In order to obtain chemical evidence concerning the configuration of free alkyl radicals, 1-(carbo-t-butylperoxy)-cis- and trans-1,4-dimethylcyclohexane and exo- and endo-2-(carbo-t-butylperoxy)-2-methylnorbornane have been synthesized, and their decomposition rates and products determined. The cis- and trans-cyclohexyl peresters undergo thermal decomposition at 60° in cumene at essentially the same rates (cis isomer ∆H⁺ = 27.5 kcal/ mole, ∆S⁺ = 5.07 eu; trans isomer ∆H⁺ = 27.8 kcal/mole, ∆S⁺ = 5.75 eu) and with direct formation of 1,4-dimethylcyclohexyl radicals, carbon dioxide, and t-butoxy radicals. The products, cis- and trans-1,4-dimethylcyclohexane, 1,4-dimethylcyclohexene, and 4-methylmethylenecyclohexane, formed from the 1,4-dimethylcyclohexyl radicals in degassed cumene, are the same from both precursors. In the presence of oxygen in 1,2-dimethoxyethane (glyme) or 25 ml Freon TF:1 ml glyme, both the cis and trans peresters gave identical yields (after reduction) of trans-1,4-dimethylcyclohexanol (58%) and cis-1,4-dimethylcyclohexanol (42%) at oxygen pressures from 1 to approximately 600 atm. A common intermediate is thus indicated. In cumene at 75°, exo-2-(carbo-t-butylperoxy)-2-methylnorbornane decomposes 6.6 - 6.7 times faster than its endo isomer. The activation parameters are ∆H⁺ = 27.9 kcal/mole, ∆S⁺ = 6.31 eu, and ∆H⁺ = 30.3 kcal/mole, ∆S⁺ = 9.33 eu, respectively. The products, exo- and endo-2-methylnorbornane, 2-methyl-2-norbornene, and 2-methylenenorbornane, resulting from 2-methyl-2-norbornyl radicals in degassed cumene, are essentially the same from either isomeric source. The same ratio of exo- to endo-2-methyl-2-norbornyl hydroperoxide (15%:85%) is formed from either perester in the presence of oxygen at pressures up to -600 atm. Unlike the apparently unique case of distinctly different cis- and trans-9-decalyl radicals, the alkyl radicals from the decomposition of isomeric norbornyl and cyclohexyl peresters have a single configuration or they invert much faster than they react with oxygen. The results suggest that if radicals with a stereochemical "memory" of their origin exist in these systems, their lifetimes are of the order of 10⁻¹⁰ seconds or less. For the 1,4-dimethylcyclohexyl radical, hydrogen atom transfer and reaction with oxygen were found to occur preferentially (82% and 58%, respectively) from an axial direction. On the other hand, cumene and oxygen react with the 2-methyl-2-norbornyl radical predominantly from an exo direction (90% and 85%, respectively). The carbonylation of tetrahydrolinalool, and several synthetic routes to 1-alkyl-4-t-butylcyclohexanecarboxylic acids also have been explored. / Science, Faculty of / Chemistry, Department of / Graduate

The prevalence of obesity has necessitated developing safe and convenient tools for timely assessing and monitoring this condition for a broad range of population. Three-dimensional (3D) body imaging has become a new mean for obesity assessment. Moreover, it generates body shape information that is meaningful for fitness, ergonomics, and personalized clothing. In the previous work of our lab, we developed a prototype active stereo vision system that demonstrated a potential to fulfill this goal. But the prototype required four computer projectors to cast artificial textures on the body which facilitate the stereo-matching on texture-deficient images (e.g., skin). This decreases the mobility of the system when used to collect a large population data. In addition, the resolution of the generated 3D~images is limited by both cameras and projectors available during the project. The study reported in this dissertation highlights our continued effort in improving the capability of 3Dbody imaging through simplified hardware for passive stereo and advanced computation techniques. The system utilizes high-resolution single-lens reflex (SLR) cameras, which became widely available lately, and is configured in a two-stance design to image the front and back surfaces of a person. A total of eight cameras are used to form four pairs of stereo units. Each unit covers a quarter of the body surface. The stereo units are individually calibrated with a specific pattern to determine cameras' intrinsic and extrinsic parameters for stereo matching. The global orientation and position of each stereo unit within a common world coordinate system is calculated through a 3Dregistration step. The stereo calibration and 3Dregistration procedures do not need to be repeated for a deployed system if the cameras' relative positions have not changed. This property contributes to the portability of the system, and tremendously alleviates the maintenance task. The image acquisition time is around two seconds for a whole-body capture. The system works in an indoor environment with a moderate ambient light. Advanced stereo computation algorithms are developed by taking advantage of high-resolution images and by tackling the ambiguity problem in stereo matching. A multi-scale, coarse-to-fine matching framework is proposed to match large-scale textures at a low resolution and refine the matched results over higher resolutions. This matching strategy reduces the complexity of the computation and avoids ambiguous matching at the native resolution. The pixel-to-pixel stereo matching algorithm follows a classic, four-step strategy which consists of matching cost computation, cost aggregation, disparity computation and disparity refinement. The system performance has been evaluated on mannequins and human subjects in comparison with other measurement methods. It was found that the geometrical measurements from reconstructed 3Dbody models, including body circumferences and whole volume, are highly repeatable and consistent with manual and other instrumental measurements (CV < 0.1$%, R2>0.99). The agreement of percent body fat (%BF) estimation on human subjects between stereo and dual-energy X-ray absorptiometry (DEXA) was found to be improved over the previous active stereo system, and the limits of agreement with 95% confidence were reduced by half. Our achieved %BF estimation agreement is among the lowest ones of other comparative studies with commercialized air displacement plethysmography (ADP) and DEXA. In practice, %BF estimation through a two-component model is sensitive to body volume measurement, and the estimation of lung volume could be a source of variation. Protocols for this type of measurement should still be created with an awareness of this factor. / text

