Diversifying crop rotation aims to balance production and ecological concerns.However,yield and water use efficiency(WUE)of crop in diversified rotation systems have not been well documented,especially under limited i...Diversifying crop rotation aims to balance production and ecological concerns.However,yield and water use efficiency(WUE)of crop in diversified rotation systems have not been well documented,especially under limited irrigation.Here,we conducted a 6-year experiment with five treatments:1)wheatmaize cropping system(WM),as control;2)WMME,spring maize→WM rotation;3)WMML,spring millet→WM rotation;4)WMMP,spring peanut→WM rotation;and 5)WMMS,spring soybean→WM rotation,to explore how diversified rotations affected yield and WUE of wheat.Results showed that approximately 60% higher precipitation during wheat growing season in Cycle 1(2015-2017)resulted in yield increases by 33.8%-55.7% compared to those in Cycle 2(2017-2019)and Cycle3(2019-2021).Grain yield and WUE of wheat were 16.7% and 9.6% higher in Cycle 1,81.5% and 86.8% higher in Cycle 2,and 56.1% and 78.7% higher in Cycle 3 on average in diversified rotations compared to those in WM,respectively.Further analysis revealed that spike number and aboveground biomass were the main contributors to the increments,which can be explained by the increased evapotranspiration during the middle-late wheat growth stages(e.g.,regreening,jointing,and anthesis)in diversified rotations.In general,diversified rotations enhanced synchronization of soil water supply with crop water demand by affecting the spatiotemporal dynamics of soil moisture under varied precipitation conditions,thereby increasing yield and WUE of wheat.Hence,diversified spring crops→WM rotations offer a sustainable and efficient strategy for enhancing wheat production and water conservation in dry areas.展开更多
A unified stress function for bi-modulus beams is proposed based on its mechanic sense on the boundary of beams. Elasticity solutions of stress and displacement for bi-modulus beams under combined loads are derived. T...A unified stress function for bi-modulus beams is proposed based on its mechanic sense on the boundary of beams. Elasticity solutions of stress and displacement for bi-modulus beams under combined loads are derived. The example analysis shows that the maximum tensile stress using the same elastic modulus theory is underestimated if the tensile elastic modulus is larger than the compressive elastic modulus. Otherwise, the maximum compressive stress is underestimated. The maximum tensile stress using the material mechanics solution is underestimated when the tensile elastic modulus is larger than the compressive elastic modulus to a certain extent. The error of stress using the material mechanics theory decreases as the span-to-height ratio of beams increases, which is apparent when L/h ≤ 5. The error also varies with the distributed load patterns.展开更多
Programming difficulties are one of the common problems faced by software engineering students,which can lead to a rapid decline in motivation and even drop out.Probing students’programming difficulties is a crucial ...Programming difficulties are one of the common problems faced by software engineering students,which can lead to a rapid decline in motivation and even drop out.Probing students’programming difficulties is a crucial step in understanding their current programming situation and implementing appropriate instructional interventions.However,how to detect students’programming difficulties accurately without students’awareness remains a big challenge.Address the issues above;this paper adopts a sensor-free difficulties detecting method based on a deep neural network which employs a recurrent neural network(RNN)model and uses the sequential timing data from programming behaviour.The method can detect students’programming difficulties in real-time with 93%accuracy without interference in the programming process.In the long term,this method is the first step for establishing an automated intelligent programming environment.At the same time,it can assist teachers in noticing the difficulties that students encounter.Then,teachers can adjust their teaching plans and provide manual tutoring intervention more quickly.展开更多
Network innovation and business transformation are both necessary for telecom operators to adapt to new situations, but operators face challenges in terms of network bearer complexity, business centralization, and IT/...Network innovation and business transformation are both necessary for telecom operators to adapt to new situations, but operators face challenges in terms of network bearer complexity, business centralization, and IT/CT integration. Network function virtualization （NFV） may inspire new development ideas, but many doubts still exist within industry, especially about how to introduce NFV into an operator＇ s network. This article describes the latest progress in NFV standardization, NFV requirements and hot technology issues, and typical NFV applications in an operator networks.展开更多
