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Articles 3661 - 3690 of 4194

Full-Text Articles in Physical Sciences and Mathematics

Smoothing Parameter Selection In Nonparametric Functional Estimation, Mohamed Amezziane Jan 2004

Smoothing Parameter Selection In Nonparametric Functional Estimation, Mohamed Amezziane

Electronic Theses and Dissertations

This study intends to build up new techniques for how to obtain completely data-driven choices of the smoothing parameter in functional estimation, within the confines of minimal assumptions. The focus of the study will be within the framework of the estimation of the distribution function, the density function and their multivariable extensions along with some of their functionals such as the location and the integrated squared derivatives.

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The Wave Structure Function And Temporal Frequency Spread In Weak To Strong Optical Turbulence, Aaron J. Masino Jan 2004

The Wave Structure Function And Temporal Frequency Spread In Weak To Strong Optical Turbulence, Aaron J. Masino

Electronic Theses and Dissertations

This paper presents analytic expressions for the wave structure function, frequency spread of the temporal frequency spectrum, and the temporal frequency spectrum of optical signals propagating through a random medium, specifically the Earth’s atmosphere. The results are believed to be valid for all optical turbulence conditions. These expressions are developed using the Rytov approximation method. Generally, the validity of statistical quantities obtained via this method is restricted to conditions of weak optical turbulence. However, in this work, by using a modification of the effective atmospheric spectral model presented by Andrews et al. for scintillation index, wave structure function expressions have …

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Electron Injection-Induced Effects In Iii-Nitrides: Physics And Applications, William Charles Burdett Jan 2004

Electron Injection-Induced Effects In Iii-Nitrides: Physics And Applications, William Charles Burdett

Electronic Theses and Dissertations

This research investigated the effect of electron injection in III-Nitrides. The combination of electron beam induced current and cathodoluminescence measurements was used to understand the impact of electron injection on the minority carrier transport and optical properties. In addition, the application of the electron injection effect in optoelectronic devices was investigated. The impact of electron injection on the minority carrier diffusion length was studied at various temperatures in Mg-doped p-GaN, p-Al[subscript x]Ga[subscript 1-x]N, and p-Al[subscript x]Ga[subscript 1-x] N/GaN superlattices. It was found that Lsubscript n] experienced a multi-fold linear increase and that the rate of change of L[subscript n] decreased …

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Individual Carbon Nanotube Probes And Field Emitters Fabrication And T, Guangyu Chai Jan 2004

Individual Carbon Nanotube Probes And Field Emitters Fabrication And T, Guangyu Chai

Electronic Theses and Dissertations

Since the discovery of carbon nanotubes (CNT) in 1999, they have attracted much attention due to their unique mechanical and electrical properties and potential applications. Yet their nanosize makes the study of individual CNTs easier said than done. In our laboratory, carbon fibers with nanotube cores have been synthesized with conventional chemical vapor deposition (CVD) method. The single multiwall carbon nanotube (MWNT) sticks out as a tip of the carbon fiber. In order to pick up the individual CNT tips, focused ion beam (FIB) technique is applied to cut and adhere the samples. The carbon fiber with nanotube tip was …

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The Use Of Pyrosequencing For The Analysis Of Y Chromosome Single Nucleotide Polymorphisms, Jeremy Charles Fletcher Jan 2004

The Use Of Pyrosequencing For The Analysis Of Y Chromosome Single Nucleotide Polymorphisms, Jeremy Charles Fletcher

Electronic Theses and Dissertations

The potential value of the Y chromosome for forensic applications has been recognized for some time with the current work dedicated to Short Tandem Repeat analysis and Single Nucleotide Polymorphism (SNP) discovery. This study examined the ability of two different SNP analysis methods to determine if they could be utilized in forensic applications and ultimately be developed into an established system for Y chromosome SNP analysis. This study examined two principle SNP analysis systems: single base extension and Pyrosequencing. Pyrosequencing was determined to be superior to single base extension, due to the wealth of information provided with sequencing and the …

