Yes / This paper reports on an experimental investigation into braking-related steering drift in motor vehicles, and follows on from a previous paper by the authors in which it was concluded that braking can cause changes in wheel alignment that in turn affect the toe-steer characteristics of each wheel and therefore the straight-line stability of the vehicle during braking. Changes in suspension geometry during braking, their magnitude and the relationships between the braking forces and the suspension geometry and compliance are further investigated in an experimental study of wheel movement arising from compliance in the front suspension and the steering system of a passenger car during braking. Using a kinematic and compliance (K&C) test rig, movement of the front wheels and the suspension subframe, together with corresponding changes in suspension and steering geometry under simulated braking conditions, have been measured and compared with dynamic measurements of the centre points of the front wheels. The results have enabled the causes and effects of steering drift during braking to be better understood in the design of front suspension systems for vehicle stability during braking.

Through an analysis of 7, semi-structured, one-on-one, open-ended interviews and relying on methodological principles from interpretive social science (ISS) and critical social sciences (CSS) this graduate thesis uncovers the voices of youth who have been suspended and/or expelled from a public secondary school in Ontario. Youth in this study spoke to the impact that being suspended and/or expelled had on school climate through describing the adverse changes that they experienced in regards to their relationships with their peers, and school professionals. A unique contribution from my study is a participant’s description of an experience of suspension, which I interpreted as being caused by, the behavioural targeting of a student living with a disability. Many of the participants also explained how the use of disciplinary procedures that rely on sending a student home from school for x amount of days can affect students’ academic progress and success. Furthermore, the similarities between the treatment of disciplined students in the education system, and the treatment of criminal offenders in the justice system found in this study, included: the use of punitive discipline, increased surveillance, and the involvement of the police in disciplinary processes. The youth in this study recognize that the use of suspension and expulsion does not dig beneath the surface and address the root of the problem, and agree that this approach to school discipline is ineffective in regards to correcting behaviour. Finally, all of the youth in this study suggested the development and implementation of more supportive approaches to addressing and preventing unsafe and inappropriate behaviour in schools that aim to keep students in school while resolving the problem. / Thesis / Master of Social Work (MSW)

The literature is inundated with data on 1) academic achievement, 2) family relations, 3) peer relations, and 4) general self-concept in relation to other areas. The purpose of the present study was to examine the relationship between the same variables and the frequency of school suspensions. Raw scores, including full scale and subscale scores, on the Coopersmith Self-Esteem Inventory (SEI) and the Parent Perception Inventory (PPI) were used as the basis for comparing three suspension groups: 1) nonsuspendees (N=14), 2) one-time suspendees (N=l7), and 3) three (or more) time suspendees (N=15), Iess descriptive data were gathered in the areas of 1) sex, age, and family characteristics, 2) academic status, 3) school discipline history, and 4) family mobility. A one-way analysis of variance was applied to the data to determine if there were significant differences among group mean scores. The Scheffe test was applied to determine where differences occurred between specific groups. Three-time suspendees reported significantly lower mean scores than nonsuspendees on the overall SEI and subscale"general self" of the SEI. Three-time suspendees reported significantly lower mean scores than nonsuspendees on 1) the overall PPI, 2) PPI subscale"school--achievement," 3) PPI subscale"family relations," and 4) PPI subscale"general self," Three-time suspendees also reported significantly lower scores than one-time suspendees on PPI subscale"school--achievement." In terms of descriptive data, noteworthy findings were that 1) three-time suspendees reported higher frequencies of"friends suspended during the school year" and"suspensions in prior years" than the other two groups and 2) nonsuspendees reported more placements in higher level mathematics and English classes. / Doctor of Education

