Title from PDF of title page. / Document formatted into pages; contains 66 pages. / Thesis (M.S.E.E.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: The rapid growth of technology in recent decades has changed the whole dimension of communications. Today people are more interested in hands-free communication. In such a situation, the use a regular loudspeaker and a high-gain microphone, in place of a telephone receiver, might seem more appropriate. This would allow more than one person to participate in a conversation at the same time such as a teleconference environment. Another advantage is that it would allow the person to have both hands free and to move freely in the room. However, the presence of a large acoustic coupling between the loudspeaker and microphone would produce a loud echo that would make conversation difficult. Furthermore, the acoustic system could become instable, which would produce a loud howling noise to occur. The solution to these problems is the elimination of the echo with an echo suppression or echo cancellation algorithm. / ABSTRACT: The echo suppressor offers a simple but effective method to counter the echo problem. However, the echo suppressor possesses a main disadvantage since it supports only half-duplex communication. Half-duplex communication permits only one speaker to talk at a time. This drawback led to the invention of echo cancellers. An important aspect of echo cancellers is that full-duplex communication can be maintained, which allows both speakers to talk at the same time. This objective of this research was to produce an improved echo cancellation algorithm, which is capable of providing convincing results. The three basic components of an echo canceller are an adaptive filter, a doubletalk detector and a nonlinear processor. The adaptive filter creates a replica of the echo and subtracts it from the combination of the actual echo and the near-end signal. The doubletalk detector senses the doubletalk. / ABSTRACT: Doubletalk occurs when both ends are talking, which stops the adaptive filter in order to avoid divergence. Finally, the nonlinear processor removes the residual echo from the error signal. Usually, a certain amount of speech is clipped in the final stage of nonlinear processing. In order to avoid clipping, a noise gate was used as a nonlinear processor in this research. The noise gate allowed a threshold value to be set and all signals below the threshold were removed. This action ensured that only residual echoes were removed in the final stage. To date, the real time implementation of echo an cancellation algorithm was performed by utilizing both a VLSI processor and a DSP processor. Since there has been a revolution in the field of personal computers, in recent years, this research attempted to implement the acoustic echo canceller algorithm on a natively running PC with the help of the MATLAB software. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Title from PDF of title page. / Document formatted into pages; contains 163 pages. / Thesis (M.S.M.E.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: Robotics in rehabilitation provides considerable opportunities to improve the quality of life for persons with disabilities. Computerized and Virtual Environment (VE) training systems for persons with disabilities, many of which utilize the haptic feedback, have gained increasing acceptance in the recent years. Our methodology here is based on creating virtual environments connected to a haptic interface as an input device. This robotic setup introduces the advantages of the haptic rendering features in the environment and also provides tactile feedback to the patients. This thesis aims to demonstrate the efficacy of assistance function algorithms in rehabilitation robotics in virtual environments. Assist functions are used to map limited human input to motions required to perform complex tasks. The purpose is to train individuals in task-oriented applications to insure that they can be incorporated into the workplace. / ABSTRACT: Further, Hidden Markov Model (HMM) based motion recognition and skill learning are used for improving the skill levels of the users. For the Hidden Markov Model based motion recognition, the user's motion intention is combined with environment information to apply an appropriate assistance function. We used this algorithm to perform a commonly used vocational therapy test referred to as the box and the blocks test. The Hidden Markov Model based skill approach can be used for learning human skill and transferring the skill to persons with disabilities. A relatively complex task of moving along a labyrinth is chosen as the task to be modeled by HMM. This kind of training allows a person with disability to learn the skill and improve it through practice. Its application to motion therapy system using a haptic interface helps in improving their motion control capabilities, tremor reduction and upper limb coordination. / ABSTRACT: The results obtained from all the tests demonstrated that various forms of assistance provided reduced the execution times and increased the motion performance in chosen tasks. Two persons with disabilities volunteered to perform the above tasks and both of the disabled subjects expressed an interest and satisfaction with the philosophy behind these concepts. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Title from PDF of title page. / Document formatted into pages; contains 155 pages. / Thesis (M.S.E.E.