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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

A física e os instrumentos musicais construindo significados em uma aula de acústica

Silva, Douglas Krüger da January 2017 (has links)
Este trabalho versa sobre desenvolver a habilidade de “reconhecer características ou propriedades de fenômenos ondulatórios ou oscilatórios, relacionando-os a seus usos em diferentes contextos” (BRASIL, 2009, p.8) de uma forma menos tradicional. O objetivo foi abordar o conteúdo de acústica utilizando instrumentos musicais (violão, guitarra, flauta, xilofone, lira...). A partir de ondas estacionárias em tubos sonoros e cordas vibrantes, foram elucidados os conceitos de altura, intensidade e timbre, relacionando com os conceitos básicos de ondas – frequência, comprimento de onda, amplitude, velocidade de propagação das ondas em cordas de diferentes densidades lineares, entre outros. Também foram trabalhadas notas musicais e conceitos bem básicos de formação de acordes. A proposta foi aplicada com os dois nonos anos de um colégio particular bastante tradicional de Novo Hamburgo: o Colégio Marista Pio XII. Nesta fase final do Ensino Fundamental, o colégio disponibiliza aos seus alunos cinco períodos de Ciências da Natureza, distribuídos em: um de Biologia, dois de Física e dois de Química. A ideia é que fossem trabalhadas Competências e Habilidades comuns aos componentes curriculares, por meio de sequências didáticas. O trabalho foi aplicado em um total de seis encontros, cada um com duração de 50 min. Alguns desses períodos foram dedicados a aulas puramente expositivas, outros deles com aulas expositivas dialogadas, com a utilização de uma espiral de caderno, uma guitarra, um cavaquinho, instrumentos de sopro e do computador, onde interpretamos as frequências fundamentais emitidas pela vibração das cordas e do ar em tubos sonoros com o software Spectrogram1. Como referencial teórico, utilizamos a teoria sócio-interacionista de Vygotsky e alguns conceitos de alfabetização científica. A discussão e o manuseio de instrumentos musicais em pequenos grupos fizeram com que os alunos interagissem entre si e com o professor, favorecendo a construção do conhecimento e a interação de signos. A partir dessas interações aluno - instrumentos musicais, professor - aluno e aluno – aluno, o objetivo era abrir espaço para questionamentos, discussões e reflexões, de maneira que o conhecimento fosse sintetizado por todos. Como referência para o planejamento de ensino, construção do significado das aulas e análise das interações, utilizamos uma ferramenta analítica de Mortimer e Scott (2002). / This work is about developing the ability to "recognize characteristics or properties of wave or oscillatory phenomena, relating them to their uses in different contexts "(BRASIL, 2009, p.8), in a less traditional way. The objective was to approach the content of acoustics using musical instruments (guitar, electric guitar, flute, xylophone, lyre ...). From stationary waves in sound tubes and vibrating strings, concepts of height, intensity and timbre, were elucidated, relating them to the basic concepts of waves - frequency, wavelength, amplitude, velocity of wave propagation in strings of different linear densities, among others. Musical notes and basic concepts of chord formation were also seen. The proposal was applied with two groups of nineth graders from a very traditional private school in Novo Hamburgo: Marista Pio XII school. In this final phase of elementary school, the school offers its students five classes of Science a week, distributed in one of Biology, two of Physics and two of Chemestry. The idea was work with common skills to these curricular components, through didactic sequences. The work was applied out in a total of six classes, each lasting 50 min. Some of these were devoted to purely expository presentation, others with dialogic lectures, with the use of the spiral of a notebook, a guitar, another small kind of guitar, wind instruments and a computer where we interpret the fundamental frequencies emitted by the vibration of the strings and air in sound tubes with the Spectrogram software2. As a theoretical reference, we use Vygotsky's socio-interactionist theory and some concepts of scientific literacy. The discussion and manipulation of musical instruments in small groups led the students to interact with each other and with the teacher, favoring the construction of knowledge and interaction. From these student - musical instruments, teacher - student and student – student interactions, the objective is to open space for questions, discussions and reflections, so that knowledge was synthesized by all. As a reference for teaching planning, construction of meaning and interaction analysis, l we used an analytical tool by Mortimer and Scott (2002).
32

Estudo da corrosão de revestimentos de zinco-ligas obtidos por imersão a quente sobre aços baixo-carbono

