大坂山公路隧道工程地质特征

大坂山公路隧道位于青海省西宁市—甘肃省张掖市公路(即227国道),自南向北穿越大坂山主峰。隧道轴线长约1.538km,轴线走向29°,系国内海拔最高的公路隧道。由于隧道址区所处的特殊地形地质背景条件,必须查明一些特殊的隧道工程地质问题。经工程地质勘探查明了:一、大坂山址区不存在多年冻土,仅发育季节冻土,对隧道工程危害不大;二、隧道围岩类型分为四类、11段,其中稳定性好的Ⅴ类围岩占隧道全长51％,Ⅳ类围岩占15％,Ⅲ类围岩占2％,稳定性差的Ⅱ类围岩占32％;三、隧道址区地壳稳定程度属次不稳定级,为6.5级地震潜在震源区,在五十年地震活动强度超越概率0.1的条件下,相应地震烈度值为7.8度;四、隧道址区位于分水岭地带,水文地质条件简单,大气降水和地表水不易补给地下水,预测隧道总涌水量仅668m~3/d。     

On one special case of parametric resonance in problems of celestial mechanics

We consider a periodic (in time) linear Hamiltonian system that depends on a small parameter. At a zero value of this parameter, the matrix of the system is constant, has two identical pairs of purely imaginary roots, and is not reducible to diagonal form. Therefore, the unperturbed system is unstable. We propose an algorithm for determining the boundaries of the instability regions for the system at nonzero values of the small parameter. This algorithm was used to analyze the stability of triangular libration points in the elliptical restricted three-body problem and in the stability problem in one special case of stationary rotation of a satellite relative to the center of mass.     

BOOK REVIEWS

Book Reviewed in this article: Unfairly Structured Cities . Blair Badcock Religion and Rural Revolt . Janos M. Bak and Gerhard Benecke The Industrial Geography of Canada . Anthony Blackbourn and Robert G. Putnam The Cuban-American Experience, Culture, Images, and Perspectives. Thomas D. Boswell and James R. Curtis Quaternary Paleoclimatology . R. S. Bradley Development and Crisis in Brazil, 1930–1983 . Luiz Bresser Pereiras Centres of Origin in Biogeography . John C. Briggs Analytical Urban Geography . Martin Cadwallader Geomorphology . Richard J. Chorley , Stanley A. Schumm, and David E. Sugden South Africa: The Impact of Past Geographies . A. J. Christopher The Geography of Underdevelopment. A Critical Survey . D. K. Forbes Health Care in Developing Countries . Wilbert M. Gesler Place to Grow Old: The Meaning of Environment in Old Age . Stephen M. Golant The Emerging Marine Economy of the Pacific . Chennat Gopalakrishnan An Introduction to Agricultural Geography . David B. Grigg The Soviet Union: A Geographical Study . G. Melvyn Howe Geographical Aspects of Health: Essays in Honour of Andrew Learmonth . N. D. Mc Glashan and J. R. Blunden Physical Geography: A Landscape Appreciation . Tom L. Mc Knight Mountain Experience. The Psychology and Sociology of Adventure. Richard G. Mitchell Jr . Systematic and Regional Biogeography. Stanley A. Morain The Economic Transformation of American Cities. T. J. Noyelle and T. M. Stanback , Jr . Normal Accidents: Living With High-Risk Technologies. Charles Perrow Vanishing Farmland: A Legal Solution for the States. Sarah E. Redfield Applied Methods of Regional Analysis: The Spatial Dimensions of Development Policy. Dennis A. Rondinelli Urbanization in Romania. A Geography of Social and Economic Change Since Independence. Per Ronnas Statistical Techniques in Geographical Analysis. Gareth Shaw and Dennis Wheeler The Granite Garden: Urban Nature and Human Design. Anne Whiston Spirn Political Geography: Recent Advances and Future Directions. Peter Taylor and John House Geographia y Medio Ambiente. Manuel Valenzuela -Rubío Nãgara and Commandery: Origins of the Southeast Asian Urban Traditions. Paul Wheatley The Common Fisheries Policy of the European Community. Mark Wise Geography and Gender. Women and Geography Study Group of the IBG Technological Hazards. D. J. Zeigler , J. H. Johnson , S. D. Brunn     

A simple mapping for comets in resonance

The dynamical evolution of a low inclination, intermediate period comet in mean-motion resonance with a giant planet can be described by a simple mapping giving the comet's heliocentric energy and ecliptic longitude at successive aphelia. Provided that the energy oscillations produced by the resonance are not too large, this mapping is linear. When the amplitude of the oscillations is close to the maximum possible within the resonance, the mapping can be improved by adding non-linear terms.     

