Research has been conducted about the hardness prediction for the carburizing and quenching process based on an optimized hardness simulation model,in accordance with the calculation rule of mixed phases.The coupling ...Research has been conducted about the hardness prediction for the carburizing and quenching process based on an optimized hardness simulation model,in accordance with the calculation rule of mixed phases.The coupling field model incorporates carburizing field analysis,temperature field analysis,phase transformation kinetics analysis and a modified hardness calculation model.In determination of the calculation model for hardness,calculation equations are given to be applied to low carbon content(x(C)<0.5%) for the child phases and the martensite hardness is calculated for high carbon content(x(C)>0.5%) in alloy.Then,the complete carburizing-quenching hardness calculation model is built,and the hardness simulation data are corrected considering the influence of residual austenite(RA) on hardness.Hardness simulations of the carburizing and quenching process of 17CrNiMo6 samples have been performed using DEFORM-HT_V10.2 and MATLAB R2013 a.Finally,a series of comparisons of simulation results and measured values show a good agreement between them,which validates the accuracy of the proposed mathematical model.展开更多
为提高现有作物生长模型单产模拟精度,明确土壤水分供需变化与产量之间的动态关系,该研究构建了水文—作物生长耦合模型SWAT-EPIC(soil and water assessment tool-environmental policy integrated climate)。基于参数敏感性优化的扩...为提高现有作物生长模型单产模拟精度,明确土壤水分供需变化与产量之间的动态关系,该研究构建了水文—作物生长耦合模型SWAT-EPIC(soil and water assessment tool-environmental policy integrated climate)。基于参数敏感性优化的扩展傅里叶幅度敏感性检验算法(extended fourier amplitude sensitivity test,E-FAST),在陕北黄土高原建立包含土壤碳动态评估的苹果单产评估体系。结果表明,优化后的模型在旱作苹果单产的模拟精度误差减少了38.98%,模拟RMSE=2.56%,RRMSE≈9.8%,具有良好的模拟性能。降水对果园浅层土壤水分补给具有直接作用,而深层水分持续消耗加剧干旱胁迫,成为限制苹果单产提升的关键因素。此外,农地改种果园后0~10m土壤有机碳储量提升了14.85%。本研究表明,通过整合水文过程与作物生长机制,SWAT-EPIC耦合模型能够更全面反演区域水分与产量的响应关系,为干旱区果园水分管理与可持续高产提供科学依据。展开更多
基金Projects(51535012,U1604255)supported by the National Natural Science Foundation of ChinaProject(2016JC2001)supported by the Key Research and Development Program of Hunan Province,China
文摘Research has been conducted about the hardness prediction for the carburizing and quenching process based on an optimized hardness simulation model,in accordance with the calculation rule of mixed phases.The coupling field model incorporates carburizing field analysis,temperature field analysis,phase transformation kinetics analysis and a modified hardness calculation model.In determination of the calculation model for hardness,calculation equations are given to be applied to low carbon content(x(C)<0.5%) for the child phases and the martensite hardness is calculated for high carbon content(x(C)>0.5%) in alloy.Then,the complete carburizing-quenching hardness calculation model is built,and the hardness simulation data are corrected considering the influence of residual austenite(RA) on hardness.Hardness simulations of the carburizing and quenching process of 17CrNiMo6 samples have been performed using DEFORM-HT_V10.2 and MATLAB R2013 a.Finally,a series of comparisons of simulation results and measured values show a good agreement between them,which validates the accuracy of the proposed mathematical model.
文摘为探究碳含量、稳定碳同位素比值(δ^(13)C)与塑料薄膜降解性的关系,在各平台收集了89个市售塑料薄膜制品,按种类将其分为纯PE薄膜(Polyethylene Films,PEF)、降解助剂添加型薄膜(Degradation Aid-added Films,DAF)、生物基薄膜(Bio-based Films,BF)、混合基薄膜(Mixed Films,MF)。用热水、稀盐酸、过氧化氢对其逐级处理后,测定原样和逐级处理后残余物的碳含量和δ^(13)C值。结果表明,薄膜原样的碳含量均值表现为PEF(84.22%±1.00%)>DAF(72.93%±2.28%)>BF(59.52%±2.18%)>MF(53.00%±1.67%),δ^(13)C值均值表现为PEF(-29.04‰±0.26‰)<DAF(-29.02‰±0.40‰)<MF(-25.09‰±0.46‰)<BF(-23.79‰±0.92‰)。不同类型的塑料薄膜经热水处理后的碳含量和δ^(13)C值与原样相比均无明显差异;但稀盐酸处理后DAF和BF的碳含量分别升高了9.34个百分点和11.32个百分点,而PEF和MF碳含量几乎不变。对于δ^(13)C值来说,PEF仅偏负0.19个千分点,DAF、BF、MF的偏负值分别是PEF的5.4倍、11.6倍和6.8倍;过氧化氢处理对BF影响最大,碳含量同原样相比升高了10.25个百分点,δ^(13)C值偏负3.14个千分点。经化学逐级处理后四种类型塑料薄膜碳含量最终都呈升高趋势,δ^(13)C值呈偏负趋势。在建立的Logistic回归模型中,ROC曲线下面积(Area Under the Curve,AUC)为0.95,预测准确率达到86.5%,因此可通过样品碳含量和热水处理后δ^(13)C值对塑料薄膜的降解类型进行鉴别。