Rodrigues, Joel da Silva January 2011 (has links)
O zinco vem sendo utilizado, já há bastante tempo, como revestimento protetor e decorativo para peças metálicas [1]. No entanto, cada vez mais a indústria busca revestimentos protetores que sejam mais resistentes à corrosão, que tenham boas características de soldabilidade, pintabilidade e, principalmente baixo custo. Os métodos mais comuns pelos quais os revestimentos de zinco são aplicados são imersão a quente, eletrodeposição e aspersão térmica. O presente trabalho tem como objetivo caracterizar a morfologia dos revestimentos Galvanized (GI), Galvannealed (GA) e Zn-55Al de zinco obtidos pelo processo de imersão a quente, verificar o comportamento eletroquímico e analisar o comportamento corrosivo dos revestimentos pelas técnicas de Potenciometria e Eletrodo Vibratório (SVET). Os resultados demonstraram que é possível a análise das fases por voltametria em microcélula no revestimento em que as fases foram crescidas, porém, não é possível aplicar a técnica nas diferentes fases formadas nos revestimentos industriais devido à espessura dos revestimentos. Não foi observado influência da luz Ultravioleta-visível na taxa de corrosão dos revestimentos estudados por SVET e esta técnica mostrou-se satisfatória para grandes aumentos e pequenas áreas. As análises por SVET demonstraram a possibilidade de analisar a corrosão localizada em diferentes fases intermetálicas nos revestimentos. / Zinc has been used for quite some time, as decorative and protective coating for metal parts. However, the industry increasingly seeks protective coatings that are more resistant to corrosion, have good weldability characteristics, and especially low cost. The most common methods by which zinc coatings are applied are hot dipping, electroplating and thermal spraying. The present work aims to characterize the morphology of the coatings Galvanized (GI), galvannealed (GA) and Zn-55Al of zinc obtained by hot dip process, check the electrochemical behavior and analyze the behavior of coatings for corrosion techniques of pots and Vibrating electrode (SVET). The results showed that it is possible to analyze the phases by microcell voltammetry in the coating in which the phases were grown, however, is not possible to apply the technique in the different phases formed in industrial coatings due to the thickness of coatings. There was no influence of UV-VIS in the corrosion rate of the coatings studied by SVET and this technique was satisfactory for large and small areas increases. The analysis by SVET demonstrated the possibility of analyzing the localized corrosion in different intermetalic phases in coatings.
33

Estudo da corrosão de revestimentos de zinco-ligas obtidos por imersão a quente sobre aços baixo-carbono

Rodrigues, Joel da Silva January 2011 (has links)
O zinco vem sendo utilizado, já há bastante tempo, como revestimento protetor e decorativo para peças metálicas [1]. No entanto, cada vez mais a indústria busca revestimentos protetores que sejam mais resistentes à corrosão, que tenham boas características de soldabilidade, pintabilidade e, principalmente baixo custo. Os métodos mais comuns pelos quais os revestimentos de zinco são aplicados são imersão a quente, eletrodeposição e aspersão térmica. O presente trabalho tem como objetivo caracterizar a morfologia dos revestimentos Galvanized (GI), Galvannealed (GA) e Zn-55Al de zinco obtidos pelo processo de imersão a quente, verificar o comportamento eletroquímico e analisar o comportamento corrosivo dos revestimentos pelas técnicas de Potenciometria e Eletrodo Vibratório (SVET). Os resultados demonstraram que é possível a análise das fases por voltametria em microcélula no revestimento em que as fases foram crescidas, porém, não é possível aplicar a técnica nas diferentes fases formadas nos revestimentos industriais devido à espessura dos revestimentos. Não foi observado influência da luz Ultravioleta-visível na taxa de corrosão dos revestimentos estudados por SVET e esta técnica mostrou-se satisfatória para grandes aumentos e pequenas áreas. As análises por SVET demonstraram a possibilidade de analisar a corrosão localizada em diferentes fases intermetálicas nos revestimentos. / Zinc has been used for quite some time, as decorative and protective coating for metal parts. However, the industry increasingly seeks protective coatings that are more resistant to corrosion, have good weldability characteristics, and especially low cost. The most common methods by which zinc coatings are applied are hot dipping, electroplating and thermal spraying. The present work aims to characterize the morphology of the coatings Galvanized (GI), galvannealed (GA) and Zn-55Al of zinc obtained by hot dip process, check the electrochemical behavior and analyze the behavior of coatings for corrosion techniques of pots and Vibrating electrode (SVET). The results showed that it is possible to analyze the phases by microcell voltammetry in the coating in which the phases were grown, however, is not possible to apply the technique in the different phases formed in industrial coatings due to the thickness of coatings. There was no influence of UV-VIS in the corrosion rate of the coatings studied by SVET and this technique was satisfactory for large and small areas increases. The analysis by SVET demonstrated the possibility of analyzing the localized corrosion in different intermetalic phases in coatings.
34

