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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Estimating resource requirements of real-time actor systems through simulation /

Kohli, Sanjay. January 1992 (has links)
Report (M.S.)--Virginia Polytechnic Institute and State University. M.S. 1992. / Abstract. Includes bibliographical references (leaves 46-47). Also available via the Internet.
2

Revised AODV Routing Protocol with Energy Management for Real-Time/Non-Real-Time Services in Mobile Ad Hoc Network

Chung, Wen-Ju 13 August 2008 (has links)
As the growth of multimedia communications involving digital audio and video, it is increasingly important for the MANET (Mobile Ad Hoc Network) routing protocols to simultaneously support both real-time and non-real-time traffic. MANET energy management should offer this support because devices are equipped with limited battery power. To achieve this end, we revise the Ad hoc On-demand Distance Vector (AODV) routing protocol to provide an energy management mechanism such that both real-time and non-real-time packets can be effectively transmitted. In the proposed scheme, real-time traffic uses higher transmission power to reduce transmission delay time and selects a shortest route with the largest minimum residual energy to avoid route break. The non-real-time traffic uses normal transmission power to save energy and chooses a proper shortest route with highest average residual energy to balance node energy consumption. The simulation results show that the revised AODV obtains lower average end-to-end delay and fewer energy-exhausted nodes comparing to the conventional AODV.
3

Dynamics analysis and integrated design of real-time control systems

Tian, Yu-Chu January 2009 (has links)
Doctor of Philosophy (PhD) / Real-time control systems are widely deployed in many applications. Theory and practice for the design and deployment of real-time control systems have evolved significantly. From the design perspective, control strategy development has been the focus of the research in the control community. In order to develop good control strategies, process modelling and analysis have been investigated for decades, and stability analysis and model-based control have been heavily studied in the literature. From the implementation perspective, real-time control systems require timeliness and predictable timing behaviour in addition to logical correctness, and a real-time control system may behave very differently with different software implementations of the control strategies on a digital controller, which typically has limited computing resources. Most current research activities on software implementations concentrate on various scheduling methodologies to ensure the schedulability of multiple control tasks in constrained environments. Recently, more and more real-time control systems are implemented over data networks, leading to increasing interest worldwide in the design and implementation of networked control systems (NCS). Major research activities in NCS include control-oriented and scheduling-oriented investigations. In spite of significant progress in the research and development of real-time control systems, major difficulties exist in the state of the art. A key issue is the lack of integrated design for control development and its software implementation. For control design, the model-based control technique, the current focus of control research, does not work when a good process model is not available or is too complicated for control design. For control implementation on digital controllers running multiple tasks, the system schedulability is essential but is not enough; the ultimate objective of satisfactory quality-of-control (QoC) performance has not been addressed directly. For networked control, the majority of the control-oriented investigations are based on two unrealistic assumptions about the network induced delay. The scheduling-oriented research focuses on schedulability and does not directly link to the overall QoC of the system. General solutions with direct QoC consideration from the network perspective to the challenging problems of network delay and packet dropout in NCS have not been found in the literature. This thesis addresses the design and implementation of real-time control systems with regard to dynamics analysis and integrated design. Three related areas have been investigated, namely control development for controllers, control implementation and scheduling on controllers, and real-time control in networked environments. Seven research problems are identified from these areas for investigation in this thesis, and accordingly seven major contributions have been claimed. Timing behaviour, quality of control, and integrated design for real-time control systems are highlighted throughout this thesis. In control design, a model-free control technique, pattern predictive control, is developed for complex reactive distillation processes. Alleviating the requirement of accurate process models, the developed control technique integrates pattern recognition, fuzzy logic, non-linear transformation, and predictive control into a unified framework to solve complex problems. Characterising the QoC indirectly with control latency and jitter, scheduling strategies for multiple control tasks are proposed to minimise the latency and/or jitter. Also, a hierarchical, QoC driven, and event-triggering feedback scheduling architecture is developed with plug-ins of either the earliest-deadline-first or fixed priority scheduling. Linking to the QoC directly, the architecture minimises the use of computing resources without sacrifice of the system QoC. It considers the control requirements, but does not rely on the control design. For real-time NCS, the dynamics of the network delay are analysed first, and the nonuniform distribution and multi-fractal nature of the delay are revealed. These results do not support two fundamental assumptions used in existing NCS literature. Then, considering the control requirements, solutions are provided to the challenging NCS problems from the network perspective. To compensate for the network delay, a real-time queuing protocol is developed to smooth out the time-varying delay and thus to achieve more predictable behaviour of packet transmissions. For control packet dropout, simple yet effective compensators are proposed. Finally, combining the queuing protocol, the packet loss compensation, the configuration of the worst-case communication delay, and the control design, an integrated design framework is developed for real-time NCS. With this framework, the network delay is limited to within a single control period, leading to simplified system analysis and improved QoC.
4

