Dans un contexte de performance énergétique et de durabilité dans le secteur du bâtiment, la maîtrise du comportement hygrothermique des matériaux d'enveloppe, notamment hygroscopiques, est essentielle. Les travaux réalisés concernent la compréhension et la modélisation des transferts de chaleur et d'humidité au sein d'une paroi multicouche de bâtiment composée de matériaux biosourcés.Une attention particulière est portée sur les phénomènes d'hystérésis observés sur les isothermes de sorption. Un modèle numérique 1D développé sur COMSOL Multiphysics est exploité pour simuler en régime transitoire les champs de température et de pression de vapeur dans trois situations. La première concerne l'étude du comportement hygrothermique de matériaux fortement hygroscopique (béton de chanvre) et faiblement hygroscopiques (enduits à base de chaux) soumis à diverses variations cycliques d'humidité relative. Un bon accord est constaté entre les simulations et des mesures d'humidité relative, de température et de teneur en eau. Néanmoins, les résultats présentent une forte sensibilité aux propriétés hydriques. Dans un second temps, une étude est menée sur une paroi de béton de chanvre instrumentée placée dans une enceinte bi-climatique et exposée à des variations de température et d'humidité relative. La confrontation des évolutions mesurées et calculées montre la nécessité de bien définir le champ de teneur en eau initiale. La dernière étude concerne une paroi multicouche (béton de chanvre et enduits). Il apparaît que les enduits jouent un rôle important sur le comportement de la paroi et il est nécessaire de prendre en compte l'influence de la température sur les courbes de sorption. / In a context of energy efficiency and durability in the field of building, the understanding of hygrothermal behaviour of building materials, especially hygroscopic ones, is essential. This study aim to understand and model heat and moisture transfers in a multi-layer building wall made of biosourced materials. We focus in particular on hysteretic phenomena observed on sorption isotherms. A one-dimensional numerical model developed with the COMSOL Multiphysics software is used to simulate transient temperature and vapour pressure in three situations. The first one is about the hygrothermal behaviour of materials, highly hygroscopic (hemp concrete) and lowly hygroscopic (lime-based plasters), exposed to several cyclical variations of relative humidity. A good agreement is observed between simulated and measured values of relative humidity, temperature and moisture content. However, results are highly sensitive to hydric properties. Then, a study is performed on an instrumented hemp-concrete wall built in a bi-climatic chamber and exposed to simultaneous temperature and relative humidity variations. The confrontation between measured and simulated values shows the importance of initial moisture content.

Le satellite altimétrique interférométrique SWOT, dont le lancement est prévu pour 2020, devrait pour la première fois permettre une couverture globale en quelques jours d'un radar proche-nadir en utilisant la bande de fréquence Ka. Or, l'utilisation d'une telle bande de fréquence est encore mal documentée pour l'hydrologie continentale. En particulier, le contraste du coefficient de rétrodiffusion sur les sols et sur les surfaces en eau pour des angles de visée nadir et proche nadir est une problématique majeure. C'est ce qui fait l'objet de ces travaux de thèse. Dans un premier temps, l'étude de la variation des coefficients de rétrodiffusion en provenance d'altimètres en bandes C et Ku et de diffusiomètres utilisant les mêmes bandes de fréquence sur l'Afrique de l'Ouest a montré qu'il existe un lien quantifiable entre l'humidité du sol et le coefficient de rétrodiffusion. En région semi-aride ce lien se manifeste via une hausse des coefficients de rétrodiffusions durant la saison humide par rapport à la saison sèche. L'analyse avec des données annexes d'humidité du sol et de précipitations a pu également montrer que le radar nadir détecte plus précisément les changements d'humidité du sol par rapport à la diffusiométrie radar à visée latérale. Dans le but de mieux comprendre la rétrodiffusion en bande Ka, très peu documentée, deux campagnes de mesures radar ont été réalisées, l'une sur des surfaces en eau à rugosité contrôlée, l'autre sur un terrain contrôlé en rugosité et humidité du sol. En parallèle, un programme de simulation de la rétrodiffusion altimétrique a été développé pour pouvoir analyser les effets d'un faible nombre de variables sur des sols réalistes, dans le but de simuler les variations du coefficient de rétrodiffusion. Ces mesures et ces simulations ont ensuite pu être comparées