By using molecular dynamics computer simulation at atomic level, the effects of single dislocation and dipole dislocations on nucleation and growth of martensitic transformation have been studied. It was found that o...By using molecular dynamics computer simulation at atomic level, the effects of single dislocation and dipole dislocations on nucleation and growth of martensitic transformation have been studied. It was found that only the location of tension or compression stress fields of the dislocations are favorable for martensite nucleation in NiAl alloy and the dislocations can move to accommodate partly the transformation strain during the nucleation and growth of martensite. Combined with the molecular dynamics simulation, a two dimensional simulation for martensite morphology based on a dislocation model has been performed. Many factors related to martensitic transformation were considered, such as supercooling, interface energy, shear strain, normal strain and hydrostatic pressure. Different morphologies of martensites, similar to lath, lenticular, thin plate, couple-plate and lenticular couple-plate martensites observed in Fe-C and Fe-Ni-C alloys, were obtained.展开更多
Different slip models were used for prediction of r value of BCC metal sheets from ODF coefficients.According to the maximum plastic work theory developed by Bishop and Hill,it is expected that the higher of Taylor fa...Different slip models were used for prediction of r value of BCC metal sheets from ODF coefficients.According to the maximum plastic work theory developed by Bishop and Hill,it is expected that the higher of Taylor factors given by a slip’ model,the better prediction obtained based on the model.From this point of view,a composed slip model of BCC metals was presented.Based on the model,the agreement of predicted r values for deep drawing steels with experimental ones is excellent.展开更多
全球气候模式BCC-CSM2-MR(Beijing Climate Center-Climate System Model version 2-Medium Resolution)由国家(北京)气候中心自主研发并参与了第六阶段国际耦合模式比较计划,该模式在BCC-CSM1.1m版本基础上对大气辐射传输、深对流过程...全球气候模式BCC-CSM2-MR(Beijing Climate Center-Climate System Model version 2-Medium Resolution)由国家(北京)气候中心自主研发并参与了第六阶段国际耦合模式比较计划,该模式在BCC-CSM1.1m版本基础上对大气辐射传输、深对流过程及重力波等方面进行了优化,因此,该模式对东亚地区降水和气温模拟能力的改进亟需进一步评估。本文主要基于不同格点观测数据集与中国区域站点观测数据,系统对比分析BCC-CSM2-MR、BCC-CSM1.1m两个模式版本对东亚地区季节平均降水(气温)和日极端降水(气温)的模拟能力。结果表明:(1)相比BCC-CSM1.1m,BCC-CSM2-MR改进了对东亚大部分区域季节平均降水的模拟能力,尤其是青藏高原地区夏季平均降水,明显提高了对中国东南地区、朝鲜半岛及日本降水月际变化的模拟性能;(2)BCC-CSM2-MR对东亚地区季节平均气温模拟能力改进不明显,且对东亚大部分区域气温月际变化的模拟误差大于BCC-CSM1.1m;(3)对日极端降水(气温),BCC-CSM2-MR的模拟能力优于BCC-CSM1.1m,明显提高了对中国东南地区日极端降水(气温)的模拟能力。总体而言,BCC-CSM2-MR在深对流过程参数方案中的改进有利于对东亚地区降水的模拟。展开更多
资源的有限性和社会对公交服务需求的日益增长,决定了公交线路的绩效对于整个公交系统的运营和发展具有重要意义.为对常规公交线路网络中的单条公交线路进行绩效评估,本文基于城市公交的属性,即公益性和经营性,构建了单条公交线路绩效...资源的有限性和社会对公交服务需求的日益增长,决定了公交线路的绩效对于整个公交系统的运营和发展具有重要意义.为对常规公交线路网络中的单条公交线路进行绩效评估,本文基于城市公交的属性,即公益性和经营性,构建了单条公交线路绩效评估概念框架.将单条公交线路的服务实现过程分为两个阶段,利用数据包络分析中的面向产出的BCC模型(Banker Charnes Cooper model),计算单条公交线路的运营效率和服务效益.从公交企业和乘客两个角度评估公交线路功能的实现程度,为公交线网的优化设计及政府决策提供参考.最后以泰州市的10条公交线路为例进行了实践应用.展开更多
文摘By using molecular dynamics computer simulation at atomic level, the effects of single dislocation and dipole dislocations on nucleation and growth of martensitic transformation have been studied. It was found that only the location of tension or compression stress fields of the dislocations are favorable for martensite nucleation in NiAl alloy and the dislocations can move to accommodate partly the transformation strain during the nucleation and growth of martensite. Combined with the molecular dynamics simulation, a two dimensional simulation for martensite morphology based on a dislocation model has been performed. Many factors related to martensitic transformation were considered, such as supercooling, interface energy, shear strain, normal strain and hydrostatic pressure. Different morphologies of martensites, similar to lath, lenticular, thin plate, couple-plate and lenticular couple-plate martensites observed in Fe-C and Fe-Ni-C alloys, were obtained.
文摘Different slip models were used for prediction of r value of BCC metal sheets from ODF coefficients.According to the maximum plastic work theory developed by Bishop and Hill,it is expected that the higher of Taylor factors given by a slip’ model,the better prediction obtained based on the model.From this point of view,a composed slip model of BCC metals was presented.Based on the model,the agreement of predicted r values for deep drawing steels with experimental ones is excellent.
文摘全球气候模式BCC-CSM2-MR(Beijing Climate Center-Climate System Model version 2-Medium Resolution)由国家(北京)气候中心自主研发并参与了第六阶段国际耦合模式比较计划,该模式在BCC-CSM1.1m版本基础上对大气辐射传输、深对流过程及重力波等方面进行了优化,因此,该模式对东亚地区降水和气温模拟能力的改进亟需进一步评估。本文主要基于不同格点观测数据集与中国区域站点观测数据,系统对比分析BCC-CSM2-MR、BCC-CSM1.1m两个模式版本对东亚地区季节平均降水(气温)和日极端降水(气温)的模拟能力。结果表明:(1)相比BCC-CSM1.1m,BCC-CSM2-MR改进了对东亚大部分区域季节平均降水的模拟能力,尤其是青藏高原地区夏季平均降水,明显提高了对中国东南地区、朝鲜半岛及日本降水月际变化的模拟性能;(2)BCC-CSM2-MR对东亚地区季节平均气温模拟能力改进不明显,且对东亚大部分区域气温月际变化的模拟误差大于BCC-CSM1.1m;(3)对日极端降水(气温),BCC-CSM2-MR的模拟能力优于BCC-CSM1.1m,明显提高了对中国东南地区日极端降水(气温)的模拟能力。总体而言,BCC-CSM2-MR在深对流过程参数方案中的改进有利于对东亚地区降水的模拟。
文摘资源的有限性和社会对公交服务需求的日益增长,决定了公交线路的绩效对于整个公交系统的运营和发展具有重要意义.为对常规公交线路网络中的单条公交线路进行绩效评估,本文基于城市公交的属性,即公益性和经营性,构建了单条公交线路绩效评估概念框架.将单条公交线路的服务实现过程分为两个阶段,利用数据包络分析中的面向产出的BCC模型(Banker Charnes Cooper model),计算单条公交线路的运营效率和服务效益.从公交企业和乘客两个角度评估公交线路功能的实现程度,为公交线网的优化设计及政府决策提供参考.最后以泰州市的10条公交线路为例进行了实践应用.
