Digital Commons Network^™

A Comparison Of Linear And Nonlinear Statcom Control For Power Quality Enhancement, Atousa Yazdani, Mariesa Crow, Jianjun Guo

Electrical and Computer Engineering Faculty Research & Creative Works

This paper introduces a multilevel STATCOM for electric arc furnace power quality enhancement. An eleven level cascaded multilevel converter is used to alleviate the impacts of an unbalanced arc furnace load. The STATCOM provides a power electronic-based means of embedded control for reactive power support.

Integer Ratio Logarithm Based Edge Detection For Runway Hazard Detection, Sri Satya Vardhan Gogineni

Electrical & Computer Engineering Theses & Dissertations

As air traffic is growing in leaps and bounds every day, flying safe has been a major concern in day to day life. Aviation safety is always dependent on the performance of the pilot and air traffic controllers. The very involvement of human discretion introduces judgment as a component of a safe takeoff and landing. A convenient and immediate alternative would be the use of technology to alleviate the problem. Several algorithms have been developed to solve this problem. However, most computer vision algorithms leave the task of interpreting the end data unaddressed. Juggling the myriad tasks during landing and …

Image Processing Technique For Runway Segmentation Using Color Spaces, Naresh Reddy Reddy

Electrical & Computer Engineering Theses & Dissertations

Aircrafts of the future now face the challenge of growing demand for safety which will require a more significant level of pilot assistance than is available today. During an approach to the airport runway, an algorithm that continuously segments the runway from the rest of the background with very little human intervention is very useful for both enhancing the landing safety and reducing the pilot's work load. This thesis presents a novel method for segmenting airport runways on a clear day and in poor visibility conditions using the color space components. In this thesis, collages were formed for both runway …

Detecting Portable Electronic Devices Onboard Commercial Aircraft, Randy Woods

Electrical & Computer Engineering Theses & Dissertations

The need to detect unauthorized usage of intentionally transmitting portable electronic devices (PEDs) onboard commercial aircraft is growing while still allowing passengers to use selected unintentionally transmitting devices, such as laptop computers and CD players, during non-critical stages of flight. This thesis presents the development and testing of an installed system for detecting PEDs over multiple frequency bands. Additionally, the advantages of a fixed versus mobile system are discussed.

Data is presented to cover the frequency range of 20 MHz to 6.5 GHz with special attention given to the cellular and PCS telephone bands, Bluetooth, and the family radio service …

Multivariable Flight Control Design Tool Incorporating Gain And Phase Root Locus, Yong Ki Yoon

Mechanical & Aerospace Engineering Theses & Dissertations

A challenging problem in flight control system design for highly maneuverable aircraft is the coordinated control of the lateral-directional axes. Design goals are based on desired flying qualities giving an indication of whether the response to pilot inputs will be acceptable. Satisfying these closed-loop design objectives employing a computerized flight control system requires multiple feedback and crossfeed paths which operate in a well coordinated fashion. Contemporary control design tools, which close all loops simultaneously, have addressed this problem for several decades. Concerns associated with these strategies are the complicated mathematical relationships between the designer inputs and resulting closed-loop properties, and …

Object Detection In Poor Visibility Conditions Using Image Segmentation, Triveni Vuppalapati

Electrical & Computer Engineering Theses & Dissertations

It can be dangerous for a pilot to attempt to land an aircraft safely in poor visibility conditions such as rain, fog, haze, snow and low light, but external imagery of a runway can be enhanced to provide increased situational awareness. Objects that are detected in a scene may or may not be a hazard, so interpretation is left to the pilot. In order to detect whether an object is a hazard to safe landing, it is necessary to determine whether the object is on the runway. For this purpose, two image segmentation algorithms: histogram based d-peak algorithm and local …

Modeling Broadband Ocean Acoustic Transmissions With Time-Varying Sea Surfaces, Martin Siderius, Michael B. Porter