aux séries temporelles issues du satellite altimétrique AltiKa, fonctionnant en bande Ka et lancé en février 2013, sur différents sites représentatifs des régions bio-climatiques d'Afrique de l'Ouest. Il en ressort que la bande Ka présente une forte sensibilité aux changements d'humidité du sol. Il est également montré que les coefficients de rétrodiffusion en provenance d'AltiKa sur les sols et sur l'eau peuvent être similaires au nadir. / The radar altimetry interferometry satellite SWOT, which is to be launched in 2020, should provide for the first time a global coverage of a close-to-nadir radar altimeter in a few days using the Ka-band. Yet, the use of such a frequency band for continental hydrology is still poorly documented. In particular, the contrast of the backscattering coefficient over soils and over water bodies for nadir and close-to-nadir angles is a major issue. This is the reason for this work. First, the study of the backscattering coefficients from C- and Ku- band altimeters and scatterometers over West Africa has shown that there is a link between the surface soil moistureand the backscattering coefficient. In semi-arid regions, this link is seen through a rise of the backscattering coefficients during the rainy season compared to the dry season. The analysis with ancillary data such as the surface soil moisture and the precipitation estimations has also shown that nadir-looking radars detect more precisely the changes in surface soil moisture compared to side-looking radars. Still with the purpose to better understand the Ka-band surface scattering, poorly documented, two measurement campaigns were led, on the one hand over water surface with controlled roughness, on the other hand over bare soils with monitored roughness and surface soil moisture. In parallel, an altimetry backscattering simulation program has been developed to analyze the effect of a low number of variables on realistic grounds, with the aim of simulating the backscattering coefficient variations. These measurements and simulations were then compared with time series from the satellite altimeter AltiKa, which has been launched in 2013 and works at Ka-band, over different sites representaing the bioclimatic areas of West Africa. It led to a high sensitivity of the Ka-band to changes in the surface soil moisture. It has also been shown that backscattering coefficients at nadir-looking angle from AltiKa over grounds and over water bodies can be similar.

Joints are critical parts of timber structures, transmitting static and dynamic forces between structural members. The ultimate behavior of a loaded building depends strongly on the structural configuration and the capacity of the joints. The collapse of a whole building or less extensive accidents that may occur is usually starting as a local failure inside or in the vicinity of a joint. Such serious failures have recently occurred in our Nordic countries. Especially the collapse of two large glued laminated timber structures clearly indicates the need of an improved joint design. The trend toward larger and more complex structures even further increases the importance of a safer design of the joints. An aim of this partly experimental and partly numerically based thesis has been to investigate if steel-to-timber dowel joints are affected by moisture-induced stresses. The experimental results showed that the load-bearing capacity of the joints is reduced by such a moisture influence. Most of the decrease in load-bearing capacity observed was found in joints initially exposed to restrained shrinkage deformations caused by the presence of dowel fasteners in the joint area. The load-bearing capacity was, however, also found to decrease in joints exposed to an initial decrease in moisture without any fasteners present in the specimens during storage before loading. An explanation of this unexpected behavior is that moisture gradients cause tensile stresses. It is shown by numerical simulations that the moisture-induced stresses are so large that they may have a considerable influence on the joint behavior. Use of contact-free measurement methods, used in some of the experimental tests, was in many ways found to be superior to traditional measurement techniques, but was also found to be a valuable complement to the numerical analysis performed. From numerical results obtained in combination with results from contact-free measurements several observations of considerable interest were made. For dowel-type joints loaded in tension parallel to the grain a strongly non-uniform strain distribution was found in the joint area. It was further observed that the shear and tensile strains were concentrated close to the fasteners in the joint area. These concentrations will influence the failure mode of the joint. A general observation was that the larger sized joints failed in a brittle manner. Keywords: constraint stresses, contact-free measurement, dowel-type joints, humidity variations, moisture-induced deformations, timber structures

