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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

Tradução comentada de artigos de Stephen Gray (1966-1736) e reprodução de experimentos históricos com materiais acessíveis : subsídios para o ensino de eletricidade /

Boss, Sergio Luiz Bragatto. January 2011 (has links)
Resumo: A literatura específica da área de Ensino de Ciências tem apresentado importantes discussões sobre dificuldades de aprendizagem e compreensão de conceitos científicos pelos alunos. Diante disso, já há algum tempo a História da Ciência tem sido defendida enquanto elemento que pode auxiliar no processo de ensino-aprendizagem dos conceitos científicos. Apesar do potencial educacional que é atribuído à História da Ciência e do esforço que tem sido feito para aproximá-la da educação científica, existem algumas barreiras que podem inviabilizar o sucesso desta aproximação impedindo que ela cumpra, efetivamente, o seu papel frente ao Ensino de Ciências. Dentre as barreiras que a literatura aponta, destacamos a falta de material histórico de qualidades e acessível a alunos e professores que possa subsidiar práticas metodológicas em sala de aula. No bojo dessa escassez está a falta de traduções de fontes primárias para o português. Tendo em vista tal contexto, este trabalho de doutorado tem como objetivo geral de fazer a tradução comentada dos dez artigos de Stephen Gray (1666-1736) relacionados à eletricidade. Dos dez textos traduzidos, nove foram publicados no periódico Philosophical Transactions of the Royal Society e uma carta foi publicada por Chipman (1954). Como objetivo específico propomos elaborar um conjunto de elementos, os quais denominamos de recursos didáticos, que possam ampliar o acesso de professores e alunos ao conteúdo das traduções: comentários em forma de notas; figuras; experimentos históricos com material de baixo custo; breve biografia do autor do texto traduzido; linha do tempo do período em questão; introdução geral ao texto. Stephen Gray foi um importante, porém mencionado, pesquisador do início do Século XVIII. Seu trabalho trouxe importantes... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The specific literature related to Science Education has presented important discussion on the difficulties faced by students in the learning and understanging of scientific concepts. In this context, some time ago the History of Science has been advocated as an element that can facilitate the process of teaching scientific conceps. Despite the educational potential that is assigned to the History of Science and the effort that has been done to bring it closer to Science Education, there are some barriers that can hinder the sucess of this approach, preventing it to fulfill effectively its role with the teaching of science. Among the barriers pointed out by the literature, we emphasize the lack of historical material with quality and accessible to students and teachers that can subsidize methodological practices in the classroom. Among this shortage of historical material, there is a lack of Portuguese translations of primary sources. Given this context, the main goal of this PhD work is the translation into Portuguese of the ten articles of Stephen Gray (1666-1736) related to electricity. Of the ten translated texts, nine were published in the Philosophical Transactions of the Royal Society and a letter was published by Chipman (1954). The specific goal of this thesis is to prepare a set of elements, which we will call teaching resources, that can expand the accesss of the content of the translations to teachers and students: comments as notes; figures; historical experiments with law-cost material; brief biography of the author of the tranlated text; timeline of the period; and a general introduction to the text. Stephen Gray was an important, though rarely mentioned, researcher at the beginning of the Eighteenth Century. His work has brought important contributions to the field of electricity. Some of his... (Complete abstract click electronic access below) / Orientador: André Koch Torres de Assis / Coorientador: João José Caluzi / Banca: Marcos Cesar Danhoni Neves / Banca: Lizete Maria Orquiza de Carvalho / Banca: Shirley Takeco Gobara / Banca: Moacir Pereira de Souza Filho / Doutor
32

Desenvolvimento e avaliação experimental de ejetores de baixo custo / Development and experimental evaluation of low cost ejectors

