Ligand assisted reprecipitation(LARP)is a widely used method for cesium lead halide perovskite nanocrystals(NCs)synthesis.Nevertheless,the ultrafast kinetics of LARP,as well as the inefficient transport properties and...Ligand assisted reprecipitation(LARP)is a widely used method for cesium lead halide perovskite nanocrystals(NCs)synthesis.Nevertheless,the ultrafast kinetics of LARP,as well as the inefficient transport properties and discontinuity of batch reactors,challenge the particle size control and experimental repeatability.To address these issues,an ultrasonic cavitation-enabled microfluidic approach was developed to achieve the continuous synthesis of cesium lead halide perovskite via LARP.It was found that the mixing between the good solvent and antisolvent in the microchannel was greatly enhanced by intensive ultrasonic cavitation.The mixing time could be reduced to below 10 ms under the irradiation of 35 W ultrasound.By modulating the mixing degree,LARP was proved to be a mixing-sensitive process.The effects of ultrasonic power,ultrasonic treatment time,total flow rate,water additive,and reprecipitation temperature on the synthesis of CsPbBr_(3) NCs were systematically investigated.As compared to CsPbBr_(3) NCs synthesized in the batch reactor,the sample synthesized via the ultrasonic cavitation-enabled microfluidic approach possessed stronger photoluminescence intensity and better repeatability.Moreover,the ultrasonic cavitation-enabled microfluidic approach could also realize the continuous synthesis of cesium lead halide perovskite NCs with different halide compositions to cover a wide visible spectrum(426-661 nm).The ultrasonic cavitation-enabled microfluidic approach paved the way for the large-scale of high-quality cesium lead halide perovskite NCs.展开更多
Regulator station is an important part in the urban gas transmission and distribution system.Once gas explosion occurs,the real explosion process and consequences of methane gas explosion in the regulator station were...Regulator station is an important part in the urban gas transmission and distribution system.Once gas explosion occurs,the real explosion process and consequences of methane gas explosion in the regulator station were not revealed systematically.In this study,a full-scale experiment was carried out to simulate the regulator station explosion process,and some numerical simulations with a commercial CFD software called FLACS were conducted to analyze the effect of ignition and vent conditions on the blast overpressure and flame propagation.The experimental results demonstrated that the peak overpressure increased as the distance from the vent increased within a certain distance.And the maximum overpressure appeared 3 m away from the door,which was about 36.6 kPa.It was found that the pressure-time rising curves obtained from the simulation are basically the same as the ones from the experiment,however,the time of reaching the peak pressure was much shorter.The numerical simulation results show that the peak overpressures show an increase trend as the ignition height decreased and the vent relief pressure increased.It indicates that the damage and peak overpressure of gas explosion could be well predicted by FLACS in different styles of regulator station.In addition,the results help us to understand the internal mechanism and development process of gas explosion better.It also offers technical support for the safety protection of the urban regulator station.展开更多
When an electromagnetic signal transmits through a coaxial cable, it propagates at speed determined by the dielectrics of insulator between the cooper core wire and the metallic shield. However, we demonstrate here th...When an electromagnetic signal transmits through a coaxial cable, it propagates at speed determined by the dielectrics of insulator between the cooper core wire and the metallic shield. However, we demonstrate here that, once the shielding layer of the coaxial cable is cut into two parts leaving a small gap, while the copper core wire is still perfectly connected, a remarkable transmission delay immediately appears in the system. We have revealed by both computational simulation and experiments that, when the gap spacing between two parts of the shielding layer is small, this delay is mostly determined by the overall geometrical parameters of the conductive boundary which connects two parts of the cut shielding layer. A reduced analytic formula for the transmission delay related with geometrical parameters, which is based on an inductive model of the transmission system, matches well with the fitted formula of the simulated delay. This above structure is analog to the situation that an interconnect is between two inter-modules in a circuit. The results suggest that for high speed circuits and systems, parasitic inductance should be taken into full consideration, and compact conductive packaging is favorable for reducing transmission delay of inter-modules, therefore enhancing the performance of the system.展开更多
The genus Arthrobacter was established in 1947 by Conn & Dimmick. So far, more than 70 recognized?species of the genus Arthrobacter have been certified. Its special functions have been widely known by researchers,...The genus Arthrobacter was established in 1947 by Conn & Dimmick. So far, more than 70 recognized?species of the genus Arthrobacter have been certified. Its special functions have been widely known by researchers, such as, in agricultural, in medical, in industrial, and in environmental areas, etc. What deserves to be mentioned is that some species of genus Arthrobacter have showed the function of degrading pesticides, fixing nitrogen, producing beneficial enzyme, treating sewage, and so on. Recently, the applications of the genus Arthrobacter, especially the VBNC?(viable but non-culturable) bacteria of this genus in the field of contaminated environment repair attract people’s attention and some related research results have also been obtained. The functions that we have known are waiting for us to study about mechanism, deeply. And, we can look forward to discovering more potential functions and applications of this genus in ecological environment. In the meantime, these discoveries must bring more new changes and knowledge.展开更多
