High fluoride groundwater occurs widely in China, presenting a quite serious environmental problem. Zeolite from Xinyang, China was tested as the fluoride removing adsorbent. Batch and column experiments on fluoride ...High fluoride groundwater occurs widely in China, presenting a quite serious environmental problem. Zeolite from Xinyang, China was tested as the fluoride removing adsorbent. Batch and column experiments on fluoride removal using modified zeolites treated with hydrochloric acid, sodium hydroxide, sodium chloride and ferric chloride, respectively show that 0.1 mol/L HCl modified zeolite can be used as an adsorbent for fluoride, with an adsorption capacity of 173.16 mg/kg.展开更多
Through separation of the hexane-heptane–octane system in a cross-wall adiabatic dividing wall column, the effects of feed position, side-draw position, liquid split ratio, vapor split ratio and their interactions on...Through separation of the hexane-heptane–octane system in a cross-wall adiabatic dividing wall column, the effects of feed position, side-draw position, liquid split ratio, vapor split ratio and their interactions on the energy consumption were analyzed by Aspen Plus under the constant product purity, and the response surface model for the energy consumption was regressed. Based on the restriction on the optimal operating zone, the comparison of different combinations of surrogate models and optimization methods showed that, the combination of the Kriging model and multi-island genetic algorithm(Kriging-MIGA) had better prediction ability than the combination of the response surface model and partial derivative method(RSM-PD), and RSM-PD had better optimization effect than Kriging-MIGA. With a self-made cross-wall adiabatic dividing wall column, the temperature at measuring points and the energy consumption were measured during experiments, the comparison between measured values and simulated ones demonstrated that the optimized values of variables searched by RSM-PD and Kriging-MIGA could be both used as the optimum technological conditions since the experimental reliability was ensured, with the optimum technological conditions shown below: The feed position is 6, the side-draw position is 7, the combinations of liquid split ratio and vapor split ratio are [0.14, 0.5] and [0.16, 0.52], respectively. RSM-PD and Kriging-MIGA can provide the appropriate optimization methods for the dividing wall column.展开更多
Based on a series of previous studies, an experiment on the integral seismic behavior of a 1/3 scaled model of two-bay and three-story reinforced concrete frame with split columns at lower two stories is performed und...Based on a series of previous studies, an experiment on the integral seismic behavior of a 1/3 scaled model of two-bay and three-story reinforced concrete frame with split columns at lower two stories is performed under cyclic loading. The original columns at lower two stories of the model frame are short columns and they are replaced by the split columns. The hysteresis curves between the horizontal cyclic load and the lateral displacement at the top of the model frame, indicate that under the cyclic loading, the model frame undergoes the process of cracking, yielding, and maximum loading before being destroyed at the ultimate load. They also indicate that the model frame has better ductility, and the ratio of the ultimate displacement to the yielding displacement, reaches 6.0. The yielding process of the model frame shows that for the frame with split columns, plastic hinges are generated at the ends of beams and then the columns begin yielding while the frame still possesses the bearing and deformation capacity. The design idea of directly changing the short column to long one in the reinforced concrete frame may be realized by replacing the short column with the split one.展开更多
Bonding fiber reinforced polymer （FRP） has been commonly used to improve the seismic behavior of circular reinforced concrete （RC） columns in engineering practice. However, FRP jackets have a significant stress hy...Bonding fiber reinforced polymer （FRP） has been commonly used to improve the seismic behavior of circular reinforced concrete （RC） columns in engineering practice. However, FRP jackets have a significant stress hysteresis effect in this strengthening method, and pre-tensioning the FRP can overcome this problem. This paper presents test results of 25 circular RC columns strengthened with pre-stressed FRP strips under low cyclic loading. The pre-stressing of the FRP strips, types of FRP strips and longitudinal reinforcement, axial load ratio, pre-damage degree and surface treatments of the specimens are considered as the primary factors in the tests. According to the failure modes and hysteresis curves of the specimens, these factors are analyzed to investigate their effect on bearing capacity, ductility, hysteretic behavior, energy dissipation capacity and other important seismic behaviors. The results show that the initial lateral confined stress provided by pre-stressed FRP strips can effectively inhibit the emergence and development of diagonal shear cracks, and change the failure modes of specimens from brittle shear failure to bending or bending-shear failure with better ductility. As a result, the bearing capacity, ductility, energy dissipation capacity and deformation capacity of the strengthened specimens are all significantly improved.展开更多
