圆柱齿轮冷锻成形技术探讨

探讨了几种圆柱齿轮冷锻成形技术 ,对圆柱齿轮冷锻特性进行了分析 ,并运用系统的观点对提高冷锻圆柱齿轮的轮齿精度做了探讨     

TOTAL SOLUTES LOADS AND GEOCHEMICAL YIELDS IN THE SASKATCHEWAN RIVER BASIN1

ABSTRACT: River solute loads have seldom been measured in very large, complex drainage basins, nor have the methods of calculating loads been critically examined. For sites in the Saskatchewan River Basin, Canada, rating curves were poor predictors of solute loads because correlations between discharge and total solutes concentration were weak (R² < 0.05 in most cases) and suffered from hysteresis. In contrast, the interval method produced reliable estimates in all seasons and sites tested, and was little affected by sampling schedule. The limit of precision (SE) for estimates of mean annual or seasonal solute load was 10–15 percent of the mean (5 percent in very small basins), reached with 10 years or more of data. Two-thirds or more of total annual solute load was transported during the open-water season, but the proportion carried during winter increased from 8 percent to 34 percent from the upstream to the downstream end of the basin, due to reservoirs retaining and mixing water. Annual loads of total solutes varied from 6.2 × 10⁴ tonnes in foothills tributaries to almost 4.0 × 10⁶ tonnes in the Saskatchewan River near the mouth. But, on an areal basis, the mountain and foothills region was the dominant solute source, producing 43–97 tonnes/km²/yr, compared with only 3–22 tonnes/km²/yr for prairie rivers. This difference is a consequence of greater rainfall and, hence, more rapid erosion in the mountains.     

郑州环境空气中粉尘浓度的统计分析及预测

对郑州市2005年1月—2009年12月份的可吸入颗粒物(PM10)指数数据进行统计分析,并利用Matlab软件建立了利用气象要素预测PM10的BP神经网络模型。结果表明:2005—2009年郑州市PM10指数的年均值和空气质量超标天数逐步下降,且趋于稳定;年内各月的PM10指数浓度差异很大,冬季PM10指数显著高于夏季,8月最低,而12月最高;采暖期PM10指数显著高于非采暖期,而节假日对于PM10指数的影响不明显;通过平均风速、平均气温、平均气压和平均相对湿度预测PM10浓度可以达到最高精度86.85%。     

土壤中环境散落放射性核素含量测定方法探讨

利用环境中散落的放射性核素示踪研究土壤侵蚀是近几十年来应用比较广泛的方法之一。介绍了^137Cs测量的原理、过程和仪器对核素计数效率的计算,影响核素测量分析精度的主要因素是样品质量、计数时间和样品的核素比活度的大小,并分析了这3个因素各自对分析精度的影响程度,对尽量减少测量中的人为误差、提高结果的精度所应注意的问题进行了讨论。     

SOME FACTORS AFFECTING THE DETERMINATION OF PARTICULATE CARBON AND NITROGEN IN RIVER WATER1

The effect of storing samples prior to determination of particulate nitrogen and carbon concentrations were investigated. Freezing of water samples between collection and analysis has a substantial effect on the results obtained. Storage of samples at 5°C also affects the results, although the changes which occurred were generally less than for frozen samples. When the particulates were collected onto a filter immediately after sample collection and stored in that form until analysis only small changes in the results were observed. This suggests that samples for the determination of particulate nitrogen and carbon concentrations should be filtered immediately upon sample collection and the analysis performed as soon as possible.     

流动注射在线消解测定水中总氮的实验研究

采用流动注射在线消解测定水中总氮,分析速度快、检出限低、精密度和准确度较高。总氮质量浓度在200～2000μg/L与峰面积有良好的线性关系（r=0．9997）,方法检出限为0．0056mg／L。对水源水、地表水和废水样品的加标回收率测定中,均满足《生活饮用水卫生规范》对方法的要求。在水质检出中具有较好的应用价值。     

利用小样本数据预处理技术提高效能指标精度

提出了运用熵值判别法和线性均方估计法来处理小样本数据的方法.熵值判别法是根据熵的上界对应最大的不确定度,利用所得数据的熵信息量判别数据是否含有粗大误差;线性均方估计消除粗大误差是一种采用软化的方法处理粗大误差.经过多次试验,结果表明这两种方法在处理小样本采样数据时能够有效地提高数据精度.     

数字水准仪DiNi11/12原理及应用中应注意的问题

本文介绍了数字水准仪的原理、特点,着重分析了对台站跨断层观测精度影响较大的几个因素,并结合台站工作实际提出了减弱这些影响的措施,实测结果表明:采取这些措施可以有效地提高测量精度.     

高精度磁测在圈定铬渣堆积范围中的试验研究

界定铬渣堆积范围对于场地环境的维护和管理具有现实意义。工业生产过程中燃烧产生尾渣的磁化率是土层的几十倍,为高精度磁测在铬渣污染场地中的调查提供了前提条件和物理基础。文章采用高精度磁测对青海海北某一铬渣堆积场地进行调查,根据异常曲线的特征和定性拟合解释剖面,判定为铬渣填埋体为三度体,可近视看成为球体,球体的直径为5.8 ...     

密封微波消解法测定总氮的研究

利用微波密封消解代替国家标准方法测定总氮过程中高压蒸气消解过程,不仅节约了消解时间,碱性过硫酸钾消解彻底,而且节约了试剂,操作简单,准确度和精确度均达到或超过国家标准方法;本实验同时对操作步骤进行了调整和改进。