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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.
711

Offshore Hydrogen Production and Storage for Wave Energy Application : A Techno-Economic Assessment for a Japanese Context

Stafverfeldt, Andrea January 2023 (has links)
There is a well-established market for hydrogen, mainly for refining purposes, producing chemicals, and producing fertilizers. Today, almost all hydrogen is sourced from fossil fuels, with less than 1% of hydrogen sourced from renewable sources. Alternative solutions for fossil-free hydrogen are necessary to ensure that the demand for hydrogen can be met in a sustainable fashion. The objective of this study is to analyse the feasibility and cost-effectiveness of combining hydrogen production through electrolysis with electricity production from an array of wave energy converters to supply the hydrogen market with fossil-free hydrogen. A techno-economic analysis is performed for 16 cases of offshore hydrogen production and storage in eastern Japan, using three storage mediums; Compressed hydrogen, liquid hydrogen and ammonia. Technical and economical specifications of all components required for the production systems are modelled for each case to find the most beneficial system through the Levelized Cost Of Hydrogen (LCOH), which is compared to other available renewable and fossil hydrogen sources today. The production systems evaluated in this study reach an LCOH of $5.5-7.1 /kgH2 depending on the hydrogen storage medium, where compressed hydrogen is the cheapest. This can be considered competitive with other renewable hydrogen sources, but not with fossil counterparts. / Det finns en väletablerad marknad för vätgas, främst för raffinering och framställning av kemikalier samt gödningsmedel. Idag produceras nästan all vätgas av fossila bränslen, med mindre än 1% från förnybara källor. Alternativa lösningar för förnybar vätgas är nödvändiga för att möta efterfrågan på ett hållbart sätt. Syftet med denna studie är att analysera om det är ekonomiskt försvarbart att producera vätgas offshore genom elektrolys av el från vågkraftverk för att förse vätgasmarknaden med fossilfri vätgas. Detta utförs genom en tekno-ekonomisk analys av 16 fall av havsbaserad vätgasproduktion och lagring i östra Japan. Fallen behandlar tre lagringsmedium; komprimerad vätgas, flytande vätgas och ammoniak. Tekniska och ekonomiska specifikationer för alla komponenter som krävs för produktionssystemet modelleras för varje fall. Det mest fördelaktiga systemet beräknas genom Levelized Cost of Hydrogen (LCOH), som jämförs med andra tillgängliga förnybara och fossila produktionssystem för att avgöra systemets konkurrenskraft på marknaden. Produktionssystemen som utvärderas i denna studie har en LCOH från $5.5-7.1 /kgH2 beroende på lagringsmedium, där komprimerad vätgas är det billigaste. Detta resultat kan betraktas som konkurrenskraftigt med andra förnybara vätgaskällor, men inte med fossila motsvarigheter.
712

An Appraisal Of The Supernova Minicomputer As A Process Simulation Tool

Foran, Charles 01 1900 (has links)
<p> The object of this work was to evaluate the Supernova ninicomputer as a process simulation tool. To accomplish this obje c tive the GEMCS ste2dy-state simulation system wa.s programmed for the Supernova. This system was programmed to run in five different modes, BASIC , two modes which require that al.L progra1ns are written in Assembly Language, and two modes in which programs may be called from the disk. Of these latter two modes, one requires all programs to be written in Assembly Language; the other mode allows programs to be written in Assembly Language or FORTRAN IV. </p> <p> Two case studies which had previously been run on the CDC 6400 were run on the Supernova to test and evaluate f our of the modes in which GEMCS was proerammed for the Supernova. </p> <p> The studies have also provided an a ssessment of the hardware and softws.re facilities of the Supernova and the results of thjs assessment were documented. In addition the opera tion of the various strategies used to impl ement GEMCS have provided an indication of the feasibility of the impl ementation of the dynamic system simulation program, DYNSYS. </p> / Thesis / Doctor of Philosophy (PhD)
713

