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Pb growth on a clean vicinal Si(557) surface at room temperature was studied using Scanning Tunneling Microscopy. The Pb film growth occurred in accordance with the Stranski-Krastanov scenario. The anisotropic wedge-shaped Pb-islands were observed on the top of a wetting layer. DFT simulations revealed the electron energy oscillations as a function of the island thickness agrees with the electronic growth model. The out-of-plane (111) Pb island consisted of stacked 2 nm thick layers. Based on the DFT simulations and proposed one-dimensional model, it was shown that the layers were separated by the twin boundaries. The energy of formation of twin boundary between the 2 nm layers exceeded the energy gain due to the quantum confinement effect. However, the electron standing wave at the Fermi level in the 2 nm layer made the hcp position of the Pb adatom on the Pb(111) surface favorable. The seed of the twin boundary formation was realized via occupation of the hcp position by the Pb adatom and dimers of adatoms on the Pb(111) surface. The adatom separation in dimers was controlled by an indirect interaction through conductive electrons at the Fermi level of the 2 nm layer of Pb. The completion of the Pb(111) atomic layer growth was achieved by an unusual collective superdiffusive mechanism in the wetting layer and on the top of the Pb nanoisland surface. A new mechanism of twinning boundary formation based on quantum effects in a system of conducive electrons was proposed. Graphical Abstract

The system of maintenance of the formation pressure is associated with the appearance of technogenic fractures near injection wells, which leads to sharp water cut of the extracted oil. Geomechanic simulators also leave out variations in the hydrodynamic fluxes due to adsorption and keeping of disperse particles in the porous medium. The quasi-one-dimensional model of the fracture development dynamics developed on the basis of mechanics of multiphase media allows one to take account of these effects. The numerical solution of these equations makes it possible to predict to a high precision the geometric parameters of a fracture at different moments of time.

The present paper considers the possibility of improving the neural network forecast for a power reactor operating in a daily load schedule. We have prepared two simplified one-dimensional models of a VVER reactor: one as the reactor itself and another as its calculation model including several types of deviations from the reactor model for simulating the calculation error. A simple single-layer neural network is trained by comparing data obtained from the calculation and reactor models. The trained neural network effectively refines the results of the calculated forecast for the reactor model beyond the training time interval.

Humid air turbine cycle (HAT) has potential of electrical efficiencies comparable to combined cycle, with lower investment cost and NO x emission. The typical heat exchanger network of HAT consists of intercooler (if there is), aftercooler, recuperator, economizer and humidifier, which brings higher efficiency but makes the system more complex. To simplify HAT layout, a novel humidifier concept is proposed by integrating the aftercooler into traditional counter-current humidifier. Based on this concept, a one-dimensional model including pressure drop and exergy calculation is established to distinguish the thermodynamic and hydrodynamic characteristics, and then the structural parameters, such as the number of rows and columns, tube diameter, pitch and type for a micro HAT are identified. The results show that the aftercool-humidifier plays the same role as original aftercooler and humidifier, and can match the in-tube air, out-tube air and water stream well with lower volume. In the case of micro HAT cycle, the volume of heat and mass transfer area can be reduced by 47% compared with traditional design. The major thermal resistance occurred in the convection heat transfer process inside the tube; however, using enhanced tube cannot effectively improve the compactness of device.

The paper is devoted to the theoretical analysis of the effects of boundary conditions on the solutions of the system of one-dimensional (1D) hemodynamics. The integral inequalities, which realize the energy inequalities for the solutions of initial-boundary-value problems, are obtained. It is demonstrated that the unphysical unbounded solutions can take place for the case of bounded functions from boundary conditions. For the periodic boundary conditions, the integral estimation illustrates the correct behavior of the solution. For this case of boundary conditions, the effective Fourier method for the analytical solution is proposed. The analytical solutions, obtained by this approach, can be used for the comparison of different 1D blood-flow models. The results obtained in the paper allow for an the alternatively view of the stated boundary conditions and can explain some problems, which can arise in numerical simulations. They expand the possibilities of the application of analytical methods in the field of blood-flow simulation. The results can be useful for the specialists on blood-flow modeling.

The asymptotic behavior of the eigenvalues of the Neumann problem for a second-order elliptic equation in a thin finite cylinder with a periodic family of fine resonators (an acoustic waveguide with rigid walls) is studied. The main purpose is to construct an asymptotics of the coefficient in the homogenized differential operator. Its principal term does not depend on the shape of the resonators, but the first correction term includes the polarization coefficient of an infinite cylinder with a resonator of unit size. Properties of the polarization coefficient are studied, which is defined as the constant in the expansion of a linearly growing solution of the homogeneous problem in the perturbed cylinder at infinity. The obtained asymptotic expansions are substantiated by using a refined one-dimensional model and Poincaré’s asymptotically exact inequalities.