This study was conducted to serve as a basis for the making of administrative and policy decisions regarding student suspension. Selected personal, academic, and socio-economic characteristics of the 3,472 secondary students suspended by the Fairfax County (Virginia) Public Schools during 1976-77 were analyzed. In addition, selected organizational and demographic features were examined as they related to reasons for types, lengths, and incidence of the 5,504 suspensions administered. Data were obtained from school suspension reports, records, census, and property assessment information. An ex-post-facto, descriptive research design, including analysis of covariance, two-way analysis of variance, and the chi-square, was employed to determine the extent of relationships among variables selected. It was found that length of suspension varied significantly with reason and type. In-school suspensions were shorter than out-of-school suspensions. Unauthorized absenteeism was the most frequent suspendable offense. Significantly more suspensions than expected were reported per thousand students for all reasons at high minority enrollment and high student mobility rate schools. More students per thousand than expected were suspended longer and more often by these same schools as well as sub-school administrative organizations and small size schools. In-school suspension was used more often than expected by open plant design, medium size, and high student mobility rate schools, while out-of-school suspension was employed more often than expected by sub-school administrative organizations, small size, high student mobility rate, and high minority enrollment schools. Analysis of a random sample of 377 suspendees revealed that reasons for, lengths, incidence of suspension, and ethnic group of suspendees varied significantly with days absent. Those students suspended for attendance problems (unauthorized absence) were absent, on the average, more often than those suspended for any other reason while those suspended for drinking/drug offenses averaged fewer days absent. Average days absent ranged from 23.25 for students excluded one day to 32.90 for those suspended five days. In addition, students suspended more than one time were absent, on the average, more often than one-time suspendees. Black suspended students were absent an average of nearly six days more than white and other suspendees. Average days absent were greater for black suspendees than for whites and others. Standard achievement scores of suspendees varied significantly with reasons for, types, and incidence of suspension, in addition to grade level, sex, and ethnic group. The average standard achievement score for those students suspended for disruptive behavior was lower than the average score of those suspended for any other reason, while higher average achievement scores were attained by those excluded for drinking/drug offenses and insubordination. In-school suspendees’ average achievement score was nearly seventeen points higher than that of the out-of-school suspendees. One-time suspendees attained an average achievement score higher than the average scores for those excluded more than once. After adjustment for maturation, achievement scores of suspendees increased with grade level. The highest incidence of suspension was at the eighth and ninth grade levels. Average achievement scores for male suspendees were lower than for females. Female scores increased when adjusted for the effects of grade level, ethnic group, grade-point average, and parent(s)’ educational attainment level(s). Black suspendees’ average achievement scores were lower than whites and others. Recidivism was significantly higher than expected per thousand students for ninth/tenth grade, male, and black student suspensions. The repeat suspension rate for males was more than twice that for females; the rate for blacks was nearly five times the rate for whites and others. Recidivous suspensions for attendance offenses and insubordination were significantly greater than expected. Neither in-school nor out-of-school repeat suspension rates were significantly greater than one-time suspension rates. / Ed. D.

Full-motion driving simulators require efficient real-time high fidelity vehicle models in order to provide a more realistic vehicle response. Typically, multi-body models are used to represent the vehicle dynamics, but these have the unfortunate drawback of requiring the solution of a set of coupled differential algebraic equations (DAE). DAE's are not conducive to real-time implementation such as in a driving simulator, without a very expensive processing capability. The primary objective of this thesis is to show that multi-body models constructed from DAE's can be reasonably approximated with linear models using suspension elements that have nonlinear constitutive relationships. Three models were compared in this research, an experimental quarter-car test rig, a multi-body dynamics differential algebraic equation model, and a linear model with nonlinear suspension elements. Models constructed from differential algebraic equations are computationally expensive to compute and are difficult to realize for real-time simulations. Instead, a linear model with nonlinear elements was proposed for a more computationally efficient solution that would retain the nonlinearities of the suspension. Simplifications were made to the linear model with nonlinear elements to further reduce computation time for real-time simulation. The development process of each model is fully described in this thesis. Each model was excited with the same input and their outputs were compared. It was found that the linear model with nonlinear elements provides a reasonably good approximation of actual model with the differential algebraic equations. / Master of Science

