以中继卫星(Racking and Data Relay Satellite,TDRS)为研究对象,以有色Petri网(Colored Petri Net,CPN)为数学工具,根据自顶向下的原则和层次化建模思想,提出一种基于CPN的TDRS操作规划模型,该模型分为顶层模型、控制模型、前向链路数...以中继卫星(Racking and Data Relay Satellite,TDRS)为研究对象,以有色Petri网(Colored Petri Net,CPN)为数学工具,根据自顶向下的原则和层次化建模思想,提出一种基于CPN的TDRS操作规划模型,该模型分为顶层模型、控制模型、前向链路数据接收任务与发送任务的操作规划模型和返向链路数据接收任务与发送任务的操作规划模型,有效地描述了TDRS的动态行为特性。最后,通过仿真实验得到了TDRS操作规划方案,验证了所建模型的有效性。与PDDL模型比较分析表明:所建模型可以有效引入TDRS的领域知识,能够有效提高求解效率。所建模型可以为TDRS操作规划方案的制定提供理论参考。展开更多
Fallout volcanic deposits of SommaVesuvius(Campania,southern Italy),characterized by the presence of layers with contrasting textural and hydraulic properties,are frequently affected by shallow landslides during rainw...Fallout volcanic deposits of SommaVesuvius(Campania,southern Italy),characterized by the presence of layers with contrasting textural and hydraulic properties,are frequently affected by shallow landslides during rainwater infiltration.The soils of the stratigraphic sequence present intraparticle pores,originated by the gases escaped during magma decompression in the volcanic conduit,thus are characterized by double porosity(i.e.,intraparticle and interparticle pores),which is expected to affect their hydraulic behaviour,and to play a key role in rainwater infiltration through layered deposits.To understand the effect of double porosity on the hydraulic behaviour of the involved soils,controlled experiments have been carried out in an infiltration column.The experimental apparatus is provided with newly designed non-invasive Time Domain Reflectometry(TDR)probes,not buried in the investigated soil layers so as to minimize disturbance to the flow,allowing water content measurement during vertical flow processes.Specifically,transient flow experiments are carried out through reconstituted specimens of black scoriae and grey pumices,both loose pyroclastic granular soils from fallout deposits of Somma-Vesuvius,featuring double porosity with different pore size distributions,that were estimated by X-ray tomography and Mercury Intrusion Porosimetry.The experimental results highlight the effects of the double porosity and clearly indicate the different behaviour of the two soils during wetting and drying processes,mainly related to the different dimensions of intraparticle pores.展开更多
文摘以中继卫星(Racking and Data Relay Satellite,TDRS)为研究对象,以有色Petri网(Colored Petri Net,CPN)为数学工具,根据自顶向下的原则和层次化建模思想,提出一种基于CPN的TDRS操作规划模型,该模型分为顶层模型、控制模型、前向链路数据接收任务与发送任务的操作规划模型和返向链路数据接收任务与发送任务的操作规划模型,有效地描述了TDRS的动态行为特性。最后,通过仿真实验得到了TDRS操作规划方案,验证了所建模型的有效性。与PDDL模型比较分析表明:所建模型可以有效引入TDRS的领域知识,能够有效提高求解效率。所建模型可以为TDRS操作规划方案的制定提供理论参考。
文摘Fallout volcanic deposits of SommaVesuvius(Campania,southern Italy),characterized by the presence of layers with contrasting textural and hydraulic properties,are frequently affected by shallow landslides during rainwater infiltration.The soils of the stratigraphic sequence present intraparticle pores,originated by the gases escaped during magma decompression in the volcanic conduit,thus are characterized by double porosity(i.e.,intraparticle and interparticle pores),which is expected to affect their hydraulic behaviour,and to play a key role in rainwater infiltration through layered deposits.To understand the effect of double porosity on the hydraulic behaviour of the involved soils,controlled experiments have been carried out in an infiltration column.The experimental apparatus is provided with newly designed non-invasive Time Domain Reflectometry(TDR)probes,not buried in the investigated soil layers so as to minimize disturbance to the flow,allowing water content measurement during vertical flow processes.Specifically,transient flow experiments are carried out through reconstituted specimens of black scoriae and grey pumices,both loose pyroclastic granular soils from fallout deposits of Somma-Vesuvius,featuring double porosity with different pore size distributions,that were estimated by X-ray tomography and Mercury Intrusion Porosimetry.The experimental results highlight the effects of the double porosity and clearly indicate the different behaviour of the two soils during wetting and drying processes,mainly related to the different dimensions of intraparticle pores.
