中国中部地区TID激发源的统计分布

利用武汉电离层观象台1985-1990年间的高频多普勒台阵观测资料,采用射线追踪方法,对观测到的电离层重力波扰动（TID）进行了定源研究,从统计上分析了扰动源的地理分布、季节变化以及与地磁活动的关系．结果表明,中国中部上空TID的激发源主要出现在春夏季的四川盆地和冬半年的山口地区．扰动的激发可能与青藏高原地形隆起对这两个地区的气象活动的影响有关．此外,有少部分尺度较大的扰动出现在冬半年,它们可能来自极区．     

富油煤的油气资源属性与绿色低碳开发

格金干馏试验下的焦油产率作为评价富油煤的唯一指标受制于前期较少的勘探资料无法满足富油煤规模化精细评价要求。

基于二分类法提出利用真密度(ρ)和自然伽马(GR)判识富油煤的最佳阈值,并阐释富油煤具有显著岩石物理参数响应的内在机理。

研究表明：不同变质程度煤不具有统一的判识阈值,其中长焰煤类富油煤最佳判识阈值为,原煤真密度小于1.41 g/cm³、GR<80 API,判识正确率达81.82%。上述富油煤的地球物理测井参数响应受控于无机和有机组分条件,其中与焦油产率呈负相关性的灰分产率是影响煤体真密度的主要因素,灰成分(Al₂O₃+SiO₂)所指示的黏土矿物含量对GR值影响显著;而对焦油产率起决定作用的显微组分则同样对原煤真密度变化具有一定影响。从分子尺度,干燥无灰基状态下的真密度(ρ_daf)越小,煤脂肪结构越丰富、越有利于热解产生焦油;反之则芳香结构含量越高、越不利于热解形成焦油。总体而言,多种因素耦合作用使得煤体真密度与焦油产率呈现良好的负相关性。上述认识为基于地球物理测井参数评价富油煤提供了理论指导。

     

Sampling for isotopic responses in surface waters

This paper considers situations in which stable isotopes may be used as natural tracers of precipitation through to surface waters. Two aspects affecting the applicability of the technique are highlighted: first, the variance through time of isotope concentrations in precipitation, i.e. the isotope input signal, and second, the attenuation or damping of this signal during the transmission of water downwards through the hydrological system. Both factors affect the likelihood of obtaining an isotope response, i.e. a variation of isotope concentrations in a surface water which may be related to variations in the precipitation input. Analysis of precipitation over the Malham area, U.K., reveals large isotopic variations through time. These variations, however, are only poorly correlated with meteorological variables (temperature, precipitation amount, and air mass type). Snowmelt and occluded frontal rainfall are suggested as providing the most reliable ‘spikes’ for an isotopic response at the output in tracing studies. In most hydrological systems, a high degree of signal attenuation is noted. In the Malham area of karst, 57 per cent of the total range of input variation was lost in surface waters, whilst 74 per cent was lost in mobile soil moisture. An isotopic response can only reasonably be expected in a system with rapid throughput, where there is little opportunity for mixing and storage of waters.     

Inversion for interface structure using teleseismic traveltime residuals

An inversion method is presented for the reconstruction of interface geometry between two or more crustal layers from teleseismic traveltime residuals. The method is applied to 2-D models consisting of continuous interfaces separating constant-velocity layers. The forward problem of determining ray paths and traveltimes between incident wave fronts below the structure and receivers located on the Earth's surface is solved by an efficient and robust shooting method. A conjugate gradient method is employed to solve the inverse problem of minimizing a least-squares type objective function based on the difference between observed and calculated traveltimes. Teleseismic data do not accurately constrain average vertical structure, so a priori information in the form of layer velocities and average layer thicknesses is required. Synthetic tests show that the method can be used to reconstruct interface geometry accurately, even in the presence of data noise. Tests also show that, if layer velocities and initial interface positions are poorly chosen, lateral structure is still recoverable. The inversion method was applied to previously published teleseismic data recorded by an in-line array of portable seismographs that traversed the northern margin of the Musgrave Block, central Australia. The solution based on interface parametrization is consistent with models given by other studies that used the same data but different methods, most notably the standard tomographic approach that inverts for velocity rather than interface structure.     

On the use of COBE results

The aim of this brief report is to find a lower limit of the Hubble parameter using the COBE's detected fluctuations in the temperature of the CMBR.     

利用孢粉分析寻找地下水资源的构想

通过孢粉分析手段，利用孢粉组合及其孢粉学资料，能进行划分，对比地层和确守质时代，进面是恢复古植被和古环境，为寻找到地下水资源提供参考参考依据，并将孢粉找民水文地质勘探等密切配合，探索和寻求地下水的运移规律，从而为大力开发和利用地下水，作了大胆构要卢。     

Image‐ray Tomography

Seismic tomography is a well‐established approach to invert smooth macro‐velocity models from kinematic parameters, such as traveltimes and their derivatives, which can be directly estimated from data. Tomographic methods differ more with respect to data domains than in the specifications of inverse‐problem solving schemes. Typical examples are stereotomography, which is applied to prestack data and Normal‐Incidence‐Point‐wave tomography, which is applied to common midpoint stacked data. One of the main challenges within the tomographic approach is the reliable estimation of the kinematic attributes from the data that are used in the inversion process. Estimations in the prestack domain (weak and noisy signals), as well as in the post‐stack domain (occurrence of triplications and diffractions leading to numerous conflicting dip situations) may lead to parameter inaccuracies that will adversely impact the resulting velocity models. To overcome the above limitations, a new tomographic procedure applied in the time‐migrated domain is proposed. We call this method Image‐Incident‐Point‐wave tomography. The new scheme can be seen as an alternative to Normal‐Incidence‐Point‐wave tomography. The latter method is based on traveltime attributes associated with normal rays, whereas the Image‐Incidence‐Point‐wave technique is based on the corresponding quantities for the image rays. Compared to Normal‐Incidence‐Point‐wave tomography the proposed method eases the selection of the tomography attributes, which is shown by synthetic and field data examples. Moreover, the method provides a direct way to convert time‐migration velocities into depth‐migration velocities without the need of any Dix‐style inversion.