Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- Laser (3)
- Liquid crystal (2)
- Optical coherence tomography (2)
- Physical optics (2)
- Remediation (2)
-
- Statistical optics (2)
- Waveguide arrays (2)
- 3D reconstruction (1)
- Action Recognition (1)
- Activity Recognition (1)
- Ad hoc wireless networks (1)
- Adaboost (1)
- Adaptive Optics (1)
- Advanced microscopy. (1)
- Affective design (1)
- Aluminum (1)
- Amphiphiles (1)
- Analog micro-optics (1)
- Anomaly (1)
- Anomaly Detection (1)
- Antenna (1)
- Atmospheric propagation (1)
- Ball milling (1)
- Base excision repair (1)
- Bayes (1)
- Behavior-based (1)
- Biomedical optical imaging (1)
- Biophotonics (1)
- Body fluid identification (1)
- CASE-based reasoner (1)
Articles 1 - 30 of 57
Full-Text Articles in Entire DC Network
Enhancing Message Privacy In Wired Equivalent Privacy., Darshan Purandare
Enhancing Message Privacy In Wired Equivalent Privacy., Darshan Purandare
Electronic Theses and Dissertations
The 802.11 standard defines the Wired Equivalent Privacy (WEP) and encapsulation of data frames. It is intended to provide data privacy to the level of a wired network. WEP suffered threat of attacks from hackers owing to certain security shortcomings in the WEP protocol. Lately, many new protocols like WiFi Protected Access (WPA), WPA2, Robust Secure Network (RSN) and 802.11i have come into being, yet their implementation is fairly limited. Despite its shortcomings one cannot undermine the importance of WEP as it still remains the most widely used system and we chose to address certain security issues and propose some …
Compressed Pattern Matching For Text And Images, Tao Tao
Compressed Pattern Matching For Text And Images, Tao Tao
Electronic Theses and Dissertations
The amount of information that we are dealing with today is being generated at an ever-increasing rate. On one hand, data compression is needed to efficiently store, organize the data and transport the data over the limited-bandwidth network. On the other hand, efficient information retrieval is needed to speedily find the relevant information from this huge mass of data using available resources. The compressed pattern matching problem can be stated as: given the compressed format of a text or an image and a pattern string or a pattern image, report the occurrence(s) of the pattern in the text or image …
An Introduction To Hellmann-Feynman Theory, David Wallace
An Introduction To Hellmann-Feynman Theory, David Wallace
Electronic Theses and Dissertations
The Hellmann-Feynman theorem is presented together with certain allied theorems. The origin of the Hellmann-Feynman theorem in quantum physical chemistry is described. The theorem is stated with proof and with discussion of applicability and reliability. Some adaptations of the theorem to the study of the variation of zeros of special functions and orthogonal polynomials are surveyed. Possible extensions are discussed.
Transform Based And Search Aware Text Compression Schemes And Compressed Domain Text Retrieval, Nan Zhang
Transform Based And Search Aware Text Compression Schemes And Compressed Domain Text Retrieval, Nan Zhang
Electronic Theses and Dissertations
In recent times, we have witnessed an unprecedented growth of textual information via the Internet, digital libraries and archival text in many applications. While a good fraction of this information is of transient interest, useful information of archival value will continue to accumulate. We need ways to manage, organize and transport this data from one point to the other on data communications links with limited bandwidth. We must also have means to speedily find the information we need from this huge mass of data. Sometimes, a single site may also contain large collections of data such as a library database, …
In Situ Remediation Of Heavy Metal Contaminated Sediments Using Emulsified Zero-Valent Metal Particles, Kristen Marie Milum
In Situ Remediation Of Heavy Metal Contaminated Sediments Using Emulsified Zero-Valent Metal Particles, Kristen Marie Milum
Electronic Theses and Dissertations
Sediments can act as both a sink for pollutants and a source for aquatic contaminants. Natural and human disturbances of the sediments can release the contaminants to the overlying water where bottom dwelling, or benthic, organisms may be exposed through direct contact, ingestion of sediment particles, or uptake of dissolved contaminants present in the water. Dredging, the most common remediation technology for heavy metals, exacerbates this process. The in situ use of emulsified metal has been studied for its ability to pull heavy metals from aqueous solution and from saturated soils. It has proven successful in the laboratory with removal …
Graph-Theoretic Approach To Modeling Propagation And Control Of Network Worms, Zoran Nikoloski
Graph-Theoretic Approach To Modeling Propagation And Control Of Network Worms, Zoran Nikoloski
Electronic Theses and Dissertations
In today's network-dependent society, cyber attacks with network worms have become the predominant threat to confidentiality, integrity, and availability of network computing resources. Despite ongoing research efforts, there is still no comprehensive network-security solution aimed at controling large-scale worm propagation. The aim of this work is fivefold: (1) Developing an accurate combinatorial model of worm propagation that can facilitate the analysis of worm control strategies, (2) Building an accurate epidemiological model for the propagation of a worm employing local strategies, (3) Devising distributed architecture and algorithms for detection of worm scanning activities, (4) Designing effective control strategies against the worm, …
