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The paper presents a stochastic analysis of the growth rate of viscous fingers in miscible displacement in a heterogeneous porous medium. The statistical parameters characterizing the permeability distribution of a reservoir vary over a wide range. The formation of fingers is provided by the mixing of different-viscosity fluids -- water and polymer solution. The distribution functions of the growth rate of viscous fingers are numerically determined and visualized. Careful data processing reveals the non-monotonic nature of the dependence of the front end of the mixing zone on the correlation length of the permeability (describing the medium graininess) of the reservoir formation. It is demonstrated that an increase in graininess up to a certain value causes an expansion of the distribution shape and a shift of the distribution maximum to the region of higher velocities. In addition, an increase in the standard deviation of permeability leads to a slight change in the shape and characteristics of the density distribution of the growth rates of viscous fingers. The theoretical predictions within the framework of the transverse flow equilibrium approximation and the Koval model are contrasted with the numerically computed velocity distributions., Comment: 18 pages, 10 figures

Random walks are powerful tools to analyze spatial-temporal patterns produced by living organisms ranging from cells to humans. At the same time, it is evident that these patterns are not completely random but are results of a convolution of organisms' sensor-based information processing and motility. The complexity of the first component is reflected in the statistical characteristics of trajectories produced by an organism -- when it is, e.g., foraging or searching for a mate (or a pathogen) -- and therefore some knowledge about the component can be obtained by analyzing the trajectories with the standard toolbox of methods used for random walks. Here we consider trajectories which appear as the results of a game played by two players on a finite square lattice. One player wants to survive, i. e., to stay within the interior of the square, as long as possible while another one wants to reach the adsorbing boundary. A game starts from the center of the square and every next movement of the point is determined by independent strategy choices made by the players. The value of the game is the survival time that is the number of steps before the adsorption happens. We present the results of a series of experiments involving both human players and an autonomous agent (bot) and concentrate on the probability distribution of the survival time. This distribution indicate that the process we are dealing with is more complex than the standard random walks.

The paper investigates the linear growth of the mixing zone during polymer slug injection into a water reservoir. The velocities of the slug front and of the boundaries of the mixing zone are analyzed as key parameters. Using two different numerical methods (finite volumes and finite elements), the impact of the slug size, reservoir dimensions, Peclet number, and viscosity curve shape on the corresponding velocities is examined. Notwithstanding the realization of the solution by two computational schemes, the simulation results coincide with sufficient accuracy. The numerically obtained velocities are compared with theoretical estimates within the transverse flow equilibrium approximation and Koval model. Based on the comparison pattern, recommendations are presented on the use of specific analytical methods for estimating the growth rate of the mixing zone depending on the characteristics of the polymer.

Using X-ray diffraction, there were determined the residual stresses on the surface of the AISI 310S stainless steel carrier tape used in manufacture of the second generation high temperature superconducting (2G HTS) wires at the National Research Center "Kurchatov Institute", from delivery to deposition of the main buffer layer YSZ between the tape and the superconducting layer, and the residual stress in the buffer layer YSZ itself. The compressive stress of -0.8 GPa induced by rolling was found on the surface of the tape as-delivered. During processing, it varies from -0.5 to -1.1 GPa. At each stage, its depth distribution was found down to 10 μm, and the residual stresses caused by processing were determined. The residual stress in the YSZ layer deposited using the ABAD technology is compressive and amounts to -3.29 GPa. The layer has a defective single-crystal structure in type to radiation swelling with the unstressed lattice period of 5.1820 Angstrem, 0.9% larger than in ordinary crystal. The results obtained are in agreement with the data of the earlier neutron diffraction study of residual stresses inside the carrier tape. Keywords: residual stress, 2G HTS wires, AISI 310S tape, YSZ layer, YSZ crystal structure, X-ray diffraction.

Non-linear absorption spectroscopy in pump and probe configuration has been used to test the population of non-equilibrium carriers in Ce-doped Y3Al5O12 (YAG), Lu3Al5O12 (LuAG), and Gd3AlxGa(5-x)O12 (GAGG) crystals with and without codoping by Mg2+ ions. A faster rise time of the induced optical density has been observed in all crystals codoped with Mg with respect to that in Mg-free samples. A significant difference in the time evolution of the differential optical density in GAGG with respect to YAG and LuAG crystals has also been measured. In both GAGG:Ce and GAGG:Ce,Mg an absorption band with maximum in the blue-green range and a decay time of 1.4 ps is present. This band is due to the absorption by free electrons before they are trapped or re-captured by Ce3+ ions. A broad absorption band in the yellow-red region with very short rise time and a decay time longer than 150 ps has been observed in all the Ce-doped garnets under study and can be attributed to the absorption from the Ce3+ excited states.

