长白山自然保护区生态环境质量的遥感评价

人类的生存质量与生态环境密切相关,利用遥感技术可快速地进行生态环境质量评价,为区域生态环境的治理、改善以及发展规划提供重要参考。本文以长白山自然保护区为例,选取1995、2007年Landsat5 TM影像和2015年Landsat8 OLI影像,反演得到能反映生态环境的绿度、湿度、热度和干度等指标,利用主成分分析法,依据新型遥感生态指数RSEI对长白山自然保护区1995-2015年的生态环境进行评价,结果表明：①绿度、湿度指标对区域生态环境起正向作用,热度、干度指标对区域生态环境起负向作用,且湿度对生态环境影响较大;②该区域1995、2007、2015年生态指数优良等级所占比例依次为49.520%、66.508%、76.189%,同时RSEI等级变差、不变、变好的比例分别为3.945%、55.598%、40.457%。生态环境质量整体不断改善,说明长白山自然保护区的天然林资源保护工程以及一系列生态保育措施起到了一定作用;而天池周边生态环境质量有所下降可能与旅游活动的快速发展有关;③逐步回归分析的结果表明,所选的各指标均为指示生态环境质量的关键指标;而裸露、干化地表的治理则是改善生态环境质量的关键。     

Crustal reworking in a shear zone: transformation of metagranite to migmatite

This study uses field, microstructural and geochemical data to investigate the processes contributing to the petrological diversity that arises when granitic continental crust is reworked. The Kinawa migmatite formed when Archean TTG crust in the São Francisco Craton, Brazil was reworked by partial melting at ~730 °C and 5–6 kbar in a regional‐scale shear zone. As a result, a relatively uniform leucogranodiorite protolith produced compositionally and microstructurally diverse diatexites and leucosomes. All outcrops of migmatite display either a magmatic foliation, flow banding or transposed leucosomes and indicate strong, melt‐present shearing. There are three types of diatexite. Grey diatexites are interpreted to be residuum, although melt segregation was incomplete in some samples. Biotite stable, H₂O‐fluxed melting is inferred via the reaction Pl + Kfs + Qz + H₂O = melt and geochemical modelling indicates 0.35–0.40 partial melting. Schlieren diatexites are extremely heterogeneous; residuum‐rich domains alternate with leucocratic quartzofeldspathic domains. Homogeneous diatexites have the highest SiO₂ and K₂O contents and are coarse‐grained, leucocratic rocks. Homogeneous diatexites, quartzofeldspathic domains from the schlieren diatexites and the leucosomes contain both plagioclase‐dominated and K‐feldspar‐dominated feldspar framework microstructures and hence were melt‐derived rocks. Both types of feldspar frameworks show evidence of tectonic compaction. Modelling the crystallization of an initial anatectic melt shows plagioclase appears first; K‐feldspar appears after ~40% crystallization. In the active shear zone setting, shear‐enhanced compaction provided an essentially continuous driving force for segregation. Thus, Kinawa migmatites with plagioclase frameworks are interpreted to have formed by shear‐enhanced compaction early in the crystallization of anatectic melt, whereas those with K‐feldspar frameworks formed later from the expelled fractionated melt. Trace element abundances in some biotite and plagioclase from the fractionated melt‐derived rocks indicate that these entrained minerals were derived from the wall rocks. Results from the Kinawa migmatites indicate that the key factor in generating petrological diversity during crustal reworking is that shear‐enhanced compaction drove melt segregation throughout the period that melt was present in the rocks. Segregation of melt during melting produced residuum and anatectic melt and their mixtures, whereas segregation during crystallization resulted in crystal fractionation and generated diverse plagioclase‐rich rocks and fractionated melts.     

小型气体质谱仪在中国大陆科学钻探钻井现场泥浆中气体的在线分析应用

采用OmniStar型质谱仪在线分析CCSD钻井泥浆中的H2、He、O2、N2、Ar、CH4和CO2等气体组分。采用脱气器、大气平衡仪、气体流量剂、冷冻干燥等样品采集装置,通过合理的设计可以有效地采集到井下气体并且克服大气的污染,除去气体中的水分。根据OmniStar型质谱仪的分析原理及分析能力,建立了可靠的分析方法,其精密度优于2%,准确度高,分析周期为8 s,为科学研究提供了及时、可靠的数据。     

熔片制样-X射线荧光光谱法测定海洋沉积物样品中主次量组分

采用混合熔剂熔融制备样片,用Axios X射线荧光光谱仪测定海洋沉积物样品中SiO2、Al2O3、Fe2O3、MgO、CaO、Na2O、K2O、P2O5、TiO2、MnO、BaO、Ni、Cu、V、Cr和Zn等16种组分,用理论α系数校正基体效应,分析方法的精密度(RSD,n=12)为Cu和Cr小于6%,其余大多数主次量组分小于2%。方法用海洋沉积物国家一级标准物质验证,测定值与标准值相符。     

Modeling and prediction of ventilation methane emissions of U.S. longwall mines using supervised artificial neural networks

