Optimization Analysis of Single-layer Reticulated Dome

A structural optimization algorithm is performed for single-layer Kiewit reticulated dome by means of ANASYS. In the process of optimum design, the overall weight is taken as objective function; the stress constraints and stability constraints etc are considered. Meanwhile, the geometrical non-linearity is taken into account. Then the overall stability analysis for the optimized single-layer reticulated dome is operated. The results show that the optimization design is reliable.     

Stability and Biological Activity of Cyfluthrin Isomers

A GC-MS method capable of completely separating the four pairs of diastereoisomers of cyfluthrin is presented and the method used to show that isomerisation of the cyfluthrin enantiomers occurs in methanol. This methanol-induced isomerisation could also be demonstrated by bioassays using water fleas. The biological activities of the various cyfluthrin isomers contained in the commercial products cyfluthrin and beta-cyfluthrin were assayed using several strains of lepidopteran larvae including Plutella xylostella, Heliothis virescens and Spodoptera frugiperda. With the susceptible strains, the efficiencies of the isomers mixtures of cyfluthrin and beta-cyfluthrin were shown to obey the rules of additivity. However, in tests with a resistant strain of P. xylostella originating from Thailand, the ‘inactive’ isomer III acted synergistically with the active isomer IV. Resistance factors in strains of H. virescens and P. xylostella were found to be higher with cis than with trans isomers. This probably contributes to the superior action of cyfluthrin and beta-cyfluthrin against various pests of agricultural importance since the commercial products contain a high content of trans isomers (‘high trans pyrethroids’).     

Effect of temperature,organic amendment rate and moisture content on the degradation of 1,3‐dichloropropene in soil

1,3‐Dichloropropene (1,3‐D), which consists of two isomers, (Z)‐ and (E)‐1,3‐D, is considered to be a viable alternative to methyl bromide, but atmospheric emission of 1,3‐D is often associated with deterioration of air quality. To minimize environmental impacts of 1,3‐D, emission control strategies are in need of investigation. One approach to reduce 1,3‐D emissions is to accelerate its degradation by incorporating organic amendments into the soil surface. In this study, we investigated the ability of four organic amendments to enhance the rate of degradation of (Z)‐ and (E)‐1,3‐D in a sandy loam soil. Degradation of (Z)‐ and (E)‐1,3‐D was well described by first‐order kinetics, and rates of degradation for the two isomers were similar. Composted steer manure (SM) was the most reactive of the organic amendments tested. The half‐life of both the (Z)‐ and (E)‐isomers in unamended soil at 20 °C was 6.3 days; those in 5% SM‐amended soil were 1.8 and 1.9 days, respectively. At 40 °C, the half‐life of both isomers in 5% SM‐amended soil was 0.5 day. Activation energy values for amended soil at 2, 5 and 10% SM were 56.5, 53.4 and 64.5 kJ mol^?1, respectively. At 20 °C, the contribution of degradation from biological mechanisms was largest in soil amended with SM, but chemical mechanisms still accounted for more than 58% of the (Z)‐ and (E)‐1,3‐D degradation. The effect of temperature and amendment rate upon degradation should be considered when describing the fate and transport of 1,3‐D isomers in soil. Use of organic soil amendments appears to be a promising method to enhance fumigant degradation and reduce volatile emissions. Published in 2001 for SCI by John Wiley & Sons, Ltd     

分层正交各向异性板壳非线性有限元分析

采用三维退化等参中厚壳元和分层模型，建立了分析弹塑性和几何非线性各向异性板壳的有限单元法，为克服退化壳元出现剪切和薄膜自锁问题，采用９节点Ｈｅｔｅｒｏｓｉｓ单元并采用选择积分方法，文末算例表明所编程序的可靠性和通用性。     

提高植物叶片面积测量精度的方法

介绍了用CCD（Charge Coupled Device) 提高植物叶片面积测量精度的方法，分析了采用不同的图像获取设备时影响测量精度的各种因素。讨论了使用数码相机时消除线性几何畸变影响的方法，使利用数码相机实现非破坏性测量真正走向了实用化。     

烯唑醇的顺反立体异构体分析方法研究

通过气相色谱和高效液相色谱法研究分析了烯唑醇的顺/反异构体分离方法.正相和反相HPLC的条件如下不锈钢柱200 mm×5 mm(i.d.),填料YWG-Si 10 μm,流动相正己烷-异丙醇为95+5(V/V)或者用正己烷-无水乙醚-无水甲醇89+9+2(V/V),流速2.0 mL·min-1,检测波长254 nm;不锈钢柱200 mm×5 mm(i.d.),填料YWG-C1810 μm,流动相甲醇-水-乙酸为70+30+0.35(V/V),流速1.0 mL·min-1.气相色谱的条件熔融石英毛细管柱10m×0.53 mm×1.0 μm膜厚,用聚乙二醇-20000涂渍,柱温160℃,进样口和检测器温度250℃,载气H216 mL·min-1.在上述气相色谱的条件下,烯唑醇顺/反异构体能达到部分分离.     

抗几何攻击的数字图像版权保护算法

为了在保证图像质量的前提下实施图像的版权保护,提出了一种基于Krawtchouk矩和标识信息的零水印算法.该方法利用从图像中提取的特征信息来构造水印,从而达到版权保护的目的.主要步骤为,首先计算原始图像的Krawtchouk低阶矩不变量来构建水印信息,接着将水印信息和密钥信息在第三方登记注册并获得标识信息,最后通过标识信息确认版权所有者.水印提取过程简单,只需计算所得图像的几个低阶Krawtchouk矩不变量.文中给出了实验结果,并与传统几何矩不变量的算法进行了比较. 结果表明,该方法对旋转、缩放、剪切、组合攻击、平移和去掉行等几何攻击以及滤波、JPEG压缩等攻击具有更高的稳健性.     

离心机主轴形位公差选择标注及检测

介绍了碟式离心机的结构,分析了其传递动力和转动的零件—主轴的功用,选择标注了主轴的形位公差值并提出了单件生产中各项形位误差的现场检测方法。     

水库微囊藻毒素3种异构体的年变化过程研究

应用高效液相色谱,对华北地区某水库5个采样点水体中微囊藻毒素（MC-LR、RR和YR）3种异构体进行了为期1a的监测,研究3种异构体随时间的变化规律及相互关系。结果表明,水体中3种异构体（-LR、YR和RR）含量分别为0.941±1.338、0.365±0.647和（2.893±5.387）μg·L-1;3种异构体出现时间不一样,LR异构体出现时间最早,在4月下旬即可检测到,而RR和YR异构体则需到5月中旬才能检测到;3种异构体峰值出现时间也不一致,LR和YR异构体峰值出现在8—9月,而RR异构体出现时间较晚,到10—11月才达到全年最高值;LR和RR异构体的含量比较高,是主要毒素,5—11月,其比值由2.20降到0.04,这与水体中的N/P比值有关,它随N/P比值的减少而减少。