共查询到20条相似文献,搜索用时 109 毫秒
1.
Exact solutions for the flow of Casson fluid over a stretching surface with transpiration and heat transfer effects 下载免费PDF全文
The effects of transpiration on forced convection boundary layer non-Newtonian fluid flow and heat transfer toward a linearly stretching surface are reported.The flow is caused solely by the stretching of the sheet in its own plane with a velocity varying linearly with the distance from a fixed point.The constitutive relationship for the Casson fluid is used.The governing partial differential equations corresponding to the momentum and energy equations are converted into non-linear ordinary differential equations by using similarity transformations.Exact solutions of the resulting ordinary differential equations are obtained.The effect of increasing Casson parameter,i.e.,with decreasing yield stress(the fluid behaves as a Newtonian fluid as the Casson parameter becomes large),is to suppress the velocity field.However,the temperature is enhanced as the Casson parameter increases.It is observed that the effect of transpiration is to decrease the fluid velocity as well as the temperature.The skin-friction coefficient is found to increase as the transpiration parameter increases. 相似文献
2.
C.H. Ziener T. Kampf P.M. Jakob W.R. Bauer 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2010,202(1):38-42
The diffusion in the magnetic dipolar field around a sphere is considered. The diffusion is restricted to the space between two concentric spheres, where the inner sphere is the source of the magnetic dipolar field. Analytical expressions for the CPMG transverse relaxation rate as well as the free induction decay and the spin echo time evolution are given in the Gaussian approximation. The influence of the inter-echo time is analyzed. The limiting cases of small and large inter-echo times as well as the short and long time behavior are evaluated. 相似文献
3.
导模共振生物传感器由于具有微型化、免标签、高通量和实时检测等优势被广泛研究。利用严格耦合波理论分析了该生物传感器对样品折射率和厚度的灵敏度随共振波长的变化规律。当样品厚度和共振波长一定时,其折射率灵敏度恒定;随着共振波长的增大,折射率灵敏度显著提高。当样品折射率和共振波长一定时,厚度灵敏度随着厚度的增加而降低,最后趋近于0;当共振波长增加时,厚度灵敏度明显提高,厚度测量范围增大。结果表明:选取较长的共振波长有利于样品的检测和分析。 相似文献
4.
5.
6.
7.
The self-Q-switched laser performance of monolithic Cr4+,Nd3+:YAG concave-planar resonator with 5-mm length was studied experimentally and theoretically. The slope efficiency is as high as 24% and pump threshold is as low as 64 mW. The pulse width, the single pulse energy and the pulse repetition rate of monolithic Cr,Nd:YAG self-Q-switched laser were measured as a function of absorbed pump power. With the increase of pump power, the pulse width decreases and the pulse energy and the pulse repetition rate increase. The average output power of 91 mW with pulse width of 7 ns at repletion rate of 35.5 kHz was obtained at the maximum absorbed pump power of 440 mW, the peak power is as high as 370 W. The theoretical prediction of pulse energy, pulse width and pulse repetition rate as a function of absorbed pump power based on rate equations is in a good agreement with our experimental data. This can lead to develop the diode laser-pumped monolithic self-Q-switched solid-state microchip lasers. 相似文献
8.
9.
H. Sprang H.-G. Busmann S. Lauer I. V. Hertel 《Applied Physics A: Materials Science & Processing》1992,55(4):347-351
Polycrystalline diamond film deposition is studied under the influence of a pulsed supersonic beam. The beam is formed by a high-pressure value which is used as gas inlet in an otherwise conventional hot-filament reactor. The growth rate of the films as well as the typical size of the microcrystallites are independent of the stagnation pressure behind the nozzle of the valve as long as the background pressure and the gas flow through the chamber are kept constant. In contrast, a drastic change in texture formation is found. 相似文献
10.
为了研究亚波长孔径的增强透射效应,把传输线理论引入到了单一亚波长金属孔径的增强光学透射效应中。把金属孔径看成传输线,将电流在传输线上的传输和类Fabry-Pérot腔联系起来;把孔径的出射面看成是传输线的输出端,将出射面的电流看成是一种局域的衰逝电流,电流经传输线在传输线的输出端以天线辐射的形式辐射电磁波。解释了孔径透射的近场分布问题、孔径增强透射峰的位置问题和透射峰位置随金属板厚度的红移问题,得到了与其它理论和实验一致的结果,对开发基于增强透射的亚波长元件具有重要的参考价值。 相似文献
11.
