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1

Cross, Patrick L. "Fuzzy reliability modeling of distributed client-server systems." Morgantown, W. Va. : [West Virginia University Libraries], 1998. http://etd.wvu.edu/templates/showETD.cfm?recnum=149.

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2

Dzimano, Gwinyai J. "Modeling Of Photovoltaic Systems." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1228307443.

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3

Segala, Roberto. "Modeling and verification of randomized distributed real-time systems." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36560.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.
Includes bibliographical references (p. 267-274) and index.
by Roberto Segala.
Ph.D.
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4

Seitz, Timothy M. "Modeling and Robust Stability of Advanced, Distributed Control Systems." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1497201155817062.

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5

Luo, Yang. "Performance modeling and load balancing for Distributed Java Virtual Machine." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B41509043.

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6

Luo, Yang, and 羅陽. "Performance modeling and load balancing for Distributed Java Virtual Machine." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B41509043.

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7

Lin, Yi-Tzer. "Modeling and analysis for message reachability in distributed manufacturing systems." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/24292.

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8

Alipourazadi, Shahram. "New approaches to linear graph modeling of distributed-parameter systems." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/41896.

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Analytical modeling is an important fundamental step in the development of procedures such as simulation, design, control, and health monitoring of engineering systems. Typically, physical properties such as inertia, flexibility (or stiffness), capacitance, inductance, and energy dissipation (mechanical damping or electrical resistance) are spatially distributed in a physical dynamic system. Often in dynamic models, these characteristics are approximated by spatially “lumped” elements. For better accuracy, however, the true distributed nature of these parameters has to be incorporated into the model. Distributed parameter (DP) models are important in this context. This thesis concerns the representation of distributed parameter engineering systems using linear graphs (LG). Among possible approaches for modeling of engineering systems, linear graphs are used in the present work due to its numerous advantages as discussed in the thesis. An engineering system may possess physical properties in many domains such as mechanical, electrical, thermal, and fluid. Mechatronic systems are multi-domain systems, which typically possess at least electro-mechanical characteristics. Linear graphs present a domain-independent unified approach for modeling multi-domain systems. Furthermore, linear graphs have beneficial features in the development of automatic procedures for modeling and designing engineering systems, which are long-term goals of the present work. In this thesis, approaches are developed for the representation of distributed-parameter systems as LG models. Different approaches are presented for this purpose and compared. The LG modeling approach enables one to visualize the system structure before formulating the dynamic equations of the system. For example, for a DP system the structure of its LG model may possess a well-defined pattern. In this work, vector linear graphs are introduced to take advantage of these patterns. General notations and elements are defined for vector linear graphs. As a result of this development a new single element is generated for use in the modeling of distributed-parameter systems, particularly in the mechanical domain. In this thesis, a software toolbox is enhanced and presented for LG modeling, which is able to automatically extract the state space equations of a mechatronic system. This software tool is provided free for academic use and is accessible through the Internet. Throughout the thesis many comprehensive examples are provided to illustrate the developed concepts and procedures and their application.
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Jung, Jin Woo. "Modeling and control of fuel cell based distributed generation systems." Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1116451881.

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Thesis (Ph. D.)--Ohio State University, 2005.
Title from first page of PDF file. Document formatted into pages; contains xvi, 209 p.; also includes graphics. Includes bibliographical references (p. 202-209). Available online via OhioLINK's ETD Center
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10

Robinson, Kevin Michael. "Modeling of Distributed Naval Ship Systems using Architecture Flow Optimization." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83884.

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Successful future surface combatants in the US Navy must embrace the growing integration and interdependency of propulsive and combat systems. Traditionally, the development of Hull, Mechanical and Electrical systems has been segregated from the development of weapons and sensors. However, with the incorporation of high energy weapons into future ship configurations, ship design processes must evolve to embrace the concept of a System of Systems being the only way to achieve affordable capability in our future fleets. This thesis bridges the gap between the physical architecture of components within a ship and the way in which they are logically connected to model the energy flow through a representative design and provide insight into sizing requirements of both system components and their connections using an Architecture Flow Optimization (AFO). This thesis presents a unique method and tool to optimize naval ship system logical and physical architecture considering necessary operational conditions and possible damage scenarios. The particular and unique contributions of this thesis are: 1) initially only energy flow is considered without explicit consideration of commodity flow (electric, mechanical, chilled water, etc.), which is calculated in post-processing; 2) AFO is applied to a large and complex naval surface combatant system of systems, demonstrating its scalability; 3) data necessary for the AFO is extracted directly from a naval ship synthesis model at a concept exploration level of detail demonstrating its value in early stage design; and 4) it uses network-based methods which make it adaptable to future knowledge-based network analysis methods and approaches.
Master of Science
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11

Zhang, Hanzhong. "A moving boundary problem in a distributed parameter system with application to diode modeling." Access restricted to users with UT Austin EID, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3037035.

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12

Qi, Chenkun. "Modeling of nonlinear distributed parameter system for industrial thermal processes /." access full-text access abstract and table of contents, 2009. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?phd-meem-b23750911f.pdf.

