McGill University Thèses et mémoires publiés en 2005

The purpose of this paper was to characterize and compare pressure patterns in the skate boot of elite and recreational players during the forward crossover turn. In-skate pressure patterns of eight elite varsity level hockey players (mean +/- SD: height (m) = 1.80 +/- 0.07, weight (kg) = 87 +/- 0.06) and eight recreational hockey players (mean +/- SD: height = 1.76 (m) +/- 0.06, weight (kg) = 82 +/- 0.07) were measured using fifteen piezo-resistive sensors per foot during the forward crossover skating stride. Each participant performed three trials in both the clock-wise (CW) and counter clock-wise (CCW) directions. …  Lire la suite

Morphological and clinical signs of lumbar intervertebral disc disruption are pronounced in the posterior and postero-lateral inner annulus fibrosus. The regional intervertebral disc predisposition to disruption suggests that intradiscal stresses and strains may also be region specific and possibly initiate the disruption. Quantitative data describing intradiscal deformations have been limited to the mid-sagittal plane using techniques that compromise the intervertebral disc integrity. No experimental study has quantified intradiscal strain patterns. The initial objectives of the present work were to use experimental cadaveric methods and finite element techniques to develop and validate methods of measuring intradiscal deformations and strains along the …  Lire la suite

Five hundred years of Christian martyrdom are represented in the Ecclesiae militantis triumphi (1583). Engraved by Giovanni Battista Cavalieri, the series that was bound into a book reproduces a fresco cycle in the church of San Stefano Rotondo in Rome. While the church belonged to the Jesuit German-Hungarian College, the book accompanied priests in their proselytizing mission in Northern Europe. This thesis will look at the function of the book in relation to various audiences, in different viewing contexts. Analyzed primarily in relation to the intended Jesuit audience as an object of devotion, the book will also be inserted within …  Lire la suite

Hypothalamic-pituitary-adrenal (HPA) responsiveness to stress is generally blunted in lactating rats, except during situations of pup endangerment, suggesting an important role of salience of stressor in stress response during lactation. Conversely, in women, breastfeeding is associated with reduced HPA responses to physical stress and perceived stress. Yet, HPA responses to a standardized speech and arithmetic task (Trier Social Stress Test, TSST) are not blunted in breastfeeding mothers. Interestingly, greater number of children (parity) increases maternal experience which can enhance responsiveness to child-related stressors. To our knowledge, no study to date has investigated the impact of infant feeding type and parity …  Lire la suite

The present study explores the role of special services and accommodations for the academic success of college students with disabilities. Two students participated, one with mild attention-deficit hyperactivity disorder (ADHD) and one with a severe language disorder. Unstructured interviews were used to examine participants' perceptions of the effectiveness of special services and accommodations. Other factors contributing to students' progress in school, such as areas of learning strengths, effort and assistance from teachers, peers and family members, as well as lack of appropriate services and funding, were also discussed by the participants. Participants' personality characteristics and life circumstances appear to influence …  Lire la suite

The dynamic and public nature of a large scale public distributed system introduces challenging security issues that demand new technical approaches. Existing literature has discussed a variety of schemes but fall short of describing an engineering process to design security in such systems. This thesis presents a process model for security system design in large distributed systems that are prone to unpredictable joins and departures, the possibility of malicious behaviors by public nodes and diverse local policies. A case study on designing security architecture for a Public Computing Utility (PCU) is presented which is in tune with the proposed process …  Lire la suite

Objectives. The purpose of this study was too determine whether there were significant kinematic differences between recreational and elite hockey players and between contra-lateral lower limbs during forward hockey skating. Methods. While skating on a hockey treadmill subjects were filmed with four synchronized digital video cameras while wearing reflective marker triads on the thighs, shanks and skates. Subjects skated within a calibrated volume at a self selected speed that they could maintain comfortably for one minute. Each subject completed three trials separated by 5 minutes of rest. Data was reduced and analyzed using programs written in MATLAB. Two-way ANOVA and …  Lire la suite

