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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.
441

Projeto e montagem de um sistema para lingotamento contínuo sob agitação eletromagnética para ligas de Al-Si / Design and assembly of a continuous casting system under a electromagnetic stirring to Al-Si alloys

Beil, Wendel Leme, 1974- 27 August 2018 (has links)
Orientador: Eugênio José Zoqui / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-27T12:27:50Z (GMT). No. of bitstreams: 1 Beil_WendelLeme_M.pdf: 9441091 bytes, checksum: a79e3096e6d5e36f55c442eaac25c9ea (MD5) Previous issue date: 2015 / Resumo: O presente trabalho visa desenvolver um projeto e executar a montagem e teste de um sistema de lingotamento contínuo, aprimorado com o uso da agitação eletromagnética, para a fabricação de lingotes de ligas de Al-Si com estrutura refinada de grãos. Durante seu desenvolvimento, o projeto almejou o estabelecimento de parâmetros construtivos do equipamento, bem como os parâmetros de processamento para obtenção dos lingotes. Os parâmetros estudados foram a altura de metal fundido na cavidade do molde, velocidade de lingotamento, temperatura de vazamento e rugosidade da cavidade do molde. Após serem determinados os parâmetros construtivos e de processamento, procedeu-se a obtenção dos lingotes propriamente ditos, em duas condições de refrigeração: refrigeração primária, somente no molde metálico, e refrigeração primária e secundária (com sistema de refrigeração na saída do lingote). Para cada uma dessas condições foram obtidos lingotes sem a aplicação do campo magnético e, sob a agitação eletromagnética a 1500 W com o campo magnético variando de 12 a 20 Gauss e 3000 W com o campo magnético variando de 22 a 38 Gauss. De posse dos lingotes seguiu-se a caracterização microestrutural por meio de análise metalográfica convencional e análise metalográfica por polarização de imagem, que buscou verificar a eficiência do sistema no refino de grãos. A condição de otimização alcançada sugere a fabricação de ligas de Al-Si nas seguintes condições: a temperatura de vazamento adotada foi de 800 ºC, rugosidade da cavidade do molde de Ra = 0,06 µm, velocidade de lingotamento 3 mm/s e altura de metal fundido na cavidade do molde de 15 a 20 mm, em que alcançou-se o tamanho de grãos com 178 µm e espaçamento interdendrítico de 125 µm, com uma potência de 1500 W e campo magnético de 12 a 20 Gauss / Abstract: This work aims to develop a project and implement the assembly and testing of a continuous casting system , enhanced with the use of electromagnetic stirring to manufacture ingots of Al-Si alloys with refined grain structure. During its development the project aspired to establishing constructive parameters of the equipment, as well as the establishment of the processing parameters for obtain ingots. The parameters studied were: the molten metal height in the mould cavity, the casting speed, the casting temperature, and the roughness of the mould cavity. After setting the construction and processing parameters were obtained obtain the ingots in two cooling conditions: primary cooling (considering only the metal mould), and primary and secondary cooling (with the ingot cooling system in the output). For each of these conditions were obtained ingots without applying the electromagnetic field and with electromagnetic stirring in 1500 W with a variation of electromagnetic field between 12 to 20 Gauss, and 3000 W with a variation eletrocmagnetic field between 22 to 38 Gauss. In possession of ingots followed the microstructural characterization by conventional metallographic analysis and metallographic analysis by polarization imaging, which aims to evaluate the efficiency of the grain refining system. The process optimized condition suggests the manufacturing Al-Si alloy in the following conditions: the pouring temperature was 800 °C, the mould cavity surface roughness Ra = 0.06 µm, casting speed is 3mm/s and molten metal height in the mould cavity of 15 to 20 mm where grain size up to 180 µm and interdendritic spacing of 125 µm, with a power of 1500 W and electromagnetic field of 12 to 20 Gauss / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica
442

Dokumentation av IT-system med continuous delivery

Harnevik, Fredrik January 2020 (has links)
Dokumentation av IT-system har enligt tidigare studier ofta brister i form av att den exempelvis inte uppdateras, den kan vara ofullständig och otydlig eller vara på fel nivå för de intressenter som finns. Continuous delivery (CD) är ett sätt att hantera leverans av mjukvara vilket är baserat på kontinuerlig integration av ny och uppdaterad kod till en gemensam kodbas där automatiska tester körs så snart koden är integrerad. Dess förespråkare menar att det leder till bättre mjukvara som kan levereras snabbare och med mindre fel. Uppsatsens syfte är att undersöka hur organisationer kan arbeta med dokumentation när de hanterar leveranser med CD. Studien är en explorativ och kvalitativ designstudie för att ta fram en artefakt i form av riktlinjer för att företa dokumentationen. Den artefakt som tagits fram har utvärderats i workshops av systemutvecklare från den medverkande organisationen. Studiens slutsatser är att det går att arbeta med dokumentation av IT-system på ett sätt som arbetar bort de problem som finns samt att leverera mjukvara med CD inte nödvändigtvis påverkar dokumentationen så mycket.
443

