Slope instability in Nicaragua triggered by Hurricane Mitch: distribution of shallow mass movements

The heavy rains associated with Hurricane Mitch triggered off a number of slope instability processes in several Central American countries. Different instability processes have been acknowledged for the various mountainous regions of Nicaragua. An enormous movement of the Casita Volcano slopes resulted in numerous deaths and some deep movements have been reactivated. On the other hand, numerous shallow mass movements and debris flows have given rise to great material loss throughout a large part of Nicaraguan mountains.Mapping the shallow mass movements in an area of Central Nicaragua clearly reveals the close ties between their distribution and some geomorphological factors. A susceptibility model has been constructed for shallow mass movements based on field mapping of the shallow mass movement distribution, the geomorphological map as well as the digital slope and accumulated flow models. A logistical regression analysis was applied. The study area has been categorized into three classes of relative landslide susceptibility. Given that phenomena of this nature occur much more frequently in the high susceptibility class, 94% of the shallow mass movements that have been used to test the model are in the high and medium susceptibility classes . The geological and geomorphological conditions of the study area are representative of a large sector of the central Nicaraguan region. Consequently, the methodology followed in this paper is deemed to constitute a useful tool, both regarding the design of new infrastructures, and as a guide to the urban development of the area.     

Statistical analysis in classification of bituminous coal

Hundreds of samples and 17 variables collected from coalfields of major coal-bearing strata over China except for Tibet and Taiwan, were used in this study. The dry, ash-free basis volatile matter (V ^r) and caking index (G _(RI)) were chosen by means of correlation analysis and stepwise discriminatory analysis as major indices of a new classification. By means of the optimum section, the boundary value of the axis of ordinate (G _(RI)) and axis of abscissas (V ^r) can be determined in the classification system. Thus, aV ^r –G _(RI) classification scheme diagram was formed and bituminous coal was divided into nine classes. Use of correspondence analysis reduced dimensions of sample-expressive space without losing initial information. The trend on the factor surface of samples shows that the classification obtained from correspondence analysis conforms to theV ^r –G _(RI) classification result and further verified the dependability of classification by two indices. At the same time, a certain relationship between the properties of a great variety of coal and their attributes can be explained. Hence, bituminous coal classification becomes more scientific, reasonable, and practical than before.     

虚实结合的地质工程实践教学方法改革探索——钻探虚拟仿真实验教学平台研究

拟仿真又称虚拟现实技术或模拟技术,就是用一个虚拟的系统模仿另一个真实系统的技术,将其应用于钻探科研、教学、训练等,对于钻探行业来说,是一次创新尝试。研发的钻探虚拟仿真实验教学平台,融入了钻探专业教学积累和计算机虚拟仿真技术等多个学科,解决了以往高校钻掘工程专业学生生产实习的诸多困难。虚拟钻进仿真平台已陆续为多个相关专业提供虚拟仿真教学,受到了各专业学生的欢迎,收到了良好的教学效果。该平台还可应用于各单位钻探技术人员、操作人员等的操作训练,以及科研和技术服务工作。     

内蒙古金厂沟梁金(铜)矿床的PGE、铁族和亲硫元素的地球化学特征与物质来源、形成环境

首次采用盐酸-过氧化氢封闭熔矿与ICP-MS相结合的方法,对金厂沟梁金(铜)矿床东、西两矿区典型矿石的铂族元素(PGE)、亲铁以及亲硫元素的含量进行了系统测定,结果显示矿石中上述元素的含量均高于实验的检测限;地球化学演化特征显示含矿流体具有岩浆性质,PGE对原始地幔/球粒陨石标准化后的配分曲线均呈强烈左倾斜的分馏模式,其配分曲线和与幔源岩浆有关的富铜硫化物和富铜镍硫化物熔体的形式相似,并与幔源玄武岩、碳酸盐熔体的配分模式基本一致,反映含矿流体具有幔源岩浆属性;从区域构造、岩浆热事件角度出发,结合典型斑岩铜(钼)矿床的PGE特征,初步确定其含矿流体形成于中生代大陆边缘环境,其直接的热动源是中生代底侵的玄武岩浆。成矿阶段富含金、铜矿石的Pd/Pt、Pd/Ir比值接近低钛玄武岩浆以及玄武安山岩,而成矿早阶段贫金、铜样品的Pd/Pt、Pd/Ir比值接近地幔;反映早期含矿流体可能是直接来自中生代幔源玄武质岩浆结晶分异,而富金(铜)流体的形成可能是玄武质岩浆演化晚期被地壳物质强烈混染后的富超临界流体岩浆(低钛熔体)发生岩浆与流体分离而产生;含矿流体演化过程的PGE地球化学行为与Cu或S(As)的饱和度有关,即主要受亲硫(铜)元素或结晶分异的硫化物矿物相所制约。     

