Tm：YAP激光晶体的生长及激光性能的研究

采用提拉法生长了高质量的4%（原子分数）Tm∶YAP晶体。X射线粉末衍射分析确定生长的晶体为Tm∶YAP晶体。吸收光谱分析表明Tm∶YAP晶体在688和794nm有较强的吸收峰。采用793nm激光二极管泵浦Tm∶YAP晶体,实现了2.01μm激光输出,最大输出功率5.1W,光转换效率为37%,斜率效率高达43.5%,连续可调范围从1894～2066nm,在2010nm得到最大的输出功率值为1.84W。     

毫米波云雷达与激光云高仪气象探测性能对比分析

为评估毫米波云雷达及激光云高仪的探测性能,选取广州市气象局KA波段毫米波云雷达和激光云高仪云高观测数据,通过对比两种测云设备在相同条件下的差异,分析不同要素对观测设备的影响,结果表明：(1)毫米波云雷达与激光云高仪同时探测到有云时,二者在云底高度观测上吻合程度较高,相关系数为0.98;(2)在数据获取率上,云雷达对高云的探测能力明显优于激光云高仪,但在对低云的探测能力上还有待提高,和激光云高仪相比,云雷达对低云和中云的识别能力有待提高;(3)对于多层云的观测,低层云的遮挡降低了激光云高仪对中高层云的观测,激光云高仪探测的中高层云多数在云雷达的回波内部.(4)对于不同强度的降水,日降水量越多,该天所测得的高、中云层回波就越少.(5)通过边界层高度与污染物的关系分析可以得出,边界层高度与PM2.5浓度呈反比.这些研究能够对毫米波云雷达和激光云高仪的探测能力进行评估,为后续选择设备提供参考,也推动了云观测技术的发展.     

机场围界入侵报警系统的设计

结合机场的地域特征,介绍一种检测人入侵行为的设计方案.以激光光电感应作为传感器件,通过对89052单片机进行C语言编程,检测和判断人入侵事件.通过大量实验获取样本时间点,利用聚类分析的算法有效排除掉噪声点,得到可靠样本空间,计算出可信赖样本阈值范围,经实验验证入侵判断误报率符合要求.     

OH自由基绝对标定系统的建立和研究

利用H2 O在 1 85nm紫外光照射下产生定量OH自由基 ,用低压扩散激光诱导荧光技术建立了OH自由基标定系统 .在实验条件下 ,体系产生OH自由基的浓度范围为 3× 1 0 7— 2× 1 0 9个·cm- 3,得到归一化荧光信号 (S)与OH自由基浓度的定量关系为S =6 0 4× 1 0 - 9[OH]- 0 0 4 0 7(R2 =0 987) ,并研究和讨论了饱和效应以及体系中可能存在的干扰 .     

Size distribution and chemical composition of secondary organic aerosol formed from Cl-initiated oxidation of toluene

Secondary organic aerosol (SOA) formed from Cl-initiated oxidation of toluene was investigated in a home-made smog chamber. The size distribution and chemical composition of SOA particles were measured using aerodynamic particle sizer spectrometer and the aerosol laser time-of-flight mass spectrometer (ALTOFMS), respectively. According to a large number of single aerosol diameter and mass spectra, the size distribution and chemical composition of SOA were obtained statistically. Experimental results showed that SOA particles created by Cl-initiated oxidation of toluene is predominantly in the form of fine particles, which have diameters less than 2.5 m (i.e., PM2.5), and glyoxal, benzaldehyde, benzyl alcohol, benzoquinone, benzoic acid, benzyl hydroperoxide and benzyl methyl nitrate are the major products components in the SOA. The possible reaction mechanisms leading to these products are also proposed.