4,937 Works

Fluid Manipulation Using Thermoexpandable Polymer Based on Ploydimethylsiloxane and Expancel

Lynda Metref
Nowadays, manipulation of liquids in miniaturised environments finds applications in many fields in biology and medicine such as diagnostics, toxicity analysis, drug delivery and so on. In those domains, the use of disposable devices has the great advantage of removing any surface contamination which could results in device malfunction. In this context, the present work revolves around the use of a thermoexpandable material, composed of expandable beads in an elastomeric matrix, used as actuator for...

Dynamics of multi-photon processes in semiconductor heterostructures

Daniel Marti
The present work is devoted to the study of the dynamics of multi-photon processes in semiconductor heterostructures. A time-dependent description is important for understanding in detail the transient response of semiconductors excited by ultrashort optical pulses. In the first part of this thesis, we set up a phenomenological model based on rate equations, in order to investigate the possibility of measuring degenerate two-photon gain in a semiconductor microcavity. The amplification predicted by the model is...

Hydrodynamics of High Specific Power Pumps for Off-Design Operating Conditions

Stefan Berten
Part load operation of high energy centrifugal pumps is associated with increased vibration levels which may adversely affect the machines operational safety. The main sources of vibrations in centrifugal pumps are of hydrodynamic nature. The interaction between rotating and stationary flow fields yields spatially distributed pressure fluctuation patterns, which excites mechanical vibrations of the rotating and stationary pump components. As virtually all modern, high-energy machines are operated using variable speed drives, an operation, where the...

Real-time motion planning, navigation, and behavior for large crowds of virtual humans

Barbara Yersin
Simulating crowds in real time is a challenging problem that touches many different aspects of Computer Graphics: rendering, animation, path planning, behavior, etc. Our work has mainly focused on two particular aspects of real-time crowds: motion planning and behavior. Real-time crowd motion planning requires fast, realistic methods for path planning as well as obstacle avoidance. The difficulty to find a satisfying trade-off between efficiency and believability is particularly challenging, and prior techniques tend to focus...

Hydrogenation and hydroformylation in ionic liquids, water and biphasic systems

Christian Ohlin
This work covers homogeneous and biphasic catalysis in ionic liquids and water. The work presented herein is divided into two major parts: catalytic hydrogenation and catalytic hydroformylation. The first part also serves as an introduction to catalysis in ionic liquids and water in general. The hydrogen solubility in ionic liquids is determined, and the effect on hydrogenation turnover frequencies in the catalytic reduction of benzene to cyclohexane in ionic liquids studied. The ruthenium catalysed reduction...

Multilevel preconditioners for elliptic problems with multiple scales

Klaus Sapelza
The purpose of this thesis is to investigate methods for the solution of multiscale problems both from the mathematical and numerical point of view, with a particular concern on applications to flows through heterogeneous porous media. After an overview of the recent developments in this vast field, a study of two representative multiscale techniques is carried out. The multiscale finite element method and a conjugate gradient iterative method preconditioned with an overlapping Schwarz domain decomposition...

Modeling and Characterization of Coated Conductors Applied to the Design of Superconducting Fault Current Limiters

François Roy
The Superconducting Fault Current Limiter (SFCL) appears to be a device of great interest to efficiently build the electrical grid of tomorrow. With the recent progress made by the superconducting wires manufacturers, there are needs coming from the industry to evaluate the potential of such devices. In the present thesis work, the behavior under external field and transport current of the last generation of wire is investigated. This study is conduct both experimentally and numerically...

Analysis of lightweight stream ciphers

Simon Fischer
Stream ciphers are fast cryptographic primitives to provide confidentiality of electronically transmitted data. They can be very suitable in environments with restricted resources, such as mobile devices or embedded systems. Practical examples are cell phones, RFID transponders, smart cards or devices in sensor networks. Besides efficiency, security is the most important property of a stream cipher. In this thesis, we address cryptanalysis of modern lightweight stream ciphers. We derive and improve cryptanalytic methods for different...