Recovery Of Hydrogen And Helium From Their Mixtures Using Metal Hydrides, Muzaffer Tonguc Oztek
Recovery Of Hydrogen And Helium From Their Mixtures Using Metal Hydrides, Muzaffer Tonguc Oztek
Electronic Theses and Dissertations
Waste streams of hydrogen and helium mixtures are produced at the Kennedy Space Center during purging of the hydrogen systems and supply lines. This process is done prior to and after hydrogen servicing. The purged waste gases are lost to the atmosphere, resulting in an annual loss of 2 million and 0.1 million standard cubic meters of helium and hydrogen, respectively. Recovery of these gases will have an economic benefit. Metals, alloys, and intermetallics are known to react with hydrogen in favorable conditions; therefore, they have the possibility of serving as separating and recovery agents. In this study, Mg2Ni, VTiNi …
Access Games: A Game Theoretic Framework For Fair Bandwidth Sharing In Distributed Systems, Sudipta Rakshit
Access Games: A Game Theoretic Framework For Fair Bandwidth Sharing In Distributed Systems, Sudipta Rakshit
Electronic Theses and Dissertations
In this dissertation, the central objective is to achieve fairness in bandwidth sharing amongst selfish users in a distributed system. Because of the inherent contention-based nature of the distributed medium access and the selfishness of the users, the distributed medium access is modeled as a non-cooperative game; designated as the Access Game. A p-CSMA type medium access scenario is proposed for all the users. Therefore, in the Access Game, each user has two actions to choose from: "transmit" and "wait". The outcome of the Access Game and payoffs to each user depends on the actions taken by all the users. …
Affective Design In Technical Communication, Michael Alan Rosen
Affective Design In Technical Communication, Michael Alan Rosen
Electronic Theses and Dissertations
Traditional human-computer interaction (HCI) is based on 'cold' models of user cognition; that is, models of users as purely rational beings based on the information processing metaphor; however, an emerging perspective suggests that for the field of HCI to mature, its practitioners must adopt models of users that consider broader human needs and capabilities. Affective design is an umbrella term for research and practice being conducted in diverse domains, all with the common thread of integrating emotional aspects of use into the creation of information products. This thesis provides a review of the current state of the art in affective …
The Scintillation Index In Moderate To Strong Turbulence For The Gaussian Beam Wave Along A Slant Path, Fredrick Eugene Thomas
The Scintillation Index In Moderate To Strong Turbulence For The Gaussian Beam Wave Along A Slant Path, Fredrick Eugene Thomas
Electronic Theses and Dissertations
Scintillation is one of the most common statistics in the literature of mathematical modeling of laser propagation through random media. One approach to estimating scintillation is through the Rytov approximation, which is limited to weak atmospheric turbulence. Recently, an improvement of the Rytov approximation was developed employing a linear filter function technique. This modifies the Rytov approximation and extends the validity into the moderate to strong regime. In this work, an expression governing scintillation of a Gaussian beam along an uplink slant path valid in all regimes of turbulence is presented, as well as results for the limiting cases of …
Decision Theory Classification Of High-Dimensional Vectors Based On Small Samples, David Bradshaw
Decision Theory Classification Of High-Dimensional Vectors Based On Small Samples, David Bradshaw
Electronic Theses and Dissertations
In this paper, we review existing classification techniques and suggest an entirely new procedure for the classification of high-dimensional vectors on the basis of a few training samples. The proposed method is based on the Bayesian paradigm and provides posterior probabilities that a new vector belongs to each of the classes, therefore it adapts naturally to any number of classes. Our classification technique is based on a small vector which is related to the projection of the observation onto the space spanned by the training samples. This is achieved by employing matrix-variate distributions in classification, which is an entirely new …
Analyzing The Community Structure Of Web-Like Networks: Models And Algorithms, Aurel Cami
Analyzing The Community Structure Of Web-Like Networks: Models And Algorithms, Aurel Cami
Electronic Theses and Dissertations
This dissertation investigates the community structure of web-like networks (i.e., large, random, real-life networks such as the World Wide Web and the Internet). Recently, it has been shown that many such networks have a locally dense and globally sparse structure with certain small, dense subgraphs occurring much more frequently than they do in the classical Erdös-Rényi random graphs. This peculiarity--which is commonly referred to as community structure--has been observed in seemingly unrelated networks such as the Web, email networks, citation networks, biological networks, etc. The pervasiveness of this phenomenon has led many researchers to believe that such cohesive groups of …
