利用光场的高斯-赫米特源项展开法,推导了粒子运动一维方程加三维修正和光场幅度、光束半径、瑞利参数的非线性方程组,编制稳态Matlab FEL code程序,初始粒子加载与国际通用软件Genesis进行对比,吻合很好。新程序对于X射线FEL理论研究...利用光场的高斯-赫米特源项展开法,推导了粒子运动一维方程加三维修正和光场幅度、光束半径、瑞利参数的非线性方程组,编制稳态Matlab FEL code程序,初始粒子加载与国际通用软件Genesis进行对比,吻合很好。新程序对于X射线FEL理论研究的深化,实验装置的设计和改进具有重要意义。展开更多
以某台2.25Cr-1Mo-V钢加氢反应器为例,从工程角度介绍现行设计方法与ASME Code Case 2605-3在反应器设计中的应用,说明过去留有一定余量的设计是设备安全运行的原因之一。探讨了压力和温度载荷对蠕变参数的影响,其中压力对三轴度系数影...以某台2.25Cr-1Mo-V钢加氢反应器为例,从工程角度介绍现行设计方法与ASME Code Case 2605-3在反应器设计中的应用,说明过去留有一定余量的设计是设备安全运行的原因之一。探讨了压力和温度载荷对蠕变参数的影响,其中压力对三轴度系数影响较大,而温度对蠕变松弛影响显著。最后提出在业主非强制要求进行完整分析的前提下,ASME Code Case 2605-3在工程上的简化应用。展开更多
To improve drying uniformity and anthocyanin content of the raspberry puree dried in a continuous microwave dryer,the effects of process parameters(microwave intensity,air velocity,and drying time)on evaluation indexe...To improve drying uniformity and anthocyanin content of the raspberry puree dried in a continuous microwave dryer,the effects of process parameters(microwave intensity,air velocity,and drying time)on evaluation indexes(average temperature,average moisture content,average retention rate of the total anthocyanin content,temperature contrast value,and moisture dispersion value)were investigated via the response surface method(RSM)and the artificial neural network(ANN)with genetic algorithm(GA).The results showed that the microwave intensity and drying time dominated the changes of evaluation indexes.Overall,the ANN model was superior to the RSM model with better estimation ability,and higher drying uniformity and anthocyanin retention rate were achieved for the ANN-GA model compared with RSM.The optimal parameters were microwave intensity of 5.53 W•g^(-1),air velocity of 1.22 m·s^(-1),and drying time of 5.85 min.This study might provide guidance for process optimization of microwave drying berry fruits.展开更多
ASME Code Case 2843(以下简称为“案例”)提供了针对高温工况和交变载荷下承受蠕变和疲劳损伤交互作用的受压元件进行评定的方法。在应用该案例方法的过程中,如不能理解这些方法的技术基础,则可能造成评定结果的不安全。案例中所提出...ASME Code Case 2843(以下简称为“案例”)提供了针对高温工况和交变载荷下承受蠕变和疲劳损伤交互作用的受压元件进行评定的方法。在应用该案例方法的过程中,如不能理解这些方法的技术基础,则可能造成评定结果的不安全。案例中所提出的蠕变-疲劳损伤评定方法主要利用线弹性分析得到的结果对弹塑性材料构成的受压元件进行评定。整套方法包括载荷控制极限的判定、应变控制极限的判定以及蠕变-疲劳损伤极限的判定三个步骤,每个步骤中采用的方法均依据多年来有关研究人员发表文献中的理论和实验结果。拟对案例中所采用方法的技术基础进行分析,为工程中应用案例的方法对承受高温和交变载荷作用的压力容器进行设计提供一定的参考。展开更多
The heat transfer performance of the phase change materials used in free cooling and air conditioning applications is low,due to the poor thermal conductivity of the materials.The recent phenomenal advancement in nano...The heat transfer performance of the phase change materials used in free cooling and air conditioning applications is low,due to the poor thermal conductivity of the materials.The recent phenomenal advancement in nano technology provides an opportunity for an appreciable enhancement in the thermal conductivity of the phase change materials.In order to explore the possibilities of using nano technology for various applications,a detailed parametric study is carried out,to analyse the heat transfer enhancement potential with the thermal conductivity of the conventional phase change materials and nano enhanced phase change materials under various flow conditions of the heat transfer fluid.Initially,the theoretical equation,used to determine the time for outward cylindrical solidification of the phase change material,is validated with the experimental results.It is inferred from the parametric studies,that for paraffinic phase change materials with air as the heat transfer fluid,the first step should be to increase the heat transfer coefficient to the maximum extent,before making any attempt to increase the thermal conductivity of the phase change materials,with the addition of nano particles.When water is used as the phase change material,the addition of nano particles is recommended to achieve better heat transfer,when a liquid is used as the heat transfer fluid.展开更多