Electrical and Computer Engineering Faculty Publications and Presentations

Solutions to ocean acoustic scattering problems are often formulated in the frequency domain, which implies that the surface is "frozen" in time. This may be reasonable for short duration signals but breaks down if the surface changes appreciably over the transmission time. Frequency domain solutions are also impractical for source-receiver ranges and frequency bands typical for applications such as acoustic communications (e.g. hundreds to thousands of meters, 1-50 kHz band). In addition, a driving factor in the performance of certain acoustic systems is the Doppler spread, which is often introduced from sea-surface movement. The time-varying nature of the sea surface …

A Satisficing Approach To Aircraft Conflict Resolution, Wynn C. Stirling, James K. Archibald, Nicholas A. Jepsen, Richard L. Frost, Jared C. Hill

Faculty Publications

Future generations of air traffic management systems may give appropriately equipped aircraft the freedom to change flight paths in real time. This would require a conflict avoidance and resolution scheme that is both decentralized and cooperative. We describe a multiagent solution to aircraft conflict resolution based on satisficing game theory. A key feature of the theory is that satisficing decision makers form their preferences by taking into consideration the preferences of others, unlike conventional game theory that models agents that maximize self-interest metrics. This makes possible situational altruism, a sophisticated form of unselfish behavior in which the preferences of another …

Image Pre-Processing Techniques For Hazard Detection In Poor Visibility Conditions, Girish Singh Rajput

Electrical & Computer Engineering Theses & Dissertations

Runway incursion is a persistent problem that has resulted in some of the most devastating accidents in aviation history. With ever increasing air traffic and more passengers, runway safety is of utmost priority to the Federal Aviation Administration (FAA) and other agencies concerned with aviation. As the issue of aviation safety becomes increasingly important, developing a consistent application that detects runway incursions in various visibility conditions is crucial for the aviation industry. This thesis presents a novel method for detecting runway hazards in poor visibility conditions using image processing techniques. The first step is to obtain images of a runway …

Live Wire Segmentation Tool For Osteophyte Detection In Lumbar Spine X-Ray Images, Santosh Seetharaman, R. Joe Stanley, Soumya De, Sameer Antani, L. Rodney Long, George R. Thoma

Electrical and Computer Engineering Faculty Research & Creative Works

Computer-assisted vertebra segmentation in x-ray images is a challenging problem. Inter-subject variability and the generally poor contrast of digitized radiograph images contribute to the segmentation difficulty. In this paper, a semi-automated live wire approach is investigated for vertebrae segmentation. The live wire approach integrates initially selected user points with dynamic programming to generate a closed vertebra boundary. In order to assess the degree to which vertebra features are conserved using the live wire technique, convex hull-based features to characterize anterior osteophytes in lumbar vertebrae are determined for live wire and manually segmented vertebrae. Anterior osteophyte discrimination was performed over 405 …

Robust Edge-Detection Algorithm For Runway Edge Detection, Swathi Tandra

Electrical & Computer Engineering Theses & Dissertations

Fog and other such weather conditions hamper the visibility of runway surfaces and any obstacles present on the runway, creating a situation where a pilot may not be able to safely land the aircraft. Assisting the pilot to land the aircraft safely in such conditions is an active area of research. A new method is being investigated that combines non-linear image enhancement with classification of runway edges to detect objects on the runway. The image is segmented into runway and non-runway regions, and objects that are found in the runway regions are deemed to constitute potential hazards. For runway edge …

Congestion Mitigation In Wireless Sensor Networks Using Single-Hop Backpressure Algorithm, Vijay Shekar Mangilipalli Gangu Sham

Electrical & Computer Engineering Theses & Dissertations

Wireless sensor networks consist of a group of small components with limited resources allocated to sense the environment and transmit data to the user or interpreter. This concept is technically evolved from Sensors that are basically used to sense the environment around and collect data based on the sensing application incorporated in them. An extension to functionality of the sensors leads to the concept of sensor networks, where, in addition to gathering information at individual sensors, the data is processed and transmitted to a central station or Base station. This concept of transmitting the information from one node to the …

