• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 32
  • 14
  • 9
  • 4
  • 4
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 79
  • 13
  • 12
  • 10
  • 9
  • 9
  • 9
  • 8
  • 8
  • 7
  • 7
  • 7
  • 7
  • 7
  • 7
  • 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

INJURY RISK TO THE UPPER EXTREMITY RESULTING FROM BEHIND SHIELD BLUNT TRAUMA

de Lange, Julia January 2023 (has links)
Ballistic shields are supported by a user’s arm, placing the upper extremity at close proximity to the back-face of the shield. Although ballistic shields must pass a protective standard that outlines projectile (bullet) penetration; there is no standard that stipulates the amount of acceptable deformation when ballistic shields stop or deflect projectiles. There are no injury criteria developed for the high-rate, short duration and focal loading that is typical of shield back-face deformation from these events. In this research, an anthropomorphic test device (ATD) was modified to allow for additional instrumentation capable of measuring these loads. It was then used in a ballistic testing facility to quantify loading at the hand, wrist, forearm, and elbow. A lightweight projectile was created that matched the shape and stiffness of the deforming ballistic shield and impacts within 5% of the peak force measured in the ballistic testing facility were applied with it to post-mortem human subjects (PMHS) until failure. Eight 50th percentile male PMHS pairs were segmented at the mid-humerus and impacted to failure to determine the fracture threshold of the hand, wrist, forearm, and elbow, confirmed by x-ray imaging. The peak force required to generate fracture varied significantly among anatomical location, indicating boundary conditions influence failure threshold. Further, these injury criteria were substantially different than previously reported criteria for other loading events (e.g., automotive), highlighting the importance of developing injury criteria specific for the intended application. An existing finite element human body model designed for automotive impacts was also assessed for its applicability to predict injury in these high-rate loading scenarios, and performed well for peak force, but not for the force-time curve shape. This is the first study of its kind to assess injury risk resulting from shield behind armour blunt trauma, and results from this work will inform a protective standard to assess ballistic shields. / Thesis / Doctor of Philosophy (PhD) / Ballistic shields used by defence personnel are designed to stop incoming bullets by deflecting or absorbing them. In the process, the back-face of the shield undergoes a rapid deformation that can potentially cause an upper extremity injury to users, an injury mechanism termed behind shield blunt trauma. This work aimed to quantify the injury risk that this mechanism poses at four locations along the upper extremity: the hand, wrist, forearm, and elbow. This was conducted by modifying and employing a crash test dummy upper extremity and measuring loads applied to the upper extremity in a ballistic testing range. Assessment of whether these loads caused injury was conducted using cadaveric specimens and testing them to failure. An existing finite element human body model was also assessed for its applicability to predict injury in these high-rate loading scenarios. Results from this work will inform a protective standard to assess ballistic shields.
12

Magnetic resonance imaging and anthropometric measurements: a correlational study in fixed fetal specimens

Wickum, Mary Ellen 22 January 2016 (has links)
For many decades the Boston University School of Medicine Department of Anatomy and Neurobiology has housed an unprovenienced collection of fetal specimens. At least ten percent of the 137 fetal specimens were lost due to drying out and other damage. The specimens were stored for many decades in individual fluid filled containers. There is no reliable information regarding the medical or curation histories of the human fetal specimens. Furthermore, there is concern that the fixative may have led some internal structures to shrink more than others. At issue was to determine whether the specimens had maintained or lost their relationships, and size amongst internal structures. In normal fetal development the cerebellum, the femur, and the foot all follow mostly positive linear growth with age. Therefore, the purpose of the present study was to assess whether these specimens demonstrate anatomical correlations that one might find within in utero fetuses. This prospective correlation study used MRI images of the cerebellum and femur as well as anthropometric measurements of each foot and mass to seek to answer this question. A blind, random sample of twenty-five specimens was selected from forty-eight specimens roughly grouped by size. The Boston University Institutional Review Board was notified and, assigned waiver status to the application because the specimens were unprovenienced fixed tissue. All specimens were magnetic resonance scanned at the Center for Biomedical Imaging at the Boston University School of Medicine using a 3.0T whole body scanner (Achieva, Philips Healthcare, Best, The Netherlands). All scans were acquired using the 8-channel high-resolution head coil made by Invivo for the Achieva 3T scanner. This study found that the measurements taken from the images, and the feet had good intra-rater reliability because paired t-tests did not show significant differences between the measurements (alpha (α) < 0.05, all p-values were > 0.17, t-values were less than t-critical, and R2 < 0.02). Pearson's correlation coefficient testing revealed strong positive correlation between all the mean measures comparing these three structures: transverse cerebellar diameter (TCD), femur length, and foot length (α < 0.05, r - values were > 0.91, p < 0.001, and R2 > 0.82). Leading us to conclude that the dimensions of the soft tissues - TCD; and bone tissues - femur and foot of the lower extremities were unlikely to have changed significantly in decades of storage.
13