Vehicle suspension systems play an integral role in influencing the overall performance of a vehicle. The suspension system of a vehicle performs multiple tasks, such as maintaining contact between the tires and the road and isolating the frame of the vehicle from road-induced vibration and shocks. A significant amount of research has been directed to improving the performance of the suspension system by varying the damping coefficient so as to alter the frequency response of the system. This study describes the development of such a damper. The goal of this research has been to design, model, fabricate and test a novel semi-active damper. The damper consists of two independent electronically controlled units placed in series with one another. The system was initially simulated using a 2 DOF quarter-car model and the performance characteristics of the damper were outlined. Following that, multiple design iterations of the damper were created and a MATLAB/Simulink model was used to simulate physical and flow characteristics of the damper. After the design and analysis was complete, the damper was fabricated and tested using a shock dyno at CenTiRe. The test results were then compared to the simulation results so as to confirm performance of the damper. Additionally, the results obtained on the dyno were then compared against that of a relative single semi-active and passive damper. / Master of Science

Master of Science

Vehicle suspensions have been a major focus of research and design since the introduction of the automobile. The two major characteristics that define the performance of a specific suspension design are the vehicle ride and handling. A simplified view of chassis development is that a desirable vehicle ride is provided by a "soft" suspension, and desirable vehicle handling is provided by "stiff" suspensions, it is impossible to simultaneously maximize both vehicle ride and handling in a passive suspension design. However, with the introduction of active components, such as actuators and semiactive dampers, coupled with dynamic control strategies, a more desirable compromise between the benefits of soft and stiff suspensions can be achieved. The purpose of this research is not to create a better suspension, but to investigate how active control can improve vehicle ride. As with any research area, a method for evaluating new ideas is required. Many computational methods exist for determining the ride performance of various suspension designs, however computational results alone can be hard to interpret and often deceiving. The following thesis outlines the design and validation of an experimental test rig for evaluating fully active or semi-active suspension algorithms. The test rig utilizes a fully active electromagnetic actuator which can simulate the performance characteristics of fully active as well as semi-active components which a suspension design may utilize. The demonstration rig couples visual inspection with computational analysis and provides the tools necessary for the designer to accurately interpret the ride performance of a new design and simultaneously compare it with a passive design. The goal is to provide a visual development platform in which new algorithms can be quickly and easily implemented and compared against existing algorithms to determine the performance characteristics of each on a physical system. The test rig demonstrated its ability to test both fully-active and semi-active skyhook control algorithms, and accurately simulated both fully-active and semi-active suspension components. The test rig provides a simple and cost effective way to evaluate new algorithms both computationally and visually on a physical system. / Master of Science

La pollution des eaux est une préoccupation majeure relayée par la Communauté Européenne. Cette problématique s'accentue avec les particules métalliques et l'émergence de produits nanostructurés tels les Nano-objets, leurs Agrégats et leurs Agglomérats (NOAA). Ces NOAA constituent un cas particulier de polluants du fait de leurs propriétés physicochimiques. La surveillance et le contrôle de ces polluants dans les eaux, nécessite le développement d'instruments de mesure aptes à répondre à ce fléau environnemental. Dans ce contexte, la technique de spectroscopie de plasma induit par laser ou Laser-Induced Breakdown Spectroscopy (LIBS) a été retenue à l'INERIS. Elle permet l'identification chimique élémentaire des polluants sous forme particulaire dans la matrice liquide et la détermination de leurs concentrations in-situ et en temps réel. Ce travail de thèse a permis d'optimiser l'analyse des suspensions par LIBS avec deux modes d'échantillonnage. La première partie de l'étude a porté sur le couplage LIBS avec un jet liquide et les limites de détection du titane ont été évaluées à 0.5 mg/L. Dans la deuxième partie, les suspensions ont été aérosolisées avec un nébuliseur et analysées par LIBS. Les résultats obtenus en comparant ces deux modes d'échantillonnage montrent que le jet liquide peut être avantageux pour l'analyse de particules dans les liquides. Cependant le mode aérosol présente un intérêt pratique à condition d'avoir un rendement d'aérosolisation supérieur à 50%. Au final, ce travail de thèse démontre l'applicabilité de la LIBS comme outil potentiel pour l'analyse in situ de particules dans les liquides telle que la surveillance et le contrôle des eaux usées / Water pollution is a major concern, as noted by the European Community. This problem is accentuated with metallic particles and the emergence of nanostructured products such as Nano-Objects, their Aggregates and their Agglomerates (NOAA). These are the special types of pollutants owing their physicochemical properties. The monitoring and control of these pollutants in water require the development of measurement instruments which are capable to anwer this environmental problem. In this context, the technique of Laser-Induced Breakdown Spectroscopy (LIBS) has been developed at INERIS. It not only allows the chemical identification of these particles pollutants present in liquids, but also the determination of their concentrations in situ and in real time. This thesis has optimized the analysis of suspensions by LIBS with two sampling modes. The first mode focused on coupling LIBS with a liquid jet in which the detection limits of titanium dioxide were estimated at 0.5 mg/L. In the second mode, the suspensions were aerosolized with a nebulizer and analyzed by LIBS. The results obtained by comparing these two sampling modes show that the liquid jet may be advantageous for the analysis of suspensions. However, the aerosol mode has a practical interest if it has an aerosolization efficiency of over 50%. Finally, this work demonstrates the applicability of LIBS as a potential tool for in situ particle analysis of suspensions such as monitoring and control of wastewater

