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991.
José Bonet 《Mathematische Nachrichten》2020,293(8):1452-1458
Continuity, compactness, the spectrum and ergodic properties of the differentiation operator are investigated, when it acts in the Fréchet space of all Dirichlet series that are uniformly convergent in all half-planes \" data-semantic-complexity=\"1\"> \" data-semantic-complexity=\"1\">
992.
993.
Results of an investigation of in situ measurements of laser‐beam intensity Is and Im transmitted through aqueous ammonium dihydrogen phosphate (ADP) solutions saturated at 30 °C and water, respectively, and temperature Ts of solution and Tm of water during feeding of antisolvent acetone at different rates RA, using an indigenously designed experimental setup, are presented and discussed. It was found that: (1) for the measurement of MSZW, defined as the maximum volume fraction of acetone content Δxmax in the solution, obtained from temperature measurements are more reliable than transmitted laser‐beam intensity measurements for solutions, (2) two minima ΔTmin1 and ΔTmin2 associated with endothermic reactions, separated by a maximum ΔTmax due to exothermic reactions appear in the plots of temperature difference ΔT = Ts−Tm against acetone feeding time t, and (3) in the ΔT(t) plots there are time intervals Δt of constant rates RT of increase in ΔT of aqueous ADP solutions, and these values of RT increase linearly with acetone feeding time rate RA. The experimental data on the observed dependence of MSZW on antisolvent feeding rate RA, the appearance of minima ΔTmin1 and ΔTmin2 and maximum ΔTmax and their dependence on RA, and the relationship between RT and RA are discussed from consideration of processes of nucleation and growth of crystallites. 相似文献
994.
Qingshan Zhang Yuxiang Li 《ZAMM - Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik》2016,96(5):570-584
This paper deals with the attraction‐repulsion chemotaxis system with logistic source under homogeneous Neumann boundary conditions in a smooth bounded domain . Under a growth restriction on logistic source and suitable assumptions on the positive parameters χ, ξ, α, β, γ and δ, we show the existence of global bounded classical solutions. The global weak solution is also constructed if the logistic damping effect is rather mild. Furthermore, we obtain the asymptotic behavior of solutions for the logistic source . 相似文献
995.
Eduard Feireisl Yong Lu Josef Mlek 《ZAMM - Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik》2016,96(4):491-508
We study mathematical properties of quasi‐incompressible fluids. These are mixtures in which the density depends on the concentration of one of their components. Assuming that the mixture meets mass and volume additivity constraints, this density‐concentration relationship is given explicitly. We show that such a constrained mixture can be written in the form similar to compressible Navier‐Stokes equations with a singular relation between the pressure and the density. This feature automatically leads to the density bounded from below and above. After addressing the choice of thermodynamically compatible boundary conditions, we establish the large data existence of weak solution to the relevant initial and boundary value problem. We then investigate one possible limit from the quasi‐compressible regime to the incompressible regime. 相似文献
996.
Ivan I. Argatov Valentin L. Popov 《ZAMM - Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik》2016,96(8):956-967
The method of dimensionality reduction (MDR) is extended to the axisymmetric frictionless unilateral Hertz‐type contact problem for a viscoelastic half‐space and an arbitrary axisymmetric rigid indenter under the assumption that the circular contact area (arbitrarily evolving in time) remains singly connected during the whole process of indentation. In particular, the MDR is applied to study in detail the so‐called rebound indentation problem, where the contact radius has a single maximum. It is shown that the obtained closed‐form analytical solution for the rebound indentation displacement (recorded in the recovery phase, when the contact force vanishes) does not depend on the indenter shape. 相似文献
997.
Veniamin D. Kubenko 《ZAMM - Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik》2016,96(12):1442-1456
An exact analytical solution has been constructed for the plane problem on action of a non‐stationary load on the surface of an elastic layer for conditions of a ‘mixed’ boundary problem when normal stress and tangent displacement (the fourth boundary problem) are specified on one boundary and normal displacement and shear stress (the second boundary problem) for another boundary. Laplace and Fourier integral transforms are used. Their inversions were obtained with the help of tabular relationships and the convolution theorem for a wide range of acting non‐stationary loads. Expressions for stresses (displacements) were obtained in explicit form. The obtained expressions allow determining the wave process characteristics in any point of the layer at an arbitrary moment of time. Some variants of non‐stationary loads acting on an area with fixed boundaries or an area with boundaries changing by a known function are considered. Distinctive features of wave processes are analyzed. 相似文献
998.
999.
Exact analytical solutions of in-plane static problems of circular beams with uniform cross-section made of functionally graded material (FGM) are obtained. Material properties are assumed to be varying arbitrarily through the thickness. The effects of axial extension and shear deformations are considered. The differential equation system is solved exactly using the initial values method. The circumferential stress distribution on the cross-section is also obtained. The results are compared with those of rather complex approaches in the literature, such as elasticity approach, and the comparison shows an excellent agreement. Effects of power law exponent and radius-to-height ratio of the beam on circumferential stress distribution and displacements are investigated. 相似文献
1000.
Dimitrios I. Papadimitriou 《International Journal of Computational Fluid Dynamics》2016,30(3):272-284
A new algorithm for the solution of the unsteady adjoint equations is proposed in this article, aiming at overcoming the excessive computational cost and memory requirements of the conventional adjoint approach for the optimisation of unsteady problems in computational mechanics. The total cost is equal to four times the cost of the unsteady state solution, which is twice the cost of the conventional backward-in-time adjoint calculation but the memory requirements are very small, equivalent to those of a steady-state problem, while stability is acceptable. The proposed algorithm is validated in the case of the 1D unsteady Burgers equation with non-smooth source terms. 相似文献