4,937 Works

Adaptive sensorimotor peripersonal space representation and motor learning for a humanoid robot

Micha Hersch
This thesis presents possible computational mechanisms by which a humanoid robot can develop a coherent representation of the space within its reach (its peripersonal space), and use it to control its movements. Those mechanisms are inspired by current theories of peripersonal space representation and motor control in humans, targeting a cross-fertilization between robotics on one side, and cognitive science on the other side. This research addresses the issue of adaptivity the sensorimotor level, at the...

Large scale selective event dissemination

Sidath Handurukande
Event-based systems usually denote distributed infrastructures that are used to asynchronously disseminate information among geographically distant computing units. In these systems, the information sources (a.k.a. publishers) produce events and the system delivers these events to destinations (a.k.a. subscribers). Subscribers are "decoupled" from publishers in the sense that they do not need to know each other or even be "up" at the same time. The subscribers can specify the kind of information they like to receive...

The closed form solution of the inverse kinematic problem of 3r positioning manipulators

Péter Mikó
In this thesis we contribute to the inverse kinematics solution of serial positional manipulators with three rotational joints (3R). This type of linkage is frequently used for 6R manipulators, where three – mostly the last – joint axes intersect at one point, decoupling with this structure the positional from the orientational part of the forward kinetics. In order to solve the inverse kinematics problem, i.e. to find the joint values for a given point in...

Modeling and optimization of ultrasonic linear motors

José Fernandez Lopez
Ultrasonic motors have received much attention these last years, in particular with regard to their modeling and their design principle. Their operating principle is based on piezoelectric ceramics that convert electrical energy into mechanical energy in the form of vibrations of an elastic body whose surface points perform an elliptic motion with a frequency in the ultrasonic range (≥ 20 kHz). The moving part, which is pressed against the vibrating body by a prestressing force,...

Building trust-aware P2P systems:from trust and reputation management to decentralized e-commerce applications

Zoran Despotovic
This thesis is concerned with enabling e-commerce applications in decentralized environments, P2P networks in particular. The work goes along the following two dimensions: P2P reputation systems design and building P2P e-commerce services and applications. Enabling any kind of commerce has as the very first precondition providing appropriate assurance mechanisms that reduce or eliminate opportunistic behavior of the involved parties. Traditional forms of such mechanisms, such as contractual agreements monitored by enforcement institutions, are not always...

Neutron Scattering Investigations of Weakly Coupled and Weakly Connected Antiferromagnets

Krunoslav Prsa
Antiferromagnetic insulators at low temperatures offer a clean arena to study non-semiclassical phenomena because the character of interactions is usually known. Macroscopic properties of the system can then be calculated by more or less sophisticated approximations and compared to experimental results. Generally, quantum effects are expected to increase by lowering the couplings or connectivity between the magnetic moments. Magnetic excitations, which can be easily measured by the neutron spectroscopy technique, are particularly sensitive to quantum...

Application des réseaux de Bragg à la détermination des déformations distribuées dans les matériaux composites

Gabriel Dunkel
The behaviour of brittle matrix fibre reinforced-composites is dependent of the properties of its constituents (fibre, matrix and fibre-matrix interface) and is affected by the mechanical and environmental loads. The fracture of a unidirectional composite material is the result of various micro-mechanisms (matrix and/or fiber fractures, crack fibre interactions, interface failure, delamination, …) that generally occur simultaneously. Among these, one distinguishes the failure by fibre-matrix debonding and the frictional sliding along the composite interfaces. The...

Développement d'un appareillage pour l'étude de la polarisation optique de l'hélium-3 et de sa relaxation par des surfaces

Jean Ganiere
We have developed an apparatus to polarize 3He gas (at a few torrs pressure) by optical pumping from a 4He light source and to measure the evolution of the magnetic moment for relaxation studies. The magnetic moment is measured by applying a pulse of radio frequency magnetic field B1 transverse to the static magnetic field B0 and by amplifying the signal induced by the free precession of the magnetic moment. As the relative decrease of...

Biomechanics of Vascular Wall:the Role of Structural Organization of Elastin and Collagen

Rana Saitta-Rezakhaniha
This thesis contributes to the field of biomechanics of vascular wall. The focus is particularly on the microstructure of vascular elastin and collagen constituents and their contribution to the macroscopic mechanical behavior of the wall. The analysis is done in the framework of continuum mechanics. The work characterizes structural features of elastin and collagen fibers using microscopy techniques and introduces these features to constituent-based constitutive models. The models are applied to the experimental data, derived...

Non-cooperative behavior in wireless networks

Márk Félegyházi
Existing cellular networks are centrally managed and require a tremendous initial investment. With the advancement of new wireless technologies, the operators of traditional networks have to face new competition. New technologies make it possible to provide wireless services with substantially less investment. There are two interdependent trends that enable this progress: the evolution of technology and the evolution of spectrum policy. These two trends point towards a more colorful landscape of wireless communication technologies. In...

Dégénérescence orbitale et ordre magnétique sur le réseau triangulaire:le cas des composés LiNiO2 et NaNiO2

François Vernay
Compounds made of transition metal ions on a triangular lattice may have orbitally degenerate eg states. This is the case for LiNiO2 and NaNiO2 : the Ni3+ ions are in a low-spin state, leaving the last electron of the d-shell in the eg orbitals. In order to understand the magnetic behavior of such systems, we investigate a spin-orbital effective hamiltonian. Using exact diagonalization algorithms of finite clusters and variational approaches we have investigated the phase...

Étapes marquantes du développement urbain de la Chaux-de-Fonds:les contributions de Moïse Perret-Gentil, de Charles-Henri Junod et de Charles-Frédéric Knab

Tearanel Te
The city planning of La Chaux-de-Fonds, they way we know it today, is the result of a long evolution. It starts the day after a fire which, in 1794, practically devastated the whole village. With the human and material loss which the fire caused, this disaster offered the possibility to reconstruct on a new basis. The fear of fire and the demands of the watch industry, will dictate the policy of city planners and architects....

RedOx Stability of Anode Supported Solid Oxide Fuel Cells

Antonin Faes
The weakness of nickel-based solid oxide fuel cell anodes is their low ability to withstand re-oxidation at working temperature, especially for the anode-supported cell design. The volume expansion coming along with nickel (Ni) oxidation induces stresses in the layers and cracks especially for the thin supported electrolyte. Standard Ni-yttria stabilized zirconia (YSZ) anode-supports and half-cells (anode + electrolyte) were studied during repeated reduction and oxidation cycles (RedOx cycles) at different scales and different temperatures. The...

Model Checking of Distributed Algorithm Implementations

Maysam Yabandeh
It is notoriously difficult to develop reliable, high-performance distributed systems that run over asynchronous networks. Even if a distributed system is based on a well-understood distributed algorithm, its implementation can contain errors arising from complexities of realistic distributed environments or simply coding errors. Many of these errors can only manifest after the system has been running for a long time, has developed a complex topology, and has experienced a particular sequence of low-probability events such...

Sediment Evacuation from Reservoirs through Intakes by Jet Induced Flow

Jolanda Maria Isabella Jenzer Althaus
Reservoir sedimentation is worldwide a significant long term problem and requires in view of the current mitigation measures an alternative and more sustainable solution. This challenge motivated the present study with the purpose to develop an alternative efficient method to release sediment out of a reservoir. The concept is based on the release of sediment through the headrace tunnel and turbines whereby a special focus was set on the fine sediment in the area in...

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