As only a little information can be obtained from torpedo's lake and sea tests,and the torpedo's life does not distribute typically. If conventional methods are used to convert the environment factor for torpe...As only a little information can be obtained from torpedo's lake and sea tests,and the torpedo's life does not distribute typically. If conventional methods are used to convert the environment factor for torpedo's lake and sea tests,their results can not reflect the actual conditions. A conversion model of the environment factor for torpedo's lake and sea tests is set up based on the GM(1,2) model of the grey system theory. For the merit of the grey system,the problem of uncertain life distributions and few samples can be solved. The calculation results show that the method is easy,realistic and high precise.展开更多
The micronucleus(MCN) test of Vicia faba root tip cell was used to screen the water quality of the Taihu Lake. The MCN ‰ and the pollution index ( PI ) were examined and the F test was carried out to ev...The micronucleus(MCN) test of Vicia faba root tip cell was used to screen the water quality of the Taihu Lake. The MCN ‰ and the pollution index ( PI ) were examined and the F test was carried out to evaluate the statistical difference in mean MCN ‰ among various samples. There were significant difference among thirty nine samples and there were six sites whose PI values are above 2. The authors suggest that the Taihu Lake has partly been polluted to different degrees and the whole water body can be divided into three types. Ames tests were then conducted to detect mutagenicity at five significant sites. The results showed that rivers flowing through urban area carried large amount of mutagenic pollutants into the lake and these pollutants contaminated the source of main waterworks.展开更多
Long-term monthly precipitation data from 1960 to 2008 at 17 rain stations are analyzed to explore spatio-temporal variation of the seasonal and annual precipitation in the Poyang Lake basin, China, using anomaly anal...Long-term monthly precipitation data from 1960 to 2008 at 17 rain stations are analyzed to explore spatio-temporal variation of the seasonal and annual precipitation in the Poyang Lake basin, China, using anomaly analysis, simple linear regressive technique, Mann-Kendall trend test and Continuous Wavelet Transform. The results indicate that: (1) increasing precipitation trend is observed in summer and winter, while decreasing precipitation trend is identified in spring and autumn, and the above mentioned precipitation trends are not statistically significant;(2) changing trend of the areal average annual precipitation is non-significantly increasing, and increasing trend happens in almost the whole basin except in western and south-eastern small parts;(3) the spatial distribution of the seasonal and annual precipitation anomalies between 1991-2008 and 1960-2008 is similar to that of seasonal and annual precipitation trend during 1960-2008;(4) three main time-frequency distributions are observed in annual precipitation series during 1960- 2008, and they are 18 - 26 years, 8 - 14 years and 2 - 8 years, respectively;accordingly, there are three main periods in annual precipitation series, and they are 11-year, 22-year and 5-year respectively. This result will be helpful for further research on availability, scientific management and assessment of the water resources of the Poyang Lake basin.展开更多
Lake Michigan, the sixth largest freshwater lake in the world by surface area, was utilized as a water body for assessment. Field data collected at sampling sites throughout the lake in an intensive monitoring effort ...Lake Michigan, the sixth largest freshwater lake in the world by surface area, was utilized as a water body for assessment. Field data collected at sampling sites throughout the lake in an intensive monitoring effort were utilized for evaluation of the distribution of sediment measurements. An assessment of sediment nutrient and carbon measurements within Lake Michigan was completed to recognize strata resulting from the hydrodynamics of the system. Nonparametric comparison tests revealed that significant differences exist between measurements of sediment nutrients and organic carbon in the lake using strata based upon water column depth (all results demon-strated a p < 0.05, α = 0.05). Cross-validation analysis was applied to the field-collected samples, revealing that large errors occur when estimating sediment flux of carbon or nutrients at a given location in the lake without considering stratification of the distributions of these measurements. Errors in estimating sediment concentrations of nutrients and carbon specific to a location in the lake demonstrated a statistically significant increase when stratification of sediment measurements wasn’t employed among sites. For example, distributions of errors in estimating all nutrients and organic carbon concentrations, whereby distance squared inverse interpolation methods were applied, demonstrated a statistically significant increase in absence of stratification (all p < 0.001, α = 0.05). These results have implications for characterization, monitoring, and modeling sediment and water interaction as related to eutrophication, as well as to contaminant exposure and bioaccumulation for chemicals within Lake Michigan and large water bodies where stratification of the sediment based upon physics of the system exists.展开更多
Extreme meteorological and hydrological events may cause major disasters and heavy social and economic losses. Therefore, more and more studies have focused on extreme hydro-meteorological events in various climates a...Extreme meteorological and hydrological events may cause major disasters and heavy social and economic losses. Therefore, more and more studies have focused on extreme hydro-meteorological events in various climates and geographic regions. Based on nearly 50 years of observed records of the Poyang Lake Basin, the occurrence and changing trends of extreme streamflow indices, including the annual maximum flow, annual peak-over-threshold flows, and low flows, were analyzed for ten hydrological stations. The results indicate that most annual maximum flows occurred from April to July, highly attributed to the Southeast Asian summer monsoons, whereas the annual minimum flows were concentrated between January and February. As for the low flow indices （the annual minimum flow, annual minimum 7-d flow, and annual minimum 30-d flow）, a significant increasing trend was detected in most parts of the Poyang Lake Basin. The trends illustrate the potential effects of climate change and human activities on the hydrological cycle over the Poyang Lake Basin.展开更多
This paper researches on a kind of control architecture for autonomous undelwater vehicle （AUV）. After describing the hybrid property of the AUV control system, we present the hierarchical AUV control architecture. ...This paper researches on a kind of control architecture for autonomous undelwater vehicle （AUV）. After describing the hybrid property of the AUV control system, we present the hierarchical AUV control architecture. The architecture is organized in three layers： mission layer, task layer and execution layer. State supervisor and task coordinator are two key modules handling discrete events, so we describe these two modules in detail. Finally, we carried out a series of tests to verify this architecture The test results show that the AUV can perform autonomous missions effectively and safely. We can conclude the control architecture is valid and practical.展开更多
文摘As only a little information can be obtained from torpedo's lake and sea tests,and the torpedo's life does not distribute typically. If conventional methods are used to convert the environment factor for torpedo's lake and sea tests,their results can not reflect the actual conditions. A conversion model of the environment factor for torpedo's lake and sea tests is set up based on the GM(1,2) model of the grey system theory. For the merit of the grey system,the problem of uncertain life distributions and few samples can be solved. The calculation results show that the method is easy,realistic and high precise.
