The Search for Supernova-produced Radionuclides in Terrestrial Deep-sea Archives

An enhanced concentration of 60Fe was found in a deep ocean's crust in 2004 in a layer corresponding to an age of ~2 Myr. The confirmation of this signal in terrestrial archives as supernova-induced and detection of other supernova-produced radionuclides is of great interest. We have identified two suitable marine sediment cores from the South Australian Basin and estimated the intensity of a possible signal of the supernova-produced radionuclides 26Al, 53Mn, 60Fe and the pure r-process element 244Pu in these cores. A finding of these radionuclides in a sediment core might allow to improve the time resolution of the signal and thus to link the signal to a supernova event in the solar vicinity ~2 Myr ago. Furthermore, it gives an insight on nucleosynthesis scenarios in massive stars, the condensation into dust grains and transport mechanisms from the supernova shell into the solar system

Search for supernova-produced 60Fe in a marine sediment

An 60Fe peak in a deep-sea FeMn crust has been interpreted as due to the signature left by the ejecta of a supernova explosion close to the solar system 2.8 +/- 0.4 Myr ago [Knie et al., Phys. Rev. Lett. 93, 171103 (2004)]. To confirm this interpretation with better time resolution and obtain a more direct flux estimate, we measured 60Fe concentrations along a dated marine sediment. We find no 60Fe peak at the expected level from 1.7 to 3.2 Myr ago. However, applying the same chemistry used for the sediment, we confirm the 60Fe signal in the FeMn crust. The cause of the discrepancy is discussed.Comment: 15 pages, 5 figures, submitted to PR

The political economy of the Jospin government

This article explores the political economy of the French Socialist Party (PS), beginning with the neo-liberal U-turn of 1983. It then charts the re-evaluation of the PS's political economic foundations after the 1993 defeat, the rejection of the neo-liberal 'pensée unique', and the rehabilitation of a broadly Keynesian frame of reference. The article goes on to explore how this shift has fed through into the Jospin government's policy and positions at both the national and international level. It explores aspirations to reinvent the EU as a Keynesian social democratic 'policy space', and at the national level, employment, macroeconomic, and structural policies

Coupled effect of loading frequency and amplitude on the fatigue behavior of advanced sheet molding compound (A-SMC)

This paper presents the experimental results of tension-tension stress-controlled fatigue tests performed on advanced sheet molding compound (A-SMC). It aims at analyzing the effect of fiber orientation, loading amplitude, and frequency on the fatigue response and the related temperature evolution due to the self-heating phenomenon. Two types of A-SMC have been analyzed: randomly oriented (RO) and highly oriented (HO). The coupled effect of the loading amplitude and the frequency has been studied. It has been shown that the couple frequency-amplitude affects the nature of the fatigue overall response which can be governed by the damage mechanisms accumulation (mechanical fatigue) and/or by the self-heating (induced thermal fatigue). For fatigue loading at 100 Hz, self-heating has been observed and yielded to a temperature rise up to 70 C. The latter causes a decrease of the storage modulus related to the b-transition of the vinylester. It has been demonstrated that the self-heating produced a material softening and decreased the fatigue life. SEM observations revealed that the samples tested at 100 Hz, exhibit smooth debonding surfaces due to the induced thermal softening of the matrix whereas more brittle fracture of the matrix surrounding fibers is observed during the fatigue tests achieved at 10 Hz

Sheet Molding Compound Automotive Component Reliability Using a Micromechanical Damage Approach

The mastering of product reliability is essential for industrial competitiveness. If for metallic materials the topic is well-known, especially in automotive industry, Original Equipment Manufacturers are expecting strong support of their suppliers to full-fill the lack data. This paper presents a new original approach, using a micromechanical based on damage model to address the problem of reliability of Sheet Molding Compound (SMC) components. The first part demonstrates the inadequacy of the standard method of reliability on SMC material through its application on the new Peugeot 3008. In fact, the very flat S-N curve of SMC, and in general, composite materials is not appropriate for acceleration effect. The proposed model correlates the stress, damage and strength with both cycle number and slamming velocity. It emphasizes the relation between the effective distribution with the slamming velocity effect. Then, a new reliability approach based on a micromechanical fatigue/damage model was developed. The definition of new probability distributions based on damage was necessary to apply properly the stress-resistance approach. It allows taking into account the velocity effect by switching in damage space. Finally, applying this new methodology on the Peugeot 3008, leads to the definition of the optimal validation laboratory tests to ensure the reliability. Indeed, the required number of cycles to ensure reliability has been reduced significantly. Micromechanical damage reliability approach could be an efficient way to ensure the reliability of short fiber reinforcement composite components used in industrial context.Authors address a strong acknowledgment to E. FEIGE and Y. HAMOY, from PSA, for the data provided. Their comments and advices were also very useful.We are grateful to Mr. OZOUF for teaching and advices on the general topic of reliability

