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1.
瞬时应变型岩爆模拟试验中花岗岩主频特征演化规律分析 总被引:3,自引:0,他引:3
利用深部岩爆模拟试验系统对花岗岩进行室内瞬时岩爆模拟试验,同时利用声发射系统采集试验过程中声发射信号,得到试验全过程应力和声发射波形信息时域图。结合声发射累计能量曲线特征,找到5个关键拐点,即花岗岩初始加载能量激增后产生的第一个拐点A、岩爆发生前两次明显的上升台阶处拐点B和C、岩爆发生时的能量突跃点D、最终峰值点E。将关键点处波形信号从全时域波形中提取出来并进行快速傅里叶变换,得到各关键点二维功率谱图,结果表明:花岗岩声发射主频值在加载初期时为106 kHz,随着荷载的增加,频率由低频向高频过渡,频带变宽且由单峰向多峰转化,频率成分复杂预示多种破裂模式的发生。岩爆前和最终岩爆时刻频带又变窄并恢复单峰,主频值降低至与初始加载时一致,约为106 kHz,预示着岩爆时刻花岗岩岩石高能量的释放。 相似文献
2.
计算机上的橡皮膜技术 总被引:11,自引:1,他引:11
由于构制和修改任意形三维物体在技术上有一定的难度,三维物探人机联作反演长期未能得到实际应用。本文提出一种技术,称之为橡皮膜技术,可以灵活地构制任意形三维物体。其特点是:用鼠标器交替地移动设置在一个闭合曲面周围的若干控制点,控制点带动其附近的曲面变形,形成所期望的复杂形态的物体模型;还可按需要多次增加控制点的数目,对模型做更为精细地调节。文章详细介绍了该技术的核心-磨光算法。通过多次磨光,将一个由为 相似文献
3.
The shape of sedimentary particles may carry important information on their history. Current approaches to shape classification
(e.g. the Zingg or the Sneed and Folk system) rely on shape indices derived from the measurement of the three principal axes
of the approximating tri-axial ellipsoid. While these systems have undoubtedly proved to be useful tools, their application
inevitably requires tedious and ambiguous measurements, also classification involves the introduction of arbitrarily chosen
constants. Here we propose an alternative classification system based on the (integer) number of static equilibria. The latter
are points of the surface where the pebble is at rest on a horizontal, frictionless support. As opposed to the Zingg system,
our method relies on counting rather than measuring. We show that equilibria typically exist on two well-separated (micro
and macro) scales. Equilibria can be readily counted by simple hand experiments, i.e. the new classification scheme is practically
applicable. Based on statistical results from two different locations we demonstrate that pebbles are well mixed with respect
to the new classes, i.e. the new classification is reliable and stable in that sense. We also show that the Zingg statistics
can be extracted from the new statistics; however, substantial additional information is also available. From the practical
point of view, E-classification is substantially faster than the Zingg method. 相似文献
4.
Magnetic field singularities detected earlier as the self-intersection points of the F = 0 curves/surfaces are studied (where F is a certain differential factor calculated in the reference frame of the magnetic field at the given point); these singularities can be considered to be sources of the energy release in solar flares. Two types of such singularities, called transition points (TPs), have been found: the first type (TP1) corresponds to an intersection of the same type of components (terms) of the divergence of the magnetic field, and the second type (TP2) to the intersection of dissimilar components. There are some discontinuous spatial processes at these singularities, which produce jumps in the components of the divergence of the magnetic field (and their signs). TP2 singularities should result in much stronger effects than those resulting from TP1 singularities, which should give rise to the most powerful solar flares. The singularities studied are also compared with the null point of the magnetic field, when it exists. In particular, a model magnetic field containing a null point is considered. It is shown that the TP singularities do not coincide with the null point, but can be located in its vicinity; in the case considered, the TP1 singularity is located fairly close to the null point. 相似文献
5.
