Improvement of uniformity in cultivation environment and crop growth rate by hybrid control of air flow devices

A complete control type plant factory has high efficiency in terms of cultivation area by constructing vertical multiple layered cultivation beds.However,it has a problem of irregular crop growth due to temperature deviation at upper and lower beds and increases in energy consumption by a prolonged cultivation period.In this work,air flow rate inside a facility was improved by a hybrid control of air flow devices like air conditioning and air circulation fan with an established wireless sensor network to minimize temperature deviations between upper and lower beds and to promote crop growth.The performance of proposed system was verified with an experimental environment or Case A wherein air conditioning device was operated without a control algorithm and Case B wherein air conditioning and circulation fans were alternatively operated based on the hybrid control algorithm.After planting leafy vegetables under each experimental condition,crops were cultivated for 21 days.As a result,Case B wherein AC(air conditioning) and ACF(air-circulation fan) were alternatively operated based on the hybrid control algorithm showed that fresh mass,number of leaves,and leaf length for the crops grown were increased by 40.6%,41.1%,and 11.1%,respectively,compared to Case A.

Orthogonal analysis of water model study on the optimization of flow control devices in a six-strand tundish

Improper flow control devices in a multi-strand tundish can cause some problems, for example, liquid steel cannot reach every nozzle at the same time and the liquid steel in nozzles far away from the entry zone has a lower temperature. The water model experiment of a six-strand tundish of Tianjin Iron ＆ Steel Co. Ltd. was performed, a new ＂U＂ type baffle was obtained, and its parameters were defined by perpendicular analysis. The ＂U＂ baffle can not only improve those imperfections, but also prolong the residence time of nonmetallic inclusions, which is good for their flotation and separation.

Improvement of tundish shape and optimization of flow control devices for sequence casting heavy steel ingots

The metallurgical effect of a round tundish used to cast heavy steel ingots in machine works at present was evaluated through water modeling experiments. The flow control devices of the improved oval tundish, which was used instead of the round tundish, had been optimized. The results show that the residence time of the round tundish is short, its inclusion removal efficiency is too low, and it has more dead zones and an unreasonable flow field. Compared with the round tundish, the improved oval tundish with the optimized weir and dam has a better effect： its minimum residence time is prolonged by 38.1 s, the average residence time is prolonged by 233.4 s, its dead volume fraction decreases from 26% to 15%, and the ratio of plug volume fraction to dead volume fraction increases from 0.54 to 1.27. The inclusion removal efficiency also increases by 17.5%.

Optimization of flow control devices in a tenstrand billet caster tundish

The physical model of a ten-strand billet caster tundish was established to study the effects of various flow control devices on the melt flow. Before and after the optimization of the melt flow, the inclusion removal in the tundish was evaluated by plant trials. The physical modeling results show that when combined with a baffle, the turbulence inhibitor, instead of the impact pad, can significantly improve the melt flow. A turbulence inhibitor with a longer length of inner cavity and without an extending lip at the top of the sidewall seems to be efficient in the improvement of the melt flow. Various types and designs of baffles all influence the flow characteristics significantly. The "V" type baffles are better than the straight baffles for flow control. The "V" type baffle with four inclined holes at the sidewall away from the stopper rods is better in melt flow control than the one with one inclined hole at each sidewall. The combination of a well-designed turbulence inhibitor and an appropriate baffle shows high efficiency on improving the melt flow and an optimal proposal was presented. Plant trials indicate that, compared with the original tundish configuration in prototype, the inclusions reduce by 42% and the inclusion distribution of individual strands is more similar with the optimal one. The optimal tundish configuration effectively improves the melt flow in the ten-strand billet caster tundish.

Effects of two different glycoprotein platelet Ⅱb/Ⅲa inhibitors and the clinical endpoints in patients with intracranial Pipeline flow diverter implant

