Engineering Commons^™

Self-Organization In Cathode Boundary Layer Discharges, Nobuhiko Takano

Electrical & Computer Engineering Theses & Dissertations

Cathode boundary layer (CBL) discharge, which has been developed as a UV light source, operates in a direct current between a planar cathode and a ring-shape anode that are separated by a dielectric with an opening of the same diameter as the anode. The nonthermal CBL discharges operate in a medium pressure range down to 30 Torr, emitting excimer radiation when operated with noble gases. The radiant excimer emittance at 172 nm in xenon reaches 1.7 W/cm², and a maximum excimer efficiency of 6 % has been obtained. The high excimer radiant emittance, in addition to low cost …

Self-Assembly And Characterization Of Germanium Quantum Dots On Silicon By Pulsed Laser Deposition, Mohammed S. Hegazy

Electrical & Computer Engineering Theses & Dissertations

Self-assembled Ge quantum dots (QD) are grown on Si(100)-(2×1) by pulsed laser deposition (PLD). In situ reflection-high energy electron diffraction (RHEED) and post-deposition atomic force microscopy (AFM) are used to study the growth dynamics and morphology of the QDs. Several films of different thicknesses were grown at a substrate temperature of 400°C using a Q-switched Nd:YAG laser (λ = 1064 mu, 40 ns pulse width, 23 J/cm2 fluence, and 10 Hz repetition rate). At low film thicknesses, but clusters that are faceted by different planes, depending on their height, are observed after the completion of the wetting layer. With increasing …

Optimization Methods Of Laser Induced Breakdown Spectroscopy (Libs) And The Self-Absorption Problem, Olodia Ayed Taha Nassef

Electrical & Computer Engineering Theses & Dissertations

Laser Induced Breakdown Spectroscopy (LIBS) is a well-established technique for determining elemental composition. Compared to conventional methods, its ability to analyze solids, liquids, and gases with little or no sample preparation makes it more versatile and ideal for field, multi-element, and in-situ analysis. The method can be certified for analytical applications of interest in environmental monitoring and quality control processes. Previous work has demonstrated that several different experimental parameters (e.g. laser wavelength, repetition rate, interaction geometry, surface conditions) may affect the effective analytical possibilities of the method. Therefore, many studies have been devoted to optimize such parameters in a way …

Detecting Compromised Nodes In Wireless Sensor Networks, Mary Lisa Mathews

Electrical & Computer Engineering Theses & Dissertations

While wireless sensor networks are proving to be a versatile tool, many of the applications in which they are utilized have sensitive data. Therefore, security is crucial in many of these applications. Once a sensor node has been compromised, the security of the network degrades quickly if measures are not taken to deal with this event. There have been many approaches researched to tackle the issue. In this thesis, an anomaly-based intrusion detection protocol is developed to detect compromised nodes in wireless sensor networks.

The proposed protocol is implemented after the sensors are deployed into the environment in which they …

Molecular Dynamics Simulations To Probe Effects Of Ultra-Short, Very-High Voltage Pulses On Cells, Viswanadham Sridhara

Electrical & Computer Engineering Theses & Dissertations

The use of very high electric fields (∼ 100kV/cm or higher) with pulse durations in the nanosecond range (Ultra-short) has been a very recent development in bioelectrics. Traditionally, the electric field effects have mostly been confined to: (a) low field, long-duration pulses, and (b) focused mainly on electroporation studies. Thus, aspects such as possible field-induced DNA damage, calcium release, alterations in neuro-transmitters, or voltage-gating have generally been overlooked.

