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Articles 3331 - 3360 of 4194

Full-Text Articles in Physical Sciences and Mathematics

Optical Solitons In Periodic Structures, Konstantinos Makris Jan 2008

Optical Solitons In Periodic Structures, Konstantinos Makris

Electronic Theses and Dissertations

By nature discrete solitons represent self-trapped wavepackets in nonlinear periodic structures and result from the interplay between lattice diffraction (or dispersion) and material nonlinearity. In optics, this class of self-localized states has been successfully observed in both one-and two-dimensional nonlinear waveguide arrays. In recent years such lattice structures have been implemented or induced in a variety of material systems including those with cubic (Kerr), quadratic, photorefractive, and liquid-crystal nonlinearities. In all cases the underlying periodicity or discreteness leads to new families of optical solitons that have no counterpart whatsoever in continuous systems. In the first part of this dissertation, a …

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Low Noise, High Repetition Rate Semiconductor-Based Mode-Locked Lasers For Signal Processing And Coherent Communications, Franklyn Quinlan Jan 2008

Low Noise, High Repetition Rate Semiconductor-Based Mode-Locked Lasers For Signal Processing And Coherent Communications, Franklyn Quinlan

Electronic Theses and Dissertations

This dissertation details work on high repetition rate semiconductor mode-locked lasers. The qualities of stable pulse trains and stable optical frequency content are the focus of the work performed. First, applications of such lasers are reviewed with particular attention to applications only realizable with laser performance such as presented in this dissertation. Sources of timing jitter are also reviewed, as are techniques by which the timing jitter of a 10 GHz optical pulse train may be measured. Experimental results begin with an exploration of the consequences on the timing and amplitude jitter of the phase noise of an RF source …

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Extended Focus Range High Resolution Endoscopic Optical Coherence Tomography, Kye-Sung Lee Jan 2008

Extended Focus Range High Resolution Endoscopic Optical Coherence Tomography, Kye-Sung Lee

Electronic Theses and Dissertations

Today, medical imaging is playing an important role in medicine as it provides the techniques and processes used to create images of the human body or parts thereof for clinical purposes (medical procedures seeking to reveal, diagnose or examine disease) or medical science (including the study of normal anatomy and function). Modalities are developing over time to achieve the highest possible resolution, speed of image acquisition, sensitivity, and specificity. In the past decade, advances in optics, fiber, as well as laser technology have enabled the development of noninvasive optical biomedical imaging technology that can also be applied to endoscopy to …

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Stable Optical Frequency Comb Generation And Applications In Arbitrary Waveform Generation, Signal Processing And Optical Data M, Sarper Ozharar Jan 2008

Stable Optical Frequency Comb Generation And Applications In Arbitrary Waveform Generation, Signal Processing And Optical Data M, Sarper Ozharar

Electronic Theses and Dissertations

This thesis focuses on the generation and applications of stable optical frequency combs. Optical frequency combs are defined as equally spaced optical frequencies with a fixed phase relation among themselves. The conventional source of optical frequency combs is the optical spectrum of the modelocked lasers. In this work, we investigated alternative methods for optical comb generation, such as dual sine wave phase modulation, which is more practical and cost effective compared to modelocked lasers stabilized to a reference. Incorporating these comblines, we have generated tunable RF tones using the serrodyne technique. The tuning range was ±1 MHz, limited by the …

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Detecting Curved Objects Against Cluttered Backgrounds, Jan Prokaj Jan 2008

Detecting Curved Objects Against Cluttered Backgrounds, Jan Prokaj

Electronic Theses and Dissertations

Detecting curved objects against cluttered backgrounds is a hard problem in computer vision. We present new low-level and mid-level features to function in these environments. The low-level features are fast to compute, because they employ an integral image approach, which makes them especially useful in real-time applications. The mid-level features are built from low-level features, and are optimized for curved object detection. The usefulness of these features is tested by designing an object detection algorithm using these features. Object detection is accomplished by transforming the mid-level features into weak classifiers, which then produce a strong classifier using AdaBoost. The resulting …

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Automated Regression Testing Approach To Expansion And Refinement Of Speech Recognition Grammars, Raul Dookhoo Jan 2008

Automated Regression Testing Approach To Expansion And Refinement Of Speech Recognition Grammars, Raul Dookhoo

Electronic Theses and Dissertations

This thesis describes an approach to automated regression testing for speech recognition grammars. A prototype Audio Regression Tester called ART has been developed using Microsoft's Speech API and C#. ART allows a user to perform any of three tasks: automatically generate a new XML-based grammar file from standardized SQL database entries, record and cross-reference audio files for use by an underlying speech recognition engine, and perform regression tests with the aid of an oracle grammar. ART takes as input a wave sound file containing speech and a newly created XML grammar file. It then simultaneously executes two tests: one with …