Objective:To compare the antiplatelet effect and major adverse cerebrovascular events of Pipeline for intracranial aneurysms using glycoproteinⅡb/Ⅲa antagonists(GPI)eptifibatide and tirofiban.Methods:Retrospective analysis of relevant data of patients using GPIs combined with oral antiplatelet therapy in Nanfang Hospital of Southern Medical University from December 2017 to December 2019.The study was approved by the ethics Committee of Nanfang Hospital of Southern Medical University.According to the random use of GPIs drugs,they were assigned to the eptifibatide group and tirofiban group.Basic data,platelet inhibition rates at baseline,24 h and 72 h after administration,short-term major adverse cerebrovascular events,and bleeding complications were compared between the two groups.Results:A total of 47 patients were included in this study,including 24 patients in eptifibatide group and 23 patients in tirofiban group.There was no significant difference in average age(53.75 vs.53.91 years)and body mass index(BMI)(24.39 vs.22.73 kg/m2)between eptifibatide group and tirofiban group.There was no significant difference in coagulation factor function(R),fibrinogen function(K),fibrinolysis function(EPL),comprehensive coagulation index(Cl),arachidonic acid pathway inhibition rate(AA%)and adenosine diphosphate inhibition rate(ADP%).However,the baseline level of residual platelet function MA(ADP)in eptifibatide group was significantly higher than that in tirofiban group(50.79 vs.35.29 mm,P=0.0026).There was a statistical difference in the platelet aggregation function MA(65.38 vs.62.54 mm,p=0.0442),the rate of spontaneous hemorrhagic stroke(4.3%vs.0%)and the rate of asymptomatic minor bleeding(26.08%vs.4.1%)in the two groups(P<0.05).Conclusion:Both eptifibatide and tirofiban can effectively inhibit platelets,but the effect of etifeptide is better than that of tirofiban in preventing intracranial microhemorrhage and asymptomatic cerebral infarction.

A portable device for studying the effects of fluid flow on degradation properties of biomaterials inside cell incubators

A portable device was designed and constructed for studying the properties of biomaterials in physiologically relevant fluids under controllable flow conditions that closely simulate fluid flow inside the body.The device can fit entirely inside a cell incubator;and,thus,it can be used directly under standard cell culture conditions.An impedance-driven pump was built in the sterile flow loop to control the flow rates of fluids,which made the device small and portable for easy deployment in the incubator.To demonstrate the device functions,magnesium(Mg)as a representative biodegradable material was tested in the flow device for immersion degradation under flow versus static conditions,while the flow module was placed inside a standard cell incubator.The flow rate was controlled at 0.1760.06 ml/s for this study;and,the flow rate is adjustable through the controller module outside of incubators for simulating the flow rates in the ranges of blood flow in human artery(0.050.43 ml/s)and vein(0.020.08 ml/s).Degradation of Mg under flow versus static conditions was characterized by measuring the changes of sample mass and thickness,and Mg2t ion concentrations in the immersion media.Surface chemistry and morphology of Mg after immersion under flow versus static conditions were compared.The portable impedance-driven flow device is easy to fit inside an incubator and much smaller than a peristaltic pump,providing a valuable solution for studying biomaterials and implants(e.g.vascular or ureteral stents)in body fluids under flow versus static conditions with or without cells.

Chopper-modulated gas chromatography electroantennography enabled using high-temperature MEMS flow control device

We report the design,fabrication and characterization of a microelectromechanical systems(MEMS)flow control device for gas chromatography(GC)with the capability of sustaining high-temperature environments.We further demonstrate the use of this new device in a novel MEMS chopper-modulated gas chromatography-electroantennography(MEMS-GC-EAG)system to identify specific volatile organic compounds(VOCs)at extremely low concentrations.The device integrates four pneumatically actuated microvalves constructed via thermocompression bonding of the polyimide membrane between two glass substrates with microstructures.The overall size of the device is 32 mm×32 mm,and it is packaged in a 50 mm×50 mm aluminum housing that provides access to the fluidic connections and allows thermal control.The characterization reveals that each microvalve in the flow control chip provides an ON to OFF ratio as high as 1000:1.The device can operate reliably for more than 1 million switching cycles at a working temperature of 300℃.Using the MEMS-GC-EAG system,we demonstrate the successful detection of cis-11-hexadecenal with a concentration as low as 1 pg at a demodulation frequency of 2 Hz by using an antenna harvested from the male Helicoverpa Virescens moth.In addition,1μg of a green leafy volatile(GLV)is barely detected using the conventional GC-EAG,while MEMS-GC-EAG can readily detect the same amount of GLV,with an improvement in the signal-to-noise ratio(SNR)of~22 times.We expect that the flow control device presented in this report will allow researchers to explore new applications and make new discoveries in entomology and other fields that require high-temperature flow control at the microscale.

