采用曲线拟合消除探测器阵列非线性对吸收光谱的影响

在微型光谱分析系统中,光电探测器阵列像元的非线性响应对光谱信号有着很大的影响,尤其是吸收谱的测量中,将导致吸收谱的畸变和假谱线的出现。文章对这一影响进行了深入的分析,并提出了根据线性像元输出信号,利用曲线拟合的方法对线性较差的像元输出进行矫正,减小非线性对光谱信号的影响。采用该方法对实验中获取的吸收谱信号进行了矫正,得到了理想的效果。     

丹酰基丝氨酸与桥联双环糊精作用机理的时间分辨荧光光谱研究

利用稳态、时间分辨荧光光谱,结合非线性最小二乘法拟合系统研究了手性探针分子丹酰-L-丝氨酸(DLS)与β-环糊精(β-CD)、2-位硒桥联β-CD(1)和2-位碲桥联β-CD(2)的复合及复合机理.对比研究了DLS与三种不同环糊精复合强度及复合方式的差别.结果表明,引入硒桥键不能使化合物1与丹酰基丝氨酸分子很好地复合;而引入碲桥键使化合物2对DLS分子的结合能力相对于β-CD有明显增强.     

Polynomial motion of non‐holonomic mechanical systems of chained form

In this study a simple general motion planning approach for non‐holonomic mechanical systems of chained form is proposed, in which the intricate motion planning problem (steering the system from an initial state to a final state) is converted to a simple curve‐fitting problem (satisfying a set of end‐point conditions). By means of this approach, other geometric constraints, such as passing a channel and avoiding collision with obstacles, and minimizing some cost functions, such as the minimum path length, can be easily handled, while the control inputs can be derived directly from the smooth path planned. For verifying the effectiveness of the proposed approach, a number of simulations are conducted for various task require ments and environments, with respect to a four‐wheel mobile chart (one‐chain system) and a three‐input firetruck (two‐chain system). Copyright © 1999 John Wiley & Sons, Ltd.     

基于图像跟踪的孔洞目标提取与区域定位研究

针对纤维材料图像分割后提取的目标图像孔洞之间粘连明显、不封闭、分布不均匀和大小不一等特点,采用常规链码与带方向链码两种跟踪手段,运用链码差实现了对边缘的方向性表示.通过结合三点圆拟合算法,对目标孔洞边缘进行了补全,再用链码跟踪所获得的边缘信息对拟合边缘进行修正,实现了对目标孔洞区域的有效定位.     

与积分有关的一个极限及其应用

将崔尚斌编著的《数学分析教程》(中册)的一个综合习题进行推广,得到求与积分有关的极限的几个实用性结果,并给出多个应用例子.     

Analytic energy gradients for orbital‐optimized MP3 and MP2.5 with the density‐fitting approximation: An efficient implementation

Efficient implementations of analytic gradients for the orbital‐optimized MP3 and MP2.5 and their standard versions with the density‐fitting approximation, which are denoted as DF‐MP3, DF‐MP2.5, DF‐OMP3, and DF‐OMP2.5, are presented. The DF‐MP3, DF‐MP2.5, DF‐OMP3, and DF‐OMP2.5 methods are applied to a set of alkanes and noncovalent interaction complexes to compare the computational cost with the conventional MP3, MP2.5, OMP3, and OMP2.5. Our results demonstrate that density‐fitted perturbation theory (DF‐MP) methods considered substantially reduce the computational cost compared to conventional MP methods. The efficiency of our DF‐MP methods arise from the reduced input/output (I/O) time and the acceleration of gradient related terms, such as computations of particle density and generalized Fock matrices (PDMs and GFM), solution of the Z‐vector equation, back‐transformations of PDMs and GFM, and evaluation of analytic gradients in the atomic orbital basis. Further, application results show that errors introduced by the DF approach are negligible. Mean absolute errors for bond lengths of a molecular set, with the cc‐pCVQZ basis set, is 0.0001–0.0002 Å. © 2017 Wiley Periodicals, Inc.     

Peak‐fitting of high resolution ToF‐SIMS spectra: a preliminary study

Peak‐fitting has been performed on a series of peaks obtained by time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) analysis in order to assess whether information may be obtained from this procedure on the samples' characteristics. A variety of samples were examined including a range of treatments for aluminium leading to different surface roughnesses, polymer films with a range of polydispersities, molecular weight (MW) and thicknesses as well as aluminium samples with adsorbed adhesion promoters on the surface. Variation of peak‐fitting was assessed by varying the peak intensity, full width at half maximum (FWHM) and peak asymmetry. Although further studies are needed it is possible to say that the peak width increases with roughness whereas peak asymmetry seems to be related to oxide thickness. Polymer characteristics do not seem to influence the width whereas the peak asymmetry increases either versus MW or polydispersity. A possible assumption is that the peak asymmetry relates to the ion formation processes. Additional work with varying polymer films thickness indicates that both FWHM and peak asymmetry may be related to sample charging and this could be used for assessment of film thicknesses. Finally, peak‐fitting was used to obtain a more reliable peak area when peaks are too close in mass to use current methods. Copyright © 2009 John Wiley & Sons, Ltd.     

In situ study of diffusion and interaction of water and electrolyte solution in polyacrylonitrile (PAN) membrane using FTIR and two-dimensional correlation analysis

In the study, the diffusion process of water and CaCl₂ aqueous solution in polyacrylonitrile (PAN) membrane have been investigated using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and two-dimensional (2D) correlation analysis. In 2D ATR-FTIR spectra, the water ν(OH) band in PAN membrane during both water and CaCl₂ solution diffusion is split into three separate bands. However, the OH band appearing from bound water which forms hydrogen-bonding of CaCl₂ solution diffusion has a considerably lower wavenumber than that of pure water diffusion, which is due to association between Ca²⁺ ions and the CN groups in PAN. The sequential orders of the intensity changes for water and CaCl₂ solution diffusion in the region of ν(OH) and ν(CN) bands reveal the diffusion process and interaction of water and electrolyte in PAN membrane. That is, in the process of water diffusion in PAN membrane, water molecules first interact with –CN group in PAN to form weak hydrogen bond, then the moderate hydrogen-bonding interactions start gradually, and finally, the strong hydrogen-bonding interactions may be formed. When CaCl₂ solution diffuses in PAN membrane, the CN groups in PAN first associate with Ca²⁺ ions and then interact with water molecules to form hydrogen bond that grows gradually from weak to strong. Furthermore, the results are validated further by band fitting to calculate the ratio of each component band area and the proportion of component band to ν(OH) water band.