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Pages
- Title
- Scalable Network Design and Management with Decentralized Software-defined Networking.
- Creator
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Atwal, Kuldip Singh, Bassiouni, Mostafa, Fu, Xinwen, Zou, Changchun, Deo, Narsingh, University of Central Florida
- Abstract / Description
-
Network softwarization is among the most significant innovations of computer networks in the last few decades. The lack of uniform and programmable interfaces for network management led to the design of OpenFlow protocol for the university campuses and enterprise networks. This breakthrough coupled with other similar efforts led to an emergence of two complementary but independent paradigms called software-defined networking (SDN) and network function virtualization (NFV). As of this writing,...
Show moreNetwork softwarization is among the most significant innovations of computer networks in the last few decades. The lack of uniform and programmable interfaces for network management led to the design of OpenFlow protocol for the university campuses and enterprise networks. This breakthrough coupled with other similar efforts led to an emergence of two complementary but independent paradigms called software-defined networking (SDN) and network function virtualization (NFV). As of this writing, these paradigms are becoming the de-facto norms of wired and wireless networks alike. This dissertation mainly addresses the scalability aspect of SDN for multiple network types. Although centralized control and separation of control and data planes play a pivotal role for ease of network management, these concepts bring in many challenges as well. Scalability is among the most crucial challenges due to the unprecedented growth of computer networks in the past few years. Therefore, we strive to grapple with this problem in diverse networking scenarios and propose novel solutions by harnessing capabilities provided by SDN and other related technologies. Specifically, we present the techniques to deploy SDN at the Internet scale and to extend the concepts of softwarization for mobile access networks and vehicular networks. Multiple optimizations are employed to mitigate latency and other overheads that contribute to achieve performance gains. Additionally, by taking care of sparse connectivity and high mobility, the intrinsic constraints of centralization for wireless ad-hoc networks are addressed in a systematic manner. The state-of-the-art virtualization techniques are coupled with cloud computing methods to exploit the potential of softwarization in general and SDN in particular. Finally, by tapping into the capabilities of machine learning techniques, an SDN-based solution is proposed that inches closer towards the longstanding goal of self-driving networks. Extensive experiments performed on a large-scale testbed corroborates effectiveness of our approaches.
Show less - Date Issued
- 2019
- Identifier
- CFE0007600, ucf:52543
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007600
- Title
- CREATING MODELS OF INTERNET BACKGROUND TRAFFIC SUITABLE FOR USE IN EVALUATING NETWORK INTRUSION DETECTION SYSTEMS.
- Creator
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LUO, SONG, Marin, Gerald, University of Central Florida
- Abstract / Description
-
This dissertation addresses Internet background traffic generation and network intrusion detection. It is organized in two parts. Part one introduces a method to model realistic Internet background traffic and demonstrates how the models are used both in a simulation environment and in a lab environment. Part two introduces two different NID (Network Intrusion Detection) techniques and evaluates them using the modeled background traffic. To demonstrate the approach we modeled five major...
Show moreThis dissertation addresses Internet background traffic generation and network intrusion detection. It is organized in two parts. Part one introduces a method to model realistic Internet background traffic and demonstrates how the models are used both in a simulation environment and in a lab environment. Part two introduces two different NID (Network Intrusion Detection) techniques and evaluates them using the modeled background traffic. To demonstrate the approach we modeled five major application layer protocols: HTTP, FTP, SSH, SMTP and POP3. The model of each protocol includes an empirical probability distribution plus estimates of application-specific parameters. Due to the complexity of the traffic, hybrid distributions (called mixture distributions) were sometimes required. The traffic models are demonstrated in two environments: NS-2 (a simulator) and HONEST (a lab environment). The simulation results are compared against the original captured data sets. Users of HONEST have the option of adding network attacks to the background. The dissertation also introduces two new template-based techniques for network intrusion detection. One is based on a template of autocorrelations of the investigated traffic, while the other uses a template of correlation integrals. Detection experiments have been performed on real traffic and attacks; the results show that the two techniques can achieve high detection probability and low false alarm in certain instances.
Show less - Date Issued
- 2005
- Identifier
- CFE0000852, ucf:46667
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000852
- Title
- CHARACTERIZATION OF CRITICAL NETWORK COMPONENTS OF COUPLED OSCILLATORS.
- Creator
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Holifield, Gregory, A. S. Wu, A. Gonzalez,, University of Central Florida
- Abstract / Description
-
This dissertation analyzes the fundamental limits for the determination of the network structure of loosely coupled oscillators based on observing the behavior of the network, specifically, node synchronization. The determination of the requisite characteristics and underlying behaviors necessary for the application of a theoretical mechanism for determining the underlying network topology in a network of loosely coupled natural oscillators are the desired outcome. To that end, this effort...
Show moreThis dissertation analyzes the fundamental limits for the determination of the network structure of loosely coupled oscillators based on observing the behavior of the network, specifically, node synchronization. The determination of the requisite characteristics and underlying behaviors necessary for the application of a theoretical mechanism for determining the underlying network topology in a network of loosely coupled natural oscillators are the desired outcome. To that end, this effort defines an analytical framework where key components of networks of coupled oscillators are isolated in order to determine the relationships between the various components. The relationship between the number of nodes in a network, the number of connections in the network, the number of connections of a given node, the distribution of the phases of the network, and the resolution of measurement of the components of the network, and system noise is investigated.
Show less - Date Issued
- 2006
- Identifier
- CFE0001452, ucf:47038
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001452
- Title
- DYNAMIC ENTREPRENEURIAL NETWORKS: AN INVESTIGATION OF ENTREPRENEURS, NEW VENTURES AND THEIR NETWORKS.
