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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.
131

A historical investigation of landscape transformation in the 'Black Swamp' region of northwestern Ohio

Heide, Joni January 1995 (has links)
The Preservation movement was born out of the realization that a significant portion of our natural and cultural resources are rapidly being consumed, lost, or destroyed in the process of contemporary development. When the preservation movement began, preservationists split into two distinctly separate philosophical groups, Natural Resource Preservationists and Cultural Resource Preservationists. Natural Resource Preservationists focused upon an ecological understanding of the universe, and fought to maintain an ecological balance, while Cultural Resource Preservationists concentrated on saving each archeological or architectural artifact. The result of this divided approach produced monuments to the grand and fantastic, and museums to the famous and nationalistic, but failed to recognize the significance of the `ordinary landscape'. Ordinary landscapes are identified by the material components created by various cultures, and these components are physical representations of the human response to the natural environment that speaks will, beliefs, and the manipulation of the natural world that surrounds them.Recognizing the dynamic and continuously evolving layers of the Cultural Landscape is a critical aspect in Cultural Landscape identification and requires that the symbiotic relationship between the human occupants and the natural environment be understood within the social, political, and natural context. The basis of this project is to establish the social, political and natural context of the Black Swamp region in northwest Ohio in order to reveal the process of landscape transformation in the 'Black Swamp', and to identify areas of the landscape that may contain significant Cultural Landscapes.The 'Black Swamp' lies parallel to the east bank of the Maumee River from Lake Erie southwest to New Haven, Indiana and measures approximately 1500 square miles. Formation of the Black Swamp and the Maumee River Valley began approximately 25,000 years ago, when the Wisconsin glacier advanced southeast out of Canada and into Ohio. Glacial movement compressed the topography into its flattened form while meltwater eroded a channel known as the Maumee River.The basin-like shape of the Maumee River Valley transported water slowly to the Maumee River. Organic matter accumulated in the drainage basin and composted into a rich black loamy soil 12"-15" thick that rested on an impervious clay subsoil. Rich in humus, the transported water of the Maumee River ran black, providing nourishment for a wide variety of vegetation, which in turn supported diverse forms of wildlife.Three distinct cultures occupied the region between the years 1700 and 1850. Native Americans, Euro-American pioneers, and American settler farmer, utilized, manipulated, and transformed the `Black Swamp' environment in varying degrees, however it was the Euro-American pioneer and the American settler farmer that exerted drastic changes upon the swamp forest environment that ultimately transformed native forest into a cultivated and highly mechanized corn belt landscape.Little, if any, components remain of the Native American culture that occupied the region for over 10,000 years. However, this study has found that the settlement and transportation patterns of the Native Americans were in each case overlapped by the subsequent culture. These initial patterns of settlement and transportation layed out by the Native American were in response to the character of the natural environment and this response created the organization of the Black Swamp landscape upon future cultures layered various components. / Department of Architecture
132

Costruzione di un Sistema Informativo Geografico Digitale per analisi ambientali

Ferrucci, Barbara <1975> 28 April 2009 (has links)
Questo lavoro ha come obiettivo l’utilizzo del Geographical Information System (GIS) per effettuare analisi di sicurezza, monitoraggio e valutazioni di impatto ambientale. Oggi, la totalità delle operazioni GIS possono essere svolte con software open source e in questa sedi si è scelto di utilizzare il GIS GRASS (Geographic Resources Analysis Support System) disponibile nei termini della GNU public license (GPL), mostrando l’usabilità e le notevoli potenzialità di tale software, nonché la qualità dei prodotti ottenibili, mai inferiori ai prodotti e agli strumenti messi a disposizione dai più radicati e diffusi programmi proprietari. Nel capitolo 4, vedremo l’applicazione all’analisi delle conseguenze di ipotetici incidenti, durante le operazioni di dismissione dell’impianto di processamento del combustibile nucleare, di Bosco Marengo (AL). Nel capitolo 5, vedremo applicazioni nel campo del monitoraggio della qualità dell’aria tramite analisi di immagini satellitari.
133

Using airborne hyperspectral imagery to estimate chlorophyll a and phycocyanin in three central Indiana mesotrophic to eutrophic reservoirs /

