by Ma Wing-Kin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 121-124). / Chapter 1 --- Introduction to Otoacoustic Emissions --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Clinical Significance of the OAEs --- p.2 / Chapter 1.3 --- Classes of OAEs --- p.3 / Chapter 1.4 --- The Distortion Product OAEs --- p.4 / Chapter 1.4.1 --- Measurement of DPOAEs --- p.5 / Chapter 1.4.2 --- Some Properties of DPOAEs --- p.8 / Chapter 1.4.3 --- Noise Reduction of DPOAEs --- p.8 / Chapter 1.5 --- Goal of this work and Organization of the Thesis --- p.9 / Chapter 2 --- Review to some Topics in Narrowband Signal Estimation --- p.11 / Chapter 2.1 --- Fourier Transforms --- p.12 / Chapter 2.2 --- Periodogram ´ؤ Classical Spectrum Estimation Method --- p.15 / Chapter 2.2.1 --- Signal-to-Noise Ratios and Equivalent Noise Bandwidth --- p.17 / Chapter 2.2.2 --- Scalloping --- p.18 / Chapter 2.3 --- Maximum Likelihood Estimation --- p.19 / Chapter 2.3.1 --- Finding of the ML Estimator --- p.19 / Chapter 2.3.2 --- Properties of the ML Estimator --- p.21 / Chapter 3 --- Review to Adaptive Notch/Bandpass Filter --- p.23 / Chapter 3.1 --- Introduction --- p.23 / Chapter 3.2 --- Filter Structure --- p.24 / Chapter 3.3 --- Adaptation Algorithms --- p.25 / Chapter 3.3.1 --- Least Squares Method --- p.25 / Chapter 3.3.2 --- Least-Mean-Squares Algorithm --- p.27 / Chapter 3.3.3 --- Recursive-Least-Squares Algorithm --- p.28 / Chapter 3.4 --- LMS ANBF Versus RLS ANBF --- p.31 / Chapter 3.5 --- the IIR filter Versus ANBF --- p.31 / Chapter 4 --- Fast RLS Adaptive Notch/Bandpass Filter --- p.33 / Chapter 4.1 --- Motivation --- p.33 / Chapter 4.2 --- Theoretical Analysis of Sample Autocorrelation Matrix --- p.34 / Chapter 4.2.1 --- Solution of Φ (n) --- p.34 / Chapter 4.2.2 --- Approximation of Φ (n) --- p.35 / Chapter 4.3 --- Fast RLS ANBF Algorithm --- p.37 / Chapter 4.4 --- Performance Study --- p.39 / Chapter 4.4.1 --- Relationship to LMS ANBF and Bandwidth Evaluation . --- p.39 / Chapter 4.4.2 --- Estimation Error of Tap Weights --- p.40 / Chapter 4.4.3 --- Residual Noise Power of Bandpass Output --- p.42 / Chapter 4.5 --- Simulation Examples --- p.43 / Chapter 4.5.1 --- Estimation of Single Sinusoid in Gaussian White Noise . --- p.43 / Chapter 4.5.2 --- Comparing the Performance of IIR Filter and ANBFs . . --- p.44 / Chapter 4.5.3 --- Harmonic Signal Enhancement --- p.45 / Chapter 4.5.4 --- Cancelling 50/60Hz Interference in ECG signal --- p.46 / Chapter 4.6 --- Simulation Results of Performance Study --- p.52 / Chapter 4.6.1 --- Bandwidth --- p.52 / Chapter 4.6.2 --- Estimation Errors --- p.53 / Chapter 4.7 --- Concluding Summary --- p.55 / Chapter 4.8 --- Appendix A: Derivation of Ts --- p.56 / Chapter 4.9 --- Appendix B: Derivation of XT(n)Λ(n)ΛT(n)X(n) --- p.56 / Chapter 5 --- Investigation of the Performance of two Conventional DPOAE Estimation Methods --- p.58 / Chapter 5.1 --- Motivation --- p.58 / Chapter 5.2 --- The DPOAE Signal Model --- p.59 / Chapter 5.3 --- Preliminaries to the Conventional Methods --- p.60 / Chapter 5.3.1 --- Conventional Method 1: Constrained Stimulus Generation --- p.60 / Chapter 5.3.2 --- Conventional Method 2: Windowing --- p.61 / Chapter 5.4 --- Performance Comparison --- p.63 / Chapter 5.4.1 --- Sidelobe Level Reduction --- p.63 / Chapter 5.4.2 --- Estimation Accuracy --- p.65 / Chapter 5.4.3 --- Noise Floor Level --- p.67 / Chapter 5.4.4 --- Additional Loss by Scalloping --- p.68 / Chapter 5.5 --- Simulation Study --- p.69 / Chapter 5.5.1 --- Sidelobe Suppressions of the Windows --- p.69 / Chapter 5.5.2 --- Mean Level Estimation --- p.70 / Chapter 5.5.3 --- Mean Squared Error Analysis --- p.71 / Chapter 5.6 --- Concluding Summary --- p.75 / Chapter 5.7 --- Discussion --- p.75 / Chapter 5.8 --- Appendix A: Cramer-Rao Bound of the DPOAE Level Estimation --- p.76 / Chapter 6 --- Theoretical Considerations of Maximum Likelihood Estimation for the DPOAEs --- p.77 / Chapter 6.1 --- Motivation --- p.77 / Chapter 6.2 --- Finding of the MLEs --- p.78 / Chapter 6.2.1 --- First Form: Joint Estimation of DPOAE and Artifact Pa- rameter --- p.79 / Chapter 6.2.2 --- Second Form: Artifact Cancellation --- p.80 / Chapter 6.3 --- Relationship of CM1 to MLE --- p.81 / Chapter 6.4 --- Approximating the MLE --- p.82 / Chapter 6.5 --- Concluding Summary --- p.84 / Chapter 6.6 --- Appendix A: Equivalent Forms for the Minimum Least Squares Error --- p.85 / Chapter 7 --- Optimum Estimator Structure and Artifact Cancellation Ap- proaches for the DPOAEs --- p.87 / Chapter 7.1 --- Motivation --- p.87 / Chapter 7.2 --- The Optimum Estimator Structure --- p.88 / Chapter 7.3 --- References and Frequency Offset Effect --- p.89 / Chapter 7.4 --- Artifact Canceling Algorithms --- p.92 / Chapter 7.4.1 --- Least-Squares Canceler --- p.93 / Chapter 7.4.2 --- Windowed-Fourier-Transform Canceler --- p.93 / Chapter 7.4.3 --- FRLS Adaptive Canceler --- p.95 / Chapter 7.5 --- Time-domain Noise Rejection --- p.97 / Chapter 7.6 --- Regional Periodogram --- p.98 / Chapter 7.7 --- Experimental Results --- p.99 / Chapter 7.7.1 --- Artifact Cancellation via External Reference --- p.99 / Chapter 7.7.2 --- Artifact Cancellation via Internal Reference --- p.99 / Chapter 7.7.3 --- Artifact Cancellation in presence of Transient Noise --- p.101 / Chapter 7.7.4 --- Illustrative Example: DPgrams --- p.102 / Chapter 7.8 --- Conclusion and Discussion --- p.111 / Chapter 7.9 --- Appendix A: Derivation of the Parabolic Interpolation Method . --- p.113 / Chapter 7.10 --- Appendix B: Derivation of Weighted-Least-Squares Canceler . . --- p.114 / Chapter 8 --- Conclusions and Future Research Directions --- p.118 / Chapter 8.1 --- Conclusions --- p.118 / Chapter 8.2 --- Future Research Directions --- p.119 / Bibliography --- p.121

Recently, electric vehicles (EVs) have been gaining attention in passenger transportation due to their greater fuel economy and reduced greenhouse gas (GHG) emissions compared to conventional vehicles (CVs). The amount of GHG emissions reduction from EVs depends on the energy sources used to generate electricity. Wind is a clean, renewable energy source and EVs charged from wind-generated electricity do not produce any emissions. However, wind is variable in nature. This thesis examines the potential impact of EVs on reducing a jurisdiction’s vehicular GHG emissions using locally available wind-electricity. Four methods of charging EVs using wind-electricity are considered, with grid-electricity as a backup, and the overall well-to-wheels GHG emission reductions are discussed. The thesis includes a case study of Summerside. The results show that up to 68% of the EVs’ demands were met with wind-electricity, and Summerside’s vehicular GHG emissions were reduced by between 56% and 73% when compared to CVs.

