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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.
211

Cosmogenic dating of fluvial terraces in the Sorbas Basin, SE Spain

Ilott, Samantha January 2014 (has links)
Long term fluvial incision spanning the Late Cenozoic is recorded in many fluvial systems around the world by terrace landform sequences. The incision manifests itself as inset sequences of river terraces which form terrace staircases. The timing of the onset of incision and the rate incision then proceeds at is poorly constrained due to the difficulties in dating river terraces. This study applies the technique of cosmogenic exposure dating to a fluvial staircase, for the first time, in the Sorbas Basin, SE Spain. Cosmogenic exposure dating allows the timing of abandonment of the fluvial terraces to be calculated therefore recording periods of incision. Cosmogenic exposure dating and the profile method offer a viable way to date Early and Middle Pleistocene terrace deposits. Combined exposure and burial age’s approaches using paired isotopes allow for insights into terrace aggradation and fluvial incision timing. The fluvial deposits in the Sorbas Basin record 1.0 Ma of incision by the Río Aguas. The timing of aggradation and incision in the Sorbas basin has been linked to both tectonics and climate cycles. Terrace aggradation took place in glacial and interglacial periods. The abandonment of terrace surfaces occurred both at warming transitions and in interglacial periods. New uplift rates calculated for the Pleistocene fluvial system suggest that tectonic activity in the Sorbas Basin has been episodic. The south margin and centre of the Sorbas Basin has uplifted at a faster rate than the northern margin impacting on the rates of incision taking place in the fluvial systems. Overall tectonic uplift has increased the fluvial system sensitivity to climatic variations.
212

Chatting online : comparing spoken and online written interaction between friends

Meredith, Joanne January 2014 (has links)
This thesis addresses the question of whether or not online interactional practices are systematically different from interaction in other contexts, particularly spoken interaction. I will establish how the organization of online interaction demonstrates participants orientations to the technological affordances of the online medium. The dataset for the study comprises one-to-one interaction between friends, conducted using the chat application of the social networking site, Facebook. Chat logs and screen capture data were used to analyze how participants engaged in, and managed, their unfolding interaction. The data were analyzed using conversation analysis (CA). CA was developed originally for the analysis of spoken talk, but in this dissertation it provides an empirical basis for comparing Facebook chat and spoken interaction. The thesis demonstrates how CA can be used for analyzing online interaction. The first analytic chapter provides an overview of how participants organize the generic orders of interaction. The findings suggest that participants draw on their knowledge of both spoken and written interaction when managing the particular interactional constraints and affordances of Facebook chat. The second analytic chapter focuses on chat openings, comparing them to openings in spoken interaction. The findings reveal some similarities, but also systematic differences which orient to the design of the chat software. The third analytic chapter examines topic management, including topic-initiation, topic change and the management of simultaneous topics. The findings suggest that the CA categorization of topic-initiating turns could potentially be extended by also analyzing action-orientation and also the epistemic stance displayed. The analysis also reveals remarkable similarities between topic change in spoken interaction and in Facebook chat. Finally in this chapter I show how organizational components of spoken interaction, such as adjacency pairs and tying techniques, are used to manage simultaneous topics. The final analytic chapter focuses on self-repair in Facebook chat. The analysis reveals that self-repairs completed during message construction orient to the same interactional contingencies as self-repairs in spoken interaction. However, the affordances of Facebook chat enable these repairs to be hidden from the recipient. Visible repairs tend to be corrections, with the affordances impacting the sequential placement of such repairs. Finally, I show how participants self-repair in response to the actions of their co-participant. Overall, the findings reveal a number of similarities between the organization of Facebook chat and spoken interaction. The analysis also reveals that participants attend to the technological affordances of Facebook in a variety of ways. Finally, this thesis demonstrates that, while there are differences between the interactional practices of spoken and online written interaction, CA can be used to analyze, and subsequently explain, such differences.
213

