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Les systèmes microélectromécaniques (MEMS) sont des dispositifs de taille micrométrique capables de transformer un signal mécanique en un signal électrique et vice-versa. Ils sont aujourd'hui largement répandus dans notre vie quotidienne pour la détection, la transformation de l'énergie et l'actionnement de dispositifs grâce à leur faible dissipation énergétique, leur réponse ultra-rapide et leur grande sensibilité. Même si depuis plusieurs décennies, les progrès technologiques ont entraîné la miniaturisation des ces dispositifs, il reste nombreux challenges à surmonter dont l'un des plus importantes est l'intégration à l'échelle nanométrique d'actionneurs à base des matériaux dit " intelligents " (à ces dimensions, les matériaux habituellement utilisés perdent leurs propriétés d'actionnement). Dans ce contexte, ce travail de thèse avait pour objectif d'explorer l'utilisation des matériaux moléculaires à transition de spin pour le développement d'actionneurs électromécaniques. Dans ce but, nous avons conçu des microleviers en silicium que nous avons recouvert par différentes molécules à transition de spin soit par sublimation, soit par " spray-coating ". Les MEMS ont été caractérisés à température et pression variables en modes dynamique et statique à l'aide d'un unique dispositif expérimental. Les résultats obtenus démontrent que les molécules à transition de spin peuvent être intégrées, à l'aide de différents procédés de fabrication, dans des dispositifs MEMS et qu'il est possible de réaliser l'actionnement à l'aide d'une source d'énergie thermique (chauffage et refroidissement) et/ou lumineuse. Simultanément, cette étude a également permis d'évaluer les propriétés mécaniques des matériaux à transition de spin (module de Young, coefficient de Poisson) qui restent mal connues. / Microelectromechanical systems (MEMS) are micrometric devices able to transform a mechanical signal into an electrical one and vice-versa. In the past years they have been successfully employed in different fields of our everyday life for sensing, transducing different forms of energy and for actuating purposes thanks to their low energy dissipation, fast response and high sensibility. Even if recent technological progress has allowed a considerable miniaturization of these devices, several challenges remain. In particular the integration of smart actuating materials at the nanometric scale remains arduous because in most cases they lose their actuating properties at reduced sizes. In this context, this thesis work aimed for exploring the possibility of using molecular spin crossover materials for the development of electromechanical actuators. To this aim we have conceived silicon microcantilevers, which have been coated by various spin crossover molecules using either thermal evaporation or spray-coating methods. The MEMS have been characterized at variable temperature and pressure both in dynamical and static modes using a single experimental setup. The results prove that spin crossover molecules can be successfully integrated into silicon MEMS devices using different fabrication processes and their actuation can be achieved using either a thermal energy source or light irradiation. In parallel, this work has allowed us to extract relevant mechanical properties of spin crossover materials (Young's modulus, Poisson's ratio), which have been largely unknown previously.

This dissertation combines three separate studies that measure coastal change using airborne laser data. The initial study develops a method for measuring subaerial and subaqueous volume change incrementally alongshore, and compares those measurements to shoreline change in order to quantify their relationship in Palm Beach County, Florida. A poor correlation (R2 = 0.39) was found between shoreline and volume change before the hurricane season in the northern section of Palm Beach County because of beach nourishment and inlet dynamics. However, a relatively high R2 value of 0.78 in the southern section of Palm Beach County was found due to little disturbance from tidal inlets and coastal engineering projects. The shoreline and volume change caused by the 2004 hurricane season was poorly correlated with R2 values of 0.02 and 0.42 for the north and south sections, respectively. The second study uses airborne laser data to investigate if there is a significant relationship between shoreline migration before and after Hurricane Ivan near Panama City, Florida. In addition, the relationship between shoreline change and subaerial volume was quantified and a new method for quantifying subaqueous sediment change was developed. No significant spatial relationship was found between shoreline migration before and after the hurricane. Utilization of a single coefficient to represent all relationships between shoreline and subaerial volume change was found to be problematic due to the spatial variability in the linear relationship. Differences in bathymetric data show only a small portion of sediment was transported beyond the active zone and most sediment remained within the active zone despite the occurrence of a hurricane. The third study uses airborne laser bathymetry to measure the offshore limit of change, and compares that location with calculated depth of closures and subaqueous geomorphology. There appears to be strong geologic control of the depth of closure in Broward and Miami-Dade Counties. North of Hillsboro Inlet, hydrodynamics control the geomorphology which in turn indicates the location of the depth of closure.

