Numerical investigation of damage protective oxide mechanisms in thermal barrier system for aeronautical turbine blade.

The choice of a material for a given application requires insuring a good durability in its conditions of employment, in particular environmental. It is especially true for the systems destined to work in corrosive hot atmospheres. For it, the knowledge and the understanding of the corrosion phenomena, oxidization, ageing and damage are indispensable in order to anticipate the life period of the structures and to propose the adapted protective solutions. The study of the corrosion in high temperature is therefore a greatly interdisciplinary topic, into the interface of the physico-chemistry, metallic and ceramic materials and mechanics.We propose in this work a finite element method for the simulation of EBPVD TBCs spallation. Our studies concern one of several systems that we call thermal barrier coatings, which are a Composite materials deposited in layers on the hot components to isolate them chemically and thermally at high temperatures. This is the last operational technology adapted on aircraft engines but it is still studied and not fully exploited.This comprehensive article describes the systems currently used and the problem of interaction between mechanical and environment in the turbine. 

Étude de l’évolution du littoral de la baie d’El Jadida (Maroc) par photo-interprétation

La baie d’El Jadida se situe sur la façade atlantique du Maroc (entre 33° 15’ 00’’ et 33° 21’ 40’’ de latitude Nord, 8° 18’ 00’’ et 8° 30’ 00’’ de longitude Ouest). Elle constitue un grand système sableux fortement marqué par la dynamique littorale. L’utilisation des photographies aériennes permet de déterminer d’une part, l’évolution du trait de côte à l’embouchure de l’Oum Rbia à long terme (de 1949 à 1996) et d’autre part.de mesurer l’évolution de l’ensemble du littoral de la baie El Jadida à moyen terme (de 1988 à 1997). Les résultats de l’étude diachronique confirment la variabilité spatio-temporelle et l’évolution du littoral de la baie d’El Jadida avec des zones en érosion et d’autres en accumulation. L’analyse des variations des traits de côte, à moyen terme, ne montre pas des modifications importantes. Les seuls changements ont été enregistrés au niveau des unités morphologiques composant ce littoral (plage aérienne, dunes,…). L’évolution du trait de côte à long terme se caractérise par une forte variabilité dans le secteur de l’estuaire de l’Oum Rbia. La période d’érosion la plus importante se situe entre 1949 et 1996 avec un taux de recul de 45 m (1,28 m/an). Durant cette même période, on distingue aussi une variabilité spatiale qui se traduit par l’existence de deux secteurs très différents : le premier est caractérisé par une forte érosion (plage de la rive droite) et le deuxième est favorisé par des accumulations importantes (flèche sableuse de la rive gauche).Mots-clés : baie d’El Jadida, plage, estuaire, trait de côte, évolution morphologique, évolution diachronique, flèche sableuse, Maroc. Study of coastline evolution of the El Jadida bay (Morocco) by photo-interpretationEl Jadida bay, is located on the middle of the Atlantic coast of Morocco (between 33° 15’ 00’’ and 33° 21’ 40’’ North and between 8° 18’ 00’’ and 8° 30’ 00’’ West), constitute a large sandy stock strongly marked by the littoral dynamic. The use of the aerial photographs permit to identify the coast evolution to the Oum Rbia estuary (of 1949 to 1996) and to measure the littoral of the bay El Jadida evolution in medium-term. The results of this diachronic study confirm space and time variability in the littoral of bay evolution with deepening reach’s and others of sedimentation. The coastline variation analysis in medium-term doesn’t give satisfactory results. The only changes were registered at the morphological units of the coast (aerial beach, dunes, ... ). The coastline evolution in the long-term coast is characterized by a strong variability in the Oum Rbia estuary. The period of the most important erosion ranges between 1949 and 1996 with a rate of retreat of 45 m (1.28 m/an). During this period, we can also notice a space variability which results in the existence of two very different sectors: the first is characterized by strong erosion (beach of Right Bank) and the second is characterized by accumulations (sandy arrow of left bank).Keywords : El Jadida bay, estuary, coastline, morphologic evolution, diachronic evolution, sandy arrow, Morocco

Optimizing passive acoustic sampling of bats in forests

Passive acoustic methods are increasingly used in biodiversity research and monitoring programs because they are cost-effective and permit the collection of large datasets. However, the accuracy of the results depends on the bioacoustic characteristics of the focal taxa and their habitat use. In particular, this applies to bats which exhibit distinct activity patterns in three-dimensionally structured habitats such as forests. We assessed the performance of 21 acoustic sampling schemes with three temporal sampling patterns and seven sampling designs. Acoustic sampling was performed in 32 forest plots, each containing three microhabitats: forest ground, canopy, and forest gap. We compared bat activity, species richness, and sampling effort using species accumulation curves fitted with the clench equation. In addition, we estimated the sampling costs to undertake the best sampling schemes. We recorded a total of 145,433 echolocation call sequences of 16 bat species. Our results indicated that to generate the best outcome, it was necessary to sample all three microhabitats of a given forest location simultaneously throughout the entire night. Sampling only the forest gaps and the forest ground simultaneously was the second best choice and proved to be a viable alternative when the number of available detectors is limited. When assessing bat species richness at the 1-km(2) scale, the implementation of these sampling schemes at three to four forest locations yielded highest labor cost-benefit ratios but increasing equipment costs. Our study illustrates that multiple passive acoustic sampling schemes require testing based on the target taxa and habitat complexity and should be performed with reference to cost-benefit ratios. Choosing a standardized and replicated sampling scheme is particularly important to optimize the level of precision in inventories, especially when rare or elusive species are expected

Scatter reduction for grid-less mammography using the convolution-based image post-processing technique

