A compressão nas flutuações da diferença de intensidades dos feixes sinal e complementar gerados por um OPO acima do limiar foi medida já há algum tempo e constituiu um dos principais interesses nestes sistemas. Emaranhamento entre esses feixes, entretanto, ainda não foi experimentalmente demonstrado em circunstâncias normais de operação acima do limiar (feixes não-degenerados em frequência). Usando um critério de não-separabilidade entre sistemas contínuos, buscamos verificar se a variância de um par de operadores tipo EPR, a diferençaa de intensidades e a soma das fases de sinal e complementar, pode violar uma desigualdade suficiente para caracterizar emaranhamento. Após um estudo teórico, verificamos que isto pode de fato ocorrer numa região de parâmetros experimentalmente acessível. A medida não foi realizada até hoje devido à dificuldade em se medir quadratura fase, o que, neste caso, exigiria o uso de osciladores locais em frequências distintas. Motivados por isso, propomos uma montagem experimental que utiliza cavidades óticas para projetar ruído de fase em ruído de intensidade, tornando dessa forma acessível a medida de anticorrelação de fase entre sinal e complementar. Realizamos nossa proposta em caráter preliminar, obtendo resultados encorajadores, embora não conclusivos, que indicam a existência de emaranhamento. / Squeezing in the intensity difference of signal and idler beams generated by an OPO operating above threshold was observed some time ago and presented one of the major attraction of this system. Entanglement between the macroscopic fields, however, has not yet been demonstrated in normal operation conditions above threshold (non-degenerate beams). Using a non-separability criterion for continuous variables, we investigate whether the variances of a pair of EPR-like operators, difference of intensities and sum of phases of signal and idler, can violate a Bell-type inequality and hence characterize entanglement. After a theoretical study, we verified that entanglement can occur in an experimentally accessible region of parameters. This measurement was not performed to date owing to the difficulty of measuring the phase quadratures, which usually requires the use of local oscillators with slightly different frequencies. Motivated by this, we propose an experimental setup that uses optical cavities to rotate the noise ellipse of each beam, projecting phase noise into intensity noise, thus allowing the experimental access to the phase quadratures. We preliminarly implemented our proposal and obtained promising although not conclusive results, that indicate entanglement.

Converting energy from ocean waves is an exciting concept aimed at reducing our dependency on fossil fuels. Ocean energy devices must convert the large forces and relatively small movements from ocean waves into electrical power with a minimum carbon and energy intensity in order to be economically viable. The research herein focuses on the Oyster, a flap-type pitching wave energy converter developed by Aquamarine Power. A device that has the minimal carbon or energy intensity is not necessarily the most mechanically efficient. A commercially viable wave energy converter should have a competitive cost of energy and be as carbon negative as possible. In order to expedite the route to commercialisation, successive designs should iterate towards a minimum lifetime cost of energy. The sheer complexity of wave energy converter systems makes for a vast optimisation problem to determine the system parameters that exhibit the minimum carbon and energy intensities. This thesis presents a study of the oscillating flap-type wave energy converter to determine the trends between design parameters, total power output and carbon and energy throughput. The minimum carbon and energy intensities have been shown to be strongly dependent on minimising maintenance requirements. In order to determine the design criterion a range of flap widths and system pressures are investigated and their effect on component service lives assessed. The results are then converted to lifetime carbon and energy intensities for a direct comparison. To achieve this, fundamental research on the maintenance requirements of critical components such as the hinge bearings and hydraulic power system is required. A hydrodynamic model describes the dynamic response and links the system energy inputs to its modelled energy output. This work is intended to help guide developers of flap-type wave energy converters towards commercialisation. It enhances the understanding of the routes to failure and service life predictions, providing avenues to balance service lives to optimise maintenance and maximise uptime. This will assist in the development of more energy efficient wave energy converters over their lifetime. This information will better enable the marine energy sector to offset our fossil fuel dependence, ultimately reducing our impact on the environment and leading to a ‘greener’ future.

