四川螺髻山旅游资源及其开发战略研究

四川古冰川遗迹发育螺髻山是川西南的重要风景名胜区。以螺髻山为中心，周边旅游资源综合性强、类型多、品位高、功能齐全。本文从旅游资源、区位、社会环境等方面，系统分析开发螺髻山的优势条件和制约因素，论述其开发价值和可行性，提出了开发发展战略构思。     

常州地区地热资源开发条件分析

系统地介绍了常州地区地质特征，分析了常州地区地下热水形成和赋存的地质背景和条件，对开发该地区地热资源提出了建议。     

GPS在城市供水管网GIS中的应用

对GPS在城市供水管网地理信息系统应用中其控制网的布网方案、施测方法、平差计算及精度分析作了详细的介绍 ,同时对高程拟合解算作了必要说明以及对管线的动态施测作了介绍     

GIS环境下空间数据多尺度特征及其关键问题探讨

介绍了GIS环境下空间数据多尺度特征的基本概念，并对与空间数据多尺度表达相关的技术作了探讨，其中主要包括它们的最新研究进展、主要方法、存在的问题及应用前景。     

The Homogeneous Finite-Difference Formulation of the P-SV-Wave Equation of Motion

Two different approaches to finite-difference modeling of the elastodynamic equations have been used: the heterogeneous and the homogeneous. In the heterogeneous approach, boundary conditions at interfaces are treated implicitly; in the homogeneous, they are explicitly discretized. We present a homogeneous finite-difference scheme for the 2-D P-SV-wave case. This scheme represents a generalization of earlier such schemes, being able to model media with arbitrary non-uniformities, provided only that all interfaces are aligned with the numerical grid. We perform a detailed comparison of the generalized homogeneous scheme with the analogous heterogeneous scheme, and show the two schemes to be identical for media with a spatially constynt Poisson's ratio. For media where Poisson's ratio is spatially varying, the schemes differ by terms first-order in the spatial step size. However, a comparison of the numerical results produced by the two schemes shows that the resulting differences are negligible for a wide range of values of the Poisson's ratio contrast.     

Factors Controlling Seismic Susceptibility of the Sele Valley Slopes: The Case of the 1980 Irpinia Earthquake Re-Examined

Most of the documented slope failures triggered by the 1980 Irpinia earthquake (M_s 6.9) occurred in the upper Sele valley epicentral area (southern Italy). The early investigations revealed some puzzling characteristics of the slope failure distribution, i.e., (i) the higher landslide concentration on the valley slopes located farther away from the earthquake fault; (ii) the predominance of re-activations over first-time movements. The analyses of factors controlling the landslide concentrations indicates that the differences in hydrological setting and in slope were the two main causal factors whereas the seismic shaking, according to the radiation pattern modelling, could have been characterised by a relatively low rate of decrease across the valley. The aspect of the slopes did not play a significant role. The differences in groundwater conditions between the western and eastern valley sides were probably enhanced by the earthquake. In addition to the probable pore-water pressure rise, the seismic shaking caused large increases in the flow of springs draining the western aquifer, and this made the adjacent flysch slopes more prone to landsliding. Data from the available literature suggest that the effects of earthquake-induced groundwater release on seismic landslide distribution is especially important for normal-fault events. The Sele valley case also indicates that the slope of the pre-existing landslides is an important factor controlling their susceptibility to seismic re-activations.     

Magnetic and electric field observations during the 2000 activity of Miyake-jima volcano, Central Japan

Magnetic and electric field variations associated with the 2000 eruption of Miyake-jima volcano are summarized. For about 1 week prior to the July 8 phreatic explosion, significant changes in the total intensity were observed at a few stations, which indicated uprising of a demagnetized area from a depth of 2 km towards the summit: this non-magnetic source can be regarded as a vacant space itself. Electric and magnetic field variations were observed simultaneously associated with the tilt-step event, which was the abrupt (∼50 s) inflation at a few km depth within the volcano followed by gradual recovery (∼several hours). The electric field is ascribed to the electrokinetic effect most probably due to forced injection of fluids from the source, while the magnetic field to the piezomagnetic effect due to increased pressure. Large magnetic variations amounting to a few tens of nT were observed at several stations since July 8, and they turned almost flat after the August 18 largest eruption. Magnetic changes are explained mostly by the vanishing of magnetic mass in the summit and additionally by the thermal demagnetization at a rather shallow depth. A large increase in the self-potential by 130 mV was also observed near the summit caldera associated with the August 18 eruption, which suggests that the hydrothermal circulation system sustained within the volcano for the past more than 10 years was destroyed by this eruption.     

Discrete‐time variable structure control method for seismic‐excited building structures with time delay in control

The discrete‐time variable structure control method for seismically excited linear structures with time delay in control is investigated in this paper. The control system with time delay is first discretized and transformed into standard discrete form which contains no time delay in terms of the time delay being integer and non‐integer times of sampling period, respectively. Then the discrete switching surface is determined using ideal quasi‐sliding mode and discrete controller is designed using the discrete approach‐law reaching condition. The deduced controller and switching surface contain not only the current step of state feedback but also linear combination of some former steps of controls. Numerical simulations are illustrated to verify the feasibility and robustness of the proposed control method. Since time‐delay effect is incorporated in the mathematical model for the structural control system throughout the derivation of the proposed algorithm, system performance and dynamic stability are guaranteed. Copyright © 2002 John Wiley & Sons, Ltd.     

内蒙古伊勒门盆地砂岩型铀矿成矿水文地质条件初析

简要介绍了伊勒门盆地地下水赋存条件与分布情况，论述了该盆地的构造－水文地质特征，着重阐明区内地下水补给、径流、排泄等水动力条件以及水文地球化学特征，总结了有利的铀矿成矿水文地质条件。     

茂县城区后山龙洞沟泥石流形成条件及防治方法探讨

茂县后山龙洞沟为老的泥石流沟，流域面积为14．63km^2，主沟长9．9km，有三条支沟，主、支沟沟床比降大，在暴雨季节曾多次发生大规模泥石流。根据其泥石流形成特征，采取以拦挡、排导等工程措施为主，结合植树造林、预警预报、工程管理等措施为辅的综合防治方案。