjall, Peter Elmroth, Erik Mulmo, Olle Johnsson, Lennart Royal Inst Technol Dept Numer Anal & Comp Sci SE-10044 Stockholm Sweden Umea Univ Dept Comp Sci SE-90187 Umea Sweden Umea Univ HPC2N SE-90187 Umea Sweden

We present the SweGrid Accounting System (SGAS) - a decentralized and standards-based system for Grid resource allocation enforcement that has been developed with an emphasis on a uniform data model and easy integration into existing scheduling and workload management software. The system has been tested at the six high-performance computing centers comprising the SweGrid computational resource, and addresses the need for soft, real-time quota enforcement across the SweGrid clusters. The SGAS framework is based on state-of-the-art Web and Grid services technologies. The openness and ubiquity of Web services combined with the fine-grained resource control and cross-organizational security models of Grid services proved to be a perfect match for the SweGrid needs. Extensibility and customizability of policy implementations for the three different parties that the system serves (the user, the resource manager, and the allocation authority) are key design goals. Another goal is end-to-end security and single sign-on, to allow resources to reserve allocations and charge for resource usage on behalf of the user. We conclude this paper by illustrating the policy customization capabilities of SGAS in a simulated setting, where job streams are shaped using different modes of allocation policy enforcement. Finally, we discuss some of the early experiences from the production system.

关键词： OGSA Grid accounting HPC

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The design of efficient ground software tools

The design of efficient ground software tools

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IEEE International conference on Space Mission Challenges for Information Technology, SMC-IT

作者： M. McCurdy G. Pyrzak A. Vera NASA Washington DC US

This paper describes the role of human-computer interaction (HCI) design in the development and deployment of mission systems. We make the argument that more broad application of HCI methods and practice will be necessary to complete the ambitious objectives of future missions. In particular, the introduction of increased autonomy, reduction of ops personnel, increasingly tactical nature of surface operations, and more distributed mission ground operations present unique challenges that must be met with sound HCI-driven solutions. We describe a case study from where solid underlying technology was hindered by lack of attention to HCI issues, and describe how this is being remedied moving forward. Future missions will require planning processes to be much more efficient (orders of magnitude) than what was achieved for the Mars Exploration Rovers mission (2003). The case study focuses on the critical shift from the MAPGEN software used for tactical activity planning on MER to SPIFe, now base-lined for the Phoenix 2007 and MSL 2009 missions. MAPGEN added automated planning functionality (Europa) to the APGEN manual planning tool. SPIFe provides a next generation interface designed specifically to take advantage of an automated planner. The design of SPIFe is based on hundreds of hours of observation and operations experience on MER. This paper examines how key HCI lessons learned are being fed forward into this new set of planning tools, SPIFe and Europa 2

关键词： Software tools Human computer interaction NASA Process planning Personnel Solids Mars Visualization Linear feedback control systems Iterative methods

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Automotive mechatronics

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control ENGINEERING PRACTICE 2004年第11期12卷 1343-1351页

作者： Schöner, HP DaimlerChrysler Res & Technol D-60528 Frankfurt Germany

A large share, of automotive innovations consists of significant improvements in formerly pure mechanical systems which are made possible using integrated electronics together with complex information processing. Such mechatronic systems require a concurrent design of mechanical, electronical, and information processing sub-systems in order to reach the cost requirements of the automotive industry. The motivation for the use of mechatronics is discussed, as well as the most important technological challenges of the mechatronical approach. Mechatronical solutions for different automotive applications are presented. The driving factors for future development of mechatronics in the automotive sector, are discussed. (C) 2004 Published by Elsevier Ltd.

关键词： automotive industry automotive control control system design chassis control engine control man/machine interaction

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Trade-offs and performance limitations in mechatronic systems: a case study

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ANNUAL REVIEWS IN control 2004年第2期28卷 181-192页

作者： El Rifai, OM Youcef-Toumi, K MIT Dept Mech Engn Cambridge MA 02139 USA

In this paper, the central issue of performance limitations is addressed in the context of design and control of mechatronic systems. Limitations arising at the component and system levels are both discussed. Presentation is made through a case study on atomic force microscopes (AFMs). Results from modeling, analysis, simulations and experiments are used to motivate and demonstrate several trade-offs and performance limitations in AFM. (C) 2004 Elsevier Ltd. All rights reserved.

关键词： mechatronics atomic force microscope AFM piezoelectric modeling trade-offs performance limitations nanotechnology

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A note on calculation of polytopic-invariant feasible sets for linear continuous-time systems

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ANNUAL REVIEWS IN control 2004年第1期28卷 59-64页

作者： Rohal-Ilkiv, B Slovak Univ Technol Bratislava Fac Mech Engn Dept Automat & Measurement Bratislava 81231 Slovakia

A common way of guaranteeing stability in model predictive control (MPC) is to add into the open-loop optimization problem a terminal constraint set which is invariant and feasible. This note presents an algorithm for calculation of low-complexity polytopic-invariant sets for linear continuous-time systems with complex conjugate closed-loop eigenvalues. Asymmetrical amplitude and rate control input constraints are considered. (C) 2004 Elsevier Ltd. All rights reserved.

关键词： constrained control stability invariant sets

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Virtual prototyping of mechatronic systems

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ANNUAL REVIEWS IN control 2004年第2期28卷 193-206页

作者： Ferretti, G Magnani, GA Rocco, P Politecn Milan Dipartimento Elettr & Informat I-20133 Milan Italy

Mechatronic systems abound in technological fields such as robotics and machine tools industry. Significant advances in dynamic performance of these systems can be achieved provided that mutual interactions of different domains (such as mechanics. electronics. hydraulics and control) are thoroughly understood. Virtual prototyping entails integration of multi-domain dynamic simulation in the design process, in order to reproduce and analyze the effects of design choices on the overall performance. This paper states the requirements of the modeling language and software tool for simulation of mechatronic systems and describes an experience of use of DYMOLA with Modelica language in the simulation of a complete machining center. The model has been successfully validated against experimental results collected on the real machining center. (C) 2004 Elsevier Ltd. All rights reserved.

关键词： mechatronics modeling object-orientation simulation virtual prototyping

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Disturbance rejection in hard disk drives with multi-rate estimated state feedback

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control ENGINEERING PRACTICE 2004年第11期12卷 1409-1421页

作者： Marcassa, F Oboe, R Univ Padua Dept Informat Engn I-35131 Padua Italy

Multi-rate control has been proposed as a solution to improve the performance of Hard Disk Drives (HDDs) head servo positioning. Some authors report unexpected decrease in performance when using this approach. This paper presents an analytical method to obtain the closed-loop sensitivity function of a multi-rate control system, with estimated state feedback. By using this tool, it is shown why disturbance rejection in multi-rate control may be worse than in single-rate. The paper reports both simulation and experimental results, confirming the possible decrease in performance, when using a standard design for the multi-rate control, even when a first-order hold is used. The paper also presents a novel design procedure for the multi-rate estimator, which takes into account the spectral distribution of disturbances and yields to a better performance, compared to both single-rate and standard multi-rate control. (C) 2003 Elsevier Ltd. All rights reserved.

关键词： multi-rate position control sensitivity function state estimation state feedback

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