基于小波变换的岩石声发射信号互相关分析及时延估计

声发射全波形采集为基于波形分析的声源定位方法提供了可能。声发射源定位方法中最常用的是时差定位方法,因此,时差获取精确与否直接影响定位的精度。借助于小波变换和互相关技术研究声发射信号的时延估计,首先利用小波分析技术对信号进行分解,确定有意义信号的频带宽度,再提取分解后的相应频带的小波系数,利用互相关技术计算出该频带信号到达各传感器的时差,进而利用时差定位法反演声发射源,实现了声发射源更精确的定位。经声发射监测验证结果表明,该时延估计方法能有效地减小声发射源定位的误差,提高声发射源的定位精度,为准确反演声发射源提供了一种有效途径。     

京西盆岭构造区积累库仑破裂应力变化对强震的影响

Since 231 B. C.,a total of 15 M6.0 - 7.5 earthquakes have been recorded in the west Beijing basin-range tectonic region( 38.3°- 41.5° E,112°- 116.2° N),a region mainly under the action of tensional normal faulting. In this paper,we calculate the Coulomb stress change of each earthquake and the cumulative Coulomb stress change,and on this basis we analyze the stress triggering of strong earthquakes. The research shows that there are 10 of 14 earthquakes that occurred in the trigger zones,in which the Coulomb stress change is positive,and the trigger rate is 71%. The positive areas of cumulative Coulomb stress change caused by these 15 earthquakes are: middle of northern Liulengshan fault,Northern Huaizhuo basin fault,Xinbaoan-Shacheng fault,Sangganhe fault and Southern Yuxian basin fault. This necessarily increases the seismic risk of these faults and can be used as a reference for future seismic risk analysis in this area.     

京西盆岭构造区积累库仑破裂应力变化对强震的影响

以拉张正断层作用为主的京西盆岭活动构造区(112°～116.2°N, 38.3°～41.5°E)自BC231年以来共记载和记录15次M6～7.5地震。 本研究计算每一次强震产生的以及逐次积累的库仑破裂静应力变化, 并分析强震之间的应力触发关系。 结果显示在14次后发的强震中, 有10次发生在先发强震产生的积累库仑破裂静应力变化为正的触发区, 触发率为71%。 所有15次历史强震作用共同引起研究区积累库仑破裂静应力变化的正值区, 主要分布于六棱山北麓断裂中段、 怀涿盆地北缘断裂、 新保安沙城断裂、 桑干河断裂以及蔚县盆地南缘断裂, 并使得这些断裂(段)的强震危险性有所增加, 这可为分析研究区的未来强震危险性提供参考。     

一种提高大高差短基线精度的方法

提出采用半参数模型解算大高差短基线,削弱残余对流层误差的影响。算例表明,与常规最小二乘法相比,采用半参数模型处理基线能很好地分离GPS残余对流层误差,提高基线解算精度。     

基于STIRPAT模型的江苏省能源消费碳排放影响因素分析及趋势预测

定量分析碳排放的影响因素,对降低区域碳排放具有重要的指导意义。利用STIRPAT模型,定量分析江苏省能源消费碳排放量与人口、富裕度（以人均GDP表示）、技术进步（以能源强度表示）和城镇化水平之间的关系,通过岭回归拟合后发现,人口数量、人均GDP、能源强度、城市化水平每变化1%,江苏省能源消费碳排放量将分别发生3.467%、(0.242+0.024 lnA)%、0.313%和0.151%的变化。在以上研究的基础上,设置8种不同的发展情景,分析了江苏省未来能源消费碳排放量的发展趋势。结果表明,当人口、经济保持低速增长,并保持高技术增长率时,有利于控制江苏省的能源消费碳排放量,2020年江苏省的能源消费碳排放量预测值为202.81 MtC。     