Manufacture variations can greatly increase the performance variability of compressor blades. Current robust design optimization methods have a critical role in reducing the adverse impact of the variations, but can b...Manufacture variations can greatly increase the performance variability of compressor blades. Current robust design optimization methods have a critical role in reducing the adverse impact of the variations, but can be affected by errors if the assumptions of the deviation models and distribution parameters are inaccurate. A new approach for robust design optimization without the employment of the deviation models is proposed. The deviation package method and the interval estimation method are exploited in this new approach. Simultaneously, a stratified strategy is used to reduce the computational cost and assure the optimization accuracy. The test case employed for this study is a typical transonic compressor blade profile, which resembles most of the manufacture features of modern compressor blades. A set of 96 newly manufactured blades was measured using a coordinate measurement machine to obtain the manufacture variations and produce a deviation package. The optimization results show that the scatter of the aerodynamic performance for the optimal robust design is 20% less than the baseline value. By comparing the optimization results obtained from the deviation package method with those obtained from widely-used methods employing the deviation model, the efficiency and accuracy of the deviation package method are demonstrated. Finally, the physical mechanisms that control the robustness of different designs were further investigated, and some statistical laws of robust design were extracted.展开更多
The study of microscopic structure of a liquid/liquid interface is of fundamental importance due to its close relation to the thermodynamics and kinetics of interfacial charge transfer reactions.In this article,the mi...The study of microscopic structure of a liquid/liquid interface is of fundamental importance due to its close relation to the thermodynamics and kinetics of interfacial charge transfer reactions.In this article,the microscopic structure of a non-polarizable water/nitrobenzene(W/NB)interface was evaluated by scanning ion conductance microscope(SICM).Using SICM with a nanometer-sized quartz pipette filled with an electrolyte solution as the probe,the thickness of this type of W/NB interface could be measured at sub-nanometer scale,based on the continuous change of ionic current from one phase to another one.The effects for thicknesses of the non-polarizable W/NB interfaces with different electrolyte concentrations,the Galvani potentials at the interface and the applied potentials on the probe were measured and systematically analyzed.Both experimental setups,that is an organic phase up and an aqueous down,and a reverse version,were employed to acquire the approach curves.These data were compared with those of an ideal polarizable interface under the similar experimental conditions,and several characteristics of non-polarizable interfaces were found.The thickness of a non-polarizable interface increases with the decrease of electrolyte concentration and the increase of applied potential,which is similar to the situation of a polarizable liquid/liquid interface.We also find that the Galvani potential across a non-polarizable interface can also influence the interfacial thickness,this phenomenon is difficult to observe when using polarizable interface.Most importantly,by the comparison of two kinds of liquid/liquid interfaces,we experimentally proved that much more excess ions are gathered in the space charge layer of non-polarizable interfaces than in that of polarizable interfaces.These results are consistent with the predictions of molecular dynamic simulations and X-ray reflectivity measurements.展开更多
Slurry pipeline transport is widely used in several industrial processes.Calculating the specific power consumption(SPC)and determining the best working conditions are important for the design and operation of transpo...Slurry pipeline transport is widely used in several industrial processes.Calculating the specific power consumption(SPC)and determining the best working conditions are important for the design and operation of transportation systems.Based on the Shanghai Jiao Tong University high-concentration multi-sized slurry pressure drop(SJTU-HMSPD)pipeline-resistance-calculation model,the SJTU-SPC model for calculating the power required to transport a unit volume of solid materials over a unit pipeline length is established for a slurry transport system.The said system demonstrates a uniformity coefficient in the 1.26–7.98 range,median particle size of 0.075–4 mm,particle volume concentration of 10–60%,and pipeline diameter of 0.203–0.8 m.The results obtained were successfully verified against existing experimental data.The influence of parameters,such as particle-gradation uniformity coefficient,median particle size,pipe diameter,and particle volume concentration,on the SPC were analysed.The results revealed that the greater is the uniformity coefficient,the smaller is the minimum specific energy consumption and the larger the optimal transport concentration for a constant,median particle size slurry.As observed,the optimal transport concentration for broad-graded sand equalled approximately 48%.These results supplement the conclusions of existing research,indicating that the optimal transport concentration is approximately 30%and provides theoretical support for high concentration transportation of broad graded slurry.展开更多
基金the financial supports from National Natural Science Foundation of China(22178336 and 21991103).