Lima Neto, Iran Eduardo 28 June 2001 (has links)
Os ejetores são dispositivos largamente utilizados nos mais diversos ramos da engenharia. Este trabalho foi desenvolvido no Laboratório de Hidráulica da Escola de Engenharia de São Carlos - USP, com o propósito de avaliar experimental e teoricamente o desempenho de ejetores de baixo custo, projetados e construídos em conexões do tipo \"tê\" de PVC, onde água foi utilizada tanto como fluido prmário como secundário. Os ensaios foram realizados com ejetores de diâmetros nominais de 25 mm e de 32 mm com relações de áreas de 0,25; 0,35 e 0,53. Foi utilizado também, para cada diâmetro, um ejetor mais compacto e sem câmara de mistura, com a relação de áreas de valor intermediário. Os ejetores comuns apresentaram rendimentos mais elevados do que os compactos, sendo o máximo de 30,52% alcançado com o ejetor de 25 mm e relação de áreas de 0,35. Os coeficientes de perda de carga em cada componente dos ejetores foram ajustados através de um modelo unidimensional. O fenômeno da cavitação também foi analisado. Os resultados mostraram que os ejetores de baixo custo apresentam funcionamento similar ao dos ejetores convencionais. / The ejectors are devices widely used in the most several branches of the engineering. This work was developed at the Laboratory of Hydraulics of the School of Engineering of São Carlos - SP, with the purpose of evaluating experimentally and theoretically the acting of low cost ejectors, projected and built in connections of the type \"tee\" of PVC, where water was used as much primary fluid as secondary. The experiments were accomplished with ejectors of nominal diameters of 25 mm and of 32 mm with area ratio of 0,25; 0,35 and 0,53. It was also used, for each diameter, a more compact ejector and without mixing chamber, with the area ratio of intermediate value. The common ejectors presented higher efficiencies than the compact ones, being the maximum of 30,52% reached with the ejector of 25 mm and area ratio of 0,35. The coefficients of head loss in each component of the ejectors were adjusted through one-dimensional model. The phenomenon of the cavitation was also analyzed. The results showed that the low cost ejectors present similar operation to the conventional ejectors.
33

Modification of a Biosand Water Filter for Household Treatment of High Turbidity Water

Moran, Paul Aaron 05 May 2010 (has links)
One billion of the poorest people in the world today do not have access to improved drinking water. Without treatment, fecal contamination results in an overwhelming disease burden. A long term best practice solution will take decades to implement. In the meantime, approximately 5 million children under five die each year from gastrointestinal diseases. This tragedy can be alleviated by household water treatment. Household Water Treatment and safe Storage systems (HWTS) provide an interim solution. While many low cost and simple technologies exist, none of them are effective against high suspended solids concentrations (>50 NTU). Previous short-term field research by others has considered modifying a BioSand water Filter (BSF), to include pretreatment through an upper sand layer in order to extend the run cycle of the primary filter, enabling complete ripening to occur. In this research program, one control and twelve configurations of modified filters were setup in the laboratory. Water was chemically conditioned to provide worst case scenario treatment by adjusting pH, TDS, and particle dispersion. Sample water was passed through each filter daily, and monitored for DO, turbidity, flow rate, and E. coli concentrations. The results indicate that pretreatment is not necessarily beneficial under all water quality conditions. Recommendations include a description of conditions under which the modification may be beneficial, and optimized pretreatment design criteria. Regardless of water quality conditions, it was found that changing the operational guidelines for filter use can significantly improve treatment efficiency, without complicating the filter design. Design guidelines for an unmodified filter coupled with operational guidelines are provided, in order to obtain sufficient quantities of the best possible water quality under high turbidity conditions. This will enable the BSF to be used in high turbidity conditions and still significantly improve the drinking water quality. It is hoped that this will decrease the disease burden and loss of life in many of the world's poorest communities.
34

