Three-Dimensional Convection in an Inclined Porous Layer Subjected to a Vertical Temperature Gradient

In this paper,we study the onset and development of three-dimensional convection in a tilted porous layer saturated with a liquid.The layer is subjected to a gravitational field and a strictly vertical temperature gradient.Typically,problems of thermal convection in tilted porous media saturated with a liquid are studied by assuming constant different temperatures at the boundaries of the layer,which prevent these systems from supporting conductive(non-convective)states.The boundary conditions considered in the present work allow a conductive state and are representative of typical geological applications.In an earlier work,we carried out a linear stability analysis of the conductive state.It was shown that at any layer tilt angles,the most dangerous type of disturbances are longitudinal rolls.Moreover,a non-zero velocity component exists in z-direction.In the present work,threedimensional non-linear convection regimes are studied.The original three-dimensional problem is reduced to two-dimensional one with an analytical expression for the velocity z-component v_(z)=v_(z)(x,y).It is shown that the critical Rayleigh number values obtained through numerical solutions of the obtained 2D problem by a finite difference method for different layer inclination angles,are in a good agreement with those predicted by the linear theory.The number of convective rolls realized in nonlinear calculations also fits the linear theory predictions for a given cavity geometry.Calculations carried out at low supercriticalities show that a direct bifurcation takes place.With increasing supercriticality,no transitions to other convective regimes are detected.The situation studied in this problem can be observed in oil-bearing rock formations under the influence of a geothermal temperature gradient,where the ensuing fluid convection can affect the distribution of oil throughout the layer.

The Behavior of a Gas Bubble in a Square Cavity Filled with a Viscous LiquidUndergoing Vibrations

External vibrations are known to be one of the promising ways to control the behavior of multiphase systems. Thecomputational modeling of the behavior of a gas bubble in a viscous liquid in a horizontal cylinder of squarecross-section, which undergoes linearly polarized translational oscillations in weightless conditions, has been carried out. Under vibrations, the bubble moves towards the wall of the vessel with acceleration determined by theamplitudes and frequency of vibrations. Near the wall, at a distance of the order of the thickness of the viscousStokes boundary layer, the effects of viscosity become more important and, as a result, the bubble is repelled fromthe wall. After some oscillations, equilibrium conditions are attained where the attractive force balances the repulsive force;accordingly, the average position of the bubble ceases to change. The numerical modelling shows thatthe average behaviors of a deformable bubble near a wall under normal and tangential vibration are similar.

Near-field characteristics of highly non-paraxial subwavelength optical fields with hybrid states of polarization

The vectorial structure of an optical field with hybrid states of polarization （SOP） in the near-field is studied by using the angular spectrum method of an electromagnetic beam. Physical images of the longitudinal components of evanescent waves are illustrated and compared with those of the transverse components from the vectorial structure. Our results indicate that the relative weight integrated over the transverse plane of the evanescent wave depends strongly on the number of the polarization topological charges. The shapes of the intensity profiles of the longitudinal components are different from those of the transverse components, and it can be manipulated by changing the initial SoP of the field cross-section. The longitudinal component of evanescent wave dominates the near-field region. In addition, it also leads to three-dimensional shape variations of the optical field and the optical spin angular momentum flux density distributions.

Derivation the Schemes of Lateral and Vertical Dispersion Parameters: Application in Gaussian Plume Model

The main objective of this paper is to estimate the plume dispersion parameters in lateral direction (σy) and vertical direction (σz) by using power law wind speed and the scheme of eddy diffusivity in unstable condition. Comparison among our model and algebraic [1] and integral [2] formulations were held. We find that our model and two other models are in agreement with observed data.

Effects of the phase variation and high-order momentum transfer components of NN amplitude on p-~4He elastic scattering

Elastic scattering differential cross sections for a p- ~4He system are calculated within the framework of optical limit approximation of the Glauber multiple scattering model. Three different ranges for proton energy(E_(lab)), 19〈E_(lab)〈50 Me V, 100≤E_(lab)≤1730 Me V, and 45 ≤E_(lab)≤393 Ge V are considered. It is shown that the Pauli blocking fails to describe the data up to the proton energy, E_(lab)〈100 Me V. For higher proton energies, a qualitative agreement is obtained. The observed elastic scattering differential cross section is nicely reproduced in the whole range of scattering angles in the center of mass system up to Θ_(c.m.)〈200° for 19〈E_(lab) ≤100 Me V when the effect of both the nucleon–nucleon(NN) phase variation parameter γNN and higher-order momentum transfer components(λ_n; n = 1 and 2) of(NN) elastic scattering amplitude is included. In the range of 200 E_(lab) 1730 Me V, introducing λ_n plays a significant role in describing the data up to the momentum transfer, q^2≤1:2(Ge V/c)~2.Moreover, it is found that considering only the effect of phase variation parameter, cNN, improved the agreement in the region of minima for elastic scattering differential cross section for 45≤E_(lab)≤393 Ge V. The values of cNNand kn as a function of incident proton energies are presented.