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The Design And Development Of A Comprehensive 49 Locus Y-Str Database For Major U.S. Populations, Paulina Niki Berdos Jan 2004

The Design And Development Of A Comprehensive 49 Locus Y-Str Database For Major U.S. Populations, Paulina Niki Berdos

Electronic Theses and Dissertations

The establishment of a U.S. National Y-STR reference database from a variety of geographically and ethically diverse populations is essential to facilitate the generation of reliable estimates of Y-STR haplotype frequencies. Such multi-locus haplotype frequencies are required to provide a statistical estimate of the significance of a match. Y-STR loci, unlike traditional STR markers, are not independent of one another and are co-inherited as extended haplotypes of linked markers. The estimation of the frequency of occurrence of a particular haplotype therefore necessitates the use of a counting method, which means that the significance of many matches is dependent upon the …

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Stability And Recovery Of Rna In Biological Stains, Mindy Eileen Setzer Jan 2004

Stability And Recovery Of Rna In Biological Stains, Mindy Eileen Setzer

Electronic Theses and Dissertations

In theory, RNA expression patterns, including the presence and relative abundance of particular RNA species, provide cell and tissue specific information that could be of use to forensic scientists. An mRNA based approach could allow the facile identification of the tissue components present in a body fluid stain and conceivably could supplant the battery of serological and biochemical tests currently employed in the forensic serology laboratory. Some of the potential advantages include greater test specificity, and the ability to perform simultaneous analysis using a common assay format for the presence of all body fluids of forensic interest. In this report, …

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New Organic/Inorganic Hybrid Sol-Gel Nanocomposite Materials For Raman Gain In Fiber Optics, Stephen James Andrasik Jan 2004

New Organic/Inorganic Hybrid Sol-Gel Nanocomposite Materials For Raman Gain In Fiber Optics, Stephen James Andrasik

Electronic Theses and Dissertations

The recent increased availability of additional wavelengths in the telecommunications window of about 1300-1600 nm has generated an interest in new optical materials and devices that can operate outside the normally used regions of 840 nm, 1310 nm, and 1550 nm. Specifically, methods to amplify fiber optical data transmission in the regions where there is limited or no existing methods to achieve amplification is of interest in the chemistry and photonic communities. Raman gain is one method that has been proposed to passively amplify optical data transmission through a distributed process. Amplification is obtained through a nonlinear light scattering process …

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Block Copolymer Stabilized Self-Assembled Magnetic Nanoparticles, Li Zhang Jan 2004

Block Copolymer Stabilized Self-Assembled Magnetic Nanoparticles, Li Zhang

Electronic Theses and Dissertations

Magnetic materials are currently being developed in the areas of pharmacology and medicinal chemistry for use in applications such as drug delivery and magnetic resonance imaging. Magnetic fluids are being used in audio equipment and hard disk drives. Their suspension in a particular fluid is promoted by the adsorption or reaction of steric or electrostatic stabilizers, which are appropriate for the particular medium. Critical to the success of these magnetic fluids is the development of the steric stabilizers, which must prevent the coagulation of the metal particles. Polymeric materials are one of the most suitable nonmagnetic media to disperse the …

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Estimation Of Standardized Mortality Ratio In Geographic Epidemiology, Anna Kettermann Jan 2004

Estimation Of Standardized Mortality Ratio In Geographic Epidemiology, Anna Kettermann

Electronic Theses and Dissertations

The analysis of geographic variation of disease and its representation on a map form an important topic of research in epidemiology and in public health in general. Identification of spatial heterogeneity of relative risk using morbidity and mortality data is required. The usual technique of disease atlas generation consists of data collection (observed number of disease cases). These data are collected during a continuous period of time (5 to 10 years). The second aspect of atlas creation relates to the analysis of these data. A traditional measure of the spatial variation is usually taken as a ratio of the number …

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Method For Determination Of Singlet Oxygen Quantum Yields For New Fluorene-Based Photosensitizers In Aqueous Media For The Advancement Of Photodynamic Therapy, Wade William Grabow Jan 2004

