The lack of research on flexible drilling tool leads to limited application of ultra-short radius horizontal wells.The flexible drilling tool is different from the conventional drilling tool.The flexible drilling pipe...The lack of research on flexible drilling tool leads to limited application of ultra-short radius horizontal wells.The flexible drilling tool is different from the conventional drilling tool.The flexible drilling pipe involves a mutual transition between the structure and the mechanism during the deformation process.At the same time,the flexible drilling pipe and the eccentric guide tube,the guide tube and the wellbore generate random contact.In this paper,3-D beam elements,universal joint elements,rigid beam elements and the beam-beam contact elements are combined to establish a two-layer contact nonlinear finite element model of the flexible drilling tool in the wellbore.The dynamic relaxation method is introduced for numerical solution.The feasibility of the model and the algorithm is verified by an example.The mechanical analysis of flexible drilling tool under the four hole inclinations in the oblique section is carried out.It is found that the flexible drilling pipe has a“folded line”deformation.The contact force between the flexible drilling pipe and the guide tube is randomly distributed.The contact force between the guide tube and the wellbore in the oblique section is greater than that in the vertical section.As the hole inclinations increase,the torque and axial force transmitted to the drill bit gradually decrease.展开更多
According to the concept of“flexible surge capacity,”hospitals may need to be evacuated on two occasions:(1)when they are exposed to danger,such as in war;and(2)when they are contaminated,such as during the Covid-19...According to the concept of“flexible surge capacity,”hospitals may need to be evacuated on two occasions:(1)when they are exposed to danger,such as in war;and(2)when they are contaminated,such as during the Covid-19 pandemic.In the former,the entire hospital must be evacuated,while in the latter,the hospital becomes a pandemic center necessitating the transfer of its non-contaminated staff,patients,and routine activities to other facilities.Such occasions involve several degrees of evacuation—partial or total—yet all require deliberate surge planning and collaboration with diverse authorities.This study aimed to investigate the extent of hospital evacuation preparedness in Thailand,using the main elements of the flexible surge capacity concept.A mixed method cross-sectional study was conducted using a hospital evacuation questionnaire from a previously published multinational hospital evacuation study.The tool contained questions regarding evacuation preparedness encompassing surge capacity and collaborative elements and an open-ended inquiry to grasp potential perspectives.All 143 secondary care,tertiary care,and university hospitals received the questionnaire;43 hospitals provided responses.The findings indicate glitches in evacuation protocols,particularly triage systems,the inadequacies of surge planning and multiagency collaboration,and knowledge limitations in community capabilities.In conclusion,the applications of the essential components of flexible surge capacity allow the assessment of hospital preparedness and facilitate the evaluation of guidelines and instructions through scenario-based training exercises.展开更多
Multi-point forming (MPF) is an advanced manufacturing technology for three-dimensional sheet metal parts. In this paper, the MPF integrated system is described that can form a variety of part shapes without the need ...Multi-point forming (MPF) is an advanced manufacturing technology for three-dimensional sheet metal parts. In this paper, the MPF integrated system is described that can form a variety of part shapes without the need for solid dies, and given only geometry and material information about the desired part. The central component of this system is a pair of matrices of punches, and the desired discrete die surface is constructed by changing the positions of punches though the CAD and control system. The basic MPF process is introduced and the typical application examples show the applicability of the MPF technology. Wrinkle and dimple are the major forming defects in MPF process, numerical simulation is a feasible way to predict forming defects in MPF. In conventional stamping, the mode to form sheet metal with blankholder is an effective way to suppress wrinkling; the same is true in MPF. A MPF press with flexible blankholder was developed, and the forming results indicated the forming stability of this technique. Based on the flexibility of MPF, varying deformation path MPF and sectional MPF were explored that cannot be realized in conventional stamping. By controlling each punch in real-time, a sheet part can be manufactured along a specific forming path. When the path of deformation in MPF is designed properly, forming defects will be avoided completely and lager deformation is achieved. A work piece can be formed section by section though the sectional MPF, and this technique makes it possible to manufacture large size parts in a small MPF press. Some critical experiments were performed that confirmed the validity of two special MPF techniques.展开更多
As more and more composite materials are used in lightweight vehicle white bodies,self-pierce riveting(SPR)technology has attracted great attention.However,the existing riveting tools still have the disadvantages of l...As more and more composite materials are used in lightweight vehicle white bodies,self-pierce riveting(SPR)technology has attracted great attention.However,the existing riveting tools still have the disadvantages of low efficiency and flexibility.To improve these disadvantages and the riveting qualification rate,this paper improves the control scheme of the existing riveting tools,and proposes a novel controller design approach of the flexible servo riveting system based on the RBF network and SPR process.Firstly,this paper briefly introduces the working principle and SPR procedure of the servo riveting tool.Then a moving component force analysis is performed,which lays the foundation for the motion control.Secondly,the riveting quality inspection rules of traditional riveting tools are used for reference to plan the force-displacement curve autonomously.To control this process,the riveting force is fed back into the closed-loop control of the riveting tool and the riveting speed is computed based on the admittance control algorithm.Then,this paper adopts the permanent magnet synchronous motor(PMSM)as the power of riveting tool,and proposes an integral sliding mode control approach based on the improved reaching law and the radial basis function(RBF)network friction compensation for the PMSM speed control.Finally,the proposed control approach is simulated by Matlab,and is applied to the servo riveting system designed by our laboratory.The simulation and riveting results show the feasibility of the designed controller.展开更多
基金support from the Natural Science Foundation of China(Grant numbers:51674088)supported by National Natural Science Foundation of China(Grant No.51674088).