Magister Scientiae (Biodiversity and Conservation Biology) / Elevated temperatures accompanying climate warming are expected to have adverse effects on sensitive lichen species. This premise was examined by measuring the sensitivity of different lichen species to elevated temperatures in the laboratory and in the field. Laboratory studies involved the exposure of nine hydrated lichen species (Xanthoparmelia austro-africana, X. hyporhytida, Xanthoparmelia sp., Xanthomaculina hottentotta, Teloschistes capensis, Ramalina sp., Flavopuntelia caperata, Lasallia papulosa, Parmotrema austrosinensis) collected from sites of different aridity and mean annual temperature for 2 hourly intervals to temperatures ranging from 24ºC to 48ºC in a forced daft oven and measuring their respiration rates and maximum quantum yield of PSII. Field studies involved simultaneous hourly measurements of ground surface air temperatures and Lichen effective quantum yield of PSII of hydrated lichen species populations under ambient and artificially modified environmental conditions. / South Africa

Extensive areas of the Eastern Cape Province have been invaded by Pteronia incana (Blue bush), a non-palatable patchy invader shrub that is associated with soil degradation. This study sought to establish the relationship between the invasion and a range of eco-physical and land use gradients. The impact of the invader on soil moisture flux was investigated by comparing soil moisture variations under grass, bare and P. incana invaded surfaces. Field based and laboratory spectroscopy was used to validate P. incana spectral characteristics identified from multi-temporal High Resolution Imagery (HRI). A belt transect was surveyed to gain an understanding of the occurrence of the invasion across land use, isohyetic, geologic, vegetation, pedologic and altitudinal gradients. Soil moisture sensors were calibrated and installed under the respective surfaces in order to determine soil moisture trends over a period of six months. To classify the surfaces using HRI, the pixel and sub-pixel based Perpendicular Vegetation Index (PVI) and Spectral Mixture Analysis (SMA) respectively were used. There was no clear trend established between the underlying geology and P. incana invasion. Land disturbance in general was strongly associated with the invasion, as the endemic zone for the invasion mainly comprised abandoned cultivated and overgrazed land. Isohyetic gradients emerged as the major limiting factor of the invasion; a distinct zone below 619mm of mean annual rainfall was identified as the apparent boundary for the invasion. Low organic matter content identified under invaded areas was attributed to the patchy nature of the invader, leading to loss of the top soil in the bare inter-patch areas. The area covered by grass had consistently higher moisture values than P. incana and bare surfaces. The difference in post-rainfall moisture retention between grass and P. incana surfaces was significant up to about six days, after which a near parallel trend was noticed towards the ensuing rainfall episode. Whereas a higher amount of moisture was recorded on grass, the surface experienced moisture loss faster than the invaded and bare surfaces after each rainfall episode. ii There was consistency in multi-temporal Digital Number (DN) values for the surfaces investigated. The typically low P. incana reflectance in the Near Infrared band, identified from the multi-temporal HRI was validated by field and laboratory spectroscopy. The PVI showed clear spectral separability between all the land surfaces in the respective multi-temporal HRI. The consistence of the PVI with the unmixed surface image fractions from the SMA illustrates that using HRI, the effectiveness of the PVI is not impeded by the mixed pixel problem. Results of the laboratory spectroscopy that validated HRI analyses showed that P. incana’s typically low reflectance is a function of its leaf canopy, as higher proportions of leaves gave a higher reflectance. Future research directions could focus on comparisons between P. incana and typical green vegetation internal leaf structures as potential causes of spectral differences. Collection of spectra for P incana and other invader vegetation types, some of which have similar characteristics, with a view to assembling a spectral library for delineating invaded environments using imagery, is another research direction.

