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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.
161

Microstructure and Mechanical Properties of Al-10at%Fe Alloy Subjected to Friction Stir Processing

Lee, I-shan 07 August 2006 (has links)
In this study, billet of a binary Al-10at%Fe alloy was prepared from pure Al and Fe powders by the use of conventional press and sinter route. The sintered billet was then subjected to multiple passages of friction stir processing (FSP). After FSP, the structure of a binary Al-10at%Fe alloy can be refined to sub-micrometer scale. Transmission electron microscopy (TEM) showed that particles of Fe-containing phase were distributed uniformly in the aluminum matrix, and the mean size of these second phase particles was about 100nm. From the results of X-ray diffraction and energy dispersive spectroscopy (EDS), the Al-Fe second phase was identified as Al13Fe4. We also observed obvious reaction zone around iron particles in the friction-stirred zone. Apparently, a rapid in-situ reaction between Al and Fe had occurred in FSP. In order to reduce the reaction time and the heat input, the higher traversing speed was used. In addition, a higher sintering temperature was used to promote Al-Fe reaction. Furthermore, micro-hardness, tensile and compressive tests were performed to evaluate the mechanical properties of the Al-10at%Fe alloy fabricated by FSP.
162

Detaljerad FE-modellering

Lund, Per, Jakobsson, Peter January 2015 (has links)
Detta examensarbete beskriver undersökningen av kärnmaterial i en sandwichpanel under belastning. Arbetet har utförts tillsammans med CCG i Laholm, Sverige. Kärnmaterialen lämpar sig vid design av sandwichpaneler på grund av sin låga vikt och sin förmåga att klara av högt tryck. Då materialet uppvisar ett ickelinjärt beteende skapar det problem vid design av sandwichpaneler och leder till att materialsammansättningarna tillverkas konservativa mot verkligheten. Projektet har gått ut på reducera designprocessen genom att bygga upp och simulera materialmodeller i programvaran ABAQUS för att kunna analysera och förutse materialets beteende. Resultaten har presenterats i kraft- och förskjutningsdiagram samt visualiseringar och har försvarats med hjälp av teorier för kontaktmekanik samt matematik. Projektet har utförts på ett vetenskapligt sätt där hypotes verifieras mot teori för att sedan verifieras i experiment, allt för att säkerställa resultatet. / This thesis describes a study of the core materials used in composite panels under static indentation. The work was conducted together with CCG in Laholm, Sweden. These materials work well when designing sandwich panels due to their low weight and high compression strength. As the cores show a non-linear behavior problems can arise when constructing panels and oftentimes lead to choosing very conservative solutions that are not optimized.The main focus of this thesis has been the modelling and simulation of materials in the software ABAQUS to analyze and predict the materials behavior and reduce the time needed for the design of new panels. The result is presented in force- displacement plots as well as von Mises visualization plots and is sustained by theories of both contact mechanics and mathematics. The group endeavored to work in a scientific manner by verifying the hypotheses through theory and experiments in order to accomplish accurate results.
163

El sentimiento trágico en San Manuel Bueno, mártir : Una lucha contra la razón en búsqueda de la fe / : The tragic sense of Saint Manuel Bueno, martyr: A struggle against the reason in search of faith

Tapia Tapia, Marcela January 2015 (has links)
Este trabajo de investigación tiene como fin analizar el pensamiento del autor Miguel de Unamuno para poder relacionarlo con los pensamientos del personaje del cura de la novela San Manuel Bueno, mártir. El objetivo es buscar la relación que existe entre el autor y el cura en lo que se refiere a los temas relacionados con la religión. Para este estudio se utilizará la metodología hermenéutica donde se analizará el pensamiento del autor en relación con el personaje San Manuel, basándose principalmente en el libro Del sentimiento trágico de la vida, uno de los libros más destacados sobre el pensamiento filosófico del autor. Al final, como una pequeña aportación a la tesis, se hablará de la posible misión profética que tuvo Unamuno en sus últimos años de vida que a través de sus obras quiso despertar la conciencia de sus lectores para que se unieran a la búsqueda de la verdadera fe.
164