The European power sector is facing significant challenges related to investments in grid infrastructure and generation capacity. The continued deployment of intermittent renewables also puts pressure on current grid conditions. Smart grids is seen as a cost-efficient way to overcome these challenges through a more efficient use of current capacity. Demand response is a corner-stone in smart grid development,  and is implemented to introduce flexibility on the demand side. Most demand response programs have used dynamic pricing to incentivize consumers to shift consumption from peak to off-peak hours. In Stockholm Royal Seaport, where a sustainable energy system is envisioned, it has been proposed that dynamic pricing should be complemented with an indicator depicting carbon intensity of purchased electricity. This indicator is based on average emissions, which is one of two fundamental perspectives on assessing environmental impacts of electricity consumption.  The aim of this study was to evaluate whether the approach used to quantify carbon intensity in Stockholm Royal Seaport is appropriate in the context of demand response. To achieve this, a literature review has been conducted regarding potential benefits of demand response, power system dynamics and carbon dioxide allocation methods. A quantitative analysis has also been conducted, where the signal proposed for Stockholm Royal Seaport has been modeled under different timeframes. The results show that the CO2-signal in Stockholm Royal Seaport is constructed in such a way that it is largely affected by hydro generation, which in turn makes it correlate negatively with price. As a result, the CO2-signal would counteract many of the predicted long-term benefits of demand response. Furthermore it seems unlikely that the signal would result in significant short-term emission reductions, since hydro generally is used to balance supply and demand in the Swedish and Nordic systems.  Based on the literature review, it was concluded that marginal emissions would be a more appropriate environmental indicator than average emissions. However, it remains a difficulty to construct a day-ahead control signal based on this perspective because of system complexity and lack of data. Historical marginal carbon intensity was nevertheless modeled in this study using a linear regression model. The results indicate that price itself might be a sufficient indicator of marginal emissions. Finally, a model for a signal based on prognoses of intermittent renewable generation is proposed, where the rationale is that consumers should decrease consumption during hours of low renewable generation. This signal was modeled using data on renewable generation from Denmark since corresponding data in Sweden is not yet available. Results show that it would be possible to construct a rather accurate control signal in this way. There are also reasons to believe that demand response based on this type of signal would result in long-term environmental benefits. / Den europeiska energisektorn står inför stora utmaningar, bland annat i form av investeringsbehov i nätinfrastruktur och produktionskapacitet för att säkra framtida leveranssäkerhet. Den fortsatta utbyggnaden av intermittent förnybar kraftproduktion ställer också nya krav på nätet och på aktörernas flexibilitet. Smarta nät ses som ett kostnadseffektivt sätt för att övervinna dessa utmaningar genom en mer effektiv användning av nuvarande kapacitet. En viktig del i detta är efterfrågerespons, som syftar till att minska belastningen på nätet under höglasttimmar genom att i högre grad än tidigare involvera konsumenten. De flesta initiativ inom efterfrågerespons har använt dynamisk prissättning för att uppmuntra konsumenter att flytta konsumtion från höglast- till låglasttimmar. I Norra Djurgårdsstaden, där