PREDICTION OF MULTI-PHASE LIVER CT VOLUMES USING DEEP NEURAL NETWORK

Afroza Haque (17544888) 04 December 2023 (has links)
<p dir="ltr">Progress in deep learning methodologies has transformed the landscape of medical image analysis, opening fresh pathways for precise and effective diagnostics. Currently, multi-phase liver CT scans follow a four-stage process, commencing with an initial scan carried out before the administration of <a href="" target="_blank">intravenous (IV) contrast-enhancing material</a>. Subsequently, three additional scans are performed following the contrast injection. The primary objective of this research is to automate the analysis and prediction of 50% of liver CT scans. It concentrates on discerning patterns of intensity change during the second, third, and fourth phases concerning the initial phase. The thesis comprises two key sections. The first section employs the non-contrast phase (first scan), late hepatic arterial phase (second scan), and portal venous phase (third scan) to predict the delayed phase (fourth scan). In the second section, the non-contrast phase and late hepatic arterial phase are utilized to predict both the portal venous and delayed phases. The study evaluates the performance of two deep learning models, U-Net and U²-Net. The process involves preprocessing steps like subtraction and normalization to compute contrast difference images, followed by post-processing techniques to generate the predicted 2D CT scans. Post-processing steps have similar techniques as in preprocessing but are performed in reverse order. Four fundamental evaluation metrics, including <a href="" target="_blank">Mean Absolute Error (MAE), Signal-to-Reconstruction Error Ratio (SRE), Peak Signal-to-Noise Ratio (PSNR), and Structural Similarity Index Measure (SSIM), </a>are employed for assessment. Based on these evaluation metrics, U²-Net performed better than U-Net for the prediction of both portal venous (third) and delayed (fourth) phases. Specifically, U²-Net exhibited superior MAE and PSNR results for the predicted third and fourth scans. However, U-Net did show slightly better SRE and SSIM performance in the predicted scans. On the other hand, for the exclusive prediction of the fourth scan, U-Net outperforms U²-Net in all four evaluation metrics. This implementation shows promising results which will eliminate the need for additional CT scans and reduce patients’ exposure to harmful radiation. Predicting 50% of liver CT volumes will reduce exposure to harmful radiation by half. The proposed method is not limited to liver CT scans and can be applied to various other multi-phase medical imaging techniques, including multi-phase CT angiography, multi-phase renal CT, contrast-enhanced breast MRI, and more.</p>
714

High-Resolution Cartography of the Transcriptome and Methylome Landscapes of Diffuse Gliomas

Willscher, Edith, Hopp, Lydia, Kreuz, Markus, Schmidt, Maria, Hakobyan, Siras, Arakelyan, Arsen, Hentschel, Bettina, Jones, David T. W., Pfister, Stefan M., Loeffler, Markus, Loeffler-Wirth, Henry, Binder, Hans 26 April 2023 (has links)
Molecular mechanisms of lower-grade (II–III) diffuse gliomas (LGG) are still poorly understood, mainly because of their heterogeneity. They split into astrocytoma- (IDH-A) and oligodendroglioma-like (IDH-O) tumors both carrying mutations(s) at the isocitrate dehydrogenase (IDH) gene and into IDH wild type (IDH-wt) gliomas of glioblastoma resemblance. We generated detailed maps of the transcriptomes and DNA methylomes, revealing that cell functions divided into three major archetypic hallmarks: (i) increased proliferation in IDH-wt and, to a lesser degree, IDH-O; (ii) increased inflammation in IDH-A and IDH-wt; and (iii) the loss of synaptic transmission in all subtypes. Immunogenic properties of IDH-A are diverse, partly resembling signatures observed in grade IV mesenchymal glioblastomas or in grade I pilocytic astrocytomas. We analyzed details of coregulation between gene expression and DNA methylation and of the immunogenic micro-environment presumably driving tumor development and treatment resistance. Our transcriptome and methylome maps support personalized, case-by-case views to decipher the heterogeneity of glioma states in terms of data portraits. Thereby, molecular cartography provides a graphical coordinate system that links gene-level information with glioma subtypes, their phenotypes, and clinical context.
715

Diagnostic Accuracy in Dual Diagnosis: The Development of the Screen for Symptoms of Psychopathology in Individuals with Intellectual Disability (SSP-ID)

Staal, Rozemarijn Nathalie January 2014 (has links)
No description available.
716

Effect of Oasis-Ultra Matrix on the Healing Rate of Stage IV Pressure Wounds

Abou Issa, Abdelfatah Shaban 25 May 2016 (has links)
No description available.
717

Chromium Carcinogenesis: Characterization of DNA damaging Intermediates by EPR <sup>31</sup>P NMR, HPLC, ESI-MS and Magnetic Susceptibility

Marin Cordoba, Roberto 16 April 2010 (has links)
No description available.
718

Cross-comparison of Non-Linear Seismic Assessment Methods for Unreinforced Masonry Structures in Groningen

