L'évaluation économique de nouveaux vaccins exige de modéliser la transmission infectieuse au sein de la population, et donc des hypothèses sur la structure et la répartition des contacts. Les matrices de contact obtenues à partir d’enquête de population ont été déterminées pour 8 pays européens. Mais aucune donnée de ce type n'existe à ce jour pour la France. L’étude ComesF (Contact Matrix Estimation – France) vise à combler cette lacune.MéthodologieL'enquête s’est effectuée sur 3 périodes (Février-Mars, Avril, Mai-Avril) avec 278 participants communs à la première et dernière période. Les participants devaient rapporter tous leurs contacts au cours de 2 jours consécutifs dans un journal, avec l'âge, le sexe, l'endroit, la fréquence, le type et la durée du contact.En combinant des enquêtes sérologiques de 2009 et 2013 et les données de couverture vaccinales, nous avons modélisé la séroprévalence de la rougeole, des oreillons et de la rubéole; puis extrapolé la susceptibilité selon l’âge par département à l'année d'intérêt (2016) ; enfin le potentiel épidémique et l'incidence relative selon l’âge d'une future épidémie ont été estimés.Nous avons analysé l'influence de conditions météorologiques sur les variations temporelles des matrices de contact. La population de l'étude a été analysée selon le jour et la météorologie pour estimer le nombre moyen de contacts et le potentiel de transmission estimée avec le R0. Nous avons effectué une revue systématique de la littérature sur les différences selon le genre pour la grippe, la rougeole, les oreillons et la rubéole, puis exploré l'impact du genre sur les matrices de contact et la modélisation des maladies infectieuses.Résultats2033 participants ont rapporté 38881 contacts (médiane pondérée [premier quartile-troisième quartile] : 8 [5–14] par jour) et 54378 contacts avec les contacts professionnels supplémentaires (9 [5–17]). Contrairement à l'âge, le genre, la taille du foyer, les vacances scolaires, le week-end et l'activité professionnelle, la période de l'année influait peu le nombre de contacts ou les schémas de contact. Les schémas de contact étaient influencés par l'âge indépendamment du lieu de contact, et par le genre, les femmes ayant 8 % plus de contacts que les hommes. La plupart des contacts avaient lieu à la maison et à l'école, mais l'ajout des contacts professionnels modifiait la structure des schémas de contact. Les vacances scolaires et les week-ends réduisaient le nombre de contacts, et le R0 de 33 % et de 28 %, respectivement. Le risque pour les Oreillons et la Rubéole concerne surtout le Sud Est et le Centre de la France, alors que le risque pour la rougeole est plus dispersé. Le risque varie avec le genre pour la Rougeole et la Rubéole. Outre les bébés < 1 an, l’épidémie toucherait surtout les adolescents et les jeunes adultes.Les conditions météorologiques influençaient les schémas de contact différemment entre les jours de semaine ou les weekends. La correction pour analyse répétée limitait le nombre de résultats significatif, mais la tendance pour un effet de la météorologie variant entre les jours de semaine et le week-end restait.Les différences de genre dans le schéma de contact pourraient expliquer en partie les différences de genre dans l'épidémiologie des maladies infectieuses. L'utilisation de données spécifiques par genre avait un impact significatif sur le résultat de la modélisation du risque d’une épidémie.Les matrices de contact françaises partageaient de nombreux points communs avec les autres matrices européennes, notamment avec un impact substantiel des fermetures d’école en cas d’épidémie sur la progression de l’épidémie. Le risque d'une nouvelle épidémie de rougeole persiste, mais prédomine pour les oreillons. L'effet des conditions climatiques sur les schémas de contact était modeste, voire négligeable. L’utilisation des données spécifiques par genre est à considérer en modélisation. / The economic evaluation of new vaccines requires the modeling of infectious disease transmission within a population, which in turn requires some assumption of specific mixing patterns. Matrixes generated from social contact studies were determined for 8 European countries. To date, no such data exist for France. The ComesF study (Contact Matrix Estimation – France) aimed to fill this gap.MethodologyThe survey was carried out over 3 different periods (Feb-Mar, Apr, Apr-May) with 278 participants common to the first and the last periods. Participants had to list all their contacts for 2 consecutive days in a diary, with the age, sex, location, frequency, type and duration of the contact, from which we estimated French contact matrixes.Combining cross-sectional serological surveys from 2009 and 2013 and vaccine coverage information, we have determined an optimal model for the serology of measles, mumps and rubella for the year of the data collection; age-dependent susceptibility by department was then derived to the year of interest (2016), and effective reproduction number and age-dependent relative incidence of a potential outbreak were estimated using the French contact matrixes.We analysed the influence of meteorological conditions on the temporal variations