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Stereopsis is the process of inferring the distance to objects from two or more images. It has applications in areas such as: novel-view rendering, motion capture, autonomous navigation, and topographical mapping from remote sensing data. Although it sounds simple, in light of the effortlessness with which we are able to perform the task with our own eyes, a number of factors that make it quite challenging become apparent once one begins delving into computational methods of solving it. For example, occlusions that block part of the scene from being seen in one of the images, and changes in the appearance of objects between the two images due to: sensor noise, view dependent effects, and/or differences in the lighting/camera conditions between the two images. Global stereopsis algorithms aim to solve this problem by making assumptions about the smoothness of the depth of surfaces in the scene, and formulating stereopsis as an optimization problem. As part of their formulation, these algorithms include a function that measures the similarity between pixels in different images to detect possible correspondences. Which of these match cost functions work better, when, and why is not well understood. Furthermore, in areas of computer vision such as segmentation, face detection, edge detection, texture analysis and classification, and optical flow, it is not uncommon to use colour spaces other than the well known RGB space to improve the accuracy of algorithms. However, the use of colour spaces other than RGB is quite rare in stereopsis research. In this dissertation we present results from two, first of their kind, large scale studies on global stereopsis algorithms. In the first we compare the relative performance of a structured set of match cost cost functions in five different global stereopsis frameworks in such a way that we are able to infer some general rules to guide the choice of which match cost functions to use in these algorithms. In the second we investigate how much accuracy can be gained by simply changing the colour representation used in the input to global stereopsis algorithms.

Measurements performed from stereo reconstruction can be obtained with a high accuracy with correct calibrated cameras. A stereo camera rig mounted in an outdoor environment is exposed to temperature changes, which has an impact of the calibration of the cameras. The aim of the master thesis was to investigate the thermal impact of a calibrated stereo camera rig. This was performed by placing a stereo rig in a temperature chamber and collect data of a calibration board at different temperatures. Data was collected with two different cameras and lensesand used for calibration of the stereo camera rig for different scenarios. The obtained parameters were plotted and analyzed. The result from the master thesis gives that the thermal variation has an impact of the accuracy of the calibrated stereo camera rig. A calibration obtained in one temperature can not be used for a different temperature without a degradation of the accuracy. The plotted parameters from the calibration had a high noise level due to problems with the calibration methods, and no visible trend from temperature changes could be seen.

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The depth information is a fundamental factor in stereo imaging. The depth information of an object can be associated to the horizontal shift (with respect to the location in the parallax image) in a simple linear relation. Therefore, we can generate a stereo video by combining a regular monoscopic video with an artificial parallax video implemented with a designed horizontal shift. In this research, the manmade horizontal shift is designed according to the pixel translations of the monoscopic video obtained by the optical flow computation algorithm. Optical flow proposed by Horn and Schunck was originally developed in the field of computer vision for the application of moving detection. Following this flow computation algorithm, a vector segmentation algorithm is applied to the flow field for grouping effects associated to the foreground. Finally, some merging procedures are applied to get a better foreground mask. With this foreground mask,the parallax video is then generated for creating our artificial stereo video.

