Learning fuzzy rules from fuzzy samples based on rough set technique

Although the traditional rough set theory has been a powerful mathematical tool for modeling incompleteness and vagueness, its performance in dealing with initial fuzzy data is usually poor. This paper makes an attempt to improve its performance by extending the traditional rough set approach to the fuzzy environment. The extension is twofold. One is knowledge representation and the other is knowledge reduction. First, we provide new definitions of fuzzy lower and upper approximations by considering the similarity between the two objects. Second, we extend a number of underlying concepts of knowledge reduction (such as the reduct and core) to the fuzzy environment and use these extensions to propose a heuristic algorithm to learn fuzzy rules from initial fuzzy data. Finally, we provide some numerical experiments to demonstrate the feasibility of the proposed algorithm. One of the main contributions of this paper is that the fundamental relationship between the reducts and core of rough sets is still pertinent after the proposed extension.     

氢氧化镁阻燃环氧树脂热降解性能研究

用氢氧化镁制备了阻燃环氧树脂复合材料,用极限氧指数(LOI)、烟密度等级(SDR)来表征其阻燃消烟性能,用热重仪和热重-质谱联用仪分析了氢氧化镁阻燃环氧树脂体系的热稳定性和热降解过程,并探讨了氢氧化镁阻燃环氧树脂的机理。结果表明:随着氢氧化镁用量的增加,复合材料的LOI不断提高,当氢氧化镁用量为47.37%时,环氧树脂/氢氧化镁阻燃体系的LOI达到27.5%,烟密度降至61.73%;氢氧化镁的加入使复合材料的最大热失重速率提高,促进了复合材料的迅速分解,使分解的温度区间变窄,降低了分解过程中二氧化碳、可燃性小分子、苯类和苯酚类物质的释放量。     

基于哈希学习的投票样例选择算法

随着数据的海量型增长,如何存储并利用数据成为目前学术研究和工业应用等方面的热门问题。样例选择是解决此类问题的方法之一,它在原始数据中依据既定规则选出代表性的样例,从而有效地降低后续工作的难度。基于此,提出一种基于哈希学习的投票样例选择算法。首先通过主成分分析（PCA）方法将高维数据映射到低维空间;然后利用k-means算法结合矢量量化方法进行迭代运算,并将数据用聚类中心的哈希码表示;接着将分类后的数据按比例进行随机选择,在多次独立运行算法后投票选择出最终的样例。与压缩近邻（CNN）算法和大数据线性复杂度样例选择算法LSH-IS-F相比,所提算法在压缩比方面平均提升了19%。所提算法思想简单容易实现,能够通过调节参数自主控制压缩比。在7个数据集上的实验结果显示所提算法在测试精度相似的情况下在压缩比和运行时间方面较随机哈希有较大优势。     

MXenes and their derivatives for advanced aqueous rechargeable batteries

Aqueous batteries are emerging power sources due to the merits of high safety, low cost, environmental friendliness, etc. However, several key issues such as narrow electrochemical stability window, dissolution of active materials, notorious dendrite growth and poor cycling lifespan hinder the practical application of aqueous batteries. Recently, 2D MXenes and their derivatives for aqueous batteries have exhibited substantial encouraging progress due to the special characters. The related researches have dramatically increased since 2019. However, comprehensive reviews on this topic are rare. Herein, the latest advances of MXenes and their derivatives for aqueous Zn-, Li-, Na- and dual-ion batteries are systematically reviewed, including cathode fabrication, anode design and electrolyte optimization, etc. This review aims to boost rational design strategies for practical application of aqueous batteries by combining the fundamental principle and research developments. Firstly, the fundamental background of aqueous rechargeable batteries is introduced and the superior merits for electrochemical energy storage of MXenes and their derivatives are summarized. Subsequently, the design strategies and internal mechanism of MXenes and their derivatives for aqueous batteries are comprehensively summarized and discussed. Finally, perspectives on the future design tactics of MXenes-based materials for aqueous batteries are proposed.     

