Advantages of the Optimum Pulse Moment in Surface NMR and Application in Groundwater Exploration     

Jianwei Pan  Kai Lu  Zhongmei Wang  Kaitian Li  Zhenyu Li 《Ground water》2021,59(2):199-213

The surface nuclear magnetic resonance (SNMR) method is widely used in groundwater detection because of its sensitivity to hydrogen in water and direct water detection. However, low signal-to-noise ratios (SNRs) restrict the development of this technique. An optimum pulse sequence is designed according to correspondence between the pulse moment strength and its best detection depth. Because only selection of the pulse intensity distribution according to the target aquifer depth is required and the “on-resonance” pulse pattern is still employed, this pulse sequence emission can be easily achieved using existing SNMR instrumentation. Numerical simulation results and field experiments show that, compared with traditional exponential growth pulses, the optimum pulse sequence effectively improves the SNR of the SNMR method. The aquifer boundary, water content, and pore characteristics of the inversion result are thus more consistent with characteristics of underground structures. Additionally, because the optimum pulse sequence focuses most of the pulse moments in the target depth range, in situations where two aquifers are separated by a relatively narrow aquitard, it is better able to resolve the individual aquifers than the traditional pulses. Optimum pulse moments improve the SNR by enhancing the signal amplitude, compared with various filtering methods, and obtain a better detection effect. This kind of pulse sequence can be used as an alternative pulse sequence form of the SNMR method.  相似文献   

Role of reservoir regulation and groundwater feedback in a simulated ground-soil-vegetation continuum: A long-term regional scale analysis     

Jianhui Wei  Ningpeng Dong  Benjamin Fersch  Joël Arnault  Sven Wagner  Patrick Laux  Zhenyu Zhang  Qianya Yang  Chuanguo Yang  Shasha Shang  Lu Gao  Zhongbo Yu  Harald Kunstmann 《水文研究》2021,35(8):e14341

The regional terrestrial water cycle is strongly altered by human activities. Among them, reservoir regulation is a way to spatially and temporally allocate water resources in a basin for multi-purposes. However, it is still not sufficiently understood how reservoir regulation modifies the regional terrestrial- and subsequently, the atmospheric water cycle. To address this question, the representation of reservoir regulation into the terrestrial component of fully coupled regional Earth system models is required. In this study, an existing process-based reservoir network module is implemented into NOAH-HMS, that is, the terrestrial component of an atmospheric–hydrologic modelling system, namely, the WRF-HMS. It allows to quantitatively differentiate role of reservoir regulation and of groundwater feedback in a simulated ground-soil-vegetation continuum. Our study focuses on the Poyang Lake basin, where the largest freshwater lake of China and reservoirs of different sizes are located. As compared to streamflow observations, the newly extended NOAH-HMS slightly improves the streamflow and streamflow duration curves simulation for the Poyang Lake basin for the period 1979–1986. The inclusion of reservoir regulation leads to major changes in the simulated groundwater recharges and evaporation from reservoirs at local scale, but has minor effects on the simulated soil moisture and surface runoff at basin scale. The performed groundwater feedback sensitivity analysis shows that the strength of the groundwater feedback is not altered by the consideration of reservoir regulation. Furthermore, both reservoir regulation and groundwater feedback modify the partitioning of the simulated evapotranspiration, thus affecting the atmospheric water cycle in the Poyang Lake region. This finding motivates future research with our extended fully coupled atmospheric–hydrologic modelling system by the community.  相似文献   

下扬子地区“三气一油”钻探发现及成藏地质条件——以皖南港地1井钻探发现为例   总被引：1，自引：0，他引：1  

石刚  徐振宇  郑红军  殷启春  滕龙  周道容  方朝刚  邵威  王佳龙  黄正清 《地质通报》2019,38(9):1564-1570

下扬子地区经历了多期构造运动,地质条件复杂,对油气保存条件产生了重要影响。页岩油气具有自生自储的特性,与常规油气相比,对保存条件的要求较低,在下扬子地区具备形成页岩油气藏的潜力。通过港地1井钻探,在下扬子地区二叠系大隆组和龙潭组获得了页岩油、页岩气、煤层气和致密砂岩气"三气一油"的发现,与常规油气"上气下油"不同,港地1井油气呈现"上油下气"式非常规油气储集方式。大隆组富有机质页岩厚度约70m,地层倾角10°～20°,现场解吸获取的页岩气样品甲烷含量达80%,有机质丰度为1.9%～2.3%,平均值约2.0%,有机质成熟度(Ro)为1%～1.25%,平均值约1.2%,具备生成页岩油气的良好基础。基于港地1井的钻探发现,认为下扬子地区构造运动影响弱、盆地规模小、保存条件好的"小而整"的坳陷或盆地具备形成页岩油气藏的地质条件。  相似文献   

From micro scale to boundary value problem: using a micromechanically based model     

Xiong  Hao  Nicot  François  Yin  Zhenyu 《Acta Geotechnica》2019,14(5):1307-1323

Acta Geotechnica - A 3D multi-scale approach is presented to investigate the mechanical behavior of a macroscopic specimen consisting of a granular assembly, as a boundary value problem. The core...  相似文献   

