Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 140-150). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 100-116). Also available on the World Wide Web.

Thesis (M. S.)--Architecture, Georgia Institute of Technology, 2006. / Thomas-Mobley, Linda, Committee Member ; Uhlik, Felix, Committee Member ; Roper, Kathy O., Committee Chair

L’objectif de cette thèse est double : 1) contribuer à la production de connaissances dans le champ théorique de la didactique professionnelle sur les activités liées aux systèmes vivants ; 2) aider à la conception, à l’ingénierie pédagogique et à l’évaluation de l’EVAH VirTeaSy. L’examen de la littérature dans le domaine des EVAH dentaires montre que les EVAH « haptiques » semblent être les plus pertinents pour répondre aux problématiques de formation en implantologie. Cependant, bien que des études montrent leur efficacité du point de vue de l’apprentissage, il reste des problèmes à résoudre en termes de méthodologie de conception. En effet, la démarche de conception s’appuie couramment sur des collaborations entre experts métiers et informaticiens qui aboutissent au développement d’EVAH technocentrés. Afin de contourner les écueils constatés dans ce type de démarche, nous choisissons d’inclure les sciences humaines sur l’ensemble du processus de conception de l’EVAH. Pour identifier les compétences à viser dans l’EVAH, nous mobilisons, dans le cadre de la didactique professionnelle, une analyse de l’activité. Celle-ci se finalise par l’identification de la structure conceptuelle de la situation reposant sur des concepts organisateurs de l’activité en liens avec des variables et des indicateurs. Notre première étude s’attache ainsi à identifier la structure conceptuelle de la situation en implantologie dentaire. Au cours de situations réelles de pose d’implant dentaire, des données d’enregistrement ont été recueillies et complétées par des verbalisations obtenues lors d’entretiens d’auto-confrontation. L’analyse des données à l’aide de la méthodologie des catégories conceptualisantes nous a permis de faire émerger les concepts organisant l’activité des dix chirurgiens-dentistes observés. L’activité d’implantologie consiste à réaliser un compromis entre le concept organisateur « d’émergence » qui permet de réaliser le projet prothétique et le concept « d’ancrage » qui permet au projet prothétique de durer dans le temps. Ces deux concepts n’étant pas toujours convergents. La conception de VirTeaSy s’appuie sur les résultats de l’étude 1 et se réalise grâce à une méthodologie en cinq étapes. Notre expérience de cette mise en œuvre méthodologique montre qu’il faut constamment faire des choix. Ces choix reposent dans un premier temps sur la littérature et conduisent à définir des éléments de conception généraux. Ces éléments sont ensuite spécifiés à l’aide des résultats de l’analyse de l’activité, celle-ci prend alors toute sa pertinence afin que l’EVAH traduise les compétences-clefs que les apprenants doivent construire pour être efficaces. L’étude 2 porte sur le transfert d’apprentissage du virtuel au réel. Pour ce faire, trente-deux dentistes sont répartis de façon aléatoire dans trois groupes : un groupe (n=10) nommé GRV formé dans VirTeaSy, un groupe (n=11) nommé GT formé de manière traditionnelle et un groupe (n=11) nommé contrôle (GC) ne recevant aucune formation. Tous les sujets sont novices en implantologie dentaire. Une semaine après que chaque groupe ait suivit sa formation, tous les sujets réalisent la tâche de réinvestissement consistant à poser un implant sur un cadavre humain. Pour chaque sujet, nous mesurons, à l’aide d’un scanner, la différence entre la performance demandée et la performance réalisée. Les mesures portent sur l’angulation, l’émergence et la centration. Nos résultats ne montrent pas de différence significative entre les trois groupes. Des prolongements à cette thèse sont en cours de mise en œuvre. Il s’agit : 1) d’étendre l’analyse de l’activité à une population internationale ; 2) d’évaluer VirTeaSy grâce à différents protocoles incluant les fonctionnalités issues de l’analyse de l’activité ; 3) d’élargir le périmètre de formation de VirTeaSy à l’odontologie. / The objective of this thesis is twofold: 1) to build knowledge in the theoretical field “didactique professionnelle” for living systems activities; 2) to help design and assess VirTeaSy. An analysis of the literature in dental V.E.T showed that “haptic V.E.T.” seem to be the most relevant for the challenge of training in dental implantology. However, some studies show, there are still problems to be solved in terms of design methodology. Indeed, the usual design approach relies on collaboration between dental experts and IT engineers. In this approach, IT engineers carry on the V.E.T. development. This means that the result is often a V.E.T. developed from an IT point of view rather than from a learning point of view. To overcome issues associated with this type of approach, we have chosen to include experts in pedagogy in design process of Virteasy.We have undertaken an analysis of activity within the framework of “didactique professionnelle” in order to identify the skills which the students were going to learn with our V.E.T. The final aim of this analysis is identification of the “conceptual structure of the situation” (structure conceptuelle de la situation) based on “organizing concepts” (concept organisateur) of the activity