Complementing field research among severely disadvantaged minority groups, the present laboratory analogue investigates how the clarity of a group member's cultural (collective) identity is related to positive feelings about oneself and one's performance. Participants were assigned to a clear, conflicted, or unclear collective identity condition, and were then faced with challenging tasks (study 1) or a challenging social interaction (study 2). In study 1, the hypotheses were not confirmed because participants overcame a lack of collective identity clarity by simply applying their own familiar collective identity to the tasks. This default alternative was removed in study 2, which resulted in …  Lire la suite

This thesis investigates the syntax-discourse interface in adult, end state second language (L2) acquisition. Specifically, it examines topic constructions in Spanish and English, namely Clitic Left Dislocation (CLLD) and Contrastive Left Dislocation (CLD), which exhibit both syntactic and discourse level properties. In both cases, topics occur at the left periphery of clauses and reintroduce a subset of a known set previously mentioned in discourse. Sensitivity to specificity is available in Spanish but not in English. The interpretation of the topicalized element as either generic or specific depends on the presence or absence of the clitic. Data from a bidirectional study …  Lire la suite

In this thesis, we present numerical examples of class invariants constructed by DeShalit-Goren in [14]. These class invariants are an attempt to generalize the classical theory of elliptic units. The hope is that a better understanding of these class invariants would lead to other cases of Stark's conjectures expressing the value of derivatives of Artin L-functions at s = 0 in term of a regulator of linear forms in logarithms of S-units.  Lire la suite

The thesis opens with an account of the origins of the modern problem of the demarcation of the logical constants in Alfred Tarski's 1936 lecture "On the Concept of Logical Consequence". Focus then shifts to the logical notions, to free the investigation from parochialism. John Etchemendy's recent challenge to the demarcation project is discussed and rejected. The thesis then surveys various methodological issues, conceptions of the aims and purposes of logic, and needed technical concepts. This provides the requisite tools to carry out the evaluation of existing demarcation proposals. Three groups of demarcation proposals are elaborated and evaluated. First are …  Lire la suite

Ultra-small angle light scattering (USALS) is a technique used to probe large average spatial and temporal structure of soft condensed matter complementary to microscopy. Limited information is available on the design and features of a multi-speckle CCD-based USALS apparatus. The optics of such a setup are described followed by an optimization scheme involving ray tracing that can be used to choose the optimum lenses by taking into account the finite spot size due to lens aberrations, diffraction, and the CCD pixel size. Results of calculations of the optimization scheme are presented for a static light scattering (SLS) setup followed by …  Lire la suite

This thesis considers the vibration control of an automobile suspension subject to road imperfections using multivariable feedback techniques. Frequency-domain system identification methods are applied to model the dynamic behaviour of the suspension system from experimental test data using a data analysis software tool called CIFER. Advanced features such as the Chirp-Z Transform and composite window techniques are used to extract high quality frequency responses. A linear multivariable state-space model is derived which matches the experimental frequency response data set in the frequency range 65Hz-240Hz. Accurate uncertainty modeling on the nominal suspension is needed to design controllers achieving acceptable levels of …  Lire la suite

I address the problem of the lack of academic attention to evidentiary issues in Honduras in comparison to Common Law Countries. I feel that Honduran law students need to be taught a working scheme to deal with issues of admissibility and weight of evidence in order to achieve the rational determination of facts. Moreover, I draw such a scheme from the conceptual basis for admission of evidence and the probative processes identified by Wigmore. I think that if this scheme were applied to trial records, academicians would identify problems in the admission and weight of evidence and would develop approaches …  Lire la suite