Graduate students are often exposed to many stressors during their rigorous academic programs which may impact their overall well-being. Researchers have long believed that self-compassion can be used as an emotion-regulated strategy to cope with stress. The purpose of this cross-sectional study is to examine the relationship between self-compassion levels and coping mechanisms for stress among graduate social work students. Data were collected from 97 graduate social work students in a Hispanic-serving university in Southern California (N =97). Using non-parametric techniques, the Kruskal-Wallis Test and the Mann-Whitney Test, this study analyzed the correlation between self-compassion and coping mechanisms for stress, while separately controlling for demographic variables. Results showed a statistically significant correlation between self-compassion level and coping mechanisms (p < .001). The magnitude of this correlation was strong (η2 = .18). Implications of these findings for social work practice were discussed.

The air that humans exhale contains various chemical markers whose levels have been associated with various respiratory disorders. Therefore, measurement of these markers offers a potential method of examining airway disease status. Furthermore, exhaled breath offers the advantage of being easy to collect and non-invasive. Hence, these exhaled breath markers are potentially of significant clinical use in examining airways. Therefore, examination of exhaled breath has become the subject of intense study. Current research is targeting the development of methods and parameters for looking at these markers. The goal of this cross-sectional pilot study was to consider the variability in the measurement of these exhaled breath markers between members of different ethnic populations. Specifically, measurements of the exhaled breath marker Nitric Oxide (NO) were compared between two ethnic groups (Caucasian men versus men of African descent). Ten healthy men in each group were studied to examine whether baseline NO measurements differed between them. In this study, a cross-sectional design was used. The study sample consisted of young, healthy men with no history of environmental allergies, asthma, or lung diseases and no significant smoking history. A total of twenty-five men volunteered for the study, including fourteen men of Caucasian descent and eleven men of African descent. Because four men were excluded and one withdrew, ten men in each ethnic group were included in the final analysis. The source population from which the sample was drawn included students and workers. All participants were residing in Florida at the time of study. Ideally, the target population for this study was young, healthy, working men. Large inter-measurement variation was seen between the participants of each ethnic group. This was hypothesized to be attributed to a tri-modal distribution due to the existence of 3 populations of subjects: (1) asymptomatic with normal airways, where NO levels were under 30 parts per billion (ppb); (2) asymptomatic with airway pathology, where NO levels were over 30 ppb; and (3) asymptomatic just before the onset of an upper respiratory tract infection, where NO levels were over 60 ppb. This pilot study did not find statistically significant evidence that there is a difference in the baseline exhaled breath NO measurements between the two ethnic groups studied. Nonetheless, in participants with NO levels under 30 ppb the mean of the African group was found to be 7.6 ppb lower than the mean of the Caucasian group when attempts were made to exclude individuals with underlying airway pathology or imminent upper respiratory tract infection. In order to find statistical significance in the results, a power analysis using the standard deviation of 7.7 ppb that was found in this study indicates that at least thirty-two eligible participants with NO levels under 30 ppb would be required. Only 13 such participants were examined in this study, Thus, at least fifty eligible participants would be required to find significant results. The implication is that even though statistical significance was not achieved, the crude mean averages differed between the two groups in participants with NO levels under 30 ppb. This implies that a larger-scale well-designed study is warranted before NO is used in clinical settings in the diagnosis and monitoring of patients.

The research work in this dissertation focuses on turbulent air jet heat transfer for commercial cooking applications. As a part of this study, convective heat transfer coefficient and its interdependency with various key parameters is analyzed for single nozzle turbulent jet impingement. Air is used as the working fluid impinging on the flat surface. A thorough investigation of velocity and temperature distributions is performed by varying nozzle velocity and height over diameter ratio (H/D). Nusselt number and Turbulent Energy are presented for the impingement surface. It was found that for H/D ratios ranging between 6 and 8, nozzle velocities over 20 m/s provide a large percentage increase in heat transfer. Single nozzle jet impingement is followed by study of turbulent multi-jet impingement. Along with parameters mentioned above, spacing over diameter ratio (S/D) is varied. Convective heat transfer coefficient, average impingement surface temperature and heat transfer rate are calculated over the impingement surface. It was found that higher S/D ratios result in higher local heat transfer coefficient values near stagnation point. However, increased spacing between the neighboring jets results in reduced coverage of the impingement surface lowering the average heat transfer. Lower H/D ratios result in higher heat transfer coefficient peaks. The peaks for all three nozzles are more uniform for H/D ratios between 6 and 8. For a fixed nozzle velocity, heat transfer coefficient values are directly proportional to nozzle diameter. For a fixed H/D and S/D ratio, heat transfer rate and average impingement surface temperature increases as the nozzle velocity increases until it reaches a limiting value. Further increase in nozzle velocity causes drop in heat transfer rate due to ingress of large amounts of cold ambient air in the control volume. The final part of this dissertation focuses on case study of conveyor oven. Lessons learned from analysis of single and multi-jet impingement are implemented in the case study. A systematic approach is used to arrive to an optimal configuration of the oven. As compared to starting configuration, for optimized configuration the improvement in average heat transfer coefficient was 22.7%, improvement in average surface heat flux was 24.7% and improvement in leakage air mass flow rate was 59.1%.

