Using finite element modelling to examine the flow process and temperature evolution in HPT under different constraining conditions

High-pressure torsion (HPT) is a metal-working technique used to impose severe plastic deformation into disc-shaped samples under high hydrostatic pressures. Different HPT facilities have been developed and they may be divided into three distinct categories depending upon the configuration of the anvils and the restriction imposed on the lateral flow of the samples. In the present paper, finite element simulations were performed to compare the flow process, temperature, strain and hydrostatic stress distributions under unconstrained, quasi-constrained and constrained conditions. It is shown there are distinct strain distributions in the samples depending on the facility configurations and a similar trend in the temperature rise of the HPT workpiece

A Comparison between Dual Phase Steel and Interstitial Free Steel Due To the Springback Effect

International audienceThis is a study of the springback effect on two kinds of high strength steel, which are: dualphase and interstitial free, currently used as feedstock in the production of vehicles. The mechanical characterization of the springback effect was performed by means of a mechanical conformation test, called three-point air bending, performed by adapting it to the unconstrained cylindrical bending test. It was also evaluated the mechanical properties of the material defined by the tensile test in order to determine its tensile strength, yield strength, and elongation. Furthermore, it was performed a microstructural characterization of advanced steels by identifying and quantifying the present phases in coexistence by means of digital image processing. The results indicate that the springback effect in the dual-phase steel has the highest springback rates due to its high mechanical strength, and it causes a decrease in the aspect ratio of the grains that suffered mechanical conformation attempting to return it to its original form. On the other hand, the springback effect has the lowest rates, and the change in aspect ratio depends only on the interstitial free steel elongation capacity due to its lower mechanical strength

Characterisation of a developmentally regulated amino acid transporter gene from Leishmania amazonensis

The metabolism of protozoan parasites of the Leishmania genus is strongly based on amino acid consumption, but little is known about amino acid uptake in these organisms. In the present work, we identified a Leishmania amazonensis gene (La-PAT1) encoding a putative amino acid transporter that belongs to the amino acid/auxin permease family, a group of H +/amino acid symporters. This single copy gene is upregulated in amastigotes, the life cycle stage found in the mammalian host. La-PAT1 putative orthologous sequences were identified in Leishmania infantum, Leishmania donovani, Leishmania major and Trypanosoma.Fil: Geraldo, Murilo V.. Universidade de Sao Paulo; BrasilFil: Silber, Ariel Mariano. Universidade de Sao Paulo; BrasilFil: Pereira, Claudio Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Médicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Médicas; ArgentinaFil: Uliana, Silvia R.B.. Universidade de Sao Paulo; Brasi

KPI development and obsolescence management in industrial maintenance

Since the industrialization of the mid-19th century, the role of maintenance has become increasingly important as time moved on. Proactive maintenance has gained a crucial role, even though a lot of organizations still view it as an expense and not an investment. This paper highlights the role of KPIs and obsolescence management in maintenance operations. The first step was to create a new KPI to assess the work done in maintenance, relating it to the work done in production. Although the ISO 15341:2007 maps out certain KPIs, the creation of a new one was necessary. The result was a two phases KPI, in which its values are matched to a decision matrix that gives a qualitative evaluation of the performed work. The second step was to create a decision-making tool to evaluate the obsolescence of electronic components and choose the mitigation approach. The IEC 62402:2007 shows some terminology and some conditions to check for obsolescence, but does not point out whether a proactive or a reactive approach should be used. Like the KPI developed, it is also composed of a two-phase process. The first phase helps to see which components are at a higher risk to become obsolescent, while the second phase evaluates the repercussions to mitigate its obsolescence. The values obtained are also connected to a decision matrix to decide whether the approach for its mitigation should be proactive or reactive. The novel KPI and obsolescence approach were successfully tested in practice in a dairy processing factory, showing perfectly fulfil the goals initially set.info:eu-repo/semantics/publishedVersio

Pressões De Contato E O Impacto De Conjuntos Motomecanizados Em Latossolo Com Presença E Ausência De Palhada De Cana-de-açúcar

