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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.
251

Blind Received Signal Strength Difference Based Source Localization with System Parameter Error and Sensor Position Uncertainty

Lohrasbipeydeh, Hannan 27 August 2014 (has links)
Passive source localization in wireless sensor networks (WSNs) is an important field of research with numerous applications in signal processing and wireless communications. One purpose of a WSN is to determine the position of a signal emitted from a source. This position is estimated based on received noisy measurements from sensors (anchor nodes) that are distributed over a geographical area. In most cases, the sensor positions are assumed to be known exactly, which is not always reasonable. Even if the sensor positions are measured initially, they can change over time. Due to the sensitivity of source location estimation accuracy with respect to the a priori sensor position information, the source location estimates obtained can vary significantly regardless of the localization method used. Therefore, the sensor position uncertainty should be considered to obtain accurate estimates. Among the many localization approaches, signal strength based methods have the advantages of low cost and simple implementation. The received signal energy mainly depends on the transmitted power and path loss exponent which are often unknown in practical scenarios. In this dissertation, three received signal strength difference (RSSD) based methods are presented to localize a source with unknown transmit power. A nonlinear RSSD-based model is formulated for systems perturbed by noise. First, an effective low complexity constrained weighted least squares (CWLS) technique in the presence of sensor uncertainty is derived to obtain a least squares initial estimate (LSIE) of the source location. Then, this estimate is improved using a computationally efficient Newton method. The Cramer-Rao lower bound (CRLB) is derived to determine the effect of sensor location uncertainties on the source location estimate. Results are presented which show that the proposed method achieves the CRLB when the signal to noise ratio (SNR) is sufficiently high. Least squares (LS) based methods are typically used to obtain the location estimate that minimizes the data vector error instead of directly minimizing the unknown parameter estimation error. This can result in poor performance, particularly in noisy environments, due to bias and variance in the location estimate. Thus, an efficient two stage estimator is proposed here. First, a minimax optimization problem is developed to minimize the mean square error (MSE) of the proposed RSSD-based model. Then semidefinite relaxation is employed to transform this nonconvex and nonlinear problem into a convex optimization problem. This can be solved e ciently to obtain the optimal solution of the corresponding semidefinite programming (SDP) problem. Performance results are presented which con rm the e ciency of the proposed method which achieves the CRLB. Finally, an extended total least squares (ETLS) method is developed for blind localization which considers perturbations in the system parameters as well as the constraints imposed by the relation between the observation matrix and data vector. The corresponding nonlinear and nonconvex RSSD-based localization problem is then transformed to an ETLS problem with fewer constraints. This is transformed to a convex semidefinite programming (SDP) problem using relaxation. The proposed ETLS-SDP method is extended to the case with an unknown path loss exponent. The mean squared error (MSE) and corresponding CRLB are derived as performance benchmarks. Performance results are presented which show that the RSSD-based ETLS-SDP method attains the CRLB for a sufficiently large SNR. / Graduate / 0544 / lohrasbi@uvic.ca
252

Identification de la zone regardée sur un écran d'ordinateur à partir du flou

Néron, Eric January 2017 (has links)
Quand vient le temps de comprendre le comportement d’une personne, le regard est une source d’information importante. L’analyse des comportements des consommateurs, des criminels, ou encore de certains états cognitifs passe par l’interprétation du regard dans une scène à travers le temps. Il existe un besoin réel d’identification de la zone regardée sur un écran ou tout autre médium par un utilisateur. Pour cela, la vision humaine fait la composition de plusieurs images pour permettre de comprendre la relation tridimensionnelle qui existe entre les objets et la scène. La perception 3D d’une scène réelle passe alors à travers plusieurs images. Mais qu’en est-il lorsqu’il n’y a qu’une seule image ?
253

