Experimental study of ultrasonic atomizer effects on values of EC and pH of nutrient solution

The objectives of this research were to reveal how main working parameters of ultrasonic atomizers would influence key properties of the atomized nutrient solution in an aeroponics system.The Yamazaki tomato nutrient solution was selected as a nutrient example.Uniform design(UD)method U_(12)(12^(2)×13)was adopted to arrange the test.In this test,spraying time and interval time were taken as quantitative factors with 12 levels(10,20,30,40,50,60,70,80,90,100,110,and 120 min,respectively),and ultrasonic atomizer frequency was taken as qualitative factor with 3 conditions(28 kHz,107 kHz,1.7 MHz).Based on test data,two regression formulations used to predict the values ofΔEC,andΔpH of atomized Yamazaki tomato nutrient solution was established and inspected.The spraying interval time of ultrasonic atomizers had no significant effect on EC and pH of the atomized Yamazaki tomato nutrient solution;the ultrasonic atomizer frequency was more effective than spraying time on the values of EC and pH;the values of EC and pH became maximum at(f_(3),T_(1))=(1.7 MHz,120 min)and minimum at(f_(1),T_(1))=(28 kHz,10 min).It was concluded that the effect of high-frequency(1.7 MHz)ultrasonic atomizer on EC and pH of the Yamazaki tomato nutrient solution was beyond the standard value for tomato growth.Therefore,the high-frequency(1.7 MHz)ultrasonic atomizer is not suitable for aeroponics cultivation when using the Yamazaki tomato nutrient solution as aeroponics nutrient solution.

Numerical simulation of flow in Hartmann resonance tube and flow in ultrasonic gas atomizer

The gas flow in the Hartmann resonance tube is numerically investigated by the finite volume method based on the Roe solver. The oscillation of the flow is studied with the presence of a needle actuator set along the nozzle axis. Numerical results agree well with the theoretical and experimental results available. Numerical results indicate that the resonance mode of the resonance tube will switch by means of removing or adding the actuator. The gas flow in the ultrasonic gas atomization （USGA） nozzle is also studied by the same numerical methods. Oscillation caused by the Hartmann resonance tube structure, coupled with a secondary resonator, in the USGA nozzle is investigated. Effects of the variation of parameters on the oscillation are studied. The mechanism of the transition of subsonic flow to supersonic flow in the USGA nozzle is also discussed based on numerical results.

Characteristics and Microstructure of a Hypereutectic Al-Si Alloy Powder by Ultrasonic Gas Atomization Process

A hypereutectic Al-Si alloy powder was prepared by ultrasonic gas atomization process. The morphologies, microstructure and phase constituent of the alloy powder were studied. The results showed that powder of the alloy was very fine and its microstructure was mainly consisted of Si crystals plus intermetallic compound A19FeSi3, which were.very fine and uniformly distributed.

Nitrogen monoxide vector of ultrasonic atomizing inhalation improves vertebro-basilar artery insufficiency Hemodynamic changes are detected by transcranial Doppler test

