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Coming dissertations at TekNat

  • Residual Trapping in Geological Storage of CO2 : Determination from Field Experiments and Data Analysis Using Numerical Modeling

    Author: Saba Joodaki
    Publication date: 2021-02-12 08:49

    Geological storage of CO2 in deep saline aquifers is one of the methods to mitigate the release of this greenhouse gas into the atmosphere. The efficiency of this solution can be improved by better understanding of the relevant trapping processes, as well as by improving available injection techniques and developing tools for more accurate site characterization. 

     This Thesis has implemented numerical simulations to investigate the processes that affect the capillary trapping of the injected CO2 in a saline aquifer with the focus on two field experiments carried out in Heletz, Israel. The two experiments, applying different test sequences and characterization techniques, were carried out with the focus on determining the parameter of the maximum residual gas saturation. The collected data and a detailed description of the injection site and operational procedures are presented in Paper I. In Paper II, numerical modeling is used to interpret the pressure and temperature data recorded during the first residual trapping experiment (RTE I). The second residual trapping experiment (RTE II) and the corresponding numerical modelling for interpretation of hydraulic and...

  • Sensor Fault Detection and Process Monitoring in Water Resource Recovery Facilities

    Author: Oscar Samuelsson
    Publication date: 2021-02-10 12:19

    Water resource recovery facilities (WRRFs) operate 24/7 to reduce the environmental impact from wastewater on receiving waters. Inaccurate measurements hinder the improvement of operations, limits the performance of automatic control, and deteriorate data quality for decision support and other purposes. This thesis studied how faults can be detected in sensors and impact the treatment process, including aeration diffusers. Simulation studies as well as three 6-18 months long pilot and full-scale experiments were conducted. Evidence was given for the commonplace problem with biofilm formation, and the consequence of biased measurements in two types of dissolved oxygen (DO) sensors. The condition of the energy critical aeration diffusers was monitored by combining process models and a tailored process disturbance, which subsequently improved the information content in existing measurements. The deliberate disturbance approach was also successful in predicting fouling and other faults in DO sensors, and further enabled separation of sensor faults from process variations. The practicability of several machine learning methods was studied for both sensor and process monitoring...

  • 100 million years of shark macroevolution : A morphometric dive into tooth shape diversity

    Author: Mohamad Bazzi
    Publication date: 2021-02-08 11:20

    Few vertebrate clades exhibit the evolutionary longevity and versatility of sharks, which constitute nearly half of all current chondrichthyan biodiversity and represent an ecological diversity of mid-to-apex trophic-level predators in both marine and freshwater environments. The rich fossil record of shark teeth from Mesozoic and Cenozoic rocks also makes the group amenable to large-scale quantitative analyses. This thesis reconstructs the morphological tooth disparity of dominant lamniform (Mackerel sharks) and carcharhiniform (Ground sharks) clades over the last 100 million years. The relative diversity of these major lineages is strongly skewed, with lamniforms, including the famous White shark, making up less than 3% of the total species richness, whereas carcharhiniforms, such as Tiger sharks, comprise over 290 described species. Paradoxically, this long-recognized disproportionate representation was reversed in the distant geological past. Indeed, the fossil record shows that lamniforms accounted for nearly all of the documented shark diversity during the final stages of the Late Cretaceous — the terminal time interval of the ‘Age of Dinosaurs’, which ended 66 million...

  • The role of Nkx3.2 and Gdf5 during zebrafish skeletal development

    Author: Laura Waldmann
    Publication date: 2021-02-05 09:25

    The vertebrate skeleton is composed of bony and cartilaginous structures that are developed under the control of numerous genetic networks. The transcription factor Nkx3.2 and the signaling molecule Gdf5 play a fundamental role during joint development and chondrogenesis, a process whereby mesenchyme cells form precartilaginous condensations followed by chondrocyte differentiation. Mutations in these genes can lead to some rare human skeletal diseases and are furthermore thought to play a role during osteoarthritis, whereby the articular cartilage in synovial joints degrades. Both genes are fairly well studied in amniotes, but their full function and regulation are not completely understood. This thesis focuses on further characterization of Nkx3.2 and Gdf5 function, by using the zebrafish Danio rerio, a small vertebrate, as a model organism.

    We generated a CRISPR/Cas9 nkx3.2 mutant zebrafish line and detected broad phenotypes in the axial skeleton. Nkx3.2 deficiency in knockout zebrafish confirms previously reported jaw joint loss, but also revealed new phenotypes in the occipital region, the Weberian apparatus, the vertebrae and some fins.

    By...

  • Search for charged Higgs bosons with tau-lepton signatures at the ATLAS experiment of the Large Hadron Collider and development of novel semiconductor particle detectors

    Author: Eleni Myrto Asimakopoulou
    Publication date: 2021-02-04 13:09

    Experimental High Energy Physics (HEP) studies are discussed in the context of exotic particle searches and data analysis techniques and the development and production of suitable detectors. The main covered topics span the aforementioned areas and are primarily related to the ATLAS experiment at the Large Hadron Collider (LHC).

    The Higgs boson discovery by the ATLAS and CMS experiments in 2012, solidified the Standard Model (SM), but at the same type provided a suitable probe for searches of new physics, beyond the SM (BSM). This thesis covers a study for a new particle, the charged Higgs boson, which is predicted by several BSM theories and its discovery would be a clear sign for new physics. The study was focused on the predicted τν final state using a 36.1fb−1 dataset of pp collisions collected at √s = 13TeV with the ATLAS detector. No discovery was made, but new limits on relevant parameters were set.

