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81.
Xian-Huan Wen 《Mathematical Geology》1994,26(6):717-731
Field tests of hydraulic conductivity (e.g., injection test, pumping test, etc.) in low permeability formations are subject to censoring due to the detection limit of the instruments used. An iterative method of estimating the mean and variance of hydraulic conductivity data with a presumed log-normal distribution function is presented. This method accounts for the data that are actually below the lower detection limit (called truncated data) and thus gives distribution parameters that are more representative for the underlying distribution. The proposed method is then tested on two simulated normally distributed random datasets having different variances. The results show that the means and variances estimated by the proposed method are very accurate. Finally, the method is used to estimate the mean and variance of hydraulic conductivity data from single hole water injection tests in a fractured geological formation. 相似文献
82.
基于瞬变电磁法探测理论,结合井下瞬变电磁探测试验,研究井下瞬变电磁探测采煤工作面巷道的影响以及探测方法,提出矿井瞬变电磁探测采煤工作面"交集法",即在井下实际探测方面,需要在采煤工作面的两条巷道内做工作。在山西吕梁某矿对该方法进行了试验验证,结果表明,采用"交集法"探测结果比较准确,可提高探测精度,减少钻探工作量,是目前矿井瞬变电磁法探测采煤工作面较为可靠的方法,建议在煤矿中推广使用。 相似文献
83.
为探测掘进巷道前方地质构造,研制一套矿井分布式地震超前探测系统。系统基于地震波反射理论,通过检波器分布式接收或震源分布式激发确定地质异常体的位置。为了进一步提高煤矿采掘过程中构造的预测预报精度,采用分布式观测系统和孔中胶囊检波器进行数据采集以提高设备的灵敏度,通过负视速度原理排除侧帮和后方地质异常体的干扰,利用绕射共偏移算法优化数据反演成果。经过大量试验验证和归纳总结,该系统采用人工锤击震源可有效探测出前方70 m范围内的地质异常信息,采用人工炸药激发震源可有效探测出前方150~200 m范围内的地质异常信息。研究结果表明,矿井分布式地震超前探测系统通过从硬件到软件优化,可实现采掘过程中对地质构造的探测精度,并提高探测效率。 相似文献
84.
Precise, automatic and fast method for vanishing point detection 总被引:1,自引:0,他引:1
A new automated approach for vanishing point detection in images of urban scenes is described. This method is based on the theorem of Thales. The main contribution of this paper is the automatic and simultaneous detection of all vanishing points of the image, achieved by converting this problem into the detection of circles in a complex cloud of points, in which each point corresponds to a segment and is associated with an uncertainty. This extraction of circles uses a RANSAC method, modified to improve its speed by using accumulation techniques (Hough transform or otherwise). This robust estimation is then refined by least squares error propagation using the individual variances of each segment. The algorithm is robust, its accuracy is optimised and it is entirely automatic. Its successful operation has been tested on a large number of images of varied urban scenes. 相似文献
85.
86.
Milad Janalipour 《International Journal of Digital Earth》2018,11(12):1241-1268
Building damage maps after disasters can help us to better manage the rescue operations. Researchers have used Light Detection and Ranging (LiDAR) data for extracting the building damage maps. For producing building damage maps from LiDAR data in a rapid manner, it is necessary to understand the effectiveness of features and classifiers. However, there is no comprehensive study on the performance of features and classifiers in identifying damaged areas. In this study, the effectiveness of three texture extraction methods and three fuzzy systems for producing the building damage maps was investigated. In the proposed method, at first, a pre-processing stage was utilized to apply essential processes on post-event LiDAR data. Second, textural features were extracted from the pre-processed LiDAR data. Third, fuzzy inference systems were generated to make a relation between the extracted textural features of buildings and their damage extents. The proposed method was tested across three areas over the 2010 Haiti earthquake. Three building damage maps with overall accuracies of 75.0%, 78.1% and 61.4% were achieved. Based on outcomes, the fuzzy inference systems were stronger than random forest, bagging, boosting and support vector machine classifiers for detecting damaged buildings. 相似文献
87.
目前钻孔机器人位姿调节多采用手动遥控调节与人工复测结合,未实现全自动调节,开环控制精度低、自动化能力低、无法实现煤矿用探放水、防突和防冲钻孔机器人精确开孔定位与孔群全自动施工。通过分析钻孔机器人钻臂结构和动作,建立了钻臂运动学模型;通过对加工误差、机身变形、装配间隙等影响因素分析,发现采用回转减速器蜗轮蜗杆结构间隙会引起倾角和方位角误差放大,并在机身平时会引起倾角和方位角误差最大达0.85°;为消除误差,首先采用传统钻臂运动学误差补偿方法建立了钻臂静、动态误差补偿模型,利用全站仪测试关节间隙和变形量,基于补偿模型和RBF神经网络法求逆解得到误差补偿量,钻臂期望位姿与实际位姿误差的
88.
影像间的匹配点通常受基本矩阵或单应矩阵模型约束,利用不同的描述模型引导匹配会得到不同的匹配结果,并且将直接影响后续的三维重建结果。引入GRIC测度来检测匹配数据的拟合模型,推导了GRIC测度拟合单应矩阵模型和基本矩阵模型的误差方程。模拟数据和真实影像数据实验表明,GRIC测度比利用误差大小来检测拟合模型更加可靠,可以更有效地剔除误匹配点。 相似文献
89.
A novel structural damage detection method with a new damage index,i.e.,the statistical moment-based damage detection(SMBDD) method in the frequency domain,has been recently proposed.The aim of this study is to extend the SMBDD method in the frequency domain to the time domain for building structures subjected to non-Gaussian and non-stationary excitations.The applicability and effectiveness of the SMBDD method in the time domainis verified both numerically and experimentally.Shear buildings with various damage scenarios are first numerically investigated in the time domain taking into account the effect of measurement noise.The applicability of the proposed method in the time domain to building structures subjected to non-Gaussian and non-stationary excitations is then experimentally investigated through a series of shaking table tests,in which two three-story shear building models with four damage scenarios aretested.The identified damage locations and severities are then compared with the preset values.The comparative results are found to be satisfactory,and the SMBDD method is shown to be feasible and effective for building structures subjected to non-Gaussian and non-stationary excitations. 相似文献
90.