in mixing patterns. The population of the study was split according to the day and the weather at the time when the diary was filled in. The mean number of contacts and the potential for transmission summarized with R0 were calculated for type and location of contact under different weather conditions.We conducted a systematic review on gender differences in infection focusing on influenza, measles, mumps and rubella. Finally, we provided an exploration of the impact of gender on mixing patterns, and eventually the potential implication for modelling.ResultsThe 2033 participants reported 38 881 contacts (weighted median [first quartile-third quartile]: 8[5–14] per day), and 54 378 contacts with supplementary professional contacts (9[5–17]). Contrary to age, gender, household size, holidays, weekend and occupation, the period of the year had little influence on the number of contacts or the mixing patterns. Contact patterns were highly assortative with age, irrespective of the location of the contact, and gender, with women having 8% more contacts than men. Although most contacts occurred at home and school, the inclusion of professional contacts modified the structure of the mixing patterns. Holidays and weekends reduced the number of contacts dramatically, and as proxies for school closure, reduced R0 by 33% and 28%, respectively.The risk for Mumps and Rubella mainly concerned southeastern and south central France, while the risk for measles was more scattered over the country. Risk differed with gender for Measles and Rubella. Besides infants under 1, the highest share of participation would concern teenagers and young adults.The weather had a differential effect on social mixing according to the type of day, notably weekdays and weekend. But correction for repeated analysis made some results no more significant, although the trend for a differential effect between weekdays and weekend remained.Gender differences in social mixing might explain some gender differences in infectious disease epidemiology. Using gender-specific susceptibility and gender-specific contact matrixes had a significant impact on the result of the modeling. Despite the differences, French contact matrixes shared many aspects with those of other European countries. Notably, school closures were likely to have a substantial impact on the spread of close contact infections in France. While the risk of a new Measles outbreak persists, it predominates for Mumps. The effect of weather on social mixing was mild, if not negligible. Gender differences in modelling should be emphasized.

L’oreille interne est l’organe responsable pour la perception auditive et le maintien de l’équilibre. L’OMS estime que 360 millions personnes dans le monde (plus que 5 % de la population) souffrent d’une perte auditive handicapante, soit 40 dB dans l’oreille qui entend le mieux. Une des principales stratégies de traitement est l’administration systémique de stéroïdes, ex : la dexaméthasone. Ces stéroïdes sont utilisés pour prévenir les inflammations ou œdèmes pouvant endommager les très sensibles cellules ciliées de l’oreille interne.La libération contrôlée de principes actifs (PA) est un vrai challenge car l’oreille interne est protégée par la barrière hémato-cochléaire qui ressemble à la barrière hémato-encéphalique et protège l’oreille de substances toxiques. Par conséquent, il est nécessaire d’utiliser de fortes doses pour obtenir des concentrations thérapeutiques dans l’oreille interne. Ainsi, une libération locale et contrôlée semble une approche prometteuse pour limiter la survenue d’effets secondaires.D’un point de vue clinique, un deuxième obstacle doit être surmonté: la taille minuscule de la cochlée et sa difficulté anatomique d’accès. Les deux membranes semi-perméables (la fenêtre ronde et ovale) qui relient l’oreille moyenne avec l’oreille interne sont une voie possible –mais challenging -pour libérer le PA dans l’oreille interne. L’injection de solutions ou de gels chargés en PA dans l’oreille moyenne à travers la membrane tympanique semble être une méthode fiable et économique pour un traitement à court ou moyen terme. Malheureusement, ces formulations risquent d’être éliminées ou dégradées rapidement et par conséquent requièrent des applications répétées. Un autre désavantage est que l’anatomie varie énormément d’un patient à l’autre menant à des concentrations très diverses dans l’oreille interne.Pour un traitement à long terme une libération à partir d’implants cochléaires semble prometteuse : l’implant étant inséré directement dans l’oreille interne, il permet de libérer le PA de manière contrôlée pendant des mois ou des années. Néanmoins, cette intervention est très invasive et le bénéfice pour chaque patient doit être évalué en détail.L’objectif de cette étude est de développer un implant miniaturisé pour la libération contrôlée de dexaméthasone dans l’oreille interne.Dans un premier temps, de fins films de silicone chargés en PA ont été préparés et caractérisé in vitro. La libération à partir de ces films peut être ajustée en modifiant le type de silicone (ex : le type des chaînes latérales, degré de réticulation) ou en ajoutant différents quantités