- Creator
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Sullivan, Diane, Ford, Cameron, University of Central Florida
- Abstract / Description
-
Entrepreneurs need resources to organize new venture offerings into marketplace-acceptable forms. Entrepreneurs use others' assistance via networks to obtain these resources. Research indicates that firms face resource dependencies, that likely change over time, where they must respond to those controlling resources. Although some work has investigated implications of new ventures' networks at one time period, little work has investigated the dynamic nature and associated outcomes of networks...
Show moreEntrepreneurs need resources to organize new venture offerings into marketplace-acceptable forms. Entrepreneurs use others' assistance via networks to obtain these resources. Research indicates that firms face resource dependencies, that likely change over time, where they must respond to those controlling resources. Although some work has investigated implications of new ventures' networks at one time period, little work has investigated the dynamic nature and associated outcomes of networks as they change due to different resource requirements as the venture develops. This research examines the dynamic nature of networks, due different resource requirements over time, and how these changes impact entrepreneurial outcomes via interactions with entrepreneurs' existing networks. In order to account for the dynamic nature of entrepreneurial new ventures and their networks of resource providers, a model is presented that investigates antecedents to subsequent entrepreneurial network characteristics. The model also anticipates changes eminent to the founder as a consequence of interactions with their networks due to experiences associated with the new venture development process. This work relies on network theory integrated with resource dependence theory arguments, work that examines founder attributes as associated with entrepreneurial outcomes and research that investigates the stages of new venture development. Predictions developed from the model were tested in two studies. The first study utilized the Panel Study of Entrepreneurial Dynamics, an existing panel database containing information about nascent entrepreneurs, as its data source to test predictions examining the dynamics of entrepreneurs' networks across two time frames. The second study used a cross-sectional mass mail survey design to investigate all of the model's predictions on a random sample of newly incorporated firms in the state of Florida. The results of the studies provided support for about one third of the predictions and there were a few contrasting findings across studies. Overall, the results of the studies suggest that some conceptualizations presented in the theoretical model should be reevaluated and that the applicability of some constructs when studying firms in the organizing stages of development should be reconsidered.
Show less - Date Issued
- 2006
- Identifier
- CFE0001173, ucf:46863
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001173
- Title
- Emotional Intelligence in Organizational Social Networks.
- Creator
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Hermsdorfer, Andrea, Joseph, Dana, Fritzsche, Barbara, Wang, Wei, University of Central Florida
- Abstract / Description
-
This study examined the role of emotional intelligence in relationships. Drawing on the notion that individuals who are high on emotional intelligence should have more social ties to others and stronger relationships within these ties, this study used social network analysis to specifically examine the extent to which emotional intelligence is positively related to social network centrality. I hypothesized that emotional intelligence would be positively related to centrality in four networks:...
Show moreThis study examined the role of emotional intelligence in relationships. Drawing on the notion that individuals who are high on emotional intelligence should have more social ties to others and stronger relationships within these ties, this study used social network analysis to specifically examine the extent to which emotional intelligence is positively related to social network centrality. I hypothesized that emotional intelligence would be positively related to centrality in four networks: advice, friendship, support, and positive affect presence. The hypotheses were not supported in this study, in spite of this, the incremental validity suggest a relationship between emotional intelligence and network centrality that may show up in future research.
Show less - Date Issued
- 2016
- Identifier
- CFE0006686, ucf:51927
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006686
- Title
- EFFECTS OF ISOLATION ON METAPOPULATIONDYNAMICS IN SMALL-WORLD NETWORKS.
- Creator
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Bernard, Alaina, Jenkins, David, University of Central Florida
- Abstract / Description
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Simulation models are valuable for making predictions that may be tested in natural systems and for understanding observed patterns. The simulation model developed for this thesis evaluates the effects of spatial network architecture, including organism dispersal patterns and isolation of habitats, on metapopulations. Two fields were merged throughout this project: metapopulation biology and small-world network theory. Small-world networks are characterized in their extremes as scale-free or...
Show moreSimulation models are valuable for making predictions that may be tested in natural systems and for understanding observed patterns. The simulation model developed for this thesis evaluates the effects of spatial network architecture, including organism dispersal patterns and isolation of habitats, on metapopulations. Two fields were merged throughout this project: metapopulation biology and small-world network theory. Small-world networks are characterized in their extremes as scale-free or single-scale. These models potentially simulate the networks of habitats and corridors in which metapopulations operate. Small-world network theory has been used to describe systems as diverse as rivers, the world-wide-web, and protein interactions, but has not been used as an experimental treatment for metapopulation dynamics. I tested the effects of growth rate, dispersal pattern, network architecture (scale-free and single-scale), attack type (targeted or random), and attack severity (0, 5, 10, 20, or 40% attacked populations) on metapopulation size and inter-population variation in a simulated system designed to be relevant to conservation biology and ecology. Metapopulation size and inter-population variation changed due to combinations of dispersal pattern, growth rate, and attack severity. Specifically, metapopulations were most affected by a combination of unidirectional dispersal and low growth rate in both metapopulation number and inter-population variation. However, a significant difference between scale-free and single-scale metapopulations was not found due to a low connectivity in the modeled networks as well as limitations of experimental assumptions. However, future studies that alter the model's assumptions could improve understanding of the influence of landscape structure on at-risk metapopulations.
Show less - Date Issued
- 2007
- Identifier
- CFE0001877, ucf:47384
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001877
- Title
- AN INVESTIGATION INTO THE PREDICTORS OF ADOPTION AND UTILIZATION OF INFORMATION-SHARING NETWORKS BY LOCAL LAW ENFORCEMENT IN THREE STATES.
