Abstract
The purpose of this work is to compare the impregnation degree of samples made from an aramid-polyurethane composite material produced by three methods of winding. The para-aramid ...impregnation degree assessment was made on the basis of a microscopic examination of a sample’s section, as well as the results of determining the delamination fracture toughness of ring samples. Based on the studies, it was concluded that the best impregnation degree for para-aramid fibers is achieved in case of using binder sputtering assisted dry winding technology. This technology can be used for high-pressure flexible pipes manufacturing to increase their strength, which can lead to the product’s working pressure increasing.
The objective of the present study was to evaluate the dynamics of the nasal breathing function and the quality of life in the patients following septoplastic surgery with the use of the classical ...method in comparison with the application of the latex tissue glue. The study included 58 patients presenting with diagnosis of deflected septum of the nose and vasomotor rhinitis. The following methods were employed for the purpose: anterior active rhinomanometry, evaluation of the transport function of the nasal cavity, and the questionnaire study for the determination of the patients' quality of life. The patients were allocated to two groups. Group 1 was comprised of the patients who underwent the classical surgical intervention (septal surgery with the mechanical disintegration of the inferior turbinated bones. The patients of the second group were treated with the use of the modified surgical procedure with the use of the latex tisue glue. The study has demonstrated that the patients treated with the use of the modified approach (including the application of the latex glue) recovered faster and reported a higher quality of life during the postoperative period than the patients of the first group treated by the conventional method.
This paper continues a series of publications on the modification of the Map of Expected Earthquakes (MEE), a method of medium-term earthquake forecasting. It is devoted to the calculation and ...analysis of retrospective statistical characteristics of dynamic and quasi-stationary prognostic indicators in the Kamchatka region used at this stage in the modernized MEE method. In our calculations we used the regional catalog of earthquakes in Kamchatka over the period from 1962 to 2020. The object of the forecast were earthquakes with
K
forecast
≥ 13.5. The slope of the recurrence frequency graph γ with an efficiency value of
J
t
= 10.7 and
J
S
= 11.3 appeared as one of the most effective precursors for the Kamchatka region, both in time and area. The next most effective (in terms of time) precursor was the number of earthquakes
N
eq
in quiescence form with
J
t
= 5.8. In terms of area, the most effective precursor is the released seismic energy
E
2/3
, also in quiescence form with
J
S
= 14.7. The value of unconditional probability
P
(
D
1
) of the occurrence of a strong earthquake was calculated based on a set of dynamic indicators, which turned out to be equal to 0.09. A map of the stationary conditional probability of a strong earthquake has been constructed that takes into account the stationary prognostic indicator “presence of faults in a cell” with values of 0.01 (in the cells where there are no faults) and 0.13 (in the cells where there are). As part of the next stage of work, it is planned to continue expanding the functionality of the algorithm for the medium-term forecast of the MEE. The ultimate goal of modernization is the development of a digital problem-oriented system for medium-term earthquake forecasting using a set of prognostic indicators.
A Novel Model of a Mode-Localized MEMS Accelerometer Morozov, N. F.; Indeitsev, D. A.; Igumnova, V. S. ...
Doklady. a journal of the Russian Academy of Sciences. Physics,
10/2020, Letnik:
65, Številka:
10
Journal Article
Recenzirano
In this work, a model of a microelectromechanical accelerometer with two movable beam elements located between two stationary electrodes is proposed. The action of inertia forces in the longitudinal ...direction leads to a change in the spectral properties of the system, which can be used as an output signal of the sensor. The dynamics of the system in the presence of weak electrostatic coupling between the sensitive elements is characterized by the phenomenon of modal localization, which is a significant change in the amplitude relationships for the forms of in-phase and antiphase oscillations with small changes in the measured component of the object’s acceleration vector. It has been shown that the sensitivity of the proposed sensor based on modal localization can be orders of magnitude higher than the sensitivity of systems based on measuring the shift of natural frequencies.
The paper investigates the nonlinear modal interaction of longitudinal and flexural vibrations of a beam resonator under periodic thermal loading. The mode of parametric oscillations is investigated ...under conditions of internal multiple resonance between some flexural and longitudinal forms of free oscillations of the resonator. The possibility of the longitudinal-bending mode generation in the system has been found, the frequency of the slow envelope of which essentially depends on the parameter of the internal frequency detuning, which is directly related to the magnitude of external disturbances subject to high-precision measurement.
The dynamic problem of thermoelasticity with a localized inclusion in a medium is considered. It is shown that in the resonant regime an important role is played by the coupling coefficient of the ...temperature and strain fields. The coupling of the problem and the presence of a discrete spectrum lead to the appearance of an additional term in the expression for temperature, which is localized and does not describe the diffusion process.
Black-red and orange magnesium perylene-3,4,9,10-tetracarboxylate species are synthesized in the ion-exchange reaction at room temperature and by boiling an aqueous solution, respectively. Upon ...heating the two species to 500°C in argon, they reversibly lose 19–27 wt % of their crystallization water, and the products become black. X-ray diffraction analysis results show the preservation of the layered structure upon heating, which is confirmed via transmission electron microscopy. Exposure to a humid atmosphere rehydrates and restores the original structure. Thermolysis to 1000°С in argon produces a composite of MgO nanoparticles in a porous glassy carbon matrix. The stability of perylenetetracarboxylates up to 500°C makes them a promising candidate for synthesizing metal–organic frameworks.
—Multicomponent polycrystalline TbIn
x
Co
2 –
x
(with
х
= 0–0.2) solid solutions are prepared for the first time, and their crystal structure and magnetic, magnetocaloric, and magnetostrictive ...properties are studied. X-ray diffraction patterns taken at room temperature demonstrate mainly the presence of the cubic C15 Laves phase in all samples. As the indium content increases to
x
= 0.1, the lattice parameter is found to increase; the further increase in the indium content to
х
= 0.2 leads to a decrease in the lattice parameter. In this case, the Curie temperature
T
C
monotonically increases to 245 K. The isotheral magnetic entropy change Δ
S
mag
is calculated in accordance with magnetic measurements using the thermodynamic Maxwell’s relation. At a magnetic field change from 0 to 1.8 T, the maximum entropy change monotonically decreases and, for composition with
x
= 0.2, is 1.8 J/(kg К). As the indium content increases to
x
= 0.05, the volume magnetostriction increases. The further increase in the indium concentration leads to the decrease in the peak values and their shift to high temperatures.
—
Internal waves based on measurements on cruise 87 of the R/V
Akademik Mstislav Keldysh
in the Bransfield Strait near Half Moon Island and calculations using a numerical model are analyzed. The ...measurements were carried out on January 25, 2022 over 4 h using a line of temperature and pressure sensors along with CTD probe measurements. Temperature fluctuations based on the data from these sensors showed that the amplitude of internal waves was close to 5 m, sometimes reaching 15 m. Irregular semidiurnal tides predominate in the study area based on the calculation results using the TPXO9 global tidal model. Numerical calculations of the internal wave parameters show that the baroclinic tide generated on a steep slope breaks up into higher frequency waves.
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