A critical state model for sands dependent on stress and density

An elastoplastic model for sands is presented in this paper, which can describe stress–strain behaviour dependent on mean effective stress level and void ratio. The main features of the proposed model are: (a) a new state parameter, which is dependent on the initial void ratio and initial mean stress, is proposed and applied to the yield function in order to predict the plastic deformation for very loose sands; and (b) another new state parameter, which is used to determine the peak strength and describe the critical state behaviour of sands during shearing, is proposed in order to predict simply negative/positive dilatancy and the hardening/softening behaviour of medium or dense sands. In addition, the proposed model can also predict the stress–strain behaviour of sands under three-dimensional stress conditions by using a transformed stress tensor instead of ordinary stress tensor. Copyright © 2004 John Wiley & Sons, Ltd.     

Spectrophotometry of comet Levy (1990c)

Two spectrophotometric scans of comet Levy (1990c) have been analysed to estimate Haser model column densities and production rates of CN andC ₂ molecules.     

Finite-element analysis of time-dependent large-deformation problems

An updated Lagrangian finite-element formulation has been developed for time-dependent problems of soil consolidation involving finite deformations. Large plastic strains as well as rotations occur in such problems and nominal stress measures are introduced in the formulation to redefine stresses. This leads to corrective terms for equilibrium and yield violations in addition to geometric stiffening terms in the governing integral equations. The soil is considered to be either a linear elastic or an elastoplastic, critical-state material. Some simple numerical examples are studied to validate the formulation, followed by a detailed analysis of the problem of penetration of a pile into soil. The results of this problem are viewed with emphasis on the physical interpretation and practical significance.     

桐柏─大别山北麓金矿带地质物化探找矿模型

从桐柏─大别山成矿带区域地质、地球物理、地球化学特征的研究入手，分析与金成矿有关的地层、构造、岩浆岩等控矿因素的地球物理场及地球化学特征；建立区域金矿找矿模型。     

洛坝铅锌矿床的构造演化分析

洛坝铅锌矿床位于黄诸关韧脆性变形带所波及的范围内,断裂、褶皱、劈理、节理等形态构造类型均很发育,经对小型构造的统计及应力场分析证明,矿区变形主要是在海西—印支期长期存在的南北向古应力场持续作用下形成的。     

Porphyroblast inclusion-trail orientation data: eppure non son girate*!

Extensive examination of large numbers of spatially orientated thin sections of orientated samples from orogens of all ages around the world has demonstrated that porphyroblasts do not rotate relative to geographical coordinates during highly non-coaxial ductile deformation of the matrix subsequent to their growth. This has been demonstrated for all tectonic environments so far investigated. The work also has provided new insights and data on metamorphic, structural and tectonic processes including: (1) the intimate control of deformation partitioning on metamorphic reactions; (2) solutions to the lack of correlation between lineations that indicate the direction of movement within thrusts and shear zones, and relative plate motion; and (3) a possible technique for determining the direction of relative plate motion that caused orogenesis in ancient orogens.     

描述地壳垂直运动过程的一种函数形式

本文在已有数据处理方法的基础上，利用近代数值逼近理论，给出了从时空域角度描述地壳垂直运动过程的一种具体的函数解析形式。最后给出了一个实际算例。     

The Siberian Solar Radio Telescope: the current state of the instrument,observations, and data

The Siberian Solar Radio Telescope (SSRT) is one of the world's largest solar radio heliographs. It commenced operation in 1983, and since then has undergone several upgrades. The operating frequency of the SSRT is 5.7 GHz. Since 1992 the instrument has had the capability to make one-dimensional scans with a high time resolution of 56 ms and an angular resolution of 15 arc sec. Making one of these scans now takes 14 ms. In 1996 the capability was added to make full, two-dimensional images of the solar disk. The SSRT is now capable of obtaining images with an angular resolution of 21 arc sec every 2 min. In this paper we describe the main features and operation of the instrument, particularly emphasizing issues pertaining to the imaging process and factors limiting data quality. Some of the data processing and analysis techniques are discussed. We present examples of full-disk solar images of the quiet Sun, recorded near solar activity minimum, and images of specific structures: plages, coronal bright points, filaments and prominences, and coronal holes. We also present some observations of dynamic phenomena, such as eruptive prominences and solar flares, which illustrate the high-time-resolution observations that can be done with this instrument. We compare SSRT observations at 5.7 GHz, including computed `light curves', both morphologically and quantatively, with observations made in other spectral domains, such as 17 GHz radio images, Hα filtergrams and magnetograms, extreme-ultraviolet and X-ray observations, and dynamic radio spectra.