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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.
1

Desenvolvimento de cadeira de rodas com nivelamento lateral e longitudinal

Kulman, Cristiano January 2015 (has links)
Pessoas com deficiência motora têm poucas opções na seleção de cadeiras de rodas que atendam suas necessidades de deslocamento, comodidade e segurança para a realização das tarefas da vida diária, principalmente com as tecnologias assistivas disponíveis no Brasil. Com o intuito de auxiliar os cadeirantes, facilitando seus deslocamentos em vias públicas, foi desenvolvido um sistema de simulação numérica e um protótipo para teste de controle de suspensão autonivelante para aplicar em cadeiras de rodas. Baseado nos resultados numéricos obtidos por meio da simulação, a planta de teste de controle foi montada visando ao estudo do desempenho da dinâmica vertical. O sistema de inclinação lateral e frontal é apresentado com o uso de atuadores para controlar os movimentos de arfagem e rolagem de uma cadeira de rodas motorizada. Os sistemas foram expostos a diversas perturbações e os resultados mostram que o controle pode melhorar o conforto e a segurança de cadeirantes em percursos em vias públicas, dependendo da velocidade de aplicação da perturbação. / People with disabilities have little choice go select a wheelchairs which meets most of the displacement, comfort and safety requirements to perform their daily life tasks, particularly amid assistive technologies available in Brazil. In order to aid disabled persons, facilitating wheelchairs displacements on public roads courses, it was designed and developed a numeric simulation model and a prototype for the test of a wheelchair self-leveling suspension control system. Based upon the numeric results obtained from the model simulation, the control test platform was created aiming to ascertain the vertical dynamics performance. The lateral and frontal tilting system is presented, using actuators to control the leveling and rolling movements of a motorized wheelchair. The system underwent a variety of perturbations and the results demonstrate the control may improve comfort and safety for the wheelchairs displacements on public roads courses, depending on the velocity of application of the perturbation.
2

Desenvolvimento de cadeira de rodas com nivelamento lateral e longitudinal

Kulman, Cristiano January 2015 (has links)
Pessoas com deficiência motora têm poucas opções na seleção de cadeiras de rodas que atendam suas necessidades de deslocamento, comodidade e segurança para a realização das tarefas da vida diária, principalmente com as tecnologias assistivas disponíveis no Brasil. Com o intuito de auxiliar os cadeirantes, facilitando seus deslocamentos em vias públicas, foi desenvolvido um sistema de simulação numérica e um protótipo para teste de controle de suspensão autonivelante para aplicar em cadeiras de rodas. Baseado nos resultados numéricos obtidos por meio da simulação, a planta de teste de controle foi montada visando ao estudo do desempenho da dinâmica vertical. O sistema de inclinação lateral e frontal é apresentado com o uso de atuadores para controlar os movimentos de arfagem e rolagem de uma cadeira de rodas motorizada. Os sistemas foram expostos a diversas perturbações e os resultados mostram que o controle pode melhorar o conforto e a segurança de cadeirantes em percursos em vias públicas, dependendo da velocidade de aplicação da perturbação. / People with disabilities have little choice go select a wheelchairs which meets most of the displacement, comfort and safety requirements to perform their daily life tasks, particularly amid assistive technologies available in Brazil. In order to aid disabled persons, facilitating wheelchairs displacements on public roads courses, it was designed and developed a numeric simulation model and a prototype for the test of a wheelchair self-leveling suspension control system. Based upon the numeric results obtained from the model simulation, the control test platform was created aiming to ascertain the vertical dynamics performance. The lateral and frontal tilting system is presented, using actuators to control the leveling and rolling movements of a motorized wheelchair. The system underwent a variety of perturbations and the results demonstrate the control may improve comfort and safety for the wheelchairs displacements on public roads courses, depending on the velocity of application of the perturbation.
3