Peterson, Viktor, Wang, Zihao January 2020 (has links)
A large amount of low-rise unreinforced masonry structures (URM) can be foundin Groningen, the Netherlands. More and more induced earthquakes with shortduration have been detected in this region due to gas exploitation. Local unreinforcedmasonry (URM) buildings were initially not designed for withstanding seismicactions, so that unexpected damage may occur due to their vulnerability, raising insecurityamong residents. Existing low-rise masonry buildings in Groningen can bedivided into different categories based on their characteristics. Two types of residentialmasonry buildings that fulfil the prerequisites for performing non-linear seismicassessment are chosen to be studied in this thesis project, including the terracedhouse and the detached house.The seismic assessment of structures requires the use of both a discretization methodand a seismic assessment method. The discretization method is used to translate themechanical model into a finite element model used for the numerical analysis. Severalmethods have previously shown to be applicable for seismic assessment, but thiswork investigates the implications of using a continuum model (CM) and an equivalentframe model (EFM) approach to discretization in the general-purpose finiteelement package described in DIANA-FEA-BV (2017). The continuum model approachadopted was in a previous work by Schreppers et al. (2017) validated againstexperimental results and is as such deemed representative of the physical behaviourof the mechanical models investigated. An equivalent frame model approach to beused with DIANA is proposed in the work by Nobel (2017). The continuum modelapproach uses continuum elements with a constitutive model developed for the seismicassessment of masonry structures. This constitutive model captures both shearand flexural failure mechanisms. The equivalent frame model approach uses a combinationof numerically integrated beam elements and nodal interfaces, each witha distinct constitutive model, thus decoupling the description of the flexural andshear behaviour. This approach aims to capture the macro-behaviour at the structurallevel. The applicability of the proposed equivalent frame model approach isevaluated by how well it replicates the validated continuum model approach results.The two discretization methods described are evaluated using two types of seismicassessment methods. The first seismic assessment method used consists of first performinga quasi-static non-linear pushover analysis (NLPO) on the model. Thisresults in the pushover curve, which describes the global behaviour of the modelunder an equivalent lateral load based on the fundamental mode shape of the structure.The pushover curve is then used with the N2-method described in EN1998-1iii(2004) to assess at which peak ground acceleration (PGA) that the model reachesthe near-collapse (NC) limit state. The second seismic assessment method consistsof performing dynamic non-linear time-history analyses (NLTH). This method usesrecorded accelerograms to impose the inertial forces. The PGA for the accelerogramwhere the near-collapse limit state is reached is compared to the PGA fromthe use of the N2-method. The applicability of the pushover analysis in conjunctionwith the N2-method is evaluated by how well it replicates the PGA found from thetime-history analyses and by how well it replicates local failure mechanisms.Therefore, the main objectives of this project can be described by the following twoquestions:i. To what extent can the equivalent frame method be applicable as a properdiscretization method for pushover analyses and time-history analyses oflow-rise unreinforced masonry residential buildings in the Groningen region?ii. To what extent can the non-linear pushover method be adopted toassess the seismic behaviour of low-rise unreinforced masonry residentialbuildings in the Groningen region?The applicability of the equivalent frame model showed to vary. For describing localfailure mechanisms its applicability is poor. Further work on connecting the edgepiers to transverse walls is needed. For seismic assessment using the N2-method theapplicability of the equivalent frame model approach is sensible. The conservativedisplacement capacity counteracts the fact that it is worse at describing local unloading,which produced a larger initial equivalent stiffness of the bi-linear curvesin comparison to the continuum model. For seismic assessment using the timehistorysignals, its applicability is possible. While it could show different behaviourin terms of displacement and damping forces, it still showed a similar PGA at thenear-collapse limit state for the cases at hand.The seismic assessment of the terraced and detached houses by the N2-method issimilar to the seismic prediction by applying time-history analyses. However, thereare still some variations in the initial stiffness, force capacity and displacement capacitybetween these two assessment methods due to the assumptions and limitationsin this study. Overall, considering the pros and cons of the quasi-static pushovermethod, it is deemed applicable during the seismic assessment of the unreinforcedmasonry structures in the Groningen area.
719

Evaluation of moisture safety in cold attic and external wall designs commonly used in the building sector

