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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

Extending the measurement range of an optical surface profiler.

Cochran, Eugene Rowland, III. January 1988 (has links)
This dissertation investigates a method for extending the measurement range of an optical surface profiling instrument. The instrument examined in these experiments is a computer-controlled phase-modulated interference microscope. Because of its ability to measure surfaces with a high degree of vertical resolution as well as excellent lateral resolution, this instrument is one of the most favorable candidates for determining the microtopography of optical surfaces. However, the data acquired by the instrument are restricted to a finite lateral and vertical range. To overcome this restriction, the feasibility of a new testing technique is explored. By overlapping a series of collinear profiles the limited field of view of this instrument can be increased and profiles that contain longer surface wavelengths can be examined. This dissertation also presents a method to augment both the vertical and horizontal dynamic range of the surface profiler by combining multiple subapertures and two-wavelength techniques. The theory, algorithms, error sources, and limitations encountered when concatenating a number of profiles are presented. In particular, the effects of accumulated piston and tilt errors on a measurement are explored. Some practical considerations for implementation and integration into an existing system are presented. Experimental findings and results of Monte Carlo simulations are also studied to explain the effects of random noise, lateral position errors, and defocus across the CCD array on measurement results. These results indicate the extent to which the field of view of the profiler may be augmented. A review of current methods of measuring surface topography is included, to provide for a more coherent text, along with a summary of pertinent measurement parameters for surface characterization. This work concludes with recommendations for future work that would make subaperture-testing techniques more reliable for measuring the microsurface structure of a material over an extended region.
2

Deeply Superficial

Searcy, Christopher 16 September 2013 (has links)
Through an exploration of the architectural aperture, this thesis seeks to abandon a representational understanding of the image and restore a more performative one. Architecture’s imageability – its capacity to create vivid and operative mental images – oscillates between two tendencies: the need to reflect a contemporary world view, and the desire to produce altogether new ways of seeing. Architecture’s history could be summarized as an endless cycle of the latter’s ossification into the former. In general, our recent paradigm is in a rut of representation. Whether we are championing the discipline’s political efficacy or acquiescing to the forces of capital, the architectural image is either pushed so far into the background as to be insignificant, or it is fetishized into an icon. This thesis defines a performative image as one which engages the user in a conceptual flip from the experience of space to the perception of an image, where depth momentarily snaps into perceived flatness. By examining the architectural aperture and focusing it onto the quotidian aspects of our lives – collecting and collapsing the world into fragmentary and simultaneous images – Deeply Superficial seeks to blur the distinction between subject and object, and collapse the relationship between publicity and privacy.
3

On Diagonal Acts of Monoids

Gilmour, Andrew James January 2007 (has links)
In this paper we discuss what is known so far about diagonal acts of monoids. The first results that will be discussed comprise an overview of some work done on determining whether or not the diagonal act can be finitely generated or cyclic when looking at specific classes of monoids. This has been a topic of interest to a handful of semigroup theorists over the past seven years. We then move on to discuss some results pertaining to flatness properties of diagonal acts. The theory of flatness properties of acts over monoids has been of major interest over the past two decades, but so far there are no papers published on this subject that relate specifically to diagonal acts. We attempt to shed some light on this topic as well as present some new problems.
4

On Diagonal Acts of Monoids

Gilmour, Andrew James January 2007 (has links)
In this paper we discuss what is known so far about diagonal acts of monoids. The first results that will be discussed comprise an overview of some work done on determining whether or not the diagonal act can be finitely generated or cyclic when looking at specific classes of monoids. This has been a topic of interest to a handful of semigroup theorists over the past seven years. We then move on to discuss some results pertaining to flatness properties of diagonal acts. The theory of flatness properties of acts over monoids has been of major interest over the past two decades, but so far there are no papers published on this subject that relate specifically to diagonal acts. We attempt to shed some light on this topic as well as present some new problems.
5

Laser Guided Automated Floor Profiling - FloorWalker

Whaley, Chad 16 June 2017 (has links)
No description available.
6

Využití laserinterferometru Renishaw pro měření přímosti a rovinosti / Using of laserinterferometer Renishaw for straightness and flatness measurement

