• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 15
  • 12
  • 4
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 45
  • 8
  • 7
  • 6
  • 6
  • 5
  • 5
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 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

The correction of astigmatism and field curvature in telescopic systems

Mouroulis, P. January 1981 (has links)
No description available.
2

Developing a QFD-based design-integrated structural analysis methodology

Mobasseri, Seyed Omid January 2012 (has links)
Design of the mechanical components greatly depends on their expected structural performances. In modern design applications these performances are quantified by computer-based analysis and occasionally confirmed by experimental measurements or theoretical calculations. The dependency of the mechanical product to the structural analysis process is more significant under the product’s multi-functionality aspect that requires analyses for a variety of Variable Input Parameters, to obtain various structural responses and against more than one failure or design criterion. Structural analysis is known as the expert field, which requires an upfront investment and facilitation to be implemented in commercial design environment. On the other hand, the product design process is a systematic and sequential activity that put the designer in the central role of decision making. Lack of mutual understanding between these two disciplines reduces the efficiency of the structural analysis for design. This research aims to develop an integrated methodology to embed the structural analysis in the design process. The proposed methodology in this research combines the benefits of state-of-the-art approaches, early simulation and Validation and Verification practice, towards the specified aim. Moreover the novelty of the proposed methodology is in creative implication of Quality Function Deployment method to include the product’s multi-functionality aspect. The QFD-Based Design Integrated Structural Analysis methodology produces a reliable platform to increase the efficiency of the structural analysis process for product design purpose. The application of this methodology is examined through an industrial case-study for the telescopic cantilever boom, as it appears in Access platforms, and Cranes products. Findings of the case-study create a reliable account for the structural performance in early stages of the design, and ensure the functionality of the proposed methodology.
3

Teleskopická zdvihací plošina s lanovým pohonem / Telescopic lifting platform with a rope drive

Suran, Dávid January 2016 (has links)
The thesis deals with construction design Telescopic lifting platform with rope drive. It includes a technical report with analysis and calculation of the proposed solution and description of options using different types of drives in the theatrical equipment.
4

Analysis of Davit Structure with a Telescopic Arm of a Ship

Chen, Hong-long 20 July 2007 (has links)
Abstract Maritime transportation is important to national development because of Taiwan is in surrounding seas region. Therefore it is necessary that this research aimed to safety of the crane transportation system. This research investigated davit structure with a telescopic arm of a ship by means of the static analysis and modal analysis. To achieve the purpose, the researcher used the computer-aided design software Solidworks to set up this structure model. After that, he used finite element analysis software ANSYS to analyze the data. This research simulated in three situations. In static analysis, the researcher found the maximum displacement, the maximum von Mises stress and factors for safety of the structure in 16 dimensional sets in 53¢X of inclination at the davit with the telescopic arm being the shortest. After that, he discussed its tendency situation. In addition, he also checked the original structure in 53¢X of inclination at the davit with the telescopic arm being the longest and horizontal at the davit with the telescopic arm being the longest, respectively. In modal analysis, the researcher found natural frequencies and vibration shapes of the original structure. The structure had good vibration-proof ability and the resonance effect possibility not to be high. Generally, the researcher hoped that this study could provide helpful references for the relevant davit structure designers in the future.
5

Converging Elements in the Development of Late Seventeenth-Century Disciplinary Astronomy: Instrumentation, Education, and the Hevelius-Hooke Controversy