The main subject of this thesis is solitons due to degenerate parametric four-wave mixing. Derivation of the governing equations is carried out for both spatial solitons (slab waveguide) and temporal solitons (optical fibre). Higher-order effects that are ignored in the standard paraxial approximation are discussed and estimated. Detailed analysis of conventional solitons is carried out. This includes discovery of various solitons families, linear stability analysis of fundamental and higher-order solitons, development of theory describing nonlinear dynamics of higher-order solitons. The major findings related to the stationary problem are bifurcation of a two-frequency soliton family from an asymptotic family of infinitely separated one-frequency solitons, jump bifurcation and violation of the bound state principle. Linear stability analysis shows a rich variety of internal modes of the fundamental solitons and existence of a stability window for higher-order solitons. Theory for nonlinear dynamics of higher-order solitons successfully predicts the position and size of the stability window, and various instability scenarios. Equivalence between direct asymptotic approach and invariant based approach is demonstrated. A general analytic approach for description of localised solutions that are in resonance with linear waves (quasi-solitons and embedded solitons) is given. This includes normal form theory and approximation of interacting particles. The main results are an expression for the amplitude of the radiating tail of a quasi-soliton, and a two-fold criterion for existence of embedded solitons. Influence of nonparaxiality on soliton stability is investigated. Stationary instability threshold is derived. The major results are shift and decreasing of the size of the stability window for higher-order solitons. The latter is the first demonstration of the destabilizing influence of nonparaxiality on higher-order solitons. Analysis of different aspects of solitons is based on universal approaches and methods. This includes Hamiltonian formalism, consideration of symmetry properties of the model, development of asymptotic models, construction of perturbation theory, application of general theorems etc. Thus, the results obtained can be extended beyond the particular model of degenerate four-wave mixing. All theoretical predictions are in good agreement with the results of direct numerical modeling.

The application of the linear prediction Model for speech waveform analysis to context-independent automatic speaker recognition is explored, primarily in terns of the parametric sensitivity of the model. Feature vectors to characterize speakers are formed from linear prediction speech parameters computed as inverse filter coefficients, reflection coefficients or cepstral coefficients, and also power spectrum parameters via Fast Fourier Transform coefficients. The comparative performance of these parameters is investigated in speaker recognition experiments. The stability of the linear prediction parameters is tested over a range of model order from p=6 to p=30. Two independent speech databases are used to substantiate the experimental results. The quality of the automatic recognition technique is assessed in a novel experiment based on a direct performance comparison with the human skill of aural recognition. Correlation is sought between the performance of the aural and automatic recognition methods, for each of the four parameter sets. Although the recognition accuracy of the automatic system is superior to that of the direct aural technique, the error distributions are highly variable. The performance of the automatic system is shown to be empirically based and unlike the intuitive human process. An extended preamble to the description of the experiments reviews the current art of automatic speaker recognition, with a critical consideration of the performance of linear prediction techniques. As supported by our experimental results, it is concluded that success in the laboratory rests upon a rather fragile foundation. Application to problems beyond the controlled laboratory environment is seen, therefore, to be still more precarious.

