Unbounded solutions for systems with hysteretic nonlinearity

The work is dedicated to study of the dynamics of model systems that are described by differential equations with additive hysteretic nonlinearities in the case when a hysteretic loop bypass clockwise. In particular, for the model of the harmonic oscillator with hysteretic external force the conditions for existence of unbounded solutions are obtained. For the model of harmonic oscillator with a dry (Coulomb) and viscous friction under external hysteretic affection we obtained a set of conditions that ensure the self-oscillation mode. The numerical examples that illustrate the results of this work are also presented.This work is supported by the RFBR grant No 16-08-00312, 17-01-00251

"Confinement Mechanism in Various Abelian Projections of SU(2)SU(2) Lattice Gluodynamics"

We show that the monopole confinement mechanism in lattice gluodynamics is a particular feature of the maximal abelian projection. We give an explicit example of the $SU(2) \rightarrow U(1)$ projection (the minimal abelian projection), in which the confinement is due to topological objects other than monopoles. We perform analytical and numerical study of the loop expansion of the Faddeev--Popov determinant for the maximal and the minimal abelian projections, and discuss the fundamental modular region for these projections.Comment: 16 pages (LaTeX) and 3 figures, report ITEP-94-6

Constructions of free commutative integro-differential algebras

In this survey, we outline two recent constructions of free commutative integro-differential algebras. They are based on the construction of free commutative Rota-Baxter algebras by mixable shuffles. The first is by evaluations. The second is by the method of Gr\"obner-Shirshov bases.Comment: arXiv admin note: substantial text overlap with arXiv:1302.004

Search for Solar Axions Produced by Primakoff Conversion Using Resonant Absorption by 169^{169}Tm Nuclei

The search for resonant absorption of the Primakoff solar axions by $^{169}$Tm nuclei have been performed. Such an absorption should lead to the excitation of low-lying nuclear energy level: $A+^{169}$Tm $\to ^{169}$Tm$^*$ $\to ^{169}$Tm$+ \gamma$ (8.41 keV). The Si(Li) detector and $^{169}$Tm target placed inside the low-background setup were used for that purpose. As a result, a new restriction on the axion-photon coupling and axion mass was obtained: $g_{A\gamma}({GeV}^{-1})\cdot m_A(eV)\leq1.36\cdot10^{-5}$ (90% c.l.). In model of hadronic axion this restriction corresponds to the upper limit on axion mass - $m_A\leq$ 191 eV for 90% c.l.Comment: 6 pages, 5 figures, submitted to Physics Letters

Obtaining silicon carbide via chemical vapor, plasma-chemical and sublimation methods

In the present paper the results of studies on obtaining silicon carbide via chemical gas phase, plasma-chemical and sublimation methods are described. The thermodynamic analysis of chemical reactions of silicon carbide in the presence of hydrogen and without was provided. Was found that, without free hydrogen reaction of silicon carbide formation can’t proceed. Established depending on ratio between the various active components of the gas phase SiCl₄:C₇H₈, entering the reactor, morphology of SiC layer. Was shown that, with increasing temperature of the substrate deposition rate increases, reaching a maximum temperature about ~ 1800 K with a steep decreasing at higher temperatures ranges, which is typical of a homogeneous reaction. From source (NbTa)SiC, received via chemical CVD, obtained films of SiC with sublimation method.Представлены результаты исследований по получению карбида кремния химическим газофазным, плазмохимическим и сублимационным методами. Проведен термодинамический анализ химических реакций получения карбида кремния в присутствии водорода и без него. Установлено, что без свободного водорода реакция образования карбида кремния протекать не может. В зависимости от различного соотношения между активными компонентами газовой фазы SiCl₄:C₇H₈, поступающими в реактор, изучена морфология SiC-слоя. Исследована кинетика процесса осаждения SiC. Показано, что с увеличением температуры подложки скорость осаждения возрастает, достигая максимума при температуре ~ 1800 K с резким снижением в области более высоких температур, что характерно для гомогенной реакции. Из полученного химическим газофазным методом источника (NbTa)SiC сублимационным методом получены плёнки SiC.Представлено результати досліджень по отриманню карбіду кремнію хімічним газофазним, плазмохімічним і сублімаційним методами. Проведено термодинамічний аналіз хімічних реакцій отримання карбіду кремнію в присутності водню і без нього. Встановлено, що без вільного водню реакція утворення карбіду кремнію протікати не може. Залежно від різного співвідношення між активними компонентами газової фази SiCl₄:C₇H₈, які надходять в реактор, вивчена морфологія SiC-шару. Досліджено кінетику процесу осадження SiC. Показано, що зі збільшенням температури підкладки швидкість осадження зростає, досягаючи максимуму при температурі ~ 1800 K з різким зниженням в області більш високих температур, що характерно для гомогенної реакції. З отриманого хімічним газофазним методом джерела (NbTa)SiC сублімаційним методом отримано плівки SiC

