The development of effective uranium-removal techniques is of great significance to the environment and human health.In this work,a double potential step technique(DPST)was applied to remove U(VI)from uranium-containi...The development of effective uranium-removal techniques is of great significance to the environment and human health.In this work,a double potential step technique(DPST)was applied to remove U(VI)from uranium-containing wastewater using a carbon felt electrode modified by graphene oxide/phytic acid composite(GO-PA@CF).The application of DPST can inhibit water splitting and prevent GO-PA from adsorbing other interfering ions in wastewater.The GO-PA composite can effectively accelerate the electrochemical reduction rate of U(VI),which significantly improved the electrochemical deposition rate of uranium oxide.As a result,the maximum removal efficiency and maximum removal capacity of GOPA@CF electrode reached 98.7%and 1149.3 mg/g,respectively.The removal efficiency remained 97.2%after five cycles of reuse.Moreover,the removal efficiency of GO-PA@CF electrode can reach more than 70%in simulated wastewater.展开更多
Cobalt ferrite CoxNi1-xFe2O4 （x = 0, 0.5, 1 ） particles with controllable magnetic properties have been prepared by calcination of co-substituted NiFe^2＋Fe^3＋ -layered double hydroxide （NiFe^2＋Fe^3＋-LDH） precu...Cobalt ferrite CoxNi1-xFe2O4 （x = 0, 0.5, 1 ） particles with controllable magnetic properties have been prepared by calcination of co-substituted NiFe^2＋Fe^3＋ -layered double hydroxide （NiFe^2＋Fe^3＋-LDH） precursors prepared via a scalable method involving separate nucleation and aging steps （SNAS）. Their structural and magnetic characteristics were investigated by powder X-ray diffraction （XRD）, scanning electron microscopy （SEM） and vibrating sample magnetometry （VSM）. Measurements of magnetic properties show that the saturation magnetization （Ms） and coercivity （He） of the calcined products increased with increasing cobalt content. The LDH precursor-based product obtained by calcination of a mixture of CoFe^2＋Fe3^＋-LDH and NiFe^2＋Fe^3＋ -LDH powders with a Co/Ni molar ratio of 1：1, exhibits a moderate value of Ms and an increased value of He compared to the corresponding values for an Ni0.5Co0.5Fe2O4 material prepared by calcination of a Co0.5Ni0.5Fe^2＋Fe^3＋-LDH precursor, and a physical mixture of CoFe2O4 and NiFe2O4 with a Co/Ni molar ratio of 1 ： 1. These results may provide a way to regulate magnetic anisotropy of ferrite spinels by varying the composition of the LDH precursors.展开更多
In rest-to-rest maneuvers,input shapers like the double step(DS),zero vibration(ZV),and zero vibration derivative(ZVD)are widely utilized to eliminate residual vibrations in single-mode systems.These shapers can be us...In rest-to-rest maneuvers,input shapers like the double step(DS),zero vibration(ZV),and zero vibration derivative(ZVD)are widely utilized to eliminate residual vibrations in single-mode systems.These shapers can be used to eliminate residual oscillations in multimode systems,given that the higher frequencies are odd multiples of the system's fundamental frequency.However,the natural frequencies depend on the physical properties of the system,and such ratios cannot be guaranteed.In this study,an analytical frequency modulation technique is proposed to eliminate the residual oscillations of a double pendulum using a modified single-mode shaper.The proposed technique is based on altering the natural frequencies of the system,forcing the odd multiple ratio.This involves modifying a single-mode double-step(SMDS)input shaper by adding scaled state variables,first and second angles,to the original shaper.This addition allows the user to choose the first natural frequency and force the second natural frequency to be an odd multiple of the chosen frequency.To apply the proposed technique,the double pendulum nonlinear equations of motion are derived,linearized,and then solved analytically using modal analysis.The scaling parameters used to modify the natural frequencies are then solved analytically.To prove the concept,several numerical simulations with randomly selected parameters are presented and then experimentally tested on a scaled overhead crane.The numerical and experimental results demonstrate the effectiveness of the proposed technique.展开更多
基金the financial support of the National Natural Science Foundation of China(Nos.41361088 and41867063)。
文摘The development of effective uranium-removal techniques is of great significance to the environment and human health.In this work,a double potential step technique(DPST)was applied to remove U(VI)from uranium-containing wastewater using a carbon felt electrode modified by graphene oxide/phytic acid composite(GO-PA@CF).The application of DPST can inhibit water splitting and prevent GO-PA from adsorbing other interfering ions in wastewater.The GO-PA composite can effectively accelerate the electrochemical reduction rate of U(VI),which significantly improved the electrochemical deposition rate of uranium oxide.As a result,the maximum removal efficiency and maximum removal capacity of GOPA@CF electrode reached 98.7%and 1149.3 mg/g,respectively.The removal efficiency remained 97.2%after five cycles of reuse.Moreover,the removal efficiency of GO-PA@CF electrode can reach more than 70%in simulated wastewater.
