The pulse features of a bubble have a close connection with the boundary condition. When a bubble moves near a rigid wall, it will be attracted by the Bjerknes force of the wall, and a jet pointing at the wall will be...The pulse features of a bubble have a close connection with the boundary condition. When a bubble moves near a rigid wall, it will be attracted by the Bjerknes force of the wall, and a jet pointing at the wall will be generated. In real application, the bubble may move under the combined action of walls in different directions when it forms at the corner of a pipe or at the bottom of a dam. The motion of the bubble shows complex and nonlinear characteristics under these conditions. In order to investigate the bubble pulse features near complex walls, a horizontal wall and a vertical wall are put into the experimental water tank synchronously, and an electric circuit with 200 voltages is designed to generate discharge bubbles, and then experimental study on the bubble pulse features under the combined action of horizontal and vertical walls is carried out. The influences of the combined action of two walls on the bubble shape, pulse period, moving trace and inside jet are obtained by changing the distances from bubble center to the two walls. It aims at providing references for the relevant theoretical and numerical research.展开更多
The long and large diameter uncharged hole boring(LLB)method is a cut blasting method that minimizes blast-induced vibrations by creating long and large diameter uncharged holes at the excavation face of tunnels prior...The long and large diameter uncharged hole boring(LLB)method is a cut blasting method that minimizes blast-induced vibrations by creating long and large diameter uncharged holes at the excavation face of tunnels prior to tunnel excavation.Drilling in this method typically uses a 50 m long with a 382 mm diameter hammer bit in the horizontal direction at the tunnel face.However,the significant weight and uni-directional rotation of the rod head,as well as variables such as geological characteristics,machine conditions,and inexperienced operators result in significant deviation from the target borehole alignment that hinders the vibration-dampening effect of the uncharged holes.Furthermore,since there is no method to verify the alignment of the boreholes until main tunnel construction,borehole misalignment is often not discovered until weeks after construction,which requires tunnel construction to cease until the equipment can be remobilized and an additional borehole be created,causing significant delays and increased costs for the entire tunnel project.In this study,the borehole alignment tracking and ground exploration system(BGS)is developed to predict and monitor the quality and alignment of boreholes for cut blasting methods such as the LLB methods immediately after boring.The BGS was subsequently tested at a subway construction site to evaluate its performance in the field.The measurements yielded by the BGS were compared with manually measured boring positions at every 5 m along the borehole.Although the BGS showed a maximum deviation of approximately 12%at a local point where the hole surface was relatively rough,the accuracy for the final boring position was approximately 97%,demonstrating excellent precision of the alignment tracking system.The BGS demonstrates excellent performance in predicting ground conditions and the boring quality of a cut hole immediately after drilling,and shows promise in various other applications for monitoring borehole alignment.展开更多
Under study is the optimization problem of line structure (primarily railroad) routing. The improved mathematical models and algorithms of vertical alignment by set versions of the route plan are offered. The problem ...Under study is the optimization problem of line structure (primarily railroad) routing. The improved mathematical models and algorithms of vertical alignment by set versions of the route plan are offered. The problem is solved in some stages in interrelation with other design problems. The original algorithm of descent is given for solving the arising problem of nonlinear programming. Structural features of constraints are used and so it is not required to solve any systems of linear equations.展开更多
Roadways in Wyoming are characterized by challenging horizontal profiles,vertical profiles,a combination of the two and adverse weather conditions,all of which affect vehicle stability.In this study,we investigated th...Roadways in Wyoming are characterized by challenging horizontal profiles,vertical profiles,a combination of the two and adverse weather conditions,all of which affect vehicle stability.In this study,we investigated the impact of different operating speeds when negotiating combined horizontal and vertical curves under unfavorable environmental conditions on Wyoming’s interstates via vehicle dynamics simulation software.The simulation tools provided the acting forces on each tire of the vehicle and the side friction(skidding)margins.This allowed for examining the interaction between vehicle dynamics and road geometry in such alignments.Also,linear regression analysis was implemented to investigate the skidding margins based on the simulation results to demonstrate when a vehicle is more likely to deviate from its desired trajectory.Specifically,this examines the contributing factors that significantly influence the skidding margins.The results indicated that:1)the skidding margins are dramatically decreased by adverse weather conditions even with lower degree of curvature and gradient values of combined curves and more particularly at higher operating speeds conditions.Increasing the vehicle speed on the curve by 10%,the skidding margin dropped by 15%.2)Compared to heavy trucks and sports utility vehicles(SUVs),passenger cars require the highest side friction demand.3)The effect of applying brakes on vehicle stability depends on the road surface condition;applying the brakes on snowy road surfaces increases the potential of vehicle skidding especially for heavy trucks.This study assessed the curve speed limits and showed how important to assign safe and appropriate limits speed since the skidding likelihood is significantly sensitive to the vehicle speeds.This study is beneficial to Wyoming’s roadway agencies since hazardous sections having combined horizontal and vertical curves are identified.Also,critical situations that require additional attention from law enforcement agencies are pinpointed.Finally,recommendations that are valuable to roadway agencies are made based on this study’s findings.展开更多
基金financially supported by the China National Funds for Distinguished Young Scholars(Grant No.51222904)the National Natural Science Foundation of China(Grant No.51379039)
文摘The pulse features of a bubble have a close connection with the boundary condition. When a bubble moves near a rigid wall, it will be attracted by the Bjerknes force of the wall, and a jet pointing at the wall will be generated. In real application, the bubble may move under the combined action of walls in different directions when it forms at the corner of a pipe or at the bottom of a dam. The motion of the bubble shows complex and nonlinear characteristics under these conditions. In order to investigate the bubble pulse features near complex walls, a horizontal wall and a vertical wall are put into the experimental water tank synchronously, and an electric circuit with 200 voltages is designed to generate discharge bubbles, and then experimental study on the bubble pulse features under the combined action of horizontal and vertical walls is carried out. The influences of the combined action of two walls on the bubble shape, pulse period, moving trace and inside jet are obtained by changing the distances from bubble center to the two walls. It aims at providing references for the relevant theoretical and numerical research.
