计算机技术和通信技术的共同发展,使得数据呈现指数大爆炸式的增长。数据中蕴含的巨大价值是有目共睹的。但是对数据集的肆意收集与分析,使用户的隐私数据处在被泄露的风险中。为保护用户的敏感数据的同时实现对基数查询的有效响应,提...计算机技术和通信技术的共同发展,使得数据呈现指数大爆炸式的增长。数据中蕴含的巨大价值是有目共睹的。但是对数据集的肆意收集与分析,使用户的隐私数据处在被泄露的风险中。为保护用户的敏感数据的同时实现对基数查询的有效响应,提出一种基于差分隐私的隐私保护算法BFRRCE(Bloom Filter Random Response for Cardinality Estimation)。首先对用户的数据利用Bloom Filter数据结构进行数据预处理,然后利用本地差分隐私的扰动算法对数据进行扰动,达到保护用户敏感数据的目的。展开更多
Algal blooms,the spread of algae on the surface of water bodies,have adverse effects not only on aquatic ecosystems but also on human life.The adverse effects of harmful algal blooms(HABs)necessitate a convenient solu...Algal blooms,the spread of algae on the surface of water bodies,have adverse effects not only on aquatic ecosystems but also on human life.The adverse effects of harmful algal blooms(HABs)necessitate a convenient solution for detection and monitoring.Unmanned aerial vehicles(UAVs)have recently emerged as a tool for algal bloom detection,efficiently providing on-demand images at high spatiotemporal resolutions.This study developed an image processing method for algal bloom area estimation from the aerial images(obtained from the internet)captured using UAVs.As a remote sensing method of HAB detection,analysis,and monitoring,a combination of histogram and texture analyses was used to efficiently estimate the area of HABs.Statistical features like entropy(using the Kullback-Leibler method)were emphasized with the aid of a gray-level co-occurrence matrix.The results showed that the orthogonal images demonstrated fewer errors,and the morphological filter best detected algal blooms in real time,with a precision of 80%.This study provided efficient image processing approaches using on-board UAVs for HAB monitoring.展开更多
Harmful algal blooms (HABs) are a serious worldwide issue which has posed great risks on marine ecosystems and public health by directly releasing toxins or indirectly leading to anoxia in marine environment. In recen...Harmful algal blooms (HABs) are a serious worldwide issue which has posed great risks on marine ecosystems and public health by directly releasing toxins or indirectly leading to anoxia in marine environment. In recent years HABs have caused huge economic losses in China, particularly in the Yangtze Estuary and the adjacent East China Sea (ECS). The present study investigated the spatial-temporal and species characteristics of large-scale HABs in this area using geographic information system (GIS) Kernel Density Estimation (KDE) spatial analysis, statistical methods and satellite image interpretation. Results revealed that the Yangtze Estuary, Zhoushan island, Xiangshan bay and Jiushan island are the regions with highest frequency of large-scale HABs. HABs in the ECS reached a peak in terms of total number and area in 2003 to 2005 and occupied a high percentage (around 70% in area and 60% in occurrence) in the four Chinese coastal waters. The number of large-scale HABs (> 1000 km2) in the Yangtze Estuary and the adjacent ECS declined after 2005 while that of HABs (> 100 km2) declined after 2008. Large-scale HABs occurrences concentrated in summer (May to July), and the averaged duration increased continually from the shortest time (1.3 days) in 2001 to the longest (10.9 days) in 2010 for each HAB. 17 causative species were found with Prorocentrum dentutam as the most frequent dominant species, followed by Skeletonema costatum, Karenia mikimotoi, and Chaetoceros curvisetus. Water discoloration observed in MODIS satellite true color images was well consistent with the corresponding HABs reported by State Oceanic Administration of China (SOA). Multiple factors involving eutrophication, physical dynamics, topography and deposition conditions contributed to the formation of frequent HABs in the ECS. Three strategies including establishing a synthesized system, improving the previous database and investigating multiple contributors were proposed for future HABs monitoring and management.展开更多