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Thesis (Ph.D.)--City University of Hong Kong, 2009.
"Submitted to Department of Manufacturing Engineering and Engineering Management in partial fulfillment of the requirements for the degree of Doctor of Philosophy." Includes bibliographical references (leaves 167-187)
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13

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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14

Chan, Patrick HonChun. "Modeling distributed asynchronous processes using events and calculus of communicating systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0022/MQ62197.pdf.

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15

Israr, Toqeer. "Modeling and Performance Analysis of Distributed Systems with Collaboration Behaviour Diagrams." Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/30950.

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The use of distributed systems, involving multiple components, has become a common industry practice. However, modeling the behaviour of such systems is a challenge, especially when the behavior consists of several collaborations of different parties, each involving possibly several starting (input) and ending (output) events of the involved components. Furthermore, the global behavior should be described as a composition of several sub-behaviours, in the following called collaborations, and each collaboration may be further decomposed into several sub-collaborations. We assume that the performance of the elementary sub-collaborations is known, and that the performance of the global behavior should be determined from the performance of the contained elementary collaborations and the form of the composition. A collaboration, in this thesis, is characterized by a partial order of input and output events, and the performance of the collaboration is defined by the minimum delays required for a given output event with respect to an input event. This is a generalization of the semantics of UML Activities, where all input events are assumed to occur at the same time, and all output events occur at the same time. We give a semantic definition of the dynamic behavior of composed collaborations using the composition operators for control flow from UML Activity diagrams, in terms of partial order relationships among the involved input and output events. Based on these semantics, we provide formulas for calculating the performance of composed collaborations in terms of the performance of the sub-collaborations, where each delay is characterized by (a) a fixed value, (b) a range of values, and (c) a distribution (in the case of stochastic behaviours). We also propose approximations for the case of stochastic behavior with Normal distributions, and discuss the expected errors that may be introduced due to ignoring of shared resources or possible dependencies in the case of stochastic behaviours. A tool has been developed for evaluating the performance of complex collaborations, and examples and case studies are discussed to illustrate the applicability of the performance analysis and the visual notation which we introduced for representing the partial-order relationships of the input and output events.
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16

Bailey-Kellogg, Christopher J. "The spatial aggregation language for modeling and controlling distributed physical systems /." The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488186329502658.

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17

Kounev, Samuel. "Performance engineering of distributed component based systems : benchmarking, modeling and performance prediction /." Aachen : Shaker, 2006. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=014763552&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.

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18

Wang, Caisheng. "Modeling and Control of Hybrid Wind/Photovoltaic/Fuel Cell Distributed Generation Systems." Thesis, Montana State University, 2006. http://etd.lib.montana.edu/etd/2006/wang/WangC0806.pdf.

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Due to ever increasing energy consumption, rising public awareness of environmental protection, and steady progress in power deregulation, alternative (i.e., renewable and fuel cell based) distributed generation (DG) systems have attracted increased interest. Wind and photovoltaic (PV) power generation are two of the most promising renewable energy technologies. Fuel cell (FC) systems also show great potential in DG applications of the future due to their fast technology development and many merits they have, such as high efficiency, zero or low emission (of pollutant gases) and flexible modular structure. The modeling and control of a hybrid wind/PV/FC DG system is addressed in this dissertation. Different energy sources in the system are integrated through an AC bus. Dynamic models for the main system components, namely, wind energy conversion system (WECS), PV energy conversion system (PVECS), fuel cell, electrolyzer, power electronic interfacing circuits, battery, hydrogen storage tank, gas compressor and gas pressure regulator, are developed. Two types of fuel cells have been modeled in this dissertation: proton exchange membrane fuel cell (PEMFC) and solid oxide fuel cell (SOFC). Power control of a grid-connected FC system as well as load mitigation control of a stand-alone FC system are investigated. The pitch angle control for WECS, the maximum power point tracking (MPPT) control for PVECS, and the control for electrolyzer and power electronic devices, are also addressed in the dissertation. Based on the dynamic component models, a simulation model for the proposed hybrid energy system has been developed using MATLAB/Simulink. The overall power management strategy for coordinating the power flows among the different energy sources is presented in the dissertation. Simulation studies have been carried out to verify the system performance under different scenarios using a practical load profile and real weather data. The results show that the overall power management strategy is effective and the power flows among the different energy sources and the load demand is balanced successfully. The DG's impacts on the existing power system are also investigated in this dissertation. Analytical methods for finding optimal sites to deploy DG sources in power systems are presented and verified with simulation studies.
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19

Behrens, Diogo, Marco Serafini, Sergei Arnautov, Flavio Junqueira, and Christof Fetzer. "Scalable error isolation for distributed systems: modeling, correctness proofs, and additional experiments." Technische Universität Dresden, 2015. https://tud.qucosa.de/id/qucosa%3A29539.

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20

Behrens, Diogo, Marco Serafini, Sergei Arnautov, Flavio Junqueira, and Christof Fetzer. "Scalable error isolation for distributed systems: modeling, correctness proofs, and additional experiments." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-203622.

