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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

Respostas cardiovasculares e biomecânicas aos efeitos do tilt test ativo e passivo em indivíduos saudáveis / Cardiovascular and biomechanics responses caused by active and passive tilt test in healthy subjects

Rogério Ferreira Liporaci 22 November 2011 (has links)
Para avaliação da sincope neurocardiogênica, testes ativos e passivos de mudança postural são utilizados, e verificar o comportamento da musculatura e da oscilação do corpo pode auxiliar no melhor entendimento das respostas cardiovasculares e biomecânicas. O objetivo do presente estudo foi comparar protocolos ativo e passivo de mudança postural, padronizado de 15 minutos, associado a três manobras de Valsalva intervaladas, para os testes de mudança postural ativa, Acive Standing test (AS) e passiva, Head-Up Tilt test (HUT), utilizados no diagnóstico da síncope neurocardiogênica (SNC), em relação às mudanças nos valores de frequência cardíaca, pressão arterial sistólica e diastólica, atividade eletromiográfica dos músculos reto abdominal (RA), eretores da espinha (EE), tibial anterior (TA) e gastrocnêmio porção medial (GM) bilateral, em 23 mulheres saudáveis, além de analisar o deslocamento e velocidade média do centro de pressão do corpo sobre uma plataforma de força. Verificamos alterações com relevância estatística para todas variáveis ao longo dos testes, principalmente durante o período onde as manobras de Valsalva eram realizadas, sendo estas alterações maiores durante o teste ativo, além do centro de pressão do corpo demonstrar um maior deslocamento e velocidade de movimento durante o mesmo período. Concluímos que este protocolo proposto para os dois testes causa mudanças tanto cardiovasculares quanto biomecânicas, mas que foram mais evidentes no teste de mudança postural ativa. / To evaluate the neurocardiogenic syncope (NCS), active and passive postural change tests are used and verify the muscles and body oscilation behavior´s can be helpful to better understand the cardiovascular and biomechanics responses. The aim of the present study was compare a standard 15 minute tilt test protocol associated with three Valsalva maneuver during both Active Standing (AS) and passive Head-Up tilt test (HUT). These tests are used to diagnosis of neurocardiogenic syncope (NCS). We analysed the effects of orthostatic position in relation to changes in the values of heart rate, systolic and diastolic blood pressure, electromyographic activity of the rectus abdominis (RA), erector of spinae (ES), tibialis anterior (TA) and medial gastrocnemius (MG) bilateral in 23 healthy women, and analyze the displacement and average velocity of the body\'s center of pressure on a force platform. We found changes with statistical significance for all variables during the tests, especially around the period where the Valsalva maneuvers were performed, and these major changes occurred during the active test, beyond the center of body pressure what indicates a greater movement and speed of movement during the same period. We conclude that the proposed protocol for the two tests produce both cardiovascular and biomechanical changes and these alterations were more evident in active postural test.
12

Designing an Aftermarket Head Up Display / Konstruktionen av en allmän Head Up Display

