A magnetic resonance imaging (MRI) compatible near infrared spectrometer (NIRS) system was developed and evaluated for continuous-wave diffuse optical spectroscopy (DOS) and concurrent functional MRI measurements of human muscle. Phantom and in-vivo experiments using the system’s fiber bundle suggested that an isolation distance greater than 8 mm needs to exist between adjacent illumination-detection channels. Using single and probe-pair arrangements (inter-fiber separations of 80 µm and 5 mm, respectively), in-vivo DOS point-measurements (total=20 images) were performed on 1) the antecubital vein and a reference tissue area and 2) the lower leg at the medial (MG) and lateral gastrocnemius (LG) under isokinetic exercise. Mean spectral morphological differences and relative mean intensity changes at Hemoglobin key wavelengths were found, namely reduced mean pixel intensity (~30%) for the vessel-area and a signal change of ~1-4% between the rest and the recovery condition at both muscle locations for the single-probe configuration. Subsequent work is necessary to evaluate the oxygenation assessment capabilities of this system. Lastly, experiments were performed in which two volunteers had concurrent measurement of optical and blood oxygen level dependent (BOLD) MRI, before and following exercise. The same probe arrangement was used for DOS measurements for this experiment. The BOLD signal was studied for manually-derived ROIs. BOLD recovery curves corresponding to the LG followed routine temporal progression where immediate post-exercise signal is hypointense, followed with a sigmoidal-shaped recovery. A decrease ranging between ~0.1-20% was found in the normalized mean spectral signal (20 images) for recovery with reference to the rest condition at both muscle locations for single-probe measurements and for one probe-pair measurement (for 800,808 and 850 nm). The specific trend of the measured decrease in the mean spectral curves during recovery was not consistent among these trials. Future steps include repeatable phantom experiments, increased optical power delivery, enhanced skin contact and improved reflectance measurements / Thesis / Master of Applied Science (MASc)

No description available.

<p> The rapid development of the use of lasers in therapeutic and diagnostic medicine in the past few years has generated interest in measuring the optical properties of tissue. In particular, the development of photodynamic therapy (PDT) has necessitated studies of the optical properties of tissue at wavelengths around 630nm, this being the wavelength at which the photosensitizer commonly used in PDT, namely dihematoporphyrin ether (DHE), is normally activated.</p> <p> The control of the volume of tissue from which information about the interaction coefficients of the tissue is obtained is an important problem in diffuse reflectance spectroscopy and other applications of light, because it is critical to understanding which tissue volumes are sampled by the injected photons that eventually are re-emitted. This report describes a simple model that predicts the parameters that control the volume of tissue interrogated by photons during reflectance spectroscopy.</p> <p> In optical fiber based diffuse reflectance spectroscopy, incident radiation is applied at one point on a tissue surface and collected at another point, a radial distance, r, away. Information about the light multiply scattered by the tissue is used to deduce optical scattering and absorption coefficients of the tissue. In this report both steady state and pulse techniques are studied. In the steady state method, the spatial dependence of the backscattered light is the measured quantity, while the pulse technique uses the temporal broadening of a picosecond (ps) pulse to determine the interaction coefficients.</p> <p> The relative contribution of a volume element of tissue to the observed signal depends on its location, the measurement geometry and the optical properties of the tissue. Knowledge of this dependence would allow some control of the volume interrogated by reflectance spectroscopy, and would provide insight into the influence of inhomogeneities.</p> <p> In the work reported here a simple diffusion model of light propagation in tissue based on the Boltzmann radiative transfer equation has been used to derive mathematical expressions for the relative time spent by photons in a given tissue volume element. Using optical interaction coefficients typical of mammalian soft tissues, results are presented for both steady state and pulse irradiation in both semi-infinite and infinite media.