Seismic hazard estimation based on the distributed seismicity in northern China

In this paper, we have proposed an alternative seismic hazard modeling by using distributed seismicites. The distributed seismicity model does not need delineation of seismic source zones, and simplify the methodology of probabilistic seismic hazard analysis. Based on the devastating earthquake catalogue, we established three seismi- city model, derived the distribution of a-value in northern China by using Gaussian smoothing function, and cal-culated peak ground acceleration distributions for this area with 2%, 5% and 10% probability of exceedance in a 50-year period by using three attenuation models, respectively. In general, the peak ground motion distribution patterns are consistent with current seismic hazard map of China, but in some specific seismic zones which in-clude Shanxi Province and Shijiazhuang areas, our results indicated a little bit higher peak ground motions and zonation characters which are in agreement with seismicity distribution patterns in these areas. The hazard curves have been developed for Beijing, Tianjin, Taiyuan, Tangshan, and Ji’nan, the metropolitan cities in the northern China. The results showed that Tangshan, Taiyuan, Beijing has a higher seismic hazard than that of other cities mentioned above.     

基于地震动参数的建筑物震害研究

本文介绍了多步简化的push—over(MSP)方法,引导出求解单体建筑物易损性指数和群体建筑物易损性指数的办法,并通过建筑物平均易损性指数曲线,来评价城市的总体抗震性能。本文不采用过去以烈度为地震输入的易损性评定方法,采用地震动参数作为城市建筑物易损性的评定标准。给出的易损性指数曲线,可用来查找不同地震动参数下各类建筑物的易损性结果,比较城市各类建筑物的抗震性能。本文研究可望在城市建筑物震害评估中有好的应用前景。     

Development of stochastic dynamic Nash game model for reservoir operation. I. The symmetric stochastic model with perfect information

Increasing water demands, higher standards of living, depletion of resources of acceptable quality and excessive water pollution due to agricultural and industrial expansions have caused intense social and political predicaments, and conflicting issues among water consumers. The available techniques commonly used in reservoir optimization/operation do not consider interaction, behavior and preferences of water users, reservoir operator and their associated modeling procedures, within the stochastic modeling framework. In this paper, game theory is used to present the associated conflicts among different consumers due to limited water. Considering the game theory fundamentals, the Stochastic Dynamic Nash Game with perfect information (PSDNG) model is developed, which assumes that the decision maker has sufficient (perfect) information regarding the associated randomness of reservoir operation parameters. The simulated annealing approach (SA) is applied as a part of the proposed stochastic framework, which makes the PSDNG solution conceivable. As a case study, the proposed model is applied to the Zayandeh-Rud river basin in Iran with conflicting demands. The results are compared with alternative reservoir operation models, i.e., Bayesian stochastic dynamic programming (BSDP), sequential genetic algorithm (SGA) and classical dynamic programming regression (DPR). Results show that the proposed model has the ability to generate reservoir operating policies, considering interactions of water users, reservoir operator and their preferences.     

全球强震与地球自转角加速度变化过程关系统计研究

统计分析了1962—2017年全球强震活动与地球自转角加速度变化过程的关系, 结果显示, 全球8级以上地震发生在地球自转角加速度下降期的概率相对自然概率高出12%, 达到64%, 统计结果具有显著性, 但7.5级和7.8级以上地震的统计结果没有显著性。 分区统计结果表明, 全球强震活动具有明显的区域性特征: 在地球自转角加速度上升期, 高于自然概率的强震主要分布在阿尔卑斯带中西段、 环太平洋地震带的琉球—菲律宾地区以及中国东部; 在地球自转角加速度下降期, 高于自然概率的强震主要分布在环太平洋地震带、 阿尔卑斯带中段(喜马拉雅弧)、 阿尔卑斯带东段(印尼岛弧海沟)以及中亚大陆地区。 分析认为地球自转角加速度变化过程与全球区域地震活动之间存在较强的相关性, 可能与地球自转角加速度变化引起板块间相互作用的强弱有关。     

