极低放填埋场防渗层设置是阻滞放射性核素进入生态环境的重要工程措施,开展防渗层的阻滞性能研究对于防渗层的设计和环境安全评价具有重要意义。针对来源废物中的主要核素^(60)Co和^(63)Ni,采用静态吸附实验和柱迁移实验获得了场址粘土...极低放填埋场防渗层设置是阻滞放射性核素进入生态环境的重要工程措施,开展防渗层的阻滞性能研究对于防渗层的设计和环境安全评价具有重要意义。针对来源废物中的主要核素^(60)Co和^(63)Ni,采用静态吸附实验和柱迁移实验获得了场址粘土的饱和渗透系数、分配系数及弥散度等特征参数,并通过数学模型预测了核素穿透防渗层后的浓度变化。结果表明,Co、Ni的分配系数分别为140.92 m L·g^(-1)和380.43 m L·g^(-1),阻滞因子分别为859和2 317,表明场址粘土对^(60)Co、^(63)Ni具有较强的阻滞性能;在防渗层正常发挥功能的情景下,防渗层渗出液中的^(60)Co、^(63)Ni浓度很低,用此类粘土建成的防渗层能够确保当地环境安全。展开更多
The earthquake resistance of transmission tower has been often discussed from the viewpoint of reinforcing the foundation of steel tower, but there are also few studies considering the damping characteristics of the t...The earthquake resistance of transmission tower has been often discussed from the viewpoint of reinforcing the foundation of steel tower, but there are also few studies considering the damping characteristics of the tower. This paper focuses on the viscous damper which has been adopted for seismic reinforcement of bridges in recent years. The purpose of this study is to improve the seismic performance of steel tower by giving the high damping to the tower. We construct a single tower model considering the influence of transmission line, and then simulate the vibration characteristics and seismic behavior of the tower by the eigenvalue analysis and the dynamic response analysis. The results show that the transmission tower with viscous damper can reduce its own response effectively and drastically. This research concludes that it is necessary to consider the extreme increase of steel tower＇s response depending on the seismic wave and the collapse of steel tower can be avoided by using the optimum damper in the design of the transmission tower.展开更多
Due to the high viscosity of magnetorheological(MR)fluid,eliminating air pockets dissolved in the fluid is very difficult,which results in a force lag phenomenon.In order to evaluate the performance of a semi-active c...Due to the high viscosity of magnetorheological(MR)fluid,eliminating air pockets dissolved in the fluid is very difficult,which results in a force lag phenomenon.In order to evaluate the performance of a semi-active control system based on the MR damper considering the trapped air effect,a performance test on a MR damper is carried out under different loading cases,and the influence of the input current,excitation amplitude and frequency on the force lag phenomenon is analyzed.A concise and efficient parametric model,combining the simple Bouc-Wen model and a spring with small stiffness,is proposed to portray the experimental characteristics of the MR damper with force lag,and then the response analysis of the semi-active controlled single-degree-of-freedom(SDOF)structure is performed using the classic clipped-optimal control strategy based on acceleration feedback.Numerical results show that the trapped air in the MR fluid can weaken the control effect of the MR damper,and the performance of the semi-active control system will be reduced more obviously and become close to the passive-off control with the increasing content of air trapped in the MR fluid.展开更多
文摘极低放填埋场防渗层设置是阻滞放射性核素进入生态环境的重要工程措施,开展防渗层的阻滞性能研究对于防渗层的设计和环境安全评价具有重要意义。针对来源废物中的主要核素^(60)Co和^(63)Ni,采用静态吸附实验和柱迁移实验获得了场址粘土的饱和渗透系数、分配系数及弥散度等特征参数,并通过数学模型预测了核素穿透防渗层后的浓度变化。结果表明,Co、Ni的分配系数分别为140.92 m L·g^(-1)和380.43 m L·g^(-1),阻滞因子分别为859和2 317,表明场址粘土对^(60)Co、^(63)Ni具有较强的阻滞性能;在防渗层正常发挥功能的情景下,防渗层渗出液中的^(60)Co、^(63)Ni浓度很低,用此类粘土建成的防渗层能够确保当地环境安全。
文摘The earthquake resistance of transmission tower has been often discussed from the viewpoint of reinforcing the foundation of steel tower, but there are also few studies considering the damping characteristics of the tower. This paper focuses on the viscous damper which has been adopted for seismic reinforcement of bridges in recent years. The purpose of this study is to improve the seismic performance of steel tower by giving the high damping to the tower. We construct a single tower model considering the influence of transmission line, and then simulate the vibration characteristics and seismic behavior of the tower by the eigenvalue analysis and the dynamic response analysis. The results show that the transmission tower with viscous damper can reduce its own response effectively and drastically. This research concludes that it is necessary to consider the extreme increase of steel tower＇s response depending on the seismic wave and the collapse of steel tower can be avoided by using the optimum damper in the design of the transmission tower.
基金The National Science Fund for Distinguished Young Scholars(No.51625803)China and Korea International Cooperation Project of the National Key Research and Development Program(No.2016YEE0119700)+3 种基金the Fundamental Research Funds for the Central Universities(No.3205008102)the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(No.CE02-2-33)Research and Innovation Project for College Graduates of Jiangsu Province(No.KYLX15_0088,KYLX16_0255)the State Foundation for Studying Abroad,China
文摘Due to the high viscosity of magnetorheological(MR)fluid,eliminating air pockets dissolved in the fluid is very difficult,which results in a force lag phenomenon.In order to evaluate the performance of a semi-active control system based on the MR damper considering the trapped air effect,a performance test on a MR damper is carried out under different loading cases,and the influence of the input current,excitation amplitude and frequency on the force lag phenomenon is analyzed.A concise and efficient parametric model,combining the simple Bouc-Wen model and a spring with small stiffness,is proposed to portray the experimental characteristics of the MR damper with force lag,and then the response analysis of the semi-active controlled single-degree-of-freedom(SDOF)structure is performed using the classic clipped-optimal control strategy based on acceleration feedback.Numerical results show that the trapped air in the MR fluid can weaken the control effect of the MR damper,and the performance of the semi-active control system will be reduced more obviously and become close to the passive-off control with the increasing content of air trapped in the MR fluid.
