9,604 Works

Hydrogen bonds of nucleic acids and local motions of proteins studied by nuclear spin relaxation

Dimitri Bytchenkoff
In my thesis I shall focus on the development of new NMR experimental methods to study structure and internal motions of two kinds of biological polymers, viz. proteins and nucleic acids. I shall investigate the anisotropic local motions of peptide planes and locate amide protons in proteins by measuring three dipole-dipole cross-correlated relaxation rate constants of single-quantum coherences involving the peptide backbone nuclei. I shall also estimate the internucleotide hydrogen bond lengths in nucleic acids...

Image/video representation and scalable coding using redundant dictionaries

Adel Rahmoune
Compact or efficient representation for either images or image sequences is key operation to performing image and video processing tasks, such as compression, analysis, etc. The efficiency of an approximation is evaluated by the sparsity measure of the approximation, i.e., the sparsest the representation is, the more efficient it is. For image processing tasks, it is often desired to decompose the image into a linear combination of few visual primitives or features selected from a...

Infrared photofragment spectroscopy of charged amino acid water clusters in the gas phase

Anthi Kamariotou
We present in this work a new technique, which combines laser photofragmentation spectroscopy with tandem mass spectrometry, for structural investigations of biomolecular ions in the gas phase. A novel apparatus was designed and built for the implementation of these studies. In this instrument closed shell ions are produced in the gas phase by electrospray ionization and stored in a hexapole ion trap prior to mass selection of a parent beam in a first quadrupole and...

Gas-sensing properties of V2O5-nanofibers and carbon nanotubes

Ulrich Schlecht
In this thesis, the synthesis and characterization of V2O5-nanostructures, as well as the gas sensing properties of V2O5-nanofibers and carbon nanotubes have been investigated. Various modifications of the nanowires have been successfully employed in order to achieve an improved sensitivity and selectivity of the sensors to specific analytes. The V2O5-nanofibers have been synthesized via solution-based chemistry. Two modifications of the standard synthesis route have been attempted in order to reduce the time required to grow...

Ecological response of a multi-purpose river development project using macro-invertebrates richness and fish habitat value

Marc Pellaud
It has been acknowledged that river morphology and hydrology have been intensively altered due to the anthropic demands in floodplain land use and management, flood protection, promotion of navigability or energy production. Rivers were transformed in water highways, having lost contact with their surrounding floodplain as well as the plethora of ecological processes and occupants once thriving in these ecotonal zones. The identification of this emerging threat of morphological and hydrological alteration on ecological integrity...

Spatio-temporal coupling of the electric and hemodynamic brain responses in humans

Roberto Martuzzi
Our comprehension of human brain functions and their dynamics has been dramatically improved by recent developments in non-invasive imaging techniques. These methods can be divided into two different categories, according to the nature of the measured signal: hemodynamic techniques, such as functional magnetic resonance imaging (fMRI) and positiron emission tomography (PET), and electromagnetic techniques, such as electroencephalography (EEG) and magnetoencephalography (MEG). These two categories are have complementary characteristics: hemodynamic techniques have a good spatial resolution...

Solar disinfection of water by photocatalytic processes:physico-chemical and biological aspects

Angela-Guiovana Rincón Benavides
Chlorine, widely used as a disinfectant for drinking water production, is known to interact with organic matter to yield disinfection by-products (DBPs). Some of these compounds, as the trihalomethanes, are highly toxic for human health. Alternative disinfection methods are thus currently being developed, especially in industrialized and wealthy countries. Methods such as ozone and ultraviolet light are equally effective and less toxic. However, these techniques are expensive and often technically difficult to apply in less...

Asymptotic properties of wireless multi-hop networks

Olivier Dousse
In this dissertation, we consider wireless multi-hop networks, where the nodes are randomly placed. We are particularly interested in their asymptotic properties when the number of nodes tends to infinity. We use percolation theory as our main tool of analysis. As a first model, we assume that nodes have a fixed connectivity range, and can establish wireless links to all nodes within this range, but no other (Boolean model). We compute for one-dimensional networks the...