Temporal changes in the environmental conditions upon which life depend are ubiquitous in nature, acting at every level of organisation from cells to ecosystems. Although the actions themselves are often poorly understood, they strongly depend on the temporal and hierarchical (organisational) scales at which they are measured; ecosystems are relatively stable through time while their species composition may undergo vast changes. Likewise any hierarchical level may be relatively stable in the short-term, but undergo vast long-term changes. This thesis aims to better understand the importance of these scales for mediating the impact of environmental variability on ecological systems. The approach …  Lire la suite

The purpose of the present study was to examine Parental Alienation Syndrome (PAS) and to expand the research based knowledge in the area. PAS entails both psychological processes and legal dimensions as it occurs primarily within the context of custody litigation. False allegations of abuse (FA) are commonly associated with PAS and similarly entail both psychological and legal issues. The research comprised two separate studies. First, interviews with target parents were conducted to attain their unique perceptions and experiences of PAS and on the way their cases were handled within the legal system. Second, a quantitative comparison between PAS and …  Lire la suite

In this critical inquiry, I look at how individuals who experience social, cultural and economic exclusion in postcolonial societies construct cultural identities and relationships with what they perceive as the dominant cultures of their countries through the process of schooling. Here, the term 'postcolonial' refers to events, places, and conditions that are situated after periods of colonization, and implicate individuals whose histories are linked to colonizers and colonized peoples. This thesis discusses theoretical, political, philosophical and methodological issues around the design, implementation, interpretation and report of an ethnographic inquiry carried out in Brazil (Sao Paulo area) and southern France in …  Lire la suite

Hazardous Materials are potentially harmful to people and environment due to their toxic ingredients. Although a significant portion of dangerous goods transportation is via railroads, prevailing studies on dangerous goods transport focus on highway shipments. We present an analytical framework that incorporates the differentiating features of trains in the assessment of risk. Each railcar is a potential source of release, and hence risk assessment of trains requires representation of multiple release sources in the model. We report on the use of the proposed approach for the risk assessment of the Ultra-train that passes through the city of Montreal everyday. The …  Lire la suite

Allison, Paul (Supervisor)  Lire la suite

The present research project is part of an overall study whose aim is to develop a process for the production of silver powders by the reduction of silver nitrate with hydrazine. This is an extremely fast reaction, which results in uncontrolled particle properties. The main objective was to develop conditions at which the rate of the reaction and hence the particle properties could be controlled; this was accomplished by carrying out the reaction under the presence of EDTA as a complexing agent. EDTA effectively slowed down the reaction still allowing it to take place at concentrations between 0.22 and 3.3 …  Lire la suite

In spite of the general prohibition of the use of force in international relations contained in the UN Charter, some jurists maintain that humanitarian intervention is valid under comtemporary international law. Too make their case, they put forward a series of arguments which can be divided into two categories. The first holds that humanitarian intervention is compatible with the UN Charter, and the second, which is used more often, that a right of humanitarian intervention has arise out of state's practice. The present thesis surveys these arguments and comes to the conclusion that humanitarian intervention remains illegal under international law. …  Lire la suite

This thesis investigates cross-modal interactions in auditory and visual perception, focusing on the perception of expressive musical performances. A primary aim of the work is to advance knowledge pertaining to how and when musicians' body movements influence an observer's overall experience. Three studies, comprising two multi-factor experimental investigations and one theoretical contribution, explore the multi-modal experience of musical performance. The two empirical chapters investigate, respectively, (1) the real-time experience of musical structure and musical emotion, comparing unimodal and multimodal conditions, and (2) the multidimensional structure of affective responses to musical performance, as a function of sensory modalities and performance intentions. …  Lire la suite

What is essential is invisible to the eye. Antoine de Saint-Exupery Of course, Saint-Exupery didn't have extra dimensions in mind when he wrote this famous line. Nevertheless, the recent realisation that standard model degrees of freedom can naturally be restricted to a submanifold embedded in a higher dimensional Universe means that an ingredient essential to our description of nature might quite literally be "invisible to the eye". Exploring the consequences of such braneworld scenarios has occupied a large part of the theoretical physics community over the last seven years, and this thesis is a collection of contributions to this endeavour. …  Lire la suite