Lešanovský, Jan January 2008 (has links)
This diploma dissertation deals with straightness and flatness measurement and data evaluation. For all measurements laserinterferometer Renishaw has been used. The main purpose of this diploma work is to get values of straightness on the travel of microscope, decrypt computing methods leading to graphs of straightness, re-count it by ČSN standards and compare both sets of graphs. Flatness measurement is performed on a desk before and after lapping and these results are compared.
7

Finite Element Analysis of the Residual Stress Distribution in Rolled Aluminum Plates after Tension Levelling

Lin, Jing-yu 09 September 2012 (has links)
When an aluminum alloy plate after rolling, non-uniform residual stress distributions existed inside the plate and defects, such as edge wave, middle wave, of the plate will be induced. Usually, a levelling process will be adopted to modify the plate flatness. By numerically simulating the tension levelling process, the purpose of this thesis is to understand the final dimensions and the residual stress distribution of the aluminum plate subjected to the tension levelling process. This study used the finite element method as the basic theory of the numerical simulation. A 3-D model of a cold-rolled plate with a side wave, subjected to tension levelling process was constructed. Then, the effects of the variations of the tensile ratio and residual stress distribution after rolled on the residual stress distribution after levelling and the improvement of flatness were studied. The simulation results showed that in the wave region, the tension levelling process could eliminate more than 90% of the residual stress, in the flat region was up to 80%.Also, after leveling, the residual stress distribution in the flat region was more uniform than the wave region. After-rolled residual stresses at the wave region affected the final peak position of the wave and the stress eliminated ratio of the wave region, but showed no significant effect on the final plate width and the residual strains. After-rolled residual stresses at the flat region affected the stress elimination ratio of the flat region only. The tensile ratio would affect the plate flatness, the plate width, stress elimination ratio, and the maximum residual stress. The higher of the tensile ratio, the more flatness of the plate would be obtained, but the higher residual strain would be induced and caused the lesser range of available plate.
8

Géométrie et platitude des systèmes de contrôle de poids différentiel minimal / Geometry and flatnessof control systems of minimal differential weight

Nicolau, Florentina 01 December 2014 (has links)
Premièrement, nous avons caractérisé les systèmes multi-entrées, affines par rapport aux contrôles, linéarisables dynamiquement via une pré-intégration d'un contrôle bien choisi. Ils forment une classe particulière de systèmes plats : ils ont un poids différentiel de n+m+1, où m est le nombre de contrôles et n est la dimension de l'état. Nous avons présenté des formes normales compatibles avec les sorties plates minimales et décrit toutes les sorties plates minimales. Nous avons appliqué nos résultats à plusieurs exemples. Deuxièmement, nous avons décrit les systèmes multi-entrées statiquement équivalents à une forme triangulaire compatible avec la forme multi-chaînée. Ensuite, la platitude de ces systèmes a été analysée et résolue. Nous avons discuté les singularités dans l'espace de contrôle et déterminé toutes les sorties plates. Nous avons appliqué ces résultats au système mécanique d'une pièce roulant sans glissement sur une table en mouvement. / Firstly, we study flatness of multi-input control-affine systems. We give a complete geometric characterization of systems that become static feedback linearizable after a one-fold prolongation of a suitably chosen control. They form a particular class of flat systems, that is of differential weight equal to n+m+l, where n is the dimension of the state-space and m is the number of controls. We illustrate our results by several examples. Secondly, we give a complete geometric characterization of systems locally static feedback equivalent to a triangular form compatible with the m-chained form. We analyze and solve their flatness. We discuss singularities and provide a system of first order PDE's to be solved in order to find all x-flat outputs. We illustrate our results by an application to a mechanical system: the coin rolling without slipping on a moving table.
9

Controle da velocidade angular de uma turbina eólica de eixo horizontal via planicidade diferencial

