To improve the performance of the traditional map matching algorithms in freeway traffic state monitoring systems using the low logging frequency GPS （global positioning system） probe data, a map matching algorithm ...To improve the performance of the traditional map matching algorithms in freeway traffic state monitoring systems using the low logging frequency GPS （global positioning system） probe data, a map matching algorithm based on the Oracle spatial data model is proposed. The algorithm uses the Oracle road network data model to analyze the spatial relationships between massive GPS positioning points and freeway networks, builds an N-shortest path algorithm to find reasonable candidate routes between GPS positioning points efficiently, and uses the fuzzy logic inference system to determine the final matched traveling route. According to the implementation with field data from Los Angeles, the computation speed of the algorithm is about 135 GPS positioning points per second and the accuracy is 98.9%. The results demonstrate the effectiveness and accuracy of the proposed algorithm for mapping massive GPS positioning data onto freeway networks with complex geometric characteristics.展开更多
A simplified method is presented for predicting consolidation settlement of soft ground improved by floating soil-cement column on the basis of double soil-layer consolidation theory. Combining the axisymmetric consol...A simplified method is presented for predicting consolidation settlement of soft ground improved by floating soil-cement column on the basis of double soil-layer consolidation theory. Combining the axisymmetric consolidation model and equal strain assumption, the governing equation was derived for the consolidation of clayey subsoil reinforced by soil-cement column. By modifying the boundary condition of the interface between the improved layer and underlying layer on seepage and pore-water pressure, the analytical solution of consolidation of soft ground improved by floating soil-cement column was developed under depth-dependent ramp load. The results of the parameter analysis of consolidation behavior show that the consolidation rate is closely related with the depth replacement ratio by the column and the permeability of upper layer. The influence of column-soil constrained modulus ratio and radius ratio of the influence zone to the column on consolidation is also affected by depth replacement ratio. The column-soil total stress ratio increases with time and approaches the final value accompanied with the dissipation of excess pore water pressure.展开更多
The dinoflagellate Noctiluca scintillans is one of the most important and abundant red tide organisms and it is distributed world-wide. It occurs in two forms. Red Noctiluca is heterotrophic and fills the role of one ...The dinoflagellate Noctiluca scintillans is one of the most important and abundant red tide organisms and it is distributed world-wide. It occurs in two forms. Red Noctiluca is heterotrophic and fills the role of one of the microzooplankton grazers in the foodweb. In contrast, green Noctiluca contains a photosynthetic symbiont Pedinomonas noctilucae （a prasinophyte）, but it also feeds on other plankton when the food supply is abundant. In this review, we document the global distribution of these two forms and include the first maps of their global distribution. Red Noctiluca occurs widely in the temperate to sub-tropical coastal regions of the world. It occurs over a wide temperature range of about 10℃ to 25℃ and at higher salinities （generally not in estuaries）. It is particularly abundant in high productivity areas such as upwelling or eutrophic areas where diatoms dominate since they are its preferred food source. Green Noctiluca is much more restricted to a temperature range of 25℃-30℃ and mainly occurs in tropical waters of Southeast Asia, Bay of Bengal （east coast of India）, in the eastern, western and northern Arabian Sea, the Red Sea, and recently it has become very abundant in the Gulf of Oman. Red and green Noctiluca do overlap in their distribution in the eastern, northern and western Arabian Sea with a seasonal shift from green Noctiluca in the cooler winter convective mixing, higher productivity season, to red Noctiluca in the more oligotrophic warmer summer season.展开更多