Mammography examinations are highly affected by scattered radiation, as it degrades the quality of the image and complicates the diagnosis process. Anti-scatter grids are currently used in planar mammography examinations as the standard physical scattering reduction technique. This method has been found to be inefficient, as it increases the dose delivered to the patient, does not remove all the scattered radiation and increases the price of the equipment. Alternative scattering reduction methods, based on post-processing algorithms, are being investigated to substitute anti-scatter grids. Methods such as the convolution-based scatter estimation have lately become attractive as they are quicker and more flexible than pure Monte Carlo (MC) simulations. In this study we make use of this specific method, which is based on the premise that the scatter in the system is spatially diffuse, thus it can be approximated by a two-dimensional low-pass convolution filter of the primary image. This algorithm uses the narrow pencil beam method to obtain the scatter kernel used to convolve an image, acquired without anti-scatter grid. The results obtained show an image quality comparable, in the worst case, to the grid image, in terms of uniformity and contrast to noise ratio. Further improvement is expected when using clinically-representative phantoms

A semi-empirical model for scatter field reduction in digital mammography

X-ray mammography is the gold standard technique in breast cancer screening programmes. One of the main challenges that mammography is still facing is scattered radiation, which degrades the quality of the image and complicates the diagnosis process. Anti-scatter grids, the main standard physical scattering reduction technique, have some unresolved challenges as they increase the dose delivered to the patient, do not remove all the scattered radiation and increase the cost of the equipment. Alternative scattering reduction methods based on post-processing algorithms, have lately been under investigation. This study is concerned with the use of image post-processing to reduce the scatter contribution in the image, by convolving the primary plus scatter image with kernels obtained from simplified Monte Carlo (MC) simulations. The proposed semi-empirical approach uses up to five thickness-dependant symmetric kernels to accurately estimate the scatter contribution of different areas of the image. Single breast thickness-dependant kernels can over-estimate the scatter signal up to 60%, while kernels adapting to local variations have to be modified for each specific case adding high computational costs. The proposed method reduces the uncertainty to a 4%-10% range for a 35-70 mm breast thickness range, making it a very efficient, case-independent scatter modelling technique. To test the robustness of the method, the scattered corrected image has been successfully compared against full MC simulations for a range of breast thicknesses. In addition, clinical images of the 010A CIRS phantom were acquired with a mammography system with and without the presence of the anti-scatter grid. The grid-less images were post-processed and their quality was compared against the grid images, by evaluating the contrast-to-noise ratio and variance ratio using several test objects, which simulate calcifications and tumour masses. The results obtained show that the method reduces the scatter to similar levels than the anti-scatter grids

Short moan call reveals seasonal occurrence and diel-calling pattern of crabeater seals in the Weddell Sea, Antarctica

Crabeater seals (Lobodon carcinophaga) are an important component of the Southern Ocean as they are the most abundant pinniped species in this krill-based ecosystem; however, their acoustic repertoire and ecology remain to be fully described. Seasonal occurrence and diel-calling pattern of crabeater seal off the Maud Rise, eastern Weddell Sea, are described using passive acoustic monitoring data collected over 8 months (mid-January to mid-September) in 2014. We describe a new call type of crabeater seals, the short moan call (mean 90% duration: 2.2 ± 0.3 (SD) s, peak frequency: 596.5 ± 109.4 Hz, and frequency range: 122–1024 Hz), which was the only detected call type and 1871 calls were enumerated. Those crabeater seal calls were detected from April until mid-September (with peak in calling around September), which coincided with the appearance of sea ice. Short moan call rates were highest at night in August (i.e., 6.4 calls per minute) and September, and showed no diel variations for April through July. Distance to the sea ice edge and month of the year were the most important predictors of call occurrence and call rates of crabeater seals. This study highlights the Maud Rise as a useful habitat for this species.The South African National Antarctic Programme and the National Research Foundation and South African National Antarctic Programme for funding the SABWP.http://www.tandfonline.comtoc/tbio202021-09-21hj2021Mammal Research Institut

Analysis of CLDN14 gene in deaf Moroccan patients with non-syndromic hearing loss

Mutations in the CLDN14 gene, encoding the tight junction claudin 14 protein has been reported to date in an autosomal recessive form of isolated hearing loss DFNB29. In order to identify the contribution of CLDN14 to inherited deafness in Moroccan population, we performed a genetic analysis of this gene in 80 Moroccan familial cases. Our results show the presence of 7 mutations: 6 being conservative and one leading to a missense mutation (C11T) which was found at heterozygous and homozygous states, with a general frequency of 6.87%. The pathogenicity of the resulting T4M substitution is under discussion. Finally, our study suggests that CLDN14 gene can be implicated in the development of hearing loss in the Moroccan population

Molecular analysis of the TMPRSS3 gene in Moroccan families with non-syndromic hearing loss

Autosomal recessive non-syndromic hearing impairment (ARNSHI) is the most common type of inherited hearing impairment, accounting for approximately 80% of inherited prelingual hearing impairment. Hearing loss is noted to be both phenotypically and genetically heterogeneous. Mutations in the TMPRSS3 gene, which encodes a transmembrane serine protease, are known to cause autosomal recessive non-syndromic hearing impairment DFNB8/10. In order to elucidate if the TMPRSS3 gene is responsible for ARNSHI in 80 Moroccan families with non-syndromic hearing impairment, the gene was sequenced using DNA samples from these families. Nineteen TMPRSS3 variants were found, nine are located in the exons among which six are missense and three are synonymous. The 10 remaining variations are located in non-coding regions. Missense variants analysis show that they do not have a significant pathogenic effect on protein while pathogenicity of some variant remains under discussion. Thus we show that the TMPRSS3 gene is not a major contributor to non-syndromic deafness in the Moroccan population

JESÚS GARCÍA, REGINA [Material gráfico]

Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte, 201