Kostnaden för CCS vid Cementa AB i Degerhamn

Nyberg, Jesper January 2016 (has links)
CCS, Carbon Capture and Storage, innebär infångning och lagring av koldioxid från stora punktutsläpp. Detta gör cementindustrin aktuell för implementering av CCS. Stora delar av branschens koldioxidutsläpp går inte att eliminera på annat sätt. Kostnaden för monoetanolamin-baserad post-combustion capture med efterföljande transport och lagring av koldioxiden vid cementfabriken Cementa AB i Degerhamn undersöktes. Studiens kostnadsberäkningar är baserade på publicerade uppgifter om kostnaden för koldioxidinfångning vid den norska cementfabriken Norcem Brevik, och på publicerade uppgifter om kostnaden för transport av koldioxid till en lagringsplats i Östersjön. Cementa Degerhamns koldioxidutsläpp kan reduceras med 5,4 miljoner ton under en 25-årsperiod till en kostnad av 2,2 miljarder SEK. Slutresultatet, som uttrycks i måttet Cost of CO2 avoided, ger en kostnad på 890 SEK/ton CO2. En känslighetsanalys visar att av de undersökta parametrarna är storleken på koldioxidutsläppen och kostnaden för användning och underhåll viktigast för storleken på Cost of CO2 avoided. Vidare studier behövs för en mer exakt beräkning av kostnaden för CCS vid Cementa Degerhamn. / CCS, Carbon Capture and Storage, involves the capture and storage of carbon dioxide from large point sources. This makes the cement industry suitable for the implementation of CCS. Large parts of the industry's carbon dioxide emissions cannot be eliminated by other means. The cost of monoethanolamine-based post-combustion capture and subsequent transport and storage of the carbon dioxide at the cement factory Cementa AB in Degerhamn was studied. This study's cost estimates are based on published data on the cost of carbon capture at the Norwegian cement plant Norcem Brevik, and on published data on the cost of transport of carbon dioxide to a storage site in the Baltic Sea. Cementa Degerhamn’s carbon dioxide emissions can be reduced by 5.4 million tons over a 25 year period to a cost of 2.2 billion SEK. The result, expressed in Cost of CO2 avoided, gives a cost of 890 SEK/ton CO2. A sensitivity analysis shows that of the examined parameters, the size of the carbon dioxide emissions and the cost of use and maintenance are the most important for the size of Cost of CO2 avoided. Further studies are required for a more accurate calculation of the cost of CCS at Cementa Degerhamn.
214

Document Retrieval Triggered by Spacecraft Anomaly: Using the Kolodner Case-Based Reasoning (CBR) Paradigm to Design a Fault-Induced Response System

Kronberg, F., Weiner, A., Morgan, T., Stroozas, B., Girouard, E., Hopkins, A., Wong, L., James, M., Kneubuhl, J., Malina, R. F. 10 1900 (has links)
International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / We report on the initial design and development of a prototype computer-mediated response system, the Fault Induced Document Officer (FIDO), at the UC Berkeley Center for EUV Astrophysics (CEA) Extreme Ultraviolet Explorer project (EUVE). Typical 24x7 staffed spacecraft operations use highly skilled expert teams to monitor current ground systems and spacecraft state for responding to anomalous ground system and spacecraft conditions. Response to ground system error messages and spacecraft anomalies is based on knowledge of nominal component behavior and the evaluation of relevant telemetry by the team. This type of human-mediated operation is being replaced by an intelligent software system to reduce costs and to increase performance and reliability. FIDO is a prototype software application that will provide automated retrieval and display of documentation for operations staff. Initially, FIDO will be applied for ground systems. Later implementations of FIDO will target spacecraft systems. FIDO is intended to provide system state summary, links to relevant documentation, and suggestions for operator responses to error messages. FIDO will provide the operator with near realtime expert assistance and access to necessary information. This configuration should allow the resolution of many anomalies without the need for on-site intervention by a skilled controller or expert.
215

Rapid screening of novel nanoporous materials for carbon capture separations

Mangano, Enzo January 2013 (has links)
In this work the experimental results from the rapid screening and ranking of a wide range of novel adsorbents for carbon capture are presented. The samples were tested using the Zero Length Column (ZLC) method which has proved to be an essential tool for the rapid investigation of the equilibrium and kinetic properties of prototype adsorbents. The study was performed on different classes of nanoporous materials developed as part of the EPSRC-funded “Innovative Gas Separations for Carbon Capture” (IGSCC) project. More than 120 novel adsorbents with different key features for post-combustion carbon capture were tested. The classes of materials investigated were: • PIMs (Polymers of Intrinsic Microporosity) • MOFs (Metal - Organic Frameworks) • Mesoporous Silica • Zeolites • Carbons All the samples were tested at experimental conditions close to the ones of a typical flue gas of a fossil fuel power plant: 35 ºC and 0.1 bar of partial pressure of CO2. The results from the ranking of the CO2 capacity of the materials, at the conditions of interest, indicate the Mg and Ni-based MOF samples as the adsorbents with the highest uptake among all the candidates. The best sample shows a CO2 capacity almost double than the benchmark adsorbent, zeolite 13X (provided by UOP). The ranking also shows some of the zeolite adsorbents synthesised as promising materials for carbon capture: uptakes comparable or slightly higher than 13X were obtained for several samples of Rho and Chabazite zeolite. Water stability tests were also performed on the best MOFs and showed a deactivation rate considerably faster for the Mg-based MOFs, proving an expected higher resistance to degradation for the Ni based materials. A focused investigation was also carried out on the diffusion of CO2 in different ionexchanged zeolites Rho samples. The study of these samples, characterised by extremely slow kinetics, extended the use of the ZLC method to very slow diffusional time constants which are very difficult to extract from the traditional long time asymptotic analysis. The results show how the combination of the full saturation and partial loading experiment can provide un-ambiguous diffusional time constants. The diffusivity of CO2 in zeolite Rho samples shows to be strongly influenced by the framework structure as well as the nature and the position of the different cations in the framework. The kinetics of the Na-Cs Rho sample was also measured by the use of the Quantachrome Autosorb-iQ™ volumetric system. To correctly interpret the dynamic response of the instrument modifications were applied to the theoretical model developed by Brandani in 1998 for the analysis of the piezometric method. The analytical solution of the model introduces parameters which allow to account for the real experimental conditions. The results confirm the validity of the methodology in the analysis of slow diffusion processes. In conclusion the advantages offered by the small size of the column and the small amount of sample required proved the ZLC method to be a very useful tool for the rapid ranking of the CO2 capacity of prototype adsorbents. Equilibrium and kinetic measurements were performed on a very wide range of novel nanoporous materials. The most promising and interesting samples were further investigated through the use of the water stability test, the partial loading experiment and the volumetric system. The ZLC technique was also extended to the measurements of systems with very slow kinetics, for which is very difficult to extract reliable diffusional time constants. An improved model for the interpretation of dynamic response curves from a non-ideal piezometric system was developed.
216

