Registry of all events from the Tara Oceans Expedition (2009-2013)

The Tara Oceans Expedition (2009-2013) sampled the world oceans on board a 36 m long schooner, collecting environmental data and organisms from viruses to planktonic metazoans for later analyses using modern sequencing and state-of-the-art imaging technologies. Tara Oceans Data are particularly suited to study the genetic, morphological and functional diversity of plankton. The present data set is a registry of all events conducted during the Tara Oceans Expedition (2009-2013). The registry provides details about the sampling date, time, location and methodology of each event. Uniform resource locators (URLs) offer direct links to the corresponding (1) event logsheet filled on board, (2) environmental data published at PANGAEA, (3) list of samples prepared on board from each event, and (4) nucleotides data published at the European Nucleotides Archive (EBI-ENA).

Puncture wounds by driftwood catfish during bucket baths: Local habits of riverside people and fish natural history in the Amazon

Objective. - To assess the prevalence of stings by small spiny driftwood catfish (carataí) of the genus Centromochlus (Auchenipteridae) accidentally caught in buckets during bucket bathing by riverside people along the Brazilian Amazon and to determine the probability of catching specimens of these fish during random throws of a bucket into the river. Methods. - We interviewed 27 adult residents living at the confluence of the Negro and Solimões rivers in Brazil regarding whether or not they had ever been stung by driftwood catfish while bucket bathing. To assess the likelihood of catching catfish in bathing buckets, we randomly threw a typical plastic bucket used for bathing in 4 series of 10 throws into the river at dusk or night around a floating house. Results. - Seventeen of the 27 subjects (63%) reported being injured by driftwood catfish during bucket bathing. Three individuals (17.6%) had been injured 2 to 3 times, totaling 23 puncture accidents. All stings occurred at dusk or early night. In the 4 series of 10 bucket throws, we caught 3 driftwood catfish (in 1 series we did not catch any fish). Thus, the chance of catching a driftwood catfish in a single bucket throw at dusk was slightly less than 10%. Conclusions. - The prevalence of stings by driftwood catfish to people bucket bathing in this section of the Brazilian Amazon is high, partly because of the relatively high chances of catching these small catfish during random throws of a bathing bucket into the river.

Analysis of the tip roundness effects on the micro- and macroindentation response of elastic-plastic materials

In this work, the effects of indenter tip roundness oil the load-depth indentation curves were analyzed using finite element modeling. The tip roundness level was Studied based on the ratio between tip radius and maximum penetration depth (R/h(max)), which varied from 0.02 to 1. The proportional Curvature constant (C), the exponent of depth during loading (alpha), the initial unloading slope (S), the correction factor (beta), the level of piling-up or sinking-in (h(c)/h(max)), and the ratio h(max)/h(f) are shown to be strongly influenced by the ratio R/h(max). The hardness (H) was found to be independent of R/h(max) in the range studied. The Oliver and Pharr method was successful in following the variation of h(c)/h(max) with the ratio R/h(max) through the variation of S with the ratio R/h(max). However, this work confirmed the differences between the hardness values calculated using the Oliver-Pharr method and those obtained directly from finite element calculations; differences which derive from the error in area calculation that Occurs when given combinations of indented material properties are present. The ratio of plastic work to total work (W(p)/W(t)) was found to be independent of the ratio R/h(max), which demonstrates that the methods for the Calculation of mechanical properties based on the *indentation energy are potentially not Susceptible to errors caused by tip roundness.

Analysis of the effects of conical indentation variables on the indentation response of elastic-plastic materials through factorial design of experiment

In this work, the effects of conical indentation variables on the load-depth indentation curves were analyzed using finite element modeling and dimensional analysis. A factorial design 2(6) was used with the aim of quantifying the effects of the mechanical properties of the indented material and of the indenter geometry. Analysis was based on the input variables Y/E, R/h(max), n, theta, E, and h(max). The dimensional variables E and h(max) were used such that each value of dimensionless Y/E was obtained with two different values of E and each value of dimensionless R/h(max) was obtained with two different h(max) values. A set of dimensionless functions was defined to analyze the effect of the input variables: Pi(1) = P(1)/Eh(2), Pi(2) = h(c)/h, Pi(3) = H/Y, Pi(4) = S/Eh(max), Pi(6) = h(max)/h(f) and Pi(7) = W(P)/W(T). These six functions were found to depend only on the dimensionless variables studied (Y/E, R/h(max), n, theta). Another dimension less function, Pi(5) = beta, was not well defined for most of the dimensionless variables and the only variable that provided a significant effect on beta was theta. However, beta showed a strong dependence on the fraction of the data selected to fit the unloading curve, which means that beta is especially Susceptible to the error in the Calculation of the initial unloading slope.

