In this paper, the control performance is investigated of Circular Tuned Liquid Column Dampers (CTLCD) over torsional response of offshore platform structures excited by ground motions. Based on the equation of motion...In this paper, the control performance is investigated of Circular Tuned Liquid Column Dampers (CTLCD) over torsional response of offshore platform structures excited by ground motions. Based on the equation of motion for the CTLCD-structure system, the optimal control parameters of CTLCD are given through some derivations on the supposition that the ground motion is a stochastic process. The influence of systematic parameters on the equivalent damping ratio of the structures is analyzed with purely torsional vibration and translational-torsional coupled vibration, respectively. The results show that the Circular Tuned Liquid Column Damper (CTLCD) is an effective torsional response control device.展开更多
Eccentric decoupling blasting is commonly used in underground excavation.Determination of perimeter hole parameters(such as the blasthole diameter,spacing,and burden)based on an eccentric charge structure is vital for...Eccentric decoupling blasting is commonly used in underground excavation.Determination of perimeter hole parameters(such as the blasthole diameter,spacing,and burden)based on an eccentric charge structure is vital for achieving an excellent smooth blasting effect.In this paper,the Riedel-Hiermaier-Thoma(RHT)model was employed to study rock mass damage under smooth blasting.Firstly,the parameters of the RHT model were calibrated by using the existing SHPB experiment,which were then verified by the existing blasting experiment results.Secondly,the influence of different charge structures on the blasting effect was investigated using the RHT model.The simulation results indicated that eccentric charge blasting has an obvious pressure eccentricity effect.Finally,to improve the blasting effect,the smooth blasting parameters were optimized based on an eccentric charge structure.The overbreak and underbreak phenomena were effectively controlled,and a good blasting effect was achieved with the optimized blasting parameters.展开更多
A new approach to reducing the seismic response of spatial structures with magneto-theological （MR） dampers is presented in this paper. The Genetic Algorithm with small populations （μGA） is used to optimize the c...A new approach to reducing the seismic response of spatial structures with magneto-theological （MR） dampers is presented in this paper. The Genetic Algorithm with small populations （μGA） is used to optimize the control for the MR dampers to reduce structural vibration, which is difficult to achieve using classical optimal control. The advantages of μGA are the use of global properties and that fewer conditions are required to obtain the optimal function. Numerical results demonstrate the effectiveness of the proposed method in reducing the seismic response of structures.展开更多
Parabolic trough collectors are essential components of solar thermal power plants,and the non-uniform heat flux on the walls may lead to low heat transfer coefficients and large wall temperature differences.A novel j...Parabolic trough collectors are essential components of solar thermal power plants,and the non-uniform heat flux on the walls may lead to low heat transfer coefficients and large wall temperature differences.A novel jet structure is proposed in this paper to explore the feasibility of adopting impinging jets to improve the heat transfer performance of the collector tube with supercritical carbon dioxide(S-CO_(2))as the working fluid.The physical model is built based on several assumptions,and numerical simulations are performed under the mass flow rate of 0.25-0.75 kg/s and the average surface heat flux of 14.7-33 kW/m^(2).Firstly,performance comparisons are made between the jet and tube-in-tube structures.The results show that the average heat transfer coefficient h of the jet structure is 46.5%higher than that of the tube-in-tube structure and the corresponding average temperature differenceΔT between the wall and S-CO_(2)is 31.7%lower.Secondly,the effects of the jet hole circumferential position and diameter on heat transfer are investigated.It's found that by adjusting the circumferential position of the jet hole from 60°to 120°and matching the impingement area of the jets and the high heat flux region,h can be increased by 14.2%andΔT can be reduced by 12.4%.h is also found to be increased by 77.4%when the jet hole diameter is reduced from D=9.7 mm to D=5 mm.Furthermore,the jet structure is further modified by incorporating it with the eccentric configuration.The effect of eccentricity e is studied in detail,and results show that appropriate eccentricity results in higher h and smallerΔT due to the decreased impingement distance and the increased heat transfer.This study can guide the design and optimization of parabolic trough collectors.展开更多
In order to effectively improve penetration rates and enhance wellbore quality for vertical wells,a new Automatic Vertical Drilling Tool(AVDT)based on Eccentric Braced Structure(EBS)is designed.Applying operating prin...In order to effectively improve penetration rates and enhance wellbore quality for vertical wells,a new Automatic Vertical Drilling Tool(AVDT)based on Eccentric Braced Structure(EBS)is designed.Applying operating principle of rotary steering drilling,AVDT adds offset gravity block automatic induction inclination mechanism.When hole straightening happens,tools take essentric moment to be produced by gravity of offset gravity lock to control the bearing of guide force,so that well straightening is achieved.The normal tool's size of the AVDT is designed as 215.9 mm,other major components'sizes are worked out by the result of theoretical analysis,including the offset angle of EBS.This paper aims to introduce the structure,operating principle,theoretical analysis and describe the key components'parameters setting of the AVDT.展开更多
文摘In this paper, the control performance is investigated of Circular Tuned Liquid Column Dampers (CTLCD) over torsional response of offshore platform structures excited by ground motions. Based on the equation of motion for the CTLCD-structure system, the optimal control parameters of CTLCD are given through some derivations on the supposition that the ground motion is a stochastic process. The influence of systematic parameters on the equivalent damping ratio of the structures is analyzed with purely torsional vibration and translational-torsional coupled vibration, respectively. The results show that the Circular Tuned Liquid Column Damper (CTLCD) is an effective torsional response control device.