Formation of Fe-rich subsurface precipitate layers on White Island, New Zealand

Win, Noel Antony January 2014 (has links)
White Island is a highly active volcano with an acidic, S-rich hydrothermal system in the Bay of Plenty, North Island, New Zealand. In this acidic environment a series of subsurface Fe-rich layers are ubiquitous in the crater sediments at shallow depth and are capable of modifying the flow and gas flux dynamics in the system. The mineralogy of the subsurface Fe-rich layer(s) and the processes leading to their formation are unknown. Here the mineralogy and formation of the subsurface Fe-rich layers in relation to the surface and subsurface environment(s) within the Main Crater at White Island are assessed. Based on geochemical analyses, subsurface Fe-rich crusts are composed of a mix of jarosite and goethite, cementing crater fill sediments into cohesive layers. Saturation index (SI) and Eh/pH assessments identify that fluids evolved at White Island are undersaturated with respect to the mineral phases present in the Fe-rich subsurface layers. Formation of the Fe-rich subsurface layers is most likely related to the transition between atmospheric gases and/or meteoric water mixing with hydrothermal fluids. This transition zone creates an environment conducive to forming jarosite and goethite forming in the same layer. Additionally, subsurface sediments including the Fe-rich layers show a consistent organic carbon isotopic signature of -23 ‰. Microscopic investigations confirm diatoms and microbes are present in the subsurface Fe-rich layers. The full extent of microbial activity in relation to the Fe-rich layers at White Island still requires further investigation. Based on chemical extractions for isotopic analyses, Fe-rich layers are shown to preserve δ¹³C signatures indicative of microbial life. Interface zones such as those identified in the hydrothermal environment at White Island can create metal-rich deposits and habitable/preservative microbial environments as well as affecting the macroscopic dynamics of volcanic and epithermal systems.
165

The studio of painting at the Santa Fe Indian School : a case study in modern American identity

Hahn, Milanne Shelburne 30 January 2012 (has links)
Founded in 1932, the Department of Painting and Design, or “Studio,” at the Santa Fe Indian School was the first official, government-run boarding school program to promote pictorial paintings based exclusively North American Indian arts and culture. It was yet another program designed to bring about the assimilation of Indians into the economy and society of American, but progressive influences had introduced a change in orientation to Indian Policy by the beginning of the 1930s; instead of demeaning Indian cultures by demanding cultural assimilation, a beneficent stance was adopted that promoted them and their assimilation as American Indians into the ethnic diversity of society. As the Studio experience unfolded, it became a unique art world in which Indian artist-students from various cultures and non-Indian educators and patrons engaged in a cross-cultural effort to carry forward ancient Indian decorative arts to shape what became know as traditional modern American Indian painting. But the Studio also became a forum in which its young artists engaged in a cross-cultural search for an American art and identity with their non-Indian educators and patrons. As such, the Studio is a unique social microcosm for studying the nature and formation of the modern American identity of both its young Indian artists and of it non-Indian progenitors. This v study will examine the personal and collective identities that arose through this cross- cultural interaction during the formative years of the Studio – the tenure of its first “guide,” Dorothy Dunn, from 1932-1937. In order to gain a fuller understanding of the concept of identity formation, individual members of that art world are prominently portrayed against the background of BIA education policies concerning indigenous arts and the Studio’s unique historical position in that regard. A selection of 150 Studio paintings is examined to detect ways in which the artist-students chose to depict themselves and their cultures, i.e., their identities. And on that score, the Studio artist- students expressed themselves and their cultures, however marginal they were then and now to American society, and they shared with the non-Indians a new understanding of how they both were Americans. / text
166

Evaluation of repair design on corrosion-damaged steel pipe piles using welded patch plates under compression

Itoh, Yoshito, Kitane, Yasuo, Chen, Xiao 01 August 2011 (has links)
No description available.
167

Sunkieji metalai (Fe, Pb, Cd, Cu) Saimaa ežero (Suomija) hidrosistemos atskirose litoralės zonose / Heavy metals (fe, pb, cd, cu) in separate littoral's zones in the saimaa (finland) lake

