Electron energy loss spectroscopy of nano-scale CrAlYN/CrN-CrAlY(O)N/Cr(O)N multilayer coatings deposited by unbalanced magnetron sputtering

The nano-scale chemical distribution and microstructure of a nitride based wear and oxidation resistant coating prepared by unbalanced magnetron sputtering was investigated. The coating consisted of multilayers of CrAlYN/CrN with a partially oxidised CrAlY(O)N/Cr(O)N oxy-nitride surface layer. The multilayer period of both the nitride and oxy-nitride layers was 3.8 ± 0.2 nm. Nano-scale chemical analysis and imaging was performed using sub-nanometer resolution electron energy loss spectroscopic profiling in a spherical aberration corrected scanning transmission electron microscope. Experimentally determined fine edge structure in electron energy loss spectra were in good agreement with theoretically determined spectra, calculated using electron density functional theory. This analysis indicated the CrN layers to be near stoichiometric with a relative Cr/N ratio of 1.05 ± 0.1 while for the CrAlYN layers the best match between the direct chemical analysis and the simulated edges was (Cr_0.5Al_0.5)N. A diffuse interface, ∼ 1 nm wide was observed between the CrAlYN and CrN layers. For the outermost oxy-nitride layer, the chromium to nitrogen ratio remains approximately constant though out the layer, while the aluminium decreases as a function of increasing oxygen content.     

Urinary mercury in people living near point sources of mercury emissions

As part of the European Mercury Emissions from Chlor Alkali Plants (EMECAP) project, we tested the hypothesis that contamination of ambient air with mercury around chlor alkali plants using mercury cells would increase the internal dose of mercury in people living close to the plants. Mercury in urine (U-Hg) was determined in 225 individuals living near a Swedish or an Italian chlor alkali plant, and in 256 age- and sex-matched individuals from two reference areas. Other factors possibly affecting mercury exposure were examined. Emissions and concentrations of total gaseous mercury (TGM) around the plants were measured and modeled. No increase in U-Hg could be demonstrated in the populations living close to the plants. This was the case also when the comparison was restricted to subjects with no dental amalgam and low fish consumption. The emissions of mercury to air doubled the background level, but contributed only about 2 ng/m(3) to long-term averages in the residential areas. The median U-Hg levels in subjects with dental amalgam were 1.2 microg/g creatinine (micro/gC) in Italy and 0.6 microg/gC in Sweden. In individuals without dental amalgam, the medians were 0.9 microg/gC and 0.2 microg/gC, respectively. The number of amalgam fillings, as well as chewing, fish consumption, and female sex were associated with higher U-Hg. The difference between the countries is probably due to higher fish consumption in Italy, demethylated methyl mercury (MeHg) being partly excreted in urine. Post hoc power calculations showed that if the background mercury exposure is low it may be possible to demonstrate an increase in U-Hg of as little as about 10 ng/m(3) as a contribution to ambient mercury from a point source.     

基于FIB-SEM制备尖晶石微米颗粒的球差校正透射电镜样品

针对尖晶石微米颗粒材料,利用聚焦离子束扫描电镜双束系统(FIB-SEM),在传统透射电镜样品制备方法的基础上进行技术性改进,成功制备了高质量的球差校正透射电镜样品.并利用球差校正透射电镜成功观察到了尖晶石颗粒的截面原子结构,为更深入地研究尖晶石材料的结构和性能奠定了基础.     

Cook结构补偿镜的球面折反型望远系统

基于Cook结构补偿镜提出了一种球面折反型望远系统。该系统将传统折反结构中的非球面球面化并用基于Cook结构的补偿镜代替传统的前置大口径补偿镜。将该镜置于次镜之后,其直径减小了很多,支撑结构也变得简单易行,整个系统容易制造。系统光学性能如下:全视场为0.5°,相对孔径可以做到F/7,遮拦比为0.42,MTF衍射极限为0.45@50pl,设计、加工和装校后总的MTF可以做到0.40@50pl,非常接近衍射极限水平。     

金属离子极谱峰电位的精确拟合解析

利用计算机技术对实验测定的铋离子示差脉冲极谱数据进行了如下处理:1)用修正的Gaossian方程拟合实验测定的极谱曲线,得到精确至±0.05mV的极谱峰电位;2)用极谱数据计算机分析系统CFC-Ⅱ计算因Bi(OH)~(2+)络合物的形成而造成的极谱峰电位移动值;3)对校正过的金属离子极谱峰电位值进行多项式曲线拟合,得到整个pH区间铋离子(Bi~(3+))的示差极谱峰电位值。数据处理与分析结果表明:当溶液的pH<2.5时,可以利用关系式E_p(mV)=-0.252[pH]~4+5.8748[pH]~3-37.673[pH]~2+94.303[pH]+19.1计算科离子的极谱峰电位(相对于银/氯化银参比电极);当溶液的pH值在2.5以上时,铋离子的极谱峰电位为101.13mV     