Rotational Molding of Polyamide-12 Nanocomposites: Modeling of the Viscoelastic Behavior

Nowadays, polyamide 12 (PA-12) is considered as an interesting polymer in the rotomolding process to manufacture different pieces like the liner part in the storage hydrogen tank (type IV). In this study, the pure polyamide-12 and PA12 pieces, incorporated with 0.5%, 1% and 3% wt Nano Carbon Black (NCB), were manufactured by the rotomolding process. Different rotomolding parameters such as heating temperature, time of heating, and cooling rate have been optimized to obtain the ideal piece. The effect of volume fraction of NCB in terms of physicochemical and mechanical properties has been studied. Afterward, the optimal volume fraction of NCB is revealed using different characterization methods. The tensile results specified the addition of NCBs until 0.5% improved the tensile behavior. The addition of NCBs more than 0.5% decreases the mechanical properties in terms of failure stress and strain, while it has no significant effect on the elastic modulus of PA-12. The bi-parabolic the Perez model has been used to study the viscoelastic behavior of PA-12 using the Cole-Cole method. The constants of the Perez model indicate a good correlation between viscoelastic experimental results and the model used

Fast fatigue life prediction of short fiber reinforced composites using a new hybrid damage approach: Application to SMC

Industrial design of Short Fiber Reinforced Composites (SFRC) structures is subject to several compounding and processing steps of optimization. Moreover, these structures are often submitted to fatigue loading. Therefore, SN curves have to be established for each new composite formulation and for several type of microstructure involved in the real component due to processing. While these preliminary characterizations are time and money consuming, this paper propose a new hybrid methodology for fast fatigue life prediction. Moreover, both monotonic and fatigue behavior of SMC composites is essentially determined by local damage propagation. Therefore, the key idea of the proposed approach is to use a Mori and Tanaka based micromechanical model in order to establish an equation of state relating local damage rate to macroscopic residual stiffness rate. The generalization of this relation to fatigue damage multi-scale description leads to the SN curve fast determination of each considered microstructure. Very limited experimental characterization is required in such a way that SN curve could be established in just one day. Comparison between experimental and simulated Whöler curves highlights a very good agreement for several microstructure configurations in the case of a SMC composite material

Multi‐scale analysis of short glass fiber‐reinforced polypropylene under monotonic and fatigue loading

Short fiber-reinforced polypropylene is largely used in the automotive industry. Fatigue failure is one of the most failure modes observed in this class of materials. In order to better understand the damage mechanisms and plasticity evolution, this article provides an overall experimental investigation of the mechanical properties of a PPGF40 composite (polypropylene matrix reinforced by a 40% weight content of short glass fibers) including monotonic and cyclic loading. The effect of various parameters such as the loading direction, the strain rate, the temperature, and the fatigue are analyzed. The evolutions of the loss of stiffness and plastic strain during monotonic and fatigue tests are analyzed. Self-heating during cyclic loading is also studied. Moreover, the coupling effect of damage and plasticity is analyzed by plotting the evolution of the relative loss of stiffness vs the plastic strain increment for monotonic and cyclic loadings. For quasi-static loading, the results emphasize an intrinsic curve independent of the loading direction. Moreover, a sharp increase in the damage and plasticity levels due to the local effect occurring during cyclic loading is observed and correlated to SEM fracture surface analysis.This work is carried out as part of a Phd thesis ( CIFRE number 2016/1520) in collaboration between Arts et Metiers Institute of Technologie and Flex N gate Exteriors Europe

Pupillary Responses to Static Images of Men and Women: A Possible Measure of Sexual Interest?

The pupil dilates to images that are arousing. In Experiment 1, we examined if the pupil’s response to brief presentations (2,000 ms) of static images could be used to identify individuals’ sexual orientation. Participants were grouped according to their self-reported gender and sexual orientation (male heterosexual, N = 20; male bisexual, N = 13; male homosexual, N = 19; female heterosexual, N = 28; female bisexual, N = 21; female homosexual, N = 17). Pupil size was monitored to images of men in seminude poses, women in seminude poses, or neutral images. Every group showed the same pattern of responses, with the greatest dilation to male images, then female images, and least dilation to the neutral images. Experiment 2 used more tightly controlled stimuli and tested at two different image durations (150 and 3,000 ms). Both heterosexual men (N = 18) and women (N = 20) showed greater pupil dilation to images of nude men than to nude women. However, in Experiment 3, where we reduced the erotic content by using images of clothed models, both heterosexual men and women showed greater pupil dilation to images of women. The results showed that while the pupil does dilate strongly to sexual imagery, its response to these brief static images does not correspond to a person’s sexual orientation in a simple manne