To achieve the manufacturing of Thin-Wall and High-Rib Components(TWHRC)with high precision,a novel heavy load Multi-DOF Envelope Forming Press(MEFP)with Parallel Kinematic Mechanism(PKM),driven by six Permanent Magne...To achieve the manufacturing of Thin-Wall and High-Rib Components(TWHRC)with high precision,a novel heavy load Multi-DOF Envelope Forming Press(MEFP)with Parallel Kinematic Mechanism(PKM),driven by six Permanent Magnet Synchronous Motors(PMSMs),is developed.However,on account of the heavy forming load,the PMSM parameters are in great variation.Meanwhile,the PMSM is always in a transient state caused by fast time-varying forming load,resulting in low identification precision of varied PMSM parameters and control precision of PMSM under traditional parameter identification methods.To solve this problem,a novel Sliding Mode Control Method with Enhanced PMSM Parameter Identification(SMCMEPPI)for heavy load MEFP is proposed.Firstly,the kinematic model of MEFP is established.Secondly,the variation law of PMSM parameters under heavy load is revealed.Thirdly,an enhanced PMSM parameter identification method is proposed,in which the q axis current of PMSM is used to represent the changing rate of forming load and the adjustment factor is first proposed to remove improper input of PMSM parameter identification online.Fourthly,the Electromechanical Coupling Dynamic Model(ECDM)of MEFP,which includes identified PMSM parameters,is developed.Finally,based on the developed ECDM,a novel SMCMEPPI is proposed to realize the high-precision control of heavy load MEFP.The experimental results indicate that the proposed SMCMEPPI can significantly improve the control precision of heavy load MEFP.展开更多
The enhanced drilling parameters and custom-designed polycrystalline diamond compact(PDC)bits have greatly improved both rate of penetration(ROP)and footage.Then how to further improve the bit’s ROP and how to deal w...The enhanced drilling parameters and custom-designed polycrystalline diamond compact(PDC)bits have greatly improved both rate of penetration(ROP)and footage.Then how to further improve the bit’s ROP and how to deal with the side effects caused by the enhanced drilling parameters remain a challenge.In this work,the single-cutter rock-cutting tests and full-sized bit drilling tests were conducted to investigate the effects of rock types,drilling parameters,and bit designs on ROP.The results showed that in the easy-to-drill formations,the enhanced drilling parameters had a more pronounced effect on improving the bit’s ROP than the optimizations of bit designs such as changing the cutter shape and size.On the other hand,in the hard-to-drill formations,smaller-sized and shaped PDC cutters combined with high-torque tools offered a promising approach to increase ROP.To further improve ROP and footage,two innovative approaches were introduced:improving the bit durability without compromising ROP to ensure one-trip drilling,and using extended directional nozzles together with enhanced hydraulic parameters.The bit durability was improved by optimizing the cutter shape and diamond materials,which helped complete the single-run footage of 2986 m in the field trial of Shengli Oilfield.It was also found that the extended directional nozzle was less effective under conventional hydraulic parameters,but increased the ROP by 32.1%under enhanced hydraulic parameters because of improving jet impact performance through reduced jet diffusion.The findings provided insights for ROP improvement in the oil and gas drilling operations.展开更多
The Ohmically heated circular limiter tokamak ADITYA （R0 = 75 cm, a = 25 cm） has been upgraded to a tokamak named the ADITYA Upgrade （ADITYA-U） with an open divertor configuration with divertor plates. The main go...The Ohmically heated circular limiter tokamak ADITYA （R0 = 75 cm, a = 25 cm） has been upgraded to a tokamak named the ADITYA Upgrade （ADITYA-U） with an open divertor configuration with divertor plates. The main goal of ADITYA-U is to carry out dedicated experiments relevant for bigger fusion machines including ITER, such as the generation and control of runaway electrons, disruption prediction, and mitigation studies, along with an improvement in confinement with shaped plasma. The ADITYA tokamak was dismantled and the assembly of ADITYA-U was completed in March 2016. Integration of subsystems like data acquisition and remote operation along with plasma production and preliminary plasma characterization of ADITYA-U plasmas are presented in this paper.展开更多
Image morphing is a powerful tool for visual effect. In this paper, a view interpolation algorithm is proposed to simulate a virtual walk along a street from start position to end position. To simulate a virtual walki...Image morphing is a powerful tool for visual effect. In this paper, a view interpolation algorithm is proposed to simulate a virtual walk along a street from start position to end position. To simulate a virtual walking view needs to create new appearing scene in the vision-vanishing point and disappearing scene beyond the scope of view. To attain these two aims we use two enhanced position parameters to match pixels of source images and target images. One enhanced position parameter is the angular coordinates of pixels. Another enhanced position parameter is the distances from pixels to the vision-vanishing point. According to the parameter values, pixels beyond the scope of view can be ＂moved＂ out in linear interpolation. Result demonstrates the validity of the algorithm. Another advantage of this algorithm is that the enhanced position parameters are based on real locations and walking distances, so it is also an approach to online virtual tour by satellite maps of virtual globe applications such as Google Earth.展开更多
In this study,nine square concrete columns,including six CFRP/ECCs and three plain concrete control specimen columns,were prepared. The CFRP tubes with fibers oriented in the hoop direction were manufactured with 10,2...In this study,nine square concrete columns,including six CFRP/ECCs and three plain concrete control specimen columns,were prepared. The CFRP tubes with fibers oriented in the hoop direction were manufactured with 10,20,or 40 mm rounded corner radii at vertical edges. A 100 mm overlap in the direction of fibers was provided to ensure a proper bond. Uniaxial compression tests were conducted to investigate the compressive behaviors including the axial strength,stress-strain response,and ductility. It is evident that the CFRP tube confinement can improve the compressive behavior of concrete core,in terms of axial compressive strength or axial deformability. Based on the experimental results and some existing test database attained by other researchers,a design-oriented model is developed. The predictions of the model for CFRP/ECCs show good agreement with test results.展开更多