Application Of Statistical Methods In Risk And Reliability, Astrid Heard
Application Of Statistical Methods In Risk And Reliability, Astrid Heard
Electronic Theses and Dissertations
The dissertation considers construction of confidence intervals for a cumulative distribution function F(z) and its inverse at some fixed points z and u on the basis of an i.i.d. sample where the sample size is relatively small. The sample is modeled as having the flexible Generalized Gamma distribution with all three parameters being unknown. This approach can be viewed as an alternative to nonparametric techniques which do not specify distribution of X and lead to less efficient procedures. The confidence intervals are constructed by objective Bayesian methods and use the Jeffreys noninformative prior. Performance of the resulting confidence intervals is …
Insulator-Insulator Contact Charging As A Function Of Pressure, Michael Hogue
Insulator-Insulator Contact Charging As A Function Of Pressure, Michael Hogue
Electronic Theses and Dissertations
Metal - metal and to an extent metal - insulator contact or triboelectric charging are well known phenomena with good theoretical understanding of the charge exchange mechanism. However, insulator insulator charging is not as well understood. Theoretical and experimental research has been performed that shows that the surface charge on an insulator after triboelectric charging with another insulator is rapidly dissipated with lowered atmospheric pressure. This pressure discharge is consistent with surface ions being evaporated off the surface once their vapor pressure falls below the saturation vapor pressure. A two-phase equilibrium model based on an ideal gas of singly …
Optical Wave Propagation In Discrete Waveguide Arrays, Jared Hudock
Optical Wave Propagation In Discrete Waveguide Arrays, Jared Hudock
Electronic Theses and Dissertations
The propagation dynamics of light in optical waveguide arrays is characteristic of that encountered in discrete systems. As a result, it is possible to engineer the diffraction properties of such structures, which leads to the ability to control the flow of light in ways that are impossible in continuous media. In this work, a detailed theoretical investigation of both linear and nonlinear optical wave propagation in one- and two-dimensional waveguide lattices is presented. The ability to completely overcome the effects of discrete diffraction through the mutual trapping of two orthogonally polarized coherent beams interacting in Kerr nonlinear arrays of birefringent …
Liquid Crystal Optics For Communications, Signal Processing And 3-D Microscopic Imaging, Sajjad Khan
Liquid Crystal Optics For Communications, Signal Processing And 3-D Microscopic Imaging, Sajjad Khan
Electronic Theses and Dissertations
This dissertation proposes, studies and experimentally demonstrates novel liquid crystal (LC) optics to solve challenging problems in RF and photonic signal processing, freespace and fiber optic communications and microscopic imaging. These include free-space optical scanners for military and optical wireless applications, variable fiber-optic attenuators for optical communications, photonic control techniques for phased array antennas and radar, and 3-D microscopic imaging. At the heart of the applications demonstrated in this thesis are LC devices that are non-pixelated and can be controlled either electrically or optically. Instead of the typical pixel-by-pixel control as is custom in LC devices, the phase profile across …
Creating Models Of Internet Background Traffic Suitable For Use In Evaluating Network Intrusion Detection Systems, Song Luo
Electronic Theses and Dissertations
This dissertation addresses Internet background traffic generation and network intrusion detection. It is organized in two parts. Part one introduces a method to model realistic Internet background traffic and demonstrates how the models are used both in a simulation environment and in a lab environment. Part two introduces two different NID (Network Intrusion Detection) techniques and evaluates them using the modeled background traffic. To demonstrate the approach we modeled five major application layer protocols: HTTP, FTP, SSH, SMTP and POP3. The model of each protocol includes an empirical probability distribution plus estimates of application-specific parameters. Due to the complexity of …
Reaction Rates For The Dehalogenation Of Trichloroethylene Using Various Types Of Zero-Valent Iron, Neil Stewart
Reaction Rates For The Dehalogenation Of Trichloroethylene Using Various Types Of Zero-Valent Iron, Neil Stewart
Electronic Theses and Dissertations
Remediation of trichloroethylene (TCE) and other chlorinated solvents is of great concern due to their toxicity and their persistence in the environment. Iron has been used extensively in the past decade as a subsurface reactive agent for the remediation of dense, nonaqueous-phase liquids (DNAPLs). Permeable reactive barrier walls (PRBW) have been installed at many sites around the country to treat contaminated plumes resulting from the presence of DNAPL pools. The use of zero-valent metals, such as iron, to effectively reductively dechlorinate DNAPLs has been employed as the reactive material in these PRBWs (Gillham et al., 1993). However, limited work has …
Qos In Cognitive Packet Networks: Adaptive Routing, Flow And Congestion Control, Pu Su
