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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
151

An Examination of the Effects of Mathematics Anxiety, Modality, and Learner-Control on Teacher Candidates in Multimedia Learning Environments

Ward, Elena 27 September 2008 (has links)
This study examined mathematics anxiety among elementary teacher candidates, and to what extent it interacted with the modality principle under various degrees of learner-control. The experiment involved a sample of 186 elementary teacher candidates learning from eight versions of a computer program on division with fractions. The eight versions varied in modality of presentation (diagrams with narration, or diagrams with written text), control of pacing (pacing was controlled by either the learner or the system), and control of sequence (sequence was controlled by either the learner or the system). A pre-test, post-test, demographic questionnaire, subjective measure of mental effort, and the Abbreviated Math Anxiety Survey were also administered. This study revealed that mathematics anxiety was significantly positively correlated with mental effort, and significantly negatively correlated with engagement, pre-test and post-test scores. Additionally, a modality x pacing interaction was observed for both high prior knowledge and low mathematics-anxious students. Under system-pacing, the modality effect was observed, and these students achieved higher far transfer scores when learning from the diagrams and narration modality condition. However, under learner-pacing, the modality effect reversed, and high prior knowledge and low mathematics-anxious students performed better on far transfer scores when learning from the diagrams and written text modality condition. Low prior knowledge, and highly mathematics-anxious students performed poorly in all treatment conditions. Additional interactions involving sequence-control, and a four-way interaction involving prior knowledge, modality, sequence-control, and pacing were also uncovered. The results from this study demonstrate that prior knowledge and mathematics anxiety have a complex relationship with the effectiveness of the format of instruction, and the design of instructional materials needs to take into account these individual differences. / Thesis (Master, Education) -- Queen's University, 2008-09-25 19:38:33.9
152

A Novel Iterative Method for Non-invasive Measurement of Cardiac Output

Klein, Michael 29 November 2013 (has links)
This thesis provides a first description and proof-of-concept of iterative cardiac output measurement (ICO) – a respiratory, carbon-dioxide (CO2) based method of measuring cardiac output (CO). The ICO method continuously tests and refines an estimate of the CO by attempting to maintain the end-tidal CO2 constant. To validate the new method, ICO and bolus thermodilution CO (TDCO) were simultaneously measured in a porcine model of liver transplant. Linear regression analysis revealed the equation ICO = 0.69•TDCO + 0.65 with a Pearson correlation coefficient of 0.89. Analysis by the method of Bland and Altman showed a bias of -0.2 L/min with 95% limits of agreement from -1.1 to 0.7 L/min. The trending ability of ICO was determined using the half-circle polar plot method where the mean radial bias, the standard deviation of the polar angle, and 95% confidence interval of the polar angle were -8º, ±17º, and ±33º, respectively.
153

A Novel Iterative Method for Non-invasive Measurement of Cardiac Output

Klein, Michael 29 November 2013 (has links)
This thesis provides a first description and proof-of-concept of iterative cardiac output measurement (ICO) – a respiratory, carbon-dioxide (CO2) based method of measuring cardiac output (CO). The ICO method continuously tests and refines an estimate of the CO by attempting to maintain the end-tidal CO2 constant. To validate the new method, ICO and bolus thermodilution CO (TDCO) were simultaneously measured in a porcine model of liver transplant. Linear regression analysis revealed the equation ICO = 0.69•TDCO + 0.65 with a Pearson correlation coefficient of 0.89. Analysis by the method of Bland and Altman showed a bias of -0.2 L/min with 95% limits of agreement from -1.1 to 0.7 L/min. The trending ability of ICO was determined using the half-circle polar plot method where the mean radial bias, the standard deviation of the polar angle, and 95% confidence interval of the polar angle were -8º, ±17º, and ±33º, respectively.
154

Exact feedback linearization with state derivative feedback for high-performance field-oriented induction motor speed/position control

Boukas, Theocharis K. 05 1900 (has links)
No description available.
155

THE PRECAUTIONARY PRINCIPLE & COMPLEX SOVEREIGNTY: USING THE PATHWAYS FRAMEWORK TO EXPLAIN DOMESTIC POLICY OUTCOMES

2015 February 1900 (has links)
The precautionary principle has emerged as one of the most contentious international norms within international environmental law. Yet, despite the vexing conceptual uncertainties confronting the precautionary principle, it is repeatedly invoked by policy makers and incorporated within international and domestic environmental law and agreements. This thesis explores how the international norm of precaution comes to be translated from the international sphere to domestic public policy. The research utilizes the pathways framework, which suggests that there are three additional pathways in additional to the direct implementation of international rules in national law and policy - international norms and discourse, markets and direct access - through which actors, institutions and interests can influence domestic and firm-level policy change. The findings propose an explanation of why Canada came to adopt a particular version of the precautionary principle, also revealing the complex nature of norm transfer, the significance of multiple causal pathways of influence and the interactions arising along these pathways.
156