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT This research effort advances millimeter-wave transistor modeling in a current RF/Microwave circuit simulator (Agilent's Advanced Design System-ADS) for small-signal noise and large signal simulations. The device modeled is a metamorphic High Electron Mobility Transistor (mHEMT) supplied by Raytheon RF components. Because of their structure, these new low noise devices are used in this work to test the abilities to accurately model in the sub 0.5dB noise figure territory and to study model prediction into W-band (75-110 GHz). New modeling issues discussed in this thesis involve the effects of noise modeling in relation to the small-signal model parameters. The noise modeling identifies two methods of extraction and how to determine good noise data. / ABSTRACT: Other modeling topics addressed are the use of an advanced nonlinear model, and the ability to optimize for gain compression in the nonlinear model. Several measurement systems were used in the extraction and validation of this modeling effort. They consist of the ATN NP5 noise system, Maury Automated Tuner System, Agilent's IC-CAP, and Gateway's Special. The concept behind using these systems was to construct a complete modeling reference for a transistor and validate it against noise parameter and nonlinear measured data. Since the modeling work for this thesis is built on previous work, one goal has been to bring past USF field-effect transistor (FET) modeling efforts up to date and refine them for future use. The noise measurements were compared to results from Raytheon to validate the USF ATN noise parameter measurement system. Also the IC-CAP modeling system has been validated in measuring the test devices using the Maury load-pull system. / ABSTRACT: Small-signal and noise modeling were accomplished using techniques standardized from several technical papers and prior USF Ph.D. work relative to the model extraction. The IC-CAP modeling software also provided a straightforward platform for large-signal model extraction that is documented in this thesis. Using optimization in ADS, a final nonlinear was created. Measured DC, S-parameter, noise parameters, harmonic power, TOI, load-pull, and efficiency measurements were shown to compare well with model data simulated in ADS. Temperature scaling was also executed using a linear approximation of model values over measured temperatures in the noise model. The results presented show that the models developed illustrate good fitting of the behavior of the mHEMT device. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Title from PDF of title page. / Document formatted into pages; contains 123 pages / Thesis (M.A.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: Since gaining independence from Colombia in 1903, Panama has witnessed both elitist democratic governments and authoritarian populist governments. The oligarchic system in place throughout much of Panama's history was a significant hindrance to real democracy taking hold within the country. Democracy was further set back by the inordinate power exerted by the US presence on the isthmus throughout the twentieth century. Omar Torrijos's time as head of the Panamanian government from 1969 to 1981 exhibited populist, paternalistic and personalistic characteristics. His government marked an attempt to establish a form of government based on popular democracy. While a number of social programs were implemented and the social welfare of a greater percentage of the population was generally improved during the years Torrijos was in power, his military regime did not ultimately institutionalize a model for democratic participation. / ABSTRACT: This study argues that some form of popular democracy should replace the status quo in Panama. This would allow for genuine representation of a greater number of the population and in turn broaden the base of decision-making, something that has not been fully accomplished under previous authoritarian or democratic forms of government. The Torrijos regime was the first and only government in Panama to have attempted this move toward popular democracy. As such it is seen as a useful case study in examining its contributions to the political landscape and the political culture that makes up contemporary Panama. Deductions are made from it for the political future of the country in terms of the democratization process. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Title from PDF of title page. / Document formatted into pages; contains 92 pages. / Thesis (M.S.I.E.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: In this research a heuristic algorithm is developed for searching and identifying preferred actions as applied to the bus route design problem. The search routine evaluates each subsequent segment added to the route in the context of the value of that segment and also the value of future decisions and opportunities for subsequent segments. The total overall maximum accessibility of the system is calculated using a minimum path network between each node pair and adding the accessibility of all route segments. This is equivalent to assuming that there was a direct shortest path route between every two destinations in the network. The quality of the designed network is obtained by comparing the share of the total benefits obtained from the heuristic with the share of the costs incurred with respect to a minimum path network. Several test cases and network scenarios are studied to evaluate the analytical tool developed. / ABSTRACT: In addition, different performance measures are used to identify the connecting routes that increase the accessibility of the system. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Includes vita. / Title from PDF of title page. / Document formatted into pages; contains 173 pages. / Thesis (Ph.D.