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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.
31

The role of microbes and organic matter in the genesis of complex carbonate facies and lithologies referred to as leopard rock, Sacramento Mountains, New Mexico

Tischler, Keith Louris 30 April 2021 (has links)
The colloquially named leopard rock of the Holder and Laborcita formations (Late Pennsylvanian-Early Permian) is an algal/foraminiferal boundstone that occurs within a cyclic, interfingered, carbonate siliciclastic system in the Sacramento Mountains of southeastern New Mexico) and often accompanies phylloid algal mounds. This project is the first to fully characterize and evaluate the evidence that leopard rock is microbial in origin and assess the potential influence of methane seeps and deltaic organics on its genesis. Characterization of the algal-foraminiferal boundstone revealed a highly variable expression in outcrop based on geolocated photo imagery, hand samples, optical microscopy, and scanning electron microscopy (SEM) data. Leopard rock is interpreted as microbial in origin based upon all features observed in aggregate, particularly upward-oriented concentric gradational laminae and striking clusters of segmented curvilinear cylinders (~1000 nm long). Leopard rock is best described as thrombolytic. A comprehensive categorization into thrombolite types was conducted and field and analytical data were used in creating a geospatial data base. The data was evaluated spatially in ArcMap for co-occurrence, trends, and possible associations within, and between, categorizations and formations. Distribution and associations of dome (1-3 m), small coniform (< 1 m), and planar outcrop structures and thrombolite types reflect a hierarchy of complexity and prevalence that would be expected from a microbial system. An extensive multi-scale feature comparison of potential modern analogues from Australia, the Bahamas, and Canada, in conjunction with contiguous paleo-analogues, support the interpretation of a highly adaptable complex microbial ecosystem. Results were also consistent within the global chemical, biologic, and physical context at the time of deposition. Evidence for methane seep contribution support the plausibility of supplemental microbial energy sources based on modern examples and limited paleo-analogues. Stratigraphic position and a paucity of data do not support a significant role for deltaic bathymetry or organic influx in leopard rock genesis. The results of this study provide robust evidence that leopard rock is a multi-faceted complex microbial thrombolite that displays a continuum of expression not represented by one all-encompassing term and illustrates the value of multi-parameter analyses augmented across time and space using analogues and geospatial software.
32

Diode-Pumped, 2-Micron, Q-Switched Tm:YAG Microchip Laser

Phelps, Charles Dustin 16 May 2011 (has links)
No description available.
33

A Hybrid Ballistic-Diffusive Method to Solve the Frequency Dependent Boltzmann Transport Equation

Allu, Pareekshith 08 June 2016 (has links)
No description available.
34

Experimental and theoretical study of sub-micron aerosol collection efficiency by Laminar Wet-Membrane electrostatic precipitator

Li, Ke January 2005 (has links)
No description available.
35

A Laboratory Investigation of Abatement of Airborne Diesel Particulate Matter Using Water Droplets

