数字地质调查系统中空间数据库建库流程 关键技术的解决方案

空间数据库建库流程是数字地质调查系统总体技术流程的一个重要组成部分。针对地质人员实际工作量等方面的几个关键技术问题提出了详细的解决方案．并在数字地质调查系统的软件系统中以辅助建库工具、辅助检查工具、数据检索工具的形式加以实现。为建库提供了技术保障,保证了数据的质量,有效地提高了地质人员对地质调查系统的应用能力和建库的效率。     

Analytical exploration of γ-function explicit method for pseudodynamic testing of nonlinear systems

It has been well studied that the γ-function explicit method can be effective in providing favorable numerical dissipation for linear elastic systems. However, its performance for nonlinear systems is unclear due to a lack of analytical evaluation techniques. Thus, a novel technique is proposed herein to evaluate its efficiency for application to nonlinear systems by introducing two parameters to describe the stiffness change. As a result, the numerical properties and error propagation characteristics of the γ-function explicit method for the pseudodynamic testing of a nonlinear system are analytically assessed. It is found that the upper stability limit decreases as the step degree of nonlinearity increases; and it increases as the current degree of nonlinearity increases. It is also shown that this integration method provides favorable numerical dissipation not only for linear elastic systems but also for nonlinear systems. Furthermore, error propagation analysis reveals that the numerical dissipation can effectively suppress the severe error propagation of high frequency modes while the low frequency responses are almost unaffected for both linear elastic and nonlinear systems.     

渭河平原地下水分布特征与环境同位素研究——以白杨水源地为例

白杨水源地座落在渭河下游重镇——渭南市西北约5km处，为渭河冲积平原的一部分。区内第四纪松散堆积物巨厚，地形平坦，降水充沛，地表水丰富，为地下水储存提供了良好的空间。按含水介质的埋藏条件可划分为潜水、浅层承压水、中层承压水和深层承压水4个含水岩组。为了进一步研究地下水的补给形成机制、储存运移过程、排泄开采条件，本文结合环境同位素（包括14C、13C、3H、D和18O）对水源地地下水年龄、地下水运动速率以及一些水文地质参数进行研究和探讨。而同位素测定表明：水源地潜水为现代水，3H含量较高，河水补给量占1/2     

Estimation of periodicities in hydrologic data

Periodicites in hydrologic data are frequently estimated and studied. In some cases the periodic components are subtracted from the data to obtain the stochastic components. In other cases the physical reasons for the occurrence of these periodicities are investigated. Apart from the annual cycle in the hydrologic data, periods corresponding to the 11 year sunspot cycle, the Hale cycle and others have been detected.The conclusions from most of these studies depend on the reliability and robustness of the methods used to detect these periodicities. Several spectral analysis methods have been proposed to investigate periodicities in time series data. Several of these have been compared to each other. The methods by Siddiqui and Wang and by Damsleth and Spjotvoll, which are stepwise procedures of spectrum estimation, have not been evaluated.     

Comparative analysis of significant wave height between a new Southern Ocean buoy and satellite altimeter

中国于2019年第35次南极考察中,首次在南大洋布放了锚系实时综合观测浮标(西风带海洋环境监测浮标,WEMB),为深入了解此海区的海洋环境变化提供了宝贵资料.国家海洋技术中心WEMB研究团队基于AVISO公开发布的多颗卫星高度计L3产品,通过数据配对,误差统计和最小二乘线性拟合等方法,对西风带海洋环境监测浮标的有效波高数据误差进行了分析与校正.校正后的浮标有效波高统计显示西风带常年处于大浪以上海况,观测期间内57％处于巨浪海况,并且伴随有高度相关的大风天气.     

南海东北部冷泉区末次冰期沉积间断及其成因

对南海东沙海域冷泉区DH-CL10和DH-CL5柱状样开展AMS14C年代学、高分辨率底栖有孔虫和沉积物同位素以及沉积学研究。结果表明:DH-CL10柱状样在全新统底部574 cm处出现沉积间断,间断面相邻沉积物AMS14C年龄分别为9 850/(9 680~9 950) cal.aBP和27 610/(27 500~27 700) cal.aBP,相当于MIS2期和部分MIS3期的沉积缺失。底栖有孔虫Uvigerina bifurcata的δ13C值为-0.37‰~-1.91‰,平均值为-1.11‰,沉积物全岩碳同位素值为-22.7‰~-23‰,均为正常的碳同位素值。尽管该柱状样未发现天然气水合物分解释放的地球化学证据,但相邻的DH-CL5柱状样相当于其所缺失的部分沉积中的自生碳酸盐岩和沉积物的δ13C负偏明显,分别为-55.24‰和-25.9‰~-27.9‰,表明与天然气水合物分解有关。推断DH-CL10柱状样沉积间断所缺失的沉积物可能记录了天然气水合物分解的证据,且沉积间断主要出现在末次盛冰期低海平面,与天然气水合物易分解的时间相吻合,因此,沉积间断的形成可能主要与下伏天然气水合物的分解导致沉积物的滑塌有关。     

