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Gubba, Ravikumar Krishnanjan. „Distributed simulation of power systems using real time digital simulator“. Master's thesis, Mississippi State : Mississippi State University, 2009. http://library.msstate.edu/etd/show.asp?etd=etd-06152009-222641.
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Kim, Song Hun. „Distributed Reconfigurable Simulation for Communication Systems“. Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/29700.
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The simulation of physical-layer communication systems often requires long execution times. This is due to the nature of the Monte Carlo simulation. To obtain a valid result by producing enough errors, the number of bits or symbols being simulated must significantly exceed the inverse of the bit error rate of interest. This often results in hours or even days of execution using a personal computer or a workstation.
Reconfigurable devices can perform certain functions faster than general-purpose processors. In addition, they are more flexible than Application Specific Integrated Circuit (ASIC) devices. This fast yet flexible property of reconfigurable devices can be used for the simulation of communication systems. However, although reconfigurable devices are more flexible than ASIC devices, they are often not compatible with each other. Programs are usually written in hardware description languages such as Very High Speed Integrated Circuit (VHSIC) Hardware Description Language (VHDL). A program written for one device often cannot be used for another device because these devices all have different architectures, and programs are architecture-specific.
Distributed computing, which is not a new concept, refers to interconnecting a number of computing elements, often heterogeneous, to perform a given task. By applying distributed computing, reconfigurable devices and digital signal processors can be connected to form a distributed reconfigurable simulator.
In this paper, it is shown that using reconfigurable devices can greatly increase the speed of simulation. A simple physical-layer communication system model has been created using a WildForce board, a reconfigurable device, and the performance is compared to a traditional software simulation of the same system. Using the reconfigurable device, the performance was increased by approximately one hundred times. This demonstrates the possibility of using reconfigurable devices for simulation of physical-layer communication systems.
Also, an middleware architecture for distributed reconfigurable simulation is proposed and implemented. Using the middleware, reconfigurable devices and various computing elements can be integrated. The proposed middleware has several components. The master works as the server for the system. An object is any device that has computing capability. A resource is an algorithm or function implemented for a certain object. An object and its resources are connected to the system through an agent. This middleware system is tested with three different objects and six resources, and the performance is analyzed. The results shows that it is possible to interconnect various objects to perform a distributed simulation using reconfigurable devices. Possible future research to enhance the architecture is also discussed.Ph. D.
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Khan, Izhar Ahmed. „A Distributed Context Simulation Component“. Thesis, Mittuniversitetet, Institutionen för informationsteknologi och medier, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-32576.
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Mobile devices with access to large numbers of sensors with internet access move forwards the development of intelligent applications towards new shape of ubiquitous applications. In order to create such applications we need to be able to do simulations to test and deploy. Current simulators do not permit this since they are centralized and the information is not shared globally. Therefore we cannot use them to test application built on distributed sensor information. I selected Siafu as the simulator component. In the next step, the simulator was customized according to the requirements of the project. There are different possibilities to achieve this task, but a simple GUI is made to control the simulator.The end result is a complete architecture for simulating context aware scenarios. The implementation is tested by running the simulator and dumping the context data into the PGRID overlay. For future work, implementing proximity estimation between the agents will be a good idea and can be interesting as well.
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Jeon, Dae Kyung. „Methodologies for developing distributed systems in Ada with a simulation of a distributed Ada system“. Virtual Press, 1989. http://liblink.bsu.edu/uhtbin/catkey/722459.
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In recent years, the field of distributed processing, distributed systems, has undergone great change, and has been an area attracting tremendous research and development efforts. This thesis explores the various current methodologies for designing, developing and implementing distributed systems using the Ada programming language, and goes on to implement a simulation of a distributed store system using the "virtual node" design approach. After a brief introduction on distributed systems in general, an investigation of the basic issues and problems involved in distributing Ada programs coupled with an analysis and comparison of various approaches to developing distributed Ada systems is carried out. It is shown that one of the critical problems of Ada in a distributed environment is its implicit assumption of a single memory processor. A simulation of a distributed system (store system) is carried out using the virtual node method of developing distributed Ada systems. The various stages of this design method including interface task specification are stepped through. A sample run of the. system is given, including the customer file, stock file data and the monitored output of the system.Department of Computer Science
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Dawson, Jeffrey. „A HOLISTIC USABILITY FRAMEWORK FOR DISTRIBUTED SIMULATION SYSTEMS“. Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2346.
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This dissertation develops a holistic usability framework for distributed simulation systems (DSSs). The framework is developed considering relevant research in human-computer interaction, computer science, technical writing, engineering, management, and psychology. The methodology used consists of three steps: (1) framework development, (2) surveys of users to validate and refine the framework, and to determine attribute weights, and (3) application of the framework to two real-world systems. The concept of a holistic usability framework for DSSs arose during a project to improve the usability of the Virtual Test Bed, a prototypical DSS, and the framework is partly a result of that project. In addition, DSSs at Ames Research Center were studied for additional insights. The framework has six dimensions: end user needs, end user interface(s), programming, installation, training, and documentation. The categories of participants in this study include managers, researchers, programmers, end users, trainers, and trainees. The first survey was used to obtain qualitative and quantitative data to validate and refine the framework. Attributes that failed the validation test were dropped from the framework. A second survey was used to obtain attribute weights. The refined framework was used to evaluate two existing DSSs, measuring their holistic usabilities. Ensuring that the needs of the variety of types of users who interact with the system during design, development, and use are met is important to launch a successful system. Adequate consideration of system usability along the several dimensions in the framework will not only ensure system success but also increase productivity, lower life cycle costs, and result in a more pleasurable working experience for people who work with the system.Ph.D.
Department of Industrial Engineering and Management Systems
Engineering and Computer Science
Industrial Engineering and Management Systems
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Leuhusen, Joakim, und Andreas Karlsson. „Simulation and synchronization of distributed real-time systems“. Thesis, Linköping University, Vehicular Systems, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-52784.
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Today we are very much dependent on different kinds of real time systems. Usually,a real time system is a system which is interacting with a physical environmentwith sensors or activators. There are many advantages by replacing mechanicalcomponents with electrical ones. For instance, it is usually cheaper and possibleto add new functions to the device without replacing the electronic part, whichwould have been necessary with a mechanical one.The possibility of simulating a distributed system is used throughout the vehi-cle industry. With the simulation of connected sub systems, using modeled busesand real time kernels, one could increase the correctness of the behavior of the sys-tem and consequently decrease the amount of time spent later in the developingprocess.In this master thesis we used modeled CAN-buses and real time models tosimulate the connection and execution time of the systems. The simulation resultsare used to validate the functionality of the distributed system. Additionally, aworst-case response time analysis is made to set timing constraints on the systemto fulfill given deadlines.During the work, different settings of the network are tested to analyze thesystem frequency needed to sustain deadlines and correctness on the network.
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Hosseinzaman, Abbas. „The parallel and distributed simulation of network systems“. Thesis, Nottingham Trent University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283272.
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Hoaglund, Catharine McIntire. „Design factors for the communication architecture of distributed discrete event simulation systems“. CSUSB ScholarWorks, 2006. https://scholarworks.lib.csusb.edu/etd-project/3058.
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The purpose of the thesis was to investigate the influence communication architecture decisions have on the performance of a simulation system with distributed components. In particular, the objective was to assess the relative importance of factors affecting reliability and variability of an external data interface to the performance of the simulation, as compared to factor within the simulation itself.
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Pastrana, John. „Model-Based Systems Engineering Approach to Distributed and Hybrid Simulation Systems“. Doctoral diss., University of Central Florida, 2014. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6336.
