To deal with the problems concerning the shore boundary, moving boundary and engineering boundary which are encountered frequently in 2D tidal current simulation by the finite difference method, the concept of line bo...To deal with the problems concerning the shore boundary, moving boundary and engineering boundary which are encountered frequently in 2D tidal current simulation by the finite difference method, the concept of line boundary is introduced and studied here, and then the line boundary technique in common use is proposed in this paper. Analysis of some calculation cases shows that this technique is practical, effective, and simple in 2D tidal current simulation involving different boundaries.展开更多
The near crack line field analysis method has been used io investigate into theexact elastic-plastic solutions of a mode II crack under plane stress condilion in anelastic-perfectly plastic solid. The assumptions of t...The near crack line field analysis method has been used io investigate into theexact elastic-plastic solutions of a mode II crack under plane stress condilion in anelastic-perfectly plastic solid. The assumptions of the usual small scale yielding theory.hare been completely. dbandoned and the correct formulations of matching conditionsat the elaslic-plastic boundary. have been given. By, matching the general solution ofthe plastic slress field (bul not the special solution used to be adopted) with the exactelastic stress field (but not the crack tip K-dominant field) at the elastic-plasticboundary, near the crack line, the plastic stresses. the length of the plastic =one and theunit normal vector of the elastic-plastic boundary.which are sufficiently precise near the crack line region ,have been given.展开更多
The near crack line field analysis method has been used to investigate into the exact elastic-plastic solutions of a mode Ⅱ crack under plane stress condition in anelastic-perfectly plastic solid. The assumptions of ...The near crack line field analysis method has been used to investigate into the exact elastic-plastic solutions of a mode Ⅱ crack under plane stress condition in anelastic-perfectly plastic solid. The assumptions of the usual small scale yielding theoryhave been completely. dbandoned and the correct .formulations of matching conditionsat the elastic-plastic boundary have been given. By matching the general solution of the plastic stress field (but not the special solution used to be adopted) will the exactelastic stress field (but not the crack tip K-dominant field) at the elastic-plasticboundary. near the crack line, the plastic .stresses, the length of the plastic zone and theunit normal vector of the elaslic-plastic boundary. which sufficiently precise nearthe crack line region, hare been given.展开更多
Agriculture faces the dual challenges of food security and environmental sustainability.Here,we investigate current maize production at the field scale,analyze the yield gaps and impacting factors,and recommend measur...Agriculture faces the dual challenges of food security and environmental sustainability.Here,we investigate current maize production at the field scale,analyze the yield gaps and impacting factors,and recommend measures for sustainably closing yield gaps.An experiment was conducted on a 3.9-ha maize seed production field in arid north-west China,managed with border and drip irrigation,respectively,in 2015 and 2016.The relative yield reached 70%in both years.However,drip irrigation saved 227 mm irrigation water during a drier growing season compared with traditional border irrigation,accounting for 44%of the maize evapotranspiration(ET).Yield variability under drip irrigation was12.1%,lower than the 18.8%under border irrigation.Boundary line analysis indicates that a relative yield increase of 8%to 10%might be obtained by optimizing the yield-limiting factors.Plant density and soil available water content and available nitrogen were the three major factors involved.In conclusion,closing yield gaps with agricultural sustainability may be realized by optimizing agronomic,irrigation and fertilizer management,using water-saving irrigation methods and using site-specific management.展开更多
基金National Natural Science Foundation of China(Grant No.49236120)
文摘To deal with the problems concerning the shore boundary, moving boundary and engineering boundary which are encountered frequently in 2D tidal current simulation by the finite difference method, the concept of line boundary is introduced and studied here, and then the line boundary technique in common use is proposed in this paper. Analysis of some calculation cases shows that this technique is practical, effective, and simple in 2D tidal current simulation involving different boundaries.
文摘The near crack line field analysis method has been used io investigate into theexact elastic-plastic solutions of a mode II crack under plane stress condilion in anelastic-perfectly plastic solid. The assumptions of the usual small scale yielding theory.hare been completely. dbandoned and the correct formulations of matching conditionsat the elaslic-plastic boundary. have been given. By, matching the general solution ofthe plastic slress field (bul not the special solution used to be adopted) with the exactelastic stress field (but not the crack tip K-dominant field) at the elastic-plasticboundary, near the crack line, the plastic stresses. the length of the plastic =one and theunit normal vector of the elastic-plastic boundary.which are sufficiently precise near the crack line region ,have been given.
文摘The near crack line field analysis method has been used to investigate into the exact elastic-plastic solutions of a mode Ⅱ crack under plane stress condition in anelastic-perfectly plastic solid. The assumptions of the usual small scale yielding theoryhave been completely. dbandoned and the correct .formulations of matching conditionsat the elastic-plastic boundary have been given. By matching the general solution of the plastic stress field (but not the special solution used to be adopted) will the exactelastic stress field (but not the crack tip K-dominant field) at the elastic-plasticboundary. near the crack line, the plastic .stresses, the length of the plastic zone and theunit normal vector of the elaslic-plastic boundary. which sufficiently precise nearthe crack line region, hare been given.
基金funded by the National Natural Science Foundation of China(51725904,51621061,51861125103)the Discipline Innovative Engineering Plan(111 Program,B14002)。
文摘Agriculture faces the dual challenges of food security and environmental sustainability.Here,we investigate current maize production at the field scale,analyze the yield gaps and impacting factors,and recommend measures for sustainably closing yield gaps.An experiment was conducted on a 3.9-ha maize seed production field in arid north-west China,managed with border and drip irrigation,respectively,in 2015 and 2016.The relative yield reached 70%in both years.However,drip irrigation saved 227 mm irrigation water during a drier growing season compared with traditional border irrigation,accounting for 44%of the maize evapotranspiration(ET).Yield variability under drip irrigation was12.1%,lower than the 18.8%under border irrigation.Boundary line analysis indicates that a relative yield increase of 8%to 10%might be obtained by optimizing the yield-limiting factors.Plant density and soil available water content and available nitrogen were the three major factors involved.In conclusion,closing yield gaps with agricultural sustainability may be realized by optimizing agronomic,irrigation and fertilizer management,using water-saving irrigation methods and using site-specific management.