Method For Determination Of Singlet Oxygen Quantum Yields For New Fluorene-Based Photosensitizers In Aqueous Media For The Advancement Of Photodynamic Therapy, Wade William Grabow

Electronic Theses and Dissertations

Photodynamic therapy (PDT) has been investigated over the past three decades and is currently an approved therapeutic modality for skin cancer, the treatment of superficial bladder, early lung and advanced esophageal cancers, and age-related macular degeneration in a number of countries. In PDT, the absorption of light by a chromophore generates cytotoxic species such as reactive singlet oxygen, leading to irreversible destruction of the treated tissue. The measurement of the singlet oxygen quantum yield is an important determinant used to evaluate the efficiency of new photodynamic therapy agents developed in the laboratory, to screen potential photosensitizers in aqueous media.The singlet …

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High Performance Data Mining Techniques For Intrusion Detection, Muazzam Ahmed Siddiqui Jan 2004

High Performance Data Mining Techniques For Intrusion Detection, Muazzam Ahmed Siddiqui

Electronic Theses and Dissertations

The rapid growth of computers transformed the way in which information and data was stored. With this new paradigm of data access, comes the threat of this information being exposed to unauthorized and unintended users. Many systems have been developed which scrutinize the data for a deviation from the normal behavior of a user or system, or search for a known signature within the data. These systems are termed as Intrusion Detection Systems (IDS). These systems employ different techniques varying from statistical methods to machine learning algorithms. Intrusion detection systems use audit data generated by operating systems, application softwares or …

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Fast Algorithms For Fragment Based Completion In Images Of Natural Scenes, Siddharth Rajkumar Borikar Jan 2004

Fast Algorithms For Fragment Based Completion In Images Of Natural Scenes, Siddharth Rajkumar Borikar

Electronic Theses and Dissertations

Textures are used widely in computer graphics to represent fine visual details and produce realistic looking images. Often it is necessary to remove some foreground object from the scene. Removal of the portion creates one or more holes in the texture image. These holes need to be filled to complete the image. Various methods like clone brush strokes and compositing processes are used to carry out this completion. User skill is required in such methods. Texture synthesis can also be used to complete regions where the texture is stationary or structured. Reconstructing methods can be used to fill in large-scale …

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Mitochondrial Dna Analysis By Pyrosequencing, Patsy-Ann Susan Hastings Jan 2004

Mitochondrial Dna Analysis By Pyrosequencing, Patsy-Ann Susan Hastings

Electronic Theses and Dissertations

Mitochondrial DNA (deoxyribo nucleic acid) is typically used in forensic casework when small quantities of high molecular weight quality DNA is not expected to be present thus negating the chances of obtaining usable nuclear DNA. Typical samples that utilized mitochondrial DNA analysis are: hair, bones, teeth, ancient remains (samples or remains that are at least 100 years old) or very old samples (samples that are less than 100 but greater than 10 years old). The current method used to evaluate mitochondrial DNA is Sanger sequencing. Although robust, it is also time consuming and labor intensive, on the other hand pyrosequencing …

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The Use Of Filters In Topology, Abdellatif Dasser Jan 2004

The Use Of Filters In Topology, Abdellatif Dasser

Electronic Theses and Dissertations

Sequences are sufficient to describe topological properties in metric spaces or, more generally, topological spaces having a countable base for the topology. However, filters or nets are needed in more abstract spaces. Nets are more natural extension of sequences but are generally less friendly to work with since quite often two nets have distinct directed sets for domains. Operations involving filters are set theoretic and generally certain to filters on the same set. The concept of a filter was introduced by H. Cartan in 1937 and an excellent treatment of the subject can be found in N. Bourbaki (1940).

