大气气溶胶消光特性和折射率的测量

 介绍了一种综合利用能见度仪、微脉冲激光雷达和光学粒子计数器测量大气气溶胶折射率的新方法。首先使用能见度仪和激光雷达测量出大气气溶胶的消光系数和消光后向散射比,然后使用粒子计数器测量出粒子谱分布,结合气溶胶粒子折射率,根据球形粒子的米（Mie）散射理论,可以得到气溶胶消光系数和消光后向散射比。通过分析消光系数、消光后向散射比、粒子谱分布和折射率之间的关系,结合已知的消光系数和消光后向散射比,反演出大气气溶胶粒子的折射率。     

监测小麦叶片氮积累量的新高光谱特征波段及比值植被指数

实时、快速、无损监测作物氮素状况对于精确氮肥管理具有重要意义。传统的氮素估测方法在时间或空间上难以满足要求,新兴的高光谱遥感技术为作物氮素监测提供了有效手段和技术途径。本研究的目的是基于三个田间试验的系统观测资料,探索可用于小麦叶片氮素监测的新的高光谱敏感波段及比值指数。利用减量精细采样法,系统构建了350～2 500 nm范围内所有两两波段形成的比值光谱指数RSI(ratio spectral index),综合分析了小麦叶片氮积累量LNA(leaf nitrogen accumulation)(g N·m-2)与RSI的定量关系,发现了监测叶片氮积累量的新高光谱特征波段(990, 720)和光谱指数RSI(990, 720),建立了相应的监测模型y=5.095x-6.040,模型的决定系数(R2)为0.814。利用独立试验资料检验模型,决定系数(R2)为0.847,相对根均方差(RRMSE)为24.70%,表明模型预测值与观察值之间的符合度较高。因此,利用高光谱比值指数RSI(990, 720)来估算小麦叶片氮积累量是精确可行的。该结果为便携式小麦氮素监测仪的研制开发及遥感信息的快速提取提供了适用可行的波段选择与技术依据。     

比波谱导数和零交点法测定混合物含量

Ｐｂ２＋、Ｃｄ２＋、Ｈｇ２＋在ｐＨ６．５的硼砂－盐酸缓冲溶液中,与四（４－三甲铵基苯基）卟啉（ＴＡＰＰ）生成稳定配合物,采用ＫＩ和低聚度聚乙烯醇（ＰＶＡ）增敏、增溶,Ｐｂ２＋、Ｃｄ２＋、Ｈｇ２＋的εｍａｘ分别为ε４８１．５（４．９×１０５Ｌ·ｍｏｌ－１·ｃｍ－１）、ε４５７（７．９×１０５Ｌ·ｍｏｌ－１·ｃｍ－１）、ε４４４．５（８．１×１０４Ｌ·ｍｏｌ－１·ｃｍ－１）。在三吸收峰相互重叠的情形下,利用比波谱导数和零交点法,同时测定它们的含量,Ｐｂ２＋、Ｃｄ２＋、Ｈｇ２＋的检出限分别达４μｇ／Ｌ、２μｇ／Ｌ和１０μｇ／Ｌ。方法计算简便、快速。     

改性丝光沸石结构研究

通过红外光谱、X射线衍射和差热分析研究表明 ,丝光沸石经铝代硅改性后 ,仍然保留丝光沸石晶格构造。但是 ,由于出现过剩负电荷 ,Na ,K 等阳离子补偿到晶格中 ,导致由阳离子的水合作用定位结合的结晶水增多。铝代替硅的另一结果是丝光沸石单位晶胞体积扩大 ,导致丝光沸石中的空穴体积也增大 ,使其吸附容量增加。     

运用Matlab中Plot函数绘制二元共聚物组成双曲线

利用Matrix Laboratory (Matlab)软件编辑Plot函数,输入共聚单体的竞聚率,然后运行可以得到二元共聚物组成双曲线。通过共聚双曲线,可以同时观察两种单体的共聚行为,使隐含的第二单体与其聚合物组成之间的变化规律具象化,丰富了共聚物组成曲线的学习内容,有助于加深对共聚合反应规律的认识。     

Identifying and supporting teachers’ robust understanding of proportional reasoning

This case study uses the Framework for Teachers’ Robust Understanding of Proportional Reasoning for Teaching (Weiland et al., 2020) to characterize how 51 mathematics teachers solved a comparison proportional problem. We found 50 of the 51 teachers productively drew upon four knowledge resources: (1) proportional situation, (2) ratios as part: part or part: whole, (3) unit rates, and (4) ratio as measure. This study details these and teachers’ less commonly used knowledge resources, as well as counterproductive statements related to the knowledge resources. We analyze the structure of the comparison proportion problem and suggest why teachers drew on particular knowledge resources. Lastly, we highlight how counterproductive statements highlight areas of focus for mathematics teacher educators and extends the operationalizing of the robust proportional reasoning framework for mathematics education researchers.     

长相依序列均值变点检测

研究了长相依序列均值变点检测问题.首先给出变点检验的Ratio统计量其次分别推导了原假设和备择假设下统计量的极限分布,最后用蒙特卡洛方法模拟出检验的临界值,并通过数值模拟和实例分析说明方法的有效性.     

The moment function for the ratio of correlated generalized gamma variables

The moment function for the ratio of correlated generalized gamma variables is expressed in terms of special functions. The expression presented generalizes the known moment expression for the integer valued moments to the real valued moments. Approximate formulas, in terms of elementary functions, are provided for low and high correlation regions and some application examples are given.     

小目标识别的小波阈值去噪方法

为改善小目标识别的滤噪效果并提高其信噪比,构造了新的阈值函数并采用局部方差估计法来计算阈值对小目标进行去噪处理。对小波分解层次中各高频子带选取不同的阈值,其中大于阈值的小波系数采用改进的双曲线函数作为阈值函数,小于阈值的小波系数采用指数函数与对数函数相互组合的方式作为阈值函数。对采用的阈值函数进行了理论推导,并与软、硬阈值法进行了实验对比。计算机仿真结果表明：经本文阈值法处理后,信噪比相对于含噪图像提高了70.8%,而软、硬阈值法分别提高了49.8%和59.7%。光学实验进一步证实：该方法能更有效地提高信噪比,增强联合变换相关器对于小目标的识别能力。     

Ratio and relative asymptotics of polynomials orthogonal with respect to varying Denisov-type measures

Let μ be a finite positive Borel measure with compact support consisting of an interval plus a set of isolated points in , such that μ^′>0 almost everywhere on [c,d]. Let , be a sequence of polynomials, , with real coefficients whose zeros lie outside the smallest interval containing the support of μ. We prove ratio and relative asymptotics of sequences of orthogonal polynomials with respect to varying measures of the form dμ/w_2n. In particular, we obtain an analogue for varying measures of Denisov's extension of Rakhmanov's theorem on ratio asymptotics. These results on varying measures are applied to obtain ratio asymptotics for orthogonal polynomials with respect to fixed measures on the unit circle and for multi-orthogonal polynomials in which the measures involved are of the type described above.