重力斜导数方法在时间域中的理论模型与研究

Miller和Singh在1994年首次提出了斜导数(Tilt梯度)的定义,J.Derek Fairhead和Chris M.Green又于2004年在斜导数的基础上提出了Tilt梯度水平导数的概念。国内学者已对斜导数及斜导数水平导数展开研究,设定了多体模型、无限延伸倾斜脉模型、有限延伸倾斜台阶模型及埋深相同无限延伸垂直厚板及薄板模型,得出一些结论。针对一些地质体产状的判断,提出非绝对值斜导数水平导数的新概念,并应用于理论模型中验证,得出正确的结论。在上述理论模型基础上补充了断层模型和无限延伸倾斜台阶模型,应用非绝对值水平导数的理论解释地质体的产状,并对上述模型提出新的观点和看法。     

新产业区的形成机制及其与传统空间组织理论的关系

在新产业区概念和特征进行概括的基础上,归纳了产业区发展的一般过程,并重点对新产业区的形成机制及所具有的优势进行了探讨。地方化产业群及区域创新网络的形成是新产业区成熟的标志,知识外溢、经济外部性导致的收益递增,以及基于密切的内部联系引来交易成本的降低使新产业区获得了强大的经济竞争优势,新产业区的空间组织形式所具有的网络效应、创新效应和企业与地方文化的良好融合是经济竞争优势的根本。最后,对新产业区理论和传统的空间组织理论之间的关系进行了对比分析,总结了二者的之间的异同。     

Détermination expérimentale des paramètres équivalents d'un milieu poreux hétérogène en écoulements uniforme ou radial

Tracer tests are carried out in a heterogeneous porous medium that has a 3D correlated random distribution of the permeabilities. The fitting of numerical models provides the values of equivalent permeability and macrodispersivity characterizing a 2D homogeneous horizontal medium. Different flow configurations are studied: uniform, radial and pump and treat (doublet). The fitted parameter sets are independent of the flow type, except for the doublet. They are greater than the values predicted by stochastic theories, due to the small number of correlation lengths explored by the tracer and the limited extension of the experimental set-up. To cite this article: C. Danquigny, P. Ackerer, C. R. Geoscience 337 (2005).     

Improvements of Planetary Theories Over 6000 Years

Taking advantage of the JPL Long Ephemeris DE406 and of the semi-analytical solution for the planetary motions VSOP87, we make an approximation of the differences JPL–VSOP. The form of the approximation (arguments and Poisson expansions) is analogous to the time series of the theory. We improve the planetary solution VSOP87 in two directions: a better fit of the integration constants via the highly precise observations used in DE406 and an extension of the length of validity covering the 6000 years of the source ephemeris. Over an interval of 2000 years, we achieve on the mean longitudes (test variables) a precision better than 0.005 for inner planets and 0.015 for outer ones. On the longest time interval covering 6000 years the precision is better than 0.03 for inner planets and 1.2 for outer ones.     

洪水演算理论与计算方法的若干进展与评论

从洪水波运动的小扰动分析、水力学洪水演算方法及新技术在洪水演算中的应用等方面,总结了近20年来国内外洪水演算理论与计算方法研究的若干进展,并作了简要的评论.     

Dynamics of a satellite orbiting a planet with an inhomogeneous gravitational field

We study the dynamics of a satellite (artificial or natural) orbiting an Earth-like planet at low altitude from an analytical point of view. The perturbation considered takes into account the gravity attraction of the planet and in particular it is caused by its inhomogeneous potential. We begin by truncating the equations of motion at second order, that is, incorporating the zonal and the tesseral harmonics up to order two. The system is formulated as an autonomous Hamiltonian and has three degrees of freedom. After three successive Lie transformations, the system is normalised with respect to two angular co-ordinates up to order five in a suitable small parameter given by the quotient between the angular velocity of the planet and the mean motion of the satellite. Our treatment is free of power expansions of the eccentricity and of truncated Fourier series in the anomalies. Once these transformations are performed, the truncated Hamiltonian defines a system of one degree of freedom which is rewritten as a function of two variables which generate a phase space which takes into account all of the symmetries of the problem. Next an analysis of the system is achieved obtaining up to six relative equilibria and three types of bifurcations. The connection with the original system is established concluding the existence of various families of invariant 3-tori of it, as well as quasiperiodic and periodic trajectories. This is achieved by using KAM theory techniques.     

Quadrupolar gravitational radiation as a test-bed for f(R)-gravity

The debate concerning the viability of f(R)-gravity as a natural extension of General Relativity could be realistically addressed by using results coming from binary pulsars like PSR 1913 + 16. To this end, we develop a quadrupolar approach to the gravitational radiation for a class of analytic f(R)-models. We show that experimental results are compatible with a consistent range of f(R)-models. This means that f(R)-gravity is not ruled out by the observations and gravitational radiation (in strong field regime) could be a test-bed for such theories.     

Wall effect of underwater explosion load based on wave motion theories

Owing to the existence of the flow field boundary, the shock wave load near the boundary is different from the freefield shock wave load. In the present paper, the hull plate load subjected to underwater shock wave is investigated based onwave motion theories; in addition, the experimental study of the hull plate load is carried out. According to the theoreticalanalysis of the hull plate pressure, we find that the hull plate pressure oscillates repeatedly and decays rapidly with timepassing, the maximum hull plate pressure is 2/（1＋n） times the maximum free field pressure, where n is the ratio ofimpedance, and the impulse is much smaller than the free field impulse. Compared with the experimental study, thetheoretical results agree well with the experimental data.     

地震动力分析的经典方法与现代计算技术

回顾了体系地震动力分析的历史过程，并对地震动力分析的传统理论方法、近似方法和现代计算技术从新的角度加以阐述，同时给出体系地震动力分析的应用前景，以促进经典的传统理论方法、近似方法和现代计算技术的综合和在实际工程中的应用，形成系统而完整的地震动力分析体系。