地震趋势预测的一种新模型研究

 本文根据自激励门限自回归模型原理,对多年的地震活动形势进行了分析,建立了用于地震大形势分析的客观化数值预测模式-在线预测模型。根据1980年以来中国大陆实际发生的地震资料对这一模型的可靠性进行了检验。统计结果表明,利用在线预测模型在对未来地震趋势进行预测时,其年度形势特征量的最大误差为0.3,平均误差为0.12;因此该模型能够比较客观地反映地震形势变化的自然特征及规律,较好的预测未来的地震活动趋势。这一模型的建立为促进地震趋势向客观化、定量化预测方向发展,提供了一种科学途径     

淮河流域大型水库联合优化调度的动态规划模型解

淮河流域暴雨洪水频繁,常常遭遇恶劣雨型的组合。为使大型水库群在大范围暴雨洪水期间综合效益达到最优,采用动态规划模型求解淮河流域大型水库群的联合优化调度问题,利用国产曙光１０００巨型计算机的高速度和大容量的优势,解决了优化中的“维数灾”和“网格灾”问题,给出了淮河流域９个大型水库联合优化调度模型极效地提高了防洪水库的利用率。     

Micromechanical Modelling of Granular Materials: Effect of Particle Size and Gradation

In this paper the effects of maximum particle size, particle gradation/sorting and fabric on bulk mechanical behaviour of granular materials such as coarse grained soils and rockfills are investigated" from micromechanical considerations starting from the grain scale level, using numerical" simulations based on Discrete Element Modelling (DEM). Hydrostatic compaction and biaxial tests on 2-dimensional assemblies of discs with varying particle sizes and gradations were modelled using DEM. An examination of the constitutive behaviour of granular media considering" the particulate nature of the medium has been attempted to explain the effect of particle size and gradation. Simulation results on perfectly parallel graded assemblies indicate that with increase in the size of the particles, a marginal increase (or no increase) in the angle of internal friction is observed during biaxial loading conditions. A change to a wider gradation (keeping the minimum grain size the same) results in a decrease in the angle of internal friction and an increase in volumetric strain to a considerable extent. Based on micromechanical force and fabric parameters, the basis for the physical behaviour was established. This helps in understanding the physics of parallel gradation techniques.     

气候变化对中国农业生产的影响

根据１９５８￣１９９７年中国３１０个气象站的月平均最高、最低气温,月平均降水量,日照时数等气象参数分析了中国气候的背影特征。用３个大气环流模型,即ＨａｄＣＭ２、ＣＧＣＭ１、ＥＣＨＡＭ４来模拟未来中国气候变化的情景。同时,建立未来气候变化的６种方案。最后,根据３个ＧＣＭｓ模拟的结果,利用国际应用系统分析研究所（ＩＩＡＳＡ）发展并改进的农业生态地带模型（ＡＥＺ）评估气候变化对中国农业生产的影响。评估主     

在AutoCAD中实现三维地层模拟的一种方法

以地层等高线和地质柱状图为建模基础信息,采用曲面样条函数进行插值计算地质曲面,并对AutoCAD进行二次开发,将二维抽象的等高线信息以三维可视化的图形效果在AutoCAD的图形窗口中直观形象地表示出来,为开采和规划决策提供依据.此方法可使煤矿主采区域、城市活断层探测以三维地层显示,对煤矿行业,地震活断层研究有一定的参考价值.     

Dimethylsulphide production in the Southern Ocean using a nitrogen-based flow network model and field measurements from ACE-1

Dimethylsulphide (DMS) has been implicated in climate change as a possible negative feedback to global warming, and several Models have been developed that simulate the production of DMS in the marine environment. The focus of this study is to improve the nitrogen based Gabric Model, using field data collected during the Southern Hemisphere First Marine Aerosol Characterisation Experiment (ACE-1) in the Southern Ocean in 1995. Two Model Runs (Series A and B) were carried out with six simulations of varying biotic and abiotic inputs applied over the voyage transect (41-48°S), reflecting Model default values or field values from the experiment. The abiotic inputs were time-step, dissolved dimethylsulphoniopropionate (DMSP) and DMS, and the biotic nitrogen inputs were from phytoplankton, bacteria, zooflagellates, large protozoa, micro and mesozooplankton. The focus of the abiotic assessment was nutrient (nitrate) uptake and dissolved DMSP and DMS output. Model output of the biotic compartments was assessed for congruence with predicted ecological patterns of succession.

