vapor-phase methylation of toluene using methanol and its isopropylation with 2-propanol has been investigated ina down flow reactor under atmospheric conditions using n2 carrier over a series of surface modified andunmodified zsm-5 (si/al= 60-170) loaded with h3po4, differing in the external surface treatment of the zeolites.the feed molar ratios of toluene/methanol and toluene/2-propanol were...

Phase contrast velocimetry can be utilized to measure complex flow for both quantitative and qualitative assessment of vascular hemodynamics. However, phase contrast requires that a maximum measurable velocity be set that balances noise and phase aliasing. To efficiently reduce noise in phase contrast images, several investigators have proposed extended velocity encoding schemes that use extra ...

Due to the important relationship between ultrasonic velocity and some properties of sample, the measurement of velocity of ultrasound is widely needed in various fields. In this paper, based on phase-locked loop technique, a new hybrid circuit is designed for ultrasonic velocity measurement and named as UV-PLL. In order to improve the stability of phase and achieve the ability of fast locking,...