Modélisation et prédiction du comportement rhéologique des mélanges bitume caoutchouc

Mehdi Ould Henia
Asphalt rubber is a modified binder widely used in pavement construction. Composition design methods of asphalt rubber blends are exclusively empiric and rely on the selection of the optimal combination of parameters after a long experimental program. The understanding of the phenomena affecting the asphalt rubber behaviour starts with the proposal of a rational theory and its validation with experimental data. To do so, a set of experiments were carried out including three main factors...

Asymptotic and finite-length analysis of low-density parity-check codes

Changyan Di
This thesis addresses the topic of Low-Density Parity-Check (LDPC) code analysis, both asymptotically and for finite block lengths. Since in general it is a difficult problem to analyze individual code instances, ensemble averages are studied by following Gallager's original idea and results of Luby et al. Often, one can relate the insights gained by studying ensemble averages to statements regarding individual codes by proving that most elements in the ensemble behave "close" to the average....

Design and control of quadrotors with application to autonomous flying

Samir Bouabdallah
This thesis is about modelling, design and control of Miniature Flying Robots (MFR) with a focus on Vertical Take-Off and Landing (VTOL) systems and specifically, micro quadrotors. It introduces a mathematical model for simulation and control of such systems. It then describes a design methodology for a miniature rotorcraft. The methodology is subsequently applied to design an autonomous quadrotor named OS4. Based on the mathematical model, linear and nonlinear control techniques are used to design...

Delay and coding in multiple-user communications

Stéphane Musy
In multiple-user communications, the bursty nature of the packet arrival times cannot be divorced from the analysis of the transmission process. However, in traditional information theory the random arrival times are smoothed out by appropriated source coding and no consideration is made for the end-to-end delay. In this thesis, using tools from network theory, we investigate simple models that consider the end-to-end delay and/or the variability of the packet arrivals as important parameters, while staying...

The relationship between the irradiation induced damage and the mechanical properties of single crystal Ni

Zhongwen Yao
Irradiation is known to lead to a degradation of the mechanical properties of materials. This is particularly crucial in the case of materials that will be used in the future thermonuclear fusion reactor, where extremely high irradiation doses are expected. In the quest of a better understanding between the irradiation induced defects and the mechanical properties Ni single crystal specimens have been irradiated with 590 MeV protons to doses ranging from 10-3 dpa to 0.3...

Développement d'un module de détection phoswich LSO/LuYAP pour le prototype de caméra à positrons ClearPET

Jean-Baptiste Mosset
The first part of this thesis describes the development of an optimised LSO/LuYAP phoswich detector head for the ClearPET demonstrator positron emission tomograph (PET) dedicated to small animals that is under construction in Lausanne within the Crystal Clear Collaboration. The detector head consists of a dual layer of 8 x 8 LSO and LuYAP crystal arrays coupled to a multi-anode photomultiplier tube (MaPMT). Equalistion of the LSO/LuYAP light collection is obtained through partial attenuation of...

Study of cementitious materials using transmission electron microscopy

Prakash Chandra Mathur
An important mode of hydration of Ordinary Portland cement (OPC) is via the formation of a shell of hydration products around cement grains. It has been shown so far that shells form not only in OPC but also around C3A grains in a mixture of alite, C3A and CS and in more restricted form in pure alite. The shells are believed to be hollow and limited information of the chemistry of the phases that constitute...

Mécanismes d'action du TiO2 illuminé sur Escherichia Coli

Gaëtan Gogniat
The increase of bacterial resistance against various disinfection processes is a worrying phenomenon. As a consequence, the search for alternative techniques for fighting micro-organisms has become one of the major issues of these last few years. In this domain, water treatment is an important preoccupation for many states, either to guarantee the quality of drinking water supply or to detoxify industrial effluents, charged with chemically or biologically pollutants. The financing of this thesis project was...

