Using indexes of dryness and wetness in historical record over the recent recent years and rainfall data over the tatest century, the work involves itself with the study of climatological evolution of dryness and wetn...Using indexes of dryness and wetness in historical record over the recent recent years and rainfall data over the tatest century, the work involves itself with the study of climatological evolution of dryness and wetness. periodic variations of climate and interannual laws of variation. The discussion also covers the subjects of effects of El Nino. sunspot, predictors of general circulation on climatic variation of dryness and wetness. There arc main conclusions as follows: (1) The main cyclic variations of climate are 40 and 11 years in Kunming. the former being subject to that of El Nino and the latter to that of sunspots. They are two principal factors for periodic variations of dryness and wetness in Kunming. (2) A close relationship exists between interannual variations and general circulation factors for Kunming. The comprehensive influence as imposed by ENSO and allocations of W.C.E. patterns of circulation in the westerly are ma.tor weather and climate causes for the interannual variations of precipitation in Kunming.展开更多
Precipitation data from 86 observing Stations for the past four decades (from the first operational use to 1994) are used to study and discuss the character of annually mean distribution in Guangdong. Grades of drynes...Precipitation data from 86 observing Stations for the past four decades (from the first operational use to 1994) are used to study and discuss the character of annually mean distribution in Guangdong. Grades of dryness and wetness on a year-to-year basis are determined and preliminary features of dryness and wetness are discussed for the whole of the province and individual regions according to a 5-grade standard of division. The result has shown that there is on an average a rainfall of 1748 mm per year across the province, with four major centers of maxima (of annual rainfall over 2000 mm) at Enping, Qingyuan, Haifeng and Longmen. For the mean across the province, the years 1959. 1 961. 1973.1975, 1991 are anomalously wet and the years 1956, 1963, 1977 and 1991 are anomalously dry. of them, 1973 is the unusually wet year (with the absolute value of precipitation anomaly over twice as large as the standard deviation) and 1956 and 1963 are the usual dry years. For the occurrence frequency of unusually wetness and dryness over individual river valleys in the province, there are more years of dryness in the valleys of the Xijiang and Dongjiang Rivers. More years of wetness in that of the Jianjiang River, and only years of wetness instead of years of dryness in the valleys of Beijiang and Hanjiang Rivers.展开更多
Dryness and wetness variations on different time scales in Shanghai were analyzed using the Standardized Precipitation Index （SPI） based on monthly precipitation data for 1873-2005. The SPI on scales of 3, 6, 12 and...Dryness and wetness variations on different time scales in Shanghai were analyzed using the Standardized Precipitation Index （SPI） based on monthly precipitation data for 1873-2005. The SPI on scales of 3, 6, 12 and 24 months has been calculated. The SPI on 3, 6, 12 and 24 months present 4 wet periods prevailed during 1873-1885, 1904-1923, 1938-1960 and 1983-2005, and 3 dry episodes during 1886-1903, 1924-1937 and 1961-1982. Significant periods of higher wavelet power in the SPI-24 months occurred on the time scales of 2-7-year band in around 1880-1890, 1910-1950 and 1970-1990, and at 8-15-year band in 1920-1960 and 1965-2000 respectively. Periodicities in the SOl and ENSO indices are similar to those in SPI-24 months with little difference, namely, in the SPI-24 months, there are significant periods at the 2-7- and 8-15-year bands during 1930-1940. The periodicity components in individual SPI-24 months, SOl and ENSO indices are more complicated, showing the wetness and dryness variability in Shanghai is controlled by more than one physical factors. The research results indicate that the Shanghai area has experienced dryness and wetness variability on different time scales during the past 133 years.展开更多
