Processing a join over unbounded input streams requires unbounded memory, since every tuple in one infinite stream must be compared with every tuple in the other. In fact, most join queries over unbounded input stream...Processing a join over unbounded input streams requires unbounded memory, since every tuple in one infinite stream must be compared with every tuple in the other. In fact, most join queries over unbounded input streams are restricted to finite memory due to sliding window constraints. So far, non-indexed and indexed stream equijoin algorithms based on sliding windows have been proposed in many literatures. However, none of them takes non-equijoin into consideration. In many eases, non-equijoin queries occur frequently. Hence, it is worth to discuss how to process non-equijoin queries effectively and efficiently. In this paper, we propose an indexed join algorithm for supporting non-equijoin queries. The experimental results show that our indexed non-equijoin techniques are more efficient than those without index.展开更多
累计局部离群因子(cumulative local outlier factor,C_LOF)算法能有效解决数据流中的概念漂移问题和克服离群点检测中的伪装问题,但在处理高维数据时,时间复杂度较高。为有效解决时间复杂度高的问题,提出一种基于投影索引近邻的累计局...累计局部离群因子(cumulative local outlier factor,C_LOF)算法能有效解决数据流中的概念漂移问题和克服离群点检测中的伪装问题,但在处理高维数据时,时间复杂度较高。为有效解决时间复杂度高的问题,提出一种基于投影索引近邻的累计局部离群因子(cumulative local outlier factor based projection indexed nearest neighbor,PINN_C_LOF)算法。使用滑动窗口维护活跃数据点,在新数据到达和旧数据过期时,引入投影索引近邻(projection indexed nearest neighbor,PINN)方法,增量更新窗口中受影响数据点的近邻。实验结果表明,PINN_C_LOF算法在检测高维流数据离群值时,在保持检测精确度的前提下,其时间复杂度较C_LOF算法明显降低。展开更多
This study is aimed at determining the level of environmental degradation as well as the concentration of trace elements in soil and stream sediments in order to evaluate the environmental impact of the mining operati...This study is aimed at determining the level of environmental degradation as well as the concentration of trace elements in soil and stream sediments in order to evaluate the environmental impact of the mining operation.Twenty-five(25) soils and ten(10) stream sediment samples were collected from the study area. The physicochemical parameters were determined using appropriate instrumentation with the aid of a digital p H meter(Milwaukee meter) to measure the p H and electrical conductivity, total dissolved solids, moisture content and loss on ignition of the soil and stream sediment samples. The p H of the soil sample ranged from(6.10 to 7.19); Electrical conductivity ranged from(21.3 to 279.4 μS/cm), moisture content varied from(0.60% to 7.20%), and the LOI ranged from(2.03% to 18.62%). The results of the analysis showed that the concentrations of the trace elements in the soils and stream sediment samples were slightly higher than the background values. Plots of the trace elements in stream sediment samples show moderate, consistent decrease downstream except at points where there was mine water discharge into the main river. The pollution levels of heavy metals were examined in stream sediment and soil samples using different assessable indices, such as the enrichment factor, which showed significant-moderate enrichment for Cr, Th, Nb, Zn, Pb, Y and Zr and the geoaccumulation index, which showed practically moderate contamination with Cr, Ni and Sr based on regional background reference values. Geo-accumulation index and contamination index for soils and stream sediment revealed uncontaminated to moderate contamination. Likewise,elements with moderate contamination were Cr, Ni and Sr.The Pearson correlation showed that there were significant positive associations among selected metals in soil and stream sediment samples.展开更多
Fish were collected from 39 sites on the main channel and major tributaries of a highly erosive stream, Hotophia Creek. A total of 2,642 specimens representing 38 species were collected between 1986 through 2003. The ...Fish were collected from 39 sites on the main channel and major tributaries of a highly erosive stream, Hotophia Creek. A total of 2,642 specimens representing 38 species were collected between 1986 through 2003. The bluntface shiner Cyprinella camura was the dominant species of fish and when grouped with other cyprinids accounted for 38.0% of the total numbers collected. By weight, Lepisosteusoculatus, Lepomismegalotis, lctiobusbubalus, and Lepomismacrochirus were the dominant species; accounting for 49.9% of the total catch. While more diminutive species such as cyprinids that might be subject to predation by large fish more frequently were found in shallow channels. Fishes with specific habitat requirement such as the pirate perch were found in the middle group of sites, that were disturbed by erosion process but that featured the necessary habitat requirements. Sensitive or intolerant species like the Yazoo darter, creek chubsucker and cyprinids in general were more frequently found in the undisturbed and habitat complex channels. This study supports the hypothesis that geomorphological stream stages are associated with specific communities of fishes.展开更多