Evolution of magnetic properties and crystallographic texture in electrical steel with large plastic deformation

Deformation leads to a hardening of steel due to an increase in the density of dislocations and a reduction in their mobility, giving rise to a state of elevated residual stresses in the crystal lattice. In the microstructure, one observes an increase in the contribution of crystalline orientations which are unfavorable to the magnetization, as seen, for example, by a decrease in B(50), the magnetic flux density at a field of 50 A/cm. The present study was carried out with longitudinal strips of fully processed non-oriented (NO) electrical steel, with deformations up to 70% resulting from cold rolling in the longitudinal direction. With increasing plastic deformation, the value of B(50) gradually decreases until it reaches a minimum value, where it remains even for larger deformations. On the other hand, the coercive field H(c) continually increases. Magnetometry results and electron backscatter diffraction results are compared and discussed. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3560895]

A discussion on volume change in the plastic phase

This technical note discusses the possibility of using a more simplified scheme to estimate the plastic multiplier when some material shows volume changes, e.g. soil, balsa wood foam and other similar materials. Two procedures regarding volume changes during the plastic phase are discussed here. The first one is the classic procedure applied to non-associative plasticity, for which a Drucker-Prager-like surface is adopted to represent the plastic potential. For the second procedure, the plastic potential is not explicitly known, however, its orthogonal direction is chosen respecting a plastic volume change parameter similar to Poisson`s ratio. Copyright (C) 2007 John Wiley & Sons, Ltd.

Consolidation of elastic-plastic saturated porous media by the boundary element method

This paper presents a domain boundary element formulation for inelastic saturated porous media with rate-independent behavior for the solid skeleton. The formulation is then applied to elastic-plastic behavior for the solid. Biot`s consolidation theory, extended to include irreversible phenomena is considered and the direct boundary element technique is used for the numerical solution after time discretization by the implicit Euler backward algorithm. The associated nonlinear algebraic problem is solved by the Newton-Raphson procedure whereby the loading/unloading conditions are fully taken into account and the consistent tangent operator defined. Only domain nodes (nodes defined inside the domain) are used to represent all domain values and the corresponding integrals are computed by using an accurate sub-elementation scheme. The developments are illustrated through the Drucker-Prager elastic-plastic model for the solid skeleton and various examples are analyzed with the proposed algorithms. (c) 2008 Elsevier B.V. All rights reserved.

Characterization of the elastic-plastic region in AISI/SAE 1070 steel by the magnetic barkhausen noise

The magnetic Barkhausen energy in the rolling and transversal directions of AISI/SAE 1070 annealed surfaces is studied. The measurements were made in the samples under applied tension in the elastic-plastic region for different angular directions. The outcomes evidence that the magnetic anisotropy coefficient can be used to characterize the linear and nonlinear elastic limits of the material tinder tensile tresses. The results also show that the area of the curve corresponding to the angular dependence of the number of Barkhausen jumps with average energy presents a maximum value that corresponds to the elastic limit of the sample. (C) 2008 Elsevier Ltd. All rights reserved.

Nondestructive inspection of plastic deformation in commercial carbon steels using magnetic Barkhausen noise

The present work shows measurements of the Magnetic Barkhausen Noise (MBN) in commercial AISI/SAE 1045 and ASTM 36 steel deformed samples. The correlation between the MBN root mean square, Barkhausen signal profile and MBN power spectrum with the plastic deformation is established. The results show that the power spectral density of the Barkhausen signal is more effective as nondestructive evaluator than root mean square of Barkhausen signal. The Outcomes also suggest the presence of unbalanced tensions between the surface and the bulk of sample due to the presence of plastic deformation.