BACKGROUND： Latest researches at home and abroad indicate that glycerol trinitrate plays its function because it can metabolize into nitrogen monoxide （NO） in vivo. OBJECTIVE： To study the therapeutic effects of NO vector of ultrasonic atomizing inhalation on vertebro-basilar artery insufficiency （VBI） through transcranial Doppler （TCD） detection and serum NO content and indirect effect of TCD on cerebral blood flow changes. DESIGN： Randomized grouping and controlled clinical study. SETTING： Department of Neurology, the Fourth People＇s Hospital of Jinan. PARTICIPANTS： A total of 130 patients who were diagnosed as VBI were selected from Department of Neurology, the Fourth People＇s Hospital of Jinan from December 2001 to December 2005. The involved inpatients were checked by CT and MRI, and met the VBI diagnostic standard enacted by the Fourth National Academic Meeting of Cerebrovascular Disease in 1995. All patients and their relatives provided the confumed consent. They were randomly divided into low-dose treatment group （n =60）, high-lose treatment group （n =30） and control group （n =40）. METHODS： Patients in the low-dose and high-dose treatment groups were given ultrasonic atomizing inhalation of 3 mg and 5 mg glycerol trinitrate, respectively, for 20 minutes, once a day. In addition, ligustrazine and energy mixture were used once a day for three days in a course. Cases in the control group were only given ligustrazine and energy mixture. All selected cases accepted TCD, blood NO content was checked at the time of beginning, after the first time and after a period of treatment. According to the TCD test, VBI patients were divided into two groups （high-low flow velocity）. The vertebral artery （VA） and basal artery （BA） of left or right sides were detected by 2 Hz detector via occipital window. MAIN OUTCOME MEASURES： ①Blood flow velocity of systolic phase, blood flow velocity of diastole phase and vascular resistance in left and right VA and BA detected by using TCD before treatment, after treatment for one course; ②content of serum NO indirectly measured by using nitric acid disoxidation technique. RESULTS： All 130 VBI patients were involved in the final analysis. ①Changes of hemodynamic indexes： Systolic phase of VA and diastole phase of BA were higher in low-dose treatment group than that in the control group after first treatment, and there was significant difference （P 〈 0.05）; meanwhile, systolic phase and diastole phase of VA and systolic phase of BA were also higher in treatment group than that in the control group after one course （P 〈 0.05）. However, both systolic phase and diastole phase of VA and BA were lower in high-dose treatment group than that in the control group after first treatment and one course, and there was significant difference （P 〈 0.05）. ②Content of serum NO： After first treatment, there was no significant difference between low-dose treatment group and high-dose treatment group （P 〉 0.05）; but both groups were higher than control group, and there was significant difference （P 〈 0.05, 0.01）. CONCLUSION： NO vector of ultrasonic atomizing inhalation can improve VBI so as to improve cerebral blood-supply state.

EVALUATON OF MICROWAVE PLASMA TORCH FOR ATOMIC FLUORESCENCE SPECTROMETRY WITH AN ULTRASONIC NEBULIZATION SAMPLE INTRODUCTION SYSTEM

In this paper, a new MPT(microwave plasma torch) device has been used as a atomizer for atomic fluorescence spectrometry. Spme elements, such as Zn, Cd, Hg, Pb, As, Co, Mg, Cu, Ag, Mn, Fe have been investigated in detail.

Preparation and characterization of Y_3Al_5O_(12):Ln(Ln=Eu,Ce) phosphor powders by ultrasonic atomization and co-precipitation process

A novel technique for YAG:Ln(Ln=Eu,Ce) phosphor powder synthesis with a nanocrystalline structure was developed.Nanocrystalline YAG:Ln powder was prepared by an ultrasonic atomization and co-precipitation method using a mixture solution of ammonium hydroxide(NH3·H2O) and ammonium hydrogen carbonate(NH4HCO3) as precipitant.The as-prepared nano-powders were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),and fluorescence spectrometer.The obtained phosphor powders were homogenous and in size of 50-70 nm.The results demonstrated that by using ultrasonic atomization and co-precipitation process,we could synthesize a good quality YAG:Ln(Ln=Eu,Ce) phosphor powder that had many potential applications.

Design and experiment of low-frequency ultrasonic nozzle integrating air-assistant system and acoustic levitation mechanism

Ultrasonic atomization nozzles are generally divided into two categories:high frequency and low-frequency ultrasonic atomization nozzles.Compared with high-frequency ultrasonic atomization nozzles(working frequencies>1 MHz),low-frequency ultrasonic atomization nozzles are not sensitive to clarity,temperature and viscosity of the liquid.However,they can control atomization quantity precisely,but the sizes of droplets generated by them are relatively large.In aeroponics cultivation,and precision welding,in such both cases,precise spraying control and tiny droplet sizes are expected.Therefore,how to decrease droplet size using low-frequency ultrasonic atomization nozzles is a valuable issue.In this paper a 60 kHz low-frequency ultrasonic atomization nozzle integrating air-assistant system and acoustic levitation mechanism was proposed and designed.Furthermore,the design was verified by FEA(Finite Element Analyzes)and impedance analyzer PV70A,and the verified results indicated relative design error was 0.49%.Driving voltage,spout angle,air pressure and levitating ball were taken as influential factors in the experimental protocol to the character in spray properties of this designed nozzle.A laser particle size analyzer was used to measure droplet sizes.Experiment results indicated that:the diameters of droplets generated by this nozzle at driving voltage 46 V were smaller than those at 40 V driving voltage;Both the assistant air and levitation mechanism could effectively change the diameters and uniformity of droplets;The minimum values of D10,D50,and D90(D10,D50 and D90 were mean diameters when cumulative percentages of the samples’diameter were 10%,50%and 90%,respectively)were 23.06μm,31.14μm and 41.38μm,respectively.However,all those minimum values were presented at the same run(spout angle 0°,air pressure 0.05 MPa,having levitated ball,driving voltage 46 V);Levitating ball above the atomization surface would make droplet sizes more uniform and tinier.More importantly,the famous Lang equation which assumes that droplet diameters just decided by the liquid surface tension,density and ultrasonic atomizer’s working frequency needed to be revised because experimental results indicated that changing vibration amplitudes of ultrasonic atomization surface might lead to the changing of the droplet diameters and those results were at odds with the Lang equation.

