14,208 research outputs found
Probing large-distance higher-dimensional gravity with Cosmic Microwave Background measurements
It has been recently argued that higher dimensional gravity theories may
manifest themselves not only at short microscopic distances but also at large
cosmological scales. We study the constraints that cosmic microwave background
measurements set on such large distance modifications of the gravitational
potential
Superfluid-insulator transition of two-dimensional disordered Bose gases
We study the two-dimensional weakly repulsive Bose gas at zero temperature in
the presence of correlated disorder. Using large-scale simulations, we show
that the low-energy Bogoliubov cumulative density of states remains quadratic
up to a critical disorder strength, beyond which a power law with
disorder-dependent exponent sets in. We associate this threshold
behavior with the transition from superfluid to Bose glass, and compare the
resulting mean-field phase diagram with scaling laws and the Thomas-Fermi
percolation threshold of the mean-field density profile.Comment: Published version, 5 pages, 4 figure
Development of a dynamic virtual reality model of the inner ear sensory system as a learning and demonstrating tool
In order to keep track of the position and motion of our body in space, nature has given us a fascinating and very ingenious organ, the inner ear. Each inner ear includes five biological sensors - three angular and two linear accelerometers - which provide the body with the ability to sense angular and linear motion of the head with respect to inertial space. The aim of this paper is to present a dynamic virtual reality model of these sensors. This model, implemented in Matlab/Simulink, simulates the rotary chair testing which is one of the tests carried out during a diagnosis of the vestibular system. High-quality 3D-animations linked to the Simulink model are created using the export of CAD models into Virtual Reality Modeling Language (VRML) files. This virtual environment shows not only the test but also the state of each sensor (excited or inhibited) in real time. Virtual reality is used as a tool of integrated learning of the dynamic behavior of the inner ear using ergonomic paradigm of user interactivity (zoom, rotation, mouse interaction,…). It can be used as a learning and demonstrating tool either in the medicine field - to understand the behavior of the sensors during any kind of motion - or in the aeronautical field to relate the inner ear functioning to some sensory illusions
New image processing tools for structural dynamic monitoring
This paper presents an introduction to structural damage assessment using image processing on real data (non ideal conditions). Our contribution is much more a groundwork than a
classical experimental validation. After measuring the bridge dynamic parameter on a small resolution video, we conjointly present advantages and limitations of our method. Finally we
introduce several "computer vision" based rules and focus on the technical ability to detect damage using camera and video motion estimation
Experimental study of depolarization and antenna correlation in tunnels in the 1.3 GHz band
Measurements have been carried out in a low-traffic road tunnel to investigate the influence of the polarization of the transmitting and receiving antennas on the channel characteristics. A real-time channel sounder working in a frequency band around 1.3 GHz has been used, the elements of the transmitting and receiving arrays being dual-polarized patch antennas. Special emphasis is made on cross-polarization discrimination factor and on the spatial correlation between array elements which has a great influence on the performances of transmit/receive diversity schemes. Various polarizations both at the transmitter and the receiver have been tested to minimize this spatial correlation while keeping the size of the array as small as possible
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