This study explores asymptotically flat wormhole solutions within the framework of f(R,T)gravity.We analyze f(R,T)expressed as f(R,T)=R+λT+λ_(1)T^(2).A linear equation of state(EoS)is employed for both radial and la...This study explores asymptotically flat wormhole solutions within the framework of f(R,T)gravity.We analyze f(R,T)expressed as f(R,T)=R+λT+λ_(1)T^(2).A linear equation of state(EoS)is employed for both radial and lateral pressures,resulting in a power-law shape function.The investigation encompasses solutions characterized by both negative and positive energy densities.It has been determined that solutions with positive energy density comply with all energy conditions,specifically the null,weak,strong,and dominant energy conditions.Additionally,we identify constraints on the parametersλ,λ_(1),and the parameters associated with the EoS and shape function.展开更多
文摘随着卫星技术的发展与成熟,星间链路(Inter-satellite Link,ISL)在导航卫星、通讯卫星等卫星星座中得到了广泛的应用,以此实现高效的星间通讯和测量.由于星间链路的建立或维持会受到日凌的影响,因此在卫星星座的设计、规划中往往需要对不同卫星、不同链路所受日凌的影响进行计算和预测,评估星间链路、系统服务受日凌的影响,更好地规划、设计相关业务.当前无论是利用成熟卫星系统设计工具搭建场景还是相关单位内部自研仿真系统,通常会基于外推星历逐个历元判断链路与太阳视线方向夹角,以此来判断和预测日凌.这一方式简单、直观、方便实现,但缺点是计算效率低下.虽然设计阶段的日凌计算并不需要十分准确的星历,通常基于二体模型外推卫星星历即可,但如果需要准确判断日凌可能发生的次数、时间、时长,那么往往要求卫星星历时间间隔很短,否则有可能错过持续时间不长的日凌,影响评估效果.针对日凌的判断和计算提出了一种快速算法.通过构造日凌发生、结束时刻卫星纬度辐角u满足的方程,解析判断日凌是否可能发生,计算日凌始末的卫星纬度辐角,快速实现对星间链路日凌存在性以及日凌始末时刻的计算.这一算法也需要事先外推星历,但星历步长只要不超过1个轨道周期即可.计算表明,该算法可以在稳定检测到比传统方法更多日凌的情况下将计算时间减少2~3个量级.即使外推星历的步长接近1个轨道周期,该方法也可以检测到超过99.9%的日凌弧段,且计算结果高度稳定,日凌发生时刻和持续时长偏差最大也不超过1 s.
文摘This study explores asymptotically flat wormhole solutions within the framework of f(R,T)gravity.We analyze f(R,T)expressed as f(R,T)=R+λT+λ_(1)T^(2).A linear equation of state(EoS)is employed for both radial and lateral pressures,resulting in a power-law shape function.The investigation encompasses solutions characterized by both negative and positive energy densities.It has been determined that solutions with positive energy density comply with all energy conditions,specifically the null,weak,strong,and dominant energy conditions.Additionally,we identify constraints on the parametersλ,λ_(1),and the parameters associated with the EoS and shape function.