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21

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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22

Assadi, Morteza. "Modeling and optimization of closed-loop systems with generally distributed failure/service times." Diss., Wichita State University, 2008. http://hdl.handle.net/10057/2068.

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Research on the maintenance of repairable machines has mostly focused on an open-loop system consisting of an infinite number of identical machines working in a production system, and a repair shop along with a spare parts inventory. The machines used in the production system are subject to failure and are replaced upon failure utilizing a spare part inventory. Meanwhile, the failed parts are repaired in the service center and are sent back to the spare parts inventory. The parts after repair are considered as good as new. In this dissertation it is assumed that the population of machines in the system is finite resulting in a closed-loop system. However, this changes the nature of problem in which the well-known queuing systems and stochastic processes need to be modified accordingly. Moreover, the times in the system are assumed to be generally distributed. For this system, the performance of the overall system is evaluated and the capacities of the repair shop together with the level of spares in inventory which optimize the performance of the system are determined simultaneously. Furthermore, the developed models and algorithms in this scenario, are utilized in order to study and optimize the performance of a healthcare system in which the length of stay of patients are generally distributed in different phases of health care process.
Thesis (Ph.D.)--Wichita State University, College of Engineering, Dept. of Industrial and Manufacturing Engineering
Includes bibliographic references (leaves 138-139)
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23

Mubeen, Saad. "Modeling and Timing Analysis of Industrial Component-Based Distributed Real-time Embedded Systems." Licentiate thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-13883.

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The model- and component-based development approach has emerged as an attractive option for the development of Distributed Real-time Embedded (DRE) systems. In this thesis we target several issues such as modeling of legacy communication, extraction of end-to-end timing models and support for holistic response-time analysis of industrial component-based DRE systems. We introduce a new approach for modeling legacy network communication in component-based DRE systems. By introducing special-purpose components to encapsulate and abstract the communication protocols in DRE systems, we allow the use of legacy nodes and legacy protocols in a component- and model-based software engineering environment. The proposed approach also supports the state-of-the-practice development of component-based DRE systems. The Controller Area Network (CAN) is one of the widely used real-time networks in DRE systems especially in automotive domain. We identify that the existing analysis of CAN does not support common message transmission patterns which are implemented by some high-level protocols used in the industry. Consequently, we extend the existing analysis to facilitate the worst-case response-time computation of these transmission patterns. The extended analysis is generally applicable to any high-level protocol for CAN that uses periodic, sporadic, or both periodic and sporadic transmission of messages. Because an end-to-end timing model should be available to perform the holistic response-time analysis, we present a method to extract the end-to-end timing models from component-based DRE systems. In order to show the applicability of our modeling techniques and extended analysis, we provide a proof of concept by extending the existing industrial component model (Rubus Component Model), implementing the holistic response-time analysis along with the extended analysis of CAN in the industrial tool suite (Rubus-ICE), and conducting an automotive case study.
EEMDEF
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Veelen, Martijn van. "Considerations on modeling for early detection of abnormalities in locally autonomous distributed systems." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 2007. http://irs.ub.rug.nl/ppn/30031776X.

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Foo, Brian. "Towards a systematic approach for modeling and optimizing distributed and dynamic multimedia systems." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1670312041&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.

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26

Assadi, Morteza Cheraghi Hossein S. "Modeling and optimization of closed-loop systems with generally distributed failure/service times /." A link to full text of this dissertation in SOAR, 2008. http://hdl.handle.net/10057/2068.

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Thesis (Ph.D.)--Wichita State University, College of Engineering, Dept. of Industrial and Manufacturing Engineering
"December 2008". Copyright 2008 by Morteza Assadi. All Rights Reserved. Includes bibliographic references (leaves 138-139).
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Cheriere, Nathanaël. "Towards Malleable Distributed Storage Systems˸ From Models to Practice." Thesis, Rennes, École normale supérieure, 2019. http://www.theses.fr/2019ENSR0018/document.