Saleh, Yad January 2020 (has links)
Kontinuerligt försvårade och mer krävande energikrav utlyst från den Europeiska unionen ochsvenska myndigheter har lett till en förändring av hur konstruktionsdetaljer och lösningar somanvänds inom nyproduktionssektorn utformas. Förändringarna har skapat en osäkerhet ur enfuktsäkerhetssynpunkt. Uttökade krav och förbättrad energiprestanda låter som ett problemfrittideal att sträva efter, dock har det i många fall lett till oförutsägbara konsekvenser i olika delar avbyggnaden. Två av de byggnadskomponenter som påverkats har varit ytterväggar och kallvindarsom har varit utformade utefter nya energikrav i nyproducerade hus.Den största utmaningen med utformningen av nyare kallvindar har varit balansgången mellanhög energiprestanda genom ökad isoleringstjocklek och fuktsäkerhet. Ökad isoleringstjocklekkombinerat med minimerad värmeförlust från ventilationsaggregat, inomhus och skorstenar harlett till, i överlag, kallare vindutrymmen med ökad risk för kondensation av fukt på kallare ytor ijämförelse med äldre byggnader. En lösning på detta har varit inkluderingen av uteluftsventileringi utformningen av vinden. Detta har lett till en återkommande fråga angående den optimalaluftomsättningen som krävs för utökad fuktsäkerhet, och i vissa fall, om uteluftsventilering ensär nödvändig.En annan stor utmaning har varit att säkerhetsställa fuktsäkerheten i väggar som är isolerade ien högre grad. Det finns en potentiell risk för kondens i kalla, yttre ytor om isoleringen utökas.Utöver detta så existerar det en hel del lösningar som har fungerat i det förflutna men som lärleda till ökad risk för skada när det kombineras med nya utformade lösningar som uppfyllerenergikraven.Detta arbete har fördjupat sig i dessa två komponenter, ytterväggar och kallvindar, för atthitta kritiska designval som har en stor påverkan på fuktsäkerheten. Arbetet har skett medsimuleringsprogrammen IDA ICE och WUFI 6. Båda programmen har kombinerats för attuttnyttja deras styrkor i simuleringsprocessen.Resultatet visar att en låg luftomsättning är optimal. Ingen ventilering alls lär leda till ökadfukthalt och ökad luftomsättning lär leda till en betydligt högre risk för mögel på råsponten ivinden. Placeringen av ett litet isoleringslager ovanpå råsponten leder till en minskad risk förmögel.Ytterväggar med tjockare isolering är mer benägna att skadas i jämförelse med mindre isoleradeväggar. Dock är det visat att en uttökad isoleringstjocklek även kan vara till fördel för att minskamögelrisken om isoleringslagret som uttökas är det yttersta isoleringslagret. Ett annat krav är attdet yttersta lagret bör ha dränerande egenskaper, exempelvis mineralull. Beräkningarna har ävenpåvisat ett antal andra faktorer som påverkar fuktsäkerheten i dess helhet.
720

Pseudomonas aeruginosa Major Pseudopilin XcpT is Incorporated into The Type IV Pilus Under Native Conditions

Rana, Navpreet K. 10 1900 (has links)
<p>Retractable surface appendages Type IV pili (T4P) are one of the major virulence determinants in the opportunistic pathogen <em>Pseudomonas aeruginosa </em>(Pa), that is the leading cause of mortality in CF patients. T4P are heteropolymers composed of the major-pilin subunit PilA and the less-abundant minor pilins (MPs), FimU/PilV/W/X/E. Pilins share high sequence and structural similarity with pseudopilins (XcpT/U/V/W/X), that are proposed to form a periplasmic-structure in the evolutionarily related Type II secretion system (T2SS). Similar to T4P system, the T2SS is a multi-subunit complex that spans the inner (IM) and the outer (OM) membranes. It involves a two-step process facilitating the secretion of toxins into the extracellular milieu from the periplasm.</p> <p>Using immunogold TEM analysis and Western blot we identified, under native conditions, the major pseudopilin of T2SS XcpT, is incorporated into the T4P appendage, thus appearing on the surface. This is in contrast to previous studies reporting, the otherwise periplasmic structure, the pseudopilus appears on the surface only upon over-expression of XcpT. Further, we identified this incorporation is strictly dependent on PilA expression, such that levels of surface-XcpT co-varied with the levels of surface-PilA. However, XcpT incorporation into the T4P fiber did not affect T4P-mediated twitching motility or T2SS-mediated elastase secretion. Based on these observations we proposed two explanations. Firstly, given the similarity between XcpT and type IV pilins, it is possible the pseudopilin is recognized by the T4P machinery and therefore is incorporated into the pilus. Secondly, since XcpT incorporation does not affect T4P-mediated motility, it may affect other properties of T4P, such adherence during biofilm formation, previously associated with surface-exposed pseudopilus. In addition, we also identified enhanced expression of <em>fimU</em> and <em>pilX</em> MPs drastically increased elastase secretion, through a yet to be discovered mechanism. Regardless, our results present an alternative role of both minor pilins and XcpT in their non-native systems suggesting there is more overlap between the T4P and T2S systems than previously appreciated. Further exploration of this overlap will aid in the study of the two systems in Pa, as well as in other pathogens.</p> / Master of Science (MSc)

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