Fetus safety in motor vehicle accidents

Moustafa, Moustafa January 2014 (has links)
Motor vehicle accidents are statistically the major cause of accidental severe injuries for pregnant women and fetuses fatality. Volunteers, post mortem human surrogates, anthropomorphic crash test devices and computational occupant models are used to improve human safety in motor vehicle accidents. However, due to the ethical issues, pregnant women and their fetuses cannot be used as volunteers or post mortem human surrogates to investigate the effects of crashes on them. The only anthropomorphic test device representing pregnant women is very limited in design and lacks a fetus. There is no computational pregnant occupant model with a fetus other than 'Expecting'. This thesis focuses on understanding the risk of placental abruption for pregnant drivers involved in road accidents, hence assessing the risk to fetus fatality. An extensive review of existing models in general and pregnant women models in particular is reported. The time line of successive development of crash test dummies and their positive effect on automotive passive safety design are examined. 'Expecting', the computational pregnant occupant model with a finite element uterus and a multibody fetus, is used in this research to determine the strain levels in the uteroplacental interface. External factors, such as the effect of restraint systems and crash speeds are considered. Internal factors, such as the effect of placental location in the uterus, and the inclusion and exclusion of a fetus are investigated. The head of the multibody fetus is replaced with a deformable head model to investigate the effects of a deformable fetus head on strain levels. The computational pregnant driver model with a fetus offers a more realistic representation of the response to crash impact hence provides a useful tool to investigate fetus safety in motor vehicle accidents. Seat belt, airbag and steering wheel interact directly with the pregnant abdomen and play an important role on fetus safety in motor vehicle accidents. The results prove that the use of a three-point seat belt with the airbag offer the greatest protection to the fetus for frontal crash impacts. The model without a fetus underestimates the strain levels. The outcome of this research should assist automobile manufacturers to address the potential safety issues at the design level.
14

Variation of image counts with patient anatomy and development of a Monte Carlo simulation system for whole-body bone scans

McGurk, Ross James January 2007 (has links)
The optimisation of image quality in medical imaging techniques is a significant factor in favourable patient prognoses. The number of counts in a nuclear medicine image is one factor in determining the diagnostic value of the image. The current study aims to determine the variation in counts in whole-body bone scan images with patient height and weight. Three separate studies were undertaken as part of the investigation. First, 65 whole-body bone scans were analysed together with patient height, weight, age and sex. Weight was found to the most important anatomy influence on image counts. However, significant influences from patient sex and age meant that a useful relationship between image counts and patient anatomy based solely on height and weight could not be determined. For the second study, a model of General Electric Millennium MG gamma camera was created and validated within the SIMIND Monte Carlo software. The results indicate that the model is an accurate representation of the gamma camera. Third, the 4D NCAT whole-body patient phantom was modified to represent the average male and female clinical study participants. The phantoms were used in conjunction with the gamma camera model to simulate the whole-body bone scan procedure. The counts in the simulated images were consistent with the average measured counts of the clinical study indicating that it is feasible to use the NCAT phantom for nuclear medicine bone imaging. However, the phantom’s method of activity distribution should be refined to allow a more realistic distribution of activity throughout the skeleton.
15

Prilog izučavanju performanse antropomorfnih mehanizama preko njihovih dinamičkih karakteristika / A Contribution to the Study of Anthropomorphic Mechanisms through their Dynamic Characteristics

Surla Dušan 12 September 1980 (has links)
<p>Glavni rezultat istraživanja je analiza uticaja parametara na performanse antropomorfnog hoda.&nbsp;&nbsp; Analiziran je uticaj parametara na pona&scaron;anje: kompenzacionih pokreta; maksimalne vrednosti pogonskih momenata i snage u toku punog koraka za sve aktuatore; skoka ubrzanja trupa u frontalnoj i sagitalnoj ravni pri prelasku tačke nula momenta (TOM) ispod jedne pod drugu nogu; ukupne snage svih aktuatora i maksimalne vrednosti vertikalne komponente sila reakcije.&nbsp; Za ovu analizu izdvojeni su sledeći parametri: dužina koraka; period trajanja koraka; Zakon TOM-a i period trajanja dvooslonačke faze.</p> / <p>The main research result is analysis of the parameters&rsquo; impact on the anthropomorphic walk performances.&nbsp; The analysis covered parameters&rsquo; impact on behavior of: compensating movements; maximal values of the driving moments and power during the full step for all actuators; rise of the body&rsquo;s acceleration in frontal and sagittal plane during the transition of the zero-moment-point (ZMP) from bellow one foot to bellow another foot; total power of all actuators and maximal value of the vertical component of the reaction force.&nbsp; For this analysis the following parameters are considered: step length; step duration period; ZMP law and the period of the double-support phase duration.</p>
16