Sengpiel, Rebecca Elizabeth. January 2007 (has links)
Thesis (M.S.)--Indiana University, 2007. / Title from screen (viewed on August 8, 2007) Includes vita. Department of Earth Sciences, Indiana University-Purdue University Indianapolis (IUPUI) Includes bibliographical references (leaves 145-149)
134

Analysis and design of high performance multiphase electric drives for vehicle and aircraft applications / Progettazione di macchine ed azionamenti elettrici multifase ad alte prestazioni per applicazioni veicolari

Rini, Giancarlo <1983> 13 May 2015 (has links)
The first part of this thesis has focused on the construction of a twelve-phase asynchronous machine for More Electric Aircraft (MEA) applications. In fact, the aerospace world has found in electrification the way to improve the efficiency, reliability and maintainability of an aircraft. This idea leads to the aircraft a new management and distribution of electrical services. In this way is possible to remove or to reduce the hydraulic, mechanical and pneumatic systems inside the aircraft. The second part of this dissertation is dedicated on the enhancement of the control range of matrix converters (MCs) operating with non-unity input power factor and, at the same time, on the reduction of the switching power losses. The analysis leads to the determination in closed form of a modulation strategy that features a control range, in terms of output voltage and input power factor, that is greater than that of the traditional strategies under the same operating conditions, and a reduction in the switching power losses.
135

Safety, Security And safeguards In GEN IV sodium fast reactors

Rossi, Fabiana <1982> 29 April 2015 (has links)
This work presents first a study of the national and international laws in the fields of safety, security and safeguards. The international treaties and the recommendations issued by the IAEA as well as the national regulations in force in France, the United States and Italy are analyzed. As a result of this, a comparison among them is presented. Given the interest of the Japan Atomic Energy Agency for the aspects of criminal penalties and monetary, also the Japanese case is analyzed. The main part of this work was held at the JAEA in the field of proliferation resistance (PR) and physical protection (PP) of a GEN IV sodium fast reactor. For this purpose the design of the system is completed and the PR & PP methodology is applied to obtain data usable by designers for the improvement of the system itself. Due to the presence of sensitive data, not all the details can be disclosed. The reactor site of a hypothetical and commercial sodium-cooled fast neutron nuclear reactor system (SFR) is used as the target NES for the application of the methodology. The methodology is applied to all the PR and PP scenarios: diversion, misuse and breakout; theft and sabotage. The methodology is applied to the SFR to check if this system meets the target of PR and PP as described in the GIF goal; secondly, a comparison between the SFR and a LWR is performed to evaluate if and how it would be possible to improve the PR&PP of the SFR. The comparison is implemented according to the example development target: achieving PR&PP similar or superior to domestic and international ALWR. Three main actions were performed: implement the evaluation methodology; characterize the PR&PP for the nuclear energy system; identify recommendations for system designers through the comparison.
136

Improvement of photon transport model by including coupled photon-electron transport and kernel refinement

Di Giulio, Eugenio <1986> 29 April 2015 (has links)
The first part of this work deals with the inverse problem solution in the X-ray spectroscopy field. An original strategy to solve the inverse problem by using the maximum entropy principle is illustrated. It is built the code UMESTRAT, to apply the described strategy in a semiautomatic way. The application of UMESTRAT is shown with a computational example. The second part of this work deals with the improvement of the X-ray Boltzmann model, by studying two radiative interactions neglected in the current photon models. Firstly it is studied the characteristic line emission due to Compton ionization. It is developed a strategy that allows the evaluation of this contribution for the shells K, L and M of all elements with Z from 11 to 92. It is evaluated the single shell Compton/photoelectric ratio as a function of the primary photon energy. It is derived the energy values at which the Compton interaction becomes the prevailing process to produce ionization for the considered shells. Finally it is introduced a new kernel for the XRF from Compton ionization. In a second place it is characterized the bremsstrahlung radiative contribution due the secondary electrons. The bremsstrahlung radiation is characterized in terms of space, angle and energy, for all elements whit Z=1-92 in the energy range 1–150 keV by using the Monte Carlo code PENELOPE. It is demonstrated that bremsstrahlung radiative contribution can be well approximated with an isotropic point photon source. It is created a data library comprising the energetic distributions of bremsstrahlung. It is developed a new bremsstrahlung kernel which allows the introduction of this contribution in the modified Boltzmann equation. An example of application to the simulation of a synchrotron experiment is shown.
137