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INCOSE defines Model-Based Systems Engineering (MBSE) as "the formalized application of modeling to support system requirements, design, analysis, verification, and validation activities beginning in the conceptual design phase and continuing throughout development and later life cycle phases." One very important development is the utilization of MBSE to develop distributed and hybrid (discrete-continuous) simulation modeling systems. MBSE can help to describe the systems to be modeled and help make the right decisions and partitions to tame complexity.
The ability to embrace conceptual modeling and interoperability techniques during systems specification and design presents a great advantage in distributed and hybrid simulation systems development efforts. Our research is aimed at the definition of a methodological framework that uses MBSE languages, methods and tools for the development of these simulation systems. A model-based composition approach is defined at the initial steps to identify distributed systems interoperability requirements and hybrid simulation systems characteristics. Guidelines are developed to adopt simulation interoperability standards and conceptual modeling techniques using MBSE methods and tools. Domain specific system complexity and behavior can be captured with model-based approaches during the system architecture and functional design requirements definition. MBSE can allow simulation engineers to formally model different aspects of a problem ranging from architectures to corresponding behavioral analysis, to functional decompositions and user requirements (Jobe, 2008).Ph.D.
Doctorate
Industrial Engineering and Management Systems
Engineering and Computer Science
Industrial Engineering
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Hendry, Barbara. „Distributed object-oriented discrete event simulation /“. Online version of thesis, 1990. http://hdl.handle.net/1850/10999.
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Cheng, Lechang. „Simulation and topology generation for large-scale distributed systems“. Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/13404.
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Simulation of P2P systems at large scale is important because some problems with the protocols or their implementations might not appear at smaller scales. In this work, a parallel message-level simulator, P2PNet, is proposed, which can simulate P2P systems with up to tens of thousands of nodes. P2PNet applies the technique of time expansion and uses real time to synchronize the processing of events among the participating processors. Simulation results show that P2PNet has small overhead compared with a single-processor event-driven simulator, a large speedup when multiple computers are used and no late events.
One of the other challenges of large-scale network simulations is the lack of scalable and realistic Internet topology generators. In this work, we propose a topology generator which can generate accurate large-scale models of the Internet. We extract the AS (autonomous system) level and router level topology of the Internet with Internet measurement data. A compact routing core is built with the AS topology and router cluster topology. Each generated topology consists of the routing core and a set of end nodes connected to router clusters. The generated topology is realistic since its routing core is extracted from Internet. We also propose efficient algorithms to compute AS level path.
The current routing algorithms of DHT-based P2P systems have a large end-to-end delay and inconsistent routing performance because of their random selection of identifiers (IDs). In this paper, an Internet topology based overlay construction method is proposed for tree-based DHTs. The node ID is divided into three parts and assigned according to the autonomous system (AS), IP network prefix, and IP address of the node. This algorithm assigns the AS ID prefix based on the AS-level Internet topology. The assignment of AS ID prefixes also takes into account the node densities of ASes to alleviate the ID space load imbalance. Simulation results show that this method can reduce the routing stretch and the standard deviation of the routing stretch without introducing any single points of failure.
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Shires, Nigel. „The distributed simulation of highly automated batch manufacturing systems“. Thesis, Loughborough University, 1988. https://dspace.lboro.ac.uk/2134/10823.
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This thesis examines the use of distributed discrete-event simulation techniques as part of an aid to the design of highly automated batch manufacturing systems. The methodology and objectives of the design of highly automated batch manufacturing systems are described and an assessment is made of the use of modelling and simulation as part of the method . Criteria are developed for a simulator used during the . detail design stage. The different approaches taken by existing simulation systems to building and configuring simulation models and their use of particular simulation techniques are described. Limitations on simulation models due to the sequential processing of event-lists and activity scans are identified in a review of the problems of simulation that current existing distributed simulators have been designed to answer. The advantages of concurrent and distributed computing and in particular, a tightly-coupled multi-microprocessor computing engine for executing the normally batch-processed computing tasks of simulation are identified . A novel approach to the distr~bution of the computational tasks in a distributed simulation system is described and the operation of a simulator built using this approach to simulate the operation of highly automated batch manufacturing systems is also described.The question of whether such a distributed simulator of highly automated batch manufacturing systems satisfies the criteria is examined on the basis of an analysis of the operation of the simulator. It is shown that a number of advantages in the areas of level of detail, configuration, parallel processing and speed of execution can be achieved through the use of distributed computing and multi-processing techniques for simulation during the detail design stage of highly automated batch manufacturing systems.
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Gaff, Douglas G. „Architecture design and simulation for distributed learning classifier systems“. Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-02132009-172649/.
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Brumbulli, Mihal. „Model-driven development and simulation of distributed communication systems“. Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät II, 2015. http://dx.doi.org/10.18452/17233.
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Verteilte Kommunikationssysteme haben in den letzten Jahren enorm an Bedeutung gewonnen, insbesondere durch die Vielzahl von Anwendungen in unserem Alltag. Die Heterogenität der Anwendungen und Anwendungsdomänen spricht für die Komplexität solcher Systeme und verdeutlicht die Herausforderungen, mit denen ihre Entwickler konfrontiert sind. Der Schwerpunkt dieser Arbeit liegt auf der Unterstützung des Entwicklungsprozesses von Anwendungen für verteilte Kommunikationssysteme. Es gibt zwei Aspekte, die dabei berücksichtigt werden müssen. Der erste und offensichtlichste ist die Unterstützung der Entwicklung der Anwendung selbst, die letztendlich auf der vorhandenen verteilten Kommunikationsinfrastruktur bereitgestellt werden soll. Der zweite weniger offensichtliche, aber genauso wichtige Aspekt besteht in der Analyse der Anwendung vor ihrer eigentlichen Installation. Anwendungsentwicklung und analyse sind also "zwei Seiten der gleichen Medaille". Durch die Berücksichtigung beider Aspekt erhöht sich jedoch andererseits der Aufwand bei der Entwicklung. Die Arbeit kombiniert und erweitert vorhandene Technologien entsprechend dem modellgetriebenen Entwicklungsparadigma zu einer einheitlichen Entwicklungsmethode. Die Eigenschaften der Anwendung werden in einer vereinheitlichten Beschreibung erfasst, welche sowohl die automatische Überführung in Installationen auf echten Infrastrukturen erlaubt, als auch die Analyse auf der Basis von Modellen. Darüber hinaus wird der Entwicklungsprozess mit zusätzlicher Unterstützung bei der Visualisierung der Analyse ergänzt. Die Praktikabilität des Ansatzes wird anschließend anhand der Entwicklung und Analyse einer Anwendung zur Erdbebenfrühwarnung unter Beweis gestellt.Distributed communication systems have gained a substantial importance over the past years with a large set of examples of systems that are present in our everyday life. The heterogeneity of applications and application domains speaks for the complexity of such systems and the challenges that developers are faced with. The focus of this dissertation is on the development of applications for distributed communication systems. There are two aspects that need to be considered during application development. The first and most obvious is the development of the application itself that will be deployed on the existing distributed communication infrastructure. The second and less obvious, but equally important, is the analysis of the deployed application. Application development and analysis are like "two sides of the the same coin". However, the separation between the two increases the cost and effort required during the development process. Existing technologies are combined and extended following the model-driven development paradigm to obtain a unified development method. The properties of the application are captured in a unified description which drives automatic transformation for deployment on real infrastructures and/or analysis. Furthermore, the development process is complemented with additional support for visualization to aid analysis. The defined approach is then used in the development of an alarming application for earthquake early warning.
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McLean, Angus L. M. Thom III. „Real-time distributed simulation analysis : an application of temporal database and simulation systems research“. Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/9124.