High contact pressures applied to soil result in a greater degree of compaction, in addition to promoting other negative effects. The objective of this study was to quantify contact areas by using different methodologies, and pressures of farm equipment employed in production activity and evaluate structural changes caused in a Red Latosol with the presence and absence of straw cover. The design was completely randomized in a factorial scheme of type 4 (tire on front axle, tire on rear axle, tire on a sugarcane wagon and metallic track of sugar cane Harvester) x 2 (presence and absence of straw). The contact area (CA) of the run was obtained by three procedures: analytical measure of the area of an ellipse (CA1); digital measurement of area of an ellipse (CA2); and measurement of real contact area (RCA), with digital resources. The contact pressure was calculated from the ratio of mass of each machine’s axle and the contact area of the run. The contact area obtained according to the procedure of the ellipse (CA1 and CA2) is overrated when compared to actual area obtained digitally (RCA). The straw reduces the contact pressure in the soil, due to the deep tire treads and consequently, increased contact area. Areas where the traffic of the machines occurred with soil covered with the presence of straw showed reduced soil resistance to penetration, cone index and pre-consolidation pressure, confirming that the increased contact area produced by straw reduced the pressure applied and the compression power dissipated in the soil. © 2016, Federal University of Lavras. All rights reserved.40326527

Expanding and Collapsing Scalar Field Thin Shell

This paper deals with the dynamics of scalar field thin shell in the Reissner-Nordstr$\ddot{o}$m geometry. The Israel junction conditions between Reissner-Nordstr$\ddot{o}$m spacetimes are derived, which lead to the equation of motion of scalar field shell and Klien-Gordon equation. These equations are solved numerically by taking scalar field model with the quadratic scalar potential. It is found that solution represents the expanding and collapsing scalar field shell. For the better understanding of this problem, we investigate the case of massless scalar field (by taking the scalar field potential zero). Also, we evaluate the scalar field potential when $p$ is an explicit function of $R$. We conclude that both massless as well as massive scalar field shell can expand to infinity at constant rate or collapse to zero size forming a curvature singularity or bounce under suitable conditions.Comment: 15 pages, 11 figure

Quantifying the levitation picture of extended states in lattice models

The behavior of extended states is quantitatively analyzed for two dimensional lattice models. A levitation picture is established for both white-noise and correlated disorder potentials. In a continuum limit window of the lattice models we find simple quantitative expressions for the extended states levitation, suggesting an underlying universal behavior. On the other hand, these results point out that the Quantum Hall phase diagrams may be disorder dependent.Comment: 5 pages, submitted to PR

Levitation of quantum Hall critical states in a lattice model with spatially correlated disorder

The fate of the current carrying states of a quantum Hall system is considered in the situation when the disorder strength is increased and the transition from the quantum Hall liquid to the Hall insulator takes place. We investigate a two-dimensional lattice model with spatially correlated disorder potentials and calculate the density of states and the localization length either by using a recursive Green function method or by direct diagonalization in connection with the procedure of level statistics. From the knowledge of the energy and disorder dependence of the localization length and the density of states (DOS) of the corresponding Landau bands, the movement of the current carrying states in the disorder--energy and disorder--filling-factor plane can be traced by tuning the disorder strength. We show results for all sub-bands, particularly the traces of the Chern and anti-Chern states as well as the peak positions of the DOS. For small disorder strength $W$ we recover the well known weak levitation of the critical states, but we also reveal, for larger $W$, the strong levitation of these states across the Landau gaps without merging. We find the behavior to be similar for exponentially, Gaussian, and Lorentzian correlated disorder potentials. Our study resolves the discrepancies of previously published work in demonstrating the conflicting results to be only special cases of a general lattice model with spatially correlated disorder potentials. To test whether the mixing between consecutive Landau bands is the origin of the observed floating, we truncate the Hilbert space of our model Hamiltonian and calculate the behavior of the current carrying states under these restricted conditions.Comment: 10 pages, incl. 13 figures, accepted for publication in PR