Rojas Mendoza, Lucas 07 October 2016 (has links)
The term diesel particulate matter (DPM) is used to refer to the solid phase of diesel exhaust, which is mainly composed of elemental carbon and organic carbon. DPM is generally in the nano-size range (i.e., 10-1,000 nm). Occupational exposure is a health concern, with effects ranging from minor eye and respiratory system irritation to major cardiovascular and pulmonary diseases. Significant progress has been made in reducing DPM emissions by improving fuels, engines and after-treatment technologies. However, the mining industry, in particular, remains challenged to curb exposures in some operations where relatively many diesel engines are working in confined environments with relatively low airflow. Basic theory and a limited amount of prior research reported in the literature suggest that water sprays may be able to scavenge airborne DPM. The goals of the work presented in this thesis were to build an appropriate laboratory set up and to test the efficacy of micron-scale water (or fog) droplets to remove DPM from an air stream. The general experimental approach was to direct diesel exhaust through a chamber where fog drops are generated, and to measure DPM up- and down-stream of the treatment. Initially, fundamental experiments were conducted to explore the effect of the fog drops on the removal of (electrically neutralized) DPM from a dry exhaust stream. Compared to no treatment (i.e., control) and with the use of a diffusion dryer downstream of the fog treatment, the fog improved DPM removal by about 57% by mass and 45% by number density (versus no treatment). Without the use of the diffusion dryer, improvement in DPM removal was about 19% by mass. Analysis of the results suggests that a likely mechanism for the DPM removal in this experimental system is thermal coagulation between DPM and fog droplets, followed by gravitational settling and/or impaction of the droplets with system components. Further tests using raw exhaust (i.e., neither dried nor neutralized) having a higher DPM number density; shorter residence times; additional fogging devices; and no diffusion dryer downstream of the fog treatment were also carried out. These yielded an average overall improvement in DPM mass removal of about 45% attributed to the fog treatment (versus no treatment). The significant increase in DPM removal in these tests compared to the initial test (i.e., 19% removal by mass) cannot be fully explained by differences in residence time or DPM and fog droplet densities. Increased humidity in the system (due to the undried exhaust) may have allowed for a larger mean droplet size, and therefore might explain more rapid settling of DPM-laden droplets. Another possible contributing factor is ambient surface charge of the DPM, which might perhaps result in more efficient attachment between DPM and fog drops and/or increased deposition loses in the system. / Master of Science
36

Avalia??o in vitro e in vivo da citotoxidade e da genotoxicidadde das soldagens a prata, a Tungsten Inert Gas (TIG) e a laser em ortodontia