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Le Cloud, avec son modèle économique, offre la possibilité d’un gestion élastique des ressources; les utilisateurs peuvent louer des ressources selon leurs besoins. Cette élasticité permet de réduire les coûts énergétiques et financiers, et aide les applications à s’adapter aux charges de travail variables.Les applications manipulant de grandes quantités de données exécutées dans le Cloud ou sur des supercalculateurs sont souvent colocalisées avec un système de stockage distribué pour garantir un accès rapide aux données. Bien que de nombreux travaux aient été proposés pour redimensionner dynamiquement les capacités de calcul pour s’ajuster à la charge de travail, le stockage n’est pas considéré comme malléable (capable d’être redimensionné dynamiquement) puisque les transferts de grandes quantités de données nécessaires sont considérés trop lents. Cependant, le matériel et les techniques de stockage ont évolué et cette hypothèse doit être réévaluée.Dans cette thèse, nous présentons une étude sous différents angles des opérations de redimensionnement des systèmes de stockage distribués.Nous commençons par modéliser la durée minimale de ces opérations pour évaluer leur vitesse potentielle. Puis, nous développons un benchmark conçu pour mesurer la viabilité de la malléabilité d’un système de stockage sur une plateforme donnée. Finalement, nous implémentons un gestionnaire d’opérations de redimensionnement pour systèmes de stockage distribués qui décide et organise les transferts de données requis par ces opérations
The Cloud, with its pay-as-you-go model, gives the possibility of elastic resource management; users can claim and release resources as needed. This elasticity leads to financial and energetical cost reductions, and helps applications to cope with varying workloads.Distributed cloud and HPC applications processing large amounts of data are often co-located with a distributed storage system in order to ensure fast data accesses. Although many works have been proposed to dynamically rescale the processing part of such systems to match their workload, the storage is never considered as malleable (able to be dynamically rescaled) since moving massive amounts of data around is assumed to be too slow in practice. However, in recent years hardware and storage techniques have evolved and this assumption needs to be revisited.In this thesis, we present a study of the rescaling operations in distributed storage systems approached from different angles. We start by modeling the minimal duration of rescaling operations to estimate their potential speed. Then, we develop a benchmark to measure the viability of distributed storage system malleability on a given platform. Last, we implement a rescaling manager for distributed storage systems that decides and organizes the data transfers required during a rescaling operation
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Mahmoud, Abdallah Abdelrahman Hassan. "Cooperative Automated Vehicle Movement Optimization at Uncontrolled Intersections using Distributed Multi-Agent System Modeling." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/84896.

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Optimizing connected automated vehicle movements through roadway intersections is a challenging problem. Traditional traffic control strategies, such as traffic signals are not optimal, especially for heavy traffic. Alternatively, centralized automated vehicle control strategies are costly and not scalable given that the ability of a central controller to track and schedule the movement of hundreds of vehicles in real-time is highly questionable. In this research, a series of fully distributed heuristic algorithms are proposed where vehicles in the vicinity of an intersection continuously cooperate with each other to develop a schedule that allows them to safely proceed through the intersection while incurring minimum delays. An algorithm is proposed for the case of an isolated intersection then a number of algorithms are proposed for a network of intersections where neighboring intersections communicate directly or indirectly to help the distributed control at each intersection makes a better estimation of traffic in the whole network. An algorithm based on the Godunov scheme outperformed optimized signalized control. The simulated experiments show significant reductions in the average delay. The base algorithm is successfully added to the INTEGRATION micro-simulation model and the results demonstrate improvements in delay, fuel consumption, and emissions when compared to roundabout, signalized, and stop sign controlled intersections. The study also shows the capability of the proposed technique to favor emergency vehicles, producing significant increases in mobility with minimum delays to the other vehicles in the network.
Ph. D.
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Puranik, Sachin V. "Control of Fuel Cell Based Green Energy Systems for Distributed Generation Applications." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1253476960.

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Kounev, Samuel [Verfasser]. "Performance Engineering of Distributed Component-Based Systems : Benchmarking, Modeling and Performance Prediction / Samuel Kounev." Aachen : Shaker, 2005. http://d-nb.info/118658808X/34.

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31

Eyries, Pascal. "A dynamic distributed-parameter modeling approach for performance monitoring of oral drug delivery systems." Link to electronic thesis, 2003. http://www.wpi.edu/Pubs/ETD/Available/etd-0501103-161142.

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Thesis (M.S.)--Worcester Polytechnic Institute.
Keywords: mass balance approach; bioavailability; drug delivery; dynamic modeling; partial differential equations; sensitivity analysis; dynamic simulations. Includes bibliographical references (p. 62-67).
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Liu, Yi. "Grey-box Identification of Distributed Parameter Systems." Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-220.

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Mayer, Tobias Rene. "Achieving collaboration in distributed systems deployed over selfish peers." Phd thesis, INSA de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-00961233.

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Today's networks are often characterized by a free aggregation of independent nodes. Thus, the possibility increases that a selfish party operates a node, which may violate the collaborative protocol in order to increase a personal benefit. If such violations differ from the system goals they can even be considered as attack. Current fault-tolerance techniques may weaken the harmful impact to some degree but they cannot always prevent them. Furthermore, the several architectures differ in their fault-tolerance capabilities. This emphasizes the need for approaches able to achieve collaboration from selfish nodes in distributed systems. In this PhD thesis, we consider the problem of attaining a targeted level of collaboration in a distributed architecture deployed over rational selfish nodes. They have interest in deviating from the collaborative protocol to increase a personal benefit. In order to cover a broad spectrum of systems, we do not modify the collaborative protocol itself. Instead, we propose to add a monitoring logic to inspect the correctness of a node's behaviour. The designer of the monitoring system is faced with a complex and dynamic situation. He needs to consider aspects such as the specific circumstances (e.g. message traffic), the inspection effort or the node's individual preferences. Furthermore, he should consider that each agent could be aware of the other agents' preferences as well as selfishness and perform strategic choices consequently. This complex and interdependent setup corresponds to a class of Game Theory (GT) known as Inspection Games (IG). They model the general situation where an inspector verifies through inspections the correct behaviour of another party, called inspectee. However, inspections are costly and the inspector's resources are limited. Hence, a complete surveillance is not possible and an inspector will try to minimize the inspections. In this thesis, the initial IG model is enriched by the possibility that a violation is not detected during an inspection (false negatives). Applied to distributed systems, the IG is used to model the network participants' strategy choice. As outcome, it enables to calculate system parameters to attain the desired collaboration value. The approach is designed as generic framework. It can be therefore applied to any architecture considering any selfish goal and any reliability technique. For the sake of concreteness, we will discuss the IG approach by means of the illustrative case of a Publish/Subscribe architecture. The IG framework of this thesis secures the whole collaborative protocol by a monitoring approach. This represents a new way in terms of reliability mechanisms. The applicability is furthermore supported by the software library RCourse. Simplifying robustness evaluations of distributed systems, it is suitable for model verification and parameter calibration.
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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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Ho, Qirong. "Modeling Large Social Networks in Context." Research Showcase @ CMU, 2014. http://repository.cmu.edu/dissertations/543.