A new type of semi-rigid thin-walled steel-concrete composite beam-to-column joint has been proposed in this paper.Five semi-rigid composite beam-to-column joint specimens subjected to hogging moments under monotonic ...A new type of semi-rigid thin-walled steel-concrete composite beam-to-column joint has been proposed in this paper.Five semi-rigid composite beam-to-column joint specimens subjected to hogging moments under monotonic loading were tested to study the static behavior of this new type of joint.The main variable parameters for the five joint specimens were the longitudinal reinforcement ratio and the joint type.The experimental results designated that the magnitude of extension of the longitudinal reinforcement is the most important factor that influenced the moment-rotation characteristic of the new type of joint.The concrete slabs could resist 3.8%-19.1% of the total shear load applied to the cross-sections near the beam-to-column connection.The edge stiffened elements,such as the flange of the lipped I-section thin-walled steel beam,were capable of having considerable inelastic deformation capacity although they had comparatively large width-to-thickness ratios.The shear failure of the concrete cantilever edge strip must be taken into account in practical design because it has significant influence on the anchorage of the longitudinal reinforcement in the new type of external joints.展开更多
It studied the behavior of transport and stability of TiO2 and SiO2 nanoparticles suspensions percolating through soil columns aiming at simulating municipal waste landfills covering soil layers performance. Experimen...It studied the behavior of transport and stability of TiO2 and SiO2 nanoparticles suspensions percolating through soil columns aiming at simulating municipal waste landfills covering soil layers performance. Experimental columns were constructed with landfill soils and water suspensions with nanoparticles percolation runs were carried out. The experimental columns were constructed with 100 mm and 200 mm of diameter and height, respectively. Outlet concentrations were measured along the percolation time using ICP-OES and nanoparticles tracking analyzer. It was observed that SiO2 nanoparticles acts as a stabilizer of TiO2 nanoparticles suspensions and promotes its transport through the soil columns, which simulates the conditions of the controlled landfills layers. The interaction of the suspensions of SiO2 nanoparticles with nanoparticles of TiO2, promote a high stability of the emulsions, which confers the high zeta potential present in SiO2 suspensions, promoting greater mobility and transport through the soil columns. The experimental results demonstrated that TiO2 nanoparticles were kept suspended, even after 10 days, which indicates good stability. It was observed that both TiO2 and SiO2 were kept in suspensions with negligible nanoparticles clustering and decantation. It was confirmed that the TiO2 and SiO2 of the outflow of soil columns are strongly affected by the soil pH, organic carbon and clay content of the soils. It was observed that the soil columns behave as a retention barrier for both TiO2 and SiO2 nanoparticles.展开更多
CQDs-doped TiO_(2)(C-TiO_(2))has drawn increased attention in recent because of its excellent catalytic performance.Understanding the transport of C-TiO_(2)in porous media is necessary for evaluating the environmental...CQDs-doped TiO_(2)(C-TiO_(2))has drawn increased attention in recent because of its excellent catalytic performance.Understanding the transport of C-TiO_(2)in porous media is necessary for evaluating the environmental process of this new nanomaterial.Column experiments were used in this study to investigate ionic strength(IS),dissolved organic matter(DOM)and sand grain size on the transport of C-TiO_(2).The mobility of C-TiO_(2)was inhibited by the increased IS and decreased sand grain size,but was promoted by the increased DOM concentration.The promotion efficiency of DOM ranked as humic acid(HA)>alginate(Alg)>bovine serum albumin(BSA),which was in the same order as their ability to change surface charges.The micromodels of pore network were prepared via 3D printing to further reveal the deposition mechanisms and spatial/temporal distribution of C-TiO_(2)in porous space.C-TiO_(2)mainly attached to the upstream region of collectors because of interception.The collector ripening was observed after long-time deposition.The existence of DOM caused visible decrease of C-TiO_(2)deposition in the pore network.HA caused the most remarkable reduce of deposition in the three types of DOM,which was consistent with the column experiment results.This research is helpful to predict the transport of C-TiO_(2)in natural porous media.展开更多
