Frost heave is an upward swelling of soil during cryogenic conditions in cold regions. It is caused by the accumulation of ice crystals in subgrade soil, which grow upwards when freezing temperatures penetrate into th...Frost heave is an upward swelling of soil during cryogenic conditions in cold regions. It is caused by the accumulation of ice crystals in subgrade soil, which grow upwards when freezing temperatures penetrate into the subgrade. This study establishes the allowable soil subgrade frost heave based on the roughness standard of asphalt pavement in China, and aims to balance the pavement design and frost heave resistance of subgrades in cold regions. We formulated a mechanical model of pavement supported by the boundary conditions of differential frost heave, based on the elastie layered system theory. The differential soil subgrade frost heave was modeled as a sinusoidal function, and the allowable frost heave and the roughness index were modeled as the displacement boundaries for the top and bottom of the pavement structure. Then the allowable frost heave was back-calculated according to the roughness standard. Numerical results show that the allowable frost heave depends on the pavement structure, material properties, the highway grade, and other factors. In order to ensure that the actual soil subgrade frost heave is lower than the allowable frost heave, pavement structures and materials need to be selected and designed carefully. The numerical method proposed here can be applied to establish the frost heave re- sistance of subgrade when the pavement structure and materials are determined.展开更多
The climate data of 84 meteorological stations in Guizhou from 1981 to 2010 was used,including the statistical data of daily precipitation,temperature,sunshine hours,evaporation,frost free period and so on. Using the ...The climate data of 84 meteorological stations in Guizhou from 1981 to 2010 was used,including the statistical data of daily precipitation,temperature,sunshine hours,evaporation,frost free period and so on. Using the equations of light and heat coefficient,light and heat index,latitude and temperature index,active accumulated temperature,effective accumulated temperature,aridity index,and arid-wet index,the red cartridge kiwifruit zoning index of Guizhou was analyzed and studied. The results showed that the zoning index system for the climatic characteristics of Guizhou mountainous area must be established in order to realize the variety regionalization of red cartridge kiwifruit in Guizhou mountainous area,and ten climatic factors were taken as climatic zoning indexes of red cartridge kiwifruit planting,including active accumulated temperature,effective accumulated temperature,annual average temperature,average temperature of July,light and heat coefficient,light and heat index,latitude and temperature index,frost free period,aridity index and arid-wet index. These indicators were giving a comprehensive evaluation for climate suitability conditions of red cartridge kiwifruit planting,and providing the scientific and reasonable basis for the promotion planting of red cartridge kiwifruit in mountain area of Guizhou.展开更多
According to different planting test data,meteorological data,field planting survey and expert interview data in recent years,frost prevention and drought resistance effect of potato under different planting methods w...According to different planting test data,meteorological data,field planting survey and expert interview data in recent years,frost prevention and drought resistance effect of potato under different planting methods were studied using agro-meteorological disaster risk index analysis method. The results showed that the risk index of potato with the full-film planting was small due to good thermal insulation and soil moisture conservation performance. The risk index of potato with half-film planting( flat mulching,ridging planting and furrow planting) was moderate,while that of ridge tillage without mulching,double rows,full of stars and flat planting was large,and their frost prevention and drought resistance effect were poor. It provides support and reference for understanding the frost and drought conditions of potatoes under different planting methods and carrying out insurance weather services for farmers and production managers.展开更多
Frosts are one of the atmospheric phenomena with one of the larger negative effects on the agricultural sector in the southern region of Brazil,therefore,an earlier forecast can minimize their impacts.In the present w...Frosts are one of the atmospheric phenomena with one of the larger negative effects on the agricultural sector in the southern region of Brazil,therefore,an earlier forecast can minimize their impacts.In the present work,artificial neural networks(ANNs)techniques were applied in order to improve the predicting capabilities of frost events in southern Brazil.In the study,two multilayer perceptron(MLP)ANNs were built,one with ADAM optimizer and the other with SGD.The input parameters MLP-ANNs were numerical predictions of the Eta model.The ANNs were trained using four years(2012-2015),while validation and testing were performed using 2016 and 2017,respectively.An episode of frost that occurred on May 21st,2018,related to an intense cold air mass,was also utilized to evaluate the performance of the ANNs.The best configurations(topologies and hyperparameters)of the ANNs were identified through experiments,using the highest accuracy obtained during the validation period as a metric.The results of the ANNs with ADAM and SGD optimizers were compared with the predictions of the Eta model.For the case study,an additional comparison against the operational frost index(IG)from the National Institute for Space Research(INPE)was also included.The performance of both ANNs(properly configured)with ADAM and SGD optimizers are comparable one to the other.And both are significantly better compared to the Eta model.The ANNs were able to drastically reduce the underestimation trends of frost events caused by the warm bias of the Eta model.The ANNs also indicated more satisfactory performances when compared to the INPE IG.In general,the ANNs were able to identify deficiencies in Eta predictions,and consequently improve their results.In this sense,the use of ANNs to predict frost events can be a very useful tool in an operational environment.展开更多
基金supported by the National Key Basic Research Development Plan(No.2012CB026104)the National Science and Technology Support Project(No.2014BAG05B07)+1 种基金the Natural Science Foundation of Heilongjiang Province(No.ZD201218)the National Natural Science Foundation of China(No.51408163)
文摘Frost heave is an upward swelling of soil during cryogenic conditions in cold regions. It is caused by the accumulation of ice crystals in subgrade soil, which grow upwards when freezing temperatures penetrate into the subgrade. This study establishes the allowable soil subgrade frost heave based on the roughness standard of asphalt pavement in China, and aims to balance the pavement design and frost heave resistance of subgrades in cold regions. We formulated a mechanical model of pavement supported by the boundary conditions of differential frost heave, based on the elastie layered system theory. The differential soil subgrade frost heave was modeled as a sinusoidal function, and the allowable frost heave and the roughness index were modeled as the displacement boundaries for the top and bottom of the pavement structure. Then the allowable frost heave was back-calculated according to the roughness standard. Numerical results show that the allowable frost heave depends on the pavement structure, material properties, the highway grade, and other factors. In order to ensure that the actual soil subgrade frost heave is lower than the allowable frost heave, pavement structures and materials need to be selected and designed carefully. The numerical method proposed here can be applied to establish the frost heave re- sistance of subgrade when the pavement structure and materials are determined.