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Mohammed, Thabit Sultan. „Fault diagnosis of distributed systems : analysis, simulation and performance measurement“. Thesis, Cranfield University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302751.
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Schäfer, Heiko Schulze Michael. „Extending and restructuring AnT for distributed simulation of dynamical systems“. [S.l. : s.n.], 2001. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB9578209.
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Lu, Kaiyuan. „Data distribution management schemes for HLA-compliant distributed simulation systems“. Thesis, University of Ottawa (Canada), 2006. http://hdl.handle.net/10393/27151.
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Data Distribution Management (DDM), one of the six services provided by High Level Architecture and Run-Time Infrastructure, provides an efficient and scalable mechanism for data routing among hosts in distributed simulations. Traditional, DDM schemes are classified into two main types, region-based methods and grid-based methods. Currently, the time, computation and communication overhead of DDMs are still issues for large-scale simulations. We proposed two new DDM schemes addressing these issues. Our first algorithm, which we refer to as optimized dynamic grid-based DDM scheme, aims at further reducing irrelevant data that might be received by simulation entities in dynamic grid-based approach [11], by enforcing a second level of sender-side data filtering mechanism. Our second algorithm, which we refer to as grid-filtered region-based DDM, uses a threshold value of coverage percentage to determines if exact matching is necessary. In this thesis, we present and discuss the implementation of our proposed DDM algorithms, and report on their performance based on an extensive set of simulation experiments. Last but not least, we present the preliminary work we have done on real-time enabling scheme to RTI for HLA-compliant simulations.
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Rihawi, Omar. „Modelling and simulation of distributed large scale situated multi-agent systems“. Thesis, Lille 1, 2014. http://www.theses.fr/2014LIL10148/document.
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Les systèmes multi-agents sont constitués d'entités autonomes qui interagissent avec leur environnement pour résoudre un objectif collectif. Si l'on souhaite modéliser des systèmes contenant des millions d'agents, une puissance de calcul et de stockage importante devient nécessaire. Pour atteindre de telles simulations large échelle, distribuer le simulateur sur un réseau de machines est nécessaire, mais il faut prendre en compte quelques aspects. Le premier aspect se concentre sur deux types de répartition de la charge de calcul : la première basée sur l'environnement, la deuxième basée sur les agents. Nous évaluons les performances de ces répartitions en les confrontant à des applications dont les dynamiques de déplacement sont très différentes, ce qui nous permet d'identifier plusieurs critères devant être pris en compte pour garantir des gains de performance lors de la distribution de simulations d'agents situés. Le second aspect de notre travail étudie la synchronisation. En effet, à notre connaissance, tous les simulateurs existants fonctionnent sur la base d'une synchronisation forte entre les machines, ce qui garantit la causalité temporelle et la cohérence des calculs. Dans cette thèse, nous remettons en cause cette hypothèse en étudiant la relaxation de la contrainte de synchronisation. Nous proposons deux politiques de synchronisation : la synchronisation forte classique et une forme de synchronisation reposant sur une fenêtre de temps bornée entre la machine la plus lente et la machine la plus rapide. Des applications de natures différentes sont exécutées avec ces différents mécanismes de synchronisationThis thesis aims to design a distributed large scale MAS simulation. When the number of agents reaches several millions, it is necessary to distribute MAS simulation. However, this can raise some issues: agents allocation, interactions from different machines, time management, etc. When we distribute MAS simulation on different machines, agents must be separated between these machines and should still be able to produce their normal behaviours. Our distribution is able to cover all agents' perceptions during the simulation and allow all agents to interact normally. Moreover, with large-scale simulations the main observations are done on the macroscopic level. In this thesis, we study two main aspects to distribute large-scale simulations. The first aspect is the efficient strategy that can be used to distribute MAS concepts (agents and environment). We propose two efficient distribution approaches: agents distribution and environment distribution. The second aspect is the relaxation of synchronization constraints in order to speed up the execution of large-scale simulations. Relaxing this constraint can induce incoherent interactions, which do not exist in a synchronized context. But, in some applications that can not affect the macroscopic level. Our experiments on different categories of MAS applications show that some applications can be distributed efficiently in one distribution approach more than the other. In addition, we have studied the impact of incoherent iterations on the emerging behaviour of different applications, and we have evidenced situations in which unsynchronized simulations still produced the expected macroscopic behaviour
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Mengistu, Dawit. „Improving the performance of distributed multi-agent based simulation“. Doctoral thesis, Karlskrona : Blekinge Institute of Technology, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-00485.
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This research investigates approaches to improve the performance of multi-agent based simulation (MABS) applications executed in distributed computing environments. MABS is a type of micro-level simulation used to study dynamic systems consisting of interacting entities, and in some cases, the number of the simulated entities can be very large. Most of the existing publicly available MABS tools are single-threaded desktop applications that are not suited for distributed execution. For this reason, general-purpose multi-agent platforms with multi-threading support are sometimes used for deploying MABS on distributed resources. However, these platforms do not scale well for large simulations due to huge communication overheads. In this research, different strategies to deploy large scale MABS in distributed environments are explored, e.g., tuning existing multi-agent platforms, porting single-threaded MABS tools to distributed environment, and implementing a service oriented architecture (SOA) deployment model. Although the factors affecting the performance of distributed applications are well known, the relative significance of the factors is dependent on the architecture of the application and the behaviour of the execution environment. We developed mathematical performance models to understand the influence of these factors and, to analyze the execution characteristics of MABS. These performance models are then used to formulate algorithms for resource management and application tuning decisions. The most important performance improvement solutions achieved in this thesis include: predictive estimation of optimal resource requirements, heuristics for generation of agent reallocation to reduce communication overhead and, an optimistic synchronization algorithm to minimize time management overhead. Additional application tuning techniques such as agent directory caching and message aggregations for fine-grained simulations are also proposed. These solutions were experimentally validated in different types of distributed computing environments. Another contribution of this research is that all improvement measures proposed in this work are implemented on the application level. It is often the case that the improvement measures should not affect the configuration of the computing and communication resources on which the application runs. Such application level optimizations are useful for application developers and users who have limited access to remote resources and lack authorization to carry out resource level optimizations.
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Wong, Wing-ki Vicky, und 黃穎琪. „An immunity-based distributed multiagent control framework“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37314348.
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Haber, Arne [Verfasser]. „MontiArc - Architectural Modeling and Simulation of Interactive Distributed Systems / Arne Haber“. Aachen : Shaker, 2016. http://d-nb.info/1118258789/34.
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Xu, Yijia. „A SIMULATION PLATFORM FOR EXPERIMENTATION AND EVALUATION OF DISTRIBUTED-COMPUTING SYSTEMS“. Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1229%5F1%5Fm.pdf&type=application/pdf.
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Hu, Xiaolin. „A simulation-based software development methodology for distributed real-time systems“. Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/280514.
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Powered by the rapid advance of computer, network, and sensor/actuator technologies, distributed real-time systems that continually and autonomously control and react to the environment have been widely used. The combination of temporal requirements, concurrent environmental entities, and high reliability requirements, together with distributed processing make the software to control these systems extremely hard to design and difficult to verify. In this work, we developed a simulation-based software development methodology to manage the complexity of distributed real-time software. This methodology, based on discrete event system specification (DEVS), overcomes the "incoherence problem" between different design stages by emphasizing "model continuity" through the development process. Specifically, techniques have been developed so that the same control models that are designed can be tested and analyzed by simulation methods and then easily deployed to the distributed target system for execution. To improve the traditional software testing process where real-time embedded software needs to be hooked up with real sensor/actuators and placed in a physical environment for meaningful test and analysis, we developed a virtual test environment that allows software to be effectively tested and analyzed in a virtual environment, using virtual sensor/actuators. Within this environment, stepwise simulation methods have been developed so that different aspects, such as logic and temporal behaviors, of a real-time system can be tested and analyzed incrementally. Based on this methodology, a simulation and testing environment for distributed autonomous robotic systems is developed. This environment has successfully supported the development and investigation of several distributed autonomous robotic systems. One of them is a "dynamic team formation" system in which mobile robots search for each other, and then form a team dynamically through self-organization. Another system is a scalable robot convoy system in which robots convoy and maintain a line formation in a coordinated way.
