VictorJuiz/thesis huggingface dataset:
On the singular stress field at the interface of bimaterial systems

Inverse square root, <math> <f> 1/<rad><rcd>r</rcd></rad>,</f> </math> singularity characterizes the stress field at the crack tip of homogeneous isotropic elastic media. This <math> <f> 1/<rad><rcd>r</rcd></rad></f> </math> singularity does not, however, hold for the stress field at the interface of a bimaterial system. A number of attempts have been made to treat this class of problems. These attempts reveal the presence of rapid oscillations in the stress and displacement fields and the dependence of the stress singularities upon the geometry and the elastic mismatch of the bimaterial system. These features complicate the determination of the singular stress field significantly. As a result, existing solutions are limited to a few specific configurations and simple loading conditions. It is, therefore, the objective of this thesis to develop a unified approach for treating general bimaterial systems. For this purpose, the bimaterial system is modeled as a bimaterial wedge, thus facilitating the simulation of a wide range of inhomogeneous solids--such as, layered composite materials, coated components and welded structures. Both theoretical and experimental techniques are employed to examine the current problem and the resulting singular stress field. The current boundary value problem is formulated in terms of the complex function method. By examining the resultant eigenequation of the system, the dependence of the stress singularities upon wedge geometry and elastic properties of the constituents is revealed and explicit expressions for the stress and displacement fields around the wedge vertex are obtained. These expressions are then used to develop a new singular finite element. This element enables the determination of the singular stress field and the associated stress intensity factors reliably and efficiently. Both quasi-static and dynamic stress intensity factors are obtained explicitly. To establish the validity of the newly developed method, a number of test cases are examined and compared with existing simplified solutions. The newly proposed method is then used to evaluate the effect of the wedge geometry, elastic mismatch, density ratio and loading conditions upon the resulting stress intensity factors. In the experimental work, a digital photoelastic technique is employed to examine the singular stress field around the vertex of a photoelastic bimaterial wedge. A special casting procedure is introduced to produce bimaterial photoelastic specimens with varied geometries. To determine the stress intensity factors reliably from the resulting isochromatic fringe patterns, a high order representation of the stress field around the vertex is used and a multi-parameter analysis method is developed. The experimental results are compared with the theoretical findings and the results reveal a good agreement between them.
Design and modeling of a new electro hydraulic actuator

This thesis addresses the issues of design and mathematical model identification of an advanced hydraulic system referred to as Electro Hydraulic Actuator (EHA). In the design part, insights into system design methodology are presented and used for the EHA prototype manufacturing. To get better knowledge of the system behavior, extensive open loop tests were performed. Test results are presented in the time and frequency domain, and it was concluded that system behavior is nonlinear. In the modeling part, a nonlinear mathematical model of the EHA is derived. Some of the unknown model parameters had to be identified experimentally by optimization. The last step in the system mathematical modeling was open and closed loop model validation using the experimental data. Proposed nonlinear mathematical model gives good correspondence with experimental data and can be used for system studying or controller design. Performed test show that the EHA system has high positioning accuracy (0.01mm), fairly high bandwidth (23 Hz with 20kg inertial load) and is easy to control. It shows significant benefits when compared to conventional hydraulic systems in the areas of control, efficiency and physical dimensions.
Epistemology of scientific inquiry and computer-supported collaborative learning

The problem addressed in the study was whether 10- and 11-year-old children, collaborating within a computer-supported classroom, could learn a process of inquiry that represented certain principal features of scientific inquiry, namely (1) engagement in increasingly deep levels of explanation, (2) progressive generation of subordinate questions, and (3) collaborative effort to advance explanations. Technical infrastructure for the study was provided by the Computer-Supported Intentional Learning Environments, CSILE. The study was entirely based on qualitative content analysis of students' written productions posted to CSILE's database. Five studies were carried out to analyze CSILE students' process of inquiry. The first two studies aimed at analyzing changes in CSILE students' culture of inquiry in two CSILE classrooms across a three-year period. The results of the studies indicate that the classroom culture changed over three years following the introduction of CSILE. The explanatory level of knowledge produced by the students became increasingly deeper in tracking from the first to third year representing the first principal feature of scientific inquiry. Moreover, between-student communication increasingly focused on facilitating advancement of explanation (the third principal feature). These effects were substantial only in one classroom; the teacher of this class provided strong pedagogical support and epistemological guidance for the students. Detailed analysis of this classroom's inquiry, carried out in the last three studies, indicated that with teacher's guidance the students were able to produce meaningful intuitive explanations as well as go beyond the functional and empirical nature of their intuitive explanations and appropriate theoretical scientific explanations (the first principal feature). Advancement of the students' inquiry appeared to be closely associated with generation of new subordinate questions (the second principal feature) and peer interaction focused on providing and requesting explanations (the third principal feature). Expert evaluations of three widely recognized philosophers of science confirmed the progressive nature of the students' inquiry as well as the cognitive value of their research questions and peer interaction. Conclusion: it is entirely possible for children, with computer-support for collaborative learning and appropriate teacher guidance, to pursue processes of inquiry that exhibit the principal features of mature scientific inquiry.
Arithmetic processing in adolescents treated for leukemia

