基于时间序列相似性匹配算法的研究

把匹配抽象时间序列相似性的方法引入到地震预报的应用中,结合大量地震历史源数据,地震领域的专家经验知识和相关成果基础上,提出了一种简化的抽象时间序列匹配模型.该模型在对海量数据进行预处理筛选的基础上再进行时间相似性匹配,增加了横向和纵向多方位地区和多方位时间段的匹配,不同时间差和阈值的匹配,并通过大量实验对该模型进行了反复验证,同时对我国地震频繁地区近几十年的地震历史数据进行了相似性匹配实验分析,取得了可信度较高的实验结果,实验结果验证了所给时间序列相似性匹配控制策略的有效性、实用性以及算法的优越性.     

RCR:一种面向金融时间序列的相似度量模型

在对我国证券市场交易数据的研究基础上,提出了一种新的面向金融时间序列的相似度量模型。此模型的数学定义清晰,易于计算机实现,能够有效完成形态搜索的自动化。给出了模型的形式化定义和模型的性质,并在实际股票交易数据上进行了相似性搜索实验,实验结果验证了模型的识别能力。     

基于MATLAB的BP神经网络模型在地震预报中的应用

根据人工神经网络模型,运用MATLAB的神经网络工具箱建立BP神经网络预测模型,以地震变化率作为神经网络的输入,对台湾地区和四川地区地震数据时间序列进行分析对大地震的发生时间进行预测.实验证明该模型用于地震预报的有效性和可行性,具有良好的应用价值.     

基于MATLAB的BP神经网络模型在地震预报中的应用

根据人工神经网络模型,运用MATLAB的神经网络工具箱建立BP神经网络预测模型,以地震变化率作为神经网络的输入,对台湾地区和四川地区地震数据时间序列进行分析对大地震的发生时间进行预测.实验证明该模型用于地震预报的有效性和可行性,具有良好的应用价值.     

基于OFC的仿真地震序列网络化特征对比分析

OFC模型通过模拟地震能量传递行为来认识地震的活动规律.为更加真实反映地震发生时的能量传递,用1992年美国加利福尼亚州地震数据抽象成的时空域网络替换传统二维规则网络OFC模型的底层网络.为了解仿真地震序列是否与真实地震数据具有相似性,将仿真地震序列网络化,与真实地震网络对比累积度分布的趋势,由此判断是否改进后的网络更接近真实地震网络.实验结果表明,时空域网络OFC模型产生的仿真地震序列和真实地震数据在宏观网络拓扑上具有一致性.     

基于节点相似性和链接次数组合时间序列的链接预测

针对现有方法利用网络信息相对割裂, 很难描述链接次数与相似性分数关系的问题, 提出一种动态网络中的链接预测方法, 用节点相似性分数和链接次数组合时间序列模型进行预测. 首先通过社区演化, 预测历史上各时间快照下节点间的相似性分数; 然后用二元时间序列模型将其与各时间快照下节点间的事实链接次数相结合, 判断下一个时间段内各节点对链接发生的可能性; 最后在Weibo Net Tweet微博转发数据集上进行测试. 实验结果表明, 该方法至少提高了5%的预测准确度, 证明了社区演化与链接预测之间的内在联系, 验证了二元时间序列模型的有效性.     

基于小波变换的多元时间序列相似性研究

多元时间序列由于多元性和变量间的相关性而趋于复杂.简单综述了时间序列研究方法,结合小波变换的降维和多尺度特性,以矩阵的Froenius加权平方范数为度量工具,提出了基于haar小波变换的多元时间序列间相似性匹配方法.实验数据表明,该方法能够有效的比较多元时间序列间的相似性程度.     

基于张量多线性PCA的多变量时间序列模式匹配

提出基于张量多线性PCA的多变量时间序列模式匹配方法,通过张量多线性PCA对多变量时间序列进行低维重构并获得其模式表示,然后利用Frobenius范数设计模式间的相似性度量.在四组公开的多变量时间序列数据集上进行实验,结果表明该方法的匹配准确率较高,时间开销较少,且适用于各种规模的数据集.     

