多阶导数紫外光谱法快速测定生物转化液中的肉桂醇、肉桂醛和肉桂酸

为高效筛选转化肉桂醛为天然肉桂醇的微生物菌株,建立直接、快速测定生物转化液中的肉桂醇、肉桂醛和肉桂酸含量的多阶导数紫外光谱法。对3个组分的紫外吸收光谱进行二阶或三阶导数处理,选择各组分合适的检测波长;在选定波长下建立各组分吸收光谱的导数值对质量浓度的工作曲线。结果表明:肉桂醛和肉桂酸分别在320 nm和306 nm波长处的二阶导数值与其质量浓度分别在0.52~9.27 mg/L和0.51~9.24 mg/L范围内有良好的线性关系,平均回收率分别为103.3%和104.1%,相对标准偏差(relative standard deviation,RSD)为4.1%和2.1%;肉桂醇在256 nm波长处的三阶导数值与其质量浓度在0.55~5.47 mg/L范围内有良好的线性关系,平均回收率为98.0%,RSD为3.5%。利用该方法,样品中各组分不需提取分离即可直接稀释测定,可用于微生物转化肉桂醛制备肉桂醇反应实验菌株的快速高效筛选。

多阶导数自适应视频超分辨率重建

传统视频超分辨率重建算法在去除噪声的同时,很难有效保持图像边缘细节信息。针对该问题,构建了一种结合多阶导数数据项和自适应正则化项的视频超分辨率重建算法。在正则化重建模型的基础上,该算法对数据项进行改进,引入能更好描述噪声统计特性的噪声多阶导数,并利用去噪效果较好的全变分(TV)和非局部均值(NLM)正则化项对视频超分辨率重建过程进行约束。此外,为了更好地保持图像细节信息,采用区域空间自适应曲率差分算法提取结构信息,从而对正则化系数进行自适应加权。实验结果表明:在噪声方差为3时,与核回归算法和聚类算法相比,该算法重建视频主观效果边缘更加锐化,局部结构更加正确、清晰;重建视频的均方误差(MSE)平均下降幅度分别为25.75%和22.50%;峰值信噪比(PSNR)分别平均提升了1.35 d B和1.14 d B。所提算法能够在去除噪声的同时有效保持图像的细节特征。

双波长和多阶导数分光光度法在贵金属分析中的应用

评述 1 990～ 2 0 0 1年国内外有关双波长和多阶导数分光光度法在贵金属分析中的应用。同时 ,收入了部分上世纪 80年代末期国内外具有代表性的论著。内容包括 :新方法与新试剂、双波长分光光度法 (等吸收点和系数倍率法、二次双波长法 )、多阶导数分光光度法和其它技术联用法。参考文献

多阶导数紫外光谱法测定肉桂醛氧化产物

为监测肉桂醛在常温常压条件下的氧化过程,对肉桂醛及其氧化产物肉桂酸、苯甲醛和苯甲酸的紫外光谱进行三阶导数处理。结果表明,苯甲醛一阶导数值、肉桂酸二阶导数值、苯甲酸和肉桂醛三阶导数值能消除相互干扰,且在质量浓度一定范围内有良好的线性关系。该方法可用于肉桂醛氧化过程的快速检测。

基于多阶结构表示的超分辨率重构图像质量盲评价方法

为了客观地预测超分辨率重构图像的质量,提出了一种基于多阶结构表示的超分辨率重构图像无参考质量评价方法。利用多阶导数信息表示超分辨率重构图像的主要结构和细微纹理,并利用局部二值模式提取超分辨率重构图像的多阶结构特征;结合主观分数,利用随机森林回归训练图像质量预测模型,再利用模型预测待测图像的质量。为了证明该算法的有效性和优越性,对比实验在一个大尺度超分辨率图像数据库上进行。该算法的斯皮尔曼相关系数和皮尔森线性相关系数分别为0.910 3和0.918 3。实验结果表明,该算法优于现有的无参考质量评价算法,与主观评价结果保持较高的一致性。此外,该算法时间复杂度低,运行时间适中。

基于Logistic函数的电网中长期发展模式的模型研究

随着用电需求增加,电网大范围应用,对电网中长期发展产生一定影响,为此研究基于Logistic函数的电网中长期发展模式模型。利用模型有效预测终端能源消耗总量和电能消耗与终端能源消耗比值,在此基础上,依照采用多阶导数方式处理模型的电网中长期发展模式划分原理,结合国内外发达地区电网建设发展态势以及实际情况,将电网中长期发展模式划分成慢速增长期、快速增长期、减速增长期以及缓慢增长饱和期等4个阶段。以青海省为例验证所研究模型的有效性,结果显示:2025年左右能源消耗总量达到饱和值3.5亿t,2028年电能与终端能源消耗比值预计达到28.15%;并且划分青海省电网中长期发展模式为2012年之前为慢速增长期,2012—2018年为快速增长期;2019—2026年为减速增长期,2027年以后处于缓慢饱和增长期。

Multiplicity Results for Second-order Generalized Sturm-Liouville Boundary Value Problems with Dependence on the First Order Derivative

By using fixed point theorems,we consider multiplicity of positive solutions for second-order generalized Sturm-Liouville boundary value problem,where the first order derivative is involved in the nonlinear term explicitly.We show the existence of multiple positive solutions for the problems.Example is given to illustrate the main results of the article.

Construction of Wave-free Potentials and Multipoles in a Two-layer Fluid Having Free-surface Boundary Condition with Higher-order Derivatives

There is a large class of problems in the field of fluid structure interaction where higher-order boundary conditions arise for a second-order partial differential equation. Various methods are being used to tackle these kind of mixed boundary-value problems associated with the Laplace’s equation （or Helmholtz equation） arising in the study of waves propagating through solids or fluids. One of the widely used methods in wave structure interaction is the multipole expansion method. This expansion involves a general combination of a regular wave, a wave source, a wave dipole and a regular wave-free part. The wave-free part can be further expanded in terms of wave-free multipoles which are termed as wave-free potentials. These are singular solutions of Laplace’s equation or two-dimensional Helmholz equation. Construction of these wave-free potentials and multipoles are presented here in a systematic manner for a number of situations such as two-dimensional non-oblique and oblique waves, three dimensional waves in two-layer fluid with free surface condition with higher order partial derivative are considered. In particular, these are obtained taking into account of the effect of the presence of surface tension at the free surface and also in the presence of an ice-cover modelled as a thin elastic plate. Also for limiting case, it can be shown that the multipoles and wave-free potential functions go over to the single layer multipoles and wave-free potential.

Asymptotic stability with probability one of MDOF nonlinear oscillators with fractional derivative damping

In this paper,the asymptotic stability with probability one of multi-degree-of-freedom(MDOF)nonlinear oscillators with fractional derivative damping parametrically excited by Gaussian white noises is investigated.A stochastic averaging method and the Khasminskii’s procedure are employed to evaluate the largest Lyapunov exponent,whose sign determines the stability of the system.As an example,two coupled nonlinear oscillators with fractional derivative damping is worked out to demonstrate the proposed procedure and to examine the effect of fractional order on the stochastic stability of system.In particular,the case of factional order more than 1 is studied for the first time.