Le vase et le corps : archéologie du caractère anthropomorphe des poteries du Néolithique en Méditerranée nord-occidentale / Pots and body : archaeology of anthropomorphic ceramics from Neolithic in the north-eastern mediterranean area.

Recchia, Johanna 18 December 2018 (has links)
L’étude du mobilier céramique des peuples de la Préhistoire récente permet aux archéologues de distinguer différents groupes culturels ou cultures matérielles. Ces variétés culturelles reposent sur l’adoption par des groupes humains d’un type particulier de vases qui varie dans le temps et dans l’espace dans les limites d’aires culturelles. Les décors, les éléments de préhension, la morphologie des vases, les techniques de fabrication déterminent ces styles. L’archéologue ou le céramologue perçoit dans l’abondance de caractères ou l’absence de ceux-ci, la marque, le signe, d’un fait culturel. Ces différents critères servent à établir une typologie qui permet d’attribuer une série céramique à un groupe culturel. À travers cette typologie, l’archéologue croit percevoir une intention culturelle. Cependant, un regard porté sur l’ensemble de la céramique du Néolithique affirmé voit, dans la poterie en elle-même, le marqueur d’une nouvelle représentation du fait social et culturel, qui accompagne le nouveau rapport entre l’homme et son environnement à partir du passage à l’économie de production. C’est au travers de la perception de l’identification du vase au corps humain, tel que l’on peut le percevoir dans les sociétés traditionnelles et dans quelques cultures archéologiques, que nous désirons dépasser les limites intrinsèques à l’analyse typologique. Les cultures matérielles sont multiples, séparées, divisées, et leur diversité ne matérialise pas seulement les variétés culturelles. La poterie est avant tout le marqueur d’un nouveau fait culturel qui concerne l’ensemble des cultures néolithiques. Elle est un des vecteurs qui cristallisent l’ancrage du Néolithique et avec lui, une nouvelle perception par l’homme de lui-même, de sa société, de l’univers réel qu’il habite, mais aussi de l’univers spirituel, mythologique, imaginé, symbolisé qui l’habitent. En choisissant comme point de départ les différentes démarches analytiques sur la céramique du Languedoc-Roussillon depuis le Néolithique ancien au Néolithique final, nous voulons considérer la poterie, au-delà de son intérêt matériel, dans son intérêt symbolique et culturel. / This thesis proposes to study the question of the relations between the body and the Neolithic pottery through the case of so-called anthropomorphous vases in the north-western Mediterranean.The first part presents the problematic of this thesis and presents the chronological and geographical framework. We make a brief review of the knowledge of the presence of this type of artefacts and commonly proposed interpretations, and we expose the methods by which we intend to analyze anthropomorphic vases.The second part presents the corpus of vases collected in the catalog (volume 2) by chrono-cultural area. It proposes a typological classification of these pottery and it discusses more particularly the modalities of their emergence in the North-Western Mediterranean, their diffusion or their evolution.The last part questions the choice of pottery as a medium of Neolithic body representation. The creation of a repository of data from ethnology, ethnoarchaeology or narratives allows us to situate our object of study in the field of metaphor and to approach it as a sign. We draw inspiration from theories from semiology and more generally from cultural anthropology in order to get out of the usual accepted archaeological interpretations.The results lead us to propose a definition of anthropomorphic vases and to discuss the phenomenon of the anthropomorphization of vases in the Neolithic context and the effects of agro-pastoral lifestyles on the production of the body's imaginary.
17

Personnages artificiels anthropomorphes et technologiques à la scène / Anthropomorphic and technological artificial characters on stage

