汽油烃类族组成测试方法对比

介绍了使用荧光指示剂吸附色谱法、多维气相色谱法的测定影响因素和近红外光谱快速法的分析特点以及三种方法在汽油族组成测定中的应用，并就三种方法对同一试样的测定结果进行了对比，找出各种测定方法容易产生误差的原因及分析对策。     

氨氮监测中样品蒸馏预处理对结果的影响分析

氨氮监测采用预蒸馏处理后，比色测定结果明显偏低。在样品预蒸馏处理过程中，硼酸作为吸收液，使显色时溶液pH值偏低，导致显色不充分是其主要影响因素。通过采取增加显色剂加入量的方法，解决了显色pH值偏低的问题，得到满意的测定结果。     

Relationships between urbanization and the oak resource of the Minneapolis/St. Paul Metropolitan area from 1991 to 1998

Urbanization was associated with loss and transformation of the oak forest in the Twin Cities (Minneapolis and St. Paul) metropolitan area (TCMA) over a recent 7-year interval. Between 1991 and 1998, urbanization increased based on several indicators: population density, area of developed land, and area of impervious surface—total impervious area and area within three classes of increasing degree of imperviousness (protected, affected, and degraded). We quantified relationships between changes in urbanization and changes in several parameters describing the oak forest at the scale of ecological subsection. Increased total and affected impervious area were strongly correlated with decreased area of oak forest when changes of the urbanization indicators and oak were expressed as percentages of the subsection area. Relationships were reversed when changes were expressed as percentages of the 1991 values. Increased population density was strongly correlated with increased loss in numbers and increased isolation of oak patches, but weakly correlated with loss of oak forest area. This is the first study to quantify relationships between changes in urbanization and changes in a specific forest cover type. Our results demonstrate complexities of urbanization impacts on a metropolitan forest resource, and highlight the importance of selected variables, spatial and temporal scales, and expressions of change when quantifying these relationships.     

Bifurcation points and bifurcated branches by an asymptotic numerical method and Padé approximants

The aim of this work is to develop a reliable and fast algorithm to compute bifurcation points and bifurcated branches. It is based upon the asymptotic numerical method (ANM) and Padé approximants. The bifurcation point is detected by analysing the poles of Padé approximants or by evaluating, along the computed solution branch, a bifurcation indicator well adapted to ANM. Several examples are presented to assess the effectiveness of the proposed method, that emanate from buckling problems of thin elastic shells. Especially problems involving large rotations are discussed. Copyright © 2004 John Wiley & Sons, Ltd.     

Field observations on the occurrence of new indicators of disinfection efficiency

This paper summarizes studies on the presence of acid-fast and yeast organisms in wastewater and water treatment plants and in surface water. These organisms were found to satisfy three of Bonde's criteria for indicator organisms: presence whenever pathogens are likely to be present; resistance at least equal to that of pathogens; and lack of regrowth in the post-treatment environment. This, plus prior data, indicates that these organisms are at least as acceptable as indicators of disinfection efficiency than the coliform group.     

单小区模型的掉话率分析

掉话率是无线通信网络中最重要的关键性能指标(KPI)之一,本文分析了中国移动在讨论网络性能评估方法时提出的3个不同的掉话率计算公式,通过建立一个单小区的模型,使用一些合理的假设和分析,从理论上确定了一个最为准确的计算公式.     

测量输入光窗台阶指标的指示表的选择

阐述了对近贴聚焦型微通道板像增强管中输入光窗台阶高度和平整度指标进行测量时，所用指示仪表的选择依据，并详细分析了指示表在检定过程中的误差来源，进一步计算出其合成标准不确定度和扩展不确定度，从而选定可用于测试的指标表。     

机械式有杆泵抽油井示功图的识别

介绍了一种用计算机精确、快速识别机械式示功图的方法。将绘制的示功图通过扫描仪输入计算机,通过对示功图进行二值、细化、矢量化等处理,将示功图的二值点阵信息转换为矢量信息,为后续示功图特征提取创造有利条件,有利于提高抽油井故障的诊断正确率。     

Automated fluorimetry in quality control of pasteurized and ultra-high temperature-treated starch soup

Automated monitoring of the microbiological quality of heat-processed foods by the resazurin reduction test was applied to microtitration plate incubator-fluorimeter technology. The appearance and disappearance of the fluorescing peak of resorufin was monitored on microtitration trays. Pasteurized or ultra-high temperature-treated starch-based soup was used as the model food system. Bacillus subtilis spores (ultra-high temperature treatment) and vegetative cells of Enterococcus faecalis (pasteurization) were inoculated into the soup before the heat treatment at levels which resulted in some survival. The timing of appearance of maximum fluorescence correlated with the number of bacteria in pre-incubated samples. Automated resazurin-reduction fluorimetry was compared with conventional plating, turbidometry and microcolony count by the direct epifluorescent filter technique. The results of the resazurin test correlated well with those of all the other methods tested. Fluorimetry had the advantage that the results could be read within 1–5h and the reproducibility was superior to the other methods.     

主战坦克进气系统随车无损检测

简要地介绍了主战坦克进气系统的重要性及无损检测的必要性,在分析总结台架试验过程和国内外主战坦克进气系统随车无损检查的基础上,提出了今后无损检查的改进方向,利用光电技术及时对质量浓度和颗粒尺寸分布报警的检测系统。