This Master’s thesis is dedicated to innovative structural design of the supporting frame rear axle of a small urban utility vehicle. The frame allows you to change the wheel base by sliding rear axle so the car can be used in its short or long version. The main part begins with description of the design solutions and continues with selection of a solution and description of its main parts. The work is finished by description of the current state of production and a list of expected expenses.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第15312号 / 工博第3191号 / 新制||工||1480(附属図書館) / 27790 / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 井合 進, 教授 田村 武, 教授 岡 二三生 / 学位規則第4条第1項該当

Abstract Type XIII collagen is a type II transmembrane protein which is expressed in many tissues throughout development and adult life. It is located in focal adhesions of cultured cells and in the adhesive structures of tissues such as the myotendinous junctions in muscle, intercalated discs in the heart and the cell-basement membrane interphases. To further characterize the function of this protein, we generated transgenic mice overexpressing it in normal and mutant forms. A large in-frame deletion in the COL2 domain of type XIII collagen led to synthesis of truncated α1(XIII) chains in transgenic mice, disrupting the assembly of normal type XIII collagen trimers. Fibroblasts derived from the mutant mice expressed shortened α1(XIII) chains, and no intracellular accumulation of the mutant protein was detected, suggesting that the mutant molecules were expressed on the cell surface. Transgene expression led to an embryonally lethal phenotype in offspring from heterozygous mating at two distinct stages of development. The early phenotype fetuses died due to the lack of chorioallantoic fusion and functioning placenta at 10.5 dpc, while the death of the late phenotype fetuses was caused by cardiac and placental defects around 13.5 dpc. The phenotype resembles closely several other cell adhesion molecule mutants, indicating that type XIII collagen has an essential role in certain adhesive interactions that are necessary for normal development. Mice overexpressing type XIII collagen with or without a point mutation developed postnatally an unexpected skeletal phenotype marked by a massive increase in bone mass. The cortical bone cross-sectional area and volumetric bone mineral density were highly increased, but trabecular bone volume was not significantly altered. The bone formation rate was several times higher in the mutant mice than in their normal littermates, while the osteoclast number and resorption activity were normal. Type XIII collagen was expressed highly in primary osteoblasts derived from the transgenic mice. Overexpression of type XIII collagen in osteoblasts enhanced both cell proliferation and differentiation while lack of it had opposite effects. Furthermore, mutant cells responded to mechanical strain differently than wild-type cells. The findings suggest that type XIII collagen has an important role in bone modeling, and it may in particular have a function in coupling the regulation of bone mass to mechanical usage.

Comme tous les milieux amorphes, lorsque les milieux granulaires sont soumis à une contrainte suffisamment importante, ils présentent de la localisation de la déformation. Lors de la rupture d'un matériau granulaire, on assiste ainsi à la formation de bandes de cisaillement. Cette transition solide-liquide est encore largement incomprise. Dans le but de caractériser cette dynamique et d'observer des précurseurs à la rupture, nous avons développé un dispositif expérimental original de test biaxial en déformation plane. Il consiste à appliquer une compression uni-axiale quasi-statique à un échantillon granulaire modèle constitué de micro-billes de verre soumis à une pression de confinement. La compréhension des mécanismes physiques mis en jeu nécessite d'observer de très faibles déformations, pour cela nous utilisons une méthode interférométrique basée sur la diffusion multiple de la lumière. Lors des expériences, nous avons mis en évidence deux types de déformation distincts caractérisés par une dynamique et des angles caractéristiques différents. Avant la rupture, on observe une dynamique intermittente de micro-bandes organisées en réseau. Il s'agit de la première observation de ce type de dynamique que nous interprétons comme une cascade de réarrangements localisés de type Eshelby. Cette dynamique collective émergente ne fait pas intervenir la friction et s'inscrit dans le cadre de la plasticité des amorphes. À la rupture, nous observons des bandes permanentes dont l'inclinaison est donnée par l'angle de friction interne (Mohr-Coulomb). Au cours de la charge, ces deux types de déformation cohabitent, révélant une transition complexe d'un écoulement plastique à une localisation sur des bandes frictionnelles. / Granular materials belong to amorphous media and display localization of deformation when submitted to a large enough stress. Indeed, shear bands appear at the failure of a granular medium and this solid/liquid transition is still an open question. In order to characterize this dynamics and to observe rupture precursors, we developed an experimental device of plane strain biaxial test. It consists in a quasistatic uniaxial compression of a model granular sample made of glass microbeads under confinement pressure. We used an original interferometric method based on multiple light scattering to probe tiny deformations. Our experiments evidenced two types of deformation, those two behaviors differ in their dynamics and their characteristic angle. We observed for the first time an organization of the deformation in an intermittent microbands network from the early stage of the loading. We interpreted this behavior as a cascade of Eshelby-like localized rearrangements. This emerging collective dynamics is not due to friction and can be understood in the framework of amorphous media plasticity. At the failure, permanent shear bands of inclination governed by internal friction angle (Mohr-Coulomb) appear. During the loading, both types of strain coexist displaying a complex transition between plastic flow and frictional shear bands.

