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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.
11

Influence of periodic stitching on the in-plane and out-of-plane mechanical properties of polymer composites

Alaziz, Radwa 08 December 2023 (has links) (PDF)
The purpose of this research is to investigate the influence of stitching architectures by using different stitching periodic patterns on the in-plane and out-of-plane mechanical properties. By using the inherent periodic architecture of these composites, their mechanical properties may be tailored for specific applications. Composite structures are extensively used in several industries such as aerospace, automotive, sports, and construction due to their many advantages, which include tailorable mechanical properties, high strength-to-weight ratios, and high specific stiffness. However, due to their low interlaminar tensile strength, composites are prone to delaminations, which can degrade the overall mechanical performance of the structure. Through-thickness stitching provides the third-direction reinforcement to enhance the interlaminar tensile and shear strengths. In this study, quasi-isotropic composite test articles were manufactured and stitched through-thickness using different chain stitch patterns. Full-field surface strain measurements were collected through the non-contact digital image correlation (DIC) technique. A design of experiments (DoE) approach was used to investigate the stitch parameters, such as stitch density (number of stitches per unit area), stitch angle (stitch seam orientation), and linear thread density (thread diameter), and their interactions on the in-plane and out-of-plane mechanical properties. Experimental results are then used to develop a statistically informed response surface model (RSM) to find optimal stitching parameters based on a maximum predicted tensile strength, tensile modulus and flexural strength.
12

Automatinis vaizdų jungimas į panoramas / Automatic image stitching into panoramas

Paulavičius, Andrius 13 August 2010 (has links)
Šiame darbe pateikiamas apibendrintas automatinio vaizdų jungimo į panoramas algoritmas, detaliai aptariami algoritmo žingsniai ir galimas našumo didinimas lygiagretaus programavimo priemonėmis. Tyrime aprašyti vaizdų jungimo bandymai panaudojant kelias populiarų vaizdų bruožų alternatyvas. Taip pat pristatoma praktinė vaizdų jungimą panaudojanti aplikacija. / This study presents a generalization of an automated image stitching algorithm, describes it's steps in great detail and discusses possible performance improvements by use of parallel execution. Results of stitching experiments using a couple of modern and popular image feature alternatives are shown. A practical application using an implementation of automated image stitching is presented.
13

Práticas e ganhos na implantação e sustentabilidade de fluxo contínuo em ambientes Lean: um estudo de caso / Practices and gains on the implementation and sustainability of a Continuous Flow in Lean environments: a case study

