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31.
YAG:Ce Phosphors for WLED via Nano-Pesudoboehmite Sol-Gel Route 总被引:5,自引:0,他引:5
The sub-micron sized YAG : Ce phosphors were synthesized via a modified sol-gel method by peptizing nano-pesudoboehmite particulate. It is found that YAG phase from the dried gel powders appears at 1000 ℃ then the pure YAG phase exists at a relatively lower sintering temperature of 1400 ℃. The smaller sizes of phosphors in the ranges of 1 - 3 μm are obtained due to the contribution of seeding effects of nano-sized alumina particles to strengthen each step of the processes. Both the excitation and emission spectra of photoluminescence of the phosphor obtained at 1400 ℃ meet well with the spectroscopic requirements of the WLED phosphors. 相似文献
32.
Delphi开发环境下的实时数据采集程序设计 总被引:3,自引:1,他引:2
本文介绍了利用Delphi开发平台开发数据采集程序的两种方法,并结合某测深仪给出了一个编程的例子. 相似文献
33.
Woo-Seog Song Seungbae Lee Dong-Shin Shin Yang Na 《Journal of Mechanical Science and Technology》2006,20(6):905-913
The instability curve of a Rijke tube system was obtained accurately by following different paths of heat power and flow-rate
for three regions and by defining its locus from the criterion based on the measured sound pressure levels. The unstable limits
in the region of flow-rate lower than that at the minimal power are compared with previous data. To observe the effect of
turbulence on the unstable limits, inflow turbulence was introduced by placing a bundle of circular cylinders upstream of
the heating part (50< Red< 700). The large-amplitude inflow fluctuation may delay the transition of the chamber acoustic mode to the unstable zone
even at a sufficient power. 相似文献
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X.B. Tu B. Jian S.J. Wang H.Y. Bian J. Wang S.G. Li 《Tunnelling and Underground Space Technology incorporating Trenchless Technology Research》2005,20(4):1106
Granite is commonly recognized as an ideal medium for underground construction. However, in the site investigation for Heimifeng Pumped Storage Power Station project, it was found that there are swelling behaviors induced by alteration in granite and eventually causing slaking and disintegration of rock blocks. The study shows that hydrothermal alteration in granite is primarily due to the intrusion of multi-phase igneous magma. The clay minerals, such as montmorillonite, chlorite, kaolinite, are the main causes for the swelling behavior of granite. In the exploratory adits, alteration was observed to occur mainly along faults or fractures in the rock masses and resulted in roof caving if water is present. Some of the highly altered borehole cores swell and crack within 24 h in water and eventually disintegrate completely. From the testing results on the samples, the maximum axial free swelling strain is about 1.2%, while the maximum axial confined swelling strain is around 0.1% with swelling stress less than 25 kPa. Under free swelling tests, 80% of swelling is completed within 24 hours. Under confined swelling condition, swelling process is completed within 1 h for some samples, with 80% of maximum swelling strain finished within around 22 h for most of the samples. Contraction of samples occurs after swelling completed. The strength of granite, reflected by deformation and elastic moduli, shear strength, decreases due to alteration. The deformation and elastic moduli are even lower compared to highly weathered rock. The shear strength is between that for highly weathered and slightly weathered rocks. The swelling characteristics of the altered rock present great challenges for support or lining during construction and operation stages. Support or lining shall be in place immediately after excavation. Since the rock may swell when encountering water, the shotcrete shall be designed accordingly. During the construction of access tunnel and caverns, water shall be drained in time. Drainage directly from surface shall be avoided so as to prevent floor heave. 相似文献
36.
本文介绍 IBM-PC 系列机中的定时信息。进而介绍利用这些信息实现各类长、短定时间隔的编程技巧,并以实例说明之。 相似文献
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注水开发的低渗透油藏存在启动压力和压力敏感性,使开发难度加大。当流压低于饱和压力以后,流入动态指示曲线凹向压力轴,会出现一个产量最大点。在前人研究的基础上,从平面径向拟稳态渗流规律出发,考虑启动压力梯度和压力敏感效应对油藏渗流的影响,与油相和液相相对流动能力方程相结合,建立了具有最大产量点的低渗透压力敏感油藏直井流入动态方程,据此可对油藏产能进行评价预测,确定出油井最低允许流动压力和油井的合理工作制度。在龙南、新站油田的应用表明,预测值与实测值比较吻合,满足矿场工程精度要求,说明所建立的流入动态方程能有效评价预测油井产能和确定油井允许的最小流压界限,为充分发挥油井生产能力、合理高效开发低渗透压力敏感油藏提供了理论依据。 相似文献