The effects of operating parameters on desulfurization efficiency of a dual-alkali FGD process in a rotating-stream-tray(RST)scrubber are investigated.A dimensionless factor,ε,is proposed in this study to predict des...The effects of operating parameters on desulfurization efficiency of a dual-alkali FGD process in a rotating-stream-tray(RST)scrubber are investigated.A dimensionless factor,ε,is proposed in this study to predict desulfurization efficiency of this dual-alkali FGD system.ε represents the desulfurization ability of a dual alkali FGD system,determined by five main operating parameters such as sodium ion concentration,ratio of absorbent flow rate to flue gas flow rate,pH value of absorbent solution,ratio of sulfate ion to total sulfur ion in absorbent solution,and sulfur dioxide concentration of inlet flue gas.The empirical expression for predicting desulfurization efficiency at different temperatures is obtained through the experimental study and theoretical calculation.It provides useful guide for engineering design.展开更多
An internal failure mode for a soil-nailed system consists of failure at nail heads,slope facing,nail strength,along groutesoil interface and pullout failure.A better understanding of pullout of soil nail thus becomes...An internal failure mode for a soil-nailed system consists of failure at nail heads,slope facing,nail strength,along groutesoil interface and pullout failure.A better understanding of pullout of soil nail thus becomes important to assess the stability of a soil-nailed system.In the present study,an investigation into the pullout behaviour of soil nail with circular discs along the shaft has been carried out by a threedimensional finite element analysis using Abaqus/Explicit routine.A total of 67 simulations have been performed to accurately predict the pullout behaviour of soil nail.The soil nail under study has circular discs along its shaft varying in numbers from 1 to 4.The pullout of this soil nail in a pullout test box has been simulated with a constant overburden pressure of 20 kPa acting on the nail.The pullout load edisplacement characteristics,stresses around soil nail and failure mechanism during pullout are studied.Variations of dimensionless factors such as normalised pullout load factor and bearing capacity factor have been obtained with different combinations of parameters in terms of relative disc spacing ratio,anchorage length ratio,embedment ratio,diameter ratio and displacement ratio.From the results of analyses,it is found that nail with more circular discs requires higher pullout load.There are critical relative disc spacing ratio and diameter ratio which significantly affect the pullout behaviour of nail.展开更多
Altitude characteristic is of great importance for studying when an air-breathing pulsed laser thruster works in the dense atmosphere condition of 0-30 km altitude.The experimental findings all over the world show tha...Altitude characteristic is of great importance for studying when an air-breathing pulsed laser thruster works in the dense atmosphere condition of 0-30 km altitude.The experimental findings all over the world show that the similar relationship between impulse coupling coefficient and altitude.According to strong explosion theory and an ideal gas model,a dimensionless factor indicating energy law of similitude is introduced,and formula of impulse coupling coefficient is deducted.Then theoretical study of altitude characteristic is carried out and mechanism of altitude characteristic is further explained.The results indicate that there is a maximum value of impulse coupling coefficient if the dimensionless factor equals to 0.41 in theory,and whether the phenomena of maximum appear or not depends on the range of the dimensionless factor related to altitude.As to a conical nozzle with the fixed length of 120 mm,the relationship between the sonic velocity and the dimensionless factor causes the maximum phenomenon at the altitude of about 12.5 km,and maximum theoretical impulse coupling coefficient is also found in the experimental investigations.The mechanism of altitude characteristic for air-breathing pulsed laser thruster is discovered in this article,which will provide reference for further research on altitude characteristic.展开更多
基金Supported by the National Hi-tech Researchand Development Program(863program)of China(No.2001AA642030-1)Key Research Project of Zhejiang Province(No.2004C23028)New Century Excellent Scholar Program of Ministry of Education of the People's Republic of China(No.NCET-04-0549)
文摘The effects of operating parameters on desulfurization efficiency of a dual-alkali FGD process in a rotating-stream-tray(RST)scrubber are investigated.A dimensionless factor,ε,is proposed in this study to predict desulfurization efficiency of this dual-alkali FGD system.ε represents the desulfurization ability of a dual alkali FGD system,determined by five main operating parameters such as sodium ion concentration,ratio of absorbent flow rate to flue gas flow rate,pH value of absorbent solution,ratio of sulfate ion to total sulfur ion in absorbent solution,and sulfur dioxide concentration of inlet flue gas.The empirical expression for predicting desulfurization efficiency at different temperatures is obtained through the experimental study and theoretical calculation.It provides useful guide for engineering design.
文摘An internal failure mode for a soil-nailed system consists of failure at nail heads,slope facing,nail strength,along groutesoil interface and pullout failure.A better understanding of pullout of soil nail thus becomes important to assess the stability of a soil-nailed system.In the present study,an investigation into the pullout behaviour of soil nail with circular discs along the shaft has been carried out by a threedimensional finite element analysis using Abaqus/Explicit routine.A total of 67 simulations have been performed to accurately predict the pullout behaviour of soil nail.The soil nail under study has circular discs along its shaft varying in numbers from 1 to 4.The pullout of this soil nail in a pullout test box has been simulated with a constant overburden pressure of 20 kPa acting on the nail.The pullout load edisplacement characteristics,stresses around soil nail and failure mechanism during pullout are studied.Variations of dimensionless factors such as normalised pullout load factor and bearing capacity factor have been obtained with different combinations of parameters in terms of relative disc spacing ratio,anchorage length ratio,embedment ratio,diameter ratio and displacement ratio.From the results of analyses,it is found that nail with more circular discs requires higher pullout load.There are critical relative disc spacing ratio and diameter ratio which significantly affect the pullout behaviour of nail.
基金National Natural Science Foundation of China(10672184)
文摘Altitude characteristic is of great importance for studying when an air-breathing pulsed laser thruster works in the dense atmosphere condition of 0-30 km altitude.The experimental findings all over the world show that the similar relationship between impulse coupling coefficient and altitude.According to strong explosion theory and an ideal gas model,a dimensionless factor indicating energy law of similitude is introduced,and formula of impulse coupling coefficient is deducted.Then theoretical study of altitude characteristic is carried out and mechanism of altitude characteristic is further explained.The results indicate that there is a maximum value of impulse coupling coefficient if the dimensionless factor equals to 0.41 in theory,and whether the phenomena of maximum appear or not depends on the range of the dimensionless factor related to altitude.As to a conical nozzle with the fixed length of 120 mm,the relationship between the sonic velocity and the dimensionless factor causes the maximum phenomenon at the altitude of about 12.5 km,and maximum theoretical impulse coupling coefficient is also found in the experimental investigations.The mechanism of altitude characteristic for air-breathing pulsed laser thruster is discovered in this article,which will provide reference for further research on altitude characteristic.