Life cycle assessment of mobile telephone networks, with focus on the end-of-life phase

Wolfram Scharnhorst
Mobile communication, in particular mobile telephony, is a service whose nonexistence nowadays is unimaginable. The ongoing, ever increasing penetration of mobile communication equipment, presently intensified by the transition from second generation1 to third generation2 mobile telephone technology, raises the necessity for environmentally sound production, operation and End-of-Life3 treatment. In order to determine potentials to improve the overall environmental performance of large technical systems, such as mobile phone networks, Life Cycle Assessment4 is increasingly accepted as...

Pôles de développement économique et logistique d'entreprise

Aymeric Sevestre
Economic development policies such as the Enterprise Zone have been pursued with different designs by state and local governments in many countries. These programs can be defined by a double objective: to promote and control economic growth. This thesis investigates the compatibility of these public policies with the location strategies of the private companies based on their logistical needs. The first step of this research gives a global view on the key elements of the...

DNA Topology:A Biophysical Study of DNA Rings, Knots, and Catenanes by Means of Atomic Force Microscopy and Numerical Simulations

Guillaume Witz
This thesis explores different aspects of DNA topology through experimental and numerical techniques. Topology is a vast mathematical field, that deals with the spatial properties of objects undergoing continuous deformations, but here it is restricted to the description of closed space curves such as rings, knots and catenanes. Topology is connected to practical problems in different domains including polymer physics, because a polymer chain is a type of space curve, whose statistical properties are affected...

Multiscale Computational Methodology Applied to Hydroacoustic Resonance in Cavitating Pipe Flow

Nicolas Ruchonnet
The present work is a contribution to the physical analysis and numerical simulation of the pressure surges in hydraulic machinery and connected conduit systems. Localized hydrodynamic instabilities including cavitation are prone to interact with the entire conduit through the propagation of acoustic plane waves. At resonance, the superimposition of the acoustic waves leads to the formation of large amplitudes standing waves along the entire conduit. The resulting fluctuation of velocity and pressure in the source...

Characterization of electron bunches from field emitter array cathodes for use in next-generation X-Ray free electron lasers

Simon Christian Leemann
PSI is interested in developing an X-FEL as a companion radiation source to the existing Swiss Light Source. In order to achieve radiation wavelengths as low as 1 Å, the X-FEL requires excellent electron beam quality and high beam energy. The energy requirements and thus the size and cost of the project can be reduced considerably if an ultra-low emittance electron source is developed. Therefore PSI has started the Low Emittance Gun Project with the...

Theory of non-linear spike-time-dependent plasticity

Jean-Pascal Pfister
A fascinating property of the brain is its ability to continuously evolve and adapt to a constantly changing environment. This ability to change over time, called plasticity, is mainly implemented at the level of the connections between neurons (i.e. the synapses). So if we want to understand the ability of the brain to evolve and to store new memories, it is necessary to study the rules that govern synaptic plasticity. Among the large variety of...

Combining robustness and recovery for airline schedules

Niklaus Eggenberg
In this thesis, we address different aspects of the airline scheduling problem. The main difficulty in this field lies in the combinatorial complexity of the problems. Furthermore, as airline schedules are often faced with perturbations called disruptions (bad weather conditions, technical failures, congestion, crew illness…), planning for better performance under uncertainty is an additional dimension to the complexity of the problem. Our main focus is to develop better schedules that are less sensitive to perturbations...

Evolution of cooperation in artificial ants

Markus Waibel
The evolution of cooperation is a fundamental and enduring puzzle in biology and the social sciences. Hundreds of theoretical models have been proposed, but empirical research has been hindered by the generation time of social organisms and by the difficulties of quantifying costs and benefits of cooperation. The significant increase in computational power in the last decade has made artificial evolution of simple social robots a promising alternative. This thesis is concerned with the artificial...

Collaborative routing in mobile partitioned networks

Natasa Sarafijanovic-Djukic
Embedded wireless networks find a broad spectrum of applications in transportation, environmental monitoring, logistics, supply chain management, and "pocketswitched" communication. The node mobility patterns in these applications tend to give rise to spatially heterogeneous node distributions, which may cause network partitions. In this thesis, we consider the problem of routing in mobile networks under such challenging conditions. More specifically, we endeavor to identify features of mobility common to different applications, in order to devise routing...

