Conflict Detection and Resolution（CD＆R） is the key to ensure aviation safety based on Trajectory Prediction（TP）. Uncertainties that affect aircraft motions cause difficulty in an accurate prediction of the trajec...Conflict Detection and Resolution（CD＆R） is the key to ensure aviation safety based on Trajectory Prediction（TP）. Uncertainties that affect aircraft motions cause difficulty in an accurate prediction of the trajectory, especially in the context of four-dimensional（4D） Trajectory-Based Operation（4DTBO）, which brings the uncertainty of pilot intent. This study draws on the idea of time geography, and turns the research focus of CD＆R from TP to an analysis of the aircraft reachable space constrained by 4D waypoint constraints. The concepts of space–time reachability of aircraft and space–time potential conflict space are proposed. A novel pre-CD＆R scheme for multiple aircraft is established. A key advantage of the scheme is that the uncertainty of pilot intent is accounted for via a Space-Time Prism（STP） for aircraft. Conflict detection is performed by verifying whether the STPs of aircraft intersect or not, and conflict resolution is performed by planning a conflict-free space–time trajectory avoiding intersection. Numerical examples are presented to validate the efficiency of the proposed scheme.展开更多
As the child-friendly concept was enshrined in China's 14th Five-Year Plan,the construction of child-friendly spaces has emerged as a key issue.Nevertheless,current research and practices mainly focus on urban env...As the child-friendly concept was enshrined in China's 14th Five-Year Plan,the construction of child-friendly spaces has emerged as a key issue.Nevertheless,current research and practices mainly focus on urban environment,with rural areas receiving comparatively less attention.Therefore,this paper employs the contextual analysis method in new time geography to examine 208 daily activity logs from children aged 4 to 15 in rural areas of southern Shaanxi Province,uncovering their behavior and activity patterns by investigating daily,geographical,social,and emotional contexts.Specifically,the observed children tend to exhibit space-time unpredictability and limited diversity.The inadequate outdoor activity spaces makes children's activities typically center around their homes,with a relatively limited travel range.The dispersed layout of schools leads to an increase in the distance children have to travel to attend school.Additionally,they have a relatively simple and insular social circle,with activity peers often confined to family members or a fixed circle of friends.Despite their strong desire for cultural and sports activities,they exhibit negative emotions towards school commutes.The paper further explores what affects rural children's behavioral activities from the perspectives of capacity constraints,coupling constraints,and authority constraints.Accordingly,this study proposes suggestions for planning and construction of child-friendly spaces in rural areas.展开更多
基金financial support from the Civil Aviation Joint Funds of the National Natural Science Foundation of China (No’s.U1533203,61179069)
文摘Conflict Detection and Resolution（CD＆R） is the key to ensure aviation safety based on Trajectory Prediction（TP）. Uncertainties that affect aircraft motions cause difficulty in an accurate prediction of the trajectory, especially in the context of four-dimensional（4D） Trajectory-Based Operation（4DTBO）, which brings the uncertainty of pilot intent. This study draws on the idea of time geography, and turns the research focus of CD＆R from TP to an analysis of the aircraft reachable space constrained by 4D waypoint constraints. The concepts of space–time reachability of aircraft and space–time potential conflict space are proposed. A novel pre-CD＆R scheme for multiple aircraft is established. A key advantage of the scheme is that the uncertainty of pilot intent is accounted for via a Space-Time Prism（STP） for aircraft. Conflict detection is performed by verifying whether the STPs of aircraft intersect or not, and conflict resolution is performed by planning a conflict-free space–time trajectory avoiding intersection. Numerical examples are presented to validate the efficiency of the proposed scheme.
基金funded by the National Key R&D Program of China During the 14~(th)Five-Year Plan Period(No.2022YFC3802801)the General Program of National Natural Science Foundation of China(No.52178056)+1 种基金the Shaanxi Province Innovation Capability Support Program–Soft Science General Project(No:2024ZC-YBXM-197)the General Program of Natural Science Basic Research Plan in Shaanxi Province(No.2022JM-290)。
文摘As the child-friendly concept was enshrined in China's 14th Five-Year Plan,the construction of child-friendly spaces has emerged as a key issue.Nevertheless,current research and practices mainly focus on urban environment,with rural areas receiving comparatively less attention.Therefore,this paper employs the contextual analysis method in new time geography to examine 208 daily activity logs from children aged 4 to 15 in rural areas of southern Shaanxi Province,uncovering their behavior and activity patterns by investigating daily,geographical,social,and emotional contexts.Specifically,the observed children tend to exhibit space-time unpredictability and limited diversity.The inadequate outdoor activity spaces makes children's activities typically center around their homes,with a relatively limited travel range.The dispersed layout of schools leads to an increase in the distance children have to travel to attend school.Additionally,they have a relatively simple and insular social circle,with activity peers often confined to family members or a fixed circle of friends.Despite their strong desire for cultural and sports activities,they exhibit negative emotions towards school commutes.The paper further explores what affects rural children's behavioral activities from the perspectives of capacity constraints,coupling constraints,and authority constraints.Accordingly,this study proposes suggestions for planning and construction of child-friendly spaces in rural areas.
