基于快速傅里叶方法的地震前兆振幅谱分析

利用FFT方法,对地电、地磁、形变及重力等前兆时间序列信号进行分析,结果显示,宝昌地震台及乌加河地震台地电两测向日均值时间序列存在3个主要谐波分量,其中周期近一年的分量物理意义明确.FFT方法在精确确定前兆时间序列中的干扰信息周期时具有较好的效果.     

随机地震反演关键参数优选和效果分析(英文)

随机地震反演技术是将地质统计理论和地震反演相结合的反演方法,它将地震资料、测井资料和地质统计学信息融合为地下模型的后验概率分布,利用马尔科夫链蒙特卡洛(MCMC)方法对该后验概率分布采样,通过综合分析多个采样结果来研究后验概率分布的性质,进而认识地下情况。本文首先介绍了随机地震反演的原理,然后对影响随机地震反演效果的四个关键参数,即地震资料信噪比、变差函数、后验概率分布的样本个数和井网密度进行分析并给出其优化原则。资料分析表明地震资料信噪比控制地震资料和地质统计规律对反演结果的约束程度,变差函数影响反演结果的平滑程度,后验概率分布的样本个数决定样本统计特征的可靠性,而参与反演的井网密度则影响反演的不确定性。最后通过对比试验工区随机地震反演和基于模型的确定性地震反演结果,指出随机地震反演可以给出更符合地下实际情况的模型。     

Finite element numerical simulation of 2.5D direct current method based on mesh refinement and recoarsement

To deal with the problem of low computational precision at the nodes near the source and satisfy the requirements for computational efficiency in inversion imaging and finite-element numerical simulations of the direct current method, we propose a new mesh refinement and recoarsement method for a two-dimensional point source. We introduce the mesh refinement and mesh recoarsement into the traditional structured mesh subdivision. By refining the horizontal grids, the singularity owing to the point source is minimized and the topography is simulated. By recoarsening the horizontal grids, the number of grid cells is reduced significantly and computational efficiency is improved. Model tests show that the proposed method solves the singularity problem and reduces the number of grid cells by 80% compared to the uniform grid refinement.     

Distribution of fatty acids in the alpine grassland soils of the Qinghai-Tibetan Plateau

As an important biomarker, fatty acids(FAs) have been extensively used to trace the origin of organic matter in sediments and soils. However, studies of the distribution and abundance of FAs in alpine grassland soils are still rare, especially on the Qinghai-Tibetan Plateau(QTP), the highest plateau in the world, which contributes sediments to many large rivers in Asia. This study investigates the composition, distribution and source of FAs with increasing soil depths from 17 typical alpine grassland sites in the QTP. The most abundant FAs included the ubiquitous C16 FA and even-numbered long-chain FAs(C20–C30), indicating mixed inputs from microbial and higher plant sources. Source apportionment showed that higher plants were the dominant contributor of FAs(approximately 40%) in QTP soils. The abundance of FAs decreased with soil depth, with the highest value(1.08±0.09 mg/g C) at a 0–10 cm depth and the lowest value(0.46±0.12 mg/g C) at a 50–70 cm depth, due to much lower plant inputs into the deeper horizons. The total concentration of FAs was negatively correlated to the mean annual temperature(MAT; P0.05) and soil p H(P0.01), suggesting that the preservation of FAs was favored in low-MAT and low-p H soils on the QTP. The abundance of fresh C source FAs increased significantly with the mean annual precipitation(MAP; P0.05), indicating that high MAP facilitates the accumulation of fresh FAs in QTP soils. Other environmental parameters, such as the soil mineral content(aluminum and iron oxide), microbial community composition as well as litter quality and quantity, may also exert a strong control on the preservation of FAs in QTP soils and warrant further research to better understand the mechanisms responsible for the preservation of FAs in QTP soils.     

中国极端气温季节变化对全球变暖减缓的响应分析

利用经过质量控制和均一化处理的中国气象站点1979-2014年逐月最高气温和最低气温资料,对806个无缺测站的数据进行趋势分析和比较,并且计算了各季节对变暖减缓的贡献率,结果表明:中国区域极端气温(最高和最低气温)存在变暖减缓或变冷现象,而不同区域在不同季节对全球变暖减缓的响应程度不同.相比于1979-1999年,2000-2014年极端气温在全国大部分地区春、冬季有明显的变暖减缓或者变冷现象,在长江流域以北大部分地区极端气温在夏季变暖减缓或变冷现象明显,而秋季全国大部分地区最低气温有明显的增暖现象.全国许多地区春季是导致极端气温变暖减缓或变冷的最主要季节,而夏、秋、冬季则是导致部分地区变暖减缓或变冷的主要季节,此外秋季也是导致全国许多地区最低气温变暖的最主要季节.我国大部分地区2000-2014年的变暖减缓或变冷趋势可能受太平洋年代际振荡(PDO)冷位相的调控,而PDO冷位相对最低气温的影响范围更大一些.     

Influence of polymer binder on the physical properties and stability of engineering spoil on a slope

An experiment was performed to study the influence of polymer binders on the physical properties,and stability against a simulated rainfall,of a slope consisting of engineering spoil.Results showed that low polymer binder concentrations(≤500g/m3) could enhance the air permeability and moisture-retaining capacity of the engineering spoil;however,adding more polymer binder made the hardness of the engineering spoil increase and then decline.With the increase of polymer binder concentrations,the surface(0-5cm) permeability of the engineering spoil decreased but the permeability of the lower layers(5-10cm) increased.Polymer binders might reduce runoff and sediment,but the effect becomes weaker with the increase of rainfall.The results of this study have significance for engineering practices.Further experiments are needed to study the effects of binders under other conditions,such as natural rainfall,different slopes,different rock types,different degrees and spoil weathering and different added material,and the chemical interaction between soil and polymer binders.     

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皖西南地区中强地震前后地磁资料变化特征

计算并分析了2011年1月19日安庆M4.8地震和2011年9月10日瑞昌-阳新M4.6地震前后震中周边主要地磁台站地磁转换函数参数的变化特征,总结了安庆地震前华东片主要地磁台站地磁资料垂直分量的变化特征。结果表明:在两次中强地震前,武汉、泾县、金寨三个地磁台的转换函数的部分参数出现了不同程度的异常变化;安庆地震前,中国大陆东部地磁低点时间出现位移,地磁日变形态亦发生了明显的畸变。     

交互式地震广播会商系统的应用

针对目前地震会商现场缺乏交互性与数据分析的动态性,提出地震会商会议发起人-参与者的应用模式。会商期间,通过在广播端实时广播操作消息、运用网络实时推送技术,使各地参与的信息节点会商资料内容一致,同时接收端实时接收并执行操作消息,从而同步显示广播计算机的操作画面,最终达到模拟广播视频的效果。该系统增强了地震会商在线动态数据分析的真实性与实时交互性。