基金Supported by Innovation Driven Project of China Association for Science(2017ZLGC004)Provincial and Municipal Scientific and Technological Cooperation Projects(52020-2015-01-02)Guizhou Science and Technology Plan Project(Qiankehe NY[2012]3020)
文摘The climate data of 84 meteorological stations in Guizhou from 1981 to 2010 was used,including the statistical data of daily precipitation,temperature,sunshine hours,evaporation,frost free period and so on. Using the equations of light and heat coefficient,light and heat index,latitude and temperature index,active accumulated temperature,effective accumulated temperature,aridity index,and arid-wet index,the red cartridge kiwifruit zoning index of Guizhou was analyzed and studied. The results showed that the zoning index system for the climatic characteristics of Guizhou mountainous area must be established in order to realize the variety regionalization of red cartridge kiwifruit in Guizhou mountainous area,and ten climatic factors were taken as climatic zoning indexes of red cartridge kiwifruit planting,including active accumulated temperature,effective accumulated temperature,annual average temperature,average temperature of July,light and heat coefficient,light and heat index,latitude and temperature index,frost free period,aridity index and arid-wet index. These indicators were giving a comprehensive evaluation for climate suitability conditions of red cartridge kiwifruit planting,and providing the scientific and reasonable basis for the promotion planting of red cartridge kiwifruit in mountain area of Guizhou.
基金Supported by the Key Laboratory Project of Arid Areas of China Meteorological Administration in 2018
文摘According to different planting test data,meteorological data,field planting survey and expert interview data in recent years,frost prevention and drought resistance effect of potato under different planting methods were studied using agro-meteorological disaster risk index analysis method. The results showed that the risk index of potato with the full-film planting was small due to good thermal insulation and soil moisture conservation performance. The risk index of potato with half-film planting( flat mulching,ridging planting and furrow planting) was moderate,while that of ridge tillage without mulching,double rows,full of stars and flat planting was large,and their frost prevention and drought resistance effect were poor. It provides support and reference for understanding the frost and drought conditions of potatoes under different planting methods and carrying out insurance weather services for farmers and production managers.
文摘Frosts are one of the atmospheric phenomena with one of the larger negative effects on the agricultural sector in the southern region of Brazil,therefore,an earlier forecast can minimize their impacts.In the present work,artificial neural networks(ANNs)techniques were applied in order to improve the predicting capabilities of frost events in southern Brazil.In the study,two multilayer perceptron(MLP)ANNs were built,one with ADAM optimizer and the other with SGD.The input parameters MLP-ANNs were numerical predictions of the Eta model.The ANNs were trained using four years(2012-2015),while validation and testing were performed using 2016 and 2017,respectively.An episode of frost that occurred on May 21st,2018,related to an intense cold air mass,was also utilized to evaluate the performance of the ANNs.The best configurations(topologies and hyperparameters)of the ANNs were identified through experiments,using the highest accuracy obtained during the validation period as a metric.The results of the ANNs with ADAM and SGD optimizers were compared with the predictions of the Eta model.For the case study,an additional comparison against the operational frost index(IG)from the National Institute for Space Research(INPE)was also included.The performance of both ANNs(properly configured)with ADAM and SGD optimizers are comparable one to the other.And both are significantly better compared to the Eta model.The ANNs were able to drastically reduce the underestimation trends of frost events caused by the warm bias of the Eta model.The ANNs also indicated more satisfactory performances when compared to the INPE IG.In general,the ANNs were able to identify deficiencies in Eta predictions,and consequently improve their results.In this sense,the use of ANNs to predict frost events can be a very useful tool in an operational environment.
