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Dissertations / Theses on the topic 'Network analysis'
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1
Oesterheld, Matthias. "Analysis of biomolecular networks using a generic network analysis suite." kostenfrei, 2008. http://mediatum2.ub.tum.de/doc/646475/646475.pdf.
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Post, David L. "Network Management: Assessing Internet Network-Element Fault Status Using Neural Networks." Ohio : Ohio University, 2008. http://www.ohiolink.edu/etd/view.cgi?ohiou1220632155.
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Lim, Kok Seng. "Analysis of network management protocols in optical networks." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Mar%5FLim%5FK.pdf.
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Silva, do Monte Lima Jennifer. "Performance analysis of network composition in ambient networks." Universidade Federal de Pernambuco, 2007. https://repositorio.ufpe.br/handle/123456789/2637.
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Previous issue date: 2007Conselho Nacional de Desenvolvimento Científico e Tecnológico
Atualmente, o compartilhamento de recursos e oferta de serviços entre redes são permitidos apenas através de intensa configuração manual e acordos prévios entre as redes envolvidas. Devido às diferentes tecnologias de acesso, à heterogeneidade dos dispositivos e dos serviços e a mobilidade dos usuários, o gerenciamento dos recursos se torna uma tarefa ainda mais complexa. As Redes de Ambiente surgem para permitir a cooperação instantânea e dinâmica de redes heterogêneas pertencentes a diferentes domínios administrativos e tecnológicos, através de um novo conceito chamado de Composição de Redes. A Composição permite a disponibilização de serviços e o compartilhamento de recursos entre redes, via Acordo de Composição. O desempenho da composição tem um fator crucial na viabilidade das Redes de Ambiente, devido à alta demanda por composição em uma interação de um usuário típico com a rede. Estas composições de redes mudam todo o cenário e trazem novas complicações para o processo tornando necessária a avaliação da estabilidade e da escalabilidade das mesmas. Diante da impossibilidade de testar tais conceitos de forma prática e real, optouse por fazê-lo através de simulação. Para atingir este objetivo foi especificado e implementado um simulador para Composições de Redes de Ambiente. Este simulador tem como objetivo principal avaliar o desempenho da composição mostrando que a mesma não representa um gargalo para a implantação das Redes de Ambiente
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Woodbury, Nathan Scott. "Network Reconstruction and Vulnerability Analysis of Financial Networks." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6370.
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Passive network reconstruction is the process of learning a structured (networked) representation of a dynamic system through the use of known information about the structure of the system as well as data collected by observing the inputs into a system along with the resultant outputs. This work demonstrates an improvement on an existing network reconstruction algorithm so that the algorithm is capable of consistently and perfectly reconstructing a network when system inputs and outputs are measured without error. This work then extends the improved network reconstruction algorithm so that it functions even in the presence of noise as well as the situation where inputs into the system are unknown. Furthermore, this work demonstrates the capability of the new extended algorithms by reconstructing financial networks from stock market data, and then performing an analysis to understand the vulnerabilities of the reconstructed network to destabilization through localized attacks. The creation of these improved and extended algorithms has opened many theoretical questions, paving the way for future research into network reconstruction.
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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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Hassan, Aamir, and Fida Mohammad. "Network Security Analysis." Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-4002.
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Security is the second step after that a successful network has been deployed. There are many types of attacks that could potentially harm the network and an administrator should carefully document and plan the weak areas, where the network could be compromised. Attackers use special tools and techniques to find out all the possible ways of defeating the network security. This thesis addresses all the possible tools and techniques that attackers use to compromise the network. The purpose for exploring these tools will help an administrator to find the security holes before an attacker can. All of these tools in this thesis are only for the forensic purpose. Securing routers and switches in the best possible way is another goal. We in this part try to identify important ways of securing these devices, along with their limitations, and then determine the best possible way. The solution will be checked with network vulnerable tools to get the results. It is important to note that most of the attention in network security is given to the router, but far less attention is given to securing a switch. This thesis will also address some more ways of securing a switch, if there is no router in the network.
The opponent for the thesis was Yan Wang and the presentation time was 60 minutes.
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Mei, Jonathan B. "Principal Network Analysis." Research Showcase @ CMU, 2018. http://repository.cmu.edu/dissertations/1175.
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Many applications collect a large number of time series, for example, temperature continuously monitored by weather stations across the US or neural activity recorded by an array of electrical probes. These data are often referred to as unstructured. A first task in their analytics is often to derive a low dimensional representation { a graph or discrete manifold { that describes the inter relations among the time series and their intrarelations across time. In general, the underlying graphs can be directed and weighted, possibly capturing the strengths of causal relations, not just the binary existence of reciprocal correlations. Furthermore, the processes generating the data may be non-linear and observed in the presence of unmodeled phenomena or unmeasured agents in a complex networked system. Finally, the networks describing the processes may themselves vary through time. In many scenarios, there may be good reasons to believe that the graphs are only able to vary as linear combinations of a set of \principal graphs" that are fundamental to the system. We would then be able to characterize each principal network individually to make sense of the ensemble and analyze the behaviors of the interacting entities. This thesis acts as a roadmap of computationally tractable approaches for learning graphs that provide structure to data. It culminates in a framework that addresses these challenges when estimating time-varying graphs from collections of time series. Analyses are carried out to justify the various models proposed along the way and to characterize their performance. Experiments are performed on synthetic and real datasets to highlight their effectiveness and to illustrate their limitations.
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Zhou, Lin. "Active network management and uncertainty analysis in distribution networks." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.675697.
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In distribution networks, the traditional way to eliminate network stresses caused by increasing generation and demand is to reinforce the primary network assets. A cheaper alternative is active network management (ANM) which refers to real-time network control to resolve power flow, voltage, fault current and security issues. However, there are two limitations in ANM. First, previous ANM strategies investigated generation side and demand side management separately. The generation side management evaluates the value from ANM in terms of economic generation curtailment. It does not consider the potential benefits from integrating demand side response such as economically shifting flexible load over time. Second, enhancing generation side management with load shifting requires the prediction of network stress whose accuracy will decrease as the lead time increases. The uncertain prediction implies the potential failure of reaching expected operational benefits. However, there is very limited investigation into the trade-offs between operational benefit and its potential risk. In order to tackle the challenges, there are two aspects of research work in this thesis. 1) Enhanced ANM. It proposes the use of electric vehicles (EVs) as responsive demand to complement generation curtailment strategies in relieving network stress. This is achieved by shifting flexible EV charging demand over time to absorb excessive wind generation when they cannot be exported to the supply network. 2) Uncertainty management. It adopts Sharpe Ratio and Risk Adjust Return On Capital concepts from financial risk management to help the enhanced ANM make operational decisions when both operational benefit and its associated risk are considered. Copula theory is applied to further integrate correlations of forecasting errors between nodal power injections (caused by wind and load forecasting) into uncertainty management. The enhanced ANM can further improve network efficiency of the existing distribution networks to accommodate increasing renewable generation. The cost-benefit assessment informs distribution network operators of the trade-off between investment in ANM strategy and in the primary network assets, thus helping them to make cost-effective investment decisions. The uncertainty management allows the impact of risks that arise from network stress prediction on the expected operational benefits to be properly assessed, thus extending the traditional deterministic cost-benefit assessment to cost-benefit-risk assessment. Moreover, it is scalable to other systems in any size with low computational burden, which is the major contribution of this thesis.
