GPS技术在地铁平面控制测量中的应用研究

简要说明了地铁GPS控制测量的重要性及GPS网形的优化设计问题,介绍了LGO结合科傻平差软件解算GPS的基本方法,讨论了GPS控制网复测较差限差取值问题。根据实际经验,总结了针对常见问题的相应解决办法。     

真菌的生物地质作用及其在环境修复中的应用

真菌在自然界中作为有机体的分解者、动植物的病原菌和共生菌,广泛分布于地表和土壤环境,并通过一系列生长 及代谢活动,与周围环境中的岩石或矿物基质发生作用,进而影响地球化学过程。真菌的生物地质作用主要包括：真菌促 进下岩石或矿物的风化,真菌诱导下次生矿物的形成,以及与上述过程相对应的营养元素和金属离子的迁移与固定。近年 来,由生物风化发展而来的生物浸取技术,已经在生物采矿、选矿以及受污染土壤和工业垃圾的生物治理等多个方面得以 应用。而将真菌用作吸附剂的生物吸附研究,则显示其能有效祛除工业废水及受污染地下水中所含的金属和有机污染物。 因此,无论是从地球化学循环的角度出发,还是考虑资源与环境效应,研究真菌的生物地质作用都具有十分重要的意义。 文中从真菌生物风化、生物矿化和环境修复等方面综述了真菌生物地质作用研究的最新进展,并对今后的研究工作进行了 展望,旨在加深真菌在地质微生物学作用过程中的认识,促进相关领域的进一步发展。     

A reconstruction method for three‐dimensional pore space using multiple‐point geology statistic based on statistical pattern recognition and microstructure characterization

To predict the macroscopic properties (e.g., transport, electromagnetic, and mechanical properties) of porous media, it is necessary to have a three‐dimensional (3D) representation of porous media. We reconstruct the geologically realistic 3D structure of Fontainebleau sandstone based on the two‐dimensional (2D) thin sections by using the multiple‐point statistics method. For this method, the size of template is an important parameter that reflects the perceived scale of spatial structure of porous media. In this paper, we take advantage of entropy method to obtain the appropriate size of the template, which is proven to be correct and feasible. The reconstruction method proposed by us combines successive 2D MPS simulations as well as 3D MPS simulation, which takes account into the pore structure information (e.g., heterogeneity and connectivity) both intralayer and interlayer. This reconstruction method is tested on Fontainebleau sandstone for which 3D images from micro‐CT scanning are available. Applying local percolation theory analysis, this new approach can depict the expected patterns of geological heterogeneities. In addition, it also can well reproduce a high degree of connectivity of the pore space better than other reconstruction methods based on lower‐order statistics. Copyright © 2011 John Wiley & Sons, Ltd.     

Earthquake-induced collapse mechanism of two types of dangerous rock masses

As the economy of China develops, an increasing number of key traffic projects have been undertaken in the west of China, where there are high, steep rock slopes. The collapse of dangerous rock masses, especially following a strong earthquake, is one of common geological disasters known in rock slope engineering. Therefore, it is important to study the collapse mechanism of dangerous rock masses induced by an earthquake and the analysis approach of its stability. This study provides a simple and convenient method to determine the collapse mechanisms of two types of dangerous rock masses (i.e. cantilever and upright) associated with the definition and calculation of the safety factor, which is based on the flexure theory of a constant-section beam by combining with the maximum tensile-stress criterion to depict the process of crack propagation caused by seismic waves. The calculation results show that there are critical crack depths in each form of the dangerous rock masses. Once the accumulated depth of the crack growth during an earthquake exceeds the critical depth, the collapse will occur. It is also demonstrated that the crack extension amount of each step is not a constant value, and is closely associated with the current accumulated crack depth. The greater the cumulative crack depth, the more easily the crack propagates. Finally, the validity and applicability of the proposed method are verified through two actual engineering examples.     

