Application of the Double-difference Relocation Method Combined with Waveform Cross-correlation on the Three Gorges Reservoir Seismicity

In this paper,we use the double difference location method based on waveform crosscorrelation algorithm for precise positioning of the Three Gorges Reservoir( TGR)earthquakes and analysis of seismic activity. First,we use the bi-spectrum cross-correlation method to analyze the seismic waveform data of TGR encrypted networks from March,2009 to December,2010,and evaluate the quality of waveform cross-correlation analysis.Combined with the waveform cross-correlation of data obtained, we use the double difference method to relocate the earthquake position. The results show that location precision using bi-spectrum verified waveform cross-correlation data is higher than that by using other types of data,and the mean 2 sig-error in EW,NS and UD are 3.2 m,3.9 m and 6.2 m,respectively. For the relocation of the Three Gorges Reservoir earthquakes,the results show that the micro-earthquakes along the Shenlongxi river in the Badong reservoir area obviously show the characteristics of three linear zones with nearly east-west direction,which is in accordance with the small faults and carbonate strata line of the neotectonic period,revealing the reservoir water main along the underground rivers or caves permeated and induced seismic activity. The stronger earthquakes may have resulted from small earthquakes through the active layers.

Multiplet relative location approach and waveform correlation correction and their application

The theory and method of relative location technique were described in the paper. The travel-time difference equa-tions for five phases (Pg, Sg, P11, S11 and Pn) were given. By using the multiplet relative location approach and wave correlation correction, the aftershock cluster of the Shunyi earthquake occurred on December 16, 1996 was relocated. The depth calculation was constrained by using multiple seismic phases. The relocation results were compared with that from traditional absolute location techniques.

The MW5.5 earthquake on August 6,2023,in Pingyuan,Shandong,China:A rupture on a buried fault

On August 6,2023,a magnitude MW5.5 earthquake struck Pingyuan County,Dezhou City,Shandong Province,China.This event was significant as no large earthquakes had been recorded in the region for over a century,and no active fault had been previously identified.This study collects 1309 P-wave arrival times and 866 S-wave arrival times from 74 seismic stations less than 200 km to the epicenter to constrain the spatial distribution of the mainshock and its 125 early aftershocks by the double difference earthquake relocation method,and selects 864 P-waveforms from 288 stations located within 800 km of the epicenter to constrain the focal mechanism solution of the mainshock through centroid moment tensor inversion.The relocation and the inversion indicate,the Pingyuan MW5.5 earthquake was caused by a rupture on a buried fault,likely an extensive segment of the Gaotang fault.This buried fault exhibited a dip of approximately 75°to the northwest,with a strike of 222°,similar to the Gaotang fault.The rupture initiated at the depth of 18.6 km and propagated upward and northeastward.However,the ground surface was not broken.The total duration of the rupture was~6.0 s,releasing the scalar moment of 2.5895×1017 N·m,equivalent to MW5.54.The moment rate reached the maximum only 1.4 seconds after the rupture initiation,and the 90%scalar moment was released in the first 4.6 s.In the first 1.4 seconds of the rupture process,the rupture velocity was estimated to be 2.6 km/s,slower than the local S-wave velocity.As the rupture neared its end,the rupture velocity decreased significantly.This study provides valuable insights into the seismic characteristics of the Pingyuan MW5.5 earthquake,shedding light on the previously unidentified buried fault responsible for the seismic activity in the region.Understanding the behavior of such faults is crucial for assessing seismic hazards and enhancing earthquake preparedness in the future.

Accurate relocation of earthquakes in central-western China using the double-difference earthquake location algorithm

The double-difference earthquake relocation algorithm (DD algorithm) has been applied to the accurate relocation of 10057 earthquakes in the central-western China (21°-36°N, 98°-112E°) during the period of 1992-1999. In total, 79706 readings for P waves and 72169 readings for S waves were used in the relocation, and the source parameters of 6496 events were obtained. The relocation results revealed a more complete picture of the hypocentral distribution in the central-western China. In several seismic belts the relocated epicenters present a more defined lineation feature, reflecting the close correlation between the seismicity and the active tectonic structures. The relocated focal depths confirmed that most earthquakes (91 percent of the 6496 relocated events) in the central-western China were located at shallower depths not deeper than 20 km. The distribution of focal depths indicates that the seismogenic layer in the central-western China is located in the upper-mid crust with its thickness no deeper than 20 km.

