Comparative topographic study of surface micro‐relief of primary martensite plates in shape memory alloys with different crystalline structures

The surface micro‐reliefs of primary martensite plates, representative for two shape memory alloys (SMAs) with different crystalline structures were compared from qualitative and quantitative point of view by scanning electron microscopy and atomic force microscopy, respectively. Qualitative evaluations revealed larger widths and heights of the primary plates of ε hexagonal close packed (hcp) martensite, in an Fe‐Mn‐Si‐Cr‐Ni SMA than those of β₂′ orthorhombic (9R) martensite, in a Cu‐Zn‐Al SMA. Quantitative evaluations were based on systematic dimensional measurements of the width and height of primary plate profiles. The measurements were performed on one hundred and twenty five profiles, five on each martensite plate belonging to five typical groups of primary plates, with length above 50 micrometers, of both ε hcp and β₂′ 9R martensites. In order to compare the topographies of the two types of plates a statistical evaluation of the dimensional intervals of width and height of measured plates was performed.     

Surface shape measurement of mirrors in the form of rotation figures by using point diffraction interferometer

The paper deals with the use of a point diffraction interferometer (PDI) to study the surface shape of rotation figures. The relations are given for the correspondence of the coordinates on the surfaces of an ellipsoid, a paraboloid and a hyperboloid as well as on an interferogram. Using PDI and Zygo white-light interferometer (WLI), we experimentally investigated the surface shape of the grazing incidence ellipsoid with the multilayer reflective coating on a wavelength of 0.154 nm with the following parameters: length is 55 mm, half-axis are 6 and 235 mm. The results coincided with an accuracy of 73 nm (RMS) without taking into account the PDI lateral resolution, and with an accuracy of 50 nm (RMS) with taking it into account, which ensures the local angles measurement accuracy of the ellipsoid-shaped reflecting surface at a level of 3 μrad. We think that this difference may be attributed to the limited lateral resolution of PDI and errors of frames stitching of WLI; nevertheless, we do believe that the PDI measurement accuracy is in the range of sub-μrad.     

Study of the dimensional instabilities of laminated polypropylene films during heating treatments

Ensuring the geometrical stability of organic coatings is a key challenge for steel/polymer composites produced by the automotive industry to reduce the cars' weight. During the thermal treatment of painting, which exceeds the melting temperature of the organic part of the laminated film, polymer shrinkage may occur. It induces uncovered parts of the steel sheet which would present negative corrosion behavior in use. Two original and innovative experiments were presented. They enable to measure the deformation induced by the shrinkage and then to identify the microstructural mechanisms responsible for its appearance. Main results show strong influences of the macromolecular chains orientation induced by the film extrusion process and of the postheating parameters used to perform the painting curing. Raman spectroscopy and differential scanning calorimetry are used both to perform analysis of the microstructure evolution during heating treatments in terms of crystals melting, crystalline macromolecular chains disorientation, and volume damage healing. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Investigations of electrically driven liquid metal flows using an ultrasound Doppler flow mapping system

This paper presents a combined experimental and numerical study of the properties of a liquid metal flow inside a cylinder driven by the application of a strong electrical current. The interaction between the electric current running through the melt and the corresponding induced magnetic field produces so-called electro-vortex flows. We consider here a configuration of two parallel pencil electrodes immersed at the free surface. Velocity measurements were performed by means of the Ultrasound Doppler method. A linear array of 25 singular transducers was used to determine the two-dimensional pattern of the vertical flow component. Numerical simulations of the magnetohydrodynamic (MHD) problem were conducted to calculate the Lorentz force, the Joule heating and the induced melt flow. Experimental and numerical results reveal a complex three-dimensional flow structure of the liquid metal flow. In particular, two pronounced downward jets are formed below both electrodes. The flow structure appears to be symmetrical with respect to two vertical cross sections being perpendicular to each other and one of the two planes contains the electrodes. The comparison between the experimental data and the numerical results shows a very good agreement.     

Optimal design of measurement network for neutronic activity field reconstruction by data assimilation

An optimal reconstruction of the neutronic activity field can be determined for a nuclear reactor core using a data assimilation framework to merge information from models and measurements. In this paper, we focus on solving the inverse problem of determining an optimal repartition of the measuring instruments within the core, to get the best possible results from the data assimilation reconstruction procedure. The position optimisation is realised using a Simulated Annealing algorithm, based on the Metropolis-Hastings proposition. Moreover, algebraic improvements of data assimilation have been developed, optimising their computational performance, and are presented here.     

Quartz crystal unit modeling at cryogenic temperatures

The aim of this paper was to develop the new quartz crystal electrical model including its temperature properties in the temperature range from 83.15 K (−190 °C) to 303.15 K (+30 °C) through experimental set-up and simulation analysis. Both the methodology of the quartz resonator measurements, the instrument setup, and the measurement methods needed to collect the necessary data as well as polynomial approximation of temperature dependence were described. The electrical model of AT-cut type quartz crystal for cryogenic temperatures was developed, in which its elements were expressed as functions of temperature. Using these polynomials, the behavioral model for PSPICE computer program has been worked out.