Automated mechanism generation. Part 1: mechanism development and rate constant estimation for VOC chemistry in the atmosphere

A framework for automated mechanism generation for modeling atmospheric chemistry at the mechanistic level was developed. In part 1, categorization of reactions into reaction families and determination of rate coefficients using a hierarchical approach that uses experimental data and kinetic correlations are described. The main focus was to develop kinetic correlations for estimating rate coefficients that are not available experimentally, and the main correlation used was the Evans–Polanyi relationship that relates the activation energy to the heat of reaction. A hierarchical scheme for calculating heats of reaction and other thermodynamic properties was developed. The rate constants calculated using the proposed correlations are in most cases within an order of magnitude of available experimental values, and 82% are within a factor of five.     

辽宁天然金刚石晶体缺陷的X射线形貌研究

本文利用透射X射线衍射形貌术研究辽宁天然金刚石晶体缺陷的问题。实验结果表明,金刚石晶体中存在有位错、亚结构及包裹体等缺陷。从这些研究中可以找到辽宁天然金刚石成矿时的某些特点     

多因素复杂参数下的圆形地下水泥土桩地基场地地震效应分析

为了实现圆形地下水泥土桩地基场地地震效应的准确分析,提高建筑抗震性能,采用ABAQUS有限元软件,分析不同随机参数的圆形地下水泥土桩地基场地地震效应,分析运算采用的各项参数、场地地质条件以及明确等效复合土体计算参数,通过二维复合模量简化模型,全面考虑加固深度、土桩地基上新建结构、下卧基岩地形、水泥土模量、输入地震波属性和不同场景环境等随机参数对圆形地下水泥土桩地基场地地震效应的影响。实验结果表明:圆形地下水泥土桩地基加固区地表的峰值加速度反应较自由场的反应显著降低,地基地表的峰值加速度反应随着水泥土桩加固深度和复合模量的增加而减小;地基上新建结构对坝基周围场地地震动特性形成较强的干扰,干扰幅度以及区域同新建结构规模具有较高的关联性;地基下端基岩表面地形同上部地基场地地震动特性间具有一定的关联性;场地土层条件对复合地基地震效应影响较大;桩体模量在可能变化范围内,对水泥土桩地基地震效应影响相对较小。     

A biomimetic experimental study of magnesium ion mineralization in Mg-enriched aragonite

In this work, we test the hypothesis that the Mg~(2+)content in biogenic aragonite has a systematic relationship with biomolecules. A series of biomimetic experiments were conducted to show the dependence of Mg~(2+)in aragonite on the model organic molecules added to the mineralizing solution, including the concentration of various organics, mineralization temperature, Mg/Ca ratio and Mg~(2+)initial concentration. The mineralized products were characterized by powder X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FT-IR), field emission scanning electron microscopy(FESEM), thermogravimetric analysis(TGA), and inductively coupled plasma-atomic emission spectrometry(ICP-AES). High Mg~(2+)is detected in aragonite obtained in the presence of organics, whereas the lowest Mg~(2+)is measured in aragonite without organics. Moreover, the concentration of Mg~(2+)in aragonite increases gradually with the amended organics. Mg K-edge NEXAFS spectra show that the magnesium microenvironment in aragonite is similar to the organic-associated environment, indicating that the Mg~(2+)ions are not on the aragonite lattices, but adhere to the intracrystalline organics. Furthermore, the mineralization temperature, Mg/Ca ratio and Mg~(2+)content in mineralization medium significantly influence Mg~(2+)content in aragonite, reiterating the effect of the microenvironment on aragonite biomineralization.     

偏最小二乘（PLS）—极谱络合吸附催化波同时测定轻稀土La,Ce,Pr,Nd,Sm,Eu

运用２７３Ａ电化学系统确定了偏最小二乘计极 法同时测定Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｓｍ、Ｅｕ分量的最佳体系为：０．０８ｍＬ的ＸＯ、ＰＨ＝４．０的ＨＡＣ－ＮａＡＣ缓冲溶液６ｍＬ。６种轻稀土在１．０＊１０＾－７－８．０＊１０＾－６ｍｏｌ＝／Ｌ的浓度范围内有良好的线性关系,每种稀土元素的检出限为１．４＊１０＾－８ｍｏｌ／Ｌ。６种轻稀土的相对标准偏差为６．７％－１２．８％。