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Tesi sul tema "Network model"
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1
Xiaodan, Xie. "Network Interdiction Model on Interdependent Incomplete Network". Ohio University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1593537784177702.
Testo completo
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Mao, Ai-sheng. "A Theoretical Network Model and the Incremental Hypercube-Based Networks". Thesis, University of North Texas, 1995. https://digital.library.unt.edu/ark:/67531/metadc277860/.
Testo completoAbstract (sommario):
The study of multicomputer interconnection networks is an important area of research in parallel processing. We introduce vertex-symmetric Hamming-group graphs as a model to design a wide variety of network topologies including the hypercube network.
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Kuehn, Daniel, e Sofia Ljunggren. "Refining a Network Model Concerning Network Security Risk Analysis". Thesis, KTH, Data- och elektroteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-154355.
Testo completoAbstract (sommario):
P²CySeMoL is a framework in which security risks are calculated and presented with a value referring to the probability that an attack will succeed in a system, mainly SCADA systems. This thesis covers the creation of a more granular network module for the P²CySeMoL security riskanalysis framework to better be able to represent a network in concrete modules and to enable security riskanalysis on a network infrastructure at a greater detail. This paper outlines the creation of a network module with the base in the OSI model. It is replicated in a way that the network module is an extension to the P²CySeMoL metamodel, without interfering and restructuring it. It also covers a smaller survey to verify and get feedback about the created module from security and network experts and analysis of the survey. The conclusion is made that the network module is a good base to build upon and reflects to good degree a model needed to do security risk analysis on a network infrastructure and suggestions about further validation and research to improve the module are outlined. This thesis was produced in cooperation with Spotify AB and parts of the team behind P²CySeMoL at the ICS department at KTH.P²CySeMoL är ett ramverk där säkerhetsrisker beräknas och redovisas i form av ett värde som hän-visar till sannolikheten att en attack lyckas i ett system, huvudsakligen SCADA system. Den här avhandlingen behandlar skapandet av en mer detaljerad nätverksmodul för säkerhetsriskramverket P²CySeMoL för att bättre representera ett nätverks konkreta moduler och för att möjliggöra analys av säkerhetsrisker rörande en nätverksinfrastruktur på ett mer detaljerat sätt. Den här rapporten beskriver skapandet av en nätverksmodul med en bas i OSI-modellen. Den är replikerad på ett sätt att den är en extension av P²CySeMoL metamodell, utan att omstrukturera den. Det omfattar även en mindre undersökning för att kontrollera och samla återkoppling på den skapade modulen från säkerhet- och nätverksexperter samt en analys av undersökningen. Slutsatsen fastställer att nätverksmodulen är en bra bas att bygga vidare på och den återspeglar till hög grad en modell som behövs för att göra säkerhetsriskanalyser på en infrastruktur, förslag om ytterligare validering och forskning för att förbättra modulnätet beskrivs. Det här arbetet har producerats i samarbete med Spotify och delar av teamet bakom P²CySeMoL vidICS avdelningen på KTH.
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Gammelgård, Magnus. "The network performance assessment model". Licentiate thesis, KTH, Electrical Systems, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1746.
Testo completoAbstract (sommario):
The electricity distribution in Sweden is experiencing aconsiderable change in conditions by the radical change inregulation policy. The Swedish Energy Agency(Energimyndigheten) is introducing a new regulatory model, theNetwork Performance Assessment Model, as the main tool forsupervising the natural monopolies of local electricitydistribution. The new model has interesting and far-reachingconsequences for the involved parties.
This thesis investigates the implications of the newregulation and the regulatory tool, in particularly related toIT-investments evaluations in the distribution utilities. Intodays utilities, IT-systems are often a vital part ofoperations, ranging from e.g. real-time monitoring andcontrolling of the network to various administrative tasks.Considerable amounts of money are spent on investments toenhance and maintain these IT-systems. The changed regulationand the new regulatory model put a focus, more than ever, onefficient use of utilitiesresources, implying a need forsuitable methods to evaluate ITinvestments.
In the thesis, the new regulation is described, inparticular the new regulatory model. The model is presented andcentral implications are identified, e.g. in terms of newrequirements put on the utilities and general businessconsequences. As stated, the focus is on implications relatedto IT-systems and investments in these systems.
Furthermore, a wide range of IT-investment evaluationmethods are presented and categorized in the thesis, focusingon IT-investment appraisal techniques. The categories rangesfrom methods only considering cash flows of investments to moreelaborate methods, e.g. for considering behavioral sciencesaspects. The thesis outlines and presents categories of methodsas well as examples of individual methods.
In the final part of the thesis, suitable IT-investmentevaluation methods, given the implications of the newregulation, are discussed. The implications include both directbusiness related aspects as well as more technical issuesrelated to the IT-investments. It is also concluded that asuitable method need to incorporate both monetary consequencesof the investment as well as a limited number of non-monetary,related to the regulatory model.
Key words:Regulation of electricity distribution,IT-investment evaluation methods, Implications of monopolyregulation
QC 20100608
5
Arulselvan, Ashwin. "Network model for disaster management". [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0024855.
Testo completo
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Lundy, G. M. "Systems of communicating machines : a model for communication protocols". Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/8210.
Testo completo
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Yao, Ye. "Ad Hoc Networks Measurement Model and Methods Based on Network Tomography". Phd thesis, Université de Technologie de Belfort-Montbeliard, 2011. http://tel.archives-ouvertes.fr/tel-00636282.