Saridakis, Voula 26 November 2001 (has links)
In this dissertation, I examine astronomical practice in the second half of the seventeenth century by analyzing the nature of observation and instrumentation within an institutional and social context. I argue that astronomical practice was transformed by the convergence of several overlapping factors including the deployment of new instruments, the mathematical and astronomical education of practitioners, the gradual assimilation of new ideas, and the rise of scientific societies and networks. More specifically, I argue that the 1670's controversy between Johannes Hevelius and Robert Hooke and the ensuing debate that involved a larger circle of practitioners, helped establish a new foundation for the discipline of astronomy. In forcing practitioners to take sides, the controversy prompted them to define the precise nature of astronomical practice as well as the necessary qualifications for its practitioners. In Chapter 1, I discuss sixteenth and seventeenth-century astronomical instruments, and I provide a history of instrumentation from the use of positional measuring instruments in the late sixteenth century to the more widespread use of micrometers and telescopically-mounted positional measuring instruments in the late seventeenth century. Proceeding from the instruments to the people involved, in Chapters 2 and 3 I discuss the mathematical and astronomical community of the late sixteenth to late seventeenth centuries. The "community" included those individuals working both within and outside the universities. In Chapter 4, I discuss the Hevelius-Hooke controversy over the relative merits of naked-eye versus telescopic sights as the watershed in positional astronomy that defined the role of astronomers, shaped their methods of observation, and directed future research. In the final chapter of this study, Chapter 5, I discuss the work of Cassini at the Paris Observatory and Flamsteed at the Greenwich Observatory, and how their efforts were shaped by the Hevelius-Hooke controversy. / Ph. D.
6

Design stavebního nakladače / Design of front loader

Groch, Luboš January 2012 (has links)
In my thesis I aim on design of front loader, which is most adapted to human operator. Human needs, repairman needs and requirements of civilization are fully respected. Loader is designed for near future.
7

Utveckling av rattstång med övre teleskopfunktion / Development of steering column with upper telescopic function

Josefsson, Johannes, Lundberg, Marcus January 2009 (has links)
<p>I denna rapport redogör projektgruppen för resultatet i kursen examensarbete 15hp (C-nivå) utfört på maskiningenjörsprogrammet, inriktning produktutveckling och design, vid Jönköpings Tekniska Högskola.</p><p>Examensarbetet har utförts i samarbete med Kongsberg Power Product Systems AB i Ljungsarp. Syftet var att utveckla en ny typ av övre teleskopfunktion till Kongsbergs modulsystem för ställbara rattstänger.</p><p>Utgångspunkten i projektet var att skapa en mer ergonomisk förarmiljö, något som Kongsbergs kunder och marknaden för långsamtgående fordon allt mer efterfrågar. Kraven som ställts på projektet bestod i största del av axiella och radiella krafter som konstruktionen skulle klara av, samt den axiella förlängningen av rattstången.</p><p>För att strukturera arbetet har en produktutvecklingsmetod från boken The Mechanical Design Process av David G. Ullman använts. Dessa metoder har använts i genomförandefasen för att leda fram till resultatet.</p><p>Projektet har resulterat i ett koncept som löser Kongsbergs krav på förbättrad förarergonomi.</p> / <p>In this report the project team describes the outcome of the course degree project 15 ECTS (C level) performed at the program of mechanical engineering, targeted product development and design, at Jönköping University.</p><p>The degree project has been carried out in cooperation with Kongsberg Power Products Systems AB in Ljungsarp. The aim was to develop a new type of upper telescopic function to the Kongsberg modular system for adjustable steering columns.</p><p>The starting point of the project was to create a more ergonomic driver's environment, as Kongsberg’s customers and the market for slow vehicles are increasingly demanding.</p><p>The requirements placed on the project consisted in the main part of the forces that construction would meet, and the axial extension of the steering column.</p><p>To structure the work a product development methodology from the book The Mechanical Design Process by David G. Ullman has been used.</p><p>The project has resulted in a concept that solves Kongsberg's demands for improved driver ergonomics.</p>
8

Robô contínuo telescópico para tarefas em alturas elevadas. / Telescopic continuum robot for tasks at high positions.