de PEG 400 ou 1000. Une solution analytique de la seconde loi de Fick a pu être utilisée pour décrire les cinétiques de la libération à partir des films et prédire théoriquement la libération du PA à partir de matrices de taille et de forme diverses.Ensuite, deux types d’implants ont été préparés en se basant sur les systèmes les plus prometteurs. Le premier est l’implant « Ear Cube » ayant une forme prédéfinie avec un cube lié à un cylindre. Ce cylindre est en contact avec la périlymphe de l’oreille interne. Le second est un implant se formant in situ qui s’adapte parfaitement à l’anatomie de l’oreille moyenne en réticulant directement dans l’oreille moyenne. Cet implant est en contact avec l’oreille interne par un orifice. Les deux types d’implants ont été caractérisés in vitro.In vivo, la libération de dexaméthasone à partir d’implant se formant in situ a été évaluée avec des gerbilles. Le PA peut être détecté déjà 20 min après l’implantation et ce jusqu’à au moins 30 jours.Ainsi, les deux implants semblent prometteurs pour contrôler à long terme la libération de dexaméthasone directement dans l’oreille interne. A l’avenir, des études pour évaluer les effets des implants « Ear Cube » seront menées. De plus, ces systèmes pourraient être adaptés pour délivrer d’autres PA, ex : la gentamicine, pour traiter d’autres maladies. / The ear is the organ responsible for the perception of sound and the sense of balance. The WHO estimated that worldwide 360 million people (over 5 % of the population) are suffering from disabling hearing loss, meaning a loss of 40 dB in the better hearing ear in adults. One of the major strategies to treat hearing loss is to administer steroids, e.g. dexamethasone, systemically. Steroids are used to prevent inflammation and oedema damaging the highly sensitive inner ear hair cells.Unfortunately, drug delivery to the inner ear is very challenging due to the blood-cochlea barrier which is similar to the blood-brain barrier and protects the inner ear from drugs or toxic substances from the blood stream. High doses are often required to reach therapeutic drug concentrations in the inner ear. Thus, local drug delivery seems to be a more promising approach to limit adverse effects due to high systemic blood levels.Nevertheless, a second major hurdle has to be overcome in clinical practice: the small dimensions of the cochlea and its difficult anatomical access. The two semipermeable membranes connecting the middle with the inner ear (the round and oval window) are one possible - but challenging - route to deliver drugs locally to the inner ear. Drug loaded solutions or gels administered with an intra-tympanic injection into the middle ear seem to be a relatively safe and economical therapy for a short or mid-term treatment. Unfortunately, they might be washed away or degraded rapidly and, though, often require repeated applications. Additionally, the anatomy of the ear varies from patient to patient leading to different drug concentrations in the inner ear.For long term treatment, intra-cochlear implants seem to be promising: Since the device is inserted directly into the inner ear, the drug concentration is better controlled and – depending on the formulation – the drug can be released over prolonged periods of time. Nevertheless, this approach is rather invasive so that the benefit for the patient has to be discussed in detail.The purpose of this study was to develop a miniaturized implant being able to deliver dexamethasone directly to the inner ear.To facilitate the development of silicone-based implants loaded with dexamethasone, thin drug loaded films have been prepared and thoroughly characterized in vitro as a model system. Drug release can easily be adjusted by varying the type of silicone used (e.g. type of side chain, degree of crosslinking), or by adding various amounts of PEG 400 or 1000. An analytical solution of Fick’s second law could be used to describe the drug release kinetics from the films and to theoretically predict drug release from dosage forms of arbitrary size and shape.Subsequently, two types of implants have been prepared using the most promising silicone systems. The first system, the Ear Cube implant with a predefined shape consists of a cube on top of a cylinder which stays in contact with the perilymph of the inner ear. The second system, the in situ forming implant adapts perfectly to middle ear anatomy because it cures directly in vivo. It also stays in contact with the inner ear fluids via a hole. Both systems have been characterized in vitro.In vivo, the dexamethasone loaded in situ forming silicone-based implants have been evaluated in mongolian gerbils. Interestingly, dexamethasone was detected within the explanted gerbil cochleae already 20 min after implant formation until at least 30 days.Thus, both implants seem to be a good tool to administer dexamethasone locally to the inner ear in a prolonged and time controlled manner. Further studies should be performed to characterize the Ear Cube implants in vivo. Additionally, both systems could be tested with different types of drug, e.g. gentamicin, to treat also other diseases with this new promising inner ear implants.

