Demenz im Bilderbuch? Martin Baltscheits "Geschichte vom Fuchs der den Verstand verlor"

Article for general public (2013)

A NEW SIMPLIFIED ANALYTICAL DESIGN METHOD FOR STEEL AND COMPOSITE SWAY FRAMES

in Journal of Constructional Steel Research (2013)

Eurocode 4 is the European design code for composite construction; in its so-called EN 1994-1-1 version, the design of “non-sway buildings” is mainly covered. As a result, EC4 focuses on the check of ... [more ▼]

Eurocode 4 is the European design code for composite construction; in its so-called EN 1994-1-1 version, the design of “non-sway buildings” is mainly covered. As a result, EC4 focuses on the check of structural elements like beams, columns, slabs and joints. However, in the last years, the construction of taller buildings and larger industrial halls without wind bracing systems tends to make global instability a relevant failure mode, which is not well covered by Eurocode 4. Recently, intensive experimental, numerical and theoretical investigations have been carried out at Liège University. The latter aimed at improving the knowledge in the field of sway composite building frames and at developing appropriate design rules. The rotational behavior of the beam-to-column composite joints is one of the key aspects of the problem to which a special attention has been paid. This paper reflects investigations carried out at Liège University on this topic. In particular, an innovative simplified analytical method to predict the ultimate loading factor and the associated collapse mode of both steel and composite frames subjected to static loadings is presented. [less ▲]

Homo ludens en la Revolución. Una lectura de Nellie Campobello

Book published by Iberoamericana/Vervuert (2013)

Holographic interferometry based on photorefractive crystal to measure 3D thermo-elastic distortion of composite structures and comparison with finite element models

in Lehmann, Peter (Ed.) Proc. SPIE Vol 8788 on Optical Measurement Systems for Industrial Inspection VIII (2013, May)

Thermo-elastic distortions of composite structures have been measured by a holographic camera using a BSO photorefractive crystal as the recording medium. The first test campaign (Phase 1) was performed ... [more ▼]

Thermo-elastic distortions of composite structures have been measured by a holographic camera using a BSO photorefractive crystal as the recording medium. The first test campaign (Phase 1) was performed on CFRP struts with titanium end-fittings glued to the tips of the strut. The samples were placed in a vacuum chamber. The holographic camera was located outside the chamber and configured with two illuminations to measure the relative out-of-plane and in-plane (in one direction) displacements. The second test campaign (Phase 2) was performed on a structure composed of a large Silicon Carbide base plate supported by 3 GFRP struts with glued Titanium end-fittings. Thermo-elastic distortions have been measured with the same holographic camera used in phase 1, but four illuminations, instead of two, have been used to provide the three components of displacement. This technique was specially developed and validated during the phase 2 in CSL laboratory. The system has been designed to measure an object size of typically 250x250 mm²; the measurement range is such that the sum of the largest relative displacements in the three measurement directions is maximum 20 μm. The validation of the four-illuminations technique led to measurement uncertainties of 120 nm for the relative in-plane and out-of-plane displacements, 230 nm for the absolute in-plane displacement and 400 nm for the absolute out-of-plane displacement. For both campaigns, the test results have been compared to the predictions obtained by finite element analyses and the correlation of these results was good [less ▲]

Statistical analysis of modulated codes for robot positioning -- Application to BeAMS

Report (2013)

Positioning is a fundamental issue for mobile robots. Therefore, a performance analysis is suitable to determine the behavior of a system, and to optimize its working. Unfortunately, some systems are only ... [more ▼]

Positioning is a fundamental issue for mobile robots. Therefore, a performance analysis is suitable to determine the behavior of a system, and to optimize its working. Unfortunately, some systems are only evaluated experimentally, which makes the performance analysis and design decisions very unclear. In [4], we have proposed a new angle measurement system, named BeAMS, that is the key element of an algorithm for mobile robot positioning. BeAMS introduces a new mechanism to measure angles: it detects a beacon when it enters and leaves an angular window. A theoretical framework for a thorough performance analysis of BeAMS has been provided to establish the upper bound of the variance, and to validate this bound through experiments and simulations. It has been shown that the estimator derived from the center of this angular window provides an unbiased estimate of the beacon angle. This document complements our paper by going into further details related to the code statistics of modulated signals in general, with an emphasis on BeAMS. In particular, the probability density function of the measured angle has been previously established with the assumption that there is no correlation between the times a beacon enters the angular window or leaves it. This assumption is questionable and, in this document, we reconsider this assumption and establish the exact probability density function of the angle estimated by BeAMS (without this assumption). The conclusion of this study is that the real variance of the estimator provided by BeAMS was slightly underestimated in our previous work. In addition to this speci c result, we also provide a new and extensive theoretical approach that can be used to analyze the statistics of any angle measurement method with beacons whose signal has been modulated. To summarize, this technical document has four purposes: (1) to establish the exact probability density function of the angle estimator of BeAMS, (2) to calculate a practical upper bound of the variance of this estimator, which is of practical interest for calibration and tracking (see Table 1, on page 13, for a summary), (3) to present a new theoretical approach to evaluate the performance of systems that use modulated (coded) signals, and (4) to show how the variance evolves exactly as a function of the angular window (while re- maining below the upper bound). [less ▲]