Cores, Vitor Finotto 12 August 2009 (has links)
Observando-se as diversas aplicações de robôs na área de serviços é possível perceber uma crescente busca por manipulação de ferramentas em lugares elevados utilizando dispositivos robóticos, visto que tais tarefas exigem a utilização de diversos equipamentos de segurança e apresentam um alto risco à presença humana. Os exemplos mais comuns desse tipo de tarefa são: inspeção de: máquinas de grande porte, tanques de armazenamento, silos, postes, linhas de transmissão e distribuição de energia elétrica, etc. Com o intuito de aplicar robôs a essas tarefas, e consequentemente aumentar a segurança e eficiência dessas operações, foi realizado, primeiramente neste trabalho, um estudo sobre as classes de robôs manipuladores existentes. Para tanto adotou-se uma classificação que separa os robôs de acordo com o número de juntas, o que gera uma divisão em três diferentes grupos, robôs discretos, robôs do tipo serpente e robôs contínuos. Ao analisar as três classes, observa-se que os robôs contínuos possuem mais graus de liberdade que os outros grupos, apresentando como estrutura uma coluna vertebral continuamente deformável, que em oposição aos tradicionais manipuladores robóticos elo/junta/elo, possuem mecanismos mais simplificados, controle menos complexo devido ao menor número de atuadores e podem interagir com obstáculos encontrados em seu ambiente sem criar grandes forças de contato. Ao utilizar configurações extrínsecas, ou seja, posicionando os atuadores fora da estrutura do robô, e transmitindo o movimento utilizando cabos, é possível construir robôs com alta isolação elétrica, o que é de grande utilidade para operações que envolvem tarefas nas proximidades de redes elétricas de alta tensão. Apesar das diversas vantagens, não foram encontradas na literatura aplicações de robôs contínuos na realização de tarefas em alturas elevadas. Levando em consideração as vantagens oferecidas pelos robôs contínuos, este trabalho propõe o estudo e a aplicação de um robô do tipo contínuo que possua uma arquitetura mais adequada para realizar trabalhos a alturas elevadas. Com o intuito de demonstrar as vantagens oferecidas por essa arquitetura, será realizado um estudo de caso no qual o objeto a ser inspecionado são as cruzetas de madeira em postes de distribuição de energia elétrica. Em uma segunda etapa, elabora-se o projeto mecânico do robô contínuo proposto, onde são detalhados os mecanismos propostos e são feitas simulações utilizando o método dos elementos finitos para analisar o comportamento da estrutura quando submetida a carregamentos. Em uma terceira etapa, adotando-se uma estratégia de controle seqüencial é elaborado o projeto de controle. Em uma ultima etapa, com o intuito de analisar o funcionamento do robô é construído um protótipo, com o qual são feitos os testes. / Among several applications of robots in the service field, it is possible to percept an increasing interest in manipulate tools in higher positions using automatic devices, due to the fact that such activities are high risked operations and demands the use of several safety equipments. The most common examples of this kind of activity are the inspection of machines, silos, electrical distribution poles, etc. With the aim of apply robots to these activities and increase the safety and efficiency in these operations, as a first step in this work is done the study of different kinds of manipulators. Adopting a classification based on the number of joints, it is possible to separate robots in three different classes: discrete robots, snake-like robots and continuum robots. By analyzing these classes, it is possible to say that continuum robots have more degrees of freedom than the robots of others groups; Compared with the classic discrete robots, continuum robots have simplified mechanisms, simpler control scheme due to the small number of actuators and, in the case of an obstacle, they can contour the obstacle without generating high contact forces. By positioning the actuators out of the robot structure and transferring the motion using cables, i.e., adopting an extrinsic actuation, it is possible to build continuum robots with high electric insulation that is important in applications in which the robot must work near of an electrical distribution network. Despite these advantages, no previous works concerning the use of continuum robots to work in higher positions were found in the literature. Considering the advantages offered by continuum robots, this work proposes a study and application of a continuum robot that uses a more suitable architecture to work in higher positions. Aiming to demonstrate the advantages provided by this architecture, It will be used a case study, in which, the object to be inspected is the wood cross-arms of an electrical poles used in the electrical distribution networks. In a second step, it is done the mechanical project of the robot, where the proposed mechanisms are explained and structural simulations using the finite element method are performed in order to analyze how the structure would react to loads. In a third step, by adopting a strategy of sequential control, it is done the control project. In the last step, with the aim of analyze the robot in practical situation, a prototype is built, which is used to perform the tests.
9

