Embedding of virtual network (VN) requests on top of a shared physical network poses an intriguing combination of theoretical and practical challenges. Two major problems with the state-of-the-art VN embedding algorithms are their indifference to the underlying substrate topology and their lack of re-optimization mechanisms for already embedded VN requests. We argue that topology-aware embedding together with re-optimization mechanisms can improve the performance of the previous VN embedding algorithms in terms of acceptance ratio and load balancing. The major contributions of this thesis are twofold: (1) we present a mechanism to differentiate among resources based on their importance in the substrate topology, and (2) we propose a set of algorithms for re-optimizing and re-embedding initially-rejected VN requests after fixing their bottleneck requirements. Through extensive simulations, we show that not only our techniques improve the acceptance ratio, but they also provide the added benefit of balancing load better than previous proposals. The metrics we use to validate our techniques are improvement in acceptance ratio, revenue-cost ratio, incurred cost, and distribution of utilization.

Conguring a network system to operate at optimal levels of performance re-quires a comprehensive understanding of the eects of a variety of system parameterson crucial metrics like connectivity and resilience to network attacks. Traditionally,omni-directional antennas have been used for communication in wireless sensor net-works. In this thesis, a hybrid communication model is presented where-in, nodes ina network are capable of both omni-directional and uni-directional communication.The eect of such a model on performance in randomly deployed wireless sensor net-works is studied, specically looking at the eect of a variety of network parameterson network performance.The work in this thesis demonstrates that, when the hybrid communication modelis employed, the probability of 100% connectivity improves by almost 90% and thatof k-connectivity improves by almost 80% even at low node densities when comparedto the traditional omni-directional model. In terms of network security, it was foundthat the hybrid approach improves network resilience to the collision attack by almost85% and the cost of launching a successful network partition attack was increased byas high as 600%. The gains in connectivity and resilience were found to improve withincreasing node densities and decreasing antenna beamwidths.

With rapidly development of wireless network technology in the past few years, hand-held devices can connect to Internet everywhere conveniently by equipped with wireless card. IEEE 802.11 defined two types of wireless networks: infrastructure networks and ad hoc networks. Since ad hoc networks are a kind of networks without access points, efficient routing is an important issue for these networks. A more efficient routing approach involves dividing the network into several clusters by using a clustering algorithm. The purpose of this paper is to investigate a hybrid cluster routing algorithm in mobile ad hoc networks. This investigation proposed a double-manager K-hop clustering algorithm based on the link evaluation. This algorithm not only can elect a more suitable node as the cluster head but also can reduce the overhead of the managers. Furthermore, this study devised maintenance and backup mechanisms to stabilize network performance in the face of network topology changes. The simulation results demonstrate that our proposed algorithm outperforms other clustering algorithm in terms of number of clusters, routing overhead of managers and cluster stability.

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In the organism, genes don¡¦t work independently. The interaction of genes shows how the functional task affects. Observing the interaction can understand what the relation between genes and how the disease caused. Several methods are adopted to observe the interaction to construct gene relation network. Existing algorithms to construct gene relation network can be classified into two types. One is to use literatures to extract the relation between genes. The other is to construct the network, but the relations between genes are not described. In this thesis, we proposed a hybrid method based on these two methods. Bayesian network is applied to the microarray gene expression data to construct gene network. Text mining is used to extract the gene relations from the documents database. The proposed algorithm integrates gene network and gene relations into gene relation networks. Experimental results show that the related genes are connected in the network. Besides, the relations are also marked on the links of the related genes.