Rinaldi, Mariana Roennau Lemos 19 January 2017 (has links)
Submitted by Caroline Xavier (caroline.xavier@pucrs.br) on 2017-06-30T14:39:33Z No. of bitstreams: 1 TES_MARIANA_ROENNAU_LEMOS_RINALDI_COMPLETO.pdf: 2232512 bytes, checksum: 72ea5572f7e50b32cdf95dc1dbfe7366 (MD5) / Approved for entry into archive by Caroline Xavier (caroline.xavier@pucrs.br) on 2017-06-30T14:39:42Z (GMT) No. of bitstreams: 1 TES_MARIANA_ROENNAU_LEMOS_RINALDI_COMPLETO.pdf: 2232512 bytes, checksum: 72ea5572f7e50b32cdf95dc1dbfe7366 (MD5) / Made available in DSpace on 2017-06-30T14:39:51Z (GMT). No. of bitstreams: 1 TES_MARIANA_ROENNAU_LEMOS_RINALDI_COMPLETO.pdf: 2232512 bytes, checksum: 72ea5572f7e50b32cdf95dc1dbfe7366 (MD5) Previous issue date: 2017-01-19 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Conselho Nacional de Pesquisa e Desenvolvimento Cient?fico e Tecnol?gico - CNPq / Soldered appliances are widely used in orthodontics and pediatric dentistry. The cytotoxicity and genotoxicity of silver solder and laser welding has already been tested in dentistry. However, little is known about the Tungsten Inert Gas (TIG) welding technique, which uses an electric arc between an electrode and the part to be welded. The aims of this study were to evaluate the cytotoxicity and genotoxicity of silver soldered (silver soldered bands - SSB), laser welded (laser welded bands - LWB), TIG welded (TIG welded bands ? TWB) joints and no soldered/welded bands (NS /WB) in vitro and in vivo. For that, MTT reduction assay was performed in HGF, HaCat, Vero and MRC-5 cell lines. The genotoxicity of the metallic eluates of the joints was determined by comet assay in HGF cells after 3-h treatment. The quantification of Ni, Fe, Cr, Cu, Ag, Zn Cd and Sn in the metallic eluates was performed with inductively coupled plasma mass spectrometry (ICP-MS). Cu, Zn and Ag were the most detected ions in SSB medium samples, and Fe, Cr and Ni in the samples of LWB and TWB. The SSB group induced strong cytotoxicity in all cell lines. NS/WB, LWB and TWB presented a weak cytotoxic induction. In comet assay, SSB group showed a higher damage index and more comets with damage class 3 and 4, compared to the other groups. In the in vivo study, the genotoxic effects on the buccal mucosa cells of children with lingual arches containing silver soldered joints, laser welded joints and without any appliance were accessed by buccal comet assay (BCA) and the buccal micronucleus cytome (BMCyt) assay. The urinary levels of Ni, Cr, Fe, Zn, Cu, Ag, Cd and Sn were investigated through urine samples analyzed by ICP-MS. The results of the study indicate that silver solder and laser welding did not cause genotoxicity in buccal mucosa cell during the period evaluated. The changes of the ions in the urinary contents cannot only be attributed to the appliances. TIG welding may be a promising technique to be applied in orthodontics and deserve be further investigated, as it presented in the in vitro and in vivo tests a low cytotoxic and genotoxic potential. / Aparelhos soldados s?o utilizados amplamente em Ortodontia e Odontopediatria. A citotoxicidade e a genotoxicidade da solda a prata e da soldagem a laser j? foram testadas em Odontologia. No entanto, pouco se sabe sobre a t?cnica de soldagem Tungsten Inert Gas (TIG), que utiliza um arco el?trico entre um eletrodo e a pe?a a ser soldada. Os objetivos deste estudo foram avaliar a citotoxicidade e a genotoxicidade de uni?es soldadas a prata (silver soldered band - SSB), soldadas a laser (laser welded band - LWB), soldadas a TIG (TIG welded band ? TWB) e de an?is n?o soldados (no soldered or welded bands ? NS / WB) in vitro e in vivo. Para isso, o ensaio de redu??o de MTT foi realizado nas linhagens celulares HGF, HaCat, Vero e MRC-5. A genotoxicidade dos eluatos met?licos das ?reas soldadas foi determinada atrav?s do ensaio de cometas em c?lulas HGF ap?s tratamento de 3 horas. A quantifica??o de Ni, Fe, Cr, Cu, Ag, Zn, Cd e Sn nos elu?dos met?licos foi realizada com espectrometria de massa por plasma indutivamente acoplado (ICP-MS). Cu, Zn e Ag foram os ?ons mais detectados nas amostras de meio de bandas soldadas a prata, e Fe, Cr e Ni, nas amostras soldadas a laser e nas soldadas a TIG. O grupo SSB induziu forte citotoxicidade em todas as linhagens celulares. NS / WB, LWB e TWB apresentaram indu??o citot?xica fraca. No ensaio Cometa, o grupo SSB apresentou maior ?ndice de danos e mais cometas com classes de dano 3 e 4, em rela??o aos outros grupos. As uni?es soldadas a TIG, bem como uni?es soldadas a laser mostraram melhor biocompatibilidade. No estudo in vivo, genotoxicidade sobre as c?lulas da mucosa bucal dessas crian?as com arcos linguais contendo uni?es soldadas a prata, uni?es soldadas a laser, e sem qualquer aparelho foram avaliadas pelo ensaio de cometa bucal (BCA) e pelo ensaio de citometria bucal do micron?cleo (BMCyt). Os n?veis urin?rios de Ni, Cr, Fe, Zn, Cu, Ag, Cd e Sn foram investigados atrav?s de amostras de urina analisadas por ICP-MS. Os resultados do estudo indicam que a solda a prata e a soldagem a laser n?o causaram genotoxicidade na mucosa bucal durante o per?odo avaliado. As altera??es dos ?ons no conte?do urin?rio n?o puderam ser unicamente atribu?das aos aparelhos. A soldagem TIG parece ser t?cnica promissora a ser aplicada em ortodontia e merece ser mais investigada, uma vez que apresentou nos testes in vitro e in vivo um baixo potencial citot?xico e genot?xico.
37

