Note on filon-type integration for higher order exponential time differencing methods in stiff systems

The Filon-type quadrature is efficient for highly oscillatory functions — Fourier transforms. Based on Cox and Matthews’ ETD schemes, the higher order single step exponential time differencing schemes are presented based on the Filon-type integration and the A-stability of the two-order Adams-Bashforth exponential time differencing scheme is considered. The effectiveness and accuracy of the schemes is tested. Foundation item: Projects(02JJY2006, 03JJY2001) supported by Natural Science Foundation of Hunan Province; project supported by JSPS Fellowship Research Program     

热镀锌钢上锌花的研究进展

由大晶粒组成的锌花是热浸锌镀层有别于其它镀层的显著特征,综述了热镀锌钢上锌花的研究现状,包括锌花的外观形貌、形貌与锌晶体学位向的关系、合金添加剂的作用以及锌花对热浸锌镀层腐蚀性能和力学性能的影响.从过冷度、晶体学位向和润湿作用3个方面论述了锌花的形成机制.     

Study of structural free volumes in the supercooled liquid state of bulk amorphous ZrTiCuNiBe

Structural free volumes in amorphous alloys play an important role for a lot of solid state properties. In this paper, we report on the determination of both the size and the chemical environment of structural free volumes in bulk amorphous Zr₄₁Ti₁₄Cu_12.5Ni₁₀Be_22.5 and particularly in the supercooled liquid state of the alloy by making use of measurements of the positron annihilation radiation. The free volumes in the supercooled liquid state are detected to be surrounded dominantly by Be and Ti atoms together with less Zr atom. The present investigations are of interest for atomic-scale understanding of the atomic processes in bulk amorphous alloys.     

Synthesis of silica nanocubes by sol–gel method

A novel approach was employed in the fabrication of silica nanocubes with controlled size and shape. The silica nanocubes were highly dispersed with width of about 30 nm and product with high purity. A small amount of tartaric acid was introduced in the TEOS hydrolysis process. In this work tartaric acid as the organic template, was formed on the surface of hydrous silica colloidal particles. The organic template ordered by carboxyl, led to the self-assembly of amorphous silica sol encapsulated into cubic matrixes, and the organic template was packed into 3D structure.     

Fabrication and characterization of direct patterning ferroelectric Sr0.9Bi2.1Ta2O9 thin films by photosensitive sol–gel solution

Photosensitive ferroelectric Sr_0.9Bi_2.1Ta₂O₉ (SBT) precursor solutions were synthesized using strontium ethoxide chelated with ethylacetoacetone, tetramethylheptanedionato bismuth and tantalum ethoxide chelated with ethylacetoacetone. SBT thin films with 200 nm thickness were prepared on Pt/TiO₂/SiO₂/Si substrates using the spin coating method. As UV light exposure time to the SBT thin film increased, the intensity of the UV absorption peak of the metal β-diketonate decreased due to metal–oxygen–metal bond formation, which led to decreased solubility of SBT thin film. The solubility difference enabled direct patterning of thin films that had ferroelectric properties. The ferroelectric properties of the UV irradiated SBT thin films were superior to those of the non-UV irradiated films. Pr/Ps and 2 Pr values (at 3 V) of SBT thin films improved approximately 8% and 5%, respectively, with UV irradiation.     

一种矢量控制型变频器的设计方案介绍

对美国A B公司生产的 1336IMPACT变频器进行了深入研究 ,剖析了该型号变频器的矢量控制算法、参数自整定方法和无速度传感器运行方式下的参数辨识方法等细节问题 ,并在此基础上总结出了系统的控制方案和设计思想 ,得到了详细的控制系统结构     

Influence of interfacial strength on the fracture toughness of glass-ceramic matrix composites

Nine kinds of glass-ceramic matrix composites with different compositions and interfacial strength (τ _s) were prepared. The influence of τ _s on the fracture toughness(K _1c) of composites was studied. It was discoved that, for the system no chemical reaction taking place at the interface, K _1c increased proportionally with τ _s increasing at the first stage, then decreased when τ _s reached a certain value. According to this result, a model of relationship between τ _s, thermal mismatch (Δα _r) and K _1c was built up. If a chemical reaction took place and a new phase was formed in the interface, the K _1c of composite was effected by the combination of τ _s, chemical bonding, radial interfacial stress and other factors. Project supported by the National Natural Science Foundation of China Synopsis of the first author Wang Lingsen, professor, born in 1938, current research field: special ceramic and ceramic matrix composite, etc.     

AN EFFICIENT ACTIVATIOR ON FLOTATION OF FINE ANTIMONY OXIDE

Recoveryoffineantimonyoxidewithfrothflotationisoneofthemostdifficultproblems.Theoxidemineralisnotonlytobeslimedeasily,butalsotendstoformcolloidinwatersolution,andtoitshydrolysis,onitssurface,thereexistsSbO,inalkalinesolutionandSbO inacidicsolution.UPtonow,traditionalgravityconcentrationmethodhasbeenuniversallyusedtorecoverantimonyoxide.Nowsomeantimonymillsstilluseshakingtabletechnique,buttherecoveryisonlyabout20%.Inflotationsystem,thecolloidofantimonyoxideiseasilyadheredonthesurfaceofsilicif…     

统一电力市场中兼具市场效率与经济公平的实现

南方电网中的五省(区)间差异巨大,为了建立统一的区域电力市场,在建立公平的交易机制和交易规则、促进自由竞争、提高市场效率的同时,必须考虑交易结果对区域内经济协调发展的影响。作者将关税理论应用于南方区域电力市场,结合各地区经济发展水平,提出了对自由竞争结果进行适度宏观调控的基本思路。算例分析表明,该思路是可行的。