Chapter 11 Simulation studies of efficiency,returns to scale and misspecification with nonlinear functions in DEA

Using statistically designed experiments, 12,500 observations are generated from a 4-pieced Cobb-Douglas function exhibiting increasing and decreasing returns to scale in its different pieces. Performances of DEA and frontier regressions represented by COLS (Corrected Ordinary Least Squares) are compared at sample sizes ofn=50, 100, 150 and 200. Statistical consistency is exhibited, with performances improving as sample sizes increase. Both DEA and COLS generally give good results at all sample sizes. In evaluating efficiency, DEA generally shows superior performance, with BCC models being best (except at corner points), followed by the CCR model and then by COLS, with log-linear regressions performing better than their translog counterparts at almost all sample sizes. Because of the need to consider locally varying behavior, only the CCR and translog models are used for returns to scale, with CCR being the better performer. An additional set of 7,500 observations were generated under conditions that made it possible to compare efficiency evaluations in the presence of collinearity and with model misspecification in the form of added and omitted variables. Results were similar to the larger experiment: the BCC model is the best performer. However, COLS exhibited surprisingly good performances — which suggests that COLS may have previously unidentified robustness properties — while the CCR model is the poorest performer when one of the variables used to generate the observations is omitted.     

An Investigation on the Effect of Arsenic Poisoning on Humans,Agriculture, and Fisheries

The purpose of this investigation is to try and understand the degree of arsenic poisoning in the waste water from agricultural chemical factories which release effluents into the waterways in their vicinity. The method of determination is to use the water samples, soil, fish, clams, shell-fish, etc. found in the areas along the canals and aqueducts and those which lie upstream, midstream, and downstream and also the hair samples of people living in the contiguous areas, to check for the levels of arsenic in them by emission spectroscopy. From the analysis during a one year investigation, we find that the level of As in the water creatures of Chungkang Stream and Lu-Er-Men Stream is much higher than in the other water areas of Taiwan such as along beaches and the other rivers; the levels in the hair of the people who live nearby these water courses have a certain degree of correspondence with their eating habits and the quantity of food eaten; however, even those people who eat relatively little have almost 3% As, beyond the 2 mg/kg limit allowed for human beings. We are fully aware of the high level of food contamination on Taiwan, and this fact has been taken into consideration. The effect of As contamination in the soil on agricultural produce does not seem to have any apparent relationship. By the way, the influence of the monthly average rainfall on As contamination in the soil is not obvious.     

锡铅银等低熔点合金中氧的测定方法研究

研究了锡铅银等低熔点合金中杂质氧的测定方法。针对这些金属高温下易挥发、分解的特点，选择适宜的加热温度，使用铜和石墨粉作为浴料，选择标准坩埚，以电流920A加热进行试验。对氧的质量分数为0.017%的试样，分析精密度为5.9%，加标回收率为91％－108％。     

Continuous flow and flow injection stripping voltammetric determination of silver(I), mercury(II), and bismuth(III) at a bulk modified graphite tube electrode

The epoxy-impregnated graphite tube electrode bulk modified with 2-mercaptobenzoxazole, employed in a wall-jet configuration, was found to be useful for the continuous flow and flow injection stripping voltammetric determinations of Ag^I, Hg^II and Bi^III. For continuous flow, detection limits for Ag^I, Hg^II and Bi^III were 1.8 × 10⁻¹⁰ M, 1.9 × 10⁻⁹ M and 9.5 × 10⁻⁹ M, respectively (10 min accumulation, S/N = 3). Precisions for 5.00 × 10⁻⁹ M Ag^I, 1.00 × 10⁻⁸ M Hg^II and 1.00 × 10⁻⁷ M Bi^III were 10.5%, 5.77 % and 7.90% (relative standard deviations, n = 6), respectively. In the case of flow injection stripping, with a 500 μL injection loop, detection limits of 0.59 ng, 2.0 ng and 120 ng were obtained for Ag^I, Hg^II and Bi^III, respectively (S/N = 3). Selected metal ions, inorganic and organic substances were investigated for interferences. The electrode was tested with a certified sample and then applied to the determinations of the metal ions in a urine and a sea-water sample.     

微量元素与妊娠及围产医学的关系

为探讨微量元素与妊娠及围产医学的关系，取４９例正常孕产妇和５１例异常孕产妇的头发进行微量元素检测．结果表明，异常孕产妇中妊娠高血压综合征组发锌均值（１０４±１７．５４）×１０－６明显低于正常组（１６８±２２．１２）×１０－６，而发铜均值（１３．３±０．７８）×１０－６明显高于正常组（１１．３±０．９４）×１０－６，不明原因流产组发锌（１１５±１０．３２）×１０－６，发铜（９．０３±１．０３）×１０－６两项均值明显低于正常组，羊膜早破组仅发铜均值（７．５９±１．９７）×１０－６低于正常组；畸胎组则锌、铜、铁、钙均值都低于正常组．经统计学处理均有显著性差异（Ｐ＜０．０５或产＜０．０１）     

Dislocation Analysis for Large-sized Sapphire Single Crystal Grown by SAPMAC Method

In this paper,large-sized sapphire (230×210 mm,27.5 kg) was grown by SAPMAC method (sapphire growth technique with micro-pulling and shoulder-expanding at the cooled center). Dislocation peculiarity in large sapphire boule (0001) basal plane was investigated by chemical etching,scanning electron microscopy and X-ray topography method. The triangular dislocation etch pit measured is 7.6×101～8.0×102 cm-2,in which relative high-density dislocations were generated at both initial and final stages of crystal growth. The analysis of single-crystal X-ray topography shows that there are no apparent sub-grain boundaries; the dislocation lines are isolated and straight. Finally,the origins of low-density dislocation in sapphire crystal are discussed by numerical analysis method.     

三梅片成份分析研究

医药品冰片有天然品与合成品之分,天然品有:由龙脑香科(Dipterocarpaceae)植物龙脑香(Dryobalanops aromatica G aertn,f.)制得的结晶,称龙脑香冰片;白菊科(Compositae)植物艾纳香(Blumea balsamifera DC.)所得的结晶,名艾片。艾片因其晶形似梅花片,又有梅片之称,根据梅花片状又分为大梅片,二梅片,三梅片,天然品化学成分为龙脑(Borneol,Ⅰ),合成冰片(又名合成龙脑),除含龙脑外尚含较大量的异龙脑(ISO-borneol,Ⅱ)     

The effect of capillary column diameter on the performance of thermal conductivity detectors

The concentration sensitivity of a thermal conductivity detector (TCD) depends, among other factors, on the amount of sample mixture in the detector's sensing cell. Since the cell volume has to be appropriately matched with column diameter, it makes the concentration sensitivity of a TCD dependent on column diameter and, therefore, on the speed of gas chromatography. Through reduction of column diameter, higher speed tends to lead to a reduction in the concentration sensitivity of the cell. The factor which the most directly affects the concentration sensitivity of a TCD cell is the heat power conducted through the cell. The higher the power, the greater the sensitivity. The limit of detection of a TCD depends on the concentration-sensitivity of its cell and on the level of statistical errors in the measurement. The errors increase with increasing analysis speed. As the column diameter is reduced, the errors cause additional worsening (on top of the decrease in concentration sensitivity) of the detection limit, dynamic range, and other performance characteristics of the TCD.     

神经网络法用于多元混酸同时测定

利用多层神经网络误差反向传播算法处理酸碱电位滴定数据，求得出多元混合酸各组分的浓度，优化了神经网络的结构和参数，测定了三组分有机酸混合样品，结果良好，平均相对偏差ＲＳＤ≤４％。