Free vibration analyses by boundary element method using component mode synthesis

The boundary element method for dynamic analysis of two dimensional structures was developed by Nardini and Brebbia in 1983. Free vibration analysis of structures by BEM results in a generalized eigenproblem with coefficient matrices nonsymmetric and full. So, it costs a lot of CPU time to solve the eigenproblem. In order to reduce the cost the improved free interface coupling method has been adopted. By aid of lower eigenvectors and residual modes the degrees of freedom of substructure equaion of dynamic equilibrium can be reduced. By assembling the reduced substructure equations, the system of equations for the whole structure will be obtained. By using the traction and displacement compatibility conditions on the interface, the second transformation matrix has been developed for further reduction of system equations. The technique has been applied to some specific examples which give the evidence that the method is satisfactory and efficient.     

Actinium coordination chemistry: A density functional theory study with monodentate and bidentate ligands

In the current study, the coordination chemistry of nine-coordinate Ac(III) complexes with 35 monodentate and bidentate ligands was investigated using density functional theory (DFT) in terms of their geometries, charges, reaction energies, and bonding interactions. The energy decomposition analysis with naturals orbitals for chemical valence (EDA-NOCV) and the quantum theory of atoms in molecules (QTAIM) were employed as analysis methods. Trivalent Ac exhibits the highest affinities toward hard acids (such as charged oxophilic donors, fluoride), so its classification as a hard acid is justified. Natural population analysis quantified the involvement of 5f orbitals on Ac to be about 30% of total valence electron natural configuration indicating that Ac is a member of the actinide series. Pearson correlation coefficients were used to study the pairwise correlations among the bond lengths, ΔG reaction energies, charges on Ac and donor atoms, and data from EDA-NOCV and QTAIM. Strong correlations and anticorrelations were found between Voronoi charges on donor atoms with ΔG, EDA-NOCV interaction energies and QTAIM bond critical point densities.     

基于嵌入式linux的输电线路杆塔倾斜度自动化测试系统的设计与实现

在总结实际工作经验的基础上,针对在测试输电线路杆塔倾斜度在线监测系统过程中存在的搭建测试环境复杂、测试步骤繁琐、测试周期长、测试效率低、测试结果格式混乱等问题,设计了一个使用客户端/服务器架构的自动化测试系统,详细论述了该系统的设计方案和实现原理;客户端基于嵌入式linux系统,采用多线程技术,通过以太网,使用定制的通信协议与服务端通信,能够在收到服务端指令后自动完成输电线路杆塔倾斜度在线监测系统硬件模块的功能测试;服务端采用python和PyQt开发,能够跨平台运行,使用多线程技术,实现了图形化控制客户端、查看客户端测试状态、保存测试日志、生成标准化的xls和pdf格式的测试报告等功能;实际应用表明,该系统有效可靠结果准确,提高了测试效率,提升了输电线路杆塔倾斜度在线监测系统的可靠性。     

Interplay effect on simultaneous catalytic oxidation of NOx and toluene over different crystal types of MnO2 catalysts

This paper firstly investigated the interplay effect on simultaneous catalytic oxidation of NO and toluene. Four tunnel-structure polymorphs, i.e., α-MnO₂, β-MnO₂, γ-MnO₂ and δ-MnO₂, were synthesized to compare individual and simultaneous oxidation of NO and toluene. Results demonstrated that toluene significantly inhibited NO conversion that near zero efficiencies were observed at low temperature over the four catalysts. Subsequently, NO oxidation efficiency climbed rapidly to the equivalent value as absence of toluene. In addition, presence of NO also elevated toluene conversion into higher temperature of 10–20 °C than that without NO. The reaction between toluene and oxygen took the superiority during simultaneous oxidation with NO. NO oxidation efficiency started to increase until toluene degradation approaching to the equilibrium. However, this competition seemed to be negligible at high temperature that both toluene and NO attained high conversion efficiencies. These findings provide a feasible way for simultaneous removal of NO_x and VOCs using catalytic oxidation as well as selecting an optimal temperature window.     

