A P-vector method was optimized using variational data assimilation technique, with which the vertical structures and seasonal variations of zonal velocities and transports were investigated. The results showed that w...A P-vector method was optimized using variational data assimilation technique, with which the vertical structures and seasonal variations of zonal velocities and transports were investigated. The results showed that westward and eastward flowes occur in the Luzon Strait in the same period in a year. However the net volume transport is westward. In the upper level (0m -500m),the westward flow exits in the middle and south of the Luzon Strait, and the eastward flow exits in the north. There are two centers of westward flow and one center of eastward flow. In the middle of the Luzon Strait, westward and eastward flowes appear alternately in vertical direction. The westward flow strengthens in winter and weakens in summer. The net volume transport is strong in winter (5.53 Sv) but weak in summer (0.29 Sv). Except in summer, the volume transport in the upper level accounts for more than half of the total volume transport (0m bottom). In summer, the net volume transport in the upper level is eastward (1.01 Sv), but westward underneath.展开更多
Data assimilation of subsurface transport is important in many energy and environmental applications,but its solution is typically challenging.In this work,we build physics-constrained deep learning models to predict ...Data assimilation of subsurface transport is important in many energy and environmental applications,but its solution is typically challenging.In this work,we build physics-constrained deep learning models to predict the full-scale hydraulic conductivity,hydraulic head,and concentration fields in porous media from sparse measure-ment of these observables.The model is developed based on convolutional neural networks with the encoding-decoding process.The model is trained by minimizing a loss function that incorporates residuals of governing equations of subsurface transport instead of using labeled data.Once trained,the model predicts the unknown conductivity,hydraulic head,and concentration fields with an average relative error<10%when the data of these observables is available at 12.2%of the grid points in the porous media.The model has a robust predictive performance for porous media with different conductivities and transport under different Péclet number(0.5<Pe<500).We also quantify the predictive uncertainty of the model and evaluate the reliability of its prediction by incorporating a variational parameter into the model.展开更多
The variational method of data assimilation is used to solve an inverse problem in the transport of sediment in river, which plays an important role in the change of natural environment. The cost function is defined t...The variational method of data assimilation is used to solve an inverse problem in the transport of sediment in river, which plays an important role in the change of natural environment. The cost function is defined to measure the error between model predictions and field observations. The adjoint model of IAP river sedimentation model is created to obtain the gradient of the cost function with respect to control variables. The initial conditions are taken as the control variables; their optimal values can be retrieved by minimizing the cost function with limited memory quasi Newton method (LMQN). The results show that the adjoint method approach can successfully make the model prediction well fit the simulated observations. And it is expected to use this method to solve other inverse problems of river sedimentation. But some numerical problems need to be discussed before applying to real river data.展开更多