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鄧沛權 and Pui-kuen Tang. "Business network: network marketing : analysis of network marketing using business network theories." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31268316.
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Tang, Pui-kuen. "Business network : network marketing : analysis of network marketing using business network theories /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B18840127.
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She, Huimin. "Network-Calculus-based Performance Analysis for Wireless Sensor Networks." Licentiate thesis, KTH, Electronic, Computer and Software Systems, ECS, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10686.
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Recently, wireless sensor network (WSN) has become a promising technologywith a wide range of applications such as supply chain monitoringand environment surveillance. It is typically composed of multiple tiny devicesequipped with limited sensing, computing and wireless communicationcapabilities. Design of such networks presents several technique challengeswhile dealing with various requirements and diverse constraints. Performanceanalysis techniques are required to provide insight on design parametersand system behaviors.
Based on network calculus, we present a deterministic analysis methodfor evaluating the worst-case delay and buffer cost of sensor networks. Tothis end, three general traffic flow operators are proposed and their delayand buffer bounds are derived. These operators can be used in combinationto model any complex traffic flowing scenarios. Furthermore, the methodintegrates a variable duty cycle to allow the sensor nodes to operate at lowrates thus saving power. In an attempt to balance traffic load and improveresource utilization and performance, traffic splitting mechanisms areintroduced for mesh sensor networks. Based on network calculus, the delayand buffer bounds are derived in non-splitting and splitting scenarios.In addition, analysis of traffic splitting mechanisms are extended to sensornetworks with general topologies. To provide reliable data delivery in sensornetworks, retransmission has been adopted as one of the most popularschemes. We propose an analytical method to evaluate the maximum datatransmission delay and energy consumption of two types of retransmissionschemes: hop-by-hop retransmission and end-to-end retransmission.
We perform a case study of using sensor networks for a fresh food trackingsystem. Several experiments are carried out in the Omnet++ simulationenvironment. In order to validate the tightness of the two bounds obtainedby the analysis method, the simulation results and analytical results arecompared in the chain and mesh scenarios with various input traffic loads.From the results, we show that the analytic bounds are correct and tight.Therefore, network calculus is useful and accurate for performance analysisof wireless sensor network.
Ipack VINN Excellence Center
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Leung, Ian Xiao Yin. "Fast network analysis and applications in real-world networks." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609931.
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Diana, Gary M. "Internetworking : an analysis and proposal /." Online version of thesis, 1990. http://hdl.handle.net/1850/10605.
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Zhao, Liang. "Multi-area network analysis." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1482.
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After the deregulation of the power systems, the large-scale power systems may contain
several areas. Each area has its own control center and each control center may have its
own state estimator which processes the measurements received from its local
substations. When scheduling power transactions, which involve several control areas a
system-wide state estimation solution is needed. In this dissertation, an estimation
approach which coordinates locally obtained decentralized estimates while improving
bad data processing capability at the area boundaries is presented. It is assumed that
synchronized phasor measurements from different area buses are available in addition to
the conventional measurements provided by the substation remote terminal units. The
estimator with hierarchical structure is implemented and tested using different
measurement configurations for two systems having 118 and 4520 buses. Furthermore,
we apply this multi-area solution scheme to the problem of Total Transfer Capability
(TTC) calculation. In a restructured power system, the sellers and buyers of power
transactions may be located in different areas. Computation of TTC will then require
system-wide studies. We investigate a multi-area solution scheme, which takes
advantage of the system-wide calculated Power Transfer Distribution Factors (PTDF) in
order for each area to calculate its own TTC while a central entity coordinates these
results to determine the final value. The proposed problem formulation and its solution
algorithm are presented. 30 and 4520 bus test systems are used to demonstrate the
approach and numerically verify the proposed TTC calculation method.
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Stone, Larry W. "Local area network analysis." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/27120.
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Approved for public release; distribution is unlimitedThis thesis focuses on the performance of the Ethernet local area network in Ingersoll Hall, Room 250, Naval Postgraduate School, Monterey, California. The primary research is in performing a cost benefit analysis, using the economic value imputed to a reduction in average response time as the return on investment. The major objective is to find the best configuration for the network, based on integrating user-computer response time guidelines and the cost benefit analysis to indicate what might be economically acceptable response times for processing initial simultaneous requests for software installed on network servers. Word Perfect 5.0 software was chosen because it is typical of the software that is used in the lab under conditions of simultaneous access. Additionally, some of the effects of response time on human performance will be researched and noted in the conclusions along with the results of the feasibility test of user-computer interfaces and related cost benefit values.
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Masood, Esa Han Hsien 1979. "Accessible broadband network analysis." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/87248.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 126-127).
by Esa Han Haien Masood.
M.Eng.
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Morehead, Heidi Utz. "Rural Health Network Effectiveness: An Analysis at the Network Level." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/27711.
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Residents of rural communities have poorer health status than people living in more populated areas. For example, The Urban and Rural Health Chartbook notes that the age-adjusted death rate among younger (1-24 years of age) persons who live in the most rural counties is 31 percent higher than those who live in the most urban counties and 65 percent higher for those who live in suburban counties (Eberhardt, Ingram, Makuc et al., 2001). Explanation for the health disparity experienced by rural residents is complex due to the influence of both community factors and the socioeconomic and behavior patterns of individuals. Access to health care, including preventive care, as well as substantial challenges with health literacy, higher instances of smoking, and lack of health insurance among rural residents, are some of the main causes of this disparity.
Rural health networks have been touted by many involved with rural health issues as an effective way to address the health disparity experienced by rural areas. The last fifteen years have seen a growth in the development of rural health networks, with a growing number of grantors, e.g. the Health Resources and Services Administration, The Robert Woods Johnson Foundation and states such as New York, Florida, and West Virginia, funding their development. However, little research has been done on the effectiveness of rural health care networks. While some have evaluated rural health networks, Wellever explains that many questions are left unanswered with â the most fundamental question â whether rural health networks benefit either their members or the rural residents they serveâ (1999, p. 133). Thus, it needs to be determined if health networks are in fact a viable means for improving the disparity in rural health and, more importantly, what can be done to make them more effective.