L’embolisation thérapeutique est devenu le traitement de choix pour l’hémorragie, les malformations artériovéneuses ou certains types de cancer. Parmi différents agents d’embolisation,les microsphères non dégradables (Embozene®, Bead BlockTM,…) sont les plus utilisées. Leur forme bien sphérique et leur taille calibrée permettent un meilleur ciblage dans les vaisseaux et une bonne qualité de l’occlusion. Dans certains cas cliniques, l’embolisation temporaire, envisageable avec l’utilisation des microsphères résorbables peut être bénéfique pour les patients. Le but du travail réalisé au cours de cette thèse a été le développement de microsphères résorbables satisfaisant les différents critères pour être employées comme matériaux d’embolisation (taille calibrée,biocompatibles, élastique pour être injectée au travers des cathéters mais suffisamment rigide pour résister à la pression sanguine). Dans cet objectif, nous avons développé une méthode de synthèse de microsphères constituées d’hydrogels hydrolysables par polymérisation en suspension. Une large gamme de microsphères ont été synthétisées en modulant la nature du réticulant et/ou la composition des milieux de polymérisation. Les expériences in vitro ont démontré que les microsphères obtenues sont satisfaisantes pour permettre leur injection au travers des cathéters. La dégradation rapide des ponts de réticulation a été confirmée à travers la diminution du module élastique G’ et du pH du surnageant, accompagnée d’une augmentation du taux de gonflement.Malgré une dégradation partielle des microsphères (due à une réaction secondaire formant des liaisons de réticulation non dégradables), le temps de l’hydrolyse a répondu parfaitement au cahier de charges (entre 7 et 49 jours). Des études complémentaires pour optimiser la réaction de polymérisation vont permettre le développement de microsphères totalement dégradables. / Therapeutic embolization is nowadays a first line treatment for haemorrhage, arteriovenous malformation or tumors. Among different embolization agents, non degradable microspheres(Embozene®, Bead BlockTM,…) are the most employed thanks to their well calibrated spherical shape which allows good occlusion. In some cases including treatment of uterine fibroids or chemo-sensitive tumors, it may be interesting to achieve a temporary embolization to avoid definitive destruction of the tissue. Temporary embolization would be possible using biodegradable microspheres. The aim of our work was to develop degradable microspheres having all requiredcharacteristics to be used as embolization material (well calibrated in size, biocompatible, rigide enough to resist blood pressure but elastic enough to remain intact during injection through catheter). To this purpose, we have developed hydrolysable hydrogel based microspheres by suspension polymerization. A wide range of microspheres was synthesized by varying the type of crosslinker and composition of the polymerization medium. In vitro test showed that the microspheres have suitable characteristics to pass through catheter. Degradation studies revealed a rapid diminution of G’ modulus and the pH of the supernatants, accompanied by an increase of swelling ratio due to the hydrolysis of the crosslinkings. Although microspheres were not totally degradable as expected (since a side reaction had created non degradable crosslinking during the polymerisation), characterisations showed promising results that the degradation did occur within a suitable time scale requirements for temporal embolization.