Accurate prediction on geological hazards can prevent disaster events in advance and greatly reduce property losses and life casualties.Glacial debris flows are the most serious hazards in southeastern Tibet in China ...Accurate prediction on geological hazards can prevent disaster events in advance and greatly reduce property losses and life casualties.Glacial debris flows are the most serious hazards in southeastern Tibet in China due to their complexity in formation mechanism and the difficulty in prediction.Data collected from 102 glacier debris flow events from 31 gullies since 1970 and regional meteorological data from 1970 to 2019 in ParlungZangbo River Basin in southeastern Tibet were used for Artificial Neural Network(ANN)-based prediction of glacial debris flows.The formation mechanism of glacial debris flows in the ParlungZangbo Basin was systematically analyzed,and the calculations involving the meteorological data and disaster events were conducted by using the statistical methods and two layers fully connected neural networks.The occurrence probabilities and scales of glacial debris flows(small,medium,and large)were predicted,and promising results have been achieved.Through the proposed model calculations,a prediction accuracy of 78.33%was achieved for the scale of glacial debris flows in the study area.The prediction accuracy for both large-and medium-scale debris flows are higher than that for small-scale debris flows.The debris flow scale and the probability of occurrence increase with increasing rainfall and temperature.In addition,the K-fold cross-validation method was used to verify the reliability of the model.The average accuracy of the model calculated under this method is about 93.3%,which validates the proposed model.Practices have proved that the combination of ANN and disaster events can provide sound prediction on geological hazards under complex conditions.展开更多
Based on a modified-Darcy-Maxwell model, two-dimensional, incompressible and heat transfer flow of two bounded layers, through electrified Maxwell fluids in porous media is performed. The driving force for the instabi...Based on a modified-Darcy-Maxwell model, two-dimensional, incompressible and heat transfer flow of two bounded layers, through electrified Maxwell fluids in porous media is performed. The driving force for the instability under an electric field, is an electrostatic force exerted on the free charges accumulated at the dividing interface. Normal mode analysis is considered to study the linear stability of the disturbances layers. The solutions of the linearized equations of motion with the boundary conditions lead to an implicit dispersion relation between the growth rate and wave number. These equations are parameterized by Weber number, Reynolds number, Marangoni number, dimensionless conductivities, and dimensionless electric potentials. The case of long waves interfaciaJ stability has been studied. The stability criteria are performed theoreticaily in which stability diagrams are obtained. In the limiting cases, some previously published results can be considered as particular cases of our results. It is found that the Reynolds number plays a destabilizing role in the stability criteria, while the damping influence is observed for the increasing of Marangoni number and Maxwell relaxation time.展开更多
Generation of the transient flexural- and capillary-gravity waves by impulsive disturbances in a two-layer fluid is investi- gated analytically. The upper fluid is covered by a thin elastic plate or by an inertial sur...Generation of the transient flexural- and capillary-gravity waves by impulsive disturbances in a two-layer fluid is investi- gated analytically. The upper fluid is covered by a thin elastic plate or by an inertial surface with the capillary effect. The density of each of the two immiscible layers is constant. The fluids are assumed to be inviscid and incompressible and the motion be irrotational. A point force on the surface and simple mass sources in the upper and lower fluid layers are considered. A linear system is establi- shed within the framework of potential theory. The integral solutions for the surface and interracial waves are obtained by means of the Laplace-Fourier transform. A new representation for the dispersion relation of flexural- and capillary-gravity waves in a two- layer fluid is derived. The asymptotic representations of the wave motions are derived for large time with a fixed distance-to-time ratio with the Stokes and Scorer methods of stationary phase. It is shown that there are two different modes, namely the surface and interracial wave modes. The wave systems observed depend on the relation between the observer＇s moving speed and the intrinsic minimal and maximal group velocities.展开更多
Antimicrobial resistance(AMR)is a global public health issue.Rapid and accurate antimicrobial susceptibility tests(AST)on bacteria isolates would facilitate appropriate choice of antibiotics,in which patients receive ...Antimicrobial resistance(AMR)is a global public health issue.Rapid and accurate antimicrobial susceptibility tests(AST)on bacteria isolates would facilitate appropriate choice of antibiotics,in which patients receive appropriate treatment and the emergence of multidrug-resistant organisms could be prevented simultaneously.In this study,we have developed a microfluidic device named Self Dilution for Faster Antimicrobial Susceptibility Testing(SDFAST).This SlipChip-based device consists of two layers of microchips,allowing injection of bacterial suspension and antibiotics by simply connecting the two chips.By slipping one microchip against another in a single press of the microchip,the antibiotics can be diluted within seconds and be well mixed with bacterial samples.By combining SDFAST with a water-soluble tetrazolium salt-8(WST-8)assay,a range of clinically prevalent bacteria,including Acinetobacter baumannii,Escherichia coli,Klebsiella pneumoniae,and Staphylococci species,were tested under various antibiotics.Color analysis after 4–6 h of incubation showed an abrupt change in the WST-8 color of certain wells with diluted antibiotics,proving that instrument-free and immediate identification of minimum inhibitory concentration(MIC)could be achieved.The testing on 51 clinical isolates had an agreement of 92%,proving the accuracy of our method.These results validated its advantages of simple operation,rapid testing,and low sample consumption comparing to conventional methods,which require 16–24 h of incubation.Therefore,our method shows great potential to be further developed into a medical instrument for automated medical testing and point-of-care diagnosis.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.41671112)the Sichuan Province Science and Technology Plan Project Key research and development projects(Grant No.18ZDYF0329)the National Natural Science Foundation of China(Grant No.41861134008)。
文摘Accurate prediction on geological hazards can prevent disaster events in advance and greatly reduce property losses and life casualties.Glacial debris flows are the most serious hazards in southeastern Tibet in China due to their complexity in formation mechanism and the difficulty in prediction.Data collected from 102 glacier debris flow events from 31 gullies since 1970 and regional meteorological data from 1970 to 2019 in ParlungZangbo River Basin in southeastern Tibet were used for Artificial Neural Network(ANN)-based prediction of glacial debris flows.The formation mechanism of glacial debris flows in the ParlungZangbo Basin was systematically analyzed,and the calculations involving the meteorological data and disaster events were conducted by using the statistical methods and two layers fully connected neural networks.The occurrence probabilities and scales of glacial debris flows(small,medium,and large)were predicted,and promising results have been achieved.Through the proposed model calculations,a prediction accuracy of 78.33%was achieved for the scale of glacial debris flows in the study area.The prediction accuracy for both large-and medium-scale debris flows are higher than that for small-scale debris flows.The debris flow scale and the probability of occurrence increase with increasing rainfall and temperature.In addition,the K-fold cross-validation method was used to verify the reliability of the model.The average accuracy of the model calculated under this method is about 93.3%,which validates the proposed model.Practices have proved that the combination of ANN and disaster events can provide sound prediction on geological hazards under complex conditions.