The present condition of Southern Kazakhstan natural reservoirs is represented in the article. The research was held in summer time of 2010. Quantitative and qualitative features and dominating types of zooplankton of...The present condition of Southern Kazakhstan natural reservoirs is represented in the article. The research was held in summer time of 2010. Quantitative and qualitative features and dominating types of zooplankton of the individual reservoirs are shown. It is detected that the waters of the South Kazakhstan oblast （region） are inhabited by 70 types of zooplankton organisms of different taxonomic groups, whose association to certain reservoir depends on the hydrochemical indicators of the aquatic environment.展开更多
There has been a continuous decline in the catches of Limnothrissa m iodon in Lake Kariba since 1994. Given the value and contribution of this sardine in the GDP （gross domestic product） of Zimbabwe, research on its...There has been a continuous decline in the catches of Limnothrissa m iodon in Lake Kariba since 1994. Given the value and contribution of this sardine in the GDP （gross domestic product） of Zimbabwe, research on its ecology becomes vital. The diet composition of L. miodon in the Sanyati basin of Lake Kariba was explored using numerical and frequency of occurrence methods. Densities of zooplankton species in the riverine and pelagic zones of the basin were established. Zooplankton species were collected at each site using 60 μm mesh plankton, preserved and classified in the laboratory. Limnothrissa miodon samples （500 g） were collected from Kapenta rigs for gut analysis. Diet overlap and relative prey selection was analysed using Schoener index and Chesson＇s index of selection respectively. ANOVA was done to establish the variations in the zooplankton densities in the riverine and pelagic sampling areas as well as proportional occurrences of prey item consumed. Significant differences on proportions of chironomids （F = 1.94, P 〈 0.05）, nauplii （F= 10.24, P 〈 0.05） and Diaphanosoma （F= 20.98, P 〈 0.05） preyed by Kapenta size classes in riverine specimens were noted. Proportion ofchironomids and Bosmina eaten by adult and sub-adult Kapenta in pelagic waters were significantly different （F = 2.55, P 〈 0.05） and （F = 2.21, P 〈 0.05）. A hierarchical cluster analysis using species densities revealed no major divisions in faunal associations among cyclopoids. Findings of this study indicate that the densities of zooplankton species between pelagic and riverine sections of the Sanyati basin are different.展开更多
文摘To improve the performance of the traditional map matching algorithms in freeway traffic state monitoring systems using the low logging frequency GPS （global positioning system） probe data, a map matching algorithm based on the Oracle spatial data model is proposed. The algorithm uses the Oracle road network data model to analyze the spatial relationships between massive GPS positioning points and freeway networks, builds an N-shortest path algorithm to find reasonable candidate routes between GPS positioning points efficiently, and uses the fuzzy logic inference system to determine the final matched traveling route. According to the implementation with field data from Los Angeles, the computation speed of the algorithm is about 135 GPS positioning points per second and the accuracy is 98.9%. The results demonstrate the effectiveness and accuracy of the proposed algorithm for mapping massive GPS positioning data onto freeway networks with complex geometric characteristics.
基金Project(51278450)supported by the National Natural Science Foundation of China
文摘A simplified method is presented for predicting consolidation settlement of soft ground improved by floating soil-cement column on the basis of double soil-layer consolidation theory. Combining the axisymmetric consolidation model and equal strain assumption, the governing equation was derived for the consolidation of clayey subsoil reinforced by soil-cement column. By modifying the boundary condition of the interface between the improved layer and underlying layer on seepage and pore-water pressure, the analytical solution of consolidation of soft ground improved by floating soil-cement column was developed under depth-dependent ramp load. The results of the parameter analysis of consolidation behavior show that the consolidation rate is closely related with the depth replacement ratio by the column and the permeability of upper layer. The influence of column-soil constrained modulus ratio and radius ratio of the influence zone to the column on consolidation is also affected by depth replacement ratio. The column-soil total stress ratio increases with time and approaches the final value accompanied with the dissipation of excess pore water pressure.
