Given the ubiquitous nature of infrastructure networks in today's society, there is a global need to understand, quantify, and plan for the resilience of these networks to disruptions. With the development of tran...
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The paper presents the method for processing of excitation-emission matrix of sea water and the allocation of the spectral characteristics of different types of colored dissolved organic matter (CDOM) and phytoplankto...
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We report on calculations of exciton nonlinearity in dielectric nanocomposites. The effect of various parameters on the spectrum of nonlinear increment to the refractive index, such as size and form factor of the nano...
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The time-dependent gas flows through axisymmetric porous objects with heterogeneous combustion sources are considered. The mathematical model, which describes the process, and the numerical method are proposed. The re...
The time-dependent gas flows through axisymmetric porous objects with heterogeneous combustion sources are considered. The mathematical model, which describes the process, and the numerical method are proposed. The regimes of heterogeneous combustion wave propagation in axisymmetric porous object with various location of ignition zones under forced filtration are investigated. It is shown that the gas tends to bend around the heated zone and flows through colder regions as in the case of two-dimensional plane flows.
The paper reports the study of photoluminescence (PL) of disc- and elliptical-shaped SiO2 nanoparticles exited by photons with energy lower than silica bandgap. Differences in the PL spectra are found to be associated...
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Using numerical experiment two-dimensional unsteady processes of heterogeneous combustion in porous objects under free convection have been investigated. Combustion is due to the exothermic reaction between the fuel i...
Using numerical experiment two-dimensional unsteady processes of heterogeneous combustion in porous objects under free convection have been investigated. Combustion is due to the exothermic reaction between the fuel in the porous solid medium and oxidizer contained in the gas flowing through the porous object. In considered porous objects the gas pressure at object permeable boundaries is known but the flow rate and velocity of the gas at these boundaries are unknown, so the flow rate of oxidant, which enters into the reaction zone in porous object, regulates itself. Various objects with combustion zones resulting from natural and man-made disasters (in particular, peatlands, coal dumps, landfills) can be modeled, in terms of mechanics, as such porous objects. An original numerical method, based on a combination of explicit and implicit finite-difference schemes, is used for investigating the two-dimensional time-dependent combustion waves in considered porous objects. It has been revealed that when the natural convection takes place, the vortex-type gas flows can occur in the combustion zone and in its vicinity. It has been revealed that sometimes the complex gas flows within the porous object under natural convection are able to restrict the oxidant supply into the combustion zone and to extinguish the fire.
Temperature influence on optical and structural properties of nanocomposite structures based on cadmium sulfide quantum dots in silicate matrix was investigated. The mechanism of occurrence of reversible laser-induced...
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Temperature influence on optical and structural properties of nanocomposite structures based on cadmium sulfide quantum dots in silicate matrix was investigated. The mechanism of occurrence of reversible laser-induced absorption is proposed. It was found that annealing of nanocomposite up to 120 °C leads to substantial change of its absorption and luminescence spectra caused by transformation of quantum dot crystal lattice from amorphous to sphalerite. The nanocomposite with the sphalerite lattice QDs does not possess the effect of the photo-induced absorption.
The effect of electrostatic field on optical properties of silicate nanocomposite with cadmium sulfide quantum dots was investigated. It was found that the electrostatic field causes quantum dot orientation along the ...
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The effect of electrostatic field on optical properties of silicate nanocomposite with cadmium sulfide quantum dots was investigated. It was found that the electrostatic field causes quantum dot orientation along the field force lines leading to changes in the polarized components of the luminescence spectrum. The influence of field force line direction on photoinduced absorption characteristics arised from λ = 405.9 nm laser radiation exposure to nanocomposite was shown.
Stationary gas flow through the porous heat-releasing object with known gas pressure difference at opened boundaries of the object and unknown gas flow rate with accounting the inertial component of resistance is cons...
Stationary gas flow through the porous heat-releasing object with known gas pressure difference at opened boundaries of the object and unknown gas flow rate with accounting the inertial component of resistance is considered. The analytical solution of this problem is obtained under certain simplifying conditions and analyzed in a wide range of problem parameters. Deviation of the gas temperature and velocity, which is defined as difference between values with and without accounting the quadratic term in motion equation, is investigated. It is shown that taking into account the quadratic velocity in motion equation can significantly impact on the problem solution even at relative small pressure difference at the objects boundaries. It is shown analytically that when taking into account the inertial component of resistance, the gas filtration velocity has an asymptotic dependence from pressure difference at opened boundaries.
New approach to organize fluorescent sensor system for determination of metal ions in aqueous solutions was presented. The approach is based on modification of hydrophilic polymer with sensitive fluorescent indicators...
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New approach to organize fluorescent sensor system for determination of metal ions in aqueous solutions was presented. The approach is based on modification of hydrophilic polymer with sensitive fluorescent indicators. Possibility to register Cu2+ ions by analyzing of luminescence excitation spectra and lifetimes of the sensitive coating is presented.
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