南图尔盖盆地储层成岩作用及孔隙演化

储层储集性能普遍良好是南图尔盖盆地油气资源丰富的主要原因.通过对该盆地储层的岩石学特征、成岩作用及孔隙类型演化分析研究发现,砂岩的成岩作用及孔隙演化对储层的储集性能有着重要影响.在对大量薄片和岩心进行分析的基础上,运用扫描电镜和X衍射粘土分析等手段,对南图尔盖盆地砂岩储层研究结果表明,该区机械压实和压溶作用、杂基充填作用、胶结作用和交代作用使砂岩孔隙度降低,不稳定矿物的溶蚀作用导致储层次生孔隙发育.根据有机质的演化及粘土矿物的变化序列,成岩作用和孔隙演化随埋深具有明显的阶段性:早成岩阶段,孔隙类型以原生孔隙粒间孔为主;中成岩阶段,孔隙类型以原生、次生混合型为主;晚成岩阶段,孔隙类型以次生型为主.综合评价南图尔盖盆地储层发现,阿雷斯库姆组、阿克萨布拉克组和库姆科尔组为Ⅰ类储层,可作为今后油气勘探的主要目的层.     

1950~2011年渤海地区海表风场的季节特征与多尺度变化分析

基于1950~2011年的NCEP/NCAR再分析资料,对渤海10 m风场的风速与风向变化进行多尺度分析。利用小波分析、交叉谱分析等方法对渤海海域的海表风速、风向的变化趋势以及周期进行研究。分析发现：渤海地区海表风的风向与风速除了存在显著的季节性变化特征外,在年际、年代际的变化尺度上也有明显的周期性。风向存在1 a、8.7 a、15.8 a的显著周期,风速存在1 a、6.3 a、15 a的显著周期。风向与风速在时间尺度分别为20 a、5.71 a、2.67 a时存在显著共振周期;共振周期受东亚季风、西太平副热带高压的年际、年代际变化的影响呈现出多尺度变化周期。     

7个月周期极移的非线性动力机制

从滞弹性阻尼形变摄动造成CW频率调制假设出发，对CW的共振激发模型加上参数的时变调制，变成了参数共振模型。经正演计算发现，参数共振模型完全符合CW的实际，表明滞弹性阻尼形变摄动造成频率的3％调制，进一步使得CW振幅调制可达70％以上。这一参数共振模型是一个非线性动力系统，在非线性情况下，运动将发生分岔，即多解。     

血液流动对MR成像的影响

本文讨论了血液流动对ＭＲ成像的影响。它们是图像为影的来源，在血管造影中，它们用于显示血管和提供关于血液流动速度的信息。流动两个方面的影响敏感，第一质子群的流入和注出。第二流动产生的相位移。本文也介绍了流动补偿技术。     

不同作物下的土壤水盐运动分析

通过１９９５，１９９６年在阿克苏水平衡试验站对不同种植作物的土壤水分，盐分取样分析，显示不同情况下盐分运动规律差异很大，呈现出干旱区土壤盐分含量高，活动强烈的特征。     

油气田微磁异常成因及性质研究的近期进展

微磁测量是80年代出现的一种成功的非常规油气勘探方法,它所检测的是与油气渗漏相关的次生磁性矿化作用。近期的大量研究表明,油气田上方的微磁乒常具有复杂多样的成因:(1)从烃类获得代谢能的硫酸盐还原茵的作用;(2)烃类的微生物降解作用;(3)硫化环境中形成的磁黄铁矿;(4)泥质岩中富铁粘土的自生菱铁矿化;(5)与油气源岩露头或油气藏渗漏有关的自燃变质带。此外,烃类在陆相红层中的磁效应可以受到赤铁矿溶离的干扰,使其磁化强度出现数量级的下降。