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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.
101

Estimation fréquentielle par modèle non entier et approche ensembliste : application à la modélisation de la dynamique du conducteur

Khemane, Firas 05 July 2011 (has links)
Les travaux de cette thèse traite de la modélisation de systèmes par fonctions de transfert non entières à partir de données fréquentielles incertaines et bornées. A cet effet, les définitions d'intégration et de dérivation non entières sont d'abord étendues aux intervalles. Puis des approches ensemblistes sont appliquées pour l'estimation de l'ensemble des coefficients et des ordres de dérivation sous la forme d'intervalles. Ces approches s'appliquent pour l'estimation des paramètres de systèmes linéaires invariants dans le temps (LTI) certains, systèmes LTI incertains et systèmes linéaires à paramètres variant dans le temps (LPV). L'estimation paramétrique par approche ensembliste est particulièrement adaptée à la modélisation de la dynamique du conducteur, car les études sur un, voire plusieurs, individus montrent que les réactions recueillies ne sont jamais identiques mais varient d'une expérience à l'autre, voire d'un individu à l'autre. / This thesis deals with system identification and modeling of fractional transfer functions using bounded and uncertain frequency responses. Therefor, both of fractional differentiation and integration definitions are extended into intervals. Set membership approaches are then applied to estimate coefficients and derivative orders as intervals. These methods are applied to estimate certain Linear Time Invariant systems (LTI), uncertain LTI systems and Linear Parameter Varying systems (LPV). They are notably adopted to model driver's dynamics, since most of studies on one or several individuals shave shown that the collected reactions are not identical and are varying from an experiment to another.
102

Palaeoenvironmental changes in the northern boreal zone of Finland: local versus regional drivers

Shala, Shyhrete January 2014 (has links)
Multiple proxies derived from the Lake Loitsana sediment sequence (NE Finland) are employed to determine the timing of deglaciation, characterise an early Holocene proglacial lake stage and reconstruct Holocene lake development. Local-scale processes causing shifts in biological assemblages are identified and the most likely Holocene mean July air temperature (Tjul) development is assessed. The study area was deglaciated shortly prior to 10 700 cal. a BP. The sediment record reflects four local events; the presence of a glacial lake, glacial lake drainage and formation of Lake Loitsana, changes in fluvial input due to progressive wetland expansion, and gradual lake infilling. The results suggest that local events have driven changes in biological assemblages through various processes, and that biotic proxies reflect changes in environmental parameters in a highly individual manner. Furthermore, biological assemblages can themselves act as important drivers, influencing the composition of other assemblages. It is suggested that future studies should consider macrophyte abundance and food-web interactions as equally important factors when assessing changes in biological assemblages. Quantitative Tjul reconstructions based on biotic proxies display contrasting trends. While Tjul reconstructions based on pollen found in the Loitsana sequence display relatively low early Holocene values, plant macrofossil and chironomid data reflect warm summer conditions also during the early Holocene, i.e. at the peak of summer insolation. The early Holocene Tjul recorded by terrestrial pollen are affected by local factors possibly combined with a delayed response of the terrestrial ecosystem compared to the aquatic one. This study emphasises the importance of using multiple proxies in palaeoenvironmental studies and shows that local factors have a potential to drive changes in biological assemblages that can affect transfer-function based temperature reconstructions. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Epub ahead of print. Paper 2: Accepted. Paper 3: Manuscript.</p>
103

Podpora ladění ve knihovně WALA pro statickou analýzu / Debugging Support for Static Analysis Library WALA

Havel, Filip January 2021 (has links)
Nowadays, static analysis is a helpful option for developers to ensure all the important properties of a developed application. But these analyses must be also developed and it is inevitable that sometimes they must be debugged to find and solve problems inside of the analyses themself. The debugging of static analyses might be more complicated because some popular analysis frameworks do not provide sufficient support for debugging. One of the widely used analysis frameworks is WALA. In this thesis, we thoroughly explored all the main features of WALA and determined possible points for better debugging support. For each of these points, we designed and implemented supporting infrastructure that should accelerate the process of debugging by avoiding the tedious manual effort needed for inspection and evaluation of the internal state of WALA. One kind of these points is the analysis configuration where we created an inspection system for class hierarchy and call graph that should detect common misconfiguration problems. The next point is the debugging of the data flow transfer functions, for which we created a visualizer of the running analysis over the subject program. This visualization is done within the Visual Studio Code editor. To connect the editor with the analysis we used Debug Adapter Protocol and...
104

True-Average Current-Mode Control of DC-DC Power Converters: Analysis, Design, andCharacterization