The Loess Plateau is one land-atmosphere coupling hotspot. Soil moisture has an influence on atmospheric boundary layer development under specific early-morning atmospheric thermodynamic structures. This paper investigates the sensitivity of atmospheric convection to soil moisture conditions over the Loess Plateau in China by using the convective triggering potential (CTP)—humidity index (HIlow) framework. The CTP indicates atmospheric stability and the HIlow indicates atmospheric humidity in the low-level atmosphere. By comparing the model outcomes with the observations, the one-dimensional model achieves realistic daily behavior of the radiation and surface heat fluxes and the mixed layer properties with appropriate modifications. New CTP-HIlow thresholds for soil moisture-atmosphere feedbacks are found in the Loess Plateau area. By applying the new thresholds with long-time scales sounding data, we conclude that negative feedback is dominant in the north and west portion of the Loess Plateau; positive feedback is predominant in the south and east portion. In general, this framework has predictive significance for the impact of soil moisture on precipitation. By using this new CTP-HIlow framework, we can determine under what atmospheric conditions soil moisture can affect the triggering of precipitation and under what atmospheric conditions soil moisture has no influence on the triggering of precipitation.

Because of the depletion of fossil fuels and because of its increasing cost, waste has been used as alternative fuels in cement rotary kilns for several years. In order to fulfil the requirements of environmental protection and quality of the final product, it is necessary to understand and quantify the different processes occurring in the kiln. The aim of our work is to develop a mathematical model of the processes occurring in the kiln. This model will rely on the coupling between a CFD model and homemade software. More precisely, the CFD model, which will be fully three-dimensional will account for the homogeneous processes taking place in the freeboard of the bed of material being processed. This bed of material will be at the center of the second model which will represent it as a 1D plug flow reactor. In the present work, we focus on this 1D model. We first give insights on the main assumptions on which the model relies, and information on the reaction pathway leading to the production of cement. Indeed, it is considered that the bed is composed of a mixture of CaCO 3 , MgCO 3 , Al 2 O 3 , SiO 2 , Fe 2 O 3 , MgO, CaO, C 2 S, C 3 A, C 4 AF and C 3 S undergoing thermochemical transformation. The bed under consideration is also composed of biomass (agricultural residues). During its transformation (pyrolysis, combustion of volatiles, combustion of the pyrolysis residue), this material contributes to thermal equilibrium of the reactor, by carrying the energy associated to its complete combustion. In this paper, the different equations that translate into mathematical formalism the processes of transport of the bed as well as mass and energy balance are also presented. The results show that the cement obtained complies with the requirements of Portland cements (73.06% of Silicates and 18.76% of Aluminates), the conversion of the biomass is total (100%), and the specific energy consumption is almost in conformity with the values of literature. Graphic Abstract

We propose a one-dimensional model for collecting lymphatics coupled with a novel Electro-Fluid-Mechanical Contraction (EFMC) model for dynamical contractions, based on a modified FitzHugh–Nagumo model for action potentials. The one-dimensional model for a deformable lymphatic vessel is a nonlinear system of hyperbolic Partial Differential Equations (PDEs). The EFMC model combines the electrical activity of lymphangions (action potentials) with fluid-mechanical feedback (circumferential stretch of the lymphatic wall and wall shear stress) and lymphatic vessel wall contractions. The EFMC model is governed by four Ordinary Differential Equations (ODEs) and phenomenologically relies on: (1) environmental calcium influx, (2) stretch-activated calcium influx, and (3) contraction inhibitions induced by wall shear stresses. We carried out a stability analysis of the stationary state of the EFMC model. Contractions turn out to be triggered by the instability of the stationary state. Overall, the EFMC model allows emulating the influence of pressure and wall shear stress on the frequency of contractions observed experimentally. Lymphatic valves are modelled by extending an existing lumped-parameter model for blood vessels. Modern numerical methods are employed for the one-dimensional model (PDEs), for the EFMC model and valve dynamics (ODEs). Adopting the geometrical structure of collecting lymphatics from rat mesentery, we apply the full mathematical model to a carefully selected suite of test problems inspired by experiments. We analysed several indices of a single lymphangion for a wide range of upstream and downstream pressure combinations which included both favourable and adverse pressure gradients. The most influential model parameters were identified by performing two sensitivity analyses for favourable and adverse pressure gradients.

From “surreal” trajectories to which-way measurements, Basil Hiley had a lesson: claims of falsifying the Bohmian model do not withstand scrutiny provided the model is applied correctly. In this work we compute de Broglie-Bohm trajectories for particles tunneling in coupled waveguides relevant to a recent experiment having claimed to challenge the Bohmian model. We show that the Bohmian model – correctly applied – gives results identical to the standard quantum approach, first by working out a simple one-dimensional model, and then by computing Bohmian trajectories for the full two-dimensional problem representing a quantum particle propagating inside coupled waveguides. We further recall the contextual nature of the Bohmian trajectories whereby the trajectories of a closed system differ from the ones observed when an interaction with a measurement apparatus takes places.