Södergren, Leo January 2021 (has links)
Road safety is one of the world’s largest challenges. New technologies have made roads both safer, but also more dangerous as people to a greater extent drive distracted. The Swedish startup Consenz AB aims to solve this by creating a hardware/software system of connected Head Up Displays (HUDs). The purpose of this thesis isto create concepts of aftermarket HUDs that can help Consenz create their first hardware. More specifically this thesis focuses on creating a device that can fit into most vehicles and provide an appropriate image. The work followed a version of the Double diamond design process, with four parts. In the first two parts the challenge was assessed, and a set of requirements made. In the second half of the project concepts were generated and evaluated from the requirements made in the first half. The first part of the project was aimed at gathering knowledge about the topic, the market today and its potential customers, this was done by contacting various stakeholders, documenting car interiors, and reading research and regulations around the topic. The second part of the project evaluated available display technologies and together with the first part, resulted in a set of requirements for the second half of the project. The third part of the project used a number of concept generation methods to create several concepts. These concepts were evaluated and narrowed down to two concepts. In the final part of the project these concepts were refined and evaluated. The work resulted in two concepts, physical models of the concepts and a recommendation for which concept to continue with. / Trafiksäkerhet är en av världens största utmaningar. Ny teknik har gjort vägar både säkrare men också farligare eftersom människor i större utsträckning kör distraherade. Svenska startupen Consenz AB vill lösa detta genom att skapa ett hårdvaru- / mjukvarusystem med anslutna Head Up Displays (HUD). Syftet med denna uppsats är att skapa koncept för eftermarknads-HUD som kan hjälpa Consenz att skapa sin första hårdvara. Mer specifikt fokuserar projektet på att skapa en enhet som passar in i de flesta fordon och som ger en lämplig bild. Arbetet följde en version av Double Diamond design processen, med fyra delar. I de två första delarna utvärderades problemet och en uppsättning krav ställdes. Under andra halvan av projektet genererades och utvärderades koncept utifrån de krav som ställts under första två delarna. Den första delen av projektet samlade kunskap om utmaningen, marknaden idag och dess potentiella kunder, detta gjordes genom att kontakta olika stakeholders, dokumentera bilinteriörer och genom att studera texter kring området. Den andra delen av projektet utvärderade olika displayteknologier och tillsammans med den första delen resulterade det i flera krav. Den tredje delen av projektet använde olika konceptgenereringsmetoder för att skapa flera koncept. Dessa koncept utvärderades och begränsades till två koncept. I den sista delen av projektet förfinades och jämfördes dessa koncept. Arbetet resulterade i två koncept, fysiska modeller av koncepten och en rekommendation för vilket koncept att fortsätta med.
13

Critical Investigation of the Pulse Contour Method for Obtaining Beat-By-Beat Cardiac Output

Matushewski, Bradley January 2001 (has links)
The purpose of this study was to explore the efficacy of two existing pulse contour analysis (PCA) models for estimating cardiac stroke volume from the arterial pressure waveform during kicking ergometer exercise and head-up tilt manoeuvres. Secondly, one of the existing models was modified in an attempt to enhance its performance. In part I, seven healthy young adults repeated two submaximal exercise sessions on a kicking ergometer, each with three different sets of steady-state cardiac output comparisons (pulsed Doppler vs. pulse contour). Across all exercise trials regression results were found to be PCA = 1. 23 x Doppler-1. 38 with an r2 = 0. 51. In part II, eight young and eight older male healthy subjects participated in a head-up tilt experiment. Cardiac output comparisons were again performed during the supine and tilt conditions using pulsed Doppler and pulse contour cardiac output. Regression results revealed that PCA performed best during supine conditions and preferentially on the older subjects. In all instances, impedance-calibrated pulse contour analysis will provide reasonable beat-by-beat cardiac output within very narrow confines and will result in a progressively more significant bias as cardiovascular dynamics change. In addition, it appears that heart rate variability negatively influences beat-by-beat pulse contour cardiac output results, further limiting application of existing models.
14

Critical Investigation of the Pulse Contour Method for Obtaining Beat-By-Beat Cardiac Output

Matushewski, Bradley January 2001 (has links)
The purpose of this study was to explore the efficacy of two existing pulse contour analysis (PCA) models for estimating cardiac stroke volume from the arterial pressure waveform during kicking ergometer exercise and head-up tilt manoeuvres. Secondly, one of the existing models was modified in an attempt to enhance its performance. In part I, seven healthy young adults repeated two submaximal exercise sessions on a kicking ergometer, each with three different sets of steady-state cardiac output comparisons (pulsed Doppler vs. pulse contour). Across all exercise trials regression results were found to be PCA = 1. 23 x Doppler-1. 38 with an r2 = 0. 51. In part II, eight young and eight older male healthy subjects participated in a head-up tilt experiment. Cardiac output comparisons were again performed during the supine and tilt conditions using pulsed Doppler and pulse contour cardiac output. Regression results revealed that PCA performed best during supine conditions and preferentially on the older subjects. In all instances, impedance-calibrated pulse contour analysis will provide reasonable beat-by-beat cardiac output within very narrow confines and will result in a progressively more significant bias as cardiovascular dynamics change. In addition, it appears that heart rate variability negatively influences beat-by-beat pulse contour cardiac output results, further limiting application of existing models.
15

