New nondestructive test method with empirical research using local hysteretic loop characteristics

提出了一种利用局部磁滞回线特性的无损检测新方法。首先,研究了钢板内部缺陷对其动态磁导率分布的影响规律。其次,探讨了变励磁条件下局部磁滞回线的形成机理,并建立了动态磁导率与局部磁滞回线之间的关系模型。再次,根据所建立的关系模型,提出了一种利用局部磁滞回线特性实现对钢板缺陷进行无损检测的新方法,并给出检测系统的实现方案。最后,通过3d有限元法对实验模型进行仿真,并开展了一系列的物理实验进行了验证。结果表明,缺陷对钢板动态磁导率分布的影响显著,可利用局部磁滞回线特性来检测磁导率变化,从而达到检测内部缺陷,甚至背面缺陷的目的。所提新方法无需检测静态漏磁场磁感应强度,因此有效减小了磁化器体积。A new nondestructive test method based on local hysteretic loop characteristics is proposed in this paper.First of all,the influence law of the steel plate internal defects on the dynamic permeability distribution is studied,and the formation mechanism of the local hysteretic loop under the variable magnetic excitation condition is discussed.Secondly,the relation model between the dynamic permeability and local hysteretic loop is established.Furthermore,according to the proposed relation model,a new nondestructive test method of steel plate defects based on the local hysteretic loop characteristics is proposed,and the implementation scheme of the test system is given.Finally,the 3D finite element method was used to simulate the experiment model and a series of physical experiments were carried out to verify the proposed method.The results show that the steel plate defects have significant influence on the dynamic permeability distribution; the local hysteretic loop characteristics can be used to detect the permeability variation,and achieve the goal of detecting the internal defects of the steel plate,even the defects on the back of the steel plate.The proposed new method does not require to test the static leakage magnetic field,which reduces the volume of the magnetizing apparatus effectively.国家自然科学基金(51177141); 中央高校基本科研业务项目(2010121041); 航空基金(2012ZD68003)项目资

New method of variable excitation MFL testing under the condition of small magnetizing apparatus

为解决常规储罐和管道的漏磁检测(Mfl)方法中磁化器体积大、耗能多的缺点,提出了一种小型磁化器条件下的变励磁Mfl检测新方法。首先,分析了小磁化器条件下被测钢板磁化状态随外部励磁强度的变化特性,推导了偏置磁化条件下励磁通变化量与漏磁场变化率的关系模型;其次,根据所建立的关系模型,设计了一种新型变励磁Mfl检测探头,并给出变励磁Mfl法的系统实现方案;再次,结合实现方案,搭建了变励磁Mfl相应的实验平台;最后,在该平台上,开展了一系列的物理实验并对实验结果进行了深入讨论。实验结果表明,所提变励磁Mfl法无需对被测钢板进行局部饱和磁化,适合小型磁化器条件并具有较高的灵敏度。变励磁Mfl法为漏磁检测领域提供了一种新的检测思路。In the conventional method of magnetic flux leakage( MFL) testing,the magnetizer is in big volume and with more energy consumption.To solve the problem,a new method of variable excitation MFL testing under the condition of small magnetizer is proposed.First of all,the state of magnetized steel along with the change of the external excitation's intensity under the condition of small magnetizer is analyzed.Secondly,according to the established model,a new type of testing probe for the variable excitation of MFL is designed and a new implementation scheme is proposed.Furthermore,combining with the implementation scheme,an appropriate testing platform of the variable excitation MFL is set.Finally,a series of physical experiments on the platform are carried out and the results of the experiment were discussed.The experimental results show that the proposed method don't need to make local saturation magnetization of tested steel plate,which is suitable for the condition of small magnetizer with higher sensitivity.The new method provides a new testing idea for MFL testing field.国家自然科学基金(51177141); 中央高校基本科研业务项目(2010121041); 航空基金(2012ZD68003)资助项

一种α,α'-双亚苄基环烷酮化合物的绿色合成方法

物理化学带填

Zwitterionic Liquid Supported SBA-15: a Multifunctional Heterogeneous Catalyst Material

Ionic liquids have attracted considerable attention in the fields of chemistry and chemical engineering due to their unique properties including extremely low volatility, nonflammable, wide liquid range and good solubility. Particularly, task-specific ionic liquids (TSILs) exhibit a great potential in replacement of conventional catalysts1 because of their designable property. Despite infinite utility, the application of TSILs are always limited by some disadvantages, such as high synthesis cost, high viscosity, difficulties of mass transfer and separation. Therefore, immobilization of TSILs on suitable solid supports is highly desirable, which is an alternative approach to solve above-mentioned problems.2 In this work, a zwitterionic liquid precursor N-(3-triethoxysilylpropyl)-N-(3-sulflopropyl)-amine (SNSA) was synthesized and characterized, which was further immobilized on SBA-15 mesoporous materials by using sol-gel and grafting methods respectively. The as-synthesized materials were characterized by X-ray diffraction (XRD), solid-state 29Si and 13C CP/MAS NMR, N2 adsorption, TEM, SEM and elemental analysis, which indicated that the precursor had been incorporated into the hexagonal silica matrix of SBA-15. Interestingly, the materials could be acidified or alkalized to form the functionalized ionic liquid supported phase (Scheme 1). Aldol condensation3 of 4-nitrobenzaldehyde and acetone (Scheme 2) was used as a model reaction to test the activity of the alkalized product. The conversion ratio was 77%, and the selectivity was 90% for hydroxide compound. The catalysts could be reused for three times without significant change of the catalytic activity

The Ionothermal Synthesis of Open-Framework Cobalt Phosphate Co7H4(PO4)6

Ionothermal synthesis (ITS) as a new synthesis method of microporous materials has attracted more and more attention in recent years. It has many advantages comparing with hydrothermal and solvothermal methods1. First of all, the reaction can take place at ambient pressure, eliminating the safety concerns. Secondly, Ionic Liquids (ILs) play both solvent and structure-directing agent roles, removing the competition interaction between template-framework and solvent-framework, and leading potentially to a new framework. Up to now, most studies of ITS are concentrated on [emim]Br (emim = 1-ethyl-3-methylimidazolium) and the synthesis of aluminophosphates2. In this work, we tried to use BF4- based dialkylimidazolium ILs to synthesize new transition metal borophosphate. Unexpectedly, a known phosphate Co7H4(PO4)63 was obtained. Typically, [bmim]BF4 (bmim = 1-butyl-3-methylimidazolium), H3PO4 and Co(OAc)2•4H2O with a molar ratio of 9 : 1 : 1 were charged into a 15 mL Teflon-lined stainless steel autoclave and heated under 180 ℃ for 5 days. Stick-like blue single crystals were received as final product. The crystal structure of Co7H4(PO4)6, as shown in Fig.1, was determined by the single crystal X-ray diffraction method. Co7H4(PO4)6 crystallizes in the space group P-1 (No.2), with cell parameters of a = 6.471(3) Å, b = 7.881(3) Å, c = 9.488(4) Å, α = 104.288(6)°, β = 109.062(5)° and γ = 101.345(5)°. The effects of different anions were studied and it was found that when [bmim]Br or [bmim]Cl was used, under the same condition, even no solid products were formed. This shows that halogen anions have a negative effect on the process of crystallization. In conclusion, this work shows that the synthesis of metal phosphates by using ITS method is possible after selecting of the right ionic liquid as solvent