Adaptive Fault-Tolerant Teleoperation

Dede, Mehmet Ismet Can 14 November 2007 (has links)
While the robots gradually become a part of our daily lives, they already play vital roles in many critical operations. Some of these critical tasks include surgeries, battlefield operations, and tasks that take place in hazardous environments or distant locations such as space missions. In most of these tasks, remotely controlled robots are used instead of autonomous robots. This special area of robotics is called teleoperation. Teleoperation systems must be reliable when used in critical tasks; hence, all of the subsystems must be dependable even under a subsystem or communication line failure. These systems are categorized as unilateral or bilateral teleoperation. A special type of bilateral teleoperation is described as force-reflecting teleoperation, which is further investigated as limited- and unlimited-workspace teleoperation. Teleoperation systems configured in this study are tested both in numerical simulations and experiments. A new method, Virtual Rapid Robot Prototyping, is introduced to create system models rapidly and accurately. This method is then extended to configure experimental setups with actual master systems working with system models of the slave robots accompanied with virtual reality screens as well as the actual slaves. Fault-tolerant design and modeling of the master and slave systems are also addressed at different levels to prevent subsystem failure. Teleoperation controllers are designed to compensate for instabilities due to communication time delays. Modifications to the existing controllers are proposed to configure a controller that is reliable in communication line failures. Position/force controllers are also introduced for master and/or slave robots. Later, controller architecture changes are discussed in order to make these controllers dependable even in systems experiencing communication problems. The customary and proposed controllers for teleoperation systems are tested in numerical simulations on single- and multi-DOF teleoperation systems. Experimental studies are then conducted on seven different systems that included limited- and unlimited-workspace teleoperation to verify and improve simulation studies. Experiments of the proposed controllers were successful relative to the customary controllers. Overall, by employing the fault-tolerance features and the proposed controllers, a more reliable teleoperation system is possible to design and configure which allows these systems to be used in a wider range of critical missions.
254

Analýza průběhu profesní kariéry absolventů VŠE / Analysis of career of University of Economics graduates

Majerníková, Lenka January 2008 (has links)
My thesis's aim was to describe start up and career development of graduates with so-called career maps, the most frequent work positions, rate of managerial posts, comparison in age and gender in various relations, the most frequent fields of companies, in which graduates work, frequency of different kinds of companies or ways of finding a first job. I was striving to introduce and analyse all of this in a global concept for the whole school and I was not comparing those aspect within school faculties. In the conclusion I added short analysis of gradues of minor specialization Managerial Psychology and Sociology.
255

Ekonomické postavení Vietnamu v regionu a ve světě / The economic position of Vietnam within the region and the world

Hoang, Phuong Anh January 2012 (has links)
The master thesis is about the economic position of Vietnam within the region and the world. The first chapter begins with the economic development of Vietnam since the mid-1980, focusing on the reform process, which began in 1986. It outlines the facts that preceded the reform process, its basic features, and resulting effects of the transformation. Emphasis is also placed on the evaluation of the position of Vietnamese economy in 21st century. The second chapter offers basic economic characteristics of the country. Some of the macroeconomic indicators (GDP, inflation, unemployment, and selected items of Balance of payments) are analyzed with regard to the global economic development. The third chapter is about the participation of Vietnam in international economic relations. It describes country's participation in international organizations and regional blocs. Foreign trade will be discussed on the basis of trade in goods and trade in services. And finally, foreign direct investments are also analyzed as they are a major source of economic growth in the country. The fourth chapter presents foreign trade relations of Vietnam with selected players of the world economy: the European Union, the United States, the Czech Republic and ASEAN countries.
256

Technological changes and business network dynamics : a longitudinal perspective from the optical recording media industry

Chou, Hsin-Hui January 2010 (has links)
In the past thirty years, the IMP Group's Interaction and Network Approach has gained its increasing popularity in researching economic behaviours among resource-dependent business actors through relational linkages (Håkansson et al., 2004; Turnbull et al., 1996). Within network research, understanding the dynamics in business networks, in which interfirm relationships are regarded as crucial constituents, has been of particular interest (Johnston et al., 2006; Möller and Halinen, 1999). Moreover, technology has been identified as an important component driving the evolution of a business network, where technological change may bring about positive and negative effects on the relationships embedded in this network, and consequently, results in network dynamics (Afuah, 2000; Christensen, 1997; Håkansson and Waluszewski, 2002b; Lundgren, 1995). A perspective of resource interaction (e.g. Håkansson et al., 2009) suggests that technological change needs to be treated as a process rather than a critical event. However the nature of this process as well as how it impacts on the configuration of a technology-based business net and on dynamics of relationships constituting this net remains under-examined.Based on qualitative research methods, a longitudinal single-case study is chosen to conduct an empirical investigation in the optical recording media industry, in order to address the above research problems. To facilitate the data collection, a focal net perspective and an input-process-output model are employed. The focal net under study is characterised as a value-creating and technology-bundled business net. A total of 72 interviews were carried out in three stages and with the focal actor, its customers, suppliers and a complementor. The empirical data allows the research to reconstruct the evolution of the focal business net, which covers a time-span of more than 10 years from 1998 to 2008, and in which major technological change has taken place three times, from CD-R to DVD-/+R, DVD Double Layer and HD/Blu-ray technologies. In the development of the optical recording technology, the focal net has experienced four net reconfigurations in which radical changes of relationships as well as disturbance in resource interaction are observed. Based on the case study result, empirical observations are offered and new insights into the process of the arrival of technological change and net reconfiguration and relationship dynamics affected by this technological arrival are developed. Moreover, theoretical contribution, managerial implications, limitations and future research directions are provided.
257

