University of the Littoral Opal Coast

About: University of the Littoral Opal Coast is a education organization based out in Dunkirk, France. It is known for research contribution in the topics: Catalysis & Dielectric. The organization has 1242 authors who have published 2383 publications receiving 46230 citations. The organization is also known as: ULCO.

Pyro, Ferro and Dielectric Properties of Ba0.8Sr0.2TiO3 Films Deposited by Sol-Gel on Platinized Silicon Substrates

Abstract: We report on the deposition by a sol-gel process of Ba 0.8 Sr 0.2 TiO 3 films on platinum coated silicon substrates. X-Ray diffraction patterns show that the films are (111) preferentially oriented. The surface morphology is smooth, without cracks and the grain size is about 50 nm as determined by AFM and SEM. The dielectric constant measured from 10 2 to 10 6 Hz decreases slightly and is around 400 at 10 4 Hz. The losses are constant in a first approximation for a 1.5 μ m thick film with a value of 0.03 at 10 kHz. The existence of an hysteresis cycle attests that the films, whatever their thickness, are in a ferroelectric state. Pyroelectric coefficients have been determined and the best figure of merit obtained at 293 K and 10 kHz is 40 μ C/m 3 /K.

GUIDE: Unifying Evolutionary Engines through a Graphical User Interface

Abstract: Many kinds of Evolutionary Algorithms (EAs) have been described in the literature since the last 30 years. However, though most of them share a common structure, no existing software package allows the user to actually shift from one model to another by simply changing a few parameters, e.g. in a single window of a Graphical User Interface. This paper presents GUIDE, a \(\underline{G}raphical~\underline{U}ser~\underline{I}nterface\) for \(\underline{D}REAM~\underline{E}xperiments\) that, among other user-friendly features, unifies all kinds of EAs into a single panel, as far as evolution parameters are concerned. Such a window can be used either to ask for one of the well known ready-to-use algorithms, or to very easily explore new combinations that have not yet been studied. Another advantage of grouping all necessary elements to describe virtually all kinds of EAs is that it creates a fantastic pedagogic tool to teach EAs to students and newcomers to the field.

Multiple-sound-source-excitation quartz-enhanced photoacoustic spectroscopy based on a single-line spot pattern multi-pass cell

Abstract: Multiple-sound-source-excitation quartz-enhanced photoacoustic spectroscopy (MSSE-QEPAS) based on a single-line spot pattern multi-pass cell (MPC) is reported for trace gas detection. The single-line spot pattern MPC is designed to make a laser beam pass through a quartz tuning fork (QTF) 60 times, thus producing 60 sound sources between the two QTF prongs. These sound sources excite the QTF operating at fundamental resonance mode in phase, resulting in a signal gain factor of ∼20. A theoretical mode based on convolution method is proposed to explain the working mechanism of MSSE-QEPAS.

Direct laser writing of a low-loss waveguide with independent control over the transverse dimension and the refractive index contrast between the core and the cladding.

Abstract: In this Letter, we present the realization of a low-loss waveguide in a chalcogenide glass by direct laser writing technique in a particular configuration that allows the independent control over the diameter of the core and the magnitude of the refractive index contrast with the cladding. The waveguide is of multicore type and composed of 19 channels arranged on a hexagonal lattice. Each channel is obtained by stacking voxels of refractive index variation obtained by static exposure to femtosecond laser pulse burst. The distance between the channels can be used to vary the diameter of the waveguide, while the duration of laser burst controls the magnitude of the effective index and the propagation loss. We demonstrate that it can be reduced down to 0.11 dB/cm.