排序方式: 共有31条查询结果,搜索用时 654 毫秒
1.
JOSEF MÁLEK JINDŘICH NEČAS K. R. RAJAGOPAL 《Archive for Rational Mechanics and Analysis》2002,165(3):243-269
To describe the flows of fluids over a wide range of pressures, it is necessary to take into account the fact that the viscosity
of the fluid depends on the pressure. That the viscosity depends on the pressure has been verified by numerous careful experiments.
While the existence of solutions local-in-time to the equations governing the flows of such fluids are available for small,
special data and rather unrealistic dependence of the viscosity on the pressure, no global existence results are in place.
Our interest here is to establish the existence of weak solutions for spatially periodic three-dimensional flows that are
global in time, for a large class of physically meaningful viscosity-pressure relationships.
(Accepted May 1, 2002) Published online November 15, 2002
Communicated by S. S. ANTMAN 相似文献
2.
V. A. Astapenko A. S. Kubankin N. N. Nasonov V. V. Polyanskiĭ G. P. Pokhil V. I. Sergienko V. A. Khablo 《JETP Letters》2006,84(6):281-284
The spectra of the collimated polarization bremsstrahlung of 7-MeV electrons intersecting Al, Cu, and Ni polycrystalline films have been measured. Detailed quantitative comparison of the experimental data with theoretical predictions has been performed. It has been shown that the model of a polycrystal as an ensemble of randomly oriented single crystals adequately describes the experimental results. This makes it possible to expect the development of a new method of diagnostics of the atomic structure of partially ordered solids. 相似文献
3.
A. S. Kubankin R. M. Nazhmudinov A. N. Oleinik I. A. Kishchin A. Yu. Aleynikov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2014,8(4):682-685
The characteristics of a possible radiation source in the vacuum-ultraviolet and soft X-ray range based on the transition radiation of electrons with an energy of about 100 keV are calculated. The possibilities of enhancing the radiation yield in the geometry of the glancing interaction of electrons with a target are analyzed. The possibility of creating a source with a yield on the order of 10?5 photon/(eV sr) per electron is demonstrated. 相似文献
4.
M. B. Gromov O. O. Ivashuk V. Y. Ionidi P. V. Karataev I. A. Kishin A. S. Kubankin A. N. Oleinik A. S. Chepurnov A. V. Shchagin 《Bulletin of the Lebedev Physics Institute》2016,43(11):319-322
A technique for measuring the spatial distribution of X-rays generated by a pyroelectric source is developed and tested. Anisotropy in the spatial distribution of X-rays from the surface perpendicular to the pyroelectric axis of the lithium niobate crystal depending on the piezoelectric crystal axis orientation was detected. The result obtained shows the necessity of considering the effect of piezoelectric properties of pyroelectric crystals on X-ray generation processes. 相似文献
5.
A waveguide in integrated optics is defined by its refractiveindex. The guide is assumed to be invariant in the propagationdirection while in the transverse direction it is supposed tobe a compact perturbation of an unbounded stratified medium.We are interested in the modes guided by this device, whichare waves with a transverse energy confined in a neighbourhoodof the perturbation. Our goal is to analyse the existence of such guided modes. Underthe assumptions of weak guidance the problem reduces to a two-dimensionaleigenvalue problem for a scalar field. The associated operatoris unbounded, selfadjoint, and bounded from below. Its spectrumconsists of the discrete spectrum corresponding to the guidedmodes and of the essential spectrum corresponding to the radiationmodes. We present existence results of guided modes and an asymptoticstudy at high frequencies, which shows that contrarily to thecase of optical fibers, the number of guided modes can remainbounded. The major tools are the min-max principle and comparisonof results between different eigenvalue problems. The originalityof the present study lies in the stratified character of theunbounded reference medium. 相似文献
6.