Modification of gravitational redshift of x-ray burst produced by pulsar surface magnetoplasma 下载免费PDF全文
In this paper, the propagation of x-ray bursts in the magnetoplasma of pulsar magnetosphere is discussed. The electromagnetic interaction between x-ray bursts and magnetoplasma is described as some geometry. The electromagnetic effects of surface superstrong magnetic field and dynamic effects of outflowing magnetoplasma of pulsars are treated as an optical metric. The Gordon metric is introduced to represent the gravitational metric and optical metric. So the propagation of x-ray bursts in magnetoplasma of pulsars can be described as x-ray bursts transmitting in an effective space characterized by Gordon metric. The modification of gravitational redshift, attributed to the flowing magnetoplasma of pulsars, is obtained and it is shown that the modification is of redshift and can reach the same magnitude as the gravitational redshift for ordinary pulsars. 相似文献
12.
The beam transport design of a novel proton dielectric wall accelerator is introduced in this paper. The protons will be accelerated from 40 keV to nearly 1 MeV under an accelerating gradient that is as high as 20 MV/m. A consideration of the beam line as well as the transport simulation is presented. The influences of the injection timing jitter and the accelerating pulse timing jitter are also discussed. 相似文献
13.
The Shannon information entropy is investigated within the nonrelativistic framework. The Kratzer potential is considered as the interaction and the problem is solved in a quasi-exact analytical manner to discuss the ground and first excited states. Some interesting features of the information entropy densities as well as the probability densities are demonstrated.The Bialynicki–Birula–Mycielski inequality is also tested and found to hold for these cases. 相似文献
14.
采用表面包覆水溶性硫醇单分子层的金团簇(MPC)对琼脂-明胶复合泡沫进行掺杂。研究表明,掺杂泡沫轴向密度均匀,金MPC粒径小,不聚焦,在泡沫中分散良好,掺杂对泡沫微观形貌没有明显影响。当掺杂泡沫密度低至5.8 mg/cmcm3,、掺杂质量分数高达30%时,金MPC在复合泡沫中不发生沉降或聚集。以水作溶剂,成功制得密度小于10 mg/cm3,孔径小于100 mm的金MPC掺杂琼脂-明胶泡沫靶材料。 相似文献
15.
The main emphasis of this review is on thermal modelling and prediction of laser welding in metals. However as similar techniques are employed to model conventional welding processes such as arc, resistance and friction, as well as related processes such as alloying, cladding and surface hardening, part of this review is given over to the modelling of these processes where appropriate. The time frame of the review is up to the year 2002. 相似文献
16.
Modification of gravitational redshift of x-ray burst produced by pulsar surface magnetoplasma 下载免费PDF全文
In this paper, the propagation of x-ray bursts
in the magnetoplasma of pulsar magnetosphere is discussed. The electromagnetic
interaction between x-ray bursts and magnetoplasma is described as some geometry.
The electromagnetic effects of surface superstrong magnetic
field and dynamic effects of outflowing magnetoplasma of pulsars are
treated as an optical metric. The Gordon metric is introduced to
represent the gravitational metric and optical metric. So the
propagation of x-ray bursts in magnetoplasma of pulsars can be
described as x-ray bursts transmitting in an effective space
characterized by Gordon metric. The modification of gravitational
redshift, attributed to the flowing magnetoplasma of pulsars, is
obtained and it is shown that the modification is of redshift and can
reach the same magnitude as the gravitational redshift for ordinary
pulsars. 相似文献
17.
We propose a new model and a solution method for two-phase compressible flows. The model involves six equations obtained from conservation principles applied to each phase, completed by a seventh equation for the evolution of the volume fraction. This equation is necessary to close the overall system. The model is valid for fluid mixtures, as well as for pure fluids. The system of partial differential equations is hyperbolic. Hyperbolicity is obtained because each phase is considered to be compressible. Two difficulties arise for the solution: one of the equations is written in non-conservative form; non-conservative terms exist in the momentum and energy equations. We propose robust and accurate discretisation of these terms. The method solves the same system at each mesh point with the same algorithm. It allows the simulation of interface problems between pure fluids as well as multiphase mixtures. Several test cases where fluids have compressible behavior are shown as well as some other test problems where one of the phases is incompressible. The method provides reliable results, is able to compute strong shock waves, and deals with complex equations of state. 相似文献
18.
19.
A. M. Popov Yu. E. Lozovik A. S. Sobennikov A. A. Knizhnik 《Journal of Experimental and Theoretical Physics》2009,108(4):621-628
The structure and elastic properties of (5,5) and (10,10) nanotubes, as well as barriers for relative rotation of the walls and their relative sliding along the axis in a double-walled (5,5)@(10,10) carbon nanotube, are calculated using the density functional method. The results of these calculations are the basis for estimating the following physical quantities: ultimate shear strengths and diffusion coefficients for relative sliding along the axis and rotation of the walls, as well as frequencies of relative rotational and translational oscillations of the walls. The commensurability-incommensurability phase transition is analyzed. The length of the incommensurability defect is estimated on the basis of ab initio calculations. It is proposed that a double-walled carbon nanotube be used as a plain bearing. The possibility of experimental verification of the results is discussed. 相似文献