Testo completoAbstract (sommario):
The measurability of Mobile ad hoc network (MANET) is the precondition of itsmanagement, performance optimization and network resources re-allocations. However, MANET is an infrastructure-free, multi-hop, andself-organized temporary network, comprised of a group of mobile nodes with wirelesscommunication devices. Not only does its topology structure vary with time going by, butalso the communication protocol used in its network layer or data link layer is diverse andnon-standard.In order to solve the problem of interior links performance (such as packet loss rate anddelay) measurement in MANET, this thesis has adopted an external measurement basedon network tomography (NT). To the best of our knowledge, NT technique is adaptable for Ad Hoc networkmeasurement.This thesis has deeply studied MANET measurement technique based on NT. The maincontributions are:(1) An analysis technique on MANET topology dynamic characteristic based onmobility model was proposed. At first, an Ad Hoc network mobility model formalizationis described. Then a MANET topology snapshots capturing method was proposed to findand verify that MANET topology varies in steady and non-steady state in turnperiodically. At the same time, it was proved that it was practicable in theory to introduceNT technique into Ad Hoc network measurement. The fitness hypothesis verification wasadopted to obtain the rule of Ad Hoc network topology dynamic characteristic parameters,and the Markov stochastic process was adopted to analyze MANET topology dynamiccharacteristic. The simulation results show that the method above not only is valid andgenerable to be used for all mobility models in NS-2 Tool, but also could obtain thetopology state keeping experimental formula and topology state varying probabilityformula.IV(2) An analysis technique for MANET topology dynamic characteristic based onmeasurement sample was proposed. When the scenario file of mobile models could notbe obtained beforehand, End-to-End measurement was used in MANET to obtain thepath delay time. Then topology steady period of MANET is inferred by judging whetherpath delay dithering is close to zero. At the same time, the MANET topology wasidentified by using hierarchical clustering method based on measurement sample of pathperformance during topology steady period in order to support the link performanceinference. The simulation result verified that the method above could not only detect themeasurement window time of MANET effectively, but also identify the MANETtopology architecture during measurement window time correctly.(3) A MANET link performance inference algorithm based on linear analysis modelwas proposed. The relation of inequality between link and path performance, such as lossrate of MANET, was deduced according to a linear model. The phenomena thatcommunication characteristic of packets, such as delay and loss rate, is more similarwhen the sub-paths has longer shared links was proved in the document. When the rankof the routing matrix is equal to that of its augmentation matrix, the linear model wasused to describe the Ad Hoc network link performance inference method. The simulationresults show that the algorithm not only is effective, but also has short computing time.(4) A Link performance inference algorithm based on multi-objectives optimizationwas proposed. When the rank of the routing matrix is not equal to that of its augmentationmatrix, the link performance inference was changed into multi-objectives optimizationand genetic algorithm is used to infer link performance. The probability distribution oflink performance in certain time t was obtained by performing more measurements andstatistically analyzing the hypo-solutions. Through the simulation, it can be safelyconcluded that the internal link performance, such as, link loss ratio and link delay, can beinferred correctly when the rank of the routing matrix is not equal to that of itsaugmentation matrix.
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Al-Musawi, Ahmad Jr. "COMPLEX NETWORK GROWING MODEL USING DOWNLINK MOTIFS". VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/3088.
Testo completoAbstract (sommario):
Understanding the underlying architecture of gene regulatory networks (GRNs) has been one of the major goals in systems biology and bioinformatics as it can provide insights in disease dynamics and drug development. Such GRNs are characterized by their scale-free degree distributions and existence of network motifs, which are small subgraphs of specific types and appear more abundantly in GRNs than in other randomized networks. In fact, such motifs are considered to be the building blocks of GRNs (and other complex networks) and they help achieve the underlying robustness demonstrated by most biological networks. The goal of this thesis is to design biological network (specifically, GRN) growing models. As the motif distribution in networks grown using preferential attachment based algorithms do not match that of the GRNs seen in model organisms like E. coli and yeast, we hypothesize that such models at a single node level may not properly reproduce the observed degree and motif distributions of biological networks. Hence, we propose a new network growing algorithm wherein the central idea is to grow the network one motif (specifically, we consider one downlink motif) at a time. The accuracy of our proposed algorithm was evaluated extensively and show much better performance than existing network growing models both in terms of degree and motif distributions. We also propose a complex network growing game that can identify important strategies behind motif interactions by exploiting human (i.e., gamer) intelligence. Our proposed gaming software can also help in educational purposes specifically designed for complex network studies.
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Draai, Kevin. "A model for assessing and reporting network performance measurement in SANReN". Thesis, Nelson Mandela Metropolitan University, 2017. http://hdl.handle.net/10948/16131.
Testo completoAbstract (sommario):
The performance measurement of a service provider network is an important activity. It is required for the smooth operation of the network as well as for reporting and planning. SANReN is a service provider tasked with serving the research and education network of South Africa. It currently has no structure or process for determining network performance metrics to measure the performance of its network. The objective of this study is to determine, through a process or structure, which metrics are best suited to the SANReN environment. This study is conducted in 3 phases in order to discover and verify the solution to this problem. The phases are "Contextualisation", "Design",and "Verification". The "Contextualisation" phase includes the literature review. This provides the context for the problem area but also serves as a search function for the solution. This study adopts the design science research paradigm which requires the creation of an artefact. The "Design" phase involves the creation of the conceptual network performance measurement model. This is the artefact and a generalised model for determining the network performance metrics for an NREN. To prove the utility of the model it is implemented in the SANReN environment. This is done in the "Verification" phase. The network performance measurement model proposes a process to determine network performance metrics. This process includes getting NREN requirements and goals, defining the NRENs network design goals through these requirements, define network performance metrics from these goals, evaluating the NRENs monitoring capability, and measuring what is possible. This model provides a starting point for NRENs to determine network performance metrics tailored to its environment. This is done in the SANReN environment as a proof of concept. The utility of the model is shown through the implementation in the SANReN environment thus it can be said that it is generic.The tools that monitor the performance of the SANReN network are used to retrieve network performance data from. Through understanding the requirements, determining network design goals and performance metrics, and determining the gap the retrieving of results took place. These results are analysed and finally aggregated to provide information that feeds into SANReN reporting and planning processes. A template is provided to do the aggregation of metric results. This template provides the structure to enable metrics results aggregation but leaves the categories or labels for the reporting and planning sections blank. These categories are specific to each NREN. At this point SANReN has the aggregated information to use for planning and reporting. The model is verified and thus the study’s main research objective is satisfied.
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Jones, Thomas Carroll Jr. "JigCell Model Connector: Building Large Molecular Network Models from Components". Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78277.
Testo completoAbstract (sommario):
The ever-growing size and complexity of molecular network models makes them difficult to construct and understand. Modifying a model that consists of tens of reactions is no easy task. Attempting the same on a model containing hundreds of reactions can seem nearly impossible. We present the JigCell Model Connector, a software tool that supports large-scale molecular network modeling. Our approach to developing large models is to combine together smaller models, making the result easier to comprehend. At the base, the smaller models (called modules) are defined by small collections of reactions. Modules connect together to form larger modules through clearly defined interfaces, called ports. In this work, we enhance the port concept by defining different types of ports. Not all modules connect together the same way, therefore multiple connection options need to exist.Master of Science
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Ikhalia, Ehinome. "A malware threat avoidance model for online social network users". Thesis, Brunel University, 2017. http://bura.brunel.ac.uk/handle/2438/16039.
