Engineering Commons^™

Short-Circuit Protection For Low-Voltage Dc Distribution Systems Based On Solid-State Circuit Breakers, Sharthak Munasib

Graduate Theses and Dissertations

Proper short-circuit protection in dc distribution systems has provided an austere challenge to researchers as the development of commercially-viable equipment providing fast operation, coordination and reliability still continues. The objective of this thesis is to analyze issues associated with short-circuit protection of low-voltage dc (LVDC) distribution systems and propose a short-circuit protection methodology based on solid-state circuit breakers (SSCBs) that provides fault-current limiting (FCL). Simulation results for a simplified notional 1-kVdc distribution system, performed in MATLAB/SIMULINKTM, would be presented to illustrate that SSCB solutions based on reverse-blocking integrated gate-commutated thyristors (RB-IGCT) are feasible for low-voltage dc distribution systems but requires …

Applications Of Krylov Subspace And Balanced Truncation Model Order Reduction In Power Systems, Sebastian Emanuel Garrido

Graduate Theses and Dissertations

Dynamic representations of power systems usually result in the order of hundreds or even thousands of buses. Therefore, reduction of these dynamic representations is convenient. Two applications of model order reduction in power systems are discussed in this thesis. First, Krylov subspace-based method is applied to the IEEE-123 Node Test Feeder in the context of distribution-level power systems simulation. Second, a Balanced Truncation-based model reduction is implemented in the 3-Machine 9-Bus system for designing a power system controller in the context of generation- and transmission-level power systems.

First, for the IEEE-123 Node Test Feeder, a two-sided Arnoldi algorithm is proposed …

Channel Estimation Overhead Reduction For Downlink Fdd Massive Mimo Systems, Abderrahmane Mayouche

Graduate Theses and Dissertations

Massive multiple-input multiple-output (MIMO) is the concept of deploying a very large number of antennas at the base stations (BS) of cellular networks. Frequency-division duplexing (FDD) massive MIMO systems in the downlink (DL) suffer significantly from the channel estimation overhead. In this thesis, we propose a minimum mean square error (MMSE)-based channel estimation framework that exploits the spatial correlation between the antennas at the BS to reduce the latter overhead. We investigate how the number of antennas at the BS affects the channel estimation error through analytical and asymptotic analysis. In addition, we derive a lower bound on the spectral …

Reducing Multiple Access Interference In Broadband Multi-User Wireless Networks, Ali Nayef Alqatawneh

Graduate Theses and Dissertations

This dissertation is devoted to developing multiple access interference (MAI) reduction techniques for multi-carrier multi-user wireless communication networks.

In multi-carrier code division multiple access (MC-CDMA) systems, a full multipath diversity can be achieved by transmitting one symbol over multiple orthogonal subcarriers by means of spreading codes. However, in frequency selective fading channels, orthogonality among users can be destroyed leading to MAI. MAI represents the main obstacle to support large number of users in multi-user wireless systems. Consequently, MAI reduction becomes a main challenge when designing multi-carrier multi-user wireless networks. In this dissertation, first, we study MC-CDMA systems with different existing …

Text-Independent Speaker Identification Using Statistical Learning, Alli Ayoola Ojutiku

Graduate Theses and Dissertations

The proliferation of voice-activated devices and systems and over-the-phone bank transactions has made our daily affairs much easier in recent times. The ease that these systems offer also call for a need for them to be fail-safe against impersonators. Due to the sensitive information that might be shred on these systems, it is imperative that security be an utmost concern during the development stages. Vital systems like these should incorporate a functionality of discriminating between the actual speaker and impersonators. That functionality is the focus of this thesis.

Several methods have been proposed to be used to achieve this system …

Distortion-Tolerant Communications With Correlated Information, Ning Sun

Graduate Theses and Dissertations

This dissertation is devoted to the development of distortion-tolerant communication techniques by exploiting the spatial and/or temporal correlation in a broad range of wireless communication systems under various system configurations. Signals observed in wireless communication systems are often correlated in the spatial and/or temporal domains, and the correlation can be used to facilitate system designs and to improve system performance. First, the optimum

node density, i.e., the optimum number of nodes in a unit area, is identified by utilizing the spatial data correlation in the one- and two-dimensional wireless sensor networks (WSNs), under the

constraint of fixed power per unit …

A Solar-Powered And Multi-Tiered Mesh Node For A Portable In Situ Emergency Response System, Adam Matthews

Graduate Theses and Dissertations

The aftermath of a natural disaster is typically characterized by lack of a reliable medium for dissemination of information to survivors. Current state-of-the-art emergency response systems rely on satellite radio-enabled devices, but survivors, unlike first responders, do not have access to such devices. To mitigate this problem, we present PERPETUU a solar-powered portable GIS microserver. The microserver node can be deployed in a disaster scene, and can serve maps to survivors viewable on browsers of off-the-shelf mobile systems. A key innovation in the design of the PERPETUU node is a multi-tiered hardware architecture-the system combines a low-power micro-controller, a medium-power …

Reliability Analysis Of Social Networks, Kellie R. Schneider

Graduate Theses and Dissertations

The primary focus of this dissertation is on the quantification of actor interaction and the dissemination of information through Social networks. Social networks have long been used to model the interactions between people in various Social and professional contexts. These networks allow for the explicit modeling of the complex interrelations between relevant individuals within an organization and the role they play in the decision making process. This dissertation considers Social networks represented as network flow models in which actors have the ability to provide some level of influence over other actors within the network. The models developed incorporate performance metrics …

Design And Analysis Of An Adaptive Asynchronous System Architecture For Energy Efficiency, Brent Michael Hollosi

Graduate Theses and Dissertations

Power has become a critical design parameter for digital CMOS integrated circuits. With performance still garnering much concern, a central idea has emerged: minimizing power consumption while maintaining performance. The use of dynamic voltage scaling (DVS) with parallelism has shown to be an effective way of saving power while maintaining performance. However, the potency of DVS and parallelism in traditional, clocked synchronous systems is limited because of the strict timing requirements such systems must comply with. Delay-insensitive (DI) asynchronous systems have the potential to benefit more from these techniques due to their flexible timing requirements and high modularity. This dissertation …

Energy And Spectral Efficient Wireless Communications, Guoqing Zhou

Graduate Theses and Dissertations

Energy and spectrum are two precious commodities for wireless communications. How to improve the energy and spectrum efficiency has become two critical issues for the designs of wireless communication systems. This dissertation is devoted to the development of energy and spectral efficient wireless communications. The developed techniques can be applied to a wide range of wireless communication systems, such as wireless sensor network (WSN) designed for structure health monitoring (SHM), medium access control (MAC) for multi-user systems, and cooperative spectrum sensing in cognitive radio systems.

First, to improve the energy efficiency in SHM WSN, a new ultra low power (ULP) …

Implementation Of Orthogonal Frequency Division Multiplexing With Fpga, Qi Hao Yang

Graduate Theses and Dissertations

In recent years, there have been dramatic shifts in cellular and telecommunication industries. As smartphones are dominating on the cellphone market, more and more people use these mobile devices to access internet either through third generation network or IEEE802.11 wireless local area network. Orthogonal frequency division multiplexing (OFDM) has been widely used in IEEE802.11 wireless local area network and fourth generation network. This paper will focus on the design and implementation of an Orthogonal Frequency Division Multiplexing system on field-programmable gate array (FPGA). The major components of an OFDM system include a modulator, an N-input inverse Fast Fourier Transform (IFFT), …