Coatings for exterior wood have two basic functions. One isto give an aesthetically acceptable surface appearance andcolour. The other is to provide protection against wooddegradation by microbiological or physical attack. Theseprotective properties, often called the barrier properties,play an important role in the selection of proper material forsupreme durability. The assessment of these barrier propertiesis of great importance. Within the CEN Technical Committee 139,Working Group 2, Coatings for exterior wood test methods andperformance specifications have been established. Forassessment of water protection efficiency a standard testprocedure, EN 927-5, has been launched. The present work hasfocused on its applicability in assessing water protectionefficiency in relation to the degradation of coatings duringexposure. Assessments according to EN 927-5 is shown to givesignificant differences in water absorption values fordifferent types of coatings on wood. The proposed performancespecifications in ENV 927 - 2 for the water absorption valuesfor coatings to be used in different constructions seem to beset at acceptable levels. It has been shown that there is agood correlation between the level of water absorption andpractical experience of the performance of paints inScandinavia. However, it has also been shown that thecombination of a standard procedure for water absorptionmeasurement and an artificial weathering procedure gives moreinformation regarding expected durability and longtermperformance than a single measurement of water absorption onfresh, unweathered coated wood. A combination of waterabsorption measurement and artificial weathering could become auseful tool in product development as well as in benchmarking.Together with statistical tools, such as reliability-basedservice life prediction methodologies for predicting theservice life of coating systems a reduction in testing timesmay be achieved. Surface-active substances in coatings have a negative effecton the coatings ability to prevent water ingress, which mostprobably is due to the hydrophilic character of thesesubstances. The presence of these substances, which are commonin waterborne coatings, alters the moisture sorptioncharacteristics of wood. Considering that these substancesoccur in waterborne coatings, may be mobilised during and afterfilm formation and accumulate at the coating/substrateinterface, there is a great probability that these substanceschange the moisture sorption characteristics of the woodsubstrate in an unfavourable way and create unexpected dynamicmoisture conditions at the coating/wood interface. Computerized tomography has been found to be a valuable,non-destructive tool for visualising the spatial moisturedistribution of water and moisture in coated wood panels. Themethod is suitable for recurrent testing of a specimen exposedto a series of processes of wetting, drying. This thesis showsthat high moisture contents occur locally at and around cracks.In these areas there is an increased risk of internal tensionand stress resulting in crack initiation and propagation andthat high moisture contents may occur in the first fewmillimetres under waterborne coatings despite intact coatingfilms. Even with good barrier properties of the coating,moisture may accumulate by water-vapour absorption in air gapsbehind the cladding thus causing favourable conditions formicrobiological colonization. The work that has been carried out regarding assessment ofthe water protection efficiency shows promising resultsregarding the possibility to use reliability-based service lifeprediction methodology for the assessment. The aim of futurework will be to establish more reliable techniques andprotocols for assessing service life expectancy and durability,especially for waterborne coatings with special focus ontendencies to early failure and robustness of the coatingsystems. Keywords:Coatings, surfactants, water absorption value,EN 927, paint, additives, moisture dynamics, absorption,desorption, artificial weathering, artificial exposure,computerized tomography, MRI. / <p>NR 20140805</p>

O aumento na produção de biodiesel e, consequentemente, de glicerina como subproduto, motivou a utilização desta na alimentação animal. Portanto, o presente trabalho objetivou avaliar as alterações fisiológicas do uso de glicerina na alimentação de frangos de corte, analisando o consumo e excreção de água, sua implicação na qualidade da cama e possível retenção de água pelas aves. Foram realizados três experimentos, dois com frangos de corte machos da linhagem Ross 308 e um com cama de aviário. No Experimento 1 (E1) foram utilizados 240 pintinhos distribuídos em 24 gaiolas em baterias, em um delineamento inteiramente aleatorizado (DIA) com 3 tratamentos e 8 repetições de 10 aves criadas até os 40 dias de idade. Os tratamentos foram compostos por dietas experimentais sendo: T1 - controle - à base de milho (M) e farelo de soja (FS); T2 - dieta com inclusão de 10% de glicerina loira (GL); T3 - dieta com inclusão de 8,75% de glicerina purificada (GP) para conter a mesma quantidade em glicerol que a GL. Foram avaliados o consumo de água, de ração e matéria seca (MS) das excretas como medidas repetidas no tempo. Aos 40 dias de idade foi determinada a MS do conteúdo ileal. Não houve efeito de tratamentos no consumo de ração. O consumo de água foi maior quando utilizada glicerina nas rações (T2 e T3). A relação consumo de água:ração apresentou interação tratamento × idade, sendo T2 e T3 maiores do que o controle até os 28 dias de idade e, após essa idade, o T3 passou a ser maior do que o T2. A matéria seca das excretas do T2 e T3 foi, de