选取我国北方薯区主栽的食用型甘薯品种龙薯9号、红香蕉、泰中6号、苏薯8号、遗字138和北京553,于2011—2012年2个生长季在山东农业大学农学试验站进行大田试验,研究不同产量水平甘薯品种光合产物的分配差异及其原因。在甘薯主要生长时...选取我国北方薯区主栽的食用型甘薯品种龙薯9号、红香蕉、泰中6号、苏薯8号、遗字138和北京553,于2011—2012年2个生长季在山东农业大学农学试验站进行大田试验,研究不同产量水平甘薯品种光合产物的分配差异及其原因。在甘薯主要生长时期测定茎蔓各部位蔗糖含量和基部茎粗、在块根膨大过程中对功能叶进行13C标记,探索不同品种13C同化物分配特点,同时研究上述项目与收获指数和块根产量的关系。结果表明,高产品种龙薯9号、红香蕉、泰中6号和苏薯8号产块根均在60 t hm–2左右,而中、低产品种遗字138和北京553产块根在50 t hm–2以下。高产品种的收获指数显著高于中、低产品种。在块根膨大前期高产品种的块根成为光合产物的分配中心,而中、低产品种的块根则在块根膨大后期成为分配中心;在块根膨大前、中期,高产品种13C同化物在块根中的分配比例显著高于中、低产品种,即高产品种光合产物由功能叶向块根的转运能力强于中、低产品种。供试品种茎蔓基部的蔗糖含量均高于顶部,且中、低产品种的蔗糖浓度差大于高产品种;随着甘薯生长发育,中、低产品种茎蔓基部增粗速率高于高产品种。相关分析表明,块根产量与收获指数呈极显著正相关(r=0.98**,2011;r=0.93**,2012);块根13C分配率与块根产量和收获指数均呈显著正相关(0.87*和0.91**,2011;0.92**和0.99**,2012);生长中后期,基部茎粗与块根产量和收获指数均呈显著负相关(–0.78*和–0.83*;–0.88**和–0.95**)。块根成为光合产物分配中心的时间早、光合产物由功能叶向块根的转运能力强是高产品种收获指数显著提高的主要原因,而中、低产品种光合产物由叶片向块根转运能力差的主要原因是块根中光合产物卸载不畅。展开更多
在盆栽试验条件下,选用铜、镉两种金属元素各设置3个浓度水平,即Cu1(100 m g/kg),Cu2(200 m g/kg),Cu3(300 m g/kg)和Cd1(10 m g/kg),Cd2(50 m g/kg),Cd3(100 m g/kg)共6个处理,以不施金属元素处理为对照,研究了Cu,Cd胁迫对冬小麦碳氮...在盆栽试验条件下,选用铜、镉两种金属元素各设置3个浓度水平,即Cu1(100 m g/kg),Cu2(200 m g/kg),Cu3(300 m g/kg)和Cd1(10 m g/kg),Cd2(50 m g/kg),Cd3(100 m g/kg)共6个处理,以不施金属元素处理为对照,研究了Cu,Cd胁迫对冬小麦碳氮运转的影响。结果表明,与对照相比,铜、镉处理降低了小麦叶片、茎鞘、颖壳等营养器官花前贮藏物质再运转量和再运转率以及花前营养器官总运转量和运转率,降低了粒重。其中以Cu2,Cd2处理对叶片影响最大,Cu3,Cd2处理对茎鞘、颖壳穗轴和总运转量影响最大。小麦叶片、茎鞘、颖壳等营养器官花前贮藏氮素再运转量和总运转量随铜、镉施用浓度的增加而降低,籽粒氮素积累量也随之降低,而各营养器官花前贮藏氮素再运转率和总运转率的变化较为复杂。Cu,Cd对籽粒产量、淀粉和蛋白质含量的影响均表现为随施用浓度增加而降低的趋势。展开更多
基金Supported by the Major State Basic Research Program (No. G1999043810) Open Laboratory for Tropical Marine Environmental Dynamics (LED)+2 种基金 South China Sea Institute of Oceanology Chinese Academy of Sciences and the NSFC (No. 40306004).
文摘A P-vector method was optimized using variational data assimilation technique, with which the vertical structures and seasonal variations of zonal velocities and transports were investigated. The results showed that westward and eastward flowes occur in the Luzon Strait in the same period in a year. However the net volume transport is westward. In the upper level (0m -500m),the westward flow exits in the middle and south of the Luzon Strait, and the eastward flow exits in the north. There are two centers of westward flow and one center of eastward flow. In the middle of the Luzon Strait, westward and eastward flowes appear alternately in vertical direction. The westward flow strengthens in winter and weakens in summer. The net volume transport is strong in winter (5.53 Sv) but weak in summer (0.29 Sv). Except in summer, the volume transport in the upper level accounts for more than half of the total volume transport (0m bottom). In summer, the net volume transport in the upper level is eastward (1.01 Sv), but westward underneath.
文摘Data assimilation of subsurface transport is important in many energy and environmental applications,but its solution is typically challenging.In this work,we build physics-constrained deep learning models to predict the full-scale hydraulic conductivity,hydraulic head,and concentration fields in porous media from sparse measure-ment of these observables.The model is developed based on convolutional neural networks with the encoding-decoding process.The model is trained by minimizing a loss function that incorporates residuals of governing equations of subsurface transport instead of using labeled data.Once trained,the model predicts the unknown conductivity,hydraulic head,and concentration fields with an average relative error<10%when the data of these observables is available at 12.2%of the grid points in the porous media.The model has a robust predictive performance for porous media with different conductivities and transport under different Péclet number(0.5<Pe<500).We also quantify the predictive uncertainty of the model and evaluate the reliability of its prediction by incorporating a variational parameter into the model.