visionen är att bygga ett hållbart och mer flexibelt energisystem, har det föreslagits att dynamisk prissättning bör kompletteras med en indikator som visar den inköpta elens koldioxidintensitet. Denna indikator är baserad på medelel, vilket är ett av två fundamentala sätt att miljövärdera el. Syftet med denna studie var att utvärdera om den metod som används för att kvantifiera koldioxidintensiteten i Norra Djurgårdsstaden är lämplig i samband med efterfrågerespons. För att uppnå detta har en litteraturstudie genomförts gällande potentiella fördelar med efterfrågerespons, hur kraftsystemet fungerar samt olika metoder för att miljövärdera el. En kvantitativ analys har också genomförts, där CO2-signalen i Norra Djurgårdsstaden har modellerats utifrån olika tidsperspektiv. Resultaten visar att CO2-signalen i Norra Djurgårdsstaden är konstruerad på ett sådant sätt att den till stor del påverkas av vattenkraftens produktionsvariationer, vilket i sin tur gör att signalen generellt rör sig i motsatt riktning mot prissignalen. Resultatet av detta är att CO2-signalen motverkar många av de långsiktiga fördelarna med efterfrågestyrning. Dessutom ter det sig osannolikt att signalen skulle leda till signifikanta utsläppsminskningar på kort sikt, eftersom lasten i Sverige främst balanseras av variationer i vattenkraft. Utifrån litteraturstudien kan man dra slutsatsen att marginalelens koldioxidintensitet skulle vara en lämpligare miljöindikator än genomsnittliga utsläpp i samband med efterfrågestyrning. Det är dock svårt att i praktiken konstruera en styrsignal baserat på detta perspektiv på grund av systemets komplexitet och brist på data. Historiska marginella utsläpp modellerades emellertid med hjälp av linjär regression. Resultaten från detta indikerade att priset kan vara en tillräcklig indikator även för variationerna i koldioxidintensitet utifrån ett marginalperspektiv. Slutligen föreslås en modell för en signal baserad på dagenföreprognoser om intermittent förnybar produktion, där budskapet skulle vara att användaren minskar sin konsumtion under timmar med låg förnybar produktion. Denna signal modellerades med hjälp av uppgifter om förnybar produktion från Danmark eftersom motsvarande uppgifter om Svensk produktion inte finns tillgängliga ännu. Resultaten visar att det skulle vara möjligt att konstruera en relativt träffsäker styrsignal på detta sätt. Det finns också skäl att tro att efterfrågerespons baserat på denna typ av signal skulle leda till miljömässiga fördelar på längre sikt.

Thesis (LL.M.). / Written for the Institute of Air and Space Law. Title from title page of PDF (viewed 2009/06/17). Includes bibliographical references.

Thesis (M. Sc.)--University of Hong Kong, 1998. / Includes bibliographical references (leaf 37-41).

Thesis (D.Phil.)--University of Oxford, 2009. / Supervisor: Professor Gordon L. Clark. Bibliography: leaves 239-260.

The aim of this diploma thesis is to compare the latest emission standards for JCB engines that are used in JCB telescopic loaders. The first part of this work is focused on the history of JCB, the development of JCB Loadall telescopic loaders and also deals with issues of emissions, their origin, effects on humans and the atmosphere. In addition, there are listed ways how to reduce emissions, both ways of reducing pollutants by designing the combustion chamber and reducing them by systems such as SCR (Selective Catalytic Reduction), DOC (Diesel Oxidation Catalyst), EGR (Exhaust Gas Recirculation) and particulate filters. Emission regulations are included as well. The second part of this work is focused on the actual measurement of the exhaust gas emissions of JCB engines with different technologies for their reduction. The measured values will be further processed and inserted into tables and graphs that will then be compared to each other.

