矿井突水水源的Bayes逐步判别分析研究

对Bayes逐步判别法在矿井突水水源判别中的应用进行研究分析。选用六大常规离子（ Ca2＋、Mg2＋、K＋＋Na＋、SO42-、Cl-、HCO3-）作为判别因子,建立Bayes逐步判别分析模型,以内蒙唐家汇矿区突水水源判别为例,在建立的判别模型回判检验准确率仅60%,分析原因可能与选定的特征判别因子对该矿区水样分类影响能力较弱有关。增加总硬度、碱度、PH值和矿化度作为判别因子,重新建立Bayes判别分析模型,使回判准确率提高至90%,证明适当增加特征判别因子对改善Bayes逐步判别模型的可靠性和稳定性有利。经对唐家会矿区的3个未知样本进行了判别分析,并与距离判别法和模糊综合评判法判别结果对比,结果表明Bayes逐步判别模型准确性较好,判别准确率与距离判别结果完全相同,而优于模糊综合评判方法。在合理选取特征判别因子的情况下,Bayes逐步判别法是目前矿井突水水源判别的有效方法。     

全球大陆弧玄武岩（CAB）的特征——与岛弧玄武岩（IAB）和弧后玄武岩（BAB）的对比

活动陆缘玄武岩（CAB）主要出现在安第斯,早先大多认为CAB 大体相当于IAB,在许多判别图中, CAB 基本上与IAB 在一起, 只是LILE 富集和HFSE 亏损的程度略有差别而已。本文的研究表明,尽管CAB 富集LILE,但是,Nb-Ta 亏损不是非常明显。在最新的采用大数据方法厘定的判别图中,CAB 不同于IAB,不是落在IAB 区,而是位于IAB 与OIB 的过渡区域。CAB 中保留了很多OIB 的印记,说明板块俯冲时伴随有来自地幔深部的岩浆的加入,故CAB 中保留了OIB 的印记。我们的研究还发现, 在安第斯弧后盆地玄武岩具有OIB 的印记,而非MORB 的特征。本文按照大数据的思路,讨论了CAB 的特征,并与IAB、BAB 进行了初步的对比。研究表明,CAB 明显不同于IAB,CAB 兼具IAB 和OIB 的特征,但对其深度的认识还有待于今后进一步的研究。     

宁淮高速公路沿线膨胀土的判别及防治

利用规范判别膨胀土类型常常出现不一致的困惑，结合宁淮高速公路等工程实例就“不一致”问题提出作者的见解，并对此工程的膨胀土改性处理进行了掺灰比试验研究。     

Discrimination between primary magmatic biotites, reequilibrated biotites and neoformed biotites

The ternary diagram TiO₂–FeO*–MgO (FeO* = FeO + MnO) is proposed as a quantitative objective tool for distinguishing between primary magmatic biotites and those that are more or less reequilibrated, or possibly neoformed, by or within a hydrothermal fluid. The limit of the domains of the primary magmatic biotites, the reequilibrated biotites and the neoformed biotites were determined on the basis of optical, paragenetic and chemical criteria. To cite this article: H. Nachit et al., C. R. Geoscience 337 (2005).     

Who’s afraid of red, yellow and green?: Redlining in Rotterdam

Redlining research is common practice in the US but not in other countries. Does this imply redlining does not take place elsewhere? This paper presents evidence from Rotterdam, the second largest city of the Netherlands, showing that in the 1990s it was impossible to get a home mortgage in large parts of the city. However, after Rotterdam joined the National Mortgage Guarantee (an institutional control measure) in 2000, hardly any evidence of redlining was found. This paper not only shows that redlining takes place outside of the US context, but also that a (discursive) treatment based on case study research has the possibility to gain a fuller understanding of redlining practices than a statistical/correlation analysis of mortgage data. Interviews with key actors are instrumental to unravelling how, why and when those in power make their decisions: agents are structured by the existing system while, at the same time, some of these agents have the power to re-produce as well as re-structure (transform) the system. One of the geographical outcomes of the agency-structure interaction is that credit is “redirected away from poorer to richer (and therefore “safer”) groups” as part of a strategy of risk avoidance [Leyshon and Thrift, 1997]. Thus redlining, like any other form of financial exclusion, deepens and accentuates prevailing levels of uneven development by creating geographical variations in access to the financial system [Dymski and Veitch, 1992].     