Le bois est utilisé comme matériau absorbeur de chocs dans les conteneurs de transport du CEA. La simulation numérique des crashs tests de ces structures fait partie intégrante de leur développement et de leur validation. Il est donc impératif d’étudier expérimentalement les différentes essences de ces matériaux afin de mettre en évidence leurs caractéristiques et de déterminer leurs lois de comportement. En effet, ces données sont absolument nécessaires afin d’alimenter les modèles numériques retenus pour les simulations. A partir des modèles existants dans les codes de calcul ou par la programmation de lois de comportement spécifiques prenant en compte le paramètre vitesse de déformation, le comportement de ce matériau cellulaire a été simulé afin de participer à ce programme de validation produit. / Wood is usually used as material absorber of shocks in CEA’s containers. Numerical simulation of crash-test of these structures is an integral part of their development and their validation. It is thus imperative to experimentally study various type of wood to highlight their characteristics and determine their behavior. Indeed, these data are absolutely necessary to feed the numerical models chosen for the simulations. From the existing models in simulation tools or by programming specific laws, both taking into account the parameter strain rate, the behavior of this cellular material was modeled to participate in this product program.

Doctor of Philosophy / Department of Civil Engineering / Asadollah Esmaeily / Over the past 30 years, FRP composites (carbon, glass, or aramid fibers) have arisen as a method of retrofitting existing reinforced concrete structures to bring them up to current code standards of confinement and ductility. The development of stress-strain models for FRP confined concrete began with the adaptation of steel confinement models then progressed to models specifically developed based on test results from FRP confined specimens. State of the art stress-strain models for FRP confined concrete models may now be validated against a wide variety of published experimental results. Recent publications show researchers branching out and looking at other aspects of FRP confined concrete behavior, including the impact of sustained service loads on long term and ultimate behavior. An experimental program which examines the effects of sustained service loading on the ultimate axial performance of FRP confined concrete is presented. The program's purpose is to determine whether or not a material model developed without the presence of a sustained load accurately predicts the ultimate stress-strain response of FRP confined concrete previously subjected to a sustained service load. Equipment and procedures were developed to model the critical events in a building life cycle: construction, sustained service loading, minor critical events, rehabilitation, and ultimate performance. Varying the order of these events produces a simulated life cycle allowing analysis of the impact of strain history on ultimate performance. The results of the experimental program indicate that the presence of a sustained service load changes the expected failure mode from FRP rupture to FRP de-lamination and the stress-strain response of a specimen is approximately 10% below published models when sustained service loads are included in the life cycle. A comprehensive modeling process is proposed for modeling significant events in a structure's life cycle. Impacts on earthquake engineering and reliability studies are addressed and future research suggested. This research shows that life cycle modeling can improve the design and rehabilitation of structures so that they meet safety requirements in future seismic events.

D. Phil. / Conventional internal wind tunnel balances are designed and constructed to accommodate foil strain gauges which measure the deformation (strain) of the material. Foil strain gauge balances are known to be affected by electromagnetic interference and temperature. These balances are expensive and their manufacture is time consuming. With an increasing demand for higher accuracy, stiffness, increased resolution and temperature compensation, current balance designs are becoming inadequate. To overcome identified balance deficiencies a research programme in the application of optical Bragg gratings to wind tunnel balances was initiated. In this programme a new concept of using optical fibre Bragg grating sensors, with the advantage of using mechanical amplification to increase sensitivity, and the implementation of temperature compensation techniques was demonstrated on a simulated two component balance.