Developing a proof of principle 3D-printed lab-on-a-disc assay platform

Tothill, Alexander M. January 2017 (has links)
A 3D-printed microfluidic lab-on-a-disc (LOAD) device was designed and manufactured using a low cost ( ̃£1600) consumer grade fused deposition modelling (FDM) Ultimaker 2+ 3D printer with imbedded microfluidic channels 1 mm wide, 400 μm depth and with a volumetric capacity of approximate 23 μl. FDM printers are not typically used, or are capable, of producing the fine detailed structures required for microfluidic fabrication; in addition 3D-printed objects can suffer from poor optical transparency. However, in this work, imbedded microfluidic channels were produced and the optical transparency of the device was improved though manufacture optimisation to such a point that optical colourimetric assays can be performed in a microfluidic cuvette device with sample path length of 500 μm and volumetric capacity of 190 μl. When acetone vapour treatment was used, it was possible to improve transparency of plastic samples by up to a further 30%. The LOAD device is capable of being spun using an unmodified optical disc drive (ODD), demonstrating the centrifugation based separation of plasma from whole blood in a low-cost FDM 3D-printed microfluidic LOAD device. A cholesterol assay and glucose assay was developed and optimised using cholesterol oxidase (ChOx) or glucose oxidase (GlOx) respectively and horseradish peroxidase (HRP) for the oxidative coupling of chromotropic acid (CTA) and 4-aminoantipyrine (AAP). This produced a blue quinoneimine dye with a broad absorbance peaking at 590 nm for the quantification of cholesterol/glucose in solution. The colourimetric enzymatic cascade assays were developed for use within low-cost FDM 3D-printed microfluidic devices to demonstrate the capabilities and functionality of the devices. For comparison, the assay was run in standard 96 well plates with a commercial plate reader. The results demonstrated that the quantification of 0-10 mM glucose solution using a 3D-printed microfluidic optical device had a performance comparable to a plate reader assay; glucose assay in whole blood samples R2 = 0.96.
35

Desenvolvimento e avaliação experimental de ejetores de baixo custo / Development and experimental evaluation of low cost ejectors

Iran Eduardo Lima Neto 28 June 2001 (has links)
Os ejetores são dispositivos largamente utilizados nos mais diversos ramos da engenharia. Este trabalho foi desenvolvido no Laboratório de Hidráulica da Escola de Engenharia de São Carlos - USP, com o propósito de avaliar experimental e teoricamente o desempenho de ejetores de baixo custo, projetados e construídos em conexões do tipo \"tê\" de PVC, onde água foi utilizada tanto como fluido prmário como secundário. Os ensaios foram realizados com ejetores de diâmetros nominais de 25 mm e de 32 mm com relações de áreas de 0,25; 0,35 e 0,53. Foi utilizado também, para cada diâmetro, um ejetor mais compacto e sem câmara de mistura, com a relação de áreas de valor intermediário. Os ejetores comuns apresentaram rendimentos mais elevados do que os compactos, sendo o máximo de 30,52% alcançado com o ejetor de 25 mm e relação de áreas de 0,35. Os coeficientes de perda de carga em cada componente dos ejetores foram ajustados através de um modelo unidimensional. O fenômeno da cavitação também foi analisado. Os resultados mostraram que os ejetores de baixo custo apresentam funcionamento similar ao dos ejetores convencionais. / The ejectors are devices widely used in the most several branches of the engineering. This work was developed at the Laboratory of Hydraulics of the School of Engineering of São Carlos - SP, with the purpose of evaluating experimentally and theoretically the acting of low cost ejectors, projected and built in connections of the type \"tee\" of PVC, where water was used as much primary fluid as secondary. The experiments were accomplished with ejectors of nominal diameters of 25 mm and of 32 mm with area ratio of 0,25; 0,35 and 0,53. It was also used, for each diameter, a more compact ejector and without mixing chamber, with the area ratio of intermediate value. The common ejectors presented higher efficiencies than the compact ones, being the maximum of 30,52% reached with the ejector of 25 mm and area ratio of 0,35. The coefficients of head loss in each component of the ejectors were adjusted through one-dimensional model. The phenomenon of the cavitation was also analyzed. The results showed that the low cost ejectors present similar operation to the conventional ejectors.
36

A Low-Cost Custom Knee Brace Via Smartphone Photogrammetry

Miguel, Olivier 25 January 2019 (has links)
This thesis provided the foundational work for a low-cost three-dimensional (3D) printed custom knee brace. Specifically, the objective was to research, develop and implement a novel workflow aimed to be easy to use and available to anyone who has access to a smartphone camera and 3D printing services. The developed workflow was used to manufacture two prototypes which proved valuable in the design iterations. As a result, an improved hinge was designed which has increased mechanical strength. Additionally, a smartphone photogrammetry validation study was included which provided preliminary results on the accuracy and precision. This novel measurement method has the potential to require little training and could be disseminated through video instructions posted online. The intention is to enable the patient to collect their own “3D scan” with the help of a friend or family member, effectively removing the need to book an appointment simply for collecting custom measurements. Lastly, it would allow the clinician to focus all their time on clinically relevant design tasks such as checking alignment, fit and comfort, which could all potentially be improved by adopting such digital methods. The ultimate vision for this work is to enable manufacturing of better custom knee braces at a reduce cost which are easily accessible for low-income populations.
37