</p> <p> The residency time depth profile calculated by this model for index matched and zero fluence boundary conditions has the same shape as that predicted by Weiss (1989), who used a somewhat different model based on a 3-dimensional random walk theory. These profiles are characterized by a build-up region near the surface and exponential fall far away from the surface in the 'diffusion region'. The influence of the absorption coefficient μa and the fiber separation on the residency time as predicted by this model is in good agreement to that predicted by the random-walk theory (i.e the depth-profile of the residency time tends to sharpen as the absorption coefficient increases. This is attributed to the fact that long trajectories are less likely with large absorption probabilities. As well, the greater the fiber separation, the wider and flatter the depth distribution of the residency time. This is because photons that reach the surface at greater r values have, in general, migrated farther from the immediate vicinity of the source and detector and hence have sampled a larger volume of tissue). All the integrations in this report were performed numerically using the IMSL/LIB on the Microvax computer system in the Hamilton Regional Cancer Center. The adequacy of this numerical integration was tested and was found to be good.</p> <p> This model therefore suggests that during diffuse reflectance spectroscopy, the volume sampled by re-emitted photons can be controlled by changing parameters such as the fiber separation (in both steady state and time-resolved techniques) and the detection time (in the time-resolved method).</p> / Thesis / Master of Science (MSc)

Depuis une vingtaine d'années, les développements dans les technologies de l'information ont fait évoluer les paradigmes de l'informatique. L'arrivée d'approches telles que l'informatique diffuse et l'intelligence ambiante ont fait émerger de nouvelles technologies permettant d'améliorer la qualité des interactions avec les systèmes informatisés. Entre autres, l'application de l'informatique diffuse et de l'intelligence ambiante à des environnements tels que des habitats, les espaces intelligents, offre des milieux où une assistance contextualisée est offerte aux utilisateurs dans la réalisation de leurs activités quotidiennes. Toutefois, la démocratisation de l'informatique diffuse et la mise en place des espaces intelligents rencontrent un bon nombre de problèmes. Le nombre important de composantes matérielles et logicielles, les dépendances entre celles-ci et leurs natures hétérogènes contribuent à la complexité de déploiement et de gestion de ces milieux, entraînant des coûts élevés. Cette thèse vise à contribuer à la gestion logicielle des espaces intelligents par la réduction de la complexité des tâches de gestion. Notre proposition consiste en une approche autonome de la gestion logicielle, fondée sur l'approche de l'informatique diffuse autonome. L'objectif est de fournir un ensemble de fonctionnalités et de mécanismes permettant de rendre autonome la majeure partie des tâches de gestion des logiciels déployés dans des espaces intelligents. Dans le cadre de ce travail, nous proposons une solution permettant l'organisation autonome des logiciels des espaces intelligents. Ainsi, cette solution utilise les informations contextuelles des milieux afin de déterminer quelle répartition des logiciels parmi les appareils des milieux correspond le mieux aux besoins des applications, aux caractéristiques propres des environnements et, non le moindre, aux modalités et préférences d'interaction des utilisateurs de ces milieux. La solution proposée a été implémentée et évaluée à l'aide d'une série de tests et de mises en situation d'organisation logicielle. Les contributions de ce travail à l'état de l'art de la gestion des espaces intelligents sont multiples avec comme principales innovations la présentation d'une vision de l'informatique diffuse autonome, l'implémentation d'un intergiciel d'organisation logicielle autonome basé sur une sensibilité au contexte macroscopique et microscopique et l'intégration des modalités d'interaction des utilisateurs dans le raisonnement portant sur l'organisation des logiciels. Enfin, ce travail de thèse se déroule dans le contexte des recherches du laboratoire DO-MUS de l'Université de Sherbrooke, Canada, et du laboratoire Handicom de Telecom SudParis, France. Ces deux laboratoires travaillent à la conception de solutions permettant d' améliorer la qualité de vie et l' autonomie de personnes dépendantes, atteinte par exemple de troubles cognitifs ou de handicaps physiques.