HIGH THROUGHPUT EXPERIMENTATION WITH DESORPTION ELECTROSPRAY IONIZATION MASS SPECTROMETRY TO GUIDE CONTINUOUS-FLOW SYNTHESIS

Harrison S Ewan (7900775) 21 November 2019 (has links)
<div>The present work seeks to use high throughput experimentation (HTE) to guide chemical synthesis. We demonstrate the use of an HTE system utilizing a robotic liquid handler to prepare arrays of reactions and print them onto a surface to be analyzed by desorption electrospray ionization mass spectrometry (DESI-MS) as a tool to guide reaction optimization, synthetic route selection, and reaction discovery. DESI-MS was employed as a high throughput experimentation tool to provide qualitative predictions of the outcome of a reaction, so that vast regions of chemical reactivity space may be more rapidly explored and areas of optimal efficiency identified. This work is part of a larger effort to accelerate reaction optimization to enable the rapid development of continuous-flow syntheses of small molecules in high yield. In the present iteration of this system, reactions are scaled up from these nanogram surface printed reactions to milligram scale microfluidic reactions, where more detailed analysis and further optimization may be performed. In the earliest iterations of this screening system prior to the use of DESI, the initial screening reactions were performed in electrospray (ESI) droplets and leidenfrost droplets before scaling up to microfluidic reactions which were analyzed by ESI-MS. The insights from this combined droplet and microfluidic screening/rapid ESI-MS analysis approach, helped guide the synthesis of diazepam. The system was further refined to by the use of liquid handling robots and DESI-MS analysis, greatly accelerating the overall pace of screening. In order to build confidence in this approach, however, it is necessary to establish a robust predictive connection between reactions performed under analogous DESI-MS, batch, and microfluidic reaction conditions. To achieve this goal, we first explored the potential of high throughput DESI-MS experiments to identify trends in reactivity based on chemical structure, solvent, temperature, and stoichiometry that are consistent across these platforms. While DESI-MS narrowed the scope of possibilities for reaction</div><div>13</div><div>selection with some parameters such as solvent, others like stoichiometry and temperature still required further optimization under continuous synthesis conditions. With our increased confidence in DESI-MS HTE, we proceeded to explore it’s application to rapidly evaluate large sets of aldol reactions of triacetic acid lactone (TAL), a compound well studied for use as a bio-based platform molecule that may be converted to a range of useful commodity chemicals, agrochemicals, and advanced pharmaceutical intermediates. Our DESI-MS HTE screening technique was used to rapidly evaluate known reactions of triacetic acid lactone, in an effort to accelerate reaction discovery with platform chemicals. Our rapid experimentation system, when applied to reaction discovery in this manner, may help to shorten the time scale of platform chemical development.</div>
444

Wireless Wearable Sensor to Characterize Respiratory Behaviors

January 2020 (has links)
abstract: Respiratory behavior provides effective information to characterize lung functionality, including respiratory rate, respiratory profile, and respiratory volume. Current methods have limited capabilities of continuous characterization of respiratory behavior and are primarily targeting the measurement of respiratory rate, which has relatively less value in clinical application. In this dissertation, a wireless wearable sensor on a paper substrate is developed to continuously characterize respiratory behavior and deliver clinically relevant parameters, contributing to asthma control. Based on the anatomical analysis and experimental results, the optimum site for the wireless wearable sensor is on the midway of the xiphoid process and the costal margin, corresponding to the abdomen-apposed rib cage. At the wearing site, the linear strain change during respiration is measured and converted to lung volume by the wireless wearable sensor utilizing a distance-elapsed ultrasound. An on-board low-power Bluetooth module transmits the temporal lung volume change to a smartphone, where a custom-programmed app computes to show the clinically relevant parameters, such as forced vital capacity (FVC) and forced expiratory volume delivered in the first second (FEV1) and the FEV1/FVC ratio. Enhanced by a simple, yet effective machine-learning algorithm, a system consisting of two wireless wearable sensors accurately extracts respiratory features and classifies the respiratory behavior within four postures among different subjects, demonstrating that the respiratory behaviors are individual- and posture-dependent contributing to monitoring the posture-related respiratory diseases. The continuous and accurate monitoring of respiratory behaviors can track the respiratory disorders and diseases' progression for timely and objective approaches for control and management. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2020
445

PROCESSING-STRUCTURE-PROPERTY RELATIONSHIPS INCO-CONTINUOUS POLYMER BLENDS AND COMPOSITES

Guo, Molin 07 September 2020 (has links)
No description available.
446

Řadič postupného nasazení software nad platformou Kubernetes / Kubernetes Canary Deployment Controller