The present study investigated arithmetic processing in adolescents, aged 14-16 years, treated for acute lymphocytic leukemia with (CRT) and without cranial irradiation (non-CRT). Although the CRT group achieved lower scores on most cognitive, memory and academic measures compared to the non-CRT group, differences were not significant. Relative to test norms, the two groups performed significantly lower on Freedom from Distractibility factor, immediate visual-spatial and multitrial learning tasks and arithmetic achievement. Arithmetic performance was associated with both verbal and visual-spatial abilities. Younger age at diagnosis was associated with difficulties in neurocognitive and academic functioning for the CRT group only.
Classical hydrodynamics on the sphere, gas giant phenomenology and novel numerical methodology

A new body of numerical methodology for the solution of hydrodynamical problems on the sphere is developed and applied to the integration of the two-dimensional shallow-water and nondivergent barotropic vorticity equations. Various discretizations of these nonlinear dynamical systems are derived and compared on the basis of these novel techniques, which utilize Cartesian representations of the governing equations defined on local patches of a refined icosahedral. grid structure. This mesh is almost uniform on the sphere and is particularly well-suited to the incorporation of multigrid methods whose implementation I also describe. In their totality, the new numerical techniques deliver (in addition to a other potential advantages) a greater theoretical efficiency at high resolution than the spectral transform methodology which is currently prevalent in hydrodynamical applications in spherical geometry. Models derived on the basis of these techniques are shown to perform well in comparisons with previously published results in the field of atmospheric dynamics, both for simple, standard test cases, and for more challenging nonlinear analyses of polar vortex erosion. The new models have also been exercised in novel simulations of physical processes relating to the action of the nonlinear inverse energy cascade that controls the evolution of two-dimensional flows and which is fundamental to the understanding of the observed atmospheric states of the Gas Giant Planets. I also present and interpret a novel nondimensionalization of global barotropic and shallow water flows on the sphere and relate it to the potential vorticity (PV) mixing principle whereby zonal flows in the presence of background rotation tend to self-organize into stable "PV staircase" configurations with latitudinal regions of homogeneous PV separated by strong gradients. Analytical representations of the corresponding mean zonal velocity profiles are developed and shown to furnish good fits to observations of the zonal flows in Gas Giant stratospheres. Numerical integrations are also discussed which analyze the nonlinear evolution of such background states when they are perturbed either by local, unstable shear layers or by random noise.
A 2.5 Gb/s CMOS Add-Drop Multiplexer for ATM

Asynchronous Transfer Mode (ATM) is used to accommodate the simultaneous transmission of voice, data and image, in an integrated manner using the same network. It is based on the transfer of fixed-length cells. In order to connect the source of information to the optical transmission line, a universal ATM functional block, the Add-Drop Multiplexer (ADM), is used. The block adds or extracts cells (53 byte words) from the high speed data bus. The objective of this work is to implement the ADM in 0.5[mu]m CMOS technology, running at 311 MHz or 2.5 Gb/s. The ADM consists of an Input Buffer which provides the selection logic for the cell extraction, an Add Module used to insert ATM cells into the high speed data bus, a Drop Module used to extract the cells from the high speed data bus and an Output Module that prepares the cells for physical transmission. The chip was designed and successfully implemented. It occupies an area of 14.7 mm2 and dissipates 4.5 W of power. The chip was tested functionally at 20 MHZ. High speed testing was also performed at 311 MHz by focusing on the critical path of the chip. A good correlation was obtained between simulation and experimental results.
College administrators' understanding of care and connectedness

