CFHCl裂解成CF的研究已有较长的历史,近年来,作者之一曾利用激光诱导荧光方法实时(in real time)测定CF的浓度,对这一均相单分子反应过程的了解更趋清楚。最近我们利用激光加热法测定了CFHCl在Pt、Ag,及Ni-Cr金属表面上的复相反应速率,...CFHCl裂解成CF的研究已有较长的历史,近年来,作者之一曾利用激光诱导荧光方法实时(in real time)测定CF的浓度,对这一均相单分子反应过程的了解更趋清楚。最近我们利用激光加热法测定了CFHCl在Pt、Ag,及Ni-Cr金属表面上的复相反应速率,发现CFHCl在Pt及Ag上的反应速率此在Ni-Cr表面上的反应速率要快,并且反应温度阈值低很多,但是由于Pt及Ag价值昂贵,难以在生产上推广。展开更多
Electronic states of CF2Cl2 （dichlorodifluoromethane, Freon 12） have been studied using a new type of electron momentum spectrometer with a very high efficiency at an impact energy of 1200 eV plus binding energy. Th...Electronic states of CF2Cl2 （dichlorodifluoromethane, Freon 12） have been studied using a new type of electron momentum spectrometer with a very high efficiency at an impact energy of 1200 eV plus binding energy. The experimental electron momentum profiles are compared with the density functional theory （DFT） and Hartree-Fock （HF） calculations. The relationship between orbital assignments in different coordinate systems is discussed. A new method of difference analysis based on the new type of electron momentum spectrometer is used to clarify the ambiguities regarding the orbital ordering.展开更多
切段式机收甘蔗含杂率的自动测量可以客观评估机收甘蔗到糖厂入榨前的质量。针对现有抽样称重估算杂质方式效率低且主观性强的问题,以及因田间环境较为复杂使得检测目标蔗段存在运动状态变换导致的模糊、光照强度变化和蔗叶遮挡等技术难...切段式机收甘蔗含杂率的自动测量可以客观评估机收甘蔗到糖厂入榨前的质量。针对现有抽样称重估算杂质方式效率低且主观性强的问题,以及因田间环境较为复杂使得检测目标蔗段存在运动状态变换导致的模糊、光照强度变化和蔗叶遮挡等技术难点,提出了一种基于改进YOLOv5安装在切段式甘蔗机上的机收蔗含杂率检测的方法。首先,针对工业相机拍摄的蔗段目标为小目标的应用场景,增加小目标检测层,增强网络模型对其的专注;其次,将C3模块替换成C2f模块,提高网络模型对小物体、低对比度目标的检测速度和检测精度;最后,加入加权交并比WIoU(Weighted Intersection over Union)损失函数,提升预测框的回归精度,增强数据集训练效果。试验结果表明:基于改进YOLOv5的机收蔗含杂率检测模型,蔗段识别准确率达95.2%、mAP(mean Average Precision)值为62.5%,相较于原始YOLOv5模型分别提高了15.3、13.5个百分点,性能优于YOLOv7、YOLOv8等模型。在台架试验中,改进后模型检测的含杂率平均相对误差为19.58%,比改进前模型降低了38.12个百分点;含杂率平均值为7.31%,比人工测量的实际含杂率高出0.05个百分点。因此,此方法是一种实时性强、效率高、准确性高且能全量检测机收蔗含杂率的方法,能够为田间甘蔗收获作业质量提供技术支撑。展开更多
The reaction mechanism of the singlet biradical CF2 with O3 has been studied by using ab initio method at 6-31G(d) level. The single pomt energy calculations of the reactants,intermediate, transition state and product...The reaction mechanism of the singlet biradical CF2 with O3 has been studied by using ab initio method at 6-31G(d) level. The single pomt energy calculations of the reactants,intermediate, transition state and products of the reaction have been performed by MP2/6-31G(d)method The relative structure data of the reaction species are given The mechanism proposed here is that there are two stages in the reaction the reactant molecules combine first to form an stable energy-enriched intermediate, this stage has no energy barrier, and then the intermediate is decomposed to D=CF2O and O2 the energy barrier of this stge is 230.73 kJ mol-1(MP2/6-31G(d)HF/6-31G(d)). The reaction is exothermic by 461.06 kJ mol-1(MP2/6-31G(d)HF/6-31G(d)). The potential energy curve along the reaction path has been obtained by IRC calculations.展开更多
文摘CFHCl裂解成CF的研究已有较长的历史,近年来,作者之一曾利用激光诱导荧光方法实时(in real time)测定CF的浓度,对这一均相单分子反应过程的了解更趋清楚。最近我们利用激光加热法测定了CFHCl在Pt、Ag,及Ni-Cr金属表面上的复相反应速率,发现CFHCl在Pt及Ag上的反应速率此在Ni-Cr表面上的反应速率要快,并且反应温度阈值低很多,但是由于Pt及Ag价值昂贵,难以在生产上推广。
基金Project supported by the National Natural Science Foundation of China （Grant Nos 19854002, 19774037 and 10274040） and the Research Fund for the Doctorate Program of Higher Education （Grant No 1999000327）.