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Synthesis And Polymerization Of Bifunctional Five-Membered Cyclic Dithiocarbonates And Their Use As Stabilizers For Magnetic Nan, Mohammed Daoudi Jan 2004

Synthesis And Polymerization Of Bifunctional Five-Membered Cyclic Dithiocarbonates And Their Use As Stabilizers For Magnetic Nan, Mohammed Daoudi

Electronic Theses and Dissertations

Novel bifunctional five-membered cyclic dithiocarbonates (1,3-oxathiolane-2-thione)s were synthesized by the reactions of the corresponding bifunctional oxiranes (epoxides) with carbon disulfide at room temperature with lithium bromide as catalyst. Full characterization of these monomers was performed including elemental analysis, proton and carbon nuclear magnetic resonance (NMR) spectroscopy, gas chromatography-mass spectroscopy, and Fourier transmission infrared (FTIR) spectroscopy. The polyaddition polymerization of 1,3-oxathiolane-2-thione with 1,4-diaminobutane at room temperature resulted in a poly(thiourethane) material. The latter undergoes crosslinking due probably to the autooxidation of the product and formation of disulfide linkages. The five-membered cyclic dithiocarbonate, 5-decyl-1,3-oxathiolane-2-thione, was used a model to demonstrate the usefulness …

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Synthesis Of A Novel Family Of Amide Derivatives Of Podocarpic Acid, Dao Nguyen Jan 2004

Synthesis Of A Novel Family Of Amide Derivatives Of Podocarpic Acid, Dao Nguyen

Electronic Theses and Dissertations

As a class, amides are of great interest in biological studies and pharmaceutical application. In this work, podocarpic acid, a natural tricyclic diterpene, derived from Podocarpus species, has been employed to form a novel family of amide derivatives which will later be studied for their potential as new drug leads. Novel amide derivatives of podocarpic acid were synthesized from podocarpic acid in three steps. The first step involved methylation with dimethylsulfate to form methyl-O-methylpodocarpate. This step was followed by iodination with iodine to give iodomethyl-O-methylpodocarpate. Finally amidation with various aliphatic amides using a copper catalyst yielded four amide derivatives of …

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Neural Networks Satisfying Stone-Weiestrass Theorem And Approximating, Pinal Thakkar Jan 2004

Neural Networks Satisfying Stone-Weiestrass Theorem And Approximating, Pinal Thakkar

Electronic Theses and Dissertations

Neural networks are an attempt to build computer networks called artificial neurons, which imitate the activities of the human brain. Its origin dates back to 1943 when neurophysiologist Warren Me Cello and logician Walter Pits produced the first artificial neuron. Since then there has been tremendous development of neural networks and their applications to pattern and optical character recognition, speech processing, time series prediction, image processing and scattered data approximation. Since it has been shown that neural nets can approximate all but pathological functions, Neil Cotter considered neural network architecture based on Stone-Weierstrass Theorem. Using exponential functions, polynomials, rational functions …

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Interactivity And User-Heterogeneity In On Demand Broadcast Video, Mounir Tantaoui El Araki Jan 2004

Interactivity And User-Heterogeneity In On Demand Broadcast Video, Mounir Tantaoui El Araki

Electronic Theses and Dissertations

Video-On-Demand (VOD) has appeared as an important technology for many multimedia applications such as news on demand, digital libraries, home entertainment, and distance learning. In its simplest form, delivery of a video stream requires a dedicated channel for each video session. This scheme is very expensive and non-scalable. To preserve server bandwidth, many users can share a channel using multicast. Two types of multicast have been considered. In a non-periodic multicast setting, users make video requests to the server; and it serves them according to some scheduling policy. In a periodic broadcast environment, the server does not wait for service …

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Dynamic Shared State Maintenance In Distributed Virtual Environments, Felix George Hamza-Lup Jan 2004

Dynamic Shared State Maintenance In Distributed Virtual Environments, Felix George Hamza-Lup

Electronic Theses and Dissertations

Advances in computer networks and rendering systems facilitate the creation of distributed collaborative environments in which the distribution of information at remote locations allows efficient communication. Particularly challenging are distributed interactive Virtual Environments (VE) that allow knowledge sharing through 3D information. In a distributed interactive VE the dynamic shared state represents the changing information that multiple machines must maintain about the shared virtual components. One of the challenges in such environments is maintaining a consistent view of the dynamic shared state in the presence of inevitable network latency and jitter. A consistent view of the shared scene will significantly increase …