Multiple Reference Frame-Based Control Of Three-Phase Pwm Boost Rectifiers Under Unbalanced And Distorted Input Conditions, Peng Xiao, Keith Corzine, Ganesh K. Venayagamoorthy

Electrical and Computer Engineering Faculty Research & Creative Works

Many control algorithms and circuits for three-phase pulse width modulation active rectifiers have been proposed in the past decades. In most of the research, it is often assumed that the input voltages are balanced or contain only fundamental frequency components. In this paper, a selective harmonic compensation method is proposed based on an improved multiple reference frame algorithm, which decouples signals of different frequencies before reference frame transformation. This technique eliminates interactions between the fundamental-frequency positive-sequence components and harmonic and/or negative-sequence components in the input currents, so that fast and accurate regulation of harmonic and unbalanced currents can be achieved. …

Improving The Availability Of Manufacturability Information Through Decentralization Of Process Planning, Eliab Opiyo

Tanzania Journal of Engineering and Technology (TJET)

Process planning is part of the general product development and production process that usually follows design and precedes manufacturing. Manufacturability and process planning information in general play central role in many product development and production activities, including paradoxically, conceptual and detail design - the activities that take place before process planning. The need of conducting some of the process planning activities formally before or during design is thus rather obvious. One of the main research issues is therefore the identification of the process planning activities that can be performed before the traditional process planning phase and handling of the process …

Channel-Access And Routing Protocols To Utilize Multiple Heterogeneous Channels For Ad Hoc Networks, Crystal Jackson

All Theses

In this thesis, we consider a multi-channel ad hoc network employing frequency-agile radios that utilize direct-sequence spread-spectrum signaling. Two of the key distributed protocols for this type of network control channel access and routing. The channel-access protocol is responsible for controlling access to the channels available to the terminals in the network, and the routing protocol determines how packets are forwarded among the terminals in the network. To achieve reliable and efficient network performance, these protocols should cooperate with one another and take advantage of the multiple channels available to the network.
In this thesis, we investigate a number of …

The Electrical Characterization Of Tantalum Capacitors As Mis Devices, Brian Holman

All Theses

Electrical characteristics of a new class of tantalum capacitor are presented. Specifically, this type of tantalum capacitor is manufactured by KEMET Electronics Corporation and utilizes Poly(3,4-ethylenedioxythiolphene) (PEDOT) as the cathode material. There are two capacitor varieties based on the polymerization method used for the PEDOT. One uses In-Situ polymerization, and the other uses Pre-Polymerization. Existing polymer Ta capacitors use In-Situ polymerization while Pre-Polymerization is a new technique of cathode application. We investigated both types of devices to determine what, if any, performance benefits were gained by using Pre-Poly.
In a basic form Ta capacitors consist of a Ta anode, Ta2O5 …

Optimize Neural Network Controller Design Using Genetic Algorithm, Ariel Kopel, Xiao-Hua Yu

Electrical Engineering

The size of a neural network must be predetermined before it can be trained for any application. Choosing the correct size of a neural network can increase its speed of response and thus improve the performance of the overall system. In this paper, a genetic algorithm is employed to find the optimal number of connections of a neural network controller which is used to regulate a class of DC power supplies. Satisfactory computer simulation results are obtained.

Financial Engineering For Energy System Capital Budgeting, Chin-Chuen Teoh

Dissertations and Theses

The United State energy industry is experiencing a major paradigm shift. This conventional vertically integrated energy industry is gradually transformed to a competitive market environment—a deregulated energy market. The market and regulatory frameworks are expected to continue to evolve in the future. Market participants are emphasizing more on profit maximization as returns on investment are no longer guaranteed. Therefore, risk management and capital budgeting play critical roles in energy system planning. Planning always involves uncertainties. When there are uncertainties, there are risks involve. This dissertation concentrates on the application of Real Options Analysis, ROA, especially lattice method, to energy system …

Enhancement Of Shg In Fused Sio2 By Corona Poling Under Water, Water Vapor And Salty Environments, Chun-An Tsai, Jung Ning Wang, Wei-Kuo Chao, Tsung Yuan Cheng, Wan-Rone Liou, Adam Y. Wu

Journal of Marine Science and Technology–Taiwan

We found that optical nonlinearity in SiO2 glass sample can be greatly enhanced when sample is poled in wet and salty environments, and the nonlinearity in the sample can be reduced drastically when sample is washed in water. Possible causes for the observed enhancement and reduction of optical nonlinearity in SiO2 glass are discussed.