Dynamic soil−pile−superstructure interaction is crucial for understanding pile behavior in earthquake-prone ground.Evaluating the safety of piles requires determining the seismic bending moment caused by combined iner...Dynamic soil−pile−superstructure interaction is crucial for understanding pile behavior in earthquake-prone ground.Evaluating the safety of piles requires determining the seismic bending moment caused by combined inertial and kinematic interactions,which is challenging.This paper addresses this problem through numerical simulations of piles in different soil sites,considering soil nonlinearity.Results reveal that the period of the soil site significantly affects the interaction among soil,piles,and structures.Bending moments in soft and hard soil sites exceed those in medium soil sites by more than twice.Deformation modes of piles exhibit distinct characteristics between hard and soft soil sites.Soft soil sites exhibit a singular inflection point,while hard soil sites show two inflection points.In soft soil sites,pile-soil kinematic interaction gradually increases bending moment from tip to head,with minor influence from superstructure’s inertial interaction.In hard soil sites,significant inertial effects from soil,even surpassing pile-soil kinematic effects near the tip,lead to reversed superposition bending moment.Superstructure’s inertial interaction notably impacts pile head in hard soil sites.A simplified coupling method is proposed using correlation coefficient to represent inertial and kinematic interactions.These findings provide insights into complex seismic interactions among soil,piles,and structures.展开更多
Global climate models(GCMs)provide valuable forecasts of precipitation around the world.This paper has presented an in-depth investigation of the overlapping versus differing information for 2 sets of GCM forecasts ba...Global climate models(GCMs)provide valuable forecasts of precipitation around the world.This paper has presented an in-depth investigation of the overlapping versus differing information for 2 sets of GCM forecasts based on the classic set operations.Specifically,by using the coefficient of determination to measure the amount of information of precipitation observations contained in GCM forecast,the common part of the 2 sets of forecasts is quantified by the intersection operation and the unique part of 1 set of forecasts is quantified by the difference operation.A case study is devised for the global precipitation forecasts in December-January-February generated by the Seamless System for Prediction and EArth System Research(SPEAR)and the Climate Forecast System version 2(CFSv2).Their overlapping and differing information are diagnosed.It is found that significant information common to the 2 sets of forecasts exists over 54.61%of global land grid cells,significant information unique to SPEAR forecasts over 23.59%of global land grid cells,and significant information unique to CFSv2 forecasts over 18.15%of global land grid cells.While the information unique to the SPEAR forecasts suggests that the SPEAR forecasts provide new information compared to the CFSv2 forecasts and the information unique to the CFSv2 forecasts suggests that the CFSv2 forecasts also provide new information compared to the SPEAR forecasts,the common information of the 2 sets of forecasts indicates that they present substantial amount of similar information.Overall,the diagnosis of the overlapping and differing information for different sets of GCM forecasts yields insights into GCM predictive performances.展开更多
基金supported by the National Natural Science Foundation of China(32172125 and U21A20218)。
文摘Diversifying crop rotation aims to balance production and ecological concerns.However,yield and water use efficiency(WUE)of crop in diversified rotation systems have not been well documented,especially under limited irrigation.Here,we conducted a 6-year experiment with five treatments:1)wheatmaize cropping system(WM),as control;2)WMME,spring maize→WM rotation;3)WMML,spring millet→WM rotation;4)WMMP,spring peanut→WM rotation;and 5)WMMS,spring soybean→WM rotation,to explore how diversified rotations affected yield and WUE of wheat.Results showed that approximately 60% higher precipitation during wheat growing season in Cycle 1(2015-2017)resulted in yield increases by 33.8%-55.7% compared to those in Cycle 2(2017-2019)and Cycle3(2019-2021).Grain yield and WUE of wheat were 16.7% and 9.6% higher in Cycle 1,81.5% and 86.8% higher in Cycle 2,and 56.1% and 78.7% higher in Cycle 3 on average in diversified rotations compared to those in WM,respectively.Further analysis revealed that spike number and aboveground biomass were the main contributors to the increments,which can be explained by the increased evapotranspiration during the middle-late wheat growth stages(e.g.,regreening,jointing,and anthesis)in diversified rotations.In general,diversified rotations enhanced synchronization of soil water supply with crop water demand by affecting the spatiotemporal dynamics of soil moisture under varied precipitation conditions,thereby increasing yield and WUE of wheat.Hence,diversified spring crops→WM rotations offer a sustainable and efficient strategy for enhancing wheat production and water conservation in dry areas.
基金Project supported by the Doctoral Fund of Ministry of Education of China(No.20103108110019)the National Natural Science Foundation of China(No.51208292)the National Key Technology R&D Programs(Nos.2011BAG07B01 and 2012BAK24B04)
文摘A unified stress function for bi-modulus beams is proposed based on its mechanic sense on the boundary of beams. Elasticity solutions of stress and displacement for bi-modulus beams under combined loads are derived. The example analysis shows that the maximum tensile stress using the same elastic modulus theory is underestimated if the tensile elastic modulus is larger than the compressive elastic modulus. Otherwise, the maximum compressive stress is underestimated. The maximum tensile stress using the material mechanics solution is underestimated when the tensile elastic modulus is larger than the compressive elastic modulus to a certain extent. The error of stress using the material mechanics theory decreases as the span-to-height ratio of beams increases, which is apparent when L/h ≤ 5. The error also varies with the distributed load patterns.
