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241.
TaN underlayers for spin valves were studied, which were deposited directly on top of Si substrates. The experimental results obtained with the TaN underlayer were compared with those obtained with other (Ta, Mo, and MoN) underlayers. The spin valve structure was Si/Underlayer(tÅ)/NiFe(21 Å)/CoFe(28 Å)/Cu(22 Å)/CoFe(18 Å)/IrMn(65 Å)/Ta(25 Å). The TaN underlayer for a spin valve element exhibited good adhesion to the Si substrate. The XRD patterns of the annealed TaN on bare Si substrate at 900 °C showed no Ta silicide phases, which suggests that the TaN layer may also be used as a diffusion barrier between Si substrate and the ensuing spin valve active layers, as well as an underlayer. A spin valve element having TaN underlayer deposited directly on top of a Si substrate showed a high MR ratio of about 8.3% after annealing at 200 °C. It is concluded that it is advantageous to use a TaN underlayer if one wants to fabricate spin valve elements directly on top of Si substrates. 相似文献
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243.
Under natural conditions, wind turbines are inevitably eroded by the action of sand-wind flow. To further investigate the effects of dust drift on the erosion of the wind turbine blades in sand-wind environments, the effects of the wind velocity, particle diameter, and particle density on the erosion of wind turbine airfoils are studied, and the effects of the particle Stokes number on the airfoil erosion are discussed. The results show that, when the angle of attack(AOA) is 6.1°, there will be no erosion on the airfoil surface if the particle Stokes number is lower than 0.013 5, whereas erosion will occur if the particle Stokes number is higher than 0.015 1. Therefore, there exists a critical range for the particle Stokes number. When the particle Stokes number is higher than the maximum value in the critical range, airfoil erosion will occur. The result is further confirmed by changing the particle diameter, particle density, and inflow speed. It is shown that the erosion area on the airfoil and the maximum erosion rate are almost equal under the same particle Stokes number and AOA. The extent of airfoil erosion increases when the particle Stokes number increases, and the critical particle Stokes number increases when the AOA increases. Moreover, the geometric shape of the airfoil pressure surface greatly affects the airfoil erosion, especially at the curvature near the leading edge. 相似文献
244.
A three-phase confocal elliptical cylinder model is proposed to analyze micromechanics of one-dimensional hexagonal piezoelectric quasicrystal (PQC) composites. Exact solutions of the phonon, phason, and electric fields are obtained by using the conformal mapping combined with the Laurent expansion technique when the model is subject to far-field anti-plane mechanical and in-plane electric loadings. The effective electroelastic constants of several different composites made up of PQC, quasicrystal (QC), and piezoelectric (PE) materials are predicted by the generalized self-consistent method. Numerical examples are conducted to show the effects of the volume fraction and the cross-sectional shape of inclusion (or fiber) on the effective electroelastic constants of these composites. Compared with other micromechanical methods, the generalized selfconsistent and Mori-Tanaka methods can predict the effective electroelastic constants of the composites consistently. 相似文献
245.
液压换向阀的耦合水击振动特性研究 总被引:1,自引:0,他引:1
以某型舵机操纵液压换向阀为例,运用特征线法,对其由于自激振动以及启闭动作产生水击诱发非线性耦合振动现象的机理进行理论分析,获得换向阀水击振动的动态特性.通过实验验证,换向阀控制口水击压力幅值与计算结果偏差为2.87%,且压力变化趋势与计算结果基本一致.该结果可为掌握液压系统的振动特性、采取振动控制措施以及换向阀的设计和改进提供理论依据. 相似文献
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频率驱动液晶光阀的电光特性研究 总被引:4,自引:1,他引:3
讨论了液晶光阀频率驱动方式的原理, 并分析了液晶光阀在频率驱动方式下的电光特性。在特定的交流电压下改变外加电场频率, 测量了TB3639型液晶光阀在频率驱动方式下的电光特性关系曲线。测量结果表明,TB3639液晶光阀在可见光区域具有电光显示灰度变化特性,不仅能实现黑白显示,也能实现不同灰度级显示。频率驱动方式在可见光的范围内对不同波长的透射率变化趋势影响大致相同,在应用中可避免出现色差较大的现象。这种新型频率驱动方式对液晶器件的显示有改善作用,将开拓液晶显示器件的新应用, 具有实际应用价值。 相似文献
249.
液晶空间光调制器在自适应光学中的应用 总被引:3,自引:0,他引:3
本文主要包括两方面的内容,一方面描述用液晶光阀产生空间与时间性能可控的小尺寸薄相位屏;另一方面则讨论用液晶空间光调制器实现波前相位畸变校正的可能性。从而表明,这类价格低廉、结构简单而性能可靠的非线性光学器件可望在高性能新型自适应光学系统中得到广泛应用。 相似文献
250.
In this paper, the method of dynamic flow birefringence (DFB) have been studied extensively under the consideration of an application to cardiovascular models. The method utilises the optical interference patterns observed in the birefringent flow for determination of the fluid shear stress and velocity distribution. In order to measure a flow in a cardiovascular model, an assumption of a simplified stress–optical relation in a pulsatile flow is suggested and special experimental techniques such as birefringent fluid for simulating blood and new experimental system have been developed. Application studies focus on pulsatile flows in typical models, namely arterial bifurcation and mechanical heart valves. Experimental results are discussed and compared with those of other researchers. 相似文献