Hybrid Simulation between Molecular Dynamics and Binary Collision Approximation Codes for Hydrogen injection onto Carbon Materials

Molecular dynamics (MD) simulation with modified Brenner's reactive empirical bond order (REBO) potential is a powerful tool to investigate plasma wall interaction on divertor plates in a nuclear fusion device. However, MD simulation box's size is less than several nm for the performance of a computer. To extend the size of the MD simulation, we develop a hybrid simulation code between MD code using REBO potential and binary collision approximation (BCA) code. Using the BCA code instead of computing all particles with a high kinetic energy for every step in the MD simulation, considerable computation time is saved. By demonstrating a hydrogen atom injection on a graphite by the hybrid simulation code, it is found that the hybrid simulation code works efficiently in a large simulation box.Comment: 5 pages, 5 figure

Visualisation of J-type counter-current chromatography: A route to understand hydrodynamic phase distribution and retention

This article can be accessed from the link below - Copyright @ 2012 Elsevier. The article was made available through open access by the Brunel Open Access Publishing Fund.This paper has addressed decade sought-after questions on phase bilateral distribution and stationary phase retention in any J-type high-speed counter-current chromatographic (CCC) centrifuge. Using a 2-D spiral column operated on such a CCC device and an aqueous two-phase system, this work systematically observed the phase interaction during transitional period and at dynamic equilibration under stroboscopic illumination. The experimental results thus obtained were used to examine the effects of the liquid–solid friction force, tangential centrifugal force, and physical properties of the two-phase system on hydrodynamic phase behaviour. We identified that (a) density difference between lower and upper phases is the critical factor to cause unusual phase bilateral distribution in the 2-D spiral column and (b) interfacial tension (manifested primarily as phase settling time) of any two-phase system is the critical factor in explaining inability to retain stationary phase in 3-D helical column and, for certain flow modes, in the 2-D spiral column. This work thus has extended or modified the well-established rule-of-thumb for operating J-type CCC devices and our conclusions can accommodate virtually all the anomalies concerning both hydrophobic and hydrophilic phase systems. To this end, this work has not only documented valuable experimental evidences for directly observing phase behaviour in a CCC column, but also finally resolved fundamentally vital issues on bilateral phase distribution orientation and stationary phase retention in 2-D spiral and 3-D helical CCC columns. Revised recommendations to end users of this technology could thus be derived out of the essence of the present work presumably following further experimental validation and a consensus in the CCC R&D and manufacturing circle.This work is funded by the BBSRC (UK) grant BB/C5063341/1, by MoST (China) as a Major State Basic Research Development Programme grant 2007CB714303 (973 Programme), by M & G Trading, and by Shanghai Science and Technology Board grant 11DZ2292700

On non-integrable complex distributions: an approach by transversality with real domains

We study the classification of singularities of holomorphic foliations and non-integrable one-forms under the hypothesis of transversality with real hypersurfaces

The WDVV Equations in N=2 Supersymmetric Yang-Mills Theory

We present a simple proof of the WDVV equations for the prepotential of four-dimensional N=2 supersymmetric Yang-Mills theory with all ADE gauge groups. According to our proof it is clearly seen that the WDVV equations in four dimensions have their origin in the associativity of the chiral ring in two-dimensional topological Landau-Ginzburg models. The WDVV equations for the BC gauge groups are also studied in the Landau-Ginzburg framework. We speculate about the topological field theoretic interpretation of the Seiberg-Witten solution of N=2 Yang-Mills theory.Comment: a footnote added, 14 pages, Latex, no figures, to appear in Phys. Lett.

The classification of Wada-type representations of braid groups

We give a classification of Wada-type representations of the braid groups, and solutions of a variant of the set-theoretical Yang-Baxter equation adapted to the free-product group structure. As a consequence, we prove Wada's conjecture: There are only seven types of Wada-type representations up to certain symmetries.Comment: 13 pages, 2 figures: Added Lemma 2.2, which was implicit in the previous version without proof and more explanation

Cosmological solutions for model with a 1/H21/H^{2} term

We drive the cosmological solutions of five-dimensional model with $1/H^{2}$ term $(H^{2}\equiv H_{MNPQ}H^{MNPQ})$, where $H_{MNPQ}$ is 4-form field strength. The behaviors of the scale factors and the scalar potential in effective theory are examined.As a consequence, we show that the universe changes from decelerated expansion to accelerated expansion in Einstein frame of the four-dimensional theory.Comment: 10 pages, 2 figures, version to appear in JCA