从民间艺术看民族情感

民间艺术是民族文化的母体与根基,承载了民族的情感,在中华文化的历史演进过程中占有极其重要的地位.千百年来,中国人民在创造了丰富的物质生活的同时,也创造出了精彩绝伦的民间艺术,将自己真挚、纯朴的情感,融于民间艺术的创造的全过程.这其中既有亲情、也有爱情.在我们今天看来,这种情感打破了生活的冷漠与疏离,唤起了人性中最美好的一面.     

Preparation of Y2O3 Buffer Layer on LaAlO3 Substrate by TFA-MOD Method

Chemical solution deposition is a promising technique for fabrication of high-temperature superconducting films and oxide buffer layers due to its reproducibility and low cost. In this work, Y₂O₃ buffer layers were prepared on (100) LaAlO₃ substrates by mental organic deposition method using trifluoroacetate. The resulting Y₂O₃ films crystallized as a single phase at 900°C and showed a low degree of c-axis orientation. The scanning electron micrography showed that the surface of the films was smooth with a uniform grain size of approximately 10 nm.     

拟阵贪婪算法在景区装饰灯中的应用

该文立足于实际,就如何在景区设置装饰灯问题给出了数学模型及求解步骤。在解决过程中采用了拟阵的贪婪算法,此算法简洁、易行。     

Caffeine Molecular Imprinted Microgel Spheres by Precipitation Polymerization

Imprinted uniform microgel spheres were prepared by precipitation polymerization. Acetonitrile was used as the dilute solvent with MAA as the monomer, EDMA as the crosslinker and caffeine as the print molecule. Comparison of caffeine adsorption on molecular imprinted and blank microgel spheres was made. Langmuir model was used to fit the adsorption data. It was found that the caffeine imprinted microgel spheres show specific binding sites to the target molecules. A binding study of caffeine on imprinted microgel spheres was made by Scatchard analysis; the dissociation constants (K_D) and the maximum binding capacity were K_D= 1.84×10⁻⁴mol/L,Q _max = 16.98 μmol/g for high affinity binding site and K_D=1.33×l0⁻³ mol/L, Q_max=46.84 μmol/g for lower affinity binding site, respectively This microgel spheres can be useful affinity adsorbents in further applications.     

Aflatoxin M1 in UHT milk consumed in Turkey and first assessment of its bioaccessibility using an in vitro digestion model

Contamination of milk and dairy products with aflatoxin M₁ (AFM₁) continues to receive increased attention because of its potential health hazard to humans. The first aim of this study was to know the occurrence and levels of AFM₁ in whole UHT milk from main processors in Turkey in order to make a preliminary exposure assessment. A total of 40 milk samples were analysed for AFM₁ using high performance liquid chromatography with fluorescence detection (HPLC-FD) after immunoaffinity column clean-up. Aflatoxin M₁ was detected in 20% of samples at levels ranging from <0.004 to 0.076 μg l⁻¹. Only two samples contained AFM₁ above the EU limit of  0.05 μg l⁻¹.The second aim of this study was to determine the bioaccessibility of AFM₁ from milk using an in vitro digestion model. The bioaccessibility of AFM₁ in spiked and naturally contaminated milk samples ranged from 80.5 to 83.8% and from 81.7 to 86.3%, respectively. No difference (P > 0.05) in AFM₁ bioaccessibility was found between spiked and naturally contaminated milk samples. This study also assessed the binding of AFM₁ by six probiotic bacteria under simulated gastrointestinal conditions. A 15.5–31.6% reduction in AFM₁ bioaccessibility was observed in the presence of probiotic bacteria. Based on the results obtained in the present study, the mean daily intake of AFM₁ through milk consumption was estimated as 0.008 ng kg⁻¹ b.w. day⁻¹ for Turkish adults.     

在小间隙放电中用Bernoulli定理分析电极移动速度效应

小间隙静电放电中电极移动速度对放电参数影响的内部因素,是受到很多研究者关心的问题.通过对实验数据的系统分析,应用流体力学中Bernoulli定律,对放电参数电极速度效应的内部原因,提出了较好的理论解释.电极的快速运动速度造成了放电间隙气体压强的下降,从而加速了载流子从电极到靶的运动过程,进而明显改变了放电参数的数值.初步的数值计算表明,表面过程因电极快速移动得到了加强.这对于电极移动速度效应进一步的研究,给出了一种较为明确的方向.