Electrical and Electronics Commons^™

Artificial Inhomogeneous Tapered Impedance Sheet Characterization And Applications, Jeffrey P. Massman

Theses and Dissertations

The ability to manipulate a complex impedance sheet about a PEC or general dielectric cylinder of arbitrary diameter to control the overall scattering characteristics at particular angles for shielding or scattering applications is presented. It is shown that with the capability to readily control both the real and imaginary components of a percolated lossy film's effective impedance, specific impedance distributions can be obtained to effectively direct the overall nulls in the bistatic scattering pattern. The exact approach only requires negligible truncation error of the matrix solution and can be applied to cylinders of arbitrary size. This approach relies on general …

Low-Complexity Transmit Diversity Scheme Using Moderate-Sized Signal Constellations, B. K. Khoo, P. Xiao, S. Y. Le Goff, B. S. Sharif, C. C. Tsimenidis

Electrical & Electronic Engineering

In the conventional space-time coding technique [1], nT radio frequency (RF) chains are employed to transmit signals simultaneously from nT transmit antennas. In this Letter, a lowcomplexity transmit diversity scheme with nT = 2 transmit antennas is proposed. The proposed system employs only one RF chain as well as a low-complexity switch for transmission.

Novel Ac Side P&O Maximum Power Transfer Control For Grid Connected Photovoltaic Systems, Mohamed Moin Hanif, Malabika Basu, Kevin Gaughan

Conference papers

Grid connected Photovoltaic inverters can convert PV energy into electricity with very high efficiencies. Power from the PV panels fluctuates depending on various weather conditions. PV inverters usually include a maximum power point tracker (MPPT) to track this varying power, in order to transfer all the available power to the grid efficiently. Control of power transferred to the grid along with the MPPT plays a crucial role in determining the efficiency of a PV system. This paper discusses about the basic power transfer theory between sources (PV and Grid) and focuses on the need of a DC-DC boost circuit, along …

Target Localization In Mimo Radar Systems, Hana Godrich

Dissertations

MIMO (Multiple-Input Multiple-Output) radar systems employ multiple antennas to transmit multiple waveforms and engage in joint processing of the received echoes from the target. MIMO radar has been receiving increasing attention in recent years from researchers, practitioners, and funding agencies. Elements of MIMO radar have the ability to transmit diverse waveforms ranging from independent to fully correlated. MIMO radar offers a new paradigm for signal processing research. In this dissertation, target localization accuracy performance, attainable by the use of MIMO radar systems, configured with multiple transmit and receive sensors, widely distributed over an area, are studied. The Cramer-Rao lower bound …

Service Oriented Networking For Multimedia Applications In Broadband Wireless Networks, Ehsan Haghani Dogaheh

Dissertations

Extensive efforts have been focused on deploying broadband wireless networks. Providing mobile users with high speed network connectivity will let them run various multimedia applications on their wireless devices. In order to successfully deploy and operate broadband wireless networks, it is crucial to design efficient methods for supporting various services and applications in broadband wireless networks. Moreover, the existing "access-oriented" networking solutions are not able to fully address all the issues of supporting various applications with different quality of service requirements. Thus, "service-oriented" networking has been recently proposed and has gained much attention.

This dissertation discusses the challenges and possible …

Cooperative Retransmission Protocols In Fading Channels : Issues, Solutions And Applications, Igor Stanojev

Dissertations

Future wireless systems are expected to extensively rely on cooperation between terminals, mimicking MIMO scenarios when terminal dimensions limit implementation of multiple antenna technology. On this line, cooperative retransmission protocols are considered as particularly promising technology due to their opportunistic and flexible exploitation of both spatial and time diversity. In this dissertation, some of the major issues that hinder the practical implementation of this technology are identified and pertaining solutions are proposed and analyzed. Potentials of cooperative and cooperative retransmission protocols for a practical implementation of dynamic spectrum access paradigm are also recognized and investigated. Detailed contributions follow.

While conventionally …

Adaptive Trust And Reputation System As A Security Service In Group Communications, Pitipatana Sakarindr

Dissertations

Group communications has been facilitating many emerging applications which require packet delivery from one or more sender(s) to multiple receivers. Owing to the multicasting and broadcasting nature, group communications are susceptible to various kinds of attacks. Though a number of proposals have been reported to secure group communications, provisioning security in group communications remains a critical and challenging issue.

