This dissertation addresses the problem of rigid-body attitude tracking control under three scenarios of high relevance to many aerospace guidance and control applications: adaptive attitude-tracking control law development for a spacecraft with time-varying inertia parameters, velocity-free attitude stabilization using only vector measurements for feedback, and smooth angular velocity observer design for attitude tracking in the absence of angular velocity measurements. Inertia matrix changes in spacecraft applications often occur due to fuel depletion or mass displacement in a flexible or deployable spacecraft. As such, an adaptive attitude control algorithm that delivers consistent performance when faced with uncertain time-varying inertia parameters is of significant interest. This dissertation presents a novel adaptive control algorithm that directly compensates for inertia variations that occur as either pure functions of the control input, or as functions of time and/or the state. Another important problem considered in this dissertation pertains to rigid-body attitude stabilization of a spacecraft when only a set of inertial sensor measurements are available for feedback. A novel gyro-free attitude stabilization solution is presented that directly utilizes unit vector measurements obtained from inertial sensors without relying on observers to reconstruct the spacecraft's attitude or angular velocity. As the third major contribution of this dissertation, the problem of attitude tracking control in the absence of angular velocity measurements is investigated through angular velocity observer (estimator) design. A new angular velocity observer is presented which is smoothed and ensures asymptotic convergence of the estimation errors irrespective of the initial true states of the spacecraft. The combined implementation of a separately designed proportional-derivative type controller using estimates generated by the observer results in global asymptotic stability of the overall closed-loop tracking error dynamics. Accordingly, a separation-type property is established for the rigid-body attitude dynamics, the first such result to the author's best knowledge, using a smooth (switching-free) observer formulation. / text

The previous research have found that consumers' choices of vacations may be significantly influenced by mental imagery processing, which is considered to be high elaboration cognitive processing. Mental imagery is defined as an experience that significantly resembles the experience of perceiving some object, event, or scene, but which occurs in the absence of the appropriate stimuli for the relevant object, event, or scene. This study first aims to identify imagery-eliciting Web site features and second, to test their influence on persuasion-related outcomes such as attitude strength, confidence, and attitude resistance. Finally, this study investigates the role of individual processing style (e.g., visualizer or verbalizer) as a moderator variable. A total of 252 subjects participated in a Web-based experiment to examine the influence of selected Web site features on individual imagery processing and its effect on consumers’ attitudes and expectations. It involved a 2 (narrative vs. expository text) × 2 (pictures vs. no picture) × 2 (sounds vs. no sound) full factorial between-subjects design. The data was analyzed primarily using a structural equation modeling methodology. Structural model results revealed that the mental imagery construct strongly influenced the communication effects, which were represented by attitude strength and attitude confidence. In addition, the results of the study found that the communication effects had a significant impact on attitude resistance. This implies that the stronger attitude creates stronger resistance to a negative impact. In the context of the influence of Web site features (e.g., narrative text, pictures, and sound) inducing mental imagery processing, only pictures have a significant effect on mental imagery processing, which support positive effects of concrete pictures on mental imagery processing. In conclusion, the findings of this study show that mental imagery processing is important. Thus, we need to continue to investigate what forms of Web site designs and features best support imagery processing. More specifically, tourism marketers need to understand how certain stimuli influence mental imagery processing, and then they need to enhance Web site designs to capture potential customers.

This study aimed to investigate the influence of the brand-image congruence on consumers¡¦ attitudes toward the sponsor, the advertisement, and the sports website, and it also examined the moderating effect of sports involvement. An experimental design was used to measure the attitudes of 1,063 Internet users. The results of this study showed that higher level of brand-image congruence resulted in more positive attitudes toward the sponsor, the advertisement, and the sports website, whereas the moderating effect of sports involvement was not significant. This study provides brand management implications for both sponsors and sports websites, and suggestions for future research were outlined.

