New LIDAR （Light Detection and Ranging） and sonar imagery have revealed remarkable geomorphic details never seen before and not visible by any other means. Numerous faults and other geologic structures are plainly v...New LIDAR （Light Detection and Ranging） and sonar imagery have revealed remarkable geomorphic details never seen before and not visible by any other means. Numerous faults and other geologic structures are plainly visible on LIDAR and sonar images. Many previously unknown faults criss-cross the islands and large fault scarps are visible on sonar imagery along the margins of the larger islands. Sonar images of sea floor morphology show many submerged faults as long linear scarps with relief up to 300m （1,000 fl）, some of which visibly truncate geologic structures. The San Juan Lopez fault, the largest fault in the islands, extends for at least 65 km （40 mi） from Stuart Island to Rosario strait with a scarp up to 330m （1,000 it） high. Since 1975, the basic structural framework of the San Juan Islands has been considered to consist of five stacked thrust faults, the Rosario, Orcas, Haro, Lopez, and Buck Bay faults, constituting the San Juan Thrust （Nappe） System that has shuffled together far distant terranes. However, the new LIDAR and sonar imagery shows that most of the mapped extent of these postulated faults are actually segments of high angle, dipslip faults and are not thrust faults at all. Thus, the San Juan Thrust （Nappe） System does not exist. The age of these faults is not accurately known and more than one period of high angle faulting may have occurred. Faults shown on L1DAR images of the surface of the islands appear as visible gashes, etched out by erosion of fault zones with few fault scarps. However, the sea floor faults have bold relief and high scarps. A late Pleistocene moraine lies undisturbed across the San Juan Lopez fault.展开更多
The species-area relationship （SAR） is one of the most fundamental concepts in community ecology and is helpful for biodiversity conservation. However, few studies have systematically addressed this topic for differ...The species-area relationship （SAR） is one of the most fundamental concepts in community ecology and is helpful for biodiversity conservation. However, few studies have systematically addressed this topic for different alpine grassland types on the Tibetan Plateau, China. We explored whether the plant composition of different functional groups affects the manner in which species richness inereases with increasing area at scales ≤ 1.0 m^2. We also compared species richness （S） within and across forbs, legumes, sedges and grasses, with sampling subplot area （A） increasing from 0.0625 m^2 to 1.0 m^2 between alpine meadow and steppe communities. We applied a logarithmic function （S = b0 ＋ b1 ln A） to determine the slope and intercept of SAR curves within and across functional groups. The results showed that the logarithmic relationship holds true between species richness and sampling area at these small scales. Both the intercept and slope of the logarithmic forbs-area curves are significantly higher than those for the three other functional groups （P 〈 0.05）. Forb accounts for about 91.9 % of the variation in the intercept and 75.0% of the variation in the slope of the SAR curve when all functional groups＇ data were pooled together. Our results indicated that the different SAR patterns should be linked with species dispersal capabilities, environmental filtering, and life form composition within alpine grassland communities. Further studies on the relationship between species diversity and ecosystem functions should specify the differential responses of different functional groups to variations in climate and anthropogenic disturbances.展开更多
A hybrid optimization approach combining a particle swarm algorithm, a genetic algorithm, and a heuristic interleaving algorithm is proposed for scheduling tasks in the multifunction phased array radar. By optimizing ...A hybrid optimization approach combining a particle swarm algorithm, a genetic algorithm, and a heuristic interleaving algorithm is proposed for scheduling tasks in the multifunction phased array radar. By optimizing parameters using chaos theory, designing the dynamic inertia weight for the particle swarm algorithm as well as introducing crossover operation and mutation operation of the genetic algorithm, both the efficiency and exploration ability of the hybrid algorithm are improved. Under the frame of the intelligence algorithm, the heuristic interleaving scheduling algorithm is presented to further use the time resource of the task waiting duration. A large-scale simulation demonstrates that the proposed algorithm is more robust and efficient than existing algorithms.展开更多