links with variables and indicators. Our first study deals with identifying the “conceptual structure of the situation” in dental implantology. Recorded data (movies) were gathered from ten dentist experts during a live implant surgery. This was followed by in depth interviews within the dentists watching the recording of the surgery and verbalizing their mental process during the procedure. A content analysis of the interview showed that the mental process of the dentist performing an implantology procedure is based on two concepts. The first is concept is “emergence”, the dentist’s actions are guided by the prosthetic teeth which is going to be fitted on the implant. The second is “anchorage”, the dentist’s action are guided by the longevity of the implant. These two concepts are not always compatible which shows the real challenge faced by implant experts. VirTeaSy design is based on the results of Study 1 and make with a five-step methodology Our experience shows that a lot decision have to be made at each stage of the methodology. These decisions were based initially on literature and led to the definition of general design elements. These components were then specified using the results of the activity analysis. This showed how important and relevant an activity analysis was in making specific and accurate decisions in the design of V.E.T. Because of this process, the V.E.T. is enable to teach skills and competences that students must acquire to perform procedures in real life situations. The study 2 focused on learning transfer from virtual to reality. To do this, thirty-two dentists are randomized into three groups: one group (n = 10) named Group with Virtual Training (GVT); one group (n = 11) named Group with Traditional Training (GTT) and one group (n = 11 ) named Control Group (CG) receiving no training. All subjects were novice to dental implantology. One week after training, all subjects had to perform a task during which they had to demonstrate and apply the skills acquired during the training (“the reinvestment” task consisting of placing an implant on a human corpse). For each subject, we measured the difference between the required performance and the performance achieved using a scanner. We recorded three kind of measure: angle; depth and center. The results showed no significant difference between the three groups. Extensions of this thesis are being implemented. Some are based on international partnerships with well-known Universities. These extensions are: 1) to extend the activity analysis to an international population, 2) To evaluate VirTeaSy through various protocols including features from the activity analysis, 3) To broaden the scope of using VirTeasy in dental training.

xvi, 216 p. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / The primary purpose of this study was to design and validate a measure of teacher knowledge of Universal Design for Assessment (TK-UDA). Guided by a validity framework, a number of inferences, assumptions, and evidences supported this investigation. By addressing a series of research questions, evidence was garnered for the use of the measure to describe what teachers know about assessment accessibility issues through their application of seven UDA principles. The investigation used research designs and sampling procedures specific to each research question. The TK-UDA was designed to capture depth of knowledge, from background to declarative to applied, through a variety of item types. Internal, external, and teacher reviews provided evidence to support the content validity of the measure, and, based on the feedback from these reviews, the measure was revised to improve content and clarity. The measure was then implemented online; a purposeful sample of experts and inservice and preservice teachers was invited to participate in the study. It was anticipated that these participants would represent a range of knowledge of UDA. Following measure implementation, analyses were conducted to evaluate whether performance on items accurately reflected a continuum of teacher knowledge. Evidence of discriminant/criterion-related validity was examined by evaluating group differences. Based on results from t -tests and MANOVAs, no significant differences between groups (based on level of expertise) were found. Item Response Theory (IRT) scaling of items along a continuum indicated that declarative knowledge items were generally less difficult than applied knowledge items. IRT scaling of person scores represented a rather narrow range of knowledge within the sample. Reliability estimates from the IRT scaling and test-retest indicated strong item reliability, relatively weak person reliability, and satisfactory test-retest reliability, respectively. To obtain evidence regarding the usefulness of the measure to determine professional development needs, a Kruskal-Wallis rank-order test was conducted to evaluate the differential difficulty of UDA elements within the applied knowledge section. This provided initial evidence for identifying professional development needs at the element level. These results provide information that will guide further instrument development and future research in this area. / Committee in charge: Paul Yovanoff, Chairperson, Educational Methodology, Policy, and Leadership; Elizabeth Ham, Member, Special Education and Clinical Sciences; Leanne Ketterlin Geller, Member, Educational Methodology, Policy, and Leadership; Douglas Blandy, Outside Member, Arts and Administration

