海洋单阶次表面多次波分离方法研究

海洋地震资料普遍发育强能量表面多次波,传统表面多次波压制技术（SRME）能够预测出所有阶次表面多次波,但是各阶次表面多次波相互混叠。为了能够单独利用不同阶次的表面多次波成像,降低干涉假象对多次波成像的影响,需要将不同阶次的表面多次波分离出来。本文提出一种基于扩展SRME的海洋单阶次表面多次波分离方法。首先,应用SRME技术预测出混叠的所有表面多次波;其次,修改常规SRME技术的边界输入条件,将上一步求得的所有多次波进行升阶次处理;再次,预测出混叠的所有表面多次波与其升阶次后的表面多次波匹配相减求得单阶次多次波。以此类推,能够逐步分离出不同阶次的表面多次波。数值模型和某深海实际资料测试表明本方法的有效性,不同阶次表面多次波被有效分离,为后期多次波的利用奠定了基础。     

基于非因果滤波器的多次波匹配相减方法(英文)

在常规多道匹配滤波方法中的滤波器是物理可实现的因果滤波器,只能实现地震信号序列延迟的滤波。本文提出了最小二乘意义下的非因果多道输入多道输出维纳滤波方法,通过比较多道匹配相减中因果和非因果滤波方法之间的差别,验证了方法的有效性,解决了模型数据滞后于实际数据的情况。而且,通过定义长度随偏移距和层速度变化的滑动时窗,解决了匹配时窗内同相轴数量随偏移距增大而增加的问题。并将上述方法应用到改进的扩展多道匹配相减去除多次波的方法中,利用Pluto1.5理论模拟数据,对非因果滤波器和变长度时窗的匹配相减方法进行测试,取得了很好的去除多次波后的地震数据。     

Towards multiple hazard resilient bridges: a methodology for modeling frequent and infrequent time-varying loads Part I, Comprehensive reliability and partial failure probabilities

The current AASHTO load and resistance factor design (LRFD) guidelines are formulated based on bridge reliability,which interprets traditional design safety factors into more rigorously deduced factors based on the theory of probability.This is a major advancement in bridge design specifications.However,LRFD is only calibrated for dead and live loads.In cases when extreme loads are significant,they need to be individually assessed.Combining regular loads with extreme loads has been a major challenge,mainly because the extreme loads are time variables and cannot be directly combined with time invariant loads to formulate the probability of structural failure.To overcome these difficulties,this paper suggests a methodology of comprehensive reliability,by introducing the concept of partial failure probability to separate the loads so that each individual load combination under a certain condition can be approximated as time invariant.Based on these conditions,the extreme loads (also referred to as multiple hazard or MH loads) can be broken down into single effects.In Part Ⅱ of this paper,a further breakdown of these conditional occurrence probabilities into pure conditions is discussed by using a live truck and earthquake loads on a bridge as an example.There are three major steps in establishing load factors from MH load distributions:(1) formulate the failure probabilities;(2) normalize various load distributions;and (3) establish design limit state equations.This paper describes the formulation of the failure probabilities of single and combined loads.     

基于切割环分解的三维建筑物细节层次模型构造

提出一种基于切割环分解的建筑物LOD（细节层次）模型的自动生成方法,该方法首先通过二面角操作算子识别建筑模型中的切割环,然后通过切割环将建筑物模型迭代分割成建筑主体和一系列细部特征,并将分割的结果存储在一棵构造实体几何树（CSG tree）中,最后对特征部件按重要性进行等级划分,同时进行简化处理。试验结果表明该方法具有较高的计算效率,能有效减少模型表面的细节和较好保持模型的结构特征。     

岩石加速破裂行为的物理自相似律

掌握岩石变形破坏过程中体积膨胀点至峰值强度点之间加速破裂行为的演化规律,是实现地质灾害物理预测的关键.本文考虑裂纹张开和闭合两种情况,基于断裂力学建立了三轴应力作用下裂纹扩展临界尺度与等效应力的关系.对微元体破坏概率,分别采用以等效应力表达的Weibull分布函数和裂纹尺度分形函数,通过对比导出了形状参数m与裂纹分布分维D_f关系的表达式.一个有趣的发现是,岩石峰值强度点与体积膨胀点应变比仅与m或D_f有关.对岩石蠕变或准蠕变破坏,合理的m值范围为[1.0,4.0],在此范围内应变比近似为常数1.48,该常数是描述不同尺度岩石加速破裂规律的物理自相似常数.实例分析表明,基于岩石加速破裂规律构建的多锁固段脆性破裂理论,其适用性广,尤其在崩滑和大地震预测领域,具有良好应用前景.此外,本文给出了b值与m值定量关系,以解释b值的物理意义,并探讨将其用于地震预测的可行性.     

自相似型各向异性自组织介质中地震波场动力学响应

地下岩石结构/构造和矿物组成在小尺度上存在的不均匀性和各向异性会导致地震波速度的分形分布,进而衍生出自组织介质模型. 本文针对地球内部岩浆垂向侵入及横向溢流为特征的岩浆作用,开展自相似型各向异性自组织介质的地震波动力学响应研究. 基于二维自组织介质模型和声波方程,本文利用有限差分法模拟了不同强度岩浆侵入和溢流作用形成的自组织介质中地震波场,并进行了波场特征分析. 研究结果表明：（1）在横向溢流作用为主的自组织介质中,横向相关长度小于地震波波长的条件下,聚焦效应随着横向相关长度的增大而增强,地震波能量随之增强;反之,在横向相关长度大于地震波波长的条件下,散射效应随横向相关长度的增大而增强,地震波能量随之减弱. （2）在垂向侵入作用为主的自组织介质中,随着垂向相关长度增大,散射效应增强,地震波的能量也随之迅速减弱. （3）岩浆作用的自组织强度增强,地震波的能量增大,而中心频率无变化. （4）自组织介质具有相同的小尺度扰动,其速度梯度背景越小,地震波能量在炮点附近越集中. （5）当多层自组织介质共存,特征层位的波场特征仍以各自的自组织特性为主,因此利用实际资料中不同层位的地震反射特征可推测地下介质的自组织性质.     

多尺度下的不确定性空间方向锥形模型研究

利用质心作为参考点,并在空间方向锥形模型中添加了扩展不确定度的参数,用区间分析法,对多尺度下顾及不确定性的空间方向关系进行形式化描述,来适应尺度变化引起的空间关系不确定性的变化,以更好地描述空间方向关系。该模型使得方向关系的划分上有个平滑的过渡区,在方向概念的表达上更符合人的认知。     

Climate change mitigation scenarios and policies and measures: the case of Kazakhstan

This article illustrates the main difficulties encountered in the preparation of GHG emission projections and climate change mitigation policies and measures (P&M) for Kazakhstan. Difficulties in representing the system with an economic model have been overcome by representing the energy system with a technical-economic growth model (MARKAL-TIMES) based on the stock of existing plants, transformation processes, and end-use devices. GHG emission scenarios depend mainly on the pace of transition in Kazakhstan from a planned economy to a market economy. Three scenarios are portrayed: an incomplete transition, a fast and successful one, and even more advanced participation in global climate change mitigation, including participation in some emission trading schemes. If the transition to a market economy is completed by 2020, P&M already adopted may reduce emissions of CO₂ from combustion by about 85 MtCO₂ by 2030 – 17% of the emissions in the baseline (WOM) scenario. One-third of these reductions are likely to be obtained from the demand sectors, and two-thirds from the supply sectors. If every tonne of CO₂ not emitted is valued up to US$10 in 2020 and $20 in 2030, additional P&M may further reduce emissions by 110 MtCO₂ by 2030.