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101.
We present in this paper a numerical scheme for incompressible Navier–Stokes equations with open and traction boundary conditions, in the framework of pressure-correction methods. A new way to enforce this type of boundary condition is proposed and provides higher pressure and velocity convergence rates in space and time than found in the present state of the art. We illustrate this result by computing some numerical and physical tests. In particular, we establish reference solutions of a laminar flow in a geometry where a bifurcation takes place and of the unsteady flow around a square cylinder. 相似文献
102.
M.A. Koshelev 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(3):550-552
Broadening and shifting of the 211-202 transition of H216O, H217O, H218O by pressure of water, nitrogen and oxygen were precisely measured at room temperature using spectrometer with radio-acoustic detection of absorption. Shift parameters for all studied lines as well as broadening parameters of H217O, H218O lines were measured for the first time. Comparison of obtained results with previously known experimental and theoretical data is presented. 相似文献
103.
Catalyst aggregation affects the growth of carbon nanotube (CNT) arrays in terms of tubular structures, waviness, entanglement, lengths, and growth density etc., which are important issues for application developments. We present a systematic correlation between the aggregation of catalyst on the SiO2/Si substrate and the structure and morphology of CNT arrays. The thickness of the catalyst film has a direct effect on the areal density of the catalytic particles and then the alignment of the CNT array. Introducing alumina as buffer layer and annealing the catalyst film at low pressure are two effective approaches to downsize the catalyst particles and then the diameter, wall number of the CNTs. Both the size and areal density of the catalyst also change with the CNT growth in accordance with Ostwald ripening process, with the bottom of the CNT array varying from well-aligned to disordered and adhesion between catalyst particles and the substrate getting enhanced. Strategies including tuning the thickness of the catalyst film, changing buffer layer, controlling on the growth time and the system pressure were used to regulate the aggregation of the catalyst. CNT arrays from disordered to well-aligned, from multi-walled to few-walled and further to single-walled were reproducibly synthesized by chemical vapor deposition of acetylene. 相似文献
104.
A.D. ProkhorovA.A. Prokhorov L.F. ChernyshV.P. Dyakonov H. Szymczak 《Journal of magnetism and magnetic materials》2011,323(11):1546-1550
The ground state of Gd3+ ions substituting for trivalent europium in the EuAl3(BO3)4 single crystal was studied by electron paramagnetic resonance (EPR) over the temperature range of 300-4.2 K and at pressures up to 9 kbar. The EPR spectra were analysed using the spin Hamiltonian of axial symmetry. The following parameters are reported: g=1.981±0.002, b20=280.18±0.12, b40=−12.95±0.08 and b60=0.61±0.12 (at Т=298 K). The distortions of the nearest environment of Gd3+ ion were analysed within the framework of the superposition model of crystal field. 相似文献
105.
Yu.D. Zavorotnev L.I. MedvedevaB.M. Todris E.A. DvornikovO.Yu. Popova 《Journal of magnetism and magnetic materials》2011,323(22):2808-2812
Experimental data on magnetization of the antiferromagnetic (AFM) polycrystalline samples in the temperature range of 20-300 K, for pressures of 2 kbar and in magnetic field of 300 kOe, are presented in the paper. In the fields of 250 kOe, the magnetization curve demonstrates a jump explained by exchange-interaction sign change. In the region of 50-70 kOe, on the differential susceptibility versus magnetic field curve, there is a break of the 2nd order corresponding to the anomalous behavior of the magnetization. The obtained results were processed on the basis of the phenomenological Landau theory. It is shown that the ferromagnetic vector occurrence is forced during the formation of AFM spiral structure. The behavior of thermodynamic potential factors has been determined. Three more anomalies have been revealed and explained by a jump-like magnetization change of the Co-subsystem. 相似文献
106.
Production optimization of gas-lifted oil wells under facility, routing and pressure constraints is a challenging problem, which has attracted the interest of operations engineers aiming to drive economic gains and scientists for its inherent complexity. The hardness of this problem rests on the non-linear characteristics of the multidimensional well-production and pressure-drop functions, as well as the discrete routing decisions. To this end, this work develops several formulations in Mixed-Integer Linear Programming (MILP) using multidimensional piecewise-linear models to approximate the non-linear functions with domains spliced in hypercubes and simplexes. Computational and simulation analyses were performed considering a synthetic but realistic oil field modeled with a multiphase-flow simulator. The purpose of the analyses was to assess the relative performance of the MILP formulations and their impact on the simulated oil production. 相似文献
107.
108.
Hao Lu Wenlong Liu Guangliu Ran Zezhou Liang Hongxiang Li Nan Wei Hongbo Wu Zaifei Ma Yahui Liu Wenkai Zhang Xinjun Xu Zhishan Bo 《Angewandte Chemie (International ed. in English)》2023,62(50):e202314420
In this work, inspired by the principles of a pressure cooker, we utilized a high-pressure method to address the processing challenges associated with high molecular weight polymers. Through this approach, we successfully dissolved high molecular weight D18 in chloroform at 100 °C within a pressure-tight vial. The increased steam pressure raised the boiling point and dissolving capacity of chloroform, enabling the creation of a hybrid film with superior properties, including more ordered molecular arrangement, increased crystallinity, extended exciton diffusion length, and improved phase morphology. Organic solar cells (OSCs) based on D18 : L8-BO prepared using this high-pressure method achieved an outstanding power conversion efficiency of 19.65 %, setting a new record for binary devices to date. Furthermore, this high-pressure method was successfully applied to fabricate OSCs based on other common systems, leading to significant enhancements in device performance. In summary, this research introduces a universal method for processing high molecular weight D18 materials, ultimately resulting in the highest performance reported for binary organic solar cells. 相似文献
109.
110.
I. N. Goncharenko 《高压研究》2013,33(1):193-204
Diamond anvil cells (DAC) provide the highest static pressures ≥1?Mbar. Because of the low intensity of neutron sources, for a long time it was thought impossible to use DAC or other anvil cells in neutron experiments. We describe pressure cells with diamond and sapphire anvils and neutron instrumentation allowing neutron diffraction experiments to be carried out under pressures as high as 50?GPa, temperatures down to 0.1?K, and applied magnetic fields up to 7.5?T. 相似文献