Increasingly, educational reform efforts are turning towards data-driven decision making strategies to help teachers improve instruction through skills-based instruction/content that is both measurable and aligned to common rigorous standards, such as the Common Core State Standards (CCSS). Examining the impact of a formative online assessment system on a summative measurement of student achievement may provide evidence that data-driven instructional platforms can impact student achievement and learning outcomes. Guided by the theoretical frameworks of Vygotsky and Dewey, along with the concepts of multiple intelligence, constructivism, and mastery learning, this study examined the relationship between student scores from an online formative assessment administered quarterly and an end-of-year summative evaluation. A stepwise multiple regression analyzed the predictive power of the iReady formative assessment program towards archived SAT-10 reading and mathematics data among Grades 1-4 students, before and after the iReady program was implemented (N = 339). The results showed a significant relationship between the iReady program and SAT-10, explaining 11.6% of the variance in SAT-10 scores. The study's intended audience is educators, school districts, and policy makers who are using the achievement data produced by formative assessments to improve results on measures of academic achievement, leading to positive social change.

Due to the limitations of silicon (Si), there is a paradigm shift in research focusing on wide-bandgap-based (WBG) materials. SiC power semiconductors exhibit superiority in terms of switching speed, higher breakdown electric field, and high working temperature, slowly becoming a global solution in harsh medium-voltage (MV) high-power environments. However, to utilize the SiC MOSFET device to achieve those next-generation, high-density, high-efficiency power electronics converters, one must solve a plethora of challenges. For the MV SiC MOSFET device, a high-performance gate-driver (GD) is a key component required to maximize the beneficial SiC MOSFET characteristics. GD units must overcome associated challenges of electro-magnetic interference (EMI) with regards to common-mode (CM) currents and cross-talk, low driving loop inductance required for fast switching, and device short-circuit (SC) protection. Developed GDs (for 1.2 kV, and 10 kV devices) are able to sustain dv/dt higher than 100 V/ns, have less than 5 nH gate loop inductance, and SC protection, turning off the device within 1.5 us. Even with the introduction of SiC MOSFETs, power devices remain the most reliability-critical component in the converter, due to large junction temperature (Tj) fluctuations causing accelerated wear-out. Real-time (online) measurement of the Tj can help improve long-term reliability by enabling active thermal control, monitoring, and prognostics. An online Tj estimation is accomplished by generating integrated intelligence on the GD level. The developed Tj sensor exhibits a maximum error less than 5 degrees Celsius, having excellent repeatability of 1.2 degrees Celsius. Additionally, degradation monitoring and an aging compensation scheme are discussed, in order to maintain the accuracy of the sensor throughout the device's lifetime. Since ultra high-voltage SiC MOSFET devices (20 kV) are impractical, the modular multilevel converter (MMC) emerged as a prospective topology to achieve MV power conversion. If the kernal part of the power-cell (main constitutive part of the MMC converter) is an SiC MOSFET, the design is able to achieve very high-density and high-efficiency. To ensure a successful operation of the power-cell, a systematic design and assessment methodology (DAM) is explored, based on the 10 kV SiC MOSFET power-cell. It simultaneously addresses challenges of high-voltage insulation, high dv/dt and EMI, component and system protections, as well as thermal management. The developed power-cell achieved high-power density of 11.9 kW/l, with measured peak efficiency of n=99.3 %@10 kHz. It successfully operated at Vdc=6 kV, I=84 A, fsw>5 kHz, Tj<150 degrees Celsius and had high switching speeds over 100 V/ns. Lastly, to achieve high-power density and high-efficiency on the MV converter level, challenges of high-voltage insulation, high-bandwidth control, EMI, and thermal management must be solved. Novel switching cycle control (SCC) and integrated capacitor blocked-transistor (ICBT) control methodologies were developed, overcoming the drawbacks of conventional MMC control. These novel types of control enable extreme reduction in passive component size, increase the efficiency, and can operate in dc/dc, dc/ac, mode, potentially opening the modular converter to applications in which it was not previously used. In order to explore the aforementioned benefits, a modular, scalable, 2-cell per arm, prototype MV converter based on the developed power-cell is constructed. The converter successfully operated at Vdc=12 kV, I=28 A, fsw=10 kHz, with high switching speeds, exhibiting high transient immunity in both SCC and ICBT. / Doctor of Philosophy / In medium-voltage applications, such as an electric grid interface in highly populated areas, a ship dc system, a motor drive, renewable energy, etc., land and space can be very limited and expensive. This requires