比估计的两个常用的方差估计量的小样本比较

本文利用冯士雍和邹国华［１］或Ｓｕｎｄｂｅｒｇ［２］提出的比较方差估计量的新准则对比估计的两个常用的方差估计量进行了小样本比较．这是Ｃｏｃｈｒａｎ［３］提出的一个公开问题．我们的结果在一定的意义下回答了该问题．     

比波谱导数和零交点法测定混合物含量

Ｐｂ２＋、Ｃｄ２＋、Ｈｇ２＋在ｐＨ６．５的硼砂－盐酸缓冲溶液中,与四（４－三甲铵基苯基）卟啉（ＴＡＰＰ）生成稳定配合物,采用ＫＩ和低聚度聚乙烯醇（ＰＶＡ）增敏、增溶,Ｐｂ２＋、Ｃｄ２＋、Ｈｇ２＋的εｍａｘ分别为ε４８１．５（４．９×１０５Ｌ·ｍｏｌ－１·ｃｍ－１）、ε４５７（７．９×１０５Ｌ·ｍｏｌ－１·ｃｍ－１）、ε４４４．５（８．１×１０４Ｌ·ｍｏｌ－１·ｃｍ－１）。在三吸收峰相互重叠的情形下,利用比波谱导数和零交点法,同时测定它们的含量,Ｐｂ２＋、Ｃｄ２＋、Ｈｇ２＋的检出限分别达４μｇ／Ｌ、２μｇ／Ｌ和１０μｇ／Ｌ。方法计算简便、快速。     

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本文在产品寿命服从双参数指数分布的无替换定数截尾寿命试验场合下,提出了两独立产品平均寿命比率的两个估计量,并研究了这两个比率估计量的渐近正态性和置信区间. 然后通过数据模拟,进一步验证了所提出比率估计量的有效性.     

A novel spectrophotometric method for the simultaneous kinetic analysis of ternary mixtures by mean centering of ratio kinetic profiles

In this paper, a novel and very simple method was developed for the simultaneous spectrophotometric determination of ternary mixtures, without prior separation steps. The method is based on the mean centering of ratio kinetic profiles. The mathematical explanation of the procedure is illustrated. In order to investigate the applicability of the proposed method, it was applied to the simultaneous spectrophotometric determination of hydrazine, phenylhydrazine and acetylhydrazine based on their condensation reactions with p-(dimethylamino)benzaldehyde (DAB) and p-nitrobenzaldehyde (NB) in micellar sodium dodecyl sulfate (SDS) media as a typical ternary mixture. The analytical characteristics of the method such as accuracy, precision, relative standard deviation (R.S.D.) and relative standard error (R.S.E.) were calculated.     

Mean centering of ratio kinetic profiles for the simultaneous kinetic determination of binary mixtures in electroanalytical methods

In this work, the applicability of mean centering (MC) of ratio kinetic profiles method to the kinetic voltammetry data is verified. For this purpose, a procedure is described for the determination of Sb(III) and Sb(V) by adsorptive linear sweep voltammetry using pyrogallol (py) as a complexing agent. The method is based on the differences between the rate of complexation of pyrogallol with Sb(V) and Sb(III) at pH 1.2. The results show that the mean centering of ratio kinetic profiles method is suitable for the speciation of antimony. Sb(III) and Sb(V) can be determined in the ranges of 3.0-120.0 and 10.0-240.0 ng mL⁻¹, respectively. Moreover, the solution is analyzed for any possible effects of foreign ions. The obtained results show that the method of MC in combination to electroanalytical techniques is a powerful method with high sensitivity and selectivity. The procedure is successfully applied to the speciation of antimony in pharmaceutical preparations.     

Application of A New Spectrophotometric Method Manipulating Ratio Spectra for Determination of Bambuterol Hydrochloride in the Presence of Its Degradation Product Terbutaline

A simple,specific,accurate and precise spectrophotometric stability indicating method is developed for determination of bambuterol hydrochloride(BH)in the presence of its degradation product terbutaline(TERB)and in pharmaceutical formulations.A newly developed spectrophotometric method called ratio difference method by measuring the difference in amplitudes between 245 and 260nm of ratio spectra.The calibration curves are linear over the concentration range of 0.1~1mg·mL-1 for BH and 0.1~0.7mg·mL-1 for TERB with mean percentage recovery of 100.56±0.751 and 99.88±1.183,respectively.The selectivity of the proposed method is checked using laboratory prepared mixtures.The proposed method has been successfully applied to the analysis of BH in pharmaceutical dosage forms without interference from other dosage form additives and the results have been statistically compared with pharmacopeial method.     

水库设计的三维可视化研究

为了提高水库设计的自动化水平,实现模型的三维可视化,本文研究了三维地形的建模方法及其在水库设计中的应用。采用了地性特征点和地性线参与三维建模的方法,提高了数字高程模型DEM的地形逼真度。在此基础上通过一种综合了水平线和覆盖消隐算法的合成消隐算法实现了彻底的消隐以及图像的快速生成。通过三维水库模型,不仅可以得到水库的容量、库水的淹没边界和淹没面积,而且还可以生成地形剖面图。如果地形剖面图与地质图、水文图、构造图等进行叠加,可以形成综合剖面图。文章最后采用三维可视化方法模拟了某水库的部分设计工作,结果表明,通过水库的三维地形模型可以简单直观的完成坝址的选择、水库容量以及蓄水的水位线的确定等方面的工作。     

基于地应力场加卸载的地下洞室稳定模型试验研究

加卸载响应比理论是研究非线性系统稳定的一种重要方法。本文分析了该理论的本质含义,研究了该理论在洞室稳定分析中存在的问题,提出了基于应力边界值即地应力场增减实现加卸载的方法。文中以某矿山巷道稳定研究作为工程背景,建立了相似材料平面应变模型。通过对顶部边界应力进行逐级加卸载,主要研究了拱顶竖向压力、拱顶沉降和声发射的响应特征。结果表明,当应力不太大时,拱顶竖向压力和拱顶沉降的加卸载响应比值接近1;当围岩接近破坏时,比值出现突然的增加,并伴随较大的波动。声发射能量和事件数虽未出现类似特征,但总体来说,随着荷载的增加,声发射呈现增加的趋势。     

Suitability of rubber track as traction device for power tillers

Suitability of using rubber tracks as traction device in power tillers replacing pneumatic tires was studied using an experimental setup consisting of a track test rig for mounting a 0.80 m × 0.1 m rubber track and a loading device for applying different drawbar pulls. Tests were conducted in the soil bin filled with lateritic sandy clay loam soil at an average soil water content of 9% dry basis by varying the cone index from 300 to 1000 kPa. Data on torque, pull and Travel Reduction Ratio (TRR) were acquired using sensors and data acquisition system for evaluating its performance. Maximum tractive efficiency of the track was found to be in the range of 77–83% corresponding to a TRR of 0.12–0.045. The Net Traction Ratio (NTR) at maximum tractive efficiency was found to be between 0.49 and 0.36.Using non-linear regression technique, a model for Gross Traction Ratio (GTR) was developed and it could predict the actual values with a maximum variation of 6% as compared to an average variation of 50% with Grisso’s model. Based on this model, tractive efficiency design curves were plotted to achieve optimum tractive performance of track for any given soil condition.