Extensive experimental work on hysteresis in a c℃urrent gas-liquid upflow packed bed was carried out with three kinds of packings and the air-water system. However, only when packed with small glass beads ((1.4 mm) w...Extensive experimental work on hysteresis in a c℃urrent gas-liquid upflow packed bed was carried out with three kinds of packings and the air-water system. However, only when packed with small glass beads ((1.4 mm) was the bed pressure drop hysteresis observed. Two more liquids with different liquid properties were employed to further examine the influence of parameters on pressure drop hysteresis. The similarity of pressure drop hysteresis in packed beds was concluded in combination of experimental evidence reported in literature.展开更多
The possibility of using a multi-stage pendulum mass damper （MSPMD） to control wind-induced vibration of a single column tower of a cable-stayed bridge during construction was studied theoretically in part I of this...The possibility of using a multi-stage pendulum mass damper （MSPMD） to control wind-induced vibration of a single column tower of a cable-stayed bridge during construction was studied theoretically in part I of this work. In this paper, the performance of the MSPMD for reducing bridge tower vibration is studied experimentally. A MSPMD model and a tower model of the bridge with geometry scaling of 1：100 were designed and manufactured. Calibration of the MSPMD model with different wire lengths is conducted to verify the analytical model of the damper. A series of tests for the uncontrolled freestanding tower, tower with cables, and tower with MSPMD model are then performed under harmonic and white noise excitations. The experimental results show that the responses of the tower model significantly decrease with the installation of the MSPMD model, which demonstrates the effectiveness of the M SPMD to mitigate the vibration of the bridge tower.展开更多
在集成散热微流道的低温共烧陶瓷(low-temperature co-fired ceramics,LTCC)封装基板中引入内嵌金属柱(embedded metal columns,EMCs)作为导热增强结构,是提升封装体散热性能的重要改进措施。基于已有的理论分析与试验研究结果,结合工...在集成散热微流道的低温共烧陶瓷(low-temperature co-fired ceramics,LTCC)封装基板中引入内嵌金属柱(embedded metal columns,EMCs)作为导热增强结构,是提升封装体散热性能的重要改进措施。基于已有的理论分析与试验研究结果,结合工艺条件,分析内嵌金属柱截面形状、长度、直径和流体入口流速对其散热性能的影响。通过正交试验设计,在有限元仿真软件中建立带有内嵌金属柱的LTCC微流道基板的热仿真模型,并对得到的热仿真数据进行极差与方差分析。研究结果表明,影响内嵌金属柱散热性能的因素由大到小依次为流体流速、内嵌金属柱截面形状、内嵌金属柱直径以及内嵌金属柱长度;在置信度为90%的情况下,流体入口流速、内嵌金属柱截面形状和直径均对其散热性能有显著影响,内嵌金属柱长度对其散热性能无显著影响。展开更多
基金This paperis supported by the National Natural Science Foundation of China( Nos.49772 15 8and4983 2 0 0 5)
文摘High fluoride groundwater occurs widely in China, presenting a quite serious environmental problem. Zeolite from Xinyang, China was tested as the fluoride removing adsorbent. Batch and column experiments on fluoride removal using modified zeolites treated with hydrochloric acid, sodium hydroxide, sodium chloride and ferric chloride, respectively show that 0.1 mol/L HCl modified zeolite can be used as an adsorbent for fluoride, with an adsorption capacity of 173.16 mg/kg.
基金the financial support by the National Natural Science Foundation of China (21306036)
文摘Through separation of the hexane-heptane–octane system in a cross-wall adiabatic dividing wall column, the effects of feed position, side-draw position, liquid split ratio, vapor split ratio and their interactions on the energy consumption were analyzed by Aspen Plus under the constant product purity, and the response surface model for the energy consumption was regressed. Based on the restriction on the optimal operating zone, the comparison of different combinations of surrogate models and optimization methods showed that, the combination of the Kriging model and multi-island genetic algorithm(Kriging-MIGA) had better prediction ability than the combination of the response surface model and partial derivative method(RSM-PD), and RSM-PD had better optimization effect than Kriging-MIGA. With a self-made cross-wall adiabatic dividing wall column, the temperature at measuring points and the energy consumption were measured during experiments, the comparison between measured values and simulated ones demonstrated that the optimized values of variables searched by RSM-PD and Kriging-MIGA could be both used as the optimum technological conditions since the experimental reliability was ensured, with the optimum technological conditions shown below: The feed position is 6, the side-draw position is 7, the combinations of liquid split ratio and vapor split ratio are [0.14, 0.5] and [0.16, 0.52], respectively. RSM-PD and Kriging-MIGA can provide the appropriate optimization methods for the dividing wall column.