This research presents a pulse-by-pulse analysis of Oscillometric blood pressure waveform at systolic, diastolic and mean arterial pressure points. Using a mathematical optimization technique, pulses are characterized into component harmonic by minimizing the least square error. The results at the important pressure points are analyzed and compared for different subject using different waveform extraction techniques. Blood pressure is estimated using the harmonic parameters. The approach studies changes in the parameters as oscillometric blood pressure recording is done. 8 harmonic parameters are obtained from the pulse characterization and are used to estimate Systolic arterial Blood Pressure, Mean arterial Blood Pressure, and Diastolic arterial Blood Pressure. The estimates are compared with our reference value to determine which has the best agreement. The proposed method is further compared with Maximum Amplitude Algorithm and Pulse Morphology Algorithm. The effect of oscillometric waveform extraction methods on the proposed method is observed. The experiment established the fact that the extraction technique can alter the shape of oscillometric pulses. The methods were compared and it was observed that the used extraction methods did not make any significant difference on the accuracy, using this technique.

Depuis l'invention de la radiographie au début du vingtième siècle et des premiers radars lors la seconde guerre mondiale, le besoin de connaître notre environnement par différentes techniques d'imagerie n'a cessé de croître. Ce besoin a pris de multiples formes, allant de l'exploration d'une structure interne avec la prolifération des techniques d'imagerie non invasives à l'imagerie par satellite qui accompagna la conquête de l'espace. Nombre de systèmes d'imagerie ont donc été proposés pour arriver à créer les images les plus représentatives des milieux étudiés. Parmi eux la tomodensitométrie, ou scanner médical, a connu un succès remarquable depuis son invention. La raison de ce succès vient du fait que son principe de fonctionnement est fondé sur la transformée de Radon dont l'inversion permet de restituer une image fidèle de l'intérieur du milieu étudié.La transformée de Radon (TR) est une transformée géométrique intégrale, qui intègre une densité physique d'intérêt, le long d'une droite du plan. Il est donc naturel de penser qu'une généralisation de la TR, qui consiste à remplacer la droite, support d'intégration, par une courbe ou par une surface, peut amener à une nouvelle imagerie. Dans cette thèse, nous étudions deux types de transformées de Radon généralisées qui sont définies sur des lignes brisées en V du plan (appelées TRV) et des sphères centrées sur un plan fixe (appelées TRS) ainsi que leurs imageries correspondantes.Les transformées de Radon généralisées sur des lignes brisées (TRV) nous permettent de proposer trois nouvelles modalités tomographiques. La première, comme la tomodensitométrie, exploite le phénomène d'atténuation du rayonnement X lors de sa propagation dans un milieu mais utilise aussi le phénomène de réflexion du rayonnement sur une surface impénétrable. La deuxième exploite le phénomène de diffusion Compton du rayonnement émis par un objet. La troisième combine deux modalités d'imageries par transmission et par émission sous la forme d'une imagerie bimodale à partir du rayonnement ionisant diffusé. Cette étude permet non seulement de faire émerger de nouvelles imageries pouvant concurrencer celles existantes mais aussi d'établir de nouveaux algorithmes pour la correction de l'atténuation (un des facteurs physiques dégradant sérieusement la qualité d'image tomographique actuellement).La transformée de Radon sur des sphères centrées sur un plan fixe (TRS) est une généralisation connue de la transformée de Radon en trois dimensions. Elle a été proposée comme modèle mathématique de l'imagerie radar à synthèse d'ouverture (RSO). On montre par la construction d'algorithmes appropriés que l'inversion