River Iyiudene is a vital distributary resource in Abakaliki, southeastern Nigeria and conveys an abundant amount of sediments to provincial and residual ecosystems. Although the importance of the river cannot be over...River Iyiudene is a vital distributary resource in Abakaliki, southeastern Nigeria and conveys an abundant amount of sediments to provincial and residual ecosystems. Although the importance of the river cannot be overemphasized, the geochemistry of its stream sediments is less investigated. Twenty (20) stream sediment samples were taken at the centre of the river channels to represent the entire drainage area well and avoid collapsed bank materials. The stream sediment samples were used to determine the dispersion, contamination status and sources of heavy metal concentrations. Total elemental digestion accompanied this with the use of aqua regia, an admixture of Hydrochloric acid (HCl) and Nitric acid (HNO<sub>3</sub>) in the ratio of 3:1 using the atomic absorption spectrometer (AAS). The heavy metal concentration levels in River Iyiudene were low compared with sediments from Imo River, Gulf of California, Upper continental crust, Average shale and surface horizons, excluding Cd, which showed high concentration levels than the other reference studies. The results delineated a wide contrast in the concentration levels of the heavy metals, with the mean contents in the order Zn > Cu > Pb > Cd > Ni > As. The pollution evaluation utilizing the Effect range low (ERL), Effect range median (ERM), single pollution index, and geo-accumulation index revealed Cd contamination. This study indicates that the heavy metals were sourced from the natural geological background of the river basin and possibly from agricultural runoff and atmospheric pollutants.展开更多
In order to study stream sediments in the terahertz range, we have measured six reference stream sediment samples by terahertz time-domain spectroscopy (THz-TDS). We obtained the absorption coefficients and refractive...In order to study stream sediments in the terahertz range, we have measured six reference stream sediment samples by terahertz time-domain spectroscopy (THz-TDS). We obtained the absorption coefficients and refractive indexes. By analyzing the spectra, we got different drops in amplitude and delays in time. The absorption and refractive properties of samples changed with its components and types. In addition, we also found there was a nearly linear relationship between the absorption coefficient and the frequency. We calculated the slope value (K) of each sample by linear fitting, and find the K was corresponding to the contents of the samples. The results showed THz-TDS was an effective method to the analysis of stream sediments.展开更多
The Castelhano Stream Hydrographic Basin, located in the city of Venancio Aires, RS, Brazil, shows an area of 675.3 km2, highlighting the Castelhano Stream as their main water course. The stream is the main responsibl...The Castelhano Stream Hydrographic Basin, located in the city of Venancio Aires, RS, Brazil, shows an area of 675.3 km2, highlighting the Castelhano Stream as their main water course. The stream is the main responsiblity for the local water supply;however, there are no published studies in the literature regarding their water quality. In this context, the present research aimed to assess the water quality of Castelhano Stream in terms of organic pollution and eutrophication, applying the Biological Water Quality Index (BWQI), which uses epilithic diatoms communities as bioindicators. Biological samples were collected at three sampling stations along the stream in the months of September, November and December 2012. The results showed 81 identified species, distributed in 30 genera. The water pollution levels detected ranged from “strong” (66.7%) and “very strong” (33.3%), with differences in species composition between sampling stations. The sampling station S1 in the upper reaches was characterized by the presence of indicative species of acidophilus and lentic environments with large amounts of organic matter. The sampling stations S2 and S3, in the intermediate and lower reaches, respectively, showed a substitution of species in the community, with the presence of highly tolerant taxa to organic pollution and eutrophication. The high pollution levels detected along the basin are related to the nutrients and high organic load originating from livestock, domestic and industrial waste, as well as excess fertilizers and agricultural inputs used in farming. The results demonstrate the necessity to implement mitigation measures to contain the processes of organic pollution and eutrophication detected due to the dangers offered to public health and the environment.展开更多
