Magister Scientiae (Biodiversity and Conservation Biology) - MSc (Biodiv and Cons Biol) / Areas of high biodiversity and complex species assemblages are often difficult to manage and to set up meaningful monitoring and evaluations programmes. Mountain Fynbos is such an ecosystem and in the Cape of Good Hope (part of the Table Mountain National Park) plant biodiversity over the last five decades has been in decline. The reasons are difficult to speculate since large herbivores, altered fire regimes and even climate change could be contributors to this decline which has been quantified using fixed quadrats and standard cover-abundance estimates based on a Braun-Blanquet methodology. To provide more detailed data that has more resolution in terms of identifying ecological processes, Fixed-Point Repeat Photography has been presented as a management “solution”. However, photography remains a difficult method to standardize subjects and has certain operational limitations.

Olivine is the most abundant mineral in Earth's upper mantle and is one of the major minerals discovered in extraterrestrial objects. Its physical properties govern the dynamics of the upper mantle. The most dynamic regions of the upper mantle are sites where melting and melt segregation occurs. These regions are also the most variable in terms of their oxygen fugacity. We therefore conducted piston cylinder experiments to determine the intergranular melt distribution, and explore a range of oxygen buffers. We annealed olivine aggregates in metallic and graphite capsules to determine the oxygen fugacities set by the capsule materials. These experiments show that oxygen fugacities are below their corresponding metal-oxide buffers. The oxygen fugacity in nickel80-iron20 and graphite capsules most closely represents the intrinsic oxygen fugacity of Fo90 olivine, while iron capsules are too reducing perhaps explaining the formation of "dusty" olivine in chondrites. We annealed olivine-basalt aggregates in order to determine the melt distribution. The results show that the length of olivine grain boundaries wetted by melt (grain boundary wetness) increases with increasing melt content to values well above those predicted by a simplified model which is commonly applied to this system. At fixed melt content the grain boundary wetness increases with increasing grain size. These observations emphasize that the dihedral angle of the simplified system is not adequate to characterize the melt distribution in partially molten rocks. Our observations indicate that at upper mantle grain sizes the shear viscosity of partially molten rocks is one order of magnitude lower than predicted by the simplified model. Naturally partially molten rocks exist in the form of olivine-rich troctolites or plagioclase dunites, but the conditions for their formation are not entirely clear. We therefore conducted step-cooling experiments that indicate that slow cooling of samples with a steady-state microstructure reproduces the interstitial geometry observed in natural samples. The grain boundary wetness determined from the interstitial phases is somewhat reduced during slow cooling relative to samples quenched from high temperature. The microstructural similarity of experimental and natural samples suggests that mush zones identified beneath mid-ocean ridges may have lower melt contents than previously envisioned. / 2016-11-18T00:00:00Z

Today more and more people are moving to the cities around the world. This puts a lot of strain on the infrastructure as the cities grow in both width and height. To be able to monitor the ongoing change remote sensing is an effective tool and ways to make it even more effective, better and easier to use are constantly sought after. One way to monitor change detection is object based change detection. The idea has been around since the seventies, but it wasn’t until the early 2000 when it was introduced by Blaschke and Strobl(2001) to the market as a solution to the issues with pixel based analysis that it became popular with remote analysts around the world. KTH-SEG is developed at KTH Geoinformatics. It is developed to segment images in order to preform object based analysis; it can also be used for classification. In this thesis object based change detection over an area of Shanghai is carried out. Two different approaches are used; post-classification analysis as well as creating change detection images. The maps are assessed using the maximum likelihood report in the software Geomatica. The segmentation and classification is done using KTH-SEG, training areas and ground truth data polygons are drawn in ArcGIS and pre-processing and other operations is carried out using Geomatica. KTH-SEG offers a number of changeable settings that allows the segmentation to suit the image at hand.  