This research provides insight into the correlates of effectiveness for a type of health network, vertically integrated rural health networks. Provan and Milwardâ s (2001) framework for evaluating the effectiveness of public-sector organizational networks, which proposes three levels of analysis, i.e., the community, network, and organization/participant, was adapted to analyze the effectiveness of vertically integrated rural health networks. One-on-one interviews, questionnaires, and archival data were used to collect data on the networks sampled. Primarily, data was collected from four networks that were chosen from a larger sample of twenty-one networks to serve as best practices.
Analysis of the data collected revealed a few significant predictors for the effectiveness of vertically integrated rural health networks. Financing was found to be the most important predictor, as it was significant at both the community and network levels. Both cohesiveness and the number of problems in the rural environment were also found to be significant predictors but only at the network level. No significant predictors were found at the organizational level; however, organizational and network-level effectiveness were found to be strongly correlated with each other. Overall, networks were found to be more favorable about their effectiveness at the network and organizational levels.Ph. D.
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Xie, Jing. "A Temporal Network Calculus for Performance Analysis of Computer Networks." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elektronikk og telekommunikasjon, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-14619.
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One inevitable trend of network development is to deliver information with various traffic characteristics and diverse Quality of Service (QoS) requirements. In response to the continually growing demand for more bandwidth, network performance analysis is needed to optimize the performance of existing technologies and evaluate the efficiency of new ones. Performance analysis investigates how traffic management mechanisms deployed in the network affect the resource allocation among users and the performance which the users experience. This topic can be investigated by constructing models of traffic management mechanisms and studying how these mechanisms perform under various types of network traffic. To this end, appropriate mathematical models are needed to characterize the traffic management mechanisms which we are interested in and represent different types of network traffic. In addition, fundamental properties which can be employed to manipulate the models should be explored. Over the last two decades a relatively new theory, stochastic network calculus, has been developed to enable mathematical performance analysis of computer networks. Particularly, several related processes are mathematically modeled, including the arrival process, the waiting process and the service process. This theory can be applied to the derivation and calculation of several performance metrics such as the backlog bound and the delay bound. The most attractive contribution of stochastic network calculus is to characterize the behavior of a process based on some bound on the complementary cumulative distribution function (CCDF). The behavior of a computer network is often subject to many irregularities and stochastic fluctuations. The models based on the bound on the CCDF are not very accurate, while they are more feasible for abstracting computer network systems and representing various types of network traffic. This thesis is devoted to investigate the performance of networks from the temporal perspective. Specifically, the traffic arrival process characterizes the distribution of the cumulative inter-arrival time and the service process describes the distribution of the cumulative service time. Central to finding a bound on the CCDF of the cumulative interarrival time and the cumulative service time, several variations of the traffic characterization and the service characterization are developed. The purpose of developing several variations to characterize the same process is to facilitate the derivation and calculation of performance metrics. In order to derive and calculate the performance metrics, four fundamental properties are explored, including the service guarantees, the output characterization, the concatenation property and the superposition property. The four properties can be combined differently when deriving the performance metrics of a single node, a series of nodes or the superposition flow. Compared to the available literature on stochastic network calculus which mainly focuses on studying network performance in the spacedomain, this work develops a generic framework for mathematically analyzing network performance in the time-domain. The potential applications of this temporal approach include the wireless networks and the multi-access networks. Furthermore, the complete procedure of concretizing the generic traffic models and service models is presented in detail. It reveals the key of applying the developed temporal network calculus approach to network performance analysis, i.e., to derive the bounding function which is the upper bound on the tail probability of a stochastic process. Several mathematical methods are introduced, such as the martingale, the moment generating function (MGF) and a concentration theory result
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Carter, Steven Michael. "Implementation and analysis of the IP measurement protocol (IPMP)." Master's thesis, Mississippi State : Mississippi State University, 2001. http://library.msstate.edu/etd/show.asp?etd=etd-11152001-090121.
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Moore, John David. "Making Sense of Networks: Exploring How Network Participants Understand and Use Information From Social Network Analysis." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/103640.
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Many of today's complex public issues are best addressed by multi-sectoral multi-organizational responses that include different types of organizations working together (Kettl, 2008; O'Toole, 1997). Social network analysis (SNA) of interorganizational networks has emerged as a useful tool for network managers to understand the structure and function of the complex networks in which they seek to manage (Human and Provan, 1997, 2000; Provan and Milward, 1995; Provan, Sebastian, and Milward, 1996; Provan, Veazie, Staten, and Teufel-Shone, 2005).
The output of an interorganizational SNA typically provides a range of information to network managers including network plots. The network plots provide visual representations of different aspects of the network by showing the kinds of ties between the actors in the network.
The information from network analyses can help network managers encourage systems thinking, see the different roles played by organizations, or identify links to outside resources among many other uses, but "will only have practical value to communities if it can be effectively presented, discussed, accepted, and acted on by community leaders and network participants [emphasis added]." (Provan et al., 2005, p. 610). However, little is currently known about if or how the information embedded in network plots is accepted or acted on by network participants.
The visual representations of the network (network plots) provided to network participants following a SNA are often open to a range of interpretations that may or may not align with the findings of the analyst or the intended use by network managers, raising many interesting questions. Little is currently known about how differently situated network participants might interpret the same network plots differently. Nor do we understand what factors might influence different individuals or organizations to come up with different interpretations.
After conducting a SNA and presenting it to network participants, I conducted interviews with a range of different representatives from participating organizations. I used a particular form of semi-structured interview, a situated micro-element interview from Dervin's Sense Making Methodology (SMM) (Dervin, Foreman-Wernet, and Lauterbach, 2003). I then analyzed the interview transcripts using standard qualitative coding methods (Bailey, 2007) to see if themes emerged that addressed the research questions.
I found that most informants had trouble extracting information and meaning from their examination of the plots without that meaning and interpretation being provided by the expert analyst. I posit some potential explanations for why that might be so in the case I studied. I then turn to some interesting methodological considerations that emerged from taking the perspectives of network participants seriously.