广域网加速在FY-3气象卫星数据传输中的应用

风云三号 (FY-3) 极轨气象卫星数据传输系统需通过广域网链路,将海量卫星观测数据从卫星接收站快速传送到资料处理中心。该文研究广域网加速技术,解决广域网链路中传输气象卫星海量观测数据延迟高、带宽利用低等难题。文中针对FY-3气象卫星观测数据传输量大、时效要求高的特点,分别分析了数据压缩、数据缓存和协议优化3种不同加速技术对卫星数据的传输优化效果,并根据分析结果提出了一种适用于气象卫星数据的广域网传输加速架构。该架构结合3种不同加速技术设计了TCP代理模块、数据段索引模块和HS-TCP传输模块以及相应算法分别实现了数据压缩与缓存和协议优化等功能。通过测试和实际运行表明:在该加速架构下卫星数据广域网传输速率提高了50%~243%。     

Stochastic modeling of reactive transport in wetlands

This study describes the development of a general model for reaction in and performance of spatially heterogeneous bioreactors such as treatment wetlands. The modeled domain possesses local-scale velocities, reaction rates and transverse dispersion coefficients that are functions of an underlying heterogeneity variate representing one or more controlling biophysical attributes, for example, reactive surface area (submerged plant) density. Reaction rate coefficients are treated as related to local velocities in an inverse square fashion via their mutual dependence upon the variate. The study focuses on the solution for the steady-state case with constant inlet concentration. Results compare well with exact solutions developed for laterally-bounded systems in which the heterogeneity is represented explicitly. Employing the bicontinuum analogue of a second-order model, an expression for an effective longitudinal dispersion coefficient as a function of travel distance is developed using the method of moments. The result provides insights into the behavior of concentration as transverse mixing drives the system asymptotically toward Fickian longitudinal dispersion. The model may represent an improvement over other approaches for characterizing treatment wetland performance because it accounts for evolving shear flow dispersion, and because parameters are few in number, physically based, and invariant with mean velocity.     

Alfven行波涌浪携带的场向电场──极光粒子加速机制

提出一个剪切Ａｌｆｖｅｎ波加速极光粒子的新模式。频率远小于离子回旋频率的Ａｌｆｖｅｎ波由磁层向电离层传播会演化成孤波，当场向电流超过离子声不稳定性的临界电流时，激发离子声不稳定性，波与粒子的相互作用产生反常阻尼使Ａｌｆｖｅｎ波演化成行波涌浪。它携带一个方向向上的平行电场，加速极光电子形成分立极光。对等离子体密度、电场及其对应的电势进行了数值计算，结果发现满足磁层加速区条件形成Ａｌｆｖｎ行波涌浪，提供足够强的加速粒子的电场。     

PREDICTION OF VERTICAL RESPONSE SPECTRA IN EUROPE

Equations for the prediction of vertical peak and absolute acceleration spectral ordinates in terms of magnitude, source-distance and site geology are presented. Comparison to similarly derived horizontal equations shows vertical spectral values to be 1/2–1/4 of the horizontal. The influence of site geology on vertical ground motion is reduced with respect to the horizontal. Ratios of peak vertical to peak horizontal ground acceleration in the near-field of thrust faults are magnitude and distance dependent, reaching values in excess of one very near the fault of large magnitude events. For strike-slip faults the ratio exceeds one for moderate events, decreasing for larger events, and is distance independent. Spectral acceleration ratios exceed one at short periods but are less than one at intermediate and long periods, irrespective of the source mechanism.     

CFG桩加固饱和粉土地基的动力特性试验研究

以京沪高速铁路液化土地基加固为背景,利用大型堆叠式剪切变形模型箱,进行了模型比例1:10的CFG桩桩网结构地基加固饱和粉土地基的振动台模型试验,得出各级加载情况下地基路基响应加速度幅值放大系数的分布以及响应加速度幅值放大系数与各级加载加速度幅值的关系,分析了CFG桩桩网结构地基加固饱和粉土地基在地震作用下的加速度传递规律,得到了以下结论：（1）在加载加速度小于0.101g时,地基路基响应加速度幅值基本不放大,且加速度放大系数云图呈现水平状分布;（2）当加载加速度为0.161g时,桩间土的液化引起地基路基的响应加速度幅值放大系数的较大增加;（3）当加载加速度为0.210g时,桩间土液化的同时部分CFG桩发生剪断破坏,从而引起了地基路基的各响应加速度幅值放大系数的增大;（4）当加载加速度为0.324g和0.363g时,地基整体刚度的大幅度减小,在一定程度上降低了桩网结构地基传递振动的能力,从而导致加速度幅值放大系数相对前一级加载时减小;（5）整个加载过程中,粉土层的放大效应显著,而黏土层对加载加速度几乎没有放大作用。