It is easy to use and produces well defined classification maps that are usable for change detection The results are evaluated in order to estimate the efficiency of object based change detection in urban area and KTH-SEG is appraised as a segmentation and classification tool. The results show that the post-classification approach is superior to the change detection images. Whether the poor result of the change detection images is affected by other parameters than the object based approach can’t be determined. / Idag flyttar fler och fler människor in i städer runt om i världen. Det utgör en stor påverkan på den befintliga infra-strukturen då städerna växer på både höjden och bredden. För att kunna bevaka den förändring som sker så används ofta fjärranalys som ett effektivt verktyg. Sätt att utveckla befintliga tekniken försöker man hela tiden hitta nya, enklare och mer effektiva sätt att bevaka förändring finns alltid på horisonten. Objektbaserad förändrings analys är ett sätt att bevaka förändringar. Iden om att använda objekt baserad analys har funnits sedan 70-talet, men det var först i början av 2000-talet, då Blaschke och Strobl(2001) introducerade tekniken som en lösning på de problem man stöter på i pixelbaserad analys, som tekniken blev populär bland fjärranalytiker världen över. KTH-SEG är ett program utvecklat på KTH Geoinformatik avdelning. KTH-SEG är utvecklat för att segmentera bilder inför objektbaserad analys. Dessutom utför programmet klassificering. I det här arbetet utförs objektbaserad förändrings analys över ett område i Shanghai. För att hitta de förändringar som har skett har två tillvägsgångssätt använts: dels har analys av bilder efter klassificeringen gjorts och dels har bilder som i sig själva skall visa den förändring som har skett skapats, så kallade förändringsbilder. Bildernas pålitlighet är utvärderad genom att använda ”maximum likelihood report” i programmet Geomatica.   Segmentering och klassificering är gjort i programmet KTH-SEG, träningsområden och testområden är skapade i ArcGIS och förbehandling av bilder samt andra operationer är gjorda i Geomatica. KTH-SEG erbjuder många valmöjligheter för att påverka segmenteringsresultatet. Den är enkelt att använda och producerar tydliga klassificerade bilder som är användbara för analys. Resultatet utvärderas för att bestämma hur effektivt det är att använda objektbaserad förändrings analys av urbana områden och KTH-SEG utvärderas som ett segmenterings- och klassifikations verktyg. Resultaten visar att förändringsbilder ger ett sämre resultat än bilder som analyseras efter klassifikationen. Huruvida det dåliga resultatet på förändingsbilderna beror på andra omständigheter än tillvägagångssättet med objekt baserad klassifikation kan inte bestämmas. Mycket tyder dock på att det är valet av två bilder från olika satelliter som ger det dåliga resultatet.

Weather and climate models applied with sufficiently fine mesh grids to enable a large part of atmospheric deep convection to be explicitly resolved have shown a significantly improved representation of local, short-duration and intense precipitation events compared to coarser scale models. In this thesis, two studies are presented aimed at exploring the dependence of horizontal resolution and of parameterization of convection on the simulation of precipitation. The first examined the ability of HARMONIE Climate (HCLIM) regional climate model to reproduce the recent climate in Europe with two different horizontal resolutions, 15 and 6.25 km. The latter is part of the ”grey-zone” resolution interval corresponding to approximately 3-10 km. Particular focus has been given to rainfall and its spatial and temporal variability and other characteristics, for example intensity distributions. The model configuration with the higher resolution is much better at simulating days of large accumulated precipitation amounts, most evident when the comparison is made against high-resolution observations. Otherwise, the two simulations show similar skill, including the representation of the spatial structure of individual rainfall areas of primarily convective origin. The results suggest a ”scale-awareness” in HCLIM, which supports a central feature of the model’s description of deep convection as it is designed to operate independently of the horizontal resolution. In the second study, summer season precipitation over the Alps region, as simulated by HCLIM at different resolutions, is investigated. Similar model configurations as in the previous study were used, but in addition a simulation at the ”convection-permitting” 2 km resolution has been made over Central Europe. The latter considerably increases the realism compared to the former regarding the distribution and intensities of precipitation, as well as other important characteristics including the duration of rain spells, particularly on sub-daily time scales and for extreme events. The simulations with cumulus parameterization active underestimate short-duration heavy rainfall, and rainspells with low peak intensities are too persistent. Furthermore, even though the 6.25 km simulation generally reduces the biases seen in the 15 km run, definitive conclusions of the benefit of ”grey-zone” resolution is difficult to establish in context of the increased requirement of computer resources for the higher-resolution simulation.

