Dauphiné twinning and texture memory in polycrystalline quartz. Part 3: texture memory during phase transformation

Samples of quartz-bearing rocks were heated above the α (trigonal)–β (hexagonal) phase transformation of quartz (625–950°C) to explore changes in preferred orientation patterns. Textures were measured both in situ and ex situ with neutron, synchrotron X-ray and electron backscatter diffraction. The trigonal–hexagonal phase transformation does not change the orientation of c- and a-axes, but positive and negative rhombs become equal in the hexagonal β-phase. In naturally deformed quartzites measured by neutron diffraction a perfect texture memory was observed, i.e. crystals returned to the same trigonal orientation they started from, with no evidence of twin boundaries. Samples measured by electron back-scattered diffraction on surfaces show considerable twinning and memory loss after the phase transformation. In experimentally deformed quartz rocks, where twinning was induced mechanically before heating, the orientation memory is lost. A mechanical model can explain the memory loss but so far it does not account for the persistence of the memory in quartzites. Stresses imposed by neighboring grains remain a likely cause of texture memory in this mineral with a very high elastic anisotropy. If stresses are imposed experimentally the internal stresses are released during the phase transformation and the material returns to its original state prior to deformation. Similarly, on surfaces there are no tractions and thus texture memory is partially lost.     

波浪作用下黄河口粉土液化与“铁板砂”形成机制的模拟试验研究

通过室内水槽试验,观测波浪作用下土体产生的振荡现象,分析土体内孔隙水压力的变化及波浪作用后土体强度变化特征,研究了波浪荷载作用下黄河口粉土粒径粗化和“铁板砂”的形成过程。试验及讨论结果表明：在波浪作用下上层粉土体大部分时间处于液化状态;由液化土形成的振荡土层与下部土层之间形成“W”型的滑动面,振荡土层的厚度随着波浪作用时间的增加而变小;细粒物质从振荡土层中的骨架中脱离进入水体中,并在土体表层形成一层以黏粒为主的絮凝状沉积物,其厚度随波浪作用时间的增加而增加,在土体停止振荡前达到最大值;土体液化是“铁板砂”形成的必要条件,而波浪引起的液化土体振荡则使“铁板砂”的形成成为可能。     

三元复合驱采出污水回注渗透率的影响因素分析

基于大庆油田三元复合驱采出污水回注对地层存在的损害现象,研究了污水回注渗透率的影响因素。采用室内水驱实验方法,对三元复合驱采出污水中悬浮物、油、碱、聚合物等因素进行了分析,阐述了各种成分对渗透率的影响机理。结果表明,悬浮物颗粒会堵塞孔隙喉道,油产生的“贾敏效应”将增大油水流动阻力,碱与岩石及黏土矿物问的物理化学作用会使地层结垢,聚合物在岩芯中的吸附和滞留共同造成地层渗透率的下降。因此,建议将三元复合驱采出污水中悬浮物、油、碱、聚合物等处理合格后再进行回注,以减轻对地层的损害。     

黔北务-正-道地区铝土矿镓含量特征与赋存状态初探

黔北务(务川)-正(正安)-道(道真)地区铝土矿是贵州铝土矿重要组成部分,对该区瓦厂坪、通塘底和高梁窝3个代表性铝土矿床的镓(Ga)及其一些主要和微量元素进行了分析,结合电子探针研究,初步探讨了ca在本区铝土矿中的赋存状态.结果表明:本区铝土矿及含矿岩系中的铝土质页岩中的Ga含量高,分别为56.1×10-6～131×10-6(平均91.0×10-6)和25.1×10-6～47.6×10-6(平均36.8×10-6),均达到铝土矿中Ga的综合利用指标(20×10-6),具有很高的综合利用价值;铝土矿中的Ga除可能以Al类质同象形式相对富集于Al矿物(主要为-水铝石)外,还有可能在金红石和锆石等重矿物中富集.     