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Phase-Shifting Haar Wavelets For Image-Based Rendering Applications, Mais Alnasser Jan 2008

Phase-Shifting Haar Wavelets For Image-Based Rendering Applications, Mais Alnasser

Electronic Theses and Dissertations

In this thesis, we establish the underlying research background necessary for tackling the problem of phase-shifting in the wavelet transform domain. Solving this problem is the key to reducing the redundancy and huge storage requirement in Image-Based Rendering (IBR) applications, which utilize wavelets. Image-based methods for rendering of dynamic glossy objects do not truly scale to all possible frequencies and high sampling rates without trading storage, glossiness, or computational time, while varying both lighting and viewpoint. This is due to the fact that current approaches are limited to precomputed radiance transfer (PRT), which is prohibitively expensive in terms of memory …

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Improving Branch Prediction Accuracy Via Effective Source Information And Prediction Algorithms, Hongliang Gao Jan 2008

Improving Branch Prediction Accuracy Via Effective Source Information And Prediction Algorithms, Hongliang Gao

Electronic Theses and Dissertations

Modern superscalar processors rely on branch predictors to sustain a high instruction fetch throughput. Given the trend of deep pipelines and large instruction windows, a branch misprediction will incur a large performance penalty and result in a significant amount of energy wasted by the instructions along wrong paths. With their critical role in high performance processors, there has been extensive research on branch predictors to improve the prediction accuracy. Conceptually a dynamic branch prediction scheme includes three major components: a source, an information processor, and a predictor. Traditional works mainly focus on the algorithm for the predictor. In this dissertation, …

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Vcluster: A Portable Virtual Computing Library For Cluster Computing, Hua Zhang Jan 2008

Vcluster: A Portable Virtual Computing Library For Cluster Computing, Hua Zhang

Electronic Theses and Dissertations

Message passing has been the dominant parallel programming model in cluster computing, and libraries like Message Passing Interface (MPI) and Portable Virtual Machine (PVM) have proven their novelty and efficiency through numerous applications in diverse areas. However, as clusters of Symmetric Multi-Processor (SMP) and heterogeneous machines become popular, conventional message passing models must be adapted accordingly to support this new kind of clusters efficiently. In addition, Java programming language, with its features like object oriented architecture, platform independent bytecode, and native support for multithreading, makes it an alternative language for cluster computing. This research presents a new parallel programming model …

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A Framework For Efficient Data Distribution In Peer-To-Peer Networks., Darshan Purandare Jan 2008

A Framework For Efficient Data Distribution In Peer-To-Peer Networks., Darshan Purandare

Electronic Theses and Dissertations

Peer to Peer (P2P) models are based on user altruism, wherein a user shares its content with other users in the pool and it also has an interest in the content of the other nodes. Most P2P systems in their current form are not fair in terms of the content served by a peer and the service obtained from swarm. Most systems suffer from free rider's problem where many high uplink capacity peers contribute much more than they should while many others get a free ride for downloading the content. This leaves high capacity nodes with very little or no …

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Appearance-Driven Material Design, Mark Colbert Jan 2008

Appearance-Driven Material Design, Mark Colbert

Electronic Theses and Dissertations

In the computer graphics production environment, artists often must tweak specific lighting and material parameters to match a mind's eye vision of the appearance of a 3D scene. However, the interaction between a material and a lighting environment is often too complex to cognitively predict without visualization. Therefore, artists operate in a design cycle, where they tweak the parameters, wait for a visualization, and repeat, seeking to obtain a desired look. We propose the use of appearance-driven material design. Here, artists directly design the appearance of reflected light for a specific view, surface point, and time. In this thesis, we …

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Evaluation Of An Augmentation Of Rocky Mountain Bighorn Sheep At Badlands National Park, South Dakota, Teresa J. Zimmerman Jan 2008

Evaluation Of An Augmentation Of Rocky Mountain Bighorn Sheep At Badlands National Park, South Dakota, Teresa J. Zimmerman

Electronic Theses and Dissertations

Audubon’s (a.k.a. Badlands) bighorn (Ovis canadensis auduboni [Merriam 1901] now O. c. Canadensis [Shaw 1804]), described as a subspecies of bighorn sheep, was extirpated from its range by 1924. In 1964, 22 Rocky Mountain bighorn sheep were translocated from Pikes Peak, Colorado, to Badlands National Park (BNP) in southwestern South Dakota. Based on the estimated effective population size and analysis of molecular data, the bighorn sheep population at BNP underwent a population bottleneck at founding. Recommendations to restore genetic diversity in the BNP population included a mixed-sex augmentation (n > 30) from an outbred, native population of Rocky Mountain bighorn sheep. …