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Oguara, Tonworio. „Data distribution strategies for the distributed simulation of multi-agent systems“. Thesis, University of Birmingham, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487221.
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Multi-agent systems are increasingly being employed in the development of concurrent systems in a wide range of areas such as telFommunications, mobile robot control, military simulation, computer games and business process modelling. These systems are however quit complex and it can be difficult to formally verify their properties. As a result, the design and implementation of these systems has been largely experimental. To this end, simulation has a fundamental role to play in the development of multi-agent systems, allowing the agent engineer to learn more about the system and its behaviour or investigate the significance of an optional agent architecture or technology. Thus, with simulation strategies, the engineer can test ideas and theories which might either be too expensive, too complex or even too dangerous to attempt in the real physical system and also focus on particular aspects ofthe system. Typically, agent-based systems are large, extremely complex and complicated, therefore the simulation of a realistic large scale model exceed the capabilities of a conventional sequential computing system. Distributed simulation has thus emerged as an appropriate technology to address this problem. This thesis is concerned with a framework for the distributed simulation of multi-agent systems. The framework namely PDES-MAS, exploits the notion of the agents' sphere of influence to achieve the dynamic partitioning and distribution of the agent model. The thesis presents the design and implementation of the PDES-MAS kernel and proposes a series of dynamic data distribution algorithms in this context. Also presented is a detailed quantitative analysis of the algorithms.
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Kassan, Mark W. „Distributed Interactive Simulation: The Answer to Interoperable Test and Training Instrumentation“. International Foundation for Telemetering, 1996. http://hdl.handle.net/10150/611445.
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International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, CaliforniaThis paper discusses Global Positioning System (GPS) Range Applications Joint Program Office (RAJPO) efforts to foster interoperability between airborne instrumentation, virtual simulators, and constructive simulations using Distributed Interactive Simulation (DIS). In the past, the testing and training communities developed separate airborne instrumentation systems primarily because available technology couldn't encompass both communities' requirements. As budgets get smaller, as requirements merge, and as technology advances, the separate systems can be used interoperably and possibly merged to meet common requirements. Using DIS to bridge the gap between the RAJPO test instrumentation system and the Air Combat Maneuvering Instrumentation (ACMI) training systems provides a defacto system-level interoperable interface while giving both communities the added benefits of interaction with the modeling and simulation world. The RAJPO leads the test community in using DIS. RAJPO instrumentation has already supported training exercises such as Roving Sands 95, Warfighter 95, and Combat Synthetic Test, Training, and Assessment Range (STTAR) and major tests such as the Joint Advanced Distributed Simulation (JADS) Joint Test and Evaluation (JT&E) program. Future efforts may include support of Warrior Flag 97 and upgrading the Nellis No-Drop Bomb Scoring Ranges. These exercises, combining the use of DIS and RAJPO instrumentation to date, demonstrate how a single airborne system can be used successfully to support both test and training requirements. The Air Combat Training System (ACTS) Program plans to build interoperability through DIS into existing and future ACMI systems. The RAJPO is committed to fostering interoperable airborne instrumentation systems as well as interfaces to virtual and constructive systems in the modeling and simulation world. This interoperability will provide a highly realistic combat training and test synthetic environment enhancing the military's ability to train its warfighters and test its advanced weapon systems.
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Park, Jaebok. „A FRAMEWORK TO MODEL COMPLEX SYSTEMS VIA DISTRIBUTED SIMULATION – A CASE STUDY OF THE VIRTUAL TEST BED SIMULATION SYSTEM US“. Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2339.
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As the size, complexity, and functionality of systems we need to model and simulate con-tinue to increase, benefits such as interoperability and reusability enabled by distributed discrete-event simulation are becoming extremely important in many disciplines, not only military but also many engineering disciplines such as distributed manufacturing, supply chain management, and enterprise engineering, etc. In this dissertation we propose a distributed simulation framework for the development of modeling and the simulation of complex systems. The framework is based on the interoperability of a simulation system enabled by distributed simulation and the gateways which enable Com-mercial Off-the-Shelf (COTS) simulation packages to interconnect to the distributed simulation engine. In the case study of modeling Virtual Test Bed (VTB), the framework has been designed as a distributed simulation to facilitate the integrated execution of different simulations, (shuttle process model, Monte Carlo model, Delay and Scrub Model) each of which is addressing differ-ent mission components as well as other non-simulation applications (Weather Expert System and Virtual Range). Although these models were developed independently and at various times, the original purposes have been seamlessly integrated, and interact with each other through Run-time Infrastructure (RTI) to simulate shuttle launch related processes. This study found that with the framework the defining properties of complex systems - interaction and emergence – are realized and that the software life cycle models (including the spiral model and prototyping) can be used as metaphors to manage the complexity of modeling and simulation of the system. The system of systems (a complex system is intrinsically a "system of systems") continuously evolves to accomplish its goals, during the evolution subsystems co-ordinate with one another and adapt with environmental factors such as policies, requirements, and objectives. In the case study we first demonstrate how the legacy models developed in COTS simulation languages/packages and non-simulation tools can be integrated to address a compli-cated system of systems. We then describe the techniques that can be used to display the state of remote federates in a local federate in the High Level Architecture (HLA) based distributed simulation using COTS simulation packages.Ph.D.
Other
Engineering and Computer Science
Modeling and Simulation
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Bangay, Shaun Douglas. „Modelling parallel and distributed virtual reality systems for performance analysis and comparison“. Thesis, Rhodes University, 1997. http://hdl.handle.net/10962/d1006656.
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Most Virtual Reality systems employ some form of parallel processing, making use of multiple processors which are often distributed over large areas geographically, and which communicate via various forms of message passing. The approaches to parallel decomposition differ for each system, as do the performance implications of each approach. Previous comparisons have only identified and categorized the different approaches. None have examined the performance issues involved in the different parallel decompositions. Performance measurement for a Virtual Reality system differs from that of other parallel systems in that some measure of the delays involved with the interaction of the separate components is required, in addition to the measure of the throughput of the system. Existing performance analysis approaches are typically not well suited to providing both these measures. This thesis describes the development of a performance analysis technique that is able to provide measures of both interaction latency and cycle time for a model of a Virtual Reality system. This technique allows performance measures to be generated as symbolic expressions describing the relationships between the delays in the model. It automatically generates constraint regions, specifying the values of the system parameters for which performance characteristics change. The performance analysis technique shows strong agreement with values measured from implementation of three common decomposition strategies on two message passing architectures. The technique is successfully applied to a range of parallel decomposition strategies found in Parallel and Distributed Virtual Reality systems. For each system, the primary decomposition techniques are isolated and analysed to determine their performance characteristics. This analysis allows a comparison of the various decomposition techniques, and in many cases reveals trends in their behaviour that would have gone unnoticed with alternative analysis techniques. The work described in this thesis supports the Performance Analysis and Comparison of Parallel and Distributed Virtual Reality systems. In addition it acts as a reference, describing the performance characteristics of decomposition strategies used in Virtual Reality systems.
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Wu, Jian. „A generalized three-phase coupling method for distributed simulation of power systems“. Diss., Mississippi State : Mississippi State University, 2006. http://sun.library.msstate.edu/ETD-db/ETD-browse/browse.