This study examines senior college administrators' understandings and practices of care. The five participants talk about the practice of care in their lives generally and in their work situations. The 3 women and 2 men each have executive-level supervisory experiences within diverse Ontario college settings. The data from a sample of Ontario's college administrators is not statistically significant and makes no claim to universality. Instead, the participants' narratives, gathered during the course of three 90 minute interviews with each provide a sense of what it is like for them to manage at a senior executive level. Care emerges thematically from the participants' work histories as a phenomenon of "connecting" presented here as 'connecting with self, connecting with others' and 'helping others connect. ' Care comes into sharper focus by using an interpretation of Martin Heidegger's 1927 'Being and Time' as a primary conceptual tool. Heidegger interprets the core of human existence to be care which is rooted in our very being-in-the-world. Heidegger's analysis locates human beings to be inescapably in relation with others. In addition to Heidegger's philosophical perspective, this study includes views of care from psychologists, researchers in educational theory, recent approaches within health care and contemporary critiques of social policy, or theory to disclose the participants' ethos of care. This study shows how the participants supervise from an implicit ethos that reflects caring for others, especially through building community. Among other things, caring administrative practices help to achieve the American Association of Community Colleges' highest priority for senior college administrators (1988)--the task of building communities. Building communities meets the present and the future needs of college students and staff to care and be cared for.
In vitro and in vivo characterization of genetically engineered cells microencapsulated in a HEMA-MMA copolymer

The encapsulation of genetically engineered cells in small-diameter (<math> <f> ~</f> </math>450 <math> <f> <g>m</g></f> </math>m) poly(hydroxyethyl methacrylate-co-methyl methacrylate) (HEMA-MMA, 75% HEMA) microcapsules as a platform for the use of encapsulated cells in an alternate approach to autologous somatic gene therapy was explored. The effect of inclusion of a matrix in the core of the capsules on the behaviour of three different cell lines, namely human embryonal kidney (HEK) "293" cells transfected to secrete human hepatic lipase, mouse C2C12 myoblasts transfected to secrete human growth hormone, and mouse L929 fibroblasts transfected to secrete human placental alkaline phosphatase (SEAP) was investigated ' in vitro'. Presence of ultralow gelling temperature agarose in the core of the capsule promoted the proliferation of HEK cells. The viability and transgene expression of transfected C2C12 cells was improved in microcapsules that contained Matrigel®, a reconstituted basement membrane extract from a mouse sarcoma. Co-encapsulation with a bovine dermal type I collagen successfully maintained the viability of L929 cells. In addition, reduction of the concentration of poly(HEMA-MMA) in the solution used to fabricate the capsules did not affect the rate or extent of proliferation of encapsulated HEK cells. The 'in vivo' performance of poly(HEMA-MMA) encapsulated cells was investigated with transfected L929 cells that were implanted in the peritoneal cavity of C3H mice. The implantation of microcapsules that were suspended in a phosphate-buffered saline solution or an ultralow gelling agarose gel (SeaPrep®, which physically disintegrated) resulted in deformation, aggregation, and poor retrievability of the microcapsules. As a result, limited viability of the encapsulated cells was observed 3 weeks post-implantation. However, immobilization of the microcapsules in a low gelling temperature agarose gel (SeaPlaque®) resulted in maintenance of viability of <math> <f> ~</f> </math>50% of the encapsulated cells. Once the viable cells were released from retrieved microcapsules and regrown as monolayers, they expressed SEAP at a similar level to cells released from non-implanted microcapsules. Thus, the potential for the delivery of recombinant proteins with poly(HEMA-MMA) encapsulated genetically engineered cells was established in this study.
p53 mutational analysis in laryngeal squamous cell carcinoma, results of full-length gene sequencing

In this study DNA was extracted from 52 paraffin embedded, formalin fixed biopsies from 42 laryngeal squamous cell carcinomas. Exons 2-11 of the p53 gene were individually amplified and sequenced. Standard IHC was performed using the monoclonal antibodies DO7 and EA1 to detect p53 and p2l proteins respectively. 22 mutations were observed in tumours from 20 patients (48%). 5 of these mutations (23%) were outside exons 5-8. Discordance between p53 genotype and protein levels was observed. Similarly, there was no association between p53 status (genotype or IHC) and either p21 protein expression or local recurrence following radiation therapy. These results show that p53 mutations are common in laryngeal carcinomas and that a large proportion occurs outside traditionally examined regions. The lack of correlation with outcome suggests p53 mutations and protein expression are not associated with tumour response to radiation therapy in laryngeal squamous cell carcinoma.
Symmetry, conservation laws, and theoretical particle physics, 1918-1979