文摘Based on a modified-Darcy-Maxwell model, two-dimensional, incompressible and heat transfer flow of two bounded layers, through electrified Maxwell fluids in porous media is performed. The driving force for the instability under an electric field, is an electrostatic force exerted on the free charges accumulated at the dividing interface. Normal mode analysis is considered to study the linear stability of the disturbances layers. The solutions of the linearized equations of motion with the boundary conditions lead to an implicit dispersion relation between the growth rate and wave number. These equations are parameterized by Weber number, Reynolds number, Marangoni number, dimensionless conductivities, and dimensionless electric potentials. The case of long waves interfaciaJ stability has been studied. The stability criteria are performed theoreticaily in which stability diagrams are obtained. In the limiting cases, some previously published results can be considered as particular cases of our results. It is found that the Reynolds number plays a destabilizing role in the stability criteria, while the damping influence is observed for the increasing of Marangoni number and Maxwell relaxation time.
基金supported by the National Natural Science Foundation of China (Grant No. 11072140)the State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University(Grant No. 0803)the Shanghai Program for Innovative Research Team in Universities
文摘Generation of the transient flexural- and capillary-gravity waves by impulsive disturbances in a two-layer fluid is investi- gated analytically. The upper fluid is covered by a thin elastic plate or by an inertial surface with the capillary effect. The density of each of the two immiscible layers is constant. The fluids are assumed to be inviscid and incompressible and the motion be irrotational. A point force on the surface and simple mass sources in the upper and lower fluid layers are considered. A linear system is establi- shed within the framework of potential theory. The integral solutions for the surface and interracial waves are obtained by means of the Laplace-Fourier transform. A new representation for the dispersion relation of flexural- and capillary-gravity waves in a two- layer fluid is derived. The asymptotic representations of the wave motions are derived for large time with a fixed distance-to-time ratio with the Stokes and Scorer methods of stationary phase. It is shown that there are two different modes, namely the surface and interracial wave modes. The wave systems observed depend on the relation between the observer＇s moving speed and the intrinsic minimal and maximal group velocities.
基金supported by the Health@InnoHK program of the Innovation and Technology Commission of the Hong Kong SAR Governmentsupported by The University of Hong Kong(202009185087)+1 种基金Collaborative Research Fund(C7165-20GF)General Research Fund(17307919 and 17303123)of the Research Grants Council of Hong Kong,Hong Kong.
文摘Antimicrobial resistance(AMR)is a global public health issue.Rapid and accurate antimicrobial susceptibility tests(AST)on bacteria isolates would facilitate appropriate choice of antibiotics,in which patients receive appropriate treatment and the emergence of multidrug-resistant organisms could be prevented simultaneously.In this study,we have developed a microfluidic device named Self Dilution for Faster Antimicrobial Susceptibility Testing(SDFAST).This SlipChip-based device consists of two layers of microchips,allowing injection of bacterial suspension and antibiotics by simply connecting the two chips.By slipping one microchip against another in a single press of the microchip,the antibiotics can be diluted within seconds and be well mixed with bacterial samples.By combining SDFAST with a water-soluble tetrazolium salt-8(WST-8)assay,a range of clinically prevalent bacteria,including Acinetobacter baumannii,Escherichia coli,Klebsiella pneumoniae,and Staphylococci species,were tested under various antibiotics.Color analysis after 4–6 h of incubation showed an abrupt change in the WST-8 color of certain wells with diluted antibiotics,proving that instrument-free and immediate identification of minimum inhibitory concentration(MIC)could be achieved.The testing on 51 clinical isolates had an agreement of 92%,proving the accuracy of our method.These results validated its advantages of simple operation,rapid testing,and low sample consumption comparing to conventional methods,which require 16–24 h of incubation.Therefore,our method shows great potential to be further developed into a medical instrument for automated medical testing and point-of-care diagnosis.