短视频平台的直播带货已成为当前企业营销获客研究的新热点,如何实现该营销渠道下的精细化营销成为企业亟需解决的问题。该模型融合目标群体指数(Target Group Index,TGI)和自组织映射(Self-Organizing Map,SOM)技术对平台Q公司进行客...短视频平台的直播带货已成为当前企业营销获客研究的新热点,如何实现该营销渠道下的精细化营销成为企业亟需解决的问题。该模型融合目标群体指数(Target Group Index,TGI)和自组织映射(Self-Organizing Map,SOM)技术对平台Q公司进行客户细分,研究其细分人群的属性特征和产品服务偏好,并分析了不同产品服务间的相似性。结果表明:Q公司的目标消费群体集中在三线以上城市;十二大产品服务可以划分四类进行组合营销。该研究证实,TGI与SOM的结合可有效地分析人群对产品服务的偏好行为,为企业在营销推广管理过程中根据消费者偏好选择合适直播达人,匹配合适产品服务提供数据决策支持。展开更多
基金Supported by the National Natural Science Foun-dation of China (60473073)
文摘Processing a join over unbounded input streams requires unbounded memory, since every tuple in one infinite stream must be compared with every tuple in the other. In fact, most join queries over unbounded input streams are restricted to finite memory due to sliding window constraints. So far, non-indexed and indexed stream equijoin algorithms based on sliding windows have been proposed in many literatures. However, none of them takes non-equijoin into consideration. In many eases, non-equijoin queries occur frequently. Hence, it is worth to discuss how to process non-equijoin queries effectively and efficiently. In this paper, we propose an indexed join algorithm for supporting non-equijoin queries. The experimental results show that our indexed non-equijoin techniques are more efficient than those without index.
文摘累计局部离群因子(cumulative local outlier factor,C_LOF)算法能有效解决数据流中的概念漂移问题和克服离群点检测中的伪装问题,但在处理高维数据时,时间复杂度较高。为有效解决时间复杂度高的问题,提出一种基于投影索引近邻的累计局部离群因子(cumulative local outlier factor based projection indexed nearest neighbor,PINN_C_LOF)算法。使用滑动窗口维护活跃数据点,在新数据到达和旧数据过期时,引入投影索引近邻(projection indexed nearest neighbor,PINN)方法,增量更新窗口中受影响数据点的近邻。实验结果表明,PINN_C_LOF算法在检测高维流数据离群值时,在保持检测精确度的前提下,其时间复杂度较C_LOF算法明显降低。
基金the Chinese Academy of Sciences and The World Academy of Sciences for sponsoring this research through the CAS-TWAS President’s Fellowship program
文摘This study is aimed at determining the level of environmental degradation as well as the concentration of trace elements in soil and stream sediments in order to evaluate the environmental impact of the mining operation.Twenty-five(25) soils and ten(10) stream sediment samples were collected from the study area. The physicochemical parameters were determined using appropriate instrumentation with the aid of a digital p H meter(Milwaukee meter) to measure the p H and electrical conductivity, total dissolved solids, moisture content and loss on ignition of the soil and stream sediment samples. The p H of the soil sample ranged from(6.10 to 7.19); Electrical conductivity ranged from(21.3 to 279.4 μS/cm), moisture content varied from(0.60% to 7.20%), and the LOI ranged from(2.03% to 18.62%). The results of the analysis showed that the concentrations of the trace elements in the soils and stream sediment samples were slightly higher than the background values. Plots of the trace elements in stream sediment samples show moderate, consistent decrease downstream except at points where there was mine water discharge into the main river. The pollution levels of heavy metals were examined in stream sediment and soil samples using different assessable indices, such as the enrichment factor, which showed significant-moderate enrichment for Cr, Th, Nb, Zn, Pb, Y and Zr and the geoaccumulation index, which showed practically moderate contamination with Cr, Ni and Sr based on regional background reference values. Geo-accumulation index and contamination index for soils and stream sediment revealed uncontaminated to moderate contamination. Likewise,elements with moderate contamination were Cr, Ni and Sr.The Pearson correlation showed that there were significant positive associations among selected metals in soil and stream sediment samples.
文摘Fish were collected from 39 sites on the main channel and major tributaries of a highly erosive stream, Hotophia Creek. A total of 2,642 specimens representing 38 species were collected between 1986 through 2003. The bluntface shiner Cyprinella camura was the dominant species of fish and when grouped with other cyprinids accounted for 38.0% of the total numbers collected. By weight, Lepisosteusoculatus, Lepomismegalotis, lctiobusbubalus, and Lepomismacrochirus were the dominant species; accounting for 49.9% of the total catch. While more diminutive species such as cyprinids that might be subject to predation by large fish more frequently were found in shallow channels. Fishes with specific habitat requirement such as the pirate perch were found in the middle group of sites, that were disturbed by erosion process but that featured the necessary habitat requirements. Sensitive or intolerant species like the Yazoo darter, creek chubsucker and cyprinids in general were more frequently found in the undisturbed and habitat complex channels. This study supports the hypothesis that geomorphological stream stages are associated with specific communities of fishes.