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Nesting And Brood-Rearing Success And Resource Selection Of Greater Sage-Grouse In Northwestern South Dakota, Nicholas W. Kaczor Jan 2008

Nesting And Brood-Rearing Success And Resource Selection Of Greater Sage-Grouse In Northwestern South Dakota, Nicholas W. Kaczor

Electronic Theses and Dissertations

Understanding population dynamics and resource selection is crucial in developing wildlife resource management plans, particularly for sensitive species. Greater sage-grouse (Centrocercus urophasianus) populations have declined range-wide at a rate of 2% per year from 1965 to 2003. In South Dakota, populations have generally declined. Reasons for the decline are mostly attributed to human-induced factors such as sagebrush degradation and removal, improper range management practices, oil and gas exploration, and West Nile virus infection. Sage-grouse occupy habitats at the eastern edge of their range in western South Dakota. We conducted a 2-year study to investigate the nesting and brood-rearing ecology of …

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Methodology And Assessment Of The Susceptibility Of Potato Genotypes To Phytophthora Erythrosetpica Causal Organism Of Pink Rot, Erica Fitzpatrick-Peabody Jan 2008

Methodology And Assessment Of The Susceptibility Of Potato Genotypes To Phytophthora Erythrosetpica Causal Organism Of Pink Rot, Erica Fitzpatrick-Peabody

Electronic Theses and Dissertations

Phytophthora erythroseptica Pethyb., causal organism of potato (Solanum tuberosum L.) pink rot is a soil-borne ubiquitous oomycete pathogen that can cause severe losses in both the field prior to harvest and during storage. The efficacy of the most effective fungicide, mefenoxam for control of P. erythroseptica is in jeopardy due to the widespread development of resistance in the US. Cultivar resistance may provide the best option for management of P. erythroseptica in the future. Recently published reports of cultivars susceptible to P. erythroseptica are based on evaluation techniques involving detached tubers and nontuber germplasm rather than field evaluations. Screening detached …

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On The Stochastic Behavior Of Brownian Particles In Potential Wells, As Observed With Optical Traps, Ross Paul Brody Jan 2008

On The Stochastic Behavior Of Brownian Particles In Potential Wells, As Observed With Optical Traps, Ross Paul Brody

Electronic Theses and Dissertations

When the random fluctuations of a system are viewed as energetic fluctuations, many of the unique qualities of the system become irrelevant to the fundamental behavior. Consequently, many stochastic processes are fundamentally identical and are treated mathematically as such. For this reason the study of colloidal particles in aqueous solution has been invaluable to investigations of biologically relevant stochastic processes. This work addresses the motion of a Brownian particle, in a potential well, whose random fluctuations are described by a Gaussian-Markov random variable. By performing optical trapping experiments on micron sized, non-interacting, latex spheres in aqueous solution we have shown …

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Packings And Coverings Of Various Complete Digraphs With The Orientations Of A 4-Cycle., Melody Elaine Cooper Dec 2007

Packings And Coverings Of Various Complete Digraphs With The Orientations Of A 4-Cycle., Melody Elaine Cooper

Electronic Theses and Dissertations

There are four orientations of cycles on four vertices. Necessary and sufficient conditions are given for covering complete directed digraphs Dv, packing and covering complete bipartite digraphs, Dm,n, and packing and covering the complete digraph on v vertices with hole of size w, D(v,w), with three of the orientations of a 4-cycle, including C4, X, and Y.

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Decomposition, Packings And Coverings Of Complete Digraphs With A Transitive-Triple And A Pendant Arc., Janice Gail Lewenczuk Dec 2007

Decomposition, Packings And Coverings Of Complete Digraphs With A Transitive-Triple And A Pendant Arc., Janice Gail Lewenczuk

Electronic Theses and Dissertations

In the study of design theory, there are eight orientations of the complete graph on three vertices with a pendant edge, K3∪{e}. Two of these are the 3-circuit with a pendant arc and the other six are transitive triples with a pendant arc. Necessary and sufficient conditions are given for decompositions, packings and coverings of the complete digraph with each of the six transitive triples with a pendant arc.

