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随着全国越来越多的高压直流线路投入运行,地电场观测数据的质量受到严重干扰。本文从高压直流输电干扰对地电场观测的影响机理出发,以江苏地区为例,对其5年来高压直流输电线路对地电场观测数据的影响特征进行分析总结,得出相关结论：①当地电场观测数据受高压直流输电线路干扰时,地电场观测数据会出现畸变,持续一段时间后,不平衡电流消失,数据恢复正常;②地电场观测数据产生畸变的方向与观测台站的装置布设方式、接地极相对观测台站的位置有关;③高压直流输电线路接地极距离江苏地电台站较远,同一台站同一方向受同一高压直流输电线路影响的长短极距观测数据变化幅度之比接近1;④不同次高压直流输电干扰在同一台站出现地磁干扰变化幅度一致时,同一台站的地电场观测变化幅度不一定一致,与台站和接地极之间的地下电性结构的导电性变化有关。 相似文献
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干扰系数表征了开采井受干扰的程度,其除受含水层性质、补给、排泄条件等天然因素影响外,还与井的结构和数量、井间距以及在平面上的布置等人为因素有关,因为试验复杂、成本高,一般多在水源地的勘探和开采阶段通过抽水试验求得。本文以甘肃省张掖电厂黑河滩水源地“探采结合”勘探实例,在单孔、干扰和群孔开采性抽水试验的基础上,准确计算干扰系数等水文地质参数,提出技术经济合理的开采方案,并通过探采生产井的优化布置,达到单井及井群出水量大、出水稳定、井间距小、井间干扰小,易于水源地管理保护和节约建设投资的目的。 相似文献
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We address the question of the reciprocity of drawdowns observed during a sequence of interference pumping tests performed within a porous medium, in the context of different conceptual models of subsurface flow. We provide a generalization of the work by Bruggeman (1972) [5], extending his results obtained in 1972 for Darcian flows in an unbounded, heterogeneous porous medium. We then analyze reciprocity within a dual-continuum conceptualization, where the medium is viewed as being composed of two overlapping continua, representing the porous matrix and embedded fractures, respectively. We show theoretically, and demonstrate numerically, that only drawdowns associated with the fracture continuum display reciprocity under transient flow conditions. Conversely, non-flowing matrix and fracture continua display reciprocity behavior under steady-state conditions. We then provide field evidence of the insurgence of reciprocity gaps by analyzing interference test data from the karstic limestone aquifer of the Hydrogeological Experimental Site (HES) in Poitiers, France. On the basis of our theoretical results and experimental observations, we discuss different interpretations of the observed reciprocity gaps. These include (a) non-linear dependencies of local hydraulic parameters, (b) occurrence of internal boundaries within the domain, (c) inertial effects that develop through open conduits within the rock matrix, (d) modifications of the aquifer properties between subsequent pumping tests, and (e) significant contribution of the matrix pressure in monitored wells when the behavior of the aquifer is conceptualized by a dual-continuum approach. 相似文献
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The main aims of this study are to show (i) that non-cylindrical three-dimensional (3D) fold shapes and patterns can form during a single, unidirectional shortening event and (ii) that numerical reverse modeling of 3D folding is a feasible method to reconstruct the formation of 3D buckle-folds. 3D viscous (Newtonian) single-layer folding is numerically simulated with the finite element method to investigate the formation of fold shapes during one shortening event. An initially flat layer rests on a matrix with smaller viscosity and is shortened in one direction parallel to the layering. Forward modeling with different initial geometrical perturbations on the flat layer and different lateral boundary conditions generates non-cylindrical 3D fold shapes and patterns. The simulations show that, in reality, the initial layer geometry and the boundary conditions strongly control the final fold geometry. Fold geometries produced from the forward folding models are used as initial setting in numerical reverse folding models with parameters identical to those of forward models. These reverse models accurately reconstruct the initial geometry of forward models with also only one extension event parallel to the previous shortening direction. The starting geometry of the forward models is inaccurately reconstructed by the reverse models if a significantly different viscosity ratio than in the forward models is used. This work demonstrates that reverse modeling has a high potential for reconstructing the deformation history of folded regions and rheological constraints such as viscosity ratio. Reverse models may be applied to natural 3D fold shapes and patterns in order to determine if they formed (i) during a single or multiple deformation events and (ii) as active buckle-folds with a viscosity ratio 1 or as passive, kinematic folds without buckling. This approach may find much application to fold interference patterns, in particular. 相似文献
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The mitigation of radio frequency interference (RFI) has a fundamental role in global navigation satellite system (GNSS) applications,
especially when a high level of availability is required. Several electromagnetic sources, in fact, might degrade the performance
of the global positioning system (GPS) and Galileo receivers, and their effects can be either in-band (i.e., secondary harmonics
generated by transmitters of other communication systems due to non-linearity distortions) or out-of-band (i.e., strong signals
that occupy frequency bandwidths very close to GNSS bands). We investigated the effects of real out-of-band signals on GNSS
receivers and analyzed the impact on the overall receiver chain in order to evaluate the impact of the interference source.
In particular, the analysis focuses on the spectrum at the front-end output, on the automatic gain control (AGC) behavior,
as well as on the digital processing stages (signal acquisition and tracking) at the analog digital converter (ADC) output.
This study refers to several experiments and data collections performed in interfered areas of downtown Torino (Italy). The
obtained results underline how digital/analog TV transmissions represent a potential interference source for GNSS applications
and might be critical for the safety of life services. 相似文献