Input Output frameworks have been widely used to study the emissions of industrial sectors either in specific economies or globally but usually focus on aggregated measures under production or consumption accounting principles (PAP and CAP). This leads to a lack of transparency in terms of the structure of the emissions and provides limited information on what are the main drivers of the emissions allocated to each sector under PAP and CAP. This information gap limits the options of policy makers to interventions on whole sectors, rather than the components of their supply chains that hold the major shares of the total embodied emissions. In this thesis we argue in favour of a more disaggregated, a ‘hot-spot’, approach that provides a better understanding of the structure of emissions under both of these headline measures. We develop a methodology to identify CO2 ‘hot-spots’ in downstream and upstream supply chains, both domestic and global. The methodology is applied first to a Single Region Input Output framework for China in 2005 identifying ‘Electricity, Gas and Water Supply’ as the Chinese sector with the highest direct emissions. Examination of the sector’s domestic downstream supply chain reveals that the majority of emissions are generated to support the final demand of other domestic sectors. Of these ‘Construction’ is the main driver and it also is the Chinese sector that is found to have the largest domestic CO2 footprint, with several emissions ‘hot-spots’ in its domestic upstream supply chain. The ‘hot-spot’ methodology is then extended to a global Inter-Regional Input Output framework to consider ‘hot-spots’ in a global supply chain context. By focusing on 2009 (the year for which appropriate data are most recently available) and UK total final demand we find that Chinese ‘Electricity, Gas and Water Supply’ is the non-UK sector with the largest direct emissions driven by UK total final demand. Studying this sector’s downstream supply chain outside China reveals that a large share of the sector’s emissions is ultimately generated to support several UK-based sectors’ domestic final demand. Furthermore, the UK ‘Health and Social Work’ sector is identified as the UK sector with the second largest global footprint to support domestic final demand. We identified a number of ‘hot-spots’ in the international part of its upstream supply chain, with a key finding being its dependence on the activity and the embodied emissions in global chemicals production. Finally, the thesis goes on to demonstrate how conducting ‘hot-spot’ analysis on disaggregated regional/sub-national Input Output tables can provide more detailed local level analysis of ‘hot-spot’ findings from the Inter-Regional Input Output framework. The key finding in this respect is the importance of introducing region specific emissions data where possible, as non-region specific data can lead in incorrect estimation of the embodied emissions in any component of the supply chains of any sectors. In general, through this research project we developed a methodology that can enhance the policy makers understanding of the structure and the drivers of the emissions generated throughout the economy. This additional information on the emissions structure, when combined with familiar IO analysis on employment and value-added for example, has the potential to lead to more targeted/focused policies, which result in significant emissions reduction with the minimum employment, resources and value-added cost.

La réduction des émissions polluantes des foyers aéronautiques est un enjeu majeur pour les motoristes. Afin de les accompagner dans cette tâche, il est nécessaire de développer des outils de simulation numérique permettant de prédire avec précision les émissions d'espèces chimiques en sortie du foyer. Pour cela, une description détaillée des réactions chimiques est nécessaire. Celle-ci est néanmoins incompatible avec la simulation des foyers industriels, compte tenu des puissances de calcul actuelles. C'est pourquoi il est nécessaire de recourir à des méthodes de réduction de la chimie qui préservent la capacité de prédire la concentration des polluants. La démarche consistant à tabuler la chimie nous a semblé appropriée pour aborder ces problèmes et son développement a fait l'objet de cette thèse. Un premier travail a été effectué afin de sélectionner dans la littérature les modèles permettant de traiter des écoulements réactifs turbulents diphasiques avec une approche de chimie tabulée. Par rapport à l’existant, des améliorations ont été apportées à la génération des tables chimiques, afin de prendre en compte l'effet du temps de résidence des gaz brûlés dans le foyer sur la formation des oxydes d'azote. Le couplage de la méthode avec un modèle de formation des suies a également été réalisé. La chimie tabulée permet d’avoir accès à la concentration des précurseurs de suie et des espèces oxydantes, quantités sur lesquelles s’appuie le modèle de formation des suies. Le modèle de chimie tabulée développé dans le cadre de cette thèse a été appliqué à la simulation d'une configuration représentative des foyers aéronautiques. Les concentrations