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Examining Significant Differences Of Gunshot Residue Patterns Using Same Make And Model Of Firearms In Forensic Distance Determination Tests., Heather Lewey Dec 2007

Examining Significant Differences Of Gunshot Residue Patterns Using Same Make And Model Of Firearms In Forensic Distance Determination Tests., Heather Lewey

Electronic Theses and Dissertations

In many cases of crimes involving a firearm, police investigators need to know how far the firearm was held from the victim when it was discharged. Knowing this distance, vital questions regarding the re-construction of the crime scene can be known. Often, the original firearm used in commission of a suspected crime is not available for testing or is damaged. Crime laboratories require the original firearm in order to conduct distance determination tests. However, no empirical research has ever been conducted to determine if same make and model firearms produce different results in distance determination testing. It was the purpose …

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Probability And Statistics For Third Through Fifth Grade Classrooms., Melissa Taylor Mckinnon Dec 2007

Probability And Statistics For Third Through Fifth Grade Classrooms., Melissa Taylor Mckinnon

Electronic Theses and Dissertations

This document contains a variety of lesson plans that can be readily used by a teacher of intermediate students. This thesis contains two units in Probability and one unit in Statistics. Any educator can supplement this document with any curriculum to teach lessons from vocabulary to concept.

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New Technique For Imputing Missing Item Responses For An Ordinal Variable: Using Tennessee Youth Risk Behavior Survey As An Example., Andaleeb Abrar Ahmed Dec 2007

New Technique For Imputing Missing Item Responses For An Ordinal Variable: Using Tennessee Youth Risk Behavior Survey As An Example., Andaleeb Abrar Ahmed

Electronic Theses and Dissertations

Surveys ordinarily ask questions in an ordinal scale and often result in missing data. We suggest a regression based technique for imputing missing ordinal data. Multilevel cumulative logit model was used with an assumption that observed responses of certain key variables can serve as covariate in predicting missing item responses of an ordinal variable. Individual predicted probabilities at each response level were obtained. Average individual predicted probabilities for each response level were used to randomly impute the missing responses using a uniform distribution. Finally, likelihood ratio chi square statistics was used to compare the imputed and observed distributions. Two other …

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Self-Management Of Type 2 Diabetes In Appalachina Women., Melissa Joy Magness Dec 2007

Self-Management Of Type 2 Diabetes In Appalachina Women., Melissa Joy Magness

Electronic Theses and Dissertations

Gender, minority, and regional-related disparities have been documented in diabetes management. Self-efficacy, the belief in one's ability to carry out the actions mandated by a task, has been identified as a key predictor in glycemic control; however, it has not been investigated in rural, female populations. This cross-sectional, correlation investigation examined the relationships among self-efficacy, depression, and diabetes self-care management in women living in Appalachia with type 2 diabetes. Using Bandura's Social Cognitive Theory, 85 women ages ≥ 21 with type 2 diabetes for a minimum of 6 months who were residents in Appalachia completed the 1) Diabetes Self-Efficacy Scale, …

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Chromatic Number Of The Alphabet Overlap Graph, G(2, K , K-2)., Jerry Brent Farley Dec 2007

Chromatic Number Of The Alphabet Overlap Graph, G(2, K , K-2)., Jerry Brent Farley

Electronic Theses and Dissertations

A graph G(a, k, t) is called an alphabet overlap graph where a, k, and t are positive integers such that 0 ≤ t < k and the vertex set V of G is defined as, V = {v : v = (v1v2...vk); vi ∊ {1, 2, ..., a}, (1 ≤ i ≤ k)}. That is, each vertex, v, is a word of length k over an alphabet of size a. There exists an edge between two vertices u, …

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Combining Geospatial And Temporal Ontologies, Kripa Joshi Dec 2007

Combining Geospatial And Temporal Ontologies, Kripa Joshi

Electronic Theses and Dissertations

Publicly available ontologies are growing in number at present. These ontologies describe entities in a domain and the relations among these entities. This thesis describes a method to automatically combine a pair of orthogonal ontologies using cross products. A geospatial ontology and a temporal ontology are combined in this work. Computing the cross product of the geospatial and the temporal ontologies gives a complete set of pairwise combination of terms from the two ontologies. This method offers researchers the benefit of using ontologies that are already existing and available rather than building new ontologies for areas outside their scope of …

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Linking Moving Object Databases With Ontologies, Kraig King Dec 2007

Linking Moving Object Databases With Ontologies, Kraig King

Electronic Theses and Dissertations

This work investigates the supporting role of ontologies for supplementing the information contained in moving object databases. Details of the spatial representation as well as the sensed location of moving objects are frequently stored within a database schema. However, this knowledge lacks the semantic detail necessary for reasoning about characteristics that are specific to each object. Ontologies contribute semantic descriptions for moving objects and provide the foundation for discovering similarities between object types. These similarities can be drawn upon to extract additional details about the objects around us. The primary focus of the research is a framework for linking ontologies …