The epistemological paradox of translating autobiography : evidential stance in translated vs. non-translated autobiographies in English and Japanese

Marshall, Sally Victoria January 2013 (has links)
Much has been written on the position of the translator; the concept of ‘position’ being understood variously in terms of spatial, ideological, sociological, philosophical, or narratological orientation. The present research project contributes to this body of work through the empirical investigation of translator position as an epistemological function, examining patterns of evidential stance-taking in original vs. translated autobiographies. A defining characteristic of autobiographical writings is a NARRATOR=EXPERIENCER relationship: the narrator has privileged access to the memory from which the narrative is sourced. However, when an autobiography is translated, the connection between the narrator and the source of the narrative – the memory of the experiencer – is interrupted. The translation of an autobiography, then, presents an epistemological paradox: the translator’s first person discursive position is at odds with the evidential basis from which he or she narrates. This research aims to investigate the extent to which the translator’s occupation of the position of an autobiographical ‘I’ is purely nominal or extends to the experiential, asking whether the textual production of a translation reveals distance between the narrator and the autobiographical experiences being narrated – a NARRATOR≠EXPERIENCER relationship – or reveals empathetic identification between the narrator and the author, projecting a NARRATOR=EXPERIENCER relationship. Based on an assumed contrast between the phenomenological and narrative character of memories acquired by first-hand experience vs. memories based on other sources, a framework is developed for the analysis of evidential stance-taking in the narration of autobiographical memories. Focusing on the narration of acts of recollection and descriptions of how recalled experiences ‘seemed’ to the experiencer, patterns of complement choice (e.g. remember –ing vs. remember that) are differentiated on the basis of their construal of memories as being either ‘experiential’ or ‘non-experiential’ in character. Applying the framework to a purpose-built, bi-directional comparable corpus of translated vs. non-translated autobiographies in English and Japanese, the study reveals a tendency towards a less frequent construal of memories from an ‘experiential’ stance, and more frequent construal of memories from an ‘non-experiential’ stance in translated texts in both English and Japanese. However, variation in stance-taking exhibited between the individual texts comprising respective sub-corpora is also in evidence. The findings are interpreted as a manifestation of the NARRATOR≠EXPERIENCER relationship characteristic of translated texts in general, but also as a possible indicator of the influence of variable degrees of translator-author identification on individual translators’ negotiation of position.
258

Poděbrady na trhu lázeňských služeb v České republice / Position of the spa town Poděbrady on the Czech spa market

Šimůnková, Monika January 2012 (has links)
The thesis analyzes and evaluates the position of the spa town Poděbrady, respectively, the largest local spa company Lázně Poděbrady, a.s., on the Czech spa market. The thesis is divided into five chapters. The theoretical part makes an introduction into balneology (basic notions, relationship between balneology and tourism, spa product, management and marketing, the economic benefits of the spa). The next section provides basic information about Poděbrady, development of providing spa services in this town and about the local natural healing resource. In the following chapter, there is an analysis and comparison of spa subjects providing spa services in Poděbrady. The fourth chapter analyzes the position of the spa company Lázně Poděbrady, a.s., on the Czech spa market. Based on the analysis and comparisons, an evaluation of the position of the company on the Czech spa market is made in the final part.
259

Effect of lateral costal breathing dissociation exercises on the position of the scapula in level two up to senior national level swimmers