A Surveillance System To Create And Distribute Geo-Referenced Mosaics Using Suav Video, Evan D. Andersen

Theses and Dissertations

Small Unmanned Aerial Vehicles (SUAVs) are an attractive choice for many surveillance tasks. However, video from an SUAV can be difficult to use in its raw form. In addition, the limitations inherent in the SUAV platform inhibit the distribution of video to remote users. To solve the problems with using SUAV video, we propose a system to automatically create geo-referenced mosiacs of video frames. We also present three novel techniques we have developed to improve ortho-rectification and geo-location accuracy of the mosaics. The most successful of these techniques is able to reduce geo-location error by a factor of 15 with …

A Secure And Efficient Communications Architecture For Global Information Grid Users Via Cooperating Space Assets, Victor P. Hubenko Jr.

Theses and Dissertations

With the Information Age in full and rapid development, users expect to have global, seamless, ubiquitous, secure, and efficient communications capable of providing access to real-time applications and collaboration. The United States Department of Defense’s (DoD) Network-Centric Enterprise Services initiative, along with the notion of pushing the “power to the edge,” aims to provide end-users with maximum situational awareness, a comprehensive view of the battlespace, all within a secure networking environment. Building from previous AFIT research efforts, this research developed a novel security framework architecture to address the lack of efficient and scalable secure multicasting in the low earth orbit …

Statistical Methods For Image Registration And Denoising, Matthew D. Sambora

Theses and Dissertations

This dissertation describes research into image processing techniques that enhance military operational and support activities. The research extends existing work on image registration by introducing a novel method that exploits local correlations to improve the performance of projection-based image registration algorithms. The dissertation also extends the bounds on image registration performance for both projection-based and full-frame image registration algorithms and extends the Barankin bound from the one-dimensional case to the problem of two-dimensional image registration. It is demonstrated that in some instances, the Cramer-Rao lower bound is an overly-optimistic predictor of image registration performance and that under some conditions, the …

Monitoring The Antarctic Ice Sheet From Space, Benjamin Rule Lambert

Theses and Dissertations

The Antarctic ice sheet is a geophysically - and in an age of growing concern about global warming, geopolitically - important portion of Earth. The composition and dynamics of the Antarctic ice sheet influence global climate patterns, global sea level and the planet's radiation budget. Recent evidence also suggests that the long term stability of portions of the ice sheet may be in jeopardy. In this thesis I use data from three Ku-band space-borne scatterometers to monitor changes in the backscatter signature of the Antarctic ice sheet from 1978 through 2007. Significant changes in backscatter, which result from geophysical changes …

Practical Issues Of Power Control In Ieee 802.11 Wireless Devices, Karol Kowalik, Marek Bykowski, Brian Keegan, Mark Davis

Conference papers

Power control techniques for IEEE 802.11 wireless networks have already gained much attention. Such techniques are particularly attractive because they can improve various aspects of wireless network operations such as interference mitigation, spatial reuse in dense wireless deployments, topology control, and link quality enhancement. However, until recently implementing such advanced power control using off-the-shelf wireless devices was not considered possible. For example, Abdesslem et al. [1] stated that “many novel power control solutions cannot be efficiently implemented over existing IEEE 802.11 cards”. However, in this paper we demonstrate that power control is now feasible and can be implemented in current …

A Real-Time Framework For Video Time And Pitch Scale Modification, Ivan Damnjanovic, Dan Barry, David Dorran, Josh Reiss