maneira geral, próxima ao T1 aos 16 e 20 dias e após os 24 dias de idade foi inferior. No Experimento 2 foi avaliada a capacidade de retenção de água (CRA) da cama composta por maravalha de madeira e as excretas das aves dos tratamentos do E1, acondicionadas em recipientes, em um DIA, composto por 3 tratamentos e 6 repetições. Por sete dias foi adicionada água à mistura. Foram avaliadas as umidades inicial e final para determinação da CRA, porém os resultados não apresentaram diferenças. No Experimento 3 foi elaborado um DIA similar ao E1, entretanto com os seguintes tratamentos: T1 - controle - dieta a base de M e FS; T2 - inclusão de 5% de GL; T3 - inclusão de 10% de GL. Foram realizados 2 abates (aos 7 e 42 dias de idade) e coletados: sangue, fígado, intestino músculo do peito e pintinho inteiro (apenas aos 7 dias), para avaliação da MS e proteína bruta (apenas músculo e fígado). As variáveis não apresentaram diferenças significativas, exceto pela MS do fígado, que foi menor para o T3. Os resultados indicam que aves alimentadas com níveis elevados de glicerina apresentam consumo e excreção de água maiores, podendo levar a uma piora na qualidade da cama. A matéria seca corporal, de maneira geral não foi afetada, exceção para a redução observada no fígado. / The increase in biodiesel production and, consequently, of glycerin as a byproduct, has led to its use in animal nutrition. Therefore, this study aimed to evaluate the physiological changes of feeding broilers with glycerin by analyzing water consumption and excretion, its effects on litter quality and possible water retention by poultry. Three experiments were conducted. Two comprised Ross 308 male broilers and one of poultry litter. In experiment 1 (E1), 240 chicks were distributed in 24 cages in batteries, in a completely randomized design (CRD) with three treatments and eight repetitions of 10 birds reared until 40 days of age. Experimental diets were used in the treatments: T1 - control - corn (C) and soybean meal based diet (SM); T2 - diet with 10% glycerin (GL); T3 - diet with 8.75% purified glycerin (GP) to contain the same amount in glycerol of GL. The consumption of water, feed and the dry matter (DM) of the excreta were evaluated as repeated measures in time. At 40 days of age, the DM of the ileal content was determined. There was no effect of treatments on feed consumption. Water consumption was higher when glycerin was used in the diet (T2, T3). The ratio for water:feed consumption showed interaction treatment × age, and in T2 and T3, it was greater than in the control until 28 days of age. Afterwards, T3 was greater than T2. The DM of the excreta of T2 and T3 was generally similar to that in T1 at 16 and 20 days of age, and after 24 days of age, it was lower. In experiment 2, it was evaluated the water retention capacity (WRC) of litter composed of wood shavings and excreta of the birds of treatments of E1, kept in bowls, in a CRD, composed of three treatments and six repetitions. For seven days, water was added to the mixture. It was evaluated the initial and final moisture to determine WRC. There was no difference among treatments. In E3, it was prepared a CRD similar to that in E1, with the following treatments: T1 - control - C and SMbased diet; T2 - 5% of GL; T3 - 10% of GL. Two slaughters were carried out (at 7 and 42 days of age) and it was collected: blood, liver, intestines, breast muscle and whole chick (only at 7 days) to evaluate DM and crude protein (only muscle and liver). The variables showed no significant differences, except for DM of the liver, which was lower for T3. The results show that birds fed high glycerin contents diets have increased water consumption and excretion; the increased water excretion is due to urinary loss and not to fecal loss. Body and tissue dry matter was not changed with the exception for a reduction found in the liver.

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In this report an illustration of a Home Irrigation System Using Internet Control by Arduino is proposed. This automated system for irrigation identifies the moisture content present in soil and automatically toggles the switching off pump when the power is supplied. An appropriate usage of irrigation system is necessary and it is essential to maintain suitable water content and avoid shortage of water due to lack of rain and spontaneous use of water, to avoid wastage of water. Due to this reason, this home irrigation system can be used to monitor soil moisture. Which is very useful in all climatic conditions. This project aims at reducing excessive and uncontrolled water usage as well as maintaining moisture content of the soil to get healthy irrigation. Home Irrigation System can be used for saving time using monitoring device thus minimizing human effort. Overall, the project achieved its primary goal to avoid the wastage of water while maintaining the moisture content of the soil with less delay in the processing time.

This dissertation is focused on a study of selected environmental effects influencing terrestrial gravity observations. Global geopotential models were used to compute quantities of the disturbing gravity field and its variations during time period. Furthermore, analyses of an atmospherical and hydrological effects on the gravity observations were provided. The computation was realized at the station Pecný, however the concept was proved and compared with data from station Strasbourg. Consequently, the results were discussed with respect to quasigeoid modelling established from gravity and astrogeodetic measurements. The result and recommendations for future research are exposed.