NBSymple, a double parallel, symplectic N-body code running on Graphic Processing Units

We present and discuss the characteristics and performances, both in term of computational speed and precision, of a numerical code which numerically integrates the equation of motions of N 'particles' interacting via Newtonian gravitation and move in an external galactic smooth field. The force evaluation on every particle is done by mean of direct summation of the contribution of all the other system's particle, avoiding truncation error. The time integration is done with second-order and sixth-order symplectic schemes. The code, NBSymple, has been parallelized twice, by mean of the Computer Unified Device Architecture to make the all-pair force evaluation as fast as possible on high-performance Graphic Processing Units NVIDIA TESLA C 1060, while the O(N) computations are distributed on various CPUs by mean of OpenMP Application Program. The code works both in single precision floating point arithmetics or in double precision. The use of single precision allows the use at best of the GPU performances but, of course, limits the precision of simulation in some critical situations. We find a good compromise in using a software reconstruction of double precision for those variables that are most critical for the overall precision of the code. The code is available on the web site astrowww.phys.uniroma1.it/dolcetta/nbsymple.htmlComment: Paper composed by 29 pages, including 9 figures. Submitted to New Astronomy

Correction to: SERENA: Particle Instrument Suite for Determining the Sun-Mercury Interaction from BepiColombo

International audienc

SERENA:Particle Instrument Suite for Determining the Sun-Mercury Interaction from BepiColombo

International audienceThe ESA-JAXA BepiColombo mission to Mercury will provide simultaneous measurements from two spacecraft, offering an unprecedented opportunity to investigate magnetospheric and exospheric particle dynamics at Mercury as well as their interactions with solar wind, solar radiation, and interplanetary dust. The particle instrument suite SERENA (Search for Exospheric Refilling and Emitted Natural Abundances) is flying in space on-board the BepiColombo Mercury Planetary Orbiter (MPO) and is the only instrument for ion and neutral particle detection aboard the MPO. It comprises four independent sensors: ELENA for neutral particle flow detection, Strofio for neutral gas detection, PICAM for planetary ions observations, and MIPA, mostly for solar wind ion measurements. SERENA is managed by a System Control Unit located inside the ELENA box. In the present paper the scientific goals of this suite are described, and then the four units are detailed, as well as their major features and calibration results. Finally, the SERENA operational activities are shown during the orbital path around Mercury, with also some reference to the activities planned during the long cruise phase

Symplectic translation planes and line ovals

A symplectic spread of a 2n-dimensional vector space V over GF(q) is a set of q^n + 1 totally isotropic n-subspaces inducing a partition of the points of the underlying projective space. The corresponding translation plane is called symplectic. We prove that a translation plane of even order is symplectic if and only if it admits a completely regular line oval. Also, a geometric characterization of completely regular line ovals, related to certain symmetric designs is given. These results give a complete solution to a problem set by W. M. Kantor in apparently different situations

Hyperovals and Hadamard designs

Hadamard designs which can be associated with a hyperoval of a projective plane of even order are investigated. In particular, when the hyperoval is a translation hyperoval, these designs are shown to contain restrictions that are isomorphic to the 2-design of points and hyperplanes of a projective geometry over GF(2)

Supercritical carbon dioxide separation of fish oil ethyl esters by means of a continuous countercurrent process with an internal reflux

The continuous countercurrent fractionation of fish oil ethyl esters using supercritical carbon dioxide is studied, modelling a process with internal reflux generated by a thermal gradient at the top stage. A methodology for process design is proposed and applied to determine the relationships between the temperature at the top stage (T-1), the number of theoretical stages (N), and the solvent to feed ratio (S IF), with the aim of providing a quantitative comparison with the external reflux process. The internal reflux process is viable and, for stated process specifications (mass fraction and recovery of C20 + C22 ethyl esters of 95%), provides comparable or better results than the external reflux process. For example, operating at 13.3 MPa and 50 degrees C, and keeping T-1 in the range (66-70) degrees C, the specifications are attained with N and S/F in the range 16-30 and 88-120, respectively. (C) 2013 Elsevier B.V. All rights reserved