We prove that for any closed manifold of dimension 3 or greater that there is an open set of smooth flows that have a hyperbolic set that is not contained in a locally maximal one. Additionally, we show that the stabilization of the shadowing closure of a hyperbolic set is an intrinsic property for premaximality. Lastly,we review some results due to Anosov that concern premaximality., 25 pages, 4 figures

The article deals with the proposals for the organization of metrological support of a new class of information and control systems based on fiberoptic sensors for use in railway transport phasesensitive optical reflectometers or coherent reflectometers. Three main approaches to the organization of metrological support are considered : 1) in the sphere of state regulation of ensuring the unity of measurements, in which reflectometers are subject to approval of the type of measuring instruments, mandatory verification at production, after repair and during operation, as well as certified measurement methods are used 2) by establishing the General technical requirements and test procedures for the release from production, in which standards need to establish common for all manufacturers technical requirements for reflectometers and test methods, the implementation of which will improve the quality of technical control reflectometers in production and the reliability of their measurements 3) by passing the entrance control in the structure of JSC Russian Railways or in the involved expert organizations, in which on the basis of the developed Requirements for reflectometers and programs and test methods, the reflectometers will be tested for compliance with these Requirements when they are delivered to JSC Russian Railways , as well as during their operation on railway transport., В статье рассмотрены предложения по организации метрологического обеспечения нового класса информационноуправляющих систем на основе волоконнооптических датчиков для применения на железнодорожном транспорте фазочувствительных оптических или когерентных рефлектометров. Предложены три основных варианта. Первый подразумевает государственное регулирование обеспечения единства измерений с обязательной поверкой утвержденных типов рефлектометров в процессе производства, эксплуатации и ремонта, а также применение аттестованных методик измерений. Во втором варианте устанавливаются стандарты, где прописываются общие для всех производителей технические требования к рефлектометрам и методики их испытаний, выполнение которых позволит повысить качество технического контроля приборов на производстве и достоверность результатов измерений. Третий вариант прохождение входного контроля в структуре ОАО РЖД или в привлеченных экспертных организациях. В этом случае на основе разработанных требований, программ и методик будут проводиться испытания рефлектометров при поставке, а также в процессе эксплуатации на железнодорожном транспорте., Автоматика, связь, информатика, Выпуск 9 (9) 2019

We study the problem of rationality of an infinite series of components, the so-called Ein components, of the Gieseker-Maruyama moduli space $M(e,n)$ of rank 2 stable vector bundles with the first Chern class $e=0$ or -1 and all possible values of the second Chern class $n$ on the projective 3-space. The generalized null correlation bundles constituting open dense subsets of these components are defined as cohomology bundles of monads whose members are direct sums of line bundles of degrees depending on nonnegative integers $a,b,c$, where $b\ge a$ and $c>a+b$. We show that, in the wide range when $c>2a+b-e,\ b>a,\ (e,a)\ne(0,0)$, the Ein components are rational, and in the remaining cases they are at least stably rational. As a consequence, the union of the spaces $M(e,n)$ over all $n\ge1$ contains an infinite series of rational components for both $e=0$ and $e=-1$. Explicit constructions of rationality of Ein components under the above conditions on $e,a,b,c$ and, respectively, of their stable rationality in the remaining cases, are given. In the case of rationality, we construct universal families of generalized null correlation bundles over certain open subsets of Ein components showing that these subsets are fine moduli spaces. As a by-product of our construction, for $c_1=0$ and $n$ even, they provide, perhaps the first known, examples of fine moduli spaces not satisfying the condition "$n$ is odd", which is a usual sufficient condition for fineness., 37 pages

Mid-rapidity transverse mass spectra and multiplicity densities of charged and neutral kaons are reported for Au+Au collisions at $\snn$=130 GeV at RHIC. The spectra are exponential in transverse mass, with an inverse slope of about 280 MeV in central collisions. The multiplicity densities for these particles scale with the negative hadron pseudo-rapidity density. The charged kaon to pion ratios are $K^+/\pi^- = 0.161 \pm 0.002 {\rm (stat)} \pm 0.024 {\rm (syst)}$ and $K^-/\pi^- = 0.146 \pm 0.002 {\rm (stat)} \pm 0.022 {\rm (syst)}$ for the most central collisions. The $K^+/\pi^-$ ratio is lower than the same ratio observed at the SPS while the $K^-/\pi^-$ is higher than the SPS result. Both ratios are enhanced by about 50% relative to p+p and $\bar{\rm p}$+p collision data at similar energies., Comment: 6 pages, 3 figures, 1 table

Properties of the latex coagulum formed during the manufacture of styrene-butadiene latices were investigated. Influence of processing conditions onthe properties of coagulum polymer compositions was investigated. Plasticizers for latex coagulum improving its handling on the process equipment were selected. Recommendations for the use of plasticized latex coagulum comprisinga polymer base rubber compounds have been proposed.

The problem of vulcanization (curing) of massive products is considered important for technology of processing of polymers. It is shown, that during structurization compound rubber materials distribution of temperatures on all section is unequal, that results in distinction in structure and properties of such samples. Temperature fields in cuts of a product are designed and dependences of change of structural parameters are established. Kinetic characteristics of process of vulcanization are determined and recommendations on creation and updating of modes of vulcanization massive elastomer products are produced.