Bandpass filtering effect in tapered asymmetrical twin-core optical fibres

The spectral coupling characteristics in asymmetrical twin-core optical fibres under fusion tapering are investigated experimentally. It is found that appropriate filtering can be achieved by fusion tapering. It is evident that, with suitable choice of tapering length and fibre parameters, it is possible to fabricate economic all-fibre bandpass filtering devices for various applications.<>     

A study of residual stress distribution through the thickness of p+ silicon films [thermal oxidation effects]

The effect of thermal oxidation on the residual stress distribution throughout the thickness of heavily-boron-doped (p⁺ ) silicon films is studied. The deflection of p⁺ silicon cantilever beams due to residual stress variation throughout the film thickness is studied for as-diffused and thermally oxidized films. Cantilevers of as-diffused p⁺ silicon films display a positive curvature (or a negative bending moment), signified by bending up of the beams. Thermal oxidation of the films prior to cantilever fabrication by anisotropic etching modifies the residual stresses in the p⁺ film, specially in the near-surface region (i.e. the top 0.3 to 0.5 μm for the oxidation times used here), and can result in beams with a negative curvature even when the oxide is removed from the p⁺ silicon cantilever surface subsequent to cantilever fabrication     

无接触法测量多晶硅材料的少子扩散长度

用微波光电导谱仪无接触、非破坏性地测量了多晶硅的微波光电导谱,推导了由光电导谱计算多晶硅样品的少子扩散长度和表面复合速度的计算方法,并由此算得了样品的少子扩散长度和表面复合速度。测试区域是一个直径为3mm的圆斑。这是一种简便而又准确的测试方法。这样的方法还适用于GaAs薄片材料少子扩散长度的测量和计算。     

Microring resonator channel dropping filters

Microring resonators side coupled to signal waveguides provide compact, narrow band, and large free spectral range optical channel dropping filters. Higher order filters with improved passband characteristics and larger out-of-band signal rejection are realized through the coupling of multiple rings. The analysis of these devices is approached by the novel method of coupling of modes in time. The response of filters comprised of an arbitrarily large dumber of resonators may be written down by inspection, as a continued fraction. This approach simplifies both the analysis and filter synthesis aspects of these devices     

A semi-empirical representation of antenna diversity gain atcellular and PCS base stations

Predictions of uplink space-diversity gain in the cellular and personal communications systems (PCS) bands (near 850 MHz and 1.9 GHz, respectively), suffer from incomplete modeling of multipath angular spread σ. Using previously published measurements to reduce the gap, we show that σ~[distance]^-1/2 and that diversity gains are about 2 dB higher for PCS than for cellular     

在线近红外光谱分析仪在汽油自动调合系统中的应用

在线近红外光谱分析仪可以实时测定汽油调合组分及成品油的多种物化性质指标如烯烃、芳烃、苯及氧化物含量、辛烷值（RON、MON）、馏程、蒸气压等。文章介绍了用于汽油自动调舍工艺中的在线近红外光谱分析仪的原理、系统组成和特点，以及在国内外的汽油调合优化控制中的实际应用情况。典型的应用实例表明，将该分析仪用于汽油自动调合工艺中，可为炼油厂带来可观的经济效益和社会效益。     

MTBE装置醇烯比测定技术现状与进展

醇烯比是甲基叔丁基醚（MTBE）生产装置的重要控制指标，对MTBE裟置醇烯比的分析技术现状进行了系统综述，包括实验室气相色谱法，在线工业色谱和软测量技术等，详细介绍了这些方法的原理和优缺点。基于以上调研情况和国际在线分析仪表的发展趋势，提出了采用在线近红外光谱方法实时测量醇烯比的技术方案，并给出了实验室模拟在线测量醇烯比的一些近红外试验结果，该方法有望成为解决在线测量醇烯比的理想手段。     

循环伏安法在润滑油检测中的应用

介绍了循环伏安法的产生背景、原理。应用该技术可以快速、方便地对润滑油中抗氧剂、总酸（碱）值进行测定，并且可以对不同厂家润滑油的抗氧剂包进行区别。该技术还可以有效地评价润滑油的使用寿命和设备工作状况。     

成品油管道工艺方案优化设计研究

基于计算期内总费用最小现值建立了干线成品油管道工艺方案优化设计的数学模型,分析了分输方式、分输流量变化及工艺计算参数的选取等问题.考虑到传统数值算法求解多变量混合整数非线性规划问题的局部最优性及对初值敏感性强等缺陷,针对所建立的数学模型的特点,引进了一种较新的全局搜索算法——杂交差分进化方法,并对其进行了局部改进,采取了动态处理约束条件的措施.在泵站可选位置确定的条件下,采用赋权有向图来表示工艺方案优化设计问题.泵站位置候选点对应图的顶点,两顶点间管道的总费用现值对应弧的权值.通过递归调用Dijkstra算法,求解出了前N条最短路径对应的最优和次优方案,并以其作为进一步进行多因素方案比选的候选方案.用实际算例说明了上述方法的有效性.