This dissertation investigates attitude transition maneuvers of a gyrosat-satellite between relative equilibria. The primary challenge in transitioning between relative equilibria is the proper adjustment of the system angular momentum so that upon completing the transition maneuver the gyrostat-satellite will satisfy all the requirements for a relative equilibrium. The system angular momentum is a function of the attitude trajectory taken during the transition maneuver. A new concept, the constant orbital momentum equilibrium trajectory or COMET, is introduced as a means to a straight-forward solution to a subset of the possible transitions between relative equilbria. COMETs are a class of paths in SO(3) that a gyrostat-satellite may travel along that maintain a constant system angular momentum. The primary contributions of this dissertation are the introduction and analysis of COMETs and their application to the problem of transitioning a gyrostat-satellite between two relative equilibria. The current work introduces, defines, and analyzes COMETs in detail. The requirements for a path in SO(3) to be a COMET are defined. It is shown via example that COMETs are closed-curves in SO(3). Visualizations of families of COMETs are presented and discussed in detail. A subset of COMETs are shown to contain critical points that represent isolated relative equilibrium attitudes or furcations of the COMET. The problem of transitioning between two relative equilibria is split into the sub-problems of transitioning between relative equilibria on the same COMET and transitioning between relative equilibria on different COMETs. For transitions between relative equilibria on the same COMET, an open-loop control law is developed that drives a gyrostat-satellite along the COMET until the target relative equilibrium is reached. For transitions between relative equilibria on different COMETs, an open-loop control law is developed that transfers a gyrostat-satellite from the initial relative equilibrium to a relative equilibrium that resides on the same COMET as the target relative equilbrium. Acquisition of the target relative equilibrium is then accomplished via the application of the open-loop control law for transitions between relative equilibria on the same COMET. The results of numeric simulations of gyrostat-satellites executing these transitions are presented. / Ph. D.

<p><strong><p>Purpose: The purpose of this thesis is to investigate if and how the presence of Fairtrade promotion can change the attitude towards the stores, ICA and Lidl. <strong></strong></p><p><strong>Background: People‟s attitude towards the brand Fairtrade is predominantly positive and by providing these socially beneficial products, stores wish to strengthen their brand image by communicating their social responsibility through the message of Fairtrade. Previous research has shown that the socially responsible actions of a company can result in an enhanced brand attitude, but also in some cases, the actions taken have had a diminished effect on the attitude towards a brand. It is therefore of interest to research which stores that can gain from Fairtrade promotions in terms of an improved attitude towards the brand. </strong></p><p><strong><strong>Method: To answer the purpose, a mixed method sequential explanatory design was applied, by collecting quantitative data from an experiment, and qualitative data from a follow-up interview. The emphasis was put on the quantitative phase, where four different experimental groups were manipulated with different internet advertisement; ICA and Lidl, with the presence and absence of Fairtrade promotion. </strong></strong></p><p><strong><strong><strong>Conclusion: The outcome of the study signified that the attitude towards Lidl was somewhat negative with the absence of Fairtrade and declined with the presence of Fairtrade promotion while the attitude towards ICA did not change regardless of promotion. The results indicate that Fairtrade can not be successfully used as a system of changing brand attitude of a store, if customers do not consider it to be congruent with the initial brand image. It is supported that consistency is the key to success for a brand to be believable and enhance the brand attitude. </strong></strong></strong></p></strong></p>

Cette thèse s'inscrit dans l'axe des travaux sur l'engagement. Son objectif est d'explorer le paradigme de la communication engageante. Il s'agit d'effectuer un rapprochement entre les théories de la Persuasion et celle de l'Engagement (Joule, Girandola & Bernard, 2007). L'intérêt de cette démarche est d'allier deux champs théoriques traditionnellement disjoints dans le processus lié au changement d'attitude et de comportement. Les théories de la Persuasion ont considérablement contribué à la compréhension des mécanismes du traitement de l'information, mais également à ceux touchant le changement d'attitude. Selon ces théories, il est nécessaire de peser sur les idées pour atteindre les comportements. A l'inverse, l'engagement préconise d'agir à partir du comportement pour atteindre l'activité cognitive. Cette activité entraîne à sa suite un changement d'attitude et ce jusqu'à la production de nouveaux comportements. Notre réflexion peut-être posée en ces termes : dans quelle(s) mesure(s) l'engagement dans un acte suivi de la lecture d'un message persuasif, influe-t-il sur l'aspect cognitif et sur l'intention comportementale des individus ? / This thesis falls within the works on the commitment. Its objective is to investigate paradigm of the binding communication. It is a question of making a link between the theories of the Persuasion and the Commitment (Joule, Girandola & Bernard, 2007).The interest of this approach is to combine two theoretical fields traditionally separated in the process connected to the attitude change and behavior. The theories of the Persuasion considerably contributed to the understanding of the mechanisms to the data processing, but also to those concerning the change of attitude. According to these theories, it is necessary to press on the ideas to reach the behavior. Conversely, the commitment recommends to act from the behavior to reach the cognitive activity. This activity leads behind an attitude change and it until the production of new behavior. Our reflection maybe put in these terms: in what measure the commitment in an act followed by the reading of a persuasive message, does it influence the cognitive aspect and the behavioral intention ?