Jay Jin Saranya Kittanakom Victoria Wong Beverly AS Reyes Elisabeth J Van Bockstaele Igor Stagljar Wade Berrettini Robert Levenson 《BMC neuroscience》2010,11(1):33
Background
Opioid agonist drugs produce analgesia. However, long-term exposure to opioid agonists may lead to opioid dependence. The analgesic and addictive properties of opioid agonist drugs are mediated primarily via the mu-opioid receptor (MOR). Opioid agonists appear to alter neuronal morphology in key brain regions implicated in the development of opioid dependence. However, the precise role of the MOR in the development of these neuronal alterations remains elusive. We hypothesize that identifying and characterizing novel MOR interacting proteins (MORIPs) may help to elucidate the underlying mechanisms involved in the development of opioid dependence. 相似文献7.
V. I. Alekseev E. F. Irribarra A. S. Kubankin R. M. Nazhmudinov N. N. Nasonov V. V. Polyanskii V. I. Sergienko 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2013,7(2):276-278
The spectrum of polarization Bremsstrahlung is measured in backscattering geometry for 7-MeV electrons and a polycrystalline Ni foil without texture. The average size of grains in the foil is 300 nm. The results show the possibility of using a new method in the diagnostics of the atomic structure of polycrystalline materials with nanosized grains. The method is based on measuring the coherent component of polarization Bremsstrahlung. 相似文献
8.
K. A. Vokhmyanina P. N. Zhukova A. S. Kubankin Le Thu Hoai R. M. Nazhmudinov A. A. Pleskanev A. N. Oleinik N. N. Nasonov G. P. Pokhil 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2014,8(2):356-359
The grazing incidence interaction of a 10-keV electron beam with a planar surface of plexiglass is studied experimentally. Moreover, the electron passage through flat channels formed by such surfaces is investigated. The experiments reveal the presence of a guiding effect of the electron passage as in the case of a glass surface. However, there are some features, such as the existence of an initial elevation angle for the case of negative inclination angles of the plate. The formation of self-consistent charge on the surface of the plexiglass and its drain when the current is turned off occur more slowly than on the glass surface. This fact points to the difference in the surface conductivity of insulators. 相似文献
9.
MF Miller IA Franchi AS Sexton CT Pillinger 《Rapid communications in mass spectrometry : RCM》1999,13(13):1211-1217
The use of infrared laser-assisted fluorination to release oxygen from milligram quantities of silicates or other oxide mineral grains is a well-established technique. However, relatively few studies have reported the optimisation of this procedure for oxygen-17 isotope measurements. We describe here details of an analytical system using infrared (10 μm) laser-assisted fluorination, in conjunction with a dual inlet mass spectrometer of high resolving power ( approximately 250) to provide (17)O and (18)O oxygen isotope measurements from 0.5-2 mg of silicates or other oxide mineral grains. Respective precisions (1) of typically 0.08 and 0.04 per thousand are obtained for the complete analytical procedure. Departures from the mass-dependent oxygen isotope fractionation line are quantified by Delta(17)O; our precision (1) of such measurements on individual samples is shown to be +/-0.024 per thousand. In turn, this permits the offset between parallel, mass-dependent fractionation lines to be characterised to substantially greater precision than has been possible hitherto. Application of this system to investigate the (17)O versus (18)O relationship for numerous terrestrial whole-rock and mineral samples, of diverse geological origins and age, indicates that the complete data set may be described by a single, mass-dependent fractionation line of slope 0.5244+/- 0.00038 (standard error). Copyright 1999 John Wiley & Sons, Ltd. 相似文献
10.
A. S. Kubankin 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2009,3(2):317-321
The transition radiation (TR) of an electron in the vacuum ultraviolet range near the direction of total quantum reflection from the medium-vacuum interface has been investigated. The effect of a substantial increase (tens times) in the TR angular density has been predicted. The substantial dependence of lightness of this effect on the susceptibility of the dielectric target, the exit angle, and the energy of the emitting electron has been found. 相似文献