基金supported by the National Natural Science Foundation of China, the 111 Project (B07004)the Program for New Century Excellent Talents in Universities, the Beijing Nova Program (2007B021)the Natural Science Foundation for Young Teachers of Beijing University of Chemical Technology
文摘Cobalt ferrite CoxNi1-xFe2O4 （x = 0, 0.5, 1 ） particles with controllable magnetic properties have been prepared by calcination of co-substituted NiFe^2＋Fe^3＋ -layered double hydroxide （NiFe^2＋Fe^3＋-LDH） precursors prepared via a scalable method involving separate nucleation and aging steps （SNAS）. Their structural and magnetic characteristics were investigated by powder X-ray diffraction （XRD）, scanning electron microscopy （SEM） and vibrating sample magnetometry （VSM）. Measurements of magnetic properties show that the saturation magnetization （Ms） and coercivity （He） of the calcined products increased with increasing cobalt content. The LDH precursor-based product obtained by calcination of a mixture of CoFe^2＋Fe3^＋-LDH and NiFe^2＋Fe^3＋ -LDH powders with a Co/Ni molar ratio of 1：1, exhibits a moderate value of Ms and an increased value of He compared to the corresponding values for an Ni0.5Co0.5Fe2O4 material prepared by calcination of a Co0.5Ni0.5Fe^2＋Fe^3＋-LDH precursor, and a physical mixture of CoFe2O4 and NiFe2O4 with a Co/Ni molar ratio of 1 ： 1. These results may provide a way to regulate magnetic anisotropy of ferrite spinels by varying the composition of the LDH precursors.
基金supported by the Kuwait University Research Sector(EM04/24).
文摘In rest-to-rest maneuvers,input shapers like the double step(DS),zero vibration(ZV),and zero vibration derivative(ZVD)are widely utilized to eliminate residual vibrations in single-mode systems.These shapers can be used to eliminate residual oscillations in multimode systems,given that the higher frequencies are odd multiples of the system's fundamental frequency.However,the natural frequencies depend on the physical properties of the system,and such ratios cannot be guaranteed.In this study,an analytical frequency modulation technique is proposed to eliminate the residual oscillations of a double pendulum using a modified single-mode shaper.The proposed technique is based on altering the natural frequencies of the system,forcing the odd multiple ratio.This involves modifying a single-mode double-step(SMDS)input shaper by adding scaled state variables,first and second angles,to the original shaper.This addition allows the user to choose the first natural frequency and force the second natural frequency to be an odd multiple of the chosen frequency.To apply the proposed technique,the double pendulum nonlinear equations of motion are derived,linearized,and then solved analytically using modal analysis.The scaling parameters used to modify the natural frequencies are then solved analytically.To prove the concept,several numerical simulations with randomly selected parameters are presented and then experimentally tested on a scaled overhead crane.The numerical and experimental results demonstrate the effectiveness of the proposed technique.
