Study　on　the　feature　selection　and　classifica－tion　effect　of　precursory　data　of　ground　tilt     

李正媛  吴奕麟  李晓军 《地震学报(英文版)》1996,9(4):605-610

Ｓｔｕｄｙｏｎｔｈｅｆｅａｔｕｒｅｓｅｌｅｃｔｉｏｎａｎｄｃｌａｓｓｉｆｉｃａ┐ｔｉｏｎｅｆｅｃｔｏｆｐｒｅｃｕｒｓｏｒｙｄａｔａｏｆｇｒｏｕｎｄｔｉｌｔＺＨＥＮＧ－ＹＵＡＮＬＩ（李正媛），ＤＥ－ＦＵＣＨＥＮ（陈德福），ＹＩ－ＬＩＮＷＵ（吴奕麟）ａ...  相似文献   

围压条件下PDC切削齿受力测量传感器的设计          下载免费PDF全文

王克雄  翟应虎  夏宏南 《探矿工程》1996,(2):31-32

详细叙述了围压条件下ＰＤＣ切削齿受力（轴向力、切削力、侧向力）的测量方法，并研制成功了相应的围岩测力传感器；解决了传感器的防水问题，同时用实验标定的方法消除了高压给传感器测量精度带来的影响。  相似文献   

高精度连续测斜仪探管的原理及应用   总被引：1，自引：0，他引：1  

Ma Shiwen  Dong Shaopeng  Meng Ming  Zhao Jie 《中国煤炭地质》2008,(12)

北京中地英捷物探仪器研究所新研制的PSX-2高精度连续孔斜检测探管,采用三轴正交磁性传感器和两个正交加速度计传感器测量,其中加速度计传感器测量顶角,磁性传感器测量方位角,实时测量的信息及解算则依靠内部集成的24位模数转换单片机来完成。实地测井证明,PSX-2型孔斜检测探管可以在顶角较小时稳定的测量方位角,符合煤田测井行业对钻孔测斜仪提出的高精度、小体积、低成本的要求。  相似文献   

光学遥感成像半实物仿真中坐标系统转换     

李明譞  江刚武  张锐  张一 《测绘科学技术学报》2017,34(4)

构建了一种以六自由度机器人为运动平台的光学遥感成像半实物仿真系统,利用共线条件方程的齐次坐标变换形式建立了仿真系统的成像模型,并对坐标系统转换问题进行了研究。提出一种利用全站仪确定沙盘坐标系与机器人基坐标系相互转换的"两步法";通过控制机器人旋转和平移运动,提出了一种单特征靶标测量模型,实现了摄像机坐标系与机器人工具坐标系的相互转换。最后通过空间前方交会计算多个靶标的物方坐标值,与物方真值进行比较,从而对系统精度进行评价。实验结果表明,立体定位误差优于0.5 mm,验证了提出的坐标转换方法的可行性与有效性,可为遥感成像仿真系统的设计与研究提供严密的空间基准和转换模型。  相似文献   

Assessing the potential of integrated Landsat 8 thermal bands,with the traditional reflective bands and derived vegetation indices in classifying urban landscapes     

Terence Darlington Mushore  Onisimo Mutanga  John Odindi  Timothy Dube 《国际地球制图》2017,32(8):886-899

Reliable and up-to-date urban land cover information is valuable in urban planning and policy development. Due to the increasing demand for reliable land cover information there has been a growing need for robust methods and datasets to improve the classification accuracy from remotely sensed imagery. This study sought to assess the potential of the newly launched Landsat 8 sensor’s thermal bands and derived vegetation indices in improving land cover classification in a complex urban landscape using the support vector machine classifier. This study compared the individual and combined performance of Landsat 8’s reflective, thermal bands and vegetation indices in classifying urban land use-land cover. The integration of Landsat 8 reflective bands, derived vegetation indices and thermal bands overall produced significantly higher accuracy classification results than using traditional bands as standalone (i.e. overall, user and producer accuracies). An overall accuracy above 89.33% and a kappa index of 0.86, significantly higher than the one obtained with the use of the traditional reflective bands as a standalone data-set and other analysis stages. On average, the results also indicate high producer and user accuracies (i.e. above 80%) for most of the classes with a McNemar’s Z score of 9.00 at 95% confidence interval showing significant improvement compared with classification using reflective bands as standalone. Overall, the results of this study indicate that the integration of the Landsat 8’s OLI and TIR data presents an invaluable potential for accurate and robust land cover classification in a complex urban landscape, especially in areas where the availability of high resolution datasets remains a challenge.  相似文献   

Modeling seasonal surface temperature variations in secondary tropical dry forests     