文摘Ligand assisted reprecipitation(LARP)is a widely used method for cesium lead halide perovskite nanocrystals(NCs)synthesis.Nevertheless,the ultrafast kinetics of LARP,as well as the inefficient transport properties and discontinuity of batch reactors,challenge the particle size control and experimental repeatability.To address these issues,an ultrasonic cavitation-enabled microfluidic approach was developed to achieve the continuous synthesis of cesium lead halide perovskite via LARP.It was found that the mixing between the good solvent and antisolvent in the microchannel was greatly enhanced by intensive ultrasonic cavitation.The mixing time could be reduced to below 10 ms under the irradiation of 35 W ultrasound.By modulating the mixing degree,LARP was proved to be a mixing-sensitive process.The effects of ultrasonic power,ultrasonic treatment time,total flow rate,water additive,and reprecipitation temperature on the synthesis of CsPbBr_(3) NCs were systematically investigated.As compared to CsPbBr_(3) NCs synthesized in the batch reactor,the sample synthesized via the ultrasonic cavitation-enabled microfluidic approach possessed stronger photoluminescence intensity and better repeatability.Moreover,the ultrasonic cavitation-enabled microfluidic approach could also realize the continuous synthesis of cesium lead halide perovskite NCs with different halide compositions to cover a wide visible spectrum(426-661 nm).The ultrasonic cavitation-enabled microfluidic approach paved the way for the large-scale of high-quality cesium lead halide perovskite NCs.
基金Supported by the National Key Research and Development Program of China(2016YFC0802502)。
文摘Regulator station is an important part in the urban gas transmission and distribution system.Once gas explosion occurs,the real explosion process and consequences of methane gas explosion in the regulator station were not revealed systematically.In this study,a full-scale experiment was carried out to simulate the regulator station explosion process,and some numerical simulations with a commercial CFD software called FLACS were conducted to analyze the effect of ignition and vent conditions on the blast overpressure and flame propagation.The experimental results demonstrated that the peak overpressure increased as the distance from the vent increased within a certain distance.And the maximum overpressure appeared 3 m away from the door,which was about 36.6 kPa.It was found that the pressure-time rising curves obtained from the simulation are basically the same as the ones from the experiment,however,the time of reaching the peak pressure was much shorter.The numerical simulation results show that the peak overpressures show an increase trend as the ignition height decreased and the vent relief pressure increased.It indicates that the damage and peak overpressure of gas explosion could be well predicted by FLACS in different styles of regulator station.In addition,the results help us to understand the internal mechanism and development process of gas explosion better.It also offers technical support for the safety protection of the urban regulator station.
文摘When an electromagnetic signal transmits through a coaxial cable, it propagates at speed determined by the dielectrics of insulator between the cooper core wire and the metallic shield. However, we demonstrate here that, once the shielding layer of the coaxial cable is cut into two parts leaving a small gap, while the copper core wire is still perfectly connected, a remarkable transmission delay immediately appears in the system. We have revealed by both computational simulation and experiments that, when the gap spacing between two parts of the shielding layer is small, this delay is mostly determined by the overall geometrical parameters of the conductive boundary which connects two parts of the cut shielding layer. A reduced analytic formula for the transmission delay related with geometrical parameters, which is based on an inductive model of the transmission system, matches well with the fitted formula of the simulated delay. This above structure is analog to the situation that an interconnect is between two inter-modules in a circuit. The results suggest that for high speed circuits and systems, parasitic inductance should be taken into full consideration, and compact conductive packaging is favorable for reducing transmission delay of inter-modules, therefore enhancing the performance of the system.
文摘The genus Arthrobacter was established in 1947 by Conn & Dimmick. So far, more than 70 recognized?species of the genus Arthrobacter have been certified. Its special functions have been widely known by researchers, such as, in agricultural, in medical, in industrial, and in environmental areas, etc. What deserves to be mentioned is that some species of genus Arthrobacter have showed the function of degrading pesticides, fixing nitrogen, producing beneficial enzyme, treating sewage, and so on. Recently, the applications of the genus Arthrobacter, especially the VBNC?(viable but non-culturable) bacteria of this genus in the field of contaminated environment repair attract people’s attention and some related research results have also been obtained. The functions that we have known are waiting for us to study about mechanism, deeply. And, we can look forward to discovering more potential functions and applications of this genus in ecological environment. In the meantime, these discoveries must bring more new changes and knowledge.