Guilherme Valadão de Brito Soares 13 February 2017 (has links)
As práticas e ferramentas de Lean Production já foram e vêm sendo implantadas em várias empresas dos mais diversos setores. Porém, muitas vezes tais implantações não atingem o resultado esperado. O que se observa é que o processo de implantação de práticas e ferramentas utilizadas em ambientes Lean, foca, em grande parte das vezes, na implantação de algumas ferramentas, tais como o sistema kanban ou 5S, deixando de lado a busca constante por um processo que funcione com estoque zero e sem defeitos. Tal cenário, mesmo sendo inatingível no curto ou médio prazo para grande parte das empresas é, porém, a essência do sistema de produção originado na Toyota. Esta pesquisa identifica que a implantação do fluxo contínuo é fundamental durante as implantações de práticas de Lean Production por embasar essa busca constante pela melhoria do fluxo de produção, visando sempre a remoção dos desperdícios presentes ao longo do fluxo. Por meio da realização de uma Revisão Bibliográfica exploratória são identificadas também as práticas e ferramentas que têm a sua implantação relatada com o objetivo de auxiliar a implantação ou dar sustentabilidade a um fluxo contínuo. Um estudo de caso relata a implantação de fluxo contínuo em um processo de costura com a utilização de células de produção, mostrando ainda quais outras práticas e ferramentas foram implantadas. O resultado encontrado foi que as práticas e ferramentas mais utilizadas para auxiliar a implantação e sustentabilidade de um fluxo contínuo são o takt time, balanceamento das operações, Mapeamento de Fluxo de Valor (MFV), layout celular, trabalho padronizado e sistemas puxados. Os principais ganhos identificados como resultado da implantação do fluxo contínuo e de práticas e ferramentas para auxiliá-lo em ambientes de lean production são a redução do lead time de produção, redução do work in process, aumento de produtividade, redução da área utilizada pela produção, redução do custo de produção e a redução do tempo gasto com atividades que não agregam valor ao produto. A principal dificuldade identificada para a implantação do fluxo contínuo foi a aceitação da equipe de produção, principalmente durante o início das operações após as implantações. O apoio dos Supervisores, Gerentes e Diretores das empresas se mostra fundamental para o sucesso de tal empreitada. / The practices and tools of Lean Production were and are being implemented in many companies of the most diverse sectors. However, many times such implementations do not achieve the expected result. What is observed is that the implementation process of the practices and tools used in Lean environments in a great part of the time focus on the implementation of some tools such as kanban system or 5S, keeping aside the constant search for a process that works with zero stock and with no defects. Such scenario, even being unachievable in a short and medium term for great part of the companies is, however, the essence of the production system started at Toyota. This paper identifies that the implementation of continuous flow is fundamental during the implementation of Lean Production practices for supporting this constant search for improvement of the production flow, always aiming the removal of the waste present along the flow. Through a Literature Review, are also identified the practices and tools that have its implementation reported with the target of supporting the implementation or sustain a continuous flow. A case study reports the implementation of continuous flow in a stitching process through the use of production cells, showing also what other practices and tools were implemented. The result found was that the practices and tools most used to support the implementation and sustainability of a continuous flow are takt time, workload balancing, Value Stream Mapping (VSM), cellular layout, standardized work and pull system. The main gains identified as a result of the implementation of the continuous flow and practices and tools to support it in Lean Production environments are the reduction of the production lead time, reduction of work in process, increase of productivity, decrease of the area used by the production, reduction of production cost and reduction of the time spent with non-add value activities. The main difficulty identified for the implementation of a continuous flow was the acceptance of the production team, mainly during the beginning of the operations right after the implementation. The support of Supervisors, Managers and Directors of the companies reveals fundamental for the success of this endeavor.
14

Discovery of stress biomarkers in biological matrices using novel sample collection techniques, inorganic and organic mass spectrometry and multivariate analysis

Patel, Pareen January 2013 (has links)
New methodologies for the collection and analysis of biological samples from psychological, physical and emotional stress are described. Currently, there is little research relating to the elemental, VOC and small molecule changes in biological samples as a consequence of stress on the human body, with much of the current research indicating physical symptoms. This research sought to measure chemical changes in three different categories of stress. The first uses an existing PASAT intervention to induce psychological stress and a further two new methodologies using exercise to induce physical stress and a trapped human in a simulation of a collapsed building to induce emotion stress. Psychological, physical and emotional stress elemental profiles are compared against their respective chemical baseline profiles. Skin samples are collected from the foreheads of participants who endured emotional stress while drool saliva, urine, plasma and forehead skin samples were obtained from physically stressed participants. Furthermore, drool saliva is also obtained from the individual who experienced emotional stress.
15

Práticas e ganhos na implantação e sustentabilidade de fluxo contínuo em ambientes Lean: um estudo de caso / Practices and gains on the implementation and sustainability of a Continuous Flow in Lean environments: a case study

