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51.
In the present paper, a liquid (or melt) film of relatively high temperature ejected from a vessel and painted on the moving
solid film is analyzed by using the second-order fluid model of the non-Newtonian fluid. The thermocapillary flow driven by
the temperature gradient on the free surface of a Newtonian liquid film was discussed before. The effect of rheological fluid
on thermocapillary flow is considered in the present paper. The analysis is based on the approximations of lubrication theory
and perturbation theory. The equation of liquid height and the process of thermal hydrodynamics of the non-Newtonian liquid
film are obtained, and the case of weak effect of the rheological fluid is solved in detail. 相似文献
52.
A. K. Chernyshov S. P. Kotova V. L. Velichanskii 《Journal of Russian Laser Research》2002,23(2):132-147
It is shown that the type of lateral waveguide of a laser diode cannot be determined uniquely based on just the measured magnitude of astigmatism. For a unique determination, the K-factor of Petermann, which characterizes the wavefront curvature at the laser output facet, must be measured as well. In order to determine the type of lateral waveguide, a setup for measuring astigmatic distances in the range 0–200 m with an error of ±2 m and a K-factor with an error of 20% was developed. Operational features of the setup were analyzed, and a technique that allows one to minimize the effect of beam ellipticity on the measurement results was found. Using the technique, the optimization of spatial matching of a laser diode with a ring interferometer of the butterfly type was accomplished. For transformation of the astigmatic elliptical beam into the axially symmetric mode of the interferometer, we have used an optical system that consists of two cylindrical and one spherical lenses. The algorithm for designing the matching system was developed, and the 85% injection of radiation of a AlGaAs laser diode into the principal mode of a ring interferometer was experimentally demonstrated. 相似文献
53.
Orbits of the ODE y=0 in corresponding jet bundles are investigated. Explicit relations for the right-hand side of an arbitrary 3-order ODE necessary and sufficient for the existence of a contact transformation reducing this equation locally to the form y=0 are obtained. 相似文献
54.
Swirling combustion is widely applied in various applications such as gas turbines, utility boilersor waste incinerators. This article contributes to the ongoing research by providing experimentaldata that are gathered in the mixing zone of a lifted swirling premixed natural gas flame. Theobjective of this paper is fivefold: (1) to introduce the lifted swirling flame featuring lowNO
x
emissions (2) to provide experimental data such as major species distributions, temperature and streamlines of the flow pattern, (3) to report on velocity bias in probability density function (PDF) distributions and to present PDF sequences of velocities in medium scale swirling flows, (4) to make an assessment on the local small-scale turbulence that is present in the swirling mixinglayer and (5) to provide new experimental data for model verification and development.The PDFs are corrected in order to compensate for the velocity bias phenomenon, which is typicalfor randomly sampled LDA data. Sequences of axial PDF data are presented and measurement locationsof interest are selected to look at the PDF characteristics of the internal and externalrecirculation zones, the mixing layer and the onset of the reacting flow into detail. The mixinglayer PDFs covered a wide velocity range and revealed bimodality; even the concept ofmulti-modality is suggested and explored. Analysis showed that a sum of two Gaussian distributionscan accurately envelop the experimental PDFs. The reason for this broadband turbulence behavior isto be found in combination of precessing and flapping motion of the flow structures, and also incombustion generated instabilities of the lifted flame. As a result, the flame brush is wide (largescale motion) and the mixing (small-scale turbulence) flattens any high temperatures in thecombustion process.The multi-scale turbulence concept is subsequently used to make anassessment of the local turbulence characteristics in the mixing layer.The idea is that the PDFs capture both contributions of the flow-inherent fine grain turbulence (u
l
) which is superposed on slowlarge scale fluctuating structures. It is this u
l
that will be of interest in continued research on the classification of the lifted flame into acombustion regime diagram (e.g. Borghi diagram). Finally, the bimodalitycharacter in reacting flows and the prediction of large-scale structuresmay be a challenge for LES researchers. 相似文献
55.
腰椎间盘纤维环膨隆症站立位动态脊髓造影的临床意义 总被引:1,自引:0,他引:1
目的:在MRI或CT检查的腰腿痛病人中,通过站立位动态脊髓造影,了解椎间盘纤维环在腰椎中立、过屈、过伸三位置下的变化,并探讨其临床意义,筛选出具有手术指征的LDH病人,决定手术方式.方法:对86例LDH患者,行站立或平卧中立、过屈、过伸脊髓造影,对比分析两组动态变化.鉴别出LDB,选择性行有限椎板减压,或保留其椎间盘.结果:脊髓造影侧位像“拿破仑帽”状影,站立三位置均明显大于平卧位,差异非常显著(P<0.01),在动态变化中平卧位者改成由中至屈曲位时,硬膜囊受压影较站立位者明显缩小,差异非常显著(P<0.01),站立由中至伸时,压迫影较平卧位增大,差异显著(P<0.05).其中28例,行有限椎板切除或保留其椎间盘,效果优良.结论:站立位会使LDB加重、临床症状加重,因站立过伸位使腰椎管狭窄病人症状加重.而平卧位造影时因重力负荷减轻,(拿破仑帽)影像不明显或消失,而出现假阴性. 相似文献
56.
A high order difference scheme is used to simulate the spatially developing compressible axisymmetric jet. The results show that the Kelvin-Helmholtz instability appears first when the jet loses its stability, and then with development of jet the increase in nonlinear effects leads to the secondary instability and the formation of the streamwise vortices. The evolution of the three-dimensional coherent structure is presented. The computed results verify that in axisymmetric jet the secondary instability and formation of the streamwise vortices are the important physical mechanism of enhancing the flow mixing and transition occurring. 相似文献
57.
58.
59.
Marco Castrillón López Jaime Muñz Masquó 《International Journal of Theoretical Physics》2007,46(4):1020-1026
It is proved that the Euler–Lagrange equations of a Yang-Mills type Lagragian is independent with respect to the chosen pairing
in the Lie algebra. Moreover, the Hamilton-Cartan equations of these Lagrangians are obtained and proved to be also independent
with respect to the pairing.
PACS Numbers 2003: 02.20.Qs, 02.20.Sv, 02.20.Tw, 02.40.Ma, 02.40.Vh, 11.10.Ef, 11.15.Kc
Mathematics Subject Classification 2000: Primary 70S15, Secondary 58A20, 58E15, 58E30, 70S05, 70S10, 81T13 相似文献
60.