555 research outputs found
Structure and Electric Conductivity of Zirconate Barium Yttrium-Doped
This work is devoted to the study of the structural and electrical transport properties of yttrium-doped barium zirconate. The activation energies of partial conductivities were calculated at different temperature values in a wide range of partial pressure of water vapor and oxygen.Работа была выполнена при поддержке гранта РНФ №18-73-00022
DETERMINATION OF THE CHEMICAL DIFFUSION COEFFICIENT AND THE CONSTANT OF SURFACE OXYGEN EXCHANGE GdBaCo2-xFexO6-δ
This work is devoted to the determination of diffusion coefficients and constants of surface oxygen exchange in double perovskites, barium and gadolinium cobaltites by ECR (electrical conductivity relaxation) method. The values of the total electrical conductivity were also determined.Работа была выполнена при поддержке Министерства Науки и Высшего Образования РФ, соглашение № 075-03-2021-051/5
Partial stabilization and control of distributed parameter systems with elastic elements
This monograph provides a rigorous treatment of problems related to partial asymptotic stability and controllability for models of flexible structures described by coupled nonlinear ordinary and partial differential equations or equations in abstract spaces. The text is self-contained, beginning with some basic results from the theory of continuous semigroups of operators in Banach spaces. The problem of partial asymptotic stability with respect to a continuous functional is then considered for a class of abstract multivalued systems on a metric space. Next, the results of this study are applied to the study of a rotating body with elastic attachments. Professor Zuyev demonstrates that the equilibrium cannot be made strongly asymptotically stable in the general case, motivating consideration of the problem of partial stabilization with respect to the functional that represents “averaged” oscillations. The book’s focus moves on to spillover analysis for infinite-dimensional systems with finite-dimensional controls. It is shown that a family of L2-minimal controls, corresponding to low frequencies, can be used to obtain approximate solutions of the steering problem for the complete system. The book turns from the examination of an abstract class of systems to particular physical examples. Timoshenko beam theory is exploited in studying a mathematical model of a flexible-link manipulator. Finally, a mechanical system consisting of a rigid body with the Kirchhoff plate is considered. Having established that such a system is not controllable in general, sufficient controllability conditions are proposed for the dynamics on an invariant manifold. Academic researchers and graduate students interested in control theory and mechanical engineering will find Partial Stabilization and Control of Distributed-Parameter Systems with Elastic Elements a valuable and authoritative resource for investigations on the subject of partial stabilization
Ecology and distribution of the Iceland scallop Chlamys islandica (O. F. Müller, 1776) in the Kola Вay (the Barents Sea)
Assessment of the current state (distribution, allocation features, size structure, habitat conditions) of the Iceland scallop Chlamys islandica settlements in the Kola Bay has been carried out. Material for the study was collected in the upper subtidal zone by scuba divers at 12 research areas. It has been established that at present in the bay the scallop is widespread. This species occurrence is higher on the hard bottom and shell rock than on the soft bottom. The scallop numbers increases from the inner to the outer region of the bay. The weight-average density varies from 0.01 to 5.56 ind/m2 and the biomass varies from 0.5 to 225.0 g/m2. The scallops can form the local aggregations with density of 15 ind/m2. The mollusks settlement density is comparable with that in other bays of the more environmentally friendly areas. The size structure of mass aggregations has a monomodal character that demonstrates a weak replenishment of shallow-water settlements by juveniles. The Iceland scallop inhabits the upper subtidal zone of the Kola Bay with the water temperature equal to 2.8–11.8 °C and the salinity – 31.4–35.6 ‰. The abundance and size composition of scallop in the middle of the bay is under the influence of illegal non-commercial fishing. The received data on distribution and dimensional structure of the Iceland scallops can form a basis for monitoring conditions of bottom fauna of the Kola Bay and also for monitoring the possible changes in the Arctic ecosystem caused by climatic fluctuations or anthropogenic influence
A stochastic model for the polygonal tundra based on Poisson–Voronoi diagrams
Subgrid processes occur in various ecosystems
and landscapes but, because of their small scale, they are
not represented or poorly parameterized in climate models.
These local heterogeneities are often important or even fundamental
for energy and carbon balances. This is especially
true for northern peatlands and in particular for the polygonal
tundra, where methane emissions are strongly influenced by
spatial soil heterogeneities.We present a stochastic model for
the surface topography of polygonal tundra using Poisson–
Voronoi diagrams and we compare the results with available
recent field studies. We analyze seasonal dynamics of water
table variations and the landscape response under different
scenarios of precipitation income. We upscale methane
fluxes by using a simple idealized model for methane emission.
Hydraulic interconnectivities and large-scale drainage
may also be investigated through percolation properties and
thresholds in the Voronoi graph. The model captures the main
statistical characteristics of the landscape topography, such
as polygon area and surface properties as well as the water
balance. This approach enables us to statistically relate
large-scale properties of the system to the main small-scale
processes within the single polygons
Retrieving Paleobehavior of the Ozone Layer from Dendrochronological Data Using Toms Satellite Data
Verification of cutaneous leishmaniasis
The article presents a case study of cutaneous leishmaniasis in a child. The patient stayed for several months in a leishmaniasis endemic area - in Tajikistan. This case is interesting from the point of view of verification of the infection that is not endemic in Russia
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