Soares, Guilherme Valadão de Brito 13 February 2017 (has links)
As práticas e ferramentas de Lean Production já foram e vêm sendo implantadas em várias empresas dos mais diversos setores. Porém, muitas vezes tais implantações não atingem o resultado esperado. O que se observa é que o processo de implantação de práticas e ferramentas utilizadas em ambientes Lean, foca, em grande parte das vezes, na implantação de algumas ferramentas, tais como o sistema kanban ou 5S, deixando de lado a busca constante por um processo que funcione com estoque zero e sem defeitos. Tal cenário, mesmo sendo inatingível no curto ou médio prazo para grande parte das empresas é, porém, a essência do sistema de produção originado na Toyota. Esta pesquisa identifica que a implantação do fluxo contínuo é fundamental durante as implantações de práticas de Lean Production por embasar essa busca constante pela melhoria do fluxo de produção, visando sempre a remoção dos desperdícios presentes ao longo do fluxo. Por meio da realização de uma Revisão Bibliográfica exploratória são identificadas também as práticas e ferramentas que têm a sua implantação relatada com o objetivo de auxiliar a implantação ou dar sustentabilidade a um fluxo contínuo. Um estudo de caso relata a implantação de fluxo contínuo em um processo de costura com a utilização de células de produção, mostrando ainda quais outras práticas e ferramentas foram implantadas. O resultado encontrado foi que as práticas e ferramentas mais utilizadas para auxiliar a implantação e sustentabilidade de um fluxo contínuo são o takt time, balanceamento das operações, Mapeamento de Fluxo de Valor (MFV), layout celular, trabalho padronizado e sistemas puxados. Os principais ganhos identificados como resultado da implantação do fluxo contínuo e de práticas e ferramentas para auxiliá-lo em ambientes de lean production são a redução do lead time de produção, redução do work in process, aumento de produtividade, redução da área utilizada pela produção, redução do custo de produção e a redução do tempo gasto com atividades que não agregam valor ao produto. A principal dificuldade identificada para a implantação do fluxo contínuo foi a aceitação da equipe de produção, principalmente durante o início das operações após as implantações. O apoio dos Supervisores, Gerentes e Diretores das empresas se mostra fundamental para o sucesso de tal empreitada. / The practices and tools of Lean Production were and are being implemented in many companies of the most diverse sectors. However, many times such implementations do not achieve the expected result. What is observed is that the implementation process of the practices and tools used in Lean environments in a great part of the time focus on the implementation of some tools such as kanban system or 5S, keeping aside the constant search for a process that works with zero stock and with no defects. Such scenario, even being unachievable in a short and medium term for great part of the companies is, however, the essence of the production system started at Toyota. This paper identifies that the implementation of continuous flow is fundamental during the implementation of Lean Production practices for supporting this constant search for improvement of the production flow, always aiming the removal of the waste present along the flow. Through a Literature Review, are also identified the practices and tools that have its implementation reported with the target of supporting the implementation or sustain a continuous flow. A case study reports the implementation of continuous flow in a stitching process through the use of production cells, showing also what other practices and tools were implemented. The result found was that the practices and tools most used to support the implementation and sustainability of a continuous flow are takt time, workload balancing, Value Stream Mapping (VSM), cellular layout, standardized work and pull system. The main gains identified as a result of the implementation of the continuous flow and practices and tools to support it in Lean Production environments are the reduction of the production lead time, reduction of work in process, increase of productivity, decrease of the area used by the production, reduction of production cost and reduction of the time spent with non-add value activities. The main difficulty identified for the implementation of a continuous flow was the acceptance of the production team, mainly during the beginning of the operations right after the implementation. The support of Supervisors, Managers and Directors of the companies reveals fundamental for the success of this endeavor.
16