云南地区GPS基准站噪声模型分析          下载免费PDF全文

管雅慧  王坦  胡顺强  杨振宇 《全球定位系统》2020,45(2):68-73

以云南地区陆态网27个全球定位系统(GPS)基准站在2011-2017年不同时间跨度的观测数据为例,使用赤池信息量和贝叶斯信息量估计准则(AIC/BIC)对解算结果进行分析,从而确定其最优有色噪声模型.结果表明,不同时间跨度基准站各坐标分量上噪声特性主要体现为白+闪烁噪声(WN+FN)、幂律噪声(PL)模型组合.部分基准站在北向和垂向的最优噪声模型会随着观测时间的累积而改变,PL模型所占比例有所下降,WN+FN模型所占比例有所上升.当时间跨度大于5 a时,基准站噪声模型的稳定性显著提高.随着坐标时间序列积累时长的增加,未知噪声分量出现的可能性也相应提高.  相似文献   

深海海底光缆敷设施工余量控制的原理和控制软件的应用          下载免费PDF全文

江伟  邵振宇  栗之炜 《海洋开发与管理》2018,35(8):90-94

为解决深海有中继海底光缆项目技术难题,中国海底电缆建设有限公司开发了海底光缆敷设施工控制软件,填补我国相关领域的空白。文章介绍海底光缆敷设施工余量控制的原理和控制软件的操作流程:海底光缆余量包括区域余量、底部余量和释放余量,余量控制是海底光缆敷设施工中最关键的核心技术环节,应用控制软件可极大地降低计算量和提高计算精确度,并可通过在施工中不断调整计划,从而极大地提高施工质量,具有传统人工计算不可比拟的优势。  相似文献   

2016年春季浙江中部海域温、盐、密度的断面分布特征     

Yang Longqi  Chen Zhaozhang  Sun Zhenyu  Hu Jianyu 《海洋学报(英文版)》2019,38(4):175-182

厦门大学海洋与地球学院，近海海洋环境科学国家重点实验室。摘要：本文通过分析2016年春季航次在浙江中部海域3条断面的观测资料，结果表明：（1）在断面的10~25米层左右观测到了"中层冷水"现象以及在上层观测到微弱的上升流；（2）在浙江中部海域的上层观测到较弱的上升流；（3）春季，在浙江中部海域观测到了丰富的温跃层、逆温跃层以及盐跃层现象。（4）台湾暖流水向上爬坡对跃层的变化有一定的影响，使得跃层厚度变小，跃层强度加强，但是强度并不足以冲破跃层到达表层。  相似文献   

对PCM编码式GPS站点布设模式的评价和改进     

邹镇宇  江在森  崔月菊  刘月  刘晓霞 《大地测量与地球动力学》2020,40(4):376-380

本文主要对PCM编码式的布设模式进行分析和改进,介绍PCM编码式和闭锁深度倍数式2种站点布设模式,然后在最小有效距离（MED）为6.31倍断层闭锁深度的情况下,通过精度评价方法对比2种布设模式的结果,发现二者相差不大。进一步研究MED的合理选择,结果表明,MED取20倍的闭锁深度比6.31倍的闭锁深度更为合理。在MED为20倍的情况下对比研究PCM编码式和常规闭锁深度倍数式布设模式的优劣,结果表明,PCM编码式的布设模式优于常规模式。将PCM编码式的布设模式应用于川滇地区的巧家-东川剖面进行检验,发现PCM编码式的结果优于目前站点分布得到的结果,说明合理的站点布设可得到精度更优的结果。本文研究对于断层形变监测中精确获取形变参数具有重要意义。  相似文献   

一种卫星EIRP自动测试方法     

闫振宇  郎宏山  刘爱民 《气象科技》2017,45(3):420-424

以往在测试EIRP值时一般采用人工测试的方法,这种测试模式不仅效率低,有时还会因人工操作影响测试结果准确性。本文提供了一种EIRP的自动化测试方法,通过一台上位机对相关设备进行自动数据采集并计算出卫星EIRP值,避免了传统测试方法的人工误差,具有高效性和实时性等特点。以FY3C532轨EIRP的测试为例,简要阐述这种自动化测试方法的测试过程。  相似文献   

基于Ripley’s K函数的南京市ATM网点空间分布模式研究   总被引：1，自引：0，他引：1  

王结臣  卢敏  苑振宇  芮一康  钱天陆 《地理科学》2016,36(12):1843-1849

运用Ripley’s K函数的相关理论,以南京市ATM网点为研究对象,分别从平面与网络空间两种视角,在中心城区范围与主城区范围两种空间尺度上,通过单变量\begin{array}{c}K\end{array}函数法分析ATM网点的分布模式,通过双变量\begin{array}{c}K\end{array}函数法分析ATM网点与地铁站点的空间关联情况,最后对计算结果进行评价与分析。研究表明,ATM网点在南京主城区与中心城区均呈现出较强的集聚状态;在一定的距离范围内,ATM网点与地铁站点之间也有较强的依赖关系。同时,对于沿着路网分布的地理空间点状对象而言,利用网络\begin{array}{c}K\end{array}函数法进行空间点模式分析比用平面\begin{array}{c}K\end{array}函数法更加符合实际情况。  相似文献