Testo completoAbstract (sommario):
The main purpose of this thesis is to develop a malware threat avoidance model for users of online social networks (OSNs). To understand the research domain, a comprehensive and systematic literature review was conducted and then the research scope was established. Two design science iterations were carried out to achieve the research aim reported in this thesis. In the first iteration, the research extended the Technology Threat Avoidance Theory (TTAT) to include a unique characteristic of OSN - Mass Interpersonal Persuasion (MIP). The extended model (TTAT-MIP), focused on investigating the factors that needs to be considered in a security awareness system to motivate OSN users to avoid malware threats. Using a quantitative approach, the results of the first iteration suggests perceived severity, perceived threat, safeguard effectiveness, safeguard cost, self-efficacy and mass interpersonal persuasion should be included in a security awareness system to motivate OSN users to avoid malware threats. The second iteration was conducted to further validate TTAT-MIP through a Facebook video animation security awareness system (referred in this thesis as Social Network Criminal (SNC)). SNC is a Web-based application integrated within Facebook to provide security awareness to OSN users. To evaluate TTAT-MIP through SNC, three research techniques were adopted: lab experiments, usability study and semi-structured interviews. The results suggest that participants perceived SNC as a useful tool for malware threat avoidance. In addition, SNC had a significant effect on the malware threat avoidance capabilities of the study participants. Moreover, the thematic analysis of the semi-structured interviews demonstrated that the study participants' found SNC to be highly informative; persuasive; interpersonally persuasive; easy to use; relatable; fun to use; engaging; and easy to understand. These findings were strongly related to the constructs of TTAT-MIP. The research contributes to theory by demonstrating a novel approach to design and deploy security awareness systems in a social context. This was achieved by including users' behavioural characteristic on the online platform where malware threats occur within a security awareness system. Besides, this research shows how practitioners keen on developing systems to improve security behaviours could adopt the TTAT-MIP model for other related contexts.
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Pitts, Robert A. "A simulation model of an Ethernet with network partitioning". Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276740.
Testo completoAbstract (sommario):
One of the local area network medium access control standards created by the Institute of Electrical and Electronic Engineers in IEEE Project 802 is the carrier sense multiple access with collision detection (CSMA/CD) medium access control. Numerous studies have been reported in the literature on the performance of CSMA/CD. These studies show that CSMA/CD performs well under light network load but not well at heavy load. To improve the performance of CSMA/CD under heavy load, a new concept called network partitioning is presented. Network partitioning allows the network to be partitioned into segments when under heavy load. Partition stations then act as bridges between the segments. The impact of network partitioning on network performance was tested using a simulation model of an Ethernet local area network (an implementation of the CSMA/CD medium access control). The simulation results show that network partitioning can improve the performance of CSMA/CD under heavy load.
13
Long, Weili. "On the topology design of hose-model VPN networks /". View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?ECED%202008%20LONG.
Testo completo
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Wongthatsanekorn, Wuthichai. "Strategic Network Growth with Recruitment Model". Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14636.
Testo completoAbstract (sommario):
In order to achieve stable and sustainable systems for recycling post-consumer goods, it is frequently necessary to concentrate the flows from many collection points to meet the volume requirements for the recycler. This motivates the importance of growing the collection network over time to both meet volume targets and keep costs to a minimum. This research addresses a complex and interconnected set of strategic and tactical decisions that guide the growth of reverse supply chain networks over time. This dissertation has two major components: a tactical recruitment model and a strategic investment model. These capture the two major decision levels for the system, the former for the regional collector who is responsible for recruiting material sources to the network, the latter for the processor who needs to allocate his scarce resources over time and to regions to enable the recruitment to be effective. The recruitment model is posed as a stochastic dynamic programming problem. An exact method and two heuristics are developed to solve this problem. A numerical study of the solution approaches is also performed. The second component involves a key set of decisions on how to allocate resources effectively to grow the network to meet long term collection targets and collection cost constraints. The recruitment problem appears as a sub-problem for the strategic model and this leads to a multi-time scale Markov decision problem. A heuristic approach which decomposes the strategic problem is proposed to solve realistically sized problems. The numerical valuations of the heuristic approach for small and realistically sized problems are then investigated.
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Tong, C. O. (Chung On) 1945. "A schedule-based transit network model". Monash University, Dept. of Civil Engineering, 1986. http://arrow.monash.edu.au/hdl/1959.1/7935.
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Yotter, Rachel A. "A network model of the hippocampus /". Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/5887.
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Velu, Chander K. "Business model innovations in network markets". Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439063.
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Chiang, Nhan Tu. "Mesh network model for urban area". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44698.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, System Design and Management Program, 2008.Includes bibliographical references (p. 52, 2-7 (2nd group)).
Decreasing population, high crime rate, and limited economic opportunities are all symptoms of urban decline. These characteristics are, unfortunately, evident in major cities and small towns. Local municipalities in these cities and towns with the aid of state and federal government have attempted to reverse urban decline through the traditional approach of urban renewal. Their idea was to create low cost housing to attract people back to urban areas. Their approach has shown mixed results with most attempts having no effect on the deterioration. The goal of this thesis is to propose a higher system approach to answer urban decline through the application of new technology, wireless mesh networks. A wireless mesh network can provide improved security, public safety, new economic opportunities, and a bridge that crosses the digital divide. Married to the appropriate applications, a wireless mesh network creates a business model that is both favorable and sustainable. More importantly, the business model brings about the human capital necessary for urban revitalization.
by Nhan Tu Chiang.
S.M.
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Loh, Kai-Chee. "A network model for perfusion chromatography". Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11375.
Testo completo
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Chang, Su Eun. "A bid-rent network equilibrium model". Thesis, University College London (University of London), 2004. http://discovery.ucl.ac.uk/1446893/.