Gallois, Aurélie 06 October 2017 (has links)
De grands metteurs en scène, précurseurs d’un nouveau théâtre, tels que Maurice Maeterlinck ou Edward Gordon Craig, souhaitaient représenter la vie en ne se contentant plus de la présence corporelle de l’acteur mais en incorporant des éléments conventionnels à la scène. Ils refusaient la simple imitation du réel au profit d'un théâtre artificiel et symbolique, avec pour problématiques les questions de la représentation de la figure humaine et de l’illusion du vivant. Cette volonté de s’émanciper du corps de l’acteur tel qu’il est dans l’usage privé, dans le quotidien, par l’utilisation de masques, de marionnettes ou encore des techniques de leur temps, comme des jeux de lumières ou des effets d’optiques, annonçait déjà l’apparition des nouveaux médias sur le plateau. C’est dans cette filiation que sont apparus sur scène, dans les années 1990, de nombreux personnages inorganiques créées grâce à des projections vidéo sur supports bi ou tridimensionnels, des hologrammes, et par la présence de robots humanoïdes et androïdes. On retrouve cette volonté de remplacer les corps des acteurs par des personnages artificiels utilisant les technologies de notre temps avec les personnages vidéo de Denis Marleau et Stéphanie Jasmin, les hologrammes de Michel Lemieux et Victor Pilon ou encore les robots d’Oriza Hirata. Ces personnages atypiques, qu’ils possèdent ou non une matérialité sur scène, qu’ils soient physiques ou virtuels, possèdent différents niveaux de présences suivant leur intégration au plateau et la dramaturgie, leur autonomie et leurs interactions avec leur environnement ou les corps réels qui leur donnent la réplique et avec lesquels ils partagent la scène. Comme nous allons le découvrir, ces nouvelles pratiques et esthétiques théâtrales visant à utiliser des Personnages Artificiels Anthropomorphes et Technologiques (PAAT) questionnent l’impact de notre époque en pleine révolution numérique et robotique sur nos corporéités et notre humanité, ce qui soulève un certain nombre d'enjeux... / Famous directors, precursors of a new theater, such as Maurice Materlinck or Edward Gordon Craig, wanted to represent life on stage, weaving some conventionnal elements into the stage, instead of just making the best of the bodily presence of the actor on stage. They repressed the very simple imitation of real for some artificial and symbolic theatre questionning the representation of human's figure and the illusion of the living. Getting rid of the actor's body like it is in its private use, in its everyday life, through the use of masks, puppets or even elder technologies as light works or optical effects, heralded the appearence of the new medias on stage. Thereby, emerged back in the 90's, many inorganic characters made with video projections in two or three dimensions, holograms, and the presence of humanoids and androids. We can find that will to replace the actors' bodies with artificial caracters using technological projections in Denis Marleau and Stéphanie Jasmin's video caracters, Michel Lemieux and Victor Pilon's holograms, and again in Oriza Hirata's robots. All these atypical characters, whether they own or not some materiality (or corporality) on stage, or that they are physical or virtual, all of these own different levels of presence according to their integration on stage and dramaturgy, to their self-suffiency and to the interplays they share with each their environnement and the real bodies with which they interact and perform. As we will see, these new theatrical and aesthetics practices that aim to use some Anthropomorphic and Technological Artificial Characters, do question the impact of our time, dealing with digital and robotic revolution, on our corporealities and our humanity, definitively raises a number of issues…
18

Planification de trajectoire pour drones de combat / Path planning of unmanned combat aircraft vehicles

