In this study, the local velocities of the liquid sheet formed by two low-speed impinging jets were directly measured using a LDV (laser Doppler velocimetry) instrument. The spatial distribution of the local sheet velocities at the forward part of the sheet and the effects of the impingement angle and jet velocity on the sheet velocities were examined. A parabolic velocity profile across the pre-impinging jet greatly affected the sheet velocity distribution, causing the sheet velocities to decrease while the azimuthal angle increased. This was attributed to the movement of a high velocity core, existing in the pre-impinging jets, to the region around the axis of the sheet. In the radial direction, the local sheet velocities were a little low around the impinging point, and remained constant, but then decreased near the edge of the sheet. The dependence of sheet velocities on the impingement angle was confirmed, and the tendency towards an even distribution of sheet velocities was found to increase as the impingement angle increased. With the exception of the lowest velocities measured near the edge of the sheet, the local sheet velocities at the forward part of the sheet were higher than the mean jet velocity.

The correlation coefficient (CC) method, which was proposed by our research group, is applied to digital particle holography to locate the focal plane of particles. It uses the fact that the CC is maximum at the focal plane. The factors influencing this method are discussed with a numerical simulation of holograms. For real holograms, the Wiener filter was proposed to process both recorded holograms and reconstructed images. The application results using the dot array target showed that the Wiener filter is a very effective tool for processing holography-related images. The effects of the dot size and the object distance on the errors in the determination of the focal plane by the CC method were investigated by using the calibration target.

No abstract

No abstract

Mol% of europium doped strontium aluminate (SrAl 2 O 4 :Eu 2+) coatings on silicon substrates were prepared by electrostatic spray deposition method using a salted sol-gel derived solution as a starting material. Asdeposited films at 100 • C for 5 h were heated at 1100 • C for 2 h under a reducing ambient atmosphere of 95%N 2 + 5%H 2. Nanocrystalline SrAl 2 O 4 film was confirmed by surface morphological and crystallographic analyses. Monitored at 520 nm, the excitation spectrum showed a broad band from 300 ∼ 500 nm and the emission intensity showed a maximum yellow peak intensity at 512 nm with a broad band from 460 ∼ 610 nm.