基于奇异值分解和小波阈值方法的地震资料处理方法

奇异值分解是一种基于代数特征值的提取方法,小波变换是一种时间频率域的去噪方法,两者在去噪方面各有特点。将奇异值分解和小波阈值去噪的方法有机地结合起来,用于消除地震勘探资料中的随机噪声。仿真实验显示对于较低信噪比资料仍有很好的处理效果。     

Restoring landscapes: the authenticity problem

Philosophical concerns about restoring landscapes often revolve around two, connected, issues. First is the idea that a restored landscape, even if it is a perfect replica, has lost some of its value. The claim might appeal to a break in the continuity of the landscape and that continuity is part of what is valuable. Alternatively, often in the case of natural landscapes, the appeal is that any human manipulation is inauthentic; here the analogy is sometimes made with the art world and the restoration is deemed a fake. The second problem highlighted in philosophical debates is that the greater the success of restoration projects, the more threatened natural landscapes become: any claim that something must be preserved in its pristine or historically layered state is undermined by the claim that it could be put back again. Initially I discuss two opposing potential responses to these claims: (1) that humans are part of nature and thus cannot be an alien dominating force outside of nature; and (2) that nature is itself a social construct. Neither of these positions is entirely satisfactory, but what they jointly reveal is the reality of our fluid and multifaceted relationship with the world. I then show that Elliot's claim of the additional value of pristine nature is actually not based on an inherent value, but is dependent on the human valuation of it. I propose an alternative that places the source of value in the thing itself and thus arrive at a positive role for restoration as the setting in train and guiding of positive relationships above and beyond their social or public amenity value to us. Copyright © 2006 John Wiley & Sons, Ltd.     

利用均值寻查法精确测定福建及周边地震震源位置

本文利用近震、地方震的各种震相的走时方程，经过变换，取得相应的二次型目标函数。对目标函数用一维寻查法、均值寻查法求出其零值点的自变量，即求得各个方程的解；再用均值寻查法求得各个方程的共解，即得震源位置。随机地处理了自2000～2003年6月福建数字地震遥测台网记录到的本省及周边地区的205个地震，定位结果显示走时残差的平均值为0．25s。在可供比较的前提下，将159个地震数据的奇异值分解法的结果与本文的结果进行对比，前者的平均走时残差为0．72s，后者为0．25s，且后者的每一个地震的走时残差都比前者小。     

锚杆静压桩最终压桩力在砂性土中设计值探讨

锚杆静压桩托换技术施工采用分节压桩,整桩压入时压力不连续,区别于中长预制桩的压桩方式。压桩力受地层影响较为明显。特别是粘性土与砂性土中压桩,最终压桩力的大小有明显区别。在无试桩结果条件下,正确采用最终压桩力,是设计部门较为关心的问题,关系到是否满足单桩设计要求的问题。通过实例,依据基桩静荷载测试成果、小应变动测资料,对在砂性土中锚杆静压桩最终压桩力与设计单桩承载力值的关系,进行分析探讨,并在理论上作了粗浅的定性分析,本文在实际应用中,可作为取用或调整Kp值的依据。     

华北平原开采地下水产生的正效益估算

利用线性回归分析、综合比较的方法计算出了京、津、冀各地工、农业单位水创造产值;1980~2003年华北总的正效益为50287.38亿元,其3地正负效益比为北京116.58∶1,河北32.26∶1,天津2.12∶1。从3个比值可以看出地面沉降的灾情严重程度,天津为最,河北次之,北京较好。这与地下水开采历史以及地面沉降的发展历程相吻合。因此要想将正负效益比最大化,必须合理地开发利用地下水。对地面沉降必须尽早采取防治措施。     

基坑围护设计与实测分析比较

通过不同围护软件分析计算并与实测结果进行比较 ,指出土层水平抗力系数“m”取值的关键性 ,基坑开挖是一个动态而复杂的过程 ,理论计算会有一定的差距     

张北6.2级地震序列特征

１９９８年１月１０日张北６．２级地震后,我们根据《地震现场工作大纲和震情分析指南》用ｂ值ｈ值、ｕ值,ｋ值对该次地震序列进行了综合判定。结果认为此次地震为主震余震型。张北地震序列在衰减过程中出现以４级地震为峰值有节律的起伏,在时间上有较规则的准周期,且每一组起伏前密集－平静规律十分明显。     

地震分析应用软件包

快速,准确地测定出每个地震的参数,编写单台地震报告是地震台站的主要任务。本软件实现了地震分析程序化既满足了台站人员的要求,提高了工作质量,又提高了工作效率。由于本软件使用了三次样条函数插值进行计算数据处理,具有一定的容错能力,实现了计算机自动处理ＲＭＺ量规函数据的插值计算,思路独特,方法简练。本软件最大的特点是具有一定的智能化;输入方法简单,程序操作易懂;免除了以往台站人员的抄写,查表等繁琐劳动。     

Determining the time and space domains for estimating b value in seismic zoning

To take the seismic zone that includes the great shock with M _s≥8.2 as the statistical unit of estimating b value can often lead to more large variance, because the seismogenic zone of the great shock with M _s≥8.2 are larger than that delineated in general seismic zone. Two-level statistical units are considered in this paper. The seismic province is the first level unit that is suitable for group of earthquakes including the great shock of M _s≥8.5. A seismic province can be divided into several seismic zones. They can be taken as the second level unit for group of quakes in which the super magnitude of the greatest shock do not exceed 8. Because of the nonstationarity in time of seismic activity, the unbalancedness of data and differential of seismic temporal series feature in different areas need to be considered when we select the time period for estimating b value. According to local conditions, the time period is selected at one’s discretion in order to reflect seismicity level of this statistical unit in future 100 years. Contribution No. 98A02039, Institute of Geophysics, China Seismological Bureau, China.