Journal articles on the topic 'Generalized continuous media'
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1
Zhuravlev, Viktor. "Exactly integrable models of the wave interaction with continuous spectrum." Izvestiya VUZ. Applied Nonlinear Dynamics 9, no. 2 (2001): 76–81. http://dx.doi.org/10.18500/0869-6632-2001-9-2-76-81.
Abstract:
Interaction with a continuous spectrum in inhomogeneous media is constructed the Laks representation of exactly integrable model of the wave by the generalized Lagrange identities method for the conjugated equations. The general analysis of the obtained equations and ways of their use in theoretical and applied physical problems of non-linear wave processes are carried out.
2
Gasilov, V. A., A. S. Boldarev, O. G. Olkhovskaya, D. S. Boykov, Yu S. Sharova, N. O. Savenko, and A. M. Kotelnikov. "MARPLE: software for multiphysics modelling in continuous media." Numerical Methods and Programming (Vychislitel'nye Metody i Programmirovanie) 24, no. 4 (September 29, 2023): 316–38. http://dx.doi.org/10.26089/nummet.v24r423.
Abstract:
The research code MARPLE was originally created to model high-speed dynamic processes caused by the action of high-intensity energy fluxes on matter. At present, it is a universal tool able to solve various continuum mechanics problems. The implemented physical models are the following: single-fluid two-temperature MHD model of plasma dynamics, including electron-ion energy exchange and generalized Ohm’s law; model of electrical and thermal conductivity taking into account the anisotropy in the magnetic field; radiative heat transfer: models pertinent to optically thin as well as optically thick media: techniques for taking into account radiative cooling losses, spectral multigroup diffusion transfer, laser radiation propagation etc.; model of multicomponent flow. The MARPLE code utilises modern computational technologies based on block structured and unstructured meshes. MARPLE works as MPI application for modern HPC systems. The paper presents examples of problems in plasma dynamics, magnetohydrodynamics, astrophysics, and solid thermomechanics solved by means of the MARPLE code. Исследовательский код MARPLE изначально создавался для моделирования высокоскоростных динамических процессов, вызванных воздействием на вещество интенсивных потоков энергии. В настоящее время это универсальный инструмент, способный решать различные задачи механики сплошных сред. Реализованы следующие физические модели: одножидкостная двухтемпературная МГД-модель динамики плазмы, включающая электрон-ионный обмен энергией и обобщенный закон Ома; модель электро- и теплопроводности с учетом анизотропии в магнитном поле; радиационный теплообмен: модели, относящиеся как к оптически тонким, так и к оптически толстым средам: методы учета радиационных потерь на охлаждение, спектральный многогрупповой диффузионный перенос, распространение лазерного излучения и т. д.; модель многокомпонентного течения. В коде MARPLE используются современные вычислительные технологии, основанные на блочно-структурированных и неструктурированных сетках. MARPLE работает как приложение MPI для современных высокопроизводительных вычислительных систем. В работе приведены примеры задач динамики плазмы, магнитогидродинамики, астрофизики и термомеханики твердого тела, решенных с помощью кода MARPLE.
3
Gasilov, Vladimir Anontol’evich, Aleksey Sergeevich Boldarev, Olga Gourgenovna Olkhovskaya, Dmitri Sergeevich Boykov, Yulia Sergeevna Sharova, Nikita Olegovych Savenko, and Alexey Mikhailovich Kotelnikov. "MARPLE: software for multiphysics modelling in continuous media problems." Keldysh Institute Preprints, no. 37 (2023): 1–40. http://dx.doi.org/10.20948/prepr-2023-37.
Abstract:
The research code MARPLE was originally created to model high-speed dynamic processes caused by the action of high-intensity energy fluxes on matter. At present, it is a universal tool able to solve various continuum mechanics problems. The implemented physical models are the following: single-fluid two-temperature MHD model of plasma dynamics, including electron-ion energy exchange and generalized Ohm's law; model of electrical and thermal conductivity taking into account the anisotropy in the magnetic field; radiative heat transfer: models pertinent to optically thin as well as optically thick media: techniques for taking into account radiative cooling losses, spectral multigroup diffusion transfer, laser radiation propagation etc.; model of multicomponent flow. Calculations are performed using wide-range equations of state, transport and optical data. The MARPLE code utilises modern computational technologies based on block structured and unstructured meshes consisting of tetrahedral, hexahedral, prismatic elements and their combinations. The solvers implement conservation laws using high-resolution techniques. We apply the physical splitting to solve the governing system. The object-oriented approach to software design is used, as well as methods of object and generic programming (C++ implementation language). Design of computational domains is provided by means of integrated SALOME open source CAD-CAE system. Marple works as MPI application for modern HPC systems. The paper presents examples of problems in plasma dynamics, magnetohydrodynamics, astrophysics, and solid thermomechanics solved by means of the MARPLE code.
4
Eisa Ali Alhazmi, Shareefa. "New Model for Solving Mixed Integral Equation of the First Kind with Generalized Potential Kernel." Journal of Mathematics Research 9, no. 5 (August 21, 2017): 18. http://dx.doi.org/10.5539/jmr.v9n5p18.
Abstract:
New technique model is used to solve the mixed integral equation (\textbf{MIE}) of the first kind, with a position kernel contains a generalized potential function multiplying by a continuous function and continuous kernel in time, in the space $L_{2} (\Omega )\times C[0,T],\, 0\leq T<1$, $\Omega$ is the domain of integration and $T$ is the time. The integral equation arises in the treatment of various semi-symmetric contact problems, in one, two, and three dimensions, with mixed boundary conditions in the mechanics of continuous media. The solution of the \textbf{MIE }when the kernel of position takes the potential function form, elliptic function form, Carleman function and logarithmic kernel are discussed and obtain in this work. Moreover, many special cases are derived.
5
Pai, David M. "Generalized f-k (frequency‐wavenumber) migration in arbitrarily varying media." GEOPHYSICS 53, no. 12 (December 1988): 1547–55. http://dx.doi.org/10.1190/1.1442436.
Abstract:
Migration requires one‐way wave continuation. In the spatial domain, one‐way wave equations are derived based on various approximations to an assumed dispersion relation. In the frequency‐wavenumber domain, the well known f-k method and the phase‐shift method are strictly valid only within homogeneous models and layered models, respectively. In this paper, a frequency‐wavenumber domain method is presented for one‐way wave continuation in arbitrarily varying media. In the method, the downward continuation is accomplished, not with plane waves individually as in the f-k or the phase‐shift method, but with the whole spectrum of plane waves simultaneously in order to account for the coupling among the plane waves due to lateral inhomogeneity. The method is based on a matrix integral equation. The method has the following merits: (1) The method is a generalization of the f-k and the phase‐shift methods, valid in arbitrarily varying models. (2) The method has physical interpretations in terms of upgoing and downgoing plane waves, and as such the method has well defined steps leading from full‐wave continuation (two‐way wave) to one‐way wave continuation for migration. (3) The method is rigorous; the only approximations in the method—other than the one‐way wave approximation necessary for migration—are the discretization of a continuous system (which is necessary in computer methods) and imperfections associated with the limited spatial aperture of the data; as such, the method can achieve high solution accuracy. (4) The method can be fast, since computations are mainly matrix‐vector multiplications, which are easily vectorizable. In particular, compared to spatial domain methods, I contend that the method is (1) more rigorous in one‐way wave theory, (2) more accurate in migration of high‐dip events, and (3) faster for smooth models. I applied the method to a few examples of zero‐offset data migration, including imaging a point diffractor below a dipping interface, migration with sharp lateral variations in velocity, and migration with smooth lateral variations in velocity.
6
Gutlyanskii, Vladimir, Olga Nesmelova, Vladimir Ryazanov, and Artyem Yefimushkin. "Logarithmic potential and generalized analytic functions." Ukrainian Mathematical Bulletin 18, no. 1 (March 9, 2021): 12–36. http://dx.doi.org/10.37069/1810-3200-2021-18-1-2.
Abstract:
The study of the Dirichlet problem in the unit disk $\mathbb D$ with arbitrary measurable data for harmonic functions is due to the famous dissertation of Luzin [31]. Later on, the known monograph of Vekua \cite{Ve} has been devoted to boundary-value problems (only with H\"older continuous data) for the generalized analytic functions, i.e., continuous complex valued functions $h(z)$ of the complex variable $z=x+iy$ with generalized first partial derivatives by Sobolev satisfying equations of the form $\partial_{\bar z}h\, +\, ah\, +\ b{\overline h}\, =\, c\, ,$ where it was assumed that the complex valued functions $a,b$ and $c$ belong to the class $L^{p}$ with some $p>2$ in smooth enough domains $D$ in $\mathbb C$. The present paper is a natural continuation of our previous articles on the Riemann, Hilbert, Dirichlet, Poincar\'{e} and, in particular, Neumann boundary-value problems for quasiconformal, analytic, harmonic, and the so-called $A-$harmonic functions with boundary data that are measurable with respect to logarithmic capacity. Here, we extend the corresponding results to the generalized analytic functions $h:D\to\mathbb C$ with the sources $g$ : $\partial_{\bar z}h\ =\ g\in L^p$, $p>2\,$, and to generalized harmonic functions $U$ with sources $G$ : $\triangle\, U=G\in L^p$, $p>2\,$. This paper contains various theorems on the existence of nonclassical solutions of the Riemann and Hilbert boundary-value problems with arbitrary measurable (with respect to logarithmic capacity) data for generalized analytic functions with sources. Our approach is based on the geometric (theoretic-functional) interpretation of boundary-values in comparison with the classical operator approach in PDE. On this basis, it is established the corresponding existence theorems for the Poincar\'{e} problem on directional derivatives and, in particular, for the Neumann problem to the Poisson equations $\triangle\, U=G$ with arbitrary boundary data that are measurable with respect to logarithmic capacity. These results can be also applied to semi-linear equations of mathematical physics in anisotropic and inhomogeneous media.
7
Das, Debraj, and Luca Giuggioli. "Dynamics of lattice random walk within regions composed of different media and interfaces." Journal of Statistical Mechanics: Theory and Experiment 2023, no. 1 (January 1, 2023): 013201. http://dx.doi.org/10.1088/1742-5468/aca8f9.
Abstract:
Abstract We study the lattice random walk dynamics in a heterogeneous space of two media separated by an interface and having different diffusivity and bias. Depending on the position of the interface, there exist two exclusive ways to model the dynamics: (a) Type A dynamics whereby the interface is placed between two lattice points, and (b) Type B dynamics whereby the interface is placed on a lattice point. For both types, we obtain exact results for the one-dimensional generating function of the Green’s function or propagator for the composite system in unbounded domain as well as domains confined with reflecting, absorbing, and mixed boundaries. For the case with reflecting confinement in the absence of bias, the steady-state probability shows a step-like behavior for the Type A dynamics, while it is uniform for the Type B dynamics. We also derive explicit expressions for the first-passage probability and the mean first-passage time, and compare the hitting time dependence to a single target. Finally, considering the continuous-space continuous-time limit of the propagator, we obtain the boundary conditions at the interface. At the interface, while the flux is the same, the probability density is discontinuous for Type A and is continuous for Type B. For the latter we derive a generalized version of the so-called leather boundary condition in the appropriate limit.
8
Ladovskii, Igor V., Petr S. Martyshko, Alexander G. Tsidaev, and Denis D. Byzov. "A Method for Quantitative Interpretation of Stationary Thermal Fields for Layered Media." Geosciences 10, no. 5 (May 22, 2020): 199. http://dx.doi.org/10.3390/geosciences10050199.