Testo completoAbstract (sommario):
This thesis discusses the development of a new model for investigating the relationship between transport and the location of activities. The research consists of three stages. In the first phase, the structural features of the relationship, which are the characteristics of locations, the decision-making processes of households, and the interaction between transport and land-use, are identified. Existing approaches are reviewed using these three components. The review shows that no existing framework satisfactorily represents the requirements in modelling the relationship. Secondly, a bid-rent network equilibrium model is developed. The modelling is considered in terms of competition for locations. Difficulties in analysing the unique characteristics of locations, namely heterogeneity and indivisibility, are discussed. A hedonic interpretation is incorporated to overcome the difficulties. The model represents the decision-making processes of households using the framework of an n-player non-cooperative game. The Nash equilibrium for this game is defined. The game is accompanied by the systematic interactions between transport and land-use. A mutual adjustment process addresses these interactions. A bi-level mathematical programme is suggested to embody the three components. The resulting formulation is interpreted as an oligopolistic Cournot game, which is an approximation of the n-player non- cooperative game. The functional relationship between the decision variables of the upper and lower levels in the bi-level model produces endogenously-determined transport impedance and locational attractiveness. The model incorporates a multiclass framework to consider interclass interactions, which establishes a multiclass bid-rent network equilibrium model. A heuristic algorithm is provided for the solution-finding technique of the bid-rent network equilibrium model. The algorithm combines a path-based routine for calculating the equilibrium solution to the lower level with the Newton-Raphson procedure for estimating the parameters of the hedonic-based stochastic bid-rent function in the upper level. The operation of the algorithm is examined using simple numerical examples. The final stage is an application of the bid-rent network equilibrium model to a real network. A medium sized city is chosen for the case study. The objective of the third stage is to demonstrate the ability of the model to investigate the relationship between transport and the location of activities. A base run and two policy runs are simulated. The base run means a simulation conducted using surveyed data. The policy runs represents the introduction of a congestion charge and the release of land for housing development. Class specific spatial behaviour is obtained. The behaviour is demonstrated using network performance indices representing transport impedance and locational attractiveness. Some policy implications of the simulation are presented.
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Rice, O. "A network model of financial markets". Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1464036/.
Testo completoAbstract (sommario):
This thesis introduces a network representation of equity markets. The model is based on the premise that assets share dependencies on abstract ‘factors’ resulting in exploitable patterns among asset price levels. The network model is a collection of long-run market trends estimated by a 3 layer machine learning framework. The network model’s comprehensive validity is established with 2 simulations in the fields of algorithmic trading, and systemic risk. The algorithmic trading validation applies expectations derived from the network model to estimating expected future returns. It further utilizes the network’s expectations to actively manage a theoretically market neutral portfolio. The validation demonstrates that the network model’s portfolio generates excess returns relative to 2 benchmarks. Over the time period of April, 2007 to January, 2014 the network model’s portfolio for assets drawn from the S&P/ASX 100 produced a Sharpe ratio of 0.674. This approximately doubles the nearest benchmark. The systemic risk validation utilized the network model to simulate shocks to select market sectors and evaluate the resulting financial contagion. The validation successfully differentiated sectors by systemic connectivity levels and suggested some interesting market features. Most notable was the identification of the ‘Financials’ sector as most systemically influential and ‘Basic Materials’ as the most systemically dependent. Additionally, there was evidence that ‘Financials’ may function as a hub of systemic risk which exacerbates losses from multiple market sectors.
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Ozkok, Ozlem. "A realistic model of network survivability". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03sep%5FOzkok.pdf.
Testo completoAbstract (sommario):
Thesis (M.S. in Information Technology Management and M.S. in Computer Science)--Naval Postgraduate School, September 2003.Thesis advisor(s): Geoffrey Xie, Alex Bordetsky. Includes bibliographical references (p. 47-48). Also available online.
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Van, der Merwe Zuann Stephanus. "A network traffic model for wireless mesh networks / Z.S. van der Merwe". Thesis, North-West University, 2013. http://hdl.handle.net/10394/9229.
Testo completoAbstract (sommario):
Design and management decisions require an accurate prediction of the performance of the network. Network performance estimation techniques require accurate network traffic models. In this thesis we are concerned with the modelling of network traffic for the wireless mesh network (WMN) environment. Queueing theory has been used in the past to model the WMN environment and we found in this study that queueing theory was used in two main methods to model WMNs. The first method is to consider each node in the network in terms of the number of hops it is away from the gateway.
Each node is then considered as a queueing station and the parameters for the station is derived from the number of hops each node is away from the gateway. These topologies can be very limiting in terms of the number of physical topologies they can model due to the fact that their parameters are only dependent on the number of hop-counts each node is away from the gateway. The second method is to consider a fixed topology with no gateways. This method simplifies analysis but once again is very limiting.
In this dissertation we propose a queueing based network traffic model that uses a connection matrix to define the topology of the network. We then derive the parameters for our model from the connection matrix. The connection matrix allows us to model a wider variety of topologies without modifying our model. We verify our model by comparing results from our model to results from a discrete event simulator and we validate our model by comparing results from our model to results from models previously proposed by other authors. By comparing results from our model to results of other models we show that our model is indeed capable of modelling a wider variety of topologies.Thesis (MIng (Computer and Electronic Engineering))--North-West University, Potchefstroom Campus, 2013.
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Wing, Peter D. "Enhancements to the XNS authentication-by-proxy model /". Online version of thesis, 1990. http://hdl.handle.net/1850/10613.
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Argyropoulos, Dimitris S. "Synthesis and degradation of model network polymers". Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=72032.
Testo completoAbstract (sommario):
Theoretical expressions essentially based on the Flory-Stockmayer statistics of gelation were experimentally examined for their applicability beyond the gel point. By studying the crosslinking process of a polyester network formed from 1,3,5-benzenetriacetic acid and 1,10-decamethylene glycol beyond the gel point, the validity of the expressions was quantitatively confirmed, and their limitations were delineated.On stepwise degradation of a similar network, increasingly large soluble fractions were obtained at each step, and their weight-average molecular weights increased as the degelation point was approached. The molecular weights and distributions of these fractions were in close quantitative agreement with theory, i.e., they represented a near-mirror image of the molecular weights of sol fractions obtained on crosslinking beyond the gel point. Similar results were obtained by degrading a network prepared by the random crosslinking of monodisperse primary chains of polystyrene.
Experimental support was thus obtained for treating random network degradation by reversing the statistics of the Flory-Stockmayer theory of gelation.
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Brooks, Clarence A. "Network model of a concentrator solar cell". Virtual Press, 1989. http://liblink.bsu.edu/uhtbin/catkey/562781.