Malina, Peter January 2019 (has links)
Potreba dodania hodnoty uživatelom každodočne rastie na kompetitívnom trhu IT. Agilita a DevOps sa stávajú kritickými aspektami pre vývoj software, vyhľadávajúci nástroje ktoré podporujú agilnú kultúru. Softwarové projekty v agilnej kultúre majú častú tendenciu zaoberať sa stratégiami nasadenia ktoré redukujú risk nasadenia nových zmien do existujúceho systému. A však, prostredia určené pre vývoj a testovanie sa takmer vždy odlišujú od produkčných. Využitie primeranej stratégie nasadenie ako canary zlepšuje celkovú stabilitu systému testovaním nových zmien na malej vzorke produkčnej prevádzky. Bolo vykonaných niekoľko experimentov pre dôkaz, že stratégia canary môže pozitívne ovplyvniť stabilitu nasadení a redukovať risk ktorý prinášajú nové zmeny.
447

Implementace součástí programu neustálého zlepšování / Implementation of Continual Improvement Program Parts

Fraňková, Magda January 2009 (has links)
This graduation theses is focus to implementation of CIP-World (continuous improvement program) and to fullfilment of requirements of Star Power Factory audit in Siemen Nízkonapěťová spínací technika Trutnov, s.r.o. company.
448

Design of assessment tasks in grade seven mathematics

Mnisi, Thabo Moses January 2013 (has links)
The study reports on two Grade 7 mathematics teachers’ assessment practices in an attempt to identify the knowledge and competencies that they have and use in designing Grade 7 mathematics tasks and how they provide feedback to the learners. These two Grade 7 mathematics teachers were selected from schools that had consistently good results despite disabling teaching conditions such as large and under–resourced classes. Data was collected through semi-structured interviews with the teachers to assess their knowledge and practice of continuous assessment. Classroom observation and analysis of teacher’s portfolio and learners’ exercise books were undertaken to triangulate data on teachers’ practices and interview protocols. A mathematics taxonomy referred to as MATH taxonomy was used as a framework to evaluate teacher mathematics assessment tasks in grade 7 lessons. Classroom observations focused on how the two teachers planned and implemented their Grade 7 mathematics lessons with emphasis on the assessment procedures. The results of the study showed that the two teachers had rudimentary knowledge and understanding of continuous assessment and its practice. Both teachers failed to demonstrate knowledge or ability with any knowledge taxonomy including the MATH taxonomy in designing (or selecting) their mathematics assessment tasks in Grade 7. The mathematics assessment tasks frequently used by the teachers were sourced from the school textbooks, and these were found to be mainly recall-type questions involving routine procedures, and which according to the math taxonomy are classified as low order thinking assessment tasks. Furthermore both teachers presented feedback to their learners in superficial ways that would not necessarily assist the latter to improve in their learning methods and the former in their teaching methods. The education implications of the findings of this study are discussed. / Dissertation (MEd)--University of Pretoria, 2013. / gm2014 / Science, Mathematics and Technology Education / unrestricted
449

Environmental fluctuations modulate microbial competition, diversity, and persistence

Mancuso, Christopher Patrick 19 May 2020 (has links)
Fitness, the competitive advantage of an organism or gene, is the basis for adaptation and the emergence of complexity in biology. Competitive advantage is contextual, as it is affected by environmental pressures and ecological interactions. To enable experiments with complex environmental dynamics, we developed eVOLVER, a novel platform for scalable programmable continuous culture. In this thesis, we apply eVOLVER to interrogate how competitive outcomes between strains change according to environmental conditions. Using soil microbe communities as a model ecological system, we tuned dilution rate and frequency across 112 cultures in eVOLVER and observed replicable changes in composition and diversity. Our experimental results challenge intuition about the relationship between diversity and disturbance. In collaborative work, we compared different models of competitive growth in simulations. A Monod growth model outperforms Lotka-Volterra and linear consumer resource models at predicting the effect of varying dilution profiles on microbial diversity. We hypothesize that trade-offs in growth rate and nutritional requirements (r/K) create distinct niches which permit coexistence at certain mortality rates, but collapse under others. These findings suggest a mechanism that potentially affects diversity-disturbance relationships, and confirm that temporal fluctuations can promote diversity. In separate studies, we apply these methods and concepts to 1) study selection on a genome-scale library in yeast under conditions of fluctuating temperature stress in eVOLVER and 2) evaluate the persistence of engineered microbial spores relative to native strains in different “real-world” environments (e.g. soil) and perturbations. Broadly, this dissertation demonstrates that the combination of next-generation sequencing and scalable programmable culture technologies finally enables the types of experiments needed to test decades of theoretical work in ecology and evolution. / 2021-05-18T00:00:00Z
450

Multifractal Analysis of Parabolic Rational Maps

Byrne, Jesse William 08 1900 (has links)
The investigation of the multifractal spectrum of the equilibrium measure for a parabolic rational map with a Lipschitz continuous potential, φ, which satisfies sup φ < P(φ) x∈J(T) is conducted. More specifically, the multifractal spectrum or spectrum of singularities, f(α) is studied.

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