基于湍流散射理论,运用边界层风廓线雷达(WPR)联合RASS(Radio Acoustic Sounding System),GPS/PWV(Global Position System/Precipitable Water Vapor)进行全遥感系统的大气比湿廓线反演试验,并对影响因子进行分析。利用2011年8—9月云...基于湍流散射理论,运用边界层风廓线雷达(WPR)联合RASS(Radio Acoustic Sounding System),GPS/PWV(Global Position System/Precipitable Water Vapor)进行全遥感系统的大气比湿廓线反演试验,并对影响因子进行分析。利用2011年8—9月云南大理综合探测试验数据的反演结果与探空数据进行比较分析,结果表明:WPR联合探空的温度廓线和起始边界比湿(q_0)反演大气比湿廓线,与探空大气比湿廓线相比具有相同的变化趋势,标准差为0.84 g·kg^(-1),误差随高度增加呈递增趋势;WPR联合RASS,GPS/PWV数据反演大气比湿廓线,与探空大气比湿廓线的标准差为0.85 g·kg^(-1)。参加反演的数据中,折射指数结构常数C_n^2与谱宽σ_(turb)~2对反演影响最大,反演算法中大气折射指数梯度M符号的判断对反演精度也有较大影响。展开更多
Based on non-Darcian flow law described by exponent and threshold gradient within a double-layered soil, the classic theory of one-dimensional consolidation of double-layered soil was modified to consider the change o...Based on non-Darcian flow law described by exponent and threshold gradient within a double-layered soil, the classic theory of one-dimensional consolidation of double-layered soil was modified to consider the change of vertical total stress with depth and time together. Because of the complexity of governing equations, the numerical solutions were obtained in detail by finite difference method. Then, the numerical solutions were compared with the analytical solutions in condition that non-Darcian flow law was degenerated to Dary's law, and the comparison results show that numerical solutions are reliable. Finally, consolidation behavior of double-layered soil with different parameters was analyzed, and the results show that the consolidation rate of double-layered soil decreases with increasing the value of exponent and threshold of non-Darcian flow, and the exponent and threshold gradient of the first soil layer greatly influence the consolidation rate of double-layered soil. The larger the ratio of the equivalent water head of external load to the total thickness of double-layered soil, the larger the rate of the consolidation, and the similitude relationship in classical consolidation theory of double-layered soil is not satisfied. The other consolidation behavior of double-layered soil with non-Darcian flow is the same as that with Darcy's law.展开更多
文摘基于湍流散射理论,运用边界层风廓线雷达(WPR)联合RASS(Radio Acoustic Sounding System),GPS/PWV(Global Position System/Precipitable Water Vapor)进行全遥感系统的大气比湿廓线反演试验,并对影响因子进行分析。利用2011年8—9月云南大理综合探测试验数据的反演结果与探空数据进行比较分析,结果表明:WPR联合探空的温度廓线和起始边界比湿(q_0)反演大气比湿廓线,与探空大气比湿廓线相比具有相同的变化趋势,标准差为0.84 g·kg^(-1),误差随高度增加呈递增趋势;WPR联合RASS,GPS/PWV数据反演大气比湿廓线,与探空大气比湿廓线的标准差为0.85 g·kg^(-1)。参加反演的数据中,折射指数结构常数C_n^2与谱宽σ_(turb)~2对反演影响最大,反演算法中大气折射指数梯度M符号的判断对反演精度也有较大影响。
文摘为研究Eclipse治疗计划系统中正常组织目标(Normal Tissue Objective, NTO)优化工具参数,对脊柱转移瘤立体定向放射治疗计划靶区覆盖剂量和靶区外剂量跌落梯度指数(Gradiet Index, GI)的影响,本研究对10例脊柱转移瘤立体定向放射治疗患者设计两种类型计划。第1种添加NTO优化工具但不添加环优化条件,共得到360个计划,为参考计划;第2种添加环优化条件但不添加NTO优化条件,总共10个计划,为标准计划。所有计划最后剂量归一为100%处方剂量覆盖90%靶区体积。比较两种类型计划的靶区剂量适形度指数(Conformity Index, CI)、靶区外剂量跌落梯度指数、靶区最大剂量(Dmax)、实际治疗时间和计划临床合格率。结果表明,当NTO优化工具参数Fall-off为0.5或者1,Priority为500、700和999时,计划的GI值相似(P>0.05),但是小于其他Fall-off和Priority的GI值(P<0.05);Fall-off和Priority对CI值大小和实际治疗时间没有影响(P>0.05);随着Priority增加,计划靶区体积(Planning Target Volume, PTV)Dmax增加(P<0.05)。参考计划的临床合格率最高为70%。与标准计划相比,最合适NTO优化工具参数计划(Priority、Fall-off分别为500和0.5)的GI值更低(3.449 vs 3.655,P=0.000,Z=-5.534),实际治疗时间没有差异(2.65 min vs 2.32 min,P=0.063,Z=0.832),PTV Dmax偏大(132.1%vs 128.8%,P=0.002,Z=4.214),CI偏大(0.911 vs 0.879,P=0.151,Z=0.984)。综上所述,在计划可通过情况下,当NTO优化工具中参数Distance from Target Border设置为0.2 cm, Start Dose设置为91%处方剂量,End Dose设置为49.4%处方剂量,Fall-off和Priority分别设置为0.5和500时,脊柱转移瘤立体定向放疗计划能够实现较好的靶区剂量适形度、更低的剂量梯度指数以及合适的治疗时间。
基金Projects(50878191,51109092)supported by the National Natural Science Foundation of China
文摘Based on non-Darcian flow law described by exponent and threshold gradient within a double-layered soil, the classic theory of one-dimensional consolidation of double-layered soil was modified to consider the change of vertical total stress with depth and time together. Because of the complexity of governing equations, the numerical solutions were obtained in detail by finite difference method. Then, the numerical solutions were compared with the analytical solutions in condition that non-Darcian flow law was degenerated to Dary's law, and the comparison results show that numerical solutions are reliable. Finally, consolidation behavior of double-layered soil with different parameters was analyzed, and the results show that the consolidation rate of double-layered soil decreases with increasing the value of exponent and threshold of non-Darcian flow, and the exponent and threshold gradient of the first soil layer greatly influence the consolidation rate of double-layered soil. The larger the ratio of the equivalent water head of external load to the total thickness of double-layered soil, the larger the rate of the consolidation, and the similitude relationship in classical consolidation theory of double-layered soil is not satisfied. The other consolidation behavior of double-layered soil with non-Darcian flow is the same as that with Darcy's law.
