Analysis of crack propagation as an energy absorption mechanism in metal matrix composites

The crack initiation and crack propagation capability was extended to the previously developed generalized plane strain, finite element micromechanics analysis. Also, an axisymmetric analysis was developed, which contains all of the general features of the plane analysis, including elastoplastic material behavior, temperature-dependent material properties, and crack propagation. These analyses were used to generate various example problems demonstrating the inelastic response of, and crack initiation and propagation in, a boron/aluminum composite

The XRF080109-SN2008D and a decade of GRB-Jet-SN connection

Last and nearest GRB-XRF 080109 has been an exceptional lesson on GRB nature. After a decade (since 25 April 08) we know that Supernovae may often contain a Jet. Its persistent activity may shine on axis as a GRBs. Such a persistent, thin beamed gamma jet may be powered by either a BH (Black Holes) or Pulsars. Late stages of these jets may loose the SN traces and appear as a short GRB or a long orphan GRB (depending on jet angular velocity and view angle). XRF are peripherical viewing of the jets. These precessing and spinning gamma jet are originated by Inverse Compton and-or Synchrotron Radiation at pulsars or micro-quasars sources, by ultra-relativistic electrons. These Jets are most powerful at Supernova birth, blazing, once on axis, to us and flashing GRB detector. The trembling of the thin jet explains naturally the observed erratic multi-explosive structure of different GRBs. The jets are precessing (by binary companion or inner disk asymmetry) and decaying by power on time scales of few hours, but they keep staying inside the observer cone view only a few seconds duration times (GRB); the jet is thinner in gamma and wider in X band. This explain the wider and longer X GRB afterglow duration and the rare presence of X-ray precursors.Comment: 11 pages, 12 figure

Energy absorption mechanisms during crack propagation in metal matrix composites

The stress distributions around individual fibers in a unidirectional boron/aluminum composite material subjected to axial and transverse loadings are being studied utilizing a generalized plane strain finite element analysis. This micromechanics analysis was modified to permit the analysis of longitudinal sections, and also to incorporate crack initiation and propagation. The analysis fully models the elastoplastic response of the aluminum matrix, as well as temperature dependent material properties and thermal stress effects. The micromechanics analysis modifications are described, and numerical results are given for both longitudinal and transverse models loaded into the inelastic range, to first failure. Included are initially cracked fiber models

Comparison between high-energy proton and charged pion induced damage in Lead Tungstate calorimeter crystals

A Lead Tungstate crystal produced for the electromagnetic calorimeter of the CMS experiment at the LHC was cut into three equal-length sections. The central one was irradiated with 290 MeV/c positive pions up to a fluence of (5.67 +- 0.46)x10^13 /cm^2, while the other two were exposed to a 24 GeV/c proton fluence of (1.17 +- 0.11) x 10^13/ cm^2. The damage recovery in these crystals, stored in the dark at room temperature, has been followed over two years. The comparison of the radiation-induced changes in light transmission for these crystals shows that damage is proportional to the star densities produced by the irradiation.Comment: 7 pages, 4 figure

Second-chance punitivism and the contractual governance of crime and incivility: New Labour, old Hobbes

The growing application of mechanisms of contractual governance to behaviour that breaches social norms, rather than the criminal law, appears to represent an ethopolitical concern with delinquent self-reform through the activation of technologies of the self. In fact, there is little empirical evidence that the contractual governance of incivility leads to such self-reform. Beneath the ideology of contractual agreement to observe social norms lies what this paper calls a ‘second-chance punitivism’ which operates to crystallise behavioural elements of the Hobbesian social contract, after breach, into a more specific form. The responsibilising and individualising properties of this form of contractual governance set the moral-ideological platform for a retributive punitivism, when the rational agents it creates fail to live up to their image, and are taken to have wasted their ‘second chance’

Localization for Schrodinger operators with random vector potentials

We prove Anderson localization at the internal band-edges for periodic magnetic Schr{\"o}dinger operators perturbed by random vector potentials of Anderson-type. This is achieved by combining new results on the Lifshitz tails behavior of the integrated density of states for random magnetic Schr{\"o}dinger operators, thereby providing the initial length-scale estimate, and a Wegner estimate, for such models