Saini, Dalvir K. 02 August 2018 (has links)
No description available.
105

Touching the Essence of Life : Haptic Virtual Proteins for Learning

Bivall, Petter January 2010 (has links)
This dissertation presents research in the development and use of a multi-modal visual and haptic virtual model in higher education. The model, named Chemical Force Feedback (CFF), represents molecular recognition through the example of protein-ligand docking, and enables students to simultaneously see and feel representations of the protein and ligand molecules and their force interactions. The research efforts have been divided between educational research aspects and development of haptic feedback techniques. The CFF model was evaluated in situ through multiple data-collections in a university course on molecular interactions. To isolate possible influences of haptics on learning, half of the students ran CFF with haptics, and the others used the equipment with force feedback disabled. Pre- and post-tests showed a significant learning gain for all students. A particular influence of haptics was found on students reasoning, discovered through an open-ended written probe where students' responses contained elaborate descriptions of the molecular recognition process. Students' interactions with the system were analyzed using customized information visualization tools. Analysis revealed differences between the groups, for example, in their use of visual representations on offer, and in how they moved the ligand molecule. Differences in representational and interactive behaviours showed relationships with aspects of the learning outcomes. The CFF model was improved in an iterative evaluation and development process. A focus was placed on force model design, where one significant challenge was in conveying information from data with large force differences, ranging from very weak interactions to extreme forces generated when atoms collide. Therefore, a History Dependent Transfer Function (HDTF) was designed which adapts the translation of forces derived from the data to output forces according to the properties of the recently derived forces. Evaluation revealed that the HDTF improves the ability to haptically detect features in volumetric data with large force ranges. To further enable force models with high fidelity, an investigation was conducted to determine the perceptual Just Noticeable Difference (JND) in force for detection of interfaces between features in volumetric data. Results showed that JNDs vary depending on the magnitude of the forces in the volume and depending on where in the workspace the data is presented.
106

The frequency response, impulse response, and transfer function of an ocean waveguide

Schulte, Walter B., III 06 1900 (has links)
Approved for public release, distribution is unlimited / In this thesis, the ocean was modeled as a waveguide with an ideal pressure - release surface, and an ideal rigid bottom. The ocean waveguide was then treated as a linear, time - invariant, space - variant (TISV) filter or communication channel. The filter is time - invariant because no motion was modeled and because the properties of the ocean were assumed to be constant. The filter is space - variant because of the presence of the two boundaries, that is, the ocean surface and ocean bottom. This thesis investigates the ocean as a linear TISV filter by evaluating 1) the complex frequency response, 2) the impulse response, and 3) the transfer function of the ocean with respect to depth. It is shown that the TISV impulse response of the ocean contains information that can be used to help localize a target in range and whether the target is above or below the receiver. Computer simulation results were obtained by evaluating the three filter functions for several different test cases. / Ensign, United States Navy
107

Adaptivna estimacija parametara sistema opisanih iracionalnim funkcijama prenosa / Adaptive Parameter Estimation in Systems described by Irrational TransferFunctions

Kapetina Mirna 22 November 2017 (has links)
<p>Predmet istraživanja je identifikaciji i adaptivna estimacija<br />parametara široke klase linearnih sistema. Predloženi algoritmi<br />za adaptivnu estimaciju parametara su primenjivi na sisteme koji se<br />opisuju funkcijama prenosa proizvoljnog oblika, što uključuje sisteme<br />sa kašnjenjem, distribuiranim parametrima, frakcione sisteme i<br />druge sisteme opisane iracionalnim funkcijama prenosa. Na<br />posletku, dat je algoritam za identifikaciju CNG sistema koji se ne<br />izvršava u realnom vremenu i pretpostavlja da struktura modela nije<br />poznata unapred.</p> / <p>The subject of this research is the system identification and adaptive<br />parameter estimation in wide class of linear processes. Proposed<br />approaches for adaptive parameter estimation can be applied to systems<br />described by transfer functions of arbitrary form, including systems with<br />delay, distributed-paratemeter systems, fractional order systems, and other<br />system described by irrational transfer functions. In the final part, an offline<br />algorithm for identification of CNG system which does not assume any a<br />priori known model structure is proposed.</p>
108

Magnetotellurics and Geomagnetic Depth Sounding in Queensland, South Eastern Australia -Evidence for the Tasman Line? / Magnetotellurik und Geomagnetische Tiefensondierung in Queensland, Süd Ost-Australien -Nachweis für die Tasmanische Linie ?

Fon, Lawrence Teku 30 September 2011 (has links)
No description available.
109

Necessary and Sufficient Conditions on State Transformations That Preserve the Causal Structure of LTI Dynamical Networks

Leung, Chi Ho 01 May 2019 (has links)
Linear time-invariant (LTI) dynamic networks are described by their dynamical structure function, and generally, they have many possible state space realizations. This work characterizes the necessary and sufficient conditions on a state transformation that preserves the dynamical structure function, thereby generating the entire set of realizations of a given order for a specific dynamic network.
110

Necessary and Sufficient Conditions on State Transformations That Preserve the Causal Structure of LTI Dynamical Networks

Leung, Chi Ho 01 May 2019 (has links)
Linear time-invariant (LTI) dynamic networks are described by their dynamical structure function, and generally, they have many possible state space realizations. This work characterizes the necessary and sufficient conditions on a state transformation that preserves the dynamical structure function, thereby generating the entire set of realizations of a given order for a specific dynamic network.

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