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881.
????BURSA????????????????????????????????????????????????????????????????????????????????????????????????????Χ???????????? 相似文献
882.
883.
手持GPS在地质矿产调查中常用来测量地质观察点和一般地质工程点点位坐标.本文根据多年的实践经验探讨手持GPS的使用及坐标转换,获取需要的各种测量成果,具有较强的实用性. 相似文献
884.
GPS����λˮ 总被引:2,自引:9,他引:2
魏子卿 《大地测量与地球动力学》2007,27(4):1-7
????????????θ?????????GPS????λ??,????????????????????????GPS???????EIGEN-CG03C????????λ?????е?????????????????????GPS????λ???????θ??????????0.5 m???????θ??????????????????????????10 cm?? ????????λ??????????????θ??????????, GPS???????????????????????????θ???????????????GPS????λ?????????????????????? 相似文献
885.
Based on the earthquake catalog reported by the Chinese digital seismic network in recent years, we select the earthquakes with both surface wave magnitude and local magnitude and fit them into a relationship between the two magnitudes. The systematic difference is found from the formula which has been used for 30 years. Because of a large dynamic range and wide frequency range of the current digital observation system, in addition to a larger number of stations and earthquakes being used compared to before, the relation obtained in this paper seems more reliable. Our calculation shows that there is no significant difference before and after magnitude conversion so we suggest the abandonment of magnitude conversion. The site response of a station consists of amplification at different frequencies. The amplification is equal to about 1 and changes little with frequency at stations located on basement rock, and it is greater than 1 at low frequency ranges and less than 1 at high frequency ranges at stations located on sediment layers. The difference between magnitudes from single station located on sediment layer and the average magnitude from the whole network increases from negative to positive with period. It seems that there is no fixed station correction factor and the station correction method does not work to improve the accuracy and magnitude estimates. 相似文献
886.
深层致密砂岩储层脆性指数评价新方法 总被引:1,自引:1,他引:0
储层岩石脆性评价是储层压裂改造方案设计的重要基础工作,对储层压裂改造效果有着重要影响。以准中地区深层致密砂岩储层为研究对象,开展了0~90 MPa多级围压下的岩石三轴试验,分析了围压变化对于岩石脆性的影响。针对现有脆性指数对目标储层岩石脆性评价效果不理想的情况,基于应力-应变曲线中的能量转化关系建立了新的脆性指数模型,包括岩石峰前峰后脆性指数和综合脆性指数。研究结果表明:试验围压对岩石脆性评价有着显著影响;岩石峰前脆性随围压增大先增加后减小,峰后脆性和综合脆性随围压增大而递减;研究区储层含砾细砂岩的脆性较细砂岩的脆性小,脆性差异主要表现在峰后脆性。 相似文献
887.
888.
2005年7月25日23点43分在黑龙江省林甸县发生了Ms5.1地震.据黑龙江省地震台网测定,这次地震的震中位置为北纬46°56'、东经124`54'.根据大庆地震台网记录结果,至2005年12月30日24时止,大庆林甸5.1级地震序列共发生余震88次,最大余震为7月25日23时57分ML4.0地震.其中不可定位地震56次,ML0.1-0.9地震1次,ML1.0-1.9地震18次,ML2.0-2.9地震7次,ML3.0-3.9地震4次,ML4.0-4.9地震1次. 相似文献
889.
A new solution of transient confined–unconfined flow driven by a pumping well is developed and compared to previous approximate solutions of Moench and Prickett [Moench AF, Prickett TA. Radial flow in an infinite aquifer undergoing conversion from artesian to water table conditions. Water Resour Res 1972;8:494–9] and Hu and Chen [Hu L, Chen C. Analytical methods for transient flow to a well in a confined–unconfined aquifer. Ground Water 2008;46(4):642–6]. The problem is rewritten in dimensionless form with the Boltzmann transform. The nonlinear equation for flow in the unconfined zone is solved with the Runge–Kutta method. Position of the conversion interface is determined with an iteration scheme. This study shows that the confined–unconfined flow depends on three dimensionless parameters that represent the confined–unconfined storativity ratio (aD), the ratio of the initial hydraulic head over the aquifer thickness (fi), and the dimensionless pumping rate (qD). The rate of expansion of the unconfined zone increases with qD, but decreases with aD and fi. Differences between the two previous approximate solutions and the new solution of this study are observable in the estimated position of the conversion interface and the drawdown–time curves. The new solution can be applied to estimate the time for confined–unconfined conversion to occur (critical conversion time), and the time when the pumping well becomes dry (critical drying time). The critical conversion time is found to be very sensitive to the initial hydraulic head. The critical drying time is often much larger than the critical conversion time and may never be observed during a finite pumping period. 相似文献
890.
深度域地震波速度模型是地震勘探中最重要的参数之一,是获得精确深度域偏移剖面的基础.本文基于成像射线的概念,阐述了时间偏移域和深度域之间的关系,明确了时间偏移后的像点是通过成像射线与深度域的散射点联系起来的.在有横向变速的情况下,时间偏移剖面需要经过时深转换才能真实反映深度域层位,同样,从时间偏移剖面上提取的速度也需要经过时深转换才能得到深度域的速度.与前者不同的是,在速度的时深转换中,不仅速度的位置需要改变,且其数值也需要进行校正.该校正因子有几种等价的描述形式:度规量、速度扩散因子和几何扩散因子. 相似文献