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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Monitoring of aerosol chemical composition by remote sensing : Verification of the concept and methodology development / Suivi de la composition chimique des aérosols par télédétection : vérification du concept et développement de la méthodologie

Li, Lei 31 January 2018 (has links)
La détermination de la composition chimique des aérosols atmosphériques est essentielle pour le climat terrestre et l’environnement. Néanmoins, les mesures in situ qui permettent d’accéder à cette composition sont limitées et les modèles de chimie-transport peuvent ne pas bien représenter la réalité. Notre travail de thèse a consisté à développer une nouvelle approche afin de remonter à la composition des aérosols à grande échelle par télédétection. Les modèles de mélange des composants des aérosols, soit par proportion en volume soit par l’approximation de Maxwell Garnett qui relient les propriétés optiques à la composition, ont été incorporés dans l’algorithme de restitution des propriétés atmosphériques (GRASP). La nouveauté du concept réside dans la restitution directe des composants chimiques de l’aérosol plutôt que dans une estimation indirecte à partir des propriétés optiques retrouvées. Les tests synthétiques ont montré une sensibilité des observations du satellite POLDER/PARASOL à la présence d’éléments chimiques clés des aérosols. La méthodologie a ensuite été appliquée aux mesures réelles. Les caractéristiques optiques dérivées de PARASOL en utilisant le module de composition chimique ont montré un bon accord (R de ~ 0,9 pour l’épaisseur optique) avec nos mesures de référence — le réseau AERONET. La méthodologie a aussi été appliquée aux mesures de AERONET. Les variabilités spatiale et temporelle de la composition de l’aérosol ainsi retrouvée correspondent bien à nos attentes. La composition obtenue a également été validée à l’aide de données de campagne de terrain et a pu être comparée avec les simulations réalisées avec le modèle chimie-transport GOCART. / Determination of atmospheric aerosol chemical composition has a great importance for Earth’s climate and environment. However, in situ measurements that enable determination of aerosol composition are limited in time and space, while simulations by chemical transport models may not accurately describe the reality. The current thesis presents a novel methodology for monitoring of aerosol composition by remote sensing on large spatial and temporal scale. Namely, the volume-weighted and Maxwell Garnett models, which link the aerosol optical properties and chemical composition, were incorporated into the first versatile algorithm (GRASP) that derives the atmospheric properties from remote sensing. The concept proposes the direct retrieval of fractions of aerosol chemical components instead of post-processing estimate of the aerosol composition from the retrieved optical properties (refractive index, aerosol sizes). The tests showed sufficient sensitivity of the POLDER/PARASOL satellite observations to presence of key aerosol chemical elements. Then, the methodology was applied for the real PARASOL measurements. The aerosol optical characteristics derived from PARASOL using the chemical composition module demonstrated a good agreement with our reference measurements – AERONET ground-based network (e.g., R of ~ 0.9 for aerosol optical thickness). The methodology was then applied to the AERONET measurements as well. The obtained spatial and temporal patterns of aerosol composition agree well with known physical expectations. The retried aerosol composition was validated using available field campaign data and inter-compared with GOCART chemical transport model simulations.
2

Contribution des observations ChArMEx en Méditerranée à l’analyse des produits avancés aérosols POLDER-3/PARASOL / Contribution of ChArMEx observations in the Mediterranean region to the analysis of POLDER-3/PARASOL advanced aerosol products

