[pt] Esta dissertação tem por objetivo realizar a caracterização metrológica de scanners ópticos tridimensionais por projeção de luz estruturada com vistas à aplicação em ensaios de coletes balísticos. Técnicas de digitalização tridimensional vêm ganhando popularidade nas últimas décadas, entretanto o recente emprego de equipamentos de digitalização 3D em ensaios de coletes balísticos constitui uma nova aplicação para estes equipamentos, em especial na caracterização dos traumas originados pelos impactos de projéteis, o que motivou a realização do estudo. A metodologia empregada fundamentou-se nas pesquisas bibliográfica, documental, experimental e de laboratório que tiveram por objetivo coletar dados utilizando scanner por projeção de luz estruturada no contexto de ensaios de coletes balísticos e compará-los com valores de referência. Foram sugeridos processos de alinhamento, segmentação, filtragem e estabelecimento de planos de referência que se mostraram adequados ao tratamento das nuvens de pontos obtidas nos ensaios de coletes balísticos. Os resultados confirmaram os erros sistemáticos relatados na literatura para equipamentos de digitalização por luz estruturada e possibilitaram uma estimativa da incerteza de medição para o equipamento em questão. Concluiuse que os valores críticos de medição de traumas são corretamente medidos pelo instrumento de digitalização 3D e por meio da utilização do método sugerido para tratamento de nuvens de pontos neste contexto. / [en] This dissertation aims at performing the metrological characterization of three-dimensional optical scanners by structured light projection for application in ballistic vest tests. Three-dimensional scanning techniques have been gaining popularity in recent decades, however the recent use of 3D scanning equipment in ballistic vests testing is a new application for these devices, especially in the characterization of traumas caused by projectile impacts, which motivated the realization of the study. The methodology used was based on bibliographic, documentary, experimental and laboratory research aimed at collecting data using a structured light projection scanner in the context of ballistic vests tests and comparing them with reference values. Procedures for alignment, segmentation, filtering and establishment of reference planes were suggested, which proved to be adequate for the treatment of point clouds obtained from ballistic vest tests. The results confirmed the systematic errors reported in the literature for structured light scanning equipment and made it possible to estimate the measurement uncertainty for the equipment in question. It was concluded that the critical trauma measurement values are correctly measured by the 3D scanning instrument and by using the suggested method for treating point clouds in this context.

Existing residential and small commercial buildings now represent the greatest opportunity to improve building energy efficiency. Building energy simulation analysis is becoming increasingly important because the analysis results can assist the decision makers to make decisions on improving building energy efficiency and reducing environmental impacts. However, manually measuring as-is conditions of building envelops including geometry and thermal value is still a labor-intensive, costly, and slow process. Thus, the primary objective of this research was to automatically collect and extract the as-is geometry and thermal data of the building envelope components and create a gbXML-based building geometry model. In the proposed methodology, a rapid and low-cost data collection hardware system was designed by integrating 3D laser scanners and an infrared (IR) camera. Secondly, several algorithms were created to automatically recognize various components of building envelope as objects from collected raw data. The extracted 3D semantic geometric model was then automatically saved as an industry standard file format for data interoperability. The feasibility of the proposed method was validated through three case studies. The contributions of this research include 1) a customized low-cost hybrid data collection system development to fuse various data into a thermal point cloud; 2) an automatic method of extracting building envelope components and its geometry data to generate gbXML-based building geometry model. The broader impacts of this research are that it could offer a new way to collect as is building data without impeding occupants’ daily life, and provide an easier way for laypeople to understand the energy performance of their buildings via 3D thermal point cloud visualization.

Master of Science / Department of Agricultural Economics / Ted C. Schroeder / It is clear that consumers rely on certain experience and credence attributes when purchasing beef products from the retail meat case. It is essential for all beef industry sectors to recognize the complexity of consumers buying behavior. The objective of this research is to determine if there are incentives to brand beef products and to determine what types of brands entertain price premiums as well as what levels these premiums exists. Retail scanner data, collected from 2004 through March 2009, was used for the evaluation of branded beef and also to determine what other product attributes benefit with a premium to six specific cuts of beef. Hedonic models were estimated using Ordinary Least Squares regressions to determine which variables affected the overall price per pound of each of the six cuts of beef chosen to analyze. Results indicate that there is an incentive to brand beef products at the retail level. Local, regional, national, and store brands all garnered premiums across the six models for the beef cuts, steak, roast, ground, strip, cube, and ribs in relation to products with no brand. Other variables that garnered premiums across all models include organic, Prime quality grade, and Kosher and Kosher-Glatt religious labels. Steak exhibited the highest mean price per pound followed by cube, roast, strip, ribs and ground. In all of the models estimated explaining price variation, there were few coefficients that were statistically insignificant. Additional modeling was done to determine if outlier observations were influencing the regression results. The sensitivity analyses resulted in small changes in parameter estimates indicating the identified influential observations did not have undue impact on the parameter estimates.

