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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.
201

Modelling the hydrology of the Greenland Ice Sheet

Banwell, Alison Frances January 2013 (has links)
There is increasing recognition that the hydrology of the Greenland Ice Sheet plays an important role in the dynamics and therefore mass balance of the ice sheet. Understanding the hydrology of the ice sheet and being able to predict its future behaviour is therefore a key aspect of glaciological research. To date, the ice sheet’s hydrology has tended to be inferred from the analysis of surface velocity measurements, or modelled in a theoretical, idealised way. This study focuses on the development of a high spatial (100 m) and temporal (1 hour) resolution, physically based, time-dependent hydrological model which is applied to the ~2,300 km2 Paakitsoq region, West Greenland, and is driven, calibrated, and evaluated using measured data. The model consists of three components. First, net runoff is calculated across the ice sheet from a distributed, surface energy- balance melt model coupled to a subsurface model, which calculates changes in temperature, density and water content in the snow, firn and upper-ice layers, and hence refreezing. The model is calibrated by adjusting key parameter values to minimize the error between modelled output and surface height and albedo measurements from the three Greenland Climate Network (GC-Net) stations, JAR 1, JAR 2 and Swiss Camp. Model performance is evaluated in two ways by comparing: i) modelled snow and ice distribution with that derived from Landsat-7 ETM+ satellite imagery using Normalised Difference Snow Index (NDSI) classification and supervised image thresholding; and ii) modelled albedo with that retrieved from the Moderate- resolution Imaging Spectroradiometer (MODIS) sensor MOD10A1 product. Second, a surface routing / lake filling model takes the time-series of calculated net runoff over the ice sheet and calculates flow paths and water velocities over the snow / ice covered surface, routing the water into ‘open’ moulins or into topographic depressions which can fill to form supraglacial lakes. This model component is calibrated against field measurements of a filling lake in the study area made during June 2011. Supraglacial lakes are able to drain by a simulated hydrofracture mechanism if they reach a critical volume. Once water is at the ice / bed interface, discharge and hydraulic head within subglacial drainage pathways are modelled using the third model component. This consists of an adaptation of a component (EXTRAN) of the U.S. Environmental Protection Agency Storm Water Management Model (SWMM), modified to allow for enlargement and closure of ice-walled conduits. The model is used to identify how the subglacial hydrological system evolves in space and time in response to varying surface water inputs due to melt and lake drainage events, driven ultimately by climate data. A key output from the model is the spatially and temporally varying water pressures which are of interest in helping to explain patterns of surface velocity and uplift found by others, and will ultimately be of interest for driving ice dynamics models.
202

Acoustics and manufacture of Caribbean steelpans

Maloney, Soren E. January 2011 (has links)
The Caribbean steelpan is a pitched percussion instrument that originated in Trinidad and Tobago during the Second World War. Despite several research initiatives to improve the making of this relatively new instrument, several areas remain unaddressed. This thesis presents new approaches to help improve the making of the instrument. These approaches are situated in the production, vibration and material aspect of the steelpan. A novel sheet forming technology termed Incremental Sheet Forming (ISF) is applied to the production of miniature steelpan dishes. The thickness distribution in the wall of the ISF dishes is compared to the wall thickness distribution in a traditionally formed steelpan dish and a wheeled dish. Unlike traditional forming and wheeling, ISF produces stretching in only a portion of the walls of the formed dishes. Multi-pass ISF is used to extend the stretched zone but this extension is minimal. A break even analysis is also applied to investigate the fiscal viability of ISF application to the production of miniature and full size steelpan dishes. The application of ISF to steelpan making is found to be commercially profitable but could be jeopardised by the tuning stage of the steelpan making process. A preliminary study on the effect of impact on tone stability is conducted on a pair of notes on a fullsize steelpan and detuning is found more likely to occur by repeated impact of the note at its centre. Mode confinement in test-pans is also investigated. ISF is used to produce miniature test-pans with test-notes that are geometrically identical to notes on full size pans. It is possible to confine modes by varying the curvature of the bowl surrounding the test-note. The number of localised modes in the test-note increases as the radius of curvature of the surrounding bowl increases. The natural frequency of the first confined mode in the test-notes is sensitive to material springback in ISF and the mechanism of confinement appears to be due to the change in geometry that occurs between the flat test-note region and the bowl wall. This control of mode confinement may find use in future efforts to completely or partially automate the steelpan making process. Material damping and mechanical properties in low-carbon steel used to produce steelpans are researched. Damping and mechanical properties are extracted from low-carbon steel that is subjected to identical stages to the steelpan production process. Material damping trends suggest that an annealing temperature between 300°C and 400°C would be appropriate for the heat treatment of steelpans. Air-cooled and water-quenched low-carbon specimens exhibit comparable damping trends. Hardness increases in cold formed low-carbon specimens is attributed to strain hardening and not strain ageing. Investigation of damping trends and mechanical properties in ultra low bake-hardenable and interstitial-free steels reveals that a wider range of low-carbon steels may be suitable for steelpan making.
203

Analýza rozpočtů města Mělník v letech 2003-2015 / Budget Analysis of the Town Mělník in the Years 2003-2015