Vadakojytė, Sandra 08 September 2009 (has links)
Mūsų gyvenamoji aplinka - gyvoji ir negyvoji gamta yra labai trapi ir pažeidžiama. Tarp daugelio cheminių teršalų ypatingą vietą užima sunkieji metalai. Jie pasižymi ilgalaikiu ir įvairiapusišku toksiniu poveikiu, keliančiu rimtą grėsmę gyvąjai gamtai ir žmonių sveikatai, o jų migracijos aplinkoje kasmet didėja. Medžiaga surinkta Saimos ežero pakrantėse, šalia urbanizacijos centų (Anttola, Astuvansalmi, Ristina, Imatra, Savonlinna, Orijärni, Mikkeli, Puumala) 2004 m. rudenį (spalio, lapkričio mėn.,) ir 2005 m. vasarą (birželio mėn.). Duomenys analizuoti naudojant Eric D. van Hullebusch 2004 m metodika – modifikuota A. Tessier metodika. Sunkiųjų metalų kiekiai nustatyti AAS ir voltimetru. Nustatyta, kad sunkieji metalai skirtinguose substratuose kaupiasi nevienodai, o didžiausias užterštumas jais teritorijose šalia trašų ir plieno fabrikų (Orijarni, Ristina) bei medžio apdirbimo įmonių (Anttola, Mikkeli). / Our living environment – the living nature and inanimate nature are extremely fragile and vulnerable. Among the various chemical pollutants the most prevalent are heavy metals. They are defined as the ones with permanent and various toxic effects, which endangers living nature and human health the most. The migration of this pollutant in the atmosphere is increasing every year. The samples were taken from the Saimaa lakeside near urban centres (Anttola, Astuvansalmi, Ristina, Imatra, Savonlinna, Orijärni, Mikkeli, Puumala ) in autumn 2004 (October, November) and summer 2005 (June). The materials were analyzed by using Eric D. van Hullebusch 2004 method – modified by A. Tessier methods. The quantity of heavy metals was measured by using a voltmeter and AAS. It was diagnosed that heavy metals are accumulating unevenly in the various substratum. And the biggest impurities were found in the territory around manufacturing of the chemical fertilizers and steel factories (Orijarni, Ristina), also wood processing factories(Anttola, Mikkeli).
168

Neutrophils versus Pathogenic Fungi : through the magnifying glass of nutritional immunity

Niemiec, Maria Joanna January 2015 (has links)
Neutrophils are among the first white blood cells recruited to the site of infection once microbial pathogens enter the host organism. At site, they perform a well-orchestrated chain of processes that aims to kill the microbial invader. Most prominent, neutrophils engulf microbes to inactivate them intracellularly, a process called phagocytosis. Alternatively, neutrophils can release neutrophil extracellular traps (NETs). NETs consist of chromatin decorated with antimicrobial effector proteins – a structure that can entangle bacteria and fungi. Neutrophils are crucial during fungal infections. This is reflected in the increased risk of fungal infections resulting of neutropenia. The concept of nutritional immunity describes every infection as a battle for resources. Those are mostly metal trace elements. For a long time, neutrophils were seen as powerful, but “mindless”, killers with a limited set of actions and no transcriptional capacity, but this view is in the flux. In the presented thesis, it was my goal to gain new insights into the interplay of neutrophils and fungi – with special attention to metal-nutritional aspects. We compared human neutrophils lacking the ability to undergo NETosis, due to a non-functional NADPH complex, and neutrophils from the same person that were “cured” by gene therapy. We investigated those NETs and found that their inhibitory activity towards the mold A. nidulans depends on calprotectin, a known zinc-chelator. Considering the high influx of neutrophils, we wanted to unravel the neutrophils’ contribution to the metal milieu at the site of infection and trace element changes resulting from NETosis. By combining synchrotron radiation XRF and ICP-MS, we analyzed the neutrophil metallome and the spatial element distribution in activated neutrophils and NETs. Most strikingly, we found neutrophils to be exceptionally high in Fe and the process of NETosis to be reducing available Zn in the surrounding and the early phagosome, possibly by the formation of Zn-rich vesicles. Using RNA-sequencing, we analyzed the interplay of the C. albicans and neutrophils face-to-face. We dissected their transcriptional profile and revealed a manifold response in neutrophils that include cytokine induction and cellular rearrangement. We further were the firsts to explore the transcriptional response of C. albicans to NETs. Our data indicates a distinct response compared to intact neutrophils or other known stress triggers. Metal homeostasis was affected in Candida in both set-ups. In summary, this thesis provides new insights into the interaction of fungal pathogens with neutrophils and emphasizes the impact of nutritional aspects on this interplay. A deeper understanding of the nutritional immunity during fungal infection might open up new strategies to tackle fungal infections – a growing threat worldwide.
169