Failure criteria for tearing of telescoping wrinkles

Ahmed, Arman U 06 1900 (has links)
An ever increasing demand to exploit oil and natural gas reserves has significantly increased extraction activities even in the remotest regions of the Arctic and sub-Arctic regions of the Canadian North. Steel pipelines are the most efficient mode for transporting and distributing these resources. These pipelines, particularly buried in cold region, often subjected to extreme geo-environmental conditions, where significant inelastic deformation may occur resulting in localized wrinkles. Under continued deformation, there is a possibility of excessive cross-sectional deformation at wrinkle locations, eventually leading to fracture or damage in the pipe wall jeopardizing pipeline safety and integrity . Prior research indicated that occurrence of fracture in pipe wrinkle is rare under monotonic load-deformation process. However, a recent field fracture was observed within the wrinkle location of an energy pipeline. Similar failure mode was observed in a laboratory specimen at the University of Alberta. Both field and laboratory observations had indicated that the final failure was a “tearing” failure at the fold of the telescopic wrinkles resulting from monotonic application of axial load not aligned with pipe axis. This research program was designed to study this specific failure mode and to develop design tool for pipeline engineers. This research started with examining the failed field and test specimens. A preliminary investigation was carried out using nonlinear finite element (FE) model to simulate test and field behaviour. Numerical results have indicated that even under monotonic loading, significant strain reversals could occur at the wrinkle fold . Presence of these strain reversals was proposed as the preliminary failure criterion responsible for this unique failure mechanism. In next phase, a full-scale ‘pipe-wrinkling’ test program was carried out concurrent to this research to better understand the loading condition responsible for this type of failure. Results of this test program have shown the presence of tearing fracture or rupture in the pipe walls of several of test specimens. A series of FE analyses was then carried out to predict and verify the behaviour of these test specimens. After successful simulation of the test behaviour, further numerical analyses were carried out using tension coupon model developed herein to simulate the material behaviour using the material test data and hence to formulate the limiting conditions in terms of critical strain responsible for the tearing failure. Based on these numerical results, a double criterion  ‘Strain Reversal’ and ‘Critical Equivalent Plastic Strain Limit’, were proposed to predict tearing fracture of wrinkled pipe under monotonic loading. Results of these numerical analyses have demonstrated that the proposed criteria predict this failure mode with reasonable accuracy. In the final phase of this research, a parametric study was carried out to consider the effect of different parameters on failure modes of wrinkled pipe. Results of this parametric study describe the range of parameters under which the tearing mechanism can/may exhibit. / Structural Engineering
10

Utveckling av rattstång med övre teleskopfunktion / Development of steering column with upper telescopic function

Josefsson, Johannes, Lundberg, Marcus January 2009 (has links)
I denna rapport redogör projektgruppen för resultatet i kursen examensarbete 15hp (C-nivå) utfört på maskiningenjörsprogrammet, inriktning produktutveckling och design, vid Jönköpings Tekniska Högskola. Examensarbetet har utförts i samarbete med Kongsberg Power Product Systems AB i Ljungsarp. Syftet var att utveckla en ny typ av övre teleskopfunktion till Kongsbergs modulsystem för ställbara rattstänger. Utgångspunkten i projektet var att skapa en mer ergonomisk förarmiljö, något som Kongsbergs kunder och marknaden för långsamtgående fordon allt mer efterfrågar. Kraven som ställts på projektet bestod i största del av axiella och radiella krafter som konstruktionen skulle klara av, samt den axiella förlängningen av rattstången. För att strukturera arbetet har en produktutvecklingsmetod från boken The Mechanical Design Process av David G. Ullman använts. Dessa metoder har använts i genomförandefasen för att leda fram till resultatet. Projektet har resulterat i ett koncept som löser Kongsbergs krav på förbättrad förarergonomi. / In this report the project team describes the outcome of the course degree project 15 ECTS (C level) performed at the program of mechanical engineering, targeted product development and design, at Jönköping University. The degree project has been carried out in cooperation with Kongsberg Power Products Systems AB in Ljungsarp. The aim was to develop a new type of upper telescopic function to the Kongsberg modular system for adjustable steering columns. The starting point of the project was to create a more ergonomic driver's environment, as Kongsberg’s customers and the market for slow vehicles are increasingly demanding. The requirements placed on the project consisted in the main part of the forces that construction would meet, and the axial extension of the steering column. To structure the work a product development methodology from the book The Mechanical Design Process by David G. Ullman has been used. The project has resulted in a concept that solves Kongsberg's demands for improved driver ergonomics.

Page generated in 0.0589 seconds