末敏弹四自由度质点弹道计算方法

根据末敏弹的运动特点，分别建立了末敏弹抛撒段弹道，减速减旋段弹道和减速稳定段及稳态扫描弹道的四自由度弹道方程，并导出了各段弹道的起始弹道诸元。为末敏弹系统的弹道计算提供了一种可行的方法。     

小波神经网络在配电网故障定位中的应用

提出一种适用于配电网架空线路的单相接地故障定位新方法,该方法以暂态零序电流的小波能量、有功功率、无功功率作为数据融合的特征量,再结合紧致型小波神经网络（WNN）来进行故障定位,并针对小波神经网络存在收敛速度缓慢且容易陷入局部极小的问题,给出一种参数修正改进的算法,通过在权值调整式中增加动量项来选择学习步长,且以新方法初始化各个权值以提高网络学习效率。大量的Matlab仿真结果表明：此方法具有很好的单相接地故障定位性能,实验准确率基本可以达到100%,可应用于配电网故障定位。     

风光蓄互补系统的技术研究

针对微电网中风光蓄互补系统展开研究,重点研究了风光蓄互补发电系统的拓扑结构,以太阳能池板作为作为主要发电设备,风力发电作为补充性发电单元,通过针对太阳能发电的特性研究,综合考虑系统的发电时效性确定了系统的直流修正参数.其次,利用蓄电池作为系统的重要储能设备,保证了系统在离网单独运行时,弥补风光发电的不确定性.通过研究蓄电池的特性,充放电特点及规律提出了针对微电网风光系统蓄电池容量的计算方法,并进行了仿真实验,实验结论证明了所提出的计算方法的正确性与有效性.     

丝网印刷柔性薄膜天线力电性能表征

为降低天线结构重量、提高天线与结构一体化效率,制备了一种可卷曲且易与结构共形的柔性薄膜天线.基于天线基本理论和丝网印刷工艺技术设计并制备了薄膜微带准八木天线.将薄膜天线辐射层看作颗粒增强复合材料,利用Mori-Tanaka复合材料细观力学方法预测其有效弹性模量,与拉伸叠加法结果吻合良好.基于内聚力模型,利用ABAQUS有限元分析软件模拟了薄膜天线基体/辐射层在90°剥离条件下的界面剥离过程,揭示了天线基体与辐射层之间界面破坏机理,得到薄膜基体/辐射层的界面剥离强度,通过90°剥离实验验证了内聚力模型的有效性.有限元得到的剥离强度为64N/m,与实测值误差为8.11%,吻合良好.最后,仿真和实验研究了柔性薄膜天线的反射系数和辐射方向图性能,仿真得到的薄膜天线谐振频率为3.02GHz,与实验谐振频率误差为2.37%,且在谐振频率处阻抗匹配良好.结果表明:本文设计制备的柔性薄膜天线具有良好的力学和电磁性能,在航空航天轻量化结构中有广泛的应用前景.     

Realization of Wurtzite GaSb Using InAs Nanowire Templates

The crystal structure of a material has a large impact on the electronic and material properties such as band alignment, bandgap energy, and surface energies. Au‐seeded III–V nanowires are promising structures for exploring these effects, since for most III–V materials they readily grow in either wurtzite or zinc blende crystal structure. In III–Sb nanowires however, wurtzite crystal structure growth has proven difficult. Therefore, other methods must be developed to achieve wurtzite antimonides. For GaSb, theoretical predictions of the band structure diverge significantly, but the absence of wurtzite GaSb material has prevented any experimental verification of the properties. Having access to this material is a critical step toward clearing the uncertainty in the electronic properties, improving the theoretical band structure models and potentially opening doors toward application of this material. This work demonstrates the use of InAs wurtzite nanowires as templates for realizing GaSb wurtzite shell layers with varying thicknesses. The properties of the axial and radial heterointerfaces are studied at the atomic scale by means of aberration‐corrected scanning transmission electron microscopy, revealing their sharpness and structural quality. The transport characterizations point toward a positive offset in the valence bandedge of wurtzite compared to zinc blende.