After the epoch of reionisation the intergalactic medium (IGM) is kept at a high photoionisation level by the cosmic UV background radiation field. Primarily composed of the integrated contribution of quasars and young star forming galaxies, its intensity is subject to spatial and temporal fluctuations. In particular in the vicinity of luminous quasars, the UV radiation intensity grows by several orders of magnitude. Due to an enhanced UV radiation up to a few Mpc from the quasar, the ionised hydrogen fraction significantly increases and becomes visible as a reduced level of absorption in the HI Lyman alpha (Ly-alpha) forest. This phenomenon is known as the proximity effect and it is the main focus of this thesis. Modelling the influence on the IGM of the quasar radiation, one is able to determine the UV background intensity at a specific frequency (J_nu_0), or equivalently, its photoionisation rate (Gamma_b). This is of crucial importance for both theoretical and observational cosmology. Thus far, the proximity effect has been investigated primarily by combining the signal of large samples of quasars, as it has been regarded as a statistical phenomenon. Only a handful of studies tried to measure its signature on individual lines of sight, albeit focusing on one sight line only. Our aim is to perform a systematic investigation of large samples of quasars searching for the signature of the proximity effect, with a particular emphasis on its detection on individual lines of sight. We begin this survey with a sample of 40 high resolution (R~45000), high signal to noise ratio (S/N~70) quasar spectra at redshift 2.1<z<4.7, publicly available in the European Southern Observatory (ESO) archive. The extraordinary quality of this data set enables us to detect the proximity effect signature not only in the combined quasar sample, but also along each individual sight line. This allows us to determine not only the UV background intensity at the mean redshift of this sample, but also to estimate its intensity in small (Delta z~0.2) redshift intervals in the range 2<z<4. Our estimates (J_nu_0~ 3x10^{-22} erg s^{-1} cm^{-2} Hz^{-1} sr^{-1}) are for the first time in very good agreement with different constraints of its evolution obtained from theoretical predictions and numerical simulations. We continue this systematic analysis of the proximity effect with the largest search to date invoking the Sloan Digital Sky Survey (SDSS) data set. The sample consists of 1733 quasars at redshifts z>2.3. In spite of the low resolution and limited S/N we detect the proximity effect on about 98% of the quasars at a high significance level. Thereby we are able to determine the evolution of the UV background photoionisation rate within the redshift range 2<z<5 finding Gamma_b~ 1.6x10^{-12} s^{-1}. With these new measurements we explore literature estimates of the quasar luminosity function and predict the stellar luminosity density up to redshift of about z~5. Our results are globally in good agreement with recent determinations inferred from deep surveys of high redshift galaxies. We then compare our measurements on the UV background photoionisation rate inferred from the two samples at high and low resolution. While these data sets show extreme differences, our determinations are in considerable agreement at z<3.3, even though they show less agreement at higher redshifts. We suspect that this may be caused by either the small number of high resolution quasar spectra at the highest redshifts considered or by some systematic effect due to the limited data quality of SDSS. Complementary to the observational investigation of the proximity effect on high redshift quasars, we exploit some theoretical aspects linked to and based on the results on this phenomenon. We employ complex numerical simulations of structure formation to achieve a better representation of the Ly-alpha forest. Modelling the signature of the proximity effect on randomly selected sight lines, we prove the advantages of dealing with individual lines of sight instead of combining their signal to investigate this phenomenon. Furthermore, we develop and test novel techniques aimed at a more precise determination of the proximity effect signal. With this investigation we demonstrate that the technique developed and employed in this thesis is the most accurate adopted thus far. Tighter determinations of the UV background are certainly based on suitable methods to detect its signature, but also on a deeper understanding of the environments in which quasars form and evolve. We initiate an investigation of complex numerical simulations including the radiative transport of energy to model in a more detailed way the proximity effect. Such a simulation may lead to the characterisation of the quasar environment based on the comparison between the observed and simulated statistical properties of the