一种机载雷达点云数据的快速分类方法 总被引:1,自引:0,他引:1
机载激光雷达扫描技术可以以点云形式快速获取地形表面高精度三维信息。基于激光雷达扫描数据及建筑物本身的拓扑信息就可以对建筑物进行精确的重建,而重建中最关键的技术是对点云数据进行分类,进而进行地物识别。对大规模三维点云数据进行快速分类,提出一种采用区域分割结合基于最小二乘平差的多项式拟合方法,将大量离散的三维点云分割后进行多项式拟合,并将二维数据分类转化为一维数据分类。在分类的基础上,将建筑物几何规则作为约束条件提取了房屋边缘。实验分析表明,该方法既能去除多余噪声,又能有效保留特征点,分类的总误差率低于3%。 相似文献
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Turkey established the TUSAGA-AKTIF CORS Network in May 2009. Network software and central server were updated in 2016. With this update, GLONASS message type was determined for Flächen Korrektur Parameter (FKP), Master Auxiliary Concept (MAC) and Virtual Reference Station (VRS) network-based real time kinematic (NRTK) techniques. A 64 bit central server and the Trimble Pivot Platform network software were also acquired with this update. To the best of our knowledge, there has not been a comprehensive accuracy and precision test of the new system yet. In this paper, we aimed to create empirical accuracy and precision model of FKP, MAC and VRS NRTK techniques of the updated system as a function of baseline distance and occupation time. It is intended that surveyors can perform mission planning according to the requirements of accuracy and precision using these models. Seven test points and two check points were chosen to conduct the experiment. The baseline lengths with respect to the closest continuously operating reference stations (CORS) station were determined as 5-20-40-50 km approximately. Three thousand epochs with 2-s sampling interval were obtained for northing, easting and ellipsoidal height coordinate components of NRTK techniques at each point. Assumed true coordinates of each test point were determined by static survey using the GAMIT/GLOBK scientific software. In terms of accuracy and precision, our results show that empirical accuracy model depends only on the occupation time while empirical precision model depends on both the baseline length with respect to the closest CORS station and the occupation time for each NRTK technique. The results indicate that estimated accuracy and precision models can be safely used for mission planning purposes. 相似文献
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This paper presents a method for the analysis of free field ground motions at various depths from actual seismograph records. The proposed method replaces the propagating rupture on the fault surface by a fictitious focal point and a seismograph station in the vicinity of the given soil site. A fictitious focal point and seismograph station scheme is used to calibrate the free field ground motion of the soil site. The harmonic vibration analysis of the half space, which elastodynamic infinite elements are adopted in the far field and finite elements in the near field, yields the Fourier transform of any constituent wave in terms of the amplitude of the forces applied at the focal point, thus in terms of the Fourier transforms of the accelerations in three orthogonal directions recorded at a seismograph station. If a seismograph station is in the far field (as it is usually), the recorded values there can be transformed into the values at the infinite element node by means of appropriate shape functions. The results can be more refined in case of the availability of simultaneous records at more seismograph stations. In case of N stations, we assume N fictitious focal points, and solve a set of 3N simultaneous equations of 3N forces, three orthogonal forces at each focal point. Naturally, only the results by the present method were ‘exact’ at the calibrated points, and should be accurate in-between and near those points. The accelerations at the points near seismograph stations at various depths can also be obtained. An appropriate inverse Fourier transform algorithm will properly yields all results as time functions. 相似文献
10.
一种实用的等值线型数据网格化方法 总被引:7,自引:2,他引:7
数据网格化通常包括三大类:测线型数据网格化、等值线型数据网格化和离散点型数据网格化。文中研究的等值线型数据分块存储、网格点八方位搜索插值的网格化方法较好地解决了平面等值线型数字化数据的网格化计算问题,其计算数据量大,实用性强,精度高,计算速度快。 相似文献
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通过对时间域激发极化法视极化率异常进行水平导数分析,由形状因子和深度的函数绘制不同的窗口曲线,然后利用不同窗口曲线的交叉点获得极化异常体的形状和深度信息,从而实现了同时确定极化体形状和埋深的一种简便快速的定位方法——窗口曲线法。利用这种方法,能够实现对均匀场中极化体形状和深度信息的快速定位。为了检验本方法,对无随机噪声和有随机噪声的理论数据、实验室物理模拟数据和矿山实例分别进行了验证,解释结果与理论值相对误差基本小于10%。 相似文献
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隧洞工程弹性参数反演的可辨识性及量测优化布置探讨 总被引:1,自引:1,他引:0
探讨依据完备的量测信息开展弹性参数反演的可辨识性及量测的优化布置,对于指导岩土工程反演实践具有重要的实用价值。利用平面弹性复变函数方法和一般弹性理论,推导出任意形状隧洞的位移、应力解析表达式,基于隧洞围岩位移、应力的解析解,依据参数可辨识条件和量测优化布置的最灵敏原则,探讨了地下隧洞工程弹性反演参数的可辨识性及测点优化布置,并通过算例进行了验证。研究表明,依据完备的量测信息开展弹性反分析,只要测点布置方式适当、反演参数满足相应的限定条件,可同时惟一辨识出5个参数P、Q、M、E、μ。参数反演的可辨识性受隧洞形状复杂性的影响,随着隧洞复杂性的提高,参数可同时惟一辨识需满足的限制条件大为减少,对测点布置方式的要求也会降低。工程实践中,为避免量测数据的少量误差导致反演计算结果的大幅度波动,测点(线)应根据最灵敏原则优化选择各反演参数的灵敏系数最大的测点(线)组合进行量测布置。 相似文献
16.