In recent years, harmful algal blooms(HABs) have occurred frequently along the coast of China, and have been exhibiting succession from diatom- to dinofl agellate-dominated blooms. To examine the eff ects of dif feren...In recent years, harmful algal blooms(HABs) have occurred frequently along the coast of China, and have been exhibiting succession from diatom- to dinofl agellate-dominated blooms. To examine the eff ects of dif ferent diatom and dinofl agellate HABs, the life history parameters of rotifers(B rachionus plicatilis Müller) were measured after exposure to dif ferent concentrations of HAB species. The HAB species examined included a diatom(S keletonema costatum) and four dinofl agellates( Prorocentrum donghaiense, Alexandrium catenella, Prorocentrum lima and Karlodinium venefi cum). Compared with the control treatment(CT), the diatom S. costatum showed no adverse impacts on rotifers. Exposure to dinofl agellates at densities equivalent to those measured in the fi eld resulted in a reduction in all the life history parameters measured. This included a reduction in: lifetime egg production(CT: 20.34 eggs/ind.) reduced to 10.11, 3.22, 4.17, 7.16 eggs/ind., life span(CT: 394.53 h) reduced to 261.11, 162.90, 203.67, 196 h, net reproductive rate(CT: 19.51/ind.) reduced to 3.01, 1.26, 3.53, 5.96/ind., fi nite rate of increase(CT: 1.47/d) reduced to 1.16, 1.03, 1.33, 1.38/d, and intrinsic rate of population increase(CT: 0.39/d) reduced to 0.15, 0.03, 0.28, 0.32/d, for the dinofl agellates P. donghaiense, A. catenella, P. lima and K. venefi cum, respectively. The results showed that the diatom S. costatum had no detrimental consequences on the reproduction and growth of B. plicatilis, however, the four dinofl agellates tested did show adverse ef fects. This suggests that dinofl agellate HABs may suppress microzooplankton, resulting in an increase in algal numbers.展开更多
Combining some information from field investigation of algae along the coastal areas in China and a few pictures materialized from the western Yellow Sea in 2008,authors analyze the necessary conditions and possible w...Combining some information from field investigation of algae along the coastal areas in China and a few pictures materialized from the western Yellow Sea in 2008,authors analyze the necessary conditions and possible water area in China producing a large biomass,some reasons for firestorm,and the possibility of the reappearance of marine bloom green alga Enteromorpha prolifera.The change of habitats and the increase of nutritional levels related to the water area could be considered as direct reasons.It was transferred northward by the combination of the flow of rainwater,wind and alongshore marine current.The original region of large biomass produced is possibly located in the southwestern Yellow sea.It will possibly be appearing again in the coming years or in the future.A summary is also given referring to its reproduction,development and distribution worldwide.展开更多
可变长地址是未来网络领域的重要研究内容之一。针对传统路由查找算法在面向可变长地址时查找效率低的问题,提出一种基于平衡二叉树AVL(Adelson-Velskii and Landis)树和Bloom过滤器的适用于可变长地址的高效路由查找算法,简称为AVL-Bl...可变长地址是未来网络领域的重要研究内容之一。针对传统路由查找算法在面向可变长地址时查找效率低的问题,提出一种基于平衡二叉树AVL(Adelson-Velskii and Landis)树和Bloom过滤器的适用于可变长地址的高效路由查找算法,简称为AVL-Bloom算法。首先,针对可变长地址灵活可变且无界的特点,利用多个片外哈希表分别存储前缀比特位数相同的路由条目及其下一跳信息,同时应用片上Bloom过滤器加速搜索可能匹配的路由前缀;其次,为了解决基于哈希技术的路由查找算法在查找最长前缀路由时需多次哈希对比的问题,引入AVL树技术,即通过AVL树组织每组路由前缀集合的Bloom过滤器及其哈希表,优化路由前缀长度的查询顺序,并减少哈希计算次数进而降低查询时间;最后,在3种不同的可变长地址数据集上将所提算法与METrie(Multi-Entrance-Trie)和COBF(Controlled prefix and One-hashing Bloom Filter)这两种传统路由查找算法进行对比实验。实验结果表明,AVL-Bloom算法的查询时间明显少于METrie和COBF算法,分别减少了将近83%和64%;同时,AVL-Bloom算法在路由表项数变化较大的情况下也能维持稳定的查找性能,适用于可变长地址的路由查找转发。展开更多