In recent years,the winter temperature in southern China decreases year by year,and the phenomenon of freeze-thaw damage is also wide-spread in hydraulic buildings.In this paper,the freezing-thawing cycle tests of ful...In recent years,the winter temperature in southern China decreases year by year,and the phenomenon of freeze-thaw damage is also wide-spread in hydraulic buildings.In this paper,the freezing-thawing cycle tests of fully graded concrete specimens and corresponding wet sieving suitable for climate conditions in southern China were carried out,and the effects of freezing-thaw cycles on the appearance,mass loss,relative dynamic elastic modulus,internal temperature and strain of fully graded concrete and wet sieving concrete were studied.The splitting tensile strength test of concrete specimens with specified salt freezing cycles was carried out,and the relationship between the strength reduction of fully graded concrete and wet sieving concrete specimens and the number of freeze-thaw cycles was analyzed.The results show that with the increase of freeze-thaw cycles,the properties of fully graded concrete and wet sieving concrete degraded,and the degradation of compressive strength was the most significant,followed by the splitting tensile strength.In the initial stage of the freeze-thaw cycles,the degradation of each property was not obvious,and the deterioration rate of each property increased significantly after 100 freeze-thaw cycles.Besides,the relationship between the splitting tensile strength of fully graded concrete and wet sieving concrete and the internal wave velocity after freeze-thaw cycles was established.The test results can provide theoretical basis for the design,repair,maintenance and life prediction of dams and offshore platforms in southern China.展开更多
On the basis of previous research results, the frost resistance of fully graded concrete and small wet sieving concrete specimens was compared and analyzed, and the characteristics and rules of freeze-thaw damage of h...On the basis of previous research results, the frost resistance of fully graded concrete and small wet sieving concrete specimens was compared and analyzed, and the characteristics and rules of freeze-thaw damage of hydraulic fully graded concrete after freeze-thaw cycles were analyzed through freeze-thaw test, impact-echo test, mechanical test and so on. Meanwhile, the damage characteristics of concrete in the salt and water freezing environment were compared. Through the mechanical test, it is found that the mechanical properties of both fully graded concrete and wet sieving concrete decreased to varying degrees after freeze-thaw cycles. The laws of uniaxial compression and tensile strength of concrete varying with the number of freeze-thaw cycles were obtained. The life of concrete after freeze-thaw cycles was predicted, and it is concluded that the life of concrete in the salt freezing environment was only 0.8 times that in the water freezing environment, proving once again that the damage of concrete in the salt freezing environment was more serious than that in the water freezing environment. Therefore, the grade of frost resistance should be improved appropriately for concrete engineering with salt solution. Finally, based on the damage theory and Lemaitre strain equivalence principle, the freeze-thaw damage evolution equation suitable for fully graded concrete was obtained.展开更多
The main soil type, principle contributor of nutrients and available agricultural land in the Hula Valley is the organic Peat. Nevertheless, the relative contribution of Phosphorus from the Hula Valley to the Lake Kin...The main soil type, principle contributor of nutrients and available agricultural land in the Hula Valley is the organic Peat. Nevertheless, the relative contribution of Phosphorus from the Hula Valley to the Lake Kinneret inputs is lower than regional outsourcing. The Nitrogenic matter, mostly Nitrate migration from the Peat soil is significant. The implementation of efficient development is the key factor of Hula Land use. The financial beneficial success of the Hula land use is therefore dependent of Peat soil properties. The porosity of the Peat Soil is high and preferential pathway volume is low and Hydraulic Conductivity is therefore low. Consequently, the Mobile Spray Irrigation line was found as most suitable for cultivation in Peat Soil. Enhancement of Summer irrigation creating moisture elevation reduces Phosphorus migration from Peat Soil and is therefore recommended and recently implemented.展开更多
