Experimental determination of the permeability of engineering textiles: Benchmark II

In this second international permeability benchmark, the in-plane permeability values of a carbon fabric were studied by twelve research groups worldwide. One participant also investigated the deformation of the tested carbon fabric. The aim of this work was to obtain comparable results in order to make a step toward standardization of permeability measurements. Unidirectional injections were thus conducted to determine the unsaturated in-plane permeability tensor of the fabric. Procedures used by participants were specified in the guidelines defined for this benchmark. Participants were asked to use the same values for parameters such as fiber volume fraction, injection pressure and fluid viscosity to minimize sources of scatter. The comparison of the results from each participant was encouraging. The scatter between data obtained while respecting the guidelines was below 25%. However, a higher dispersion was observed when some parameters differed from the recommendations of this exercise.The authors are grateful to J.M. Beraud from Hexcel Fabrics for his support that made possible this exercise. The contributions of J.B. Alms, N.C. Correia, S. Advani, E. Ruiz and P.C.T. Goncalves to the preparation of the guidelines document and templates are acknowledged by the participants of this benchmark.Vernet, N.; Ruiz, E.; Advani, S.; Alms, JB.; Aubert, M.; Barburski, M.; Barari, B.... (2014). Experimental determination of the permeability of engineering textiles: Benchmark II. Composites Part A: Applied Science and Manufacturing. 61:172-184. doi:10.1016/j.compositesa.2014.02.010S1721846

Long-term growth rates of four Mediterranean cold-water coral species maintained in aquaria

Growth rates of the cold-water corals (CWC) Madrepora oculata, Lophelia pertusa, Desmophyllum dianthus and Dendrophyllia cornigera were measured over 8 mo under controlled conditions (12°C in the dark, fed 5 times a week) by means of the buoyant weight technique. Additionally, linear growth rates were measured in M. oculata and L. pertusa for 2 and 1 yr, respectively. The weight measurements revealed growth rates, expressed as percent growth per day (mean ± SD), of 0.11 ± 0.04 for M. oculata, 0.02 ± 0.01 for L. pertusa, 0.06 ± 0.03 for D. dianthus and 0.04 ± 0.02 % d–1 for D. cornigera. Growth in M. oculata was significantly higher (p < 0.0001) than in the other 3 CWC species. For M. oculata and L. pertusa, also linear growth was recorded. These values (mean ± SD) were 0.014 ± 0.007 and 0.024 ± 0.018 mm d–1 for M. oculata and L. pertusa, respectively. This is the first study that compares the growth rates of 4 different CWC species under the same experimental conditions of water flow, temperature, salinity and food supply. These corals have different growth rates, both in terms of total weight increase and linear increase, and these growth rates can be related to interspecific physiological differences. Data on growth rates are essential to understand the population dynamics of CWC as well as the recovery capacity of these communities after disturbancePublicado

Isomeric decay of 67^{67}Fe - Evidence for deformation

Decay-spectroscopy study of the $^{\rm 67m}$Fe isomer has been performed at GANIL. This isomer is found to have an energy of 387 keV and a half-life of 75(21) $\mu$s. An intermediate excited state is introduced at 367 keV. The results are interpreted in terms of various nuclear models, and a deformed shape is inferred for $^{67}$Fe