P-wave velocity structure beneath reservoirs and surrounding areas in the lower Jinsha River

The lower reaches of the Jinsha River are rich in hydropower resources because of the high mountains,deep valleys,and swift currents in this area.This region also features complex tectonic structures and frequent earthquakes.After the impoundment of the reservoirs,seismic activity increased significantly.Therefore,it is necessary to study the P-wave velocity structure and earthquake locations in the lower reaches of the Jinsha River and surrounds,thus providing seismological support for subsequent earthquake prevention and disaster reduction work in reservoir areas.In this study,we selected the data of 7.670 seismic events recorded by the seismic networks in Sichuan.Yunnan,and Chongqing and the temporary seismic arrays deployed nearby.We then applied the double-difference tomography method to this data,to obtain the P-wave velocity structure and earthquake locations in the lower reaches of the Jinsha River and surrounds.The results showed that the Jinsha River basin has a complex lateral P-wave velocity structure.Seismic events are mainly distributed in the transition zones between high-and low-velocity anomalies,and seismic events are particularly intense in the Xiluodu and Baihetan reservoir areas.Vertical cross-sections through the Xiangjiaba and Xiluodu reservoir areas revealed an apparent high-velocity anomaly at approximately 6 km depth:this high-velocity anomaly plays a role in stress accumulation,with few earthquakes distributed inside the high-velocity body.After the impoundment of the Baihetan reservoir,the number of earthquakes in the reservoir area increased significantly.The seismic events in the reservoir area north of 27°N were related to the enhanced activity of nearby faults after impoundment:the earthquakes in the reservoir area south of 27°N were probably induced by additional loads(or regional stress changes),and the multiple microseismic events may have been caused by rock rupture near the main faults under high pore pressure.

考虑舰载无人机的海战场作战物资保障中心选址及配置优化研究

俗话说:兵马未动,粮草先行.作战物资供应保障能力已经成为影响战争胜负的重要因素.传统的海战场作战物资保障大多采用有人船只在海面运送物资,运输速度慢,容易被敌军发现,可能产生人员伤亡.为提升运送效率、人员和物资的安全性,考虑采用舰载无人机的方式解决海战场作战物资保障中心的选址及配置问题.首先,构建了双目标非线性规划模型,并设计了一种结合自适应聚类算法和整数规划模型的两阶段决策方法对问题进行求解,分别得到物资运送时间最短的海战场物资保障中心选址方案、满足物资需求前提下成本最小的母舰和无人机的配置方案.最后,通过算例分析证实了本文提出方法的有效性和实用性,为海战场作战物资保障中心选址及配置提供了理论依据和决策支持,有助于增强海战场作战后勤保障能力.

2021年5月22日青海玛多M7.4地震余震重新定位与断层面参数拟合

文中基于青海和周边地震台网72个台站以及震后布设的12个流动观测台站于2021年5月22—27日记录的青海玛多M7.4地震主震及1 357次余震资料,使用双差地震定位法重新对余震位置进行了修定,获得了1 289次余震修定后的震源位置。重新定位后,余震基本沿昆仑山口-江错断裂呈NWW向线性分布,震源深度由重新定位前主要集中于5~10km变为在5~15km深度范围内相对均匀地分布。根据重新定位后的余震分布特点并参考地质断层及现场考察的地震破裂带展布情况,依据成丛地震发生在断层附近的原则,选取了6个矩形区域内重新定位后的震源信息,联合采用模拟退火与高斯-牛顿算法反演获得了每个区域断层面的详细参数。结果表明,主干断裂为长约146km、总体走向为285°~290°的高倾角大型左旋走滑兼逆冲断裂。重新定位还显示,主干断裂东、西两侧有分叉现象,可能是大地震发生时期由于复杂的应力分配导致触发并新产生2条分支断裂,断裂整体显示为树形。西侧分支走向为306°,与主干断裂相交,夹角为21°。东侧分支走向近EW,与主干断裂的东段相连。