Methane emissions from a longwall ventilation system are an important indicator of how much methane a particular mine is producing and how much air should be provided to keep the methane levels under statutory limits. Knowing the amount of ventilation methane emission is also important for environmental considerations and for identifying opportunities to capture and utilize the methane for energy production.Prediction of methane emissions before mining is difficult since it depends on a number of geological, geographical, and operational factors. This study proposes a principle component analysis (PCA) and artificial neural network (ANN)-based approach to predict the ventilation methane emission rates of U.S. longwall mines.Ventilation emission data obtained from 63 longwall mines in 10 states for the years between 1985 and 2005 were combined with corresponding coalbed properties, geographical information, and longwall operation parameters. The compiled database resulted in 17 parameters that potentially impacted emissions. PCA was used to determine those variables that most influenced ventilation emissions and were considered for further predictive modeling using ANN. Different combinations of variables in the data set and network structures were used for network training and testing to achieve minimum mean square errors and high correlations between measurements and predictions. The resultant ANN model using nine main input variables was superior to multilinear and second-order non-linear models for predicting the new data. The ANN model predicted methane emissions with high accuracy. It is concluded that the model can be used as a predictive tool since it includes those factors that influence longwall ventilation emission rates.     

GPS RTK技术及其在“数字城管”中的应用

概述了RTK技术作业模式的基本原理,分析了RTK技术的误差来源及解决对策,讨论了RTK技术在数字城管控制测量及部件测量中的应用。     

The Diagenesis of Plant Lipids during the Formation of the Krepoljin Coal Basin (Serbia) — Using Multivariate Statistical Analysis in the Saturated Biomarkers

The composition of the saturated hydrocarbon fraction of soluble organic matter (bitumen) from the Krepoljin brown coal basin (East Serbia) of Miocene age was investigated. The Krepoljin basin is especially interesting from a geochemical point of view. Namely, by the end of Tertiary Period, the basin was covered by powerful Mesozoic formations of great possibilities, the bedding became hermetically enclosed and protected from subsequent external influences. The nature of early diagenetic processes in the environment with abundant accumulation of organic substance is defined by the molecular content of bitumen through the connections of molecular structures to potential precursors in paleoplant phylla, as well as by the degree of their diagenetic transformations. The hierarchy of parameters based on molecules of saturated hydrocarbons was determined by applying the principal component analysis to the soluble organic matter. The most significant, most “loadings” values of component C1, are the plant types such as precursors or participants in early diagenetic transformations of steranes Cs27-algal precursor material, Cs28-moulds, Cs29-higher land and water plants; resinous from the group of higher plant gymnosperms (G); also triterpanes α and β-amirin-dicotyledonous angiosperms (A) and bacterial and/or terrestrial plants population represented by hopanes/moretanes; as well as the parameters which describe the degree of diagenetic/maturation transformation of precursor biomass, and based on next reactions: (1) shifting of methyl group, influenced by the inorganic sediment constitutents, sterane-rearranged steranes, (2) isomerization in the ring system, ααα→βββ C29 sterane as well as (3) isomerization on chiral center of the side chain sequence R→S C29 sterane S/(S+R). Additionally, a pyrite-derived inhibitory effect on the rearrangment of C29 steranes must be taken into account, but not on triterpanes reaction. Non-appearance of statistically important correlations, before all with maturational depended parameters, and after all also with source indicators contributies to the affirmation of the newly-suggested parameter α-Phyllocladane/S27 as the real source biomarker of coal. Indicators derived from the distribution and abundance of n-alkanes and isoprenoid alkanes are of less significance in hierarchy of parameters.     

Water pollution sources assessment by multivariate statistical methods in the Tahtali Basin,Turkey

In this study, multivariate statistical methods including factor, principal component and cluster analysis were applied to surface water quality data sets obtained from the Tahtali River Basin, Turkey. Factor and principal components analysis results revealed that surface water quality was mainly controlled by agricultural uses and domestic discharges. Cluster analysis generated two clusters. Based on the locations of the sites consisted by each cluster and variable concentrations at these stations, it was concluded that agricultural discharges strongly affected north and northeast part of the region. These methods are believed to assist water managers to understand complex nature of water quality issues and determine priorities to improve water quality.     

Web环境下房产测绘信息三维可视化技术研究

Web环境下的三维可视化技术存在诸多技术难点。相对单机及局域网环境,Web环境下的网络响应时间将很大程度上影响着三维可视化的实际效果。文章围绕这一问题,从三维建模效率和三维模型数据量两方面入手,在分析现有方法不足的基础上,结合房产测绘信息特点,提出了基于模型库的房产测绘信息三维场景实时构建方法、基于模块化和参考复用的三维建模方法,进而提出一套行之有效的解决方案,使Web环境下房产测绘信息三维可视化技术得以实用化。实验系统证明了该方法的有效性、实用性。     

赫尔默特方差分量估计方法在嫦娥一号卫星测角计算中的应用

在我国探月工程嫦娥一号卫星测轨中,需要对测距观测和VLBI时延观测进行综合解算,以确定卫星的角位置时间序列,因而需要考虑不同类型观测资料之间的权重分配问题。本文通过仿真计算,具体比较了不同情况下最小二乘平差方法与赫尔默特(Helmert)方差分量估计方法下测角计算的精度。虽然通常情况下观测资料都提供误差估计,但此估计却不一定能够准确反映实际的观测精度。仿真计算表明,此时应用Helmert求解方法,能够显著提高解算的精度。相比于最小二乘平差方式,Helmert求解方式在计算量上略有增加,但这对于现代计算设备几乎可以忽略。