辽宁天然金刚石晶体缺陷的X射线形貌研究     

郭起志  孙继光 《矿物学报》1990,10(4):356-359

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  相似文献   

糜棱岩化作用中角闪石变形结构的透射电子显微镜研究   总被引：2，自引：0，他引：2  

薛纪越  赵晓宁 《矿物学报》1994,14(2):110-114,T001

石英的显微结构是判别含石英石变形程度的重要标志，为了认识角闪石在岩石变形过程中的特征，笔者对糜棱岩化闪长岩中普通角闪石的变形显微结构进行了光学和透射电子显微镜研究。研究的角闪石都在石英共生，因而以石英的变形结构作为角闪石变形研究的参照系。笔者发现，当石英呈明显波状消光时，普通角闪石未显示变形结构；当石英变形达到亚颗粒化和重结晶阶段时，普通角闪石的变形显微结构主要表现为单一方向的位错，其伯格斯矢量ｂ  相似文献   

天然变形微斜长石中几种面缺陷的透射电镜初步观察     

安琳吉 《矿物学报》1987,(2)

本文利用超高压透射电子显微镜对在相当于角闪岩相条件下天然变形的微斜长石进行了初步研究。研究发现,光学显微镜下看到的一组平行细纹不是出浴条纹,而是变形条带。另一种超显微构造——滑动小叶片见于变形条带邻区,它们和另一相矿物出港或沉淀形成的小叶片不同,是由矿物的变形造成的。变形条带、滑动小叶片以及比较常见的堆垛层错都相互平行,看来都是由分位错沿同一类型的滑移面运动形成的。  相似文献   

Mechanisms of OH defect incorporation in naturally occurring,hydrothermally formed diopside and jadeite     

M. Andrut  M. Wildner  J. Ingrin  A. Beran 《Physics and Chemistry of Minerals》2007,34(8):543-549

The IR spectrum of an alpine, hydrothermally formed diopside containing 17 wt ppm H₂O consists of three main OH absorption bands centred at 3647, 3464 and 3359 cm⁻¹. Jadeite from a Californian vein occurrence is characterised by bands at 3616 and 3557 cm⁻¹ and contains about 197 wt ppm H₂O. Based on the pleochroic scheme of the OH absorption bands in diopside, OH defect incorporation models are derived on the basis of fully occupied cation sites and under the assumption of M1 and M2 site vacancies; OH defects replacing O2 oxygen atoms are most common. The less pronounced OH pleochroism and the broad band absorption pattern of jadeite indicate a high degree of OH defect disordering. The pleochroic scheme of the main absorption bands at 3616 and 3557 cm⁻¹ implies partial replacement of O2 oxygen atoms by OH dipoles pointing to vacant Si sites. Under the assumption of M1 and M2 site vacancies, O1–H and O2–H defects are also derivable. OH incorporation modes assuming Si-vacancies should be considered for jadeite-rich clinopyroxenes formed in deep crust and upper mantle regions.  相似文献   

基于XGBoost算法的电网二次设备缺陷分类研究     

陈凯  南东亮  孙永辉  夏响 《南京气象学院学报》2019,11(4):483-489

电网二次设备缺陷严重程度的精确判断可为设备的运行和维护提供重要依据.针对电网二次设备缺陷数据特征量多、人为判断难度大、易出错等问题,提出基于XGBoost（eXtreme Gradient Boosting）的二次设备缺陷分类方法,提高二次设备缺陷分类的准确率.首先,对二次设备历史缺陷数据进行去异常值、编码等一系列预处理工作,并筛选出与设备缺陷相关性高的特征建立特征指标集;然后,利用历史缺陷数据对XGBoost模型进行训练和参数寻优;最后,用训练好的分类模型实现二次设备缺陷的准确分类.本文采用某电厂二次设备缺陷数据对所提算法进行算例分析,并与传统分类器（决策树、逻辑回归等）进行比较,结果表明XGBoost可以实现对二次设备缺陷程度的精确判断,进而可以很好地辅助检修人员进行设备的维护与管理.  相似文献   

Predicting the limit pressure capacity of pipe elbows containing single defects     

《Applied Ocean Research》2015

Numerous studies have investigated the weakening effect of corrosion or erosion induced defects on the limit pressure capacity of straight pipes, but few have focused on elbows. In this paper the roles of material and geometric parameters of an elbow with a single defect were studied and formulized by means of a vast nonlinear parametric finite element analysis followed by artificial neural network. Results showed that length, depth and circumferential position of the corroded area have the most effects on the limit pressure capacity. In addition to the primary approach of this paper, an analytical approach was also used by combining some ideas from previous relevant studies to reach to a simple and easy-to-use formula. The predictions of the two methods were compared with each other. This paper presents the first part of two-part study investigating elbows with single defects (part 1) and interacting defects (part 2).  相似文献   

Fe–Mg diffusion in olivine II: point defect chemistry,change of diffusion mechanisms and a model for calculation of diffusion coefficients in natural olivine     

Ralf Dohmen  Sumit Chakraborty 《Physics and Chemistry of Minerals》2007,34(6):409-430