银额盆地哈日凹陷油气成藏条件及成藏模式

近年来,银额盆地哈日凹陷的油气勘探呈现出良好的态势,但对于哈日凹陷油气成藏条件相关研究甚少,已不能满足目前油气勘探开发的需求。本研究基于钻录井、地球物理、分析化验等资料,系统分析哈日凹陷油气成藏的烃源岩、储层、圈闭等条件,总结油气成藏条件配置关系,以期为哈日凹陷的后续油气勘探及地质研究提供依据。哈日凹陷主要发育三套烃源岩,其中银根组烃源岩有机质丰度极高,成熟度较低,有机质类型为Ⅰ-Ⅱ1型;巴二段烃源岩有机质丰度较高,成熟-高成熟,有机质类型为Ⅱ1-Ⅱ2型;巴一段烃源岩有机质丰度中等,成熟-高成熟,有机质类型为Ⅱ1-Ⅱ2型。储层类型为砂（砾）岩常规储层、碳酸质泥岩非常规储层和火山岩储层,且均属于特低孔超低渗储层,其中砂、砾岩储层和灰质泥岩储层物性最好,白云岩储层和火成岩储层次之,目前主力油藏主要集中在砂、砾岩储层和灰质泥岩储层这两种类型中。哈日凹陷主要发育两套岩性圈闭,即巴一段砂岩岩性圈闭和巴二段泥岩岩性圈闭,形成了源内（准）连续成藏模式和近源不连续成藏模式。     

Route planning and cost analysis for travelling through the Arctic Northeast Passage using public 3D GIS

To plan undeveloped optimal routes between Asia and Europe via the Arctic Northeast Passages using a 3D geographic information system (GIS), voyage paths are simulated in a 3D visual form. This ensures that the distances are calculated accurately, and that other voyage data such as water depths, sea ice distribution, and seashore topology are also easily deciphered, giving a more direct and clear demonstration compared to simplified presentations on an Electronic Chart Display & Information System (ECDIS). This article also implements a higher-geometry maze router in ice zone areas to obtain the optimal path in relation to safety and costs. This article compares the optimal Arctic Northeast Passages with traditional routes through the Suez Canal for dynamic analyses of the cost efficiency (including time costs, fuel costs, and other factors) of travel between major ports in Asia and Europe. The average benefit assessment is around 30–45% in a bulk carrier comparison. Thus, a 3D GIS can easily obtain and demonstrate safe navigation routes, providing a very convenient tool for initial planning.     

Modified compressive sensing approach for GNSS signal reception in the presence of interference

Pre-processing traditional navigation signals in global navigation satellite system (GNSS) receivers includes the conversion of an analog-to-digital sample and acquisition following the basic principle of Nyquist sampling theory. This condition inevitably increases the system computation time and cost of a modern wideband receiver. In recent years, the compressive sensing (CS) approach has been proven to effectively reduce the number of measurement samples required for digital signal acquisition systems. This method gives new potential to this modern design. In this study, a modified compressive sensing algorithm for the acquisition of a GNSS signal that is contaminated by an interfering signal is presented. The proposed method attempts to combine CS demodulation and the subspace projecting method to enhance GNSS signal acquisition performance with interference present. First, the received signal is sub-sampled and aliased from a compressive sampling process. This operation maintains the restricted isometry property (RIP) condition of the second sampling process using a Toeplitz-structured sensing matrix, which replaces a conventional random sensing matrix. The matrix ensures that distances between desired signals on the set of sparse space are not influenced by the sampling process. Next, the interference is eliminated through the orthogonal feature between the interference signal and the desired signal using the subspace projecting method. This also preserves the RIP of the projecting matrix to ensure that the original structure of the linear projection of the signal is preserved. After this, an iterative least-square method is utilized to recover the correlator output from the reception samples taken by the CS demodulator. In addition, the signal detection performance in the presence of co-channel interference using a CS demodulator is analyzed and evaluated. Finally, the relationships between signal detection probability, compressive factor and signal bandwidth are also illustrated. Several numerical results are presented to verify the theory.