Boreal peatlands store carbon sequestered from the atmosphere over millennia and the importance of this and the other ecosystem services these areas provide is now widely recognised. However, a changing climate will affect these environments and, consequently, the services they provide to the global population. The rate and direction of environmental change to peatlands is currently unclear and they have not yet been included in many climate models. This may in part be due to the ecological heterogeneity and spatial extent of these areas and the sparse sampling survey methods currently adopted. Hyperspectral remote sensing from satellite platforms may in future offer an approach to surveying and do so at the high spectral and spatial resolutions necessary to infer ecological change in these peatlands. However, work is required to develop methods of analysis to determine if hyperspectral data can be used to measure the overstorey vegetation of these areas. This will require an understanding of how annual and inter-annual cyclical changes affect the peatland plant canopy reflectances that would be recorded by hyperspectral sensors and how these reflectances can be related to state variable of interest to climate scientists, ecologists and peatland managers. There are significant areas of peatland within Scotland and, as it is towards the southern extreme of the boreal peatlands, these may be an early indicator of environment change to the wider boreal region. Calluna vulgaris, a hardy dwarf shrub, is the dominant overstorey species over much of these peatlands and could serve as a proxy for ecological, and consequently, environmental change. However, little has been done to understand how variations in leaf pigments or canopy structural parameters influence the spectral reflectance of Calluna through annual and inter-annual growth and senescence cycles. Nor has much work been done to develop methods of analysis to enable images acquired by hyperspectral remote sensing to be utilised to monitor change to these Calluna dominated peatlands over time. To advance understanding of the optical properties of Calluna leaves and canopies and develop methods to analyse hyperspectral images laboratory, field and modelling studies have been carried out in time series over a number of years. The leaf and canopy parameters significantly affecting reflectance have been identified and quantified. Differences between published Chlorophyll(a+b) in vivo absorption spectra and those determined were found. Carotenoids and Anthocyanins were also identified and quantified. The absorption spectra of these pigments were incorporated into a canopy reflectance model and this was coupled to a Calluna growth model. This combined model enabled the reflectance of Calluna canopies to be modelled in daily increments through annual and inter-annual growth and senescence cycles. Reasonable results were achieved in spectral regions where reflectance changed systematically but only for homogeneous Calluna stands. However, it was noted during this research that the area of support for the spectral measurements appeared to differ from that assumed from the specification provided by the spectroradiometer manufacturers. The directional response functions (DRFs) of two spectroradiometers were investigated and wavelength, or wavelength region, specific spatial dependences were noted. The effect that the DRFs of the spectroradiometers would have on reflectances recorded from Calluna canopies was investigated through a modelling study. Errors and inaccuracies in the spectra that would be recorded from these canopies, and commonly used biochemical indices derived from them, have been quantified.

Fluid dynamicists are always in need of innovative instruments for flow velocity measurements. An ideal instrument would be non-intrusive, have a very fine spatial resolution as well as a very fine temporal resolution, be able to measure three-components of velocity, and be compact. Through recent advancements, laser Doppler velocimetry can now meet all of those requirements making it an important part of aerodynamicist's research toolbox. The first paper presented in this manuscript style thesis explains the development of an advanced three-velocity component, spatially-resolving laser-Doppler velocimetry (LDV) system for highly resolved velocity measurements in situations with limited optical access. The new instrument, a next generation version of the previously developed 'comprehensive' LDV technology, enables measurements of three components of velocity and particle position in the axial direction all through a single transceiving lens. Described here is the design process and the final design for the 'compact, comprehensive' LDV (Comp²LDV). The probe was designed to achieve ± 10 micron root-mean-square uncertainties in axial particle position, which combined with the long measurement volume, allow researchers to obtain a three-velocity-component velocity statistics profiles over a span of approximately 1.5mm without the need for traversing. Results from measurements in a flat plate turbulent boundary layer very near the wall have compared favorably to data from previous studies. The second paper focuses on the motion and evolution of coherent structures in supersonic jet flows and how that relates to the intense noise the flows generate. As a preliminary study to experimentally address these relationships, novel non-intrusive measurements using two-component laser Doppler velocimetry (LDV) have been conducted at exceptionally high data rates to lend insight into the statistical behavior of noise-generating flow structures. A new heated supersonic jet facility has been constructed to provide supersonic flow at total temperatures ratios (T₀/Tₐ) up to 3. In the present work, the instrumentation is validated via comparison of LDV measurements along the centerline of a screeching cold jet with microphone and high-speed shadowgraph results. Reynolds stress spectra are presented for an over-expanded case (nozzle pressure ratio of 3.2) of a design Mach number 1.65 nozzle operated cold (T₀/Tₐ = 1). A preliminary study was then conducted in the near-nozzle shear layer, up to x/d = 4.0, at design nozzle pressure ratio (4.58) and total temperature ratio of 2.0. Results are presented for Reynolds stress time-delay correlations and power spectra at Re_d = 1.1M for this case. The stream-wise Reynolds normal stress spectra are compared with published spectral behavior reported by other researchers, indicating a similar spectral shape in the downstream stations as previously measured with LDV and hot wire anemometry for cold jets, but which differ in shape from density-based techniques. / Master of Science

