高温水解-离子色谱法同时测定再生锌原料中氟和氯

采用自制的高温水解装置处理样品,结合离子色谱法测定了再生锌原料中氟、氯的含量。试样在1 000℃高温下通入氧气与水蒸汽进行水解反应,以NaHCO_3(6.0mmol/L)与Na_2CO_3(2.4mmol/L)的混合溶液作为淋洗液,经SH-AG-1保护柱及SH-AC-3分离柱分离,测得F-在0~10 mg/L、Cl-在0~50mg/L范围内浓度与峰面积呈线性关系,相关系数分别为r=0.999 8和r=0.999 9,检出限分别为0.020mg/L与0.033 mg/L。分析再生锌原料中氟、氯的加标回收率分别在95.70%~102.5%和96.72%~101.3%,相对标准偏差(n=11)分别在2.1%~6.6%和2.0%~5.8%。方法对再生锌原料中氟(0.010%~1.00%)和氯(0.050%~5.00%)测定,结果满意。     

Multi-window invisible cloaks

This paper reports that a general method of designing invisible cloaks is using variant constitutive material parameters to realize the space transformation. A hollow region can be hidden after this transformation. It was recently shown (Ma H, Qu S B, Xu Z and Wang J F 2009 \wx{Appl. Phys. Lett.}{94} 103501) that when the original point moves to the boundary of a cloak, the cloak can be designed to be open. Based on this theory, we propose multi-window invisible cloaks which can conceal a group of objects. Full wave simulations for invisible cloaks with regular and irregular shapes verified this method.     

具有极化选择特性的超材料频率选择表面的设计

基于超材料结构的设计理论,通过长金属线周期阵列和具有Lorentz谐振形式等效介电常数的金属短线的组合可频率选通特性.由不同周期排布和结构尺寸的长金属线和金属短线组合而成的频率选择表面具有不同频段的选通特性.文章提出了双层及单面两种具有极化选择特性的频率选择表面,两种结构均可实现对特定频段TE及TM波选通.具有极化选择特性的超材料频率选择表面的设计为极化滤波器以及极化波产生器的设计提供了借鉴. 关键词： 频率选择表面 超材料 极化选择     

5,5,8aβ-三甲基-6β-羟基-反八氢-1-萘酮的合成及在Phenylspirodrimane类混源萜天然产物骨架构建中的应用

以(E)-5,9-二甲基-4,8-癸二烯酸乙酯为原料,发展了一种合成5,5,8aβ-三甲基-6β-羟基-反八氢-1-萘酮(1)的新方法,并将其成功应用于phenylspirodrimane类混源萜天然产物骨架的构建.对合成过程中所涉及的关键反应如区域选择性环氧化和Cp₂TiCl催化的自由基串联环合反应进行了优化.所合成化合物的结构均通过核磁共振波谱(NMR)和高分辨质谱(HRMS)进行了表征和确认.     

预混段长度对旋流燃烧器气固两相流动特性的影响

本文利用三维PDA测量了预混段减小的斗山巴布科克旋流燃烧器气、固两相流动特性,并与设计的斗山巴布科克旋流燃烧器PDA测量结果对比,得出:预混段减小的燃烧器在x/d=0.1,0.3截面存在回流区,并将设计燃烧器回流区的位置由一二次风之间推迟至外二次风区域;预混段减后的燃烧器与设计燃烧器相比,轴向,径向,切向平均速度在二次风区域产生的峰值远离燃烧器轴线;在x/d=0.1～0.5截面,预混段减小的燃烧器与设计燃烧器相比一次风区域颗粒体积流量的峰值变大,二次风区域颗粒体积流量的峰值变小,在燃烧器出口附近回流区内的颗粒体积流量明显降低。     

Pattern imprinting in deep sub-micron static random access memories induced by total dose irradiation

Pattern imprinting in deep sub-micron static random access memories(SRAMs) during total dose irradiation is investigated in detail. As the dose accumulates, the data pattern of memory cells loading during irradiation is gradually imprinted on their background data pattern. We build a relationship between the memory cell’s static noise margin(SNM) and the background data, and study the influence of irradiation on the probability density function of ?SNM, which is the difference between two data sides’ SNMs, to discuss the reason for pattern imprinting. Finally, we demonstrate that, for micron and deep sub-micron devices, the mechanism of pattern imprinting is the bias-dependent threshold shift of the transistor, but for a deep sub-micron device the shift results from charge trapping in the shallow trench isolation(STI) oxide rather than from the gate oxide of the micron-device.     

基于电阻膜的宽频带超材料吸波体的设计

基于电阻膜设计了一种宽频带、极化不敏感和宽入射角的超材料吸波体.该吸波体的结构单元由六边形环状电阻膜结构、介质基板和金属背板组成.仿真得到的反射率和吸收率表明,该吸波体在7.0-27.5 GHz之间对入射电磁波具有宽频带的强吸收,证实了电路谐振相对于电磁谐振易于实现宽带吸波.仿真得到的不同极化角和不同入射角下超材料吸波体的吸收率表明,该吸波体具有极化不敏感和宽入射角特性.仿真得到的基板和电阻膜对超材料吸波体吸收率的影响表明,电阻膜结构和金属背板之间形成的电容以及电阻膜结构的电阻都存在一个最佳值,此时电路谐 关键词： 电阻膜 电路谐振 宽频带 超材料吸波体     

无单位元环A=sZ_(st)的同调不变量Tor_m~(Z,Z)的计算

设A=sZst,A~=A Z,本文作者给出了A~-模Z的自由预解,并以此为基础计算了T orAm(Z,Z).     

考虑熵层效应的扫掠激波/湍流边界层干扰特性研究

为了探究熵层对扫掠激波/湍流边界层干扰特性的影响规律,采用仿真方法对尖鳍/钝板物理模型进行研究。结果表明：扫掠激波上游的熵层厚度随着平板前缘钝化半径的增大而增加,同时边界层厚度也随着熵层厚度的增加而增加。熵层的引入并不改变扫掠激波/湍流边界层干扰固有的准锥形相似特性,也不会改变拟锥原点(virtual conical origin, VCO)的位置,仅会改变干扰形成的上游影响线和分离线的角度。扫掠激波/湍流边界层干扰形成的锥形主旋涡和角涡的尺度随着熵层厚度的增加而增大。上游熵层的引入增大了下游扫掠激波/湍流边界层干扰区的总压损失,但扫掠激波/湍流边界层干扰自身造成的相对总压损失并不受上游熵层的影响。     

Nonsingularity in two-dimensional cylindrical invisible cloaks

The method of designing electromagnetic invisible cloaks is usually based on the form-invariance of Maxwell's equations in coordinate transformation. The exterior boundary of a cylindrical invisible cloak is unchanged and the interior boundary is extended from that of a point to that of a cylindrical region in coordination transformation. This transformation process makes perfect cloaks, but it causes singularity in the constitutive material parameters of cloaks. This singularity makes the cloaks impossible to realize in practice. In order to remove this singularity, this paper sets a small cylindrical region replacing a point in the space transformation. The cylindrical region is so small that it does not affect the invisibility effects, but it can remove the singularity for material parameters. Full wave simulations based on the finite element method were used to verify the designed cloaks.