Doctor of Philosophy / Department of Biological & Agricultural Engineering / Naiqian Zhang / Soil surface roughness is a major factor influencing soil erosion by wind and water. Studying surface roughness requires accurate Digital Elevation Model (DEM) data. A vehicle-based laser measurement system was developed to generate high-resolution DEM data. The system consisted of five units: a laser line scanner to measure the surface elevation, a gyroscope sensor to monitor the attitude of the vehicle, a real-time kinematic GPS to provide the geographic positioning, a frame-rail mechanism to support the sensors, and a data-acquisition and control unit. A user interface program was developed to control the laser system and to collect the sensors data through a field laptop. Laboratory experiments were conducted to evaluate the performance of the laser sensor on different type of targets. The results indicated that the laser measurement on a white paper had the least variability than that on other targets. The laser distance measurement was calibrated using the data acquired on the white paper. Static accuracy tests of the gyroscope sensor on a platform that allowed two-axis rotations showed that angle measurement errors observed in combined pitch/roll rotations were larger than those in single rotations. Within ±30° of single rotations, the measurement errors for pitch and roll angles were within 0.8° and 0.4°, respectively. A model to study the effect of attitude measurement error on elevation measurement was also developed. DEM models were created by interpolating the raw laser data using a two-dimensional, three-nearest neighbor, distance-weighted algorithm. The DEM models can be used to identify shapes of different objects. The accuracy of the laser system in elevation measurement was evaluated by comparing the DEM data generated by the laser system for an unknown surface with that generated by a more accurate laser system for the same surface. Within four replications, the highest correlation coefficient between the measured and reference DEMs was 0.9371. The correlation coefficients among the four replications were greater than 0.948. After a median threshold filter and a median filter were applied to the raw laser data before and after the interpolation, respectively, the correlation coefficient between the measured and reference DEMs was improved to 0.954. Correlation coefficients of greater than 0.988 were achieved among the four replications. Grayscale images, which were created from the intensity data provided by the laser scanner, showed the potential to identify crop residues on soil surfaces. Results of an ambient light test indicated that neither sunlight nor fluorescent light affected the elevation measurement of the laser system. A rail vibration test showed that the linear rail slightly titled towards the laser scanner, which caused small variations in the pitch angle. A preliminary test on a bare soil surface was conducted to evaluate the capability of the laser system in measuring the DEM of geo-referenced surfaces. A cross-validation algorithm was developed to remove outliers. The results indicated that the system was capable of providing geo-referenced DEM data.

La tomodensitométrie (TDM) permet d'obtenir, et ce de façon non invasive, une image tridimensionnelle de l'anatomie interne d'un sujet. Elle constitue l'évolution logique de la radiographie et permet l'observation d'un volume sous différents plans (sagittal, coronal, axial ou n'importe quel autre plan). La TDM peut avantageusement compléter la tomographie d'émission par positrons (TEP), un outil de prédilection utilisé en recherche biomédicale et pour le diagnostic du cancer. La TEP fournit une information fonctionnelle, physiologique et métabolique, permettant la localisation et la quantification de radiotraceurs à l'intérieur du corps humain. Cette dernière possède une sensibilité inégalée, mais peut néanmoins souffrir d'une faible résolution spatiale et d'un manque de repère anatomique selon le radiotraceur utilisé. La combinaison, ou fusion, des images TEP et TDM permet d'obtenir cette localisation anatomique de la distribution du radiotraceur. L'image TDM représente une carte de l'atténuation subie par les rayons-X lors de leur passage à travers les tissus. Elle permet donc aussi d'améliorer la quantification de l'image TEP en offrant la possibilité de corriger pour l'atténuation. L'image TDM s'obtient par la transformation de profils d'atténuation en une image cartésienne pouvant être interprétée par l'humain. Si la qualité de cette image est fortement influencée par les performances de l'appareil, elle dépend aussi grandement de la capacité de l'algorithme de reconstruction à obtenir une représentation fidèle du milieu imagé. Les techniques de reconstruction standards, basées sur la rétroprojection filtrée (FBP, filtered back-projection), reposent sur un modèle mathématiquement parfait de la géométrie d'acquisition. Une alternative à cette méthode étalon est appelée reconstruction statistique, ou itérative. Elle permet d'obtenir de meilleurs résultats en présence de bruit ou d'une quantité limitée d'information et peut virtuellement s'adapter à toutes formes de géométrie d'acquisition. Le présent mémoire se consacre à l'étude de ces algorithmes statistiques en imagerie TDM et à leur implantation logicielle. Le prototype d'imageur TEP/TDM basé sur la technologie LabPET[indice supérieur TM] de l'Université de Sherbrooke possède tous les pré-requis pour bénéficier de ces nombreux avantages.