the attributes of high-density, high-efficiency, and reliable distribution by a power electronics converter, whose central piece is the semiconductor device. With the recent breakthrough of SiC devices, these characteristics are obtainable, due to SiC inherent superiority over conventional Si devices. However, to achieve them, several challenges must be overcome and are tackled by this dissertation. Firstly, as a key component required to maximize the beneficial SiC MOSFET characteristics, it is of utmost importance that the high-performance gate-driver be immune to interference issues caused by fast switching and be able to protect the device against a short-circuit, thus increasing the reliability of the system. Secondly, to prevent accelerated degradation of the semiconductor devices due to high-temperature fluctuations, real-time (online) measurement of the Tj is developed on the gate-driver to help improve long-term reliability. Thirdly, to achieve medium-voltage high-power density, high-efficiency modular power conversion, a converter block (power-cell) is developed that simultaneously addresses the challenges of high-voltage insulation, high interference, component and system protections, and thermal management. Lastly, a full-scale medium-voltage modular converter is developed, exploiting the advantages of the fast commutation speed and high switching frequency offered by SiC, meanwhile exhibiting exceptional power density and efficiency.

In comparison with Si-based converters, the emerging Medium Voltage (MV) SiC-based converters can achieve higher blocking voltage capability, lower on-resistance, faster switching speed with less switching related losses and run under higher temperature. Thus, theoretically, it can achieve much higher power density, which becomes very promising for future power transmission and distribution. However, in order to achieve the desired high power density, insulation system of the MV SiC-based converter must be compact. Therefore, challenges for the insulation system gradually appeared, as the insulation size becomes smaller and the Electric field (E-field) intensity significantly increases. Under such high E-field intensity, it is necessary and important to eliminate Partial Discharge (PD) for such power converters, since the converter system is vulnerable to PDs. Developing an insulation design, assessment and online monitoring method to help reach a compact and PD free insulation system for MV SiC-based converters is a goal of this work. General insulation design and assessment guidelines based on experimental PD investigation and physics-based model –Experimental PD investigation is completed for internal void discharge, surface discharge, and point discharge representative coupons under square excitations. Based on the data and the existing knowledge about PD mechanisms, widely accepted PD models are selected. Using these physics-based models, simulation results can demonstrate the major features observed in the experiments. With the experimental data and valid PD models, several general insulation design and assessment guidelines are proposed, which could be further applied during converter prototypes development. Partial Discharge elimination methodology and design examples – By using the laminated bus as the design example, internal void evaluation and analysis method is demonstrated. Then, targeting the internal PD-free design with reasonable insulation thickness, several insulation improvement methods are applied and experimentally verified by using representative coupons. After understanding the possible ways for evaluating and eliminating internal voids, a PCB-based planar bus is designed and fabricated, which shows great insulation improvement after experimental verification. In order to eliminate PDs in the air and shrink the insulation distance, three ways for managing E-field distribution in air are demonstrated by three examples. First, by using the interconnections among the power modules, Rogowski-based current-sensing board, and the laminated bus as an example, E-field distribution can be estimated by Finite Element Analysis (FEA) and its management can be achieved by geometrical modifications. Second, for the one-turn inductor, a methodology is demonstrated that builds a coaxial insulation structure with proper termination technology in order to squeeze air out of the insulation system. Finally, E-field shielding technology is applied along the heatsink edges in order to make the E-field distribution uniform and to shrink the insulation distance between the heatsink and the cooling system. After improving the insulation, this work shrinks the converter unit size by around 50% while maintaining its PD-free status under normal operation conditions. Besides the significant increase in power density and weight reduction, the entire converter system has less ringing and better current-sharing performance due to reductions of the parasitic inductance. Partial Discharge online monitoring via acoustic and photon detection methods –Targeting the online monitoring and even localization of surface discharge for power converter applications, two novel types of sensors have been proposed and fabricated. In order to verify the concepts, one example with experimental results has been given for each type of sensor. The experimental data demonstrates that such sensors can be placed inside the converter and online