基于USB接口的电能量测试系统

为提升测量精度、方便数据传输管理,设计并实现了以S3C4480处理器作为控制核心,CS5460作为计量器件,通过USB接口与上位机实现数据通讯的新型电能量测试系统;重点讨论了USB接口程序的结构与实现.实践证明系统具有广泛的适应范围.     

旋转长线圈法测量加速器磁铁程序设计

;为完成美国PEPII低能环四极磁铁的测量任务,我们利用慢速旋转长线圈的测量方法,使测量重复精度达到万分之二;旋转长线圈由主线圈和反低线圈组成,利用主线圈测量主极矩信号,利用主线圈和反线圈串联反接所组成的双线圈测量高次谐波,其目的是将主极矩信号(即四极矩)信号抵消掉,从而可以采用较大的放大倍数,提高了测量系统的灵敏度,使高次谐波的测量精度大大提高;介绍基于V isual C++的慢速旋转长线圈测量法测量加速器多极磁铁的程序设计方法,并结合对美国PEPII低能环四极铁的测量,给出相应的数据处理方法和测量结果;程序编写过程中,还给出了数据采集和图形界面的设计思想,以供参考。     

结晶器液压振动自动控制系统

采用伺服控制技术动态调整结晶器液压振动系统的振幅和频率,实现液压非正弦振动,取得最佳的负滑脱时间和保护渣流动效果,降低漏钢事故,改善铸坯质量。     

Stability and performance analysis of switched linear systems subject to time delays and actuator saturation

This paper is devoted to the stability and the performance for the switched linear systems with time delays and actuator saturation. Problems to be considered include the reachable set under a class of bounded energy disturbances and time delays. This treatment yields two forms of differential inclusions, a polytopic differential inclusion (PDI) and a norm-bounded differential inclusion (NDI) that contain the original system. Using the PDI and the NDI describing actuator saturation systems, sufficient conditions for the output feedback control laws are derived to stabilise the systems. The estimation of the attraction domain is to ensure that the state remains inside the level set of a certain Lyapunov function where the PDI and NDI are valid. The sufficient conditions for stability and performances are derived as linear matrix inequalities. A example based on jitterbug tools is used to illustrate the effectiveness of the proposed approach.     

垂直干旱指数在高寒农区春旱监测中的应用研究

青海省东部农业区“十年九旱”,“春旱年年有”,对农业生产的影响非常严重,但该地区至今缺乏有效的春季干旱遥感监测方法。使用环境减灾卫星CCD数据提取青海省东部农业区农业气象观测站的垂直干旱指数(PDI),拟合其与不同深度土壤水分的关系模型,各模型的无偏相关系数均在0.7以上;其中PDI与0~20 cm土壤相对湿度关系模型(y=-489.00x+188.78)的拟合效果最好(无偏相关系数为0.7985)。该模型反演的湟源农业气象观测站固定观测地段的土壤水分时间变化序列与人工测量值的时间变化序列,在趋势变化上较为一致。2013年西宁农区的春季干旱监测中,该模型监测结果显示:发生干旱的地区主要出现在大通河谷地和湟水谷地,湟源农区的土壤旱情在整个西宁农区的土壤旱情发展中最为严重,监测结果与实际旱情分布地区一致。     

共表达蛋白二硫键异构酶对IFNβ-HSA融合蛋白在毕赤酵母中表达的影响

目的探讨共表达蛋白二硫键异构酶(PDI)对干扰素β与人血清白蛋白(IFNβ-HSA)融合蛋白在毕赤酵母中表达的影响。方法根据GenBank公布的毕赤酵母PDI序列设计引物,利用PCR方法从毕赤酵母基因组中扩增目的基因片段,插入表达载体pPICZαA,并整合入融合蛋白(IFNβ-HSA)基因工程菌中,筛选共表达PDI的重组酵母菌,甲醇诱导表达,SDS-PAGE鉴定表达产物,ELISA法检测IFNβ-HSA的表达量。结果经PCR鉴定,重组表达质粒pPICZαA-PDI已转入毕赤酵母KM71/pPIC9K-IFNβ-HSA中。经SDS-PAGE分析,PDI在菌体内大量表达,原始菌株和共表达菌株均明显表达融合蛋白IFNβ-HSA,共表达PDI菌株表达量提高了60%,ELISA法测定达(22.49±3.52)mg/L。结论共表达PDI能促进外源蛋白的分泌表达,为进一步研究在毕赤酵母中过量表达分子伴侣对其分泌外源蛋白的影响奠定了基础。     

