Map management for robust long-term visual localization of an autonomous shuttle in changing conditions

Multimedia Tools and Applications - Changes in appearance present a tremendous problem for the visual localization of an autonomous vehicle in outdoor environments. Data association between the...     

Partial safety factors for laminated glass

Glass plies can be bonded together by polymeric interlayers to form laminated glass. Thanks to the capacity in finding alternative stress paths after partial breakage, it is commonly accepted that the more the layers are, the higher the safety level is. However, a negative aspect is that the tensile strength of glass carries a size effect in terms of surface area, which increases with lamination. Here we evaluate these competing factors by calibrating the partial safety factors to be used in semi-probabilistic (level-I) design, through comparison with probabilistic (level-III) methods in paradigmatic case-studies under wind, snow, and dead weight. Starting from a two-parameter Weibull distribution for glass strength, the “failure modes” approach determines the statistical distribution of strength for a multi-laminate as a function of the number of plies, which interferes with the statistics for actions. As a function of the target probability of failure for the assigned class of consequence, we introduce a new coefficient in the verification formula of level-I, to account for the effects of lamination with dependence upon the number of plies. We find that there is strong gain when passing from a monolith to a two-ply laminate, but the advantage fades by increasing the number of layers. Verification formulas of this type could avoid overconservative design.     

Degradation of C.I. Acid Orange 7 by heterogeneous Fenton oxidation in combination with ultrasonic irradiation

BACKGROUND: A mesoporous alumina supported nanosized Fe₂O₃ was prepared through an original synthesis procedure and used as a heterogeneous catalyst for the Fenton process degradation of the model azo dye C.I. Acid Orange 7 enhanced by ultrasound irradiation (US/Fe₂O₃‐Al₂O₃‐meso/H₂O₂ system). The effect of various operating conditions was investigated, namely hydrogen peroxide concentration, initial pH, ultrasonic power and catalyst loading. RESULTS: The results indicated that the degradation of C.I. Acid Orange 7 followed a pseudo‐first‐order kinetic model. There exists an optimal hydrogen peroxide concentration, initial pH, ultrasonic power and catalyst loading for decolorization. The aggregate size of the spent catalyst was reduced after dispersion in water by ultrasonic irradiation. A very low level of iron leaching was observed ranging from < 0.1 to 0.23 mg L^?1. The intermediate products of C.I. Acid Orange 7 degradation were identified using gas chromatography–mass spectrometry (GC‐MS). CONCLUSION: The optimal conditions for efficient C.I. Acid Orange 7 degradation were pH close to 3, hydrogen peroxide concentration 4 mmol L^?1, catalyst loading 0.3 g L^?1, and ultrasonic power 80 W. Copyright © 2011 Society of Chemical Industry     

Polarized second harmonic response of square, hexagonal and random arrays of gold metallic nanocylinders

The vertically and horizontally polarized second harmonic responses from arrays of gold metallic nanocylinders with different two-dimensional spatial organization, namely square, hexagonal and random arrangements, have been determined in transmission as a function of the input fundamental polarization angle. The results demonstrate that the second harmonic response is incoherent, resulting from the breaking of the centrosymmetry of the shape of the nanocylinders by surface defects. As a result, no effect from the geometrical arrangement of the nanocylinders on the substrate is observed.     

Sensitive detection of biological species through localized surface-plasmon resonance on gold nanodisks

In this paper, we are interested in the detection of biological molecules. This detection relies on the use of nanosensors based on localized surface-plasmon resonance (LSPR). We discuss the sensitivity of these nanosensors by studying the influence of the concentration of Biotin on the shift of the LSPR wavelength. Moreover, to study the selectivity of these sensors, the systems Biotin/Anti-Biotin (AB) and Biotin/Streptavidin (SA) are used to detect very weak concentration of AB or SA. We found respectively 7 pM and 3 nM for the limits of detection of SA and AB.     

évaluation de la fiabilité d'un dispositif d'évaluation des habiletés sociales chez des adolescents ayant des troubles du comportement.