L’effet de Conditionnement Evaluatif (CE) correspond au changement de valence émotionnelle d’un stimulus initialement neutre (Stimulus Conditionnel, SC), suite à son association avec un stimulus affectif (Stimulus Inconditionnel, SI). Dans cette thèse, nous abordons le sujet du CE avec une approche fonctionnelle en trois axes. Après une présentation générale de l’effet de CE, nous proposons, dans chacun des axes, la description et l’opérationnalisation de nouvelles procédures expérimentales pour chacune des étapes typiques d’une expérience de CE (Apprentissage, Mesure et Modification).Dans l’axe 1, nous proposons une nouvelle procédure d’apprentissage, utilisant des mouvements en tant que stimuli affectifs. L’axe 2 porte sur la mesure de l’effet de CE, nous y présentons la Semi Implicit Task (SIT) destinée à évaluer l’attitude envers un stimulus. Enfin, l’axe 3 s’intéresse à la modification de l’effet de CE, nous présentons des méthodologies destinées à modifier les affects acquis par des stimuli, avec et sans recours à des interventions verbales.Tout au long de ce travail, pour chacune des méthodologies proposées, les implications théoriques et les applications pratiques, particulièrement en psychothérapie, sont discutées. Dans la dernière partie de cette thèse, nous partageons différentes réflexions théoriques relatives à la fonction et la conceptualisation de l’effet de CE, et présentons quelques perspectives de recherches cliniques. / Evaluative Conditioning (EC) is a change in liking of a neutral stimulus (conditioned stimulus, CS) resulting from its association with an emotional stimulus (Unconditioned stimulus, US). In the present thesis we investigate EC using a functional approach. After a general presentation of EC, we focus on both describing and operationalizating new experimental procedures corresponding to each typical phase of an EC experiment: Learning, Measurement and Modification.First, we describe a new learning procedure using motion as USs. Second, we investigate a new measure of EC that we have called the Semi Implicit Task that assess attitude toward CSs. Finally, we investigate the modification of acquired valences with methodologies based on interventions with and without the use of verbal information.Within this general perspective, we discuss both theoretical implications and practical applications of EC. Regarding the second point, we shed light on potential applications in the domain of clinical psychology.

Purpose: The purpose of this thesis is to investigate if and how the presence of Fairtrade promotion can change the attitude towards the stores, ICA and Lidl. Background: People‟s attitude towards the brand Fairtrade is predominantly positive and by providing these socially beneficial products, stores wish to strengthen their brand image by communicating their social responsibility through the message of Fairtrade. Previous research has shown that the socially responsible actions of a company can result in an enhanced brand attitude, but also in some cases, the actions taken have had a diminished effect on the attitude towards a brand. It is therefore of interest to research which stores that can gain from Fairtrade promotions in terms of an improved attitude towards the brand. Method: To answer the purpose, a mixed method sequential explanatory design was applied, by collecting quantitative data from an experiment, and qualitative data from a follow-up interview. The emphasis was put on the quantitative phase, where four different experimental groups were manipulated with different internet advertisement; ICA and Lidl, with the presence and absence of Fairtrade promotion. Conclusion: The outcome of the study signified that the attitude towards Lidl was somewhat negative with the absence of Fairtrade and declined with the presence of Fairtrade promotion while the attitude towards ICA did not change regardless of promotion. The results indicate that Fairtrade can not be successfully used as a system of changing brand attitude of a store, if customers do not consider it to be congruent with the initial brand image. It is supported that consistency is the key to success for a brand to be believable and enhance the brand attitude.

The analysis, verification and emulation of attitude control hardware for nanosatellite spacecraft is described. The overall focus is on hardware that pertains to a multitude of missions currently under development at the University of Toronto Institute for Aerospace Studies - Space Flight Laboratory. The requirements for these missions push the boundaries of what is currently the accepted performance level of attitude control hardware. These new performance envelopes demand new acceptance test methods which must verify the performance of the attitude control hardware. In particular, reaction wheel and hysteresis rod actuators are the focus. Results of acceptance testing are further employed in post spacecraft integration for hardware emulation. This provides for a reduced mission cost as a function of reduced spare hardware. The overall approach provides a method of acceptance testing to new performance envelopes with the benefit of cost reduction with hardware emulation for simulations during post integration.

The analysis, verification and emulation of attitude control hardware for nanosatellite spacecraft is described. The overall focus is on hardware that pertains to a multitude of missions currently under development at the University of Toronto Institute for Aerospace Studies - Space Flight Laboratory. The requirements for these missions push the boundaries of what is currently the accepted performance level of attitude control hardware. These new performance envelopes demand new acceptance test methods which must verify the performance of the attitude control hardware. In particular, reaction wheel and hysteresis rod actuators are the focus. Results of acceptance testing are further employed in post spacecraft integration for hardware emulation. This provides for a reduced mission cost as a function of reduced spare hardware. The overall approach provides a method of acceptance testing to new performance envelopes with the benefit of cost reduction with hardware emulation for simulations during post integration.