Applications of optical manipulation for low cost implementation, beam shaping and biophysical force measurements

McDonald, Craig January 2017 (has links)
There are a growing variety of research fields requiring non-contact micro- manipulation. An increasing number of these fields are turning to optical tweezers as a solution, owing to their high spatial and temporal resolution. Optical tweezers have the ability to quantitively exert and measure forces on the piconewton scale, a convenient force scale for soft biological materials, and are hugely versatile due to the wide assortment of beam shaping techniques that can be employed. The work in this thesis can be broadly divided into two main themes: that quantifying the optical trapping forces in shaped beams; and bringing control and simplification of complex systems to non-expert users who may utilise optical tweezers as part of interdisciplinary collaborations. Static beam shaping is used to generate a conically refracted optical trap and the trapping properties are characterised. It is shown that trapping in the lower Raman spot gives full, 3D gradient trapping, while the upper Raman spot allows for particle guiding due to its levitation properties. Particles in the Lloyd/Poggendorff rings experience a lower trap stiffness than particles in the lower Raman spot but benefit from rotational control. Dynamic beam shaping techniques are exploited for the simplification of complex systems through the development and testing of the HoloHands program. This software allows a holographic optical tweezers experiment to be controlled by gestures that are detected by a Microsoft Kinect. Multiple particle manipulation is demonstrated, as well as a calibration of the tweezers system. Application of trapping forces is demonstrated through an examination of integrin – ligand bond strength. Both wild type effector T cells and those with a kindlin-3 binding site mutation similar to that found in neutrophils from Leukocyte Adhesion Deficiency sufferers are investigated. Through the use of back focal plane interferometry, a bond rupture force of (17.9 ± 0.6) pN at a force loading rate of (30 ± 4) pN/s, was measured for single integrins expressed on wild type cells. As expected, a significant drop in rupture force of bonds was found for mutated cells, with a measured rupture force of (10.1 ± 0.9) pN at the same pulling rate. Therefore, kindlin-3 binding to the cytoplasmic tail of the β2-tail directly affects bond strength of single integrin-ligand bonds. An experimental system for studying these cells under more physiologically relevant conditions is also presented. Additionally, a low-cost optical micromanipulation system that makes use of simple microfabricated components coupled to a smartphone camera for imaging is proposed and demonstrated. Through the layering of hanging droplets of polydimethylsiloxane (PDMS) on microscope coverslips, lenses capable of optical trapping are created. Combination of PDMS with Sudan II dye led to the fabrication of long pass filters. An extension of this low-cost system into the life sciences is proposed through the adaptive use of bubble wrap, which allows for the culturing of cells in a chamber compatible with optical trapping.
38

Low Cost Scanning Arrays

Livadaru, Matilda Gabriela 22 June 2018 (has links)
Over the past decades, phased arrays have played a significant role in the development of modern radar and communication systems. The availability of printed circuit technology and ease of integration with microwave components, as well as the development of low profile and low weight approaches, have also played an important role in their conformal adaptation. However, fabrication costs remain prohibitive for many emergent platforms, including 5G base stations and autonomous vehicles, when compared to a conventional mechanically steered passive array. Therefore, cost reductions in the fabrication and integration of modern phased arrays are essential to their adaptation for many upcoming commercial applications. Indeed, although phased array design methods are well-understood, even for wideband and wide-angle scanning applications, their fabrication is still based on high-cost, low-yield printed circuit technology. With this in mind, this dissertation focuses on a new planar aperture topology and low-cost techniques for phased array methodologies. The first part of the thesis presents new fabrication advancements using commercially available multi-layered printed circuit technologies. We discuss methods for low cost fabrication while still maintaining performance and design constraints for planar array apertures. The second part of the dissertation presents a novel Integrated Planar Array (IPA) at S-Band and discusses dramatic cost reductions for multi-function radar applications. Performance and cost benefits are presented, and fabrication techniques to exploit an emerging class of high-speed digital laminates are discussed. These are compatible with high-volume, high-yield production, while reducing aperture cost by 75% when compared to conventional approaches. Performance of a planar array employing a pin-fed dual-polarized antenna element with active VSWR Overall, this dissertation addresses several manufacturing and performance challenges in realizing affordable planar phased arrays using low cost fabrication without performance compromise. As commercial interest in phased array technology is anticipated to grow, the proposed approaches for phased array design and fabrication will enable quick turnaround times for mainstream adoption.
39