Influence of flame retardant additives on the processing characteristics and physical properties of ABS

Seddon, Richard January 2000 (has links)
Antimony trioxide (Sb203) and halogenated additives are used together in flameretarded formulations due to their synergistic retardant properties. A study has been made to determine the effects of adding different grades of Sb203 (dSD particle sizes 0.11 um, 0.52um and 1.31 um) into ABS polymer either alone or with commercial brominated materials (BTBPE, TBBA, DBDPO) and an experimental bromine grade (sDBDPO). The Sb20 3 was added at 4wt% loadings and the bromines at 20wt% loadings. The results consider the influence of the additives on processing, mechanical, morphological and flame retardant properties. All compounds were produced using a twin-screw co-rotating extruder and then an injection moulder was used to mould notched impact (falling weight testing), flexural, LOI and UL-94 flame test bars. Samples of all the compounded formulations were titrated to determine Sb20 3 and Br contents. Fracture surface, morphology, size and dispersion analysis was carried out using both SEM and TEM equipment. Osmium tetroxide (OS04) staining was used to determine relative locations of filler particles and polybutadiene phase. Additions of the different antimony trioxide grades showed that the 0.52um and 1.31 um grades lowered impact energy absorption (-25 to -30%) when added at 4wt% loading. The use of a sub-micron size grade (0.1 um) did not significantly lower impact properties (-3%) and had similarly small effects on the flexural modulus and flexural strength. Additions of the brominated materials had much greater effects causing large reductions in impact properties (-20 to :70%). The presence of the bromines generally increased flexural modulus and lowered flexural strength with the exception of TB BA, which increased both modulus and strength. Compounds containing both 1.31 um Sb203 and bromines suffered a further reduction in impact energies, with the bromine properties dominating. Using the 0.1 um Sb20 3 grade again improved impact and flexural properties compared to the 1.31 um grade. The 0.1 um grade resulted in improvements in fire resistance as measured by the UL-94 properties when used with all bromine grades.
38

METALTEC - JOGO DE EMPRESAS VOLTADO À QUALIFICAÇÃO DE GESTORES DE MICRO E PEQUENAS INDÚSTRIAS / METALTEC BUSINESS GAME FOR QUALIFICATION OF MANAGERS OF MICRON AND SMALL INDUSTRIAS

Rigodanzo, Jonas 30 March 2007 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Business games search to simulate the taking of decisions in enterprise managements also serving as a tool of learning and managemental training. In this work a game of companies based in the characteristics and typical variable of a locksmith shop was developed, that can be a tool of teach-learning and training of enterprise managers. The developed JE simulates the reality of a composed environment of six locksmith shops, being that the controlling of each company will have that to manage all its sectors, since the production until the commercialization of its products, creating and evaluating its strategies. The game was shaped mathematically, programmed in Excel language and applied a group of the PPGEP of the UFSM. The analysis of the results showed that the Metaltec, beyond being an efficient tool in the managemental qualification, also can be used as a teach-learning instrument / Jogos de empresas buscam simular a tomada de decisões em gestões empresariais servindo também como uma ferramenta de aprendizagem e treinamento gerencial. Neste trabalho foi desenvolvido um jogo de empresas baseado nas características e variáveis típicas de uma serralheria, que possa ser uma ferramenta de ensino-aprendizado e treinamento de gestores empresariais. O JE desenvolvido simula a realidade de um ambiente composto de seis serralherias, sendo que os gerentes de cada empresa terão que administrar todos os seus setores, desde a produção até a comercialização de seus produtos, criando e avaliando suas estratégias. O jogo foi modelado matematicamente, programado em linguagem Excel e aplicado a uma turma do PPGEP da UFSM. A análise dos resultados mostrou que o Metaltec, além de ser uma ferramenta eficiente na qualificação gerencial, também pode ser utilizado como um instrumento de ensinoaprendizado
39

Controladoria empresarial : gestão econômica para as micro e pequenas empresas. / CONTROLLING COMPANY: economic management for micro and small enterprises.