文摘The micronucleus(MCN) test of Vicia faba root tip cell was used to screen the water quality of the Taihu Lake. The MCN ‰ and the pollution index ( PI ) were examined and the F test was carried out to evaluate the statistical difference in mean MCN ‰ among various samples. There were significant difference among thirty nine samples and there were six sites whose PI values are above 2. The authors suggest that the Taihu Lake has partly been polluted to different degrees and the whole water body can be divided into three types. Ames tests were then conducted to detect mutagenicity at five significant sites. The results showed that rivers flowing through urban area carried large amount of mutagenic pollutants into the lake and these pollutants contaminated the source of main waterworks.
文摘Long-term monthly precipitation data from 1960 to 2008 at 17 rain stations are analyzed to explore spatio-temporal variation of the seasonal and annual precipitation in the Poyang Lake basin, China, using anomaly analysis, simple linear regressive technique, Mann-Kendall trend test and Continuous Wavelet Transform. The results indicate that: (1) increasing precipitation trend is observed in summer and winter, while decreasing precipitation trend is identified in spring and autumn, and the above mentioned precipitation trends are not statistically significant;(2) changing trend of the areal average annual precipitation is non-significantly increasing, and increasing trend happens in almost the whole basin except in western and south-eastern small parts;(3) the spatial distribution of the seasonal and annual precipitation anomalies between 1991-2008 and 1960-2008 is similar to that of seasonal and annual precipitation trend during 1960-2008;(4) three main time-frequency distributions are observed in annual precipitation series during 1960- 2008, and they are 18 - 26 years, 8 - 14 years and 2 - 8 years, respectively;accordingly, there are three main periods in annual precipitation series, and they are 11-year, 22-year and 5-year respectively. This result will be helpful for further research on availability, scientific management and assessment of the water resources of the Poyang Lake basin.
文摘Lake Michigan, the sixth largest freshwater lake in the world by surface area, was utilized as a water body for assessment. Field data collected at sampling sites throughout the lake in an intensive monitoring effort were utilized for evaluation of the distribution of sediment measurements. An assessment of sediment nutrient and carbon measurements within Lake Michigan was completed to recognize strata resulting from the hydrodynamics of the system. Nonparametric comparison tests revealed that significant differences exist between measurements of sediment nutrients and organic carbon in the lake using strata based upon water column depth (all results demon-strated a p < 0.05, α = 0.05). Cross-validation analysis was applied to the field-collected samples, revealing that large errors occur when estimating sediment flux of carbon or nutrients at a given location in the lake without considering stratification of the distributions of these measurements. Errors in estimating sediment concentrations of nutrients and carbon specific to a location in the lake demonstrated a statistically significant increase when stratification of sediment measurements wasn’t employed among sites. For example, distributions of errors in estimating all nutrients and organic carbon concentrations, whereby distance squared inverse interpolation methods were applied, demonstrated a statistically significant increase in absence of stratification (all p < 0.001, α = 0.05). These results have implications for characterization, monitoring, and modeling sediment and water interaction as related to eutrophication, as well as to contaminant exposure and bioaccumulation for chemicals within Lake Michigan and large water bodies where stratification of the sediment based upon physics of the system exists.
基金supported by the National Basic Research Program of China (the 973 Program,Grant No.2007CB407203)the Chinese Postdoctoral Science Fund Project (Grant No. 20110490402)
文摘Extreme meteorological and hydrological events may cause major disasters and heavy social and economic losses. Therefore, more and more studies have focused on extreme hydro-meteorological events in various climates and geographic regions. Based on nearly 50 years of observed records of the Poyang Lake Basin, the occurrence and changing trends of extreme streamflow indices, including the annual maximum flow, annual peak-over-threshold flows, and low flows, were analyzed for ten hydrological stations. The results indicate that most annual maximum flows occurred from April to July, highly attributed to the Southeast Asian summer monsoons, whereas the annual minimum flows were concentrated between January and February. As for the low flow indices （the annual minimum flow, annual minimum 7-d flow, and annual minimum 30-d flow）, a significant increasing trend was detected in most parts of the Poyang Lake Basin. The trends illustrate the potential effects of climate change and human activities on the hydrological cycle over the Poyang Lake Basin.
文摘This paper researches on a kind of control architecture for autonomous undelwater vehicle （AUV）. After describing the hybrid property of the AUV control system, we present the hierarchical AUV control architecture. The architecture is organized in three layers： mission layer, task layer and execution layer. State supervisor and task coordinator are two key modules handling discrete events, so we describe these two modules in detail. Finally, we carried out a series of tests to verify this architecture The test results show that the AUV can perform autonomous missions effectively and safely. We can conclude the control architecture is valid and practical.