A study of plastic deformation around a defect using the magnetic Barkhausen noise in ASTM 36 steel

The present work presents the measurements of the magnetic Barkhausen noise (MBN) in ASTM 36 steel samples around a pit under plastic deformation. The contour maps obtained from these Barkhausen noise measurements are compared with the finite element analysis of the ideal plastic deformation. Also, a parameter of the Barkhausen signal to detect the plastic deformation around the pit in ASTM 36 steel is obtained. Additionally to that, we propose another MBN parameter to estimate the pit width using the Barkhausen noise. (c) 2007 Elsevier Ltd. All rights reserved.

A numerical investigation on the visco-plastic response of structures to different pulse loading shapes

The time varying intensity character of a load applied to a structure poses many difficulties in analysis. A remedy to this situation is to substitute a complex pulse shape by a rectangular equivalent one. It has been shown by others that this procedure works well for perfectly plastic elementary structures. This paper applies the concept of equivalent pulse to more complex structures. Special attention is given to the material behavior, which is allowed to be strain rate and strain hardening sensitive. Thanks to the explicit finite element solution, it is shown in this article that blast loads applied to complex structures made of real materials can be substituted by equivalent rectangular loads with both responses being practically the same. (c) 2007 Elsevier Ltd. All rights reserved.

Modeling of Plastic Deformation Effects in Ferromagnetic Thin Films

To explain the magnetic behavior of plastic deformation of thin magnetic films (Fe and permalloy) on an elastic substrate (nitinol), it is noted that unlike in the bulk, the dislocation density does not increase dramatically because of the dimensional constraint. As a result, the resulting residual stress, even though strain hardening is limited, dominates the observed magnetic behavior. Thus, with the field parallel to the stress axis, the compressive residual stress resulting from plastic deformation causes a decrease in remanence and an increase in coercivity; and with the field perpendicular to the stress axis, the resulting compressive residual stress causes an increase in remanence and a decrease in coercivity. These elements have been inserted into the model previously developed for plastic deformation in the bulk, producing the aforementioned behavior, which has been observed experimentally in the films.

Impact of plastic deformation on magnetoacoustic properties of Fe-2%Si alloy

The paper presents the results of a complementary study including magnetic hysteresis loops B(H), magnetic Barkhausen noise (MBN) and magnetoacoustic emission (MAE) signals measurements for plastically deformed Fe-2%Si samples. The investigated samples had been plastically deformed with plastic strain level (epsilon(p)) up to 8%. The properties of B(H) loops are quantified using the coercivity H(C) and maximum differential permeability mu(rmax) as parameters. The MBN and MAE voltage signals were analysed by means of rms-like voltage (Ub and Ua, respectively) envelopes, plotted as a function of applied field strength. Integrals of the Ub and Ua voltages over half of a period of magnetization were then calculated. It has been found that He and integrals of Ub increase, while mu(rmax) decreases monotonically with increasing epsilon(p). The MAE (Ua) peak voltage at first decreases, then peaks at epsilon(p) approximate to 1.5% and finally decreases again. The integral of the Ua voltage at first increases for low epsilon(p) and then decreases for epsilon(p) > 1.5%. All those various dependence types suggest the possibility of detection of various stages of microstructure change. The above-mentioned results are discussed qualitatively in the paper. Some modelling of the discussed dependency is also presented. (C) 2008 Elsevier Ltd. All rights reserved.

Modeling of Effect of Plastic Deformation on Barkhausen Noise and Magnetoacoustic Emission in Iron With 2% Silicon

Before one models the effect of plastic deformation on magnetoacoustic emission (MAE), one must first treat non-180 degrees domain wall motion. In this paper, we take the Alessandro-Beatrice-Bertotti-Montorsi (ABBM) model and modify it to treat non-180 degrees wall motion. We then insert a modified stress-dependent Jiles-Atherton model, which treats plastic deformation, into the modified ABBM model to treat MAE and magnetic Barkhausen noise (HBN). In fitting the dependence of these quantities on plastic deformation, we apply a model for when deformation gets into the stage where dislocation tangles are formed, noting two chief effects, one due to increased density of emission centers owing to increased dislocation density, and the other due to a more gentle increase in the residual stress in the vicinity of the dislocation tangles as deformation is increased.