Analysis of Surface Tension from Aerodynamic Levitation of Liquids

Aerodynamic levitation allows contactless diagnostics of very high-temperature liquid properties. Liquids can be metals or inorganic compounds, and the levitation gas may have any composition. Temperature limitation is dependent on the heating power and radiative properties of the samples, with 3000°C possible for oxides. Surface-tension measurement is based on previous theories, which relate it to specific vibrations of the drop. Rotation and precession of liquid drops are specific aspects of aerodynamic levitation, and their effects are quantified here. Experimental examples for nickel and alumina are also shown and compared with results from previous experiments, when available.     

Estimation of time delays with fewer sensors than sources

A number of papers have been dealing with the problem of estimating the differential delay of an unknown signal impinging on two sensors. The present contribution deals with the presence of more than one source, which is a case that has never been dealt with before. The solution resorts to slices of high-order spectra, and the full spectral band of the signals is utilized in order to recover the delays. It can be viewed as an improvement to the classical procedure consisting of searching the autocorrelation for local maxima, which does not work when delays are smaller than the source correlation length     

Etude par mesures electriques des correlations entre defauts de structure et potentiel chimique de l'oxygene dans WO3 non-stoechiometrique

The variation of the electrical resistivity of non-stoichiometric WO₃, as a function of oxygen pressure has been studied at 750°C and in the range of 1 atm ? P_O2 ? 10^?16.6 atm, corresponding to 0 ? x ? 0.04.The stair-like log₁₀ρ vs log₁₀ P_O2 curve shows evidence of the existence of seven Magneli type phases in which the conduction mechanism depends on the shear planes rather than on point defects.     

Identification of precancerous lesions by multispectral gastroendoscopy

Gastric cancer is one of the fifth most deadly cancers worldwide. Nowadays the diagnosis is performed through gastroendoscopy under white light and histological analysis. However, the precancerous lesions are multifocalized and present low differences with respect to healthy tissue. Several systems have been proposed based on light tissue interaction to improve the visualization of malignancies. However, these systems are limited to few wavelengths. In this paper, we propose a minimally invasive technique based on multispectral imaging and a methodology to identify malignancies in the stomach. We developed a multispectral gastroendoscopic system compatible with current gastroendoscopes, where only the illumination is changed. The spectra are extracted from the acquired multispectral images in order to compute statistical features that are used to classify the data in two classes: healthy and malignant. The features are ranked by pooled variance t test to train three classifiers. Neural networks using generalized relevance learning vector quantization, support vector machine (SVM) with a Gaussian kernel and k-nn are evaluated using leave one patient out cross-validation. Taking into consideration the data collected in this work, the quantitative results from the classification using SVM show high accuracy and sensitivity using a low number of features. These results show the ability to discriminate malignancies of the gastric tissue. Therefore, multispectral imaging could help in the identification of malignancies during gastroendoscopy.     

Structure Control of Calcium Silicate Hydrate Gels for Dye Removal Applications

The structure of calcium silicate hydrate (C‐S‐H) gels was modified by hydrothermal reaction with aqueous acetic acid solvent, and then the C‐S‐H gels were used for dye removal from aqueous solution. With increasing acetic acid concentration, the Ca:Si molar ratio decreased and the length of the silicate anion chain structure of the C‐S‐H gels increased. The silicate anion chain length affects the number of available silanol groups on the surface of the C‐S‐H gel: the longer the silicate anion chain length, the greater the number of negative charges and the higher the surface potential. C‐S‐H gels with a long silicate anion structure exhibited higher adsorption capacity for methylene blue than gels with a short silicate anion structure. The enhanced adsorption capacity of the C‐S‐H gels is related to the higher number of silanol groups in the bridging silica tetrahedra of the intermediate anion chain structure compared with those in the end units of silica tetrahedra.     

Laser ultrasonic study of Lamb waves: determination of the thickness and velocities of a thin plate

Transient Lamb waves in a thin copper plate were generated and measured using a laser ultrasonic setup. A two-dimensional Fourier transform method has been employed to analyse the dispersion curves. This allowed a clear identification of multi-mode Lamb waves. Fitting of the dispersion curve allowed a direct determination of the thickness and bulk velocities, as well as the elastic constants. The obtained experimental results of Lamb waves on a copper plate show excellent agreement with the theoretical model.     

The high-challenge fireball — A trademark of the seventies

The high-challenge fire is a growing menace in commercial and industrial occupancies. Are sprinkler systems as we know them today able to meet the challenge? Perhaps they are not!     

Boltzmann machines as a model for parallel annealing

The potential of Boltzmann machines to cope with difficult combinatorial optimization problems is investigated. A discussion of various (parallel) models of Boltzmann machines is given based on the theory of Markov chains. A general strategy is presented for solving (approximately) combinatorial optimization problems with a Boltzmann machine. The strategy is illustrated by discussing the details for two different problems, namely MATCHING and GRAPH PARTITIONING.     

Contrôle optique du dépôt de couches multidiélectriques quart d’onde : techniques hybrides de traitement du signal utilisées pour améliorer les caractéristiques

An apparatus allowing an optical control of the deposition of quarterwave dielectric thin layers is described. This device utilizes a rapid scanning multichannel spectrometer coupled with a minicomputer; it gives, in real time, two signals respectively proportional to the two partial derivatives of the transmission factor with respect of thickness and of wavelength. By combining the effect of an analogic filtering and that of a numerical data processing, we obtain signals with extremely low noise, which permits a high precision control of quaterwave optical thickness layers by using the location of the zeros of one of the two derivatives. This allows layer stacks with a very critical control such as multicavity filters used in optical multi-demultiplexers required in telecommunications to be realized.