This paper presents an efficient parallel algorithm for the shortest-path problem in interval graph for computing shortest-paths in a weighted interval graph that runs in O(n) time with n intervals in a graph. A linea...This paper presents an efficient parallel algorithm for the shortest-path problem in interval graph for computing shortest-paths in a weighted interval graph that runs in O(n) time with n intervals in a graph. A linear processor CRCW algorithm for determining the shortest-paths in an interval graphs is given.展开更多
Sediment cores （-40-100 cm） were collected at 12 locations in the western Bohai Bay, the Haihe River estuary, the Yongding River estuary and the Tianjin Harbor, China, during 24-26 July 2007, and analyzed for ^7Be a...Sediment cores （-40-100 cm） were collected at 12 locations in the western Bohai Bay, the Haihe River estuary, the Yongding River estuary and the Tianjin Harbor, China, during 24-26 July 2007, and analyzed for ^7Be and ^210pb activities. Due to localized hydrodynamic patterns and frequent disturbance from dredging activities, steady-state sedimentation features were not observed in this study. As demonstrated in the VBe and ^210pb profiles, the temporal and spatial variations of these radionuclides support a non-steady state depositional environment in the study area. By comparing ^7Be and ^210pb inventories in the sediments with those of the atmospheric source, we found that： 1） sediments dredged from the Tianjin Harbor or eroded from nearby estuarine and coastal areas are retained in the western Bohai Bay for relatively short intervals （several months）, as reflected in the relatively high ^7Be inventories in the western Bohai Bay; 2） over the long-term （years to decades）, ^210Pb inventories in the sediments imply that there is a net on-shore transport of sediments, and the sediments are mass-balanced in the entire study area. Overall, our results suggest that the sediments are retained in the estuaries and the western Bohai Bay despite local variability in sediment dynamics and disturbance due to human activities.展开更多
As the fast economic development and urban expansion, it is dififcult for traditional methods to monitor land use changes in short time interval. Moreover, remotely sensed data acquired by optical sensors is often lim...As the fast economic development and urban expansion, it is dififcult for traditional methods to monitor land use changes in short time interval. Moreover, remotely sensed data acquired by optical sensors is often limited by bad weathers and cloud cover. SAR images, such as RADARSAT-1, are an ideal tool for weather-proof observation on ground surface. This paper analyzed the results of land use change detections with time lags of 24, 48 and 72 days according to the period of acquisition dates of RADARSAT-1. The results need a compromise between accuracies and efifciencies related to the time lags. For most of the situation, it is sufifcient of using a time lag of 24 days to obtain accuracy of 60%or above. In some cases of months, a time lag of 48 days is needed. For obtaining higher accuracies, longer time lag such as 72 days is needed.展开更多
It is the first time to document the trilobite Mucronaspis(Songxites) wuningensis and the brachiopod ParomalomenaAegiromenella Assemblage from the Xinkailing Bed(Hirnantian, uppermost Ordovician) in Taoyuan and Cili c...It is the first time to document the trilobite Mucronaspis(Songxites) wuningensis and the brachiopod ParomalomenaAegiromenella Assemblage from the Xinkailing Bed(Hirnantian, uppermost Ordovician) in Taoyuan and Cili counties,northwestern Hunan Province. Synecological analysis shows that this is a deep water shelly fauna of South China during the Hirnantian. It lived on the upper Jiangnan Slope in northwestern Hunan, adjacent to the southeast margin of the Upper Yangtze Region, and belongs to the Hirnantia fauna with cool and deep water, and low diversity affinity, similar to its contemporary shelly faunas from the southern Shaanxi Slope adjacent to the north margin of the Upper Yangtze Region, the northern Chongqing depression(new name), and the Jiangxi-Anhui-Jiangsu gentle slope of the Lower Yangtze Region. Paleoecologically,it could be attributed to the BA 4–5 benthic regime(about 60–150 m deep, and deepest to 200 m), and was significantly different from the trilobite M.(S.) mucronata and the typical Hirnantia fauna while the latters may have habited in BA 2–3 benthic regimes(about 5–60 m deep). A new paleogeographic distribution pattern of the Hirnantian shallow and deep water shelly faunas of South China is herein proposed for the first time. Assuming that the depositional rate was constant in northwestern Hunan during the end Ordovician, the duration of the Xinkailing Bed might be only 12 thousand years according to the thickness of the Wufeng Formation and the absolute age values of those relevant graptolitic biozones. Such a short time interval may indicate that the global environmental change during the crisis was much shorter than previously thought, and its influence on the deep water regime was significantly shorter than that on the shallow water regime.展开更多
文摘This paper presents an efficient parallel algorithm for the shortest-path problem in interval graph for computing shortest-paths in a weighted interval graph that runs in O(n) time with n intervals in a graph. A linear processor CRCW algorithm for determining the shortest-paths in an interval graphs is given.