Abstract:
A new method to solve thermal conjugacy problems is presented for layered models with a thermal conductivity jump at their boundaries. The purpose of this method is to approximate the inverse thermal conductivity coefficient, which has breaks, by using a combination of step functions. A generalized continuous operator is constructed in a continuous space of piecewise–homogeneous media. We obtained an analytical solution for the stationary problem of heat conjugacy in the layered model with finite thickness and with Dirichlet–Neumann conditions at the external boundaries. An algorithm was constructed for downward continuation of the heat flux to depths that correspond to the top of the mantle layer. The advantages of this method are illustrated by testing the crustal seismic, gravity and geothermal data of a study area in the Urals and neighboring regions of Russia. We examined statistical relations between density and thermal parameters and determined heat flux components for the crust and the mantle. The method enables a downward continuation of the heat flux to the base of the upper mantle and allows us to determine the thermal effects of the lateral and vertical features of deep tectonic structures.
9
Misra, Anil, Luca Placidi, and Daria Scerrato. "A review of presentations and discussions of the workshop Computational mechanics of generalized continua and applications to materials with microstructure that was held in Catania 29–31 October 2015." Mathematics and Mechanics of Solids 22, no. 9 (August 29, 2016): 1891–904. http://dx.doi.org/10.1177/1081286516649654.
Abstract:
A report on the workshop Computational mechanics of generalized continua and applications to materials with microstructure (Catania 29–31 October 2015) is provided. The constructive atmosphere that was present at the workshop in 2012 and the Euromech Colloquium in 2014, both in Cisterna di Latina, was repeated for this workshop in Catania. The objective of this meeting was to bring together experts within the CNRS International Associate Laboratory (LIA) Francois Cosserat–Tullio Levi Civita Coss & Vita in order to discuss topics of common interest. Particularly, the workshop was dedicated to the following projects of LIA: (i) computational mechanics of generalized continua; and (ii) nonlinearity and stability in continuous media. Also subjects related to the application of generalized continua to multiscale and smart materials were discussed. Approximately 25 Coss & Vita LIA members and other experts (mostly from France and Italy) gathered together, including PhD students and those students from the Scuola Superiore di Catania.
10
Othman, M. I., and Y. Q. Song. "Reflection and refraction of thermo-viscoelastic waves at the interface between two micropolar viscoelastic media without energy dissipation." Canadian Journal of Physics 85, no. 7 (July 1, 2007): 797–812. http://dx.doi.org/10.1139/p07-072.
Abstract:
Reflection and refraction of a plane harmonic wave at the interface between two viscoelastic media are studied under generalized thermo-viscoelastic theory. Using potential function, the governing equations reduce to two fourth-order ifferential equations. Coefficient ratios of reflection and refraction of different waves with the angle of incidence are obtained using continuous boundary conditions. By numerical calculations, the variation of coefficient ratios of reflection and refraction with the angle of incidence are illustrated graphically for aluminium–epoxy and magnesium crystal micropolar viscoelastic materials. Also, the effects of viscous and micropolar elastic are illustrated by numerical results in the theory of thermo-viscoelasticity without energy dissipation. PACS No.: 62.20.Dc
11
Gavrilieva, Uygulana, Maria Vasilyeva, and Eric T. Chung. "Generalized Multiscale Finite Element Method for Elastic Wave Propagation in the Frequency Domain." Computation 8, no. 3 (July 7, 2020): 63. http://dx.doi.org/10.3390/computation8030063.
Abstract:
In this work, we consider elastic wave propagation in fractured media. The mathematical model is described by the Helmholtz problem related to wave propagation with specific interface conditions (Linear Slip Model, LSM) on the fracture in the frequency domain. For the numerical solution, we construct a fine grid that resolves all fracture interfaces on the grid level and construct approximation using a finite element method. We use a discontinuous Galerkin method for the approximation by space that helps to weakly impose interface conditions on fractures. Such approximation leads to a large system of equations and is computationally expensive. In this work, we construct a coarse grid approximation for an effective solution using the Generalized Multiscale Finite Element Method (GMsFEM). We construct and compare two types of the multiscale methods—Continuous Galerkin Generalized Multiscale Finite Element Method (CG-GMsFEM) and Discontinuous Galerkin Generalized Multiscale Finite Element Method (DG-GMsFEM). Multiscale basis functions are constructed by solving local spectral problems in each local domains to extract dominant modes of the local solution. In CG-GMsFEM, we construct continuous multiscale basis functions that are defined in the local domains associated with the coarse grid node and contain four coarse grid cells for the structured quadratic coarse grid. The multiscale basis functions in DG-GMsFEM are discontinuous and defined in each coarse grid cell. The results of the numerical solution for the two-dimensional Helmholtz equation are presented for CG-GMsFEM and DG-GMsFEM for different numbers of multiscale basis functions.
12
Leleka, S. V. "GENERALIZED MATHEMATICAL MODEL OF PHYSICAL FIELDS OF TECHNOLOGICAL REDISTRIBUTIONS OF MANUFACTURING ELECTROGRAPHITE PRODUCTS." Energy Technologies & Resource Saving, no. 2 (June 20, 2021): 28–43. http://dx.doi.org/10.33070/etars.2.2021.03.
Abstract:
A generalized mathematical model of the physical fields of the main technological redistributions of electrographite products is developed, which is based on a continuous-discrete approach to the description of nonlinear behavior of solids, liquids and gases, and bulk media. It is shown that the continuous formulation of physical processes in the technology of carbongraphite production is based on the Euler frame of reference and may include the following equations: conservation of mass, momentum and energy, electrical conductivity in the vortex-free approximation of electric potential and transport of chemical components of combustion reactions. The discrete formulation of physical processes in bulk materials used in the technology of production of carbon graphite products is based on the Lagrangian frame of reference and may include the following equations: translational and rotational motion and energy. The application of the generalized mathematical model for construction or refinement of mathematical and numerical models of separate redistributions for performance of the numerical analysis of physical fields and parameters of processes and the equipment on examples of pressing of "green" electrode preparations and theoretical research of effective thermophysical properties of loose carbonaceous materials. On the basis of the developed generalized statement, the complex of separate mathematical models of such redistributions of production of electrographite production as: calcination of carbonaceous materials in electrocalciners, gasification of carbonaceous materials in the equipment of rotary calcination furnaces is also formulated and specified, burning and graphitization of electrographite blanks. Bibl. 40, Fig. 4.
13
Xue, Bing Bing, Hong Yu Xu, Zhu Mu Fu, and Qing Yong Sun. "Reflection and Refraction of Longitudinal Displacement Wave at Interface between Two Micropolar Elastic Solid." Advanced Materials Research 139-141 (October 2010): 214–17. http://dx.doi.org/10.4028/www.scientific.net/amr.139-141.214.
Abstract:
Using the model of generalized micropolar magneto-thermo-elasticity, reflection and refraction of longitudinal displacement wave at interface of two welded micropolar elastic media are studied. The model can be applied to the coupled theory as well as to five generalizations, such as L-S theory, G-L theory, H-I theory, G-N theory of type (II) and C-T theory. And if some parameters in this model are taken as given values, we can easily deduce the known models of Kelvin-Voigt model and other generalized micropolar/magneto/thermo/viscoelastic theory model. Using continuous conditions at the interface, the amplitude ratios of reflected and refracted micropolar magneto-thermoelastic longitudinal displacement waves, longitudinal microrotational waves and the coupled transverse and microrotational waves are studied for incident longitudinal displacement wave. The numerical results show that the effect of magnetic field is very significant on the amplitude ratios.
14
Xu, Hong Yu, Bing Bing Xue, and Zhu Mu Fu. "Frequency Equations of Magneto-Thermoviscoelastic Surface Wave." Advanced Materials Research 97-101 (March 2010): 479–83. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.479.
Abstract:
The model of the generalized linear micropolar magneto-thermoviscoelastic theory is presented in this paper. It can be applied to the coupled theory as well as to five generalizations, such as L-S theory, G-L theory, H-I theory, G-N theory of type (II) and C-T theory. If some parameters in this model are taken as given values, we can easily deduce the known models of Kelvin-Voigt model and other generalized micropolar/magneto/thermo/viscoelastic theory model. The magneto-thermo- viscoelastic waves at an interface between two micropolar viscoelastic solid mediums are discussed with the model. Using continuous conditions, the general frequency equations are obtained. Also as a validation, if one media is replaced by vacuum, we have deduced the frequency equation of Rayleigh wave. And if the problem is reduced to elastic case, it coincides with the results of Ewing et al.
15
Gutlyanskii, Vladimir, Olga Nesmelova, Vladimir Ryazanov, and Artem Yefimushkin. "Boundary value problems for the generalized analytic and harmonic functions." Proceedings of the Institute of Applied Mathematics and Mechanics NAS of Ukraine 33 (December 27, 2019): 66–82. http://dx.doi.org/10.37069/1683-4720-2019-33-5.
Abstract:
The study of the Dirichlet problem with arbitrary measurable data for harmonic functions is due to the famous dissertation of Luzin. Later on, the known monograph of Vekua has been devoted to boundary value problems (only with H\"older continuous data) for the generalized analytic functions, i.e., continuous complex valued functions $h(z)$ of the complex variable $z=x+iy$ with generalized first partial derivatives by Sobolev satisfying equations of the form $\partial_{\bar z}h\, +\, ah\, +\ bh\, =\, c\, ,$ where $\partial_{\bar z}\ :=\ \frac{1}{2}\left(\ \frac{\partial}{\partial x}\ +\ i\cdot\frac{\partial}{\partial y}\ \right),$ and it was assumed that the complex valued functions $a,b$ and $c$ belong to the class $L^{p}$ with some $p>2$ in the corresponding domains $D\subset \mathbb C$. The present paper is a natural continuation of our articles on the Riemann, Hilbert, Dirichlet, Poincare and, in particular, Neumann boundary value problems for quasiconformal, analytic, harmonic and the so-called $A-$harmonic functions with boundary data that are measurable with respect to logarithmic capacity. Here we extend the correspon\-ding results to the generalized analytic functions $h:D\to\mathbb C$ with the sources $g$ : $\partial_{\bar z}h\ =\ g\in L^p$, $p>2\,$, and to generalized harmonic functions $U$ with sources $G$ : $\triangle\, U=G\in L^p$, $p>2\,$. It was also given relevant definitions and necessary references to the mentioned articles and comments on previous results. This paper contains various theorems on the existence of nonclassical solutions of the Riemann and Hilbert boundary value problems with arbitrary measurable (with respect to logarithmic capacity) data for generalized analytic functions with sources. Our approach is based on the geometric (theoretic-functional) interpretation of boundary values in comparison with the classical operator approach in PDE. On this basis, it is established the corresponding existence theorems for the Poincare problem on directional derivatives and, in particular, for the Neumann problem to the Poisson equations $\triangle\, U=G$ with arbitrary boundary data that are measurable with respect to logarithmic capacity. These results can be also applied to semi-linear equations of mathematical physics in anisotropic and inhomogeneous media.
16
RODRÍGUEZ-BERMÚDEZ, PANTERS, and DAN MARCHESIN. "RIEMANN SOLUTIONS FOR VERTICAL FLOW OF THREE PHASES IN POROUS MEDIA: SIMPLE CASES." Journal of Hyperbolic Differential Equations 10, no. 02 (June 2013): 335–70. http://dx.doi.org/10.1142/s0219891613500124.
Abstract:
We study Riemann solutions for a system of two nonlinear conservation laws that models buoyancy-driven flow of three immiscible fluids in a porous medium, which do not exchange mass. We also assume that the fluids are incompressible and the flow occurs in the vertical spatial dimension. We consider the simplified case in which two of the three fluids have equal densities, obtaining the Riemann solutions by the wave curve method. As expected, the solutions contain waves traveling both upwards and downwards. The sequences of waves contain rarefactions, shocks (sometimes traveling with characteristic speed), and constant states. The shocks found in this work are proper or generalized Lax shock waves. The solutions we found are L1-continuous with respect to the initial data. Waves involving only two fluids often take part in three-phase flow Riemann solutions; this is the basis of a useful tool (the wedge construction) to obtain shocks separating states in distinct two-phase regimes having a common fluid. This tool is similar to fractional flow theory, or Oleinik's convex construction. In this investigation, the wave curve method from the theory of conservation laws is combined with numerical calculations.
