手掘式顶管在市政排水工程中的应用

从混凝土管材的选定、工作坑的设计及施工、顶管顶进中若干关键问题入手,介绍了手掘式顶管施工技术在成都市中心城水环境综合整治工程G标段管道排水工程中的应用。     

西部大开发与中国经济发展

在对中国西部的区域划分进行界定并阐述中国西部区域特征的基础上,对中国西部的开发进行了历史回顾,并对中国西部开发的历史背景和现实基础、中国西部开发的优势和制约条件进行分析,最后提出了中国西部开发的发展战略和政策措施.     

不同年度收存的褶皱臂尾轮虫休眠卵的孵化及滞育胚胎“激活”效果的研究

比较了 1 985— 1 998年间由同一褶皱臂尾轮虫 (Brachionusplicatilis)种群在实验室内历年产生并收存的休眠卵的孵化效果 ,并初步探讨了胚胎“激活”处理对孵化的影响。结果表明 ,休眠卵的收存年度或时间对其在一定孵育期内的总孵化率 (THR)和日孵化率 (DHR)有极显著影响 (x2 检验 ,p<0 .0 0 1 ) ,但THR和DHR与储存时间间均无显著的相关性 ,而是呈极大波动。同时发现“激活”作用具有促使孵化高峰提前到来、增强孵化同步性的双重功效 ,从而可明显缩短孵育时间 ,提高孵化速率。但“激活”前后多数卵样的总孵化率无显著变化 (p >0 .0 5 )。详细讨论了可能导致孵化率波动的多种因素 ,例如遗传变异、培养历史、储存及孵化的环境条件等。     

Characteristic analysis on oxygen isotopic tracer in the East China Sea and waters to east of the Ryūkyū-guntō

Samples of O isotopic tracer were mlleMed at Sections P₃,P₂₅,P_cM-t/2-E and P_CM-1/2.w in both the Fast China Sea and the area to the east of the Ryūkyū-gunto during October-November,1991.Analytical results of the δ¹⁸O are as follows: (1) In the Kuroshio area,the δ¹⁸O isolines are almost parallel to the 200 m isobath.The value of δ¹⁸O is negative and reaches minimum mt the main axis of the Kuroshio,and increases on both sides.(2) In the Taiwan Warm Current (TWC) area there is a high δ¹⁸O tongue extending to the northeast.(3) In the area near the coast,the distribution of δ¹⁸O isoline shows that the Changjiang River runoff diffuses seaward and the land-ocean isotopic effect from the nearshore to the offshore.(4) The values of δ¹⁸O are from -1.0×10^-3 to -0.5×10^-3 in the shelf.(5) There is a low mre of δ¹⁸O value(<-1.6×10^-3) at the 600 m layer in the Kuroshio area,which is quite in accord with the existence of a low salinity mre (S G 34.30) between the 600 and 800 m layers in the same area.Finally,the mrrelations of the δ¹⁸O with the salinity and temperature,the upwelling and so on are discussed.     

基于历史关系数据库的时空数据库实现研究

时空数据库是研究如何存储历史和当前的时空数据,从而跟踪分析某一区域的变化,最终实现时空模型化和模拟地学过程.采用历史关系数据库模式的时空数据库可以充分利用传统时态数据库时态查询功能和GIS空间分析处理功能这些方面成熟的研究成果和现有系统,降低时空数据库建立的费用和开销.分析了采用扩展关系型时空数据库的原因,介绍了历史关系数据库模式、时态关系代数和查询语言,研究了采用历史关系数据库模式在全关系化空间数据库中组织时态信息的方法,从而实现时空数据库.以麦地轮作为例说明了采用历史关系数据库模式建立时空数据库的可行性和有效性.     