Korkie, Elzette January 2015 (has links)
Swimmers depend on accessory breathing muscles for adequate ventilation. Pectoralis minor is an accessory breathing muscle. The daily repetition of gleno-humeral flexion and medial rotation results in adaptive shortening of Pectoralis, a common phenomenon in competitive swimmers. If Pectoralis minor is shortened the scapula is in an anteriorly tipped position. This anteriorly tipped position will affect scapula kinematics as well as the strength of Pectoralis minor to function as an accessory breathing muscle. One of the risk factors contributing to shoulder dysfunction in competitive swimmers is an altered scapular position. The study aimed to determine if lateral costal breathing dissociation exercises in conjunction with scapular retraining exercises had an effect on the position of the scapula in competitive swimmers. A comparative parallel group longitudinal design was used in this study. During a six week supervised intervention period the intervention group (n=28) and control group (n=30) did retraining of the scapula stabilisers and stretching of Pectoralis minor. The intervention group did breathing dissociation exercises to facilitate lateral costal breathing. No specific breathing exercises were facilitated within the control group. Pectoralis minor length and thoracic expansion had been measured. The function of the scapula stabilisers was evaluated. The resting as well as dynamic scapula positions were evaluated. Evaluations were done at baseline, six weeks and five months post intervention. Treatment groups were compared with respect to change from baseline to six weeks and baseline to five months in PMI, FVC and thoracic expansion utilizing analysis of covariance (ANCOVA) with covariates baseline reading. The intervention group showed an increase in the Pectoralis minor Index (PMI) of 0.5 (left & right) and the control group reflected an increase of 0.5 (left) and 0.7 (right). The intervention group reflected continuous improvement in PMI and the control group showed deterioration. In addition to the PMI upper thoracic, expansion decreased and lower thoracic expansion increased in the intervention group. The control group showed a decrease in upper and lower thoracic expansion. Groups were compared with respect to change from baseline to six weeks and five months respectively for categorical parameters, muscle function and scapula position (resting and dynamic) using Fisher’s exact test. After six weeks the intervention group showed significantly (p<0.04) less winging of the distal third of the scapula on the left side when compared to the control group. After five months the scapula showed significantly less tipping (p<0.02) during gleno-humeral flexion, on the left side. The McNemar test for symmetry had been applied to determine if any within group changes occurred. Within the intervention group ten of the thirteen markers used to determine the resting position of the scapula, reflected significant improvement compared to the six markers in the control group. Only the intervention group reflected remarkable improvement in function of the lower fibres of Trapezius muscle. Serratus anterior and middle fibres of Trapezius muscles showed significance within group improvement in function for both groups. The scapula showed significantly less dysrhythmia within the intervention group on the left and right sides (p< 0.0209) when compared to the control group. After five months the resting scapula position reflected deterioration for both groups. Dysrhythmia and winging of the scapula deteriorated from six weeks to five months for both groups. The muscle function of the lower fibres of Trapezius showed significance within group changes for both groups from six weeks to five months. The ability to contract Serratus anterior and the middle fibres of Trapezius agonistically was maintained from six weeks to five months. However the eccentric control and ability to contract the muscle without fatigue within the Serratus anterior and middle fibres of Trapezius showed deterioration from six weeks to five months for both groups. Conclusion: The increase in PMI and increase in lower thoracic expansion for the intervention group could favour swimmers to breathe more effectively. An increase in Pectoralis minor length resulted in a more posteriorly tipped scapula. This better positioned scapula promotes optimum function of the lower fibres of Trapezius. Contracting from a stable scapula, Pectoralis minor can fulfil its function as an accessory breathing muscle more effectively. / Thesis (PhD)--University of Pretoria, 2015. / tm2015 / Physiotherapy / PhD / Unrestricted
260

Thin position, bridge structure, and monotonic simplification of knots

Zupan, Alexander Martin 01 July 2012 (has links)
Since its inception, the notion of thin position has played an important role in low-dimensional topology. Thin position for knots in the 3-sphere was first introduced by David Gabai in order to prove the Property R Conjecture. In addition, this theory factored into Cameron Gordon and John Luecke's proof of the knot complement problem and revolutionized the study of Heegaard splittings upon its adaptation by Martin Scharlemann and Abigail Thompson. Let h be a Morse function from the 3-sphere to the real numbers with two critical points. Loosely, thin position of a knot K in the 3-sphere is a particular embedding of K which minimizes the total number of intersections with a maximal collection of regular level sets, where this number of intersections is called the width of the knot. Although not immediately obvious, it has been demonstrated that there is a close relationship between a thin position of a knot K and essential meridional planar surfaces in its exterior E(K). In this thesis, we study the nature of thin position under knot companionship; namely, for several families of knots we establish a lower bound for the width of a satellite knot based on the width of its companion and the wrapping or winding number of its pattern. For one such class of knots, cable knots, in addition to finding thin position for these knots, we establish a criterion under which non-minimal bridge positions of cable knots are stabilized. Finally, we exhibit an embedding of the unknot whose width must be increased before it can be simplified to thin position.

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