突出矿井瓦斯抽放限制影响因素的AHP-熵权法评价模型

为提高煤与瓦斯突出矿井瓦斯抽放效果,建立了3个一级指标、14个二级指标的突出矿井瓦斯抽放限制影响因素评价指标体系,利用AHP和熵权法分别确定指标因子主、客观权重.通过实地调研分析和反馈验证了AHP-熵权法的可行性和正确性,利用加权平均法确定评价模型的综合权重.研究表明:封孔方式、钻孔半径、抽放时间、煤体裂隙发育程度和抽放负压是目前影响煤矿瓦斯抽放效果的主控因素.     

电感耦合等离子体原子发射光谱法测定工业废水中铅、镉、铬和砷

采用电感耦合等离子体原子发射光谱(ICP-AES)法同时测定工业废水中铅、镉、铬和砷。对仪器的工作参数和被测元素的分析谱线进行了优化和选择。方法的检出限依次为0.008,0.002,0.007,0.015 mg.L-1。在质量浓度为0.489 mg.L-1(Pb),0.086 6 mg.L-1(Cd),0.231 mg.L-1(Cr)及0.395 mg.L-1(As)的水平上按试验方法测定8次,作了精密度试验,测得相对标准偏差值依次为1.71%,1.22%,0.95%及1.40%。在两个废水样品的基础上作了加标回收试验,所得结果在95.4%~104.6%之间。     

端视ICP-AES法同时测定玩具涂料中可溶性铅、镉、汞、砷、铬、锑、硒和钡

采用端视电感耦合等离子体原子发射光谱(ICP-AES)法同时测定玩具涂料中可溶性铅、镉、汞、砷、铬、锑、硒和钡.对仪器的工作参数和被测元素的分析谱线进行了优化和选择.铅、镉、汞、砷、铬、锑、硒和钡的检出限分别为0.006、0.0009、0.012、0.023、0.000 8、0.013、0.030和0.0006 mg/L.定量下限分别为0.99、0.15、2.0、3.8、0.14、2.2、5.0和0.10 mg/kg.相对标准偏差为0.76%～2.72%(n=8),加标回收率为96.0%～104.0%.该法适用于玩具涂料中铅、镉、汞、砷、铬、锑、硒和钡的快速测定.     

一种简便的铂坩埚整形方法

铂坩埚是分析中常用的高级器皿。铂较软,长期使用后容易变形,凹陷内易积附杂质,影响溶样及恒重效果,送铂制品厂整形费用较贵,且影响日常检验工作。 本文介绍一种简便实用的铂坩埚整形方法。铂坩埚用焦硫酸钾熔融,洗净内外壁,水煮,擦干。台面上垫一厚橡胶布,坩埚平放在橡胶布上,选择长度不小于     

负吸光值最小二乘法同时测定工业硅中钙和铁

在氨性缓冲溶液中,钙、铁与酸性络蓝K生成的络合物在450～650nm之间存在负吸光值,两者负吸收峰高绝对值均大于正吸收值(以试剂空白为参比)。探讨消色法即负吸光值最小二乘法同时测定钙、铁。所拟方法用于工业硅样品中钙、铁测定,结果满足分析要求。     

尿素与间甲酚共晶法分离间/对甲酚

Urea was dissolved into mixture of m/p-cresol(m/p = 59.1/40.9) upon heating to 80℃. The resulting solution was cooled spontaneously to 40℃, then further to a designated temperature in an even speed with stirring with even dropping of toluene. Co-crystal of urea and m-cresol was thus formed as white precipitate, which was then isolated by filution. Pure m-cresol was obtained by distillation of oil layer that was the upper layer of hydmlyzed decomposition of filtrating cake. Effects of solvent, material ratio, temperature on the yield and the purity were investigated, m-Cresol with purity of 99.0% and yield of 73.9 % is obtained at an optimized condition at urea/(m/p)-cresol = 23g/50ml,final temperature = - 15℃ ,time = 110min, and dropping of 150ml toluene.The existence of co-crystal of urea and m-cresol was verified by IR spectroscopy. The product purity was assayed by GC.     

附加浓度权重的校准线回归方法

至今大多数分析方法都要通过对分析信号校正来计算被测组分含量,因此,分析信号校正是分析中的重要问题.一元线性回归是信号校正的常用方法.1 绝对偏差和相对偏差最小二乘回归设有普通变量Y_i,随机变量X_i,回归方程形式为Y=a bX,用绝对偏差最小二乘法拟合校准线,即求Σ((?)_i-Y_i)~2为最小值时a,b值,由方程组解得 计算简便,绘图直观是绝对偏差最小二乘法拟合校准线的一大优点,故在实际中得到广泛应用.但