This work first presents a survey on recent advances in security requirements and services in group communications in wireless and wired networks, and discusses challenges in designing secure group communications in these networks. Effective security services to secure group communications are …

Generalized Discrete Fourier Transform With Non-Linear Phase : Theory And Design, Handan Agirman-Tosun

Dissertations

Constant modulus transforms like discrete Fourier transform (DFT), Walsh transform, and Gold codes have been successfully used over several decades in various engineering applications, including discrete multi-tone (DMT), orthogonal frequency division multiplexing (OFDM) and code division multiple access (CDMA) communications systems. Among these popular transforms, DFT is a linear phase transform and widely used in multicarrier communications due to its performance and fast algorithms. In this thesis, a theoretical framework for Generalized DFT (GDFT) with nonlinear phase exploiting the phase space is developed. It is shown that GDFT offers sizable correlation improvements over DFT, Walsh, and Gold codes. Brute force …

Advanced Classification Of Ofdm And Mimo Signals With Enhanced Second Order Cyclostationarity Detection, Miao Shi

Dissertations

With the emergence of cognitive radio and the introduction of new modulation techniques such as OFDM and MIMO, the problem of Modulation Classification (MC) becomes more challenging and complicated. In the first part of the thesis, we explore the automatic modulation classification to blindly distinguish OFDM from single carrier signals. We use the fourth order cumulants; an approach which in the past has been also applied to classify single carrier signals. A blind OFDM parameter estimation scheme was then followed, which includes the estimation of number of subcarriers, CP length, timing and frequency offset and the oversampling factor for the …

A Fpga/Dsp Design For Real-Time Fracture Detection Using Low Transient Pulse, Akash Mathur

Theses

This work presents the hardware and software architecture for the detection of fractures and edges in materials. While the detection method is based on the novel concept of Low Transient Pulse (LTP), the overall system implementation is based on two digital microelectronics technologies widely used for signal processing: Digital Signal Processor (DSP) and Field Programmable Gate Array (FPGA). Under the proposed architecture, the DSP carries out the analysis of the received baseband signal at a lower rate and hence can be used for large number of signal channels. The FPGA's master clock runs at a higher frequency (62.5MHz) for the …

Sparse Representation For Audio Noise Removal Using Zero-Zone Quantizers, Neha Mittal

Theses

In zero zone quantization, bins around zero are quantized to a zero value. This kind of quantization can be applied on orthogonal transforms to remove the unwanted or redundant signal. Transforms reveal structures and properties of a signal and hence careful application of a zero zone over the transform coefficients leads to noise removal. In this thesis, such quantizers are applied over Discrete Fourier Transform and Karhunen Loeve Transform coefficients separately, and outputs compared. Further, the localization of the zero zones to certain frequencies leads to better performance in terms of noise removal. PEAQ (Perceptual Evaluation of Audio Quality) scores …

The Size Ellect On The Infrared Spectra Of Condensed Media Under Conditions Of Id, 2d And 3d Dielectric Confinement, Igor I. Shaganov, Tatiana S. Perova, Vasily A. Melnikov, Kevin Berwick

Articles

A general expression for the dielectric loss spectrum of an absorbing composite medium was obtained from a Maxwell-Garnett general equation. This expression was simplified for the cases of one, two and three dimensional dielectric confinement in both ordered and disordered thin layers, rods (wires) and spheres of absorbing medium which are considered as mesoparticles or mesoscopic molecules. This theoretical approach was verified experimentally using high purity organic liquids with strong absorption bands in the infrared range. Three organic liquids, namely benzene, chloroform and carbon disulphide, were measured in various dielectric confinement configurations using Fourier Transform Infrared (FTIR) spectroscopy with a …

Double Quantum Dot Photoluminescence Mediated By Incoherent Reversible Energy Transport, S. Yu Kruchinin, A. V. Federov, A. V. Baranov, T. S. Perova, Kevin Berwick

Articles

We present a theoretical study of the stationary photoluminescence of two, direct-gap, semiconductor nanocrystals, taking into account electronic excitation energy-transfer processes due to electrostatic interaction. The results obtained here allow for the incoherent reversible energy transport that occurs when the intraband relaxation rate in a quantum dot acceptor is comparable to, or less than, the energy-transfer rate. We investigate the secondary emission of two different electronic level schemes that can be realized experimentally, obtain analytical expressions for the luminescence differential cross section, and perform an analysis of its spectrum. It is shown that when excitation is not in resonance with …

The Effects Of Harmonics On Power Quality And Energy Efficiency, Alan Harrison

Other resources

By making our electricity supply more secure, reliable and versatile will mean that we reduce our reliance upon oil, gas and solid fuels, which mostly exist outside of Ireland and the European community. The majority of our fuel is imported and this makes our economy dependent on outside interests and out of our control. Even more importantly as the world’s fossil fuel reserves are running out and electricity demand is ever increasing.