Degradation of 2,4,6-trichlorphenol by producing hydrogen using ultrasonic mist generated from photocatalysts suspension

Photocatalytic hydrogen production synergized with the oxidation of pollutants is an environmentally friendly and economical approach to generate clean energy and remove the pollution from environment.In this study,photocatalytic hydrogen production cooperating with 2,4,6-trichlorophenol(2,4,6-TCP)degradation have been reinforced by introducing an ultrasonic atomization.The degradation of 2,4,6-TCP in a mist of three photocatalysts(g-C3N4,TiO2,and Bi2O3)generated by ultrasonic atomization was performed under 254 nm ultraviolet(UV254)light irradiation.The results showed that,under UV254 irradiation,three different photocatalysts(g-C3N4,TiO2,and Bi2O3)all accelerated both hydrogen production and 2,4,6-TCP degradation.Additionally,2,4,6-TCP degradation and photocatalytic hydrogen production exhibited an obvious synergistic effect,since 2,4,6-TCP has a strong tendency to react with photo-generated holes and their second radicals so as to inhibit the recombination of carriers,and thus improved the efficiency of hydrogen production simultaneously.Moreover,by introducing ultrasonic atomization,the atomized droplets acted as micro-photocatalytic units to replace the macrophotocatalytic reaction reactor.Therefore,the mass transfer distance for free radicals was restricted and the utilization of light energy by photocatalysts was increased.Further,the reaction efficiency was improved.The results reveal environmentally friendly and economical potential of hydrogen production by photocatalytic degradation of 2,4,6-TCP in atomized droplets.

WC Particle High Speed Steel Composites Manufactured by Ultrasonic Spray Forming

The process of manufacturing high speed steel matrix composites reinforced by WC particles was studied. The changes in microstructures and mechanical properties of composites with WC particles were also investigated. The results show that increasing the deposition height can significantly enhance the bending strength and hardness of the alloy, and that the fishbone like carbide ledeburite structure gradually diminishes as the WC particles content increases. It was discovered that the hardness of the composites increases due to the increase of pointlike carbide ledeburite, accompanying the breaking of the fishbone like and the net like carbides. However, the bending strength deteriorates due to excessive WC particles increasing the brittle interfacial phase.

Development and experiments of low frequency ultrasonic electrostatic atomizing nozzle with double resonators