Maillot, Thibault 03 October 2013 (has links)
L’objectif principal de ce travail est l’étude de la planification de trajectoires pour des drones de type HALE ou MALE. Les modèles cinématiques de ces drones sont étudiés. Les drones HALE sont modélisés par le système de Dubins. Pour les drones MALE, le modèle est construit en étudiant le repère cinématique du drone. Nous considérons les problèmes de planification de trajectoires point-point et point-pattern. Il s’agit, à partir de la position courante du drone, de rejoindre un point ou une figure prédéfinie dans l’espace. La planification point-point est abordée sous forme d’un problème de contrôle optimal. Deux méthodes sont proposées pour résoudre le problème point-pattern. D’abord nous présentons la synthèse en temps minimal pour le système de Dubins. Ensuite, nous développons une méthode basée sur le principe de LaSalle. La première méthode est utilisée au sein d’un algorithme de planification pour des drones HALE. La deuxième permet de stabiliser les deux types de drones considérés vers un pattern. Nous proposons une extension des algorithmes de planification développés, basée sur une discrétisation del’espace grâce aux graphes de Voronoï et une méthode de planification discrète, pour construire des trajectoiresdans des milieux encombrés. Nous étudions également le problème de couplage drone/capteur. Il s’agit de calculer une trajectoire permettant de satisfaire les objectifs du drone et de son capteur (une caméra). L’algorithme proposé est construit à partir de la résolution d’un problème quadratique sous contraintes.Dans une seconde partie, nous analysons un problème de contrôle optimal inverse. Celui-ci permet d’améliorer les résultats des méthodes de planification en s’inspirant du comportement des pilotes. Après avoir posé le problème, les résultats théoriques sont exposés et le cas particulier du système de Dubins est étudié en pratique. / This thesis is about path planning for HALE or MALE UAVs (Unmanned Aircraft Vehicles), possibly under mission constraints. As such, the study is performed at the kinematic level : HALE UAVs are represented as Dubins systems, and a model for MALE UAVs is constructed by studying their kinematic frame. In the first part, we tackle the path planning problem for a UAV that must join a target (a point or a pattern), starting from any position. The point to point path planning problem is addressed as an optimal control problem. Regarding the point to pattern path planning problem, two different methods are proposed. The former consists in solving the minimum time synthesis for the Dubins system, in order to obtain a basis for a HALE UAVs planning algorithm. The latter method relies on the LaSalle principle ; it permits to stabilize a HALE or MALE UAV to a pattern.In addition, extensions of the previously developed algorithms to cluttered environnement are provided. This extension is achieved thanks to a space discretization using Voronoi diagrams and a discrete planning method. Finally, the mission constraints are dealt with as a coupling problem between the UAV and its sensors. The proposed algorithm is presented in the form of a constrained quadratic problem.In the second part of this thesis, we want to refine the planning algorithm to get a result closer to trajectories of pilots. In order to do that, we solve an inverse optimal control problem where the cost to find is computed from the experience of pilots. Theoretical results are presented and applied to the particular case of the Dubins system.
19

Radiotherapy X-ray dose distribution beneath retracted patient compensators

Piyaratna, Nelson, University of Western Sydney, Nepean, Faculty of Science and Technology January 1995 (has links)
Computer designed missing tissue and dose compensators have been produced and dosimetrically tested under a linear accelerator 6MV X-ray beam. Missing tissues compensators were developed to correct for patient external contour change only. Target dose compensators were developed to achieve a uniform dose throughout the target volume. With compensators present in the beam, data acquisition was repeated in a water phantom and an Anthropomorphic phantom. Clinically acceptable dose uniformity was achieved within these phantoms. For external contour compensation flat isodose curves were obtained giving an even dose in the region of interest. The dose difference found was within plus/minus 3% only. For the phantoms containing inhomogeneities dose uniformity to target volume was achieved within plus/minus 7%. Prediction of radiation dose was made using a GE Target Series 2 Treatment Planning Computer for each of the phantoms. Validation of the computer predicted dose was carried out using diode and TLD measurements. The measured data in the water tank was consistent with the computer data within plus/minus 2% for external contour changes and for inhomogeneities. The TLD measured results in the anthropomorphic phantom agreed with the planning computer results within 6%. Up to 4% of the difference is explainable due to supra-linearity and scatter effects / Master of Science (Hons) (Physics)
20

Monte Carlo simulations for Homeland Security using anthropomorphic phantoms

Burns, Kimberly A. 17 March 2008 (has links)
After a radiation dispersion device (RDD) event, there may be internally and/or externally contaminated victims. After the RDD event, victims may require immediate medical assistance prior to decontamination. The dose rates to which a healthcare provider is exposed due to the internal and external contamination of the victim were computed using Monte Carlo simulations and five anthropomorphic phantoms. The dose rates to which the victim is exposed due to his/her own external contamination were also computed. For the external contamination modeling, the contamination is assumed to be distributed over the entire exterior of the victimâ s body. The geometrical models of the human body were based on the MIRD stylized phantom. The specific isotopes considered were 60Co, 137Cs, 131I, 192Ir, and 241Am. The surface contamination was generated by creating a 2-mm thick layer adjacent to the outside of the skin of the victim and uniformly sampling the emissions of the radioactive sources throughout this volume. The attending healthcare provider was assumed to be standing 20 cm from mid-torso of the victim. The organ absorbed doses in both the contaminated individual and a healthcare professional were computed. The effective dose to the victim and the attending healthcare professional were computed using the tissue weighting factors in ICRP Publication 60. For example, the dose rate to a reference male healthcare provider from the victim six hours after the inhalation of one ALI by an adipose male victim will be 0.277 mSv/hr. In addition, the air kerma was computed at different distances from the surfaces of the victim phantom and ratios were generated for the air kerma and the effective dose due to the victim from the surface contamination on the victim.

Page generated in 0.057 seconds