proximity effect signature. / Nach dem kosmologischen Zeitalter der Reionisation wird der hohe Photoionisationsgrad des intergalaktische Mediums (IGM) durch die kosmische UV-Hintergrundstrahlung aufrecht erhalten. Zur Intensitaet der Hintergrundstrahlung tragen hauptsaechlich Quasare und jungen Galaxien bei. Daher entstehen sowohl raeumliche als auch zeitliche Fluktuationen, wobei die Intensistaet insbesondere in der Naehe von leuchtkraeftigen Quasaren um mehrere Groessenordnungen ansteigt. Aufgrund der erhoehten UV-Strahlung in einer Entfernung von bis zu einigen Mpc von einem Quasar wird ein groesserer Anteil des intergalaktischen Wasserstoffs ionisiert, was als reduzierte Absorption im Lyman alpha (Ly-alpha) Wald sichtbar wird. Dieses Phaenomen wird proximity effect genannt und ist das Hauptthema dieser Arbeit. Durch Modellierung des Einflusses des Quasars auf das IGM kann die Intensitaet des UV-Hintergrunds bei einer bestimmten Frequenz (J_nu_0) bzw. die entsprechende Photoionisationrate (Gamma_b) bestimmt werden. Dies ist sowohl fuer die theoretische als auch fuer die beobachtende Kosmologie eine wichtige Groesse. Bisher wurde der Proximity-Effekt als ein statistisches Phaenomen untersucht, wobei die Signale vieler einzelner Quasare kombiniert wurden. Nur in wenigen Analysen wurde versucht, den Effekt in einzelnen Sehlinien zu detektieren. Das Ziel dieser Arbeit ist eine systematische Untersuchung des Proximity-Effekts in einer grossen Anzahl von Quasaren, wobei der besonderen Schwerpunkt auf seiner Detektion in einzelnen Sehlinien liegt. Zunaechst werden 40 Quasare im Rotverschiebungsbereich 2.1<z<4.7 untersucht, deren Spektren mit hoher Aufloesung (R=45000) und hohem Signal-zu-Rausch-Verhaeltnis (S/N~70) im Archiv des European Southern Observatory (ESO) vorliegen. Die ausserordentlich gute Qualitaet dieser Daten ermoeglicht die Detektion des Proximity-Effekts nicht nur als kombiniertes Signal aller Quasare sondern auch in jeder einzelnen Sehlinie. Daher konnten wir nicht nur die Intensitaet des UV-Hintergrunds bei der mittleren Rotverschiebung ermitteln sondern auch in kleineren Rotverschiebungsintervallen (Delta z~0.2) im Bereich 2<z<4. Unsere Ergebnisse (J_nu_0}~3x10^{-22} erg s^{-1} cm^{-2} Hz^{-1} sr^{-1}) stimmen zum ersten Mal gut anderen Bestimmungen ueberein, die auf theoretischen Voraussagen und auf numerischen Simulationen beruhen. Unsere systematische Analyse des Proximity-Effekts wird mit dem bisher groessten Datensatz bestehend aus 1733 Quasaren mit Rotverschiebungen z>2.3 aus dem Sloan Digital Sky Survey (SDSS) fortgefuehrt. Trotz der niedrigen Aufloesung und dem begrenzten S/N detektieren wir den Proximity-Effekt mit einer hohen Signifikanz in etwa 98% der Sehlinen. Dabei kann die Entwicklung der Photoionisationsrate Gamma_b~1.6x10^{-12} s^{-1} im Rotverschiebungsbereich 2<z<5 bestimmt werden. Mit diesen neuen Messungen diskutieren wir verschiedene Quasar-Leuchtkraftfunktionen aus der Literatur und berechnen die stellare Emissivitaet bis z~5. Unsere Ergebnisse stimmen im Allgemeinen gut mit denen von neueren Himmelsdurchmusterungen nach hochrotverschobenen Galaxien ueberein. Dann vergleichen wir die auf den hoch bzw. niedrig aufgeloesten Spektren basierenden Photoionisationsraten miteinander. Obwohl die Datensaetze sehr unterschiedlich sind, fuehren sie bei z<3.3 zu den selben Ergebnissen, waehrend die Resultate bei hoeheren Rotverschiebungen weniger gut uebereinstimmen. Wir vermuten, dass dies entweder durch die kleine Anzahl von hochaufgeloesten Quasarspektren bei den hoechsten Rotverschiebungen, oder durch systematische Effekte der geringen SDSS Datenqualitaet hervorgerufen wird. Ergaenzend zu der Auswertung der Beobachtungsdaten fuehren wir basierend auf unseren Ergebnissen einige theoretische Untersuchugen durch. Wir benutzen komplexe Strukturbildungssimulationen, um eine bessere Beschreibung des Ly-alpha-Walds zu gewinnen. Mit Hilfe der Modellierung des Proximity-Effekts in zufaellig ausgesuchten Sehlinien zeigen wir den Vorteil auf, den die Analyse einzelner Sehlinien im Vergleich zur kombinierten Auswertung mehrerer Spektren hat. Ausserdem entwickeln und testen wir neue Ansaetze zur genaueren Bestimmung des Proxmity-Effekts. Dabei zeigen wir, dass die im Rahmen dieser Arbeit entwickelte und angewendete Methode bisher zu den genauesten Ergebnissen fuehrt. Fuer eine noch bessere Bestimmung des UV-Hintergurnds brauchen wir neben der optimalen Detektionsmethode auch ein tieferes Verstaendnis der Umgebung, in der Quasare entstehen und sich entwickeln. Wir beginnen eine Analyse komplexer numerischer Simulationen, die auch Strahlungstransportrechungen beinhalten, um weitere Details des Proximity-Effekts zu verstehen. Der Vergleich der statistischen Eigenschaften des Proximity-Effekts in solchen Simulationen mit Beobachtungen koennte in Zukunft zu einer genaueren Beschreibung der Umgebung von Quasaren fuehren.

