Coupled DEM-LBM method for the free-surface simulation of heterogeneous suspensions

The complexity of the interactions between the constituent granular and liquid phases of a suspension requires an adequate treatment of the constituents themselves. A promising way for numerical simulations of such systems is given by hybrid computational frameworks. This is naturally done, when the Lagrangian description of particle dynamics of the granular phase finds a correspondence in the fluid description. In this work we employ extensions of the Lattice-Boltzmann Method for non-Newtonian rheology, free surfaces, and moving boundaries. The models allows for a full coupling of the phases, but in a simplified way. An experimental validation is given by an example of gravity driven flow of a particle suspension

Financial panic and emerging market funds

This article studies equity investment of emerging-market funds based on the 2003–2009 weekly data and compares the dynamics of flow and return between tranquil period and financial panic based on the experience of the latest 2008–2009 global financial crisis. First, we find that the well-documented positive feedback trading is a tranquil-period phenomenon such that it is more difficult in general for emerging-market funds to attract new investment in financial panic. Second, the predictive power of flow on return is driven by a combination of price pressure and information effects in tranquil period, while the information effect dominates in financial panic. Third, the underlying co-movements or contagion of flow across the emerging-market funds influence the association between flow and return. Overall, the findings highlight the importance of accounting for state-dependent dynamics as well as cross-regional co-movements in the analysis of flow and return

Lattice Boltzmann scheme for relativistic fluids

A Lattice Boltzmann formulation for relativistic fluids is presented and numerically verified through quantitative comparison with recent hydrodynamic simulations of relativistic shock-wave propagation in viscous quark-gluon plasmas. This formulation opens up the possibility of exporting the main advantages of Lattice Boltzmann methods to the relativistic context, which seems particularly useful for the simulation of relativistic fluids in complicated geometries.Comment: Submitted to PR

Influence of MWCNT/surfactant dispersions on the mechanical properties of Portland cement pastes

This work studies the reinforcing effect of Multi Walled Carbon Nanotubes (MWCNT) on cement pastes. A 0.35% solid concentration of MWCNT in powder was dispersed in deionized water with sodium dodecyl sulfate (cationic surfactant), cetylpyridinium chloride (anionic surfactant) and triton X-100 (amphoteric surfactant) using an ultrasonic tip processor. Three concentrations of each surfactant (1mM, 10mM and 100mM) were tested, and all samples were sonicated until an adequate dispersion degree was obtained. Cement pastes with additions of carbon nanotubes of 0.15% by mass of cement were produced in two steps; first the dispersions of MWCNT were combined with the mixing water using an ultrasonic tip processor to guarantee homogeneity, and then cement was added and mixed until a homogeneous paste was obtained. Direct tensile strength, apparent density and open porosity of the pastes were measured after 7 days of curing. It was found that the MWCNT/surfactants dispersions decrease the mechanical properties of the cement based matrix due to an increased porosity caused by the presence of surfactants. © Published under licence by IOP Publishing Ltd

Graphite: Open Source 2D Graphics Editor

Graphite is an open source 2D graphics editor aiming to provide a useful alternative to the Adobe product suite while integrating modern ideas from research and industry, including a node-based procedural approach that makes the design process fully non-destructive. Tools from the VFX and gamedev industry like Nuke, Houdini, and Substance Designer have proven the power and flexibility of node-based systems, but they are each lacking in their user experience because of the deep level of complexity that is not abstracted into simpler concepts for users (Adobe Systems, SideFX, The Foundry Visionmongers Ltd., n.d.). Graphite puts the node-based core into a traditional tool-based shell, making it more accessible and familiar to experienced 2D designers and artists as well as new users. These tools, which form an abstraction around the node graph concepts, act much like existing graphics editors. One aspect of tool-based editing is the snapping system that can constrain artwork manipulations to align with other layers, geometry, or a grid. Graphite seeks to improve upon the user experience of many core tools and workflows in areas neglected by traditional editing software, and snapping systems are one prime example of a common, “boring” feature where pain points and potential improvements are hidden in plain sight. Graphite’s goal is to fundamentally improve upon the user experience of snapping so artists and designers can benefit from a more useful way to make pixel-perfect artwork

Molecules with a peptide link in protostellar shocks: a comprehensive study of L1157

Interstellar molecules with a peptide link -NH-C(=O)-, like formamide (NH$_2$CHO), acetamide (NH$_2$COCH$_3$) and isocyanic acid (HNCO) are particularly interesting for their potential role in pre-biotic chemistry. We have studied their emission in the protostellar shock regions L1157-B1 and L1157-B2, with the IRAM 30m telescope, as part of the ASAI Large Program. Analysis of the line profiles shows that the emission arises from the outflow cavities associated with B1 and B2. Molecular abundance of $\approx~(0.4-1.1)\times 10^{-8}$ and $(3.3-8.8)\times 10^{-8}$ are derived for formamide and isocyanic acid, respectively, from a simple rotational diagram analysis. Conversely, NH$_2$COCH$_3$ was not detected down to a relative abundance of a few $\leq 10^{-10}$. B1 and B2 appear to be among the richest Galactic sources of HNCO and NH$_2$CHO molecules. A tight linear correlation between their abundances is observed, suggesting that the two species are chemically related. Comparison with astrochemical models favours molecule formation on ice grain mantles, with NH$_2$CHO generated from hydrogenation of HNCO.Comment: 11 pages, 9 figures. Accepted for publication in MNRAS Main Journal. Accepted 2014 August 19, in original form 2014 July

Search for the Higgs Boson H20H_2^0 at LHC in 3-3-1 Model

We present an analysis of production and signature of neutral Higgs boson ($H_{2}^{0}$) on the version of the 3-3-1 model containing heavy leptons at the Large Hadron Collider. We studied the possibility to identify it using the respective branching ratios. Cross section are given for the collider energy, $\sqrt{s} =$ 14 TeV. Event rates and significances are discussed for two possible values of integrated luminosity, 300 fb$^{-1}$ and 3000 fb$^{-1}$.Comment: 17 pages 7 figures. arXiv admin note: substantial text overlap with arXiv:1205.404