17
Karazeeva, N. A. "Solvability of initial boundary value problems for equations describing motions of linear viscoelastic fluids." Journal of Applied Mathematics 2005, no. 1 (2005): 59–80. http://dx.doi.org/10.1155/jam.2005.59.
Abstract:
The nonlinear parabolic equations describing motion of incompressible media are investigated. The rheological equations of most general type are considered. The deviator of the stress tensor is expressed as a nonlinear continuous positive definite operator applied to the rate of strain tensor. The global-in-time estimate of solution of initial boundary value problem is obtained. This estimate is valid for systems of equations of any non-Newtonian fluid. Solvability of initial boundary value problems for such equations is proved under some additional hypothesis. The application of this theory makes it possible to prove the existence of global-in-time solutions of two-dimensional initial boundary value problems for generalized linear viscoelastic liquids, that is, for liquids with linear integral rheological equation, and for third-grade liquids.
18
Kara, Iryna. "Peculiarities of wave propagation processes in poroelastic media." Strength of Materials and Theory of Structures, no. 105 (November 30, 2020): 247–54. http://dx.doi.org/10.32347/2410-2547.2020.105.247-254.
Abstract:
During analyzing of wave propagation processes in the fluid-saturated porous media unlike the theory of elasticity should be applied proposed by Biot the two phase model of media in which porous the solid elements are belonging to the first phase and the elements of pores fluid filler are belong to the second phase. Sometimes, for solving problems three phase model are used in which porous skeleton is partially saturated by fluid and partially saturated by gas. For the elastic porous media are introduced parameters such as: the porosity, the fluid viscosity, the permeability, the Biot coefficient of effective stress, the shear modulus and the bulk modulus, the mass densities and the total density of the porous material. Also the fundamental characteristic of the porous media is propagation of three different compression waves: the longitudinal fast wave, the second longitudinal slow wave, and the third transversal slow wave. One of the methods that are used for solving problems of poroelasticity is the Boundary Integral Equation Method. The algorithmic bases of it are the boundary analogues of Somiliani’s formulas for the solid displacements and the fluid pressure. The boundary integral equations and the fundamental solutions that are comprised in the poroelastic equations are different from the theory of elasticity analogues because the body with fluid-saturated pores is differ from the continuous homogeneous elastic media. Figures show that the graphs for the poroelastic region may be gradual approximated to the elastic analogues during changing some parameters. The biggest influence for displacements functions has change of the parameter R especially gradual increase of it for the some order. When for changing the functions graphs of the generalized derivatives one gradual increase of the parameter Q for one order is enough.
19
Mo, Chen, Jingjing Yin, Isaac Chun-Hai Fung, and Zion Tsz Ho Tse. "Aggregating Twitter Text through Generalized Linear Regression Models for Tweet Popularity Prediction and Automatic Topic Classification." European Journal of Investigation in Health, Psychology and Education 11, no. 4 (November 26, 2021): 1537–54. http://dx.doi.org/10.3390/ejihpe11040109.
Abstract:
Social media platforms have become accessible resources for health data analysis. However, the advanced computational techniques involved in big data text mining and analysis are challenging for public health data analysts to apply. This study proposes and explores the feasibility of a novel yet straightforward method by regressing the outcome of interest on the aggregated influence scores for association and/or classification analyses based on generalized linear models. The method reduces the document term matrix by transforming text data into a continuous summary score, thereby reducing the data dimension substantially and easing the data sparsity issue of the term matrix. To illustrate the proposed method in detailed steps, we used three Twitter datasets on various topics: autism spectrum disorder, influenza, and violence against women. We found that our results were generally consistent with the critical factors associated with the specific public health topic in the existing literature. The proposed method could also classify tweets into different topic groups appropriately with consistent performance compared with existing text mining methods for automatic classification based on tweet contents.
20
Abd-Alla, A. M., S. M. Abo-Dahab, and F. S. Bayones. "Rayleigh Waves in Generalized Magneto-Thermo-Viscoelastic Granular Medium under the Influence of Rotation, Gravity Field, and Initial Stress." Mathematical Problems in Engineering 2011 (2011): 1–47. http://dx.doi.org/10.1155/2011/763429.
Abstract:
The surface waves propagation in generalized magneto-thermo-viscoelastic granular medium subjected to continuous boundary conditions has been investigated. In addition, it is also subjected to thermal boundary conditions. The solution of the more general equations are obtained for thermoelastic coupling. The frequency equation of Rayleigh waves is obtained in the form of a determinant containing a term involving the coefficient of friction of a granular media which determines Rayleigh waves velocity as a real part and the attenuation coefficient as an imaginary part, and the effects of rotation, magnetic field, initial stress, viscosity, and gravity field on Rayleigh waves velocity and attenuation coefficient of surface waves have been studied in detail. Dispersion curves are computed numerically for a specific model and presented graphically. Some special cases have also been deduced. The results indicate that the effect of rotation, magnetic field, initial stress, and gravity field is very pronounced.
21
Maslov, B. P. "Application of a quasi-linear visco-elastic model for the creep of a non-heterogeneous geological media prediction." Bulletin of Taras Shevchenko National University of Kyiv. Series: Physics and Mathematics, no. 1 (2019): 122–25. http://dx.doi.org/10.17721/1812-5409.2019/1.28.
Abstract:
The problem of computer modeling of physical and mechanical processes in geological environments whose properties change in time is considered. The theoretical substantiation of approaches to the method of constructing micromechanical geophysical models of a porous medium with a liquid is proposed. The analysis of the current state of the problem of construction of calculated nonlinear models of multiphase geological environments is carried out and the necessity of using nonlinear rheology approaches is indicated. The results obtained earlier within the elastic linear and nonlinear domains of the behavior of the medium are generalized to the case of visco-elastic quasilinear behavior. The method of identification of creep parameters and permeability of multiphase porous medium and forecasting algorithms is proposed on the basis of developed numerical-analytical modeling of effective physical and mechanical properties of fluid-saturated rocks. Considered variants of random or periodic microstructure. The model is based on the use of the fundamental relations of the mechanics of the viscoelastic continuous medium, integral Fourier transforms and Laplace-Carson using the corresponding numerical algorithms.
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Luo, Jianping, Xingdong Liang, Qichang Guo, Tinggang Zhao, Jihao Xin, and Xiangxi Bu. "A Novel Estimation Method of Water Surface Micro-Amplitude Wave Frequency for Cross-Media Communication." Remote Sensing 14, no. 22 (November 20, 2022): 5889. http://dx.doi.org/10.3390/rs14225889.
Abstract:
Cross-media communication underpins many vital applications, especially in underwater resource exploration and the biological population monitoring domains. Water surface micro-amplitude wave (WSAW) frequency detection is the key to cross-media communication, where the WSAW frequency can invert the underwater sound source frequency. However, extracting the WSAW frequency information encounters many challenges in a real environment, such as low precision and symbol synchronization, leading to inaccurately estimating the WSAW frequency. Thus, this paper proposed a WSAW frequency estimation method based on an improved RELAX algorithm, incorporating two improvements. First, adding a nonlinear filter to the RELAX kernel function compensates for the filtered gain and enhances the WSAW frequency precision. Second, the improved RELAX kernel function is combined with the generalized inner product method to obtain the time distribution of the non-stationary signals, which is convenient for decoding. Several simulations and experiments applying our method on a Ka-band frequency modulated continuous wave (FMCW) radar demonstrate that our algorithm attains a better performance than traditional methods, e.g., periodogram and the RELAX algorithm. Using the improved algorithm affords to extract the frequency information of the WSAW signal accurately with a short sampling duration, further improving the performance indicators of the communication system, such as communication rate.
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Cirstoveanu, Catalin, Carmina Georgescu, Nicolae Ruxandra, Mihaela Bizubac, Eliza Cinteza, Corina Maria Vasile, Cristina Filip, and Irina Margarint. "Contrast-Associated Acute Kidney Injury Requiring Continuous Renal Replacement Therapy in A Neonate with Aortic Stenosis—A Case Report." Pediatric Reports 15, no. 2 (May 22, 2023): 323–32. http://dx.doi.org/10.3390/pediatric15020028.
Abstract:
Background: Acute kidney injury occurs commonly in the Neonatal Intensive Care Unit and is associated with increased mortality and morbidity. We report a case of a neonate with congenital heart disease who developed acute kidney injury after cardiac surgery, administration of iodinated contrast media for cardiac catheterization, and a combination of nephrotoxic drugs. Case report: A term neonate without a prenatal diagnosis of congenital heart disease and with a good postnatal transition was transferred at 13 days of life to the MS Curie Emergency Hospital for Children, Newborn Intensive Care Unit, from a regional hospital where he was admitted at 10 days of life with severe general status, respiratory distress, cyanosis, and arterial hypotension. The cardiac ultrasound detected critical aortic valve stenosis, hypoplastic descending aorta, acute heart failure, and pulmonary hypertension. The patient was intubated and mechanically ventilated and received antibiotherapy (meropenem, vancomycin, and colistin), inotropic and vasoactive support (epinephrine, norepinephrine, dopamine, and milrinone), and diuretic support (furosemide, aminophylline, and ethacrynic acid). A balloon aortic valvuloplasty was performed several hours after admission, but after two days the patient required reintervention by open heart surgery due to relapsing severe aortic stenosis. He developed oligo-anuria, generalized edema, and altered renal function tests on the second postoperative and fourth day post-contrast media administration. Continuous renal replacement therapy was initiated for 75 h, leading to almost instant improvement in blood pressure, then diuresis and creatinine levels. The patient required long-term treatment for heart, respiratory, and liver failure. He was discharged at almost four months of age with normal renal function tests, blood pressure, and good urine output without diuretic support. The literature review indicates that contrast-associated acute kidney injury (CA-AKI) requiring continuous renal replacement therapy is rare. Conclusions: Our current case proves that iodinated contrast media administration in a neonate with concomitant insults, such as cardiac surgery for a specific pathology, aortic stenosis, coarctation, arch stenosis, arterial hypotension, and administration of nephrotoxic drugs, may lead to severe kidney injury.
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Grechikhin, Valeriy V., Galina A. Galka, Anatoliy I. Ozerskiy, and Mikhail E. Shoshiashvili. "The method of dynamic operating modes investigation in electrohydraulic drive systems with improved accuracy of positioning executive elements." MATEC Web of Conferences 226 (2018): 04024. http://dx.doi.org/10.1051/matecconf/201822604024.
Abstract:
The article describes the method of dynamic operating modes investigation in electrohydraulic drive systems with improved accuracy of positioning output element. The method is the evolution of the fundamental positions of the mechanics of continuous media with moving boundaries as applied to the research of non-stationary processes accompanying the operation of hydraulic drive systems with piston hydraulic machines. The method is based on generalized modeling (technical, physical, mathematical and computer), takes into account the peculiarities of mutual influence of electric and hydraulic machines during their joint work as part of the electrohydraulic drive, which raises the level and adequacy of actuators simulation, as well as the reliability of the assessment of their technical condition. The method extends the field of research, improves the accuracy of the calculation of the positioning of the executive elements, taking into account the different dynamic modes of the drives under study.
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Saunders, Manu E., Jasmine K. Janes, and James C. O’Hanlon. "Moving On from the Insect Apocalypse Narrative: Engaging with Evidence-Based Insect Conservation." BioScience 70, no. 1 (December 18, 2019): 80–89. http://dx.doi.org/10.1093/biosci/biz143.