Computation of worst operation scenarios under uncertainty for static security management

in IEEE Transactions on Power Systems (2013), 28(2), 1697-1705

This paper deals with day-ahead static security assessment with respect to a postulated set of contingencies while taking into account uncertainties about the next day system conditions. We propose a ... [more ▼]

This paper deals with day-ahead static security assessment with respect to a postulated set of contingencies while taking into account uncertainties about the next day system conditions. We propose a heuristic approach to compute the worst-case under operation uncertainty for a contingency with respect to overloads. We formulate this problem as a non-convex nonlinear bilevel program that we solve approximately by a heuristic approach which relies on the solution of successive optimal power flow (OPF) and security-constrained optimal power flow (SCOPF) problems of a special type. The method aims at revealing those combinations of uncertainties and contingencies for which the best combination of preventive and corrective actions would not suffice to ensure security. Extensive numerical results on a small, a medium, and a very large system prove the interest of the approach. [less ▲]

L'outil SAFE : un outil interactif d’évaluation des consommations énergétiques des bâtiments résidentiels et des déplacements des personnes

Article for general public (2013)

Bovine lymphotropic herpesvirus detected in Belgium

in Veterinary Record : Journal of the British Veterinary Association (2013), 172

The bovine lymphotropic herpesvirus was detected for the first time outside the US, Canada and UK in a cow with nonresponsive chronic metritis.

Third generation stellar models for asteroseismology of hot B subdwarf stars. A test of accuracy with the pulsating eclipsing binary PG 1336–018

in Astronomy and Astrophysics (2013), 553

Context. Asteroseismic determinations of structural parameters of hot B subdwarfs (sdB) have been carried out for more than a decade now. These analyses rely on stellar models whose reliability for the ... [more ▼]

Context. Asteroseismic determinations of structural parameters of hot B subdwarfs (sdB) have been carried out for more than a decade now. These analyses rely on stellar models whose reliability for the required task needs to be evaluated critically. Aims. We present new models of the so-called third generation (3G) dedicated to the asteroseismology of sdB stars, in particular to long-period pulsators observed from space. These parameterized models are complete static structures suitable for analyzing both p- and g-mode pulsators, contrary to the former second generation (2G) models that were limited to p-modes. While the reliability of the 2G models has been successfully verified in the past, this important test still has to be conducted on the 3G structures. Methods. The close eclipsing binary PG 1336−018 provides a unique opportunity to test the reliability of hot B subdwarf models. We compare the structural parameters of the sdB component in PG 1336−018 obtained from asteroseismology based on the 3G models, with those derived independently from the modeling of the reflection/irradiation effect and the eclipses observed in the light curve. Results. The stellar parameters inferred from asteroseismology using the 3G models are found to be remarkably consistent with both the preferred orbital solution obtained from the binary light curve modeling and the updated spectroscopic estimates for the surface gravity of the star. The seismology gives M∗ = 0.471 ± 0.006 M⊙ , R∗ = 0.1474 ± 0.0009 R⊙ , and log g = 5.775 ± 0.007, while orbitology leads to M∗ = 0.466 ± 0.006 M⊙ , R∗ = 0.15 ± 0.01 R⊙ , log g = 5.77 ± 0.06, and spectroscopy yields log g = 5.771 ± 0.015. In comparison seismology from a former analysis based on the 2G models gave very similar results with M∗ = 0.459 ± 0.005 M⊙ , R∗ = 0.151±0.001 R⊙, and log g = 5.739±0.002. We also show that the uncertainties on the input physics included in stellar models have no noticeable impact, at the current level of accuracy, on the structural parameters derived by asteroseismology. Conclusions. The stellar models (both of second and third generation) presently used to carry out quantitative seismic analyses of sdB stars are reliable for the task. The stellar parameters inferred by this technique, at least for those that could be tested (M∗, R, and log g), appear to be both very precise and accurate, as no significant systematic effect has been found. [less ▲]

Fluorine-18 labeling of biocompatible nanoparticles for PET imaging

Poster (2013, May)