Finally, I synthesize the subject area and methodological findings into a refined framework for sense-making around network plots and offer propositions and potential approaches for future research.Doctor of Philosophy
Many of today's complex public issues are best addressed by multi-sectoral multi-organizational responses that include different types of organizations working together (Kettl, 2008; O'Toole, 1997). Social network analysis (SNA) of interorganizational networks has emerged as a useful tool for network managers to understand the structure and function of the complex networks in which they seek to manage (Human and Provan, 1997, 2000; Provan and Milward, 1995; Provan, Sebastian, and Milward, 1996; Provan, Veazie, Staten, and Teufel-Shone, 2005). The output of an interorganizational SNA typically provides a range of information to network managers including network plots. The network plots provide visual representations of different aspects of the network by showing the kinds of ties between the actors in the network. The information from network analyses can help network managers encourage systems thinking, see the different roles played by organizations, or identify links to outside resources among many other uses, but "will only have practical value to communities if it can be effectively presented, discussed, accepted, and acted on by community leaders and network participants [emphasis added]." (Provan et al., 2005, p. 610). However, little is currently known about if or how the information embedded in network plots is accepted or acted on by network participants. The visual representations of the network (network plots) provided to network participants following a SNA are often open to a range of interpretations that may or may not align with the findings of the analyst or the intended use by network managers, raising many interesting questions. Little is currently known about how differently situated network participants might interpret the same network plots differently. Nor do we understand what factors might influence different individuals or organizations to come up with different interpretations. After conducting a SNA and presenting it to network participants, I conducted interviews with a range of different representatives from participating organizations. I used a particular form of semi-structured interview, a situated micro-element interview from Dervin's Sense Making Methodology (SMM) (Dervin, Foreman-Wernet, and Lauterbach, 2003). I then analyzed the interview transcripts using standard qualitative coding methods (Bailey, 2007) to see if themes emerged that addressed the research questions. I found that most informants had trouble extracting information and meaning from their examination of the plots without that meaning and interpretation being provided by the expert analyst. I posit some potential explanations for why that might be so in the case I studied. I then turn to some interesting methodological considerations that emerged from taking the perspectives of network participants seriously. Finally, I synthesize the subject area and methodological findings into a refined framework for sense-making around network plots and offer propositions and potential approaches for future research.
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Moore, John. "Making Sense of Networks: Exploring How Network Participants Understand and Use Information From Social Network Analysis." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/103640.
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Many of today's complex public issues are best addressed by multi-sectoral multi-organizational responses that include different types of organizations working together (Kettl, 2008; O'Toole, 1997). Social network analysis (SNA) of interorganizational networks has emerged as a useful tool for network managers to understand the structure and function of the complex networks in which they seek to manage (Human and Provan, 1997, 2000; Provan and Milward, 1995; Provan, Sebastian, and Milward, 1996; Provan, Veazie, Staten, and Teufel-Shone, 2005).
The output of an interorganizational SNA typically provides a range of information to network managers including network plots. The network plots provide visual representations of different aspects of the network by showing the kinds of ties between the actors in the network.
The information from network analyses can help network managers encourage systems thinking, see the different roles played by organizations, or identify links to outside resources among many other uses, but "will only have practical value to communities if it can be effectively presented, discussed, accepted, and acted on by community leaders and network participants [emphasis added]." (Provan et al., 2005, p. 610). However, little is currently known about if or how the information embedded in network plots is accepted or acted on by network participants.
The visual representations of the network (network plots) provided to network participants following a SNA are often open to a range of interpretations that may or may not align with the findings of the analyst or the intended use by network managers, raising many interesting questions. Little is currently known about how differently situated network participants might interpret the same network plots differently. Nor do we understand what factors might influence different individuals or organizations to come up with different interpretations.
After conducting a SNA and presenting it to network participants, I conducted interviews with a range of different representatives from participating organizations. I used a particular form of semi-structured interview, a situated micro-element interview from Dervin's Sense Making Methodology (SMM) (Dervin, Foreman-Wernet, and Lauterbach, 2003). I then analyzed the interview transcripts using standard qualitative coding methods (Bailey, 2007) to see if themes emerged that addressed the research questions.
I found that most informants had trouble extracting information and meaning from their examination of the plots without that meaning and interpretation being provided by the expert analyst. I posit some potential explanations for why that might be so in the case I studied. I then turn to some interesting methodological considerations that emerged from taking the perspectives of network participants seriously.
Finally, I synthesize the subject area and methodological findings into a refined framework for sense-making around network plots and offer propositions and potential approaches for future research.Doctor of Philosophy
Many of today's complex public issues are best addressed by multi-sectoral multi-organizational responses that include different types of organizations working together (Kettl, 2008; O'Toole, 1997). Social network analysis (SNA) of interorganizational networks has emerged as a useful tool for network managers to understand the structure and function of the complex networks in which they seek to manage (Human and Provan, 1997, 2000; Provan and Milward, 1995; Provan, Sebastian, and Milward, 1996; Provan, Veazie, Staten, and Teufel-Shone, 2005). The output of an interorganizational SNA typically provides a range of information to network managers including network plots. The network plots provide visual representations of different aspects of the network by showing the kinds of ties between the actors in the network. The information from network analyses can help network managers encourage systems thinking, see the different roles played by organizations, or identify links to outside resources among many other uses, but "will only have practical value to communities if it can be effectively presented, discussed, accepted, and acted on by community leaders and network participants [emphasis added]." (Provan et al., 2005, p. 610). However, little is currently known about if or how the information embedded in network plots is accepted or acted on by network participants. The visual representations of the network (network plots) provided to network participants following a SNA are often open to a range of interpretations that may or may not align with the findings of the analyst or the intended use by network managers, raising many interesting questions. Little is currently known about how differently situated network participants might interpret the same network plots differently. Nor do we understand what factors might influence different individuals or organizations to come up with different interpretations. After conducting a SNA and presenting it to network participants, I conducted interviews with a range of different representatives from participating organizations. I used a particular form of semi-structured interview, a situated micro-element interview from Dervin's Sense Making Methodology (SMM) (Dervin, Foreman-Wernet, and Lauterbach, 2003). I then analyzed the interview transcripts using standard qualitative coding methods (Bailey, 2007) to see if themes emerged that addressed the research questions. I found that most informants had trouble extracting information and meaning from their examination of the plots without that meaning and interpretation being provided by the expert analyst. I posit some potential explanations for why that might be so in the case I studied. I then turn to some interesting methodological considerations that emerged from taking the perspectives of network participants seriously. Finally, I synthesize the subject area and methodological findings into a refined framework for sense-making around network plots and offer propositions and potential approaches for future research.
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Hui, Daniel Hang-Yan. "Protocol validation via reachability analysis : an implementation." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/24689.
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Reachability analysis is one of the earliest and most common techniques for protocol validation. It is well suited to checking the protocol syntactic properties since they are a direct consequence of the structure of the reachability tree. However, validations of unbounded protocols via reachability analysis always lead to the "state explosion" problem. To overcome this, a new approach in reachability analysis has been proposed by Vuong et al [Vuong 82a, 83a]. While not loosing any information on protocol syntactic properties, the Teachability tree constructed by the new approach for all non-FIFO and for a particular set of FIFO protocols (called well-ordered protocols) will become finite. This thesis is concerned with the implementation of an integrated package called VALIRA (VALIdation via Reachability Analysis) which bases on both the proposed technique and the conventional technique. Details and implementation of the various approaches used in VALIRA are presented in order to provide an insight to the package. Various features of the package are demonstrated with examples on different types of protocols, such as the FIFO, the non-FIFO, and the priority protocols. The use of VALIRA was found to be practical in general, despite some limitations of the package. Further enhancements on the VALIRA are also suggested.Science, Faculty of
Computer Science, Department of
Graduate
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Gatkowski, Mateusz. "Financial network stability and structure : econometric and network analysis." Thesis, University of Essex, 2015. http://repository.essex.ac.uk/17090/.