Abstract:
Abstract Recent studies showing temporal changes in local and regional insect populations received exaggerated global media coverage. Confusing and inaccurate science communication on this important issue could have counterproductive effects on public support for insect conservation. The insect apocalypse narrative is fuelled by a limited number of studies that are restricted geographically (predominantly the United Kingdom, Europe, the United States) and taxonomically (predominantly some bees, macrolepidoptera, and ground beetles). Biases in sampling and analytical methods (e.g., categorical versus continuous time series, different diversity metrics) limit the relevance of these studies as evidence of generalized global insect decline. Rather, the value of this research lies in highlighting important areas for priority investment. We summarize research, communication, and policy priorities for evidence-based insect conservation, including key areas of knowledge to increase understanding of insect population dynamics. Importantly, we advocate for a balanced perspective in science communication to better serve both public and scientific interests.
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Gutlyanskii, Volodymyr, Olga Nesmelova, Volodymyr Ryazanov, and Artyem Yefimushkin. "On boundary-value problems for semi-linear equations in the plane." Ukrainian Mathematical Bulletin 18, no. 3 (September 9, 2021): 359–88. http://dx.doi.org/10.37069/1810-3200-2021-18-3-5.
Abstract:
The study of the Dirichlet problem with arbitrary measurable data for harmonic functions in the unit disk $\mathbb{D}$ is due to the dissertation of Luzin. Later on, the known monograph of Vekua was devoted to boundary-value problems only with H\"{o}lder continuous data for generalized analytic functions, i.e., continuous complex-valued functions $f(z)$ of the complex variable $z=x+iy$ with generalized first partial derivatives by Sobolev satisfying equations of the form $\partial _{\bar{z}}f\,+\,af\,+\ b{% \overline{f}}\,=\,c\,$, where the complex-valued functions $a,b$, and $c$ are assumed to belong to the class $L^{p}$ with some $p>2$ in smooth enough domains $D$ in $\mathbb{C}$. Our last paper \cite{GNRY} contained theorems on the existence of nonclassical solutions of the Hilbert boundary-value problem with arbitrary measurable data (with respect to logarithmic capacity) for generalized analytic functions $f:D\to\mathbb{C}$ such that $\partial_{\bar z}f = g$ with the real-valued sources. On this basis, the corresponding existence theorems were established for the Poincar\'e problem on directional derivatives and, in particular, for the Neumann problem to the Poisson equations $\triangle\, U=G\in L^p, p>2$, with arbitrary measurable boundary data over logarithmic capacity. The present paper is a natural continuation of the article \cite{GNRY} and includes, in particular, theorems on the existence of solutions for the Hilbert boundary-value problem with arbitrary measurable data for the corresponding nonlinear equations of the Vekua type $\partial _{\bar{z}% }f(z)=h(z)q(f(z))$. On this basis, existence theorems were also established for the Poincar\'{e} boundary-value problem and, in particular, for the Neumann problem for the nonlinear Poisson equations of the form $\triangle \,U(z)=H(z)Q(U(z))$ with arbitrary measurable boundary data over logarithmic capacity. The Dirichlet problem was investigated by us for the given equations, too. Our approach is based on the interpretation of boundary values in the sense of angular (along nontangential paths) limits that are a conventional tool of the geometric function theory. As consequences, we give applications to some concrete semi-linear equations of mathematical physics arising from modelling various physical processes. Those results can also be applied to semi-linear equations of mathematical physics in anisotropic and inhomogeneous media.
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Nugmanova, N. "ASYMTOTIC PROPERTIES OF THE GENERALIZED SOLUTION OF NONLINEAR PROBLEM FOR THE PSEUDOPARABOLIC EQUATION WITH p,q-LAPLACIAN STRUCTURE." BULLETIN Series of Physics & Mathematical Sciences 70, no. 2 (June 30, 2020): 110–15. http://dx.doi.org/10.51889/2020-2.1728-7901.16.
Abstract:
The development of modern science and technology requires accurate and comprehensive mathematical modeling of physical and hydrodynamic processes of continuous media. For example, experimental studies show that the presence of even small amounts of polymeric substances in a viscous medium can significantly affect to motion of fluid. A comparison of the physical characteristics of water and weak aqueous solutions of polymers showed that at almost the same density and viscosity, these fluids sharply differ in their relaxation properties. In recent years, the investigation of solvability and qualitative properties such as blow up and extinction of a solution in a finite time, large time behavior of a solution of the problems in various statements for pseudo-parabolic equations has been rapidly developing. This is confirmed by publications have been publishing in world ranking scientific journals. This paper is devoted to the study of a mathematical model of the one-dimensional motion of a Kelvin-Voigt fluid with complex rheological properties, which describes by a nonlinear pseudo-parabolic equation (Sobolev type equation) with p-Laplacian. The study of pseudo-parabolic equations was first started by Sobolev in [1] for the linear version. In this work the asymptotic behavior of solutions of pseudo-parabolic equations at large times, in clearly, the properties of exponential and power-law decay of a solution are proved.
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Gutlyanskii, Vladimir, Vladimir Ryazanov, Olga Nesmelova, and Eduard Yakubov. "On the Hilbert problem for semi-linear Beltrami equations." Ukrainian Mathematical Bulletin 19, no. 4 (January 30, 2023): 489–516. http://dx.doi.org/10.37069/1810-3200-2022-19-4-4.
Abstract:
The presented paper is devoted to the study of the well-known Hilbert boundary-value problem for semi-linear Beltrami equations with arbitrary boundary data that are measurable with respect to logarithmic capacity. Namely, we prove here the corresponding results on the existence, regularity, and representation of its nonclassical solutions with a geometric interpretation of boundary values as the angular (along the nontangential paths) limits in comparison with the classical approach in PDE. For this purpose, we apply completely continuous operators by Ahlfors-Bers, first of all to obtain solutions of semi-linear Beltrami equations, generally speaking with no boundary conditions, and then to derive their representation through the solutions of the Vekua-type equations and the so-called generalized analytic functions with sources. Besides, we obtain similar results for nonclassical solutions of the Poincare boundary-value problem on directional derivatives and, in particular, of the Neumann problem with arbitrary measurable data to semi-linear equations of the Poisson type. The obtained results are applied to some problems of mathematical physics describing such phenomena as diffusion with physical and chemical absorption, plasma states, and stationary burning in anisotropic and inhomogeneous media.
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Guo, Peng, and George A. McMechan. "Compensating Q effects in viscoelastic media by adjoint-based least-squares reverse time migration." GEOPHYSICS 83, no. 2 (March 1, 2018): S151—S172. http://dx.doi.org/10.1190/geo2017-0235.1.
Abstract:
Low values of P- and S-wave quality factors [Formula: see text] and [Formula: see text] result in strong intrinsic seismic attenuation in seismic modeling and imaging. We use a linearized waveform inversion approach, by generalizing least-squares reverse time migration (LSRTM) for viscoelastic media ([Formula: see text]-LSRTM), to compensate for the attenuation loss for P- and S-images. We use the first-order particle velocity, stress, and memory variable equations, with explicit [Formula: see text] in the formulations, based on the generalized standard linear solid, as the forward-modeling operator. The linearized two-way viscoelastic modeling operator is obtained with modulus perturbations introduced for the relaxed P- and S-moduli. The viscoelastic adjoint operator and the P- and S-imaging conditions for modulus perturbations are derived using the adjoint-state method and an augmented Lagrangian functional. [Formula: see text]-LSRTM solves the viscoelastic linearized modeling operator for generating synthetic data, and the adjoint operator is used for back propagating the data residual. With the correct background velocity model, and with the inclusion of [Formula: see text] in the modeling and imaging, [Formula: see text]-LSRTM is capable of iteratively updating the P- and S-modulus perturbations, and compensating the attenuation loss caused by [Formula: see text] and [Formula: see text], in the direction of minimizing the data residual between the observed and predicted data. Compared with elastic LSRTM results, the P- and S-modulus perturbation images from [Formula: see text]-LSRTM have stronger (closer to the true modulus perturbation), and more continuous, amplitudes for the structures in and beneath low-[Formula: see text] zones. The residuals in the image space obtained using the correctly parameterized [Formula: see text]-LSRTM are much smaller than those obtained using the incorrectly parameterized elastic LSRTM. However, the data residuals from [Formula: see text]-LSRTM and elastic LSRTM are similar because elastic Born modeling with a weak reflector in the image produces similar reflection amplitudes with viscoelastic Born modeling with a strong reflector.
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Brovko, George L. "Tensors in Newtonian Physics and the Foundations of Classical Continuum Mechanics." Mathematical and Computational Applications 24, no. 3 (September 3, 2019): 79. http://dx.doi.org/10.3390/mca24030079.
Abstract:
In the Newtonian approach to mechanics, the concepts of objective tensors of various ranks and types are introduced. The tough classification of objective tensors is given, including tensors of material and spatial types. The diagrams are constructed for non-degenerate (“analogous”) relations between tensors of one and the same (any) rank, and of various types of objectivity. Mappings expressing dependence between objective tensor processes of various ranks and types are considered. The fundamental concept of frame-independence of such mappings is introduced as being inherent to constitutive relations of various physical and mechanical properties in the Newtonian approach. The criteria are established for such frame-independence. The mathematical restrictions imposed on the frame-independent mappings by the objectivity types of connected tensors are simultaneously revealed. The absence of such restrictions is established exclusively for mappings and equations linking tensors of material types. Using this, a generalizing concept of objective differentiation of tensor processes in time, and a new concept of objective integration, are introduced. The axiomatic construction of the generalized theory of stress and strain tensors in continuum mechanics is given, which leads to the emergence of continuum classes and families of new tensor measures. The axioms are proposed and a variant of the general theory of constitutive relations of mechanical properties of continuous media is constructed, generalizing the known approaches by Ilyushin and Noll, taking into account the possible presence of internal kinematic constraints and internal body-forces in the body. The concepts of the process image and the properties of the five-dimensional Ilyushin’s isotropy are generalized on the range of finite strains.
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Lim, Leonard Thomas S., Zypher Jude G. Regencia, J. Rem C. Dela Cruz, Frances Dominique V. Ho, Marcela S. Rodolfo, Josefina Ly-Uson, and Emmanuel S. Baja. "Assessing the effect of the COVID-19 pandemic, shift to online learning, and social media use on the mental health of college students in the Philippines: A mixed-method study protocol." PLOS ONE 17, no. 5 (May 3, 2022): e0267555. http://dx.doi.org/10.1371/journal.pone.0267555.
Abstract:
Introduction The COVID-19 pandemic declared by the WHO has affected many countries rendering everyday lives halted. In the Philippines, the lockdown quarantine protocols have shifted the traditional college classes to online. The abrupt transition to online classes may bring psychological effects to college students due to continuous isolation and lack of interaction with fellow students and teachers. Our study aims to assess Filipino college students’ mental health status and to estimate the effect of the COVID-19 pandemic, the shift to online learning, and social media use on mental health. In addition, facilitators or stressors that modified the mental health status of the college students during the COVID-19 pandemic, quarantine, and subsequent shift to online learning will be investigated. Methods and analysis Mixed-method study design will be used, which will involve: (1) an online survey to 2,100 college students across the Philippines; and (2) randomly selected 20–40 key informant interviews (KIIs). Online self-administered questionnaire (SAQ) including Depression, Anxiety, and Stress Scale (DASS-21) and Brief-COPE will be used. Moreover, socio-demographic factors, social media usage, shift to online learning factors, family history of mental health and COVID-19, and other factors that could affect mental health will also be included in the SAQ. KIIs will explore factors affecting the student’s mental health, behaviors, coping mechanism, current stressors, and other emotional reactions to these stressors. Associations between mental health outcomes and possible risk factors will be estimated using generalized linear models, while a thematic approach will be made for the findings from the KIIs. Results of the study will then be triangulated and summarized. Ethics and dissemination Our study has been approved by the University of the Philippines Manila Research Ethics Board (UPMREB 2021-099-01). The results will be actively disseminated through conference presentations, peer-reviewed journals, social media, print and broadcast media, and various stakeholder activities.