The objectives of this dissertation are to examine how expatriates¡¦ social network affect the ability of access information/resource and knowing- whom capital on their career advancement, as well as the effects of perceived organizational support correlate to host and home social network. Specially, this research investigates dual sources (host and home office) of expatriates¡¦ network in order to understand the impact on the network abilities and extent. Through confirmed factor analysis of pretest data, measurements were refined and the questionnaire used for the study was developed. For the study, 267 surveys were used for the data analyses. Structural equation modeling in LISREL 8.8 was employed to analyze the relationships among the latent constructs. The findings from the study revealed significant relationships between 1) expatriates¡¦ social network of host office and access information & resource, 2) social network of host office and knowing whom capital, 3) expatriates¡¦ social network of home office and access information & resource, 4) access information & resource and career advancement, and knowing whom capital and career advancement. This study contribute theoretically to the expatriates dual social network literature by clarifying the relationships among host social network, home social network, social network abilities and career advancement, while the previous studies focus on expatriates host country context. This research findings pointed out the expatriates not re-establish a personal network in the host environment but still keep contact with his/her home social network. The expatriates¡¦ host social network has direct and strong effect on access to information/resources and knowing-whom capital. And the expatriates¡¦ home social network also has positive impact on access to information/resources. This empirical model also provides future research with a new angle of view over expatriates social network and career advancement.

We live in a post-PC era with mobile devices on the rise. We can witness a growing number of applications that utilize the mobility of such devices to create applications that make our lives more efficient and connected. In the United States alone, millions of Americans play sports each year starting from middle school through college. With social media on the rise, there is a need for an application that takes advantage of the technologies incorporated in mobile devices with the ability to connect athletes in an area to one another. There is currently a lack of a social network application in the sports category of the Apple App Store. Therefore, this report describes how an iOS mobile application for a sports social network is designed, developed, and deployed. Specifically, we will explore in depth the iOS framework, user stories and requirements, the design and development of the client and backend application, and the tests and results. / text

The recent years have observed a tremendous shift from the technology-centric assessment to the user-centric assessment of network services. Consequently, measurement and modelling of Quality of Experience (QoE) attracted many contributions from researchers and practitioners. Generally, QoE is assessed via active and passive measurements. While the former usually allows QoE assessment on the test traffic, the latter opens avenues for continuous QoE assessment on the real traffic generated by the users. This thesis contributes towards passive assessment of QoE. This thesis document begins with a background on the fundamentals of network management and objective QoE assessment. It extends the discussion further to the QoE-centric monitoring and management of network, complimented by the details about QoE estimator agent developed within the Celtic project QuEEN (Quality of Experience Estimators in Network). The discussion on findings starts with results from subjective tests to understand the relationship between waiting times and user subjective feedback over time. These results strengthen the understanding of timescales on which users react, as well as, the effect of user memory on QoE. The findings show that QoE drops significantly when the user faces recurring waiting times of 0.5 s to 4 s durations in case of video streaming and web browsing services. With recurring network disturbances within every 8 s – 16 s time intervals, the user tolerance to waiting times decreases constantly, showing the sign of user memory of recent disturbances. Subsequently, this document introduces and evaluates a passive wavelet-based QoE monitoring method. The method detects timescales on which transient outages occur frequently. A study presents results from qualitative measurements, showing the ability of wavelet to differentiate on-fly between “Good” and “Bad” traffic streams. In sequel, a quantitative study systematically evaluates wavelet-based metrics. Subsequently, the subjective evaluation and wavelet analysis of 5 – 6 minutes long video streaming sessions on mobile networks show that wavelet-based metrics is indeed useful for passive monitoring of QoE issues. Finally, this thesis investigates a method for passive monitoring of user reactions to degrading network performance. The method is based on the TCP termination flags. With a systematic evaluation in a test environment, the results characterise termination of data transfers in case of different user actions in the web browser.

ITC/USA 2012 Conference Proceedings / The Forty-Eighth Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2012 / Town and Country Resort & Convention Center, San Diego, California / The iNET program uses network technology and infrastructure to enhance traditional telemetry systems. The program's components were designed with an eye to existing and emerging technology and infrastructure, requiring the program to gather data about these systems. The methods used in this design effort can be used to characterize existing network infrastructure to determine what upgrades and changes are necessary to deploy a TmNS. This paper describes the methods used for characterizing a range network infrastructure and explores network capacity and policy issues effecting a TmNS deployment. This effort includes making estimates and taking measurements of network capacity, surveying and analyzing network routing/management policies, and proposes a system for evaluating networks for future TmNS deployments.

published_or_final_version / abstract / toc / Electrical and Electronic Engineering / Master / Master of Philosophy