文摘Electronic states of CF2Cl2 （dichlorodifluoromethane, Freon 12） have been studied using a new type of electron momentum spectrometer with a very high efficiency at an impact energy of 1200 eV plus binding energy. The experimental electron momentum profiles are compared with the density functional theory （DFT） and Hartree-Fock （HF） calculations. The relationship between orbital assignments in different coordinate systems is discussed. A new method of difference analysis based on the new type of electron momentum spectrometer is used to clarify the ambiguities regarding the orbital ordering.
文摘切段式机收甘蔗含杂率的自动测量可以客观评估机收甘蔗到糖厂入榨前的质量。针对现有抽样称重估算杂质方式效率低且主观性强的问题,以及因田间环境较为复杂使得检测目标蔗段存在运动状态变换导致的模糊、光照强度变化和蔗叶遮挡等技术难点,提出了一种基于改进YOLOv5安装在切段式甘蔗机上的机收蔗含杂率检测的方法。首先,针对工业相机拍摄的蔗段目标为小目标的应用场景,增加小目标检测层,增强网络模型对其的专注;其次,将C3模块替换成C2f模块,提高网络模型对小物体、低对比度目标的检测速度和检测精度;最后,加入加权交并比WIoU(Weighted Intersection over Union)损失函数,提升预测框的回归精度,增强数据集训练效果。试验结果表明:基于改进YOLOv5的机收蔗含杂率检测模型,蔗段识别准确率达95.2%、mAP(mean Average Precision)值为62.5%,相较于原始YOLOv5模型分别提高了15.3、13.5个百分点,性能优于YOLOv7、YOLOv8等模型。在台架试验中,改进后模型检测的含杂率平均相对误差为19.58%,比改进前模型降低了38.12个百分点;含杂率平均值为7.31%,比人工测量的实际含杂率高出0.05个百分点。因此,此方法是一种实时性强、效率高、准确性高且能全量检测机收蔗含杂率的方法,能够为田间甘蔗收获作业质量提供技术支撑。
文摘The reaction mechanism of the singlet biradical CF2 with O3 has been studied by using ab initio method at 6-31G(d) level. The single pomt energy calculations of the reactants,intermediate, transition state and products of the reaction have been performed by MP2/6-31G(d)method The relative structure data of the reaction species are given The mechanism proposed here is that there are two stages in the reaction the reactant molecules combine first to form an stable energy-enriched intermediate, this stage has no energy barrier, and then the intermediate is decomposed to D=CF2O and O2 the energy barrier of this stge is 230.73 kJ mol-1(MP2/6-31G(d)HF/6-31G(d)). The reaction is exothermic by 461.06 kJ mol-1(MP2/6-31G(d)HF/6-31G(d)). The potential energy curve along the reaction path has been obtained by IRC calculations.