Light Sensitive

Thompson, Andrew 01 June 2015 (has links)
I am an excremental artist. I do not mean an artist who works with feces or is interested in manure but one whose artwork is expelled through the results of process. As a photographer, I am not as interested in indexing a location, a person or a moment as I am dissolving the structure of photography through the manipulation of photographic materials. I typically photograph landscapes that catch my attention for a myriad of reasons. The commonality between these images is anonymity of place. Hints of location are always present but never accentuated, instead their purpose is akin to a forging slug: raw blank material from which my artwork will be created. My photographic slugs are then entered into various processing systems that I have devised over the years. Common processing techniques that I incorporate include hand and machine stitching, chemically altering photographic paper and the integration of open-source electronics. These and other processes are mixed, matched and blended to form the corpus of my work. The body of my work is not complete without my head, heart and hands. My intellectual interests are constantly feeding the physical processes described above. I have an extended engagement with photography’s rich history along with a critical commitment to philosophy. My intuition is permitted to work in concert with my intellect despite stark contrasts between the two. My intellect looks for structures and speaks in logical thought while my intuition arrives in waves of unarticulated emotions and ‘gut feelings’. The heart’s language is often more difficult to translate than intellectual headband but both are equally valuable in my process. Finally, my hands play a vital role in creating my art. They transcribe the conversation between the head and the heart and physically complete the processes defined prior. My artwork is not conceived and the built into a structure, instead it is a result of the passing through a system. I consume copious amounts of stimuli (intellectually, visually, emotionally) and digest it through my creative process and the result is my artwork.
17

The Evolution of Craft in Contemporary Feminist Art

Packer, Carolyn E. 03 May 2010 (has links)
No description available.
18

Seamless Automatic Projector Calibration of Large Immersive Displays using Gray Code

Andersson, Carl January 2013 (has links)
Calibrating multiple projectors to create a distortion free environment is required in many fields e.g. simulators and the calibration may be done in a series different ways. This report will cover an automatic single camera projector calibration algorithm.The algorithm handles multiple projectors and can handle projectors covering bigger field of view than a camera by supporting image stitching. A proof of concept blending algorithm is also presented. The algorithm includes a new developed interpolation method building on spline surfaces and an orientation calculation algorithm that calculates the orientation difference between two camera views. Using the algorithm to calibrate, gives pixel accuracy of less than 1 camera pixel after interpolation and the relation between two views are calculated accurately. The images created using the algorithm is distortion free and close to seamless. The algorithm is limited to a controlled projector environment and calibrates the projectors for a single viewpoint. Furthermore, the camera needs to be calibrated positioned in the sweet spot although it can be arbitrary rotated.
19

Cylindrical Surface Analysis with White Light Interferometry

Bora, Ethem January 2011 (has links)
At present, one of the big challenges is to develop a precise surface measurement method for mechanical parts. Especially, to study cylindrical surface, the cause of many difficulties because of its geometry shape. This thesis presents a quite good solution for analyzing topography of cylindrical surface with White Light Interferometry optical system which is one of the important and suitable tools in optics. In the construction period, the aim was to build a system which can be easily mounted on the sample. This is done by a very simple and compact design that also enables us to use it in research laboratories. In the project, a cylindrical surface analysis is achieved by taking subsequent images with different nano-scale distance from the sample and stitched the acquired images. To achieve this implementation, subsequent images with the highest intensity are first determined and then located in a single image. In the stitching process, cross correlation method that is extremely useful to find out relative point of the images is used to merge the acquired images. Additionally, stitching process is helped us to extend the area where research can be done. In the project, MATLAB & LABVIEW are used for analyzing the images and controlling the motors, respectively.
20

Foveated coding for persistics

Bernstein, Alan Aaron 19 April 2013 (has links)
Persistics is an advanced framework for processing wide-area aerial surveillance video. This framework handles the tasks of data collection, stitching of multi-sensor imagery, image registration and stabilization, motion tracking, and compression. As the technology for image sensor sizes improves, significant improvements in compression techniques are necessary in order to make full use of the data. Because the information of interest in such video is naturally moving, point-like targets, the applicability of foveated coding to the compression problem is an interesting question. Foveated coding, a compression technique that was designed to be perceptually optimal for the human visual system, has several components that are appropriate to the persistics compression problem. Foveation is applied in several different scenarios and methods to persistics data. As foveation can make good use of the persistics tracker data, a problem affecting tracker performance is explored as well. The multi-sensor stitching component of persistics can generate artifacts that reduce the effectiveness of the tracker. A method for characterizing, detecting, and correcting such artifacts is desirable. These three concepts are explored, and a method for detection is developed. Components of these algorithms were absorbed into a more general framework for artifact correction. / text

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