Suehara, Bruno Batista 30 August 2016 (has links)
Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Mecânica, 2016. / Submitted by Raquel Viana (raquelviana@bce.unb.br) on 2018-04-25T17:36:15Z No. of bitstreams: 1 2016_BrunoBatistaSuehara.pdf: 6751035 bytes, checksum: 0dd1bcc9580dd606f254f041995047ec (MD5) / Approved for entry into archive by Raquel Viana (raquelviana@bce.unb.br) on 2018-04-25T17:37:01Z (GMT) No. of bitstreams: 1 2016_BrunoBatistaSuehara.pdf: 6751035 bytes, checksum: 0dd1bcc9580dd606f254f041995047ec (MD5) / Made available in DSpace on 2018-04-25T17:37:01Z (GMT). No. of bitstreams: 1 2016_BrunoBatistaSuehara.pdf: 6751035 bytes, checksum: 0dd1bcc9580dd606f254f041995047ec (MD5) Previous issue date: 2018-04-25 / A crescente utilização da energia proveniente dos ventos em todo o mundo vem trazendo desafios aos desenvolvedores de turbinas eólicas. Mais especificamente, o desenvolvimento de controladores capazes de aumentar a potência produzida pelos aerogeradores e otimizar a resposta gerada para as trajetórias nominais torna-se de suma importância para as indústrias do setor eólico, as quais buscam melhores resultados a cada dia. Um dos principais desafios enfrentados pelos fabricantes de turbinas eólicas é a complexa aerodinâmica envolvida no sistema eólico, que é particularmente não-linear, o que gera regiões de alta instabilidade para determinados pontos de operação em regime permanente. Neste contexto, o presente trabalho propõe um método de controle para velocidade angular de turbinas eólicas por meio de técnicas de planejamento de trajetória. Este método é denominado controle por planicidade diferencial, também conhecido apenas como Flatness, que juntamente com a utilização de um filtro de Kalman, irá produzir uma solução ótima para a resposta do sistema mesmo considerando-se a hipótese da presença de ruídos. Um controlador linear quadrático gaussiano será aplicado ao modelo do sistema com o intuito de comparar seus resultados com as saídas do controlador via planicidade diferencial. / The increasing use of energy from the winds around the world has brought challenges to developers of wind turbines. More specifically, the development of controllers able to increase the power produced by wind turbines and optimize the response generated for nominal trajectories becomes very important for the sector’s industries wind, which searches better results every day. One of the main challenges faced by wind turbine manufacturers is the complex aerodynamics involved in the wind power system, which is particularly non-linear, generating high instability regions for certain operating points on a steady state. In this context, this paper proposes a method to control the angular velocity of wind turbines through trajectory planning techniques. This method is named flatness based control, also known only as Flatness, with together the use of a Kalman filter, will produce an optimum solution to the system response even considering the possibility of the presence of noise. A linear quadratic gaussian controller will be applied to the model in order to compar its results to the outputs of the flatness based control.
10

Height inspection of wafer bumps without explicit 3D reconstruction.

January 2007 (has links)
by Dong, Mei. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 83-90). / Abstracts in English and Chinese. / INTRODUCTION --- p.1 / Chapter 1.1 --- Bump Height Inspection --- p.1 / Chapter 1.2 --- Our Height Inspection System --- p.2 / Chapter 1.3 --- Thesis Outline --- p.3 / BACKGROUND --- p.5 / Chapter 2.1 --- Wafer Bumps --- p.5 / Chapter 2.2 --- Common Defects of Wafer Bumps --- p.7 / Chapter 2.3 --- Traditional Methods for Bump Inspection --- p.11 / BIPLANAR DISPARITY METHOD --- p.22 / Chapter 3.1 --- Problem Nature --- p.22 / Chapter 3.2 --- System Overview --- p.25 / Chapter 3.3 --- Biplanar Disparity Matrix D --- p.30 / Chapter 3.4 --- Planar Homography --- p.36 / Chapter 3.4.1 --- Planar Homography --- p.36 / Chapter 3.4.2 --- Homography Estimation --- p.39 / Chapter 3.5 --- Harris Corner Detector --- p.45 / Chapter 3.6 --- Experiments --- p.47 / Chapter 3.6.1 --- Synthetic Experiments --- p.47 / Chapter 3.6.2 --- Real image experiment --- p.52 / Chapter 3.7 --- Conclusion and problems --- p.61 / PARAPLANAR DISPARITY METHOD --- p.62 / Chapter 4.1 --- The Parallel Constraint --- p.63 / Chapter 4.2 --- Homography estimation --- p.66 / Chapter 4.3. --- Experiment: --- p.69 / Chapter 4.3.1 --- Synthetic Experiment: --- p.69 / Chapter 4.3.2 --- Real Image Experiment: --- p.74 / CONCLUSION AND FUTURE WORK --- p.80 / Chapter 5.1 --- Summary of the contributions --- p.80 / Chapter 5.2 --- Future Work --- p.81 / Publication related to this work: --- p.83 / BIBLIOGRAPHY --- p.83

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