基金supported by the Korea Agency for Infrastructure Technology Advancement(KAIA)grant funded by the Ministry of Land,Infrastructure,and Transport,South Korea(Grant No.22UUTI-C157786-03).
文摘The long and large diameter uncharged hole boring(LLB)method is a cut blasting method that minimizes blast-induced vibrations by creating long and large diameter uncharged holes at the excavation face of tunnels prior to tunnel excavation.Drilling in this method typically uses a 50 m long with a 382 mm diameter hammer bit in the horizontal direction at the tunnel face.However,the significant weight and uni-directional rotation of the rod head,as well as variables such as geological characteristics,machine conditions,and inexperienced operators result in significant deviation from the target borehole alignment that hinders the vibration-dampening effect of the uncharged holes.Furthermore,since there is no method to verify the alignment of the boreholes until main tunnel construction,borehole misalignment is often not discovered until weeks after construction,which requires tunnel construction to cease until the equipment can be remobilized and an additional borehole be created,causing significant delays and increased costs for the entire tunnel project.In this study,the borehole alignment tracking and ground exploration system(BGS)is developed to predict and monitor the quality and alignment of boreholes for cut blasting methods such as the LLB methods immediately after boring.The BGS was subsequently tested at a subway construction site to evaluate its performance in the field.The measurements yielded by the BGS were compared with manually measured boring positions at every 5 m along the borehole.Although the BGS showed a maximum deviation of approximately 12%at a local point where the hole surface was relatively rough,the accuracy for the final boring position was approximately 97%,demonstrating excellent precision of the alignment tracking system.The BGS demonstrates excellent performance in predicting ground conditions and the boring quality of a cut hole immediately after drilling,and shows promise in various other applications for monitoring borehole alignment.
文摘Under study is the optimization problem of line structure (primarily railroad) routing. The improved mathematical models and algorithms of vertical alignment by set versions of the route plan are offered. The problem is solved in some stages in interrelation with other design problems. The original algorithm of descent is given for solving the arising problem of nonlinear programming. Structural features of constraints are used and so it is not required to solve any systems of linear equations.
基金the generous financial support of the Wyoming Department of Transportation (WYDOT)Mountain-Plains Consortium (MPC) (Grant number: 69A3551747108 (FAST Act)) for this study
文摘Roadways in Wyoming are characterized by challenging horizontal profiles,vertical profiles,a combination of the two and adverse weather conditions,all of which affect vehicle stability.In this study,we investigated the impact of different operating speeds when negotiating combined horizontal and vertical curves under unfavorable environmental conditions on Wyoming’s interstates via vehicle dynamics simulation software.The simulation tools provided the acting forces on each tire of the vehicle and the side friction(skidding)margins.This allowed for examining the interaction between vehicle dynamics and road geometry in such alignments.Also,linear regression analysis was implemented to investigate the skidding margins based on the simulation results to demonstrate when a vehicle is more likely to deviate from its desired trajectory.Specifically,this examines the contributing factors that significantly influence the skidding margins.The results indicated that:1)the skidding margins are dramatically decreased by adverse weather conditions even with lower degree of curvature and gradient values of combined curves and more particularly at higher operating speeds conditions.Increasing the vehicle speed on the curve by 10%,the skidding margin dropped by 15%.2)Compared to heavy trucks and sports utility vehicles(SUVs),passenger cars require the highest side friction demand.3)The effect of applying brakes on vehicle stability depends on the road surface condition;applying the brakes on snowy road surfaces increases the potential of vehicle skidding especially for heavy trucks.This study assessed the curve speed limits and showed how important to assign safe and appropriate limits speed since the skidding likelihood is significantly sensitive to the vehicle speeds.This study is beneficial to Wyoming’s roadway agencies since hazardous sections having combined horizontal and vertical curves are identified.Also,critical situations that require additional attention from law enforcement agencies are pinpointed.Finally,recommendations that are valuable to roadway agencies are made based on this study’s findings.