Recent interest in hydrogen as an energy source has resulted in development of new technologies such as non-thermal plasma processing of natural gas. We report the development of a process yielding hydrogen from natural gas that generates no green house gases and thus meets the Kyoto accord targets. In this process, natural gas is treated in a dielectric barrier discharge (DBD) yielding hydrogen and solid carbon according to the following reaction: CH4 (g) → 2H2 (g) + C (s). The direct cracking of the hydrocarbon is possible if the natural gas is injected in the plasma zone, created by the …  Lire la suite

A rapidly growing senior population is facing loneliness, desolation andisolation in our ageist society. Age-linked detachment and a number of socialinteractors are closely related to general health, physical condition anddepression.Using standardized instruments, the UCLA Loneliness Scale (Russellet al., 1980), the Multidimensional Scale of Perceived Social Support (Zimetet al., 1988), and the Geriatric Depression Scale (Brink et al., 1982), this nonexperimental-study investigated the level of perceived loneliness, socialsupport and the causative relationship of these factors to the presence ofdepression among 50 independent, relatively healthy elders in a Montrealsenior centre.Findings suggest that loneliness is a major predictor of elderdepression. Lack of perceived …  Lire la suite

The French temperance movement during the nineteenth century believed that it had discovered the source of social problems when it linked accidents, conjugal violence and crime to an increase in alcohol consumption by the working classes. In a swift attempt to curb these societal ills, the campaign led by the medical community targeted the working classes in France. This instigated the further alienation of the masses and allowed government officials to promote its own agenda of moral reform. In an effort to expose the elitist intentions of this state run temperance movement, this thesis analyzes four images from Camille Pissarro's …  Lire la suite

Since the discovery of a giant magnetocaloric effect in Gd5Si 2Ge2 that is associated with a first-order magnetostructural transition, the R5SixGe4- x materials (where R=Y,La-Lu) have come under intensive study. Systematic structural data has now been obtained for most of the R5Si xGe4-x compounds (Y, Pr, Nd, Gd, Tb, Er, and recently Yb), and from this structural data, trends have been begun to emerge. The Yb5SixGe 4-x system however defies all conventional wisdom and adopts the orthorhomic Gd5Si4 structure, independently of x, a unique feature in the R5SixGe 4-x family. The magnetic transition temperatures of the Yb5SixGe4- x compounds have …  Lire la suite

Learning to play in the presence of independent and self-motivated opponents is a difficult task, because the dynamics of the environment appear to be non-stationary. In recent years there has been considerable amount of research in the field of Multi-Agent Learning, and some of this work has been in the context of Reinforcement Learning. One commonly used approach has been to restrict the opponent to a class of computationally bounded players, creating a parametrized model of it, and then search the model that can best explain the observed opponent behavior. In this thesis we study the problem of Reinforcement Learning …  Lire la suite

The present study is devoted to the morphologies and corona compositions in aggregates of mixtures of PS-b-PAA and PS-b-P4VP block copolymers as influenced by controllable assembly parameters, such as block length, pH, solvent, water content and the molar ratio of PAA/P4VP. Morphologies and surface properties of the aggregates were investigated by transmission electron microscopy and electrophoretic mobility, respectively. According to the results, the general hypothesis that the external corona is composed of long chains, while short chains form the inner corona of the vesicles, is valid only in mixtures without additives (no acid or base). In the presence of acid …  Lire la suite

This study investigated the possibility of using ground-based remotely sensed hyperspectral observations with a special emphasis on detection of water, weed and nitrogen stresses contributing towards in-season decision support for precision crop management (PCM). A three factor split-split-plot experiment, with four randomized blocks as replicates, was established during the growing seasons of 2003 and 2004. Corn (Zea mays L.) hybrid DKC42-22 was grown because this hybrid is a good performer on light soils in Quebec. There were twelve 12 x 12m plots in a block (one replication per treatment per block) and the total number of plots was 48. Water …  Lire la suite