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Since the Global Financial Crisis, the literature of financial networks analysis has been trying to investigate the changes in the financial networks structure, that led to the instability of the financial system. The Global Financial Crisis followed by the Great Recession costed taxpayers an unprecedented $14 trillion (Alessandri and Haldane, 2009), austerity and downturns in GDP. The dynamics of the financial networks transferred the collapse of a US housing market bubble into a large meltdown of the financial systems globally. The study of systemic risk and macro-prudential policy has come to the forefront to model and manage the negative externalities of monetary, fiscal and financial sector activities that can lead to system wide instabilities and failure. The dimensions of crisis propagation have been modelled as those that can spread cross-sectionally in domino like failures with global scope, or build up over time, as in asset bubbles. The cross sectional propagation of shocks that occur due to non-payment of debt or other financial obligations with the failure of a financial intermediary or a sovereign leading to the failure of other economic entities, is called financial contagion. Cross sectional analysis of financial contagion can be done using statistical methods or by network analysis. The latter gives a structural model of the interconnections in terms of financial obligations. This dissertation uses both approaches to model financial contagion. The applications include the study of systemic risk in Eurozone Sovereign crisis, the US CDS market and the global banking network. This is organized in three self-contained chapters Our contribution to the literature begins with the study of the dynamics of the market of the Credit Default Swap (CDS) contracts for selected Eurozone sovereigns and the UK. The EWMA correlation analysis and the Granger-causality test demonstrate that there was contagion effect since correlations and cross-county interdependencies increased after August 2007. Furthermore, the IRF analysis shows that among PIIGS, the CDS spreads of Spain and Ireland have the biggest impact on the European CDS spreads, whereas the UK is found not be a source of sovereign contagion to the Eurozone. Next we perform the empirical reconstruction of the US CDS network based on the real-world data obtained from the FDIC Call Reports, and study the propagation of contagion, assuming different network structures. The financial network shows a highly tiered core-periphery structure. We find that network topology matters for the stability of the financial system. The “too interconnected to fail” phenomenon is discussed and shown to be the result of highly tiered network with central core of so called super-spreaders. In this type of network the contagion is found to be short, without multiple waves, but with very high losses brought by the core of the network. Finally we study a global banking network (GBN) model based on the Markose (2012) eigen-pair approach and propose a systemic risk indices (SRI) which provide early warning signals for systemic instability and also the rank order of the systemic importance and vulnerability of the banking systems. The empirical model is based on BIS Consolidated Banking Statistics for the exposures of 19 national banking systems to the same number of debtor countries and the data obtained from Bankscope for the equity capital of these 19 national banking systems. The SRI is based on the ratio of the netted cross-border exposures of the national banking systems to their respective equity capital. The eigen-pair method stipulates that if the maximum eigenvalue of the network exceeds the capital threshold, there is cause for concern of a contagion. This is compared with the loss multiplier SRI proposed by Castrén and Rancan (2012). The latter is found to have no early warning capabilities and peaks well after the onset of the crisis in 2009 while the eigen-pair SRI gives ample warning by late 2006 that the cross border liabilities was unsustainable in respect of the equity capital of the national banking systems. We contribute to the literature by highlighting the efficacy of the network approach to systemic stability analysis of GBNs. In particular we develop an eigen-pair approach for GBNs and prove its usefulness in an early warning context.
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Kuehn, Daniel, and 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.
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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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Morley, George David. "Analysis and design of ring-based transport networks." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ60329.pdf.
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Baronikian, Haig. "Modelling and analysis of a computer conferencing system." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63756.
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Kim, Hyoungshick. "Complex network analysis for secure and robust communications." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610134.
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Kouhbor, Shahnaz University of Ballarat. "Optimal number and placement of network infrastructure in wireless networks." University of Ballarat, 2007. http://archimedes.ballarat.edu.au:8080/vital/access/HandleResolver/1959.17/12762.
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Wireless Local Area Networks (WLANs) have become a major success in telecommunications during the last few years, due to advantages such as mobility, flexibility, and easier maintenance. A device called an access point (AP) acts as a base station in WLAN for connecting a group of users to the network via radio signal. During the planning of such a network an important problem is to determine the optimal number of these devices and their placement/distribution so that coverage, capacity, and physical security are maximised at minimum cost. In this thesis we are using continuous optimisation techniques to optimise the number of APs and their distribution while cost of deployment is reduced and physical security of the network is enhanced. To find the number and placement of APs, we developed a multi-objective functions model based on path losses and power for free space environments. The two functions in the models are combined by using a balancing parameter. Since it is recognised that some of the objectives can be handled one at a time, in another approach, we followed a step-by-step procedure. We start with a novel optimisation model based on path losses for indoor environments including obstacles. Cost of deployment is saved by finding the minimum number of APs ensuring that the path loss at each test point/receiver is below the given maximum path loss. Next, the physical security of the network is enhanced by placing the APs far from places accessible to unauthorised users to reduce the risk of intrusion into the network. This is achieved in the framework of the model by introducing potential unauthorised users in unauthorised areas for whom coverage is minimised. Due to the presence of obstacles in indoor buildings, the path loss function is discontinuous. Therefore, the objective functions are very complicated and most of the existing optimisation algorithms cannot be applied to solve the problem. We use a global optimisation algorithm that is not used by other researchers to solve the same problem. To validate the accuracy of the optimisation model and performance of the numerical methods, we run tests on several indoor buildings and use wide range of WLAN parameters. The results demonstrate the quality of our model and algorithm. Based on the proposed model and algorithm, we developed a software to assist the network designers in planning wireless LANs.Doctor of Philosophy
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Kouhbor, Shahnaz. "Optimal number and placement of network infrastructure in wireless networks." Thesis, University of Ballarat, 2007. http://researchonline.federation.edu.au/vital/access/HandleResolver/1959.17/65892.