Warning systems design in a glass cockpit environment

Norén, Johan January 2008 (has links)
<p>In Sweden close to 500 people are killed and several thousands severely injured in traffic each year. This is one of the largest health problems for society in both Sweden and the whole world. In the cars of tomorrow will the main instrument panel and the centre console be screen-based instead of the current solution with “iron instruments” and other physical devices. This future driver environment opens for a flexible and situation-dependent usage of presentation resources. The purpose of this thesis is to explore these possibilities from a warning system perspective.</p><p>The project had its main focus on designing warning system concepts using the HUD and vibrotactile information in a coordinated way based on established HMI principles. Another goal for this thesis work was to generate a functional concept for demonstration and evaluation in the virtual reality lab at the University of Linköping.</p><p>The method of realization was divided into three phases – information gathering, concept generation and implementation. These phases are commonly used in design projects. This way of work supplies structure to the project and makes it possible to achieve an iterative design process.</p><p>The information gathering involved a thorough theoretical study of HMI, interface design and warning design. A state of the art investigation was then conducted to find out how the warning systems, relevant to this thesis, are presented today.</p><p>The concept generation was divided into two parts – warning system design and visual design. The Warning system design concepts were based on different combinations from a morphologic matrix and relevant theory. Consideration was also taken to when the systems are likely to be activated and which modality, or modalities, that then was suitable to use. The visual design concepts were developed by using creative product development methods and the iterative Simulator-Based Design (SBD) theory.</p><p>After concluding the concept generation was the visual design results given functionality by programming software. The visual warning system were then integrated in the simulator software and fully implemented in the simulator cockpit at the university.</p><p>The implemented warning systems were then evaluated by a pilot study conducted in the simulator. Test persons were invited to the VR-lab and given an introduction to the warning systems. They were then asked to drive a predetermined route with a number of different warning system conditions. These test results were later statistically analyzed and evaluated.</p>
16

Warning systems design in a glass cockpit environment

Norén, Johan January 2008 (has links)
In Sweden close to 500 people are killed and several thousands severely injured in traffic each year. This is one of the largest health problems for society in both Sweden and the whole world. In the cars of tomorrow will the main instrument panel and the centre console be screen-based instead of the current solution with “iron instruments” and other physical devices. This future driver environment opens for a flexible and situation-dependent usage of presentation resources. The purpose of this thesis is to explore these possibilities from a warning system perspective. The project had its main focus on designing warning system concepts using the HUD and vibrotactile information in a coordinated way based on established HMI principles. Another goal for this thesis work was to generate a functional concept for demonstration and evaluation in the virtual reality lab at the University of Linköping. The method of realization was divided into three phases – information gathering, concept generation and implementation. These phases are commonly used in design projects. This way of work supplies structure to the project and makes it possible to achieve an iterative design process. The information gathering involved a thorough theoretical study of HMI, interface design and warning design. A state of the art investigation was then conducted to find out how the warning systems, relevant to this thesis, are presented today. The concept generation was divided into two parts – warning system design and visual design. The Warning system design concepts were based on different combinations from a morphologic matrix and relevant theory. Consideration was also taken to when the systems are likely to be activated and which modality, or modalities, that then was suitable to use. The visual design concepts were developed by using creative product development methods and the iterative Simulator-Based Design (SBD) theory. After concluding the concept generation was the visual design results given functionality by programming software. The visual warning system were then integrated in the simulator software and fully implemented in the simulator cockpit at the university. The implemented warning systems were then evaluated by a pilot study conducted in the simulator. Test persons were invited to the VR-lab and given an introduction to the warning systems. They were then asked to drive a predetermined route with a number of different warning system conditions. These test results were later statistically analyzed and evaluated.
17