Detta arbete har utförts på uppdrag givet av Sundsvall Energi AB med syftet att skapa en koppling mellan Sundsvall Energi AB:s ackumulator i Granloholm och stadsnätet med temperatur- och därmed volymbas, samt använda denna koppling för att få en bättre förståelse för deras läckage. Under Projektets gång genomfördes en litteraturstudie och en undersökning av företagets nuvarande system, för att få en förståelse över systemet och uppdraget. Avsaknaden av liknande arbeten tvingade mig att titta på läckage detektionsmetoder som var relevanta även fast de inte hanterade samma område helt och hållet. Handledarna och personal på plats hjälpte däremot till med att få fram den information som efterfrågades samt gav råd och tips om aspekter angående uppdraget som inte hade tagits i betänkande tidigare. Modellen utvecklades fram bit för bit under arbetes period, då inget annat arbete hittades som kunde ge någon riktig ram för arbetet. Modellen har visat sig vara noggrannare än dess företrädare men också svårare att implementera då den behöver behandla mycket mer indata.   Examensarbetet har visat hur annorlunda energisystem kan vara från varandra och hur olika, de olika metoderna som finns att titta och åtgärda problem i systemet är. Användning av existerande mätare och instrument är inte alltid pålitligt eller tillgängligt och antaganden och föreklingar måste ibland göras för att få en översiktsbild och en fungerande grund att utgå ifrån. / This work has been carried out on behalf of Sundsvall Energi AB, with the purpose of establishing a link between Sundsvall Energi AB:s accumulator in Granloholm and the urban network with a temperature base, and using this connection to get a better understanding of their leakage. During the project, a literature study and a survey of the company's current system, was conducted to gain an understanding of the system and the mission. The lack of similar work forced me to look at leak detection methods that were relevant even though they did not handle the same area altogether. On the other hand, counselors and staff members assisted in obtaining the information requested and gave advice and tips on aspects of the assignment that had not been included in the report before. The model was developed piece by piece during the work period, when no other work was found that could provide a proper framework for the work. The model has proven to be more accurate than its predecessor but also more difficult to implement. The thesis has shown how different energy systems can be from each other and how different, the different methods that are available to look and solve problems in the system are. The use of existing meters and instruments is not always reliable or available, and assumptions and occurrences must sometimes be made to get an overview picture and a valid basis.