monitoring can be realized for surface or corona discharges by capturing either the acoustic signal or the photons that are generated by discharge events. / Doctor of Philosophy / A unproper designed insulation system can take more than 50% volume of Medium Voltage (MV) SiC-based converters and have significant internal or external Partial Discharge (PD), which can not only accelerate the insulation aging but also risk to multiple aspects of the converter system. Therefore, developing an insulation design, assessment and online monitoring method to help reach a compact and PD free insulation system for MV SiC-based converters is a goal of this work. Experimental PD investigation is completed for internal void discharge, surface discharge, and point discharge representative coupons under square excitations. Several general insulation design and assessment guidelines are proposed based on the experimental PD investigation and physics-based explanations, which are further applied during converter prototypes development. Then, PD elimination methodology is developed and demonstrated by design examples. By using the laminated bus as an example, internal void evaluation and analysis method is demonstrated. Then, targeting the internal PD-free design with reasonable insulation thickness, several insulation improvement methods are applied and experimentally verified by using representative coupons. In order to eliminate PDs in air and shrink the insulation distance, three ways for managing E-field distribution in air are demonstrated by three examples. First, by using the interconnections among the power modules, Rogowski-based current-sensing board, and the laminated bus as an example, E-field distribution can be estimated by Finite Element Analysis (FEA) and its management can be achieved by geometrical modifications. Second, for the one-turn inductor, a coaxial insulation structure with proper termination technology in order to squeeze air out of the insulation system is demonstrated. Finally, E-field shielding technology is applied along the heatsink edges in order to make the E-field distribution uniform and to shrink the insulation distance between the heatsink and the cooling system. After improving the insulation, this work shrinks the converter unit size by around 50% while maintaining its PD-free status under normal operation conditions. Besides the significant increase in power density and weight reduction, the entire converter system has less ringing and better current-sharing performance due to reductions of the parasitic inductance. Targeting the PD online monitoring for power converter applications, two novel types of sensors have been proposed and fabricated. In order to verify the concepts, one example with experimental results has been given for each type of sensor. The experimental data demonstrates that such sensors can be placed inside the converter and online monitoring can be realized for surface or corona discharges by capturing either the acoustic signal or the photons that are generated by discharge events.

DIRECT USE OF PGV FOR ESTIMATING PEAK NONLINEAR OSCILLATOR DISPLACEMENTS K&Uuml / &Ccedil / &Uuml / KDOGAN, Bilge Recently established approximate methods for estimating the lateral deformation demands on structures are based on the prediction of nonlinear oscillator displacements (Sd,ie). In this study, a predictive model is proposed to estimate the inelastic spectral displacement as a function of peak ground velocity (PGV). Prior to the generation of the proposed model, nonlinear response history analysis is conducted on several building models of wide fundamental period range and hysteretic behavior to observe the performance of selected demands and the chosen ground-motion intensity measures (peak ground acceleration, PGA, peak ground velocity, PGV and elastic pseudo spectral acceleration at the fundamental period (PSa(T1)). Confined to the building models used and ground motion dataset, the correlation studies revealed the superiority of PGV with respect to the other intensity measures while identifying the variation in global deformation demands of structural systems (i.e., maximum roof and maximum interstory drift ratio). This rational is the deriving force for proposing the PGV based prediction model. The proposed model accounts for the variation of Sd,ie for bilinear hysteretic behavior under constant ductility (&micro / ) and normalized strength ratio (R) associated with postyield stiffness ratios of = 0% and = 5%. Confined to the limitations imposed by the ground-motion database, the predictive model can estimate Sd,ie by employing the PGV predictions obtained from the attenuation relationships. This way the influence of important seismological parameters can be incorporated to the variation of Sd,ie in a fairly rationale manner. Various case studies are presented to show the consistent estimations of Sd,ie by the proposed model using the PGV values obtained from recent ground motion prediction equations.

Diploma thesis deals with design and assessment of bracing the excavation during the construction of subway in the route Dejvická – Motol. The introduction presents possible methods of bracing. The next part is design and assessment of the chosen option, which ensure this construction. It consists of considering of engineering-geological conditions, static design, technological process of building and construction plans.