一种基于Cross—bar空分交换的共享总线型ATM交换单元

本文提出了一种基于Ｃｒｏｓ－ｂａｒ空分交换的共享总线型ＡＴＭ交换单元，—阻塞信元共享总线（ＢＣＳＢ，ｂｌｏｃｋｅｄ－ｃｅｌｓｓｈａｒｅｄ－ｂｕｓ）交换单元，并研究了其中关键电路的实现。ＢＣＳＢ新颖的构思将空分交换和时分交换体制有机的结合在一起。它既有效地降低了普通共享总线交换单元对内部电路加速的要求，又首次在Ｃｒｏｓｓ－ｂａｒ交换单元中不对内部电路进行加速，实现了输出排队策略。理论分析和计算机模拟结果证明，ＢＣＳＢ交换单元具有很好的平均信元时延、吞吐量和信元丢失率性能。     

强激光反射镜基体材料的热畸变特性有限元分析

利用有限元方法数值模拟了单晶硅（Si）、铜（Cu）、钨(W)、氧化铍(BeO)等镜体材料的热畸变特性。结果表明：当入射激光功率为2 kW、镜面反射率为93%、光斑直径为17 mm、激光照射时间为10 s时,四种材料基板的中心最大热变形分别为0.984,3.32,1.55,1.88 μm。相比之下,Si镜的热变形最小,是比较理想的镜体材料;Cu镜的热变形最大;W和BeO两种材料的镜热变形介于Si镜和Cu镜之间,具有较高的强度和硬度,抗破坏能力较强。     

A general finite element model for numerical simulation of structure dynamics

A finite element model used to simulate the dynamics with continuum and discontinuum is presented. This new approach is conducted by constructing the general contact model. The conventional discrete element is treated as a standard finite element with one node in this new method. The one-node element has the same features as other finite elements, such as element stress and strain. Thus, a general finite element model that is consistent with the existed finite element model is set up. This new model is simple in mathematical concept and is straightforward to be combined into the existing standard finite element code. Numerical example demonstrates that this new approach is more effective to perform the dynamic process analysis in which the interactions among a large number of discrete bodies and continuum objects are included.     

龋病易感儿童头发微量元素含量的分析

为进一步了解龋病发病机理,探求儿童龋病发生,发展与预防与微量元素含量的关系,收集３￣５周岁儿童患龋组４０名和正常对照组４０名的头枕部近头皮处发样２ｇ／人,用原子吸收光谱法测定头发中锌,铜,铁,锰,铅的含量,结果表明未见五种微量元素与龋病有显著相关,微量元素含量与患龋易感关系有待于进一步研究。     

The role of surface terminations on the band structure and optical properties of silicon nanonets

The ab initio calculations are carried out to investigate the effect of hydrogen, oxygen and nitrogen terminations on the properties of the band edge and the values of the band-gap, as well as the oscillator strength of the silicon nanonets (SiNNs). The oxygen functional groups are found to effectively preserve the direct band-gap nature of the SiNNs, and even change the luminescence properties of the silicon nanowires (SiNWs) to the direct band-gap transition. The appreciable oscillator strength of the first direct transition is obtained for the oxygen terminated nanostructure. The study on the electronic states indicates that the variation of the band edge caused by the surface terminations is attributed to the change of the state compositions. These surface modifications are thought to be useful for silicon band-gap engineering in the area of optoelectronics.     

关于“产业技术创新战略联盟”——我的认识与理解

文章概述了在PcB中创建“产业技术创新战略联盟”的基本目的、要求和条件。     

过渡元素卤化物标准生成焓的连接性拓扑研究

基于邻接矩阵和成键原子的价环值（Ｖ１）,建立２个新连接性指数（＾０Ｈ,＾１Ｈ）。它们与３３种过渡元素卤化物标准生成焓的直线方程为：－△Θｍ＝－３８．３９＋２２８．０８＾０Ｈ,ｒ＝０．９９０３－△ｆＨΘｍ＝１２７．４５＋３１８．５０＾１Ｈ,ｒ＝０．９８４０与其它指数相比,新指数计算更为准确。结果表明,＾０Ｈ、＾１Ｈ具有良好的结构选择性和性质相关性,可用于预测其它过渡元素卤化物的标准生成焓。     

Fast switching beam steering based on ferroelectric liquid crystal phase shutter and polarisation grating

We report on fast-switching and high-efficient optical beam steering based on a polymerisable liquid crystal polarisation grating (PG) in combination with ferroelectric liquid crystal (FLC) phase shutter. The PG was fabricated in a convenient single-step holographic exposure process using photo-sensitive azo-dye material as alignment layer for liquid crystal (LC) director. A binary electro-optical FLC was employed for circular polarisation selection, which enables the electro-tunable steering of the combined system. The efficiency of 95.7% with 82 μs switching time is obtained for 1064 nm laser. This work provides a versatile candidate for non-mechanical beam steering devices.     

Phase Systems and Post-Column Dithizone Reaction Detection for the Analysis of Organo-Mercurials by HPLC

Abstract

The suitability of HPLC (normal and reversed phase adsorption) with UV or post-column reaction detection for the analysis of organomercurials was investigated systematically. The separation of organomercurials is best carried out on a reversed phase system with a C-8 bonded phase material as the stationary phase and acetonitrile-aqueous sodium bromide mixtures as the mobile phase.

The precision and detection limit of the method and the efficiency of the extraction procedure were established. For the alkylmercury compounds the lowest limit of detection (80ppb) was obtained with the dithizone reaction detection and for the phenylmercury compounds with UV detection (60ppb). A chromatogram of a spiked fish (2ppmHg) and a river water sample (50ppbHg) is shown.     

Pine Needles (Pinus Sylvestris) as a Bioindicator of Sulphur and Heavy Metal Deposition in the Area Around a Pulp and Paper Mill Complex at Kemi,Northern Finland

Abstract

The determination of sulphur and heavy metals in plants is an integral part of many environmental studies. Pine needles (Pinus Sylvestris) have proved to be suitable air quality indicators for pollutants, especially for sulphur. This study was carried out in the vicinity of Kemi, a town situated on the Gulf of Bothnia in northern Finland. An industrial complex comprising two pulp and paper mills is located in the centre of the area. Scots pine (Pinus Sylvestris) needles were collected from 29 sampling sites. The samples were dried, homogenized and digested with nitric acid. The concentrations of the elements S, Fe, Zn, Ca, V, and Pb were determined by ICP-AES. According to our results pine needles (Pinus sylvestris) appear to be an ideal bioindicator and sampling material for identifying and assessing atmospheric sulphur pollution derived from pulp and paper mills and can complement the information provided by plant mapping studies around pulp and paper mills.