Thesis (M.S.) --University of Texas Graduate School of Biomedical Sciences at San Antonio, 2008. / Vita. Includes bibliographical references.

This thesis provides a detailed analysis of the feasibility of voluntary moral bioenhancement through an ethico-legal exploration of three motivators: money (and financial incentives in general), health, and duty. These motivators are explored in turn over the course of three papers and it is concluded that while none offer a motivator that could encourage broad participation in voluntary programmes of moral bioenhancement, they do provide insight into things that will be important to note in advance of the advent of such an intervention and (especially) of attempts to promote it. In addition, this thesis identifies and explores areas of discussion not previously addressed in the literature, including issues such as: taboo trade-offs in the use of financial incentives to promote participation in programmes of moral bioenhancement, the use of medical definitions in order to classify moral bioenhancement interventions as medically indicated, and the question as to whether there could be a duty to undergo moral bioenhancement interventions. Moral bioenhancement, though currently a hypothetical notion, is considered by many to be a desirable endeavour due to its potential to bring about good consequences and to avoid instances of significant and even ultimate harm. However, unlike other enhancements, moral bioenhancement is something that does not seem to directly benefit the enhanced individual and so there are concerns that people would be disinclined to undergo the intervention. Some writers have proposed that this therefore demonstrates a need for compulsory approaches to the endeavour, but in the introductory chapters of this thesis I demonstrate that such an approach would be ethically and legally problematic and, therefore, a voluntary approach would be required. If moral bioenhancement is considered as something that is good to have (and it seems that such a case can be made, certainly on a societal level), then a method of encouraging participation in programmes of the endeavour will be required. This thesis aims to identify that method by exploring the three possible motivators already mentioned and, in doing so, to analyse the feasibility of voluntary moral bioenhancement in a broader sense.

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Motivated by the problem of improving the performance of speech enhancement algorithms in non-stationary acoustic environments with low SNR, a framework is proposed for identifying signal frames of noisy speech that are unlikely to contain voice activity. Such voice-inactive frames can then be incorporated into an adaptation strategy to improve the performance of existing speech enhancement algorithms. This adaptive approach is applicable to single-channel as well as multi-channel algorithms for noisy speech. In both cases, the adaptive versions of the enhancement algorithms are observed to improve SNR levels by 20dB, as indicated by PESQ and WER criteria. In advanced speech enhancement algorithms, it is often of interest to identify some regions of the signal that have a high likelihood of being noise only i.e. no speech present. This is in contrast to advanced speech recognition, speaker recognition, and pitch tracking algorithms in which we are interested in identifying all regions that have a high likelihood of containing speech, as well as regions that have a high likelihood of not containing speech. In other terms, this would mean minimizing the false positive and false negative rates, respectively. In the context of speech enhancement, the identification of some speech-absent regions prompts the minimization of false positives while setting an acceptable tolerance on false negatives, as determined by the performance of the enhancement algorithm. Typically, Voice Activity Detectors (VADs) are used for identifying speech absent regions for the application of speech enhancement. In recent years a myriad of Deep Neural Network (DNN) based approaches have been proposed to improve the performance of VADs at low SNR levels by training on combinations of speech and noise. Training on such an exhaustive dataset is combinatorically explosive. For this dissertation, we propose a voice inactivity ranking framework, where the identification of voice-inactive frames is performed using a machine learning (ML) approach that only uses clean speech utterances for training and is robust to high levels of noise. In the proposed framework, input frames of noisy speech are ranked by ‘voice inactivity score’ to acquire definitely speech inactive (DSI) frame-sequences. These DSI regions serve as a noise estimate and are adaptively used by the underlying speech enhancement algorithm to enhance speech from a speech mixture. The proposed voice-inactivity ranking framework was used to perform speech enhancement in single-channel and multi-channel systems. In the context of microphone arrays, the proposed framework was used to determine parameters for spatial filtering using adaptive beamformers. We achieved an average Word Error Rate (WER) improvement of 50% at SNR levels below 0dB compared to the noisy signal, which is 7±2.5% more than the framework where state-of-the-art VAD decision was used for spatial filtering. For monaural signals, we propose a multi-frame multiband spectral-subtraction (MF-MBSS) speech enhancement system utilizing the voice inactivity framework to compute and update the noise statistics on overlapping frequency bands. The proposed MF-MBSS not only achieved an average PESQ improvement of 16% with a maximum improvement of 56% when compared to the state-of-the-art Spectral Subtraction but also a 5 ± 1.5% improvement in the Word Error Rate (WER) of the spatially filtered output signal, in non-stationary acoustic environments.