基金Projects(11802058,52074262)supported by the National Natural Science Foundation of ChinaProjects(BK20170670,BK20180651)supported by the Jiangsu Youth Foundation,China+2 种基金Project(2020QN06)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(SKLGDUEK1803)supported by the State Key Laboratory for Geomechanics and Deep Underground Engineering,ChinaProject supported by the Mass Entrepreneurship and Innovation Project of Jiangsu,China。
文摘Eccentric decoupling blasting is commonly used in underground excavation.Determination of perimeter hole parameters(such as the blasthole diameter,spacing,and burden)based on an eccentric charge structure is vital for achieving an excellent smooth blasting effect.In this paper,the Riedel-Hiermaier-Thoma(RHT)model was employed to study rock mass damage under smooth blasting.Firstly,the parameters of the RHT model were calibrated by using the existing SHPB experiment,which were then verified by the existing blasting experiment results.Secondly,the influence of different charge structures on the blasting effect was investigated using the RHT model.The simulation results indicated that eccentric charge blasting has an obvious pressure eccentricity effect.Finally,to improve the blasting effect,the smooth blasting parameters were optimized based on an eccentric charge structure.The overbreak and underbreak phenomena were effectively controlled,and a good blasting effect was achieved with the optimized blasting parameters.
基金the Outstanding Youth Science Foundation of the National Natural Science Foundation of China Under Grant No. 50025823
文摘A new approach to reducing the seismic response of spatial structures with magneto-theological （MR） dampers is presented in this paper. The Genetic Algorithm with small populations （μGA） is used to optimize the control for the MR dampers to reduce structural vibration, which is difficult to achieve using classical optimal control. The advantages of μGA are the use of global properties and that fewer conditions are required to obtain the optimal function. Numerical results demonstrate the effectiveness of the proposed method in reducing the seismic response of structures.
基金supported by the National Natural Science Foundation of China(Grant No.52376087)Hunan Provincial Natural Science Foundation of China(Grant No.2023JJ30688)。
文摘Parabolic trough collectors are essential components of solar thermal power plants,and the non-uniform heat flux on the walls may lead to low heat transfer coefficients and large wall temperature differences.A novel jet structure is proposed in this paper to explore the feasibility of adopting impinging jets to improve the heat transfer performance of the collector tube with supercritical carbon dioxide(S-CO_(2))as the working fluid.The physical model is built based on several assumptions,and numerical simulations are performed under the mass flow rate of 0.25-0.75 kg/s and the average surface heat flux of 14.7-33 kW/m^(2).Firstly,performance comparisons are made between the jet and tube-in-tube structures.The results show that the average heat transfer coefficient h of the jet structure is 46.5%higher than that of the tube-in-tube structure and the corresponding average temperature differenceΔT between the wall and S-CO_(2)is 31.7%lower.Secondly,the effects of the jet hole circumferential position and diameter on heat transfer are investigated.It's found that by adjusting the circumferential position of the jet hole from 60°to 120°and matching the impingement area of the jets and the high heat flux region,h can be increased by 14.2%andΔT can be reduced by 12.4%.h is also found to be increased by 77.4%when the jet hole diameter is reduced from D=9.7 mm to D=5 mm.Furthermore,the jet structure is further modified by incorporating it with the eccentric configuration.The effect of eccentricity e is studied in detail,and results show that appropriate eccentricity results in higher h and smallerΔT due to the decreased impingement distance and the increased heat transfer.This study can guide the design and optimization of parabolic trough collectors.
文摘In order to effectively improve penetration rates and enhance wellbore quality for vertical wells,a new Automatic Vertical Drilling Tool(AVDT)based on Eccentric Braced Structure(EBS)is designed.Applying operating principle of rotary steering drilling,AVDT adds offset gravity block automatic induction inclination mechanism.When hole straightening happens,tools take essentric moment to be produced by gravity of offset gravity lock to control the bearing of guide force,so that well straightening is achieved.The normal tool's size of the AVDT is designed as 215.9 mm,other major components'sizes are worked out by the result of theoretical analysis,including the offset angle of EBS.This paper aims to introduce the structure,operating principle,theoretical analysis and describe the key components'parameters setting of the AVDT.