ABSTRACT: The present study reconstructs an annual dry/wet grade series from 960 A. D. to 1992 A. D. in the Tai-hu drainage basin of eastern coast, China by collecting historical climatic records, to examine the clima...ABSTRACT: The present study reconstructs an annual dry/wet grade series from 960 A. D. to 1992 A. D. in the Tai-hu drainage basin of eastern coast, China by collecting historical climatic records, to examine the climate periodicity and climate jumps. Power Spectrum analysis reveals that the dry/wet climate in the study area was a superposed phenomenon with the major period of quasi-100-year, and several other notable periods. These periods were supposed to be closely linked with the celestial activity. Climate jumps are detected using moving t-test. The two abrupt changes around 1247 - 1263 A. D. and 1618 - 1635 A. D. are proved as regional events. The 14th to 15th century appeared as the wettest period during the last 1000 years in the Taihu drainage basin. These are interpreted as the consequence of east Asia climate change.展开更多
文摘Using indexes of dryness and wetness in historical record over the recent recent years and rainfall data over the tatest century, the work involves itself with the study of climatological evolution of dryness and wetness. periodic variations of climate and interannual laws of variation. The discussion also covers the subjects of effects of El Nino. sunspot, predictors of general circulation on climatic variation of dryness and wetness. There arc main conclusions as follows: (1) The main cyclic variations of climate are 40 and 11 years in Kunming. the former being subject to that of El Nino and the latter to that of sunspots. They are two principal factors for periodic variations of dryness and wetness in Kunming. (2) A close relationship exists between interannual variations and general circulation factors for Kunming. The comprehensive influence as imposed by ENSO and allocations of W.C.E. patterns of circulation in the westerly are ma.tor weather and climate causes for the interannual variations of precipitation in Kunming.
文摘Precipitation data from 86 observing Stations for the past four decades (from the first operational use to 1994) are used to study and discuss the character of annually mean distribution in Guangdong. Grades of dryness and wetness on a year-to-year basis are determined and preliminary features of dryness and wetness are discussed for the whole of the province and individual regions according to a 5-grade standard of division. The result has shown that there is on an average a rainfall of 1748 mm per year across the province, with four major centers of maxima (of annual rainfall over 2000 mm) at Enping, Qingyuan, Haifeng and Longmen. For the mean across the province, the years 1959. 1 961. 1973.1975, 1991 are anomalously wet and the years 1956, 1963, 1977 and 1991 are anomalously dry. of them, 1973 is the unusually wet year (with the absolute value of precipitation anomaly over twice as large as the standard deviation) and 1956 and 1963 are the usual dry years. For the occurrence frequency of unusually wetness and dryness over individual river valleys in the province, there are more years of dryness in the valleys of the Xijiang and Dongjiang Rivers. More years of wetness in that of the Jianjiang River, and only years of wetness instead of years of dryness in the valleys of Beijiang and Hanjiang Rivers.
基金Frontier Project of Nanjing Institute of Geography and Limnology,CAS, No.CXNIGLAS200814National Forestry Science and Technique Foundation during the 11th Five-Year Plan Period,No.2006BAD03A1601+1 种基金Project of Huaihe River Basin,No.HRM200708National Climate Center,China Meteorological Administration, No.CCSF2007-35
文摘Dryness and wetness variations on different time scales in Shanghai were analyzed using the Standardized Precipitation Index （SPI） based on monthly precipitation data for 1873-2005. The SPI on scales of 3, 6, 12 and 24 months has been calculated. The SPI on 3, 6, 12 and 24 months present 4 wet periods prevailed during 1873-1885, 1904-1923, 1938-1960 and 1983-2005, and 3 dry episodes during 1886-1903, 1924-1937 and 1961-1982. Significant periods of higher wavelet power in the SPI-24 months occurred on the time scales of 2-7-year band in around 1880-1890, 1910-1950 and 1970-1990, and at 8-15-year band in 1920-1960 and 1965-2000 respectively. Periodicities in the SOl and ENSO indices are similar to those in SPI-24 months with little difference, namely, in the SPI-24 months, there are significant periods at the 2-7- and 8-15-year bands during 1930-1940. The periodicity components in individual SPI-24 months, SOl and ENSO indices are more complicated, showing the wetness and dryness variability in Shanghai is controlled by more than one physical factors. The research results indicate that the Shanghai area has experienced dryness and wetness variability on different time scales during the past 133 years.