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Murashkin, E. V., T. K. Nesterov, and N. E. Stadnik. "УСЛОВИЯ СОВМЕСТНОСТИ В МОДЕЛЯХ ПОЛУИЗОТРОПНЫХ ТЕРМОУПРУГИХ ТЕЛ." Вестник Чувашского государственного педагогического университета им. И.Я. Яковлева. Серия: Механика предельного состояния, no. 1(55) (June 6, 2023): 102–9. http://dx.doi.org/10.37972/chgpu.2023.55.1.011.
Abstract:
In this paper, we discuss the compatibility conditions on the surfaces of weak and strong discontinuities propagating in continuous semi-isotropic thermoelastic media. To derive such boundary conditions, the well-known Yugonio–Hadamar theory, substantially developed by G. I. Bykovtsev, and generalized to the case of pseudotensor physical fields, is used. The questions of differentiation with respect to pseudoscalar time and its transformation under mirror reflections and space inversions are considered. First-order geometric and kinematic compatibility conditions are obtained in terms of pseudotensors. Compatibility conditions are derived for weak discontinuities of displacements and microrotations in a hemitropic micropolar continuum. Compatibility conditions are obtained for strong discontinuities in a semi-isotropic thermoelastic continuum. В настоящей работе обсуждаются условия совместности на поверхностях слабых и сильных разрывов, распространяющихся в сплошных полуизотропных термоупругих средах. Для вывода таких граничных условий примняется хорошо известная теория Югонио– Адамара, существенно развитая Г.И. Быковцевым, обобщенная на случай псевдотензорных физических полей. Рассматриваются вопросы дифференцирования по псевдоскалярному времени и его преобразования при зеркальных отражениях и инверсиях пространства. Получены геометрические и кинематические условия совместности первого порядка в терминах псевдотензоров. Выведены условия совместности для слабых разрывов перемещений и микровращений в полуизотропном микрополярном континууме. Получены условия совместности на сильных разрывах в полуизотропном термоупругом континууме.
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Bashir, Farhat, Farzana Rehman, Samina Ghaznavi, and Jamal Ara. "DIABETES MELLITUS;." Professional Medical Journal 24, no. 02 (February 14, 2017): 308–14. http://dx.doi.org/10.29309/tpmj/2017.24.02.523.
Abstract:
Diabetes mellitus is a modifiable risk factor for generalized atherosclerosis.Measurement of carotid intima media thickness by Doppler ultrasonography can be used tomeasure the extent of atherosclerosis. Objectives: To determine the association of carotidatherosclerosis in patients with type 2 diabetes mellitus and its relationship with glycemiccontrol. Study Design: Cross-sectional comparative study. Period: 12 months June 2015 toMay 2016. Setting: Creek General Hospital in the Department of Medicine and Radiology,Karachi, Pakistan. Method: The subjects were selected from diabetic patients presenting tothe Out-Patient Department and controls from their attendants. All subjects had a detailedhistory, physical examination and laboratory investigations recorded. The variables includedage, gender, weight, BMI, blood pressures, fasting and post prandial blood sugars, HbA1cand lipid profile. All individuals underwent B-mode ultrasound for carotid Doppler studies. Asingle operator conducted all the Doppler studies. The carotid intima media thickness wasmeasured and the presence of carotid plaque was recorded for each subject. The data wasentered on SPSS ver 20.0. Numbers and percentages were calculated for categorical datawhile mean±standard deviation was calculated for continuous data. The carotid intima mediathickness and its association with diabetes were analyzed by Student’s t test. P-value of <0.05was considered significant. Among the diabetic patients the relationship of glycemic controland carotid intima media thickness was analyzed through student’s t-test. P-value of <0.05was considered significant. The association of presence of carotid plaque for diabetic and nondiabeticsubjects was assessed by Chi-square test. P-value of <0.05 was taken as significant.Association of carotid plaque among diabetic patients with satisfactory and unsatisfactoryglycemic control was also assessed through the Chi-square test and p-value of<0.05 wasconsidered significant. Result: Out of the total study population of 237 subjects, which consistedof 119 diabetic and 118 normal controls, there were 105 male and 132 female patients. Themean fasting blood sugar was 113.3±55.2 mg/dl, mean random blood sugar was 185.9±102.0mg/dl, mean HbA1c was 6.98±2.5 %. Mean ±SD of carotid intima media thickness was0.91±0.17 mm. Results revealed that diabetes has significant association with the thicknessof carotid intima media (p-value<0.000). A total of 28 individuals (11.8%) had a carotid intimamedia thickness that was classified as a localized carotid artery plaque. The presence of carotidplaque also showed a significant association with the presence of diabetes. The degree ofglycemic control showed no relationship with carotid intima media thickness. The presenceof carotid plaque also showed no association with degree of glycemic control. Conclusion:CIMT measured by Doppler ultrasonography was found to be significantly associated with thepresence of diabetes mellitus. There was no relationship of glycemic control with CIMT amongthe diabetic patients.
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Litovchenko, V., and M. Gorbatenko. "INHOMOGENEOUS DIFFERENTIAL EQUATIONS OF VECTOR ORDER WITH DISSIPATIVE PARABOLICITY AND POSITIVE GENUS." Bukovinian Mathematical Journal 10, no. 2 (2022): 144–55. http://dx.doi.org/10.31861/bmj2022.02.10.
Abstract:
Parabolicity in the sense of both Petrosky and Shilov has a scalar character. It is not able to take into account the specificity of the heterogeneity of the environment. In this regard, in the early 70-s, S.D. Eidelman proposed the so-called $\vec{2b}$-parabolicity, which is a natural generalization of the Petrovsky parabolicity for the case of an anisotropic medium. A detailed study of the Cauchy problem for equations with such parabolicity was carried out in the works of S.D. Eidelman, S.D. Ivasishena, M.I. Matiichuk and their students. An extension of parabolicity according to Shilov for the case of anisotropic media is $\{\vec{p},\vec h\}$-parabolicity. The class of equations with such parabolicity is quite broad, it includes the classes of Eidelman, Petrovskii, and Shilov and allows unifying the classical theory of the Cauchy problem for parabolic equations. In this work, for inhomogeneous $\{\vec{p},\vec h\}$-parabolic equations with vector positive genus, the conditions under which the Cauchy problem in the class of generalized initial functions of the type of Gelfand and Shilov distributions will be correctly solvable are investigated. At the same time, the inhomogeneities of the equations are continuous functions of finite smoothness with respect to the set of variables, which decrease with respect to the spatial variable, and are unbounded with the integrable feature with respect to the time variable.
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Savelyeva, I. Yu. "Variational Formulation of the Mathematical Model of Stationary Heat Conduction with Account for Spatial Nonlocality." Herald of the Bauman Moscow State Technical University. Series Natural Sciences, no. 2 (101) (April 2022): 68–86. http://dx.doi.org/10.18698/1812-3368-2022-2-68-86.
Abstract:
In creating and using new structurally sensitive materials, it is essential to construct mathematical models which make it possible to describe the materials’ behavior in widely changing external influences. Modeling of non-local media is a class of methods of generalized continuum mechanics. The capability of analyzing mathematical models of a continuous medium can be extended through variational methods. The paper describes the construction of a functional for the problem of stationary heat conduction in a homogeneous body, taking into account the effects of nonlocality and with a temperature-independent heat conduction coefficient. A variational formulation used in the case of a linear problem in combination with acceptable admissible functions allowed us to quantify this effect. The study gives an example of using the variational formulation, which takes into account the influence of the spatial nonlocality of the stationary heat conduction process on the parameters that determine the well-known phenomenon of thermal explosion with an exponential temperature dependence of the volumetric heat release rate in the plate. The quantitative analysis was carried out for two versions of the function that is admissible for the constructed integral functional and describes the possible temperature distribution over the thickness of the plate under consideration. Having compared the obtained results, we opted for the admissible function, as its use leads to a smaller difference between the maximum value of the parameter characterizing the intensity of heat release in the plate and the known result found with no account for the influence of spatial nonlocality
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Alavi, Nazanin, Callum Stephenson, Megan Yang, Amirhossein Shirazi, Yijia Shao, Anchan Kumar, Caitlin S. Yee, et al. "Determining the Efficacy of Electronic Cognitive Behavioral Therapy for Generalized Anxiety Disorder Compared to Pharmaceutical Interventions: Protocol for a Quasi-Experimental Study." JMIR Research Protocols 10, no. 5 (May 27, 2021): e27772. http://dx.doi.org/10.2196/27772.
Abstract:
Background Generalized anxiety disorder (GAD) is an extremely prevalent and debilitating mental health disorder. Currently, the gold standard treatment for GAD is cognitive behavioral therapy (CBT) and/or pharmacotherapy. The most common medications used to treat GAD are selective serotonin reuptake inhibitors and selective norepinephrine reuptake inhibitors. While CBT is the gold standard treatment for GAD, it is costly, time-consuming, and often inaccessible. Fortunately, the electronic delivery of CBT (e-CBT) has emerged as a promising solution to address these barriers. e-CBT has shown to offer comparable results to in-person CBT while improving accessibility for patients and time efficiency for clinicians. Objective This study aims to investigate the treatment efficacy of e-CBT compared to and in conjunction with pharmacotherapy for GAD. Methods This study will use a quasi-experimental design to allow patients the freedom to choose which treatment modality they would like to receive. Participants with a diagnosis of GAD will be enrolled in 1 of 3 possible treatment arms: (1) e-CBT, (2) medication, or (3) a combination of e-CBT and medication. The e-CBT program will include a 12-week psychotherapy program delivered through the Online Psychotherapy Tool—a secure, cloud-based, digital mental health platform. The treatment efficacy of e-CBT will be compared with that of medication alone and medication in combination with e-CBT. Results The study received ethics approval in April 2019 and participant recruitment began in June 2019. Participant recruitment has been conducted through social media advertisements, physical advertisements, and physician referrals. To date, 146 participants (e-CBT: n=53; medication: n=49; combination: n=44) have been recruited. Data collection is expected to conclude by June 2021, and data analysis is expected to be completed by October 2021. Linear regression (for continuous outcomes) and binomial regression (for categorical outcomes) analysis will be conducted using interpretive qualitative methods. Conclusions If either the efficacy of e-CBT is shown to be comparable to that of medication or the effects of both treatments are augmented when used in tandem, these findings could have major implications on the mental health care system. e-CBT is a more accessible and affordable treatment that could increase mental health care capacity 4-fold if proven viable. Trial Registration ClinicalTrials.gov NCT04478526; https://clinicaltrials.gov/ct2/show/NCT04478526 International Registered Report Identifier (IRRID) DERR1-10.2196/27772
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Zhukova, Liudmila V. "Express-Evaluation of Industrial Enterprises Operations in Moscow with Universal Composite Indicator." Economics of Contemporary Russia, no. 4 (December 29, 2021): 89–97. http://dx.doi.org/10.33293/1609-1442-2021-4(95)-89-97.
Abstract:
Recent years were a transformation period of the analytic systems to support management decision-making on continuously available open data away from official periodic reports. In this regard, the system of control and supervision of management objects by the state controlling bodies is changing, new sources of information are included; monitoring of the external environment and media space is introduced. The author proposes an approach to the formation of a generalized key indicator for rapid assessment of the object of management (on the example of an industrial enterprise) on the basis of open data from the Internet. The object of the research is developing universal comprehensive indicator for rapid assessment of the compliance of the economic object of management on the part of regulators or relevant services on the basis of structured and unstructured data from the Internet. Scientific novelty of the study is to propose the concept of building a universal comprehensive indicator (UCI) based on a logical function that uses an extended set of arguments, including both continuous and discrete variables. Transformation into the values of the indicator is proposed using the logical rules, given the requirements for the control object from the regulators. Main results of the work: the concept of constructing universal comprehensive indicator allowing to get an express assessment of the state of the object in control was developed. The algorithm was tested to assess the need and feasibility for the state authorities in the financial assistance of the Moscow industrial enterprise. The approach in this research is applicable to current monitoring of the situation due to official reporting at the tactical level of management.
