Science Letters:Chemically processed Nb-doped SrTiO_3 films and properties

Homogeneous, crack-free SrNbxTi1-xO3 thin films on （110） silicon substrates were successfully fabricated by sol-gel processing. The optimum route and conditions were systematically investigated. Sr（OAc）2 glacial acetic acid solution, after being refluxed and reacted with tartrate, formed Sr（OAc）2（C4H6O6）2; Ti（OBu）4 formed Ti（OAc）4-x（AcAc）x. after having the ligand partially exchanged with AcAc, while Nb（OC2H5）5 formed （OAc）2Nb（AcAc） （C4H606）by exchanging of ligand in glacial acetic acid with （CH3CO）2O. All the metal species after undergoing partial hydrolysis and polymerization with hydroxyl or oxygen, formed SrNb,Ti1-xO3 cluster sol. Methyl cellulose （MCL） caused SrNbxTi1-xO3 sol to have polymeric structure and easily form films. SrNbxTi1-xO3 films with perovskite were subsequently formed after being annealed at 650-750 ℃ for 60 min in 25% N2＋75% H2 （volume ratio） atmosphere. Resistivity of the SrNb0.1 Ti0.9O3 films at room temperature was 64 μΩ·cm, a particular T2 temperature dependence of the resistivity, from 25 K up to room temperature, was observed.

某非对称连体超高层结构抗震性能分析

晟通梅溪湖国际总部中心属超B级高度的连体超高层结构,存在多项不规则项,核心筒相互正交,扭转效应明显,结构受力复杂。其中核心筒的布置、连接体的设计及加强层的设置均是结构设计中的难点和重点。结合工程实例,介绍了结构体系、超限项判断、连接体的设计、加强层的设置等。对整体结构进行了小震、中震、大震作用下的抗震性能分析,对结构进行了施工过程、楼板应力和连接体专项等关键问题分析,并完成了0°和45°模型在水平力作用下的受力及变形分析。分析结果表明,通过设置较少的加强层且未设置环带桁架,在达到较好的立面效果的同时,结构还可以获得较好的抗震性能,能够达到预设的抗震性能目标。通过关键问题分析,获得了合理的施工顺序以及楼板局部加强区域,连接体的抗震性能良好,能够很好地协同双塔的水平变形。

基于序贯均匀设计的支持向量机超参数的优化方法

求解支持向量机超参数的优化问题可通过多因素多水平的试验设计来实现。运用序贯均匀设计的方法对高斯径向基核函数参数σ和惩罚因子C进行优化,可以快速且有效地找到最优参数。仿真结果表明,运用序贯均匀设计比直接运用均匀设计效果更佳,且比网格搜索法更具稳健性。