Thermodynamics of aqueous piperazine/aminoethylpiperazine for CO₂ capture

Du, Yang, active 21st century 11 September 2014 (has links)
Aqueous piperazine (PZ) blended with N-(2-aminoethyl) piperazine (AEP) is an attractive solvent for CO₂ capture from coal-fired power plants. Blending PZ with AEP can remediate the precipitation issue of concentrated PZ while maintaining its high CO₂ absorption rate, and high resistance to degradation. 5 m PZ/2 m AEP also shows a milder nitrosamine issue than concentrated piperazine. A rigorous thermodynamic model was developed in Aspen Plus® to predict properties of PZ/AEP/H₂O/CO₂, using the electrolyte-Nonrandom Two-Liquid (eNRTL) activity coefficient model. A sequential regression was performed to represent CO₂ solubility, speciation, and amine volatility data over operationally significant loading and temperature ranges. The model predicts a CO₂ cyclic capacity of 0.78 mol/kg (PZ + AEP + water) for 5 m PZ/2 m AEP, compared to 0.50 mol/kg for 7 m MEA and 0.86 mol/kg for 8 m PZ. The predicted heat of absorption is 75 to 80 kJ/mol CO₂ at the operating loading range (0.290-0.371 mol CO₂/mol alkalinity). Although 5 m PZ/2 m AEP has a slightly lower CO₂ capacity than 8 m piperazine, its higher heat of absorption may offset the negative effect on energy consumption. Speciation for PZ/AEP/H₂O at various CO₂ loading and temperature was also predicted, from which behavior of CO₂ in the amine system was proposed. / text
217

Activation and Capture of Carbon Dioxide and Carbon Disulfide by N-Containing Compounds

Ang, Mary Trisha Cabacungan 04 December 2013 (has links)
The interaction between carbon dioxide (CO2) and N-compounds such as 1,8-diazobicyclo[5.4.0]undec-7-ene (DBU) has been extensively studied in the Jessop Lab. Carbon disulfide (CS2) is the sulfur congener of CO2, although it exhibits different reactivity with N-containing compounds. This thesis presents the search for zwitterionic CO2-switchable polarity solvents, new and general reactivity of CS2 with amidines and guanidines, and attempts at using CO2 as a carbonyl source in the synthesis of nitrogen containing compounds. In the second chapter, the reactions of CO2 with various diamines are described. Spectroscopic methods and X-ray crystallography determined the structure of a solid zwitterionic carbamate salt of CO2 and N,N’-dimethyl-1,3-propanediamine. The polarity of the liquid zwitterionic carbamate salt formed with N,N,N’-trimethyl-1,3-propanediamine was measured using UV-Vis and the solvatochromic dye Nile red; its polarity was comparable to previous switchable polarity systems. The CO2 gravimetric uptake of the liquid zwitterionic carbamate salt was 28%, far greater than other solvents for the capture and release of CO2. In the third chapter, it was found that a variety of products can be accessed depending on the structure of the N-base (cyclic or acyclic) upon reaction of the base with CS2 at room temperature. The reaction of CS2 with cyclic amidines produced a cyclic trithioanhydride structure, forming a new C-C bond at a sp2-carbon beta to the imino nitrogen centre. When an amidine was acyclic it led to cleavage and formation of isothiocyanates in near quantitative yields. When a N-base had a N-H bond, CS2 can insert, forming a dimer in the presence of dichloromethane. In the fourth chapter, preliminary investigations are ascribed for synthesis of α-amino acids, amides, and ureas. Carboxylation of ketimines was detected, although the formed carboxylates from a variety of ketimines readily decomposed. Isomerization products of two ketimines were generated with DBU and CO2. Lewis acid catalysts were implemented towards the amidation of benzoylacetic acid and synthesis of ureas. Amidation of benzoylacetic acid did not occur in the presence of Lewis acid catalysts and CO2. Formation of a cyclic tetraalkylurea was afforded in low yields by the use of a diamine, CO2 and Lewis acid catalysts. / Thesis (Ph.D, Chemistry) -- Queen's University, 2013-12-01 19:16:55.257
218