指数平滑法及其在滑坡预报中的应用

指数平滑法是一种非统计性的预报方法，它具有计算过程简单，适应性好等优点，本文介绍的是其中的二次曲线指数平滑法及其在骨坡中，短期预报中的应用。     

Distributions of polycyclic aromatic hydrocarbons in the Daliao River Estuary of Liaodong Bay, Bohai Sea (China)

The distributions of 16 polycyclic aromatic hydrocarbons (PAHs) were determined in the aqueous phase, suspended particulate matter (SPM), sediment, and pore water of the Daliao River Estuary in Liaodong Bay, Bohai Sea (China). Total PAH concentrations ranged from 139.16 to 1717.87 ng L⁻¹ in surface water, from 226.57 to 1404.85 ng L⁻¹ dry weight in SPM, from 276.26 to 1606.89 ng g⁻¹ dry weight in sediments, and from 10.20 to 47.27 μg L⁻¹ in pore water. PAH concentrations were at relatively moderate levels in water, SPM, sediment and pore water in comparison with those reported for other estuary and marine systems around the world. Sedimentary PAH concentrations decreased offshore owing to active deposition of laterally-transported river-borne particles. PCA analysis of the possible PAH source suggested petrogenic and pyrolytic PAH inputs in the studied region.     

北京市区冬季颗粒态有机硝酸酯的污染特征与生成

有机硝酸酯是二次有机气溶胶的重要组分,对区域氮循环有重要意义。本次研究于2018年冬季在北京市区采集大气细颗粒物样品并测定5类主要有机硝酸酯的含量。结果显示,5类有机硝酸酯(包括单萜烯羟基硝酸酯、蒎烯羰基硝酸酯、柠檬烯羰基硝酸酯、油酸羰基硝酸酯和油酸羟基硝酸酯)的总浓度范围为127～528 ng/m³,对二次有机气溶胶的平均贡献为5.6%,昼夜浓度基本相当。其中,单萜烯羟基硝酸酯的含量最高,平均占比高达41%。灰霾期间有机硝酸酯浓度明显升高,相关性分析表明,燃煤和机动车排放的NO_x对有机硝酸酯浓度有显著促进作用。利用基于观测的盒子模型模拟了单萜烯羟基硝酸酯的生成速率,发现OH自由基和NO₃自由基氧化分别是白天和夜间单萜烯羟基硝酸酯的主要生成途径,但模拟值普遍低于计算值,推测模型中的生成机制可能有一定缺失。结果表明,人为活动会影响有机硝酸酯的二次生成,削减NO_x和臭氧有利于降低有机硝酸酯的大气浓度。     

Pointing and tracking analysis of alt‐azimuthal multi‐focus telescopes: the THEMIS case

We discuss the pointing and tracking configuration of THEMIS which may be considered as representative of those alt‐azimuthal telescopes with an optical configuration with multiple focal planes, not all locked to both the alt‐azimuthal coordinates. In the THEMIS case two focal planes are present. The primary focus F1 is locked to the alt‐azimuthal mount, while the secondary focus F2 (which is used by the instruments), is only locked to the azimuth angle. The different contributions to the final accuracy of both absolute pointing and tracking as observed at F2 are defined, and an extimation of the contribution of each component of the whole chain which affects the field position at F2 (software, mechanical and optical) is given. The experimental data are the result of a test campaign carried on at THEMIS in February and March 2002. We can say that (a) for all the used observing configurations, the tracking accuracy is coherent at any point along the trajectory with the correspondent absolute pointing accuracy, which is an indication for the quality of the telescope dynamical performances (b) the main contribution to the residual field shift which is observed at F2 arises from the opto‐mechanical alignment configuration of the optics between F1 and F2, which therefore is the crucial point for such multi‐focus configuration. More informations can be found at the official THEMIS website (http://www.themis.iac.es).