Testo completoAbstract (sommario):
Solar concentrating systems are often used to decrease the cost of solar energy by redirecting the incident sunlight from a relatively large area onto a photovoltaic cell of smaller area. In addition to the convergence characteristics of the concentrator, indices of refraction and reflectivities which are functions of wavelength can result in an illumination which varies both spatially and spectrally on the solar cell. Nonuniformity can also be induced by concentrator tracking error. The effects of such nonuniform illumination on solar cell performance are of interest.In this investigation, a model of a concentrator solar cell consisting of a network of preexisting one-dimensional models has been developed. This model is analyzed for three sample grid configurations for both spot-focusing and line-focusing concentrator applications.Ada computer programs have been created which, together with a few other pieces of readily available software, are capable of simulating the model. Sample simulations have been performed for line-focusing concentrator applications. These results are presented and discussed.Department of Physics and Astronomy
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FARINAS, MAYTE SUAREZ. "THE LINEAR LOCAL-GLOBAL NEURAL NETWORK MODEL". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2003. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=3694@1.
Testo completoAbstract (sommario):
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICONesta tese apresenta-se o Modelo de Redes Neurais Globais- Locais (RNGL) dentro do contexto de modelos de séries temporais. Esta formulação abrange alguns modelos não- lineares já existentes e admite também o enfoque de Mistura de Especialistas. Dedica-se especial atenção ao caso de especialistas lineares, e são discutidos extensivamente aspectos teóricos do modelo: condições de estacionariedade, identificabilidade do modelo, existência, consistência e normalidade assintótica dos estimadores dos parâmetros. Considera-se também uma estratégia de construção do modelo e são discutidos os procedimentos numéricos de estimação, apresentando uma solução para o cálculo de valores iniciais. Finalmente, ilustra-se a metodologia apresentada em duas séries temporais reais, amplamente utilizada na literatura de modelos não lineares.
In this thesis, the Local Global Neural Networks model is proposed within the context of time series models. This formulation encompasses some already existing nonlinear models and also admits the Mixture of Experts approach. We place emphasis on the linear expert case and extensively discuss the theoretical aspects of the model: stationary conditions, existence, consistency and asymptotic normality of the parameter estimates, and model identifiability. A model building strategy is also considered and the whole procedure is illustrated with two real time-series.
28
Gonzalez, Pinto Jose Maria 1975. "A knowledge-network model of scientific communities". Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/8517.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2002.Includes bibliographical references (p. 68-69).
The amount of information organizations possess now days is overwhelming and the need of being capable of extracting valuable knowledge from such large amount of information is imperative. This thesis presents a software tool capable of extracting valuable knowledge (e.g. expertise) of a scientific community, generating relationships among community members automatically and revealing these relationships through a visualization tool. The types of relationships that this tool reveals are of the form of "who knows what" and "who can collaborate with whom" (both based on areas of expertise). The work presented was conducted and evaluated within the context of research institutions.
by Jose Maria Gonzalez Pinto.
S.M.
29
Krohn, J. P. "A gene regulatory network model for control". Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1416287/.
Testo completoAbstract (sommario):
The activity of a biological cell is regulated by interactions between genes and proteins. In artificial intelligence, this has led to the creation of developmental gene regulatory network (GRN) models which aim to exploit these mechanisms to algorithmically build complex designs. The emerging field of GRNs for control aims to instead exploit these natural mechanisms and this ability to encode a large variety of behaviours within a single evolvable genetic program for the solution of control problems. This work aims to extend the application domain of GRN models to previously unsolved control problems; the focus will here be on reinforcement learning problems, in which the dynamics of the system controlled are kept from the controller and only sparse feedback is given to it. This category of problems closely matches the challenges faced by natural evolution in generating biological GRNs. Starting with an existing GRN model, the fractal GRN (FGRN) model, a successful application to a standard control problem will be presented, followed by multiple improvements to the FGRN model and its associated genetic algorithm, resulting in better performances in terms of both reliability and speed. Limitations will be identified in the FGRN model, leading to the introduction of the Input-Merge- Regulate-Output (IMRO) architecture for GRN models, an implementation of which will show both quantitative and qualitative improvements over the FGRN model, solving harder control problems. The resulting model also displays useful features which should facilitate further extension and real-world use of the system.
30
Winqvist, Rebecka. "Neural Network Approaches for Model Predictive Control". Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-284323.
Testo completoAbstract (sommario):
Model Predictive Control (MPC) is an optimization-based paradigm forfeedback control. The MPC relies on a dynamical model to make predictionsfor the future values of the controlled variables of the system. It then solvesa constrained optimization problem to calculate the optimal control actionthat minimizes the difference between the predicted values and the desiredor set values. One of the main limitations of the traditional MPC lies in thehigh computational cost resulting from solving the associated optimizationproblem online. Various offline strategies have been proposed to overcomethis, ranging from the explicit MPC (eMPC) to the recent learning-basedneural network approaches. This thesis investigates a framework for thetraining and evaluation of a neural network for learning to implement theMPC. As a part of the framework, a new approach for efficient generationof training data is proposed. Four different neural network structures arestudied; one of them is a black box network while the other three employMPC specific information. The networks are evaluated in terms of twodifferent performance metrics through experiments conducted on realistictwo-dimensional and four-dimensional systems. The experiments revealthat while using MPC specific structure in the neural networks resultsin performance gains when the training data is limited, all the networkstructures perform similarly as extensive training data is used. They furthershow that a recurrent neural network structure trained on both the state andcontrol trajectories of a family of MPCs is able to generalize to previouslyunseen MPC problems. The proposed methods in this thesis act as a firststep towards developing a coherent framework for characterization of learningapproaches in terms of both model validation and efficient training datageneration.Modell-prediktiv reglering (MPC) är en strategi inom återkopplad regleringmed rötter i optimeringsteori. MPC:n använder sig av en dynamiskmodell för att prediktera de framtida värdena på systemets styrvariabler.Den löser sedan ett optimeringsproblem för att beräkna en optimalstyrsignal som minimerar skillnaden mellan referensvärdena och depredikterade värdena. Att lösa det associerade optimeringsproblemetonline kan medföra höga beräkningskostnader, något som utgör en av dehuvudsakliga begränsningarna med traditionell MPC. Olika offline-strategierhar föreslagits för att kringgå detta, däribland explicit modell-prediktivreglering (eMPC) samt senare inlärningsmetoder baserade på neuronnät.Den här masteruppsatsen undersöker ett ramverk för träning och utvärderingav olika neuronnätsstrukturer för MPC-inlärning. En ny metod för effektivgenerering av träningsdata presenteras som en del av detta ramverk.Fyra olika nätstrukturer studeras; ett black box-nät samt tre nät sominkluderar MPC-specifik information. Näten evalueras i termer av två olikaprestandamått genom experiment på realistiska två- och fyrdimensionellasystem. Experimenten visar att en MPC-specifik nätstruktur resulterar iökad prestanda när mängden träningsdata är begränsad, men att de fyranäten presterar likvärdigt när mycket träningsdata finns att tillgå. De visarvidare att ett återkopplat neuronnät som tränas på både tillstånds- ochstyrsignalstrajektorier från en familj av MPC:er har förmågan att generaliseravid påträffandet av nya MPC-problem. De föreslagna metoderna i den häruppsatsen utgör ett första steg mot utvecklandet av ett enhetligt ramverk förkaraktärisering av inlärningsmetoder i termer av både modellvalidering ocheffektiv datagenerering.
