基于梯度加权类激活热力图的卷积神经网络故障诊断模型鲁棒性分析

深度学习近年来在故障诊断领域受到广泛应用,但基于深度学习的故障诊断模型缺乏工程上的物理解释性,难以保证其故障诊断结果的稳定性。以轴承为例,建立了以小波时频图像为故障诊断依据的卷积神经网络模型(convolutional neural network, CNN),提出了一种基于梯度加权类激活热力图(gradient-weighted class activation map, Grad-CAM)的网络模型鲁棒性分析方法,并利用美国凯斯西储大学(Case Western Reserve University, CWRU)轴承数据集进行验证。首先,将故障直径轴承数据以不同方式混合并训练大、小多个模型。其次,利用Grad-CAM方法,建立时频区域与故障模式之间的联系。最后,利用其他工况下的轴承故障数据,以及含噪数据进行测试,并根据结果结合模型最注重的时频区域进行分析。结果表明,基于深度学习的轴承故障诊断模型在参数较少时更加注重低频区域,并能使其具有更好的鲁棒性。     

Synthesis and magnetic properties of trinuclear copper(II) complexes bridged by dimethylglyoximate groups

Summary New three Cu^II-Cu^II-Cu^II homotrinuclear complexes have been synthesized, namely [Cu(dmg)₂{CuL}₂](ClO₄)₂ [L = 5-nitro-1,10-phenanthroline (5-NO₂-phen), 4,4-dimethyl-2,2-bipyridiine (DMbpy), tetramethylenediamine (TMDA) and dimethylglyoximate ion (dmg)^2-]. The magnetic susceptibilities of complexes (1) (L = 5-NO₂-phen) and (2) (L = DMbpy) were measured in the 4.2–300 K range, giving the parameters,J = -335cm^-1 (1) andJ= -327.5cm^-1 (2). The results demonstrate a very strong antiferromagnetic exchange interaction between the adjacent copper(II) ions.     

Theory of solid solubility for rare earth metal based alloys

Both parabola and ellipse separating schemes are used to study the solid solubilities for the binary alloy systems based on the 13 rare earth metals. It has been found that the soluble elements can be separated from the insoluble ones by a parabolyy ₁=a?bx ₁ ² or an ellipse(x ₂?m)²/c²+(y₂?n)²/d²=1. The results show that the overall reliabilities of the solid solubilities for the 897 binary alloys based on the rare earth metals are 89.2% and 92.8% for the parabola and ellipse regularities respectively. The constants a and b in the parabola equation, andm, n, c andd in the ellipse equation are discussed, which can be related to some appropriate parameters for each host metal respectively.     

μ-phenoxo-bridged binuclear copper(II) complexes

Summary Two -phenoxo-bridged binuclear copper(II) complexes, [Fsal(GG)₂Cu₂Cl₃]·H₂O (1) containing an exogenous chloride-bridge and [Fsal(GG)₂Cu₂(OH)](ClO₄)₂·H₂O (2) containing an exogenous hydroxide-bridge, where {Fsal(GG)₂ = 2,6-bis[N-(acetylglycine)-imino-methylene]-4-methylphenol}, were synthesized. The complexes were characterized be several spectroscopic methods. According to variable temperature magnetic susceptibility measurements (4–300 K), the hydroxide-bridged complex (2) has a weak antiferromagnetic spin exchange integral (J =- 23.6 cm), while the chloride complex (1) has an unusual weak ferromagnetic spin exchange integral (J = + 30.9 cm); both complexes have similar optical spectra in the aqueous solutions.     

CHAOS FOR MIXING TRANSFORMATIONS

ＣＨＡＯＳＦＯＲＭＩＸＩＮＧＴＲＡＮＳＦＯＲＭＡＴＩＯＮＳ￥ＬＩＡＯＧＯＮＧＦＵ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｈｅｍａｔｉｃｓ,ＪｉｌｉｎＵｎｉｖｅｒｓｉｔｙ,Ｃｈａｎｇｃｈｕｎ１３００２３,Ｃｈｉｎａ．）Ａｂｓｔｒａｃｔ：Ｆｏｒａｃｌａｓｓｏｆｍ...     

Progress in magnetic couple system of nitroxidemetal complexes

Metal_radical method is an effective approach to synthesizing magnetic molecular materials. With the development in decades, the study of nitroxide_metal complexes has made great progress in model, theoretical treatment and design of molecules. Several mechanisms of the metal_radical magnetic coupling are discussed. Molecular magnetic project of nitroxide_metal complexes has made fruitful achievements, but crystal magnetic project is difficult to be controlled, and it is a challenge to chemists. The studies on nitronyl nitroxide_metal complexes are summarized. At present, there are three major approaches to increasing the T c of the metal_radical compounds: (ⅰ) Searching for nitronyl nitroxide ligands that can yield 3_D ferro_ or ferrimagnetic structures; (ⅱ) decorating the structure of radicals with the aim to enhance the coordinate capability of radicals; (ⅲ) grafting polynitroxide radicals as a versatile bridge. The third approach, namely searching for polynitroxide ligand, will serve as a hopeful strategy for exploring higher T c radical molecule_based magnets.     

新型食品抗氧剂TBHQ的合成研究

在酸催化下,用对苯二酚和叔丁醇合成了叔丁基对苯二酚（ＴＢＨＱ）,它是一种食用新型抗氧剂。采用正交试验法探讨了各种反应因素对产率的影响。指出在物料比对苯二酚：叔丁醇：催化剂：溶剂为１∶１∶１．２∶２．９（ｍｏｌ）,反应温度为９０℃时,总共反应２．５小时,ＴＢＨＱ得率最高,可达５５％以上。     

均匀设计在氯乙酸乙酯合成中的应用

文章采用均匀设计法探讨了固体超强酸Ｆｅ２Ｏ３／ＳＯ２－４催化酯化合成氯乙酸乙酯的工作条件。试验设计合理、操作简单、省时省力。酯化工艺“三废”少,得率达８０％以上。     

紫苏微量元素的测定

利用火焰原子吸收涨研究了紫苏根、茎、叶中８种微量元素的含量,并通过实验拟定了各待测元素的最佳分析条件,呼元素的回收率在９６－１０５％之间,相对偏差小于６％,方法快速、准确、实用性强、同时,对紫苏的药理作用进行了探讨,为办的开发提供实验依据。