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Today’s social and internet networks contain millions or even billions of nodes, and copious amounts of side information (context) such as text, attribute, temporal, image and video data. A thorough analysis of a social network should consider both the graph and the associated side information, yet we also expect the algorithm to execute in a reasonable amount of time on even the largest networks. Towards the goal of rich analysis on societal-scale networks, this thesis provides (1) modeling and algorithmic techniques for incorporating network context into existing network analysis algorithms based on statistical models, and (2) strategies for network data representation, model design, algorithm design and distributed multi-machine programming that, together, ensure scalability to very large networks. The methods presented herein combine the flexibility of statistical models with key ideas and empirical observations from the data mining and social networks communities, and are supported by software libraries for cluster computing based on original distributed systems research. These efforts culminate in a novel mixed-membership triangle motif model that easily scales to large networks with over 100 million nodes on just a few cluster machines, and can be readily extended to accommodate network context using the other techniques presented in this thesis.
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Chang, Hung-Ching. "Measuring, modeling, and optimizing counterintuitive performance phenomena in power-scalable, parallel systems." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/51682.

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The demands of exascale computing systems and applications have pushed for a rapid, continual design paradigm coupled with increasing design complexities from the interaction between the application, the middleware, and the underlying system hardware, which forms a breeding ground for inefficiency. This work seeks to improve system efficiency by exposing the root causes of unexpected performance slowdowns (e.g., lower performance at higher processor speeds) that occur more frequently in power-scalable systems where raw processor speed varies. More precisely, we perform an exhaustive empirical study that conclusively shows that increasing processor speed often reduces performance and wastes energy. Our experimental work shows that the frequency of occurrence and magnitude of slowdowns grow with clock frequency and parallelism, indicating that such slowdowns will increasingly be observed with trends in processor and system design. Performance speedups at lower frequencies (or slowdowns at higher frequencies) have been anecdotally observed in the prevailing literature since 2004, but no research has explained nor exploited this phenomenon. This work conclusively demonstrates that performance slowdowns during processor speedup phases can exceed 47% in common I/O workloads. Our hypothesis challenges (and ultimately debunks) a fundamental assumption in computer systems: faster processor speeds result in the same or better performance. In this work, with the use of code and kernel instrumentation, exhaustive experiments, and deep insight into the inner workings of the Linux I/O subsystem, I overcome the aforementioned challenges of variance, complexity, and nondeterminism and identify the I/O resource contention as the root cause of the slowdowns during processor speedup. Specifically, such contention comes from the Linux kernel when the journaling block device (JBD) interacts with the ext3/4 file system that introduces file write delays and file synchronization delays. To fully explain how such I/O contention causes performance anomaly, I propose analytical models of resource contention among I/O threads to describe the root cause of the observed I/O slowdowns when processors speed up. To this end, I introduce LUC, a runtime system to limit the unintended consequences of power scaling and demonstrate the effectiveness of the LUC system for two critical parallel transaction-oriented workloads, including a mail server (varMail) and online transaction processing (oltp).
Ph. D.
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38

Zhang, Yu. "Small-Signal Modeling and Analysis of Parallel-Connected Power Converter Systems for Distributed Energy Resources." Scholarly Repository, 2011. http://scholarlyrepository.miami.edu/oa_dissertations/551.