The dynamics of the atmospheric mesoscale and oceanic submesoscale are characterized by strong stratification and weak rotation, and the resulting energy spectra, though surprisingly universal, are still poorly understood. The aim of this work is to study the nonlinear dynamics and interactions of vortical motion (with potential vorticity) and internal inertia-gravity waves in the idealized context of homogeneous stratified turbulence, and to examine the extent to which they can account for the observations. We consider separately turbulence generated by vortical motion and internal waves using a combination of theory and numerical simulations. When vortical motion dominates the flow, the statistical …  Lire la suite

Between the mid-eighteenth and the mid-nineteenth centuries, the Crown coordinated a revolution in land usage in the Kawartha Lakes, as elsewhere in the colony, through 'civilization' and land redistribution. Attempts to change native society and build settler communities did not quite unfold the way the government intended. 'Civilization' helped the Mississauga farm and taught skills that eased interaction with colonial society, but they continued to produce much of their food by traditional means. Speculation isolated settlers and made land acquisition more difficult, though some speculators provided essential services. Most immigrants bought land privately and many were not able to establish …  Lire la suite

Witnesses believed that the Black Death and subsequent fourteenth-century plagues threatened profound social change. However, Geoffrey Chaucer (c.1340-1400) does not appear to accord the plague a place of any importance in his works. This is especially surprising in the case of the Canterbury Tales , which presents a complex portrait of plague-era society. Chaucer's silence on the plague is reinforced by critical positions that deemphasize the effects of the plague and emphasize Chaucer's supposed lack of interest in his world. This thesis contends that the plague is in fact present in the Canterbury Tales in the guise of the changes …  Lire la suite

Developmental sympathetic neuron death is determined by functional interactions between the TrkA/NGF receptor and the p75 neurotrophin receptor (p75NTR). A key question is whether p75NTR promotes apoptosis by directly inhibiting or modulating TrkA activity, or by stimulating cell death independently of TrkA. Here we show that the presence or absence of p75NTR does not alter Trk activity or NGF- and NT-3-mediated downstream survival signaling in primary neurons. Crosses of p75NTR-/- and TrkA-/-mice indicate that the coincident absence of p75NTR substantially rescues TrkA-/-sympathetic neurons from developmental death in vivo. These data support a model where developing sympathetic neurons are "destined to …  Lire la suite

The rapid growth of Canadian pork industry has been challenged by its negative impact on the environment. To find an economical and promising solution to the environmental problems, 4% zeolite (90%+ clinoptilolite) were supplemented to a regular (100% crude protein (CP) and energy) or low CP and energy (90% CP and 90% energy or 90% CP and 85% energy) grower pig diets. Twenty male and twenty-four female grower pigs were used in two feeding experiments respectively, followed by a metabolic test with three batches of animals repeated to determine the metabolic effects of zeolite supplementation. Pig performance (body weight gain, …  Lire la suite

In this paper, we first theoretically revise the traditional particle modeling (PM) by means of mathematical derivation in that, adopting of Lennard Jones (LJ) format equations, four conservative rules are satisfied in order to determine the four unknown in a LJ equation, such as the mass, the elastic energy, the Young's modulus and the tensile strength conservations in the PM and molecular dynamic (MD) models. This enables the new developed PM to uniquely define a material's properties to be studied and promisingly become a predictive tool in mining industries. A safe time increment scheme is also defined and a new …  Lire la suite

When an aircraft flies through clouds under icy conditions, supercooled water droplets at temperatures below the freezing point may impact on its surfaces and result in ice accretion. The design of efficient devices to protect aircraft against in-flight icing continues to be a challenging task in the aerospace industry. Advanced numerical tools to simulate complex conjugate heat transfer phenomena associated with hot-air anti-icing are needed. In this work, a 3D conjugate heat transfer procedure based on a loose-coupling method has been developed to solve the following four domains: the external airflow, the water film, conduction in the solid, and the …  Lire la suite