Philosophiae Doctor - PhD / Mycobacterium tuberculosis, the causative agent of tuberculosis, is estimated to infect approximately one-third of the world’s population and is responsible for around 2 million deaths per year. The disease is endemic in South Africa which has one of the world’s highest tuberculosis incidence and death rates. The M. tuberculosis Beijing genotype are characterised by having an enhanced virulence capability over other M. tuberculosis strains and are the predominant strain observed in the Western Cape of South Africa. DNA methylation is a largely untapped area of research in M.tuberculosis and has been poorly described in the literature especially given its connection to virulence despite it being well characterised along with its role in virulence in other pathogenic bacteria such as E.coli. The overall aim was to characterise a global DNA methylation profile for two M. tuberculosis Beijing strains, hyper-virulent and hypo-virulent, using single molecule real time sequencing data technology. Moreover, to determine if adenine methylation in promoter regions has a possible functional role. This study identified and characterised the DNA methylation profile at the single nucleotide resolution in these strains using Pacific Biosciences single molecule real time sequencing data. A computational approach was used to discern DNA methylation patterns between the hyper and hypo-virulent strains with a view of understanding virulence in the hyper-virulent strain. Methylated motifs, which belong to known Restriction Modification (RM) systems of the H37Rv referencegenome were also identified. N6-methyladenine (m6A) and N4-methlycytosine (m4C) loci were identified in both strains. m6A were idenitified in both strains occuring within the following sequence motifs CACGCAG (Type II RM system), GATNNNNRTAC/GTAYNNNNATC (Type I RM system), while the CTGGAGGA motif was found to be uniquley methylated in the hyper-virulentstrain.Interestingly, the CACGCAG motif was significantly methylated (p = 9.9 x10 -63) at a higher proportion in intergenic regions (~70%) as opposed to genic regions in both the hyper-virulent and hypo-virulent strains suggesting a role in gene regulation. There appeared to be a higher proportion of m6A occuring in intergenic regions compared to within genes for hyper-virulent (61%) and hypo-virulent (62%) strains. The genic proportion revealed that 35% of total m6A occurred uniquely within genes for the hyper-virulent strain while 27.9% for uniquely methylated genes in hypo-virulent strain.

This study investigates the use of vibration and strain measurements on machine tools in order to identify the propagating wear of the selected tools. Two case studies are considered, one of which was conducted in the plant of a South African piston manufacturer. The purpose of the ftrst case study was to investigate the feasibility of vibration monitoring to identify tool wear, before attempting to implement a monitoring system in the manufacturing plant. During this case study, data from a turning process was recorded using two accelerometers coupled to a PL202 real time FFT analyser. Features indicative of tool wear were extracted from the sensor signals, and then used as inputs to a Self-Organising Map (SOM). The SOM is a type of neural network based on unsupervised learning, and can be used to classify the input data into regions corresponding to new and worn tools. It was also shown that the SOM can also be used very efficiently with discrete variables. One of the main contributions of the second case study was the fact that a unique type of tool was investigated, namely a synthetic diamond tool specifically used for the manufacturing of aluminium pistons. Data from the manufacturing of pistons was recorded with two piezoelectric strain sensors and a single accelerometer, all coupled to a DSPT Siglab analyser. A large number of features indicative of tool wear were automatically extracted from different parts of the original signals. These included features from time and frequency domain data, time series model coefficients as features and features extracted from wavelet packet analysis. A correlation coefficient approach was used to auto-lJUltically select the best features indicative of the progressive wear of the diamond tools. The SOM was once again used to identify the tool state. Some of the advantages of using different map sizes on the SOM were also demonstrated. A near 100% correct classification of the tool wear data was obtained by training the SOM with two independent data sets, and testing it with a third independent data set. It was also shown that the monitoring strategy proposed in the second case study can be fully automated and can be implemented on-line if the manufacturer wishes to. Some of the contributions of this study are the use of the SOM for tool wear classification, and conclusions regarding the wear modes of the synthetic diamond tools. / Dissertation (M Eng (Mechanical Engineering))--University of Pretoria, 2006. / Mechanical and Aeronautical Engineering / unrestricted

No description available.