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排序方式: 共有2160条查询结果,搜索用时 234 毫秒
51.
S. A. Petrov O. Yu. Sinel'shchikova L. F. Grigor'eva I. B. Patrina N. O. Ovchinnikov V. V. Gusarov 《Glass Physics and Chemistry》2005,31(6):803-807
The ramsdellite-type phases crystallizing in the Li2O-Fe2O3-TiO2 system in the course of synthesis in gaseous media at different oxygen partial pressures are studied. Solid solutions based on the ramsdellite structure with the composition Li2Ti3?xFe x O7 ? δ (0 ≤ x ≤ 0.7) are prepared in an oxidizing medium (PO2 = 1 atm) for the first time. Analysis of the results obtained by electron paramagnetic resonance and Mossbauer spectroscopy revealed that, in these solid solutions, all iron ions are in the oxidation state Fe+3. 相似文献
52.
The influence of pitch composition and surface properties of petroleum coke on the interaction of pitch and coke in the composite is studied. The adsorption results and EPR data indicate that recombination of paramagnetic centers and interaction of oxygen functional groups occur during the preparation of the composite. As a result of interaction between petroleum coke and pitch, polar compounds are concentrated in the adsorption layer. The baking criterion is used for the characterization of the baking ability of the pitches obtained as a result of different oxidation treatments of commercial coal tar pitch. It is determined that physico-chemical properties of the obtained pitches influence the value of the “baking criterion”. The kind of thermo-oxidation treatment of the parent pitch should be chosen hence achieving the maximum value of the baking criterion. For this purpose, the maximal part of the pitch has to take part in the adsorption layer. 相似文献
53.
D. M. Gokhfeld D. A. Balaev K. A. Shaikhutdinov S. I. Popkov M. I. Petrov 《The Physics of Metals and Metallography》2006,101(1):S27-S28
The current-voltage characteristic (CVC) of a break junction made from polycrystalline Bi1.8Pb0.3Sr1.9Ca2Cu3Ox is investigated. The experimental CVC has a hysteretic feature that reflects part of the curve with a negative differential resistance. The CVC is discussed within the framework of the Kümmel-Gunsenheimer-Nicolsky theory that takes into account multiple Andreev reflections in superconductor/normalmetal/superconductor junctions. 相似文献
54.
A. V. Favorskaya I. B. Petrov D. I. Petrov N. I. Khokhlov 《Mathematical Models and Computer Simulations》2016,8(4):348-357
The aim of this work is the numerical simulation of wave propagation in media with linear-elastic and acoustic layers as exemplified by the seismic prospecting problems in the Arctic region and the explosive impact on an iceberg. The complete system of equations describing the state of a linearly elastic body and the system of equations describing the acoustic field are solved. The grid-characteristic method is used to provide the contact and boundary conditions, including the contact condition between acoustic and linear-elastic layers, to be correctly described. 相似文献
55.
A mathematical model is proposed for the proximity dynamics of political positions of interacting individuals which form a closed group. The model is described as a system of ordinary differential equations. The results of numerical experiments for the system are presented and a number of substantial conclusions are formulated. It is shown that in the case of two individuals the system has an asymptotically stable zero steady state. In the case of two individuals and two themes we get an infinite number of stationary states, all except the zero state being unstable. 相似文献
56.
V. M. Bashmakov B. S. Sirozhev G. N. Petrov 《Power Technology and Engineering (formerly Hydrotechnical Construction)》1995,29(12):681-689
1. | In connection with the historically established economic conditions and existing agreements with neighboring countries, the cascade of Vakhsh hydrostation was designed on the basis of operating conditions in an irrigation regime and cannot provide Tajikistan's own need for power in the winter, the deficit of which is 4 billion kWh/yr. The traditional methods of solving this problem call for the construction of either an irrigation reregulator in the lower course of the river or a hydrostation operating in a power compensator regime in its upper course. Both these variants require vast expenditures of material and financial resources and provide an effect just due to one particular hydro development. |
2. | The natural conditions of Tajikistan created the unique possibility of increasing the effectiveness of the combined operation of the Vakhsh cascade by constructing a tunnel conduit and using the runoff of the Pyandzh River in operating the Vakhsh hydrostations. With minimum construction costs the power effect of the cascade in this case increases substantially since it is achieved due to the repeated use of Pyandzh River water at all stations of the cascade and without any detriment for irrigation. |
3. | Realization of the proposed project will increase the total power production of the cascade for all hydrostations specified by the scheme depending on the degree of streamflow regulation by the Pyandzh reservoir. The cost effectiveness of the proposed project is an order higher than that of the traditional variants. Even for the stations operating today on the cascade its effect is comparable to the effect of the Nurek hydrostation with respect to all indices. Here the total cost of the tunnel conduit together with the dam is an order lower than the cost of the Nurek hydro development. |
57.