Gamma spectroscopy of the doubly - odd ¹��T1 nucleus.

Ramashidzha, Tshifhiwa Marius January 2006 (has links)
<p>The odd &ndash / odd Tl nuclei with A &ge / 190 have moderate oblate nuclear deformation and show rotational bands built on different quasiparticle excitations. Several phenomena, not yet fully understood, were observed in these nuclei, such as large signature splitting in the yrast band (built on a &pi / h9/2&otimes / &nu / i13/2 configuration), possible non &ndash / axiality of the nuclear shape, etc. In this work the high &ndash / spin states in 194Tl were studied. The 194Tl nuclei were produced in the 181Ta (18O, 5n) 194Tl reaction at a beam energy of 93 MeV and the &gamma / - rays were detected using the AFRODITE array. The obtained extended level scheme of 194Tl is presented and discussed in this work. CSM (Cranking shell model) and TRS (Total Routhians Surface) models were both applied to interpret the results for band 1. The results were compared with the neighboring isotone 193Hg.</p>
219

The development and applications of serious games in the public services : defence and health

Paraskevopoulos, Ioannis January 2014 (has links)
The latest advances of Virtual Reality technologies and three-dimensional graphics, as well as the developments in Gaming Technologies in the recent years, have stemmed the proliferation of Serious Games in a broader spectrum of research applications. Among the most popular areas of application are public services such as Defence and Health, where digital technologies realise new challenges and opportunities for research and development of Serious Games and for a variety of contexts. As with all games, the user engagement is elevated and apart from the entertaining aspect, Serious Games serve as a novel and promising alternative experience to knowledge transfer. Furthermore, Serious Games bring to the end user and the overall society a series of attractive benefits. These benefits include safety, cost-effectiveness, increased motivation and personalisation. Hence, this Thesis aims to investigate novel approaches of developing Serious Games that utilise the recent advances of Virtual Reality and Gaming Technology and facilitate the aforementioned benefits. The process of design and development of the novel tools and applications follow an iterative manner and are driven by the review of the available literature as well as end-user feedback.
220

Pyrene-Derived Porous Organic Polymers: Design, Synthesis, and Application to Gas Storage and Separation

Sekizkardes, Ali Kemal, PhD 01 January 2014 (has links)
Porous organic polymers (POPs) received great attention in recent years because of their novel properties such as permanent porosity, adjustable chemical nature, and remarkable thermal and chemical stability. These attractive features make POPs very promising candidates for use in gas separation and storage applications. In particular, CO2 capture and separation from gas mixtures by POPs have been intensively investigated in recent years because of the greenhouse nature of CO2, which is considered a leading cause for global warming. CO2 chemical absorption by amine solutions from the flue gas of coal-fired power plants suffers from several challenges such as high-energy consumption in desorption, chemical instability, volatility, and corrosive nature, limiting the widespread use of this technology. To mitigate these limitations, new adsorbents with improved CO2 capturing properties need to be designed, synthesized, and tested. Alternatively, the use of cleaner fuels such as methane can reduce CO2 release or completely eliminates it in the case of hydrogen. However, the on-board storage of methane and hydrogen for automotive applications remains a great challenge. With these considerations in mind, our research goals in this dissertation focus on the systematic design and synthesis of N-rich POPs and their use in small gas (H2 and CH4) storage as well as selective CO2 capture from gas mixtures. In particular, we have studied the effect of integrating pyrene and triazine building units into benzimidazole-linked polymers (BILPs) and covalent organic frameworks (COFs) on gas storage and separation. We have found that pyrene-based BILPs exhibit remarkable selective CO2 capturing capacities under industrial settings (VAS, PSA). However the methane and hydrogen storage capacities of BILPs were found to be only modest especially at high pressure due to their moderate surface area and pore volume. We addressed these limitations by the synthesis of a highly porous imine-linked COF (ILCOF-1), which has very high surface area and improved hydrogen and methane uptakes when compared to BILPs. We have demonstrated that the use of pyrene in BILPs and COFs can direct frameworks growth through - stacking and improve porosity and pore volume whereas the use of triazine is instrumental in improving the binding affinity of the frameworks towards CO2.

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