Deep learning, usually built upon artificial neural networks, was proposed in 1943, but poor computational capability restricted its development at that time. With the advancement of computer architecture and chip design, deep learning gains sufficient computational power and has revolutionized many areas in computer vision. As a fundamental research area of computer vision, video enhancement often serves as the first step of many modern vision systems and facilitates numerous downstream vision tasks. This thesis provides a comprehensive study of video enhancement, especially in the sense of video frame interpolation and space-time video super-resolution. For video frame interpolation, two novel methods, named GDConvNet and VFIT, are proposed. In GDConvNet, a novel mechanism named generalized deformable convolution is introduced in order to overcome the inaccuracy flow estimation issue in the flow-based methods and the rigidity issue of kernel shape in the kernel-based methods. This mechanism can effectively learn motion information in a data-driven manner and freely select sampling points in space-time. Our GDConvNet, built upon this mechanism, is shown to achieve state-of-the-art performance. As for VFIT, the concept of local attention is firstly introduced to video interpolation, and a novel space-time separation window-based self-attention scheme is further devised, which not only saves costs but acts as a regularization term to improve the performance. Based on the new scheme, VFIT is presented as the first Transformer-based video frame interpolation framework. In addition, a multi-scale frame synthesis scheme is developed to fully realize the potential of Transformers. Extensive experiments on a variety of benchmark datasets demonstrate the superiority and liability of VFIT. For space-time video super-resolution, a novel unconstrained space-time video super-resolution network is proposed to solve the common issues of the existing methods that either fail to explore the intrinsic relationship between temporal and spatial information or lack flexibility in the choice of final temporal/spatial resolution. To this end, several new ideas are introduced, such as integration of multi-level representations and generalized pixshuffle. Various experiments validate the proposed method in terms of its complete freedom in choosing output resolution, as well as superior performance over the state-of-the-art methods. / Thesis / Doctor of Philosophy (PhD)

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Human activities are causing a global loss of plant and animal species, degrading ecosystem properties and threatening ecosystem services. One indicator of these losses is the increasing proportion of fish stocks in decline, and the Challenger oyster fishery in Tasman Bay, central New Zealand is an example of one such fishery. Anthropogenic effects from land-based activities, and towed-gear fishing have been implicated as contributors to the decline of shellfisheries and degradation of the marine ecosystem in Tasman Bay. Increased sedimentation in the bay caused by soil erosion and runoff associated with forestry, agriculture and subdivision is likely to have a range of negative effects on the benthic community. Also towed-gear fishing, dredging and trawling homogenise benthic habitat structure (reduce habitat heterogeneity) and facilitate sediment resuspension as well as causing removal and direct physical damage to benthic biota. There is an imperative to seek to mitigate these effects and look at ways to restore the benthic community including the commercial shellfish species. In this context, my central hypothesis was that enhancement of the benthic habitat by returning waste shell to the seabed would increase oyster production for the fishery. Related to this main goal of oyster fishery enhancement, a primary objective of the study was to fill knowledge gaps relating to the biology and ecology of the oyster in Tasman Bay. The second main topic of my thesis was to investigate how this form of habitat enhancement would alter the benthic community structure, and potentially aid in restoration of the wider ecosystem in the bay. I sought to link the twin goals of fishery enhancement and ecological restoration by considering potential management measures to promote a sustainable oyster fishery and at the same time facilitate ecological restoration within Tasman Bay. The investigations focused on four main themes: temporal patterns of oyster larval abundance, spatial patterns of spatfall and larval dispersal, effects of habitat enhancement on oyster population productivity, and effects of habitat enhancement on the benthic faunal community. Laboratory and field studies were conducted between October 2004 and May 2009. A peak period of oyster reproductive activity began in late spring and continued through summer in each year. Maximum rates of adult oysters brooding larvae were 17% in November 2004 and 2005, and 23 % in December 2006. Over the entire summer breeding period it was estimated that 55 to 78 % of adult oysters incubated larvae. A very low level of brooding activity (1 %) occurred during winter. Temporal trends in larval settlement closely tracked brooding patterns. Settlement on collectors deployed in Tasman Bay was greatest between November and January, and there were very low rates in winter. Results are useful in optimising the timing of substratum deployment in an enhancement program for the oyster fishery. Spat settlement density was strongly related to background adult oyster density. Spat settlement on experimental arrays deployed through the water column only occurred within a narrow vertical range very close to (<1 m above) the seabed. If suitable habitat is available for settlement, oysters tend to settle within a few hours after release, but approximately half of the larvae settled in a laboratory experiment were capable of remaining viable for several days. Oyster distribution assessed at the scale of the shellfishing industry’s annual biomass survey (median distance between sample tows ~ 1 km) is adequate to broadly predict spat settlement distribution in the subsequent settlement season, and the distribution of mature oysters is a key determinant in the placement of shell for habitat enhancement to maximise spat settlement. Deployment of waste whole scallop shell on the seabed as settlement substratum increased oyster spat density significantly. Available settlement surface on enhanced shell plots decreased by 82% in the five months after deployment, due to fouling by numerous invertebrates and sedimentation. Survival of oysters recruited to enhanced habitat was generally very low, and varied greatly among 4 experimental sites and through time. After 3+ years, survival among site/treatment combinations ranged from 0% to 0.04%. At the site where survival was greatest, the absolute density of oysters surviving to 3.41 years on enhanced habitat was estimated as 0.4 m⁻². This equated to an increase in relative density of commercial sized oysters from ~0.01 m⁻² prior to enhancement, to ~0.14 m⁻² at the end of the experiment, and demonstrated that habitat enhancement can elevate adult oyster densities to commercial levels on areas of seabed where oysters were previously below threshold densities for commercial fishing (0.02 m⁻²). Peaks in mortality occurred within experimental plots when oysters were less than one year old, and three years old. Growth modeling indicated that after 4.25 years, 98% of living oysters would attain legal size (≥ 58mm length), and 92% would attain sufficient shell depth (≥ 20 mm) to provide high grade (grade A in the industry) meat. Shell depth was a better morphometric predictor of meat weight than either shell height or shell length. The species assemblages on the shell-enhanced habitat were distinct from those on adjacent non-enhanced seabed. Measures of taxonomic and functional richness, faunal densities, and taxonomic redundancy within functional groups all increased in enhanced habitat. Beta and gamma diversity also increased due to patchiness of the habitat created within enhanced experimental sites. Large scale habitat enhancement in Tasman Bay via the deposition of waste shell on the seabed is likely to confer benefits to ecosystem function associated with those community level effects. To sustain an oyster fishery in Tasman Bay, an ecosystem-based approach to fishery management is recommended to facilitate restoration of benthic habitats and communities and to help maintain ecosystem function supporting all components of the benthic community, including the oyster population. Planning and implementation of a combination of specific management measures including habitat enhancement, rotational fishing, permanent exclusion of towed fishing gear from a network of protected areas, and integration of the management of the oyster, scallop, and finfish fisheries would provide the best chance for restoration and maintenance of a sustainable oyster fishery.