d'oxydes d'azote, de particules de suie, mais aussi de monoxyde de carbone et d'hydrocarbures imbrûlés prédites par les calculs ont été comparées aux résultats expérimentaux. Un bon accord avec l'expérience est observé concernant la topologie du champ de suie et l'allure des profils de concentration de polluants en sortie. Néanmoins, les niveaux de concentration obtenus par les simulations diffèrent des résultats expérimentaux. Cela est imputable notamment à une erreur de prédiction du champ de température qui n'est pas due à l'approche de chimie-tabulée puisque une erreur similaire a été observée avec un autre modèle de combustion. / The reduction of pollutant emissions of aeronautical combustion chambers is a major issue for engine manufacturers. In order to support them in this task, it is necessary to develop numerical simulation tools able to predict accurately chemical species emissions at the chamber outlet. To achieve this, a detailed description of the chemical reactions is necessary. Nevertheless, considering the current computer capabilities, this description is not presently affordable. This is why the use of chemistry reduction methods preserving the capability to predict pollutants species is necessary. The method of tabulated chemistry is a good candidate to tackle these problems and therefore is used as the basis of model developments achieved in the framework of this PhD thesis. A preliminary work has been made to select in the literature tabulated chemistry methods applying to turbulent reactive two-phase flows. The technique to create the chemical tables has been improved in order to take into account the effect of the residence time of the burnt gases on nitrogen oxides formation. The coupling of the method with a soot model has also been achieved. The tabulated chemistry gives access to the concentration of soot precursors and oxidizers, quantities which are required by the model used for the soot prediction. The developed tabulated chemistry model has been applied to the simulation of a configuration representative of aeronautical combustors. The concentration of nitrogen oxides, soot particles, carbon monoxide and unburnt hydrocarbons predicted by the numerical simulations have been compared to experimental results. The topology of the soot volume fraction field and the shape of pollutant concentrations profiles at the outlet agree quite well with the experiments. Nevertheless, concentration levels obtained from the simulations differ from the experimental results. This can be imputed to the error in the prediction of the temperature field that is independent of the combustion model, since a similar error was observed with another combustion model.

The clinical value of oto-acoustic emissions (OAEs) for the identification of the integrity of outer hair cell function has been proven numerous times in research studies, and OAEs are commonly included in the audiological test battery used by audiologists. The technological advances in this field, however, require continuous research to determine the value of new equipment. The main objective of this study was to determine the test-retest reliability of distortion product oto-acoustic emissions (DPOAEs) and transient evoked oto-acoustic emissions (TEOAEs). The subjects were female adults between 18 and 25 years of age, and 30 ears were used for this study. All participants had normal middle-ear function, normal hearing sensitivity (pure tone thresholds) and present OAEs. DPOAEs and TEOAEs were performed at specific time intervals to determine the test-retest reliability, and an OAE-gram was generated by combining DPOAE and TEOAE test results. These measures were performed as an initial measure (M1), after five minutes (M2), after an hour (M3), after a week (M4) and after a month (M5). The test-retest reliability was calculated by analysing the statistics quantitatively. Results were analysed to determine the variance between each participant individually at different time intervals, and also to determine the variance of the group as a whole at different time intervals. Through this analysis high test-retest reliability between the different tests was proven. Inferential statistical Analysis of Variance (ANOVA) and Intraclass Correlation Coefficient (ICC) proved that the test-retest reliability of DPOAEs, TEOAEs and the OAE-gram (generated through a combination of the DPOAE and TEOAE results) was consistent throughout all periods of testing. The highest correlation existed between immediate re-measurements, while the largest difference was observed between M1 and M3. High test-retest reliability for all tests conducted at different time intervals from original measures were confirmed. Recommendations that arose from this study are further research in the normal hearing population for better generalization, research into specific variables between subjects, research with longer time between different tests, as well as the test-retest reliability in pathologic populations. / Dissertation (MCommunication Pathology)--University of Pretoria, 2017. / Speech-Language Pathology and Audiology / MCommunication Pathology / Unrestricted