Conference papers

A framework is presented which addresses the issues related to the real-time implementation of synchronised video and audio time-scale and pitch-scale modification algorithms. It allows for seamless real-time transition between continually varying, independent time-scale and pitch-scale parameters arising as a result of manual or automatic intervention. We illuminate the problems which arise in a real-time context as well as provide novel solutions to prevent artefacts, minimise latency, and improve synchronisation. The time and pitch scaling approach is based on a modified phase vocoder with optional phase locking and an integrated transient detector which enables high quality transient preservation in real-time. …

Synthesis Of Double-Input Dc-Dc Converters Using A Single-Pole Triple-Throw Switch As A Building Block, Karteek Gummi, Mehdi Ferdowsi

Electrical and Computer Engineering Faculty Research & Creative Works

Hybridizing power electronic systems using an energy storage unit has gained popularity in transportation and power system applications. This task has traditionally been performed by using several independent power electronic converters. Multi-input converters, due to their reduced part count and improved efficiency, seem to be an advantageous option to replace the conventional converters. A few multi-input converter topologies have been reported in the literature; however, there is not a systematic approach to derive them. Furthermore, all possible topologies are not completely explored and it is difficult to derive new converters from the existing topologies. Hence, in this paper, a systematic …

Towards Spike-Based Speech Processing: A Biologically Plausible Approach To Simple Acoustic Classification, Ismail Uysal, Harsha Sathyendra, John G. Harris

Electrical and Computer Engineering Faculty Research & Creative Works

Shortcomings of automatic speech recognition (ASR) applications are becoming more evident as they are more widely used in real life. The inherent non-stationarity associated with the timing of speech signals as well as the dynamical changes in the environment make the ensuing analysis and recognition extremely difficult. Researchers often turn to biology seeking clues to make better engineered systems, and ASR is no exception with the usage of feature sets such as Mel frequency cepstral coefficients, which employ filter banks similar to cochlear filter banks in frequency distribution and bandwidth. In this paper, we delve deeper into the mechanics of …

Vector Support For Multicore Processors With Major Emphasis On Configurable Multiprocessors, Hongyan Yang

Dissertations

It recently became increasingly difficult to build higher speed uniprocessor chips because of performance degradation and high power consumption. The quadratically increasing circuit complexity forbade the exploration of more instruction-level parallelism (JLP). To continue raising the performance, processor designers then focused on thread-level parallelism (TLP) to realize a new architecture design paradigm. Multicore processor design is the result of this trend. It has proven quite capable in performance increase and provides new opportunities in power management and system scalability. But current multicore processors do not provide powerful vector architecture support which could yield significant speedups for array operations while maintaining …

Synthesis And Analysis Of Carbon Nanowalls And Their Raman Spectroscopy, Amit Mahajan

Theses

Growth of Carbon Nanowalls has been carried out by Radio Frequency Chemical Vapor Deposition (RF-PECVD) on various substrates. Hydrogen was used as an active gas for the growth where as Ethanol bubbled with Argon was used as carbon source for formation of Carbon Nanowalls (CNW). The growth was then confinned by Raman Spectroscopy and Scanning Electron Microscope (SEM) images. Also the need of using catalyst in CNW has been analyzed. The intensities of D and G bands obtained from Raman spectrum have been related to the length of Graphene walls, to study the CNW's length on different substrates.

The growth …

College Of Engineering Senior Design Competition Spring 2008, University Of Nevada, Las Vegas

Fred and Harriet Cox Senior Design Competition Projects

Part of every UNLV engineering student’s academic experience, the senior design project stimulates engineering innovation and entrepreneurship. Each student in their senior year chooses, plans, designs, and prototypes a product in this required element of the curriculum. A capstone to the student’s educational career, the senior design project encourages the student to use everything learned in the engineering program to create a practical, real world solution to an engineering challenge.

The senior design competition helps to focus the senior students in increasing the quality and potential for commercial application for their design projects. Judges from local industry evaluate the projects …