基金the University Grants Council of Hong Kong and its Area of Excellence Program to PJH. KF was supported by a JSPS grant on the ecophysiology of green Noctiluca in the Gulf of Thailand. PMG received funding from NSF （No. OCE-1015980）This is contribution number 4502 from the University of Maryland Center for Environmental Studies. KY Acknowledges Support from the CAS/SAFEA International Partnership Program for Creative Research Teams （No. KZCXZYW-T001）. DMA received partial funding through the NSF/NIEHS Centers for Oceans and Human Health （No. NIEHS P50 ES012742, NSF OCE- 043072 and OCE-0911031）, and through NSF Grant （No. OCE-0850421）+1 种基金 This paper is based on work partially supported by SCOR/LOICZ Working Group 132, supported by the Scientific Committee on Oceanographic Research （SCOR） through grants from the U.S. National Science Foundation （No OCE-0938349 and OCE-0813697） from the Land-Ocean Interactions in the Coastal Zone （LOICZ） Project and the Chinese Academy of Sciences. We thank A. KANA for assistance with the GIS produced maps and LIU Hao for his assistance with the tables and references.
文摘The dinoflagellate Noctiluca scintillans is one of the most important and abundant red tide organisms and it is distributed world-wide. It occurs in two forms. Red Noctiluca is heterotrophic and fills the role of one of the microzooplankton grazers in the foodweb. In contrast, green Noctiluca contains a photosynthetic symbiont Pedinomonas noctilucae （a prasinophyte）, but it also feeds on other plankton when the food supply is abundant. In this review, we document the global distribution of these two forms and include the first maps of their global distribution. Red Noctiluca occurs widely in the temperate to sub-tropical coastal regions of the world. It occurs over a wide temperature range of about 10℃ to 25℃ and at higher salinities （generally not in estuaries）. It is particularly abundant in high productivity areas such as upwelling or eutrophic areas where diatoms dominate since they are its preferred food source. Green Noctiluca is much more restricted to a temperature range of 25℃-30℃ and mainly occurs in tropical waters of Southeast Asia, Bay of Bengal （east coast of India）, in the eastern, western and northern Arabian Sea, the Red Sea, and recently it has become very abundant in the Gulf of Oman. Red and green Noctiluca do overlap in their distribution in the eastern, northern and western Arabian Sea with a seasonal shift from green Noctiluca in the cooler winter convective mixing, higher productivity season, to red Noctiluca in the more oligotrophic warmer summer season.
文摘The present condition of Southern Kazakhstan natural reservoirs is represented in the article. The research was held in summer time of 2010. Quantitative and qualitative features and dominating types of zooplankton of the individual reservoirs are shown. It is detected that the waters of the South Kazakhstan oblast （region） are inhabited by 70 types of zooplankton organisms of different taxonomic groups, whose association to certain reservoir depends on the hydrochemical indicators of the aquatic environment.
文摘There has been a continuous decline in the catches of Limnothrissa m iodon in Lake Kariba since 1994. Given the value and contribution of this sardine in the GDP （gross domestic product） of Zimbabwe, research on its ecology becomes vital. The diet composition of L. miodon in the Sanyati basin of Lake Kariba was explored using numerical and frequency of occurrence methods. Densities of zooplankton species in the riverine and pelagic zones of the basin were established. Zooplankton species were collected at each site using 60 μm mesh plankton, preserved and classified in the laboratory. Limnothrissa miodon samples （500 g） were collected from Kapenta rigs for gut analysis. Diet overlap and relative prey selection was analysed using Schoener index and Chesson＇s index of selection respectively. ANOVA was done to establish the variations in the zooplankton densities in the riverine and pelagic sampling areas as well as proportional occurrences of prey item consumed. Significant differences on proportions of chironomids （F = 1.94, P 〈 0.05）, nauplii （F= 10.24, P 〈 0.05） and Diaphanosoma （F= 20.98, P 〈 0.05） preyed by Kapenta size classes in riverine specimens were noted. Proportion ofchironomids and Bosmina eaten by adult and sub-adult Kapenta in pelagic waters were significantly different （F = 2.55, P 〈 0.05） and （F = 2.21, P 〈 0.05）. A hierarchical cluster analysis using species densities revealed no major divisions in faunal associations among cyclopoids. Findings of this study indicate that the densities of zooplankton species between pelagic and riverine sections of the Sanyati basin are different.