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Technical Evaluation Of Hardwood Biorefinery Using The "Near-Neutral" Hemicellulose Extraction Process, Haibo Mao Dec 2007

Technical Evaluation Of Hardwood Biorefinery Using The "Near-Neutral" Hemicellulose Extraction Process, Haibo Mao

Electronic Theses and Dissertations

A technical analysis was performed for a new process that produces ethanol and acetic acid from hardwood in addition to bleached hardwood Kraft pulp. The new process, termed the "near neutral" hemicellulose extraction process, involves the extraction of wood hemicellulose using green liquor prior to conventional Kraft pulping. This thesis assumes that the new process is located at an existing kraft pulp mill. Ancillary unit operations in the process include hydrolysis of the extracted carbohydrates using sulfuric acid, filtration of the extract to remove lignin that was extracted with the carbohydrates, liquid-liquid extraction of acetic acid and by-product furfural, liming …

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Sharing A Landscape: The Construction Of Sense Of Place On The Maine Coast, Andrea Jane Ednie Dec 2007

Sharing A Landscape: The Construction Of Sense Of Place On The Maine Coast, Andrea Jane Ednie

Electronic Theses and Dissertations

Motivated by interest and concern over the changing coastline in Maine, this study uses the concept of sense of place to develop an understanding of how a range of users share the resource, and to explore how place meanings are associated with their social experiences and perceptions. The site for this study was the Stonington region archipelago, an area that has not yet experienced the same amount of development as seen on the southern Maine coast, yet one that has witnessed a boom in recreational use and an influx of people from other areas. Using a mixed methodology, two groups …

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Mechanics Of Burrowing In Muddy Sediments, Kelly M. Dorgan Dec 2007

Mechanics Of Burrowing In Muddy Sediments, Kelly M. Dorgan

Electronic Theses and Dissertations

Marine muds are elastic solids through which animals move by propagating a crack-shaped burrow. Dilations previously considered anchors serve to exert dorsoventral compressive stresses on the burrow walls that, through elastic behavior of the medium, focus strongly at the tip of the burrow. This focused stress breaks adhesive or cohesive bonds, propagating a crack for the animal to follow. The force exerted by the polychaete, Nereis virens, to propagate a crack has been measured in gelatin, an analogue of muddy sediment, through photoelastic stress analysis. Finite element analysis was used to convert measured forces to those exerted in natural sediments …

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Confidence Intervals For Population Size In A Capture-Recapture Problem., Xiao Zhang Aug 2007

Confidence Intervals For Population Size In A Capture-Recapture Problem., Xiao Zhang

Electronic Theses and Dissertations

In a single capture-recapture problem, two new Wilson methods for interval estimation of population size are derived. Classical Chapman interval, Wilson and Wilson-cc intervals are examined and compared in terms of their expected interval width and exact coverage properties in two models. The new approach performs better than the Chapman in each model. Bayesian analysis also gives a different way to estimate population size.

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A Statistical Evaluation Of Algorithms For Independently Seeding Pseudo-Random Number Generators Of Type Multiplicative Congruential (Lehmer-Class)., Robert Grisham Stewart Aug 2007

A Statistical Evaluation Of Algorithms For Independently Seeding Pseudo-Random Number Generators Of Type Multiplicative Congruential (Lehmer-Class)., Robert Grisham Stewart

Electronic Theses and Dissertations

To be effective, a linear congruential random number generator (LCG) should produce values that are (a) uniformly distributed on the unit interval (0,1) excluding endpoints and (b) substantially free of serial correlation. It has been found that many statistical methods produce inflated Type I error rates for correlated observations. Theoretically, independently seeding an LCG under the following conditions attenuates serial correlation: (a) simple random sampling of seeds, (b) non-replicate streams, (c) non-overlapping streams, and (d) non-adjoining streams. Accordingly, 4 algorithms (each satisfying at least 1 condition) were developed: (a) zero-leap, (b) fixed-leap, (c) scaled random-leap, and (d) unscaled random-leap. Note …

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Tricyclic Steiner Triple Systems With 1-Rotational Subsystems., Quan Duc Tran Aug 2007

Tricyclic Steiner Triple Systems With 1-Rotational Subsystems., Quan Duc Tran

Electronic Theses and Dissertations

A Steiner triple system of order v, denoted STS(v), is said to be tricyclic if it admits an automorphism whose disjoint cyclic decomposition consists of three cycles. In this thesis we give necessary and sufficient conditions for the existence of a tricyclic STS(v) when one of the cycles is of length one. In this case, the STS(v) will contain a subsystem which admits an automorphism consisting of a fixed point and a single cycle. The subsystem is said to be 1-rotational.

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