Qos In Cognitive Packet Networks: Adaptive Routing, Flow And Congestion Control, Pu Su
Electronic Theses and Dissertations
With the emergence of various applications that have different Quality of Service (QoS) requirements, the capability of a network to support QoS becomes more and more important and necessary. This dissertation explores QoS in Cognitive Packet Networks (CPN) by using adaptive routing, flow and congestion control. We present a detailed description and analysis of our proposed routing algorithms based on single and multiple QoS constraints. An online estimation of packet loss rate over a path is introduced. We implement and evaluate the adaptive routing scheme in an experimental CPN test-bed. Our experiments support our claims that the users can achieve …
Contributions To Automatic Particle Identification In Electron Micrographs: Algorithms, Implementation, And Applications, Vivek Singh
Electronic Theses and Dissertations
Three dimensional reconstruction of large macromolecules like viruses at resolutions below 8 Ã… - 10 Ã… requires a large set of projection images and the particle identification step becomes a bottleneck. Several automatic and semi-automatic particle detection algorithms have been developed along the years. We present a general technique designed to automatically identify the projection images of particles. The method utilizes Markov random field modelling of the projected images and involves a preprocessing of electron micrographs followed by image segmentation and post processing for boxing of the particle projections. Due to the typically extensive computational requirements for extracting hundreds of …
Refractive Indices Of Liquid Crystals And Their Applications In Display And Photonic Devices, Jun Li
Refractive Indices Of Liquid Crystals And Their Applications In Display And Photonic Devices, Jun Li
Electronic Theses and Dissertations
Liquid crystals (LCs) are important materials for flat panel display and photonic devices. Most LC devices use electrical field-, magnetic field-, or temperature-induced refractive index change to modulate the incident light. Molecular constituents, wavelength, and temperature are the three primary factors determining the liquid crystal refractive indices: ne and no for the extraordinary and ordinary rays, respectively. In this dissertation, we derive several physical models for describing the wavelength and temperature effects on liquid crystal refractive indices, average refractive index, and birefringence. Based on these models, we develop some high temperature gradient refractive index LC mixtures for photonic applications, such …
Multizoom Activity Recognition Using Machine Learning, Raymond Smith
Multizoom Activity Recognition Using Machine Learning, Raymond Smith
Electronic Theses and Dissertations
In this thesis we present a system for detection of events in video. First a multiview approach to automatically detect and track heads and hands in a scene is described. Then, by making use of epipolar, spatial, trajectory, and appearance constraints, objects are labeled consistently across cameras (zooms). Finally, we demonstrate a new machine learning paradigm, TemporalBoost, that can recognize events in video. One aspect of any machine learning algorithm is in the feature set used. The approach taken here is to build a large set of activity features, though TemporalBoost itself is able to work with any feature set …
Structural Study Of Disease Related Proteins, Ayse Sinem Ozyurt
Structural Study Of Disease Related Proteins, Ayse Sinem Ozyurt
Electronic Theses and Dissertations
The availability of complete sequences for the genomes of many organisms changes the researcher's attention from genome sequencing to finding the function of gene products, the proteins. The three dimensional (3D) structure of a protein is helpful to understand its function, because tertiary structure is more conserved in evolution than sequence. The 3D structures can be found quickly by using high-throughput (HT) methods for protein expression, purification, characterization and structure determination. This process is very challenging in every step. Therefore we selected nearly 200 cancer related proteins as targets to see the difficulties in trying to determine the web predicted …
Formalization Of Input And Output In Modern Operating Systems: The Hadley Model, Matthew Gerber
Formalization Of Input And Output In Modern Operating Systems: The Hadley Model, Matthew Gerber
Electronic Theses and Dissertations
We present the Hadley model, a formal descriptive model of input and output for modern computer operating systems. Our model is intentionally inspired by the Open Systems Interconnection model of networking; I/O as a process is defined as a set of translations between a set of computer-sensible forms, or layers, of information. To illustrate an initial application domain, we discuss the utility of the Hadley model and a potential associated I/O system as a tool for digital forensic investigators. To illustrate practical uses of the Hadley model we present the Hadley Specification Language, an essentially functional language designed to allow …
Real-Time Realistic Rendering And High Dynamic Range Image Display And Compression, Ruifeng Xu
Real-Time Realistic Rendering And High Dynamic Range Image Display And Compression, Ruifeng Xu
Electronic Theses and Dissertations