Experimental Study of the Shortest Reset Word of Random Automata

In this paper we describe an approach to finding the shortest reset word of a finite synchronizing automaton by using a SAT solver. We use this approach to perform an experimental study of the length of the shortest reset word of a finite synchronizing automaton. The largest automata we considered had 100 states. The results of the experiments allow us to formulate a hypothesis that the length of the shortest reset word of a random finite automaton with $n$ states and 2 input letters with high probability is sublinear with respect to $n$ and can be estimated as $1.95 n^{0.55}.

Two-proton correlations from 158 AGeV Pb+Pb central collisions

The two-proton correlation function at midrapidity from Pb+Pb central collisions at 158 AGeV has been measured by the NA49 experiment. The results are compared to model predictions from static thermal Gaussian proton source distributions and transport models RQMD and VENUS. An effective proton source size is determined by minimizing CHI-square/ndf between the correlation functions of the data and those calculated for the Gaussian sources, yielding 3.85 +-0.15(stat.) +0.60-0.25(syst.) fm. Both the RQMD and the VENUS model are consistent with the data within the error in the correlation peak region.Comment: RevTeX style, 6 pages, 4 figures, 1 table. More discussion are added about the structure on the tail of the correlation function. The systematic error is revised. To appear in Phys. Lett.

Event-by-event fluctuations of average transverse momentum in central Pb+Pb collisions at 158 GeV per nucleon

We present first data on event-by-event fluctuations in the average transverse momentum of charged particles produced in Pb+Pb collisions at the CERN SPS. This measurement provides previously unavailable information allowing sensitive tests of microscopic and thermodynamic collision models and to search for fluctuations expected to occur in the vicinity of the predicted QCD phase transition. We find that the observed variance of the event-by-event average transverse momentum is consistent with independent particle production modified by the known two-particle correlations due to quantum statistics and final state interactions and folded with the resolution of the NA49 apparatus. For two specific models of non-statistical fluctuations in transverse momentum limits are derived in terms of fluctuation amplitude. We show that a significant part of the parameter space for a model of isospin fluctuations predicted as a consequence of chiral symmetry restoration in a non-equilibrium scenario is excluded by our measurement.Comment: 6 pages, 2 figures, submitted to Phys. Lett.

Grain Surface Models and Data for Astrochemistry

AbstractThe cross-disciplinary field of astrochemistry exists to understand the formation, destruction, and survival of molecules in astrophysical environments. Molecules in space are synthesized via a large variety of gas-phase reactions, and reactions on dust-grain surfaces, where the surface acts as a catalyst. A broad consensus has been reached in the astrochemistry community on how to suitably treat gas-phase processes in models, and also on how to present the necessary reaction data in databases; however, no such consensus has yet been reached for grain-surface processes. A team of ∼25 experts covering observational, laboratory and theoretical (astro)chemistry met in summer of 2014 at the Lorentz Center in Leiden with the aim to provide solutions for this problem and to review the current state-of-the-art of grain surface models, both in terms of technical implementation into models as well as the most up-to-date information available from experiments and chemical computations. This review builds on the results of this workshop and gives an outlook for future directions

The composition of the protosolar disk and the formation conditions for comets

Conditions in the protosolar nebula have left their mark in the composition of cometary volatiles, thought to be some of the most pristine material in the solar system. Cometary compositions represent the end point of processing that began in the parent molecular cloud core and continued through the collapse of that core to form the protosun and the solar nebula, and finally during the evolution of the solar nebula itself as the cometary bodies were accreting. Disentangling the effects of the various epochs on the final composition of a comet is complicated. But comets are not the only source of information about the solar nebula. Protostellar disks around young stars similar to the protosun provide a way of investigating the evolution of disks similar to the solar nebula while they are in the process of evolving to form their own solar systems. In this way we can learn about the physical and chemical conditions under which comets formed, and about the types of dynamical processing that shaped the solar system we see today. This paper summarizes some recent contributions to our understanding of both cometary volatiles and the composition, structure and evolution of protostellar disks.Comment: To appear in Space Science Reviews. The final publication is available at Springer via http://dx.doi.org/10.1007/s11214-015-0167-