基金the National Science and Technology Major Project of China(No.2019-Ⅶ-0017-0158)the National Natural Science Foundation of China(Nos.U2037204,U21A20131)the Innovative Research Team Development Program of Ministry of Education of China(No.IRT17R83)for the support given to this research。
文摘To achieve the manufacturing of Thin-Wall and High-Rib Components(TWHRC)with high precision,a novel heavy load Multi-DOF Envelope Forming Press(MEFP)with Parallel Kinematic Mechanism(PKM),driven by six Permanent Magnet Synchronous Motors(PMSMs),is developed.However,on account of the heavy forming load,the PMSM parameters are in great variation.Meanwhile,the PMSM is always in a transient state caused by fast time-varying forming load,resulting in low identification precision of varied PMSM parameters and control precision of PMSM under traditional parameter identification methods.To solve this problem,a novel Sliding Mode Control Method with Enhanced PMSM Parameter Identification(SMCMEPPI)for heavy load MEFP is proposed.Firstly,the kinematic model of MEFP is established.Secondly,the variation law of PMSM parameters under heavy load is revealed.Thirdly,an enhanced PMSM parameter identification method is proposed,in which the q axis current of PMSM is used to represent the changing rate of forming load and the adjustment factor is first proposed to remove improper input of PMSM parameter identification online.Fourthly,the Electromechanical Coupling Dynamic Model(ECDM)of MEFP,which includes identified PMSM parameters,is developed.Finally,based on the developed ECDM,a novel SMCMEPPI is proposed to realize the high-precision control of heavy load MEFP.The experimental results indicate that the proposed SMCMEPPI can significantly improve the control precision of heavy load MEFP.
基金supported by Beijing Natural Science Foundation(Grant number:2232060)the Ministry of Industry and Information Technology(Grant number:ZX20240310)National Natural Science Foundation of China(Grant numbers:52574016,52394250,52234002).
文摘The enhanced drilling parameters and custom-designed polycrystalline diamond compact(PDC)bits have greatly improved both rate of penetration(ROP)and footage.Then how to further improve the bit’s ROP and how to deal with the side effects caused by the enhanced drilling parameters remain a challenge.In this work,the single-cutter rock-cutting tests and full-sized bit drilling tests were conducted to investigate the effects of rock types,drilling parameters,and bit designs on ROP.The results showed that in the easy-to-drill formations,the enhanced drilling parameters had a more pronounced effect on improving the bit’s ROP than the optimizations of bit designs such as changing the cutter shape and size.On the other hand,in the hard-to-drill formations,smaller-sized and shaped PDC cutters combined with high-torque tools offered a promising approach to increase ROP.To further improve ROP and footage,two innovative approaches were introduced:improving the bit durability without compromising ROP to ensure one-trip drilling,and using extended directional nozzles together with enhanced hydraulic parameters.The bit durability was improved by optimizing the cutter shape and diamond materials,which helped complete the single-run footage of 2986 m in the field trial of Shengli Oilfield.It was also found that the extended directional nozzle was less effective under conventional hydraulic parameters,but increased the ROP by 32.1%under enhanced hydraulic parameters because of improving jet impact performance through reduced jet diffusion.The findings provided insights for ROP improvement in the oil and gas drilling operations.
文摘The Ohmically heated circular limiter tokamak ADITYA （R0 = 75 cm, a = 25 cm） has been upgraded to a tokamak named the ADITYA Upgrade （ADITYA-U） with an open divertor configuration with divertor plates. The main goal of ADITYA-U is to carry out dedicated experiments relevant for bigger fusion machines including ITER, such as the generation and control of runaway electrons, disruption prediction, and mitigation studies, along with an improvement in confinement with shaped plasma. The ADITYA tokamak was dismantled and the assembly of ADITYA-U was completed in March 2016. Integration of subsystems like data acquisition and remote operation along with plasma production and preliminary plasma characterization of ADITYA-U plasmas are presented in this paper.
文摘Image morphing is a powerful tool for visual effect. In this paper, a view interpolation algorithm is proposed to simulate a virtual walk along a street from start position to end position. To simulate a virtual walking view needs to create new appearing scene in the vision-vanishing point and disappearing scene beyond the scope of view. To attain these two aims we use two enhanced position parameters to match pixels of source images and target images. One enhanced position parameter is the angular coordinates of pixels. Another enhanced position parameter is the distances from pixels to the vision-vanishing point. According to the parameter values, pixels beyond the scope of view can be ＂moved＂ out in linear interpolation. Result demonstrates the validity of the algorithm. Another advantage of this algorithm is that the enhanced position parameters are based on real locations and walking distances, so it is also an approach to online virtual tour by satellite maps of virtual globe applications such as Google Earth.
文摘In this study,nine square concrete columns,including six CFRP/ECCs and three plain concrete control specimen columns,were prepared. The CFRP tubes with fibers oriented in the hoop direction were manufactured with 10,20,or 40 mm rounded corner radii at vertical edges. A 100 mm overlap in the direction of fibers was provided to ensure a proper bond. Uniaxial compression tests were conducted to investigate the compressive behaviors including the axial strength,stress-strain response,and ductility. It is evident that the CFRP tube confinement can improve the compressive behavior of concrete core,in terms of axial compressive strength or axial deformability. Based on the experimental results and some existing test database attained by other researchers,a design-oriented model is developed. The predictions of the model for CFRP/ECCs show good agreement with test results.