de cette TRS donne une solution efficace à la reconstruction d'images de l'environnement directement en 3D.La faisabilité théorique de ces nouvelles imageries modélisées par ces deux classes de transformées de Radon généralisées et la performance des algorithmes de reconstruction d'images basés sur les formules d'inversion de ces transformées ouvrent plusieurs perspectives : extension en 3D de l'imagerie bimodale par rayonnement ionisant diffusé, ou possibilité de détection de cibles mobiles en imagerie RSO par introduction d'autres généralisations de la TR. De plus, les méthodes développés dans cette thèse sont susceptibles d'application dans d'autres imageries : imagerie sismique modélisée par la transformée de Radon définie sur des paraboles, imagerie radar Doppler par la TR sur des hyperboles ou encore imagerie thermo-opto-acoustique modélisée par la TR sur des cercles centrés sur un cercle fixe. / Since the invention of radiography at the beginning of the 20th century and of the radar during the 2nd world war, the need of information on our environment is ever increasing. This goes from the exploration of internal structures using non-invasive numerous imaging techniques to satellite imaging which rapidly expands with space exploration. A huge number of imaging systems have been conceived to provide faithful images of the objects of interest. Computed Tomography (or the medical scanner) has experienced a tremendous success since it was invented. The reason for this success lies in the fact that its mathematical foundation is the Radon transform (RT), which has an inverse formula allowing the faithful reconstruction of the interior of an object.The Radon transform is a geometric integral transform which integrates a physical density of interest along a straight line in the plane. It is natural to expect that, when the line is replaced by a curve or a surface as an integration support, new imaging processes may emerge. In this thesis, we study two generalized Radon transforms which are defined on broken lines in the form of a letter V (called V-line RT or VRT) and on spheres centered on a fixed plane (called spherical RT or SRT), as well as their resulting imaging processes.The Radon transforms on V-lines (VRT) form the mathematical foundation of three tomographic modalities. The first modality exploits not only the attenuation of X-rays in traversed matter (as in Computed Tomography) but also the phenomenon of reflection on an impenetrable surface. The second modality makes use of Compton scattering for emission imaging. The third modality combines transmission and emission imaging modalities into a bimodal imaging system from scattered ionizing radiation. This study puts forward new imaging systems which compete with the existing ones and develops new algorithms for attenuation corrections (in emission imaging the attenuation is one of factors degrading seriously tomographic image quality up to now).The Radon transform on spheres centered on a fixed plane (SRT) is a generalization of the classical Radon transform in three dimensions. It has been proposed as a mathematical model for Synthetic Aperture Radar (SAR) imaging. We show through the setting up of appropriate algorithms that the inversion of the SRT yields an efficient solution to the landscape reconstruction problem, directly in three dimensions.The theoretical feasibility of these new imaging systems based on generalized Radon transforms and the good performance of inversion algorithms based on inversion formulas open the way to several perspectives: 3D extension of bimodal imaging by scattered radiation or SAR target motion detection through the introduction of other generalized Radon transforms. Moreover the algorithmic methods developed here may serve in other imaging activities such as: seismics with the parabolic Radon transform, Doppler radar with the hyperbolic Radon transform, thermo-opto-acoustic imaging with the Radon transform on circles centered on a fixed circle.

