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Full-Text Articles in Computer Engineering

Sequence Design Via Semidefinite Programming Relaxation And Randomized Projection, Dian Mo Jan 2019

Sequence Design Via Semidefinite Programming Relaxation And Randomized Projection, Dian Mo

Doctoral Dissertations

Wideband is a booming technology in the field of wireless communications. The receivers in wideband communication systems are expected to cover a very wide spectrum and adaptively extract the parts of interest. The literature has focused on mixing the input spectrum to baseband using a pseudorandom sequence modulation and recovering the received signals from linearly independent measurements by parallel branches to mitigate the pressures from required extreme high sampling frequency. However, a pseudorandom sequence provides no rejection for the strong interferers received together with weak signals from distant sources. The interferers cause significant distortion due to the nonlinearity of the ...


Inference In Networking Systems With Designed Measurements, Chang Liu Jan 2017

Inference In Networking Systems With Designed Measurements, Chang Liu

Doctoral Dissertations

Networking systems consist of network infrastructures and the end-hosts have been essential in supporting our daily communication, delivering huge amount of content and large number of services, and providing large scale distributed computing. To monitor and optimize the performance of such networking systems, or to provide flexible functionalities for the applications running on top of them, it is important to know the internal metrics of the networking systems such as link loss rates or path delays. The internal metrics are often not directly available due to the scale and complexity of the networking systems. This motivates the techniques of inference ...


Topology Design And Delay Control For Communication Networks In Smart Grid, Xiaodong Wang Aug 2016

Topology Design And Delay Control For Communication Networks In Smart Grid, Xiaodong Wang

Doctoral Dissertations

Stability is a critical concern in the design and maintenance of power systems. Different approaches have been proposed for the analysis of power grid stability in various scenarios depending on small or large perturbations and the speed of the phenomenon of interest. In this work, we consider the power grid as a group of flocking birds, as synchronization is the key issue in both contexts. The framework of partial difference equation (PdE) is used to analyze the system stability, when designing the communication network of the power grid network for conveying measurements between different power stations. Both the cases where ...


Data Security And Privacy In Smart Grid, Yue Tong Aug 2015

Data Security And Privacy In Smart Grid, Yue Tong

Doctoral Dissertations

This dissertation explores novel data security and privacy problems in the emerging smart grid.

The need for data security and privacy spans the whole life cycle of the data in the smart grid, across the phases of data acquisition, local processing and archiving, collaborative processing, and finally sharing and archiving. The first two phases happen in the private domains of an individual utility company, where data are collected from the power system and processed at the local facilities. When data are being acquired and processed in the private domain, data security is the most critical concern. The key question is ...


Energy-Efficient Content Delivery Networks, Vimal Mathew Jan 2015

Energy-Efficient Content Delivery Networks, Vimal Mathew

Doctoral Dissertations

Internet-scale distributed systems such as content delivery networks (CDNs) operate hundreds of thousands of servers deployed in thousands of data center locations around the globe. Since the energy costs of operating such a large IT infrastructure are a significant fraction of the total operating costs, we argue for redesigning them to incorporate energy optimization as a first-order principle. We focus on CDNs and demonstrate techniques to save energy while meeting client-perceived service level agreements (SLAs) and minimizing impact on hardware reliability.

Servers deployed at individual data centers can be switched off at low load to save energy. We show that ...


Asymptotic Analysis Of Random Wireless Networks: Broadcasting, Secrecy, And Hybrid Networks, Cagatay Capar Sep 2014

Asymptotic Analysis Of Random Wireless Networks: Broadcasting, Secrecy, And Hybrid Networks, Cagatay Capar

Doctoral Dissertations

This thesis work is concerned with communication in large random wireless ad hoc networks. We mathematically model the wireless network as a collection of randomly located nodes, and explore how its performance scales as the network size increases. In particular, we study three important properties: broadcasting ability, rate of information exchange, and secret communication capability. In addition, we study connectivity properties of large random graphs in a more general context, where the graph does not necessarily represent a wireless communication network.

Broadcasting, i.e., delivering a message from a single node to the entire network in a wireless ad hoc ...


Barrier Coverage In Wireless Sensor Networks, Zhibo Wang Aug 2014

Barrier Coverage In Wireless Sensor Networks, Zhibo Wang

Doctoral Dissertations

Barrier coverage is a critical issue in wireless sensor networks (WSNs) for security applications, which aims to detect intruders attempting to penetrate protected areas. However, it is difficult to achieve desired barrier coverage after initial random deployment of sensors because their locations cannot be controlled or predicted. In this dissertation, we explore how to leverage the mobility capacity of mobile sensors to improve the quality of barrier coverage.

We first study the 1-barrier coverage formation problem in heterogeneous sensor networks and explore how to efficiently use different types of mobile sensors to form a barrier with pre-deployed different types of ...


Interpreting, Stephanie Jo Kent May 2014

Interpreting, Stephanie Jo Kent

Doctoral Dissertations

What do community interpreting for the Deaf in western societies, conference interpreting for the European Parliament, and language brokering in international management have in common? Academic research and professional training have historically emphasized the linguistic and cognitive challenges of interpreting, neglecting or ignoring the social aspects that structure communication. All forms of interpreting are inherently social; they involve relationships among at least three people and two languages. The contexts explored here, American Sign Language/English interpreting and spoken language interpreting within the European Parliament, show that simultaneous interpreting involves attitudes, norms and values about intercultural communication that overemphasize information and ...


Achieving Energy Efficiency On Networking Systems With Optimization Algorithms And Compressed Data Structures, Yanjun Yao May 2014

Achieving Energy Efficiency On Networking Systems With Optimization Algorithms And Compressed Data Structures, Yanjun Yao

Doctoral Dissertations

To cope with the increasing quantity, capacity and energy consumption of transmission and routing equipment in the Internet, energy efficiency of communication networks has attracted more and more attention from researchers around the world. In this dissertation, we proposed three methodologies to achieve energy efficiency on networking devices: the NP-complete problems and heuristics, the compressed data structures, and the combination of the first two methods.

We first consider the problem of achieving energy efficiency in Data Center Networks (DCN). We generalize the energy efficiency networking problem in data centers as optimal flow assignment problems, which is NP-complete, and then propose ...


Collaborative Solutions To Visual Sensor Networks, Mahmut Karakaya Aug 2011

Collaborative Solutions To Visual Sensor Networks, Mahmut Karakaya

Doctoral Dissertations

Visual sensor networks (VSNs) merge computer vision, image processing and wireless sensor network disciplines to solve problems in multi-camera applications in large surveillance areas. Although potentially powerful, VSNs also present unique challenges that could hinder their practical deployment because of the unique camera features including the extremely higher data rate, the directional sensing characteristics, and the existence of visual occlusions.

In this dissertation, we first present a collaborative approach for target localization in VSNs. Traditionally; the problem is solved by localizing targets at the intersections of the back-projected 2D cones of each target. However, the existence of visual occlusions among ...