IMPROVED PHASE-ELLIPSE METHOD FOR IN SITU GEOPHONE CALIBRATION*

For amplitude and phase response calibration of moving-coil electromagnetic geophones two parameters are needed, namely, the geophone natural frequency, f₀, and the geophone upper resonance frequency f_u. The phase-ellipse method is commonly used for the in situ determination of these parameters. For a given signal-to-noise ratio, the precision of the measurement off₀ andf_u depends on the phase sensitivity, f(δφ/δf) For some commercial geophones f(δφ/δf) atf_u can be an order of magnitude less than the sensitivity atf₀. In this paper we present an improved phase-ellipse method with increased precision. Compared to measurements made with the existing phase-ellipse methods, our method shows a 6- and 3-fold improvement in the precision, respectively, on measurements of f₀ andf_u on a commercial geophone.     

Application of improved discrepancy principle in inversion of atmosphere infrared remote sensing

With the use of techniques in nonlinear problems, the IDP (improved discrepancy principle) method has been proposed and applied to the optimal smooth factor (parameterγ) in the inversion process of atmosphere profiles from satellite observation. This method has also been used to inverse atmospheric parameters from the observation of new generation geostationary operational environmental satellite (GOES-8). Results show that this method is more accurate than that in use.     

Sr isotope evolution during chemical weathering of granites -- impact of relative weathering rates of minerals

The Sr isotopic systematics in the weathering profiles of biotite granite and granite porphyry in southern Jiangxi Province were investigated. The results showed that during the chemical weathering of granites, remarked fractionation occurred between Rb and Sr. During the early stages of chemical weathering of granites, the released Sr/Si and Sr/Ca ratios are larger than those of the parent rocks, and the leaching rate of Sr is higher than those of Si, Ca, K, Rb, etc. Dynamic variations in relative weathering rates of the main Sr-contributing minerals led to fluctuation with time in 87Sr/86Sr ratios of inherent and released Sr in the weathering crust of granite. Successive weathering of biotite, plagioclase and K-feldspar made 87Sr/86Sr ratios in the weathering residues show such a fluctuation trend as to decrease first, increase, and then decrease again till they maintain stable. This work further indicates that when Sr isotopes are used to trace biogeochemical processes on both the catchment and global scales, one must seriously take account of the prefer-ential release of Sr from dissolving solid phase and the fluctuation of 87Sr/86Sr ratios caused by the variations of relative weathering rates of Sr-contributing minerals.     

PREDICTION OF LOCATION OF HIDDEN ORE DEPOSITS IN THE AGED ORE FIELDS:AN EXAMPLE FROM FENGHUANGSHAN ORE FIELD,TONGLING,CHINA

This paper discusses the strategy for successfully predicting the location of potential hidden ore bodies in aged ore field,and presents the result of location prediction of hidden ore bodies in Fenghuangshan ore field,Tongling.Innovative conceptual targeting procedures based on a genetic understanding of mineralization systems,carefully geological investigation and correct deduction,together with new geochemical and geophysical technology and integrating of comprehensive information are all very important for the successful prediction.In the aged Fenghuangshan ore field,through researching by application of the metallogenic theory of polygenetic compound ore deposits and triple-frequency induced polarization method and exploration tectono-geochemical method,we predicted location and quality of hidden ore bodies.According to the prediction,hidden high quality Cu-Au ore bodies of skarn type and porphyry type have been discovered.     

福州地铁二号线主要工程地质问题探讨

福州市地铁二号线是福州市轨道交通东西主轴线,沿线工程问题复杂,盾构施工条件困难,主要有孤石问题、过江的富水砂层及冲蚀深槽问题、过河的冒顶突水问题和软硬接触等。通过福州城市地质调查工作搜集的20余万个钻孔资料,标准化3000余个有效钻孔,补充以专项调查及少许钻探,总结孤石发育规律,分析孤石等主要工程地质问题的发育特征,推断它们可能出现的路段,指出它们可能给施工造成的危害,提出初步处理建议。同时,针对福州地区特有的有害气体、温泉等进行了补充说明,对规划线路优选具有重要的指导意义。同时,为详勘、施工前勘察奠定了一定的工作基础。     

黄河流域分布式水文模型初步研究与进展

结合国家重点基础研究规划项目"黄河流域水资源演化规律与可再生性维持机理"的研究,综述了黄河流域分布式水文模型研究的主要进展,包括分布式水文模型的特点和基本结构、分布式水文模型中的数字高程模型(DEM)和水文学基础、地理信息系统(GIS)和遥感(RS)在分布式水文模拟中的应用等方面的内容,对未来分布式水文模型的研究提出几点认识。     

激波在磁盔－电流片位场中的传播：（Ⅰ）激波与磁盔间的相互作用

利用新近获得的子午面磁盔－电流片背景太阳风稳态解,对激波从盔底沿电流片方向往外传播时与磁盔间的相互作用进行了数值模拟研究,重要新结果是：１．磁盔的存在使受扰介质速度跃变中央出现下凹,随着激波传出磁盔区并沿电流片方向传播,速度下凹逐渐减弱以致消失;２．激波将磁盔拉长并把盔顶的环形（垂直赤道面）磁场带到行星际空间,成为行星际磁场南向分量的来源之一;３．５个太阳半径（Ｒ⊙）内的磁盔部分将出现精细结构,沿盔外边界形成两条高速带,以及马蹄形密度（亮）环形结构等．这些结果表明,太阳附近高速等离子体与磁盔间存在重要的动力学相互作用过程,对行星际空间的太阳风三维结构有重要影响．     

贵州高速公路隧道工程施工质量管理技术探讨

根据国内外高速公路隧道工程施工质量存在的主要问题,结合贵州省近年来修建的几条高速公路隧道工程的实际情况,提出高速公路隧道工程施工质量管理技术问题。首先,需要对具体的隧道工程所存在的工程地质条件及施工中可能存在的工程地质问题进行详细分析;然后,有针对性地选择地质超前预报方法,实施综合地质超前预报;并根据隧道施工过程中揭露的不同工程地质问题和隧道监控量测数据,采取不同的施工措施;为了保障工程施工质量,需要有针对性地开展隧道超前支护及初期支护质量检测;在工程全部施工完毕,进行衬砌质量全面检测。分析认为,隧道工程施工质量管理是一个系统工程,需要采取点面结合、定性与定量相结合、宏观控制与细微管理相结合的多种方式。只有这样,才能将高速公路隧道工程施工质量及管理技术提升到新的高度。     

黄河流域水循环演变若干问题的研究

从若干方面的研究结果揭示了黄河流域水循环发生的巨大变化.水循环是水资源科学评价与合理开发利用的基本依据.水循环主要要素的变化取决于气候条件的变化与人类活动的影响.对前者宜采用适应性对策,在研究气候变化的基础上,分析水循环变动的规律并预测其趋势,制定相应的适应性措施;对于后者则应加强水资源开发利用的科学管理,以维持流域天然水资源的可更新(可再生)性.