Considerable research is being carried out into the parameters that affect catalyst performance in order to meet the latest emission regulations. The conversion efficiency and the durability of automotive catalytic converters are significantly dependent on catalyst flow performance. Related investigations are commonly conducted using CFD techniques which represent an inexpensive and fast alternative to experimental methods. This thesis focuses on the flow performance of automotive catalytic converters using both experimental and computational techniques. The work describes the effects of inlet flow conditions on catalyst performance, the application of radial vanes to catalyst systems and the refinement of the CFD flow model which increases the accuracy of the predicted catalyst flow performance. the effects of inlet flow conditions on the flow maldistribution across the catalyst face and the total pressure loss through the system were assessed using a steady air flow rig. Tests were conducted over a range of Reynolds numbers typically encountered in automotive catalytic converters using a uniform and a fully-developed inlet flow condition. The results showed that the flow maldistribution significantly increases with Reynolds number notably in wide-angled diffusers. The catalyst flow performance is considerably improved when the inlet flow is uniform rather than fully-developed, the non-dimensional total pressure loss is reduced by 8% at Re=60000 and the flow maldistribution across the catalyst face is decreased by 12.5% and 15% respective Reynolds numbers of 30000 and 60000 when using a 60 degree diffuser. The total pressure loss through the system was found to be mostly associated with the monolith brick resistance. When the flow maldistribution is approximately 2, the pressure loss across the monolith brick represents 80% of the system pressure loss. The flow maldistribution across the catalyst face was improved by locating a system of radial splitters in the diffuser. The optimum flow performance was found to be a complex function of the vane design. A maximum improvement in the flow maldistrution indices M and Mi of 25% and 50% respectively was achieved at the expense of an increase in total pressure loss of 13.5% at Re = 60000. Both CFD and flow visualisation techniques were used as an aid to interpreting the flow field in the diffuser. Although a qualitative agreement was obtained using CFD, the flow maldistribution across the catalyst face was underpredected by up to 20%. The accuracy of the flow predictions was significantly improved by investigating the flow field in the monolith channels. Flow recirculation occurs in the channel entry length when the flow approaches the monolith channels at an angle which induces an additional implemented into four models of the flow through axisymmetric catalyst assemblies using various diffuser geometries and inlet flow conditions. By including the flow entrance effects in the porous media approach, the flow maldistribution was predicted within 8% instead of 15% when these effects are neglected. Further investigation of the flow in the monolith channels will be required to accurately model three-dimentional flows (racetrack catalysts) and to include various channel geometries and system flow rates.

<div>International development projects are a massive business, with billions invested annually in the Global South. However, such projects have an unacceptably long record of high failure rates. The problem perpetuates, in part, due to the success factors by which international development projects are judged. Often, projects are assessed on the basis of donor-identified priorities that are not aligned with local impacts. One such international development project involves the construction of small-scale water harvesting structures known as sand dams. Non-governmental organizations (NGOs) continue to raise sufficient funds to build thousands of sand dams across sub-Saharan Africa, and yet 50% of sand dams are estimated to be non-functioning.</div><div><br></div><div>Sand dams are small, reinforced concrete dams built across an impermeable stream-bed. Over time, sand settles behind the dam, creating an upstream sand reservoir that fills with rainwater and surface runoff. The sand helps filter the water, protects it from evapotranspiration, and can provide water to the local community for domestic and agricultural use during the dry season. Sand dams often fail due to poor construction, inadequate siting, and siltation.</div><div><br></div><div>This dissertation explores methodologies for studying the regional and local impacts of sand dams and investigates the feasibility of developing model-based site selection guidelines for sand dams. Three objectives of this study are: (1) to develop a methodology to assess the ability of sand dams in improving the overall water availability in the region; (2) to examine claims made by non-scientific bodies about sand dam impacts by investigating how diverse sand dams influence macroinvertebrate habitat, vegetation, erosion, and local water availability; and (3) to create guidelines for siting new sand dams based on a fully integrated surface and groundwater flow model.</div><div><br></div><div>For the first objective, two multiple regression models are developed to compare (1) water storage and (2) vegetation in an area with a high density of sand dams, termed the sand dam counties (SDC), to those in a control area. The models analyze remotely sensed datasets to assess whether evidence exists of significantly increased storage in the SDC relative to the control area. The results show that the remotely sensed water storage data is unable to consistently detect higher levels of water storage in the SDC. This is likely due to the low resolution of the dataset combined with the small magnitude of sand dams' impact on regional water storage. The results of the vegetation model show that the sand dams have a consistent, positive impact on vegetation within the SDC relative to the control area. Because vegetation health and cover is often correlated with groundwater levels, these results likely indicate that the sand dams are also increasing local groundwater levels. Overall, this study shows that remotely sensed dataset can provide a useful basis