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The Proteomics Approach To Evolutionary Computation: An Analysis Of Pr, Ivan Garibay Jan 2004

The Proteomics Approach To Evolutionary Computation: An Analysis Of Pr, Ivan Garibay

Electronic Theses and Dissertations

As the complexity of our society and computational resources increases, so does the complexity of the problems that we approach using evolutionary search techniques. There are recent approaches to deal with the problem of scaling evolutionary methods to cope with highly complex difficult problems. Many of these approaches are biologically inspired and share an underlying principle: a problem representation based on basic representational building blocks that interact and self-organize into complex functions or designs. The observation from the central dogma of molecular biology that proteins are the basic building blocks of life and the recent advances in proteomics on analysis …

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Partitioning A Graph In Alliances And Its Application To Data Clustering, Khurram Hassan-Shafique Jan 2004

Partitioning A Graph In Alliances And Its Application To Data Clustering, Khurram Hassan-Shafique

Electronic Theses and Dissertations

Any reasonably large group of individuals, families, states, and parties exhibits the phenomenon of subgroup formations within the group such that the members of each group have a strong connection or bonding between each other. The reasons of the formation of these subgroups that we call alliances differ in different situations, such as, kinship and friendship (in the case of individuals), common economic interests (for both individuals and states), common political interests, and geographical proximity. This structure of alliances is not only prevalent in social networks, but it is also an important characteristic of similarity networks of natural and unnatural …

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Factors Influencing A Declining Pronghorn Population In Wind Cave National Park, South Dakota, Jaret D. Sievers Jan 2004

Factors Influencing A Declining Pronghorn Population In Wind Cave National Park, South Dakota, Jaret D. Sievers

Electronic Theses and Dissertations

Pronghorn (Antilocapra americana) were reintroduced into Wind Cave National Park (WCNP) in 1914 and thus, have inhabited the park for almost a century. A decline in the population has raised concern for the continued existence of pronghorn inside the park. Historically, pronghorn numbers reached greater than 300 individuals but were estimated to be less than 50 individuals during this study. Knowledge of food habits, genetic structure, causes of mortality, survival rates, and information related to movements were important to developing an understanding of factors contributing to this decline. Past studies have described spatial relationships and breeding behavior of adults and …

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Effects Of Fire On The Nutritional Ecology Of Selected Ungulates In The Southern Black Hills, South Dakota, Teresa J. Zimmerman Jan 2004

Effects Of Fire On The Nutritional Ecology Of Selected Ungulates In The Southern Black Hills, South Dakota, Teresa J. Zimmerman

Electronic Theses and Dissertations

Research in the 1990s indicated that populations of white-tailed deer (Odocoileus virginianus) in the northern and central Black Hills had declined since the late 1970s likely due to habitat deterioration. In August 2000, the Jasper fire consumed nearly 35,000 ha of ponderosa pine (Pinus ponderosa) forest in the southern Black Hills. To ascertain the nutritional condition of white-tailed deer and mule deer (O. hemionus) and their response to fire, 5 adult white-tailed deer and 5 adult mule deer were collected in burned and unburned habitat, in February and August, 2002 and 2003. Collected deer were weighed and necropsied at a …

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Is Mwp 1a Real And Could It Have Originated In The Northern Hemisphere In Response To Bolling Warming, Sean D. Birkel Jan 2004

Is Mwp 1a Real And Could It Have Originated In The Northern Hemisphere In Response To Bolling Warming, Sean D. Birkel

Electronic Theses and Dissertations

Meltwater Pulse 1A (MWP 1A) is thought to have encompassed an abrupt rise in sea-level of 19 - 24 m ca. 14,000 calendar years B.P. The postulated rate of sea-level rise during the event was 24 - 50 mrnJyr. In contrast, the average rate of change during the overall glacial termination was 13 mrn/yr. Although MWP 1A is commonly accepted at face value, a compilation of all basic data points casts doubts on its validity. The Laurentide Ice Sheet (LIS) is commonly cited as the source of MWP 1A. Accelerated discharge of freshwater from the ice sheet could have weakened …