Just Housing: An Examination of Inequality in John Rawls’ Theory of Justice as Fairness

Mackie, Julian E 01 January 2015 (has links)
How would a housing system work in a just society? How do we account for differences in opportunity according to one’s birthplace? These two questions, both a result of our recent housing crisis, can be addressed through inquiries into policy, economics, history, or other forms of social sciences. In this paper I attempt to address these questions instead through a philosophical lens by examining the principles that guide the distribution of goods in our society. It is from such a theory that we can construct the fairest government or economic policies. Theories of distributive justice try to account for the fairest distribution of goods in a society. I take one such theory, John Rawls’ theory of justice as fairness, and apply it to the distribution of housing. I begin by deconstructing the core principles of Rawls’ theory and analyzing how each applies to housing. Then I make an argument about the fairness of these outcomes. My conclusion is, in fact, Rawls theory does not adequately account for the importance of housing in our society. In doing so, I hope to demonstrate the inequalities that face families throughout our society by illustrating the profound impact of housing on one’s well-being as well as one’s opportunity to succeed.
157

Könskvotering i bolagsstyrelser : Ett instrument för att främja en jämställd arbetsmarknad?

Palm Weman, Isabella January 2015 (has links)
The European Union has been working to promote equality between women and men for a long time. Despite this, Sweden still have a gender segregated labor market where men generally has the leading positions. According to European law the member states shall promote gender equality and to take all appropriate measures. Statutory gender quotas for company boards is one such measure that some of the European member states have implemented in national law. The Swedish law has no provisions governing gender quotas and therefore the purpose of this study is to explain how gender quotas for company boards relate to current law, both of European law and national legislation. After examining the legal situation I am also referring to examine however an extent eventual legislation is possible, with the principle of non-discrimination in consideration. The main goal of Swedish gender equality policy is that women and men should have the same power to shape society and their own lives. There should be just as much power and similar power resources between women and men. The government argued that a change must be made regarding the structural power relations between men and women, where women as a group are still subordinate to men. It is found that women more generally occupies subordinate positions in society. This is something that has its origin from the past. The question is whether the statutory quotas are the correct action to take to fulfill this target objective.
158

Minimum principle of the temperature in compressible Navier-Stokes equations with application to the existence theory

Zhang, Weizhe 27 August 2014 (has links)
This thesis is on the Navier-Stokes equations which model the motion of compressible viscous fluid. A minimum principle on the temperate variable is established. Under the thermo-insulated boundary conditions and some reasonable assumptions on the solution, the minimum of the temperature does not increase. To our best knowledge, that's the first result on the minimum principle of the temperature variable in the compressible Navier-Stokes equation. As an application of the minimum principle, global in time existence of the weak solution for the Navier-Stokes equations is established when the viscosities and heat conductivity are power functions of the temperature. In this model the temperature is coupled with density which may have vacuum or concentration and the heat conductivity has possible degeneracy. However the temperature is proved to obey the minimum principle, which secured the dissipative mechanism of the system, and paved the road to the existence theory.
159