Mbemba Kabuiku, Lydie 06 October 2017 (has links)
Par diffusion et absorption des rayonnements solaire et terrestre, et en modifiant les propriétés des nuages, les aérosols atmosphériques exercent un forçage direct et indirect sur le climat encore difficile à estimer dans le présent et à prédire pour le futur. Ces considérations s’appliquent au bassin méditerranéen, l’une des régions du globe climatiquement sensible, où on trouve de fortes concentrations en aérosols issus de sources diverses, naturelles (aérosols marins, poussières sahariennes) et anthropiques (industrie, transport, feux intentionnels). Dans ce contexte, les observations satellitaires sont incontournables pour décrire la distribution spatiale et l’évolution temporelle à long terme des concentrations et propriétés des aérosols, et en déterminer les impacts. En particulier, l’instrument POLDER-3/PARASOL (2005-2013) est un capteur polarisé, multi-spectral/directionnel qui permet d’accéder à différentes propriétés optiques des aérosols, notamment au-dessus des océans, avec une distinction entre les composantes fines, grossières sphériques/non-sphériques des aérosols. Dans ce cadre, ma thèse a porté sur la validation poussée des produits aérosols mesurées par POLDER (notamment des épaisseurs optiques des fractions grossières sphériques/non-sphériques non validées à ce jour), avec les observations de télédétection et in situ des propriétés optiques et physico-chimiques, obtenues grâce aux campagnes du projet ChArMEx en Méditerranée (étés 2012-2013), afin d’évaluer leurs potentiels à caractériser et quantifier les aérosols dans la région. Cette validation permet de dresser une cartographie régionale des aérosols et analyser leur distribution spatiale et temporelle avec une distinction sur leur taille et leur forme / By scattering and absorbing solar and terrestrial radiations, and by modifying the properties of clouds, atmospheric aerosols have a direct and indirect radiative forcing on the climate that is still difficult to estimate and to predict. These considerations apply to the Mediterranean basin, one of the major climatic hot-spot of the globe, where there are high concentrations of aerosols from various natural (marine aerosols, Saharan dust) and anthropogenic (industry, transport, intentional fires) sources. In this context, satellite observations are essential to describe the spatial distribution and long-term temporal evolution of aerosol concentrations and properties, and to determine their impacts. In particular, POLDER-3 / PARASOL spatial instrument (2005-2013) is a polarized, multi-spectral/directional sensor that allows access to different optical properties of aerosols, especially over oceans, with a distinction between fine and coarse spherical / non-spherical aerosol components. In this framework, my thesis focused on the thorough validation of aerosol products measured by POLDER (notably the aerosol optical depth of the coarse spherical/non-spherical fractions not evaluated at the time of this work), with remote sensing and in situ observations of optical and physic-chemical properties obtained from ChArMEx project in the Mediterranean basin (summers 2012-2013) to assess their potential to characterize and quantify aerosols in this region. Thanks to this validation, it is possible to map and to analyze aerosol spatial and temporal distribution with a distinction on their size and their shape
3

Energy Saving Curtain : ENERGY INVENTORY AND CONSERVATION POSSIBILITIES

Zou, Fan January 2008 (has links)
<p>This paper presents the energy saving curtains, in order to make the</p><p>consumers be more aware of the energy efficiency of the energy saving</p><p>curtains, the paper gave related analysis and conclusions.</p><p>The work was performed by using the Parasol Program, developed by Lunds University, Sweden. The Program is used for quantifying the influence of window size, glass type, textile type, wall thermal insulation and sun shading on annual energy use and indoor thermal comfort. The results which are obtained from the calculations are applicable to similar climatic and environment conditions. Calculations were performed to investigate the potential for using sunshade devices to reduce annual energy demand for cooling and heating. Different materials and dimensions of the energy saving</p><p>curtain are used as variables in the analysis. The results indicated that for the current climatic conditions and other related factors, the total reduction rate of the annual energy consumption of office used buildings in Stockholm is estimated generally 20% -30% lower comparing to those buildings without energy saving curtain system. That means at least 20% of energy cost can be saved by the energy saving curtain system.</p>
4

Energy Saving Curtain : ENERGY INVENTORY AND CONSERVATION POSSIBILITIES

Zou, Fan January 2008 (has links)
This paper presents the energy saving curtains, in order to make the consumers be more aware of the energy efficiency of the energy saving curtains, the paper gave related analysis and conclusions. The work was performed by using the Parasol Program, developed by Lunds University, Sweden. The Program is used for quantifying the influence of window size, glass type, textile type, wall thermal insulation and sun shading on annual energy use and indoor thermal comfort. The results which are obtained from the calculations are applicable to similar climatic and environment conditions. Calculations were performed to investigate the potential for using sunshade devices to reduce annual energy demand for cooling and heating. Different materials and dimensions of the energy saving curtain are used as variables in the analysis. The results indicated that for the current climatic conditions and other related factors, the total reduction rate of the annual energy consumption of office used buildings in Stockholm is estimated generally 20% -30% lower comparing to those buildings without energy saving curtain system. That means at least 20% of energy cost can be saved by the energy saving curtain system.
5