31
Yellapragada, Ramani. "Probabilistic Model for Detecting Network Traffic Anomalies". Ohio University / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1088538020.
Testo completo
32
Surasani, Vikranth Kumar. "A non-isothermal pore network drying model". Magdeburg Docupoint-Verl, 2008. http://d-nb.info/992455790/04.
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33
Walker, David Lennox. "Towards a Model of Large Network Cooperation". Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/25784.
Testo completoAbstract (sommario):
An insurgency is a clandestine movement seeking to overthrow a government using a combination of violence, intimidation, and peaceful means. Defeating an insurgency requires re-shaping the civilian social networks within which the insurgency is operating. Over the last 70 years, attempts by militaries and other government agencies to do this have often been counterproductive, destroying trust and generated conflict. Infrastructure projects have been used to provide a context for network development and shaping activities, but they carry a high risk of corruption and fraud.
This research develops a model of large network cooperation (LNC) that partially explains why some contemporary counterinsurgency tactics and strategies fail. It is proposed large network cooperation emerges when a Central Organisation offers a Membership Contract that is a simple, valuable, and offered indiscriminately to all Potential Members.
Additionally, the Central Organisation should have strong ties to its potential competitors and implementation of Membership Contracts should be facilitated by Decentralised Decision Makers, who should not negotiate or change the contract. The architecture and membership of the network should evolve through many short iterations and the network must be subject to constant testing.
The model is validated using qualitative case study research. Evidence suggests that the Provincial Reconstruction Teams – the primary tactical units employed by the International Security Assistance Force in Afghanistan – have been relatively unsuccessful because several of the program’s fundamental assumptions undermine LNC. Conversely, evidence suggests that the National Solidarity Program – a government infrastructure program in Afghanistan – is relatively successful because it more closely resembles the proposed model.
The research contributes to the fields of Defence and National Security, Social Network Analysis, Economics, and Organisational Science.
34
Brown, Douglas Graeme. "Formal network behaviour analysis using model checking". Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/93693/1/Douglas_Brown_Thesis.pdf.
Testo completoAbstract (sommario):
In this research we modelled computer network devices to ensure their communication behaviours meet various network standards. By modelling devices as finite-state machines and examining their properties in a range of configurations, we discovered a flaw in a common network protocol and produced a technique to improve organisations' network security against data theft.
35
Weng, Huibin. "A Social Interaction Model with Endogenous Network Formation". University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin159317152899108.
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36
Chen, Yao-Hsuan. "Network modeling of sexually transmitted diseases". Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51883.
Testo completoAbstract (sommario):
We create a dynamic network model to replicate more closely the population network structures of interest. Network, Norms and HIV/STI Risk Among Youth (NNAHRAY) is a community relationship survey data set, which provides a rare sample of a human risky-behavior contact network. Combining disease compartmental models with our dynamic network model, we simulate the spread of Human Immunodeficiency Virus (HIV) and Herpes Simplex Type 2 Virus (HSV2) with consideration of HSV2's synergistic impact on HIV's transmission. Our model reproduces HIV prevalence, HSV-2 prevalence, and the contact network close to those observed in NNAHRAY, with HIV annual prevalence closer to the estimated values from the literature than those of any disease spread model based on static networks. The success of fitting our model to the target data shows the importance of considering the data sampling process, contact dynamics, and contact network structures. Our model, under certain conditions, has prevalence prediction results that are insensitive to changes in network size. The analysis of various prevention/intervention strategies targeting different risky groups gives important insights into strategy prioritization and illustrates how our model can be used to assist in making public health policy decisions in practice, both for individual diseases and in the more-recent area of study that considers synergy between two diseases.
37
Viduto, Valentina. "A risk assessment and optimisation model for minimising network security risk and cost". Thesis, University of Bedfordshire, 2012. http://hdl.handle.net/10547/270440.
Testo completoAbstract (sommario):
Network security risk analysis has received great attention within the scientific community, due to the current proliferation of network attacks and threats. Although, considerable effort has been placed on improving security best practices, insufficient effort has been expanded on seeking to understand the relationship between risk-related variables and objectives related to cost-effective network security decisions. This thesis seeks to improve the body of knowledge focusing on the trade-offs between financial costs and risk while analysing the impact an identified vulnerability may have on confidentiality, integrity and availability (CIA). Both security best practices and risk assessment methodologies have been extensively investigated to give a clear picture of the main limitations in the area of risk analysis. The work begins by analysing information visualisation techniques, which are used to build attack scenarios and identify additional threats and vulnerabilities. Special attention is paid to attack graphs, which have been used as a base to design a novel visualisation technique, referred to as an Onion Skin Layered Technique (OSLT), used to improve system knowledge as well as for threat identification. By analysing a list of threats and vulnerabilities during the first risk assessment stages, the work focuses on the development of a novel Risk Assessment and Optimisation Model (RAOM), which expands the knowledge of risk analysis by formulating a multi-objective optimisation problem, where objectives such as cost and risk are to be minimised. The optimisation routine is developed so as to accommodate conflicting objectives and to provide the human decision maker with an optimum solution set. The aim is to minimise the cost of security countermeasures without increasing the risk of a vulnerability being exploited by a threat and resulting in some impact on CIA. Due to the multi-objective nature of the problem a performance comparison between multi-objective Tabu Search (MOTS) Methods, Exhaustive Search and a multi-objective Genetic Algorithm (MOGA) has been also carried out. Finally, extensive experimentation has been carried out with both artificial and real world problem data (taken from the case study) to show that the method is capable of delivering solutions for real world problem data sets.
