Gravimetric determination of an intrusive complex under the Island of Faial (Azores): some methodological improvements

We present some improvements of a gravity inversion method to determine the geometry of the anomalous bodies for priori density contrasts. The 3-D method is based on an exploratory process applied, not for the global model, but for the steps of a growth approach. The (positive and/or negative) anomalous structure is described by successive aggregation of cells, while its corresponding gravity field remains nearly proportional to the observed one. Moreover, a simple (e.g. linear) regional trend can be simultaneously adjusted. The corresponding program is applied to new gravity data on the volcanic island of Faial (Azores archipelago). The inversion approach shows a subsurface anomalous structure for the island, the main feature being an elongated high-density body. The body is interpreted as a compact sheeted dyke swarm, emplaced along Faial-Pico Fracture Zone, a leaky transform structure that forms the current boundary between Eurasian and African plates in the Azores area. The new results in this paper are (1) a Bouguer gravity anomaly map, (2) several improvements in the inversion process (robust process, optimal balance fitness/model magnitude), (3) a new gravimetric method for estimating the mean terrain density, (4) a 3-D model for subsurface mass anomalies in Faial and (5) some interpretative conclusions about a main intrusive complex detected under the island as a wall-like structure extending from a depth of 0.5 to 6 km b.s.l., with a N100°E trend and corresponding to an early fissural volcanic episode controlled by the regional tectonics.     

河南省水资源状况及对策研究

本文论述了河南省水资源分布状况及开发利用现状，依据地下水动态长期监测资料，指出了地下水开采利用中出现的一些环境水文地质问题，并提出了相应的对策。     

’97青海地勘工作成绩与问题

作者通过详细总结和充分肯定青海地勘局1997年地质矿产工作和矿产开发工作成绩的基础上,指出了工作中存在的诸多问题。最后,提出了解决这些问题的方法和措施。     

Sequential integrated inversion of refraction and wide-angle reflection traveltimes and gravity data for two-dimensional velocity structures

A new algorithm is presented for the integrated 2-D inversion of seismic traveltime and gravity data. The algorithm adopts the 'maximum likelihood' regularization scheme. We construct a 'probability density function' which includes three kinds of information: information derived from gravity measurements; information derived from the seismic traveltime inversion procedure applied to the model; and information on the physical correlation among the density and the velocity parameters. We assume a linear relation between density and velocity, which can be node-dependent; that is, we can choose different relationships for different parts of the velocity–density grid. In addition, our procedure allows us to consider a covariance matrix related to the error propagation in linking density to velocity. We use seismic data to estimate starting velocity values and the position of boundary nodes. Subsequently, the sequential integrated inversion (SII) optimizes the layer velocities and densities for our models. The procedure is applicable, as an additional step, to any type of seismic tomographic inversion.
We illustrate the method by comparing the velocity models recovered from a standard seismic traveltime inversion with those retrieved using our algorithm. The inversion of synthetic data calculated for a 2-D isotropic, laterally inhomogeneous model shows the stability and accuracy of this procedure, demonstrates the improvements to the recovery of true velocity anomalies, and proves that this technique can efficiently overcome some of the limitations of both gravity and seismic traveltime inversions, when they are used independently.
An interpretation of field data from the 1994 Vesuvius test experiment is also presented. At depths down to 4.5 km, the model retrieved after a SII shows a more detailed structure than the model obtained from an interpretation of seismic traveltime only, and yields additional information for a further study of the area.     

基于CE-1数据的数字月海分形刻画及其动力学意义

月海是月球表面的主要地理单元。对月海地貌特征的研究能够认识月表起伏及其动力学成因。依据CE-1 影像图和全月球数字高程模型数据,提取了南北半球不同纬度地区、不同填充岩性的典型月海范围,运用盒维数法、立方体覆盖法和多重分形q-Dq语言对月海边界及其地形表面的地貌特征进行了线和面的描述和研究。结果表明：① 分形方法可以有效地描述月球地貌的复杂程度。月海边界的分维值介于1.065~1.100 之间,平均值为1.086,标准差为0.014,在双对数坐标下5 个月海区边界复杂度拟合的直线都近似平行。② 月海地形表面的分维值介于2.704~2.852 之间,5 个月海地形表面的分维值标准差为0.051,ln δ -lnN（δ）图也近似平行,但截距的离散程度相较于月海边界的高。③ 月海地貌多重分析的q-Dq曲线图总体呈现非递增趋势,Dq值在q=-10 和q=0 时基本达到饱和,但差异较小。④ 从线、面单分形以及多重分形可见,5 个月海均具有分形特征,但彼此之间差异较小。其动力学意义在于它们在形成之后,内动力作用基本停止或很小,与分形特征基本一致;而外力主要由陨石撞击作用少量地改变着月表的面貌,导致在分形特征上表现出差异性。     

About the Hill stability of extrasolar planets in stellar binary systems

We use a three dimensional generalization of Szebehely’s invariant relation obtained by us (Makó and Szenkovits, Celest. Mech. Dyn. Astron. 90, 51, 2004) in the elliptic restricted three-body problem, to establish more accurate criterion of the Hill stability. By using this criterion, the Hill stability of four extrasolar planets (γ Cephei Ab, Gliese 86 Ab, HD 41004 Ab and HD 41004 Bb) is investigated.     

高校校办企业财务管理问题的思考

针对高校校办企业的主要特点．分析了高校校办企业财务管理上存在的激励制度扭曲，多头管理、条块分割以及财务制度不健全等问题，并提出了强化会计制度基础建设工作、优化财务管理体制、实行会计委派制、加强财会人员的业务培训以及规范运作防范风险等相应的对策加强高校校办企业财务管理。     

Chaotic Motions in The Field of Two Fixed Black Holes

We study the chaotic motions in the field of two fixed black holes M₁, M₂ by calculating (a) the asymptotic curves from the main unstable periodic orbits, (b) the asymptotic orbits, with particular emphasis οn the homoclinic and heteroclinic orbits, and (c) the basins of attraction of the two black holes. The orbits falling on M₁and M₂form fractal sets. The asymptotic curves consist of many arcs, separated by gaps. Every gap contains orbits falling on a black hole. The sizes of various arcs decrease as the mass ofM₁ increases. The basins of attraction of the black holes M₁, M₂consist of large compact regions and of thin filaments. The relative area of the basin M₂ tends to 100 as M₁ → 0, and it decreases as M₁ increases. The total area of the basins is found analytically, while the relative area of the basin M₂ is given by an empirical formula. Further empirical formulae give the exponential decrease of the number of asymptotic orbits that have not yet reached a black hole after n iterations.     

Numerical Simulations of Free Convection about a Vertical Flat Plate Embedded in a Porous Medium

We consider the free convection about a vertical flat plate embedded in a porous medium within the framework of a boundary layer approximation. In some cases, similarity solutions arise in the modelization of such phenomena, allowing a reduction of the dimension of the problem. We suggest two complementary and rather simple numerical methods to compute such solutions. When possible, the numerical analysis for the two discretizations is performed and convergence results are given. Numerical experiments with a physical model are presented to confirm the efficiency of both approaches.