Analysis of existing data and models on point defects in pure (Fe,Mg)-olivine (Phys Chem Miner 10:27–37,1983; Phys Chem Miner 29:680–694, 2002) shows that it is necessary to consider thermodynamic non-ideality of mixing to adequately describe the concentration of point defects over the range of measurement. In spite of different sources of uncertainties, the concentrations of vacancies in octahedral sites in (Fe,Mg)-olivine are on the order of 10⁻⁴ per atomic formula unit at 1,000–1,200 °C according to both the studies. We provide the first explicit plots of vacancy concentrations in olivine as a function of temperature and oxygen fugacity according to the two models. It is found that in contrast to absolute concentrations at ∼1,100 °C and dependence on fO₂, there is considerable uncertainty in our knowledge of temperature dependence of vacancy concentrations. This needs to be considered in discussing the transport properties such as diffusion coefficients. Moreover, these defect models in pure (Fe,Mg)-olivine need to be extended by considering aliovalent impurities such as Al, Cr to describe the behavior of natural olivine. We have developed such a formulation, and used it to analyze the considerable database of diffusion coefficients in olivine from Dohmen et al. (Phys Chem Miner this volume, 2007) (Part - I) and older data in the literature. The analysis documents unequivocally for the first time a change of diffusion mechanism in a silicate mineral—from the transition metal extrinsic (TaMED) to the purely extrinsic (PED) domain, at fO₂ below 10⁻¹⁰  Pa, and consequently, temperatures below 900 °C. The change of diffusion mechanism manifests itself in a change in fO₂ dependence of diffusivity and a slight change in activation energy of diffusion—the activation energy increases at lower temperatures. These are consistent with the predictions of Chakraborty (J Geophys Res 102(B6):12317–12331, 1997). Defect formation enthalpies in the TaMED regime (distinct from intrinsic defect formation) lie between −66 and + 15 kJ/mol and migration energies of octahedral cations in olivine are most likely ∼ 260 kJ/mol, consistent with previous inferences (Phys Chem 207:147–162, 1998). Plots are shown for diffusion at various constant fO₂ as well as along fO₂ buffers, to highlight the difference in behavior between the two. Considering all the diffusion data and constraints from the point defect models, (Fe–Mg) diffusion in olivine along [001] is best described by the Master equations: (1) At oxygen fugacities greater than 10⁻¹⁰ Pa: where T is in Kelvin, P and fO₂ is in Pascals, X _Fe is the mole fraction of the fayalite component and R is the gas constant in J/mol/K. (2) At oxygen fugacities less than 10⁻¹⁰  Pa: These equations reproduce all of the 113 experimental data points within half an order of magnitude. (3) Alternately, a global equation averaging out the change of mechanism may be used, with somewhat larger errors in reproducing the measured diffusion data. It underestimates data at higher temperatures, and overestimates them at lower temperatures on the average. Note that fO₂ is not explicitly considered here, leading to additional sources of error: To obtain diffusion coefficients along [100] and [010], log 6 needs to be subtracted from each of the above equations. An erratum to this article can be found at  相似文献   

TBM组装洞岩壁梁岩台缺陷处理技术研究          下载免费PDF全文

苗双平 《探矿工程》2016,43(5):89-91

TBM组装间岩壁梁在施工过程中,由于受地质条件及人为因素影响,导致TBM组装间岩壁梁在施工过程中发生无法成型或岩壁梁岩台存在缺陷,对后序岩壁梁上部吊车轨道安装埋下严重的安全隐患。以吉林引松供水总干线三标TBM组装间岩壁梁为研究背景,对岩壁梁缺陷处理进行了详细分析和研究,提出了岩壁梁岩台缺陷的处理技术,并对研究结果进行了验证,对类似工程有一定的参考价值。  相似文献   

裂纹缺陷体积百分数与CT数的关系分析   总被引：1，自引：0，他引：1  

敖波  赵歆波  张定华  徐夏刚  王唤抒 《CT理论与应用研究》2006,15(2):64-68

本文利用混合体的线性衰减系数的线性表示,推导出材料受力环境下,不含杂质时,微裂纹群的出现所带来的密度相对变化量与CT数相对变化量之间的关系式。进一步分析得到了裂纹缺陷体积百分数相对变化量与CT数相对变化量之间的关系式。含单杂质时,得到了裂纹缺陷体积百分数相对变化量与CT数相对变化量的关系式,并且把结论进一步推广到多杂质情形。为后期利用CT进行材料疲劳寿命分析奠定了理论基础。  相似文献   

孔隙压力对含随机缺陷岩石破坏过程及全部变形特征的影响   总被引：2，自引：0，他引：2  

王学滨  ;赵福成  ;潘一山 《地震学刊》2009,(1):1-8

对于平面应变压缩条件下含有随机缺陷的岩样,利用FLAC研究了孔隙压力对岩样破坏过程、全部变形特征及前兆的影响。以前编写的若干FISH函数,被用于生成缺陷和计算轴向、侧向、体积应变及侧向应变与轴向应变比值的负值（计算得到的泊松比）。在峰值应力之后,密实岩石单元服从线性应变软化行为及随后的理想塑性行为,而材料缺陷呈现理想塑性行为。当孔隙压力较高时,应力-侧向应变曲线具有一平台;破坏的前兆更明显;变形后岩样的体积总是大于原始体积;在初始加栽阶段、均匀变形阶段及峰后变形阶段,由于明显的侧向膨胀,计算得到的泊松比远大于0．5。当孔隙压力较低时,在峰值应力之前,变形后岩样的体积小于原始体积,体积扩容出现于峰值应力之后,引起了负的体积应变。利用广义虎克定律,解释了平面应变弹性状态下数值结果的合理性。对岩样进行带状区域扫描后,确认随机缺陷的初始分布与岩样的最终破坏形态紧密相关。  相似文献