基金Supported by the New Jersey Sea Grant (No. 6560-0000, H. Feng)the Tianjin Science and Technology Committee (No. 06YFGHHZ01500)
文摘Sediment cores （-40-100 cm） were collected at 12 locations in the western Bohai Bay, the Haihe River estuary, the Yongding River estuary and the Tianjin Harbor, China, during 24-26 July 2007, and analyzed for ^7Be and ^210pb activities. Due to localized hydrodynamic patterns and frequent disturbance from dredging activities, steady-state sedimentation features were not observed in this study. As demonstrated in the VBe and ^210pb profiles, the temporal and spatial variations of these radionuclides support a non-steady state depositional environment in the study area. By comparing ^7Be and ^210pb inventories in the sediments with those of the atmospheric source, we found that： 1） sediments dredged from the Tianjin Harbor or eroded from nearby estuarine and coastal areas are retained in the western Bohai Bay for relatively short intervals （several months）, as reflected in the relatively high ^7Be inventories in the western Bohai Bay; 2） over the long-term （years to decades）, ^210Pb inventories in the sediments imply that there is a net on-shore transport of sediments, and the sediments are mass-balanced in the entire study area. Overall, our results suggest that the sediments are retained in the estuaries and the western Bohai Bay despite local variability in sediment dynamics and disturbance due to human activities.
基金the Research Grant Council Program of Hong Kong(Grant No.HKU7301/04H,HKU7466/06H)the International Collaborative Program of Science and Technology of Guangzhou Municipal Bureau of Science and Information Technology(Grant No.2012J5100044)
文摘As the fast economic development and urban expansion, it is dififcult for traditional methods to monitor land use changes in short time interval. Moreover, remotely sensed data acquired by optical sensors is often limited by bad weathers and cloud cover. SAR images, such as RADARSAT-1, are an ideal tool for weather-proof observation on ground surface. This paper analyzed the results of land use change detections with time lags of 24, 48 and 72 days according to the period of acquisition dates of RADARSAT-1. The results need a compromise between accuracies and efifciencies related to the time lags. For most of the situation, it is sufifcient of using a time lag of 24 days to obtain accuracy of 60%or above. In some cases of months, a time lag of 48 days is needed. For obtaining higher accuracies, longer time lag such as 72 days is needed.
基金supported by the National Natural Science Foundation of China(Grant Nos.41290260,41521061,41530103)Chinese Academy of Sciences(Grant No.XDPB05)
文摘It is the first time to document the trilobite Mucronaspis(Songxites) wuningensis and the brachiopod ParomalomenaAegiromenella Assemblage from the Xinkailing Bed(Hirnantian, uppermost Ordovician) in Taoyuan and Cili counties,northwestern Hunan Province. Synecological analysis shows that this is a deep water shelly fauna of South China during the Hirnantian. It lived on the upper Jiangnan Slope in northwestern Hunan, adjacent to the southeast margin of the Upper Yangtze Region, and belongs to the Hirnantia fauna with cool and deep water, and low diversity affinity, similar to its contemporary shelly faunas from the southern Shaanxi Slope adjacent to the north margin of the Upper Yangtze Region, the northern Chongqing depression(new name), and the Jiangxi-Anhui-Jiangsu gentle slope of the Lower Yangtze Region. Paleoecologically,it could be attributed to the BA 4–5 benthic regime(about 60–150 m deep, and deepest to 200 m), and was significantly different from the trilobite M.(S.) mucronata and the typical Hirnantia fauna while the latters may have habited in BA 2–3 benthic regimes(about 5–60 m deep). A new paleogeographic distribution pattern of the Hirnantian shallow and deep water shelly faunas of South China is herein proposed for the first time. Assuming that the depositional rate was constant in northwestern Hunan during the end Ordovician, the duration of the Xinkailing Bed might be only 12 thousand years according to the thickness of the Wufeng Formation and the absolute age values of those relevant graptolitic biozones. Such a short time interval may indicate that the global environmental change during the crisis was much shorter than previously thought, and its influence on the deep water regime was significantly shorter than that on the shallow water regime.