Dynamics analysis and integrated design of real-time control systems

Tian, Yu-Chu January 2009 (has links)
Doctor of Philosophy (PhD) / Real-time control systems are widely deployed in many applications. Theory and practice for the design and deployment of real-time control systems have evolved significantly. From the design perspective, control strategy development has been the focus of the research in the control community. In order to develop good control strategies, process modelling and analysis have been investigated for decades, and stability analysis and model-based control have been heavily studied in the literature. From the implementation perspective, real-time control systems require timeliness and predictable timing behaviour in addition to logical correctness, and a real-time control system may behave very differently with different software implementations of the control strategies on a digital controller, which typically has limited computing resources. Most current research activities on software implementations concentrate on various scheduling methodologies to ensure the schedulability of multiple control tasks in constrained environments. Recently, more and more real-time control systems are implemented over data networks, leading to increasing interest worldwide in the design and implementation of networked control systems (NCS). Major research activities in NCS include control-oriented and scheduling-oriented investigations. In spite of significant progress in the research and development of real-time control systems, major difficulties exist in the state of the art. A key issue is the lack of integrated design for control development and its software implementation. For control design, the model-based control technique, the current focus of control research, does not work when a good process model is not available or is too complicated for control design. For control implementation on digital controllers running multiple tasks, the system schedulability is essential but is not enough; the ultimate objective of satisfactory quality-of-control (QoC) performance has not been addressed directly. For networked control, the majority of the control-oriented investigations are based on two unrealistic assumptions about the network induced delay. The scheduling-oriented research focuses on schedulability and does not directly link to the overall QoC of the system. General solutions with direct QoC consideration from the network perspective to the challenging problems of network delay and packet dropout in NCS have not been found in the literature. This thesis addresses the design and implementation of real-time control systems with regard to dynamics analysis and integrated design. Three related areas have been investigated, namely control development for controllers, control implementation and scheduling on controllers, and real-time control in networked environments. Seven research problems are identified from these areas for investigation in this thesis, and accordingly seven major contributions have been claimed. Timing behaviour, quality of control, and integrated design for real-time control systems are highlighted throughout this thesis. In control design, a model-free control technique, pattern predictive control, is developed for complex reactive distillation processes. Alleviating the requirement of accurate process models, the developed control technique integrates pattern recognition, fuzzy logic, non-linear transformation, and predictive control into a unified framework to solve complex problems. Characterising the QoC indirectly with control latency and jitter, scheduling strategies for multiple control tasks are proposed to minimise the latency and/or jitter. Also, a hierarchical, QoC driven, and event-triggering feedback scheduling architecture is developed with plug-ins of either the earliest-deadline-first or fixed priority scheduling. Linking to the QoC directly, the architecture minimises the use of computing resources without sacrifice of the system QoC. It considers the control requirements, but does not rely on the control design. For real-time NCS, the dynamics of the network delay are analysed first, and the nonuniform distribution and multi-fractal nature of the delay are revealed. These results do not support two fundamental assumptions used in existing NCS literature. Then, considering the control requirements, solutions are provided to the challenging NCS problems from the network perspective. To compensate for the network delay, a real-time queuing protocol is developed to smooth out the time-varying delay and thus to achieve more predictable behaviour of packet transmissions. For control packet dropout, simple yet effective compensators are proposed. Finally, combining the queuing protocol, the packet loss compensation, the configuration of the worst-case communication delay, and the control design, an integrated design framework is developed for real-time NCS. With this framework, the network delay is limited to within a single control period, leading to simplified system analysis and improved QoC.
5