There is a growing recognition worldwide of the need for more powerful, smaller petrol engines, capable of delivering the higher picking power of larger engines, yet still being economical and environmentally friendly when used for day-to-day driving. An engineering solution for more efficient engines has been considered by research so far. It has been identified that superchargers can potentially improve the performance of automotive engines; therefore research has focused on developing superchargers and supercharger components with higher efficiency. Of particular interest to the research presented in this thesis has been the twin-screw supercharging compressor with design adapted for automotive use (the twin-screw supercharger). The performance of this supercharger type depends on the volume and total losses of the air flow through the supercharger rotors more than on any other aspects of its behaviour. To accurately predict the efficiency of the twin-screw su percharger for matching a particular engine system, accurate supercharger design is required. The main objective of this research was the investigation of the existing limitations of twin-screw superchargers, in particular leakage and reduced efficiency, leading to the development of optimal asymmetric rotor profiles. This research has been completed in four stages defining an innovative rotor design method. The parametric three-dimensional geometric model of twin-screw supercharger rotors of any aspect ratio was developed. For model validation through visualisation, CAD rotor models with scalable data were generated in commercial CAD software and calibrated experimentally by Laser Doppler Velocimetry (LDV) tests. Calibrated rotor profile data can be transferred into CAD-CFD interface for flow simulation and performance optimisation. Through the application of this new rotor design method, new opportunities are created for the twin-screw supercharger design practice, making it a part of the engineering solution for more efficient engines.

<p>In a real-time system, it is crucial to ensure that all tasks of the system holdtheir deadlines. A missed deadline in a real-time system means that the systemhas not been able to function correctly. If the system is safety critical, this canlead to disaster. To ensure that all tasks keep their deadlines, the Worst-CaseExecution Time (WCET) of these tasks has to be known. This can be done bymeasuring the execution times of a task, however, this is inflexible, time consumingand in general not safe (i.e., the worst-casemight not be found). Unlessthe task is measured with all possible input combinations and configurations,which is in most cases out of the question, there is no way to guarantee that thelongest measured time actually corresponds to the real worst case.Static analysis analyses a safe model of the hardware together with thesource or object code of a program to derive an estimate of theWCET. This estimateis guaranteed to be equal to or greater than the real WCET. This is doneby making calculations which in all steps make sure that the time is exactlyor conservatively estimated. In many cases, however, the execution time of atask or a program is highly dependent on the given input. Thus, the estimatedworst case may correspond to some input or configuration which is rarely (ornever) used in practice. For such systems, where execution time is highly inputdependent, a more accurate timing analysis which take input into considerationis desired.In this thesis we present a framework based on abstract interpretation andcounting of possible semantic states of a program. This is a general methodof WCET analysis, which is language independent and platform independent.The two main applications of this framework are a loop bound analysis and aparametric analysis. The loop bound analysis can be used to quickly find upperbounds for loops in a program while the parametric framework provides aninput-dependent estimation of theWCET. The input-dependent estimation cangive much more accurate estimates if the input is known at run-time.</p> / PROGRESS

The incidence of infectious diseases in livestock is a major concern for animal breeders as well as for consumers. As a alternative approach to the use of prophylactic measures or therapeutic agents, infectious diseases can be contended by increasing the disease resistance of animals by genetic improvement. Animals can be selected either on a measure of their resistance (indicator trait) or on the presence or absence of some specific resistance genes in their genotype. A prerequisite to the latter approach is the identification of the genes, or QTL for quantitative trait loci, underlying the trait of interest. By means of sophisticated statistical tools, the QTL mapping strategy combines the information from genetic markers and phenotypic values to dissect quantitative traits into their individual genetic components. Some of the methodological aspects of this strategy are studied in the present thesis in the context of disease resistance in livestock. Indicator traits of the resistance (such as bacteria or parasites counts) are not always satisfying the normality assumption underlying most of the QTL mapping methods. In this context, the ability of statistical tests to identify the underlying genes (i.e. the statistical power) can be considerably reduced. We show that compared to the use of a non-parametric method, the use of the least-squares-based parametric method on mathematically transformed phenotypes gives always the best results. In the context of high number of ties (equal values) as observed when measuring resistance to bacterial or parasitic diseases, the non-parametric test is a good alternative to this approach, as far as midranks are used for ties instead of random ranks. The efficiency of QTL mapping methods can also be increased by use of simple combinations of repeated measurements of the same trait. As a result of analyses performed on real data sets in chicken and sheep, we show that much attention should be paid to obtaining good quality measurements, reflecting at best differences in terms of resistance between animals, before performing a QTL search. The appropriate choice of resistance traits as well as of the time of their measurement are, beside the choice of the method and the quality of marker information, among the most preponderant factors to guarantee satisfying results.