指出了在当今世界能够进行直接找水的地球物理方法即为核磁共振-Nuclear Magnetic Resonance,简称NMR技术。从核磁共振在具体的地下水探测工作当中的应用状况入手,对核磁共振找水技术运用原理、工作方式、应用环境及资料整理进行了分析...指出了在当今世界能够进行直接找水的地球物理方法即为核磁共振-Nuclear Magnetic Resonance,简称NMR技术。从核磁共振在具体的地下水探测工作当中的应用状况入手,对核磁共振找水技术运用原理、工作方式、应用环境及资料整理进行了分析,总结了实际多年来的工作经验,望能够对于核磁共振在复杂条件地下水探测中的大范围推广及应用提供参考。展开更多
地面磁共振(Surface Nuclear Magnetic Resonance,SNMR)技术作为一种非侵害性可直接探测地下水的地球物理方法,其理论和技术在近年来得到了快速发展。为了给国内研究者提供一个SNMR探水理论和仪器软硬件技术的全面参考,本文综述了各国...地面磁共振(Surface Nuclear Magnetic Resonance,SNMR)技术作为一种非侵害性可直接探测地下水的地球物理方法,其理论和技术在近年来得到了快速发展。为了给国内研究者提供一个SNMR探水理论和仪器软硬件技术的全面参考,本文综述了各国研制的代表性SNMR探水仪性能以及特点,讨论了SNMR探水理论和正反演问题;并以地面磁共振探水仪为例,详细介绍了SNMR探水仪的软硬件关键技术,包括大功率发射技术、弱信号检测技术、数字信号处理技术。同时,本文也总结了近几年SNMR探水技术的新进展,并指出了该方法的发展趋势和目前仍然存在的技术问题,包括最大探测深度、信噪比、死区时间、测量效率、反演稳定性等问题,为SNMR技术在未来的进一步发展提供思路。展开更多
近20多年来,用核磁共振(Nuclear Magnetic Resonance,NMR)方法形成的一种直接非侵害性的探测地下水的地球物理新技术,与传统的地球物理探测地下水的方法相比具有高分辨力、高效率、信息量丰富和解的唯一性等优点,是一种很有发展前景的...近20多年来,用核磁共振(Nuclear Magnetic Resonance,NMR)方法形成的一种直接非侵害性的探测地下水的地球物理新技术,与传统的地球物理探测地下水的方法相比具有高分辨力、高效率、信息量丰富和解的唯一性等优点,是一种很有发展前景的找水方法技术.我国的水资源短缺,对地下水资源的勘探、开发与利用十分重视,已将核磁共振找水技术研究列入国家十一五科技支撑计划.本文在广泛收集迄今为止的国内外大量资料的基础上,并根据作者近年来有关核磁共振找水技术的研究经历,综述了核磁共振找水技术的发展历史、现状和发展趋势,以推进我国核磁共振找水技术的发展.展开更多
Under suitable conditions of tidal current and wind, underwater topography can be detected by synthetic aperture radar (SAR) indirectly. Underwater topography SAR imaging includes three physical processes: radar ocean...Under suitable conditions of tidal current and wind, underwater topography can be detected by synthetic aperture radar (SAR) indirectly. Underwater topography SAR imaging includes three physical processes: radar ocean surface backscattering, the modulation of sea surface short wave spectrum by the variations in sea surface currents, and the modulation of sea surface currents by the underwater topography. The first process is described usually by Bragg scattering theory because the incident angle of SAR is always between 20°-70°. The second process is described by the action balance equation. The third process is described by an ocean hydrodynamic model. Based on the SAR imaging mechanism for underwater topography, an underwater topography SAR detection model and a simplified method for its calculation are introduced. In the detection model, a two-dimensional hydrodynamic model – the shallow water model is used to describe the motion of tidal current. Due to the difficulty of determining the expression of SAR backscattering cross section in which some terms can not be determined, the backscattering cross section of SAR image used in the underwater topography SAR detection is pro-processed by the simulated SAR image of the coarse-grid water depth to simplify the calculation. Taiwan Shoal, located at the southwest outlet of Taiwan Strait, is selected as an evaluation area for this technique due to the occurrence of hundreds of sand waves. The underwater topography of Taiwan Shoal was detected by two scenes of ERS-2 SAR images which were acquired on 9 January 2000 and 6 June 2004. The detection results are compared with in situ measured water depths for three profiles. The average absolute and relative errors of the best detection result are 2.23 m and 7.5 %, respectively. These show that the detection model and the simplified method introduced in the paper is feasible.展开更多