L’objectif de ce travail, mené en partenariat avec le Département de Chirurgie Oncologique du Centre Paul Strauss à Strasbourg, est d’évaluer les conséquences d’une chirurgie thyroïdienne sur la voix des patients, afin de déceler les différentes perturbations qu’entraîne cette opération chirurgicale, et de mettre au jour les possibles stratégies de compensation ou de réajustements que le patient peut mettre en place, seul ou à l’aide d’une rééducation orthophonique ; il s’agit d’une étude longitudinale. L’évaluation reposait sur l’analyse de signaux acoustiques, à partir desquels une quantité importante d’indices relatifs à la qualité vocale, mais aussi aux comportements articulatoires des locuteurs, a pu être extraite. La production de voyelles soutenues a permis de conduire deux études spectrales. L’étude spatio-temporelle a été rendue possible grâce à l’analyse de logatomes, et plus précisément de séquences VCV. Nous avons mené trois expériences sur le plan acoustique. La première expérience traite des caractéristiques spectrales de la voix de patients ayant subi une thyroïdectomie et ne présentant pas d’immobilité laryngée. La deuxième étude est menée à partir des caractéristiques spectrales de la voix de locuteurs présentant une immobilité laryngée post-thyroïdectomie. Enfin, notre dernière expérience a pour objet, l’étude des caractéristiques spatio-temporelles de la voix de locuteurs qui ont subi une thyroïdectomie et présentant une immobilité laryngée. L’interprétation articulatoire, effectuée à partir des données acoustiques, révèle des perturbations aussi bien des gestes glottiques que des gestes supraglottiques, avec des stratégies de réajustements variables suivant les patients. La conception d’une « cible », comme espace de contrôle pour la réalisation de possibles articulatoires et acoustiques perceptivement acceptables, semble particulièrement pertinente ici, dans la mesure où les locuteurs pathologiques réorganisent leurs productions selon leurs propres contraintes physiologiques et anatomiques, provoquées par leur pathologie. / The aim of this study, conducted in partnership with the Department of Surgical Oncology, Centre Paul Strauss in Strasbourg, is to assess the consequences of thyroid surgery on the voice of patients, in order to identify the various perturbations caused by this surgery, and also to reveal possible compensatory strategies or readjustments that the patient may develop, alone or with speech therapy; this is a longitudinal study. The assessment was based on the analysis of acoustic signals, from which a large amount of cues related to voice quality, but also to articulatory behaviour of speakers was extracted. Production of sustained vowels allowed carrying out two spectral studies. The spatiotemporal study was made possible through the analysis of nonsense words, and more specifically through VCV sequences. We conducted three experiments on the acoustic level. The first experiment deals with the spectral characteristics of the voice of patients who underwent thyroidectomy, with no laryngeal paralysis. The second study was conducted based on spectral characteristics of the voice of speakers with laryngeal post-thyroidectomy paralysis. Our final experiment was to study spatio-temporal characteristics of the voice of speakers who underwent thyroidectomy, with laryngeal paralysis. Articulatory interpretations, made from the acoustic data, reveal perturbations of gestures on both the glottal and supraglottal levels, with readjustment strategies varying according to patients. The concept of a "target" as a control space for execution of possible articulatory and acoustic entities, which are perceptually acceptable, seems particularly relevant in this study, since disordered speakers reorganize their productions according to their own physiological and anatomical constraints, caused by the disorder.

The oldest parts of continents, so-called cratons, are the focus of worldwide research not only because they represent primary constraints for our understanding of the early evolution of the Earth, but also because of their significant mineral potential. This work contributes to the understanding of the geological and geomorphological evolution of the West African Craton, by an integrated analysis of airborne geophysical and satellite remote sensing data constrained by field structural, lithological, geophysical, and geomorphological observations acquired around Houndé, Boromo and Banfora greenstone belts and associated granitoid domains in western Burkina Faso. The results of this integration suggest that the granitoid domains of western Burkina Faso are formed by numerous small- to medium-sized plutons, and the magnetic data provided a better definition of the actual pluton shapes. Airborne gamma ray spectrometry data aided in the mapping process in areas with less regolith cover. Three deformation events (D1-D3) can be distinguished in western Burkina Faso. A megacrystic tholeiitic basalt unit allowed us to establish stratigraphic correlations between the two belts and propose a crustal scale anticline (D1). The D1 penetrative structures, resulting from an E-W to WNW-oriented compression are...