基坑失稳时土的各向异性对管线的位移影响

在考虑粘土的各向异性时,对由外因引起的基坑失稳而导致的位于基坑附近,且与基坑方向成一角度的管道的变形进行了分析,得到了在考虑粘土的各向异性时,计算弯曲变形和拉伸变形的公式,并对计算结果进行了分析,得到了一些有益的结果.     

异步电动机无速度传感器控制的成就与发展

本文着重点评IEEE-IES2006年第1期《感应电动机无速度传感器控制专辑》中霍尔茨教授撰写的《客座编者的话》和综述论文,两篇文章按照无速度传感器控制技术的应用和研究进展把它归纳为两大类:(1)基于电动机的基波模型,(2)利用电机的各向异性性质,与笔者所分析的三条思路不谋而合。最后,进一步指出两文所显示的先进技术。     

Systematic study of anomalous fragment anisotropies in subbarrier complete fusion—fission reactions

The complete fusion-fission is separated from the transter-induced-fission with the fragment folding angle technique.The cross sections and fragment angular distributions for the complete fusion-fission reactions of 11B 238U(237Np),237NP,16O 232Th(238U) and 19F 232Th at near-and sub-barrier energies have been measured.The present fusion and fission standard models can reproduces both the excitation functions and the fragment anisotropies for the systems of 11B 238U(237Np)and 12C 237Np;but fail to explain both the experimental data for the other 3 systems simultaneously,The evidence of the entrance-channel dependence of fission-fragment anisotropies is revealsed by comparison of the 11B 237NP and ^16O 232Th data.Based on the observations a new version model of preequilibrium fission is put forward to explain the anomaly.     

Enhanced Collective Magnetic Properties Induced by the Controlled Assembly of Iron Oxide Nanoparticles in Chains

1D assemblies of magnetic nanoparticles are of great potential for designing novel nanostructured materials with enhanced collective magnetic properties. In that challenging context, a new assembly strategy is presented to prepare chains of magnetic nanoparticles that are well‐defined in structure and in spatial arrangement. The 1D assembly of iron oxide nanoparticles onto a substrate is controlled using “click” chemistry under an external magnetic field. Co‐aligned single nanoparticle chains separated by regular distances can be obtained by this strategy. The intrinsic high uniaxial anisotropy results in a strong enhancement of magnetic collective properties in comparison to 2D monolayers or isolated nanoparticles. In contrast to the intensively studied bundle chains of nanoparticles, the finely tuned chain structure reported here allows evidencing a first order intrachain dipolar interaction and a second order interchain magnetic coupling. This study offers new insights into the collective magnetic properties of highly anisotropic particulate assemblies which have been investigated by combining superconducting quantum interference device magnetometry, magnetic force microscopy, and ferromagnetic resonance.     

Ti-V合金hcp结构弹性性质的第一原理研究

为研究V元素对Ti合金弹性模量的影响,采用平面波展开的第一原理赝势法,对固溶状态下hcp结构的Ti-V合金的结构、弹性模量进行研究,结果表明V含量小于5.6 at%时合金呈稳定的hcp结构,且随V含量的增加,合金的体弹模量、剪切模量和杨氏模量单调减小,泊松比单调增大。     

Twisted Crystalline Organic Semiconductor Photodetectors

Optoelectronic properties of anisotropic crystals vary with direction requiring that the orientation of molecular organic semiconductor crystals is controlled in optoelectronic device active layers to achieve optimal performance. Here, a generalizable strategy to introduce periodic variations in the out-of-plane orientations of 5,11-bis(triisopropylsilylethynyl)anthradithiophene (TIPS ADT) crystals is presented. TIPS ADT crystallized from the melt in the presence of 16 wt.% polyethylene (PE) forms banded spherulites of crystalline fibrils that twist in concert about the radial growth direction. These spherulites exhibit band-dependent light absorption, photoluminescence, and Raman scattering depending on the local orientation of crystals. Mueller matrix imaging reveals strong circular extinction (CE), with TIPS ADT banded spherulites exhibiting domains of positive or negative CE signal depending on the crystal twisting sense. Furthermore, orientation-dependent enhancement in charge injection and extraction in films of twisted TIPS ADT crystals compared to films of straight crystals is visualized in local conductive atomic force microscopy maps. This enhancement leads to 3.3- and 6.2-times larger photocurrents and external quantum efficiencies, respectively, in photodetectors comprising twisted crystals than those comprising straight crystals.