This thesis focuses on the theory, fabrication, and characterization of 2-port surface acoustic wave (SAW) resonators, as well as the application of their Fabry-Pérot resonance modes for strain sensing. The thesis includes three articles. In the first article, a fabrication method for high frequency SAW devices using traditional UV photolithography equipment is developed. It is well known that SAW sensors become more sensitive at higher frequencies but realizing high frequency devices requires small features which challenge existing photolithography methods. The proposed process is a modified version of a previously reported tri-layer lift-off photolithography process intended for Si or SiO2 substrates which allows for compatibility with materials that are piezoelectric and pyroelectric, often used as the substrate in SAW devices. The process uses a lithographic tri-layer consisting of layers of lift-off resist (LOR) on the bottom, back anti-reflection coating (BARC) in the middle, and photoresist (PR) on top, improving resolution by a factor of two over traditional lift-off photolithography techniques. We demonstrate the fabrication of a SAW device with an interdigital transducer (IDT) pitch of 4 μm (minimum feature size of 1 μm) on 128o Y-X cut lithium niobate, whose operating frequency is measured as 994.5 MHz. The 2-Port SAW devices that are used in subsequent chapters are fabricated using this process. The second article proposes a method of analyzing acoustic Fabry-Pérot spectra, by analogy with optical cavities, to determine key SAW parameters. In our experiment, 2-port SAW resonators, consisting of two interdigital transducers (IDTs) laterally separated by a free surface cavity length, are used to generate SAWs on 128o Y-X lithium niobate that are trapped between the two IDTs which also act as Bragg reflectors. Fabry-Pérot cavity peaks can be observed through the electrical S11 (reflection) spectrum measured on one IDT, hence a 2-Port resonator is equivalent to an acoustic Fabry-Pérot cavity/resonator. Measurements of the free spectral range and linewidths are then fitted to linear models to obtain the free surface velocity and attenuation of SAW waves, as well as the reflection of interdigital transducers (IDTs), all of which are crucial design parameters. Our method of analyzing Fabry-Pérot spectra provides a convenient method for determining key characteristics of SAW waves and cavities. In the third article, a surface acoustic wave (SAW) strain sensor based on measuring acoustic Fabry-Pérot resonance peaks from a 2-port SAW resonator is demonstrated. A theoretical analysis is proposed to estimate the frequency sensitivity to strain of IDT and cavity resonances and to predict strain distributions in both the cavity and IDT regions of a 2-port SAW resonator bonded to a tapered cantilever beam. The frequency stability of cavity resonance peaks for fabricated 2-port SAW resonators of different cavity length are measured and analyzed to determine the cavity length which exhibits maximum frequency stability. A cross-correlation analysis technique is then introduced to improve the detection of the frequency shift of SAW resonances and enable multimode frequency shift detection. The measured frequency sensitivity to strain of the cavity resonances of a resonator 10 mm in length (operating frequency = 97.7 MHz) was found to be -103.2 ± 0.2 Hz/με while demonstrating excellent linearity (R2 = 0.9999). By considering a minimum signal to noise ratio (SNR) of 3 dB, the device exhibits a minimum strain resolution of only 234 nε.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23479号 / 工博第4891号 / 新制||工||1764(附属図書館) / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 立川 康人, 准教授 市川 温, 教授 角 哲也 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

>Magister Scientiae - MSc / Southern offshore basins of South Africa are well known as potential provinces of hydrocarbon exploration and production. The complex nature of the Bredasdorp sub-basin’s syn-rift architecture (transform fault system) can have adverse effects on reservoir distribution due to periodic local and regional uplift of horsts and grabens. This present investigation focusses on an integrated approach of the 1AT1-V horizon or early Cretaceous sediments in the Bredasdorp sub-basin to identify the depositional environment and provenance of these sediments as well as their role in regionally complex compositional heterogeneities associated with the late stage rifting of Gondwana