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A 200-Year Sulfate Record From 16 Antarctic Ice Cores And Associations With Southern Ocean Sea Ice Extent, Daniel A. Dixon Jan 2004

A 200-Year Sulfate Record From 16 Antarctic Ice Cores And Associations With Southern Ocean Sea Ice Extent, Daniel A. Dixon

Electronic Theses and Dissertations

Data from sixteen, 50m- to 115m-deep, sub-annually dated ice cores are used to examine the recent spatial and temporal concentration variability of sea salt (ss)S04 " and excess (xs)S04 " over West Antarctica for the last 200 years. The preservation of seasonal layers throughout the length of each record results in a dating accuracy of better than one year based on known global scale volcanic events. A dual transport source for West 9 9 Antarctic SSSO4 " and XSSO4 " is observed: lower tropospheric for areas below 1000m elevation and mid-upper tropospheric/stratospheric for areas located above 1000m. The XSSO4 " …

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Aesthetic Values Of Five Primary Wood Transporting Methods Common To Northern New England, Michael C. Eckley Jan 2004

Aesthetic Values Of Five Primary Wood Transporting Methods Common To Northern New England, Michael C. Eckley

Electronic Theses and Dissertations

Throughout northern New England and across the country, increasing populations and the exurbanization of rural forested landscapes have had a tremendous impact on forest management. As forested areas become more populated, society has become more exposed to the sights and sounds associated with different forest operations. As a result, aesthetics are increasingly driving public reaction to and concern about forestry practices, especially timber harvesting. How people perceive forestry harvesting can be significant in defining the future of forest management, particularly in more populated woodlands. The objective of this study was to better understanding public values as they relate to timber …

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Statistical Mechanics Of Farey Fraction Spin Chain Models, Jan Fiala Jan 2004

Statistical Mechanics Of Farey Fraction Spin Chain Models, Jan Fiala

Electronic Theses and Dissertations

This thesis considers several statistical models defined on the Farey fractions. Two of these models, considered first, may be regarded as "spin chains", with long-range interactions, another arises in the study of multifractals associated with chaotic maps exhibiting intermittency. We prove that these models all have the same free energy. Their thermodynamic behavior is determined by the spectrum of the transfer operator (Ruelle-Perron-F'robenius operator), which is defined using the maps (presentation functions) generating the Farey "tree". The spectrum of this operator was completely determined by Prellberg. It follows that all these models have a second-order phase transition with a specific …

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Sinbad Automation Of Scientific Process: From Hidden Factor Analysis To Theory Synthesis, Olcay Kursun Jan 2004

Sinbad Automation Of Scientific Process: From Hidden Factor Analysis To Theory Synthesis, Olcay Kursun

Electronic Theses and Dissertations

Modern science is turning to progressively more complex and data-rich subjects, which challenges the existing methods of data analysis and interpretation. Consequently, there is a pressing need for development of ever more powerful methods of extracting order from complex data and for automation of all steps of the scientific process. Virtual Scientist is a set of computational procedures that automate the method of inductive inference to derive a theory from observational data dominated by nonlinear regularities. The procedures utilize SINBAD – a novel computational method of nonlinear factor analysis that is based on the principle of maximization of mutual information …

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Depth From Defocused Motion, Zarina Myles Jan 2004

Depth From Defocused Motion, Zarina Myles

Electronic Theses and Dissertations

Motion in depth and/or zooming causes defocus blur. This work presents a solution to the problem of using defocus blur and optical flow information to compute depth at points that defocus when they move. We first formulate a novel algorithm which recovers defocus blur and affine parameters simultaneously. Next we formulate a novel relationship (the blur-depth relationship) between defocus blur, relative object depth and three parameters based on camera motion and intrinsic camera parameters. We can handle the situation where a single image has points which have defocused, got sharper or are focally unperturbed. Moreover, our formulation is valid regardless …

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