文摘计算机技术和通信技术的共同发展,使得数据呈现指数大爆炸式的增长。数据中蕴含的巨大价值是有目共睹的。但是对数据集的肆意收集与分析,使用户的隐私数据处在被泄露的风险中。为保护用户的敏感数据的同时实现对基数查询的有效响应,提出一种基于差分隐私的隐私保护算法BFRRCE(Bloom Filter Random Response for Cardinality Estimation)。首先对用户的数据利用Bloom Filter数据结构进行数据预处理,然后利用本地差分隐私的扰动算法对数据进行扰动,达到保护用户敏感数据的目的。
文摘Algal blooms,the spread of algae on the surface of water bodies,have adverse effects not only on aquatic ecosystems but also on human life.The adverse effects of harmful algal blooms(HABs)necessitate a convenient solution for detection and monitoring.Unmanned aerial vehicles(UAVs)have recently emerged as a tool for algal bloom detection,efficiently providing on-demand images at high spatiotemporal resolutions.This study developed an image processing method for algal bloom area estimation from the aerial images(obtained from the internet)captured using UAVs.As a remote sensing method of HAB detection,analysis,and monitoring,a combination of histogram and texture analyses was used to efficiently estimate the area of HABs.Statistical features like entropy(using the Kullback-Leibler method)were emphasized with the aid of a gray-level co-occurrence matrix.The results showed that the orthogonal images demonstrated fewer errors,and the morphological filter best detected algal blooms in real time,with a precision of 80%.This study provided efficient image processing approaches using on-board UAVs for HAB monitoring.
文摘Harmful algal blooms (HABs) are a serious worldwide issue which has posed great risks on marine ecosystems and public health by directly releasing toxins or indirectly leading to anoxia in marine environment. In recent years HABs have caused huge economic losses in China, particularly in the Yangtze Estuary and the adjacent East China Sea (ECS). The present study investigated the spatial-temporal and species characteristics of large-scale HABs in this area using geographic information system (GIS) Kernel Density Estimation (KDE) spatial analysis, statistical methods and satellite image interpretation. Results revealed that the Yangtze Estuary, Zhoushan island, Xiangshan bay and Jiushan island are the regions with highest frequency of large-scale HABs. HABs in the ECS reached a peak in terms of total number and area in 2003 to 2005 and occupied a high percentage (around 70% in area and 60% in occurrence) in the four Chinese coastal waters. The number of large-scale HABs (> 1000 km2) in the Yangtze Estuary and the adjacent ECS declined after 2005 while that of HABs (> 100 km2) declined after 2008. Large-scale HABs occurrences concentrated in summer (May to July), and the averaged duration increased continually from the shortest time (1.3 days) in 2001 to the longest (10.9 days) in 2010 for each HAB. 17 causative species were found with Prorocentrum dentutam as the most frequent dominant species, followed by Skeletonema costatum, Karenia mikimotoi, and Chaetoceros curvisetus. Water discoloration observed in MODIS satellite true color images was well consistent with the corresponding HABs reported by State Oceanic Administration of China (SOA). Multiple factors involving eutrophication, physical dynamics, topography and deposition conditions contributed to the formation of frequent HABs in the ECS. Three strategies including establishing a synthesized system, improving the previous database and investigating multiple contributors were proposed for future HABs monitoring and management.