Surface parameterization and optimum design methodology for hydraulic turbines

Lluis Ferrando López
This thesis presents a methodology for the design optimization of hydraulic runner blades. The originality of the methodology comes from the geometric definition of the blade shapes, which uses parametric surfaces instead of a set of profiles. The main advantage of using surfaces is the number of parameters required. The use of surfaces requires a different technique for the blade construction when compared to traditional approaches. NURBS surfaces are used for the geometric representation, the...

Managing competing technology standards in the digital economy

Arnaud Varé
Over the last decades, battles for technological dominance between competing and incompatible technologies have had a significant impact on competition within many high-tech industries. In this dissertation, we are concerned with the management of such standards wars. We recognize that many changes have occurred in the technology environment since the beginning of the digital economy (and especially the commercialization of the Internet). We acknowledge, in particular, that an alleged winner of a standards war can...

Reactivity and fluxionality of late transition metal cluster compounds

Zoltán Béni
The first part of this work deals with oxidative addition reactions of the triangulo platinum cluster [Pt3(μ-CO)3(PCy3)3]. Reactions with the electrophilic molecules ICH2CN and X2 (X = I and Br) and with the weakly polar reagent Ph3SnH have been studied. All three reactants convert the starting cluster firstly to novel 44-electron clusters probably via a SN2 mechanism. In the case of ICH2CN the adduct [Pt3(μ-CO)3(PCy3)3(I)(CH2CN)] is the first example where a Pt(II)L3 moiety is bonded...

A flexible framework for efficient design of advanced 3D audio systems in multimedia applications

Aleksandar Simeonov
The recent advance of computer technology pushed the computing power of the modern computer systems to unprecedented levels; modern processors moved from the conventional, scalar type of architecture to more sophisticated, parallel ones, combining fast processing speed clock with multiple processing units. This jump of the computing power made possible the real-time implementations of many 3D audio algorithms that was hard to imagine 10-15 years before; on the other hand, the permanent increase of customer...

Solid oxide fuel cell stack simulation and optimization, including experimental validation and transient behavior

Diego Larrain
This thesis presents the development of models for the simulation and optimization of the design of a planar solid oxide fuel cell (SOFC) stack. Fuel cells produce electric power directly from a fuel by electrochemical reactions. The high efficiencies demonstrated make them a promising technology for energy conversion. The main challenges lie with reliability and cost reduction. Some applications demand at the same time strong requirements on the compactness of the system and its ability...

Adaptive media streaming over multipath networks

Dan Jurca
With the latest developments in video coding technology and fast deployment of end-user broadband internet connections, real-time media applications become increasingly interesting for both private users and businesses. However, the internet remains a best-effort service network unable to guarantee the stringent requirements of the media application, in terms of high, constant bandwidth, low packet loss rate and transmission delay. Therefore, efficient adaptation mechanisms must be derived in order to bridge the application requirements with the...

Wastewaters:occurrence of pharmaceutical substances and genotoxicity

Annick Tauxe Würsch
The major pathways of human pharmaceuticals into the environment are from their use by individuals either at home or under medical supervision in hospitals, and to a lesser extent by the disposal of unwanted or out of date drugs. The administered pharmaceuticals will be excreted as the parent compound, metabolite or conjugate and will be transported to sewage treatment works. In sewage treatment, the compound may be degraded or partially degraded, adsorbed to sludge if...

Application of Adaptive Optics to Focusing and Imaging

Daniel Iwaniuk
Adaptive optics is used to abate aberrations with a wavefront correction. It is widely used in astronomy and is starting to expand into applications of laser focusing and imaging with high numerical apertures, e.g. microscopy. The physical background of focusing laser light and imaging is the same, so we can use the same methods. In both cases, light is propagating through a lens; either it becomes focused into a small region or light from a...

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