Retrieval of Non-Spherical Dust Aerosol Properties from Satellite Observations

Huang, Xin 16 December 2013 (has links)
An accurate and generalized global retrieval algorithm from satellite observations is a prerequisite to understand the radiative effect of atmospheric aerosols on the climate system. Current operational aerosol retrieval algorithms are limited by the inversion schemes and suffering from the non-uniqueness problem. In order to solve these issues, a new algorithm is developed for the retrieval of non-spherical dust aerosol over land using multi-angular radiance and polarized measurements of the POLDER (POLarization and Directionality of the Earth’s Reflectances) and wide spectral high-resolution measurements of the MODIS (MODerate resolution Imaging Spectro-radiometer). As the first step to account for the non-sphericity of irregularly shaped dust aerosols in the light scattering problem, the spheroidal model is introduced. To solve the basic electromagnetic wave scattering problem by a single spheroid, we developed an algorithm, by transforming the transcendental infinite-continued-fraction-formeigen equation into a symmetric tri-diagonal linear system, for the calculation of the spheroidal angle function, radial functions of the first and second kind, as well as the corresponding first order derivatives. A database is developed subsequently to calculate the bulk scattering properties of dust aerosols for each channel of the satellite instruments. For the purpose of simulation of satellite observations, a code is developed to solve the VRTE (Vector Radiative Transfer Equation) for the coupled atmosphere-surface system using the adding-doubling technique. An alternative fast algorithm, where all the solid angle integrals are converted to summations on an icosahedral grid, is also proposed to speed-up the code. To make the model applicable to various land and ocean surfaces, a surface BRDF (Bidirectional Reflectance Distribution Function) library is embedded into the code. Considering the complimentary features of the MODIS and the POLDER, the collocated measurements of these two satellites are used in the retrieval process. To reduce the time spent on the simulation of dust aerosol scattering properties, a single-scattering property database of tri-axial ellipsoid is incorporated. In addition, atmospheric molecule correction is considered using the LBLRTM (Line-By-Line Ra- diative Transfer Model). The Levenberg-Marquardt method was employed to retrieve all the interested dust aerosol parameters and surface parameters simultaneously. As an example, dust aerosol properties retrieved over the Sahara Desert are presented.
6

Hydrological and sediment Yield modelling in Lake Tana Basin, Blue Nile Ethiopia

Setegn, Shimelis Gebriye January 2008 (has links)
<p>Land and water resources degradation are the major problems on the Ethiopian highlands. Poor land use practices and improper management systems have played a significant role in causing high soil erosion rates, sediment transport and loss of agricultural nutrients. So far limited meas-ures have been taken to combat the problems. In this study a physically based watershed model, SWAT2005 was applied to the Northern Highlands of Ethiopia for modelling of the hydrology and sediment yield. The main objective of this study was to test the performance and feasibility of SWAT2005 model to examine the influence of topography, land use, soil and climatic condi-tion on streamflows, soil erosion and sediment yield. The model was calibrated and validated on four tributaries of Lake Tana as well as Anjeni watershed using SUFI-2, GLUE and ParaSol algo-rithms. SWAT and GIS based decision support system (MCE analysis) were also used to identify the most erosion prone areas in the Lake Tana Basin. Streamflows are more sensitive to the hy-drological response unites definition thresholds than subbasin discretization. Prediction of sedi-ment yield is highly sensitive to subbasin size and slope discretization. Baseflow is an important component of the total discharge within the study area that contributes more than the surface runoff. There is a good agreement between the measured and simulated flows and sediment yields with higher values of coefficients of determination and Nash Sutcliffe efficiency. The an-nual average measured sediment yield in Anjeni watershed was 24.6 tonnes/ha. The annual aver-age simulated sediment yield was 27.8 and 29.5 tonnes/ha for calibration and validation periods, respectively. The SWAT model indicated that 18.5 % of the Lake Tana Basin is erosion potential areas. Whereas the MCE result indicated that 25.5 % of the basin are erosion potential areas. The calibrated model can be used for further analysis of the effect of climate and land use change as well as other different management scenarios on streamflows and soil erosion. The result of the study could help different stakeholders to plan and implement appropriate soil and water conser-vation strategies.</p>
7

