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81.
Olga N. Goncharova Oleg A. Kabov Vladislav V. Pukhnachov 《International Journal of Heat and Mass Transfer》2012,55(4):715-725
The convective fluid flows with an interface are modeled using the classical Oberbeck–Boussinesq model of convection. The three dimensional solutions for the infinite domains with fixed heat-insulated boundaries and with the interface under action of a longitudinal temperature gradient are studied. Construction of the solutions for the flows of two immiscible fluids in a channel with a rectangular cross-section is carried out using a complete problem statement. The kinematic and dynamic conditions are prescribed at the interface. The additional condition of continuity of the tangential velocities, the conditions of continuity of temperature and of the thermal fluxes are assumed to be fulfilled on the interface. In the present paper the fluid flows are studied in the stationary case under conditions of gravity and microgravity. To investigate this problem numerically an iteration algorithm is introduced. This algorithm is based on a finite difference scheme (the alternating direction method) and it allows to find all the components of velocity for both phases and temperature distributions. The examples of flows which can be characterized as a combination of the translational and progressively rotational types of motion are presented. 相似文献
82.
Konstantin O. Nagornov Oleg Y. Tsybin Edith Nicol Anton N. Kozhinov Yury O. Tsybin 《Mass spectrometry reviews》2022,41(2):314-337
Ion cyclotron resonance (ICR) cells provide stability and coherence of ion oscillations in crossed electric and magnetic fields over extended periods of time. Using the Fourier transform enables precise measurements of ion oscillation frequencies. These precisely measured frequencies are converted into highly accurate mass-to-charge ratios of the analyte ions by calibration procedures. In terms of resolution and mass accuracy, Fourier transform ICR mass spectrometry (FT-ICR MS) offers the highest performance of any MS technology. This is reflected in its wide range of applications. However, in the most challenging MS application, for example, imaging, enhancements in the mass accuracy of fluctuating ion fluxes are required to continue advancing the field. One approach is to shift the ion signal power into the peak corresponding to the true cyclotron frequency instead of the reduced cyclotron frequency peak. The benefits of measuring the true cyclotron frequency include increased tolerance to electric fields within the ICR cell, which enhances frequency measurement precision. As a result, many attempts to implement this mode of FT-ICR MS operation have occurred. Examples of true cyclotron frequency measurements include detection of magnetron inter-harmonics of the reduced cyclotron frequency (i.e., the sidebands), trapping field-free (i.e., screened) ICR cells, and hyperbolic ICR cells with quadrupolar ion detection. More recently, ICR cells with spatially distributed ion clouds have demonstrated attractive performance characteristics for true cyclotron frequency ion detection. Here, we review the corresponding developments in FT-ICR MS over the past 40 years. 相似文献
83.
Silicon - The products of solid-phase mechanochemical interaction between pyrocatechol and silicon dioxide yielding a powdered composite were studied using a number of physicochemical methods. This... 相似文献
84.
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86.
This study investigated the high-temperature strength of spark plasma sintered tantalum diboride (TaB2) for the first time. TaB2 exhibited a unique elastic fracture behavior below 1900°C, unlike other transition metal diborides. The consolidation process involved spark plasma sintering at 2000–2200°C yielding dense TaB2 samples. The flexural strength was measured at elevated temperatures up to 2000°C, showing a quite high flexural strength of 400 ± 20 MPa at 1900°C. These findings provide valuable insights into the high-temperature behavior of TaB2, highlighting its potential for advanced applications. 相似文献
87.