Iron is an essential but potentially harmful metal element. Iron regulatory protein 1 and IRP2 posttranscriptionally control cellular iron homeostasis by binding to iron-responsive elements (IREs). Binding of IRPs to single IRE within 5'-untranslated region (5'-UTR) of ferritin mRNA attenuates biosynthesis of the iron-storage protein by translational repression, while their binding to multiple IREs within 3'-UTR of transferrin receptor 1 (TfR1) mRNA stimulates that of the iron-acquisition protein through mRNA stabilization. IRP1 and IRP2 share extensive homology, but respond to levels of cellular iron by distinct mechanisms. According to cellular iron status, IRP1 is switched between the states of RNA-binding …  Lire la suite

A variety of studies were conducted in model and biological membrane systems to examine the phenomenon of putative 'lipid raft' microdomains in the plasma membrane of mammalian cells. The studies focused on understanding the physical properties of lipid rafts, and how these properties influence the partitioning of lipids and lipidated proteins into raft-like membrane domains; and finally, how lipid raft properties play a role in mediating T-cell signaling. The model membrane system employed in the majority of our studies utilized a fluorescence-quenching assay that could directly monitor the partitioning of various lipidated molecules into liquid-ordered, raft-like domains in membrane vesicles …  Lire la suite

The semiconductor ZnO has a band gap of 3.3 eV and has potential in applications as transparent and conducting layers for electronic devices. In the present work, experiments have been carried out to deposit thin films of ZnO on glass and silicon substrates by RF magnetron sputtering. The deposition experiments were performed at substrate temperatures in a range from room value to 400°C. Resistivity measurements were performed on the films. The resistivity increased as the substrate temperature was increased from room value to 400°C. The films on the silicon substrates were then processed into ZnO(n)-Si(p) heterojunctions whereas the ones on …  Lire la suite

Papaya mosaic virus (PapMV), as a member of potexvirus family, has a rod-shape, crystalline and repetitive structure. Other potexviruses have been shown to possess proinflammatory properties. To test the proinflammatory properties of PapMV, we first monitored chemokine transcripts expressed in murine macrophage B10R cells. Our data revealed that PapMV rapidly induced two chemokines, macrophage-inflammatory protein (MIP)-2/CXC chemokine ligand (CXCL) 2 and interferon-garmma inducible 10 kDa protein (IP-10)/CXCL 10 in a time and dose-dependent manner. Thereafter, by using various macrophage deficient cell lines (TLR4-/-,MyD88 -/-), we identified that PapMV-induced chemokines expression through a TLR4 and MyD88-dependent signaling pathway. In addition, we …  Lire la suite

This thesis is composed of major parts, as well as the introduction and conclusion. The second part of this thesis provides an overview the offence of aircraft hijacking, providing the foundation for this thesis. This part defines and introduces the terminology of aircraft hijacking, the relationship between hijacking and aerial terrorism, the categories of aerial terrorism, a comparative analysis of the concept of aircraft hijacking, the historic evolution of hijacking, and the present situation and characters of hijacking. Next, the third part will conduct a comprehensive study of the international Conventions available for combating hijacking, including the Tokyo Convention, The …  Lire la suite

In this thesis, the "green" McGill Paleoclimate Model (MPM) is developed by interactively coupling the five-component physical MPM with a Dynamic Global Vegetation Model (DGVM) known as VECODE (VEgetation COntinuous DEscription model). Three applications to the pre-industrial Holocene climate, ocean, vegetation and terrestrial carbon cycle dynamics are presented, after a new land surface scheme is introduced. In these applications, orbital (Milankovitch) forcing and prescribed atmospheric CO2, starting from eight thousand years before present (8 kyr BP), are applied. In addition, a prescribed retreat of the Laurentide Ice Sheet (LIS) from 8 to 6 kyr BP is introduced. [Note: All acronyms …  Lire la suite

