Using application level multicast can partly pad the lack of IP multicast deployment. To perform single-source applications in hierarchical topology, we propose an application level multicast approach, Hierarchical To...Using application level multicast can partly pad the lack of IP multicast deployment. To perform single-source applications in hierarchical topology, we propose an application level multicast approach, Hierarchical Topology Aware Grouping (HTAG), which exploits information about path overlap among members and topological hierarchy to construct overlay tree at different network layers. We present simulations of both our protocol and the TAG over generated hierarchical topologies. The results indicate the effectiveness of our approach in reducing duplicate packets and preserving available bandwidth, with reasonable delays increase.展开更多
We examined stable isotope signals of precipitation, soil water, and xylem water and ran the multi-source linear mixing model （IsoSource） to determine water uptake depths and estimate proportional contribution of po...We examined stable isotope signals of precipitation, soil water, and xylem water and ran the multi-source linear mixing model （IsoSource） to determine water uptake depths and estimate proportional contribution of possible water pools to the water use of Mongolian pine （Pinus sylvestris var. mongolica） plantation in southeast Horqin Sandy Land. We also examined variations of the water use by Mongolian pine trees before and after a heavy precipitation event. The closeness of isotopic composition between xylem water and potential water pools presented that most of water uptake by the trees occurred in the depth of below 20 cm soil （up to 80 cm in this study）. Estimate from the IsoSource model agrees well with observation, and the model yielded that over 60% of the water was derived from 20–80 cm soil layer under relatively higher soil moisture conditions, contribution from much deeper soil depth may increase when the soil in this layer became dry. The contribution from the groundwater was very low since water table was much deeper than rooting depth of the trees. Isotopic signals of xylem water of Mongolian pine trees before and after a heavy precipitation of 14.4 mm on July 13 in 2009 exhibited that the trees could sense and use recent rain-charged soil water at the upper 20 cm soil layer 36 hours after the rain, and this contribution decreased rapidly in the following 24 hours. The ability of accessing different water pools of Mongolian pine trees under various soil moisture conditions is likely a good indicator of their adaptability to dry habitats in sandy lands.展开更多
文摘Using application level multicast can partly pad the lack of IP multicast deployment. To perform single-source applications in hierarchical topology, we propose an application level multicast approach, Hierarchical Topology Aware Grouping (HTAG), which exploits information about path overlap among members and topological hierarchy to construct overlay tree at different network layers. We present simulations of both our protocol and the TAG over generated hierarchical topologies. The results indicate the effectiveness of our approach in reducing duplicate packets and preserving available bandwidth, with reasonable delays increase.
基金the National Science Foundation of China (30770339)
文摘We examined stable isotope signals of precipitation, soil water, and xylem water and ran the multi-source linear mixing model （IsoSource） to determine water uptake depths and estimate proportional contribution of possible water pools to the water use of Mongolian pine （Pinus sylvestris var. mongolica） plantation in southeast Horqin Sandy Land. We also examined variations of the water use by Mongolian pine trees before and after a heavy precipitation event. The closeness of isotopic composition between xylem water and potential water pools presented that most of water uptake by the trees occurred in the depth of below 20 cm soil （up to 80 cm in this study）. Estimate from the IsoSource model agrees well with observation, and the model yielded that over 60% of the water was derived from 20–80 cm soil layer under relatively higher soil moisture conditions, contribution from much deeper soil depth may increase when the soil in this layer became dry. The contribution from the groundwater was very low since water table was much deeper than rooting depth of the trees. Isotopic signals of xylem water of Mongolian pine trees before and after a heavy precipitation of 14.4 mm on July 13 in 2009 exhibited that the trees could sense and use recent rain-charged soil water at the upper 20 cm soil layer 36 hours after the rain, and this contribution decreased rapidly in the following 24 hours. The ability of accessing different water pools of Mongolian pine trees under various soil moisture conditions is likely a good indicator of their adaptability to dry habitats in sandy lands.