文摘In recent years,the winter temperature in southern China decreases year by year,and the phenomenon of freeze-thaw damage is also wide-spread in hydraulic buildings.In this paper,the freezing-thawing cycle tests of fully graded concrete specimens and corresponding wet sieving suitable for climate conditions in southern China were carried out,and the effects of freezing-thaw cycles on the appearance,mass loss,relative dynamic elastic modulus,internal temperature and strain of fully graded concrete and wet sieving concrete were studied.The splitting tensile strength test of concrete specimens with specified salt freezing cycles was carried out,and the relationship between the strength reduction of fully graded concrete and wet sieving concrete specimens and the number of freeze-thaw cycles was analyzed.The results show that with the increase of freeze-thaw cycles,the properties of fully graded concrete and wet sieving concrete degraded,and the degradation of compressive strength was the most significant,followed by the splitting tensile strength.In the initial stage of the freeze-thaw cycles,the degradation of each property was not obvious,and the deterioration rate of each property increased significantly after 100 freeze-thaw cycles.Besides,the relationship between the splitting tensile strength of fully graded concrete and wet sieving concrete and the internal wave velocity after freeze-thaw cycles was established.The test results can provide theoretical basis for the design,repair,maintenance and life prediction of dams and offshore platforms in southern China.
文摘On the basis of previous research results, the frost resistance of fully graded concrete and small wet sieving concrete specimens was compared and analyzed, and the characteristics and rules of freeze-thaw damage of hydraulic fully graded concrete after freeze-thaw cycles were analyzed through freeze-thaw test, impact-echo test, mechanical test and so on. Meanwhile, the damage characteristics of concrete in the salt and water freezing environment were compared. Through the mechanical test, it is found that the mechanical properties of both fully graded concrete and wet sieving concrete decreased to varying degrees after freeze-thaw cycles. The laws of uniaxial compression and tensile strength of concrete varying with the number of freeze-thaw cycles were obtained. The life of concrete after freeze-thaw cycles was predicted, and it is concluded that the life of concrete in the salt freezing environment was only 0.8 times that in the water freezing environment, proving once again that the damage of concrete in the salt freezing environment was more serious than that in the water freezing environment. Therefore, the grade of frost resistance should be improved appropriately for concrete engineering with salt solution. Finally, based on the damage theory and Lemaitre strain equivalence principle, the freeze-thaw damage evolution equation suitable for fully graded concrete was obtained.
文摘The main soil type, principle contributor of nutrients and available agricultural land in the Hula Valley is the organic Peat. Nevertheless, the relative contribution of Phosphorus from the Hula Valley to the Lake Kinneret inputs is lower than regional outsourcing. The Nitrogenic matter, mostly Nitrate migration from the Peat soil is significant. The implementation of efficient development is the key factor of Hula Land use. The financial beneficial success of the Hula land use is therefore dependent of Peat soil properties. The porosity of the Peat Soil is high and preferential pathway volume is low and Hydraulic Conductivity is therefore low. Consequently, the Mobile Spray Irrigation line was found as most suitable for cultivation in Peat Soil. Enhancement of Summer irrigation creating moisture elevation reduces Phosphorus migration from Peat Soil and is therefore recommended and recently implemented.
基金Under the auspices of Youth Innovation Foundation of East China Normal University,China.
文摘ABSTRACT: The present study reconstructs an annual dry/wet grade series from 960 A. D. to 1992 A. D. in the Tai-hu drainage basin of eastern coast, China by collecting historical climatic records, to examine the climate periodicity and climate jumps. Power Spectrum analysis reveals that the dry/wet climate in the study area was a superposed phenomenon with the major period of quasi-100-year, and several other notable periods. These periods were supposed to be closely linked with the celestial activity. Climate jumps are detected using moving t-test. The two abrupt changes around 1247 - 1263 A. D. and 1618 - 1635 A. D. are proved as regional events. The 14th to 15th century appeared as the wettest period during the last 1000 years in the Taihu drainage basin. These are interpreted as the consequence of east Asia climate change.