Fine droplets with high adhesion can greatly improve the efficiency of atomization culture.Therefore,the development of a spray nozzle that can produce fine fog droplets with high adhesion is of great significance for aeroponics.Compared to piezoelectric ultrasonic atomizer,Hartmann resonator low-frequency ultrasonic electrostatic atomizer has the advantages of large atomization volume and constant liquid chemical structure,but the droplet size is larger.High-speed gas can generate low-frequency ultrasonic vibration sound waves in Hartmann resonator.The frequency and intensity of sound waves determine the atomization performance of supersonic atomizer nozzle.However,very few research literatures can be found on how the structure and operating parameters of Hartmann resonator affect the atomization performance.In order to improve the atomization performance of ultrasonic atomizer,a two-stage Hartmann resonator low-frequency ultrasonic electrostatic atomizer was designed.The shrinkage-type Laval tube was designed by fluid mechanics theory,and the design results were verified by fluent software.The virtual orthogonal test method was used to optimize the structure parameters of two-stage resonator and spray test was carried out.The results showed that when the included angle between the two stage resonators was 80°,the diameter was 4.86 mm,the tube length ratio was 1.0 and the gas pressure was 0.5 MPa,the droplet size could reach 22.05μm.Additionally,compared with the traditional Hartmann cavity with 90°included angle,the droplet size was decreased by 63%.The annular electrode was used as the charging electrode,and Comsol Multiphysics software was used to simulate and calculate the deformation and crushing process of electrostatic droplets and the influence of different voltage,surface tension and droplet diameter on the droplet deformation rate.The results showed that:(1)the optimum charge range of the electrode ring was within 20 mm of the axial distance along the electrode ring.(2)The higher the voltage U,the smaller the surface tensionσ;the larger the droplet diameter d and the larger the droplet deformation rate.(3)The experimental results showed that the droplet size was inversely proportional to the gas pressure P0,electrostatic voltage U and spray height h.When the gas pressure and electrostatic voltage were 0.4 MPa and 18 kV,0.4 MPa and 18 kV,respectively,the droplet sizes were 7.8μm and 43.9μm respectively,the droplet size difference between the two conditions was 82.2%.

GaAs surface wet cleaning by a novel treatment in revolving ultrasonic atomization solution

A novel process for the wet cleaning of GaAs surface is presented. It is designed for technological simplicity and minimum damage generated within the GaAs surface. It combines GaAs cleaning with three conditions consisting of （1） removal of thermodynamically unstable species and （2） surface oxide layers must be completely removed after thermal cleaning, and （3） a smooth surface must be provided. Revolving ultrasonic atomization technology is adopted in the cleaning process. At first impurity removal is achieved by organic solvents; second NH4OH ： H202 ： H2O = 1 ： 1 ： 10 solution and HCI ： H2O2 ： H2O = 1 ： 1 ： 20 solution in succession to etch a very thin GaAs layer, the goal of the step is removing metallic contaminants and forming a very thin oxidation layer on the GaAs wafer surface; NHaOH ： H2O = 1 ： 5 solution is used as the removed oxide layers in the end. The effectiveness of the process is demonstrated by the operation of the GaAs wafer. Characterization of the oxide composition was carried out by X-ray photoelectron spectroscopy. Metal-contamination and surface morphology was observed by a total reflection X-ray fluorescence spectroscopy and atomic force microscope. The research results show that the cleaned surface is without contamination or metal contamination. Also, the GaAs substrates surface is very smooth for epitaxial growth using the rotary ultrasonic atomization technology.

Laser-induced topology optimized amorphous nanostructure and corrosion electrochemistry of supersonically deposited Ni_(30)Cr_(25)Al_(15)Co_(15)Mo_(5)Ti_(5)Y_(5) HEA coating based on AIMD

A novel Ni_(30)Cr_(25)Al_(15)Co_(15)Mo_(5)Ti_(5)Y_(5) high-entropy alloy(HEA)coating was irradiated to optimize its internal structure via laser after supersonic particle deposition(SPD).Owing to the high energy density of the laser and large temperature gradient,the crystallization process of the molecules and atoms in the coating was restrained and supercooling occurred.Experimental results showed that a considerable number of nano-crystal grains precipitated and amorphous structures were formed because of the random orientation of the crystals.The baseline of differential scanning calorimetry scans obtained for the coating started to shift at the Tg of 939.37℃ and a step was observed.Multiple dispersion peaks and lattice fringes indicated that the nucleation of the irradiated laser-induced topology optimized(LTO)coating was incomplete.The laser-induced topology optimizing treatment led to quasi-isotropy in the SPD coating.Furthermore,the LTO coating exhibited a residual stress of 18.4 MPa,stress-strain response,and fatigue limit of 265 MPa.Hence,the LTO coating exhibited higher performance than the unirradiated SPD coating.The Nyquist and Bode electrochemical impedance spectra of the LTO coating,including two relaxation processes,indicated that the corrosion process steadily recovered to the equilibrium state.This implies that the uniform oxidation passivation layer on the surface of the LTO coating insulated the material from the corrosive medium,protecting the substrate from further corrosion,thus enhancing the structural security of the material for use in super-intense laser facility applications.