Fibre reinforced polymer (FRP) strengthened masonry arch structures

Tao, Yi January 2013 (has links)
Masonry arch bridges have played a significant role in the road and rail transportation network in the world for centuries. They are exposed to damage due to overloading and deterioration caused by environmental actions. In order to reestablish their performance and to prevent their collapse in various hazardous conditions, many of them require strengthening. Fibre reinforced polymer (FRP) systems are increasingly used for repair and strengthening of structures, with particularly widespread application to concrete structures. However, the application of FRP composites to masonry structures is less well established due to the complexity of masonry caused by the material discontinuity. FRP strengthening masonry arch bridges has been even less studied due to the additional complexity arising from the co-existence of the normal interfacial stress and the shear interfacial stress at the curved FRP-to-masonry bondline. This thesis presents an extensive study investigating the behaviour of FRP strengthened masonry bridges. The study started with a laboratory test of a two span masonry arch bridge with sand backfill. A single ring arch bridge was first tested to near failure, and then repaired by bonding FRP into their intrados and tested to failure. It was found that the FRP strengthening not only improved the loading capacity and stiffness of bridge, but also significantly restrained the opening of cracks in the masonry. Shear and peeling debonding of FRP was observed. There have been two common strategies in finite element (FE) modelling of FRP strengthened structures in meso-scale: direct model and interface model. The former is necessary when investigating the detailed bond behaviour but challenges remain due to the difficulties in concrete modelling. A new concrete damage model based on the plastic degradation theory has been developed in this study to study the bond behaviour of FRP strengthened concrete structure. This robust model can successfully capture this bond behaviour and simulate the entire debonding process. A numerical study of masonry arch bridges including the backfill was conducted to study the behaviour of masonry arch bridge. A total of four modelling strategies were examined and compared. Although they all can successfully predict the behaviour of arch, a detailed solid model newly developed in this study is more suitable for modelling both plain masonry and FRP strengthened structures. Finally, a numerical study of bond behaviour and structural response of FRP strengthened masonry arch structures with sand backfill was conducted. In addition to the masonry and backfill, the mixed mode interfacial behaviour was modelled by the aforementioned interface model strategy and investigated in detail to achieve a deeper understanding of the behaviour of FRP strengthened masonry arch structures. The results are in close agreement with test results, and highlight the influence of the key parameters in the structural response to failure and revealed the mechanisms on how the load is transmitted through this complex multi-component structural system.
170

Santa Fe de Nuevo Mexico : a study of a frontier city based on an annotated translation of selected documents (1825-1832) from the Mexican Archives of New Mexico

Parraga, Charlotte Marie Nelson January 1976 (has links)
A study of Santa Fe de Nuevo Mexico (1821-1832) during the Mexican period through the transcription and translation of selected manuscripts in Spanish made available on microfilm by the State of New Mexico Records Center is the primary intent of this research. The dissertation contains photocopies of the microfilm frames, transcriptions and translations of the frames, and annotations to the translations of the eight documents selected. It also contains suggestions about transcribing and translating these manuscripts to help other researchers to unlock the door to the wealth of information contained in these archives.Chapter I provides historical information about Mexico on the eve. of her independence from Spain and relates the structure of the political system to New Mexico, a territory of Mexico.Chapters II-VI contain photocopies of eight documents, the Spanish transcriptions of the documents, and annotated English translations. In these five chapters new or more precise information is gained about persons prominent in Santa Fe, the territory of New Mexico, and the Mexican republic. New light is shed on the activities of Anglo-American traders and trappers involved in affairs in northern Mexico. Especially clarified is the operation of the system of justice and the politics of the municipality and the territory. The functional level of municipal political structure is revealed. The work of the municipal, territorial, and national governments with respect to international trade on the far frontier is shown.Chapter VII sums up the findings revealed in the documents and concludes that the need for more transcriptions and translations of these archives to add to the limited information_ available for the history of New Mexico, 1821-1846, is evident from the richness of this limited selection of the documents.

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