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Alternative energy resources (such as photovoltaics, fuel cells, wind turbines, micro-turbines, and internal combustion engines) and energy storage systems (such as batteries, supercapacitors, and flywheels) are increasingly being connected to the utility grid, creating distributed energy resources which require the implementation of an effective distributed power management strategy. Parallel-connected power converters form a critical component in such a distributed energy resources system. This dissertation addresses small-signal modeling and analysis of parallel-connected power converter systems operating in distributed energy environments. This work focuses on DC-DC and DC-AC power converters. First, this work addresses the small-signal modeling and analysis of parallel-connected power converters in a battery/supercapacitor hybrid energy storage system. The small-signal model considers variations in the current of individual energy storage devices and the DC bus voltage as state variables, variations in the power converter duty cycles as control variables, and variations in the battery and the supercapacitor voltages and the load current as external disturbances. This dissertation proposes several different control strategies and studies the effects of variations in controller and filter parameters on system performance. Simulation studies were carried out using the Virtual Test Bed (VTB) platform under various load conditions to verify the proposed control strategies and their effect on the final states of the energy storage devices. Control strategies for single DC-AC three-phase power converters are also identified and investigated. These include a novel PV (active power and voltage) control with frequency droop control loop, PQ (active power and reactive power) control, voltage control, PQ control with frequency droop control, and PQ control with voltage and frequency droop control. Small-signal models of a three-phase power converter system with these control strategies were developed, and the impact of parameter variations on the stability of a PV controlled converter were studied. Moreover, a small-signal model of parallel-connected three-phase DC-AC power converters with individual DC power supplies and network is proposed. The simulations carried out in stand-alone and grid-connected modes verify the combined control strategies that were developed. In addition, a detailed small-signal mathematical model that can represent the zero-sequence current dynamics in parallel-connected three-phase DC-AC power converters that share a single DC power source is presented. The effects of a variety of factors on the zero-sequence current are investigated, and a control strategy to minimize the zero-sequence current is proposed. Time-domain simulation studies verify the results. Simulations of a parallel-connected DC-AC power converter system with nonlinear load were carried out. The active power filter implemented in this system provides sharing of harmonic load between each power converter, and reduces harmonic distortion at the nonlinear load by harmonic compensation.
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39

Shafer, Keith Edward. "Modeling, implementing, and tools for studying logical process- to-process channels in asynchronous distributed systems /." The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487760357820315.

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40

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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41

Drwal, Maciej. "Data mining in distributedcomputer systems." Thesis, Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-5709.

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42

Mayer, Tobias René. "Achieving collaboration in distributed systems deployed over selfish peers." Thesis, Lyon, INSA, 2013. http://www.theses.fr/2013ISAL0083/document.

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Les réseaux actuels sont souvent caractérisés par une intégration dynamique de nœuds étrangers. La possibilité qu’une entité dissidente égoïste exploite un nœud augmente alors, ce qui peut constituer une violation du protocole de collaboration en vue d’accroître un avantage personnel. Si de telles violations diffèrent des objectifs du système, elles peuvent même être considérées comme une attaque. Si des techniques de tolérance aux fautes existent pour affaiblir l’impact sur le système, celui-ci ne peut pas totalement se prémunir de ce type d’attaque. Cela justifie la nécessité d’une approche pour maintenir un degré de collaboration nœuds égoïstes dans les systèmes distribues. Dans cette thèse, nous considérons le problème d’atteindre un niveau ciblé de collaboration dans une architecture répartie intégrant des nœuds égoïstes, qui ont intérêt à violer le protocole de collaboration pour tirer parti du système. L’architecture et le protocole seront modifies le moins possible. Un mécanisme d’inspection de chaque nœud sera mis en place pour décider de la légitimité de ses interactions avec ses voisins. Le concepteur du système d’inspection est confronté avec une situation complexe. Il doit corréler plusieurs aspects tels que les circonstances particulières de l’environnement ou des préférences individuelles du nœud. En outre, il doit tenir compte du fait que les nœuds peuvent connaitre l’état de ses voisins et construire ses décisions en conséquence. La surveillance proposée dans cette thèse correspond à une classe de modèles de la théorie des jeux connus sous le nom « Inspection Game » (IG). Ils modélisent la situation générale où un « inspecteur » vérifie par des inspections du comportement correct d’une autre partie, appelée « inspectee ». Toutefois, les inspections sont coûteuses et les ressources de l’inspecteur sont limitées. Par conséquent, une surveillance complète n’est pas envisageable et un inspecteur tentera de minimiser les inspections. Dans cette thèse, le modèle initial IG est enrichi par la possibilité d’apparition de faux négatifs, c’est à dire la probabilité qu’une violation ne soit pas détectée lors d’une inspection. Appliqué sur des systèmes distribués, cette approche permet de modéliser les choix collaboratifs de chacun des acteurs (violer le protocole ou pas, inspecter ou pas). Comme résultat, le modèle IG retourne les paramètres du système pour atteindre le niveau de collaboration souhaité. L’approche est conçue comme un « framework ». Elle peut donc s’adapter à toutes les architectures et toutes les techniques de fiabilité. Cette approche IG sera présentée à l’aide d’un exemple concret d’architecture Publish/Subscribe. L’approche du jeu d’inspection de cette thèse pour objectif de sécuriser l’ensemble du protocole de collaboration. Ceci constitue un nouveau concept de mécanisme de fiabilité. [...]
Today’s networks are often characterized by a free aggregation of independent nodes. Thus, the possibility increases that a selfish party operates a node, which may violate the collaborative protocol in order to increase a personal benefit. If such violations differ from the system goals they can even be considered as attack. Current fault-tolerance techniques may weaken the harmful impact to some degree but they cannot always prevent them. Furthermore, the several architectures differ in their fault-tolerance capabilities. This emphasizes the need for approaches able to achieve collaboration from selfish nodes in distributed systems. In this PhD thesis, we consider the problem of attaining a targeted level of collaboration in a distributed architecture deployed over rational selfish nodes. They have interest in deviating from the collaborative protocol to increase a personal benefit. In order to cover a broad spectrum of systems, we do not modify the collaborative protocol itself. Instead, we propose to add a monitoring logic to inspect the correctness of a node’s behaviour. The designer of the monitoring system is faced with a complex and dynamic situation. He needs to consider aspects such as the specific circumstances (e.g. message traffic), the inspection effort or the node’s individual preferences. Furthermore, he should consider that each agent could be aware of the other agents’ preferences as well as selfishness and perform strategic choices consequently. This complex and interdependent setup corresponds to a class of Game Theory (GT) known as Inspection Games (IG). They model the general situation where an inspector verifies through inspections the correct behaviour of another party, called inspectee. However, inspections are costly and the inspector’s resources are limited. Hence, a complete surveillance is not possible and an inspector will try to minimize the inspections. In this thesis, the initial IG model is enriched by the possibility that a violation is not detected during an inspection (false negatives). Applied to distributed systems, the IG is used to model the network participants’ strategy choice. As outcome, it enables to calculate system parameters to attain the desired collaboration value. The approach is designed as generic framework. It can be therefore applied to any architecture considering any selfish goal and any reliability technique. For the sake of concreteness, we will discuss the IG approach by means of the illustrative case of a Publish/Subscribe architecture. The IG framework of this thesis secures the whole collaborative protocol by a monitoring approach. This represents a new way in terms of reliability mechanisms. The applicability is furthermore supported by the software library RCourse. Simplifying robustness evaluations of distributed systems, it is suitable for model verification and parameter calibration
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43