Effektivisering vid bedömningsprocessen av  indikatorn Dagsljus för miljöcertifieringsmetoden Miljöbyggnad : Ett förprojekteringsverktyg

Fredriksson, Jane, Weissmann, Angelica January 2015 (has links)
Dagsljus i byggnader är viktigt för både den fysiska och psykiska hälsan. Dagsljusinsläpp i byggnader sker genom fönster, men fönster är även den byggnadskomponent som medför störst energiförluster i en byggnad. Därför finns det problem i att skapa en god balans mellan utformning, energieffektivisering och termisk komfort samtidigt som ett tillfredsställande dagsljus ska tillämpas i byggnader där människor vistas. Detta examensarbete som omfattar 15 hp syftar till att effektivisera samt förenkla bedömningen av ett tillfredsställande dagsljus, för att uppnå kraven i miljöcertifieringsmetoden Miljöbyggnad, där även intilliggande faktorer som energi och termiskt klimat studeras. Målet var att upprätta ett förprojekteringsverktyg för indikatorn Dagsljus som i framtiden kan användas av konsulter, arkitekter och andra inom byggbranschen när en byggnad ska miljöcertifieras enligt metoden Miljöbyggnad. För att skapa verktyget gjordes datamodeller av testrum med olika förutsättningar, där dagsljusfaktorn, DF, kontrollerades. Under arbetets gång har datorprogrammen Velux, ParaSol och Thermal Comfort Calculator använts. Parameterstudier utfördes för att åskådliggöra samband mellan dagsljusfaktor, fönsterarea samt rummets form och storlek, vilket resulterade i att två diagram upprättades. För att kontrollera att parameterstudiens resultat kan tillämpas för verkliga objekt och rum utfördes en fallstudie på byggnaden Ängsbacken i Sandviken. Denna fallstudie validerade att diagrammen som upprättats kan uppskatta en dagsljusfaktor, DF, för ett rum som sedan kan erhålla ett preliminärt betyg för indikatorn Dagsljus inom Miljöbyggnad. Diagrammen som upprättats kan användas som ett grovt förprojekteringsverktyg som kan tillämpas när konsult, arkitekt m.fl känner till rumsdjup samt fasadväggens area (bredden och höjden i rummet) men vill veta hur stort fönster som krävs för att uppnå BRONS eller SILVER för indikatorn Dagsljus inom Miljöbyggnad. Vidare kan vara intressant att studera om det även finns ett samband mellan de tre indikatorerna Dagsljus, Solvärmelast och Termiskt klimat och vilken påverkan fönsterglas, solavskärmningar m.m kan ha på dagsljusfaktorn. För samtliga testrum som modellerats och tillämpats i studien har betyget GULD erhållits för Solvärmelasten. För det Termiska klimatet fick samtliga testrum betyget SILVER. Dessa indikatorer verkar inte påverkas av rummets geometri i lika stor utsträckning som dagsljusfaktorn, som tar mer hänsyn till både rummets och fönstrets storlek samt utformning. Därför bör vid bedömning enligt Miljöbyggnad största vikt ligga på att uppfylla ett tillfredsställande dagsljusinsläpp genom att kontrollera att dagsljusfaktorn uppfylls i rummet, vilket enkelt kan utföras med hjälp av studiens förprojekteringsverktyg. Det effektiva förprojekteringsverktyget kan användas för att förenkla och påskynda bedömningsprocessen samt uppskatta ett betyg för indikatorn Dagsljus inom Miljöbyggnad. Genom att använda sig av verktyget i ett tidigt projekteringsskede, där användningen av tidskrävande datorprogram undviks, kan både kostnader och tid minimeras. / Daylight in buildings is important for both physical and mental health. Daylighting in buildings is transferred through windows, but the windows are also the building component that causes the greatest energy loss in a building. Therefore, there is a problem in creating a good balance between design, energy efficiency and thermal comfort while maintaining a sufficient daylight to be applied in buildings where people are staying. This thesis comprising 15 hp aims to efficiency and simplify the assessment of satisfying daylight, to achieve the requirements of the environmental certification method Miljöbyggnad, where neighboring factors such as energy and the thermal environment is studied. The goal was to establish a pre-planning tool for the indicator Daylight that can be used in the future by consultants and similar when a building is assessed by environmental certification according to the method Miljöbyggnad. The tool is based on computer models of experimental room with different conditions where the daylight factor, DF, was controlled. The computer programs Velux, ParaSol and Thermal Comfort Calculator where applied during the study. Parametric studies were performed to illustrate the connection between daylight factor, window area and the shape and size of the room, resulting in the establishment of two charts. To check that the parameter results of the study can be applied to real-world objects and rooms a case study was performed on the building Ängsbacken in Sandviken. This case study validated that the diagrams drawn can appreciate a daylight factor, DF, for a room that can then obtain a preliminary rating for the indicator Daylight in Miljöbyggnad. The diagrams can be used as a rough pre-planning tool that can be applied when the consultant, architect or similar knows the room depth and facadewall area (width and height of the room) but want to know how big window needed to achieve BRONZE or SILVER for indicator Daylight in Miljöbyggnad. In the future it might be interesting to study if there is also a correlation between the three indicators Daylight, Solar Thermal Load and Thermal environment and the impact of windows, sun screens etc. which can affect the daylight factor. For all test room modeled and applied in the study, grade GOLD were obtained for the Solarheating. For the Thermal environment all the test room obtained the grade SILVER. These indicators seem unaffected by the geometry just as much as the daylight factor, which takes more into account both the room and the window size and design. Therefore the assessment according to Miljöbyggnad paramount lie on meeting a satisfying daylight by checking that the daylight factor is fulfilled in the room, which can easily be performed with the help of this studies pre-planning tool. The effective pre-planning tool can be used to simplify and speed up the evaluation process and appreciate a score for indicator Daylight in Miljöbyggnad. By making use of the tool in an early planning stage, where the use of time-consuming computer programs is avoided, both the cost and time can be minimized.
8