基金Supported by National Science Fund for Distinguished Young Scholars of China( No. 50425824
文摘Based on a series of previous studies, an experiment on the integral seismic behavior of a 1/3 scaled model of two-bay and three-story reinforced concrete frame with split columns at lower two stories is performed under cyclic loading. The original columns at lower two stories of the model frame are short columns and they are replaced by the split columns. The hysteresis curves between the horizontal cyclic load and the lateral displacement at the top of the model frame, indicate that under the cyclic loading, the model frame undergoes the process of cracking, yielding, and maximum loading before being destroyed at the ultimate load. They also indicate that the model frame has better ductility, and the ratio of the ultimate displacement to the yielding displacement, reaches 6.0. The yielding process of the model frame shows that for the frame with split columns, plastic hinges are generated at the ends of beams and then the columns begin yielding while the frame still possesses the bearing and deformation capacity. The design idea of directly changing the short column to long one in the reinforced concrete frame may be realized by replacing the short column with the split one.
基金National Natural Science Foundation of China under Grant No.51178029 State Key Laboratory for Disaster Reduction in Civil Engineering at Tongji University under Grant No.SLDRCE08-MB-01
文摘Bonding fiber reinforced polymer （FRP） has been commonly used to improve the seismic behavior of circular reinforced concrete （RC） columns in engineering practice. However, FRP jackets have a significant stress hysteresis effect in this strengthening method, and pre-tensioning the FRP can overcome this problem. This paper presents test results of 25 circular RC columns strengthened with pre-stressed FRP strips under low cyclic loading. The pre-stressing of the FRP strips, types of FRP strips and longitudinal reinforcement, axial load ratio, pre-damage degree and surface treatments of the specimens are considered as the primary factors in the tests. According to the failure modes and hysteresis curves of the specimens, these factors are analyzed to investigate their effect on bearing capacity, ductility, hysteretic behavior, energy dissipation capacity and other important seismic behaviors. The results show that the initial lateral confined stress provided by pre-stressed FRP strips can effectively inhibit the emergence and development of diagonal shear cracks, and change the failure modes of specimens from brittle shear failure to bending or bending-shear failure with better ductility. As a result, the bearing capacity, ductility, energy dissipation capacity and deformation capacity of the strengthened specimens are all significantly improved.
基金Sponsored by the National Natural Science Foundation of China (Grant No.50478027)
文摘A new type of semi-rigid thin-walled steel-concrete composite beam-to-column joint has been proposed in this paper.Five semi-rigid composite beam-to-column joint specimens subjected to hogging moments under monotonic loading were tested to study the static behavior of this new type of joint.The main variable parameters for the five joint specimens were the longitudinal reinforcement ratio and the joint type.The experimental results designated that the magnitude of extension of the longitudinal reinforcement is the most important factor that influenced the moment-rotation characteristic of the new type of joint.The concrete slabs could resist 3.8%-19.1% of the total shear load applied to the cross-sections near the beam-to-column connection.The edge stiffened elements,such as the flange of the lipped I-section thin-walled steel beam,were capable of having considerable inelastic deformation capacity although they had comparatively large width-to-thickness ratios.The shear failure of the concrete cantilever edge strip must be taken into account in practical design because it has significant influence on the anchorage of the longitudinal reinforcement in the new type of external joints.
文摘It studied the behavior of transport and stability of TiO2 and SiO2 nanoparticles suspensions percolating through soil columns aiming at simulating municipal waste landfills covering soil layers performance. Experimental columns were constructed with landfill soils and water suspensions with nanoparticles percolation runs were carried out. The experimental columns were constructed with 100 mm and 200 mm of diameter and height, respectively. Outlet concentrations were measured along the percolation time using ICP-OES and nanoparticles tracking analyzer. It was observed that SiO2 nanoparticles acts as a stabilizer of TiO2 nanoparticles suspensions and promotes its transport through the soil columns, which simulates the conditions of the controlled landfills layers. The interaction of the suspensions of SiO2 nanoparticles with nanoparticles of TiO2, promote a high stability of the emulsions, which confers the high zeta potential present in SiO2 suspensions, promoting greater mobility and transport through the soil columns. The experimental results demonstrated that TiO2 nanoparticles were kept suspended, even after 10 days, which indicates good stability. It was observed that both TiO2 and SiO2 were kept in suspensions with negligible nanoparticles clustering and decantation. It was confirmed that the TiO2 and SiO2 of the outflow of soil columns are strongly affected by the soil pH, organic carbon and clay content of the soils. It was observed that the soil columns behave as a retention barrier for both TiO2 and SiO2 nanoparticles.