Desenvolvimento de cadeira de rodas com nivelamento lateral e longitudinal

Kulman, Cristiano January 2015 (has links)
Pessoas com deficiência motora têm poucas opções na seleção de cadeiras de rodas que atendam suas necessidades de deslocamento, comodidade e segurança para a realização das tarefas da vida diária, principalmente com as tecnologias assistivas disponíveis no Brasil. Com o intuito de auxiliar os cadeirantes, facilitando seus deslocamentos em vias públicas, foi desenvolvido um sistema de simulação numérica e um protótipo para teste de controle de suspensão autonivelante para aplicar em cadeiras de rodas. Baseado nos resultados numéricos obtidos por meio da simulação, a planta de teste de controle foi montada visando ao estudo do desempenho da dinâmica vertical. O sistema de inclinação lateral e frontal é apresentado com o uso de atuadores para controlar os movimentos de arfagem e rolagem de uma cadeira de rodas motorizada. Os sistemas foram expostos a diversas perturbações e os resultados mostram que o controle pode melhorar o conforto e a segurança de cadeirantes em percursos em vias públicas, dependendo da velocidade de aplicação da perturbação. / People with disabilities have little choice go select a wheelchairs which meets most of the displacement, comfort and safety requirements to perform their daily life tasks, particularly amid assistive technologies available in Brazil. In order to aid disabled persons, facilitating wheelchairs displacements on public roads courses, it was designed and developed a numeric simulation model and a prototype for the test of a wheelchair self-leveling suspension control system. Based upon the numeric results obtained from the model simulation, the control test platform was created aiming to ascertain the vertical dynamics performance. The lateral and frontal tilting system is presented, using actuators to control the leveling and rolling movements of a motorized wheelchair. The system underwent a variety of perturbations and the results demonstrate the control may improve comfort and safety for the wheelchairs displacements on public roads courses, depending on the velocity of application of the perturbation.
4

Studium vzájemné závislosti objemových změn a napjatosti litých podlahových materiálů / Study of mutual influences of volume changes and internal stresses of flow floor screeds

Mikeš, Vít January 2019 (has links)
This thesis deals with the comparison of volumetric and stress variations in different formulations of cast floor self-leveling screeds during maturation. These changes were measured by several methods. Furthermore, the strength parameters of the test materials were compared. The test specimens were cured in metallic and elastic forms. The microstructure of these samples were monitored by scanning electron microscopy. In conclusion, the suitability of the tested methods for the given type of flooring materials was evaluated.
5

Pojiva a maltové směsi na bázi síranu vápenatého / Binders and Mixtures Based on Calcium Sulfate

Hanáček, Jan January 2016 (has links)
This Diploma Thesis deals with the research and advancements in the field of sulphate binders, especially the anhydrite binder. The theoretical part of the thesis is dedicated to the fundamentals of sulphate binders and anhydrite binders. Its second part also introduces standard requirements for screed coatings together with technological methods of their application. Practical part of the thesis looks at the research and production of anhydrite binder with special emphasis on self-levelling compounds. Various types of plasticizers were used in these compounds and their effectiveness and final product quality are compared.
6

Studie vlivu složení a ošetřování cementových litých potěrů na jejich vlastnosti v rané fázi zrání / Study of the influence of composition and curing of self-leveling cement screeds on their properties in the early stage of maturation

Powetz, Dominik January 2021 (has links)
The diploma thesis deals with the study of the influence of composition and curing of self-leveling cement screeds on their properties in the early stage of maturation. Within this work, various concepts of ensuring the volume stability of cement self-leveling screeds were verified. An anti-shrink additive based on neopentyl glycol and an expansion additive based on hard-burnt lime were used as modifiers. The reduction of plastic and overall shrinkage using various types of liquid membrane-forming compounds was verified on the most volume-stable screed using the optical dilatometry method. The effectiveness of the individual solutions was monitored by continuous measurement of the intensity of evaporation from the screed surface. Subsequently, the effect of membrane-forming compounds on the residual moisture of the cured treated cement self-leveling screed was measured by the carbide method and also the effect of this curing on the adhesion of bonded ceramic tiles.
7

Latexem modifikované cementové kompozity / Latex Modified Cement Composites

Kunc, Michal January 2013 (has links)
The subject of dissertation is a study of physic-mechanical properties and development of self-leveling polymer-cement composite of the ternary binder system PC-CAC-CS modified with chemical additives and polymeric substances. The dissertation systematically describes a four-step optimalization of the composite considering its key properties. Experimental part has been focused on monitoring the impact of composite components on selected final properties. Basic physico-mechanical, structural properties and its relations (compressive strength, porosity, flow abilities, setting times) have been analyzed for deeper understanding of the effects of individual composite components. Methods which quantify the existence of the newly formed hydration product – ettringite (XRD, SEM with EDS, calorimetry, dilatometry) has been chosen as additional study methods on selected combinations. A working prototype of self-leveling polymer-cement composite was successfully developed based on systematic process and using of testing procedures and measuring methods.
8

