Resonant behaviors of ultra-sonic gas atomization nozzle with zero mass-flux jet actuator

The resonant behaviors of an ultra-sonic gas atomization nozzle with a zero mass-flux jet actuator were numerically investigated with FLUENT software by using a double precision unsteady two-dimensional pressure-based solver. The Spalart-Allmaras turbulence model was adopted in the simulations. Numerical results indicated that the oscillation properties of the gas efflux were effectively improved. Several resonatory frequencies corresponding to different vibration modes of gas were distinguished in the nozzle. With the changing of nozzle geometric parameters, different characters among those modes were elucidated by analyzing the propagations of pressure waves.

Properties of acoustic resonance in double-actuator ultra-sonic gas nozzle:numerical study

The ultra-sonic gas atomization （USGA） nozzle is an important apparatus in the metal liquid air-blast atomization process. It can generate oscillating supersonic gas effiux, which is proved to be effective to enforce the atomization and produce narrow-band particle distributions. A double-actuator ultra-sonic gas nozzle is proposed in the present paper by joining up two active signals at the ends of the resonance tubes. Numerical sim- ulations axe adopted to study the effects of the flow development on the acoustic resonant properties inside the Haxtmann resonance cavity with/without actuators. Comparisons show that the strength and the onset process of oscillation are enhanced remarkably with the actuators. The multiple oscillating amplitude peaks are found on the response curves, and two kinds of typical behaviors, i.e., the Hartmann mode and the global mode, are discussed for the corresponding frequencies. The results for two driving actuators are also investigated. When the amplitudes, the frequencies, or the phase difference of the input signals of the actuators are changed, the oscillating amplitudes of gas effiux can be altered effectively.

Gastric duplication associated with pancreas divisum diagnosed by a multidisciplinary approach before surgery

We report a unique case of communicating gastric duplication associated with pancreas divisum,diagnosed with a multidisciplinary approach,including X-rays,computed tomography,magnetic resonance imaging,esophagogastro duodenoscopy,ultrasound endoscopy and histology. We believe that this approach constitutes a fuller diagnostic evaluation,resulting in better and safer surgery.

Study on Ultra-sonic Frequency Pulse TIG of Titanium Alloy

Ti-6Al-4V alloy is used extensively in aerospace and aircraft because of its excellent comprehensive properties and outstanding machinability. Ti-6Al-4V alloy was welded by conventional tungsten iner-gas arc welding (TIG) and ultra-sonic frequency pulse TIG welding (U-TIG) respectively. The welding quality was tested by X-ray, and the mechanical properties of welded joint were tested , the microstructure and the fracture appearance of welded joint were observed by means of optical microscope and SEM .The results show that the joints were welded successfully by U-TIG welding, U-TIG welding could reduced pores defects of welded joint. With the increment of ultra-sonic pulse frequency, the microstructure became more and more fine and was inclined to equiaxed crystal. Moreover, the properties of joint by U-TIG welding were improved compared with that of conventional TIG. Tensile fractures of joints by TIG welding and U-TIG welding all presented character of quasi-cleavage crack, but the cellular dendrite depredation was not observed obviously in U-TIG joint.

Effect of pulsed ultrasound assisted extraction and aqueous acetone mixture on total hydrolysable tannins from pomegranate peel

Pomegranate peels are disposed of as waste even though it is an eminent source of total hydrolysable tannins(THT)and possesses a great worth for recycling.The present study was carried out with the hypothesis that pulsed system ultrasound-assisted extraction(PSUAE)technique optimization would aid in retaining high extract yield and THT recovery yield from pomegranate peel extract(PPE)with enhanced antioxidant potential.The extraction was performed at various conditions regarding solvent concentration(30-90% of acetone),solvent-feed ratio(10-30 mL/g),extraction time(10-20 min),and ultrasound amplitude(40-80%)for maximum extract yield,THT and antioxidant activity(AA).To model and optimize the process conditions tools namely response surface methodology(RSM)and artificial neural network(ANN)were applied.For solvent concentration,solvent-feed ratio,extraction time,and amplitude the optimal conditions attained with aid of RSM and ANN were:56%,26.5 mL/g,15 min,55%,and 45%,23 mL/g,15 min,50% respectively.The extract yield and THT content determined with RSM and ANN optimized values were 51.2%,86.4 mg TAE/g,and 62%,98.1 mg TAE/g,respectively.The mean square error value displayed the minimum and R^(2) exhibited maximum value in case of ANN compared to RSM model.PSUAE significantly augmented the AA of PPE to 77.2±0.50% compared to 49.7±0.35% of conventional extraction.FTIR and HPLC analysis established that PPE produced from PSUAE contains a significant amount of THT compounds(gallic acid and tannic acid derivative).SEM elucidated that the sonication effect resulted in peel cell wall disruptions ensuing in elevated extraction of THT.Therefore,this pulsed mode of ultrasound extraction could be regarded as an easy,cost-effective,and competent technique for the extraction of preferred natural THT from pomegranate peels that possess high prospective to be applied in food and nutraceutical formulations.