38
Stanczyk, Jacek P. "Distributed programming model for networks". Thesis, University of Salford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308381.
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Junuthula, Ruthwik Reddy. "Modeling, Evaluation and Analysis of Dynamic Networks for Social Network Analysis". University of Toledo / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1544819215833249.
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Martorello, Cristiane Dias de Souza. "Epidemiology in complex networks - modified heterogeneous mean-field model". Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/100/100132/tde-16012019-173906/.
Testo completoAbstract (sommario):
The study of complex networks presented a huge development in last decades. In this dissertation we want to analyze the epidemic spread in scale-free networks through the Susceptible - Infected - Susceptible (SIS) model. We review the fundamental concepts to describe complex networks and the classical epidemiological models. We implement an algorithm that produces a scale-free network and explore the Quenched Mean-Field (QMF) dynamics in a scale-free network. Moreover, we simulate a change on the topology of the network according to the states of the nodes, and it generates a positive epidemic threshold. We show analytically that the fraction of infected vertices follows a power-law distribution in the vicinity of this critical pointO estudo de redes complexas tem se desenvolvido muito nos últimos anos. Nesta dissertação queremos analisar o processo de propagação de epidemia em redes livres de escala através do modelo Suscetível - Infectado - Suscetível (SIS). Apresentamos uma revisão de redes e as principais características dos modelos epidemiológicos clássicos. Implementamos um algoritmo que produz uma rede livre de escala dado um expoente e exploramos a dinâmica do modelo Quenched Mean-Field (QMF) inserido em uma rede livre de escala. Além disso, foi simulada uma possível alteração na topologia da rede, devido aos estados dos vértices infectados, que gerou um limiar epidêmico positivo no modelo e a probabilidade de vértices infectados seguiu uma lei de potência na vizinhança desse ponto crítico
41
Mahajan, Harshad S. "Filtering engine model for VIMNet". Toledo, Ohio : University of Toledo, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1271388865.
Testo completoAbstract (sommario):
Thesis (M.S.)--University of Toledo, 2010.Typescript. "Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Science Degree in Engineering." "A thesis entitled"--at head of title. Title from title page of PDF document. Bibliography: p. 77-78.
42
Khanal, Sandarva. "Aeronautical Channel Modeling for Packet Network Simulators". International Foundation for Telemetering, 2011. http://hdl.handle.net/10150/595747.
Testo completoAbstract (sommario):
ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, NevadaThe introduction of network elements into telemetry systems brings a level of complexity that makes performance analysis difficult, if not impossible. Packet simulation is a well understood tool that enables performance prediction for network designs or for operational forecasting. Packet simulators must however be customized to incorporate aeronautical radio channels and other effects unique to the telemetry application. This paper presents a method for developing a Markov Model simulation for aeronautical channels for use in packet network simulators such as OPNET modeler. It shows how the Hidden Markov Model (HMM) and the Markov Model (MM) can be used together to first extract the channel behavior of an OFDM transmission for an aeronautical channel, and then effortlessly replicate the statistical behavior during simulations in OPENT Modeler. Results demonstrate how a simple Markov Model can capture the behavior of very complex combinations of channel and modulation conditions.
43
Waterbury, L. A. "A mathematical model of biological signaling networks and network characteristics correlated with signaling behavior". Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1446094.
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Skagerlind, Mikael. "Developing a methodology model and writing a documentation template for network analysis". Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-32393.
Testo completoAbstract (sommario):
This report focuses on finding best practices and a better methodology when performing computer network analysis and troubleshooting. When network analysis is performed, computer network data packets are captured using data capturing software. The data packets can then be analysed through a user interface to reveal potential faults in the network. Network troubleshooting is focusing more on methodology when finding a fault in a network. The thesis work was performed at Cygate where they have recently identified needs for an updated network analysis methodology and a documentation template when documenting the network analysis results. Thus, the goal of this thesis has been to develop an elaborated methodology and discover best practices for network analysis and to write a documentation template for documenting network analysis work. As a part of discovering best practices and a methodology for network analysis, two laboratory tests were performed to gather results and analyse them. To avoid getting too many results but to still keep the tests within the scope of this thesis, the laboratory tests were limited to four network analysis tools and two test cases that are explained below. In the first laboratory test during three different test sequences, voice traffic (used in IP-phones and Skype etc.) is sent in the network using a computer program. In two of the test sequences other traffic is also congesting the network to disturb the sensitive voice traffic. The program used to send the voice traffic then outputs values; packet delay, jitter (variation in delay) and packet loss. Looking at these values, one can decide if the network is fit for carrying the sensitive voice traffic. In two of the test cases, satisfying results were gathered, but in one of them the results were very bad due to high packet loss. The second laboratory test focused more on methodology than gathering and analysing results. The goal of the laboratory test was to find and prove what was wrong with a slow network, which is a common fault in today’s networks due to several reasons. In this case, the network was slow due to large amounts of malicious traffic congesting the network; this was proven using different commands in the network devices and using different network analysis tools to find out what type of traffic was flowing in the network. The documentation template that was written as part of this thesis contains appealing visuals and explains some integral parts for presenting results when network analysis has been performed. The goal of the documentation template was an easy-to-use template that could be filled in with the necessary text under each section to simplify the documentation writing. The template contains five sections (headlines) that contain an explanation under it with what information is useful to have under that section. Cygate’s network consultants will use the documentation template when they are performing network analysis. For future work, the laboratory test cases could be expanded to include Quality of Service (QoS) as well. QoS is a widely deployed technology used in networks to prioritise different types of traffic. It could be used in the test cases to prioritise the voice traffic, in which case the results would be completely different and more favourable.
45
Ma, Yong. "A network model for heterogeneous sensor networks /". 2004. http://wwwlib.umi.com/dissertations/fullcit/3131409.
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Liu, JangJeng, e 劉正章. "Model for Evaluating Netwotks under Interface Effect-base onNETCOR Network Model". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/29383103117498696144.