Peterson, Mikael. "CAESAR : A proposed method for evaluating security in component-based distributed information systems." Thesis, Linköping University, Department of Electrical Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2470.

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Background: The network-centric defense requires a method for securing vast dynamic distributed information systems. Currently, there are no efficient methods for establishing the level of IT security in vast dynamic distributed information systems.

Purpose: The target of this thesis was to design a method, capable of determining the level of IT security of vast dynamic component-based distributed information systems.

Method: The work was carried out by first defining concepts of IT security and distributed information systems and by reviewing basic measurement and modeling theory. Thereafter, previous evaluation methods aimed at determining the level of IT security of distributed information systems were reviewed. Last, by using the theoretic foundation and the ideas from reviewed efforts, a new evaluation method, aimed at determining the level of IT security of vast dynamic component-based distributed information systems, was developed.

Results: This thesis outlines a new method, CAESAR, capable of predicting the security level in parts of, or an entire, component-based distributed information system. The CAESAR method consists of a modeling technique and an evaluation algorithm. In addition, a Microsoft Windows compliant software, ROME, which allows the user to easily model and evaluate distributed systems using the CAESAR method, is made available.

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44

Tong, Shiqiong Miu Karen Nan. "Slack bus modeling for distributed generation and its impacts on distribution system analysis, operation and planning /." Philadelphia, Pa. : Drexel University, 2006. http://hdl.handle.net/1860/1229.

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45

Arafat, Md Nayeem. "Modeling and Control of Distributed Energy Systems during Transition Operation between Grid Connected and Standalone Modes." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1405888130.

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46

Weißbach, Martin, Philipp Chrszon, Thomas Springer, and Alexander Schill. "Decentrally Coordinated Execution of Adaptations in Distributed Self-Adaptive Software Systems." ACM, 2017. https://tud.qucosa.de/id/qucosa%3A75268.

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Software systems in domains like Smart Cities, the Internet of Things or autonomous cars are coined by a high degree of distribution across several independent computing devices and the requirement to be able to adjust themselves to varying situations in their operational environment. Self-adaptive software systems are a natural choice to implement such context-dependent software systems. A multitude of approaches already implement self-adaptive systems and some consider even distribution aspects.Yet, none of the existing solutions supports the coordination of adaptation operations spanning multiple independent nodes, which is necessary to ensure a consistent adaptation even in presence of network errors or node failures. In this paper, we tackle this challenge to execute adaptations in distributed self-adaptive software systems in a coordinated manner. We present a protocol that enables the self-adaptive software system to execute correlated adaptations on multiple nodes in a transactional manner ensuring an atomic and consistent transition of the distributed system from its source to the desired target configuration. The protocol is validated to be free of deadlocks for any given adaptation at any point in time using a model-checking approach. The performance of our approach is investigated in experiments that emulate the protocol's execution on real devices for different sizes of distributed applications and adaptation scenarios.
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47

Gupta, Piyush. "Importance of Detailed Modeling of Loads/PV Systems Connected to Secondary of Distribution Transformers." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/79820.