Shoulder Impingement in Water Polo Players

Davis, Kelly A. 01 January 2014 (has links)
Water polo is a highly dynamic and physically demanding sport that has heretofore not inspired nearly as much research as other overhead sports such as baseball or swimming. As in almost all overhead sports, water polo puts its players at high risks for shoulder injuries since the motions required to perform the sport at an optimum level push the limits of normal shoulder function. Human shoulders are inherently unstable as a tradeoff to their flexibility. Because of this instability, many structures are required to work concurrently to keep the shoulder in place. These structures include muscles, ligaments and cartilages. It is important to recognize that the shoulder is not a singular joint in itself but rather a highly mobile complex that can perform many nuanced motions. Shoulder instability can cause a variety of injuries such as impingement, which occurs often among overhead athletes. This malady refers to a pathologic limitation of normal subacromial space that causes structures to be in abnormal contact with each other, which causes abrasive and pinching forces. These forces can result in a range of shoulder maladies including bursitis, tendinitis, and tearing of muscles and ligaments. Impingement is very apparent in both swimmers and water polo players due to the repetitive stresses present in each sport. In swimmers, impingement has been relatively well researched; the freestyle stroke utilized in water polo, however, is fundamentally different in that water polo players keep their heads and chests erect out of the water with a stroke known as head-up freestyle. Hitherto unknown are the biomechanics of this stroke and the extent to which impingement in water polo players is caused and/or worsened by this form of freestyle. The proposed research is a two-part study to investigate the biomechanics of water polo head-up freestyle as a first step to understanding its role in impingement in water polo players. First, experienced water polo players with healthy shoulders approved by the IRB committee of Scripps College will be recruited in this study, and their head-up freestyle kinematic sequences and muscle activities will be recorded by synchronized high-speed cinematography and fine-wire electromyography. These data will be compared to those of head-down freestyle in the literature to understand the biomechanical differences between head-up in and head-down. Part II of the study will recruit experienced water polo players with existing shoulder impingement in addition to those with healthy shoulders in Part I, and their head-up freestyle will be recorded in the same manner. These data will be compared to those in Part I to understand how the head-up stroke differs between impinged and healthy shoulders. This research will provide a basis for the understanding of impingement in head-up freestyle to ultimately increase the safety of the players. Further studies should be conducted to compare the patterns of biomechanical differences between healthy and impinged shoulders in head-up vs. head-down, analyze impingement in each phase of the head-up swim stroke, and investigate how the rate of impingement is altered by fatigue and poor technique.
18

CALF HEMODYNAMICS DURING VENOUS OCCLUSION AND HEAD-UP TILT

Kilfoil, Peter J 01 January 2007 (has links)
The potential role of lower limb blood pooling in reducing venous return to the heart during orthostasis and elevated venous pressure is investigated. This study compares lower limb capacitance, microvascular filtration, and peripheral resistance between a group of highly trained endurance athletes and a group of their sedentary peers. Seven endurance trained males were selected between the ages of 23-33 [(29.1 4.1 yr), mean SD]. The subjects weekly cycling mileage ranged from 80 to 150 miles per week with an average of 125 8.5 miles/week. Nine healthy, age-matched sedentary subjects (25.8 4.8 yr.) were selected for the control group, based upon their reporting they had not participated in repeated lower-body or cardiovascular exercise in the months prior to their study. Results show that both subject groups had similar calf venous capacitances, rates of capillary fluid filtration, and local flow shunting (vascular resistance change) in response to venous thigh occlusion and 70 head-up tilt (HUT). The only significant difference found between groups was the cyclist groups smaller rise in heart rate in response to HUT. The findings of this study suggest that cyclists are not predisposed to orthostatic intolerance due to any changes in lower limb function.
19

Méthode des Eléments Finis pour les nanostructures métalliques : application au filtrage spectral dans le visible et extension au calcul modal en présence de dispersion / Finite element method for plasmonics nanostructures : application to spectral filtering in the visible range and extension to modal computation with dispersion

