IR thermography for lightning-strike damage monitoring in composite materials

International audienceThe increasing tendency to substitute metallic parts of aircrafts by lighter composite structures comes with other issues. One of them is the resistance of composite materials to lightning strike. The present paper illustrates how the use of infrared thermography can improve the understanding of lightning-strike induced damage and assess its severity. It is based on an experimental campaign carried out in ONERA: several carbon/epoxy composite samples, with or without specific protection, were impacted by lightning arcs of various current levels. An infrared camera was used during and after those tests to monitor and analyze the resulting damage inside the samples

Impacto da adiposidade nos parâmetros imunológicos

Studies evaluating immune function in obese humans and experimental animals indicate that the excess adiposity is associated with impaired in immune responses. Obesity is related to a higher rate of infections and to some types of cancer. Nutritional, metabolic and endocrine factors are implicated in the immunological changes. The adipose tissue directly produces substances with various functions related to immune system. Furthermore, some investigations suggest that certain types of weight reduction strategies can alter the immune function. Nevertheless, long-term studies should be carried out to address whether these changes positively affects the ability of these obese individuals to control infections and tumor development.Estudos acerca da função imunológica em animais experimentais e humanos obesos indicam que o excesso de adiposidade associa-se ao prejuízo da resposta imune. A obesidade está relacionada a uma taxa maior de infecções e a alguns tipos de câncer. Fatores nutricionais, metabólicos e endócrinos estão implicados nessas alterações imunológicas. O próprio tecido adiposo produz diretamente substâncias com várias funções relacionadas ao sistema imune. Além disso, algumas investigações sugerem que certas estratégias para perda de peso podem alterar a função imune. Entretanto, estudos em longo prazo são necessários para avaliar se tais alterações afetam positivamente a capacidade desses pacientes obesos de controlar infecções e desenvolver tumores

Effects of Ultrashort Pulsed Direct Laser Writing on Ni/Al Reactive Multilayer Foils

Reactive multilayer foils (RMFs) for joining processes have attracted a great deal of attention over the last few years. They are capable of exothermic self-propagating reactions and can serve as localized heat sources for joining applications when ignited by suitable means. Using short and ultrashort pulsed lasers with carefully selected parameters, cutting and shaping of RMFs makes it possible to tailor heat release characteristics without triggering the reaction. The present study is an investigation of microstructural changes induced by femtosecond laser machining of a commercially available Ni/Al-based RMF. The effects of the specific laser parameters pulse duration and repetition rate on the heat-affected zone (HAZ) are investigated by scanning and transmission electron microscopy. Debris consisting of oxide deposits can be found at a distance of several tens of microns from the cut edge. A negligible HAZ extending to less than 100 nm was observed for all parameters tested and no signs of ignition of a self-propagating reaction were observed. These results underline the suitability of femtosecond lasers for metal machining with minimal heat input

Status of Scoping Nuclear Analyses for the Evolving Design of ITER TBM Port Cells

ITER is an international collaborative effort towards the realization of fusion energy via the magnetic confinement concept. Two of the equatorial ports in the facility are dedicated to the testing of tritium breeding concepts, which is essential for the tritium self-sufficiency of future fusion reactors. The concerned Test Blanket System (TBS) consists of a Test Blanket Module (TBM) residing inside the TBM–Port Plug (TBM-PP) and its associated ancillary systems in the Tokamak facility. In this paper, the results of a full suite of nuclear analyses concerning the shielding performance of the Pipe Forest (PF) and Bioshield Plug (BP), to reflect on the evolution of their designs, are discussed. On the BP side, the design of the peripheral part has been reviewed considering the ventilation openings and butterfly doors, to assure the design compliance with the Radiation Map (RadMap) requirements for the neutron flux in the Port Cell (PC), behind the BP. On the PF side, the pipes routing and maintenance corridor door have been redesigned, by taking into account results from previously concluded nuclear analyses. The neutronics model was developed from CAD and was used to perform transport simulations in two plasma modes: on and off. For plasma-on mode, the plasma neutron field in the Port Interspace (PI) as well as behind the BP was assessed and few shielding options were explored. The responses due to decay neutrons from 17N in activated cooling water were also considered. For the plasma-off mode, the focus was shifted to further refine the ShutDown Dose Rate (SDDR) maps, which is of importance for maintenance operations that are foreseen to take place at various stages of ITER operation, in particular following the FPO-1, FPO-2, and Short operation scenarios. In addition, detailed activation analyses were carried out to provide a provisional waste classification

The QUEST initiative anemia study in ESRD: rationale and study protocol

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Numerical Modeling For Fracture Mechanics Problems Using The Open-source Fenics Platform