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Wireless Local Area Networks (WLANs) have become a major success in telecommunications during the last few years, due to advantages such as mobility, flexibility, and easier maintenance. A device called an access point (AP) acts as a base station in WLAN for connecting a group of users to the network via radio signal. During the planning of such a network an important problem is to determine the optimal number of these devices and their placement/distribution so that coverage, capacity, and physical security are maximised at minimum cost. In this thesis we are using continuous optimisation techniques to optimise the number of APs and their distribution while cost of deployment is reduced and physical security of the network is enhanced. To find the number and placement of APs, we developed a multi-objective functions model based on path losses and power for free space environments. The two functions in the models are combined by using a balancing parameter. Since it is recognised that some of the objectives can be handled one at a time, in another approach, we followed a step-by-step procedure. We start with a novel optimisation model based on path losses for indoor environments including obstacles. Cost of deployment is saved by finding the minimum number of APs ensuring that the path loss at each test point/receiver is below the given maximum path loss. Next, the physical security of the network is enhanced by placing the APs far from places accessible to unauthorised users to reduce the risk of intrusion into the network. This is achieved in the framework of the model by introducing potential unauthorised users in unauthorised areas for whom coverage is minimised. Due to the presence of obstacles in indoor buildings, the path loss function is discontinuous. Therefore, the objective functions are very complicated and most of the existing optimisation algorithms cannot be applied to solve the problem. We use a global optimisation algorithm that is not used by other researchers to solve the same problem. To validate the accuracy of the optimisation model and performance of the numerical methods, we run tests on several indoor buildings and use wide range of WLAN parameters. The results demonstrate the quality of our model and algorithm. Based on the proposed model and algorithm, we developed a software to assist the network designers in planning wireless LANs.Doctor of Philosophy
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Kouhbor, Shahnaz. "Optimal number and placement of network infrastructure in wireless networks." University of Ballarat, 2007. http://archimedes.ballarat.edu.au:8080/vital/access/HandleResolver/1959.17/14597.
Full textAbstract:
Wireless Local Area Networks (WLANs) have become a major success in telecommunications during the last few years, due to advantages such as mobility, flexibility, and easier maintenance. A device called an access point (AP) acts as a base station in WLAN for connecting a group of users to the network via radio signal. During the planning of such a network an important problem is to determine the optimal number of these devices and their placement/distribution so that coverage, capacity, and physical security are maximised at minimum cost. In this thesis we are using continuous optimisation techniques to optimise the number of APs and their distribution while cost of deployment is reduced and physical security of the network is enhanced. To find the number and placement of APs, we developed a multi-objective functions model based on path losses and power for free space environments. The two functions in the models are combined by using a balancing parameter. Since it is recognised that some of the objectives can be handled one at a time, in another approach, we followed a step-by-step procedure. We start with a novel optimisation model based on path losses for indoor environments including obstacles. Cost of deployment is saved by finding the minimum number of APs ensuring that the path loss at each test point/receiver is below the given maximum path loss. Next, the physical security of the network is enhanced by placing the APs far from places accessible to unauthorised users to reduce the risk of intrusion into the network. This is achieved in the framework of the model by introducing potential unauthorised users in unauthorised areas for whom coverage is minimised. Due to the presence of obstacles in indoor buildings, the path loss function is discontinuous. Therefore, the objective functions are very complicated and most of the existing optimisation algorithms cannot be applied to solve the problem. We use a global optimisation algorithm that is not used by other researchers to solve the same problem. To validate the accuracy of the optimisation model and performance of the numerical methods, we run tests on several indoor buildings and use wide range of WLAN parameters. The results demonstrate the quality of our model and algorithm. Based on the proposed model and algorithm, we developed a software to assist the network designers in planning wireless LANs.Doctor of Philosophy
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Yang, Zhenyu. "Network Coding in Multihop Wireless Networks: Throughput Analysis and Protocol Design." Digital WPI, 2011. https://digitalcommons.wpi.edu/etd-dissertations/222.
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Multi-hop wireless networks have been widely considered as promising approaches to provide more convenient Internet access for their easy deployment, extended coverage, and low deployment cost. However, providing high-speed and reliable services in these networks is challenging due to the unreliable wireless links, broadcast nature of wireless transmissions, and frequent topology changes. On the other hand, network coding (NC) is a technique that could significantly improve the network throughput and the transmission reliability by allowing intermediate nodes to combine received packets. More recently proposed symbol level network coding (SLNC), which combines packets at smaller symbol scale, is a more powerful technique to mitigate the impact of lossy links and packet collisions in wireless networks. NC, especially SLNC, is thus a particular effective approach to providing higher data rate and better transmission reliability for applications such as mobile content distribution in multihop wireless networks. This dissertation focuses on exploiting NC in multihop wireless networks. We studied the unique features of NC and designed a suite of distributed and localized algorithms and protocols for content distribution networks using NC and SLNC. We also carried out a theoretical study on the network capacity and performance bounds achievable by SLNC in mobile wireless networks. We proposed CodeOn and CodePlay for popular content distribution and live multimedia streaming (LMS) in vehicular ad hoc networks (VANETs), respectively, where many important practical factors are taken into consideration, including vehicle distribution, mobility pattern, channel fading and packet collision. Specifically, CodeOn is a novel push based popular content distribution scheme based on SLNC, where contents are actively broadcast to vehicles from road side access points and further distributed among vehicles using a cooperative VANET. In order to fully enjoy the benefits of SLNC, we proposed a suite of techniques to maximize the downloading rate, including a prioritized and localized relay selection mechanism where the selection criteria is based on the usefulness of contents possessed by vehicles, and a lightweight medium access protocol that naturally exploits the abundant concurrent transmission opportunities. CodePlay is designed for LMS applicaitions in VANETs, which could fully take advantage of SLNC through a coordinated local push mechanism. Streaming contents are actively disseminated from dedicated sources to interested vehicles via local coordination of distributively selected relays, each of which will ensure smooth playback for vehicles nearby. CodeOn pursues a single objective of maximizing downloading rate, while CodePlay improves the performance of LMS service in terms of streaming rate, service delivery delay, and bandwidth efficiency simultaneously. CodeOn and CodePlay are among the first works that exploit the features of SLNC to simplify the protocol design whilst achieving better performance. We also developed an analytical framework to compute the expected achievable throughput of mobile content distribution in VANETs using SLNC. We presented a general analytical model for the expected achievable throughput of SLNC in a static wireless network based on flow network theory and queuing theory. Then we further developed the model to derive the expected achievable accumulated throughput of a vehicle driving through the area of interest under a mobility pattern. Our proposed framework captures the effects of multiple practical factors, including vehicle distribution and mobility pattern, channel fading and packet collision, and we characterized the impacts of those factors on the expected achievable throughput. The results from this research are not only of interest from theoretical perspective but also provide insights and guidelines on protocol design in SLNC-based networks.
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Prabhu, Haladi Ramanatha Sachin. "A network component analysis based divide and conquer method for transcriptional regulatory network analysis." Thesis, University of Sheffield, 2019. http://etheses.whiterose.ac.uk/22640/.