Recent advances in image analysis techniques have allowed rapid generation of peripheral points of two-dimensional objects. Such points, defining overall shape of an object, have been analyzed using several techniques including geometric shape analysis, Fourier analysis, and, more recently, by “eigenshape” analysis. The latter technique purports to represent a general, optimal, and universally best technique to analyze shapes of fossils. Such a technique was devised allegedly due to failure of exisiting techniques. We seriously question the validity of the eigenshape technique and discuss limitations of such an approach. Objections presented in this paper are applicable to a variety of other multivariable data reduction techniques as well. 相似文献
17.
地震波形状描述技术及其在地震相分析中的应用 总被引:2,自引:1,他引:1
地震波的波形变化及其分布规律,是重要的地震参数之一。对地震波形中包含的地质信息加以分析和应用,将有利于提高储层预测,油藏描述精度和钻探成功率。以波形的形状进行分类,并进行地震相和沉积相分析,是目前应用较为广泛的一类地震属性分析的方法技术。在这类技术中,其核心是波形的形状描述和刻画技术。这里以Stratimagic软件为例,通过对构成地震波形状的主要参数(振幅、相位、频率)对其波形状变化影响的细致分析和比较,总结出了可以利用地震波的形状变化规律及形状描述方法,探讨了依据该波形形状分类在地震相分析中的效果和意义。 相似文献
18.
Kingshuk Roy Choudhury 《Mathematical Geosciences》2009,41(5):535-553
Finite strain estimation is a widely used technique for the study of rock deformation in structural geology. One particular
algorithm proposed by Shimamoto and Ikeda uses the ‘average shape matrix’ of deformed markers. This paper provides a detailed
error analysis for resulting strain estimates in two dimensions. When the number of markers exceeds 100, estimators of components
of the strain tensor are shown to have an approximately Gaussian distribution with variances that increase with their mean.
Equal variance estimators are obtained by applying a log transform for the elongation and an arcsin transformation for the
orientation estimates. Confidence interval formulae for strain tensor components are proposed. Lithology specific constants
arising in these formulae are estimated from undeformed samples. The results are validated by application to simulated data
as well as observational data from thin sections of sandstone sampled from SE Ireland. 相似文献
19.
In Korea most of the old mine workings were worked with room and pillar method or sublevel caving method and today they possess
great possibility of surface subsidence especially for shallow depth mines. In most of the cases, mine roadways, rooms and
pillars are irregular in shape and information about the local geology is uncertain. For these reasons, it is difficult to
standardize the estimating method of subsidence especially sinkhole type over abandoned mine area. This paper describes the
application procedure for the fuzzy reasoning techniques to analyze the possibility of sinkhole occurrences over abandoned
mines. This technique is implemented in software which can simplify the analysis procedure and present the possibility of
sinkhole subsidence without having precise information about local geological/mining conditions. This technique has been applied
to forecast sinkhole possibilities at Bonghwa site where a massive sinkhole has already been occurred. 相似文献
20.
电子探针化学测年技术及其在地学中的应用 总被引:13,自引:0,他引:13
主要对电子探针化学测年技术的基本原理及其相关技术作一介绍。并以其在地学中的具体应用 ,如对独居石、锆石的化学测年 ,证明它是一种分析快速、测试容易的技术 ,与传统的同位素法测得的年龄具可比性。此项技术对矿石的来源、不同矿物的不同环带、不同世代的成分演化乃至时间演化均可进行分析 ,并可使年龄数据点与成分数据严格对应 ,而且测试所需的样品量少 ,可进行单颗粒的测定。因此 ,当某些岩体的被测矿物有捕虏体成因、岩浆成因、地幔成因等各种来源时 ,可分别求出某单一事件的年龄。另外 ,利用碎屑独居石的 w( Pb O) /w( Th O*2 )比值来确定碎屑岩的源岩是一种新的方法 ,并指出了其局限性 相似文献