基金funded by the National Science and Technology Major Project, China (No. 2017-II-0001-0013)Science Center for Gas Turbine Project, China (Nos. P2022-A-II-002-001 and P2022-B-II-002-001)。
文摘Manufacture variations can greatly increase the performance variability of compressor blades. Current robust design optimization methods have a critical role in reducing the adverse impact of the variations, but can be affected by errors if the assumptions of the deviation models and distribution parameters are inaccurate. A new approach for robust design optimization without the employment of the deviation models is proposed. The deviation package method and the interval estimation method are exploited in this new approach. Simultaneously, a stratified strategy is used to reduce the computational cost and assure the optimization accuracy. The test case employed for this study is a typical transonic compressor blade profile, which resembles most of the manufacture features of modern compressor blades. A set of 96 newly manufactured blades was measured using a coordinate measurement machine to obtain the manufacture variations and produce a deviation package. The optimization results show that the scatter of the aerodynamic performance for the optimal robust design is 20% less than the baseline value. By comparing the optimization results obtained from the deviation package method with those obtained from widely-used methods employing the deviation model, the efficiency and accuracy of the deviation package method are demonstrated. Finally, the physical mechanisms that control the robustness of different designs were further investigated, and some statistical laws of robust design were extracted.
基金supported by the National Natural Science Foundation of China(21575006,21335001)the National Key Research and Development Program of China(2016YFA0201300).
文摘The study of microscopic structure of a liquid/liquid interface is of fundamental importance due to its close relation to the thermodynamics and kinetics of interfacial charge transfer reactions.In this article,the microscopic structure of a non-polarizable water/nitrobenzene(W/NB)interface was evaluated by scanning ion conductance microscope(SICM).Using SICM with a nanometer-sized quartz pipette filled with an electrolyte solution as the probe,the thickness of this type of W/NB interface could be measured at sub-nanometer scale,based on the continuous change of ionic current from one phase to another one.The effects for thicknesses of the non-polarizable W/NB interfaces with different electrolyte concentrations,the Galvani potentials at the interface and the applied potentials on the probe were measured and systematically analyzed.Both experimental setups,that is an organic phase up and an aqueous down,and a reverse version,were employed to acquire the approach curves.These data were compared with those of an ideal polarizable interface under the similar experimental conditions,and several characteristics of non-polarizable interfaces were found.The thickness of a non-polarizable interface increases with the decrease of electrolyte concentration and the increase of applied potential,which is similar to the situation of a polarizable liquid/liquid interface.We also find that the Galvani potential across a non-polarizable interface can also influence the interfacial thickness,this phenomenon is difficult to observe when using polarizable interface.Most importantly,by the comparison of two kinds of liquid/liquid interfaces,we experimentally proved that much more excess ions are gathered in the space charge layer of non-polarizable interfaces than in that of polarizable interfaces.These results are consistent with the predictions of molecular dynamic simulations and X-ray reflectivity measurements.
基金This research was supported by the National Natural Science Foundation of China(Grant No.51779143)the Cultivation of Scientific Research Ability of Young Talents of Shanghai jiao Tong University(Grant No.19×100040072).
文摘Slurry pipeline transport is widely used in several industrial processes.Calculating the specific power consumption(SPC)and determining the best working conditions are important for the design and operation of transportation systems.Based on the Shanghai Jiao Tong University high-concentration multi-sized slurry pressure drop(SJTU-HMSPD)pipeline-resistance-calculation model,the SJTU-SPC model for calculating the power required to transport a unit volume of solid materials over a unit pipeline length is established for a slurry transport system.The said system demonstrates a uniformity coefficient in the 1.26–7.98 range,median particle size of 0.075–4 mm,particle volume concentration of 10–60%,and pipeline diameter of 0.203–0.8 m.The results obtained were successfully verified against existing experimental data.The influence of parameters,such as particle-gradation uniformity coefficient,median particle size,pipe diameter,and particle volume concentration,on the SPC were analysed.The results revealed that the greater is the uniformity coefficient,the smaller is the minimum specific energy consumption and the larger the optimal transport concentration for a constant,median particle size slurry.As observed,the optimal transport concentration for broad-graded sand equalled approximately 48%.These results supplement the conclusions of existing research,indicating that the optimal transport concentration is approximately 30%and provides theoretical support for high concentration transportation of broad graded slurry.