Sydney's caravan parks: Community and closure

Wedgwood, Kate, Built Environment, Faculty of Built Environment, UNSW January 2009 (has links)
Although typically associated with the provision of low-cost holiday accommodation, for over 30 years city-based caravan parks have provided an unrecognised source of permanent housing to the lower end of the market. Due to their often dilapidated condition and the demographic profile of their residents, caravan parks do not fit within the Australian housing ideal and are often considered enclaves of despondency. Residents are subject to harsh stereotypes and are often referred to as ??trailer trash?? ?? a tag which originated in the USA. However the reality is that caravan parks provide significant social benefits and are unique living environments for their permanent residents. This research involved an extensive discourse analysis complemented by in-depth interviews with caravan park residents and industry stakeholders, which found that the residential experience is typically based on solidarity, companionship, pride and a true sense of belonging. As urban land prices in Australia have increased exponentially and the footprints of its capital cities continue to grow, large parcels of under-developed land accommodating caravan parks have become ??land banks?? ripe for redevelopment. While it is the park owner??s prerogative to maximise profit, individuals and households are being displaced with little or no compensation, to make way for more lucrative land uses. With deficiencies in the public housing system and the failure of the housing market to provide an adequate level of low-cost accommodation, caravan park residents face an uncertain future, even homelessness. However, the understated impact of this trend is the social implications which affect some of the community??s most vulnerable members. The loss of home, community disintegration and feelings of insecurity appear to be disregarded in the planning process, and this trend seems certain to continue with a lack of responsibility and strategic vision by the government. For this reason, the continued closure of Sydney??s caravan parks should not be tolerated for the purpose of land profiteering. A comprehensive all-of-government and industry response is urgently required to address the threats to Sydney??s caravan parks and to develop mitigation strategies aimed at reducing the resultant outcomes for their vulnerable residents.
40

The achievement of sustainable competitive advantage through relationship marketing

Jamart, Thierry, Kupka, Stefanie January 2009 (has links)
<p>Nowadays, the European airline market is characterized by two major different airline business models; the full service airlines and the low cost airlines. Secondary, appeared for the first time in 1985 in form of the Irish low cost carrier Ryanair. In recent days, the European low cost market stands out through its growth potential and high competitiveness. Therefore, startup companies aiming to join the wave of success as well as insolvency of newly established airlines are part of the daily occurrence. The challenge, that established low cost airlines are faced with, is to create competitive advantages against new entrants and direct competitors under the circumstances of environmental changes. In addition to the described problem a model was developed in order to picture the situation. This paper aims to provide an answer to the specific question: How do low cost airlines use relationship marketing in order to enhance, maintain and attract new customers? The second step is to figure out how those tools affect the airlines generic strategy. The purpose of this study is to find out how low cost airlines in Europe deal with tools of relationship marketing and what are the effects those tools have on generic strategies. This thesis is based on a case study within the European low cost airlines market, with a special focus on three airlines: Ryanair, EasyJet and Air Berlin. These questions are addressed using information obtained in interviews with respondents from the airlines that were recently conducted in Brussels and Bremen by personal interviews and additionally by telephone interviews and email contact. The results show that relationship marketing tools are used in a different extent by the airlines. The authors could not find evidence that using relationship marketing tools is the single solution to compete more successfully than without. It is further argued by the authors that RM is just one aspect strengthening the generic strategy in order to gain sustainable competitive advantage.</p>

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