联合平差中的方差分量估计问题的探讨

天文大地网与GPS空间网联合平差从大的方面分为空间网与地面网两部分。空间网主要是GPS点的三维地心坐标及协方差阵 ;而地面网又涉及到多类观测值 ,主要包括方向观测、导线边、天文方位角三类观测值 ,且各类观测值又分为不同等级的观测。空间网与地面网之间、地面网不同类观测之间及同一类不同观测等级之间的权比不正确将直接影响平差结果 ,因此 ,各类观测值的最佳权匹配就成为联合平差的一个关键。本文就Helmert方差分量简化算法及Baumker简化公式用于联合平差中方差分量估计问题进行讨论 ,并用我国天文大地网 1万点的地面观测数据进行实算、比较、分析 ,以确定联合平差中方差分量估计的方法     

Earthquake magnitude estimation using the τc and Pd method for earthquake early warning systems

Earthquake early warning （EEW） systems are one of the most effective ways to reduce earthquake disaster. Earthquake magnitude estimation is one of the most important and also the most difficult parts of the entire EEW system. In this paper, based on 142 earthquake events and 253 seismic records that were recorded by the KiK-net in Japan, and aftershocks of the large Wenchuan earthquake in Sichuan, we obtained earthquake magnitude estimation relationships using the τe and Pa methods. The standard variances of magnitude calculation of these two formulas are ±0.65 and ±0.56, respectively. The Pd value can also be used to estimate the peak ground motion of velocity, then warning information can be released to the public rapidly, according to the estimation results. In order to insure the stability and reliability of magnitude estimation results, we propose a compatibility test according to the natures of these two parameters. The reliability of the early warning information is significantly improved though this test.     

Comparison of adaptive structural damage identification techniques in nonlinear hysteretic vibration isolation systems

Early structural damage identification to obtain an accurate condition assessment can assist in the reprioritization of structural retrofitting schedules in order to guarantee structural safety. Nowadays, seismic isolation technology has been applied in a wide variety of infrastructure, such as buildings, bridges, etc., and the health conditions of these nonlinear hysteretic vibration isolation systems have received considerable attention. To effectively detect structural damage in vibration isolation systems based on vibration data, three time-domain analysis techniques, referred to as the adaptive extended Kalman filter （AEKF）, adaptive sequential nonlinear least-square estimation （ASNLSE） and adaptive quadratic sum-sqnares error （AQSSE）, have been investigated. In this research, these analysis techniques are compared in terms of accuracy, convergence and efficiency, for structural damage detection using experimental data obtained through a series of laboratory tests based on a base-isolated structural model subjected to E1 Centro and Kobe earthquake excitations. The capability of the AEKF, ASNLSE and AQSSE approaches in tracking structural damage is demonstrated and compared.     

Accuracy of the half-power bandwidth method with a third-order correction for estimating damping in multi-DOF systems

A third-order correction was recently suggested to improve the accuracy of the half-power bandwidth method in estimating the damping of single DOF systems.This paper analyzes the accuracy of the half-power bandwidth method with the third-order correction in damping estimation for multi-DOF linear systems.Damping ratios in a two-DOF linear system are estimated using its displacement and acceleration frequency response curves,respectively.A wide range of important parameters that characterize the shape of these response curves are taken into account.Results show that the third-order correction may greatly improve the accuracy of the half-power bandwidth method in estimating damping in a two-DOF system.In spite of this,the half-power bandwidth method may significantly overestimate the damping ratios of two-DOF systems in some cases.     

An adaptive over/under data combination method

The traditional ＂dephase and sum＂ algorithms for over/under data combination estimate the ghost operator by assuming a calm sea surface. However, the real sea surface is typically rough, which invalidates the calm sea surface assumption. Hence, the traditional ＂dephase and sum＂ algorithms might produce poor-quality results in rough sea conditions. We propose an adaptive over/under data combination method, which adaptively estimates the amplitude spectrum of the ghost operator from the over/under data, and then over/under data combinations are implemented using the estimated ghost operators. A synthetic single shot gather is used to verify the performance of the proposed method in rough sea surface conditions and a real triple over/under dataset demonstrates the method performance.