Brûlé, Yoann 18 November 2016 (has links)
Dans ce travail de Thèse de Doctorat, dans le contexte d’une application de filtrage optique pour la réalité augmentée des Viseurs Tête Haute (VTH), plusieurs possibilités de conception de filtres basés sur des résonances de nanoparticules métalliques sont explorées. Pour ce faire, une formulation de la Méthode des Éléments Finis (FEM) précédemment développée au sein de l’Institut Fresnel est appliquée à différentes structures électromagnétiques complexes. La validité des résultats de la FEM est alors vérifiée, dans une configuration extrêmement résonante d’un réseau bidimensionnel de nanocônes d’or illuminé dans des conditions d’absorption totale de la lumière incidente, par comparaison avec les résultats d’une autre méthode numérique complètement indépendante. Une fois validée dans cette configuration extrême, cette méthode a pu être utilisée afin de conduire une étude paramétrique sur deux types particuliers de réseaux de nanoparticules métalliques. Les résultats de cette étude paramétrique ont conduit aux designs de deux types de composant de filtrage de la lumière visible requis pour l’application VTH: celui de réseaux monodimensionnels de rubans d’argent permettant de réfléchir une partie du spectre lumineux pour une composante de polarisation de la lumière tout en étant globalement transparent pour l’autre composante de polarisation, et celui de réseaux bidimensionnels de nanocylindres à section elliptique permettant de réfléchir deux parties distinctes du spectre en fonction de la polarisation de la lumière incidente et ceci toujours avec des propriétés de transparence globale. Dans un dernier temps, une nouvelle formulation de la FEM est développée afin d’étendre cette méthode numérique au calcul des modes de résonance de ce type de nanostructures métalliques. En présence de structures incorporant des matériaux métalliques, dispersifs et dissipatifs, l’opérateur de Maxwell associé est non-linéaire en fréquence et non-Hermitien et donc difficile à aborder numériquement. Dans le but de linéariser cet opérateur vis-à-vis de la fréquence, le formalisme dit de “champs auxiliaires” a été implémenté numériquement aux éléments finis. La validité des résultats numériques obtenus est enfin vérifiée sur une cavité fermée puis sur différents cristaux photoniques bidimensionnels constitués de tiges métalliques de Drude. Enfin, dans le cas de structures ouvertes, une couche parfaitement adaptée (PML) dispersive est étudiée dans le cadre des problèmes modaux. / In this PhD, in the frame of a filtering application for augmented reality of Head-Up Display (HUD), several possibilities to design filters based on metallic nanoparticles resonances are explored. To do so, a Finite Element Method formulation previously developed within the Institut Fresnel is initially recalled and its implementation applied to various complex electromagnetic structures. The validity of its results is verified, in the particuliar case of an extremely resonant configuration consisting in a gold nanocones metallic grating illuminated in the condition of total absorption of light, by comparison with the results of another completely independent numerical method. Thus, the results of this implementation having been validated in this extreme configuration, they could then be used to conduct a parametric study on two particular types of metallic nanoparticles gratings significantly less resonant. The results of this parametric study have led to the design of both types of filtering component of the visible light required for the HUD application: the mono-dimensional silver ribbons gratings allowing to reflect a part of the visible spectrum for one polarization’s component of the light while being globally transparent for the other component, and that of two-dimensional silver nanocylinders of elliptic cross section allowing to reflect two distinct parts of the spectrum according to the polarization of incident light while still being globally transparent. In a last time, a new FEM formulation is developed in order to extend this numerical method to the resonances computation of this kind of metallic nanostructures. When metallic materials are involved into electromagnetic structures, the associated Maxwell operator is non-linear and non-Hermitian. The Eigenvalue problem to solve is practically impossible to implement into the FEM. In order to linearize the Maxwell operator toward the frequency, a formalism called “Auxiliary fields formalism” is introduced and implemented numerically. The validity of the results obtained through this implementation is then verified on a closed cavity and on several example of bi-dimensional photonic crystals made of Drude metallic rods. Finally, when tackling open structures, a dispersive perfectly matched layer (PML) is studied in the frame of eigenvalue problems.
20

The designs and aesthetics of Augmented Reality Head-Up Displays / The designs and aesthetics of Augmented Reality Head-Up Displays

Johansson, Anton January 2022 (has links)
Head-up displays convey important information to the viewer: from time and weather conditions to GPS navigation and proactive danger alerts. This information can be key to significantly improving driving experience from merely making it more enjoyable to saving lives. Taking its roots in the military field,  Augmented Reality Head-Up Displays (AR HUD) is now being piloted and commercialised for upper-class consumers, such as the new Mercedes S-Class. It is easy to imagine how companies would want to take the next step and make these technologies even more accessible. However, one of the main challenges of diffusing these solutions lie within flaws of its visual design that can be perceived as distracting or exhausting. The purpose of this article has been to investigate the perception drivers have on AR HUDs aesthetic design and identify three areas for improvement: "style-cleaningness", flexible colour scheme and optimal positioning. This has been done through interviews and analysing the answers. Together with the answers and related research I have drawn conclusions and made suggestions of improvement. The results indicate a positive opinion of the technology and the potential it has for driver safety.

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