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Mohamed, Hesham Kamal Arafat. „MINA - a tool for MSC-based performance analysis and simulation of distributed systems“. [S.l. : s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=974451436.
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Albanna, Ahmad. „HARMONIC MODELING AND SIMULATION OF NON-LINEAR PWM INVERTERS IN DISTRIBUTED GENERATION SYSTEMS“. OpenSIUC, 2010. https://opensiuc.lib.siu.edu/dissertations/243.
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The research presented in this dissertation primarily focuses on providing analytical frequency-domain equations that use the system and controller parameters to accurately characterize the power conversion harmonics resulting from the deployment of hysteresis current-controlled inverters within the ac network. In addition, the ac and dc harmonic interactions under both ideal system conditions (constant dc excitation and pure sinusoidal ac voltages) and non-ideal system conditions (harmonic terms are added to the dc and ac sources) are derived for the fixed- and variable-band hysteresis current control. The spectral characteristics, such as frequency orders, spectral magnitude and bandwidth, are given in terms of line and control parameters, a development not only useful in analyzing the harmonic output sensitivity to line and controller parameter variations, but also in filter and system design. Various simulation studies compared results obtained from the developed models to those obtained from the Fourier analysis of MATLAB/Simulink output with very good agreement. The developed models proved their reliability and improved numerical efficiency in harmonic studies compared to those performed using time-domain simulations.
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Brogan, David C. „Simulation levels of detail for control and animation“. Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/8142.
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33
Andersson, Filip. „Fault Diagnosis in Distributed Simulation Systems over Wide Area Networks using Active Probing“. Thesis, Linköpings universitet, Programvara och system, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-124701.
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The domain of distributed simulation is growing rapidly. This growth leads to larger and more complex supporting network architectures with high requirements on availability and reliability. For this purpose, efficient fault-monitoring is required. This work is an attempt to evaluate the viability of an Active probing approach in a distributed simulation system in a wide area network setting. In addition, some effort was directed towards building the probing-software with future extensions in mind. The Active probing approach was implemented and tested against certain performance requirements in a simulated environment. It was concluded that the approach is viable for detecting the health of the network components. However, additional research is required to draw a conclusion about the viability in more complicated scenarios that depend on more than the responsiveness of the nodes. The extensibility of the implemented software was evaluated with the QMOOD-metric and not deemed particularly extensible.
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Brohede, Marcus. „Real-Time Database Support for Distributed Real-Time Simulations“. Thesis, University of Skövde, Department of Computer Science, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-620.
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Simulation is a good way to gain insight into a system, for example during development, without having to run or build the actual system. This is especially true for real-time systems, which often operate in hazardous environments or control critical entities in the 'real' world, making testing of these systems in their real environment unsafe during development.
When building simulations, one simulator is not likely to fit every type of simulation project. Therefore, different simulators, which focus on different aspects of simulation, are built. The High Level Architecture (HLA) from the Defense Modeling and Simulation Office (DMSO) is an architecture for distributed simulations providing a means to communicate between different simulations.
However, the HLA standard has limitations if viewed from a real-time perspective. For example, there is no built-in support for fault tolerance. In this thesis some of the limitations in HLA are identified and an extended architecture that uses a distributed active real-time database as a way to overcome these limitations is presented. One of the major advantages with this new extended HLA architecture is that it is still compliant with HLA, i.e., no modifications have been made to the HLA interfaces.
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Zeswitz, Steven Randall. „NPSNET integration of distributed interactive simulation (DIS) protocol for communication architecture and information interchange /“. Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1993. http://handle.dtic.mil/100.2/ADA275061.
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Tacic, Ivan. „Efficient Synchronized Data Distribution Management in Distributed Simulations“. Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6822.
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Data distribution management (DDM) is a mechanism to interconnect data producers and data consumers in a distributed application. Data producers provide useful data to consumers in the form of messages. For each message produced, DDM determines the set of data consumers interested in receiving the message and delivers it to those consumers.
We are particularly interested in DDM techniques for parallel and distributed discrete event simulations. Thus far, researchers have treated synchronization of events (i.e. time management) and DDM independent of each other. This research focuses on how to realize time managed DDM mechanisms. The main reason for time-managed DDM is to ensure that changes in the routing of messages from producers to consumers occur in a correct sequence. Also time managed DDM avoids non-determinism in the federation execution, which may result in non-repeatable executions.
An optimistic approach to time managed DDM is proposed where one allows DDM events to be processed out of time stamp order, but a detection and recovery procedure is used to recover from such errors. These mechanisms are tailored to the semantics of the DDM operations to ensure an efficient realization. A correctness proof is presented to verify the algorithm correctly synchronizes DDM events.
We have developed a fully distributed implementation of the algorithm within the framework of the Georgia Tech Federated Simulation Development Kit (FDK) software. A performance evaluation of the synchronized DDM mechanism has been completed in a loosely coupled distributed system consisting of a network of workstations connected over a local area network (LAN). We compare time-managed versus unsynchronized DDM for two applications that exercise different mobility patterns: one based on a military simulation and a second utilizing a synthetic workload.
The experiments and analysis illustrate that synchronized DDM performance depends on several factors: the simulations model (e.g. lookahead), applications mobility patterns and the network hardware (e.g. size of network buffers). Under certain mobility patterns, time-managed DDM is as efficient as unsynchronized DDM. There are also mobility patterns where time-managed DDM overheads become significant, and we show how they can be reduced.
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Villarroel, Felipe Andres Cruz. „Particle flow simulation using a parallel FMM on distributed memory systems and GPU architectures“. Thesis, University of Bristol, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.541607.
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Shadid, Ahmad Jamal. „Efficient load balancing techniques for Real-Time RTI-based large-scale distributed simulation systems“. Thesis, University of Ottawa (Canada), 2008. http://hdl.handle.net/10393/28023.
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The Real-time extension of the High Level Architecture (HLA) is very essential and useful for many large-scale distributed simulation systems. Most previous attempts to design the Real-Time Run Time Infrastructure (RT-RTI) have enabled the usage of supported scheduling and prioritization services from underlying Real-time operating systems (RTOSs) augmented by communication QoS mechanisms. In this thesis, we wish to build on this functionality by proposing an algorithm that differentiates services processing within the RTI itself by incorporating resources' load balancing mechanisms with several scheduling and allocation policies. We focus our efforts on making the RTIs internal operations organized and well suited to the tasks and services it will be providing throughout the lifetime of HLA-compliant federations.
The load-balancing mechanisms incorporated within the proposed system have been designed to build an efficient management scheme of the available processing resources. The proposed design have been heavily verified and tested from all related perspectives under the constraints of the Discrete Event System Specification (DEVS), especially the (RT-DEVS). This formalized system design approach have propagated a totally-new RT-RTI design that solves most of the shortcomings demonstrated and shown by previous designs.
We have proved through our analytical performance evaluation and simulation experiments that our proposed real-time RTI framework exhibits a better performance in all terms, especially in the number of tasks served within deadlines when compared with existing RT-RTI frameworks. Our simulation results from the design model of the RT-DEVS formalism have verified the experimental results of the real implementation of the proposed RT-RTI design. In addition, these simulation models are capable of predicting key factors that may affect the performance of the RT-RTI core system, and could be used as guidance in searching for the optimal design.
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Stockar, Stephanie. „Model-Order Reduction for Nonlinear Distributed Parameter Systems with Application to Internal Combustion Engine Modeling and Simulation“. The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1372847649.
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Rappin, Noel. „A framework for teaching learners to model by focusing complexity of modeling and simulation tools“. Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/8248.