Avaliação da vibração mecânica com o uso de aparelhos de massagem vibratórios comerciais / Evaluation of mechanical vibration with the use of vibratin massage equipment business

Leonardo Serafim dos Santos 12 December 2009 (has links)
A massagem tradicional tem sido auxiliada com o uso de acessórios convencionais e eletro-eletrônicos, onde estes produtos trabalham por intermédio de equipamentos programados por micro-controladores que atuam de forma eficiente, atuando na qualidade de vida do ser humano. O objetivo principal deste trabalho foi comparar os níveis de freqüência (Hz) da almofada vibratória com os da esteira vibratória tendo como referência a massagem tradicional e a vibroterapia, analisando por meio de pesquisa quantitativa o desenvolvimento e fabricação de aparelhos vibratórios. Não é do nosso conhecimento estudos avaliando tais parâmetros nesta área, pois a comparação e detalhamento de freqüências tem o parecer inédito neste aspecto. Foram feitos dez medições de freqüências com uso de tacômetro e acelerômetro para as quatro funções na almofada vibratória e, cinco medições para as quinze funções na esteira vibratória onde os valores de intensidades mínimo e máximo foram comparados às normas para garantir o bem estar no momento da utilização. Para os aparelhos vibratórios utilizados nesse trabalho, foram encontrados valores de freqüências de 7,33 a 116,35 Hz, onde na massagem tradicional a variação é de 10 a 20 Hz, para as normas de fabricação é de 1 a 100 Hz para corpo inteiro, 5 a 1.250 Hz para as transmitidas à mão e 100 a 300 Hz citados em trabalhos acadêmicos. Portanto, ambos os aparelhos vibratórios apresentaram resultados de valores de freqüência dentro dos limites definidos pelos autores de trabalhos acadêmicos, assim como as normas de fabricação. / The traditional massage has been assisted with use of conventional accessories and electric-electronics, where this product works for intermediary of equipment programmed by microcontrollers that act of efficient form acting in the quality of life of the human being. The mean goal of this study was to compare the levels of frequency (Hz) vibration of the pad with the belt vibration with reference to traditional massage and vibrotherapy, analyzing by quantitative research development and manufacturing of vibration equipments. Not the best of our knowledge studies evaluating these parameters in this area, because the comparison of frequencies and detail has unpublished opinion in this regard. Ten measurements were made of frequencies using tachometer and accelerometer for the four functions in vibrating cushion and, five measurements for the fifteen functions in vibrating mat where the values of minimum and maximum of intensities were compared to standards to ensure the well-being at use. For the vibration equipments used in this study, we found values of frequencies from 7,33 to 116,35 Hz, where the change in traditional massage is 10 to 20 Hz, for the standards of manufacture is from 1 to 100 Hz for the whole body , 5 to 1.250 Hz vibration to the hands and 100 Hz to 300 cited in academic work. Therefore, both devices performed vibration frequency of values within the limits defined by the authors of academic works and the manufacture standards.
35

Ramanova spektroskopie biologicky aktivních látek a protinádorových léčiv / Raman spectroscopy of biologically active species and antitumor drugs

Třeštíková, Liběna January 2009 (has links)
SERRS spektra of biological materials are very komplex, because they consist of signals from all molecules present in cells. In this text are presented SERRS spektra of antitumor drugs and its komplex with DNA. Experimental are rated on doxorubicin and another antitumor druha and on study of theirs potential by treatment for tumors. Doxorubicin belong to clase antracycline antibiotics and is used for stop of tumor cells reproduction. Scientists found still new ways, new drugs. SERRS is one of possibilities for study of this drugs and theirs interaction with DNA.
36

