A genetic algorithm approach to determine stratum boundaries and sample sizes of each stratum in stratified sampling

Stratified sampling is a methodology in which a heterogeneous population is partitioned into homogeneous subgroups called strata. The focus is on solving the combined problem of sample allocation and stratum boundary determination with the genetic algorithm (GA). Assuming that the number of strata and the total sample size are arbitrarily predetermined, stratum boundaries are determined using an objective function of minimum variance of the estimator; with sample size allocated through equal, proportional, Neyman, and GA allocation methods. Some numerical examples are given and the performance of GA is compared with the geometric and the cumulative root frequency methods.     

The skin permeation mechanism of ketotifen: evaluation of permeation pathways and barrier components in the stratum corneum

To evaluate the pathways and barrier components in the stratum corneum (SC) for the permeation of ketotifen, the effect of delipidization on the permeation and partition was examined under several donor pHs. Assuming that ionized ketotifen (KTH+) and un-ionized ketotifen (KT) contribute independently in both permeation and partition, the intrinsic permeability coefficients and SC/water partition coefficients of both species were estimated. Delipidization enlarged the permeability of KTH+ 100 times. This suggested that the lipid phase functions as the barrier against KTH+. KT has an intrinsic permeability 100 times larger than that of KTH+. Delipidization did not result in a significant change in permeability of KT. This suggested that the permeability of KT through the lipid phase is comparable to that through the aqueous phase in delipidized SC; that is, the lipid phase functions as a highly permeable pathway for KT. On the other hand, the permeability coefficient of KTthrough delipidized SC was 1/34 of that through the pure aqueous layer, which had a thickness equivalent to SC. Since this suggests that the permeability of KT through the proteinaceous phase is much lower than that through the aqueous phase, the proteinaceous phase can be assumed to function as a barrier against the permeation of KT. From these results, it is concluded that the predominant permeation pathway for KT is through the lipid phase. The SC/water partition coefficient of KT was cut in half by delipidization, but the value was still more than 100. These results show that the proteinaceous phase functions not only as the barrier, but also as the depot for KT. The knowledge obtained here will be useful for formulation design and for the selection of enhancers in a transdermal therapeutic system of ketotifen.     

爆破地震波在地层介质中产生的能量集中效应

论述了爆破地震在地层介质中传播的规律，分析了地质地层条件造成爆破能量集中对建(构)筑物产生的危害，探讨不同岩石性质的爆破震动效应，可为矿区建(构)筑物的位置选择及防震提供参考。     

Research into the inversion of the induced polarization relaxation time spectrum based on the uniform amplitude sampling method

The induced polarization relaxation time spectrum (RTS) reflects the distribution of rock pore size, which is a key factor in estimating the oil or water storage capacity of strata. However, as the data acquisition and transmission abilities of well logging instruments are much limited due to the underground environment, it is necessary to explore suitable sampling methods which can be used to obtain an accurate RST with less sampling data. This paper presents a uniform amplitude sampling method (UASM), and compares it with the conventional uniform time sampling method (UTSM) and logarithm time sampling method (LTSM) in terms of the adaptability to different strata, RTS inversion accuracy, and stratum vertical resolution. Numerical simulation results show that the UASM can obtain high inversion accuracy of RTS with different kinds of pore size distribution formation, with high dynamic ranges of pore size, and with a small number of sampling points. The UASM, being able to adapt to the attenuation speed of polarization curve automatically, thus has the highest vertical resolution. The inversion results of rock samples also show that the UASM is superior to the UTSM and LTSM.     

Corneobiology and corneotherapy--a final chapter

The text obtained for this review from Professor Albert Kligman was drawn posthumously from a variety of notes that he had been planning to use to write a review on corneobiology and corneotherapy. It was a review that he had dearly hoped to complete--his final 'magnum opus' with reflections on the subject.     

温度对P110钢在饱含CO_2/H_2S水介质中腐蚀行为影响

利用高温高压釜失重实验、电化学阻抗谱、Tafel曲线以及扫描电镜等技术,研究了温度对P110钢在饱含CO_2和H_2S气体的吉林油田采出水中的腐蚀行为影响。结果表明,随着温度的升高,P110钢的腐蚀速率首先增大;当温度高于50℃后,腐蚀速率又呈现下降的趋势。这主要是由于低温下所成腐蚀膜的致密性较差,当温度高于50℃后腐蚀膜由明显的晶态FeCO_3组成,且温度越高,腐蚀膜的晶态特征越明显、晶粒越细,膜对基体的腐蚀保护作用越强。     

砂土层中长距离曲线顶管施工技术探讨

鉴于砂土地层中超长距离曲线顶管施工技术在国内外少有研究,本文重点探讨了砂土层中长距离曲线顶管施工中有待解决的几个技术优化的问题。     

基于三棱柱体元结构的GIS地层仿真模型

在Delaunay离散点三角剖分算法,自适应三角格网划分算法和散乱数据曲面插值算法的基础上,提出一种新GIS地层仿真模型,描述该模型的对象存储结构,着重于如何获得足够的数据去仿真整个模型,以及对它进行切割并求其截面.     

北京地铁富水砂层中盾构区间联络通道水平冻结施工技术

北京地铁七号线富水砂层盾构区间联络通道利用冻结法加固土体顺利完成施工,本文详细介绍了冻结法设计、施工以及信息化监测技术,为北京地铁联络通道水平冻结施工提供了参考依据。本工程的成功经验可供其他相似工程参考。     

高应变动力试桩对摩擦型桩检测的研究分析

高应变动力试桩是检测基桩承载力是否能够满足设计要求的重要手段,并在基桩检测领域得到广泛应用。但在使用曲线拟合法计算承载力时,由于影响分析结果的因素很多,比如信号曲线的判断;岩土阻力的分布;检测人员的相关经验等,造成检测结果准确度下降。根据高应变检测试验相关经验,通过基桩动测仪进行分析,研究总结出摩擦型桩在各个土层状态下的曲线特征,进行类比分析,以及在曲线拟合时,相关参数确定的定性定量方法。