Effect of Laser Shock Peening on Fatigue Crack Propagation of Aeronautical Structures

Taddia, Sara <1986> 08 May 2015 (has links)
Laser Shock Peening (LSP) is a surface enhancement treatment which induces a significant layer of beneficial compressive residual stresses up to several mm underneath the surface of metal components in order to improve the detrimental effects of crack growth behavior rate in it. The aim of this thesis is to predict the crack growth behavior of thin Aluminum specimens with one or more LSP stripes defining a compressive residual stress area. The LSP treatment has been applied as crack retardation stripes perpendicular to the crack growing direction, with the objective of slowing down the crack when approaching the LSP patterns. Different finite element approaches have been implemented to predict the residual stress field left by the laser treatment, mostly by means of the commercial software Abaqus/Explicit. The Afgrow software has been used to predict the crack growth behavior of the component following the laser peening treatment and to detect the improvement in fatigue life comparing to the specimen baseline. Furthermore, an analytical model has been implemented on the Matlab software to make more accurate predictions on fatigue life of the treated components. An educational internship at the Research and Technologies Germany- Hamburg department of Airbus helped to achieve knowledge and experience to write this thesis. The main tasks of the thesis are the following: -To up to date Literature Survey related to laser shock peening in metallic structures -To validate the FE models developed against experimental measurements at coupon level -To develop design of crack growth slow down in centered and edge cracked tension specimens based on residual stress engineering approach using laser peened patterns transversal to the crack path -To predict crack growth behavior of thin aluminum panels -To validate numerical and analytical results by means of experimental tests.
138

Modelling, diagnostics and experimental analysis of plasma assisted processes for material treatment

Boselli, Marco <1983> 29 April 2015 (has links)
This work presents results from experimental investigations of several different atmospheric pressure plasmas applications, such as Metal Inert Gas (MIG) welding and Plasma Arc Cutting (PAC) and Welding (PAW) sources, as well as Inductively Coupled Plasma (ICP) torches. The main diagnostic tool that has been used is High Speed Imaging (HSI), often assisted by Schlieren imaging to analyse non-visible phenomena. Furthermore, starting from thermo-fluid-dynamic models developed by the University of Bologna group, such plasma processes have been studied also with new advanced models, focusing for instance on the interaction between a melting metal wire and a plasma, or considering non-equilibrium phenomena for diagnostics of plasma arcs. Additionally, the experimental diagnostic tools that have been developed for industrial thermal plasmas have been used also for the characterization of innovative low temperature atmospheric pressure non equilibrium plasmas, such as dielectric barrier discharges (DBD) and Plasma Jets. These sources are controlled by few kV voltage pulses with pulse rise time of few nanoseconds to avoid the formation of a plasma arc, with interesting applications in surface functionalization of thermosensitive materials. In order to investigate also bio-medical applications of thermal plasma, a self-developed quenching device has been connected to an ICP torch. Such device has allowed inactivation of several kinds of bacteria spread on petri dishes, by keeping the substrate temperature lower than 40 degrees, which is a strict requirement in order to allow the treatment of living tissues.
139

Severe Accident Simulation of Small Modular Reactors

Di Giuli, Mirco <1976> January 1900 (has links)
Since the Three Mile Island Unit 2 (TMI-2), accident in 1979 which led to the meltdown of about one half of the reactor core and to limited releases of radioactive materials to the environment, an important international effort has been made on severe accident research. The present work aims to investigate the behaviour of a Small Modular Reactor during severe accident conditions. In order to perform these analyses, a SMR has been studied for the European reference severe accident analysis code ASTEC, developed by IRSN and GRS. In the thesis will be described in detail the IRIS Small Modular Reactor; the reference reactor chosen to develop the ASTEC input deck. The IRIS model was developed in the framework of a research collaboration with the IRSN development team. In the thesis will be described systematically the creation of the ASTEC IRIS input deck: the nodalization scheme adopted, the solution used to simulate the passive safety systems and the strong interaction between the reactor vessel and the containment. The ASTEC SMR model will be tested against the RELAP-GOTHIC coupled code model, with respect to a Design Basis Accident, to evaluate the capability of the ASTEC code on reproducing correctly the behaviour of the nuclear system. Once the model has been validated, a severe accident scenario will be simulated and the obtained results along with the nuclear system response will be analysed.
140