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Rao, Sachit Srinivasa. „Sliding mode control in mechanical, electrical and thermal distributed processes“. Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1164817694.
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42
Ďuriš, Anton. „Simulace distribuovaných systémů“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-442811.
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This thesis is focused on distributed systems modeling using Petri nets. Distributed systems are increasingly being implemented in applications and computing systems, where their task is to ensure sufficient performance and stability for a large number of its users. When modeling a distributed systems, stochastic behavior of Petri nets is important, which will provide more realistic simulations. Therefore, this thesis focuses mainly on timed Petri nets. The theoretical part of this thesis summarizes distributed systems, their properties, types and available architectures, as well as Petri nets, their representation, types and the principle of an operation. In the practical part, two models were implemented, namely a horizontally scaled web application divided into several services with a distributed database and a large grid computing system, more precisely the BOINC platform with the Folding@home project. Both models were implemented using the PetNetSim library of Python. The goal of this thesis is to perform simulations on the created models for different scenarios of their behavior.
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Aybar, Guray. „Simulation And Performance Evaluation Of A Distributed Real-time Communication Protocol For Industrial Embedded Systems“. Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613921/index.pdf.
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The Dynamic Distributed Dependable Real-Time Industrial communication Protocol (D3RIP) provides service guarantees for Real-Time traffic and integrates the dynamically changing requirements of automation applications in their operation to efficiently utilize the resources. The protocol dynamically allocates the network resources according to the respective system state. To this end, the protocol architecture consists of an Interface Layer that provides time-slotted operation and a Coordination Layer that assigns each time slot to a unique transmitter device based on a distributed computation.
In this thesis, a software simulator for D3RIP is developed. Using the D3RIP Simulator, modifications in D3RIP can be easily examined without facing complexities in real implementations and extensive effort in terms of time and cost. The simulator simulates the Interface Layer, the Coordination Layer and additionally, the Shared Medium. Hence, using the simulator, the system-protocol couple can be easily analyzed, tested and further improvements on D3RIP can be achieved with the least amount of effort.
The simulator implements the Timed Input Output Automata (TIOA) models of the D3RIP stack components using C++. The resulting code is compiled on GCC (Gnu Compiler Collection). The logs of the simulation runs and the real system with 2 devices connected via cross 100MbE cables are compared. In a 3ms time slot, the simulator and the system incidents differ about 135µs on the average, causing no asynchronousity in their instantaneous operational states. The D3RIP Simulator is useful in keeping track of any variable in the D3RIP system automaton at any instant up to 1µ
s resolution.
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Darling, James Campbell Charles. „The application of distributed and mobile computing techniques to advanced simulation and virtual reality systems“. Thesis, University of Surrey, 1998. http://epubs.surrey.ac.uk/843917/.
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Current technologies for creating distributed simulations or virtual environments are too limited in terms of scalability and flexibility, particularly in the areas of network saturation, distribution of VR scenes, and co-ordination of large systems of active objects. This thesis proposes the use of mobile and distributed computing technology to alleviate some of these limitations. A study of contemporary technologies for distributed simulation and networked virtual environments has been made, examining the benefits and drawbacks of different techniques. The main theory that has been investigated is that processing of a global simulation space should be spread over a network of computers, the principle of locality cutting the network bandwidth required. Using a prototype language for distributed graph processing, which fully supports mobile programming, experimental systems have been developed to demonstrate the use of distributed processing in creating large-scale virtual environments. The working examples created show that the ideas proposed for distribution of interactive virtual environments are valid, and that mobile programming techniques provide a new direction of development for the field of simulation. A more detailed summary of the work is given in Appendix D. Five publications to date (shown overleaf) have resulted from my involvement in the work, and a number of others have resulted from the overall project.
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Abich, Geancarlo. „Extending FreeRTOS to support dynamic and distributed task mapping in multiprocessor systems“. reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/164048.
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Sistemas de Multiprocessados Embarcados são uma realidade, tanto no setor da indústria e quanto no setor acadêmico. Esses dispositivos oferecem capacidades de processamento paralelo objetivando cobrir requisitos cada vez maiores de aplicações complexas. A carga de trabalho subjacente das aplicações é suscetível a variação em tempo de execução o que, se não for tratada adequadamente, pode levar a degradação de eficiência em desempenho e energia. O aumento contínuo da complexidade da carga de trabalho das aplicações, bem como do tamanho dos sistemas multiprocessados emergentes, requer soluções de mapeamento dinâmicas e distribuídas. A maioria das técnicas de mapeamento propostas são implementações personalizadas, considerando um sistema operacional interno desenvolvido para uma arquitetura de processador específica. Essa prática restringe sua aplicação em outras plataformas, levando a um design extra, revalidação e, consequentemente, um custo oculto que pode ser um tanto quanto alto. Neste cenário, esta dissertação propõe a extensão do FreeRTOS para suportar mapeamento dinâmico e distribuído de tarefas em sistemas multiprocessados. O FreeRTOS tem portabilidade para mais de 30 arquiteturas de processadores embarcados, aumentando a portabilidade de software e reduzindo o tempo de desenvolvimento. A extensão proposta utiliza técnicas de mapeamento que permitem ao FreeRTOS atender a altas demandas de mapeamento de aplicações em tempo de execução. Outra contribuição deste trabalho é o desenvolvimento de um framework que permite a exploração de grandes sistemas fornecendo, simultaneamente, resultados para depuração. O framework proposto possibilita a geração automática de plataformas multiprocessadas considerando seu tamanho, a arquitetura do processador e um conjunto de aplicações. A descrição da plataforma resultante é altamente escalável permitindo extração de dados em tempo de execução e alta depuração. Estas características permitiram validar a extensão do FreeRTOS proposta em mais de uma arquitetura de processador da família ARM Cortex-M. Os casos de teste foram executados em plataformas de grande escala e em diferentes níveis de abstração com casos de mais de 120 aplicações incorporando mais de 600 tarefas processadas. Os resultados mostram que a extensão proposta apresenta resultados melhores ou iguais à literatura.Embedded Multiprocessor systems are a reality, in both industry and academia sectors. Such devices offer parallel processing capabilities, aiming at covering the increasing requirements of complex applications. Underlying application workloads are susceptible to variation at runtime, which if not properly handled, may lead to the performance and power efficiency degradation. The continuous increase in the complexity of application workload and the size of emerging multiprocessor systems, calls for dynamic and distributed mapping solutions. The majority of the promoted mapping techniques are bespoke implementations, which consider an in-house operating system developed to a particular processor architecture. This practice restricts its adoption in other platforms, leading to extra design time, re-validation and, consequentially, a hidden cost that may well be quite high. In this scenario, this dissertation proposes a FreeRTOS extension that integrates the support to dynamic and distributed tasks mapping in multiprocessor systems. FreeRTOS is portable to more than 30 embedded processors architectures, increasing software portability and reducing development time. The proposed extension employs mapping techniques allowing FreeRTOS for handle high demands of application mapping in runtime. Another contribution of this work is the development of a framework, which enables the exploration of large systems while providing debugging facilities. The proposed framework provides the automatic generation of multiprocessor platforms, considering parameters of size, processor architecture, and an application set. The resulting platform description is high scalable while allows runtime data extraction and high debugging. These features allowed to validate the proposed FreeRTOS extension in more than one processor architecture from ARM Cortex-M family. Test cases were executed on large-scale platforms and at different levels of abstraction with cases of more than 120 applications incorporating more than 600 tasks processed. The results show that the proposed extension presents better or equal results to the literature.
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Arad, Cosmin Ionel. „Programming Model and Protocols for Reconfigurable Distributed Systems“. Doctoral thesis, KTH, Programvaruteknik och Datorsystem, SCS, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-122311.