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Nooruddin, Shanila, Tooba Jawed Khan, Sidrah Nausheen, Fouzia Nasir, Ghulam Abbas Shaikh, Asif Shaikh, Ayesha Sadiqa, et al. "COVID-19 associated anxiety and perceived risk among the pregnant women: a cross-sectional study." International Journal Of Community Medicine And Public Health 9, no. 3 (February 28, 2022): 1150. http://dx.doi.org/10.18203/2394-6040.ijcmph20220670.
Abstract:
Background: COVID-19 is an infectious disease, categorized as a global pandemic. Daily implications and coping strategies of pregnant women with coronavirus outbreak is currently unknown. This study will assess their knowledge, attitude, and practices (KAP), risk perceptions, anxiety and concerns related to COVID-19.Methods: A hospital-based cross-sectional survey was conducted in Karachi. Self-reported questionnaires including KAP, generalized anxiety disorder (GAD) scale and perception of pregnancy risk questionnaire were administered. Descriptive statistics were calculated for continuous variables and were reported as mean ± standard deviation. Frequencies and percentages were computed for categorical variables. Pearson correlation was calculated to explore linear associations among the perception of pregnancy risk, age, body mass index (BMI), and gestation. All data analysis was done using STATA 16.0.Results: The 575 pregnant women were enrolled with an average age of 26.07 years and 27.22±8.99 gestational age. Their knowledge showed that 92.2% knew that coronavirus causes COVID-19 and 72.30% knew the importance of wearing masks. Regarding attitudes, 96.3% felt safe to breastfeed their newborns, 80.20% considered changing their birth method whereas 54.6% were not concerned about the outbreak and around 70-80% cancelled their social gatherings. 72% trusted healthcare frontline staff with their struggle towards COVID-19. The 43.82% women were more anxious (scoring ≥7) and 56.17% were less anxious (<7) on GAD scale. The mean score for perceived risk for baby and mother was 22.95±13.72 and 19.40±0.57 respectively.Conclusions: Considering the burden of COVID-19, pregnant women’s perception is a major contributor to her and her baby’s health and wellbeing. Well-planned strategies by media, healthcare providers and government would significantly support such pregnant women during COVID-19.
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Vodovozov, A. M. "Nonlinear Pulse-Time Conversion in Radioisotope Devices: Analysis and Application Possibilities." Devices and Methods of Measurements 12, no. 2 (June 25, 2021): 133–38. http://dx.doi.org/10.21122/2220-9506-2021-12-2-133-138.
Abstract:
The paper considers the operation of radioisotope measuring devices under dynamic conditions, when the Poisson pulse flux at the output of the radiation detector becomes unsteady and the nonlinearity of the calibration curve of the device, the stochasticity of the radiation signal and the inertia of the meter significantly complicate the task of estimating the measured physical parameter. of the device and analysis of the possibility of its application for linearization of the characteristics of the device, increasing the speed of the devices and solving the measuring problem in real time.The process of nonlinear transformation of the radiation signal in the system is analyzed on the basis of the assumption about the exponential distribution of the intervals between the pulses of the information flow at the output of the radiation detector. A generalized algorithm for the synthesis of a given transformation function of a time-pulse computing device of a radioisotope device has been developed according to its mathematical description. To describe the transformation function given by a set of points, it is proposed to use its approximation by a power series.The proposed calculation formulas are verified by modeling in the Scilab program on a specific example of linearization of the curve of a radioisotope altimeter with a given tabular calibration characteristic. The results obtained confirm the expediency of using time-pulse computing devices for linearizing the conversion curve of radioisotope devices in real time.Carrying out calculations according to the proposed algorithms by means of modern microelectronics opens up new possibilities for expanding the field of application of radioisotope devices in dynamic problems of industrial flaw detection, measuring the parameters of object movement, thickness of rolled products and coatings, in devices for continuous monitoring of liquid media.
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Калинюк, Юрий Владимирович. "DESIGNING CHANGES IN SECONDARY VOCATIONAL EDUCATION SYSTEM IN THE REGION: CLUSTER APPROACH." Pedagogical Review, no. 6(40) (December 8, 2021): 84–94. http://dx.doi.org/10.23951/2307-6127-2021-6-84-94.
Abstract:
Показаны современные направления развития системы среднего профессионального образования (СПО) в России. Обозначены особенности СПО Томской области и стратегические цели его преобразования в контексте их взаимосвязи с приоритетами социально-экономического развития региона. Представлено экспертно-теоретическое обоснование целесообразности использования кластерного подхода для развития региональных систем СПО. Аргументированы необходимость и продуктивность управления изменениями в региональной системе СПО средствами кластерной политики. Предложено проектное видение нового дизайна инфраструктуры СПО Томской области в логике кластерной политики. Доказательно заданы базовые характеристики кластеров двух видов: образовательного и образовательно-отраслевого, приведены научно обоснованные гипотезы о закономерностях их эффективного функционирования. Обоснованы проектные предложения, отражающие организационно-педагогические механизмы интеграции практик СПО и непрерывной профессионализации действующих кадров реального сектора экономики в кластерном формате. Обозначены способы такой интеграции. Предложено экспертное авторское видение условий реализации образовательного потенциала взаимодействия субъектов, включенных в кластерно-отраслевые сообщества. Обобщен имеющийся практический опыт, отражающий проектирование изменений в управлении развитием СПО на основе кластерного подхода в Томской области. Спрогнозированы социально-экономические и образовательные перспективы кластерно-сетевого взаимодействия в региональной практике СПО для решения актуальных и перспективных задач его развития на региональном уровне. Материалы статьи основаны на результатах образовательного проектирования и подготовлены при использовании исследовательских методов теоретического анализа, опроса, экспертного метода. The article discusses modern trends in Russia’s secondary vocational education (SPE) system development. Features of SPE in the Tomsk Region and strategic objectives of its transformation as opposed to their relationship with the priorities of the region’s socioeconomic advancement are outlined. An expert-theoretical justification of the expediency in using the cluster approach for the SPE regional system development is presented. Necessity and productivity in the SPE regional system change management by means of cluster policy are argued. A project vision of Tomsk Region’s SPO new infrastructure design in the logic of cluster policy is proposed. Basic characteristics of the clusters’ two types are educational and educational-industrial; scientifically substantiated hypotheses on the regularities of their effective functioning are proved. Project proposals reflecting organizational and pedagogical mechanisms of SPE practice integration and continuous professionalization of the current economy’s real sector personnel in a cluster format are substantiated. Paths of such integration are outlined. The authors’ expert vision of conditions for implementing educational potential in the interaction between the subjects included in the cluster-branch communities is offered. The current practical experience reflecting the design of changes in the SPO development management on the basis of cluster approach in the Tomsk Region is generalized. Socio-economic and educational prospects of cluster-network interaction in the SPO regional practice for solving urgent and prospective problems of its development at the regional level are predicted. Materials of the article are based on the results of educational design and prepared using research methods of theoretical analysis, survey, and the expert method.
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Endres, Anthony L., and Rosemary J. Knight. "Incorporating pore geometry and fluid pressure communication into modeling the elastic behavior of porous rocks." GEOPHYSICS 62, no. 1 (January 1997): 106–17. http://dx.doi.org/10.1190/1.1444110.
Abstract:
Inclusion‐based formulations allow an explicit description of pore geometry by viewing porous rocks as a solid matrix with embedded inclusions representing individual pores. The assumption commonly used in these formulations that there is no fluid pressure communication between pores is reasonable for liquid‐filled rocks measured at high frequencies; however, complete fluid pressure communication should occur throughout the pore space at low frequencies. A generalized framework is presented for incorporating complete fluid pressure communication into inclusion‐based formulations, permitting elastic behavior of porous rocks at high and low frequencies to be described in terms of a single model. This study extends previous work by describing the pore space in terms of a continuous distribution of shapes and allowing different forms of inclusion interactions to be specified. The effects of fluid pressure communication on the elastic moduli of porous media are explored by using simple models and are found to consist of two fundamental elements. One is associated with the cubical dilatation and governs the effective bulk modulus. Its magnitude is a function of the range of pore shapes present. The other is due to the extensional part of the deviatoric strain components and affects the effective shear modulus. This element is dependent on pore orientation, as well as pore shape. Using sandstone and granite models, an inclusion‐based formulation shows that large differences between high‐ and low‐frequency elastic moduli can occur for porous rocks. An analysis of experimental elastic wave velocity data reveals behavior similar to that predicted by the models. Quantities analogous to the open and closed system moduli of Gassmann‐Biot poroelastic theory are defined in terms of inclusion‐based formulations that incorporate complete fluid pressure communication. It was found that the poroelastic relationships between the open and closed system moduli are replicated by a large class of inclusion‐based formulations. This connection permits explicit incorporation of pore geometry information into the otherwise empirically determined macroscopic parameters of the Gassmann‐Biot poroelastic theory.
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Park, E., G. Schuller-Levis, and M. R. Quinn. "Taurine chloramine inhibits production of nitric oxide and TNF-alpha in activated RAW 264.7 cells by mechanisms that involve transcriptional and translational events." Journal of Immunology 154, no. 9 (May 1, 1995): 4778–84. http://dx.doi.org/10.4049/jimmunol.154.9.4778.
Abstract:
Abstract We previously reported that taurine chloramine (Tau-Cl) inhibits the production of both nitric oxide and TNF-alpha by activated RAW 264.7 cells. The current studies were conducted to gain insight into the mechanisms through which Tau-Cl exerts these effects. RAW 264.7 cells were activated by LPS (10 micrograms/ml) and rIFN-gamma (50 U/ml) in the absence or presence of either 0.8 mM Tau-Cl or taurine. Production of NO and TNF-alpha by RAW 264.7 cells was monitored: NO was measured spectrophotometrically as nitrite and TNF-alpha was measured by ELISA. Cell lysates were analyzed for the inducible form of nitric oxide synthase (iNOS) by Western blot analyses, and TNF-alpha and iNOS mRNAs were assessed by northern blot analyses. Tau-Cl inhibited transcription of the iNOS gene, or some earlier event in the signal transduction pathway, because iNOS protein and iNOS mRNA were undetected in lysates of cells activated in the continuous presence of Tau-Cl. In contrast, steady-state levels of TNF-alpha mRNA increased in the presence of Tau-Cl to at least the same extent as that in untreated activated cells and persisted for a longer period of time. Metabolic labeling experiments demonstrated that Tau-Cl inhibited translation of TNF-alpha mRNA because the presence of the presecretory 26-kDa form and the secreted 17-kDa form of TNF-alpha were greatly reduced in lysates and culture media, respectively, of cells activated in the presence of Tau-Cl. Inhibition of TNF-alpha synthesis by Tau-Cl is not the result of a generalized effect on protein synthesis because the amount of radiolabeled protein precipitated from metabolically labeled cells by TCA was unaffected by Tau-Cl, and cell viability was unaffected. The results of these studies demonstrate that Tau-Cl decreases production of tissue-damaging inflammatory mediators and thus may act as a physiologic modulator of macrophage function.
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Mohylnyk, A., L. Vishnikina, K. Tarasenko, S. Suprunenko, and A. Davydenko. "“COGNITIVE FRAGMENTATION” AS A CONSEQUENCE OF CLIP THINKING AND ITS IMPACT ON MODERN SOCIETY EVOLUTION." Актуальні проблеми сучасної медицини: Вісник Української медичної стоматологічної академії 24, no. 2 (May 20, 2024): 250–56. http://dx.doi.org/10.31718/2077-1096.24.2.250.