Vibrational, rotational, and triaxiality features in extended O(6) dynamical symmetry of IBM using three-body interactions

The shape transition between the vibrational U(5)and deformed c-unstable O(6)dynamical symmetries of sd interacting boson model has been investigated by considering a modified O(6)Hamiltonian,providing that the coefficients of the Casimir operator of O(5)are N-dependent,where N is the total number of bosons.The modified O(6)Hamiltonian does not contain the number operator of the d boson,which is responsible for the vibrational motions.In addition,the deformation features can be achieved without using the SU(3)limit by adding to the O(6)dynamical symmetry the three-body interaction[QQQ]^(0),where Q is the O(6)symmetric quadrupole operator.Moreover,triaxiality can be generated through the inclusion of the cubic d-boson interaction[d+d+d+]^(3)·∣ddd∣^(3).The classical limit of the potential energy surface(PES),which represents the expected value of the total Hamiltonian in a coherent state,is studied and examined.The modified O(6)model is applied to the even–even^124-132 Xe isotopes.The parameters for the Hamiltonian and the PESs are calculated using a simulated search program to obtain the minimum root mean square deviation between the calculated and experimental excitation energies and B(E2)values for a number of low-lying levels.A good agreement between the calculations and experiment results is found.

Disturbances Propagation in Supersonic Boundary Layers

Disturbances propagation processes are investigated in two-dimensional boundary layers for the case of strong viscous-inviscid interaction. The speed of upstream disturbances propagation as a function of specific heat ratio and Prandtl number is determined. Formula for speed propagation is developed on the basis of characteristics and subcharacteristics analysis corresponding to the gasdynamic wave processes and processes of convection and diffusion.

Dynamics of magnetic flux tubes and IR-variability of young stellar objects

We simulate the dynamics of slender magnetic flux tubes （MFTs） in the accretion disks of T Tauri stars. The dynamical equations of our model take into account aerodynamic and turbulent drag forces, and the radiative heat exchange between the MFT and ambient gas. The structure of the disk is calculated with the help of our MHD model of the accretion disks. We consider the MFTs formed at distances of 0.027 - 0.8 au from the star with various initial radii and plasma betas β0. The simulations show that MFTs with a weak magnetic field （β0 = 10） rise slowly with speeds less than the speed of sound. MFTs withβ0 = 1 form an outflowing magnetized corona above the disk. Strongly magnetized MFTs （β0 = 0.1） can cause outflows with velocities 20 - 50 km s-1. The tubes rise periodically over times from several days to several months according to our simulations. We propose that periodically rising MFTs can absorb stellar radiation and contribute to the IR-variability of young stellar objects.

Generalized quantum mechanical two-Coulomb-center problem (Demkov problem)

We present a new exactly solvable quantum problem for which the Schrtidinger equation allows for separation of variables in oblate spheroidal coordinates. Namely, this is the quantum mechanical two-Coulomb-center problem for the case of an imaginary intercenter parameter and complex conjugate charges are considered. Since the potential is defined by the two-sheeted mapping whose singularities are concentrated on a circle rather than at separate points, there arise additional possibilities in the choice of boundary conditions. A detailed classification of the various types of boundary-value problems is given. The quasi-radial equation leads to a new type of boundary value problem which has never been considered before. Results of the numerical calculations, which allow conclusions to be drawn about the structure of the energy spectrum, are shown. Possible physical applications are discussed.

Vibrational Nonequilibrium in the Hydrogen-Oxygen Reaction at Different Temperatures

A theoretical model of chemical and vibrational kinetics of hydrogen oxidation is suggested based on the consistent account for the vibrational nonequilibrium of HO2 radical which forms in result of bimolecular recombination H + O2 = HO2 in the vibrationally excited state. The chain branching H + O2 = O + OH and inhibiting H + O2 + M = HO2 + M formal reactions are considered (in the terms of elementary processes) as a general multi-channel process of forming, intramolecular energy redistribution between modes, relaxation, and monomolecular decay of the comparatively long-lived vibrationally excited HO2 radical which is capable to react and exchange of energy with another components of the mixture. The model takes into account the vibrational nonequilibrium for the starting (primary) H2 and O2 molecules, as well as the most important molecular intermediates HO2, OH, O2(1D), and the main reaction product H2O. The calculated results are compared with the shock tube experimental data for strongly diluted H2-O2 mixtures at 1000 T p < 4 atm. It is demonstrated that this approach is promising from the standpoint of reconciling the predictions of the theoretical model with experimental data obtained by different authors for various compositions and conditions using different methods. It is shown that the hydrogen-oxygen reaction proceeds in absence of vibrational equilibrium, and the vibrationally excited HO2 radical acts as a key intermediate in the principally important chain branching process. For T < 1500 K, the nature of hydrogen-oxygen reaction is especially nonequilibrium, and the vibrational nonequilibrium of HO2 radical is the essence of this process.