Behaviour difficulties (BD) in school-age children and adolescent constitute an increasingly important concern for all participants in the Quebec and foreign education systems. The risk factors that can contribute to the development of BD are numerous (Kauffman, 2005). Amongst these appears a whole set of skills related to social competence (Bowen, Desbiens, Martin, & Hamel, 2001). The present study aims to test, by means of Generalisability theory, the reliability of the evaluation process developed to measure the level of teenage social skills according to various indicators (cooperation, self-control, assertion), various sources of information (adolescent, parent, and teacher), and various times (pretest, posttest 1, posttest 2). The coefficient of relative generalisability was found to be higher than the limit considered satisfactory, indicating that the evaluation process is reliable enough to allow differentiation of social skills for adolescent with BD. To develop intervention guidelines for BD students, a review of the sources of variation that may influence the accuracy of the measurement provided by the evaluation process is conducted through an analysis of facets (Bertrand & Blais, 2004) and a study of the most important variances components (Bain & Pini, 1996). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

3D modeling of uranium-bearing solution-collapse breccias in Proterozoic sandstones (Athabasca Basin,Canada)—Metallogenic interpretations

Unconformity-related uranium deposits are the highest grade, large tonnage uranium resources in the world. In the Athabasca Basin (northern Saskatchewan, Canada), which is the premier host for unconformity-type deposits, the ore deposits are frequently hosted and surrounded by breccias in sandstone. The significance of these breccias and their relation to mineralization are of major importance for the genesis of these high-grade deposits. Therefore, a modeling study, integrating results from structural geology and petrology, was performed with the gOcad 3D modeling software, in order to decipher geometrical and geological relationships between breccias, faults and mineralization zones. Mineralized bodies and the sudoite–dravite breccia bodies display strong spatial correlations. They appear to be controlled by reverse shear zones cross-cutting the unconformity and containing graphite in the basement. Geochemical computations evidenced that volumetric water–rock ratios up to 10,000 could be obtained in these breccia bodies for volume losses of up to 90%. Assuming reasonable values for quartz saturation, hydraulic conductivity and connected porosity, the minimal fluid volume and the time duration necessary to generate the sudoite–dravite breccia bodies were estimated at ca. 2 km³ and ca. 1 Myr, respectively. The comparison of these results with literature data suggests that the formation of sudoite–dravite breccia and mineralization could have been coeval. It may be proposed that within the space created by the quartz dissolution in the breccia body, a mixing between basement and basinal fluids could have induced U deposition and allowed the development of high-grade mineralization. The first-order uranium solubility that this coeval formation would imply is consistent with literature data, which suggests that this conceptual model is reasonable.     

Natural cement and monumental restoration

Natural cement, called “Roman” cement, was invented at the end of the 19th century and played an important role in the development of civil engineering works until the 1860s. More surprisingly, it was also used to restore historic buildings, such as gothic cathedrals. This paper deals with the mineralogy and the durability of natural cement in the particular case of the Bourges Cathedral in France. This study illustrates the interest of this material particularly adapted in stone repair or substitution. Contrary to traditional mortars, the present samples are made of neat cement paste, revealed by the absence of mineral additions as quartz or carbonate sand. Several combined techniques (SEM-EDS, TGA, XRD) were carried out to determine the composition of the hydraulic binder rich in calcium aluminate hydrates. The raw marl at the origin of the cement production contains oxidized pyrites which consist in a potential source of sulphate pollution of the surrounding limestone. The exposition of the cement in urban environment leads to some weathering features as atmospheric sulfation. Finally a petrophysical approach, based on water porosity, capillary sorption and compressive strength, has been performed to demonstrate the durability and the compatibility of natural cement applied as an historical building restoration mortar.     

In-line characterization of dielectric constant and leakage currents of low-k films with corona charge method

The use of corona charge method for monitoring the electrical properties of low-k dielectrics is investigated in this paper. First, the stability and reproducibility of k measurements are demonstrated on SiO₂-based low-k materials. As mercury probe is the reference tool for k and leakage measurements, a comparison of the dielectric constants and leakage currents between both techniques is carried out on a set of different low-k films with various dielectric constants and thicknesses. Good correlations (over 95%) were obtained for the k values and breakdown voltages on all studied layers and an 82% correlation has been obtained for leakage densities at 1 MV/cm. As a consequence, corona charge method seems to be a good alternative for mercury probe to monitor in-line back-end low-k films.