The petrogenesis of modern and ophiolitic lavas reconsidered: Ti-V and Nb-Th

Tectonic discrimination diagrams are a key tool for understanding ancient volcanic rock origins. In this contribution we compile over 15,000 whole rock compositions to re-evaluate the Ti-V discrimination diagram and compare it to another commonly used tool, the Nb/Yb-Th/Yb diagram. We have reformulated the Ti-V diagram into a log–log plot to distinguish samples more clearly at lower concentrations. The compilation shows that MORB are dominated by Ti/V = 20–43, whereas juvenile arc tholeiites and boninites are characterized by Ti/V < 20 generally, although there is minor overlap at the boundary (Ti/V = 20–22). Plume-related volcanic rocks (ocean island basalts, oceanic plateaux, and continental flood basalts) generally have Ti/V > 43, although there may be significant overlap with MORB-like ratios for ridge-centered OIB and for some oceanic plateaux. About 56% of alkaline OIB have Ti/V > 70. Back-arc basins are dominantly MORB-like. Melt models show that MORB and juvenile arc volcanics most likely formed under different ?O₂ conditions, but are permissive of similar ?O₂ if the arc rocks form by much higher melt fractions. The Nb/Yb vs. Th/Yb plot clearly distinguishes most oceanic basalts (MORB, plateaux, OIB) from subduction-related volcanic rocks (boninite, juvenile arc tholeiite, calc-alkaline) and from flood basalts. We propose here a new two-proxy diagram of Ti/V vs. Th/Nb, which incorporates the advantages of both.     

Modeling position error probability density functions for statistical inversions using a Goff–Jordan rough surface model

Buried unexploded ordnance (UXO) continues to be a difficult remediation problem from both a sensing and a discrimination point of view. Modern approaches to both the sensing and discrimination problems utilize high bandwidth electromagnetic induction (EMI) sensors to collect geo-referenced data which is then inverted, or fit, using a forward model in order to obtain features that can be directly interpreted using the physics associated with electromagnetic induction-based sensing. These features are then used in a variety of classification architectures. One aspect of this process that has captured recent interest is that uncertainty in the positions at which data was collected can degrade the inversion performance and thus the subsequent classification. Several mechanisms to address this issue have been explored that range from filtering and prediction of actual positions to exploiting Bayesian approaches for uncertainty mitigation. In the Bayesian approach, a statistical model of the position errors is used as a prior for integrating over the uncertainty in the inversion process. In this study, we demonstrate that errors in the statistical priors used in this process can negatively impact subsequent classification performance, thus highlighting the need for an accurate statistical model for the position errors. Next, we propose a mechanism by which to obtain such models. Specifically, we utilize a Goff–Jordan rough surface model and simulate the sensor data collection system motion over the simulated ground or ocean surfaces to calculate errors and generate statistical models. Our results suggest that this approach can be used to develop the statistical models necessary for mitigating uncertain position information.     

泥质砂岩黏土附加导电强度评价指数定义及应用方法

针对泥质砂岩黏土附加导电还没有综合定量评价指标的现状,从Archie公式和Waxman-Smits方程计算的含水饱和度的相对误差出发定义了黏土附加导电强度指数η,并考察了地层水电导率C_w、阳离子交换容量Q_v、含水饱和度S_w、饱和度指数n对η的影响,给出了黏土附加导电强度判别方法和图版,通过低阻油气层的工程应用实例探讨了η在饱和度方程选取中的应用.结果表明,η随C_w、S_w、n值的增大而以近似乘幂规律减小,随Q_v的增大而近似线性增大;C_w与Q_v对η的影响最大,n与S_w次之;无法由单一因素判断黏土附加导电性强弱,必须综合考虑Q_v、C_w、S_w、n的影响;对于低阻油气层,可利用该指数按照"三步法"及判别图版定量判断低阻成因并为饱和度模型的选取提供技术依据.     

植物碳同位素分馏作用与环境变化研究进展

在简述植物碳同位素与环境要素之间关系的基础上,介绍了植物碳同位素分馏机理和分馏模式,并综述了近年来利用植物碳同位素及其组成在研究环境变化方面的研究进展,同时对未来的研究作了展望。