基于相似度的装备数据聚合方法

现代战争需要对多源异构的装备数据进行高效集成。针对不同来源数据中装备名称不一致的问题,设计了装备数据的聚合模型和聚合流程,在综合分析现有算法的基础上,结合装备名称特点为该模型提供了一种新的相似度匹配算法,算法将Jaro-Winkler和最长公共子序列相结合,以提高匹配的精度。最后通过实验进行了验证,结果表明该算法与传统相似度算法相比具有较高的适配性和鲁棒性,可以为装备数据聚合工作提供有效支撑。     

一种有效的多元时间序列相似性度量算法分析

为验证Eros距离对MTS数据集相似性度量的有效性,针对不同MTS数据集进行了相似性搜索实验研究.结果表明:相对于其他的传统多元时间序列相似性度量,基于Eros距离的相似性度量方法比传统的方法在查全率-查准率上具有更大的优越性.     

Earthquake slip weakening and asperities explained by thermal pressurization

An earthquake occurs when a fault weakens during the early portion of its slip at a faster rate than the release of tectonic stress driving the fault motion. This slip weakening occurs over a critical distance, D(c). Understanding the controls on D(c) in nature is severely limited, however, because the physical mechanism of weakening is unconstrained. Conventional friction experiments, typically conducted at slow slip rates and small displacements, have obtained D(c) values that are orders of magnitude lower than values estimated from modelling seismological data for natural earthquakes. Here we present data on fluid transport properties of slip zone rocks and on the slip zone width in the centre of the Median Tectonic Line fault zone, Japan. We show that the discrepancy between laboratory and seismological results can be resolved if thermal pressurization of the pore fluid is the slip-weakening mechanism. Our analysis indicates that a planar fault segment with an impermeable and narrow slip zone will become very unstable during slip and is likely to be the site of a seismic asperity.     

Slip zone and energetics of a large earthquake from the Taiwan Chelungpu-fault Drilling Project

Determining the seismic fracture energy during an earthquake and understanding the associated creation and development of a fault zone requires a combination of both seismological and geological field data. The actual thickness of the zone that slips during the rupture of a large earthquake is not known and is a key seismological parameter in understanding energy dissipation, rupture processes and seismic efficiency. The 1999 magnitude-7.7 earthquake in Chi-Chi, Taiwan, produced large slip (8 to 10 metres) at or near the surface, which is accessible to borehole drilling and provides a rare opportunity to sample a fault that had large slip in a recent earthquake. Here we present the retrieved cores from the Taiwan Chelungpu-fault Drilling Project and identify the main slip zone associated with the Chi-Chi earthquake. The surface fracture energy estimated from grain sizes in the gouge zone of the fault sample was directly compared to the seismic fracture energy determined from near-field seismic data. From the comparison, the contribution of gouge surface energy to the earthquake breakdown work is quantified to be 6 per cent.     

Fault lubrication during earthquakes

The determination of rock friction at seismic slip rates (about 1?m?s(-1)) is of paramount importance in earthquake mechanics, as fault friction controls the stress drop, the mechanical work and the frictional heat generated during slip. Given the difficulty in determining friction by seismological methods, elucidating constraints are derived from experimental studies. Here we review a large set of published and unpublished experiments (～300) performed in rotary shear apparatus at slip rates of 0.1-2.6?m?s(-1). The experiments indicate a significant decrease in friction (of up to one order of magnitude), which we term fault lubrication, both for cohesive (silicate-built, quartz-built and carbonate-built) rocks and non-cohesive rocks (clay-rich, anhydrite, gypsum and dolomite gouges) typical of crustal seismogenic sources. The available mechanical work and the associated temperature rise in the slipping zone trigger a number of physicochemical processes (gelification, decarbonation and dehydration reactions, melting and so on) whose products are responsible for fault lubrication. The similarity between (1) experimental and natural fault products and (2) mechanical work measures resulting from these laboratory experiments and seismological estimates suggests that it is reasonable to extrapolate experimental data to conditions typical of earthquake nucleation depths (7-15?km). It seems that faults are lubricated during earthquakes, irrespective of the fault rock composition and of the specific weakening mechanism involved.     

地震中广义分维的计算结果

对某海域20年实测的地震数据分段进行广义分维计算，分析表明高q值的分维数在强震前后有明显差别.     

