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排序方式: 共有78条查询结果,搜索用时 15 毫秒
1.
花丝内插物强化竖直管内凝结换热的实验研究 总被引:1,自引:1,他引:0
1前言大空隙率多孔体管内插物-绕花丝内插物,被认为是强化管内凝结换热的最有效途径之一[1].但以往的研究,由于实验雷诺数范围较小,蒸汽速度较低,要正确全面评价其性能尚显不够。本文在原有工作的基础上,进一步完善了实验系统,改进了测试手段,扩大了实验雷诺数范围,并测试了其阻力性能,对花丝内插物强化管内凝结换热进行了较深入全面的实验研究,以全面评价花丝内插物对管内凝结换热的强化效果。2实验系统本文实验系统如图1所示。实验段是一个竖直套管冷凝器,如图2所示.本试验研究蒸汽完全凝结时的传热。凝结水流量采用容积法计… 相似文献
2.
高温固相法合成Ba0.11Sr2.89-2x-2yCexTbyNax+yAlO4F荧光粉,并用X射线衍射(XRD)、荧光光谱(PL)测定分析了其晶体结构及光谱性质。结果表明:当Tb3+掺杂量x=0.07时,发光强度最高,发射主峰位于545 nm,并进一步研究了Ce3+,Tb3+共掺的样品中Ce3+→Tb3+能量传递过程。其次,测试由近紫外LED(~380 nm)和三基色荧光粉(Ba0.11Sr2.89Ce0.01Tb0.07Na0.08AlO4F,BAM and Sr2Si5N8:Eu2+)封装的白光LED光电性能,其色品坐标(x=0.3223,y=0.3408),色温5500 K,显色指数为86.26。因此,Ba0.11Sr2.89-2x-2yCexTbyNax+yAlO4F可作为一种潜在的适用于近紫外LED激发的荧光材料。 相似文献
3.
TBP萃淋树脂吸附钪的性能研究及应用 总被引:6,自引:0,他引:6
本文采用静动态两种方法较系统地研究了TBP草淋树脂在高氟酸介质中吸附钪的性能,并用自己设计的减压微色谱柱考察了共存离子的萃取色谱行为,选择了分离微量钪的最佳条件,获得了良好的分离效果,用于标准矿样中微量机的测定,分析结果与标准值相近。 相似文献
4.
纳米SiC蓝光发射的研究 总被引:4,自引:0,他引:4
在4.68eV的激光激发下,室温CVD合成的纳米SiC粉体,可发射475nm的蓝光,经600~1100℃在N2气氛下进行快速退火(RTA)处理,其荧光强度随退火温度升高而增强,当T≥900℃时,荧光强度下降,但发光峰位与退火温度无关.通过XRD、IR、TEM、XPS等研究,认为纳米SiC中与氧有关的缺陷可能是引起475nm蓝光发射的主要原因 相似文献
5.
This paper describes a novel fiber-coupled heterodyne interferometer using a micro-electro-mechanical system (MEMS) mirror
and an f-theta lens. In this interferometer system, the cross-polarized laser beams operating at 2 μm with the frequency difference
of 100 kHz are introduced by means of the two acousto-optic modulators (AOM). The sample with diameter of 300 mm is uniformly
scanned by the 1 mm laser beam with the help of the combined optical scanning configuration, a MEMS mirror and an f-theta
lens. The output intermediate signal from the two channels, reference channel and the measurement channel, are processed in
the 12 bit analog-to-digital (A/D) process system. Details of our interferometer scheme are discussed. 相似文献
6.
In this paper, we consider the block-GMRES method with deflated restarting for solving nonsymmetric linear systems with multiple right-hand sides. We modify slightly the restarted block-GMRES method with deflation of eigenvalues proposed by Morgan to obtain a new one. It is shown that the modified method is mathematically equivalent to the Morgan’s original method. However, the error analysis shows the modified version minimizes the numerical errors during a restart and therefore is better suited if the linear systems have to be solved with high precision. Numerical experiments report the effectiveness of the modified method. 相似文献
7.
<正>A non-destructive technique for subsurface measurements is proposed by combining light scattering method with laser confocal scanning tomography.The depth and distribution of subsurface defect layers are represented in term of scattered light intensity pattern,and three types of fused silica specimens are fabricated by different grinding and polishing processes to verify the validity and effectiveness.By using the direct measurement method with such technique,micron-scale cracks and scratches can be easily distinguished,and the instructional subsurface defect depths of 55,15,and 4μm are given in real time allowing for an in-process observation and detection. 相似文献
8.
9.
Physical and chemical properties of bio-oils from microwave pyrolysis of corn stover 总被引:4,自引:0,他引:4
Yu F Deng S Chen P Liu Y Wan Y Olson A Kittelson D Ruan R 《Applied biochemistry and biotechnology》2007,137(1-12):957-970
This study was aimed to understand the physical and chemical properties of pyrolytic bio-oils produced from microwave pyrolysis of corn stover regarding their potential use as gas turbine and home heating fuels. The ash content, solids content, pH, heating value, minerals, elemental ratio, moisture content, and viscosity of the bio-oils were determined. The water content was approx 15.2 wt%, solids content 0.22 wt%, alkali metal content 12 parts per million, dynamic viscosity 185 mPa.s at 40 degrees C, and gross high heating value 17.5 MJ/kg for a typical bio-oil produced. Our aging tests showed that the viscosity and water content increased and phase separation occurred during the storage at different temperatures. Adding methanol and/or ethanol to the bio-oils reduced the viscosity and slowed down the increase in viscosity and water content during the storage. Blending of methanol or ethanol with the bio-oils may be a simple and cost-effective approach to making the pyrolytic bio-oils into a stable gas turbine or home heating fuels. 相似文献
10.
溶解度的概念及有关百分比浓度的计算是初中化学的屯点和难点,应该安排一个必做实验来加深学生对这墓本概念的理解和应用。由于原教材中盐的挤解度测定方法、操作要求高而作为学生选做实验。 相似文献