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Distributed systems are everywhere. From large datacenters to mobile devices, an ever richer assortment of applications and services relies on distributed systems, infrastructure, and protocols. Despite their ubiquity, testing and debugging distributed systems remains notoriously hard. Moreover, aside from inherent design challenges posed by partial failure, concurrency, or asynchrony, there remain significant challenges in the implementation of distributed systems. These programming challenges stem from the increasing complexity of the concurrent activities and reactive behaviors in a distributed system on the one hand, and the need to effectively leverage the parallelism offered by modern multi-core hardware, on the other hand. This thesis contributes Kompics, a programming model designed to alleviate some of these challenges. Kompics is a component model and programming framework for building distributed systems by composing message-passing concurrent components. Systems built with Kompics leverage multi-core machines out of the box, and they can be dynamically reconfigured to support hot software upgrades. A simulation framework enables deterministic execution replay for debugging, testing, and reproducible behavior evaluation for largescale Kompics distributed systems. The same system code is used for both simulation and production deployment, greatly simplifying the system development, testing, and debugging cycle. We highlight the architectural patterns and abstractions facilitated by Kompics through a case study of a non-trivial distributed key-value storage system. CATS is a scalable, fault-tolerant, elastic, and self-managing key-value store which trades off service availability for guarantees of atomic data consistency and tolerance to network partitions. We present the composition architecture for the numerous protocols employed by the CATS system, as well as our methodology for testing the correctness of key CATS algorithms using the Kompics simulation framework. Results from a comprehensive performance evaluation attest that CATS achieves its claimed properties and delivers a level of performance competitive with similar systems which provide only weaker consistency guarantees. More importantly, this testifies that Kompics admits efficient system implementations. Its use as a teaching framework as well as its use for rapid prototyping, development, and evaluation of a myriad of scalable distributed systems, both within and outside our research group, confirm the practicality of Kompics.QC 20130520
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Arad, Cosmin. „Programming Model and Protocols for Reconfigurable Distributed Systems“. Doctoral thesis, SICS, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:ri:diva-24202.
Der volle Inhalt der QuelleAnnotation:
Distributed systems are everywhere. From large datacenters to mobile devices, an ever richer assortment of applications and services relies on distributed systems, infrastructure, and protocols. Despite their ubiquity, testing and debugging distributed systems remains notoriously hard. Moreover, aside from inherent design challenges posed by partial failure, concurrency, or asynchrony, there remain significant challenges in the implementation of distributed systems. These programming challenges stem from the increasing complexity of the concurrent activities and reactive behaviors in a distributed system on the one hand, and the need to effectively leverage the parallelism offered by modern multi-core hardware, on the other hand. This thesis contributes Kompics, a programming model designed to alleviate some of these challenges. Kompics is a component model and programming framework for building distributed systems by composing message-passing concurrent components. Systems built with Kompics leverage multi-core machines out of the box, and they can be dynamically reconfigured to support hot software upgrades. A simulation framework enables deterministic execution replay for debugging, testing, and reproducible behavior evaluation for large-scale Kompics distributed systems. The same system code is used for both simulation and production deployment, greatly simplifying the system development, testing, and debugging cycle. We highlight the architectural patterns and abstractions facilitated by Kompics through a case study of a non-trivial distributed key-value storage system. CATS is a scalable, fault-tolerant, elastic, and self-managing key-value store which trades off service availability for guarantees of atomic data consistency and tolerance to network partitions. We present the composition architecture for the numerous protocols employed by the CATS system, as well as our methodology for testing the correctness of key CATS algorithms using the Kompics simulation framework. Results from a comprehensive performance evaluation attest that CATS achieves its claimed properties and delivers a level of performance competitive with similar systems which provide only weaker consistency guarantees. More importantly, this testifies that Kompics admits efficient system implementations. Its use as a teaching framework as well as its use for rapid prototyping, development, and evaluation of a myriad of scalable distributed systems, both within and outside our research group, confirm the practicality of Kompics.Kompics
CATS
REST
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Derasevic, Sinisa. „Node fault tolerance for distributed embedded systems based on FTT-Ethernet“. Doctoral thesis, Universitat de les Illes Balears, 2018. http://hdl.handle.net/10803/666276.
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[eng] When Distributed Embedded Systems (DESs) operate in evolving environments,
changing requirements might be imposed on the system, and thus the system
needs the ability to adapt to them. Furthermore, when such systems are
employed for real-time (RT) critical applications, both support for satisfying stringent RT guarantees and attaining a high level of reliability must be provided.
The Flexible Time-Triggered (FTT) communication paradigm provides support
for changing real-time traffic requirements in adaptive RT DESs, i.e., it provides
RT flexibility. The different implementations of FTT on Ethernet have recently
added to FTT advantages of Ethernet such as high bandwidth, low cost and, since
Ethernet is the de facto Link Layer standard of many communication systems,
also an easier potential integration.
A specific FTT implementation on Ethernet, called Flexible Time-Triggered
Ethernet Star (FTTRS), has been recently proposed to add mechanisms to
tolerate faults in the channel as a means to increase the reliability of the final
system. However, it is known that to reach a very high level of system reliability it
is crucial to also tolerate faults in the computation nodes. This is so because the
computation nodes are usually the most complex components of a DES and,
hence, they are less reliable than most of the components that constitute the
channel, e.g. the links.
This thesis proposes a node replication architecture and appropriate node faulttolerance
(FT) mechanisms so as to attain a high level of reliability for critical RT
DES. The proposed architecture and FT mechanisms are based on an active node
replication strategy with distributed majority voting. The mechanisms are
designed on top of FTTRS in order to take advantage of the features that the FTT
paradigm and the FTTRS communication subsystem already provide in terms of
channel RT flexibility and channel fault tolerance.
We start by introducing the concepts, terminology and methodology used to
specify, design and test a fault-tolerant system. Special attention has been paid to
describing the specific fault-tolerance techniques used in this dissertation. Also,
we present the foundations on top of which we develop our node FT mechanisms.
In particular we present the FTT communication paradigm and the details of the
FTTRS itself.
Then, we describe the main contributions of this dissertation. We start by a
general description of the overall system. Then, we clarify what types of faults
(fault model) we address, and we thoroughly describe and classify all the
manners in which these faults may manifest (failure model). Afterwards we focus
on describing the proposed FT mechanisms based on both active node replication and FTTRS. Once this description is completed, we propose a realization of the
designed FT mechanisms for the specific case of control applications.
Moreover, in order to test and verify the correctness of our node replication
architecture and FT mechanisms, we present a simulation model as well as a real
prototype. We use these simulation model and real prototype to thoroughly inject
faults (in terms of all the manners in which faults can manifest according to the
failure model) and, then, we inspect if the mechanisms function as intended in
both of them. Finally, we build a dependability model to quantify the level of
reliability attainable by a DES relying on our node replication architecture and FT
mechanisms.