Mountain glaciers are expected to be the greatest contributor to sea level rise over the next century. Glaciers provide a good indicator of global climate and how to monitor their change is an increasingly important issue for climate science and for sea level rise forecasts. However, there has been little direct measurement of glacier volume change in New Zealand. This study explores the use of remotely sensed data for measuring glacier volume change from 1965 to 2006. Digital photogrammetric methods were used to extract topographic data of the Tasman Glacier from aerial photography and ASTER imagery for the years 1965, 1986, 2002 and 2006. SRTM C band data from 2000 were also analysed. Data were compared to an existing digital elvation model produced from the New Zealand Digital Topographic Database to test for their reliability. Using regression analysis, the data were filtered and points representing rock were used to correct points on the glacier ice for vertical bias. The quality of the data extracted from the aerial photography was good on rock and debris covered ice, but poor on snow. The data extracted from ASTER was much more reliable on snow in the upper glacier than the aerial photography, but was very poor in the lower debris covered region of the glacier. While the quality of the SRTM data is very high, there is a second order distortion present in the data that is evident over elevation differences. However, the overall mean difference of the SRTM rock from TOPODATA is close to zero. An overall trend could be seen in the data between dates. However, the 2006 ASTER data proved unreliable on the debris covered section of the glacier. Total volume change is therefore calculated for the period between 1965 and 2002. The data show a loss of 3:4km³ or 0:092km³ per year, an estimated 6% of the total ice in New Zealand. This is compared to estimates using the annual end of summer snowline survey between 1977 and 2005 of 1:78 km³, or 0:064km³ per year. The spatial resolution of ASTER makes high temporal resolution monitoring of volume change unlikely for the New Zealand glaciers. The infrequency of aerial photography, the high cost and vast time involved in extracting good quality elevation data from aerial photography makes it impractical for monitoring glacier volume change remotely. However, SRTM and other radar sensors may provide a better solution, as the data do not rely heavily on user processing.

This report compares surface elevation change and volume change esti- mates from three methods: repeat track (RT), crossover (CX), and overlapping footprints (OFP). These three methods use different approaches to group- ing elevation point measurements taken at different measurement epochs and estimating elevation change. Volume changes are calculated from elevation changes in the same manner for all three methods but differences in sampling resolution between the methods affect volume change estimates in different ways. The recently reprocessed Release 633 version of elevation measurements from the Geoscience Laser Altimeter System (GLAS), flown on the Ice, Cloud and land Elevation Satellite (ICESat), are used in this analysis. Both elevation changes and volume changes are compared for both the Greenland Ice Sheet (GrIS) and the Antarctic Ice Sheet (AIS). Additionally, uncertainties in the estimates for each method are quantified and compared. Results are separated by drainage systems and by above/below 2000 m surface elevation for the GrIS. For the AIS, results are aggregated to the East, West, and Penin- vi sula regions. Volume change estimates agree well for the three methods for the GrIS, with estimates of -227.75 ± 2.12 km³/yr, -249.30 ± 3.42 km³/yr, and -218.24 ± 7.39 km³/yr for the RT, CX, and OFP methods, respectively. These estimates are similar to those published from previous studies. For the AIS, however, larger discrepancies are found in the estimates. This stems primarily from a large discrepancy in the volume change estimate of the East AIS, where the RT, CX, and OFP methods estimate volume changes of 33.39 ± 1.42 km³/yr, 46.42 ± 5.46 km³/yr, and -2.72 ± 2.12 km³/yr, respectively. It's not entirely clear why this large discrepancy exists in this particular region, and elevation change estimates for a few particular drainage systems in this region are examined. Previously published volume changes for the AIS also show a large scatter and more work must be done to reconcile the various estimates. Finally, the volume change uncertainties reported do not completely account for the discrepancies in most regions. Additional analysis must be done to completely quantify all error sources. / text