Pedestrian detection is one of the most researched areas in computer vision and is rapidly gaining importance with the emergence of autonomous vehicles and steering assistance technology. Much work has been done in this field, ranging from the collection of extensive datasets to benchmarking of new technologies, but all the research depends on high-quality hardware such as high-resolution cameras, Light Detection and Ranging (LIDAR) and radar. For detection in low-quality moving camera videos, we use image deblurring techniques to reconstruct image frames and use existing pedestrian detection algorithms and compare our results with the leading research done in this area.

The increased use of personal communication devices, personal computers and wireless cellular telephones enables the development of new inter-personal communication systems. The merge between computers and telephony technologies brings up the demand for convenient hands-free communications. In such systems the users wish to lead a conversation in much the same way as in a normal person-to-person conversation. The advantages of hands-free telephones are safety, convenience and greater flexibility. In many countries and regions, hand held telephony in cars is prohibited by legislation. By placing the microphone far away from the user a number of disadvantages are introduced, which results in substantial speech distortion and poor sound quality. These disturbances are mainly caused by room reverberation and background noise. Furthermore, acoustic feedback generated at the near-end side is a problem for the far-end side talker, who will hear his/her own voice echoed with 100-200 ms delay, making speech conversation substantially more difficult. Digital filtering may be used to obtain a similar sound quality as for hand held telephony. Three major tasks must be addressed in order to improve the quality of hands-free communication systems; noise suppression, room reverberation suppression, and acoustic feedback cancellation of the hands-free loudspeaker. The filtering operation must perform the above mentioned tasks without causing severe near-end speech distortion. A properly designed broad-band microphone array is able to perform all the given tasks, i.e. speech enhancement, echo cancellation and reverberation suppression, in a concise and effective manner. This is due to the fact that the spatial domain may be utilized as well as the temporal domain. This thesis deals with the problem of specification and design of beamformers used to extract the source signal information. A new subband adaptive beamforming algorithm is proposed, where many of the drawbacks embedded in conventional adaptive beamforming are eliminated. Evaluation in a car hands-free situation show the benefits of the proposed method. Blind signal separation is discussed and a new structure based on frequency domain inverse channel identification and time domain separation, is proposed. Further, filter-bank properties and design are discussed together with performance limitations in subband beamforming structures. / Avhandlingen behandlar specifikation och konstruktion av mikrofon-arrayer för att extrahera talinformation. En ny adaptiv delbands beamforming-algoritm föreslås där många av nackdelarna hos konventionella adaptiva beamformers är eliminerade. En utvärdering i en bil med ett frihands-system bekräftar fördelarna med den föreslagna metoden. Blind signal-separation diskuteras och en ny struktur föreslås, baserad på en inverterande kanalidentifiering utförd i frekvensdomän med en kontinuerlig separation utförd i tidsdomän. Filterbanks-egenskaper och designmetoder diskuteras tillsammans med begränsningar som finns i beamforming-strukturer utförda i delband.