文摘The variational method of data assimilation is used to solve an inverse problem in the transport of sediment in river, which plays an important role in the change of natural environment. The cost function is defined to measure the error between model predictions and field observations. The adjoint model of IAP river sedimentation model is created to obtain the gradient of the cost function with respect to control variables. The initial conditions are taken as the control variables; their optimal values can be retrieved by minimizing the cost function with limited memory quasi Newton method (LMQN). The results show that the adjoint method approach can successfully make the model prediction well fit the simulated observations. And it is expected to use this method to solve other inverse problems of river sedimentation. But some numerical problems need to be discussed before applying to real river data.
文摘选取我国北方薯区主栽的食用型甘薯品种龙薯9号、红香蕉、泰中6号、苏薯8号、遗字138和北京553,于2011—2012年2个生长季在山东农业大学农学试验站进行大田试验,研究不同产量水平甘薯品种光合产物的分配差异及其原因。在甘薯主要生长时期测定茎蔓各部位蔗糖含量和基部茎粗、在块根膨大过程中对功能叶进行13C标记,探索不同品种13C同化物分配特点,同时研究上述项目与收获指数和块根产量的关系。结果表明,高产品种龙薯9号、红香蕉、泰中6号和苏薯8号产块根均在60 t hm–2左右,而中、低产品种遗字138和北京553产块根在50 t hm–2以下。高产品种的收获指数显著高于中、低产品种。在块根膨大前期高产品种的块根成为光合产物的分配中心,而中、低产品种的块根则在块根膨大后期成为分配中心;在块根膨大前、中期,高产品种13C同化物在块根中的分配比例显著高于中、低产品种,即高产品种光合产物由功能叶向块根的转运能力强于中、低产品种。供试品种茎蔓基部的蔗糖含量均高于顶部,且中、低产品种的蔗糖浓度差大于高产品种;随着甘薯生长发育,中、低产品种茎蔓基部增粗速率高于高产品种。相关分析表明,块根产量与收获指数呈极显著正相关(r=0.98**,2011;r=0.93**,2012);块根13C分配率与块根产量和收获指数均呈显著正相关(0.87*和0.91**,2011;0.92**和0.99**,2012);生长中后期,基部茎粗与块根产量和收获指数均呈显著负相关(–0.78*和–0.83*;–0.88**和–0.95**)。块根成为光合产物分配中心的时间早、光合产物由功能叶向块根的转运能力强是高产品种收获指数显著提高的主要原因,而中、低产品种光合产物由叶片向块根转运能力差的主要原因是块根中光合产物卸载不畅。
文摘在盆栽试验条件下,选用铜、镉两种金属元素各设置3个浓度水平,即Cu1(100 m g/kg),Cu2(200 m g/kg),Cu3(300 m g/kg)和Cd1(10 m g/kg),Cd2(50 m g/kg),Cd3(100 m g/kg)共6个处理,以不施金属元素处理为对照,研究了Cu,Cd胁迫对冬小麦碳氮运转的影响。结果表明,与对照相比,铜、镉处理降低了小麦叶片、茎鞘、颖壳等营养器官花前贮藏物质再运转量和再运转率以及花前营养器官总运转量和运转率,降低了粒重。其中以Cu2,Cd2处理对叶片影响最大,Cu3,Cd2处理对茎鞘、颖壳穗轴和总运转量影响最大。小麦叶片、茎鞘、颖壳等营养器官花前贮藏氮素再运转量和总运转量随铜、镉施用浓度的增加而降低,籽粒氮素积累量也随之降低,而各营养器官花前贮藏氮素再运转率和总运转率的变化较为复杂。Cu,Cd对籽粒产量、淀粉和蛋白质含量的影响均表现为随施用浓度增加而降低的趋势。