58.
Kseniia A. Sergeeva Dmitrii V. Pavlov Albert A. Seredin Eugeny V. Mitsai Aleksandr A. Sergeev Evgeny B. Modin Anastasiia V. Sokolova Tsz Chun Lau Kseniia V. Baryshnikova Mihail I. Petrov Stephen V. Kershaw Aleksandr A. Kuchmizhak Kam Sing Wong Andrey L. Rogach 《Advanced functional materials》2023,33(44):2307660
In order to advance the development of quantum emitter-based devices, it is essential to enhance light-matter interactions through coupling between semiconductor quantum dots with high quality factor resonators. Here, efficient tuning of the emission properties of HgTe quantum dots in the infrared spectral region is demonstrated by coupling them to a plasmonic metasurface that supports bound states in the continuum. The plasmonic metasurface, composed of an array of gold nanobumps, is fabricated using single-step direct laser printing, opening up new opportunities for creating exclusive 3D plasmonic nanostructures and advanced photonic devices in the infrared region. A 12-fold enhancement of the photoluminescence in the 900–1700 nm range is observed under optimal coupling conditions. By tuning the geometry of the plasmonic arrays, controllable shaping of the emission spectra is achieved, selectively enhancing specific wavelength ranges across the emission spectrum. The observed enhancement and shaping of the emission are attributed to the Purcell effect, as corroborated by systematic measurements of radiative lifetimes and optical simulations based on the numerical solution of Maxwell's equations. Moreover, coupling of the HgTe photoluminescence to high quality factor modes of the metasurface improves emission directivity, concentrating output within an ≈20° angle. 相似文献
59.
Weber Lukas Vinon Tobias Kndler Christian Solis-Vasquez Leonardo Bernhardt Arthur Petrov Ilia Koch Andreas 《Distributed and Parallel Databases》2022,40(1):27-45
Distributed and Parallel Databases - Massive data transfers in modern data-intensive systems resulting from low data-locality and data-to-code system design hurt their performance and scalability.... 相似文献
60.
A. A. Zatsiupa L. A. Bashkirov I. A. Vialikanava G. S. Petrov S. V. Shevchenko 《Inorganic Materials》2016,52(4):361-366
Bi2–хLaхFe4O9 and Bi2Fe4–2xTixCoxO9 ferrites have been prepared by solid-state reactions at a temperature of 1073 K. X-ray diffraction data indicate that, in the Bi2–хLaхFe4O9 system, the limiting degree of La3+ substitution for Bi3+ ions in Bi2Fe4O9 does not exceed 0.05 and that the limiting degree of substitution in the Bi2Fe4–2xTixCoxO9 system lies in the range 0.05 < x < 0.1. The specific magnetization and specific magnetic susceptibility of the samples have been measured at temperatures from 5 to 300 K in a magnetic field of 0.86 T. The field dependences of magnetization obtained for the Bi2–хLaхFe4O9 and Bi2Fe4–2xTixCoxO9 ferrites at temperatures of 300 and 5 K demonstrate that partial isovalent substitution of La3+ for Bi3+ ions in Bi2Fe4O9 and heterovalent substitution of Ti4+ and Co2+ ions for two Fe3+ ions leads to partial breakdown of the antiferromagnetic state and nucleation of a ferromagnetic state. 相似文献