Farmer Participatory Evaluation of Sorghum Hybrid in Niger

Participatory varietal selection (PVS) with farmers and Seed Companies was conducted at Maradi research station (07°05'E/13°48'N) and in farmer field to evaluate and select sorghum hybrid varieties for high yield and other important agronomic traits. The experimental design was a randomized complete block with three replications where flowering (days), plant height (cm) and yield (kg) were collected. The analysis of variance showed highly significance among treatments of all traits measured Environment and Genotype by Environment interactions also contributed significantly to the performance of yield components. The highest average grain yield was recorded from hybrids P9511A x ST9007-5-2-1 (4289 kg/ha), NE223A x 90SN1 (3666 kg/ha), NE223A x Sepon 82 (3533 kg/ha) and NE223A x P9405 (3519 kg/ha) across locations. Farmers’ preferences were the panicle size, good seed set, earliness, and seed color. Hence, in a variety selection farmer’s preferences focus more on prioritized yield-related trait. The best varieties ranked by traits of interest were P9511A x ST9007-5-2-1, NE223A x 90SN1, NE223A x P9405 and P9511A x SEPON 82 that performed well under their circumstances. The results showed that farmers’ preferred varieties match with researchers. Therefore, based on objectively measured traits, farmers’ preferences and the agro ecologies of the site, varieties NE223A x 90SN1 and P9511A x ST9007-5-2-1 were found promising for production.

无线传感器网络中的定位模型

位置信息在无线传感器网络应用中日益重要,针对该网络中的定位问题,提出一种新颖的基于模糊识别的定位模型.在该模型中,定位空间被一些样本点划分为若干个小区域,每个样本点唯一地对应一个信号向量,通过计算未知点信号向量与各个样本点对应向量的贴近度,可以最终确定未知点的坐标.该定位模型直接采用了射频信号对未知点进行定位,不但避免了一些range-based定位模型中出现的误差叠加等问题,而且还降低了计算复杂度.最后,借助NS-2仿真手段对该定位模型进行了验证.结果表明,该定位模型具有较高的性能,适合无线传感器网络应用.

地震定位研究综述

综述了各种地震定位方法的基本原理 ,重点介绍了Geiger的经典方法以及在此基础上建立的各种线性方法 :联合定位法 ,相对定位法 ,和最新的双重残差法 ;对每一种方法的应用情况 ,尤其是国内的工作做了总结 ;同时也指出了各种方法的特点 ,并进行了相应的比较 .此外 ,还简要介绍了空间域的定位方法和各种非线性定位方法 .

基于光纤光栅传感器的结构故障定位方法

提出了一种实现结构故障定位和故障实时监测的新方法。该方法利用光纤光栅传感网络测量结构应变,得到结构的挠度矩阵,分析故障前后挠度矩阵变化,计算得出故障定位向量,进而确定损伤区域,实现了结构故障准确定位和健康状况实时监测。实验结果表明,上述方法大大提高了故障定位的准确度和实时性。

基于Hough变换圆检测的人眼定位方法改进

对基于Hough变换圆检测的人眼定位方法进行了改进,借助积分投影定位人眼坐标时求得的灰度特征值,给出了一种快捷准确的眼睛定位方法。采用基于灰度积分投影的方法粗定位人眼,求得大致的虹膜半径、中心坐标和虹膜区域等;再采用"最小外接矩形法"估算待检测圆的圆心及半径,运用Hough变换检测圆的方法精确检测出虹膜。在VPM642实验平台上,使用C语言进行了编程实现。实验结果表明,该人眼定位方法有很好的检测效果,人眼定位精度达到93.5%。

夹具自动化设计中定位方案的生成式设计方法

为提高金属切削加工的精度,研究了计算机辅助夹具设计系统在定位方案自动化设计中的应用,建立了定位方案的生成式逐点设计方法。基于齐次线性方程组解的存在性,建立了定位正确性的理论条件,并根据几何空间约束条件,推出了定位正确性的工艺条件。基于分布迭代思想,提出了逐个选择定位基准并在其上逐个布局定位点的生成式逐点设计方法。通过典型实例讨论了该方法的分析应用过程。

对不受波速影响的输电线路单端行波法故障测距的探讨

在不受波速影响的行波法测距研究中,必须注意研究暂态初始行波、故障点反射波、对端母线反射波相互间的极性关系。而波形处理工具也将影响测距结果。该文通过分析故障初始行波、故障点反射波、对端母线反射波的极性关系来区别不同的行波分量,以暂态电流行波为分析对象,并用数学形态学检测故障波形,对不受波速影响的单端测距算法进一步研究。