Mountain glaciers are expected to be the greatest contributor to sea level rise over the next century. Glaciers provide a good indicator of global climate and how to monitor their change is an increasingly important issue for climate science and for sea level rise forecasts. However, there has been little direct measurement of glacier volume change in New Zealand. This study explores the use of remotely sensed data for measuring glacier volume change from 1965 to 2006. Digital photogrammetric methods were used to extract topographic data of the Tasman Glacier from aerial photography and ASTER imagery for the years 1965, 1986, 2002 and 2006. SRTM C band data from 2000 were also analysed. Data were compared to an existing digital elvation model produced from the New Zealand Digital Topographic Database to test for their reliability. Using regression analysis, the data were filtered and points representing rock were used to correct points on the glacier ice for vertical bias. The quality of the data extracted from the aerial photography was good on rock and debris covered ice, but poor on snow. The data extracted from ASTER was much more reliable on snow in the upper glacier than the aerial photography, but was very poor in the lower debris covered region of the glacier. While the quality of the SRTM data is very high, there is a second order distortion present in the data that is evident over elevation differences. However, the overall mean difference of the SRTM rock from TOPODATA is close to zero. An overall trend could be seen in the data between dates. However, the 2006 ASTER data proved unreliable on the debris covered section of the glacier. Total volume change is therefore calculated for the period between 1965 and 2002. The data show a loss of 3:4km³ or 0:092km³ per year, an estimated 6% of the total ice in New Zealand. This is compared to estimates using the annual end of summer snowline survey between 1977 and 2005 of 1:78 km³, or 0:064km³ per year. The spatial resolution of ASTER makes high temporal resolution monitoring of volume change unlikely for the New Zealand glaciers. The infrequency of aerial photography, the high cost and vast time involved in extracting good quality elevation data from aerial photography makes it impractical for monitoring glacier volume change remotely. However, SRTM and other radar sensors may provide a better solution, as the data do not rely heavily on user processing.

abstract: Unsaturated soil mechanics is becoming a part of geotechnical engineering practice, particularly in applications to moisture sensitive soils such as expansive and collapsible soils and in geoenvironmental applications. The soil water characteristic curve, which describes the amount of water in a soil versus soil suction, is perhaps the most important soil property function for application of unsaturated soil mechanics. The soil water characteristic curve has been used extensively for estimating unsaturated soil properties, and a number of fitting equations for development of soil water characteristic curves from laboratory data have been proposed by researchers. Although not always mentioned, the underlying assumption of soil water characteristic curve fitting equations is that the soil is sufficiently stiff so that there is no change in total volume of the soil while measuring the soil water characteristic curve in the laboratory, and researchers rarely take volume change of soils into account when generating or using the soil water characteristic curve. Further, there has been little attention to the applied net normal stress during laboratory soil water characteristic curve measurement, and often zero to only token net normal stress is applied. The applied net normal stress also affects the volume change of the specimen during soil suction change. When a soil changes volume in response to suction change, failure to consider the volume change of the soil leads to errors in the estimated air-entry value and the slope of the soil water characteristic curve between the air-entry value and the residual moisture state. Inaccuracies in the soil water characteristic curve may lead to inaccuracies in estimated soil property functions such as unsaturated hydraulic conductivity. A number of researchers have recently recognized the importance of considering soil volume change in soil water characteristic curves. The study of correct methods of soil water characteristic curve measurement and determination considering soil volume change, and impacts on the unsaturated hydraulic conductivity function was of the primary focus of this study. Emphasis was placed upon study of the effect of volume change consideration on soil water characteristic curves, for expansive clays and other high volume change soils. The research involved extensive literature review and laboratory soil water characteristic curve testing on expansive soils. The effect of the initial state of the specimen (i.e. slurry versus compacted) on soil water characteristic curves, with regard to volume change effects, and effect of net normal stress on volume change for determination of these curves, was studied for expansive clays. Hysteresis effects were included in laboratory measurements of soil water characteristic curves as both wetting and drying paths were used. Impacts of soil water characteristic curve volume change considerations on fluid flow computations and associated suction-change induced soil deformations were studied through numerical simulations. The study includes both coupled and uncoupled flow and stress-deformation analyses, demonstrating that the impact of volume change consideration on the soil water characteristic curve and the estimated unsaturated hydraulic conductivity function can be quite substantial for high volume change soils. / Dissertation/Thesis / Ph.D. Civil and Environmental Engineering 2013

This thesis deals with the comparison of volumetric and stress variations in different formulations of cast floor self-leveling screeds during maturation. These changes were measured by several methods. Furthermore, the strength parameters of the test materials were compared. The test specimens were cured in metallic and elastic forms. The microstructure of these samples were monitored by scanning electron microscopy. In conclusion, the suitability of the tested methods for the given type of flooring materials was evaluated.

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