汶川特大地震后成都盆地内隐伏断层活动性分析

成都盆地内主要有3条隐伏的活动断裂带,包括大邑断裂带、蒲江-新津断裂带和龙泉山断裂带,它们在第四纪都表现出了一定的活动性."512"汶川特大地震后,笔者实地考察的结果表明,在汶川特大地震中成都盆地中的隐伏断裂没有产生新的活动性,目前成都盆地不存在发生特大地震的危险性,是安全的.     

Bayesian estimation of seismic hazard for two sites in Switzerland

Seismic hazard analysis is based on data and models, which both are imprecise and uncertain. Especially the interpretation of historical information into earthquake parameters, e.g. earthquake size and location, yields ambiguous and imprecise data. Models based on probability distributions have been developed in order to quantify and represent these uncertainties. Nevertheless, the majority of the procedures applied in seismic hazard assessment do not take into account these uncertainties, nor do they show the variance of the results. Therefore, a procedure based on Bayesian statistics was developed to estimate return periods for different ground motion intensities (MSK scale).Bayesian techniques provide a mathematical model to estimate the distribution of random variables in presence of uncertainties. The developed method estimates the probability distribution of the number of occurrences in a Poisson process described by the parameter . The input data are the historical occurrences of intensities for a particular site, represented by a discrete probability distribution for each earthquake. The calculation of these historical occurrences requires a careful preparation of all input parameters, i.e. a modelling of their uncertainties. The obtained results show that the variance of the recurrence rate is smaller in regions with higher seismic activity than in less active regions. It can also be demonstrated that long return periods cannot be estimated with confidence, because the time period of observation is too short. This indicates that the long return periods obtained by seismic source methods only reflects the delineated seismic sources and the chosen earthquake size distribution law.     

Actinic flux and photolysis frequency comparison computations using the model PHOTOGT

The accurate radiative transfer model GOMETRAN, initially designed to yield radiances at TOA in the wavelength range 240–790 nm, has been extended to allow for the computation of actinic fluxes down to 175 nm and for the calculation of photolysis frequencies in the atmosphere. The capability of the extended model PHOTOGT (PHOTOGOMETRAN) is demonstrated in a number of successful comparison studies both with recent experiments (ground-based, balloonborne, airborne) and model calculations of radiances, actinic fluxes and photolysis frequencies in the stratosphere and troposphere. In an atmospheric case study, the impact of new quantum yield data for the O₃ » O₂+O(¹ d) photodissociation channel on the photolytic production of O(¹ d) atoms in the lower atmosphere has been quantified.     

寒武系古流体地球化学特征及其对页岩气保存的指示意义 ——以中扬子地区寒武系页岩气发现井宜地2井为例

保存条件是中扬子地区页岩气富集的关键因素之一，宜地2井是中扬子寒武系页岩气发现井，通过对该井全井段岩芯裂缝古流体的地球化学分析，探讨了寒武系古流体成因和对水井沱组页岩气保存条件的指示意义。结果认为：① 覃家庙组膏岩层之上方解石脉缺少Fe2+、Mn2+，且δ13C和δ18O值较围岩偏负，指示其形成于氧化的环境，石牌组方解石脉δ13C偏负，黄铁矿脉δ34S值与膏盐相似，表明其成因与TSR密切相关；水井沱组脉体δ13C和δ18O与围岩相似，形成于封闭的环境。② 方解石脉包裹体群SO42-、Ca2+、Mg2+含量整体上由覃家庙组向上向下分别递减，钠氯系数以水井沱组最低，整体上向上升高，表明覃家庙组是高盐度卤水的主要来源，水井沱组受外来流体影响弱；包裹体水溶液δD和δ18O也指示娄山关组、石牌组方解石脉成因分别与大气水、TSR相关。③ 古流体地球化学研究表明宜昌地区页岩气保存条件整体较好，页岩气散失的主要通道是垂直裂缝，页岩气保存条件好与膏盐盖层发育、后期构造破坏弱、脉体对裂缝的及时封闭以及白垩系盖层等因素密切相关。