GPS and the Search for Axions

GPS, an excellent tool for geodesy, may serve also particle physics. In the presence of Earth’s magnetic field, a GPS photon may be transformed into an axion. The proposed experimental setup involves the transmission of a GPS signal from a satellite to another satellite, both in low orbit around the Earth. To increase the accuracy of the experiment, we evaluate the influence of Earth’s gravitational field on the whole quantum phenomenon. There is a significant advantage in our proposal. While the geomagnetic field B is low, the magnetized length L is very large, resulting into a scale (BL)2 orders of magnitude higher than existing or proposed reaches. The transformation of the GPS photons into axion particles will result in a dimming of the photons and even to a “light shining through the Earth” phenomenon.

Dark Neutrinos

Solar, atmospheric and reactor neutrino experiments established that neutrinos are massive. It is quite natural then to consider neutrinos as candidate particles for explaining the dark matter in halos around galaxies. We study the gravitational clustering of these neutrinos within a model of a massive core and a surrounding spherical neutrino halo. The neutrinos form a degenerate Fermi gas and a loaded polytropic equation is established. We solve the equation and we obtain the neutrino density in a galaxy, the size of the galaxy and the galactic rotational curves. The available data favor a neutrino with a mass around 10 eV. The consequent cosmological implications are examined.

Quantum Entanglement on Cosmological Scale

It has been indicated that relational logic may serve as the common foundation of quantum mechanics and string theory. A relation may be represented by a spinor and the Cartan-Penrose connection of spinor to geometry, allows to abstract geometry as the outcome of entangled relations-spinors. Our approach goes in parallel with Wheeler’s pregeometry, where pregeometry, the stage preceding geometry, is based on a calculus of relations-propositions. With a single spinor related to the null cone of Minkowski space-time, we search for the geometry when we couple a left-handed spinor and a right-handed spinor. We find that a Majorana-type coupling gives rise to the ordinary entanglement, while a Diractype coupling generates an extra dimension with two branes coexisting in the extra dimension. One brane hosts lefthanded particles (our brane), while the other brane hosts right-handed particles. A distinct phenomenology accompanies our proposal. The left-right symmetry is achieved with having two “mirror” branes and the neutrino appears as the ideal mediator between the branes. We may revisit also the dark matter, dark energy issues, with everything on the other brane and in the bulk appearing “dark” to us. During the brane collision all points are causally connected, making less pressing the inflationary scenario. Our scheme brings closer logic—quantum theory—cosmology, while space-time, rather than an abstract and an a priori construction, appears as the outcome of a quantum logical act.

Hartree-Fock Calculations of ¹⁶O and ⁴⁰Ca Nuclei Using Fish-Bone Potential

Hartree-Fock calculations are carried out to describe some properties of 16O and 40Ca nuclei using the two forms of fish-bone potential (I and II). A computer simulation search program has been introduced to solve this problem. The Hilbert space was restricted to three dimensional variational space spanned by single spherical harmonic oscillator orbits. Binding energies, root mean square radii and form factors are found to have a good fit with experimental data.

An Axion Interpretation of the ANITA Events

We suggest that the unusual events observed by the ANITA experiment originate from axion particles traversing the Earth. Under the influence of the geomagnetic field, the axion may oscillate into a photon and vice-versa. To amplify the axion transition into photon, we consider that the phenomenon takes place at resonance, where the effective photon mass is equal to the axion mass. This requirement fixes the axion mass at 44 eV. An axion at this mass scale reproduces the cold dark matter scenario. If our interpretation prevails, with the help of axions we can establish an axion tomography of the Earth.