Physical and numerical investigation on fluid flow and inclusion removal behavior in a single-strand tundish

Aiming at the problem that the existence of inclusions in the tundish continuous casting process can easily lead to quality defects of the slab,the stainless steel continuous casting tundish was taken as the research object.The effects of flow control device,inclusion density and inclusion size on the mixing characteristics of molten steel and inclusion behavior in tundish were studied.The results showed that compared with the tundish without flow control device,the average residence time of molten steel was prolonged by about 49 s,the dead zone volume fraction was reduced by 8.93%,and the piston fluid integral rate was increased by 12.68%.In the turbulence inhibitor(TI)tundish with weir-dam combination,the removal rate of inclusions with a density of 2700 kg m^(-3) and a particle size of 5 lm is 63.32%,while the removal rate of large inclusions with a density of 150μm could reach 89.04%.When the inclusion particle size was 10-50μm and the density was 2700-4500 kg m^(-3),the effect of inclusion density on inclusion removal rate was small.At the same time,when weir-dam combination TI tundish was set,the inclusions were mainly limited to the slag-metal interface of the first and second chambers of the tundish.The removal rate of inclusions in the first chamber was generally improved,with 10μm inclusions accounting for 47.67% and 150μm inclusions accounting for 60.69%.Furthermore,it has the best effect on the removal of small-size inclusions,especially those less than 70μm.

Design and performance analysis of tangential-axial flow threshing device for oat harvester

Aiming at the problems of stalks winding and poor threshing performance in the process of mechanical harvesting of oats,a type of threshing and crushing experimental device was designed.The device was composed of a belt conveyor,a tangential-flow threshing drum,an axial-flow threshing drum,a high-speed camera and a testing device.According to a regression orthogonal test method,using the rotation speed of the axial-flow drum,the horizontal center distance,and the vertical height difference of the two threshing drums as experimental factors;using the mass fraction of long stalks and the threshing rate as experimental indexes,a mathematical regression model of factors and indexes was established,and combined parameters were analyzed for the threshing quality and crushing ability.Experimental results showed that this device had the best crushing performance when the rotation speed of the axial-flow drum was 850 r/min,the horizontal center distance was 820 mm,and the vertical height difference was 10 mm,and this device had optimal threshing performance when the rotation speed of the axial-flow drum was 760 r/min,the horizontal center distance was 820 mm,and the vertical height difference was 20 mm.The parameters were optimized by Design-Expert 11 to obtain an optimization result that the rotation speed of the axial-flow drum was 800 r/min,the horizontal center distance was 820 mm,and the vertical height difference was 10 mm.A verification experiment was carried out by using a high-speed camera,and the two groups of parameters were selected for a comparative experiment.Images of material movement between the two threshing drums were captured by the high-speed camera.Experimental results showed that the optimized parameters were beneficial to improving the threshing performance and anti-winding performance of the oat threshing process.This study provides a technical basis for the research and development of oat combine harvesters.

Automated Determination of Cd^(2+) and Pb^(2+) in Natural Waters with Sequential Injection Analysis Device Using Differential Pulse Anodic Stripping Voltammetry

An electrochemical flow device has been developed for the determination of heavy metal ions(HMI)in water using multiwalled carbon nanotubes(MWCNTs)/Nafion(NA)/Hg electrode,by mean of diff erential pulse anodic stripping voltammetry coupled with sequential injection analysis.The accuracy of the determination was ensured by the great electrical conductivity of MWCNTs and the high adsorption capacity of Hg.NA was used for MWCNTs immobilization for the long-term application of the electrode.The mercury film was cleaned after determination and another one would form during deposition.A lower limit of detection and a wider determination range of Cd^(2+)and Pb^(2+)could be achieved using the automatically analytical device combining with the MWCNTs/NA/Hg-modified electrode.The real-time monitoring of Cd^(2+)and Pb^(2+)in fresh water using this device continued for 10 days.The results indicated that the method was potential for on-site and real-time determination of HMI in water samples.

Molten Steel Flow in a Slab Continuous-casting Tundish

Fields of fluid flow and temperature, and residence time distribution(RTD) curves were investigated by mathematical simulation in a one-strand tundish for continuous casting. It was known from the investigation that a big "spring uprush" formed on surface around the long shroud when molten steel flowed into a turbulence inhibitor(TI) with extending lips and rushed up reversely out of the TI, while four small "spring uprushes" existed on surface when a TI without extending lips because the liquid steel flowed mainly out of the 4 corners of the TI. The flow of liquid steel in the former tundish configuration was not reasonable and the height of an area where temperature was less than 1819 K was about half of liquid surface height on the right side of the stopper, which meant that big dead zone existed in the former tundish configuration. In the optimal one, the height of such area was only seventh of the liquid surface height. The RTD curves obtained from the mathematical simulation basically agreed with those from the physical modeling and the flow characteristics obtained from these two methods agreed with each other.