基金This work was supported by the National Natural Science Foundation of China(No.41773110)the National Natural Science Foundation of China-Shandong Joint Fund(No.U2006214)the Shenzhen Science and Technology Research and Development Funds,China(No.JCYJ20180301171357901).
文摘CQDs-doped TiO_(2)(C-TiO_(2))has drawn increased attention in recent because of its excellent catalytic performance.Understanding the transport of C-TiO_(2)in porous media is necessary for evaluating the environmental process of this new nanomaterial.Column experiments were used in this study to investigate ionic strength(IS),dissolved organic matter(DOM)and sand grain size on the transport of C-TiO_(2).The mobility of C-TiO_(2)was inhibited by the increased IS and decreased sand grain size,but was promoted by the increased DOM concentration.The promotion efficiency of DOM ranked as humic acid(HA)>alginate(Alg)>bovine serum albumin(BSA),which was in the same order as their ability to change surface charges.The micromodels of pore network were prepared via 3D printing to further reveal the deposition mechanisms and spatial/temporal distribution of C-TiO_(2)in porous space.C-TiO_(2)mainly attached to the upstream region of collectors because of interception.The collector ripening was observed after long-time deposition.The existence of DOM caused visible decrease of C-TiO_(2)deposition in the pore network.HA caused the most remarkable reduce of deposition in the three types of DOM,which was consistent with the column experiment results.This research is helpful to predict the transport of C-TiO_(2)in natural porous media.
基金Supported by the National Natural Science Foundation of China (No.: 29676042)
文摘Extensive experimental work on hysteresis in a c℃urrent gas-liquid upflow packed bed was carried out with three kinds of packings and the air-water system. However, only when packed with small glass beads ((1.4 mm) was the bed pressure drop hysteresis observed. Two more liquids with different liquid properties were employed to further examine the influence of parameters on pressure drop hysteresis. The similarity of pressure drop hysteresis in packed beds was concluded in combination of experimental evidence reported in literature.
基金Area Strategic Development Program in Structural Control and Intelligent Building from The Hong Kong Polytechnic UniversityNational Natural Science Foundation of China Under Grant No. 50408011
文摘The possibility of using a multi-stage pendulum mass damper （MSPMD） to control wind-induced vibration of a single column tower of a cable-stayed bridge during construction was studied theoretically in part I of this work. In this paper, the performance of the MSPMD for reducing bridge tower vibration is studied experimentally. A MSPMD model and a tower model of the bridge with geometry scaling of 1：100 were designed and manufactured. Calibration of the MSPMD model with different wire lengths is conducted to verify the analytical model of the damper. A series of tests for the uncontrolled freestanding tower, tower with cables, and tower with MSPMD model are then performed under harmonic and white noise excitations. The experimental results show that the responses of the tower model significantly decrease with the installation of the MSPMD model, which demonstrates the effectiveness of the M SPMD to mitigate the vibration of the bridge tower.
文摘在集成散热微流道的低温共烧陶瓷(low-temperature co-fired ceramics,LTCC)封装基板中引入内嵌金属柱(embedded metal columns,EMCs)作为导热增强结构,是提升封装体散热性能的重要改进措施。基于已有的理论分析与试验研究结果,结合工艺条件,分析内嵌金属柱截面形状、长度、直径和流体入口流速对其散热性能的影响。通过正交试验设计,在有限元仿真软件中建立带有内嵌金属柱的LTCC微流道基板的热仿真模型,并对得到的热仿真数据进行极差与方差分析。研究结果表明,影响内嵌金属柱散热性能的因素由大到小依次为流体流速、内嵌金属柱截面形状、内嵌金属柱直径以及内嵌金属柱长度;在置信度为90%的情况下,流体入口流速、内嵌金属柱截面形状和直径均对其散热性能有显著影响,内嵌金属柱长度对其散热性能无显著影响。
