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1.
2.
We study the mechanical response, and tearing features of crêpe paper, a two-dimensional, very anisotropic material, with one direction much less stiff than the other one. Depending on how the soft direction has been pre-stretched or not, the apparent Young modulus of the material can be varied over a broad range, while its fracture energy remains unaltered. The classical tearing concertina problem shows that a macroscopic measurement (the shape of the teared region) provides a direct access to the fracture properties of the material (effective Young's modulus, and fracture energy). The overall discussion is conducted in the frame of Griffith's theory of fracture. 相似文献
3.
Camille Flament Joël Ribis Jérôme Garnier Thierry Vandenberghe Jean Henry Alexis Deschamps 《哲学杂志》2015,95(8):906-917
The age hardening 6061-T6 aluminium alloy has been chosen as structural material for the core vessel of the material testing Jules Horowitz nuclear reactor. The alloy contains incoherent Al(Cr, Fe, Mn)Si dispersoids whose characterization by energy-filtered transmission electron microscopy (EFTEM) analysis shows a core/shell organization tendency where the core is (Mn, Fe) rich, and the shell is Cr rich. The present work studies the stability of this organization under irradiation. TEM characterization on the same particles, before and after 1 MeV electron irradiation, reveals that the core/shell organization is enhanced after irradiation. It is proposed that the high level of point defects, created by irradiation, ensures a radiation-enhanced diffusion process favourable to the unmixing forces between (Fe, Mn) and Cr. Shell formation may result in the low-energy interface segregation of Cr atoms within the (Fe, Mn) system combined with the unmixing of Cr, Fe and Mn components. 相似文献
4.
I. Nedkov L. Slavov T. Merodiiska P. Lukanov Ph. Tailhades M. Gougeon R. E. Vandenberghe 《Journal of nanoparticle research》2008,10(5):877-880
Ferrofluids based on two types of hybrid particles Fe3O4/β-cyclodextrin were prepared: Using monodomain (below 60 nm) magnetite nanoparticles with (A) non-superparamagnetic (non-SPM)
behaviour and (B) with superparamagnetic (SPM) behaviour. We found a strong dependence of the hybrid particles’ magnetic properties
on their size and homogeneity. In both types of ferrofluids we observed hyperthermia upon applying an ac electromagnetic field
with frequency 40 kHz and amplitude 30 kA/m. The maximal ΔТ upon irradiation with duration of about 12 min for the non-SPM particles was 12 °C, while for the SPM ones it was 3.5 °C. 相似文献
5.
By immersing a compliant yet self-supporting sheet into flowing water, we study a heavy, streamlined, and elastic body interacting with a fluid. We find that above a critical flow velocity a sheet aligned with the flow begins to flap with a Strouhal frequency consistent with animal locomotion. This transition is subcritical. Our results agree qualitatively with a simple fluid dynamical model that predicts linear instability at a critical flow speed. Both experiment and theory emphasize the importance of body inertia in overcoming the stabilizing effects of finite rigidity and fluid drag. 相似文献
6.
Several samples of hematite, one a natural specimen, are considered in order to study the specific effect of the morphology on the magnetic structure and especially on the Morin transition. It seemed that mainly the weak-ferromagnetic contribution is affected by the morphology, as well as the transition temperature and region. 相似文献
7.
F. De Corte M. Dejaeger S. M. Hossain D. Vandenberghe A. De Wispelaere P. Van den Haute 《Journal of Radioanalytical and Nuclear Chemistry》2005,263(3):659-663
Summary Recently, in our laboratory an intercomparison was made of methods for the annual radiation dose determination (assessed from direct radiation counting and/or from the measurement of the K, Th and U contents) applied to luminescence dating of loess and sand sediment, whereby the emphasis was put on their precision and accuracy. Although these properties are important, the duration of the measurement is also a practically relevant aspect. Indeed, direct alpha, beta and gamma-counting can last a week or more, and the determination of K, Th and U via NAA can take up to three weeks to enable proper gamma-ray spectrometry of the long-lived 233 Th/233Pa. Therefore, in the present work the performance of k0-based epiCd-NAA (ENAA, with irradiation under a cadmium cover) when applied to sediments is compared to k0-NAA. As concluded, with the use of k0-ENAA the analysis turnaround time could be considerably reduced from ~3 weeks to ~ 2.5days, while maintaining satisfactory accuracy, precision and determination sensitivity. 相似文献
8.
9.
R. M. Persoons E. De Grave P. M. A. De Bakker R. E. Vandenberghe H. H. A. Smit 《Hyperfine Interactions》1990,54(1-4):661-666
Spectra for three members of the spinel system Mg1+t
Fe2(1−t)Ti
t
O4, witht=0.5, 0.6 and 0.7, all showing re-entrant spin-glass-like behavior, were collected at temperatures down to 1.6 K and decomposed
in A- and B-site components, both having a broad distribution of hyperfine fields. The numerical results suggest a more pronounced
spin canting on A sites as compared to B sites. From spectra recorded at 4.2 K in an applied field of 6 T, and analysed with
a sum of two bi-dimensional distributions of hyperfine fields and canting angles, the existence of reversed A-site spins is
evidenced. The number of such spins increases with increasing magnetic dilution.
Senior Research Associate at the National Fund for Scientific Research, Belgium 相似文献
10.
L. H. Bowen E. De Grave P. M. A. De Bakker R. E. Vandenberghe 《Hyperfine Interactions》1990,54(1-4):467-472
Six goethite samples α(Fe, Al)OOH prepared by a similar synthetic method but varying in Al substitution from 0 to 31 mole percent, have been examined by Mössbauer spectroscopy at ≌ 4 K in an external field of 6 T. The resulting spectra have been fitted by two methods: first a simplified model consisting of three distributions of magnetic fields (parallel, perpendicular and antiparallel orientations of internal and external field) and second, a model-independent bi-dimensional distribution of both the internal hyperfine field and the orientation angle ? with the external field. Both fitting methods show that the angular distribution of spins is not random in the case of high Al substitution, but canted towards an antiparallel orientation (?>90°). 相似文献