In Part I, the C.D. spectra of a number of 3-keto and 20-keto steroids are reported. The 3-keto steroids were comprised of two series of compounds. For one series, the conformationally transmitted effects of olefinic centers located in, or exocyclic to, rings B and C were investigated. It was found that these effects were reflected in the C.D. spectra when the double bond was located in ring B, but not when the double bond was located in ring C. Further, no correlation could be made between the relative rates of alkali-catalyzed benzaldehyde condensation and the C.D. data. For the other series, the conformations of ring A in a number of steroids substituted at the 2- and 4- positions are discussed. The C.D. results are in agreement with other evidence on this subject, and suggest that a 1,3-diaxial methyl interaction leads to flattening of ring A. For the Δ⁵- 4,4-dimethyl-3-keto steroids, a non-chair conformation is indicated, but a distinction between a boat and a flat chair conformation cannot be made . For 2 α -bromo-4,4-dimethylcholest-5-en-3-one, a conformational equilibrium is suggested. The 20-keto steroids were comprised of a large number of 16-substituted pregnanone and 17 α -pregna-none derivatives. The C.D. spectra of the 16,17 trans compounds and the 16α , 17α -cis-compounds were similar to those of the 16-unsubstituted parent compounds. Modifications in rings A and B had little effect upon the dichroism of the 20-keto group. The C.D. spectra of the 16β, 17β-compounds were very sensitive to the nature of the 16β -substituent, These results are interpreted in terms of the preferred conformation of the 17β -acetyl group. Finally, the C.D. spectra of a number of 16, 17-epoxy-20-keto steroids are reported and discussed with reference to the "reversed octant rule". In Part II, the structural determination of the mould metabolite, hirsutic acid C, is reported. The functional groups were established from chemical information; however the X-ray analysis of the p-bromo-phenacyl ester was required to reveal the novel ring system. During the X-ray irradiation an unusual solid-phase rearrangement occurred, transforming the α-epoxy hydroxyl system of p-bromophenacyl hirsutate to a β -hydroxy ketone system without disrupting the crystal structure. The X-ray analysis revealed a 50:50 mixture of starting material and rearrangement product. A combination of the X-ray and the chemical data was required to complete the structural determinations of both products. The generality of the rearrangement process was investigated. It occurred with methyl hirsutate and dihydromethylhirsutate, but not with hirsutic acid. It could not be induced thermally. It did not occur with the steroids 3 α - and 3 β -hydroxy-4 β, 5-epoxy-5β-cholestane. The rearrangement process is probably controlled by the nature of the molecular packing and hydrogen-bond formation. In Part III, the biogenetic-type syntheses of a number of acetate-derived aromatic compounds are reported. A discussion of the preparation of the condensed polypyrone intermediates is given, and in particular the synthesis of the tetrapyrone, 4-hydroxy-9-methyl-2,5,7,12-tetraketo 1,6,8,11-tetra-oxachrysene from the condensation of bis (2,4-dichlorophenyl) malonate and the tripyrone, 7-methyl-1-hydroxy-3,5,10-triketo 4,6,9-trioxaphenanthrene is reported. Treatment of the tripyrone with methanolic potassium hydroxide solution resulted in ring opening to form a poly- β-keto chain, and subsequent aldol-type condensation to give aromatic compounds representative of the naturally-occurring 6,8 dihydroxy-isocoumarins and C-acetylorsellinic acid. Treatment with methanolic magnesium methoxide solution gave aromatic compounds derivable from different cyclization modes of the poly- β-keto chain. Among the compounds isolated were two representative of the naturally-occurring curvulinic acid and the 5,7-dihydroxychromones respectively. Structural assignments were made largely on the basis of the characteristic spectral properties of the compounds. / Science, Faculty of / Chemistry, Department of / Graduate

Recently, stereo vision has been widely used in many applications, and depth map is important information in stereo vision. In general, depth map can be generated from the disparity using stereo matching based on two input images of different viewing positions. Due to the large computation complexity, software implementation of stereo matching usually cannot achieve real-time computation speed. In this thesis, we propose hardware implementations of stereo matching to speed up the generation of depth map. The proposed design uses a global optimization method, called dynamic programming, to find the disparity based on two input images: left image and right image. It consists of three main processing steps: matching cost computation (M.C.C.), minimum cost accumulation (M.C.A.), and disparity optimization (D.O.). The thesis examines the impact of different pixel operation orders in M.C.C and M.C.A modules on the cost of hardware. In the design of D.O. module, we use two different approaches. One is a Systolic-Like structure with streaming processing, and the other is memory-based design with low hardware cost. The final architecture with pipelining and memory-based D.O. can save a lot of hardware cost and achieve high throughput rate for processing a sequence of image pairs.

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