温变化对“U”形薄壁渡槽表面应力的影响分析

为了解气温变化对“U”形薄壁渡槽结构应力的影响程度及规律,在南水北调中线一期干线工程湍河渡槽的设计中,采用1〖DK（〗∶〖DK）〗1 物理模型试验与有限元数学模型计算相结合的方法,对结构的温度应力进行了研究。结果表明：当日变化温度为10℃时,渡槽表面的环向应力变化幅值约为0.8 MPa,纵向应力变化幅值约为1.0 MPa;渡槽在施工期的设计温度荷载可取3℃~4℃,若考虑温度骤降等极端天气,则要根据骤降值增加线性温差值。分析成果可为类似薄壁结构工程设计提供参考。      

面向机器自动识别的方位词“中”的用法规则研究

构建面向机器的现代汉语方位词知识库(方位词用法机器词典、方位词用法规则库),对于现代汉语方位词用法的自动识别研究具有重要的意义。致力于面向机器的方位词"中"的用法自动识别研究,以《人民日报》2000年1月-6月的语料作为实验数据,通过对其原始规则的自动识别结果的分析,调整和改进了面向机器识别的方位词"中"的规则描述,把方位词"中"的用法识别准确率由12.88%提高到86.35%,使现代汉语方位词用法规则库得到了进一步完善。     

基于Matlab GUI的数字滤波器设计及其应用

基于数字信号处理原理,在分析数字滤波器设计理论和Matlab编程技术及其GUI图形用户界面设计的基础上,开发了具有交互式特点的数字滤波器软件,界面操作简单方便,可以根据需要选择滤波器类型,输入相关参数,然后选择相应的功能按钮,就可以得到滤波器的特性参数,并进行滤波器的性能分析,打破了以往滤波器设计过程中大量繁琐的数值计算问题,为数字滤波器的设计和应用提供了一个有效的辅助工具。     

Atropine and exercise-induced bronchoconstriction

Six asthmatic children were studied to determine whether supplemental, parenteral atropine would increase the effects of bronchodilation and protection against exercise-induced bronchoconstriction after maximal effects had been achieved by inhalation. First, we determined the amount of inhaled atropine sulfate that would give maximal bronchodilation for each patient at rest. This quantity of atropine was designated as "A." Then all subjects exercised for five sessions with the following pre-exercise treatments in a random order: (a) inhaled distilled water plus intramuscular (IM) saline solution; (b) inhaled A dose of atropine plus IM saline solution; (c) inhaled distilled water plus 0.35 mg IM atropine; (d) inhaled A dose of atropine plus 0.35 mg IM atropine; and (e) inhaled double the A dose plus IM saline solution. The results showed that the combination of inhaled and IM atropine had the greatest bronchodilation effect and the greatest protection against exercise-induced bronchoconstriction. Atropine inhalation alone (A dose) or IM injection (0.35 mg) was not as effective in bronchodilation or in alleviation of exercise-induced bronchoconstriction. Doubling the dose of inhalation (2A) did not increase the effects of the A dose. These results support the hypothesis that inhaled atropine does not reach all the airways where cholinergic receptors are present.     

Feasibility study of the application of voltage contrast to printed circuit board

Voltage contrast (VC) has been a powerful tool for the failure analysis of integrated circuits and multichip module. As the packing density of printed circuit board (PCB) is increasing, conventional failure analysis methods to detect open or short circuit in PCBs are no longer adequate, and voltage contrast method could be a method for this purpose. However, unlike the cases of integrated circuits and multichip module, there are many areas in PCB that will produce serious charging effect when examine under the scanning electron microscope. One of the areas is the presence of solder mask on PCB.This work examines the feasibility of using voltage contrast for PCB failure analysis. Specially designed PCB is used for experimentation, and it is found that positive bias on one track and zero bias on another copper track provide a better image contrast as compared to negative and zero biases on the tracks. Also, the variation of the image contrast with different spacing between inter copper tracks has studied. It is found that the variation depends on the presence of solder mask and its location. The variation can be very different for negative bias case as compared to the positive bias case.Finite element analysis is also performed to explain the experimental observations. All the observations can be well explained by the charging effect of the solder masks. The charging effect of solder mask is indeed very significant in affecting the image contrast, and it could reduce the contrast to almost zero in some cases.     

山西移动NGN建设探讨

首先着重分析了山西移动本地NGN的需求。阐述了山西移动NGN建设需要考虑的因素．最后就山西移动NGN的网络建设策略提出了具体的建议。     

基于WinCC的污水处理厂监控系统设计与实现

本文结合实际的工程项目,介绍了在污水处理厂中利用Siemens公司的Profibus-DP现场总线技术和WinCC组态软件设计实现的一个监控系统。     

基于GIS的道路事故黑点聚类应用研究

由于地理信息系统中数据的多样性和空间复杂性,在GIS数据空间挖掘时原有的挖掘算法会遇到一些新问题。本文针对城市道路网中交通事故黑点发掘问题,对基于密度的DBSCAN算法进行改进,使改进后的算法能够确保聚类仅在连通空间内进行。最后以某市交通事故数据为例对该方法进行验证,实验结果表明此方法是有效的。     

现代电炉炼钢技术发展趋势

综述国内外电炉炼钢技术发展趋势。就国内外电弧炉技术现状度发展趋势进行了讨论，总结了目前电弧炉发展的短期目标、长期目标。     

混合炸药造型粉的超临界流体反溶剂过程制备

将超临界流体反溶剂（Supercritical FluidAnti-solvent，SAS）过程用于炸药表面包覆．采用氟橡胶F2602为包覆材料．乙酸乙酯为共溶剂,与炸药形成悬浮液：超临界CO2为反溶剂,研究了体系温度、压力和进气速率对炸药包覆效果的影响．经过对包覆后样品的性能测定和SEM分析．结果表明：体系温度是影响包覆效果的最关键的工艺参数，压力和进气速率也有一定影响．通过合理调节以上工艺参数可以获得较佳的包覆效果.