Abstract:
In today’s information-saturated world, individuals are inundated with verbal and visual messages, leading to the development of what is termed “clip thinking” as an adaptive response. This phenomenon, characterized by constant interaction with superficial and nonsensical texts, alongside continuous internet browsing, has profound implications beyond mere cognition. Clip thinking, a systemic issue, extends its influence beyond cognitive processes. Its roots lie in the transmission of information through modern gadgets, the ubiquity of the internet, and the prevalence of clip culture. Modern youth, constrained by the small screens of digital devices and the constant scrolling of text, are increasingly averse to engaging with complex material, resulting in decreased information retention and comprehension. This shift in information consumption habits has concerning implications for higher education. Many students rely heavily on electronic aids, neglecting memorization and overlooking the importance of understanding complex texts. Consequently, the prevalence of fragmented thinking among students leads to deficiencies in conceptual and critical thinking skills. Instead of engaging deeply with subject matter, students often resort to generalized concepts, overlooking causal connections. Carriers of clip thinking become vulnerable to any manipulations by the mass media, as the mosaic nature of their consciousness is capable perceive only what is happening right now and information provided through information and telecommunication gadgets without subjecting it to critical analysis. Hence, university lecturers face significant challenges as they endeavor to navigate the need for innovative teaching methodologies in light of the fragmented thinking prevalent among modern students. The searching for innovative teaching technologies should not solely aim at altering the thinking patterns of students with clip-like cognitive tendencies. Rather, the primary objective of modern educational technologies should be to foster the mental skills necessary for information analysis and synthesis, as well as the identification of similarities and differences, generalizations, and classifications within the information landscape. Hence, this topic retains its profound relevance in contemporary education.
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Endalamaw, Aklilu, Charles F. Gilks, and Yibeltal Assefa. "Socioeconomic inequality in adults undertaking HIV testing over time in Ethiopia based on data from demographic and health surveys." PLOS ONE 19, no. 2 (February 14, 2024): e0296869. http://dx.doi.org/10.1371/journal.pone.0296869.
Abstract:
Introduction HIV testing is the entry point to HIV prevention, care and treatment and needs continuous evaluation to understand whether all social groups have accessed services equally. Addressing disparities in HIV testing between social groups results in effective and efficient response against HIV prevention. Despite these benefits, there was no previous study on inequality and determinants over time in Ethiopia. Thus, the objective of this research was to examine socioeconomic inequality in individuals undertaking HIV testing over time, allowing for the identification of persistent and emerging determinants. Methods Data sources for the current study were the 2011 and 2016 Ethiopian Demographic Health Surveys. The 2016 population health survey is the one that Ethiopia used to set national AIDS response strategies; there was no other recent survey with HIV/AIDS-related indicators in Ethiopia. The final sample size for the current study was 28,478 for the year 2011 and 25,542 for the year 2016. The concentration curve and Erreygers’ concentration index were used to estimate socioeconomic inequality in HIV testing. Subsequently, decomposition analysis was performed to identify persistent and emerging contributors of socioeconomic inequality. Generalized linear regression model with the logit link function was employed to estimate the marginal effect, elasticity, Erreygers’ concentration index (ECI), and absolute and percentage contributions of each covariate. Results The concentration curve was below the line of equality over time, revealing the pro-rich inequality in HIV testing. The inequality was observed in both 2011 (ECI = 0.200) and 2016 (ECI = 0.213). A household wealth rank had the highest percentage contribution (49.2%) for inequality in HIV testing in 2011, which increased to 61.1% in 2016. Additional markers include listening to the radio (13.4% in 2011 and 12.1% in 2016), education status (8.1% in 2011 and 6.8% in 2016), and resident (-2.0% in 2011 and 6.3% in 2016). Persistent determinants of individuals undertaking HIV testing were age 20–34 years, geographic region, education status, marital status, religion, income, media exposure (listening to the radio, reading newspaper, watching television), knowledge about HIV/AIDS, and attitudes towards people living with HIV. Age between 35 and 44 years and urban residence emerged as new associated factors in 2016. Conclusions The higher HIV testing coverage was among individuals with higher socioeconomic status in Ethiopia. Socioeconomic inequality amongst individuals undertaking HIV testing was diverging over time. Household wealth rank, mass media exposure, education status, and resident took the largest share in explaining the disparity in individuals undertaking HIV testing between the lower and higher income groups. Therefore, interventions to equalise HIV testing coverage should take account of these determinants.
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Voronkov, Ivan A., and Aleksandr A. Kalashnikov. "Digital Correction of Readings Produced by Fluid Level Measurement Channels at NPPs Equipped with Sensors Having a Dead Zone." Vestnik MEI 2, no. 2 (2021): 119–25. http://dx.doi.org/10.24160/1993-6982-2021-2-119-125.
Abstract:
The introduction and development of computerized digital systems in modern power engineering has led in Russia to a full modernization of domestically produced nuclear power plant measurement systems. In particular, digital methods for correcting the readings of hydrostatic level sensors have been widely put in use since 2013. The experience gained from putting them in use was generalized in the reference and organizational and methodological literature in 2017. However, the subsequent results of preoperational adjustments carried out at newly designed nuclear power units and at those under construction have shown that some issues still remain unresolved in this application field. In particular, there is a need is to develop digital methods for correcting the readings produced by channels measuring the level of liquid media in pressurized process tanks if there occurs a sensor dead zone. The complexity of this problem is stemming from the fact that it is not possible to take the sensor dead zone into account by introducing a constant correction to the measurement channel readings in view of the technological process peculiarities. Thus, during the operation of nuclear power units, the water density in pressurized process tanks and vessels decreases from 980 to 590 kg/m3, and the vapor density increases from 0 to 100 kg/m3. Such changes give rise to complex thermal and physical interphase processes that occur under the conditions of large mass transfers of the vapor--water mixture. As a result, the sensor's dead zone boundary undergoes an essential change in the tank longitudinal section depending on the current values of the working fluid thermal and physical characteristics. To solve this problem, digital methods for online correction of measured level readings are proposed that take into account changes in the two-phase working medium (vapor--water) in the course of a continuous technological process. Nowadays, the introduction of digital methods for correcting the hydrostatic level sensor readings is especially relevant in connection with the development of industry programs aimed at increasing the capacity of newly designed and operating nuclear power units, which pose more demanding requirements to the accuracy of thermal and physical measurements and operational safety as a whole.
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Akinsolu, Mobayode O., and Khalil Zribi. "A Generalized Framework for Adopting Regression-Based Predictive Modeling in Manufacturing Environments." Inventions 8, no. 1 (January 29, 2023): 32. http://dx.doi.org/10.3390/inventions8010032.
Abstract:
In this paper, the growing significance of data analysis in manufacturing environments is exemplified through a review of relevant literature and a generic framework to aid the ease of adoption of regression-based supervised learning in manufacturing environments. To validate the practicality of the framework, several regression learning techniques are applied to an open-source multi-stage continuous-flow manufacturing process data set to typify inference-driven decision-making that informs the selection of regression learning methods for adoption in real-world manufacturing environments. The investigated regression learning techniques are evaluated in terms of their training time, prediction speed, predictive accuracy (R-squared value), and mean squared error. In terms of training time (TT), k-NN20 (k-Nearest Neighbour with 20 neighbors) ranks first with average and median values of 4.8 ms and 4.9 ms, and 4.2 ms and 4.3 ms, respectively, for the first stage and second stage of the predictive modeling of the multi-stage continuous-flow manufacturing process, respectively, over 50 independent runs. In terms of prediction speed (PS), DTR (decision tree regressor) ranks first with average and median values of 5.6784×106 observations per second (ob/s) and 4.8691×106 observations per second (ob/s), and 4.9929×106 observations per second (ob/s) and 5.8806×106 observations per second (ob/s), respectively, for the first stage and second stage of the predictive modeling of the multi-stage continuous-flow manufacturing process, respectively, over 50 independent runs. In terms of R-squared value (R2), BR (bagging regressor) ranks first with average and median values of 0.728 and 0.728, respectively, over 50 independent runs, for the first stage of the predictive modeling of the multi-stage continuous-flow manufacturing process, and RFR (random forest regressor) ranks first with average and median values of 0.746 and 0.746, respectively, over 50 independent runs, for the second stage of the predictive modeling of the multi-stage continuous-flow manufacturing process. In terms of mean squared error (MSE), BR (bagging regressor) ranks first with average and median values of 2.7 and 2.7, respectively, over 50 independent runs, for the first stage of the predictive modeling of the multi-stage continuous-flow manufacturing process, and RFR (random forest regressor) ranks first with average and median values of 3.5 and 3.5, respectively, over 50 independent runs, for the second stage of the predictive modeling of the multi-stage continuous-flow manufacturing process. All methods are further ranked inferentially using the statistics of their performance metrics to identify the best method(s) for the first and second stages of the predictive modeling of the multi-stage continuous-flow manufacturing process. A Wilcoxon rank sum test is then used to statistically verify the inference-based rankings. DTR and k-NN20 have been identified as the most suitable regression learning techniques given the multi-stage continuous-flow manufacturing process data used for experimentation.
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Ryazanov, Vladimir, and Ruslan Salimov. "On Hölder continuity of solutions of the Beltrami equations on the boundary." Proceedings of the Institute of Applied Mathematics and Mechanics NAS of Ukraine 32 (December 28, 2018): 104–14. http://dx.doi.org/10.37069/1683-4720-2018-32-11.
Abstract:
In the present paper, it is found conditions on the complex coefficient of the Beltrami equations with the degeneration of the uniform ellipticity in the unit disk under which their generalized homeomorphic solutions are continuous by Hölder on the boundary. These results can be applied to the investigations of various boundary value problems for the Beltrami equations. In a series of recent papers, under the study of the boundary value problems of Dirichlet, Hilbert, Neumann, Poincare and Riemann with arbitrary measurable boundary data for the Beltrami equations as well as for the generalizations of the Laplace equation in anisotropic and inhomogeneous media, it was applied the logarithmic capacity, see e.g. Gutlyanskii V., Ryazanov V., Yefimushkin A. On the boundary value problems for quasiconformal functions in the plane // Ukr. Mat. Visn. - 2015. - 12, no. 3. - P. 363-389; transl. in J. Math. Sci. (N.Y.) - 2016. - 214, no. 2. - P. 200-219; Gutlyanskii V., Ryazanov V., Yefimushkin A. On a new approach to the study of plane boundary-value problems // Dopov. Nats. Akad. Nauk Ukr. Mat. Prirodozn. Tekh. Nauki. - 2017. - No. 4. - P. 12-18; Yefimushkin A. On Neumann and Poincare Problems in A-harmonic Analysis // Advances in Analysis. - 2016. - 1, no. 2. - P. 114-120; Efimushkin A., Ryazanov V. On the Riemann-Hilbert problem for the Beltrami equations in quasidisks // Ukr. Mat. Visn. - 2015. - 12, no. 2. - P. 190–209; transl. in J. Math. Sci. (N.Y.) - 2015. - 211, no. 5. - P. 646–659; Yefimushkin A., Ryazanov V. On the Riemann–Hilbert Problem for the Beltrami Equations // Contemp. Math. - 2016. - 667. - P. 299-316; Gutlyanskii V., Ryazanov V., Yakubov E., Yefimushkin A. On Hilbert problem for Beltrami equation in quasihyperbolic domains // ArXiv.org: 1807.09578v3 [math.CV] 1 Nov 2018, 28 pp. As well known, the logarithmic capacity of a set coincides with the so-called transfinite diameter of the set. This geometric characteristic implies that sets of logarithmic capacity zero and, as a consequence, measurable functions with respect to logarithmic capacity are invariant under mappings that are continuous by Hölder. That circumstance is a motivation of our research. Let \(D\) be a domain in the complex plane \(\mathbb C\) and let \(\mu: D\to\mathbb C\) be a measurable function with \( |\mu(z)| \lt 1 \) a.e. The equation of the form \(f_{\bar{z}}\ =\ \mu(z) f_z \) where \( f_{\bar z}={\bar\partial}f=(f_x+if_y)/2 \), \(f_{z}=\partial f=(f_x-if_y)/2\), \(z=x+iy\), \( f_x \) and \( f_y \) are partial derivatives of the function \(f\) in \(x\) and \(y\), respectively, is said to be a Beltrami equation. The function \(\mu\) is called its complex coefficient, and \( K_{\mu}(z)=\frac{1+|\mu(z)|}{1-|\mu(z)|}\) is called its dilatation quotient. The Beltrami equation is said to be degenerate if \({\rm ess}\,{\rm sup}\,K_{\mu}(z)=\infty\). The existence of homeomorphic solutions in the Sobolev class \(W^{1,1}_{\rm loc}\) has been recently established for many degenerate Beltrami equations under the corresponding conditions on the dilatation quotient \(K_{\mu}\), see e.g. the monograph Gutlyanskii V., Ryazanov V., Srebro U., Yakubov E. The Beltrami equation. A geometric approach. Developments in Mathematics, 26. Springer, New York, 2012 and the further references therein. The main theorem of the paper, Theorem 1, states that a homeomorphic solution \( f:\mathbb D\to\mathbb D \) in the Sobolev class \( W^{1,1}_{\rm loc} \) of the Beltrami equation in the unit disk \(\mathbb D\) has a homeomorphic extension to the boundary that is Hölder continuous if \(K_{\mu}\in L^1(\Bbb D)\) and, for some \(\varepsilon_0\in(0,1)\) and \(C\in[1,\infty)\), $$ \sup\limits_{\varepsilon\in(0,\varepsilon_0)} \int_{\mathbb D\cap D(\zeta,\varepsilon)}K_{\mu}(z) dm(z) \lt C \qquad \forall \zeta \in \partial \mathbb{D} $$ where \(D(\zeta,\varepsilon)=\left\{z\in{\Bbb C}: |z-\zeta| \lt \varepsilon\right\}\).