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: N-Methylthio beta-lactams represent a promising new family of antibacterial agents whose in vitro activity is confined largely to Staphylococcus species, including multidrug-resistant forms of S. aureus. Originally developed in the 1980's for use as synthetic intermediates, N-methylthio beta-lactams have recently been shown in these laboratories to possess intriguing biological properties which are addressed in Chapters I-IV. In terms of the antibacterial activities, the structural features and species specificities exhibited by these compounds are unlike those of any existing family of beta-lactam drugs. The lactams seem to exert their effects intracellularly, requiring passage of the bioactive species through the cellular membrane, rather than acting extracellularly on cell wall components in the manner of penicillin and related antibiotics. / ABSTRACT: The lipophilic nature of these molecules, which lack the polar side chain functionality of all other microbially-active Beta-lactams, suggests the compounds do not target the penicillin binding proteins within bacterial membranes. The most active members of this Beta-lactam class appear to be those bearing an aryl (Ar) substituent at C4 of the ring. The synthesis and structure-activity relationship of these analogues is discussed in Chapter III. Moreover, microscopy and 3H pulse-labeling studies, which are described in Chapter IV, demonstrate that N-methylthio beta-lactams appear to be inhibitors of protein biosynthesis. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Includes vita. / Title from PDF of title page. / Document formatted into pages; contains 141 pages. / Thesis (Ph.D.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: The factor structure of the work/family conflict scale developed by Carlson, Kacmar, & Williams (2000) was analyzed for measurement invariance between a US and an Australian/New Zealand (ANZ) sample using a multisample confirmatory factor analysis procedure. Results indicated that factor pattern fit between the female samples on the common model was good-to-mediocre, and factor pattern fit between the male samples and the common model was mediocre-to-poor. Both samples exhibited significant changes in chi square when testing for the more restrictive factor loading equivalence. Partial measurement invariance revealed a better fit between the male samples when three of the items were unconstrained, and when eight items were unconstrained between the female samples. Finally, males and females in the ANZ sample exhibited factor pattern invariance, but required two items to be unconstrained before factor loading invariance was achieved. / ABSTRACT: Mean differences on the six scales revealed higher levels of time-based work interference with family and family interference with work for males than for females in the ANZ sample. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Includes vita. / Title from PDF of title page. / Document formatted into pages; contains 172 pages. / Thesis (PH.D.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: Modeling methods are required for predicting the chemical stability of macromolecular materials used in critical spacecraft components of satellites orbiting in the high-energy radiation environment of near earth and deep space planetary magnetic belts. Methods for establishing degradation mechanisms and predicting and simulating the total absorbed dose and ionization for long term space missions are presented herein. This investigation evaluates cross-linking, main-chain scission and elimination products in a linear series of narrowly dispersed poly(methyl methacrylate) (PMMA) and polystyrene (PS) polymers. A comparison is made of the scission radiation yield (Gs) and crosslinking (Gx) predicted for the simulated ionization data to the results of degradation in a ground-based simulation of the space radiation environment using a 60Co source. / ABSTRACT: The influence of molecular weight on the stability of post-irradiated polymer is evident in the degree of change observed for each molecular weight series with respect to the degradation products produced by exposure to gamma radiation. The analysis of the specific polymer degradation products and changes in the average molecular weight (Mw) were performed using chemical analysis (FTIR and GPC) and thermal analysis (DSC). The analytical results for PMMA and polystyrene radiation-induced degradation products demonstrate that, depending on Mw, the amount and types of degradation products will vary with respect to crosslinking, chain scission and other oxidative pathways. The results support the preference for end group loss with free volume properties driving the observed differences in the G(s) and (Gx) values. / ABSTRACT: The cross-linking observed for polystyrene is controlled by molecular weight as well wherein the lowest molecular weight molecules display greater resistance to cross-linking. This research investigation employs proven tools of analysis (NASA AP8 and AE8) that accurately predict the amount of energy applied to spacecraft materials during a typical near-earth, aggressive mission environment . Another model (SPENVIS) is applied to determine the amount of total energy absorbed by the spacecraft materials from proton, electron and Brehmsstralung radiation throughout the mission life. Another set of models (SRIM and CASINO) are used to asses the range of penetration of particles into the materials and the extent of ionization caused by the particle spectrum and fluence. The absorption coefficients for the PS and PMMA structure are determined to ensure good correlation between ground simulation and the true space environment. / ABSTRACT: The total dose values are used to establish the total dose that is to be deposited during the ground simulation experiments. A 60Co irradiator was used as the ground simulation source. Dosimetry was used to determine the exposure time needed to deposit an equivalent amount of dose accumulation needed to simulate the total dose modeled for the space mission. Using gel permeation chromatography, previous studies have demonstrated that the characteristic Gaussian distribution of narrowly-dispersed PS and PMMA is perturbed by the accumulation of degradation products following irradiation. The change in distribution provides insight into the preferred path of degradation. The role of free volume in the