Peculiarities of Calculating Bridges with Seismic Isolation Including Spherical Bearings and Hydraulic Dampers in Russia

The peculiarities of calculating isolated structures with spherical bearings are analyzed in this paper. Some of peculiarities are caused by the lack of data at the moment when engineering solutions had to be made, Other peculiarities are connected with physical peculiarities of the device behaviour. To provide the analysis of structure hehaviour under the condition of the lack of input information, two types of design models of seismic protection devices were considered. They are the dampers linearization and the modelling of real dampers by dry friction ones. The dampers linearization makes it possible to use the existing software for calculating linear strongly-damped systems. To calculate structures with dry friction dampers, a new software was worked out. In this case, the structure is described as a piecewise-linear system of a relay-type. The investigations of the structure oscillations take into account both horizontal and vertical components of earthquake input. Under this condition, horizontal oscillation equations of structures are the MaRie-Hill ones. The input and structure parameters which caused the structure instability are estimated. To exclude the structure instability, high damping devices should be used. These methods were used for seismic resistant analysis of bridges with spherical bearings and hydraulic dampers applied in Sochi.

Relation between the Actual and Estimated Maximum Ground Level Concentration of Air Pollutant and Its Downwind Locations

In this work we used the Gaussian plume model to calculate the actual maximum ground level concentration (MGLC) of air pollutant and its downwind location by using different systems of dispersion parameters and for different stack heights. An approximate formula for the prediction of downwind position that produces the MGLC of a pollutant based on the Gaussian formula was derived for different diffusion parameters. The derived formula was used to calculate the approximate MGLC. The actual and estimated values are presented in tables. The comparison between the actual and estimated values was investigated through the calculation of the relative errors. The values of the relative errors between the actual and estimated MGLC lie in the range from: 0 to 70.2 and 0 to 1.6 for Pasquill Gifford system and Klug system respectively. The errors between the actual and estimated location of the MGLC lies in the range from: 0.2 to 227 and 0.7 to 9.4 for Pasquill Gifford system and Klug system respectively.

Grand Canonical Approach to an Interacting Network

We consider a network composed of an arbitrary number of directed links. We employ a grand canonical partition function to study the statistical averages of the network in equilibrium. The Hamiltonian is composed of two parts: a “free” Hamiltonian H0 attributing a constant energy E to each link, and an interacting Hamiltonian Hint involving terms quadratic in the number of links. A Gaussian integration leads to a reformulated Hamiltonian, where now the number of links appears linearly. The reformulated Hamiltonian allows obtaining the exact behavior in limiting cases. At high temperatures the system reproduces the behavior of the free model, while at low temperatures the thermodynamic behavior is obtained by using a renormalized chemical potential, μeff = μ + l, where l is the strength of the interaction. We also resort to a mean field approximation, describing accurately the system over the entire range of all dynamical parameters. A detailed Monte-Carlo simulation verifies our theoretical expectations. We indicate that our model may serve as a prototype model to address a number of different systems.

Molecular Modeling of Chemicals Products Inhibitors of Growth Struvite Crystal

Struvite (MgNH4PO46H2O) crystals were produced by infection associated with urea generating organ- isms.The aim of this study is to examine the interactions between the enzyme urease and two inhibitors, the first is an inhibitor monoatomic: Aluminum and the second is a polyatomic: Citrate by the methods of molecular modeling: molecular mechanics, molecular dynamics (MM+, AMBER) and molecular docking (FleX). Supersaturated solutions induce crystallization by nucleation and subsequent crystal growth .The mechanisms for the formation of calcium phosphate urinary stones are still not understood. Chemicals prod- uct has been studied extensively as inhibitors and has been observed in the attachment of crystals to in vitro study. As a complement we have using an electron microscope Hitachi TM1000, we examined specimens of crystals struvite. The various figures show a set of grains of sizes of the order of 20 μm. The majority of these particles present regular forms. This suggests the crystal growing. This result to an alteration in the expression of these faces and the development of a characteristic architectural struvite morphology. Similar changes were observed in the presence of identical concentrations of citrate acid, and Alluminuium, emphasizing the unique interaction of phosphocitrate with the struvite crystal.

Acceleration of solar wind particles due to inertial Alfvén waves

Gaining an understanding of the effects and dynamics of the solar wind is crucial for the study of space weather,Earth's magnetosphere,spacecraft protection,the dynamics of the Solar System,and various other subjects.Observations show that Alfvén waves effectively transfer energy to resonant particles.This study demonstrates how inertial Alfvén waves deliver their energy to resonant plasma particles in different solar environments under certain conditions.The analysis shows that inertial Alfvén waves experience more rapid damping with increasing parallel wavenumber,ambient magnetic field strength,and particle number density,coupled with a decrease in temperature.The rate of energy transfer to resonant particles intensifies with higher temperatures and reduced parallel wavenumber and particle number density.Particles with higher initial velocities actively participate in Landau damping,especially in regions with a stronger ambient magnetic field.