一种改进的LiDAR点云TIN迭代滤波算法

采用了设定最大内插距离和最大内插角度两个阌值,根据滤波次数动态调整了其值以达到最佳滤波效果,实现并改进了TIN迭代滤波算法。     

Combined Effect of Climatic Variations and Groundwater Movement on Observed Heat Flow

In most practical situations, the upper part of a geological section consists of loose sediments, in which heat transfer cannot be described as a purely conductive process. To investigate such situations a one-dimensional numerical model of terrestrial temperature field formation under the combined influence of vertical groundwater filtration and ground surface temperature changes has been developed. The model allows one to consider the perturbation of heat flow interval values resulting from short- and long-period temperature waves propagating into permeable rocks under conditions of advective heat transfer, caused by vertical groundwater filtration. The results show that temperature profiles and interval heat flow values are sensitive to both the paleoclimatic history and the rate of groundwater filtration. The latter plays the prevailing role in the variations of geothermal field parameters, especially within the uppermost part of the loose sediments in unconfined aquifers. The problem was solved for a permeable layer, underlaid by an impermeable layer. This schematisation of water exchange is the typically accepted for hydrogeological analysis. Even at very low rates of filtration the intensity of this effect is enhanced substantially for long-period variations. In the extreme case (for periods of temperature variations of the order of 100,000 years) at typical rates of filtration within the permeable layer, an almost gradient-free zone can be formed down to depths of a few hundred metres. For the case of upward filtration, on the contrary, the influence of climatic variations on the terrestrial temperature field becomes substantially attenuated.     

中华鲟卵黄脂磷蛋白的分离纯化及性质分析

采用Sephacryl S-300凝胶过滤和DEAE Fast Flow阴离子交换两种层析法分离纯化中华鲟(Acipenser sinensis)卵黄脂磷蛋白(lipovitellin,Lv),对每个峰进行SDS-PAGE电泳及油红O、甲基绿和Schiff试剂特异染色,峰Ⅱ蛋白均呈阳性,表明峰Ⅱ蛋白为中华鲟卵中的一种卵黄脂磷蛋白,SDS-PAGE电泳分析表明其由一种分子质量为43.5 ku的亚基构成。对中华鲟Lv氨基酸组成进行研究,证明其是一种含有相对较多天冬氨酸、谷氨酸、缬氨酸和亮氨酸的蛋白。     

The effect of salinity on clearance rate in the suspension-feeding estuarine gastropod Crepipatella dilatata under natural and controlled conditions

The suspension-feeding gastropod Crepipatella dilatata occurs in estuaries in southern Chile that experience considerable fluctuations in salinity, driven by tidal and atmospheric forces. In the Quempillén estuary salinities as low as 9 psu may occur after severe rainstorms, and persist for several hours. In this study salinity was the major factor influencing the clearance rate of C. dilatata. At salinities below 20 psu, filtration ceased, whereas at high salinities (>22 psu) mean clearance rate was 0.24 l h⁻¹ standard animal⁻¹ (S.D. 0.18) for actively filtering individuals. This was confirmed by laboratory experiments under controlled conditions. Endoscopic observations were consistent with measurements of clearance rate, and showed that at salinity 25–30 psu the rate of transport along the gill filaments of particulate material embedded in mucus was 759 μm s⁻¹ (S.D. 480), but particle transport ceased at and below salinity 20 psu. Complete or partial isolation of the mantle cavity from the environment may be a mechanism to protect soft tissues and/or incubated egg capsules from osmotic stress.     

极限保土状态下的反滤机制试验研究

提出了反滤系统极限保土状态的概念,分别采用4种不同孔径的钢丝编织网进行粉土反滤试验,研究反滤系统的极限保土状态。试验表明,当滤网孔径O和粉土特征粒径d85的比值等于12时,反滤系统才达到极限保土状态。极限保土状态下的反滤系统,在淹没式出流条件下,经往复水流作用26 h后改为单向水流,水力梯度从3.8逐渐增加到9.1,并在9.1的水力梯度下持续渗透453.25 h,反滤系统仍保持稳定,未发生失稳破坏;在非淹没式出流条件下,水力梯度从5.3逐渐增加到12.7期间,反滤系统保持稳定,但在维持12.7的水力梯度下持续渗透261.83 h后,反滤系统发生失稳破坏。对极限保土状态的研究有助于工程设计中更加合理地确定织物滤层孔径上限,减少淤堵。     

高密度低失水泥浆体系在煤田绳索取心钻探中的应用研究

煤田钻探中,经常会遇到比较破碎、易坍塌、易水化膨胀等复杂地层,给钻进造成较大的困难。开发了具有良好的防塌性能、较好的抑制性并具有适当密度的高密度低失水泥浆体系。现场使用证明,该泥浆体系在煤田小口径金刚石绳索取心钻探中能很好维持孔壁稳定、有效抑制泥页岩的水化膨胀,降低孔内事故的发生率。     

河流渗滤系统对地表污水的净化作用综述

河流渗滤系统可充分利用水环境的净化功能,提高污水处理效率,避免地下水遭受污染.河流渗滤对地表污水的净化是一种自然过程,它作为天然的过滤器及生物地球化学反应器,可以除去河水中多种污染物,包括天然有机物、合成有机物、无机物、颗粒物、细菌及病原体等.文章分析了影响河流渗滤系统自净作用的影响因素,包括河流沉积物的组成、河流渗滤系统的结构、季节等.最后提出了今后研究河流渗滤系统的方向.