The plants and animals that inhabit river channels may act as zoogeomorphic agents affecting the nature and rates of sediment recruitment, transport and deposition. The impact of benthic-feeding fish, which disturb bed material sediments during their search for food, has received little attention, even though benthic feeding species are widespread in rivers and may collectively expend significant amounts of energy foraging across the bed. A series of experiments were conducted to investigate the impacts of benthic feeding fish on the structure and composition of gravel-bed river sediments, and the implications for bed material transport. An ex-situ experiment was conducted to investigate the impact of a benthic feeding fish (European Barbel Barbus barbus) on particle displacements, bed sediment structures, gravel entrainment and transport fluxes. In a laboratory flume, changes in bed surface topography were measured and grain displacements examined when an imbricated, water-worked bed of 5.6-16 mm gravels was exposed to feeding juvenile Barbel. For substrates that had been exposed to feeding fish and control substrates which had not, grain entrainment rates and bedload fluxes were measured under a moderate transport regime. On average, approximately 37% of the substrate, by area, was modified by foraging fish during a four-hour treatment period, resulting in increased microtopographic roughness and reduced particle imbrication. Structural changes caused by fish increased bed load flux by 60% under entrainment flows, whilst on average the total number of grains transported during the entrainment phase was 82% higher from substrates that had been disturbed by Barbel. An ex-situ experiment utilising Barbel and Chub Leuciscus cephalus extended this initial study by considering the role of fish size and species as controls of sediment disturbance by foraging. Increasing the size of Barbel had a significant effect on measured disturbance and bedload transport. Specifically, the area of disturbed substrate, foraging depth, microtopographic roughness and sediment structure all increased as functions of fish size, as did bedload flux and total transported mass. In a comparison of the foraging effects of like-sized Barbel and Chub 8-10 in length, Barbel foraged a larger area of the riverbed and had a greater impact on microtopographic roughness and sediment structure. Foraging by both species was associated with increased sediment transport, but the bed load flux after foraging by Barbel was 150% higher than that following foraging by Chub and the total transported mass of sediment was 98% greater. An in-situ experiment quantified the effects of foraging fish, primarily Cyprinids (specifically Barbel and Chub), on gravel-river bed sediment structures, surface grain-size distributions, sediment transport fluxes and grain entrainment in the River Idle, Nottinghamshire, UK. This was achieved by installing large experimental sediment trays seeded with food at typical densities. The experiments yielded data about 1) topographic and structural differences between pre- and post-feeding substrates using DEMs interpolated from laser scans, 2) modifications to surface and sub-surface grain-size distributions as a function of fish foraging and 3) differences in sediment entrainment from water-worked substrates exposed to feeding fish and control substrates, without fish. Small sections of the substrate trays were recovered in tact from the field and for substrates that had been exposed to feeding fish and control substrates which had not, grain entrainment rates and bedload fluxes were measured under a moderate transport regime in the laboratory. On average, approximately 74% of the substrate, by area, was modified by foraging fish during a twelve-hour period, resulting in increased microtopographic roughness and substrate coarsening which had significant implications for bed material transport during the steady entrainment flow. Together, results from these experiments indicate that by increasing surface microtopography, modifying the composition of fluvial substrates and undoing the naturally stable structures produced by water working, foraging can influence sediment transport dynamics, predominately by increasing the mobility of river bed materials. The implication of this result is that by influencing the quantity of available, transportable sediment and entrainment thresholds, benthic feeding may affect sediment transport fluxes in gravel-bed rivers. In addition, three discrete studies were performed alongside the core experiments described above. A quantitative examination of habitat conditions favoured by feeding Barbel was conducted in the River Idle (Nottinghamshire, UK) which served to supplement existing literature pertaining to Barbel ecology, and inform experimental design during the core experiments. Two further studies considered the potential importance of foraging as a zoogeomorphic activity in terms of spatial extent, at a variety of scales, thereby extending core experiments to larger spatial scales in-situ.