break-up. An integrated seismic, sedimentological (including petrography and geochemistry) and ichnologic analysis of the 1AT1-V horizon sediments showed an overall lower regressive element complex assemblage set and an upper transgressive element complex assemblage set that occurred as a >120m thick succession. The analysis identified a mixed-energy deltaic succession followed by an estuarine succession. The 1AT1-V interval (late syn-rift) consisted of nine sedimentary facies associations (and associated petrofacies) on a dipslope setting with variations occurring along the strike and the downdip depositional slope areas. Two overall sequences were identified as a lower regressive and upper transgressive sequence (Element complex assemblage sets). The regressive sequence consisted of middle to distal delta front lobe fringes, hyperpycnal event beds (sourced from basement highs), offshore migrating tidal bars (and associated inter-bar regions), distal mouth bars, terminal distributary channels (and associated inter-terminal distributary regions). The distal delta plain to proximal delta front consisted of interdistributary bays, distributary channels, crevasse splay sub-deltas, mouth bars, tidal flats and offshore embayments. In the laterally isolated depocenter, these deposits also consisted of basement high slopes with upliftment of the basement highs leading to proximal/central embayment to regressive shoreface/foreshore environments. These sequences consisted generally of low diversity and intensities (impoverished abundances) of trace fossils. The paleoclimate inference from this sequence indicates a humid climate with intermediate degrees of weathering intensities (possibly fluctuating arid-humid conditions). The transgressive sequence consisted of estuarine sedimentation with the occurrence of tidal sand ridges and compound dune fields, embayment facies and tidal bars. These sequences consisted of relatively higher ichnodiversities and intensities than their relative regressive sequences. The paleoclimate inference during these times consisted of more arid to semi-arid settings with low degrees of weathering in the source terrain. Local tectonic upliftment and subsidence, with exposed basement highs, gave rise to differential process regimes (tidal, wave and fluvial) and hence depositional facies in the diachronous updip/downdip areas (spatial) and within-stratigraphic (temporal) variations. There are several modern analogues that are similar to the 1AT1-V horizon sequence and they are the Mahakam, Ganges-Brahmaputra, Po, Burdekin deltaic and Satpara lake environments Compaction and dissolution diagenetic features as well as transportation were responsible for the major compositional heterogeneities concerning the reservoir quality and distribution. Proximal and distal sources were identified with first cycle and polycyclic sediments being deposited in the northern and southern part of the basin during the late stages of rifting in the Bredasdorp sub-basin. The provenance lithology has been identified as recycled sedimentary rocks (and their meta-equivalents) with an ultimate source terrain that was largely felsic in nature (Cape granite suite). The northern part of the studied section is suggested to have received sediments from the main metasedimentary rocks of the Cape fold belt (including the Table Mountain Group and Bokkeveld Group) whereas the southern sections received more sediments from the basement highs (recycled Malmesbury Group (and Pre-Cape sediments) and Cape granite suite), which is further supported by seismic data. Provenance analysis revealed that the Cape Fold belt (most recent collision) was possibly a provenance terrain but overprinting of several collisions are also acknowledged. The tectonic setting was envisaged to be of a rifted margin during the break-up of Gondwana. This compositional heterogeneity due to facies and provenance-related terrains had major consequences to the reservoir quality and distribution from the northern part to the southern part of the studied section

