Retaining walls have been used in many construction projects such as for road and inclined surfaces protection. The damage caused by an earthquake depends on the fundamental frequency, amplitude and the duration of th...Retaining walls have been used in many construction projects such as for road and inclined surfaces protection. The damage caused by an earthquake depends on the fundamental frequency, amplitude and the duration of the seismic motion. These parameters strongly depend on the seismic properties of the layers that are near the surface. In the study of retaining walls, in addition to the infl uence of soil, the infl uence of topography is also important. In the present study, site response analysis is performed by using fi nite element software PLAXIS to obtain the eff ect of various factors such as embedded length of the sheet pile, underground water table, length and angle of the nail, shear wave velocity of soil on site eff ect and dynamic response. Moreover, for better understanding of the eff ect of the above parameters, the stability analysis was performed by using shear reduction method. The results show that an increase in the embedded length of the sheet pile and the length of nailing causes an increase in the amplifi cation factor. Moreover, for shear-wave velocity in the range of 200- 600 m/s, the amplifi cation factor increases with increase of the shear-wave velocity due to the decrease of nonlinear behavior.展开更多
Linde Type-A (LTA) zeolite was prepared from sodium aluminate and sodium metasilicate by hydrothermal process precursors. Sodium metasilicate prepared from molten NaOH and SiO2. The zeolite was characterized by FTIR, ...Linde Type-A (LTA) zeolite was prepared from sodium aluminate and sodium metasilicate by hydrothermal process precursors. Sodium metasilicate prepared from molten NaOH and SiO2. The zeolite was characterized by FTIR, XRD, XRF and SEM. The adsorption of Fe(III) from aqueous solution by zeolite A was studied. Different parameters like contact time, pH and concentration of iron were investigated. The results show that at contact time of 60 min and pH of 6 maximum adsorption of iron onto zeolite was observed. The kinetic data was analyzed using pseudo-first-order and pseudo-second-order kinetic models. The adsorption kinetics of Fe(III) were fitted well with the pseudo-second-order kinetic model.展开更多
Multicell converters are an interesting alternative for medium voltage and high power applications,because of the increased number of output voltage levels and apparent frequency.The two most significant types of mult...Multicell converters are an interesting alternative for medium voltage and high power applications,because of the increased number of output voltage levels and apparent frequency.The two most significant types of multicell converter are the flying capacitor multicell (FCM) converter and its derivative,stacked multicell (SM) converter.Balancing flying capacitor voltages is an important constraint to the proper performance of FCM and SM converters.Thus,observation of the flying capacitor voltages used in active control is valuable,but using voltage sensors for observation increases cost and size of the converter.This paper deals with a new strategy to estimate the flying capacitor voltages of both FCM and SM converters.The proposed strategy is based on a discrete time model of the converter and uses only a load current sensor.The circuit was simulated using PSCAD/EMTDC software and simulation results were presented to validate the effectiveness of the proposed estimation strategy in observing the flying capacitor voltages.Simplicity is the most significant advantage of the proposed strategy,its performance being based on simple equations.展开更多
文摘Retaining walls have been used in many construction projects such as for road and inclined surfaces protection. The damage caused by an earthquake depends on the fundamental frequency, amplitude and the duration of the seismic motion. These parameters strongly depend on the seismic properties of the layers that are near the surface. In the study of retaining walls, in addition to the infl uence of soil, the infl uence of topography is also important. In the present study, site response analysis is performed by using fi nite element software PLAXIS to obtain the eff ect of various factors such as embedded length of the sheet pile, underground water table, length and angle of the nail, shear wave velocity of soil on site eff ect and dynamic response. Moreover, for better understanding of the eff ect of the above parameters, the stability analysis was performed by using shear reduction method. The results show that an increase in the embedded length of the sheet pile and the length of nailing causes an increase in the amplifi cation factor. Moreover, for shear-wave velocity in the range of 200- 600 m/s, the amplifi cation factor increases with increase of the shear-wave velocity due to the decrease of nonlinear behavior.
文摘Linde Type-A (LTA) zeolite was prepared from sodium aluminate and sodium metasilicate by hydrothermal process precursors. Sodium metasilicate prepared from molten NaOH and SiO2. The zeolite was characterized by FTIR, XRD, XRF and SEM. The adsorption of Fe(III) from aqueous solution by zeolite A was studied. Different parameters like contact time, pH and concentration of iron were investigated. The results show that at contact time of 60 min and pH of 6 maximum adsorption of iron onto zeolite was observed. The kinetic data was analyzed using pseudo-first-order and pseudo-second-order kinetic models. The adsorption kinetics of Fe(III) were fitted well with the pseudo-second-order kinetic model.
文摘Multicell converters are an interesting alternative for medium voltage and high power applications,because of the increased number of output voltage levels and apparent frequency.The two most significant types of multicell converter are the flying capacitor multicell (FCM) converter and its derivative,stacked multicell (SM) converter.Balancing flying capacitor voltages is an important constraint to the proper performance of FCM and SM converters.Thus,observation of the flying capacitor voltages used in active control is valuable,but using voltage sensors for observation increases cost and size of the converter.This paper deals with a new strategy to estimate the flying capacitor voltages of both FCM and SM converters.The proposed strategy is based on a discrete time model of the converter and uses only a load current sensor.The circuit was simulated using PSCAD/EMTDC software and simulation results were presented to validate the effectiveness of the proposed estimation strategy in observing the flying capacitor voltages.Simplicity is the most significant advantage of the proposed strategy,its performance being based on simple equations.