Microfluidic magnetic particles manipulation:concepts and devices

Amar Rida
In this thesis work we propose new concepts of transporting and manipulating magnetic particles on microfluidic scale. The objective is to propose solutions to the problems related to the integration of the magnetic inductive components within a microfluidic network for magnetic particle manipulation. A second part of this work is the study of the physics of magnetic particle pattern formation when a suspension of the particles is subjected to an external magnetic field. The first...

Automatic face analysis in static and dynamic environments

Matteo Sorci
Faces play a vital role in people's daily lives, as they are able to convey many different information and above all their behaviour and emotions. Therefore, for decades the face has been investigated by researchers in several fields such as computer science, psychology and social science to the extent that it became recently a fundamentally multidisciplinary matter. In order to study the perception and interpretation of this information in human-human, as well as human-computer interaction,...

Parametric coding of spatial audio

Christof Faller
A wide range of techniques for coding a single speech or audio signal channel have been developed over the last few decades. In addition to pure redundancy reduction, sophisticated source and receiver models have been considered for reducing the bitrate. Only a few techniques address joint-coding of the channels of stereo1 and multi-channel audio signals. Stereo and multi-channel audio signals evoke an auditory spatial image in a listener. Thus the receiver model may consider properties...

Novel organometallic ruthenium complexes for selective activation in tumour cells

Anna Katherine Renfrew
In recent years, ruthenium-based antitumour drugs have emerged as an attractive alternative to cisplatin, exhibiting both excellent activity in tumours where cisplatin is of limited use and low general toxicity, leading to reduced side effects. Two ruthenium(III) complexes, KP1019, and NAMI-A, have currently completed Phase I clinical trials and are in, or set to enter, Phase II trials. Expanding on the success of ruthenium(III) complexes, organoruthenium(II) compounds are also attracting increasing attention as anticancer drugs....

The role of the amygdala in emotional memories:a multidisciplinary approach

Kamila Markram & Carmen Sandi
This thesis investigates the role of the amygdala for the establishment of fear memories with a multidisciplinary approach, including behavioural, psychopharmacological, genetic, molecular, and electrophysiological techniques in rats or mice, under healthy or pathological conditions. This research program aims to shed light on the acquisition and storage of emotional memories in the amygdala and closely interconnected brain areas. In one line of experiments, the molecular mechanisms leading to the establishment of fear memory traces in...

Error handling in multimodal voice-enabled interfaces of tour-guide robots using graphical models

Plamen Prodanov
Mobile service robots are going to play an increasing role in the society of humans. Voice-enabled interaction with service robots becomes very important, if such robots are to be deployed in real-world environments and accepted by the vast majority of potential human users. The research presented in this thesis addresses the problem of speech recognition integration in an interactive voice-enabled interface of a service robot, in particular a tour-guide robot. The task of a tour-guide...

Quantum size effects in ultrathin metallic islands:a scanning tunneling microscopy/spectroscopy study

I-Po Hong
This thesis reports measurements concerning quantum size effects of single crystalline metallic islands by using low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS). Different sample systems are presented in the following chapters. In chapter 2, several aspects of quantum well states (QWS) of Pb ultrathin islands grown on Si(111) substrate are reported. The differential conductance spectra of QWS can be understood by discrete energy levels with linewidth broadening because of finite quasiparticle lifetime. Using low...

Seismic behavior of lightly reinforced concrete squat shear walls

Christian Greifenhagen
This thesis addresses the seismic evaluation of existing buildings. In particular, it focuses on the seismic behavior of lightly reinforced shear walls that are not designed to withstand earthquake actions. A shear strength envelope for the assessment of deformation capacity of these non-ductile walls is presented. The approach is the result of experimental investigations and analytical modeling. Existing models for plastic hinges in beams are enhanced in order to determine drift capacity of lightly reinforced...

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