Segmented copolymers with monodisperse crystallizable hard segments: Novel semi-crystalline materials

Segmented block copolymers with short monodisperse crystallizable hard segments have interesting structures and properties. In the melt, such short monodisperse segments are miscible with the matrix segments. Moreover, upon cooling, they crystallize fast, demonstrating a very high crystallinity, and only a small crystallization window is needed. The melting temperature of the short segments is high, provided that they can H-bond and/or contain aromatic groups. The melting temperature was found to decrease with increasing matrix segment concentration, due to the solvent effect of the matrix segments. At concentrations of crystallizable segment of 4-35 wt%, good dimensional and solvent stabilities were obtained.The monodisperse segments crystallized into nano-ribbons with uniform thickness and high aspect ratio, and these dispersed nano-ribbon crystallites constituted physical crosslinks, while acting also as reinforcing fillers. At concentrations of the monodisperse segments below 20 wt% no spherulitic ordering took place, and the semi-crystalline polymers were transparent. The monodisperse crystallizable segments can be used in combination with matrix segments of either low or high glass transition temperature, and may even contain (bio)functional units.     

Design and synthesis of novel fluorescence sensing perylene diimides based on photoinduced electron transfer

Two novel tetraester- and PAMAM-branched perylene diimides were synthesized and configured as “fluorophore-spacer-receptor” systems based on photoinduced electron transfer. Due to their long alkylester and alkylamine terminal groups the examined compounds were well soluble in organic solvents. Photophysical characteristics of the dyes were investigated in DMF and water/DMF (1:1, v/v) solution. The ability of the synthesized perylene diimides to detect cations was evaluated by the changes in their fluorescence intensity in the presence of metal ions (Zn²⁺, Co²⁺, Cu²⁺, Fe³⁺, Pb²⁺, Hg²⁺, Ag⁺ and Ni²⁺) and protons. The dyes under study displayed “off-on” switching in its fluorescence as a function of pH, which is attributed to disallowing photoinduced electron transfer from the receptor moiety to the fluorophore. PAMAM-branched dye displayed a good pH sensor activity (FE = 6.4), however the pH sensing ability of tetraester was substantially higher (FE = 184). In the presence of Cu²⁺ and Pb²⁺ ions tetraester quenched its fluorescence intensity (FQ = 22 and 12 respectively), while PAMAM-branched dye enhanced its fluorescence intensity with pronounced selectivity to Cu²⁺ and Fe³⁺ (FE = 3.2 and 4.9, respectively). The results obtained indicate the potential of the novel compounds as fluorescent detectors for metal ions with pronounced selectivity towards Cu²⁺, Pb²⁺ and Fe³⁺ ions and highly efficient “off-on” pH switches, especially a tetraester-branched perylene diimide.     

A golden-template self-generating method for patterned wafer inspection

This paper presents a novel golden-template self-generating technique for detecting possible defects in periodic two-dimensional wafer images. A golden template of the patterned wafer image under inspection can be obtained from the wafer image itself and no other prior knowledge is needed. It is a bridge between the existing self-reference methods and image-to-image reference methods. Spectral estimation is used in the first step to derive the periods of repeating patterns in both di r ections. Then a building block representing the structure of the patterns is extracted using interpolation to obtain sub-pixel resolution. After that, a new defect-free golden template is built based on the extracted building block. Finally, a pixel-to-pixel comparison is all we need to find possible defects. A comparison between the results of the proposed method and those of the previously published methods is presented. Received: 19 May 1999 / Accepted: 20 May 2000     

Modifications of carbon for polymer composites and nanocomposites

The various forms of carbon used in composite preparation include mainly carbon-black, carbon nanotubes and nanofibers, graphite and fullerenes. This review presents a detailed literature survey on the various modifications of the carbon nanostructures for nanocomposite preparation focusing upon the works published in the last decade. The modifications of each form of carbon are considered, with a compilation of structure-property relationships of carbon-based polymer nanocomposites. Modifications in both bulk and surface modifications have been reviewed, with comparison of their mechanical, thermal, electrical and barrier properties. A synopsis of the applications of these advanced materials is presented, pointing out gaps to motivate potential research in this field.