This dissertation focuses on the many issues that arise from the visual rendering problem. Of primary consideration is light transport simulation, which is known to be computationally expensive. Monte Carlo methods represent a simple and general class of algorithms often used for light transport computation. Unfortunately, the images resulting from Monte Carlo approaches generally suffer from visually unacceptable noise artifacts. The result of any light transport simulation is, by its very nature, an image of high dynamic range (HDR). This leads to the issues of the display of such images on conventional low dynamic range devices and the development of …
Synthesis, Characterizations, And Evaluation Of New Reactive Two-Photon Absorbing Dyes For Two-Photon Excited Fluorescence Imaging Applications, Katherine J. Hales
Synthesis, Characterizations, And Evaluation Of New Reactive Two-Photon Absorbing Dyes For Two-Photon Excited Fluorescence Imaging Applications, Katherine J. Hales
Electronic Theses and Dissertations
Recent, cooperative advances in chemistry, biology, computing, photophysics, optics, and microelectronics have resulted in extraordinary developments in the biological sciences, resulting in the emergence of a novel area termed 'biophotonics'. The integrative and interdisciplinary nature of biophotonics cuts across virtually all disciplines, extending the frontiers of basic cellular, molecular, and biology research through the clinical and pharmaceutical industries. This holds true for the development and application of the novel imaging modality utilizing multiphoton absorption and its extraordinary contribution to recent advances in bioimaging. Intimately involved in the revolution of nonlinear bioimaging has been the development of optical probes for probing …
Design And Assessment Of Compact Optical Systems Towards Special Effects Imaging, Vesselin Chaoulov
Design And Assessment Of Compact Optical Systems Towards Special Effects Imaging, Vesselin Chaoulov
Electronic Theses and Dissertations
A main challenge in the field of special effects is to create special effects in real time in a way that the user can preview the effect before taking the actual picture or movie sequence. There are many techniques currently used to create computer-simulated special effects, however current techniques in computer graphics do not provide the option for the creation of real-time texture synthesis. Thus, while computer graphics is a powerful tool in the field of special effects, it is neither portable nor does it provide work in real-time capabilities. Real-time special effects may, however, be created optically. Such approach …
Resource Allocation Schemes And Performance Evaluation Models For Wavelength Division Multiplexed Optical Networks, Mounire El Houmaidi
Resource Allocation Schemes And Performance Evaluation Models For Wavelength Division Multiplexed Optical Networks, Mounire El Houmaidi
Electronic Theses and Dissertations
Wavelength division multiplexed (WDM) optical networks are rapidly becoming the technology of choice in network infrastructure and next-generation Internet architectures. WDM networks have the potential to provide unprecedented bandwidth, reduce processing cost, achieve protocol transparency, and enable efficient failure handling. This dissertation addresses the important issues of improving the performance and enhancing the reliability of WDM networks as well as modeling and evaluating the performance of these networks. Optical wavelength conversion is one of the emerging WDM enabling technologies that can significantly improve bandwidth utilization in optical networks. A new approach for the sparse placement of full wavelength converters based …
Voice Authenticationa Study Of Polynomial Representation Of Speech Signals, John Strange
Voice Authenticationa Study Of Polynomial Representation Of Speech Signals, John Strange
Electronic Theses and Dissertations
A subset of speech recognition is the use of speech recognition techniques for voice authentication. Voice authentication is an alternative security application to the other biometric security measures such as the use of fingerprints or iris scans. Voice authentication has advantages over the other biometric measures in that it can be utilized remotely, via a device like a telephone. However, voice authentication has disadvantages in that the authentication system typically requires a large memory and processing time than do fingerprint or iris scanning systems. Also, voice authentication research has yet to provide an authentication system as reliable as the other …
Session-Based Intrusion Detection System To Map Anomalous Network Traffic, Bruce Caulkins
Session-Based Intrusion Detection System To Map Anomalous Network Traffic, Bruce Caulkins
Electronic Theses and Dissertations
Computer crime is a large problem (CSI, 2004; Kabay, 2001a; Kabay, 2001b). Security managers have a variety of tools at their disposal -- firewalls, Intrusion Detection Systems (IDSs), encryption, authentication, and other hardware and software solutions to combat computer crime. Many IDS variants exist which allow security managers and engineers to identify attack network packets primarily through the use of signature detection; i.e., the IDS recognizes attack packets due to their well-known "fingerprints" or signatures as those packets cross the network's gateway threshold. On the other hand, anomaly-based ID systems determine what is normal traffic within a network and reports …