Vibrofluidized Bed Drying Of Citrus Processing Residue For Byproduct Recovery

Roe, Eric A 14 November 2003 (has links)
Approximately 44% of the citrus that is processed becomes processing residue. The residue consists of the non-juice components of a citrus fruit, primarily peel and pulp, and is recovered by conversion to animal feed. The material is hygroscopic, agglomerating, has a wide particle size distribution, and must be carefully dried to avoid thermal damage to nutrients and flavors. This dissertation evaluates the possibility of utilizing a vibrofluidized bed dryer for citrus processing residue. Results demonstrate that it is possible to overcome the agglomeration difficulties associated with this material, offering an economically viable alternative processing methodology. To properly analyze this proposed system, a benchtop vibrofluidized bed dryer was designed, constructed and instrumented. Vibrofluidization and batch drying trials were conducted and analyzed. An economic evaluation of the proposed process was undertaken. Two mathematical models of the drying process were developed and validated. Characteristics that describe the vibrofluidized bed drying of the residue were determined. The conditions that facilitated fluidization were: 1) A particle size distribution of the dried residue that was lognormal, had a geometric mean diameter, dgw, of 3.829 mm, and a geometric standard deviation, Sgw, of 2.49x10-07 mm. 2) A vibrational acceleration, Aω2/g, of 2.54. 3) A minimum vibrofluidization velocity, Umvf, of 4.2 cm/s. The controlling mechanism of the falling rate period was determined to be diffusion, with an effective diffusion coefficient, Deff, of 2.85x10-5 cm/s, and critical moisture content, Mc, of 30%. Economic evaluation of the proposed method has a payback period of 4.34 years, and an estimated processing cost of $33 per ton of dried material. Models were developed based on bed hydrodynamics and three-phase drying kinetics, and thin-layer drying. Both models accurately predicted the drying curves. The three-phase kinetic drying model solved a series of simultaneous equations, and differential equations, based on moisture and enthalpy balances. This complex model successfully predicted the bed hydrodynamic properties and serves to facilitate scale-up, design, and bed configuration investigations. For the thin-layer drying model, the drying constants, K & N, for Page’s equation were determined as a function of bed temperature. This computationally simple, single-parameter model would serve process control algorithms.
37

Resonant Ferromagnetic Absorption and Magnetic Characterization of Spintronic Materials

O'Dell, Ryan Andrew January 2018 (has links)
No description available.
38

Wet Electrostatic Precipitator, Increasing the Efficiency of Collecting Dust Particlesthrough Vibrating Precipitator Analysis

Lutfullaeva, Anbara 02 June 2020 (has links)
No description available.
39

Design of a Vibrational Energy Harvesting System for Wireless Sensor Nodes

Wilson, Aaron M. E. 11 1900 (has links)
McMaster University in conjunction with an industrial partner has been designing wireless vibrational condition monitoring sensors for implementation on a vibrating screening machine used in mining applications. A limitation with the current sensor design is their dependency on battery power. In order for the sensors to provide real-time continuous streaming of acceleration data, an alternate power supply was required outside of traditional sources such as batteries or wired power. This thesis outlines the research and development of a power system that harvests the kinetic vibrational energy of a mining screen and converts it into electrical energy for use by a wireless sensor node. During development, multiple prototypes were built and evaluated under laboratory conditions. The core concept of the system is an eccentric pendulum mass excited by the external vibrations of the screening machine used to drive a stepper motor generator. The major design obstacle of the project was how to get the system to self initiate. Both a mechanical and an electrical solution were developed to solve this concern. The final prototype design is fully autonomous, able to react to the start up or shut-down of a screening machine, while also providing a continuous power supply to a wireless vibrational analysis sensor as tested in the lab. With minor optimization, this prototype can be turned into a commercial product for industrial implementation and sale. / Thesis / Master of Applied Science (MASc)
40

Filiform-Like Corrosion Mechanism on Magnesium-Aluminum and Magnesium-Aluminum-Zinc Alloys

Cano, Zachary P. 06 1900 (has links)
The filiform-like corrosion of Magnesium (Mg) alloys AZ31B and AM30 was investigated with electrochemical and microanalytical techniques. Potentiodynamic polarization testing and scanning vibrating electrode technique (SVET) measurements confirmed the “differential electrocatalytic” mechanism previously reported for filiform and filiform-like corrosion on pure Mg and AZ31B. Transmission electron microscopy (TEM) and Auger electron spectroscopy (AES) revealed that the MgO corrosion filaments on both alloys were likely a product of the direct reaction of Mg and water (H2O), responsible for the rapid hydrogen (H2) evolution observed at the propagating corrosion fronts. TEM analysis also revealed through-thickness cracks and noble intermetallic particles within the corrosion filaments and noble metal enrichment at the corrosion filament/metal interfaces, which were proposed to play significant roles in the cathodic activation of the corrosion filaments. The higher susceptibility of the AZ31B alloy to cathodic activation versus AM30 suggested that Zinc (Zn) has a detrimental effect on the resistance of Magnesium-Aluminum-Zinc (Mg-Al-Zn) alloys to filiform and filiform-like corrosion. / Thesis / Master of Applied Science (MASc)

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