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Residential solar Photovoltaic (PV) installations are increasing at a very high pace in the United States. In 2017 there are approximately one million residential solar PV installations in the US. A significant share of these installations are downstream of distribution transformers and thus connected to the secondary. To precisely analyze voltage variations induced by PV systems into distribution systems, accurate models of load and PV systems connected to the secondary side of distribution transformers are required. In the work here we consider two secondary circuit modeling approaches, simple secondary and detailed secondary models. In simple secondary models all loads and all PV generators below a distribution transformer are modeled as an aggregate load and an aggregate PV generator. In the detailed secondary models all loads and PV systems below the distribution transformers are modeled individually and secondary conductors and service drops are also modeled. Using a cloud motion simulator, it is observed that employing the simple secondary models can lead to inaccurate and conservative results. Moreover, the locations with the greatest voltage changes are different in the two modeling approaches. This paper highlights the importance of utilizing detailed secondary models over simple secondary models in analyzing PV generation.
Master of Science
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48

Sharma, Pratibha. "Modeling, Optimization, and Characterization of High Concentration Photovoltaic Systems Using Multijunction Solar Cells." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35917.

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Recent advancements in the development of high-efficiency multijunction solar cells have led to a renewed interest in the design and implementation of high concentration photovoltaic systems. With the emergence of novel materials and design structures, understanding the operation of multijunction solar cells has become a challenging task. Modeling and simulation hence play an important role in the analysis of such devices. In this dissertation, techniques for accurate optoelectrical modeling of concentrating photovoltaic systems, based on multijunction solar cells, are proposed. A 2-dimensional, distributed circuit model is proposed, parametrized to values obtained by numerical modeling of three multijunction cell designs, namely: a three-junction, lattice matched design, a three-junction lattice-mismatched, inverted metamorphic design, and a four-junction,lattice matched design. Cell performance for all the three designs is evaluated under both uniform and nonuniform illumination profiles at high concentrations and efficiency enhancement by optimizing finger spacing is proposed. The effect of luminescent coupling from higher bandgap subcells is also determined.Fresnel-lens based, refractive concentrating optical systems are modeled and optimized using an optical ray-tracing simulator at two different concentrations, with and without a secondary optical element. The corresponding optical efficiency, acceptance angle, and the degree of nonuniformity are determined for each optical system. An integrated approach,combining optical design with electrical modeling is proposed for optimizing the multijunction solar cell in tandem with the corresponding concentrating optics. The approach is validated by on-sun, acceptance angle measurements, using a three-junction,lattice-matched cell. Also, temperature effects are modeled and are experimentally validated for a three-junction, lattice-matched design. Experimental results with a single-junction, dilute-nitride cell, targeted for four-junction operation, are presented as well. A modified distributed circuit model is used for analysis of temperature effects in a four-junction solar cell, and the results under both uniform and nonuniform temperature profiles are presented. When implemented, the designs and their corresponding analyses, may result in new insights into the development of CPV systems, thereby enabling enhanced efficiencies at higher concentrations.
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49

Ghafoor, Sheikh Khaled. "Modeling of an adaptive parallel system with malleable applications in a distributed computing environment." Diss., Mississippi State : Mississippi State University, 2007. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11092007-145420.

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50

Lacks, Daniel Jonathan. "MODELING, DESIGN AND EVALUATION OF NETWORKING SYSTEMS AND PROTOCOLS THROUGH SIMULATION." Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3792.

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Computer modeling and simulation is a practical way to design and test a system without actually having to build it. Simulation has many benefits which apply to many different domains: it reduces costs creating different prototypes for mechanical engineers, increases the safety of chemical engineers exposed to dangerous chemicals, speeds up the time to model physical reactions, and trains soldiers to prepare for battle. The motivation behind this work is to build a common software framework that can be used to create new networking simulators on top of an HLA-based federation for distributed simulation. The goals are to model and simulate networking architectures and protocols by developing a common underlying simulation infrastructure and to reduce the time a developer has to learn the semantics of message passing and time management to free more time for experimentation and data collection and reporting. This is accomplished by evolving the simulation engine through three different applications that model three different types of network protocols. Computer networking is a good candidate for simulation because of the Internet's rapid growth that has spawned off the need for new protocols and algorithms and the desire for a common infrastructure to model these protocols and algorithms. One simulation, the 3DInterconnect simulator, simulates data transmitting through a hardware k-array n-cube network interconnect. Performance results show that k-array n-cube topologies can sustain higher traffic load than the currently used interconnects. The second simulator, Cluster Leader Logic Algorithm Simulator, simulates an ad-hoc wireless routing protocol that uses a data distribution methodology based on the GPS-QHRA routing protocol. CLL algorithm can realize a maximum of 45% power savings and maximum 25% reduced queuing delay compared to GPS-QHRA. The third simulator simulates a grid resource discovery protocol for helping Virtual Organizations to find resource on a grid network to compute or store data on. Results show that worst-case 99.43% of the discovery messages are able to find a resource provider to use for computation. The simulation engine was then built to perform basic HLA operations. Results show successful HLA functions including creating, joining, and resigning from a federation, time management, and event publication and subscription.
Ph.D.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Computer Engineering PhD
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