Interferometric calibrations and astronomical calibrators

This chapter gives some indications on the selection of suitable astronomical calibrators for interferometric observations. After an introduction to interferometric calibrations, we will focus on the criteria, steps and tools developed by ESO to prepare VLTI observations and to select calibrators. Although the tools described here are focused on VLTI, the problem of astronomical calibrators is the same for the other interferometers and can be approached in the same way.     

试论二氧化硅观测中标样系列的选定对观测质量的影响

本文通过对同一批次的标样系列及水样先后进行两次对比观测实验,指出标样系列的取值范围在一定程度上影响观测质量,尤其对直线首尾两端点的测值影响较大,而测值居中的则影响较小;符合所测水样系列的标样系列则可以使水样取得稳定的测值。并据此指明标样系列取值范围应尽可能遵循的原则。     

Problems in the determination of plastic and liquid limits of remoulded soils using a drop-cone penetrometer

This short communication describes difficulties of sample preparation associated with the determination of plastic and liquid limits using a drop-cone penetrometer. Problems of sample packing, soil moisture distribution and degree of remoulding are identified. These problems are particularly relevant in influencing liquid limit values whilst the effects on plastic limits are less marked. It is concluded that if the need is for the quick determination of liquid and plastic limits for general classification purposes, then the traditional Casagrande and thread methods are adequate. If these limits require to be measured with greater precision using the drop-cone technique, then careful consideration must be given to sample preparation.     

鄂尔多斯盆地北缘地球化学大数据样本优选分析

众所周知,地球化学数据携带有众多地质噪音,这些噪音严重影响地球化学数据信息的客观性与可靠性;对于地球化学大数据融合分析而言,确定样品的有效性及变量优选是滤除地质噪音、建立最优样本集合的必要性工作,因而在地球化学大数据处理分析前需首先进行大样本优选,从而更加客观、真实的揭示地球化学大数据信息及相关地质意义。本文以鄂尔多斯盆地北缘1∶20万地球化学土壤测量数据为例,考虑元素之间的地球化学亲和力与组合匹配关系,建立非线性大样本优选模型。具体做法是基于优选后的样品矩阵,将39个元素变量分解成若干独立因子向量,将最优独立因子向量作为元素组合,其向量各分量作为元素变量的权重,依权重大小进行变量优选;优选后的样本集合可以作为该区地球化学数据分析与信息识别的有效地学信息集合,运用这种集合可以有效开展鄂尔多斯盆地外围铀地球化学分析,并为盆地铀资源预测奠定基础。     

RANSAC估算基础矩阵的不确定性评价

RANSAC是计算机视觉领域内应用最广泛的基础矩阵估算方法,如何实现RANSAC估算基础矩阵的不确定性评价值得探讨。该文在研究RANSAC估算基础矩阵模型的基础上,提出采用基础矩阵的错误率和平均对极距离的标准差作为评价RANSAC估算基础矩阵不确定性的指标,并构建RANSAC估算基础矩阵不确定性评价方法,实现RANSAC估算基础矩阵不确定性评价。     

Impact of sample size on geotechnical probabilistic model identification

This paper aims to investigate the impact of sample size on geotechnical probabilistic model identification. First, the copula approach is presented to model the bivariate distribution of geotechnical parameters. Thereafter, the AIC scores are adopted to identify the best-fit marginal distribution and copula. Second, the variation of AIC scores because of small sample size is investigated using simulated data. Finally, the impact of the variation of AIC scores on identification of the best-fit marginal distribution and copula is examined. The minimum sample sizes for geotechnical data are also suggested to obtain a correct identification of the probabilistic models. The results indicate that the AIC scores estimated from a small sample exhibit large variation. The variation of the AIC scores has a significant impact on probabilistic model identification. The marginal distributions and copulas have a low percentage of correct identification when sample size is small. The percentages of correct identification for the marginal distributions and copulas increase with increasing sample size. The correlation coefficient between geotechnical parameters has a much larger impact on probabilistic model identification than the COV of geotechnical parameters. The suggested minimum sample sizes for geotechnical data are useful for guiding practical geotechnical site investigation.     

苏中腹地湖相沉积土层相关距离的统计分析

相关距离是用随机场理论建模土层剖面的一个非常重要的参数,也是利用随机场理论进行岩土工程可靠性分析的关键所在。基于苏中地区某建筑工程原位静力触探测试数据中的锥尖阻力指标,针对粉质黏土层,利用不同取样间距对相关距离进行了统计计算,分析了取样间距对相关距离计算结果的影响及原因,提出了实际应用中基于尺度匹配原则的取样间距确定方法;随后,基于江苏中部某高速公路工程地质勘察所提供的大量原位静力触探测试数据,结合相关距离计算的平均零跨距法、递推空间法和相关函数法,对该区湖相沉积土层土性参数的竖直向和水平向相关距离进行了系统地统计分析。研究成果不仅提供了土性参数相关距离计算过程中取样间距的确定原则,而且获得了相关距离的区域性代表值,为区域性土性参数随机场模型的建立打下坚实的基础,能对苏中地区岩土工程可靠性分析提供参考。     

食品级氯化钾制备工艺和杂质检测方法的研究进展

食品级氯化钾的制备工艺主要为热溶结晶法,其间通过加入晶种、酸、碱、助滤剂等去除原料中的镁离子、钙离子、硫酸根、有机物等杂质。氯化钾中杂质的检测方法可采用滴定法、电感耦合等离子体光谱法、原子吸收分光光度法、紫外可见分光光度法等。随着食品级氯化钾市场规模的逐渐扩大,行业对产品质量要求也不断提高,其制备工艺技术和杂质检测方法也需不断改进和完善,进一步促进行业有序发展。     

紫外辐照条件下二维填料对聚丙烯耐老化行为的影响

采用水热法合成了二维层状材料——镁镍铁水滑石(MgNiFe-LDH),考察不同水热时间和水热温度对MgNiFe-LDH合成的影响,通过X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、扫描电镜(SEM)和热分析(TG/DTG)等测试方法,对样品的结构、形貌及热性能进行表征。将合成的MgNiFe-LDH添加至聚丙烯(PP)制备MgNiFe-LDH/PP复合材料,通过对材料加速老化测其力学性能,研究了添加MgNiFe-LDH前后材料机械性能变化。结果表明,当Mg~(2+):Ni~(2+):Fe~(3+)=2∶1∶1,水热温度140℃、水热时间24 h时,合成的MgNiFe-LDH为片状,形貌较为规整,颗粒粒径约为2μm。MgNiFe-LDH/PP复合材料经加速老化后,填充MgNiFe-LDH复合材料的抗老化性能优于纯PP,当MgNiFe-LDH的填充量为6 wt%复合材料拉伸强度不变,可明显提高PP的抗老化性能。     

纳米氢氧化镁的制备

以氯化镁和氢氧化钠为原料,添加表面活性剂,直接利用表面活性剂在固/液界面的“双亲性”使其吸附在新生成的氢氧化镁微粒上,制备纳米氢氧化镁。并采用X-射线和透射电镜等对样品进行表征,结果表明样品晶型发育完善,样品为片状、粒径为85 nm、粒度均匀且分散性好的纳米氢氧化镁粉体。