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951.
本文运用DES(Detached-Eddy Simulation)分离涡方法,对吹风比为0.51和1.04的平板孤立直圆孔和弯圆孔下游的换热特性和漩涡结构进行了数值研究,并简要分析了下游涡量场的结构。模拟结果显示,预测的壁面温度场的趋势与实验值吻合较好;与RANS方法相比,DES方法得到了更加丰富的流场细节和旋涡结构,同时再现了冷却孔下游具有流场的间歇性,对进一步理解和研究冷却孔下游流场内的旋涡结构提供了参考。 相似文献
952.
Pawan Kumar R. PrasadR.K. Dwivedi H.K. Singh 《Journal of magnetism and magnetic materials》2011,323(21):2564-2568
A comparative study of the out-of-plane anisotropic magnetoresistance (AMR) in single crystalline and polycrystalline thin films of phase separated manganite Nd0.51Sr0.49MnO3 has been carried out. On-axis DC magnetron sputtering was used to deposit the single crystalline films (30 and 100 nm in thickness) on single crystal (0 0 1) LaAlO3 (LAO) and polycrystalline films (100 nm) on (1 0 0) Yttrium-stabilized ZrO2 (YSZ) substrates. The in-plane and out-of-plane magnetotransport properties of these films differ significantly. A large low field AMR is observed in all the films. AMR shows a peak below the insulator-metal transition temperature in the single crystalline films, while the same increases monotonically in the polycrystalline film. Relatively larger low field AMR (∼20% at T=78 K and H=1.7 kOe) in the polycrystalline films suggests the dominance of the shape anisotropy. 相似文献
953.
Crystal structure and magnetic properties of SmCo-based films deposited on hot Si (1 0 0) substrates
SmCo-based films were deposited on Si (1 0 0) substrates by the rf magnetron sputtering process. The growth conditions are improved for the films deposited on hot Si substrates without the annealing process. The dependence of crystal structure and intrinsic coercivity on substrate temperature is chiefly investigated. It is suggested that TbCu7 type structural films can be obtained with enhanced in-plane magnetic properties with proper substrate temperature. 相似文献
954.
Subhasis RoyS.B. Majumder 《Physics letters. A》2011,375(13):1538-1542
We have investigated the electrical and magnetic properties of solution synthesized Pb0.85La0.15TiO3-CoFe2O4 composite thin films. These composite films exhibit both polarization as well as magnetic hysteresis characteristics at room temperature. The dielectric constant of the composite films is found to increase remarkably up to 6.0 vol% CFO contents. The increase of the dielectric constant and loss tangent follow a general percolation model originally developed for metal-ceramic composites. It is argued that Maxwell-Wagner polarization, as well as diffusion of transition metal cation(s) from CFO to PLT15 lattice are responsible for the percolative behavior of the dielectric properties in these films. 相似文献
955.
956.
957.
A numerical investigation is performed into the nonlinear dynamic behavior of a clamped–clamped micro-beam actuated by a combined DC/AC voltage and subject to a squeeze-film damping effect. An analytical model based on a nonlinear deflection equation and a linearized Reynolds equation is proposed to describe the deflection of the micro-beam under the effects of the electrostatic actuating force. The deflection of the micro-beam is investigated under various actuating conditions by solving the analytical model using a hybrid numerical scheme comprising the differential transformation method and the finite difference approximation method. It is shown that the numerical results for the dynamic pull-in voltage of the clamped–clamped micro-beam deviate by no more than 2.04% from those presented in the literature based on the conventional finite difference scheme. The effects of the AC voltage amplitude, excitation frequency, residual stress, and ambient pressure on the center-point displacement of the micro-beam are systematically explored. Moreover, the actuation conditions which ensure the stability of the micro-beam are identified by means of phase portraits. Overall, the results presented in this study confirm that the hybrid numerical method provides an accurate means of analyzing the complex nonlinear behavior of common electrostatically-actuated microstructures. 相似文献
958.
报道了对JEE-4x型真空镀膜仪蒸发装置的改进以及建立蒸发材料回收装置的具体方法,并介绍了改进后该仪器在高分辨扫描电镜样品制备上的应用实例.实验证明,上述改进不但扩展了JEE—4x型真空镀膜仪的制样功能又节省了蒸发材料,集中了离子溅射法及常规高真空镀膜法的优点,完全满足SEM样品的分析要求,该方法简单易操作. 相似文献
959.
960.
掺铒光纤光源的输出光谱有两个不对称峰,但光源的应用一般都要求有比较平坦的增益输出。借鉴EDFA的增益平坦技术,简述了几种增益平坦滤波器的工作原理及优缺点,包括电介质薄膜滤光片、光纤光栅滤波器、马赫-曾德尔滤波器、光子晶体光纤光栅滤波器和基于高双折射光纤环形镜的滤波器。指出目前采用长周期光纤光栅和电介质薄膜滤光片作为光纤光源的滤波器是比较适合的选择。最后以电介质薄膜滤光片为例,给出了C波段掺铒光纤光源增益平坦的实验结果,并与滤波前做了对比分析。实验表明,滤波器的加入使光纤光源获得了增益平坦的输出光谱。 相似文献