Fracture mechanics is the mechanical approach to fracture processes, which emerged due to limitations in the application of traditional concepts of Mechanics of Materials to predict the behavior of cracked materials. Analytical problem solutions with this approach may be unattainable, which allows the use of numerical modeling, such as the finite element method. However, the use of more advanced software that solves engineering problems numerically is limited by its high cost. FEniCS is an open source computational platform that solves partial differential equations by the finite element method. Thus, from a tutorial for this computational platform, this work proposes to reproduce a classic problem of linear elastic fracture mechanics, based on the validation of a comparison of a linear elastic problem with the commercial software ANSYS ®. With the help of the provided tutorial, an code was built to model a three-point bending test. Implemented with the aid of Gmsh and Paraview, it was possible to obtain satisfactory results, and to show that FeniCS is a powerful and accessible tool for solving fracture mechanics problems. La mecánica de la fractura es el enfoque mecánico de los procesos de fractura, que surgió debido a las limitaciones en la aplicación de los conceptos tradicionales de la Mecánica de Materiales para predecir el comportamiento de los materiales fisurados. Las soluciones analíticas de los problemas con este enfoque pueden ser inalcanzables, lo que permite el uso de la modelización numérica, como el método de los elementos finitos. Sin embargo, el uso de software más avanzado que resuelve numéricamente problemas de ingeniería está limitado por su elevado coste. FEniCS es una plataforma computacional de código abierto que resuelve ecuaciones diferenciales parciales por el método de los elementos finitos. Así, a partir de un tutorial para esta plataforma computacional, este trabajo propone reproducir un problema clásico de mecánica de fractura elástica lineal, basado en la validación de una comparación de un problema elástico lineal con el software comercial ANSYS ®. Con la ayuda del tutorial proporcionado, se construyó un código para modelar un ensayo de flexión en tres puntos. Implementado con la ayuda de Gmsh y Paraview, fue posible obtener resultados satisfactorios, y demostrar que FeniCS es una herramienta potente y accesible para resolver problemas de mecánica de fractura

Palaeoenvironmental evolution in the coastal plain of Baixo Ribeira during the shell mounds occupation.

Pollen and diatoms analyses in a peat bog from the Baixo Ribeira do Iguape region (São Paulo State, Brazil) showed expressive changes in the environmental conditions. Brackish waters connected to the sea covered this site before 3.250 years BP; after that a swamp forest developed. Sea presence is due to the marine transgression that culminated at 5.100 years BP. Lowering of sea level has been gradual from 5.100 years BP to the present, without major oscillations. This drastic change in environmental conditions can explain the distribution of the archaeological sites in this region, specially the presence of shell mounds 50 km away from the coast.A análise palinológica e diatomológica do perfil sedimentar de uma turfeira da região do Baixo Ribeira de Iguape (estado de São Paulo, Brasil), mostrou mudanças significativas nas condições ambientais. Antes de 3.250 anos AP a região era recoberta por águas salobras em conexão com o mar, depois ela foi ocupada por uma floresta paludosa. A penetração do mar está relacionada à transgressão marinha que culminou há 5.100 anos AP. A descida do nível do mar foi progressiva de 5.100 anos AP até o presente, sem oscilações notáveis. Esta mudança radical das condições ambientais pode explicar a distribuição geográfica dos sítios arqueológicos da região, em particular a presença de sambaquis a 50 km da costa

Geomorphic markers of Quaternary tectonics in Westernmost Iberia: insights from the Lower Mondego River terraces (central Portugal)

The Lower Mondego Valley (LMV), located in the Western Iberian passive margin which is under compressive tectonic reactivation since ca. 80 Ma, is used for deciphering long-term landscape evolution during the Quaternary and the control played by active tectonics, eustasy and climate. The elaboration of a detailed geomorphological map allowed the establishment of the spatial and temporal distribution of the different geomorphological units and morphogenetic systems operating in the LMV. The culminant unit of the Mondego Cenozoic Basin (allostratigraphic unit UBS13, recording an Atlantic fan-delta and adjacent shallow marine siliciclastic environments) and terrace levels (river and marine) are used as geomorphic markers to quantify fluvial development and tectonic activity. The main stages of evolution are a transition of endorheic to exorheic (Atlantic base level) drainage in the Mondego Cenozoic Basin, ca. 3.7 Ma ago, followed by onset of the fluvial incision stage (valley entrenchment) by ca. 1.8 Ma. Electron spin resonance (ESR) dating is used to improve the chronological framework for the terrace staircases of the LMV and to decipher the response of the river to the regional uplift and other longterm controls (resistance of the substratum to erosion, eustasy and climate). Six river terrace levels (T1, the older, to T6, the younger), inset in the UBS13 and previous to the modern alluvial plain, were characterized and correlated with marine terraces represented at Cape Mondego, near the river mouth. The fluctuating eustatic and climate controls are superimposed on a long-term crustal uplift. The data show marked compartmentalization of fluvial system behaviour with changes in incision rates (acting as a proxy of uplift rates) from east to west, creating distinctly different sectors. Differential uplift is inferred between the valley sides and between the four main reaches in which the LMV is subdivided by major faults. Differential uplift is mainly related to regional fault sets trending N-S to NNW-SSE, NNE-SSW, ENE-WSW, and E-W to WNW-ESE. Using as geomorphic references the topmost deposits of the UBS13 unit and river terraces located above the alluvial plain, average long term incision rates were estimated ranging from 0.03 to 0.16 m/ka, dependin