Šimko, Viktor January 2016 (has links)
The thesis deals with the budget of the town of Mělník. The thesis is aimed at analysing the development of budgets in the years 2003 - 2015, and ascertaining the major determinants affecting these budgets. Besides, the thesis uses the town`s balance sheets, and describes the development of property and indebtedness ratio of the town of Mělník. The theoretical part is concerned with local governments and their budget creation, and also describes municipal property and funding possibilities. The practical part analyses budgets, revenues and expenses thereof, as well as the balance sheets showing Mělník`s property and indebtedness. On the basis of the data from the budget and balance sheet development, a medium-term outlook for the town`s economic activity was created.
204

Význam rozvahy v účetním výkaznictví Švýcarska / Importance of balance sheet in the Swiss financial reporting

Dufková, Iva January 2012 (has links)
The thesis investigates the importance of balance sheet in the Swiss financial reporting. At first it shows, on a theoretical basis, which is represented by balancing theories, the essential role of the balance sheet for recipients of accounting information. It also deals with the accounting legislation in Switzerland, general accounting principles, financial statement and its appurtenances and projection of selected balance sheet items. Moreover it examines the information capability of the balance sheet on the practical example of a Swiss company.
205

Criteria for Selecting PEGylation Sites on Proteins for Higher Thermodynamic Stability

Lawrence, Paul B. 01 June 2016 (has links)
PEGylation of protein side-chains has been used for more than 30 years to enhance the pharmacokinetic properties of protein drugs, and has been enabled by the recent development of many chemoselective reactions for protein side-chain modification. However, there are no structure- or sequence-based guidelines for selecting sites that provide optimal PEG-based pharmacokinetic enhancement with minimal loss to biological activity. Chapter 1 is a brief introduction to protein PEGylation. In chapter 2 we use the WW domain of the human protein Pin 1 (WW) as a model system to probe the impact of PEG on protein conformational stability. Using a combination of experimental and theoretical approaches, we develop a structure-based method for predicting which sites within WW are most likely to experience PEG-based stabilization, and show that this method correctly predicts the location of a stabilizing PEGylation site within the chicken Src SH3 domain. PEG-based stabilization in WW is associated with enhanced resistance to proteolysis, is entropic in origin, and likely involves disruption by PEG of the network of hydrogen-bound solvent molecules that surround the protein. Chapter 3 shows that PEG-based stabilization of the WW domain depends strongly on the identity of the PEG-protein linker, with the most stabilizing linkers involving conjugation of PEG to an Asn side-chain amide nitrogen. Chapter 4 investigates the interplay between structure-based guidelines for PEG-base stabilization developed in chapter 2 and the different chemistries explored in chapter 3.
206

Health Monitoring of Large Composite Structures

Jaswal, Priya 28 October 2019 (has links)
No description available.
207

Tažení pocínovaného ocelového plechu / Drawing of a tin-coated metal sheet

Hudousek, Jiří January 2018 (has links)
HUDOUSEK Jiří: Drawing of a tin-coated metal sheet. The project elaborated in frame of master studies is submitting design of the given part production - business card case from tin-coated metal sheet by deep drawing technology. From a variations of the design of the product has been chosen option, when the case is assembled from two identical drawn parts which form the bottom and the lid of the component, the connection of these two parts is arranged by a spacer in form of a plastic insert on which the metal parts are attached. Based on the literary survey and calculations drawing in die with blankholder was designed for metal parts production, according to the force needed and tool size a hydraulic press ZH 100 was selected. Part of the work is the process parameters determination, technical and economic evaluation and drawing documentation.
208

Návrh nástroje pro výrobu tvarových přístřihů / Design of a tool for production of shaped blanks

Řáda, Aleš January 2010 (has links)
Master thesis reports questions about purchasing supplies for stamping shop. It solves task, that is cheaper buy blanks, or buy coils and cut them in free time of Raster 250 press. Thesis contains a design of cutting tools for production rectangular and trapeze shaped blanks. Tool for cutting of rectangular blanks is documented with drawings of assembly and main parts. The project was verified in techno-economic summary including repayment time calculation.
209

Analýza možností laserového řezání / The analisys of possibility laser cutting

Plevka, Vojtěch January 2013 (has links)
Master’s thesis deals with application of lasers in manufacturing, mainly with the technology of cutting material. This technology is compared with the technology of punching and cutting sheet metal, with the aid of control specimens. The parameters of surface structure, dimension accuracy and appearance of cut-ting surfaces are compared. By consensus of results the recommendation for practical realization was created.
210

Features of Random Metal Nanowire Networks with Application in Transparent Conducting Electrodes

Maloth, Thirupathi 05 1900 (has links)
Among the alternatives to conventional Indium Tin Oxide (ITO) used in making transparent conducting electrodes, the random metal nanowire (NW) networks are considered to be superior offering performance at par with ITO. The performance is measured in terms of sheet resistance and optical transmittance. However, as the electrical properties of such random networks are achieved thanks to a percolation network, a minimum size of the electrodes is needed so it actually exceeds the representative volume element (RVE) of the material and the macroscopic electrical properties are achieved. There is not much information about the compatibility of this minimum RVE size with the resolution actually needed in electronic devices. Furthermore, the efficiency of NWs in terms of electrical conduction is overlooked. In this work, we address the above industrially relevant questions - 1) The minimum size of electrodes that can be made based on the dimensions of NWs and the material coverage. For this, we propose a morphology based classification in defining the RVE size and we also compare the same with that is based on macroscopic electrical properties stabilization. 2) The amount of NWs that do not participate in electrical conduction, hence of no practical use. The results presented in this thesis are a design guide to experimentalists to design transparent electrodes with more optimal usage of the material.

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