    Studies that involve hadronically decaying τ leptons, such as the aforementioned charged Higgs boson search, are affected by background processes where quark- and gluon-initiated jets as misidentified as τs. A universal method for determining the impact of this...

  • Towards Higher Code Quality in Scientific Computing

    Author: Malin Källén
    Publication date: 2021-02-03 12:29

    In scientific computing and data science, computer programs employing mathematical and statistical models are used for obtaining knowledge in different application domains. The results of these programs form the basis of among other things scientific papers and important desicions that may e.g. affect people's health. Consequently, correctness of the programs is of great importance. To reduce the risk of defects in the source code, and to not waste human resources, it is important that the code is maintainable, i.e. not unnecessarily hard to analyze, test, modify or reuse. For these reasons, this thesis strives towards increased maintainability and correctness in code bases for scientific computing and data science.

    Object-oriented programming is a programming paradigm that facilitates writing maintainable code, by providing mechanisms for reuse and for division of code into smaller components with restricted access to each others data. Further, it makes extending a code base without changing the existing code possible, increasing flexibility and decreasing the risk of breaking existing functionality. However, in many cases, object-orientation trades its benefits for...

  • Fragment-based drug discovery : Novel methods and strategies for identifying and evolving fragment leads

    Author: Edward A. FitzGerald
    Publication date: 2021-02-03 10:48

    The need for new drugs became ever more apparent in the year 2020 when the world was faced with a viral pandemic. How drugs are discovered and their relevance to society became part of daily discussions in workplaces and homes throughout the world. Consequently, efficient strategies for preclinical drug discovery are clearly needed. 

    The aim of this thesis has been to contribute to the drug discovery process by developing novel methods for fragment-based drug discovery (FBDD), a rapidly developing approach where success relies on access to sensitive and informative analytical methods as well as chemical compounds with suitable properties. This process is fundamentally dependent on the interplay between scientists and engineers across biology, chemistry and physics. 

    This project is characterized by the development and implementation of novel biophysical methods over a series of studies, which are subdivided into: 1. Development of biosensor assays and approaches for challenging targets, 2. Discovery of fragments targeting dynamic proteins using biosensors, and 3. Reconstruction of ligands using fragment-based strategies.

    A selection of diverse targets was used...

  • Charge Separation on Localized Surface Plasmon and Hot Carrier Transfer to Semiconductors

    Author: Yocefu Hattori
    Publication date: 2021-02-02 14:11

    The relatively recent discovery that plasmonic nanoparticles generate energetic electron-hole pairs known as hot carriers has been the source of interest from many scientific groups. The capability to extract these short-lived hot carriers from metal nanoparticles (NPs) might potentially lead to applications in solar cells, photodetection, and photocatalysis. However, a better understanding of the hot carrier dynamics, starting from the formation process, is required. This thesis seeks to elucidate some aspects of charge formation, extraction, and hot carriers' recombination in plasmonic composite systems.

    First, two systems based on Ag and Au NPs were designed and studied to elucidate charge carriers' dynamics. The studies revealed that electrons and holes were effectively extracted and injected into suitable acceptors. Additionally, the electron injection and back transfer on TiO2 was significantly affected by the interface's status. The result motivated the following study that consisted of Au plasmonic NPs supported on different metal oxides, namely TiO2, ZnO, SnO2, and Al-ZnO (AZO). The electron dynamics on these systems were widely different. They could not be...

  • Biostratigraphy and Systematics of Cambrian Small Shelly Fossils from East Antarctica and South Australia

    Author: Thomas M. Claybourn
    Publication date: 2021-01-29 07:54

    The remote lower Cambrian Byrd group of sedimentary rocks from East Antarctica has been studied intermittently since its discovery over a century ago. Previous insights into the trilobites and archaeocyaths indicated a close correlation to the sedimentary sequences of South Australia. The lowest unit of the Byrd Group is the fossiliferous Shackleton Limestone which overlies the Neoproterozoic metamorphic rocks of the Beardmore Group and is representative of a long period of carbonate shelf formation on a passive margin with the palaeo-Pacific. This was truncated by marine transgression and the deposition of the deeper-water calcareous siltstones of the fossiliferous Holyoake Formation. This is overlain by the Starshot Formation and all three units are cross-cut by the Douglas Conglomerate, marking the start of a collisional tectonic regime between the East Gondwana and palaeo-Pacific plates. The first systematically sampled and analysed sections through the carbonate Shackleton Limestone and argillaceous Holyoake Formation has yielded a new fauna of small primarily phosphatic and secondarily phosphatised shelly fossils. The abundant molluscs, brachiopods and tommotiids are...

  • The Importance of Gender Equality in Climate Action : An investigation into how UN member states view the relation between gender equality and climate action

    Author: Diandra van Duijn
    Publication date: 2021-01-28 07:53

    Scientists warn that the current rate of climate change will raise average global temperature by 4°C compared to 1990, although warming of +2°C will already have dire effects throughout the world. Therefore, the UN acknowledges SDG 13 (Climate Action) as one of the most important goals for the coming decade in order to fight climate change. Another focus of the UN is SDG 5 (Gender Equality), which is also an overarching goal but still lagging behind. Working on one of the goals can have a positive effect on other goals. Therefore a synergy can be created when investigating how climate change affects gender equality and how gender equality affects climate action. 

    The link between gender equality and climate action was already established by the UN at the Beijing Platform of Action in 1995. However, there has been little research into how government representatives understand how the goals are interconnected. These representatives are important in the drafting of new policy and keeping the UN accountable for incorporating gender into its policies. Hence, this thesis investigates how the relationship between gender equality and climate action is viewed by government...

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