- Creator
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saviak, joe, Martin, Lawrence, University of Central Florida
- Abstract / Description
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ABSTRACT A major change in longstanding police organizational behavior is increasingly evident in the recent emergence of computerized information-sharing networks in public safety. From both theoretical and empirical perspectives, a better understanding of the determinants that can explain and predict the rise and growth of this new and significant development in American policing is needed. A highly limited body of empirical studies has endeavored to validate effective predictors of...
Show moreABSTRACT A major change in longstanding police organizational behavior is increasingly evident in the recent emergence of computerized information-sharing networks in public safety. From both theoretical and empirical perspectives, a better understanding of the determinants that can explain and predict the rise and growth of this new and significant development in American policing is needed. A highly limited body of empirical studies has endeavored to validate effective predictors of adoption and utilization of electronic information-sharing networks by local law enforcement agencies. Utilizing an integrated theoretical framework largely built upon Rogers' diffusion of innovations theory, sixteen hypotheses were tested through logistic regression and multiple regression analyses of survey research data collected from local law enforcement executives in the three states of California, New York, and Georgia. Qualitative research organized and conducted through targeted telephone interviews with twenty law enforcement executives across the three study states and with responses to open ended questions within the study survey instrument aided in the examination of these hypotheses. 66.7% of the cases of agency adoption of information sharing were correctly classified by the predictors within the logistic regression model. Adoption was positively influenced by a chief executive who demonstrated strong leadership and possessed more extensive experience in law enforcement. Adoption was negatively affected by increasing the opportunity to experiment with this innovation and advancing age of the chief executive. Both quantitative and qualitative findings confirmed that law enforcement agencies that exhibited dedicated leadership are more likely to adopt information-sharing networks. 19.4-25.9% of the variation in the outcome variable of adoption was explained by the predictors within the logistic regression model. Utilization was negatively impacted by growing autonomy of police organizations within the network but benefited from innovation attributes such as the acquisition of an advantage in crime fighting capabilities and reduced complexity in employment of the information-sharing network. 9.1% of the variation in utilization of information-sharing networks could be explained by the predictor variables included within the multiple regression model. Qualitative research also cross-validated the positive effect of gaining an advantage over the criminal element as influential to utilization. A greater advantage in preventing and solving crimes, higher levels of inter-organizational trust between police agencies, and enthusiastic executive leadership were found by the qualitative inquiry to enhance both adoption and utilization. Knowing in advance which theoretically informed and empirically validated antecedents can facilitate or impede adoption and utilization of information integration networks could enable policymakers and law enforcement administrators to optimize strategies to attain successful outcomes.
Show less - Date Issued
- 2007
- Identifier
- CFE0001839, ucf:47377
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001839
- Title
- Prediction of survival of early stages lung cancer patients based on ER beta cellular expressions and epidemiological data.
- Creator
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Martinenko, Evgeny, Shivamoggi, Bhimsen, Chow, Lee, Peale, Robert, Brandenburg, John, University of Central Florida
- Abstract / Description
-
We attempted a mathematical model for expected prognosis of lung cancer patients based ona multivariate analysis of the values of ER-interacting proteins (ERbeta) and a membranebound, glycosylated phosphoprotein MUC1), and patients clinical data recorded at the timeof initial surgery. We demonstrate that, even with the limited sample size available to use,combination of clinical and biochemical data (in particular, associated with ERbeta andMUC1) allows to predict survival of lung cancer...
Show moreWe attempted a mathematical model for expected prognosis of lung cancer patients based ona multivariate analysis of the values of ER-interacting proteins (ERbeta) and a membranebound, glycosylated phosphoprotein MUC1), and patients clinical data recorded at the timeof initial surgery. We demonstrate that, even with the limited sample size available to use,combination of clinical and biochemical data (in particular, associated with ERbeta andMUC1) allows to predict survival of lung cancer patients with about 80% accuracy whileprediction on the basis of clinical data only gives about 70% accuracy. The present work canbe viewed as a pilot study on the subject: since results conrm that ER-interacting proteinsindeed inuence lung cancer patients' survival, more data is currently being collected.
Show less - Date Issued
- 2011
- Identifier
- CFE0004134, ucf:49120
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004134
- Title
- Synthetic generators for simulating social networks.
- Creator
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Mohammed Ali, Awrad, Sukthankar, Gita, Wu, Annie, Boloni, Ladislau, University of Central Florida
- Abstract / Description
-
An application area of increasing importance is creating agent-based simulations to model human societies. One component of developing these simulations is the ability to generate realistic human social networks. Online social networking websites, such as Facebook, Google+, and Twitter, have increased in popularity in the last decade. Despite the increase in online social networking tools and the importance of studying human behavior in these networks, collecting data directly from these...
Show moreAn application area of increasing importance is creating agent-based simulations to model human societies. One component of developing these simulations is the ability to generate realistic human social networks. Online social networking websites, such as Facebook, Google+, and Twitter, have increased in popularity in the last decade. Despite the increase in online social networking tools and the importance of studying human behavior in these networks, collecting data directly from these networks is not always feasible due to privacy concerns. Previous work in this area has primarily been limited to 1) network generators that aim to duplicate a small subset of the original network's properties and 2) problem-specific generators for applications such as the evaluation of community detection algorithms.In this thesis, we extended two synthetic network generators to enable them to duplicate the properties of a specific dataset. In the first generator, we consider feature similarity and label homophily among individuals when forming links. The second generator is designed to handle multiplex networks that contain different link types. We evaluate the performance of both generators on existing real-world social network datasets, as well as comparing our methods with a related synthetic network generator. In this thesis, we demonstrate that the proposed synthetic network generators are both time efficient and require only limited parameter optimization.
Show less - Date Issued
- 2014
- Identifier
- CFE0005532, ucf:50300
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005532
- Title
- NETWORK PERFORMANCE MANAGEMENT USING APPLICATION-CENTRIC KEY PERFORMANCE INDICATORS.
- Creator
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McGill, Susan, Shumaker, Randall, University of Central Florida
- Abstract / Description
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The Internet and intranets are viewed as capable of supplying "Anything, Anywhere, Anytime" and e-commerce, e-government, e-community, and military C4I are now deploying many and varied applications to serve their needs. Network management is currently centralized in operations centers. To assure customer satisfaction with the network performance they typically plan, configure and monitor the network devices to insure an excess of bandwidth, that is overprovision. If this proves uneconomical...
Show moreThe Internet and intranets are viewed as capable of supplying "Anything, Anywhere, Anytime" and e-commerce, e-government, e-community, and military C4I are now deploying many and varied applications to serve their needs. Network management is currently centralized in operations centers. To assure customer satisfaction with the network performance they typically plan, configure and monitor the network devices to insure an excess of bandwidth, that is overprovision. If this proves uneconomical or if complex and poorly understood interactions of equipment, protocols and application traffic degrade performance creating customer dissatisfaction, another more application-centric, way of managing the network will be needed. This research investigates a new qualitative class of network performance measures derived from the current quantitative metrics known as quality of service (QOS) parameters. The proposed class of qualitative indicators focuses on utilizing current network performance measures (QOS values) to derive abstract quality of experience (QOE) indicators by application class. These measures may provide a more user or application-centric means of assessing network performance even when some individual QOS parameters approach or exceed specified levels. The mathematics of functional analysis suggests treating QOS performance values as a vector, and, by mapping the degradation of the application performance to a characteristic lp-norm curve, a qualitative QOE value (good/poor) can be calculated for each application class. A similar procedure could calculate a QOE node value (satisfactory/unsatisfactory) to represent the service level of the switch or router for the current mix of application traffic. To demonstrate the utility of this approach a discrete event simulation (DES) test-bed, in the OPNET telecommunications simulation environment, was created modeling the topology and traffic of three semi-autonomous networks connected by a backbone. Scenarios, designed to degrade performance by under-provisioning links or nodes, are run to evaluate QOE for an access network. The application classes and traffic load are held constant. Future research would include refinement of the mathematics, many additional simulations and scenarios varying other independent variables. Finally collaboration with researchers in areas as diverse as human computer interaction (HCI), software engineering, teletraffic engineering, and network management will enhance the concepts modeled.
Show less - Date Issued
- 2007
- Identifier
- CFE0001818, ucf:47371
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001818
- Title
- IMPROVING ROUTING EFFICIENCY, FAIRNESS, DIFFERENTIATED SERVISES AND THROUGHPUT IN OPTICAL NETWORKS.
- Creator
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ZHOU, BIN, Bassiouni, Mostafa, University of Central Florida
- Abstract / Description
-
Wavelength division multiplexed (WDM) optical networks are rapidly becoming the technology of choice in next-generation Internet architectures. This dissertation addresses the important issues of improving four aspects of optical networks, namely, routing efficiency, fairness, differentiated quality of service (QoS) and throughput. A new approach for implementing efficient routing and wavelength assignment in WDM networks is proposed and evaluated. In this approach, the state of a multiple...
Show moreWavelength division multiplexed (WDM) optical networks are rapidly becoming the technology of choice in next-generation Internet architectures. This dissertation addresses the important issues of improving four aspects of optical networks, namely, routing efficiency, fairness, differentiated quality of service (QoS) and throughput. A new approach for implementing efficient routing and wavelength assignment in WDM networks is proposed and evaluated. In this approach, the state of a multiple-fiber link is represented by a compact bitmap computed as the logical union of the bitmaps of the free wavelengths in the fibers of this link. A modified Dijkstra's shortest path algorithm and a wavelength assignment algorithm are developed using fast logical operations on the bitmap representation. In optical burst switched (OBS) networks, the burst dropping probability increases as the number of hops in the lightpath of the burst increases. Two schemes are proposed and evaluated to alleviate this unfairness. The two schemes have simple logic, and alleviate the beat-down unfairness problem without negatively impacting the overall throughput of the system. Two similar schemes to provide differentiated services in OBS networks are introduced. A new scheme to improve the fairness of OBS networks based on burst preemption is presented. The scheme uses carefully designed constraints to avoid excessive wasted channel reservations, reduce cascaded useless preemptions, and maintain healthy throughput levels. A new scheme to improve the throughput of OBS networks based on burst preemption is presented. An analytical model is developed to compute the throughput of the network for the special case when the network has a ring topology and the preemption weight is based solely on burst size. The analytical model is quite accurate and gives results close to those obtained by simulation. Finally, a preemption-based scheme for the concurrent improvement of throughput and burst fairness in OBS networks is proposed and evaluated. The scheme uses a preemption weight consisting of two terms: the first term is a function of the size of the burst and the second term is the product of the hop count times the length of the lightpath of the burst.
Show less - Date Issued
- 2006
- Identifier
- CFE0001019, ucf:46811
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001019
- Title
- SOCIAL NETWORKING AND USERS: THE INTERACTION OF PERSONALITY AND MOTIVATION FOR FACEBOOK POSTING.
- Creator
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Kessler, Theresa, Hancock, Peter, University of Central Florida
- Abstract / Description
-
Facebook is the reigning king of Social Networking Sites (SNSs). Due to Facebook's impact on current culture, researchers have been focused on how it interacts with its members on a variety of issues including well-being, personal identity, personality type, and motivation. While the topics of personality type and motivation have been investigated separately, their possible relationship has not been examined until now. Participants consisted of 415 students from the University of Central...
Show moreFacebook is the reigning king of Social Networking Sites (SNSs). Due to Facebook's impact on current culture, researchers have been focused on how it interacts with its members on a variety of issues including well-being, personal identity, personality type, and motivation. While the topics of personality type and motivation have been investigated separately, their possible relationship has not been examined until now. Participants consisted of 415 students from the University of Central Florida were surveyed with an International Personality Item Pool (IPIP), a Facebook Intensity Survey, and a Facebook Motivation Scale. Results showed that the personality traits of agreeableness, conscientiousness, and emotional stability were positively related to intrinsic and extrinsic motivation to make posts on Facebook, extraversion was found to be related to extrinsic motivation to make posts, and intellect was found to have almost no relationship to motivation. In addition, participants who were higher in the traits of agreeableness, conscientiousness, and emotional stability were more likely to be more intensely involved in Facebook than those who were high in extraversion and intellect. Finally, I found that participants who were more intensely involved in Facebook experienced more motivation to make posts on Facebook.
Show less - Date Issued
- 2013
- Identifier
- CFH0004504, ucf:45213
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004504
- Title
- Algorithms for Community Identification in Complex Networks.
- Creator
-
Vasudevan, Mahadevan, Deo, Narsingh, Hughes, Charles, Guha, Ratan, Chatterjee, Mainak, Zhao, Yue, University of Central Florida
- Abstract / Description
-
Complex networks such as the Internet, the World Wide Web (WWW), and various social and biological networks, are viewed as large, dynamic, random graphs, with properties significantly different from those of the Erd(&)#246;s-R(&)#233;nyi random graphs. In particular, properties such as degree distribution, network distance, transitivity and clustering coefficient of these networks have been empirically shown to diverge from classical random networks. Existence of communities is one such...
Show moreComplex networks such as the Internet, the World Wide Web (WWW), and various social and biological networks, are viewed as large, dynamic, random graphs, with properties significantly different from those of the Erd(&)#246;s-R(&)#233;nyi random graphs. In particular, properties such as degree distribution, network distance, transitivity and clustering coefficient of these networks have been empirically shown to diverge from classical random networks. Existence of communities is one such property inherent to these networks. A community may informally be defined as a locally-dense induced subgraph, of significant size, in a large globally-sparse graph. Recent empirical results reveal communities in networks spanning across different disciplines (-) physics, statistics, sociology, biology, and linguistics. At least two different questions may be posed on the community structure in large networks: (i) Given a network, detect or extract all (i.e., sets of nodes that constitute) communities; and (ii) Given a node in the network, identify the best community that the given node belongs to, if there exists one. Several algorithms have been proposed to solve the former problem, known as Community Discovery. The latter problem, known as Community Identification, has also been studied, but to a much smaller extent. Both these problems have been shown to be NP-complete, and a number of approximate algorithms have been proposed in recent years. A comprehensive taxonomy of the existing community detection algorithms is presented in this work. Global exploration of these complex networks to pull out communities (community discovery) is time and memory consuming. A more confined approach to mine communities in a given network is investigated in this research. Identifying communities does not require the knowledge of the entire graph. Community identification algorithms exist in the literature, but to a smaller extent. The dissertation presents a thorough description and analysis of the existing techniques to identify communities in large networks. Also a novel heuristic for identifying the community to which a given seed node belongs using only its neighborhood information is presented. An improved definition of a community based on the average degree of the induced subgraph is discussed thoroughly and it is compared with the various definitions in the literature. Next, a faster and accurate algorithm to identify communities in complex networks based on maximizing the average degree is described. The divisive nature of the algorithm (as against the existing agglomerative methods) efficiently identifies communities in large complex networks. The performance of the algorithm on several synthetic and real-world complex networks has also been thoroughly investigated.
Show less - Date Issued
- 2012
- Identifier
- CFE0004294, ucf:49463
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004294
- Title
- MITIGATING MISBEHAVIOR IN WIRELESS NETWORKS: A GAME THEORETIC APPROACH.
- Creator
-
Wang, Wenjing, Chatterjee, Mainak, University of Central Florida
- Abstract / Description
-
In a distributed wireless system, multiple network nodes behave cooperatively towards a common goal. Though such assumptions on cooperation are desirable (e.g., controlling the transmit power level, reducing interference for each other, revealing private information, adhering to network policies) for analyzing and modeling, certain nodes belonging to a real-world system have often shown to deviate. These nodes, known as misbehaving nodes, bring more challenges to the design of the wireless...
Show moreIn a distributed wireless system, multiple network nodes behave cooperatively towards a common goal. Though such assumptions on cooperation are desirable (e.g., controlling the transmit power level, reducing interference for each other, revealing private information, adhering to network policies) for analyzing and modeling, certain nodes belonging to a real-world system have often shown to deviate. These nodes, known as misbehaving nodes, bring more challenges to the design of the wireless network because the unreliable channel makes the actions of the nodes hidden from each other. In this dissertation, we analyze two types of misbehavior, namely, selfish noncooperation and malicious attacking. We apply game theoretic techniques to model the interactions among the nodes in the network. First, we consider a homogeneous unreliable channel and analyze the necessary and sufficient conditions to enforce cooperative packet forwarding among a node pair. We formulate an anti-collusion game and derive the conditions that achieve full cooperation when the non-cooperative nodes collude. In addition, we consider multi-hop communication with a heterogeneous channel model. We refine our game model as a hidden action game with imperfect private monitoring. A state machine based strategy is proposed to reach Nash Equilibrium. The strategy attains cooperative packet forwarding with heterogeneous channel and requires only partial and imperfect information. Furthermore, it also enforces cooperation in multi-hop packet forwarding. To tackle the malicious attacks, we use Bayesian game analysis to show the existence of equilibrium in the detection game and argue that it might not be profitable to isolate the malicious nodes upon detection. We propose the concept of "coexistence with malicious nodes" by proving the co-existence equilibrium and derive the conditions that achieve the equilibrium. This research is further accomplished by extensive simulation studies. Simulation results illustrate the properties of the games and the derived equilibria. The results validate our design philosophy and clearly indicate that the proposed game theoretic solutions can be effectively used to enforce cooperation and mitigate attacks.
Show less - Date Issued
- 2010
- Identifier
- CFE0003080, ucf:48294
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003080
- Title
- ON THE APPLICATION OF LOCALITY TO NETWORK INTRUSION DETECTION: WORKING-SET ANALYSIS OF REAL AND SYNTHETIC NETWORK SERVER TRAFFIC.
- Creator
-
Lee, Robert, Lang, Sheau-Dong, University of Central Florida
- Abstract / Description
-
Keeping computer networks safe from attack requires ever-increasing vigilance. Our work on applying locality to network intrusion detection is presented in this dissertation. Network servers that allow connections from both the internal network and the Internet are vulnerable to attack from all sides. Analysis of the behavior of incoming connections for properties of locality can be used to create a normal profile for such network servers. Intrusions can then be detected due to their abnormal...
Show moreKeeping computer networks safe from attack requires ever-increasing vigilance. Our work on applying locality to network intrusion detection is presented in this dissertation. Network servers that allow connections from both the internal network and the Internet are vulnerable to attack from all sides. Analysis of the behavior of incoming connections for properties of locality can be used to create a normal profile for such network servers. Intrusions can then be detected due to their abnormal behavior. Data was collected from a typical network server both under normal conditions and under specific attacks. Experiments show that connections to the server do in fact exhibit locality, and attacks on the server can be detected through their violation of locality. Key to the detection of locality is a data structure called a working-set, which is a kind of cache of certain data related to network connections. Under real network conditions, we have demonstrated that the working-set behaves in a manner consistent with locality. Determining the reasons for this behavior is our next goal. A model that generates synthetic traffic based on actual network traffic allows us to study basic traffic characteristics. Simulation of working-set processing of the synthetic traffic shows that it behaves much like actual traffic. Attacks inserted into a replay of the synthetic traffic produce working-set responses similar to those produced in actual traffic. In the future, our model can be used to further the development of intrusion detection strategies.
Show less - Date Issued
- 2009
- Identifier
- CFE0002718, ucf:48171
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002718
- Title
- Parallel Distributed Discrete Event Simulation Optimization Using Complexity and Deep Learning.
- Creator
-
Cortes, Edwin, Rabelo, Luis, Lee, Gene, Kincaid, John, Elshennawy, Ahmad, University of Central Florida
- Abstract / Description
-
Parallel distributed discrete event simulation (PDDES) is the execution of a discrete event simulation on a tightly or loosely coupled computer system with multiple processors. The discrete-event simulation model is decomposed into several logical processors (LPs) or simulation objects that can be executed concurrently using partitioning types such as spatial and temporal. PDDES is exceedingly important for the reduction of the simulation time, increase of model size, intellectual property...
Show moreParallel distributed discrete event simulation (PDDES) is the execution of a discrete event simulation on a tightly or loosely coupled computer system with multiple processors. The discrete-event simulation model is decomposed into several logical processors (LPs) or simulation objects that can be executed concurrently using partitioning types such as spatial and temporal. PDDES is exceedingly important for the reduction of the simulation time, increase of model size, intellectual property issue mitigation in multi-enterprise simulations, and the sharing of resources.One of the problems with PDDES is the time management to provide flow control over event processing, the process flow, and the coordination of different logical processors to take advantage of parallelism. Time Warp (TW), Breathing Time Buckets (BTB), and Breathing Time Warp (BTW) are three time management schemes studied by this research. For a particular PDDES problem, unfortunately, there is no clear methodology to decide a priori a time management scheme to achieve higher system and simulation performance.This dissertation shows a new approach for selecting the optimal time synchronization technique class that corresponds to a particular parallel distributed anddiscrete simulation with different levels of simulation logic complexity. Simulation complexities such as branching, parallelism, function calls, concurrency, iterations, mathematical computations, messaging frequency, event processing, and number of simulation objects interactions were given a weighted parameter value based on the cognitive weight approach. Deep belief neural networks were then used to perform deep learning from the simulation complexity parameters and their corresponding optimal time synchronization scheme value as measured by speedup performance.
Show less - Date Issued
- 2015
- Identifier
- CFE0006211, ucf:51114
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006211
- Title
- Performance Evaluation of Connectivity and Capacity of Dynamic Spectrum Access Networks.
- Creator
-
Al-tameemi, Osama, Chatterjee, Mainak, Bassiouni, Mostafa, Jha, Sumit, Wei, Lei, Choudhury, Sudipto, University of Central Florida
- Abstract / Description
-
Recent measurements on radio spectrum usage have revealed the abundance of under- utilized bands of spectrum that belong to licensed users. This necessitated the paradigm shift from static to dynamic spectrum access (DSA) where secondary networks utilize unused spectrum holes in the licensed bands without causing interference to the licensed user. However, wide scale deployment of these networks have been hindered due to lack of knowledge of expected performance in realistic environments and...
Show moreRecent measurements on radio spectrum usage have revealed the abundance of under- utilized bands of spectrum that belong to licensed users. This necessitated the paradigm shift from static to dynamic spectrum access (DSA) where secondary networks utilize unused spectrum holes in the licensed bands without causing interference to the licensed user. However, wide scale deployment of these networks have been hindered due to lack of knowledge of expected performance in realistic environments and lack of cost-effective solutions for implementing spectrum database systems. In this dissertation, we address some of the fundamental challenges on how to improve the performance of DSA networks in terms of connectivity and capacity. Apart from showing performance gains via simulation experiments, we designed, implemented, and deployed testbeds that achieve economics of scale. We start by introducing network connectivity models and show that the well-established disk model does not hold true for interference-limited networks. Thus, we characterize connectivity based on signal to interference and noise ratio (SINR) and show that not all the deployed secondary nodes necessarily contribute towards the network's connectivity. We identify such nodes and show that even-though a node might be communication-visible it can still be connectivity-invisible. The invisibility of such nodes is modeled using the concept of Poisson thinning. The connectivity-visible nodes are combined with the coverage shrinkage to develop the concept of effective density which is used to characterize the con- nectivity. Further, we propose three techniques for connectivity maximization. We also show how traditional flooding techniques are not applicable under the SINR model and analyze the underlying causes for that. Moreover, we propose a modified version of probabilistic flooding that uses lower message overhead while accounting for the node outreach and in- terference. Next, we analyze the connectivity of multi-channel distributed networks and show how the invisibility that arises among the secondary nodes results in thinning which we characterize as channel abundance. We also capture the thinning that occurs due to the nodes' interference. We study the effects of interference and channel abundance using Poisson thinning on the formation of a communication link between two nodes and also on the overall connectivity of the secondary network. As for the capacity, we derive the bounds on the maximum achievable capacity of a randomly deployed secondary network with finite number of nodes in the presence of primary users since finding the exact capacity involves solving an optimization problem that shows in-scalability both in time and search space dimensionality. We speed up the optimization by reducing the optimizer's search space. Next, we characterize the QoS that secondary users can expect. We do so by using vector quantization to partition the QoS space into finite number of regions each of which is represented by one QoS index. We argue that any operating condition of the system can be mapped to one of the pre-computed QoS indices using a simple look-up in Olog (N) time thus avoiding any cumbersome computation for QoS evaluation. We implement the QoS space on an 8-bit microcontroller and show how the mathematically intensive operations can be computed in a shorter time. To demonstrate that there could be low cost solutions that scale, we present and implement an architecture that enables dynamic spectrum access for any type of network ranging from IoT to cellular. The three main components of this architecture are the RSSI sensing network, the DSA server, and the service engine. We use the concept of modular design in these components which allows transparency between them, scalability, and ease of maintenance and upgrade in a plug-n-play manner, without requiring any changes to the other components. Moreover, we provide a blueprint on how to use off-the-shelf commercially available software configurable RF chips to build low cost spectrum sensors. Using testbed experiments, we demonstrate the efficiency of the proposed architecture by comparing its performance to that of a legacy system. We show the benefits in terms of resilience to jamming, channel relinquishment on primary arrival, and best channel determination and allocation. We also show the performance gains in terms of frame error rater and spectral efficiency.
Show less - Date Issued
- 2016
- Identifier
- CFE0006063, ucf:50980
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006063
- Title
- Examining multi-level and inter-organizational collaborative response to disasters: The case of Pakistan Floods in 2010.
- Creator
-
Khosa, Sana, Kapucu, Naim, Wan, Thomas, Knox, Claire, Sadri, Houman, University of Central Florida
- Abstract / Description
-
Catastrophic disasters are different than routine disasters and managing them requires the mobilization of inter-organizational, inter-governmental, cross-sectoral and international humanitarian support. The role of the international community through International Non-governmental Organizations (INGOs), and multi-lateral organizations such as the United Nations (UN) becomes imperative when the scale of the disaster is unprecedented and difficult for a country to manage on its own. The...
Show moreCatastrophic disasters are different than routine disasters and managing them requires the mobilization of inter-organizational, inter-governmental, cross-sectoral and international humanitarian support. The role of the international community through International Non-governmental Organizations (INGOs), and multi-lateral organizations such as the United Nations (UN) becomes imperative when the scale of the disaster is unprecedented and difficult for a country to manage on its own. The initial response and relief phase of managing disasters is one in which many agencies with different expertise, capacities, working mandates, resources, skills, working cultures and norms come together to coordinate and collaborate to provide timely response and relief services. Thus, the terrain of managing catastrophic disasters is complex and requires a deeper study to understand and delineate the factors shaping and facilitating collaborative response and relief efforts.This study examines the multi-level and multi-layered collaborative response networks present at the national-international level, provincial and district/local level of disaster response and interactions. In this research the nature and effectiveness of collaboration is being studied through a relevant case study of a catastrophic natural disaster, the 2010 Pakistan Floods. The phase of immediate response is explored primarily through Network Theory perspectives including supportive theoretical perspectives such as Social Capital, Resource Dependency, and Institutional Collective Action Theory perspectives that help to explain collaborative interactions in disaster response networks. This study explores and describes factors that influence (either facilitate or hinder) collaboration is disaster response networks.The key research questions for this study are: What factors facilitate and impede collaborative response to catastrophic disasters at the local, provincial, national and international levels? What are the differences and similarities in response systems at different levels? Additional questions address how leadership support (attributed to government and political leaders and organizations), institutional support (in the form of plans, international appeals of response, and development of relief funds to manage aid), network capacity of different organizations (programmatic and relational), nature of resource dependencies between responding agencies, and structural configurations of response systems impact the collaborative response in disasters.A case study method has been applied in this research. The 2010 Pakistan Floods response network/system is identified through content analysis of various newspapers, situation reports and after-action reports using the Social Network Analysis (SNA) method via UCINET Software 6.1. The actual response network is analyzed and compared with existing national disaster response plans to examine the effectiveness of collaborative response through centrality measures, clique analysis and visual display. This approach is supplemented with semi-structured interviews of key institutional representatives that responded to the 2010 Floods. These organizations and institutions were primarily identified through the networks formulated via SNA.Findings and results from the analysis reflect that the response networks at each level of analysis differ both in structural aspects and also in functional aspects. The nature of the international-national response system is focused on mobilizing donor support and receiving and managing aid, both in-kind and cash. Also a major role at the international and national level is to mobilize the UN cluster approach and focus on broader aims of response such as providing shelter and food to affected areas. Some of the factors identified as facilitating collaborative response were leadership of both national and international leaders, and availability of donor support and funds.At the provincial level of analysis, the Chief Minister of Punjab is playing a central and influential role and is partnering closely with the Armed Forces and local district administration. Interviews conducted of provincial level officials help to support the hypotheses concerning leadership support's influence on collaborative response and also the role of institutional support in the form of creation of plans, and policies that help to mobilize quick funds and resources for relief. At the local level of response, networks are highly influenced by local conditions and local capacities of the district administration. Thus, there are diverse factors impacting each level of collaborative disaster response. All in all, leadership support, institutional support and network structural aspects are important variables that impact the effectiveness of collaborative response.Today policy makers are trying to figure out ways to collaborate successfully across sector boundaries for better and effective service delivery, both in the mundane operational tasks and in uncertain and complex situations such as disasters and catastrophic events. Thus, this research helps in expanding the literature on collaborative public management, collaborative emergency management, and network management. Also the frequency of natural disasters throughout the world demonstrate the need to study and examine factors that contribute to or hinder the effectiveness of inter-organizational response in disasters
Show less - Date Issued
- 2013
- Identifier
- CFE0005361, ucf:50496
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005361
- Title
- Influence of Personal and State Level Variables on Perception of State Emergency Management Network Resilience In 47 States.
- Creator
-
Jennison, Victoria, Wan, Thomas, Zhang, Ning, Ramirez, Bernardo, Kapucu, Naim, University of Central Florida
- Abstract / Description
-
Emergency management coordination in the United States has fallen victim to over a century of strategies to organize, reorganize, consolidate, or decentralize disaster preparedness, planning and response. Regardless of the agency in charge at the federal level, individual citizens have been responsible for their own well-being immediately after any disaster or emergency event for more than 100 years because it takes time to mobilize and deliver aid. The system most often charged with managing...
Show moreEmergency management coordination in the United States has fallen victim to over a century of strategies to organize, reorganize, consolidate, or decentralize disaster preparedness, planning and response. Regardless of the agency in charge at the federal level, individual citizens have been responsible for their own well-being immediately after any disaster or emergency event for more than 100 years because it takes time to mobilize and deliver aid. The system most often charged with managing that mobilization during an emergency event that exceeds the response capacity of local public safety agencies is the state emergency management network. Many entities in a state emergency management network have different responsibilities during disaster states vs. non-disaster states. Regardless of their role and function, entities need to be able to exchange resources and information with each other, often under time, economic, or other constraints during disasters. This resource exchange generates trust, an essential element of a resilient network. Resilient networks suffer fewer negative impacts from disaster related loss and are more likely to retain collective capacity to respond and help communities recover.The purpose of this study is to explore the ability of individual and state level attributes to explain variability in perception of network resilience. One-hundred fifty one state emergency management agency employees were surveyed regarding their perception of 5 constructs of network resilience (rapidity, redundancy, relationships, resourcefulness, and robustness) and individual level attributes. State level indicators from FEMA, NEMA, American Human Development Index, and Social Vulnerability Index were also analyzed. Overall, it was found that the individual attribute of perception of network integrity had the most influence on perception of network resilience, followed by perception of community resilience and state level attributes including disaster experience, state well-being, and number of full time state emergency management agency employees. These findings can improve network resilience by informing state emergency management network development activity. Networks that increase member opportunities to develop relationships of resource and information exchange will increase their resilience. That increased network resilience impacts community resilience because, as Winston Churchill's wise words during World War II reconstruction advise, (")We shape our communities and then they shape us(").?
Show less - Date Issued
- 2015
- Identifier
- CFE0005812, ucf:50040
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005812
- Title
- DESIGN AND IMPLEMENTATION OF WIRELES SENSOR NETWORKS FOR PARKING MANAGEMENT SYSTEM.
- Creator
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Kora, Sudhir, Phillips, Ronald, University of Central Florida
- Abstract / Description
-
The technology of wirelessly networked micro sensors promises to revolutionize the way we interact with the physical environment. A new approach to solve parking-related issues of vehicles in parking lots using wireless sensor networks is presented. This approach enables the implementation of the Parking Management System (PMS®) in public parking lots found in Airports, Commercial Buildings, Universities, etc. The design architecture of the sensor nodes is discussed here. An overall view...
Show moreThe technology of wirelessly networked micro sensors promises to revolutionize the way we interact with the physical environment. A new approach to solve parking-related issues of vehicles in parking lots using wireless sensor networks is presented. This approach enables the implementation of the Parking Management System (PMS®) in public parking lots found in Airports, Commercial Buildings, Universities, etc. The design architecture of the sensor nodes is discussed here. An overall view of the sensor network, which covers the whole of the parking lot, is also summarized. Detailed description of the software architecture that supports the hardware is provided. A sample experiment for detecting the movement of vehicles by placing the sensor nodes allowing vehicles to pass over it is performed. The readings are sent to a local database server, which gives an indication of the actual number of vehicles parked in the building at any time. This application-oriented project also identifies important areas of further work in power management, communication, collaborative signal processing and parking management.
Show less - Date Issued
- 2005
- Identifier
- CFE0000669, ucf:46522
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000669