质量传输和同位素交换:流动几何学和交换机制

耦合的质量传输和动力学限制的同位素交换模型综合考虑了平流、扩散、热液弥散 ,以及岩石与水之间的不平衡同位素交换等项因素。把耦合模型应用于 2个构造环境下的古热液系统 ,进而解释稳定同位素数据。对于造成环绕浅成侵入岩体分布的18O亏损环带的流体的流动几何学 ,以及浅部正断层流体流动的几何学 ,耦合模型提供了不同于单一同位素交换模型的解释。耦合模型也提供了关于同位素相对交换速率和同位素交换机制的信息。结果表明 ,断层带的动态重结晶促进了表面反应 ,进而便利了同位素交换 ;在化学不反应性和未变形的矿物中 ,同位素交换可能受制于固态条件下的扩散。     

Considerations on the European Standard EN 14157 Test Methods: Abrasion Resistance of Natural Stones Used for Flooring in Buildings

In Europe, the Wide Wheel abrasion (WWA) test and the B?hme abrasion (BA) test are among the most widely used standard test methods for determining abrasion resistance of natural stones, the former being the reference test method in EN 14157 Standard. However, it is stated in the Annex-A (Informative) of EN 14157 Standard that very limited data are available to provide correlations between these two test methods. To be able to fill this gap, in this study, 25 different natural stones belonging to sedimentary, metamorphic and igneous groups were tested for their abrasion resistance as well as physico-mechanical properties. Also, for a better interpretation of abrasion resistance characteristics of the tested stone materials, relationships between abrasion resistance and physico-mechanical properties were statistically examined. A statistically significant linear correlation (R ² = 0.85; P value = 0.000) was established between the WWA test and the BA test, which could be used in practice for converting the measured abrasion resistance values from one testing method to another. It was also found that the correlation between these two test methods improved significantly (R ² = 0.93; P value = 0.001) when relatively high-porosity stone materials (porosity ≥1%) were separately evaluated. Both methods of abrasion resistance employed in the present study showed statistically significant linear correlations with uniaxial compressive strength and Brazilian tensile strength, the former proving to be a more influencing parameter on resistance to abrasion. Also, from the point view of representing actual abrasion mechanism of stone materials in practice, the necessity of simulating multi-directional foot traffic in abrasion testing methods was discussed. In this respect, the reference test method in the EN 14157 Standard was criticized for not fully meeting this requirement. It was also pointed out that the reference method could have some drawbacks when applied to coarse-grained granitic rocks having cleavable minerals such as plagioclase and orthoclase feldspars.     

高精度温度采集系统设计

针对高精度温度采集的需求,设计了一个以低功耗单片机MSP430F149作为核心处理器,以PT100铂电阻为传感器的温度采集系统。为了提高系统的复用性,采用精密电阻法,从硬件设计上消除了恒流源电流漂移以及A/D转换电路参考电压精度对温度测量数据的影响。重点描述了系统设计方案,详细说明了恒流源选择的原则、电流偏差的消除以及AD7792转换器的操作步骤。实验结果表明,温度测量精度优于0.1 ℃。对比试验表明,系统稳定性良好,已应用于业务产品中。     

CINRAD/CB新一代天气雷达常见硬件故障及维护

通过对鄂尔多斯CINRAD/CB新一代天气雷达运行近6a(2005年11月至2011年11月)中出现的主要硬件故障成因分析,提出排除方法和措施。这些方法和措施在日常雷达运行维护保障应用中取得良好的效果,极大地减少了CINRAD/CB雷达的故障率和维修时间。     

江淮地区冬季一次罕见强对流风暴的数值模拟结果诊断分析

本文利用数值模拟的诊断分析结果对出现在江苏地区冬季的一次强对流风暴的成因进行了研究,结果表明,在河套气旋缓慢东移过程中,冷锋前暖区较长时期的大雾天气及下湿上干的湿度分布为强风暴的产生准备了大气层结不稳定的条件,中尺度辐合流场对强风暴的产生起了触发作用。对流云的下沉辐散气流是雷暴向前传播的重要机制。     

大连市小平岛地热资源潜力研究

在明确小平岛地质背景的基础上,分析地热地质条件并判断地热资源类型,结合已有两眼井S1、S2数据资料,采用热储法对其地热资源进行潜力评估。结果表明,大连市小平岛地区为深层传导型地热资源,该区桥头组及长岭子组上部为良好地热盖层,长岭子组下部及南关岭组上部(2 100~3 300 m)为该区热储层,热储体面积为7.3 km2。单井涌水量可达600~800 m3/d,水温可达50℃~60℃,地热资源量约为4.88×1011kcal,折合标准煤为6.97×107t,可开采的地热资源量约为7.32×1010kcal。