Calcoli di sezioni d'urto efficaci di riflettore in sistemi PWR di terza generazione / Reflector effective cross sections calculations for GENIII PWR systems

Guglielmelli, Antonio <1975> 29 April 2015 (has links)
La corretta modellizzazione della zona del riflettore dei sistemi GEN III+ è un passaggio fondamentale per un’accurata predizione dei parametri di cella il cui valore influenza direttamente la distribuzione di potenza su tutto il nocciolo. Tale esigenza si è resa ancora più stringente dopo la constatazione che il fenomeno del “tilt power” risulta essere più amplificato nei noccioli nucleari equipaggiati con un riflettore pesante. Per tali ragioni, nel presente lavoro di tesi si è dedicata particolare attenzione alle metodiche di modellizzazione ed alla generazione delle sezioni d’urto efficaci omogenee ed agli assembly discontinuity factors (ADF) nella zona di riflessione. Il codice deterministico utilizzato per il calcolo è SCALE 6.1.3. La notevole differenza nelle proprietà neutroniche associata ad un’elevata eterogeneità geometrica tra un nocciolo ed un riflettore hanno suggerito di effettuare un’analisi preliminare sul sistema riflettente GEN II proposto nel benchmark NEA-NSC-DOC (2013) per testare la capacità di SCALE 6.1.3 di effettuare un corretto calcolo di cella adottando una modellizzazione monodimensionale assembly/riflettore. I risultati ottenuti sono confrontati con quelli presentati nel benchmark e e con quelli valutati attraverso il codice Monte Carlo SERPENT 2.0 confermando la capacità di calcolo di SCALE 6.1.3. L’analisi sulla modellizzazione dei sistemi riflettenti GEN III+ è stata effettuata ricavando il valore dei parametri di cella per configurazioni omogenee ed una serie di configurazioni geometriche esatte che comprendono tutte le modellizzazioni del sistema riflettente lungo la direzione angolare del riflettore. Si è inoltre effettuata un’analisi di sensitività su parametri operativi e sui parametri di codice. Si è infine effettuato un calcolo in color-set per indagare l’influenza degli effetti 2-D sui parametri di cella. I risultati prodotti rappresentano un contributo migliorativo nella conoscenza dei parametri di cella di riflettore e potranno essere utilizzati per una più precisa valutazione del fenomeno del tilt nei sistemi GEN III+. / In GEN III+ systems the correct modelization of the reflector zone is a key step for an exact prediction of the cell parameters whose values directly affect the radial power distribution of the core system. This need has become even more necessary after the discovery of the amplification of the “tilt power” phenomenon in the GEN III+ nuclear core. For this reason, special care is taken in the modelization methodology and in the generation of reflector homogenized cross-section and discontinuity factor (DFs) on the reflector zone. The deterministic package code used for the cell data calculation is SCALE 6.1.3 suite. The strong difference in the neutronic properties at core/reflector interface combined with a high geometric heterogeneity between a core and a reflector system have suggested to perform a preliminary analysis on the GEN II reflector system as presented by NEA-NSC-DOC (2013) benchmark with the aim of testing the capability of the deterministic code to perform a correct calculation on a 1-D assembly/reflector modelization. The results, which are in good agreement with those evaluated with SERPENT 2.0 Monte Carlo code, confirmed the capability of SCALE code to perform cell data reflector calculations. The modelization analysis on the GEN III+ reflector system has been performed for two homogeneous configurations and for a series of exact heterogeneous zones along the angular direction of the reflector. It has been also realized a sensitivity analysis on operational and code parameters. Finally, it was performed a 2x2 color-set calculation to investigate the 2-D geometry effects on the numerical values of cell reflector parameters. The final results are an improvement in the scientific knowledge of the reflector cell data values. These values can be used in a EPR nodal code calculation for a more accurate assessment of the core power distribution and of the “power tilt” values.

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