Scanning tunneling microscopy and atomic force microscopy were used to study the topography of epitaxial Mo films of small thicknesses grown on the
R
-plane of sapphire. The domain of parameters of ...the Kardar–Parisi–Zhang model for the evolution of film surface profile in which it corresponds to the experimental results is found.
Abstract
In situ monitoring the surface and structure stability of the constructional material in the conditions of outer space solar wind is an interesting scientific and engineering problem. For ...this purpose, as a part of the project of the first in the world probe microscope – space satellite, multilayered graphenes were plasma treated in conditions imitating solar wind and studied by scanning probe microscope in laboratory conditions. Accelerating factor of laboratory plasma treatment was estimated in order to compare the result with further solar wind exposure in outer space. Multilayered graphenes were selected for the study because if their promising properties as light shields – for equipment protection, as well as for material for solar sailing. It was found that plasma treatment affects surface morphology, and these changes correlate with the duration of the treatment. Thus, the applied method can be applied to simulate the erosional effect of the solar wind on structural materials in open space.
Ti–Al–Nb–Mo–B alloy was successfully produced via high-energy ball milling (HEBM), self-propagating high-temperature synthesis (SHS) and hot isostatic pressing (HIP) techniques. HEBM was used to ...prepare powder mixtures with different types of microstructure and homogeneous distribution of the components. After SHS in thermal explosion mode powder grains with a microgradient structure were synthesized: their central part consists of α2-Ti3Al and the peripheral part consists of γ-TiAl. Compacted samples with duplex fine-grained structure and high thermomechanical properties (σ0.2 = 1245 MPa and 524 at 20 °C and 800 °C, respectively) have been obtained using the HIP technology. It was found, that mechanical twinning is the preferential deformation mechanism of the studied Ti–Al–Nb–Mo–B alloy.
The surface topology of epitaxial films of lead tin telluride solid solution (including with In additive, Pb
1 –
x
Sn
x
Te:In) has been examined using atomic force microscopy. The films have been ...grown on BaF
2
(111) single-crystal substrates and on a CaF
2
/BaF
2
buffer layer covering a Si(111) wafer. It has been shown that the relief statistical parameters depend on film growth conditions and the incorporation mechanism of indium, an excess amount of which has been detected on the surface by ex situ XPS.
Networks for data transmission between objects of V2X intelligent transport systems are currently being actively developed. Most existing V2X networks operate based on the IEEE 802.11p standard. ...However, these networks can only provide basic V2X applications and are unable to meet the demands of today’s applications. As a result, the IEEE committee began developing a new IEEE 802.11bd standard. A significant innovation of this standard is the use of the channel bonding method, which allows data to be transmitted in several channels at once. One of the approaches that can significantly increase the efficiency of the channel bonding method is the correct selection of the contention window. In this paper, we propose an adaptive algorithm for selecting a contention window that is compatible with the channel bonding method, is easy to implement, does not require changes to existing devices, and takes into account the requirements for the quality of service of various types of traffic. Using simulation it is shown that the proposed algorithm increases the maximal allowable density of stations, at which the requirements for quality of service are still met, by 25% compared to the standardized solution.
—
Single-phase (1 –
x
)(K
0.5
Na
0.5
)NbO
3
⋅
x
LiNbO
3
(KNN–LN) perovskite-structure ceramic materials with
x
= 0–0.10 modified with CuO and KCl additions have been prepared by solid-state ...synthesis, and their phase composition, structure, microstructure, and dielectric and ferroelectric properties have been studied. Increasing the percentage of lithium niobate has been shown to increase their Curie temperature and lower the temperature of their polymorphic phase transition, which is accompanied by a decrease in perovskite cell parameters, in accord with the ionic radii of the A-site cations. The
x
= 0.2 material has been found to have an increased room-temperature dielectric permittivity, which correlates with the observed increase in spontaneous polarization, as evidenced by laser radiation second harmonic generation intensity measurements.
•Model allowing synchronous measurement of flow and structure oscillations.•Experimental data used to validate the one-way and two-way FSI calculations.•Appearing harmonics of the vortex shedding and ...natural frequencies for lock-in mode.
This paper presents results of dynamic measurements of the flow and structure oscillations. We proposed a model consisting of two in-tandem flexible cylinders in the water cross-flow. During the studies, vibration acceleration amplitudes at the shedding frequency and at the cylinders natural frequency were obtained as a function of the flow velocity. The velocity pulsation and pressure pulsation spectra were determined in the flow. A relatively simple structure enabled the use of non-contact measurement systems for cross validation and uncertainty quantifications. The mutual influence of flow and structural dynamics induced by the lock-in effect between the vortex shedding frequency (or its harmonics) and the natural frequency was analyzed. These activities were conducted to generate representative data in order to validate the requirements for hydrodynamic force calculation accuracy and the methods of one-way and two-way coupled FSI calculations.
The dependence of the exciton-light coupling on the size of a quantum well in an external electric field is theoretically analyzed. It is shown that in a sufficiently strong field, an increase in the ...width of the well leads to weakening of the exciton-light coupling in comparison with narrower wells. Numerical calculations of the longitudinal-transverse exciton splitting are performed for wide ranges of the electric field strength and quantum well width. The analysis of the obtained data allowed us to derive expressions describing the dependences of the exciton-light coupling on both the magnitude of the applied electric field and the well width.
We have analyzed the surface and electron-transport properties of thin molybdenum epitaxial films. Experimental results are compared with available quantum models of the influence of the film surface ...relief on their resistance.
The microstructure and phase composition of cast and laser-melted Al-Fe-Ni alloys were investigated. Two main phases—Al
3
(Ni,Fe) and Al
9
FeNi—were formed in the as-cast state. A fine microstructure ...without porosity or solidification cracks was observed in the Al-Fe-Ni alloys after laser treatment. The hardness of the laser-melted alloys was 2.5–3 times higher than the hardness of the as-cast alloys owing to the formation of an aluminum-based solid solution and fine eutectic particles. The formation of the primary Al
9
FeNi phase was suppressed as a result of the high cooling rate. Annealing these alloys at temperatures less than 300°C demonstrated the high thermal stability of the microstructure while maintaining the hardness. The Al-Fe-Ni alloys investigated in this study are promising heat-resistant materials for additive manufacturing because of their fine, stable structure, and the low interdiffusion coefficients of Fe and Ni.
PDF