Dynamics analysis and integrated design of real-time control systems

Tian, Yu-Chu. January 2008 (has links)
Thesis (Ph. D.)--University of Sydney, 2009. / Title from title screen (viewed November 30, 2009). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Electrical and Information Engineering in the Faculty of Engineering & Information Technologies. Degree awarded 2009; thesis submitted 2008. Includes bibliographical references. Also available in print form.
6

A PROGRAMMATIC OVERVIEW OF THE DEVELOPMENT AND IMPLEMENTATION OF THE RICS

Snider, Christopher W. 10 1900 (has links)
International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The Range Instrumentation and Control System (RICS) is a network of personal computers (PCs), routers, and switches designed to transport time-space-position information (TSPI) and/or other data between multiple Test Sites and data reduction facilities. The typical use of RICS will be the transport of TSPI data from a System Under Test (SUT) to a Focus Site for real-time display and post-mission analysis of the data. This capability will be expanded to include the transport of telemetry (TM), video, and communications data via the RICS. This paper will discuss the overall hardware design of the RICS. It will further describe the programmatic issues encountered during the implementation phase of the RICS project. The paper will describe the initial design criteria, the selection of hardware to implement the design, problems encountered with the implementation of the hardware, solutions and workarounds to the problems encountered, and lessons learned during the entire process.
7

A constrained computational model for flexible scheduling

McElhone, Charles Gerard January 1996 (has links)
No description available.
8

Computational architecture : a step towards predictable software design

Vickers, Andrew J. January 1994 (has links)
No description available.
9

Implementation of a Low Cost Commercial-Off-the-Shelf Commanding System

Grich, Richard J., Jr., Bourassa, Chris R. 10 1900 (has links)
International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Traditional satellite and launch control systems have consisted of custom solutions requiring significant development and maintenance costs. These systems have typically been designed to support specific program requirements and are expensive to modify and augment after delivery. Over the past five years, technical advances have resulted in Commercial-Off-The-Shelf (COTS) products which greatly reduce the complete life cycle costs associated with satellite and launch control system procurements. These advances, however, have been restricted to specific functional areas of the satellite and launch control system - most notably, telemetry processing and simulation. Until recently, technological advances in the development of COTS products which support functional areas like commanding and mission planning have lagged behind. This paper describes the development and application of a COTS product which provides a highly advanced commanding capability that is tightly integrated with the processing of telemetry data. This closed loop telemetry and commanding system forms the basis of a satellite or launch control system at a fraction of the cost normally associated with systems of this kind.
10

A Fast Realtime Simulation of a Complex Mechanical System on a Parallel Hardware Architecture

Oertel, C.-H., Gelhaar, B. 10 1900 (has links)
International Telemetering Conference Proceedings / October 26-29, 1992 / Town and Country Hotel and Convention Center, San Diego, California / Real-time computation speed is an additional requirement for simulations. It is necessary for 'man-in-the-loop' systems like flight simulators and for 'hardware-in-the-loop' systems where real components like new closed loop controllers are tested under realistic conditions. In the past a lot of companies have designed and built special purpose simulation computers which are very powerful but expensive and not handy enough for 'in-the-field-tests'. The progress in computer science shows a trend to distributed systems where multiple processors are running in parallel to improve the performance dramatically. At the DLR Institute for Flight Mechanics a computer system, based on the transputer, was designed to achieve the real-time simulation capabilities for the ROTEST model rotor. This four-bladed rotor is a 2.5 scale of the BO105 main rotor, equipped with elastic blades, operating at 1050 rpm. After an introduction to the ROTEST rotor, including the demands upon the simulation, a short introduction to transputers and the associated philosophy is given. The next part of the paper presents the characteristics of the simulation model, its mathematical description and the transputer architecture on which it is running. In the last part of the paper the input and output processes to the simulation are described. This includes a real-time representation of the rotor and an oscilloscope like output device, as well as analogue input and output devices to a controller.

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