A Gas-Particle Analogue to the Richtmyer-Meshkov Instability: Comparing Multiphase Simulations to Shock Tube Experiments

A research area emerging in the multiphase flow community is the study of Shock-Driven Multi-phase Instability (SDMI), a gas-particle analog of the traditional fluid-fluid Richtmyer-Meshkov instability (RMI). In this work, we study the interaction of planar air shocks with corrugated glass particle curtains through the use of numerical simulations with an Eulerian-Lagrangian approach. This approach has simulations track computational particle trajectories in a Lagrangian framework while evolving the surrounding fluid flow on a fixed Eulerian mesh. In addition to observing the evolution of the perturbed particle curtain in the simulations, we also observe the evolution of the curtain of gas which is initially trapped inside of the particle curtain as the simulation progresses. The objective of this study is to compare the evolving simulation curtains (both particle and gas) to a comparable set of shock tube experiments performed to analyze traditional fluid RMI evolution. The simulations are set to match the experimental shock Mach numbers and perturbation wavelengths (3.6 and 7.2 mm) while matching the Atwood number of the experiments to the multiphase Atwood number of the simulations. However, multiple particle diameters are tested in the simulations to get a view into the impact of the particle diameter on the evolution of the particle curtain. This simulation setup allows for a one-to-one comparison between RMI and SDMI under comparable conditions while also allowing for a separate study into the validity of the use of both the multiphase Atwood number and the fluid-only Atwood number to compare the single-phase and multiphase instabilities. In particular, we show that this validity is at least partly dependent on the diameters of the particles in the curtain (thus, dependent on the Stokes number of the flow). We also analyze the effect of the multiphase terms of the vorticity evolution equation on the vorticity deposition in SDMI. Also discussed is the effect of the particle diameter on the multiphase generation terms as well as in the baroclinic vorticity generation term in SDMI as the shock passes over the curtain.

Accidental synthesis of a previously unknown quasicrystal in the first atomic bomb test

The first test explosion of a nuclear bomb, the Trinity test of 16 July 1945, resulted in the fusion of surrounding sand, the test tower, and copper transmission lines into a glassy material known as “trinitite.” Here, we report the discovery, in a sample of red trinitite, of a hitherto unknown composition of icosahedral quasicrystal, Si61Cu30Ca7Fe2. It represents the oldest extant anthropogenic quasicrystal currently known, with the distinctive property that its precise time of creation is indelibly etched in history. Like the naturally formed quasicrystals found in the Khatyrka meteorite and experimental shock syntheses of quasicrystals, the anthropogenic quasicrystals in red trinitite demonstrate that transient extreme pressure–temperature conditions are suitable for the synthesis of quasicrystals and for the discovery of new quasicrystal-forming systems.

HDFx, a Natural Biologic is Associated with Elevated DNA Methylation, Reduced DNA Oxidation and Telomerases Down-regulation in Macrophages and Monocytes Derived from Surviving Animals Subjected to Experimental Shock and Burns: Males vs. Females and Relation to Resistance Against Bacterial & Viral Infections

Circulatory shock and burns are significant and sustained states of hypoperfusion and lead to decreases in circulating blood volume combined with decreased tissue and organ oxygenation. This hypoperfusion state often causes sepsis resulting in a state of “multiple organ failure” [1-3]. Due to severe body burns, battle field casualties are most susceptible to the latter resulting in numerous loss of lives.

HDFx, a Natural Biologic is Associated with Elevated DNA Methylation, Reduced DNA Oxidation and Telomerases Down-regulation in Macrophages and Monocytes Derived from Surviving Animals Subjected to Experimental Shock and Burns: Males vs. Females and Relation to Resistance Against Bacterial & Viral Infections

Circulatory shock and burns are significant and sustained states of hypoperfusion and lead to decreases in circulating blood volume combined with decreased tissue and organ oxygenation. This hypoperfusion state often causes sepsis resulting in a state of “multiple organ failure” [1-3]. Due to severe body burns, battle field casualties are most susceptible to the latter resulting in numerous loss of lives.

High pressure impacts on meteorites

In the invited article, we review observations on changes in meteorite texture relevant to the early stages of formation of the Solar System based on the experimental shock wave loading of the material at the laboratory. Investigation of the physical and structural properties of high-pressure impacts on meteorites is important for few reasons, such as: Protection of the Earth from the near-Earth objects (NEOs); Study of processes that cannot yet be achieved under laboratory conditions; Understanding of conditions for asteroid mining.

Why Accounting Matters: Evidence from Accounting's “Big Bang”

ABSTRACT This article is based on my keynote speech presented at the 2018 Journal of International Accounting Research Conference held at Ca' Foscari University of Venice, Italy. The worldwide adoption of International Financial Reporting Standards in 2005 represents a “quasi-experimental” shock for thousands of companies around the world. This “Big Bang” event provided accounting researchers with an opportunity to gain insights into the fundamental qualitative characteristics of accounting that users find valuable. This research identifies several qualitative characteristics that help explain “why accounting matters,” including: (1) reliability, as captured by strong legal institutions, (2) accruals, (3) increased disclosure, (4) greater comparability, and (5) the use of historical costs (at least for contracting purposes). Notably, the overarching characteristic, which is necessary for all of the other characteristics to matter, is strong legal institutions.