生物介质萃取技术研究进展

生物介质萃取技术,即以生物(或仿生)材料如细胞、细菌和蛋白质等为萃取吸附固定相的样品制备技术。近年来该技术在多个领域得到了较为广泛的应用,例如利用生物材料对金属的吸附性质用于分析环境样品中微量金属元素;利用生物材料(免疫蛋白)的抗原–抗体结合性质用于食品和药品中毒素的检测等。主要针对近年来生物材料作为样品预处理介质用于微量重金属离子富集及霉菌毒素纯化富集两个方面的应用进行概述,为生物介质萃取技术的进一步推广应用提供参考。     

Maleated glycidyl 3‐pentadecenyl phenyl ether with styrene: synthesis and application as compatibilizer in SBR/silica composite

Maleated glycidyl 3‐pentadecenyl phenyl ether with styrene (MGS) was synthesized from glycidyl 3‐pentadecenyl phenyl ether (GPPE), maleic anhydride (MAH) and styrene (St) in the presence of AIBN initiator at 80°C, and then the resultant MGS was applied as a compatibilizer to prepare SBR/silica composites. Meanwhile, the commercial compatibilizer bis‐(triethoxysilylpropyl) tetrasulfide (named Si69) added into composite was also prepared for comparison purpose. The synthetic MGS structure was characterized by GPC and FTIR, and SBR/silica compounds with different compatibilizer were analyzed using RPA, DMA and so on. The results showed that M?n and M?w of MGS were 19,538 g/mol and 23,790 g/mol, respectively. The curing time of compounds with MGS increased, whereas the maximum and minimum torques decreased. The addition of MGS decreased Payne effect of SBR/silica compounds, which implied an improvement of silica dispersion in the compounds. Bound rubber content of compound with MGS was about 1.7 times higher than the absence and 1.5 times higher than that with Si69. The tensile strength of the composites was improved by increasing compatibilizer loading, and the optimum value was observed at 6 phr of MGS. Meanwhile the use of MGS can improve the anti‐aging property of composite. According to DMA, the tanδ value at 0°C of composite with MGS was higher than composite without compatibilizer suggesting that MGS can improve the wet skid resistance of composite. The SEM analysis revealed that introduction of MGS enhanced the compatibility between SBR and silica. Copyright © 2015 John Wiley & Sons, Ltd.     

Direct numerical simulation of a particle-laden low Reynolds number turbulent round jet

Direct numerical simulation method is used for the investigating of particle-laden turbulent flows in a spatially evolution of low Reynolds number axisymmetric jet, and the Eulerian–Lagrangian point-particle approach is employed in the simulation. The simulation uses an explicit coupling scheme between particles and the fluid, which considers two-way coupling between the particle and the fluid. The DNS results are compared well with experimental data with equal Reynolds number (R_e = 1700). Our objects are: (i) to investigate the correlation between the particle number density and the fluctuating of fluid streamwise velocity; (ii) to examine whether the three-dimensional vortex structures in the particle-laden jet are the same as that in the free-air jet and how the particles modulate the thee-dimensional vortex structures and turbulence properties with different Stokes number particles; (iii) to discover the particle circumferential dispersion with different Stokes number particles. Our findings: (i) all the particles, regardless of their particle size, tend to preferentially accumulate in the region with large-than-mean fluid streamwise velocity; (ii) the small Stokes number particles take an important part in the modulation of three-dimensional vortex structures, but for the intermediate and larger sized particles, this modulation effect seems not so apparent; (iii) the particle circumferential dispersion is more effective for the smaller and intermediate sized particles, especially for the intermediate sized particles.     

Stochastic Kolmogorov-type system with infinite delay

The paper considers a stochastic functional Kolmogorov-type population system with infinite delay under the general probability measures. Main aim is to show that the environment noise will not only suppress a potential population explosion but also make the solution be stochastically ultimately bounded and asymptotic stable. Moreover, two stochastic functional Lotka-Volterra equations as examples are provided to illustrate the main results.