基金Supported by the Innovation Research Group Program of National Natural Science Foundation of China(No.41121064)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA01020304)
文摘In recent years, harmful algal blooms(HABs) have occurred frequently along the coast of China, and have been exhibiting succession from diatom- to dinofl agellate-dominated blooms. To examine the eff ects of dif ferent diatom and dinofl agellate HABs, the life history parameters of rotifers(B rachionus plicatilis Müller) were measured after exposure to dif ferent concentrations of HAB species. The HAB species examined included a diatom(S keletonema costatum) and four dinofl agellates( Prorocentrum donghaiense, Alexandrium catenella, Prorocentrum lima and Karlodinium venefi cum). Compared with the control treatment(CT), the diatom S. costatum showed no adverse impacts on rotifers. Exposure to dinofl agellates at densities equivalent to those measured in the fi eld resulted in a reduction in all the life history parameters measured. This included a reduction in: lifetime egg production(CT: 20.34 eggs/ind.) reduced to 10.11, 3.22, 4.17, 7.16 eggs/ind., life span(CT: 394.53 h) reduced to 261.11, 162.90, 203.67, 196 h, net reproductive rate(CT: 19.51/ind.) reduced to 3.01, 1.26, 3.53, 5.96/ind., fi nite rate of increase(CT: 1.47/d) reduced to 1.16, 1.03, 1.33, 1.38/d, and intrinsic rate of population increase(CT: 0.39/d) reduced to 0.15, 0.03, 0.28, 0.32/d, for the dinofl agellates P. donghaiense, A. catenella, P. lima and K. venefi cum, respectively. The results showed that the diatom S. costatum had no detrimental consequences on the reproduction and growth of B. plicatilis, however, the four dinofl agellates tested did show adverse ef fects. This suggests that dinofl agellate HABs may suppress microzooplankton, resulting in an increase in algal numbers.
基金Supported by general and major projects of National Natural Science Foundation of China (Nos 40876081,30570125,and 30499340(partly)the National High Technology Research and Development Program of China (863 Program)(No 2008BAC49B01)Knowledge Innovation Project of Chinese Academy of Sciences (No KSCX2-YW-Z-018)
文摘Combining some information from field investigation of algae along the coastal areas in China and a few pictures materialized from the western Yellow Sea in 2008,authors analyze the necessary conditions and possible water area in China producing a large biomass,some reasons for firestorm,and the possibility of the reappearance of marine bloom green alga Enteromorpha prolifera.The change of habitats and the increase of nutritional levels related to the water area could be considered as direct reasons.It was transferred northward by the combination of the flow of rainwater,wind and alongshore marine current.The original region of large biomass produced is possibly located in the southwestern Yellow sea.It will possibly be appearing again in the coming years or in the future.A summary is also given referring to its reproduction,development and distribution worldwide.
文摘可变长地址是未来网络领域的重要研究内容之一。针对传统路由查找算法在面向可变长地址时查找效率低的问题,提出一种基于平衡二叉树AVL(Adelson-Velskii and Landis)树和Bloom过滤器的适用于可变长地址的高效路由查找算法,简称为AVL-Bloom算法。首先,针对可变长地址灵活可变且无界的特点,利用多个片外哈希表分别存储前缀比特位数相同的路由条目及其下一跳信息,同时应用片上Bloom过滤器加速搜索可能匹配的路由前缀;其次,为了解决基于哈希技术的路由查找算法在查找最长前缀路由时需多次哈希对比的问题,引入AVL树技术,即通过AVL树组织每组路由前缀集合的Bloom过滤器及其哈希表,优化路由前缀长度的查询顺序,并减少哈希计算次数进而降低查询时间;最后,在3种不同的可变长地址数据集上将所提算法与METrie(Multi-Entrance-Trie)和COBF(Controlled prefix and One-hashing Bloom Filter)这两种传统路由查找算法进行对比实验。实验结果表明,AVL-Bloom算法的查询时间明显少于METrie和COBF算法,分别减少了将近83%和64%;同时,AVL-Bloom算法在路由表项数变化较大的情况下也能维持稳定的查找性能,适用于可变长地址的路由查找转发。