Ziel dieser Arbeit war es, die Stickstoff- und Phosphorprozesse im nordostdeutschen Tiefland detailliert zu untersuchen und Handlungsoptionen hinsichtlich der Landnutzung zur nachhaltigen Steuerung der Stickstoff- und Phosphoreinträge in die Fließgewässer aufzuzeigen. Als Grundvoraussetzung für die Modellierung des Nährstoffhaushaltes mussten zunächst die hydrologischen Prozesse und die Abflüsse für die Einzugsgebiete validiert werden. Dafür wurde in dieser Arbeit das ökohydrologische Modell SWIM verwendet. Die Abflussmodellierung umfasste den Zeitraum 1991 - 2000. Die Ergebnisse dazu zeigen, dass SWIM in der Lage war, die hydrologischen Prozesse in den Untersuchungsgebieten adäquat wiederzugeben. Auf der Grundlage der Modellierung des Wasserhaushaltes wurden mit SWIM die Stoffumsatzprozesse für den Zeitraum 1996 - 2000 simuliert. Um dabei besonders das Prozessgeschehen im Tiefland zu berücksichtigen, war die Erweiterung von SWIM um einen Ammonium-Pool mit dessen Umsatzprozessen erforderlich. Außerdem wurde der Prozess der Nährstoffversickerung so ergänzt, dass neben Nitrat auch Ammonium und Phosphat durch das gesamte Bodenprofil verlagert und über die Abflusskomponenten zum Gebietsauslass transportiert werden können. Mit diesen Modellerweiterungen konnten die Stickstoff und Phosphorprozesse in den Untersuchungsgebieten gut abgebildet werden. Mit dem so validierten Modell wurden weitere Anwendungen ermöglicht. Nährstoffsimulationen für den Zeitraum 1981 bis 2000 dienten der Untersuchung des abnehmenden Trends in den Nährstoffkonzentrationen der Nuthe. Die Untersuchungsergebnisse lassen deutlich erkennen, dass sich die Konzentrationen nach 1990 hauptsächlich auf Grund der Reduzierung der Einträge aus punktförmigen Quellen und Rieselfeldern verringert haben. Weitere Modellrechnungen zur Herkunft der Nährstoffe haben ergeben, dass Nitrat überwiegend aus diffusen Quellen, Ammonium und Phosphat dagegen aus punktförmigen Quellen stammen. Als besonders sensitiv auf die Modellergebnisse haben sich die Parameter zu Landnutzung und -management und die Durchwurzelungstiefe der Pflanzen herausgestellt. Abschließend wurden verschiedene Landnutzungsszenarien angewendet. Die Ergebnisse zu den Szenariorechnungen zeigen, dass fast alle vorgegebenen Landnutzungsszenarien zu einer Verringerung der Stickstoff- bzw. Phosphoremissionen führten. Die Anwendung von Szenarien, die alle relevanten Zielvorgaben und Empfehlungen zum Ressourcenschutz berücksichtigen, zeigen die größten Veränderungen. / The main objective of this study was to investigate the nitrogen and phosphorus processes in the north-eastern German lowlands and to suggest sustainable management options concerning land use that could lead to a reduction in nitrogen and phosphorous emissions into the river network. In order to fulfil the basic requirements of water quality modelling on river basin scale, the hydrological processes had to be validated first. For this purpose the ecohydrological model SWIM was used. The simulations were carried out on a daily time step within the period 1991 - 2000. The results have shown that SWIM was able to reproduce adequately the hydrological processes within all investigation areas. Based on these hydrological simulations the nutrient processes were modelled with SWIM for the time period 1996 - 2000. It became obvious that the modelling approaches within SWIM, especially concerning the nutrient cycling processes in lowland watersheds, had to be modified. Thus, an ammonium pool including its transformations processes was added. In addition, leaching not only of nitrate but also of ammonium and phosphate throughout the whole soil profile is now possible. Thus all nutrients can be transported to the outlet of the watersheds by the flow components. It could be shown that with these modifications the model was able to reproduce well the nitrogen and phosphorus processes in the research areas. With the validated model further applications were enabled. In order to investigate the reason for the decreasing trend in the nutrient concentrations in the Nuthe River, nutrient simulations were performed for the period 1981 - 2000. The results show that the concentrations after 1990 have decreased mainly because of the reduction of emissions from point sources and sewage fields. Further simulations in order to gain more information about the different nutrient sources showed that nitrate basically originates from diffuse sources and ammonium as well as phosphorus from point sources. Especially parameters related to land use and management as well as the root depth of plants turned out to be very sensitive to model results. Concluding, different land use change scenarios were adapted. The calculation results demonstrate that almost all provided scenarios lead to a reduction in the emission rates. Applying those scenarios which consider all relevant aims and recommendations concerning the protection of resources the highest changing rates could be achieved.