glass transition temperature are reported with respect to Tg variation with molecular weight. Using differential scanning calorimetry. / ABSTRACT: The role of free volume in the determination of the mechanism of radiation-induced degradation is a primary focus of this investigation when considering the ability of the main chain to recombine or undergo abstraction as opposed to crosslinking or scission where motion is restricted in the solid state. The subtle distinction of structural changes brought about by the loss of side groups, double bond formation and crosslinking have been characterized by infrared spectroscopy. The resultant spectra of irradiated polymers offer considerable information on verifying the extent of competing reactions that involve structural features of the molecule. These instrumental methods are the tools of research that will assess the affect of molecular structure on polymer radiation resistance, and will support the rationale explaining the preference for one degradation mechanism over another. / ABSTRACT: This research investigation has yielded information on the affect of polymer molecular structure on radiation resistance. The work goes beyond previous studies that define empirical observations for a change in radiation resistance by virtue of a change in side group. The effect of free volume, stabilized intermediates and reactive intermediates are related to molecular weight and side group functionality. The understanding of the mechanistic rationale behind the effect of structural features on polymer radiation resistance are essential to the development of modeling systems for predicting polymer stability in space mission environments. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Title from PDF of title page. / Document formatted into pages; / Thesis (M.A.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: U.S. fisheries legislation requires National Marine Fisheries Service (NMFS) to attend to the critical social and economic issues surrounding the definition and identification of fishing communities, and to the effects that changes to the physical environment and regulatory decisions can have on such communities. To fulfil their mandate, National Marine Fisheries Service (NMFS) sponsored the research entitled "Identifying Fishing Communities in the Gulf of Mexico" to study the economic, social and cultural status of potential fishing communities along the Gulf of Mexico. NMFS contracted the research project to Impact Assessment, Inc. to study 80 plus potential fishing communities in the Florida Gulf Coast. I worked as an intern in the research and visited the communities with other team members. The task of our project was to provide NMFS with basic profiles of fishing communities for NMFS to develop a culturally appropriated intervention. / ABSTRACT: Research methods include Rapid Assessment Procedures (RAP), semi-structured key informant interviews, participant observation, and archival and secondary research mainly for community histories. Apart from my internship research, I also conducted some additional interviews and observations for my thesis. My findings indicate that fishing communities along the Florida Gulf Coast encounter with challenge from increased regulation, "dumping" seafood imports and virtually uncontrolled waterfront development. By a comparison of three groups of fishing communities, i.e., "diminished communities," "residual communities," and "resilient communities," the thesis explores how communities respond to the challenges and encourages fishermen to take action to preserve their generation-long fishing tradition. / ABSTRACT: In conclusion, the thesis suggests that a solution to ease the decline of fishing communities requires cooperation of all parties concerned, including the fishery regulatory agency, commercial fishermen, and the federal and local government. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Title from PDF of title page. / Document formatted into pages; contains 201 pages. / Thesis (M.S.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: Melongena corona and closely related congeners are a conspicuous part of the marine intertidal benthic communities of Florida and southeastern Alabama. Significant genetic differentiation among adjacent populations has been conjectured based on variation in shell morphology, habitat discontinuity, low levels of adult motility, and the presence of an aplanic lecithotrophic larval stage. Furthermore, studies of the highly variable shell morphology often have resulted in confusing specific and subspecific definitions of these gastropods, which are often referred to as the "corona complex". Variation in shell morphology may indicate local adaptation or environmentally induced phenotypic plasticity. In this study I utilized mitochondrial DNA sequences in order to reconstruct the phylogenetic relationships of crown conchs, and nuclear microsatellite loci to investigate the patterns of relatedness within and among populations inhabiting the southeastern United States. / ABSTRACT: Approximately 500 individuals from 20 populations throughout the known range of the Crown Conch were genotyped at eight microsatellite loci. Additionally, a 1200bp portion of the cytochrome oxidase subunit I gene was sequenced along with a 490bp fragment of the 16s ribosomal gene from individuals representing all known species and subspecies of the genus Melongena. Phylogenetic analyses completed with these data provide no support for current taxonomic designations within this group and these genetic data indicate that the corona complex is composed of a single polymorphic species. Furthermore, microsatellite data reveal population structure consistent with restricted gene flow between extant populations and phylogeography heavily influenced by historical sea-level fluctuations during the Late Pleistocene. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.