Khazanov E Andreev N Palashov O Poteomkin A Sergeev A Mehl O Reitze DH 《Applied optics》2002,41(3):483-492
We present a comprehensive and systematic investigation of the fundamental physical limitations of Faraday isolation performance at high average powers that are due to thermally induced birefringence. First, the operation of various Faraday isolator designs by use of arbitrary orientation of cubic magneto-optic crystals is studied theoretically. It is shown that, for different Faraday isolator designs, different crystal orientations can optimize the isolation ratio. Second, thermo-optic and photoelastic constants for terbium gallium garnet crystals grown by different manufacturers were measured. Measurements of self-induced depolarization are made for various orientations of crystallographic axes. The measurements are in good agreement with our theoretical predictions. Based on our results, it is possible to select a crystal orientation that optimizes isolation performance at high average powers, resulting in a 5-dB enhancement over nonoptimized orientations. 相似文献
88.
Zoltan Zyman Matthias Epple Anton Goncharenko Dmytro Rokhmistrov Oleg Prymak Kateryna Loza 《Journal of materials science. Materials in medicine》2017,28(3):52
Thermal evolution of amorphous calcium phosphate (ACP) powder from a fast nitrate synthesis with a Ca/P ratio of 1:1 were studied in the range of 20–980?°C. The powder consisted of amorphous dicalcium phosphate anhydrate (CaHPO4) after heating to 200?°C. CaHPO4 gradually condensed to amorphous calcium pyrophosphate Ca2P2O7 (CPP) between 200 to 620?°C. Amorphous CPP crystallized at 620–740?°C to a metastable polymorph α′-CPP of the high-temperature phase α-CPP and β-CPP. The α′-CPP/ β-CPP phase ratio reached a maximum at 800?°C (60?wt% α′-CPP/40?wt% β-CPP), and α′-CPP gradually transformed to β-CPP at a higher temperature. Some β-TCP occurred at 900?°C, so that a three-phasic mixture was obtained in the powder heated to 980?°C. The occurrence of metastable α′-CPP is attributed to Ostwald’s step rule, and a mechanism for β-TCP formation is proposed. The advantages of prospective biomaterials from these powders are discussed. 相似文献
89.
Yury Kapelyushin Yasushi Sasaki Jianqiang Zhang Sunkwang Jeong Oleg Ostrovski 《Metallurgical and Materials Transactions B》2017,48(2):889-899
Reduction of un-doped magnetite is developed topochemically with the formation of a dense iron shell. However, the reduction of alumina-doped magnetite to wüstite proceeds with the formation of a network-like structure which consists of criss-crossed horizontal and vertical plates of wüstite. Reduction of magnetite includes the conversion of Fe3+ to Fe2+ and the movement of iron cations from the tetrahedral sites on the {400} and {220} planes of magnetite to the octahedral sites on the {200} planes of wüstite. Alumina has a negligibly small solubility in wüstite. In the reduction of magnetite doped with Al2O3, rejected Al3+ cations from wüstite diffuse to the magnetite–hercynite solid solution. Enrichment of the Fe3O4–FeAl2O4 solution with alumina in the vicinity of the reduction interface restricts the growth of {220} planes of wüstite and nucleation of {220} planes adjusted to the existing planes, preventing the merging of wüstite plates during the reduction process. Reduction of magnetite from the magnetite–hercynite solid solution practically stops when the Al3+ content at the interface approaches the solubility limit. Wüstite in the separated plates is reduced further to iron. 相似文献
90.
M. Bockstedte S. J. Liu Oleg Pankratov C. H. Woo Hanchen Huang 《Computational Materials Science》2002,23(1-4):85-94
The key factor determining nucleation processes and faceting in homoepitaxial growth as well as texture competition is the mobility of adatoms and small clusters across step edges and facets. Using a combination of molecular dynamics and ab initio calculations, we investigate the mechanisms of small clusters (dimer and trimer) diffusion down the aluminum (1 1 1) surface. In this paper we report results of molecular dynamics studies. Our study shows that the clusters dissociate at the step-edge of compact islands. As a result, the clusters diffuse down the step by an exchange mechanism with a small or medium Schwoebel barrier. The mechanism of this down-diffusion/dissociation is discussed and the corresponding energetics are calculated using the molecular statics method. We find a large anisotropy between the barriers at the two types of 1 1 0 oriented steps. 相似文献