Ziel dieser Arbeit war es, die Stickstoff- und Phosphorprozesse im nordostdeutschen Tiefland detailliert zu untersuchen und Handlungsoptionen hinsichtlich der Landnutzung zur nachhaltigen Steuerung der Stickstoff- und Phosphoreinträge in die Fließgewässer aufzuzeigen. Als Grundvoraussetzung für die Modellierung des Nährstoffhaushaltes mussten zunächst die hydrologischen Prozesse und die Abflüsse für die Einzugsgebiete validiert werden. Dafür wurde in dieser Arbeit das ökohydrologische Modell SWIM verwendet. Die Abflussmodellierung umfasste den Zeitraum 1991 - 2000. Die Ergebnisse dazu zeigen, dass SWIM in der Lage war, die hydrologischen Prozesse in den Untersuchungsgebieten adäquat wiederzugeben. Auf der Grundlage der Modellierung des Wasserhaushaltes wurden mit SWIM die Stoffumsatzprozesse für den Zeitraum 1996 - 2000 simuliert. Um dabei besonders das Prozessgeschehen im Tiefland zu berücksichtigen, war die Erweiterung von SWIM um einen Ammonium-Pool mit dessen Umsatzprozessen erforderlich. Außerdem wurde der Prozess der Nährstoffversickerung so ergänzt, dass neben Nitrat auch Ammonium und Phosphat durch das gesamte Bodenprofil verlagert und über die Abflusskomponenten zum Gebietsauslass transportiert werden können. Mit diesen Modellerweiterungen konnten die Stickstoff und Phosphorprozesse in den Untersuchungsgebieten gut abgebildet werden. Mit dem so validierten Modell wurden weitere Anwendungen ermöglicht. Nährstoffsimulationen für den Zeitraum 1981 bis 2000 dienten der Untersuchung des abnehmenden Trends in den Nährstoffkonzentrationen der Nuthe. Die Untersuchungsergebnisse lassen deutlich erkennen, dass sich die Konzentrationen nach 1990 hauptsächlich auf Grund der Reduzierung der Einträge aus punktförmigen Quellen und Rieselfeldern verringert haben. Weitere Modellrechnungen zur Herkunft der Nährstoffe haben ergeben, dass Nitrat überwiegend aus diffusen Quellen, Ammonium und Phosphat dagegen aus punktförmigen Quellen stammen. Als besonders sensitiv auf die Modellergebnisse haben sich die Parameter zu Landnutzung und -management und die Durchwurzelungstiefe der Pflanzen herausgestellt. Abschließend wurden verschiedene Landnutzungsszenarien angewendet. Die Ergebnisse zu den Szenariorechnungen zeigen, dass fast alle vorgegebenen Landnutzungsszenarien zu einer Verringerung der Stickstoff- bzw. Phosphoremissionen führten. Die Anwendung von Szenarien, die alle relevanten Zielvorgaben und Empfehlungen zum Ressourcenschutz berücksichtigen, zeigen die größten Veränderungen. / The main objective of this study was to investigate the nitrogen and phosphorus processes in the north-eastern German lowlands and to suggest sustainable management options concerning land use that could lead to a reduction in nitrogen and phosphorous emissions into the river network. In order to fulfil the basic requirements of water quality modelling on river basin scale, the hydrological processes had to be validated first. For this purpose the ecohydrological model SWIM was used. The simulations were carried out on a daily time step within the period 1991 - 2000. The results have shown that SWIM was able to reproduce adequately the hydrological processes within all investigation areas. Based on these hydrological simulations the nutrient processes were modelled with SWIM for the time period 1996 - 2000. It became obvious that the modelling approaches within SWIM, especially concerning the nutrient cycling processes in lowland watersheds, had to be modified. Thus, an ammonium pool including its transformations processes was added. In addition, leaching not only of nitrate but also of ammonium and phosphate throughout the whole soil profile is now possible. Thus all nutrients can be transported to the outlet of the watersheds by the flow components. It could be shown that with these modifications the model was able to reproduce well the nitrogen and phosphorus processes in the research areas. With the validated model further applications were enabled. In order to investigate the reason for the decreasing trend in the nutrient concentrations in the Nuthe River, nutrient simulations were performed for the period 1981 - 2000. The results show that the concentrations after 1990 have decreased mainly because of the reduction of emissions from point sources and sewage fields. Further simulations in order to gain more information about the different nutrient sources showed that nitrate basically originates from diffuse sources and ammonium as well as phosphorus from point sources. Especially parameters related to land use and management as well as the root depth of plants turned out to be very sensitive to model results. Concluding, different land use change scenarios were adapted. The calculation results demonstrate that almost all provided scenarios lead to a reduction in the emission rates. Applying those scenarios which consider all relevant aims and recommendations concerning the protection of resources the highest changing rates could be achieved.