This study presents techniques that can be applied to optimize the quality of coated fried chicken nuggets. Heat and mass transfer during deep fat frying of breaded chicken nugget was simultaneously modeled using the moving boundary concept. Numerical software FEMLABRTM 3.0 was used to solve the proposed model. To validate the model, experiments were conducted. Chicken nuggets were made with wheat flour based batter and breading. The samples were fried in a fryer using oil temperatures at 160, 170 and 180°C. Total frying times ranged from 90 to 300 s. A good agreement was obtained between predicted and observed results. …  Lire la suite

Telomerase is the ribonucleoprotein enzyme whose principal function is to catalyze the de novo addition of telomeric repeats to the ends of linear chromosomes. Telomerase activity is predominantly observed in cancerous tissues and rarely in normal somatic cells making telomerase an attractive anticancer target. BIBR1532 is a highly selective pharmacological inhibitor of telomerase catalytic activity and induces telomere shortening and eventual growth arrest. We treated drug-sensitive and drug-resistant human leukemia and breast cancer cells lines with BIBR1532 and observed telomere shortening and a progressive decrease in proliferative capacity or colony forming ability. This effect was increased with the co-treatment of …  Lire la suite

Wildfires are a major part of the Mackenzie River Basin climate system, and most wildfires within the basin are lightning-caused. Thus, a study has been conducted that identifies the atmospheric circulation patterns associated with extreme lightning events. In addition, events are stratified according to the number of resultant large wildfires to determine why some extreme lightning events induce a large quantity of wildfires within the basin, and why others do not. Extreme lightning events in the MRB are characterized by a strong, persistent upper-tropospheric ridge dominating the basin until event onset. The triggering mechanism of the majority of extreme lightning …  Lire la suite

Individual differences in gene expression and behaviour are the result of an interaction between a given set of genes and a variety of environmental conditions. The study of epigenetics focuses on the nature of this interaction. The early developmental period in the life of a mammal is exquisitely sensitive to environmental cues. One critical question is how is the genome capable of adapting to these developmental or environmental signals? Building on an established rodent model, in which the effects of maternal care have been demonstrated to regulate the development and expression of neurobiological and behavioural measures in offspring as adults, …  Lire la suite

In niobium (Nb) microalloyed steels one of the strengthening mechanisms is precipitation of Nb(C, N). Precipitation in austenite has been studied and applied for many decades, but its precipitation in ferrite has been paid less attention. Some of the findings are somewhat contradictory. Due to environmental and resource saving consideration in recent years, more and more scrap has been recycled and re-used. Thus, tramp elements inevitably exist in steel such as Cu, Sn, Ni and so on. These elements may influence properties of steels at some extent although they are very little in content. The X80 steel examined in this …  Lire la suite

This thesis treats type synthesis and kinematic analysis of translational parallel manipulators (TPMs) from a group theoretical point of view. For the TPM type synthesis, based on displacement group theory (DGT), TPM leg motion is represented by a series of displacement subgroups. For symmetrical three-legged TPMs, three categories are classified and a total of 90 architectures are proposed. For asymmetrical three-legged TPMs, 13 cases of possible leg combinations are presented and some possible constructions of TPMs are shown. The advantages of DGT in mechanism synthesis are described. For the kinematic analysis of symmetrical TPMs, geometric elements are employed to denote …  Lire la suite

This thesis deals with the application of sensitivity analysis to a variational geometry environment for the optimization of the design of electromagnetic devices. Through a graphical user interface, an electromagnetic device is sketched in a free-hand manner. The device topology is stored in a parameteric fashion. The sketch provides the topology (geometric entities and their interconnection) and defines the device, where changing the parameters provides all the possible devices under consideration. The performance of the device is computed using a commerical finite-element package. The effect of changing the system parameters on the device performance is investigated and used to modify …  Lire la suite