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Kozat, Ulaș C. "Heterogeneous wireless networks : an analysis of network and service level diversity /." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1404.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2004.Thesis research directed by: Electrical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Dunn, Nathan A. "A Novel Neural Network Analysis Method Applied to Biological Neural Networks." Thesis, view abstract or download file of text, 2006. http://proquest.umi.com/pqdweb?did=1251892251&sid=2&Fmt=2&clientId=11238&RQT=309&VName=PQD.
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Thesis (Ph. D.)--University of Oregon, 2006.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 122- 131). Also available for download via the World Wide Web; free to University of Oregon users.
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Banerji, Pratip K. "An analysis of network management traffic and requirements in wireless networks." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42744.
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Crowley, Patrick. "Design and analysis of architectures for programmable network processing systems /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/6991.
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Mummaneni, Avanthi. "Analysis of the enzymatic network." Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/4285.
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Thesis (M.S.)--University of Missouri-Columbia, 2005.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (January 22, 2007) Includes bibliographical references.
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Wallis, David C. "Vibration analysis via wireless network." Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion-image.exe/07Sep%5FWallis.pdf.
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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, September 2007.Thesis Advisor(s): Yun, Xiaoping. "September 2007." Description based on title screen as viewed on October 25, 2007. Includes bibliographical references (p. 65-66). Also available in print.
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Liu, Wei 1975. "Network traffic modelling and analysis." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82613.
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In all-photonic networks, both transmission and switching is performed in the optical domain, without optoelectronic conversion for the data traversing the network. An accurate traffic model is critical in an agile all-photonic network (AAPN) which has the ability to dynamically allocate bandwidth to traffic flows as the demand varies.This thesis focuses on traffic modelling and analysis. A novel traffic model is proposed which can capture the traffic behaviours in all-photonic networks. The new model is based on a study of existing traffic modelling literature. It combines the time-varying Poisson model, gravity model and fractional Gaussian noise. This model can be used for the short-range traffic prediction. We examine Long-Range Dependence and test the time constancy of scaling parameters using the tools designed by Abry and Veitch, to analyze empirical and synthesized traffic traces.
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Littlewort, G. C. "Neural network analysis and simulation." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292677.
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Liu, Mei. "Vulnerability analysis of road network." Thesis, University of Bristol, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.617702.
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The vulnerability analysis of road networks has been receiving increased attention due largely to such disparate events as earthquakes and terrorist attacks. The current evaluations of performance of a road network tend to focus on the change of traffic .demand on the network .and the probability of damage events. A major difficulty is the forecasting of low-probability high-consequence events. The research described in this thesis examines the problem from the perspective of identifying the weakest or most vulnerable parts of the network. A new method to examine the vulnerability of road network systems has been developed. The purpose is to identify weaknesses in the form of the network independent of a model of traffic demand or other hazards. The core ideas are based on a previously developed theory of structural vulnerability together with graph theory and road traffic theory. Road networks are represented by graphs and the features of vertices and links are studied. The structural vulnerability theory is applied to road networks in the perspective of systems thinking, which is also the basis for the application of road vulnerability analysis to other network systems, such as railway networks, water pipe networks, electricity networks and the Internet. The major achievements include: (a) the development of a graphical and theoretical model of road circuits, (b) the presentation of a model that describes the relationship of traffic flow and speed) (c) the identification of new measures of road links and circuits such as the transmittance of road links and the well-formedness of road circuits, (d) the development of a new concept of a road cluster and the development of an algorithm for forming clusters, (e) the restructuring of a road network at various hierarchical levels of definition using sets of interconnected road clusters, (f) the development of an algorithm to unzip the hierarchical model so that various failure scenarios may be identified, (g) the examination of the potential applications of the analysis to other transport network systems, (h) the implementation of algorithms into computer programs and user-interactive windows using MATLAB. A selection of various examples of road networks has been used to demonstrate and test the analysis. It is concluded that high vulnerability failure scenarios for a road network are not always obvious and they may be low probability high impact scenarios. Through these scenarios the vulnerable parts of large road networks are identified so that they can be monitored and maintained to be a better form, which would increase robustness and reduce risk. The vulnerability analysis of road networks is potentially of use in the procedures of road network planning and performance improvement.
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Ray, Gavin Peter. "Computer network analysis and optimisation." Thesis, University of Plymouth, 1993. http://hdl.handle.net/10026.1/1639.
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This thesis presents a study and analysis of the major influences on network cost and their related performance. New methods have been devised to find solutions to network optimisation problems particular to the AT&T ISTEL networks in Europe and these are presented together with examples of their successful commercial application. Network performance is seen by the user in terms of network availability and traffic delay times. The network performance is influenced by many parameters, the dominating influences typically being the number of users accessing the network, the type of traffic demands they place upon it and the particular network configuration itself. The number of possible network configurations available to a network designer is vast if the full range of currently available equipment is taken into account. The aim of this research has been to assist in the selection of most suitable network designs for optimum performance and cost. This thesis looks at the current differing network technologies, their performance characteristics and the issues pertinent to any network design and optimisation procedures. A distinction is made between the network equipment providing user 'access' and that which constitutes the cross country, or *core\ data transport medium. This partitioning of the problem is exploited with the analysis concentrating on each section separately. The access side of the AT&T ISTEL - UK network is used as a basis for an analysis of the general access network. The aim is to allow network providers to analyse the root cause of excessive delay problems and find where small adjustments to access configurations might lead to real performance improvements from a user point of view. A method is developed to allow statistical estimates of performance and quality of service for typical access network configurations. From this a general method for the optimisation of cost expenditure and performance improvement is proposed. The optimisation of both circuit switched and packet switched computer networks is shown to be difficult and is normally tackled by the use of complex procedures on mainframe computers. The new work carried out in this study takes a fresh look at the basic properties of networks in order to develop a new heuristic method for the design and optimisation of circuit switched core networks on a personal computer platform. A fully functional design system was developed that implements time division multiplexed core network design. The system uses both a new heuristic method for improving the quality of the designs and a new 'speed up' algorithm for reducing times to find feasible routes, thereby dramatically improving overall design times. The completed system has since been used extensively to assist in the design of commercial networks across Europe.
