放弃一个很爱你的人，并不痛苦；
放弃一个你很爱的人，那才痛苦；
爱上一个不爱你的人，那是更痛苦。
若是有缘，时间、空间都不是距离；
若是无缘，终是相聚也无法会意。
凡事不必太在
千万不能把时间全部消耗在实验台上。看文献、看书、看别人的操作、听别人的经验、研究别人的思路，边做边思考。要学会比较，不要盲从。否则，会被一些小小的问题困扰许久。
2.准备越充分，实验越顺利。
古人云，磨刀不误砍柴工。前期的知识储备、文献储备、材料准备、方法准备可以避免手忙脚乱，充分的预实验使你充满信心。一步一个脚印，就不必“从头再来”。最不能容忍的是在开始的几步偷懒，造成后面总有一些无法排除的障碍。
3.记录真实详尽。
人总是有一点虚荣心的。只把成功的步骤或漂亮的结果记到实验记录里，是很多人的做法。殊不知，许多宝贵经验和意外发现就这样与你擦肩而过。客观、真实、详尽的记录是一笔宝贵的财富。
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标签：科学 |
Description: Measure fluid mixing in a two dimensional plane of a fluid flow. Can also be used to measure two dimensional temperature fields. Technique involves videoing laser induced fluorescence from a laser sheet passing through a fluid flow containing a fluorescent dye. The fluorescence intensity will contain the mixing information of the fluid flow.
Parameter Space Covered: Aqueous environments, non-reacting flows. Can be used for both low and high Re number flows.
Limitations:
1) The spatial and temporal resolution will be dictated by the type
of camera us
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标签：科学 |
Brief Description: This technique is very similar to PSP except that the coating is temperature sensitive rather than pressure sensitive. In the case of TSP, changes in the free volume in the binder affect the luminescence, as the temperature increases, the luminescence decreases. As in PSP, a ratio of two images provides the temperature. In this case, one image is taken at a known, constant temperature, and the other is taken at the unknown conditions. The ratio of the two images is then converted to temperature using the appropriate calibration. As in PSP testing, during the acquisition of the images, the test surface is exposed to excitation light in only a narrow frequency band. The detector is then notch filtered to pass only the luminescence band for the particular probe molecule. Of course, these two bands must not overlap.
Brief Description:
Technique for measuring velocity of flowfield by pulsing two short-duration laser pulses at times characteristic of the flow velocity in a flowfield seeded with very small particles. The laser light is formed into a sheet, and the resultant scattered light, which is at the same frequency as the incident laser, is recorded either on film or CCD camera, oriented perpendicular to the plane of the light sheet. The image is analyzed to determine the particle separation, and hence the velocity of the particles, which are assumed to follow the path of the flow. PIV ca
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标签：科学 |
Brief Description: The use of cheap, compact, reliable, solid-state near infra-red lasers for laser measurements. Until very recently these lasers have been used for line of sight absorption measurements usually via modulation spectroscopy. Very recently high power diode laser arrays have been developed that make it possible to use these near-infrared lasers in Rayleigh and Raman scattering measurements to obtain spatially resolved measurements of velocity, density, individual species concentrations, and temperature. As of this writing (January 1996) only preliminary results have been obtained and measurements in flow systems have not yet been demonstrated.
Parameter Space
Covered:
Brief Description: LIF is a process whereby molecules/atoms are excited to higher electronic energy states via laser absorption and subsequently fluoresce; the intensity of this fluorescence is, in general, a function of the species concentration (number density), and the gas temperature and pressure. Among other things, this fluorescence is linearly dependent on the absorber number density. By virtue of the fact that the energy states of molecules/atoms are quantized, the spectral absorption regions are discrete; however, for large molecules, the spacing of the discrete transitions may be sufficiently small (and the number of transitions sufficiently great) that discrete absorption regions are not observed (only absorption bands are observed). Typically, fluorescence occurs at wavelengths greater than or