文摘以某台2.25Cr-1Mo-V钢加氢反应器为例,从工程角度介绍现行设计方法与ASME Code Case 2605-3在反应器设计中的应用,说明过去留有一定余量的设计是设备安全运行的原因之一。探讨了压力和温度载荷对蠕变参数的影响,其中压力对三轴度系数影响较大,而温度对蠕变松弛影响显著。最后提出在业主非强制要求进行完整分析的前提下,ASME Code Case 2605-3在工程上的简化应用。
基金Supported by the National Natural Science Foundation of China(32072352)。
文摘To improve drying uniformity and anthocyanin content of the raspberry puree dried in a continuous microwave dryer,the effects of process parameters(microwave intensity,air velocity,and drying time)on evaluation indexes(average temperature,average moisture content,average retention rate of the total anthocyanin content,temperature contrast value,and moisture dispersion value)were investigated via the response surface method(RSM)and the artificial neural network(ANN)with genetic algorithm(GA).The results showed that the microwave intensity and drying time dominated the changes of evaluation indexes.Overall,the ANN model was superior to the RSM model with better estimation ability,and higher drying uniformity and anthocyanin retention rate were achieved for the ANN-GA model compared with RSM.The optimal parameters were microwave intensity of 5.53 W•g^(-1),air velocity of 1.22 m·s^(-1),and drying time of 5.85 min.This study might provide guidance for process optimization of microwave drying berry fruits.
文摘ASME Code Case 2843(以下简称为“案例”)提供了针对高温工况和交变载荷下承受蠕变和疲劳损伤交互作用的受压元件进行评定的方法。在应用该案例方法的过程中,如不能理解这些方法的技术基础,则可能造成评定结果的不安全。案例中所提出的蠕变-疲劳损伤评定方法主要利用线弹性分析得到的结果对弹塑性材料构成的受压元件进行评定。整套方法包括载荷控制极限的判定、应变控制极限的判定以及蠕变-疲劳损伤极限的判定三个步骤,每个步骤中采用的方法均依据多年来有关研究人员发表文献中的理论和实验结果。拟对案例中所采用方法的技术基础进行分析,为工程中应用案例的方法对承受高温和交变载荷作用的压力容器进行设计提供一定的参考。
文摘The heat transfer performance of the phase change materials used in free cooling and air conditioning applications is low,due to the poor thermal conductivity of the materials.The recent phenomenal advancement in nano technology provides an opportunity for an appreciable enhancement in the thermal conductivity of the phase change materials.In order to explore the possibilities of using nano technology for various applications,a detailed parametric study is carried out,to analyse the heat transfer enhancement potential with the thermal conductivity of the conventional phase change materials and nano enhanced phase change materials under various flow conditions of the heat transfer fluid.Initially,the theoretical equation,used to determine the time for outward cylindrical solidification of the phase change material,is validated with the experimental results.It is inferred from the parametric studies,that for paraffinic phase change materials with air as the heat transfer fluid,the first step should be to increase the heat transfer coefficient to the maximum extent,before making any attempt to increase the thermal conductivity of the phase change materials,with the addition of nano particles.When water is used as the phase change material,the addition of nano particles is recommended to achieve better heat transfer,when a liquid is used as the heat transfer fluid.
