Synthesis and characterization of perovskite oxides lafe1-xcuxo3 (0 ≤ x ≤ 0.4) obtained by sol-gel method

LaFe1-xCuxO3 (where x ranged from 0 to 0.4) powders are successfully synthesized by the solgel method employing metal nitrate salts as cations precursors and methanol as solvent. Thermogravimetric and differential thermal analysis (TGA/DTA) results exhibit that decomposition of the precursor to the oxide completed at about 750°C. XRD patterns exhibit that the materials belong to a cubic system. All samples show two IR active vibrational modes, one at 560 cm-1 assigned to Fe-O stretching vibration and another one at 1385 cm-1 assigned to the stretching of metal carbonates. SEM images of the samples show that the particle size is from 63 to 158 nm and the specific surface areas are relatively low. The electrochemical measurements exhibit that the catalytic activity is influenced by copper doping. The highest electrode performance is achieved with the oxide LaFe0.7Cu0.3O3.Keywords: perovskite oxide, sol-gel, thermogravimetric analysis, powder diffraction,electrochemical properties

Exploring Spoken Named Entity Recognition: A Cross-Lingual Perspective

Recent advancements in Named Entity Recognition (NER) have significantly improved the identification of entities in textual data. However, spoken NER, a specialized field of spoken document retrieval, lags behind due to its limited research and scarce datasets. Moreover, cross-lingual transfer learning in spoken NER has remained unexplored. This paper utilizes transfer learning across Dutch, English, and German using pipeline and End-to-End (E2E) schemes. We employ Wav2Vec2-XLS-R models on custom pseudo-annotated datasets and investigate several architectures for the adaptability of cross-lingual systems. Our results demonstrate that End-to-End spoken NER outperforms pipeline-based alternatives over our limited annotations. Notably, transfer learning from German to Dutch surpasses the Dutch E2E system by 7% and the Dutch pipeline system by 4%. This study not only underscores the feasibility of transfer learning in spoken NER but also sets promising outcomes for future evaluations, hinting at the need for comprehensive data collection to augment the results

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Optimization of GaInP solar cell performances

In this paper we study a BSF layer structure of a GaInP solar cell and we search for technological parameters of this last leading to its optimized performance (using PC1D simulator). The optimized structure gives the following results: η=19% and FF=85,2%. We also compare these cell performances with those of an optimized GaInP single junction solar cell to show the BSF layer improvement

Effet de la couche fenetre sur les performances d’une cellule solaire à base de GaAs

Abstract- During the last years, III-V solar cells were widely used, more particularly in spatial applications, because of their high conversion efficiency and their weak degradation in front of space irradiations. This paper reports on a simulation of a GaAs solar cell using a PC1D. The properties of the top layer in a solar cell (thickness, doping,...) in particular, plays a crucial role in its performances, in order to optimise them we analysed their influence on the Photovoltaic parameters of the cell. To demonstrate the importance of the deposition of a window layer Ga1-xAlxAs on the top of a GaAs solar cell we carried out a comparison of performances between a cell with a window and a conventional GaAs cell (without window). The optimized structure gives the following results: η =26.5% end FF=86.05%. We also compare these cell performances with those of an optimised GaAs single junction solar cell to show the window layer improvement

Étude de la réponse à une sollicitation cyclique des composants en AMF utilisés comme activateurs

Les alliages à mémoire de forme (AMF) présentent plusieurs propriétés particulières: la pseudoélasticité, l’effet mémoire de forme et la propriété qui concerne l’amortissement. Les mécanismes relativement complexes qui sont à la base de ces propriétés exceptionnelles ont pour origine une transformation au sein du matériau, dite transformation martensitique. Les alliages à mémoire de forme sont sujets à des modifications de leurs propriétés remarquables lors de cycles thermomécaniques. Le comportement en fatigue de ces matériaux est conditionné par différents mécanismes qui agissent sur la microstructure de ces alliages. Il est intéressant d’étudier la dégradation (endommagement) de ces caractéristiques durant des cycles de fatigue pour pouvoir prédire la stabilité d’un système mécanique utilisant ces alliages. Le travail présenté ici est une contribution à l’étude de la réponse à une sollicitation de fatigue des AMF. Pour cela, on considère un modèle mathématique qui prend en compte l’endommagement de la pseudoélasticité, conséquence à un chargement cyclique

New approach to determine the plastic viscosity of self-compacting concrete

International audienceThe rheology of concrete is best measured with the use of a rheometer. The slump flow test gives a good indication of the flowability of the mixture and is therefore still used extensively to judge the workability of SCC mixtures. However, this test presents some defects. The objective of this paper is to develop a new methodology for measuring the workability of a SCC. In this article, we have proposed a correlation between the plastic viscosity of concrete, the time and the characteristics of the flow final profile from the V-funnel coupled to a Plexiglas horizontal channel. The proposed approach, verified by experimental results, represents a simple, economical and usable tool on building site, and it allows to characterize rheologically the SCC from its flow. The comparison between our approach and the experimental values of the plastic viscosity shows that, in a laboratory or on site, instead of using a rheometer we can use our approach to characterize the rheological behavior of a SCC

Prediction of Self-Compacting Concrete homogeneity by ultrasonic

To evaluate the filling capacity of self-compacting concrete SCC without segregation, a technique based on the ultrasonic velocity has been adapted in order to estimate homogeneity and quality of concrete at very young age. To monitor local change in ultrasonic velocity, the process consists of using a pair of transducers at different depths of the concrete. The aim of our experimental study was to establish the relationship between ultrasonic velocity measured by sensors of 50 mm diameter and of 54 kHz frequency, and homogeneity of fresh concrete. Measurements of wave propagation velocity are carried out every half an hour on a vertical channel whose dimensions (in mm) are 160 × 160 × 700. These measurements have been determined with three modes of transmission: direct, semi-direct and indirect. The different mixtures were prepared with the same Water/Binder ratio (W/B) of 0.28. The amount of binder is in the order of 520 kg/m3. Comparison between ultrasonic velocity and empirical tests such as sieve stability test, slump flow test, air content, and compressive strength, at 1 day, shows that the ultrasonic velocity can also be very useful to evaluate homogeneity and quality of fresh concrete