Monteiro, José Morais 07 May 2010 (has links)
This study aims to identify the importance of Corporate Controller for the universe of small businesses, as regards the applicability of their tools to improve the process of management. For that was selected micro and small enterprises in the cities of Aracaju and Nossa Senhora do Socorro in Sergipe, in 2009.The methodological procedures applied in the selection of companies have followed the criteria of convenience, using the inductive method, using the application of a questionnaire to managers/owners of the forty selected micro and small businesses who were willing to answer questions. Are presented in this paper some concepts collected from references consolidated in specific books Controller, forming the theoretical basis for comparative work in the same line of observation and the present investigation, adding to the reader more insight into the subject. Possession of the consolidation of the results showed that the tools of the Controller Enterprise (planning, budgeting, financial analysis, information management) are not fully utilized by micro and small companies surveyed - even taking into account constraints on composition and size of those organizations - towards better and efficient results, corroborated with the findings of the authors of similar studies, referenced in this dissertation. However, it is shown that micro and small businesses already have a more integrated vision of what the management and the need for information so that the goals are achieved more consistently and with minimum risk of business. For this, the perception of this evolution is apparent when the managers interviewed said the need to expand knowledge of strategy, controls, financial and managerial accounting, with the specific purpose of taking hands reasons to decide the direction of the enterprise. Thus, consolidates the need to manage micro and small enterprises with professionalism, aimed at reducing the death business segment, since the representation in the economic and social development is considerable, taking into account the contribution of 20 % to GDP (IBGE, 2005) and by volume of 91% of formal employment that is generated by the segment (BNDES, 2005). / O presente trabalho tem por objetivo identificar a importância da Controladoria Empresarial para micro e pequenas empresa no tocante à aplicabilidade das suas ferramentas para aperfeiçoar o processo da gestão. O universo pesquisado são as empresas nos municípios de Aracaju e Nossa Senhora do Socorro, Sergipe, em 2009. Os procedimentos metodológicos aplicados na escolha das empresas seguiram o critério de conveniência, utilizando o método indutivo, com aplicação de questionário aos gestores/proprietários das quarenta micro e pequenas empresas selecionadas, que se dispuseram a responder às questões. São apresentados neste trabalho alguns conceitos coletados a partir de referências consolidadas em livros específicos Controller, formando a base teórica para o trabalho comparativo na mesma linha de observação e do presente inquérito, somando-se ao leitor uma ideia mais clara sobre o assunto. De posse da consolidação dos resultados observou-se que as ferramentas da Controladoria Empresarial (planejamento, orçamento, análise financeira, gestão da informação) não são totalmente utilizadas pelas micro e pequenas empresas pesquisadas - mesmo levando em conta as restrições sobre a composição e o tamanho das organizações - para melhores resultados e eficiência, corroborado com os achados dos autores de estudos semelhantes, referenciados nesta dissertação. No entanto, é mostrado que micro e pequenas empresas já têm uma visão mais integrada da gestão e da necessidade de informação para que os objetivos sejam alcançados de forma mais consistente e com o mínimo de riscos do negócios. Para isso, a percepção dessa evolução é evidente quando os gestores entrevistados afirmam da necessidade de ampliar o conhecimento sobre estratégia, controles, contabilidade financeira e gerencial, com o objetivo específico de ter em mãos fundamentos para decidir os rumos da empresa. Assim, consolida-se a necessidade de gerir as micro e pequenas empresas com profissionalismo, visando a redução do segmento de negócio da morte, pois a representatividade no desenvolvimento econômico e social é considerável, tendo em conta a contribuição de 20% para o PIB (IBGE, 2005) e em volume de 91% dos empregos formais que é gerado pelo segmento (BNDES, 2005).
40

Gas Jet Process for Production of Sub-micron Fibers

Benavides, Rafael Esteban 21 May 2013 (has links)
No description available.

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