Despite a limited data set the study provides a good insight into the utility of the Model, which functioned as a heuristic rather than predictive tool. In simulation 1 (Series A) where the only field value was nitrate, all latitudes from 41-48°S concurred with the ecological succession predicted by the Model authors and the successional pattern predicted by other researchers, with a double phytoplankton peak indicating remineralisation of nitrogen via the microbial loop. In many simulations the Model produced lower values of dissolved DMS than were measured, and production of DMS in the Model appears constrained. However, in simulation 5 (Series A) DMS model outputs were closest to the mean dissolved DMS levels reported on RV Discoverer. In this simulation, field values were used for phytoplankton, nitrate, dissolved DMSP and DMS, with bacterial abundance and micro and mesozooplankton increased over their Gabric default values. Also, the phytoplankton double peak occurred earlier, as did the peaks in bacteria, zooflagellates, and large protozoa. Simulations that deviated more significantly from the predicted successional patterns were characterised by single peaks in phytoplankton growth and delayed bacterial growth. Series C simulations at latitude 43°S, in an attempt to reduce phytoplankton predation by bacteria, increased DMS output reasonably successfully. However, significant recalibration of the Model is recommended in conjunction with field studies to gather vital background biological data - particularly in the areas of nutrient limitation, phytoplankton speciation, and the cellular content of the DMS precursor compound, DMSP.     

混合海气耦合模式中的ENSO循环及其形成机制

在无异常外强迫的情况下, 将混合海气耦合模式进行了45年的模拟积分.结果表明:模式能较好地再现类似ENSO循环的热带太平洋海洋、大气的年际振荡, 模式ENSO循环的主周期为4~5年; 探讨了ENSO循环的负反馈机制, 指出:暖态的消亡与El Ni?o发展过程中太平洋东部不断增强的东风异常所产生的冷水上翻的加强以及纬向向西的冷平流有关; 冷态的消亡主要由赤道波的时滞效应所致.     

流体饱和多孔介质波动方程的有限元解法

讨论了流体饱和多孔介质中波传播问题的有限元解法,首先在Ｂｉｏｔ理论的基础 上,概述了数学问题的提法,然后提出了一种新型简便的人工边界上的无反射边界条件,同时 给出了有人工边界时流体饱和多孔介质波动方程的有限元计算公式．数值试验的结果表明, 本文提出的无反射边界条件和数值方法均很有效．     

Site effects at Euroseistest—II. Results from 2D numerical modeling and comparison with observations

This paper presents results of numerical modeling of site response for Euroseistest. Ground motion across a very detailed model of the subsoil of this valley has been simulated for vertically incident SH waves. The predominance of locally generated surface waves is very clear in the synthetic seismograms. These results are then compared with published studies of observed site effects at this basin and with a detailed analysis of two events in the time domain. It is discussed in which sense it is possible to obtain a good fit between observations and 1D models, even though the real behavior involves locally generated Love waves. For this reason, it can be misleading to rely on an incomplete observation such as empirical transfer functions. Finally, it is stressed that in order to predict ground motion in alluvial valleys the information contained in the phase cannot be neglected.     

地下水位前兆敏感水力学条件的数值模拟研究

根据弹性孔隙理论,利用数值分析的方法,研究了承压含水层对井水位的映震效果的影响,模拟结果显示：含水层系统的封闭状态对水位的映震效果有很大的影响,侧漏的大小和水头的高低会直接影响水位的观测效果,在系统封闭很好的情况下,观测水位的变化基本与水头的变化呈线性关系,此外,含水层系统的渗透性也是影响水位变化的重要条件之一,渗透性好则水位的映震效果明显。