Les filtres CRIGFs sont une nouvelle génération de filtres optiques réflectifs nanostructurés qui présentent un très fort intérêt pour de nombreuses applications. Cependant, leur fabrication est relativement complexe : il s'agit de composants structurés à des échelles petites devant la longueur d'onde d'utilisation, mais de surface totale relativement grande. Ils sont usuellement fabriqués en utilisant des procédés de lithographie de type lithographie électronique, qui présente une résolution suffisante mais qui est séquentielle et donc lente pour de telles surfaces de composant. En outre, les CRIGFs sont souvent réalisés sur des substrats isolants, ce qui complexifie encore plus l'utilisation de cette lithographie. Lors de cette thèse, un procédé de fabrication des CRIGFs a été développé à partir de la lithographie par nanoimpression via moule souple (SNIL). Cette technologie collective et à haut rendement contourne les inconvénients et garde les avantages de la traditionnelle lithographie électronique. Elle permet de fabriquer des motifs nanométriques par simple pressage d'un moule souple sur une couche de résine de polymères sous insolation d'ultraviolets. Après avoir stabilisé le procédé et établi les limites de la technologie, de nombreux filtres CRIGFs ont ainsi été créés. Ils présentent des résultats optiques équivalents dans le proche infrarouge (NIR) à ceux fabriqués par lithographie électronique. Dans un deuxième temps, le caractère générique du procédé mis en place a été démontré de plusieurs façons. Premièrement, nous avons montré qu'il était possible à l'aide de celui-ci de dépasser les compromis usuels de conception en structurant directement le guide d'onde, qui sera ensuite ré-encapsulé. Deuxièmement, nous avons montré que ce même procédé pouvait être directement transféré pour réaliser des filtres CRIGF dans la gamme du moyen infrarouge, bien que les filtres soient alors réalisés sur un matériau cristallin III-V et présentent des dimensions micrométriques plutôt que nanométriques. Enfin, nous avons démontré la grande souplesse et stabilité du procédé en l'utilisant pour explorer différentes géométries potentiellement intéressantes de cette nouvelle famille de filtres optiques nanostructurés. Nous avons notamment étudié des CRIGFs comportant un gradient de période qui ont permis pour la première fois d'obtenir un filtre CRIGF accordable. Pour finir, nous nous sommes attachés à étudier le potentiel de réalisation de filtres CRIGFs plus complexes et présentant plusieurs niveaux de corrugation. / Cavity resonator integrated grating filters (CRIGFs) are a new generation of nanostructured reflective filters. They present a strong interest for many applications. However, their manufacturing is relatively complex: CRIGFs are components structured at small scales compared to the wavelength of interest but on a relatively large area. They are usually made by electron beam lithography technique which presents a sufficient resolution but does not allow parallel patterning and is thereby time consuming for large area components. Furthermore, CRIGFs are often fabricated on insulating wafers which make the e-beam lithography process more complicated. In this PhD, a CRIGF process manufacturing has been implemented through soft mold nanoimprint lithography (SNIL). This high throughput collective technology keeps the benefits of the traditional electron beam lithography while overcoming its limits. Nano-scale patterns can be made by a simple stamping under UV exposure of a soft mold on a polymer resist layer. After stabilizing the process and assessing the technique limits, plenty of CRIGFs have been manufactured. They exhibit optical performances in the near- infrared range equivalent to those manufactured by e-beam lithography. Secondly, it has been demonstrated that the implemented process is generic. We have shown the possibility to overcome the usual design trade-offs by structuring directly the waveguide, before embedding. Moreover, this same process has been shown to be applied in a straightforward way to fabricate CRIGFS in the mid-infrared range using a III-V crystalline material and micrometric sized patterns. Finally, we have demonstrated the great flexibility and sustainability of the process by testing different potential geometries of CRIGFs. Notably, we have designed a CRIGF with a period gradient leading to the first tunable CRIGF ever demonstrated. Lastly, we have evaluated the potential manufacturing of complex CRIGFs with several corrugation levels.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第17972号 / 理博第3916号 / 新制||理||1565(附属図書館) / 80816 / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 高橋 義朗, 教授 田中 耕一郎, 教授 石田 憲二 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19700号 / 工博第4155号 / 新制||工||1641(附属図書館) / 32736 / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 井手 亜里, 教授 松野 文俊, 教授 蓮尾 昌裕 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM