Heteroheptacene-based acceptors with thieno[3,2-b]pyrrole yield high-performance polymer solar cells

Rationally utilizing and developing synthetic units is of particular significance for the design of high-performance non-fullerene small-molecule acceptors (SMAs). Here, a thieno[3,2-b]pyrrole synthetic unit was employed to develop a set of SMAs (ThPy1, ThPy2, ThPy3 and ThPy4) by changing the number or the position of the pyrrole ring in the central core based on a standard SMA of IT-4Cl, compared to which the four thieno[3,2-b]pyrrole-based acceptors exhibit bathochromic absorption and upshifted frontier orbital energy level due to the strong electron-donating ability of pyrrole. As a result, the polymer solar cells (PSCs) of the four thieno[3,2-b]pyrrole-based acceptors yield higher open-circuit voltage and lower energy loss relative to those of the IT-4Cl-based device. What is more, the ThPy3-based device achieves a power conversion efficiency (PCE) (15.3%) and an outstanding fill factor (FF) (0.771) that are superior to the IT-4Cl-based device (PCE = 12.6%, FF = 0.758). The ThPy4-based device realizes the lowest energy loss and the smallest optical band gap, and the ternary PSC device based on PM6:BTP-eC9:ThPy4 exhibits a PCE of 18.43% and a FF of 0.802. Overall, this work sheds light on the great potential of thieno[3,2-b]pyrrole-based SMAs in realizing low energy loss and high PCE.     

基于SVM/LDA的SAR图像目标鉴别方法

提出一种基于主成分分析和支持向量机与线性判别分析结合算法的合成孔径雷达(synthetic aperture radar,SAR)图像目标鉴别方法. 利用主成分分析算法对SAR图像向量进行降维并提取其全局特征,对降维后的全局特征采用最小类内散度支持向量机算法进行变换,并对变换结果训练生成最佳分类器,进行分类完成目标鉴别. 实验结果表明该方法可以获得较高的分类正确率.     

基于SVM/LDA的SAR图像目标鉴别方法

提出一种基于主成分分析和支持向量机与线性判别分析结合算法的合成孔径雷达(synthetic aperture radar,SAR)图像目标鉴别方法.利用主成分分析算法对SAR图像向量进行降维并提取其全局特征,对降维后的全局特征采用最小类内散度支持向量机算法进行变换,并对变换结果训练生成最佳分类器,进行分类完成目标鉴别.实验结果表明该方法可以获得较高的分类正确率.     

大数据环境下高校大学生信息素养影响因素研究 ——基于粗糙集理论

【目的/意义】通过对大数据环境下高校大学生信息素养影响因素的研究,寻找一种科学量化方法,揭示影 响高校大学生信息素养的决策因素,以利于采取有效措施提升大学生信息素养。【方法/过程】论文基于粗糙集理 论,构建了大数据环境下高校大学生信息素养影响因素模型,设计开发了基于网络的信息素养量化分析专家系 统。选取多个工科专业作为研究样本,进行数据采集。运用多层次粗糙集方法对模型进行分析,在研究结果基础 上,提出高校大学生信息素养提升的建议。【结果/结论】实证研究结果表明,课程体系设计是大数据环境下高校大 学生信息素养的重要影响因素,各高校应从多个层面入手提升大学生信息素养水平。     

几种含硫肥料对油菜和三叶鬼针草吸收铅镉的影响

通过盆栽实验,研究4种含硫肥料对2种镉富集能力较强的植物——油菜和三叶鬼针草在铅、镉复合污染土壤中吸收铅、镉的影响.结果表明,硫磺和(NH4)2SO4增加了油菜对铅的吸收量,含硫肥料降低了三叶鬼针草对铅的吸收.硫磺和(NH4)2SO4增加了油菜对镉的吸收量,含硫肥料对三叶鬼针草吸收镉没有显著影响.在铅、镉复合污染土壤中,硫磺和(NH4)2SO4可以作为有效的肥料提高油菜对铅或镉的吸收,而对于三叶鬼针草,添加含硫肥料不能促进其提高对铅、镉的吸收.     

A class of fast and accurate deterministic trend decomposition in the spectral domain using simple and sharp diffusive filters

This study proposes a spectral domain algorithm to remove the deterministic non-periodic trend from a time series using a class of fast, sharp and diffusive filters. These filters are principally the iterative moving least squares methods weighted using Gaussian windows. The responses of the filters expressed in analytic forms are proven to be diffusive. If it is a polynomial of finite degree, the embedded trend can be decoupled by the filters with specific order and iteration steps. The filters’ order, transition zone, error tolerance, iteration number and smoothing factor are subject to two algebraic equations to form a specific class. The operation counts of all filters are slightly larger than twice that applying a Fast Fourier Transform (FFT). It is numerically shown for a given transition zone and tolerance, there is a filter generating the shortest error penetration distance among all the filters. If either the trend or a spectral band is the main concern, there is an optimal strategy to shrink the error penetration distance. The numerical results show the filter has better performance than several existing methods. In addition, four examples successfully show direct applications of the filter’s response.     

Cross-shore sediment transport estimation using fuzzy inference system in the swash zone

The interactions between fluid and sediment in the swash zone dominate the erosion or accretion of the beach, and they act as boundary conditions for nearshore hydrodynamic and morphodynamic models. Thus, the evaluation of sediment transport is of particular importance for many coastal processes and the design of coastal structures. In this paper, unlike conventional approaches, Fuzzy Inference System (FIS) and Adaptive-Network-Based Fuzzy Inference System (ANFIS) methods are used for the prediction and simulation of cross-shore sediment transport in the swash zone. The ANFIS and FIS are established using the free stream velocity time series, Shields parameter and antecedent cross-shore sediment transport of the available swash experimental data. Statistical measures were used to evaluate the performance of the models. Numerical experiments showed that the neuro-fuzzy approach provided satisfactory predictions in sediment transport modeling without incorporating different multipliers for uprush and backwash. Furthermore, the numerical results revealed that the ANFIS-based predictions are slightly superior to the FIS-based predictions.     

我国大学本科教学管理制度的反思与重建

本文从教学管理制度是协调与规范教学管理者与学生之关系的准则这一逻辑出发，运用访谈调查、问卷调查、制度文本分析等多种方法，深刻反省了现行本科教学管理制度制约学习自由的缺陷，分析了导致大学学习自由缺失的主要原因，并在解剖制度建设中教学自由与教学控制的矛盾的基础上，提出了建构以学生为中心的本科教学管理制度的若干建议。