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LLANES, KATHRIN RODRIGUEZ. "BUS NETWORK ANALYSIS AND MONITORING." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2017. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=31068@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE EXCELENCIA ACADEMICA
Ônibus, equipados com dispositivos GPS ativos que transmitem continuamente a sua posição, podem ser entendidos como sensores móveis de trânsito. De fato, as trajetórias dos ônibus fornecem uma fonte de dados útil para analisar o trânsito na rede de ônibus de uma cidade, dado que as autoridades de trânsito da cidade disponibilizem as trajetórias de forma aberta, oportuna e contínua. Neste contexto, esta tese propõe uma abordagem que usa os dados de GPS dos ônibus para analisar e monitorar a rede de ônibus de uma cidade. Ela combina algoritmos de grafos, técnicas de mineração de dados geoespaciais e métodos estatísticos. A principal contribuição desta tese é uma definição detalhada de operações e algoritmos para analisar e monitorar o tráfego na rede de ônibus, especificamente: (1) modelagem, análise e segmentaçãoda rede de ônibus; (2) mineração do conjunto de dados de trajetória de ônibus para descobrir padrões de tráfego; (3) detecção de anomalias de trânsito, classificação de acordo com sua gravidade, e avaliação do seu impacto; (4) manutenção e comparação de diferentes versões da rede de ônibus e dos seus padrões de tráfego para ajudar os planejadores urbanos a avaliar as mudanças. Uma segunda contribuição é a descrição de experimentos realizados para a rede de ônibus da Cidade do Rio de Janeiro, utilizando trajetórias de ônibus correspondentes ao período de junho de 2014 até fevereiro de 2017, disponibilizadas pela Prefeitura do Rio de Janeiro. Os resultados obtidos corroboram a utilidade da abordagem proposta para analisar e monitorar a rede de ônibus de uma cidade, o que pode ajudar os gestores do trânsito e as autoridades municipais a melhorar os planos de controle de trânsito e de mobilidade urbana.
Buses, equipped with active GPS devices that continuously transmit their position, can be understood as mobile traffic sensors. Indeed, bus trajectories provide a useful data source for analyzing traffic in the bus network of a city, if the city traffic authority makes the bus trajectories available openly, timely and in a continuous way. In this context, this thesis proposes a bus GPS data-driven approach for analyzing and monitoring the bus network of a city. It combines graph algorithms, geospatial data mining techniques and statistical methods. The major contribution of this thesis is a detailed discussion of key operations and algorithms for modeling, analyzing and monitoring bus network traffic, specifically: (1) modelling, analyzing, and segmentation of the bus network; (2) mining the bus trajectory dataset to uncover traffic patterns; (3) detecting traffic anomalies, classifying them according to their severity, and estimating their impact; (4) maintaining and comparing different versions of the bus network and traffic patterns to help urban planners assess changes. Another contribution is the description of experiments conducted for the bus network of the City of Rio de Janeiro, using bus trajectories obtained from June 2014 to February 2017, which have been made available by the City Hall of Rio de Janeiro. The results obtained corroborate the usefulness of the proposed approach for analyzing and monitoring the bus network of a city, which may help traffic managers and city authorities improve traffic control and urban mobility plans.
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Simhairi, Nather Zeki. "Traffic assignment and network analysis." Thesis, Royal Holloway, University of London, 1987. http://repository.royalholloway.ac.uk/items/a3377f99-4ed8-4000-91f8-0384aed4a3c6/1/.
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This thesis studies the transportation network, and is divided into three sections. Initially an algorithm is described which finds the user-equilibrium assignment for networks with linear congestion functions where the cost of travel on a link is dependent on the flow in the whole network. Secondly it investigates the sensitivity of the cost of travel and of the flow distribution in the network, to changes in the link congestion function. Combinatorial methods are used for evaluating the results of the sensitivity analysis. This is done with the aim of obtaining fast and efficient algorithms for the evaluation of cost sensitive and paradoxical links. Finally, for networks where the demand is elastic, it describes the catastrophic behaviour of the point representing the user-equilibrium flow distribution under certain cost conditions.
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Zhang, Wanping. "Power network analysis and optimization." Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3369236.
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Thesis (Ph. D.)--University of California, San Diego, 2009.Title from first page of PDF file (viewed September 17, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 91-94).
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Engström, Helena. "Network Analysis of Calcium Activity." Thesis, KTH, Tillämpad fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-256344.
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CURZI, MIRCO. "Content based social network analysis." Doctoral thesis, Università Politecnica delle Marche, 2009. http://hdl.handle.net/11566/242305.
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Perissinotto, Alex <1991>. "Rischio sistemico e Network Analysis." Master's Degree Thesis, Università Ca' Foscari Venezia, 2017. http://hdl.handle.net/10579/9663.
Full textAbstract:
Scopo della tesi è quello di valutare la presenza di rischio sistemico tra le maggiori banche europee. A tal fine sono state impiegate tecniche ed indicatori propri della teoria delle reti. Per la costruzione dei network sono stati utilizzati i processi autoregressivi vettoriali (VAR). L'analisi è stata effettuata per il periodo post crisi finanziaria (dal 2012 al 2016), con dati a frequenza giornaliera.
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SALA, SARA. "Statistical analysis of brain network." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2013. http://hdl.handle.net/10281/43723.
Full textAbstract:
Recent developments in the complex networks analysis, based largely on
graph theory, have been used to study the brain network organization. The brain is a complex system that can be represented by a graph. A graph is
a mathematical representation which can be useful to study the connectivity of the brain.
Nodes in the brain can be identified dividing its volume in regions of interest and links can be identified calculating a measure of dependence between
pairs of regions whose activation signal, measured by functional magnetic
resonance imaging (fMRI) techniques, represents the strength of the connec-tion between regions.
A graph can be synthesized by the so-called adjacency matrix, which, in its
simplest form, is an undirected, binary, and symmetric matrix, whose en-tries are set to one if a link exists between a pair of brain areas and zero
otherwise. The adjacency matrix is particularly useful because allows the
calculation of several measures which summarize global and local character-istics of functional brain connectivity, such as centrality, e ciency, density
and small worldness property.
In this work, we consider the
global measures, such as the clustering coe cient, the characteristic path
length and the global e ciency, and the local measures, such as centrality
measures and local e ciency, in order to represent global and local dynam-ics and changes between networks. This is achieved by studying with resting
state (rs) fMRI data of healthy subjects and patients with neurodegenerative
diseases.
Furthermore we illustrate an original methodology to construct
the adjacency matrix. Its entries, containing the information about the ex-istence of links, are identified by testing the correlation between the time
series that characterized the dynamic behavior of the nodes. This involves
the problem of multiple comparisons in order to control the error rates. The
method based on the estimation of positive false discovery rate (pFDR)
has been used. A similar measure involving false
negatives (type II errors), called the positive false nondiscovery rate (pFNR)
is then considered, proposing new point and interval estimators for pFNR
and a method for balancing the two types of error. This approach is demonstrated using both simulations and fMRI data, and providing nite sample as
well as large sample results for pFDR and pFNR estimators. Besides a
ranking of the most central nodes in the networks is proposed using q-values,
the pFDR analog of the p-values. The di erences on the inter-regional connectivity between cases and controls are studied.
Finally network models are discussed. In order to gain deeper insights into the complex neurobiological
interaction, exponential random graph models (ERGMs) are applied to assess several network properties simultaneously and to compare case/control brain networks.