Fast analysis of volatile components of Achillea tenuifolia Lam with microwave distillation followed by headspace single-drop microextraction coupled to gas chromatography-mass spectrometry (GC–MS)

This article investigates the effect of microwaves on the amount of volatile compounds Achillea tenuifolia Lam with two methods, headspace single-drop microextraction and microwave-assisted headspace single-drop microextraction (MA-SDME), for the analysis of essential oil. Solvent selection, solvent volume, microwave power, irradiation time and sample mass were optimised by the simplex method.     

基于微波光子学的准分布式光纤传感解调技术

准分布式光纤传感系统在土木工程、能源勘测、航空航天、国防、化工等领域一直发挥着不可替代的重要作用。以微波光子学为基础的准分布式光纤传感解调技术被广泛应用于光纤复用系统的快速、高精度的信号解调与传感器定位。与传统的光学波长解调方案相比,该技术大幅提高了系统的解调速率,弥补了传统解调方法在传感器定位方面的缺陷。本文主要介绍了近年来国内外在基于微波光子学的准分布式光纤传感解调领域的研究进展,从光纤光栅准分布式传感系统和光纤法布里-珀罗准分布式传感系统两方面入手,对比分析了现有的数种微波解调光纤准分布式系统的优缺点,并对基于微波光子学的准分布式光纤传感解调技术的未来发展方向进行了总结与展望。     

利用具有相位跳跃技术的阴影摩尔图测量电子组装元件的热翘曲

Phase-stepping technique is applied to the analysis of fringe patterns of shadow moiré of electronic packages.Sensitivity of the fringe pattern analysis is demonstrated to be significantly increased.Thermally induced warpage of electronic packages is successfully measured in real-time as the sample is driven through a simulated reflow process.The paper discusses the technique of phase stepping,noise filtering and its application to the shadow moiré method.Applications of the technology are presented.     

非线性椭圆边值问题和极大单调算子的零点

本文利用非线性极大单调算子值域的扰动结论,研究一类与广义p-Laplacian算子相关的、具Neumann边值条件的非线性椭圆方程的解的存在唯一性.同时研究这个唯一解与适当定义的非线性极大单调算子的零点之间的关系.进而设计一种迭代算法强收敛到这个唯一解.本文采用新的构造算子和拆分方程的方法,推广和补充了以往的相关研究工作.     

任意相移阴影叠栅相位解调技术的研究

结合时域和频域干涉图分析方法,提出一种任意相移阴影叠栅条纹图相位解调技术,降低了干涉图在采样过程中对相移量的严格标定要求,补偿了相移阴影叠栅技术固有的相移不匀误差。使用空域技术确定采样干涉图的正交信号,进而得到了采样干涉图的相移量,然后运用任意相移相位提取算法搜索测量相位信息。实验证明此方法简单方便、求解迅速,且优于典型的相移算法,其测量误差的标准差不超过3×10-3 mm,该方法为提高相移阴影叠栅技术的测量精度提供了有效手段。     

带两个形状参数的五次Bézier曲线的扩展

给出了一组含有两个形状参数α,β的六次多项式基函数,是五次Bernstein基函数的扩展,分析了这组基的性质;基于这组基定义了带两个形状参数的多项式曲线,所定义的曲线具有五次Bézier曲线的性质,改变参数α,β的取值,曲线具有更灵活的形状可调性,而且能向上或从两侧逼近控制多边形.另外,经典的五次Bézier曲线和有关文献中带一个形状参数的曲线均是该文所定义曲线的特例.实例表明,定义的曲线为曲线/曲面的设计提供了一种有效的方法.     

An L 2-theory for a class of SPDEs driven by Lévy processes

In this paper we present an L 2-theory for a class of stochastic partial differential equations driven by Lévy processes.The coefficients of the equations are random functions depending on time and space variables,and no smoothness assumption of the coefficients is assumed.     

向量优化问题有效点集的稳定性

在不需要紧性假设下,利用拟C-凸函数及回收锥的性质,建立了向量优化问题有效点集的稳定性, 获得了一列目标函数和可行集均扰动情形下的向量优化问题与对应的向量优化问题有效点集的Painlevé Kuratowski内收敛性结果．所得结果推广和改进了相关文献(Attouch H, Riahi H. Stability results for Ekeland’s ε-variational principle and cone extremal solution; Huang X X. Stability in vector-valued and set-valued optimization)中的相应结果, 并给出例子说明了所得结果的正确性.     

Rapid screening and purification of potential alkaloid neuraminidase inhibitors from Toddalia asiatica (Linn.) Lam. roots via ultrafiltration liquid chromatography combined with stepwise flow rate counter‐current chromatography

Toddalia asiatica (Linn.) Lam. is a medical plant traditionally used to treat coughs, fevers, and various diseases. Alkaloids are the main active ingredients in Toddalia asiatica (Linn.) Lam., but traditional methods for screening and separation are complex and labor‐intensive. In this work, an efficient strategy was developed to rapidly screen, identify, and separate neuraminidase inhibitors from Toddalia asiatica (Linn.) Lam. Ultrafiltration, high performance liquid chromatography, and time‐of‐flight mass spectrometry were employed for rapid screening and identification of neuraminidase inhibitors. A two‐phase solvent system comprising n‐hexane/ethyl acetate/methanol/water (5:5:3:7, v/v) was then selected for separation by high‐speed counter‐current chromatography. A sample loading of 200 mg and a stepwise flow rate were achieved by increasing the flow rate from 2 to 4 mL/min after 4 h. Three main fluoroquinoline alkaloids (haplopine, skimmianine, and 5‐methoxydictamnine) along with two coumarins were obtained via one‐step separation and their structures were determined by mass spectrometry and nuclear magnetic resonance. In vitro assays revealed skimmianine with half‐maximal inhibitory concentration of 16.2 ± 0.7 µmol/L was selected as the potential highest neuraminidase inhibitor. The results suggest that ultrafiltration high performance liquid chromatography–mass spectrometry combined with high‐speed counter‐current chromatography is efficient for the screening and isolation of neuraminidase inhibitors from complex natural products.     

HL-2A装置反剪切阿尔芬本征模实验观测与模拟验证

利用 AMC 程序获取了不同最小安全因子( q_min )情况下反剪切阿尔芬本征模频率(RSAE)的变化特征： 当最小安全因子 q_min >1 时,RSAE 频率随着 q_min 增大而增大;当 q_min <1 时,RSAE 频率随着 q_min 减小而增大。这 与简化 RSAE 色散关系给出的频率相符。在 HL-2A 电流爬升期间和锯齿期间分别发现了 q_min >1 和 q_min <1 情况下 缓慢向上扫频的模。这些模的频率介于环向阿尔芬本征模和比压阿尔芬本征模之间,与 AMC 得到的 RSAE 模频 率一致,模的径向结构由单一极向谐波组成,并且高度局域在 q_min 附近,具有典型的 RSAE 特征。