Hydrological and sediment yield modelling in Lake Tana Basin, Blue Nile Ethiopia

Setegn, Shimelis Gebriye January 2008 (has links)
Land and water resources degradation are the major problems on the Ethiopian highlands. Poor land use practices and improper management systems have played a significant role in causing high soil erosion rates, sediment transport and loss of agricultural nutrients. So far limited meas-ures have been taken to combat the problems. In this study a physically based watershed model, SWAT2005 was applied to the Northern Highlands of Ethiopia for modelling of the hydrology and sediment yield. The main objective of this study was to test the performance and feasibility of SWAT2005 model to examine the influence of topography, land use, soil and climatic condi-tion on streamflows, soil erosion and sediment yield. The model was calibrated and validated on four tributaries of Lake Tana as well as Anjeni watershed using SUFI-2, GLUE and ParaSol algo-rithms. SWAT and GIS based decision support system (MCE analysis) were also used to identify the most erosion prone areas in the Lake Tana Basin. Streamflows are more sensitive to the hy-drological response unites definition thresholds than subbasin discretization. Prediction of sedi-ment yield is highly sensitive to subbasin size and slope discretization. Baseflow is an important component of the total discharge within the study area that contributes more than the surface runoff. There is a good agreement between the measured and simulated flows and sediment yields with higher values of coefficients of determination and Nash Sutcliffe efficiency. The an-nual average measured sediment yield in Anjeni watershed was 24.6 tonnes/ha. The annual aver-age simulated sediment yield was 27.8 and 29.5 tonnes/ha for calibration and validation periods, respectively. The SWAT model indicated that 18.5 % of the Lake Tana Basin is erosion potential areas. Whereas the MCE result indicated that 25.5 % of the basin are erosion potential areas. The calibrated model can be used for further analysis of the effect of climate and land use change as well as other different management scenarios on streamflows and soil erosion. The result of the study could help different stakeholders to plan and implement appropriate soil and water conser-vation strategies. / QC 20101123

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