文摘New LIDAR （Light Detection and Ranging） and sonar imagery have revealed remarkable geomorphic details never seen before and not visible by any other means. Numerous faults and other geologic structures are plainly visible on LIDAR and sonar images. Many previously unknown faults criss-cross the islands and large fault scarps are visible on sonar imagery along the margins of the larger islands. Sonar images of sea floor morphology show many submerged faults as long linear scarps with relief up to 300m （1,000 fl）, some of which visibly truncate geologic structures. The San Juan Lopez fault, the largest fault in the islands, extends for at least 65 km （40 mi） from Stuart Island to Rosario strait with a scarp up to 330m （1,000 it） high. Since 1975, the basic structural framework of the San Juan Islands has been considered to consist of five stacked thrust faults, the Rosario, Orcas, Haro, Lopez, and Buck Bay faults, constituting the San Juan Thrust （Nappe） System that has shuffled together far distant terranes. However, the new LIDAR and sonar imagery shows that most of the mapped extent of these postulated faults are actually segments of high angle, dipslip faults and are not thrust faults at all. Thus, the San Juan Thrust （Nappe） System does not exist. The age of these faults is not accurately known and more than one period of high angle faulting may have occurred. Faults shown on L1DAR images of the surface of the islands appear as visible gashes, etched out by erosion of fault zones with few fault scarps. However, the sea floor faults have bold relief and high scarps. A late Pleistocene moraine lies undisturbed across the San Juan Lopez fault.
基金supported by the Chinese Academy of Sciences (Grant Nos.XDB03030401,KZCXZ-XB3-08)the State Scholarship Fund of the China Scholarship Council (Grant No.201400260118)the International Postdoctoral Exchange Fellowship Program 2014 by the Office of China Postdoctoral Council (Grant No.20140041)
文摘The species-area relationship （SAR） is one of the most fundamental concepts in community ecology and is helpful for biodiversity conservation. However, few studies have systematically addressed this topic for different alpine grassland types on the Tibetan Plateau, China. We explored whether the plant composition of different functional groups affects the manner in which species richness inereases with increasing area at scales ≤ 1.0 m^2. We also compared species richness （S） within and across forbs, legumes, sedges and grasses, with sampling subplot area （A） increasing from 0.0625 m^2 to 1.0 m^2 between alpine meadow and steppe communities. We applied a logarithmic function （S = b0 ＋ b1 ln A） to determine the slope and intercept of SAR curves within and across functional groups. The results showed that the logarithmic relationship holds true between species richness and sampling area at these small scales. Both the intercept and slope of the logarithmic forbs-area curves are significantly higher than those for the three other functional groups （P 〈 0.05）. Forb accounts for about 91.9 % of the variation in the intercept and 75.0% of the variation in the slope of the SAR curve when all functional groups＇ data were pooled together. Our results indicated that the different SAR patterns should be linked with species dispersal capabilities, environmental filtering, and life form composition within alpine grassland communities. Further studies on the relationship between species diversity and ecosystem functions should specify the differential responses of different functional groups to variations in climate and anthropogenic disturbances.
基金Project supported by the National Natural Science Foundation of China （Nos. 61503408 and 61601504）
文摘A hybrid optimization approach combining a particle swarm algorithm, a genetic algorithm, and a heuristic interleaving algorithm is proposed for scheduling tasks in the multifunction phased array radar. By optimizing parameters using chaos theory, designing the dynamic inertia weight for the particle swarm algorithm as well as introducing crossover operation and mutation operation of the genetic algorithm, both the efficiency and exploration ability of the hybrid algorithm are improved. Under the frame of the intelligence algorithm, the heuristic interleaving scheduling algorithm is presented to further use the time resource of the task waiting duration. A large-scale simulation demonstrates that the proposed algorithm is more robust and efficient than existing algorithms.