文摘指出了在当今世界能够进行直接找水的地球物理方法即为核磁共振-Nuclear Magnetic Resonance,简称NMR技术。从核磁共振在具体的地下水探测工作当中的应用状况入手,对核磁共振找水技术运用原理、工作方式、应用环境及资料整理进行了分析,总结了实际多年来的工作经验,望能够对于核磁共振在复杂条件地下水探测中的大范围推广及应用提供参考。
文摘地面磁共振(Surface Nuclear Magnetic Resonance,SNMR)技术作为一种非侵害性可直接探测地下水的地球物理方法,其理论和技术在近年来得到了快速发展。为了给国内研究者提供一个SNMR探水理论和仪器软硬件技术的全面参考,本文综述了各国研制的代表性SNMR探水仪性能以及特点,讨论了SNMR探水理论和正反演问题;并以地面磁共振探水仪为例,详细介绍了SNMR探水仪的软硬件关键技术,包括大功率发射技术、弱信号检测技术、数字信号处理技术。同时,本文也总结了近几年SNMR探水技术的新进展,并指出了该方法的发展趋势和目前仍然存在的技术问题,包括最大探测深度、信噪比、死区时间、测量效率、反演稳定性等问题,为SNMR技术在未来的进一步发展提供思路。
文摘近20多年来,用核磁共振(Nuclear Magnetic Resonance,NMR)方法形成的一种直接非侵害性的探测地下水的地球物理新技术,与传统的地球物理探测地下水的方法相比具有高分辨力、高效率、信息量丰富和解的唯一性等优点,是一种很有发展前景的找水方法技术.我国的水资源短缺,对地下水资源的勘探、开发与利用十分重视,已将核磁共振找水技术研究列入国家十一五科技支撑计划.本文在广泛收集迄今为止的国内外大量资料的基础上,并根据作者近年来有关核磁共振找水技术的研究经历,综述了核磁共振找水技术的发展历史、现状和发展趋势,以推进我国核磁共振找水技术的发展.
基金Supported by National Natural Science Foundation of China (Nos. 60672159 & 60890075)the State Oceanic Administration Marine Science Foundation for Youths (No.2009421)+1 种基金the Special Funds for Marine Commonweal Research (No. 200705027)the Special Funds for Basic Scientific Research Project of the First Institute of Oceanography, S.O.A (No. 2008T29)
文摘Under suitable conditions of tidal current and wind, underwater topography can be detected by synthetic aperture radar (SAR) indirectly. Underwater topography SAR imaging includes three physical processes: radar ocean surface backscattering, the modulation of sea surface short wave spectrum by the variations in sea surface currents, and the modulation of sea surface currents by the underwater topography. The first process is described usually by Bragg scattering theory because the incident angle of SAR is always between 20°-70°. The second process is described by the action balance equation. The third process is described by an ocean hydrodynamic model. Based on the SAR imaging mechanism for underwater topography, an underwater topography SAR detection model and a simplified method for its calculation are introduced. In the detection model, a two-dimensional hydrodynamic model – the shallow water model is used to describe the motion of tidal current. Due to the difficulty of determining the expression of SAR backscattering cross section in which some terms can not be determined, the backscattering cross section of SAR image used in the underwater topography SAR detection is pro-processed by the simulated SAR image of the coarse-grid water depth to simplify the calculation. Taiwan Shoal, located at the southwest outlet of Taiwan Strait, is selected as an evaluation area for this technique due to the occurrence of hundreds of sand waves. The underwater topography of Taiwan Shoal was detected by two scenes of ERS-2 SAR images which were acquired on 9 January 2000 and 6 June 2004. The detection results are compared with in situ measured water depths for three profiles. The average absolute and relative errors of the best detection result are 2.23 m and 7.5 %, respectively. These show that the detection model and the simplified method introduced in the paper is feasible.