By means of the work described in the current dissertation we prove the
following thesis statement:
“It is possible to attain high levels of reliability of adaptive critical RT DES that
rely on a reliable and flexible RT communication subsystem based on an FTT
implementation on Ethernet by providing FT mechanisms for the nodes.”[spa] Los sistemas empotrados distribuidos son sistemas compuestos por un conjunto de nodos interconectados que trabajan para lograr un objetivo común y que forman parte de un sistema mecánico o eléctrico más grande. Los nodos suelen estar interconectados por medio de una red de comunicación. En cuanto a las redes de comunicación, en las últimas décadas Ethernet se ha convertido en una de las tecnologías más populares debido a sus muchas ventajas tales como simplicidad, anchos de banda siempre crecientes y bajo coste, entre otras. Cuando los sistemas empotrados distribuidos forman parte de sistemas más grandes que ejecutan aplicaciones críticas, a menudo existe la necesidad de proporcionar un soporte para requisitos de respuesta en tiempo real y para la consecución de una muy elevada fiabilidad. La tecnología original de Ethernet no proporciona ningún soporte de este tipo. Por lo tanto, en esta disertación usamos el recientemente propuesto subsistema de comunicación que recibe el nombre de Flexible Time-Triggered Replicated Star (FTTRS) como medio para interconectar los nodos de los sistemas empotrados distribuidos que ejecutan aplicaciones críticas. FTTRS toma la tecnología de red Ethernet como base y sobre ella proporciona mecanismos para soportar respuesta en tiempo real y elevada fiabilidad. La respuesta en tiempo real es proporcionada por el uso del paradigma de comunicación Flexible Time-Triggered (FTT) implementado sobre el protocolo Ethernet el cual, además de la provisión de garantías de tiempo real, también proporciona flexibilidad, en concreto, la capacidad de modificar el comportamiento de la red en tiempo de ejecución mientras se mantienen las garantías de tiempo real comprometidas. La elevada fiabilidad en FTTRS se logra mediante mecanismos que toleran los fallos que podrían afectar a la comunicación entre nodos. Sin embargo, proporcionar tolerancia a fallos únicamente al subsistema de comunicación no es suficiente para satisfacer los requisitos de fiabilidad más exigentes de las aplicaciones críticas. Para alcanzar altos niveles de fiabilidad, los fallos en los propios nodos del sistema empotrado distribuido también deben ser tratados. En consecuencia, hemos diseñado varios mecanismos de tolerancia a fallos para tratar los fallos que puedan afectar al correcto funcionamiento de los nodos. Estos mecanismos aprovechan las características del subsistema de comunicación FTTRS y del paradigma de comunicación FTT subyacente. Concluyendo, en esta tesis veremos cómo podemos, con la introducción de mecanismos específicos para tolerar los fallos de los nodos de un sistema empotrado distribuido basado en FTTRS, lograr muy elevados niveles de fiabilidad para el sistema en su conjunto. Además del diseño de los mecanismos de tolerancia a fallos de los nodos, también mostraremos cómo se puede evaluar la fiabilidad resultante y estableceremos cuál es el beneficio obtenido, comparando dicha fiabilidad con la de una versión no tolerante a fallos del mismo sistema.
[cat] Els sistemes encastats distribuïts són sistemes composts per un conjunt de nodes interconnectats que treballen per aconseguir un objectiu comú i que formen part d’un sistema mecànic o elèctric més gran. Els nodes solen estar interconnectats mitjançant una xarxa de comunicació. Quant a les xarxes de comunicació, en les últimes dècades Ethernet s’ha convertit en una de les tecnologies més populars a causa dels seus molts avantatges tals com a simplicitat, amples de banda sempre creixents i baix cost, entre d’altres. Quan els sistemes encastats distribuïts formen part de sistemes més grans que executen aplicacions crítiques, sovint existeix la necessitat de proporcionar un suport per a requisits de resposta en temps real i per a la consecució d’una molt elevada fiabilitat. La tecnologia original d’Ethernet no proporciona cap suport d’aquest tipus. Per tant, en aquesta dissertació usem el recentment proposat subsistema de comunicació que rep el nom de Flexible Time-Triggered Replicated Star (FTTRS) com a mitjà per interconnectar els nodes dels sistemes encastats distribuïts que executen aplicacions crítiques. FTTRS pren la tecnologia de xarxa Ethernet com a base i sobre ella proporciona mecanismes per suportar resposta en temps real i elevada fiabilitat. La resposta en temps real és proporcionada per l’ús del paradigma de comunicació Flexible Time-Triggered (FTT) implementat sobre el protocol Ethernet el qual, a més de la provisió de garanties de temps real, també proporciona flexibilitat, en concret, la capacitat de modificar el comportament de la xarxa en temps d’execució mentre es mantenen les garanties de temps real compromeses. L’elevada fiabilitat en FTTRS s’aconsegueix mitjançant mecanismes que toleren les fallades que podrien afectar a la comunicació entre nodes. En qualsevol cas, proporcionar tolerància a fallades únicament al subsistema de comunicació no és suficient per satisfer els requisits de fiabilitat més exigents de les aplicacions crítiques. Per aconseguir alts nivells de fiabilitat, les fallades en els propis nodes del sistema encastat distribuït també han de ser tractades. En conseqüència, hem dissenyat diversos mecanismes de tolerància a fallades per tractar les fallades que puguin afectar al correcte funcionament dels nodes. Aquests mecanismes aprofiten les característiques del subsistema de comunicació FTTRS i del paradigma de comunicació FTT subjacent. Concloent, en aquesta tesi veurem com podem, amb la introducció de mecanismes específics per tolerar les fallades dels nodes d’un sistema encastat distribuït basat en FTTRS, aconseguir molt elevats nivells de fiabilitat per al sistema en el seu conjunt. A més del disseny dels mecanismes de tolerància a fallades dels nodes, també mostrarem com es pot avaluar la fiabilitat resultant i establirem quin és el benefici obtingut, comparant aquesta fiabilitat amb la d’una versió no tolerant a fallades del mateix sistema.
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Kachirski, Oleg. „AN INTERACTIVE DISTRIBUTED SIMULATION FRAMEWORK WITH APPLICATION TO WIRELESS NETWORKS AND INTRUSION DETECTION“. Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2531.
Der volle Inhalt der QuelleAnnotation:
In this dissertation, we describe the portable, open-source distributed simulation framework (WINDS) targeting simulations of wireless network infrastructures that we have developed. We present the simulation framework which uses modular architecture and apply the framework to studies of mobility pattern effects, routing and intrusion detection mechanisms in simulations of large-scale wireless ad hoc, infrastructure, and totally mobile networks. The distributed simulations within the framework execute seamlessly and transparently to the user on a symmetric multiprocessor cluster computer or a network of computers with no modifications to the code or user objects. A visual graphical interface precisely depicts simulation object states and interactions throughout the simulation execution, giving the user full control over the simulation in real time. The network configuration is detected by the framework, and communication latency is taken into consideration when dynamically adjusting the simulation clock, allowing the simulation to run on a heterogeneous computing system. The simulation framework is easily extensible to multi-cluster systems and computing grids. An entire simulation system can be constructed in a short time, utilizing user-created and supplied simulation components, including mobile nodes, base stations, routing algorithms, traffic patterns and other objects. These objects are automatically compiled and loaded by the simulation system, and are available for dynamic simulation injection at runtime. Using our distributed simulation framework, we have studied modern intrusion detection systems (IDS) and assessed applicability of existing intrusion detection techniques to wireless networks. We have developed a mobile agent-based IDS targeting mobile wireless networks, and introduced load-balancing optimizations aimed at limited-resource systems to improve intrusion detection performance. Packet-based monitoring agents of our IDS employ a CASE-based reasoner engine that performs fast lookups of network packets in the existing SNORT-based intrusion rule-set. Experiments were performed using the intrusion data from MIT Lincoln Laboratories studies, and executed on a cluster computer utilizing our distributed simulation system.Ph.D.
School of Computer Science
Engineering and Computer Science
Computer Science
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Ollerton, Robert Milton. „Using discrete-event simulation to address the probe effect in software testing of real-time distributed systems“. Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1998. http://handle.dtic.mil/100.2/ADA356089.
Der volle Inhalt der QuelleAnnotation:
Thesis (M.S. in Software Engineering) Naval Postgraduate School, September 1998."September 1998." Thesis advisor(s): Timothy Shimeall. Includes bibliographical references (p. 69-71). Also available online.