Modeling the process of producing hydrogen from methane

Using the chemical reactions that accompany the production of syngas via the steam reforming of methane as a basis, the differential material balance equations were derived and solved for all conversion products on an aluminum/nickel catalyst. For the following stage of hydrogen synthesis on an iron/chromium catalyst, the system of two differential equations of the material balance of the direct and reverse reactions of steam carbon monoxide conversion was obtained and solved. The analytical solutions were compared with the experiment. © 2013 Pleiades Publishing, Ltd

Influence of the solar EUV flux on the Martian plasma environment

The interaction of the solar wind with the Martian atmosphere and ionosphere is investigated by using three-dimensional, global and multi-species hybrid simulations. In the present work we focus on the influence of the solar EUV flux on the Martian plasma environment by comparing simulations done for conditions representative of the extrema of the solar cycle. The dynamics of four ionic species (H<sup>+</sup>, He<sup>++</sup>, O<sup>+</sup>, O<sub>2</sub><sup>+</sup>), originating either from the solar wind or from the planetary plasma, is treated fully kinetically in the simulation model in order to characterize the distribution of each component of the plasma, both at solar maximum and at solar minimum. The solar EUV flux controls the ionization frequencies of the exospheric species, atomic hydrogen and oxygen, as well as the density, the temperature, and thus the extension of the exosphere. Ionization by photons and by electron impacts, and the main charge exchange reactions are self-consistently included in the simulation model. Simulation results are in reasonable agreement with the observations made by Phobos-2 and Mars Global Surveyor (MGS) spacecraft: 1) the interaction creates a cavity, void of solar wind ions (H<sup>+</sup>, He<sup>++</sup>), which depends weakly upon the phase of the solar cycle, 2) the motional electric field of the solar wind flow creates strong asymmetries in the Martian environment, 3) the spatial distribution of the different components of the planetary plasma depends strongly upon the phase of the solar cycle. The fluxes of the escaping planetary ions are computed from the simulated data and results for solar maximum are compared with estimates based on the measurements made by experiments ASPERA and TAUS on board Phobos-2

The Structure of Martian Magnetosphere at the Dayside Terminator Region as Observed on MAVEN Spacecraft

We analyzed 44 passes of the MAVEN spacecraft through the magnetosphere, arranged by the angle between electric field vector and the projection of spacecraft position radius vector in the YZ plane in MSE coordinate system (${\theta}$ E ). All passes were divided into 3 angular sectors near 0{\deg}, 90{\deg} and 180{\deg} ${\theta}$ E angles in order to estimate the role of IMF direction in plasma and magnetic properties of dayside Martian magnetosphere. The time interval chosen was from January 17 through February 4, 2016 when MAVEN was crossing the dayside magnetosphere at SZA ~ 70{\deg}. Magnetosphere as the region with prevailing energetic planetary ions is always found between the magnetosheath and the ionosphere. 3 angular sectors of dayside interaction region in MSE coordinate system with different orientation of the solar wind electric field vector E = -1/c V x B showed that for each sector one can find specific profiles of the magnetosheath, the magnetic barrier and the magnetosphere. Plume ions originate in the northern MSE sector where motion electric field is directed from the planet. This electric field ejects magnetospheric ions leading to dilution of magnetospheric heavy ions population, and this effect is seen in some magnetospheric profiles. Magnetic barrier forms in front of the magnetosphere, and relative magnetic field magnitudes in these two domains vary. The average height of the boundary with ionosphere is ~530 km and the average height of the magnetopause is ~730 km. We discuss the implications of the observed magnetosphere structure to the planetary ions loss mechanism.Comment: 24 pages, 13 figure

Rational method of generation of combinations for parallel calculations in some combinatorial problems

Целью данной статьи являлась разработка нового способа нумерации сочетаний. Его особенностью является отсутствие в алгоритме циклов и ветвлений, что позволяет эффективно использовать его в многопоточном режиме. Для выполнения поставленной задачи были произведены разработка алгоритма, нахождение оптимального способа вычисления требуемых величин и оптимизация под многопоточные системы. По сравнению с классическими, данный метод показывает заметное увеличение производительности даже не в самых благоприятных условиях. Особенностью полученного алгоритма является независимое выполнение разных потоков вычисления, что очень важно при выполнении программы на процессорах SIMD архитектуры. Таким образом, разработанный способ нумерации имеет очевидные преимущества и может быть использован в задачах, решаемых методами комбинаторной оптимизации.The purpose of this paper is development of a new method of numbering combinations. Its feature is the absence of loops and branches in the algorithm, which allows using it effectively multithreaded. For this purpose the following tasks have been produced: development of an algorithm, finding an optimal method for calculating the required values and optimization for multi-threaded system. Compared to classical ones, proposed method showed a significant performance increase even in adverse conditions. Thus, the developed algorithm of numbering has obvious advantages, and can be used in tasks, solved by methods of combinatorial optimization

Метод генерации сочетаний для параллельных вычислений

В предыдущих работах решалась задача составления оптимального производственного расписания. Для оптимизации процесса потребовался метод генерации сочетаний, пригодный для использования на графических процессорах. Обзор литературы показал, что предлагаемые решения не оптимальны, поэтому было решено разработать такой метод самостоятельно. В основе разработанного метода лежит другой принцип представления комбинаторных объектов. Благодаря этому номера объектов, составляющих выборку, можно вычислять алгебраически, без использования циклов и операций ветвления.In previous works we solved the problem of optimal production schedules. To optimize the process, a method of generating combinations, suitable for use on graphics processing units, was needed. Literature review showed that the proposed solutions are not optimal, so it was decided to develop a method of their own. The basis of this method is another principle of representation of combinatorial objects. This allows computing algebraically sample’s objects numbers, without using loops and branching operations

γγ Physics

This chapter is devoted to QCD and, more generally, Strong Interaction studies in γγ collisions. For our purposes, LEP2 is a continous energy γγ collider with a reach of up to 100 GeV center of mass energy for some observables. At low energy, the main studies concern resonance production and quasi two-body processes which probe the meson and baryon wavefunctions. At high energy, the partonic structure of the photon plays a dominant role and, as for hadronic processes, several tests of perturbative QCD, using many different observables, are possible. A specific feature of γγ collisions is the variability of the mass of the incoming photons which can be used to tune the non-perturbative component of the photon

Phase diagrams in nonlocal PNJL models constrained by Lattice QCD results

Based on lattice QCD-adjusted SU(2) nonlocal Polyakov--Nambu--Jona-Lasinio (PNJL) models, we investigate how the location of the critical endpoint in the QCD phase diagram depends on the strenght of the vector meson coupling, as well as the Polyakov-loop (PL) potential and the form factors of the covariant model. The latter are constrained by lattice QCD data for the quark propagator. The strength of the vector coupling is adjusted such as to reproduce the slope of the pseudocritical temperature for the chiral phase transition at low chemical potential extracted recently from lattice QCD simulations. Our study supports the existence of a critical endpoint in the QCD phase diagram albeit the constraint for the vector coupling shifts its location to lower temperatures and higher baryochemical potentials than in the case without it.Comment: 23 pages, 10 figures. Version accepted in Phys. Part. Nucl. Lett. (to appear), references adde