In this work, we trace the role of symmetry throughout the history of theoretical particle physics, paying particular attention to the role of group theory, the formal mathematics of symmetry. After an analysis of the role of conservation laws and invariance in the theory of general relativity, we move on to Weyl's gauge theory of 1918, which was developed within the context of general relativity as an attempt to unify gravitation and electromagnetism. Weyl was trying to exploit an invariance of scale, and although his theory was experimentally refuted, it provided a formulation of the conservation of charge. After the advent of quantum mechanics, gauge theory was reinterpreted by London as an invariance of the wave-function. Weyl and Wigner studied group theory in the context of quantum mechanics, but the broadness of its application had yet to be appreciated. Symmetry was soon exploited in the nuclear interactions, however, and we examine the events leading to the discovery of SU(2) of isotopic spin. We analyze how the discovery of strangeness was linked to the generalization of SU(2) to SU(3), and also how it led to a differentiation between the strong interactions, which conserve isotopic spin and strangeness, and the weak interactions, which violate these conservation laws, along with the conservation of parity. Yang and Mills were impressed with gauge invariance, and in 1954, they took the bold step of imposing it upon the Lagrangian of the strong interactions, forcing the introduction of three new gauge fields. There was a problem, however, because although the short-range of the strong interactions implied that these gauge bosons should be massive, they needed to be massless in order to preserve gauge invariance. In addition, efforts were made to extend Yang-Mills theory to the weak interactions, but they also faced the same zero-mass problem. This problem was finally solved in 1967, when Weinberg and Salam showed how gauge boson masses could be generated using spontaneous symmetry breaking. They based a unification of the electromagnetic and weak interactions upon local gauge invariance, and this principle was soon applied to the strong interactions as well.
The use of cow milk, meat and cereal to prevent iron depletion in infants from low-income households

The hypothesis of this thesis was that there would be a reduction of iron depletion and/or anaemia in six to 12 month old cow milk-fed infants from low-income households consuming infant cereals and pureed meats (n = 43) when compared to infants from low-income households with no dietary intervention (n = 54). Unfortunately the incidence of endpoint (haemoglobin<110 g/L or ferritin<10 [mu]g/L confirmed in a second sample) was very low in the control group (9.3%) much below the 30% anticipated; thus, the hypothesis could not be adequately tested. However, the three objectives of the study were achieved. Firstly the data obtained indicate that the control group followed proper feeding patterns which explained the low incidence of iron depletion. Most of the treatment infants complied with the dietary restrictions of the protocol and thus had low rates of iron depletion. Secondly three lines of evidence show that the iron from cereal and meat was well utilised and prevented iron deficiency in cow milk-fed infants: (i) The incidence of iron depletion/anaemia in the treatment group (7.0%) was low compared to past studies of infants in Canada and not different from control infants who followed proper infant feeding patterns (p = 0.66). (ii) Infants using cow milk but not consuming infant cereal or meat, were at great risk of reaching end-point (p = 0.0002) which may explain why feeding cow milk at ten months of age was associated with iron depletion/anaemia. (iii) The rate of fall in plasma ferritin (Ferr) with age was the same in both groups, suggesting that the iron status of the two groups were equivalent (p = 0.49). Thirdly transferrin receptor (TfR) was evaluated as a diagnostic measure of iron deficiency. The sensitivity was calculated to be 0.75 and the specificity to be 0.94. It is concluded that the consumption of adequate amounts of infant cereals and pureed meats prevented iron depletion and anaemia in infants fed whole cow milk after six month of age and that, as a measure of iron deficiency, TfR appears to be an accurate, relatively sensitive and specific diagnostic measure compared to traditional measures of iron status.
Intelligent delineation of rock discontinuity data using fuzzy cluster analysis

Discontinuities affect the behaviour of rock masses in many important ways and superimpose properties on them. Discontinuity analysis, which in the main deals with the delineation of discontinuities into sets, plays a crucial role in helping rock mechanics and rock engineering experts make important design and construction decisions. The conventional approach to analysing discontinuity data is subjective and does not utilize many of the important properties (other than orientations) in delineating discontinuities into sets. The traditional approach is also slow, can be very boring, and poorly handles the uncertainty present in discontinuity data. In this thesis the application of intelligent computer methods that can inject objectivity into the delineation process in discontinuity analysis were examined. These methods included a non-parametric density estimation method for clustering discontinuity orientations and fuzzy clustering techniques. As a result, a fuzzy cluster algorithm was developed for separating discontinuity data into sets or clusters. The algorithm uses fuzzy and statistical methods that introduce objectivity into discontinuity analysis and account for the uncertainty present in both discontinuity data and the data analysis process. The practical application of the fuzzy 'K'-means algorithm is limited unless clustering issues such as distance metrics, variable weighting, variable standardisation and cluster validity are meaningfully addressed. The thesis provides insight into the importance of resolving these issues in clustering and develops solutions to them.