to assess the impact of international development projects, particularly those that involve the natural environment. </div><div><br></div><div>For the second objective, data relating to macroinvertebrates, vegetation, erosion, and water table elevations at three sand dams were collected and analyzed during a year-long field study in Tanzania. These study subjects were specifically selected to test an NGO claim that sand dams revitalize the entire ecosystem. The results of this study show that sand dams are not a suitable habitat for macroinvertebrates due to their homogeneity. The impact of sand dams on vegetation cover can be significant, but may be limited by the slope of the surrounding land. Functioning sand dams likely have little impact on streambank erosion, but non-functioning sand dams may contribute to the erosion of streambanks in unstable reaches. Lastly, the water table is locally raised by recharge from sand dams, however, the spatial and temporal extent of the impact is more limited than conveyed by NGOs and previous studies. This study adds to the limited body of knowledge on the environmental responses to sand dams and demonstrates the importance of examining the local impacts of individual international development projects. </div><div><br></div><div>For the third objective, results from four different simulations of a watershed-based model with three cascading sand dams are analyzed to identify overland features that improve vadose zone storage and groundwater recharge and reduce evapotranspiration. Results from this study show that sand dams constructed in a low-lying area that collects surface runoff from adjacent steep slopes, such as in a U-shaped valley, will likely collect and store sufficient water for use by a local community. Watersheds with relatively more area cultivated with low-water-need crops will similarly be beneficial to sand dam performance. In addition, the analysis revealed that the volume of water a sand dam receives during a rainy season is less important for water storage than the duration of dry seasons. Lastly, the simulations showed that sand dams constructed in an area with sandier soils will perform better than those in an area with loamy soils. This study produced a set of guidelines that can be used to identify locations where sand dams are likely to capture and store sufficient water for community use during the dry season.</div>

In it´s theoretical part, my master thesis handles selected softwares for wastewater treatment mathematical modelling. It summarizes and compares availible softwares on the market, it´s use, advantages and disadvantages. The practical part deals with an exemplar evaluation of selected wastewater treatment plant according to Czech normative standards and evaluation of the same wastewater treatment plant per mathematical model created in WEST program. The assembly of a wastewater treatment plant model consisted of studies, creation of the layout, insertion of provided data, calibration and model evaluation.

Thesis starts with brief overview of the present role of pneumatic actuators. Further research is carried out in modelling and control of pneumatic actuators. A basic overview of thermodynamic laws is presented. These laws are used to assemble a mathematical model of the pneumatic drive. Subsequently the identification of model parameters is shown. A controller is propřed using fuzzy PID algorithms. Results are compared with the conventional PID controller.

The main goal of the thesis is to create an accurate model of the current state of water quality modelling in the river basin. The basin of the Olšava River, as found in the bachelor thesis "Analysis of Water Quality in the Basin", is polluted with large concentrations of total phosphorus PTot. The master thesis analyses sources of nutrients in the basin that is mainly listed in the vulnerable areas indentified under the Nitrates Directive 91/676/EEC, on the protection of waters against pollution caused by nitrates from agricultural sources. For the water resources management and environmental policy is crucial to recognize distribution of pollution sources throughout main categories. The thesis is concerned with the seasonal variability of the average mass concentrations along the river channel. Broadly used mathematical modelling software of water quality is discussed in the sense of reliability, availability and user interface. Last but not least is a suggestion of two improvements of the water quality based on the MIKE Basin modelling software. The main aim of these proposals is to be realistic in the economical and environmental sense. Proposals consider both in point and non-point sources. Key words: Mathematical modelling, MIKE Basin, Water Quality, Water Quality models, Hydrology, Olšava

This study aims to investigate opportunities to make commercial buildings in Pretoria, South Africa, more energy efficient, which is made by examining prerequisites in South Africa. To achieve this objective, barriers and measures to decrease cooling demand are investigated by a qualitative approach and a roof heat transfer model is developed to get a deeper understanding of the ceiling temperature distribution. The heat transfer model is simulated in MATLAB and is further validated by conducting a two-case scenario sensitivity analysis and by comparing the results to previous research. The results show that there is a great correlation between the Global Horizontal Irradiance [GHI] and the interior ceiling temperature and a higher GHI contributes to a higher ceiling temperature. The hot climate and the long summer period in South Africa indicate that there is a great demand for cooling during a year. Regarding barriers, the socioeconomic aspects in the country and the low electricity prices may contribute to less willingness to adapt to an environmentally friendly behaviour. As some technologies are still perceived as expensive, this may also provide a lower willingness to make changes regarding choices that contribute to a lower cooling demand and thus, energy consumption. Finally, it is concluded that there are several measures that can be applied to decrease the cooling demand, such as constructional changes or enhancement of the heating, ventilation and air-conditioning [HVAC] operation.