If we make our electricity networks secure and designed to the highest standards we can import and export electrical energy more easily as our demands change, for example …

Live Video Database Management Systems, Rui Peng

Electronic Theses and Dissertations

With the proliferation of inexpensive cameras and the availability of high-speed wired and wireless networks, networks of distributed cameras are becoming an enabling technology for a broad range of interdisciplinary applications in domains such as public safety and security, manufacturing, transportation, and healthcare. Today’s live video processing systems on networks of distributed cameras, however, are designed for specific classes of applications. To provide a generic query processing platform for applications of distributed camera networks, we designed and implemented a new class of general purpose database management systems, the live video database management system (LVDBMS). We view networked video cameras as …

Interactive Music Archive Access System, Martin Gallagher, Mikel Gainza, Derry Fitzgerald, Dan Barry, Matt Cranitch, Eugene Coyle

Conference papers

The goal of the Interactive Music Archive Access System (IMAAS) project was to develop an interactive music archive access system which was capable of allowing an end-user to easily extract rhythmic, melodic and harmonic musical metadata
descriptors from audio, and allow the user to interact with the archive contents in a manner not typically allowed in archive access systems. To this end, the IMAAS system incorporates a range of real-time interaction tools which allow the user to modify the retrieved audio in a number of ways including the ability to isolate individual instruments in stereo mixes, pitch and timescale modification, …

Architectural Support For Improving System Hardware/Software Reliability, Martin Dimitrov

Electronic Theses and Dissertations

It is a great challenge to build reliable computer systems with unreliable hardware and buggy software. On one hand, software bugs account for as much as 40% of system failures and incur high cost, an estimate of $59.5B a year, on the US economy. On the other hand, under the current trends of technology scaling, transient faults (also known as soft errors) in the underlying hardware are predicted to grow at least in proportion to the number of devices being integrated, which further exacerbates the problem of system reliability. We propose several methods to improve system reliability both in terms …

Bit-Rate Aware Reconfigurable Architecture For H.264/Avc Deblocking Filter, Rakan Khraisha

Electronic Theses and Dissertations

In H.264/AVC, DeBlocking Filter (DBF) achieves bit rate savings and it is used to improve visual quality by reducing the presence of blocking artifacts. However, these advantages come at the expense of increasing computational complexity of the DBF due to highly adaptive mode decision and small 4x4 block size. The DBF easily accounts for one third of the computational complexity of the decoder. The computational complexity required for various target applications from mobile to high definition video applications varies significantly. Therefore, it becomes apparent to design efficient architecture to adapt to different requirements. In this work, we exploit the scalability …

Electron-Electron Scattering In A Double Quantum Dot: Effective Mass Approach, S. Yu. Kruchinin, A. V. Federov, A. V. Baranov, Tatiana Perova, Kevin Berwick

Articles

We present a theoretical description of the first-order scattering of interacting electrons and holes in a double quantum dot. Assuming infinitely high walls, strong confinement, and a two-band approximation, we derive general expressions for the two-particle matrix elements of the screened Coulomb potential. We also determine the selection rules for different scattering channels and consider special cases where the corresponding matrix elements can be represented by simple analytical expressions. Numerical calculations of the matrix elements and an analysis of their dependence on the geometrical and material parameters of the double quantum dot have also been performed.

The Relevance Of Time-To-Digital Converters To Small Platform Direction Finding Systems, Paul Jeffrey Nelson

Electronic Theses and Dissertations

This thesis explores a Time-Difference-of-Arrival (TDOA) approach to radio direction finding, utilizing picosecond-resolution Time-to-Digital Converters (TDCs). By measuring the relative time of arrival of a pulsed RF signal impinging on an antenna array, direction of arrival (DOA) can be ascertained. This technology enables versatile DOA calculation on platforms only several meters in length, and offers various size, weight, power, and cost advantages when compared to present DF technologies. A short baseline S-band TDOA DF system utilizing TDCs is designed, fabricated, and tested in a laboratory environment. This research suggests that such a DF system based on TDCs provides sufficient accuracy …