Vývoj samonivelačního potěru na bázi ternárního pojivého systému / Development of Self-leveling Screed Based on the Ternary Binder System

Běťák, Rostislav January 2016 (has links)
The thesis deals with the development of self-leveling cement screed with compensated shrinkage. It is a ternary binder system with the majority of portland cement, that in the beginning of setting and hardening form an expandable folder ettringite. At first there was a background research of volume changes of hydrating cement composites and methods for measuring these changes. Various sort of expansion additives were also introduced, the main emphasis was on concepts of calculated formation of ettringite, which are typical for self-leveling underlayment. Background research included the issues of formation of ettringite, influences on it’s nucleation and it’s stability. The practical development of the screed began by measuring volume changes of different pastes on a ternary composition. Selected formulations suitable for use are verified together with additives to semi-application tests. After the final configuration of the screed mixture, there was a test in real application of an representative area. Individual formulations were tested in terms of long-term stability of ettringite in dry and moist environments.
9

Vliv modifikujících přísad na dosahované vlastnosti anhydritových maltovin / Influence of Modifying Additives on Achieved Properties of Anhydrite Binders

Ciencialová, Zuzana January 2017 (has links)
This diploma thesis deals with influence of modifying additives on achieved properties of anhydrite binders. The first part is focused on funamentals of anhydrite binders. Ist second part introduces anhydrite under-layments and their standard requirements. The experimental part is dedicated to anhydrite binders modyfyied by plasticizers, while their final properties are compared.
10

Nivellerande vinschsystem till ett vågkraftverk / Self leveling wave power converter winch system

Henningsson, Nils, Sjöberg, Marcus January 2019 (has links)
Detta projekt undersöker konstruktionsmöjligheterna för ett nivellerande vinschsystem till ett vågkraftverk. Kedjekonstruktionen till detta vinschsystem består av länkar med låg tolerans för vrid- och skjuvspänningar och har begränsad böjlighet vilket innebär att vinschsystemet behöver kunna vinkelkompensera för att kedjan inte ska brista. Initialt togs flera koncept fram genom att utvärdera en kravspecifikation och se vilka problem som fanns. Dessa konceptförslag modellerades sedan i Solid Edge och en ny utvärdering gjordes där förslagen utvärderades med avseende på komplexitet, vinkelstyrning, servicebarhet och energiåtgång från styrsystemen. Det förslag som var mest lovande utifrån denna utvärdering består av en vagga i vilken vinschtrumman är upphängd. Lutningen av denna vagga kan styras av två motorer och rotationsrörelsen styrs av ett rälssystem med boggier. Detta förslag vidareutvecklades sedan med hjälp av ANSYS Workbench för att göra konstruktionen lättare, undersöka utmattningsproblem samt se var spänningskoncentrationer uppstår. Från denna analys togs kravprofiler fram för ett antal komponenter som konstruktionen kräver för att kunna drivas. Vidare analys av växel, motor, lager samt energiåtgång kommer krävas för att utvärdera om hurvida konstruktionen är lönsam att bygga. / This project examines the design possiblilites for a self-leveling winch system for a wave power converter. The chain design for this winch consists of links with limited resistance to torsional shear and bending shear stress and with limited bending capabilities, which requires the winch construction to be able to compensate for angular changes to prevent the chain from breaking. Initially several designs were made by evaluating a specification of requirements and by examining the problems facing a winch based wave power converter. These designs were modelled in Solid Edge and evaluated based on complexity, angular steering, servicability and energy requirements for the control systems. The most promising of these designs is composed of a cradle in which the winch drum is mounted. The inclination of the cradle is controlled by electric motors and the rotation is controlled by a rail system with boggies. The design was then further improved upon by utilising ANSYS Workbench to decrease the mass of the design, examining problems related to fatigue failure, and studying stress concentrations. Based on this analysis a set of requirements were specified for a number of key components required for controlling the winch system. Further analysis of the transmission, motor, bearings and energy requirements for the control systems will be needed to evaluate wether the design is profitable to build.

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