文摘The lack of research on flexible drilling tool leads to limited application of ultra-short radius horizontal wells.The flexible drilling tool is different from the conventional drilling tool.The flexible drilling pipe involves a mutual transition between the structure and the mechanism during the deformation process.At the same time,the flexible drilling pipe and the eccentric guide tube,the guide tube and the wellbore generate random contact.In this paper,3-D beam elements,universal joint elements,rigid beam elements and the beam-beam contact elements are combined to establish a two-layer contact nonlinear finite element model of the flexible drilling tool in the wellbore.The dynamic relaxation method is introduced for numerical solution.The feasibility of the model and the algorithm is verified by an example.The mechanical analysis of flexible drilling tool under the four hole inclinations in the oblique section is carried out.It is found that the flexible drilling pipe has a“folded line”deformation.The contact force between the flexible drilling pipe and the guide tube is randomly distributed.The contact force between the guide tube and the wellbore in the oblique section is greater than that in the vertical section.As the hole inclinations increase,the torque and axial force transmitted to the drill bit gradually decrease.
文摘According to the concept of“flexible surge capacity,”hospitals may need to be evacuated on two occasions:(1)when they are exposed to danger,such as in war;and(2)when they are contaminated,such as during the Covid-19 pandemic.In the former,the entire hospital must be evacuated,while in the latter,the hospital becomes a pandemic center necessitating the transfer of its non-contaminated staff,patients,and routine activities to other facilities.Such occasions involve several degrees of evacuation—partial or total—yet all require deliberate surge planning and collaboration with diverse authorities.This study aimed to investigate the extent of hospital evacuation preparedness in Thailand,using the main elements of the flexible surge capacity concept.A mixed method cross-sectional study was conducted using a hospital evacuation questionnaire from a previously published multinational hospital evacuation study.The tool contained questions regarding evacuation preparedness encompassing surge capacity and collaborative elements and an open-ended inquiry to grasp potential perspectives.All 143 secondary care,tertiary care,and university hospitals received the questionnaire;43 hospitals provided responses.The findings indicate glitches in evacuation protocols,particularly triage systems,the inadequacies of surge planning and multiagency collaboration,and knowledge limitations in community capabilities.In conclusion,the applications of the essential components of flexible surge capacity allow the assessment of hospital preparedness and facilitate the evaluation of guidelines and instructions through scenario-based training exercises.
文摘Multi-point forming (MPF) is an advanced manufacturing technology for three-dimensional sheet metal parts. In this paper, the MPF integrated system is described that can form a variety of part shapes without the need for solid dies, and given only geometry and material information about the desired part. The central component of this system is a pair of matrices of punches, and the desired discrete die surface is constructed by changing the positions of punches though the CAD and control system. The basic MPF process is introduced and the typical application examples show the applicability of the MPF technology. Wrinkle and dimple are the major forming defects in MPF process, numerical simulation is a feasible way to predict forming defects in MPF. In conventional stamping, the mode to form sheet metal with blankholder is an effective way to suppress wrinkling; the same is true in MPF. A MPF press with flexible blankholder was developed, and the forming results indicated the forming stability of this technique. Based on the flexibility of MPF, varying deformation path MPF and sectional MPF were explored that cannot be realized in conventional stamping. By controlling each punch in real-time, a sheet part can be manufactured along a specific forming path. When the path of deformation in MPF is designed properly, forming defects will be avoided completely and lager deformation is achieved. A work piece can be formed section by section though the sectional MPF, and this technique makes it possible to manufacture large size parts in a small MPF press. Some critical experiments were performed that confirmed the validity of two special MPF techniques.
基金The authors gratefully thank the research funding by the National Key Research and Development Plan of China(Grant No.2017YFB1303503)the research supported by the Key Research and Development Program of Shandong Province(Grant No.2019JZZY010441)+1 种基金the National Natural Science Foundation of China(Grant No.62103234)the project supported by the Natural Science Foundation of Shandong Province(Grant No.ZR2021QF027).
文摘As more and more composite materials are used in lightweight vehicle white bodies,self-pierce riveting(SPR)technology has attracted great attention.However,the existing riveting tools still have the disadvantages of low efficiency and flexibility.To improve these disadvantages and the riveting qualification rate,this paper improves the control scheme of the existing riveting tools,and proposes a novel controller design approach of the flexible servo riveting system based on the RBF network and SPR process.Firstly,this paper briefly introduces the working principle and SPR procedure of the servo riveting tool.Then a moving component force analysis is performed,which lays the foundation for the motion control.Secondly,the riveting quality inspection rules of traditional riveting tools are used for reference to plan the force-displacement curve autonomously.To control this process,the riveting force is fed back into the closed-loop control of the riveting tool and the riveting speed is computed based on the admittance control algorithm.Then,this paper adopts the permanent magnet synchronous motor(PMSM)as the power of riveting tool,and proposes an integral sliding mode control approach based on the improved reaching law and the radial basis function(RBF)network friction compensation for the PMSM speed control.Finally,the proposed control approach is simulated by Matlab,and is applied to the servo riveting system designed by our laboratory.The simulation and riveting results show the feasibility of the designed controller.