Rigid Quasilocal Frames

McGrath, Paul January 2014 (has links)
This thesis begins by introducing the concept of a rigid quasilocal frame (RQF) as a geometrically natural way to define an extended system in the context of the dynamical spacetime of general relativity. An RQF is defined as a two-parameter family of timelike worldlines comprising the worldtube boundary of the history of a finite spatial volume with the rigidity conditions that the congruence of worldlines is expansion-free (the ``size'' of the system is not changing) and shear-free (the ``shape'' of the system is not changing). We demonstrate that this frame exists in flat and arbitrary curved spacetimes and, moreover, exhibits the full six motional time-dependent degrees of freedom we are familiar with from Newtonian mechanics. The latter result is intimately connected with the fact that a spatial slice through the RQF - having a two-sphere topology - always admits precisely six conformal Killing vector (CKV) fields (three boosts and three rotations) associated with the action of the Lorentz group on a two-sphere. These CKVs, along with the four-velocity of observers on the RQF, are then used to quasilocally define the energy, momentum, and angular momentum inside an RQF without relying on the pre-general relativistic practice of appealing to spacetime symmetries. These quasilocal definitions for energy, momentum, and angular momentum also involve replacing the local matter-only stress-energy-momentum (SEM) tensor with the Brown-York matter plus gravity boundary SEM tensor. This allows for the construction of completely general conservation laws which describe the changes in a system in terms of fluxes across the boundary. Furthermore, since an RQF is a congruence with zero expansion and shear only relevant fluxes appear in these conservation laws - that is, fluxes due merely to changes in the size or shape of the boundary are eliminated. These resulting fluxes are simple, exact, and quantified in terms of operationally-defined geometrical quantities on the boundary and we show that they explain at a deeper level the mechanisms behind gravitational energy and momentum transfer by way of the equivalence principle. In particular, when we accelerate relative to a mass, the energy changes at a rate proportional to our acceleration times the momentum (and we propose an exact gravitational analogue of the electromagnetic Poynting vector to capture this idea). Similarly, the momentum of that object changes at a rate proportional to our acceleration times the energy. This new insight has fascinating consequences for how we should understand everyday occurrences like a falling apple - that is, the change in energy of the apple involves frame dragging while the change in momentum involves extrinsic curvature effects near the apple. Our naive general relativistic intuition tells us that these quantities should be so tiny that they should be negligible and, indeed, they are tiny but they are multiplied by huge numbers to give rise to macroscopic effects. This is how general relativity universally explains the transfer of energy and momentum but we needed rigid quasilocal frames to uncover this beautiful property of nature. Using the RQF formalism we also investigate a variety of specific problems. In particular, while looking at time-dependent rotations we discover that the reason Ehrenfest's rigid rotating disk paradox has gone unsolved for so long is that rotation introduces a subtle non-locality in time. By this we mean that, in order to maintain rigidity while undergoing time-dependent rotation, one needs to know, not only the instantaneous rotation rate, but the entire history of the motion. This makes it impossible to keep a volume of observers rigid but is doable with an RQF. We also consider RQFs in the small-sphere limit to derive many of our results and one example with particularly interesting consequences involves Bell's spaceship accelerating through an electromagnetic field. Here, we show that the change in electromagnetic energy inside the spaceship is made up of two pieces: the usual electromagnetic Poynting flux accounts for half the change while the gravitational Poynting vector equally contributes to make up the other half. This means that electromagnetism in flat spacetime generically does not tell you what is actually going on. Rather, the curvature due to the electromagnetic field necessitates a fully general relativistic treatment to get the whole story. We also use the RQF linear momentum conservation law in the context of stationary observers and fields to derive, for the first time, an exact fully general relativistic analogue of Archimedes' law. In essence, this law demonstrates that the weight of the matter and gravitational fields contained in a finite region of space is supported by the stresses (buoyant forces) acting on the boundary of that region. Furthermore, in a post-Newtonian approximation, we derive a simple set of quasilocal conservation laws which describe non-relativistic systems bound by mutual gravitational attraction. In turn, we use these laws to obtain expressions for the rates of gravitational energy and angular momentum transfer between two tidally interacting bodies - that is, the tidal heating and tidal torque - without the need to define unphysical pseudotensors. Moreover, the RQF approach explains these transfers of energy and momentum again, not as the difference of forces acting on a tidal bulge, but instead more fundamentally in the language of the equivalence principle in terms of ``accelerations relative to mass''. Throughout this work we demonstrate that the RQF approach always gives very simple, geometrical descriptions of the physical mechanisms at work in general relativity. Given that this approach also includes both matter and gravitational energy, momentum, and angular momentum and does not rely on spacetime symmetries to define these quantities, we argue that we are seeing here strong evidence that the universe is actually quasilocal in nature. We are really deeply ingrained with a local way of thinking, so shifting to a quasilocal mindset will require great effort, but we contend that it ultimately leads to a deeper understanding of the universe.
160

Vlasov's Equation on a Great Circle and the Landau Damping Phenomenon

Shen, Shengyi 16 December 2014 (has links)
Vlasov's equation describes the time evolution of the distribution function for a collisionless physical system of identical particles, such as plasma or galaxies. Together with Poisson's equation, which yields the potential, it forms the Vlasov-Poisson system. In Euclidean space this system has been extensively studied in the past century. It has been recently shown that the Valsov-Poisson system exhibits an interesting, counter-intuitive phenomenon called Landau damping. Our universe, however, may not be at on a large scale, so it is important to introduce and study a natural extension of the Vlasov-Poisson systems to spaces of constant curvature. Our starting point is the unit sphere S2, but we further restrict our study to one of its great circles. We show that, even for this reduced model, the potential function has more singularities than in the classical case. Our main result is to derive a Penrose stability criterion for the linear Landau damping phenomenon. / Graduate / 0405 / shengyis@uvic.ca

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