Testo completoAbstract (sommario):
碩士國立交通大學
土木工程系
89
Interface is a common uncertainty factor in construction region. An idea of that interface management is related completing construction is generally accepted and respected by constructors. But existing technology of schedule and tools, for example, bar char, CPM, PERT, Monte-Carlo simulation, all base on take account of time of single activity. And by the way constructor calculate the finish time of project. So thinking of uncertain factor is also set measure to single activity. However the same uncertainty in different activities may have correlation that is always neglected. A constructor who has copious experience should envelop a mass of uncertainty factors when he evaluates time of one activity. But he must not differentiate between all uncertain factors; even more consider the time change reduces by the same uncertainty in before and after activities. However the networks model of NETCOR already provides a good base of research to understand each influence of uncertain factor in the activity. Further it also mentions the correlation of uncertainty. This dissertation is base on the networks model of NETCOR and consults the arrangement of interface by the CIAR system to establish a model for evaluating networks under interface effect. The model can express each interface effect in all activities and the relevance of both activities’ interface effect. For this reason, we can further understand the interface effect to time in schedule networks and catch the information for interface management. In the end of dissertation ,we use three examples（two activity, three activity and a small network） to explain how to use and what we can get from the model. Key words：Interface、Uncertainty、NETCOR、CIAR
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Tsai, Po-Feng, e 蔡柏灃. "Model predictive control with artificial neural network models". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/83061253206770147339.
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Sappidi, Rajasekhar Reddy. "In-network computation in sensor networks". Thesis, 2012. http://hdl.handle.net/10012/7142.
Testo completoAbstract (sommario):
Sensor networks are an important emerging class of networks that have many
applications. A sink in these networks acts as a bridge between the sensor nodes
and the end-user (which may be automated and/or part of the sink). Typically,
convergecast is performed in which all the data collected by the sensors is
relayed to the sink, which in turn presents the relevant information to the
end-user. Interestingly, some applications require the sink to relay just a
function of the data collected by the sensors. For instance, in a fire alarm
system, the sinks needs to monitor the maximum of the temperature readings of
all the sensors. For these applications, instead of performing convergecast, we
can let the intermediate nodes process the data they receive, to significantly
reduce the volume of traffic transmitted and increase the rate at which
the data is collected and processed at the sink: this is known as in-network
computation.
Most of the current literature on this novel technique focuses on asymptotic
results for large networks and for very elementary functions. In this
dissertation, we study a new class of functions for which we want to compute
explicit solutions for networks of practical size.
We consider the applications where the sink is interested in the first
M statistical moments of the data collected at a certain time.
The k-th statistical moment is
defined as the expectation of the k-th power of the data. The M=1 case represents the
elementary functions like MAX, MIN, MEAN, etc. that are commonly considered in
the literature. For this class of functions, we are interested in explicitly
computing the maximum achievable throughput including routing, scheduling and
queue management for any given network when in-network computation is allowed.
Flow models have been routinely used to solve optimal joint routing and scheduling
problems when there is no in-network computation and they are typically
tractable for relatively large networks. However, deriving such models is not
obvious when in-network computation is allowed. Considering a single rate wireless network
and the physical model of interference, we develop a discrete-time model for
the real-time network operation and perform two transformations to obtain a flow
model that keeps the essence of in-network computation. This model gives an
upper bound on the maximum achievable throughput. To show the tightness of that
upper bound, we derive a numerical lower bound by computing a feasible solution
to the discrete-time model. This lower bound turns out to be
close to the upper bound proving that the flow model is an excellent
approximation to the discrete-time model.
We then adapt the flow model to a
wired multi-rate network with asynchronous transmissions on links with different
capacities. To compute the lower bound for wired networks, we propose a
heuristic strategy involving the generation of multiple trees and effective
queue management that achieves a throughput close to the one computed by the
flow model. This cross validates the tightness of the upper bound and the
goodness of our heuristic strategy. Finally, we provide several engineering
insights on what in-network computation can achieve in both types of networks.
49
Nanda, Ashish. "Adaptive secure network model for dynamic wireless mesh network". Thesis, 2018. http://hdl.handle.net/10453/129428.
Testo completoAbstract (sommario):
University of Technology Sydney. Faculty of Engineering and Information Technology.We as an advanced civilization rely on communication networks for a lot of important tasks. They are used to share information between vital systems, provide us with our pin-point location, access various digital resources and to stay connected with each other. Due to its necessity and enormity, maintaining and securing such a communication medium is an important task. As most communication networks rely on centralized systems, they are bound by the control of a central entity and are unable to keep up with the current growth of the network and advancements in electronic devices. The next step in an inter-connected world requires a decentralized distributed system that can also provide high levels of security. One possible solution is a dynamic distributed wireless mesh network as it provides all the features of a traditional network along with the flexibility of wireless communication and an infrastructure less distributed setup. The network can be created by connecting mobile or stationary devices together using wireless communication devices (such as smartphones, laptops, hot-spots, etc). As the network is created by multiple devices, it would not break-down if some of the devices were disabled. On the contrary, as the network uses hopping for message transmission using dynamic routes, it can self-heal by creating alternate routes if a device was to fail. As the workings and features of a dynamic mesh network differ from the traditional network, it also requires a modified security framework that can provide high levels of security whilst taking benefit of the dynamic mesh network’s unique features. This thesis investigates the problems and limitations linked to secure dynamic wireless mesh networks and how they can be improved upon. In addition to the routing protocols used and how they can be improved upon, the thesis also elaborates on the various security concerns with such networks. As distributed networks aren’t dependent on a central entity, enabling various security features such as authentication are a major challenge. In addition to the decentralized nature of the networks, a single security scheme would not be able to cover the various types of requirements a given scenario in the network might have. Along with authentication, providing end-to-end encryption is also an important component towards ensuring the data travelling through the network is secure and not tampered with. Encryption is also essential in a dynamic wireless mesh network as the data transmitted travels through multiple devices on the network before reaching the destination node and can be easily compromised if not secured. With such an importance of encryption, the network also requires a key management and distribution framework. As traditional network uses a centralized system for maintaining and distributing cryptographic keys in the network, it is a big challenge to implement the same in a distributed network with minimal dependence on a central entity. The key exchange must consider the nature of the network and accordingly incorporate improvements to be able to function in a distributed network. This thesis explores the above areas to propose a new network model for a secure dynamic wireless mesh network including a new routing scheme and a security framework comprising a hybrid encryption scheme, a hybrid authentication scheme and an improved key exchange and management scheme. This thesis demonstrates that our solutions not only strengthen and secure the dynamic wireless mesh networks but also significantly improve the performance and efficiency as compared to existing approaches.
50
Paladugu, Bharath. "North Carolina truck network model". 2007. http://www.lib.ncsu.edu/theses/available/etd-07092007-094756/unrestricted/etd.pdf.
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