Made available in DSpace on 2014-06-11T19:24:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-08-27Bitstream added on 2014-06-13T19:11:22Z : No. of bitstreams: 1 inacio_t_me_botfca.pdf: 488409 bytes, checksum: f07ac54da8077b5df98e78bea1785b2e (MD5) / No presente trabalho é apresentado o estudo do potencial da energia solar disponível no município de Botucatu, através das análises das séries temporais médias anuais diárias, médias mensais diárias e séries anuais dos acumulados mensais das radiações global, difusa e direta na horizontal do período de 1996 à 2005. As irradiações, em MJ/m2, foram calculadas a partir das integrações diárias das irradiâncias global , irradiância difusa , irradiância direta na horizontal e no topo da atmosfera , determinando-se as irradiações diárias: , e ; e médias mensais: G I d I D I O I dG H d d H dD H dGH , d d H e dD H . A partir das médias mensais, determinou-se o índice de claridade t K (razão da irradiação global pela do topo da atmosfera), e as demais frações das radiações: d K (razão da irradiação difusa pela global), ′ d K (razão da irradiação difusa pela do topo da atmosfera), D K (razão da irradiação direta pela global), ′ D K (razão da irradiação direta pela do topo da atmosfera). Realizou-se uma análise estatística dos dados de radiação solar, de forma a se obter os valores médios, desvios, máximos, mínimos, variação e acumulados, mensais e anuais. E apresentaram-se de forma gráfica os resultados estatísticos obtidos para compará-los com os valores médios mensais diários da precipitação, nebulosidade e insolação, para que se possam explicar os fenômenos que causam as variações nos valores da série temporal de radiação solar na superfície terrestre de Botucatu. Os valores médios mensais diários da radiação global variaram de 21,0 MJ/m² em novembro até 12,6 MJ/m² em junho. A fração t K media anual foi de 53,0%. Os valores médios mensais diários da radiação difusa variaram de 10,0 MJ/m² em dezembro... / The present work presents the potential of solar energy available in the city of Botucatu, by analyzing time series of annual average daily, monthly averages of daily and cumulative monthly series of annual global radiation, diffuse and horizontal direct in the period of 1996 to 2005. The irradiation in MJ/m2 were calculated from daily integrations of the global irradiance , diffuse irradiance , horizontal direct irradiance and at the top of the atmosphere , by providing daily the daily irradiation: , and ; and monthly averages: G I d I D I O I dG H d d H dD H dG H , d d H and dD H . From the monthly averages, it was determined the clearness index t K (global/top of the atmosphere irradiation), and other fractions of radiation: d K (diffuse/global irradiation), ′ d K (diffuse/top of the atmosphere irradiation), D K (direct/global irradiation), ′ D K (direct/top of the atmosphere irradiation). Was held a statistical analysis of data on solar radiation in order to obtain the average values, deviation, minimum, maximum, variation and cumulative, monthly and yearly. And it showed in graphic statistical results obtained to compare them with the monthly average daily values of precipitation, cloudiness and sunshine, so that can explain the phenomena that cause variation in te values of time series of solar radiation on the Earth's surface of Botucatu. The values daily monthly average global radiation varied from 21.0 MJ/m² in november to 12,6 MJ/m² in june. The average annual t K fraction was 53,0%. The values daily monthly average diffuse radiation varied from 10,0 MJ/m² in december to 3,7 MJ/m² in june. The average annual d K fraction was 37% and the average annual ′ d K fraction was 19,7%. The values daily average monthly direct radiation varied from 11,8 MJ/m² in november... (Complete abstract click electronic access below)

Resumo: No presente trabalho é apresentado o estudo do potencial da energia solar disponível no município de Botucatu, através das análises das séries temporais médias anuais diárias, médias mensais diárias e séries anuais dos acumulados mensais das radiações global, difusa e direta na horizontal do período de 1996 à 2005. As irradiações, em MJ/m2, foram calculadas a partir das integrações diárias das irradiâncias global , irradiância difusa , irradiância direta na horizontal e no topo da atmosfera , determinando-se as irradiações diárias: , e ; e médias mensais: G I d I D I O I dG H d d H dD H dGH , d d H e dD H . A partir das médias mensais, determinou-se o índice de claridade t K (razão da irradiação global pela do topo da atmosfera), e as demais frações das radiações: d K (razão da irradiação difusa pela global), ′ d K (razão da irradiação difusa pela do topo da atmosfera), D K (razão da irradiação direta pela global), ′ D K (razão da irradiação direta pela do topo da atmosfera). Realizou-se uma análise estatística dos dados de radiação solar, de forma a se obter os valores médios, desvios, máximos, mínimos, variação e acumulados, mensais e anuais. E apresentaram-se de forma gráfica os resultados estatísticos obtidos para compará-los com os valores médios mensais diários da precipitação, nebulosidade e insolação, para que se possam explicar os fenômenos que causam as variações nos valores da série temporal de radiação solar na superfície terrestre de Botucatu. Os valores médios mensais diários da radiação global variaram de 21,0 MJ/m² em novembro até 12,6 MJ/m² em junho. A fração t K media anual foi de 53,0%. Os valores médios mensais diários da radiação difusa variaram de 10,0 MJ/m² em dezembro... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract : The present work presents the potential of solar energy available in the city of Botucatu, by analyzing time series of annual average daily, monthly averages of daily and cumulative monthly series of annual global radiation, diffuse and horizontal direct in the period of 1996 to 2005. The irradiation in MJ/m2 were calculated from daily integrations of the global irradiance , diffuse irradiance , horizontal direct irradiance and at the top of the atmosphere , by providing daily the daily irradiation: , and ; and monthly averages: G I d I D I O I dG H d d H dD H dG H , d d H and dD H . From the monthly averages, it was determined the clearness index t K (global/top of the atmosphere irradiation), and other fractions of radiation: d K (diffuse/global irradiation), ′ d K (diffuse/top of the atmosphere irradiation), D K (direct/global irradiation), ′ D K (direct/top of the atmosphere irradiation). Was held a statistical analysis of data on solar radiation in order to obtain the average values, deviation, minimum, maximum, variation and cumulative, monthly and yearly. And it showed in graphic statistical results obtained to compare them with the monthly average daily values of precipitation, cloudiness and sunshine, so that can explain the phenomena that cause variation in te values of time series of solar radiation on the Earth's surface of Botucatu. The values daily monthly average global radiation varied from 21.0 MJ/m² in november to 12,6 MJ/m² in june. The average annual t K fraction was 53,0%. The values daily monthly average diffuse radiation varied from 10,0 MJ/m² in december to 3,7 MJ/m² in june. The average annual d K fraction was 37% and the average annual ′ d K fraction was 19,7%. The values daily average monthly direct radiation varied from 11,8 MJ/m² in november... (Complete abstract click electronic access below) / Orientador: João Francisco Escobedo / Coorientador: Eduardo Nardini Gomes / Banca: Dinival Martins / Banca: Alexandre Dal Pai / Mestre

Ever since the first observations of diffuse ultraviolet radiation by Hayakawa et al. (1969) and Lillie & Witt (1976), there has been an effort to understand its distribution and its origin. Unfortunately, because of the difficulty of the observations and the faintness of the background, many of the early observations were conspicuous more by their disagreements than by the light they shed on the topic. The state of the observations and theories before 1990 have been reviewed by Bowyer (1991) and Henry (1991). There has been significant progress in more recent years, particularly in the far ultraviolet (< 1200˚A) where Murthy et al. (1999) and Murthy & Sahnow (2004) have used spectroscopic data from the Voyager and FUSE (Far Ultraviolet Spectroscopic Explorer) spacecraft, respectively, to trace the radiation field over many different locations in the sky. There have also been a number of observations at longer wavelengths, most recently by the SPEAR instrument (Ryu et al. 2008, and references therein), but no systematic study of the UV background. The Galaxy Evolution Explorer (GALEX) offers us the opportunity to extend coverage of the diffuse background to a significant fraction of the sky with a sensitivity of better than 100 photons cm−2 sr−1 s−1 ˚A−1 . In this work, we will report on one such observation, that of the nebulosity observed near M82 by Sandage (1976). These GALEX observations are the first to probe the diffuse UV background at a spatial resolution comparable to other surveys of dust emission, notably the IR. We obtain a quantitative estimate of the Airglow, the Zodiacal Light and the Extragalactic Background Radiation. We have modelled the data with our monte carlo scattering simulation program, and inferred an estimate of albedo and scattering phase function parameter of the dust in Sandage region. In this thesis the methods and results of these deductions are explained in detail.