文摘River Iyiudene is a vital distributary resource in Abakaliki, southeastern Nigeria and conveys an abundant amount of sediments to provincial and residual ecosystems. Although the importance of the river cannot be overemphasized, the geochemistry of its stream sediments is less investigated. Twenty (20) stream sediment samples were taken at the centre of the river channels to represent the entire drainage area well and avoid collapsed bank materials. The stream sediment samples were used to determine the dispersion, contamination status and sources of heavy metal concentrations. Total elemental digestion accompanied this with the use of aqua regia, an admixture of Hydrochloric acid (HCl) and Nitric acid (HNO<sub>3</sub>) in the ratio of 3:1 using the atomic absorption spectrometer (AAS). The heavy metal concentration levels in River Iyiudene were low compared with sediments from Imo River, Gulf of California, Upper continental crust, Average shale and surface horizons, excluding Cd, which showed high concentration levels than the other reference studies. The results delineated a wide contrast in the concentration levels of the heavy metals, with the mean contents in the order Zn > Cu > Pb > Cd > Ni > As. The pollution evaluation utilizing the Effect range low (ERL), Effect range median (ERM), single pollution index, and geo-accumulation index revealed Cd contamination. This study indicates that the heavy metals were sourced from the natural geological background of the river basin and possibly from agricultural runoff and atmospheric pollutants.
文摘In order to study stream sediments in the terahertz range, we have measured six reference stream sediment samples by terahertz time-domain spectroscopy (THz-TDS). We obtained the absorption coefficients and refractive indexes. By analyzing the spectra, we got different drops in amplitude and delays in time. The absorption and refractive properties of samples changed with its components and types. In addition, we also found there was a nearly linear relationship between the absorption coefficient and the frequency. We calculated the slope value (K) of each sample by linear fitting, and find the K was corresponding to the contents of the samples. The results showed THz-TDS was an effective method to the analysis of stream sediments.
文摘The Castelhano Stream Hydrographic Basin, located in the city of Venancio Aires, RS, Brazil, shows an area of 675.3 km2, highlighting the Castelhano Stream as their main water course. The stream is the main responsiblity for the local water supply;however, there are no published studies in the literature regarding their water quality. In this context, the present research aimed to assess the water quality of Castelhano Stream in terms of organic pollution and eutrophication, applying the Biological Water Quality Index (BWQI), which uses epilithic diatoms communities as bioindicators. Biological samples were collected at three sampling stations along the stream in the months of September, November and December 2012. The results showed 81 identified species, distributed in 30 genera. The water pollution levels detected ranged from “strong” (66.7%) and “very strong” (33.3%), with differences in species composition between sampling stations. The sampling station S1 in the upper reaches was characterized by the presence of indicative species of acidophilus and lentic environments with large amounts of organic matter. The sampling stations S2 and S3, in the intermediate and lower reaches, respectively, showed a substitution of species in the community, with the presence of highly tolerant taxa to organic pollution and eutrophication. The high pollution levels detected along the basin are related to the nutrients and high organic load originating from livestock, domestic and industrial waste, as well as excess fertilizers and agricultural inputs used in farming. The results demonstrate the necessity to implement mitigation measures to contain the processes of organic pollution and eutrophication detected due to the dangers offered to public health and the environment.
文摘短视频平台的直播带货已成为当前企业营销获客研究的新热点,如何实现该营销渠道下的精细化营销成为企业亟需解决的问题。该模型融合目标群体指数(Target Group Index,TGI)和自组织映射(Self-Organizing Map,SOM)技术对平台Q公司进行客户细分,研究其细分人群的属性特征和产品服务偏好,并分析了不同产品服务间的相似性。结果表明:Q公司的目标消费群体集中在三线以上城市;十二大产品服务可以划分四类进行组合营销。该研究证实,TGI与SOM的结合可有效地分析人群对产品服务的偏好行为,为企业在营销推广管理过程中根据消费者偏好选择合适直播达人,匹配合适产品服务提供数据决策支持。