Ultra-short, high-field pulses open the way to targeted and deliberate apoptotic cell killing (e.g., of tumor cells). Though experimental data is very useful, it usually yields information on macroscopic variables that is …

The Distributed Independent-Platform Event-Driven Simulation Engine Library (Diesel), Reejo Mathew

Electrical & Computer Engineering Theses & Dissertations

The Distributed, Independent-Platform, Event-Driven Simulation Engine Library (DIESEL) is a simulation executive, capable of supporting both sequential and distributed discrete-event simulations. A system level specification is provided along with the expected behavior of each component within DIESEL. This behavioral specification of each component, along with the interconnection and interaction between the different components, provides a complete description of the DIESEL behavioral model. The model provides a considerable amount of freedom for an application developer to partition the simulation model, when building sequential and distributed applications with respect to balancing the number of events generated across different components. It also allows …

Prediction Of Interference Pathloss Inside Commercial Aircraft Using Modulated Fuzzy Logic And Neural Networks, Madiha Jamil Jafri

Electrical & Computer Engineering Theses & Dissertations

Although several modeling techniques have been used to model indoor radio wave propagation and coupling patterns, to date no efficient model exists that calculates indoor-outdoor radio wave propagations on commercial aircraft. Due to the complexity of an aircraft structure, with the additive introduction of creeping wave phenomenon and unknown back-door propagation values from the exterior aircraft antenna to the avionics bay, numerical modeling approaches using Method of Moments (MoM) or Finite Difference Time Domain (FDTD) prove too complex with limitations. This dissertation presents an expert neuro-fuzzy (NF) model for Interference pathloss (IPL) predictions inside an Airbus 320 (A320) airplane, for …

Development Of Fast, Distributed Computational Schemes For Full Body Bio-Models And Their Application To Novel Action Potential Block In Nerves Using Ultra-Short, High Intensity Electric Pulses, Ashutosh Mishra

Electrical & Computer Engineering Theses & Dissertations

An extremely robust and novel scheme for computing three-dimensional, time-dependent potential distributions in full body bio-models is proposed, which, to the best of our knowledge, is the first of its kind. This simulation scheme has been developed to employ distributed computation resources, to achieve a parallelized numerical implementation for enhanced speed and memory capability. The other features of the numerical bio-model included in this dissertation research, are the ability to incorporate multiple electrodes of varying shapes and arbitrary locations. The parallel numerical tool also allows for user defined, current or potential stimuli as the excitation input. Using the available computation …

Neighborhood Defined Feature Selection Strategy For Improved Face Recognition In Different Sensor Modalitie, Satyanadh Gundimada

Electrical & Computer Engineering Theses & Dissertations

A novel feature selection strategy for improved face recognition in images with variations due to illumination conditions, facial expressions, and partial occlusions is presented in this dissertation. A hybrid face recognition system that uses feature maps of phase congruency and modular kernel spaces is developed. Phase congruency provides a measure that is independent of the overall magnitude of a signal, making it invariant to variations in image illumination and contrast. A novel modular kernel spaces approach is developed and implemented on the phase congruency feature maps. Smaller sub-regions from a predefined neighborhood within the phase congruency images of the training …

Modeling And Simulations Of Electrical Breakdown And Thermal Failure In Zinc Oxide And Titanium Dioxide For High-Voltage Dielectric Applications, Guogang Zhao

Electrical & Computer Engineering Theses & Dissertations

The development of transmission lines with higher energy storage capabilities is an important goal for compact pulsed power systems. In this context, ceramic dielectrics are promising candidates from the standpoint of high dielectric constants and breakdown strength. Though such materials look promising, their breakdown response characteristics have not been well studied, nor adequately understood. The electrical response of dielectrics also seems to depend on the internal structure and its granularity. For example, the breakdown strength of nano-crystalline insulators such as titania and zinc oxide have been observed to depend on the internal grain size. In general, the hold-off voltage increases …

Power-Aware Design Methodologies For Fpga-Based Implementation Of Video Processing Systems, Hau Trung Ngo

Electrical & Computer Engineering Theses & Dissertations

The increasing capacity and capabilities of FPGA devices in recent years provide an attractive option for performance-hungry applications in the image and video processing domain. FPGA devices are often used as implementation platforms for image and video processing algorithms for real-time applications due to their programmable structure that can exploit inherent spatial and temporal parallelism. While performance and area remain as two main design criteria, power consumption has become an important design goal especially for mobile devices. Reduction in power consumption can be achieved by reducing the supply voltage, capacitances, clock frequency and switching activities in a circuit. Switching activities …