基金supported by the 2018-2020 Higher Education Talent Training Quality and Teaching Reform Project of Sichuan Province(Grant No.JG2018-46)the Science and Technology Planning Program of Sichuan University and Luzhou(Grant No.2017CDLZG30)the Postdoctoral Science fund of Sichuan University(Grant No.2019SCU12058).
文摘Programming difficulties are one of the common problems faced by software engineering students,which can lead to a rapid decline in motivation and even drop out.Probing students’programming difficulties is a crucial step in understanding their current programming situation and implementing appropriate instructional interventions.However,how to detect students’programming difficulties accurately without students’awareness remains a big challenge.Address the issues above;this paper adopts a sensor-free difficulties detecting method based on a deep neural network which employs a recurrent neural network(RNN)model and uses the sequential timing data from programming behaviour.The method can detect students’programming difficulties in real-time with 93%accuracy without interference in the programming process.In the long term,this method is the first step for establishing an automated intelligent programming environment.At the same time,it can assist teachers in noticing the difficulties that students encounter.Then,teachers can adjust their teaching plans and provide manual tutoring intervention more quickly.
文摘Network innovation and business transformation are both necessary for telecom operators to adapt to new situations, but operators face challenges in terms of network bearer complexity, business centralization, and IT/CT integration. Network function virtualization （NFV） may inspire new development ideas, but many doubts still exist within industry, especially about how to introduce NFV into an operator＇ s network. This article describes the latest progress in NFV standardization, NFV requirements and hot technology issues, and typical NFV applications in an operator networks.
基金the National Natural Science Foundation of China(Grant No.42277163)for the financial support to this work.
文摘Dynamic soil−pile−superstructure interaction is crucial for understanding pile behavior in earthquake-prone ground.Evaluating the safety of piles requires determining the seismic bending moment caused by combined inertial and kinematic interactions,which is challenging.This paper addresses this problem through numerical simulations of piles in different soil sites,considering soil nonlinearity.Results reveal that the period of the soil site significantly affects the interaction among soil,piles,and structures.Bending moments in soft and hard soil sites exceed those in medium soil sites by more than twice.Deformation modes of piles exhibit distinct characteristics between hard and soft soil sites.Soft soil sites exhibit a singular inflection point,while hard soil sites show two inflection points.In soft soil sites,pile-soil kinematic interaction gradually increases bending moment from tip to head,with minor influence from superstructure’s inertial interaction.In hard soil sites,significant inertial effects from soil,even surpassing pile-soil kinematic effects near the tip,lead to reversed superposition bending moment.Superstructure’s inertial interaction notably impacts pile head in hard soil sites.A simplified coupling method is proposed using correlation coefficient to represent inertial and kinematic interactions.These findings provide insights into complex seismic interactions among soil,piles,and structures.
基金supported by the National Key Research and Development Program of China(2023YFF0804900)the National Natural Science Foundation of China(52379033)the Guangdong Provincial Department of Science and Tech-nology(2019ZT08G090).
文摘Global climate models(GCMs)provide valuable forecasts of precipitation around the world.This paper has presented an in-depth investigation of the overlapping versus differing information for 2 sets of GCM forecasts based on the classic set operations.Specifically,by using the coefficient of determination to measure the amount of information of precipitation observations contained in GCM forecast,the common part of the 2 sets of forecasts is quantified by the intersection operation and the unique part of 1 set of forecasts is quantified by the difference operation.A case study is devised for the global precipitation forecasts in December-January-February generated by the Seamless System for Prediction and EArth System Research(SPEAR)and the Climate Forecast System version 2(CFSv2).Their overlapping and differing information are diagnosed.It is found that significant information common to the 2 sets of forecasts exists over 54.61%of global land grid cells,significant information unique to SPEAR forecasts over 23.59%of global land grid cells,and significant information unique to CFSv2 forecasts over 18.15%of global land grid cells.While the information unique to the SPEAR forecasts suggests that the SPEAR forecasts provide new information compared to the CFSv2 forecasts and the information unique to the CFSv2 forecasts suggests that the CFSv2 forecasts also provide new information compared to the SPEAR forecasts,the common information of the 2 sets of forecasts indicates that they present substantial amount of similar information.Overall,the diagnosis of the overlapping and differing information for different sets of GCM forecasts yields insights into GCM predictive performances.