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Łacny, Justyna. "The Rule of Law Conditionality Under Regulation No 2092/2020—Is it all About the Money?" Hague Journal on the Rule of Law 13, no. 1 (April 2021): 79–105. http://dx.doi.org/10.1007/s40803-021-00154-6.
Abstract:
AbstractSome say that the Union is built by moving from crisis to crisis. Crises in the last decade which affected the Union and its citizens concerned, inter alia, public finance (the financial crisis, 2008), migration (2014), public health (the COVID-19 pandemic, 2020) and the rule of law crisis (2018). This paper focus on the latter. It has been noted that some Member States have been happy to receive the benefits of EU membership, specifically the financial ones, while their commitment to European values, including the rule of law (Article 2 TEU), has been lacking. Since many instruments applied by EU institutions to improve this situation have proved rather insufficient, halting transfers of EU funds to these recalcitrant Member States has been touted as the way that might solve this crisis. Accordingly, a draft regulation was put on the table that authorised the EU institutions to suspend EU funds if a Member State is found to be in breach of the rule of law. This draft aimed to make the transfer of EU funds to the Member States conditional upon their continuous respect for the rule of law (and therefore became known as ‘the rule of law conditionality’). This paper comments on this draft as first proposed by the Commission in 2018 (Proposal for a regulation of the European Parliament and of the Council on the protection of the Union budget in the event of generalized gaps in the rule of law in the Member States [COM (2018) 324 final).], amended in 2019 by the European Parliament [European Parliament legislative resolution of 4 April 2019 on the proposal for a regulation of the European Parliament and of the Council on the protection of the Union's budget in case of generalised deficiencies as regards the rule of law in the Member States (COM(2018)0324–C8-0178/2018–2018/0136(COD)); https://www.europarl.europa.eu/RegData/seance_pleniere/textes_adoptes/provisoire/2019/04-04/0349/P8_TA-PROV(2019)0349_EN.pdf. A draft version of these provisions was presented in von Bogdandy and Łacny (Suspension of EU funds for breaching the rule of law - µ a dose of tough love needed? European Policy Analysis 2020, No 2, p. 1–15, https://sieps.se/en/publications/2020/suspension-of-eu-funds/, 2020).], and finally adopted by the European Parliament and the Council as Regulation (EU, Euratom) 2020/2092 of 16 December 2020 on a general regime of conditionality for the protection of the Union budget [Hungary and Poland voted against it and it is expected that its validity will be challenged before the CJEU via an action for annulment (Article 263 TFEU).] (henceforth called ‘Regulation 2020/2092′). This Regulation, containing 29 recitals in the preamble and 10 articles, entered into force on 1 January 2021 (Article 10 Regulation 2020/2092.). In the conclusions of the European Council meeting in December 2020 it was however accepted that it will be applied only in relation to budgetary commitments starting under the new Multiannual Financial Framework (MFF) 2021–2027, including Next Generation EU [Conclusions of the European Council meeting, 10 and 11 December 2020, para I (2) (k) https://www.consilium.europa.eu/media/47296/1011-12-20-euco-conclusions-en.pdf.]. This paper provides the legal characteristics of rule of law conditionality established under Regulation 2020/2092 and aims to determine whether financial incentives can restore compliance with the rule of law in Member States. Or in other words, is it all about the money?
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Quirici, Nadia, Nicoletta Del Papa, Cinzia Scavullo, Michela Cortiana, Chiara Borsotti, Wanda Maglione, Denise Comina, Agostino Cortelezzi, Giorgio Lambertenghi Deliliers, and Davide Soligo. "Stem Cells Defects in Systemic Sclerosis." Blood 106, no. 11 (November 16, 2005): 4194. http://dx.doi.org/10.1182/blood.v106.11.4194.4194.
Abstract:
Abstract Systemic Sclerosis (SSc) is a connective tissue disease characterized by early generalized microangiopathy and culminating in systemic fibrosis. Recent studies have provided evidence that SSc is associated with a reactive but ineffective angiogenesis, so that the disease finally leads to the irreversible loss of capillaries. Aim of the study was to investigate whether impaired vasculogenesis in SSc is due to defective characteristics in BM microenvironment. Peripheral blood (PB) samples were collected from 70 patients (pts): circulating endothelial progenitors (CEPs) were characterized as CD45−/CD133+ and evaluated by flow cytometry. BM samples were collected from 14 SSc pts and hematopoiesis evaluated by various assays. CD133+ cells were isolated by immunomagnetic sorting (IMS) and grown in order to induce endothelial differentiation. Long-term bone marrow cultures (LTBMC) were assessed and the number of stromal clonogenic precursors evaluated by a CFU-F (colony-forming unit fibroblast) assay. Mesenchymal stem cells (MSC) were separated by IMS for the expression of the nerve growth factor-receptor (NGF-R+) and grown in order to assess the clonogenic potential and the proliferative capacity, while their multipotential differentiation ability was determined after culture in different conditioned media. Phenotypic analysis of BM mononuclear cells showed a greater expression of the surface markers P1H12 and CD105 TGF-β receptor (1.2%±0.6 vs 0.5%±0.1 in normal controls, p=0.01 and 9.9%±5 vs 4.7%±3, p=0.02 respectively), but lower percentages of NGF-R+ stromal cell precursors (0.73±0.5 vs 1.61±0.6, p=0.02) and CD133+ cells (0.36%±0.4 vs 1.2%±0.8, p=0.05). On the contrary, the absolute number of CEPs in PB was higher in patients with SSc than in healthy controls (mean values 2.1 cells/μL vs 0.26 cells/μL, p=0.04). When BM CD133+ cells were grown in the presence of VEGF, only 3/12 cases gave endothelial differentiation, but always with a reduced proliferative ability. All pts showed a defective stromal compartment and a reduced number of BM stromal precursors, as detected by the LTBMC and by the lower CFU-F frequency (4%±3.2 vs 43%±19.8/1x10(e)6 LDMNCs, p=0.002 and 7±12.8 vs 69±61/1x10(e)5 NGF-R+ cells, p=0.01). Interestingly, NGF-R+ MSC overexpressed KDR and CD117 (26.4%±7.4 vs 4.6%±1.7, p=0.01 and 87.7%±5.1 vs 57.6%±11, p=0.03 respectively): when grown in the presence of VEGF they gave rise to endothelial colonies, only in 2/8 cases they formed a confluent layer with fibroblastic morphology but a reduced proliferative ability, while in the presence of adipogenic or osteogenic inductive media they failed to origin specific differentiation. Moreover, all “in vitro” differentiated endothelial cells even before activation showed high levels of CD62-E, VCAM-1 and CD105 expression, suggestive of the presence of increased levels of proangiogenic factors in BM. The results of this study provide evidence that patients with SSc have a stem cell defect involving both the hematopoietic and the stromal cells compartments. The higher expression of KDR on NGF-R+ cells suggests a role for VEGF in inducing endothelial differentiation of MSC, so resulting in a depletion of stromal precursors. The continuous recruitment of endothelial progenitors to sites of vascular injury, suggested by the high numbers of CEPs in PB, might lead to the irreversible BM damage we observed.
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Alavi, Nazanin, Megan Yang, Callum Stephenson, Niloofar Nikjoo, Niloufar Malakouti, Gina Layzell, Jasleen Jagayat, et al. "Using the Online Psychotherapy Tool to Address Mental Health Problems in the Context of the COVID-19 Pandemic: Protocol for an Electronically Delivered Cognitive Behavioral Therapy Program." JMIR Research Protocols 9, no. 12 (December 18, 2020): e24913. http://dx.doi.org/10.2196/24913.
Abstract:
Background The considerable rise of mental health challenges during the COVID-19 pandemic has had detrimental effects on the public health sector and economy. To meet the overwhelming and growing demand for mental health care, innovative approaches must be employed to significantly expand mental health care delivery capacity. Although it is not feasible to increase the number of mental health care providers or hours they work in the short term, improving their time efficiency may be a viable solution. Virtually and digitally delivering psychotherapy, which has been shown to be efficient and clinically effective, might be a good method for addressing this growing demand. Objective This research protocol aims to evaluate the feasibility and efficacy of using an online, digital, asynchronous care model to treat mental health issues that are started or aggravated by stressors associated with the COVID-19 pandemic. Methods This nonrandomized controlled trial intervention will be delivered through the Online Psychotherapy Tool, a secure, cloud-based, digital mental health platform. Participants will be offered a 9-week electronically delivered cognitive behavioral therapy program that is tailored to address mental health problems in the context of the COVID-19 pandemic. This program will involve weekly self-guided educational material that provides an overview of behavioral skills and weekly homework. Participants (N=80) will receive personalized feedback from and weekly interaction with a therapist throughout the course of the program. The efficacy of the program will be evaluated using clinically validated symptomology questionnaires, which are to be completed by participants at baseline, week 5, and posttreatment. Inclusion criteria includes the capacity to consent; a primary diagnosis of generalized anxiety disorder or major depressive disorder, with symptoms that started or worsened during the COVID-19 pandemic; the ability to speak and read English; and consistent and reliable access to the internet. Exclusion criteria includes active psychosis, acute mania, severe alcohol or substance use disorder, and active suicidal or homicidal ideation. Results This study received funding in May 2020. Ethics approval was received in June 2020. The recruitment of participants began in June 2020. Participant recruitment is being conducted via social media, web-based communities, and physician referrals. To date, 58 participants have been recruited (intervention group: n=35; control group: n=23). Data collection is expected to conclude by the end of 2020. Analyses (ie, linear regression analysis for continuous outcomes and binomial regression analysis for categorical outcomes) are expected to be completed by February 2021. Conclusions If proven feasible, this care delivery method could increase care capacity by up to fourfold. The findings from this study can potentially influence clinical practices and policies and increase accessibility to care during the COVID-19 pandemic, without sacrificing the quality of care. Trial Registration ClinicalTrials.gov NCT04476667; https://clinicaltrials.gov/ct2/show/NCT04476667 International Registered Report Identifier (IRRID) DERR1-10.2196/24913