《International Journal of Applied Earth Observation and Geoinformation》2017

Secondary tropical dry forests (TDFs) provide important ecosystem services such as carbon sequestration, biodiversity conservation, and nutrient cycle regulation. However, their biogeophysical processes at the canopy-atmosphere interface remain unknown, limiting our understanding of how this endangered ecosystem influences, and responds to the ongoing global warming. To facilitate future development of conservation policies, this study characterized the seasonal land surface temperature (LST) behavior of three successional stages (early, intermediate, and late) of a TDF, at the Santa Rosa National Park (SRNP), Costa Rica. A total of 38 Landsat-8 Thermal Infrared Sensor (TIRS) data and the Surface Reflectance (SR) product were utilized to model LST time series from July 2013 to July 2016 using a radiative transfer equation (RTE) algorithm. We further related the LST time series to seven vegetation indices which reflect different properties of TDFs, and soil moisture data obtained from a Wireless Sensor Network (WSN). Results showed that the LST in the dry season was 15–20 K higher than in the wet season at SRNP. We found that the early successional stages were about 6–8 K warmer than the intermediate successional stages and were 9–10 K warmer than the late successional stages in the middle of the dry season; meanwhile, a minimum LST difference (0–1 K) was observed at the end of the wet season. Leaf phenology and canopy architecture explained most LST variations in both dry and wet seasons. However, our analysis revealed that it is precipitation that ultimately determines the LST variations through both biogeochemical (leaf phenology) and biogeophysical processes (evapotranspiration) of the plants. Results of this study could help physiological modeling studies in secondary TDFs.  相似文献   

Petrophysical analysis of regional-scale thermal properties for improved simulations of geothermal installations and basin-scale heat and fluid flow     

Andreas Hartmann  Renate Pechnig  Christoph Clauser 《International Journal of Earth Sciences》2008,97(2):421-433

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Precise temperature monitoring in boreholes: evidence for oscillatory convection? Part 1: Experiments and field data     

Vladimir Cermak  Jan Safanda  Louise Bodri 《International Journal of Earth Sciences》2008,97(2):365-373

Temperature was monitored in two boreholes in Kamchatka (Russia) in years 2001–2003. Ten-min reading (sampling) interval was selected for the first half-year run followed by shorter (12 days) experiment with 5-s reading interval. A similar experiment was repeated later in the test borehole Sporilov (Prague, Czech Republic), where four temperature–time series were performed with reading intervals varying from 1 to 20 s. All temperature–time series (except the record from the bottom of the hole) displayed intermittent, non-periodic oscillations of temperature of up to several hundredths of degree with sharp gradients and large fluctuations over all observed time intervals. No such oscillation was detected at the bottom of the hole. The spectral analysis revealed a high level of stochasticity in the measured signal. Calculated spectra showed “band-pass” behavior without any definite peaks, which might characterize certain periodicity. Local growth of the second moment technique revealed the presence of at least two distinct temperature-forming processes. One of them can be related to heat transfer in the structurally and compositionally complex subsurface. The second process, which presents the bulk of the measured signal, probably reflects certain intra-hole convection. We hypothesized that the oscillatory regime of such convection is responsible for the stochastic nature of measured temperatures. Results of numerical modeling describing the fluctuation of water-cells in a vertical slot support the idea of thermally unstable water column in a hole, the instability of which produces a complex oscillation system. Model solutions and their discussion is presented in Part II of this work.  相似文献   

Simulation of axis-symmetric seismic waves in fluid-filled boreholes in the presence of a drill string     

José M. Carcione  Flavio Poletto  Biancamaria Farina 《Computational Geosciences》2008,12(4):593-604

A numerical algorithm for simulation of 2-D (axis-symmetric) wave propagation using a multidomain approach is proposed. The method uses a cylindrical coordinate system, Chebyshev and Fourier differential operators to calculate the spatial derivatives along the radial and vertical direction, respectively, and a Runge–Kutta time-integration scheme. The numerical technique is based on the solution of the equations of momentum conservation combined with the stress–strain relations of the fluid (drilling mud) and isotropic elastic media (drill string and formation). Wave modes and radiated waves are simulated in the borehole-formation system. The algorithm satisfies the reciprocity condition and the results agree with an analytical solution and low-frequency simulation of wave-propagation modes reported in the literature. Examples illustrating the propagation of waves are presented for hard and soft formations. Moreover, the presence of casing, cement, and formation heterogeneity have been considered. Since the algorithm is based on a direct (grid) method, the geometry and the properties defining the media at each grid point, can be general, i.e., there are no limitations such as planar interfaces or uniform (homogeneous) properties for each medium.   相似文献   

A new method for the interpretation of the constant-head well permeameter   总被引：1，自引：0，他引：1  

Giorgio Cassiani 《Journal of Hydrology》1998,210(1-4):11-20

A novel semi-analytical solution for the interpretation of the constant-head permeameter test is introduced, which accounts for the correct mixed-type boundary condition at the wellbore, unlike all published analytical solutions. Capillarity can also be accounted for. The simplifications are that flow from the bottom of the borehole is neglected (therefore the solution is applicable to slender boreholes, where the ponding depth is at least 10 times the radius) and capillarity can be modeled with a quasi-linear approach. The Green's function approach leads to an integral equation, the solution of which does not show significant ill-posedness. Two sub-cases are presented: the first neglects capillary effects (the all-saturated approximation) and the second (general solution) takes them into account. The all-saturated solution is successfully tested against finite element simulations. The corresponding values of the borehole shape factor C are slightly larger than the ones obtained with approximate analytical solutions from the literature. When capillarity is accounted for, C changes of a factor of 10 when the dimensionless sorptive number A goes from typical values for fine soils to typical values for coarse soils (about two orders of magnitude of variation for A). This range shifts to lower values of A as the dimensionless borehole depth increases. Consequently, the all-saturated solution is a good approximation of the soil behavior for boreholes with large ponding depth, and coarse soils. The proposed semi-analytical solution is fast to compute and thus it is possible to use it in an automated optimization technique to fit field data and estimate the field-saturated hydraulic conductivity and the sorptive number; this would not be feasible using a numerical solution.  相似文献