超声横切扫描定位在肥胖患者硬膜外穿刺中的应用

目的评估超声横切扫描定位在肥胖患者硬膜外穿刺应用的可行性及应用前景。方法选择76例拟行硬膜外穿刺的肥胖患者。随机分为传统定位组（c组）和超声横切扫描定位组（u组）,每组各38例。c组采用常规方法进行定位穿刺,u组采用超声成像（横切扫描,高清晰12L5高频电子线阵探头）定位脊柱正中线、所要穿刺椎间隙并测量皮肤至硬膜外间隙的距离（超声深度,UD）。穿刺成功后,利用标记有刻度的硬膜外穿刺针测量经皮肤到达硬膜外间隙的深度（进针深度,ND）。观察两组穿刺时间、成功率,术后腰痛发生率等指标以及u组UD和ND并进行比较。结果 76例肥胖患者中,u组穿刺时间比c组明显缩短（P〈0.05）,38例肥胖患者均穿刺成功,成功率为100.0%;术后腰痛并发症发生率也低于c组。c组有3例下肢手术患者穿刺失败改全身麻醉。超声深度为（5.76±0.78）cm（4.4-8.7 cm）,而进针深度为（5.77±0.76）cm（4.5~8.8 cm）,两者行直线回归分析（r=0.571）,相关性较好。结论经超声横切扫描定位的肥胖患者硬膜外穿刺成功率高,穿刺时间短,并发症少,安全性高,这提示超声横切扫描法可以为肥胖患者硬膜外穿刺提供可靠的定位标志。

多重相对定位法和波形相关校正及其应用

阐述了地震相对定位法的原理和方法 ,给出了Pg ,Sg ,P11,S11和Pn 5种震相的走时差方程 .运用多重相对定位法和波形互相关技术 ,对 1996年 12月 16日发生的顺义地震的余震震群进行重新定位 ,同时使用多种震相 ,对深度进行约束 ;并对传统的绝对定位法、多重相对定位法和波形互相关技术的结果进行比较 .

基于参数估计的双端不同步故障测距算法

提出一种利用双端不同步采样数据并基于线路参数估计的故障测距算法,将输电线路参数、两端数据采样非同步误差角和故障距离作为未知量,利用故障时线路两端的非同步采样得到的电压和电流,通过牛顿-拉夫逊法求解非线性方程得到这些未知量。并将故障测距结果采用故障距离占线路全长的比例来表示,可以避免输电线路受温度影响产生长度变化导致的故障定位误差。利用线路杆塔在线路上所处的位置来估测故障点位置,更方便查找故障点。该算法减小了因线路参数不准确所带来的测距误差,仿真结果和实际数据验证表明该算法具有较高的测距精度。

一种基于模糊逻辑的室内定位方法

提出一种包含两层模糊逻辑的室内定位方法,第一层模糊逻辑用来计算检测点与参考点之间的相似程度;第二层模糊逻辑综合考虑检测点RSS矢量值与参考点RSS矢量值的欧氏距离和相似程度,计算检测点的位置坐标。在仿真实验中,用无线路由器构建室内无线网络,以采集到的Wi-Fi信号强度数据为基础,将提出的方法与常用室内定位算法的定位精度进行对比,验证了所提方法的有效性和精确性。

基于双层规划的农资供应链覆盖率优化

结合农资供应链的特点确定农资供应链工厂的数量、位置、规模和分配,构建双层规划模型。该模型以顾客覆盖最大化为基础、选址总利润最大为目标,引入时间和距离的敏感度变量以反映客户在选择供应商时对运输距离和产品价格的敏感程度,优化农资供应链工厂对分销商的覆盖率问题.上层从决策者出发,以工厂利润最大为目标;下层从顾客角度出发,考虑市场竞争,以对分销商的最大覆盖率为目标.将模型应用于具体农资企业,用遗传算法求解模型,验证模型的有效性.

需求不确定的电动汽车换电站选址鲁棒模型

在电动汽车换电站选址问题中,用户充电需求是重要的输入参数,而需求受到技术发展、电动汽车保有量、国家相关政策等因素的影响,通常较难准确预测。假设交通网络上用户需求是不确定的,利用基约束鲁棒优化方法提出基于用户路径流量不确定的换电站选址鲁棒模型,并将鲁棒模型转换为等价的线性规划。最后应用Nguyen-Dupius网络作为数值算例进行分析,结果表明当解的鲁棒水平较低时,通过适当增加选址成本,可以较大程度地提高解的鲁棒性。同时对模型的重要参数作灵敏性分析,随着鲁棒水平的提高,换电站选址成本对路径流量的波动越来越敏感,续航里程的改变对换电站选址策略影响较大。