Signal crayfish are an internationally widespread invasive species that can have important detrimental ecological impacts. This thesis aims to determine whether signal crayfish have the potential to also impact the physical environment in rivers. A series of experiments were undertaken in purpose-built still-water aquaria using a laser scanner to obtain Digital Elevation Models (DEMs) of narrowly-graded gravel surfaces before and after exposure to crayfish. The difference between DEMs was used to quantify volumetric changes in surface topography due to crayfish activity. Two distinct types of topographic change were identified. The first was the construction of pits and mounds which resulted in an increase in surface roughness and grain exposure. The second was the rearrangement of surface material caused by crayfish brushing past grains when walking and foraging, reorientating grains and altering friction angles. A series of 80 flume runs were undertaken to quantify alterations made by crayfish to water-worked, as well as loose, gravel substrates at low velocity flows. Crayfish significantly altered the structure of water-worked substrates, reversing the imbrication of surface grains to a more random arrangement. Surfaces were entrained at a relatively high velocity flow subsequent to crayfish activity in order to directly link topographic and structural alterations to substrate stability. Nearly twice as many grains were mobilised from surfaces which had been disturbed by crayfish in comparison to control surfaces that were not exposed to crayfish. A field investigation aimed to determine the potential significance of the geomorphic impact of crayfish in rivers. Signal crayfish were tracked through a 20 m reach of a small, lowland alluvial river for 150 days using a Passive Integrated Transponder (PIT) system. Crayfish were active throughout the channel, although their activity became limited as water temperature dropped and flow stage increased. Substrate was not an important determinant of crayfish activity at this scale. Instead, crayfish tended to be found along the inner bank of a meander bend where there was a substantial cover of macrophytes. Consequently, signal crayfish were active for extended periods on substrates of a similar size to those that they could disturb in flume experiments. These results suggest that signal crayfish could have important geomorphic effects in rivers, disturbing bed structures and increasing the mobility of coarse material. This may have important implications for both the management of some rivers and benthic organisms that reside on the river bed.

Introduction: Orthodontists increasingly rely on digital models in clinical practice. The ability of modern scanners to articulate digital models must be scientifically evaluated. Methods:Twenty five digital articulated models were produced from four digital scanners in five experimental groups. The resulting inter-arch measurements were compared to the gold standard. An acceptable range of 0.5mm more or less than the gold standard was used for evaluation. Results: iTero® and iTero® Element yielded all acceptable inter-arch measurements. The 3M™ True Definition and Ortho Insight 3D® with Regisil® bite registration produced four of six acceptable inter-arch measurements. The Ortho Insight 3D® with Coprwax ™ bite registration yielded three of six acceptable inter-ach measurements. Conclusions: The iTero® and iTero® Element produced the most accurately articulated models. The 3M™ True Definition and Ortho Insight 3D® with Regisil® were the next most accurate. The Ortho Insight 3D® scanner with Coprwax ™ was the least accurate method tested.

The growth of networks around the world has also given rise to threats like viruses and Trojans. This rise in threats has resulted in counter measures for these threats. These counter measures are in the form of applications called firewalls or IDS. The incorporation of these applications in the network results in some delay in communications. The aim of the experiment in this thesis is to measure the delay introduced by such a firewall in the best case and compare it with the communication done on a network without such an application. These experiments are done using a special miniature computer called the net4801 with an embedded operating system and the packet scanning application (firewall or IDS) executing on it.

I have always preferred the journey to the destination. When I was growing up, my family drove back and forth between Florida and New York every summer. My father did the driving, my mother sat next to him, and my older brother and sister sat in the back seat. This left the cavernous back of the family station wagon for me and the luggage. There was no radio, very little conversation, and I didn't sleep. I spent these summer trips staring for endless hours, out of the back window of the car, transfixed on the expanse of open road behind us. Since I bought my first car I have traveled the country, and since I borrowed my first camera I have been documenting my travels. The miles of highway between destinations, the quiet hours, have interested me as much as, and often more than, the destination. The images in my exhibition are intended to document the journey.These photographs are sequential montages with each photo composed of multiple overlapping images that bleed into one another making an expansive image of open space. Each finished product represents a panorama, but unlike traditional panoramic images, forward, not lateral, movement defines them. Each new frame advances the journey while maintaining a connection with the frame before it. The ambiguity and lack of detail refer to the experience and the quietness of the elapsed time the journey has taken. The finished images reference the journey without necessarily referencing the destination. The presentation size is meant to fill the viewers' vision, making an all-encompassing experience.