Seismology: speed and size of the Sumatra earthquake

Our seismological results reveal that Indonesia's devastating Sumatra-Andaman earthquake on 26 December 2004 was 2.5 times larger than initial reports suggested--second only to the 1960 Chilean earthquake in recorded magnitude. They indicate that it slowly released its energy by slip along a 1,200-km fault, generating a long rupture that contributed to the subsequent tsunami. Now that the entire rupture zone has slipped, the strain accumulated from the subduction of the Indian plate beneath the Burma microplate has been released, and there is no immediate danger of a similar tsunami being generated on this part of the plate boundary, although large earthquakes on segments to the south still present a threat.     

汤加火山的地震学研究

俯冲带的地震监测仍然是一个挑战，特别是对于人口稠密地区。2022年1月汤加的洪阿汤加—洪阿哈阿帕伊火山的喷发以及引发的地震凸显了这一需求的急迫性。综合汤加地震学观测，推测汤加部分火山近期仍有小规模喷发风险。选取2009—2010年覆盖汤加的海底地震仪台阵数据，应用机器学习算法进行数据处理，得到汤加火山岛链附近高分辨率的地震目录。     

CZ191型梳麻机预梳部分工艺研究

本文着重研究CZ191型梳麻机喂入预梳部分中,工艺参数改变时对生条质量的影响。采用了三因子二次通用旋转组合设计的试验方法,通过对生条中纤维平均长度、纤维长度不匀率、短纤维率、麻粒数、硬条数等指标的测量和分析,找出了喂入部分因子:喂入定量、分梳辊转速、分梳辊与喂麻针辊之间的隔距等对生条各指标的影响关系。在此基础上,采用多目标优化方法,找出了最佳的喂入部分的工艺参数。分析和讨论的结果表明,合理选择喂入预梳部分的工艺参数对提高梳理质量有重要意义。     

Fracture surface energy of the Punchbowl fault, San Andreas system

Fracture energy is a form of latent heat required to create an earthquake rupture surface and is related to parameters governing rupture propagation and processes of slip weakening. Fracture energy has been estimated from seismological and experimental rock deformation data, yet its magnitude, mechanisms of rupture surface formation and processes leading to slip weakening are not well defined. Here we quantify structural observations of the Punchbowl fault, a large-displacement exhumed fault in the San Andreas fault system, and show that the energy required to create the fracture surface area in the fault is about 300 times greater than seismological estimates would predict for a single large earthquake. If fracture energy is attributed entirely to the production of fracture surfaces, then all of the fracture surface area in the Punchbowl fault could have been produced by earthquake displacements totalling <1 km. But this would only account for a small fraction of the total energy budget, and therefore additional processes probably contributed to slip weakening during earthquake rupture.     

基于进化策略的实数域准零相关区序列生成算法

该文提出实数域准零相关区序列的概念,当信道延迟和同步误差之和不超过零相关区长度时,可以较为理想地消除CDM A系统的码间干扰和多址干扰。同时,基于进化策略设计了实数域准零相关区序列的搜索算法,与传统零相关区序列的生成算法相比,该算法可以在全局解空间进行优化搜索,而且生成的序列在序列周期和零相关区长度等参数上较少受到构造方法的限制,更方便于实际应用。     

汶川地震的岩石圈深部结构与动力学背景

中国西部地区由于受到印度板块向北推移挤压,青藏高原强烈变形,高原内部及其边缘的活断层上经常发生强烈地震,是大陆内部最活跃的地震区.汶川8级地震就发生在青藏高原东缘的松潘一甘孜地块与扬子地块交界的龙门山主中央断裂带上.作者利用面波层析成像、跨龙门山的被动源地震观测、爆破地震剖面的结果对震源附近的岩石圈结构和动力学特征进行研究,发现松潘一甘孜地块与扬子地块的岩石圈结构与性质有重大差异.扬子地块岩石圈显示为高速、坚固和稳定特性,而松潘-甘孜地块为低速、软弱及易于破碎.在松潘-甘孜地块中,中地壳内普遍存在一个低速层,它是引起中上地亮推覆运动的滑脱层,龙门山的推覆构造就是上部地壳仰冲的结果.汶川地震震源深度为14 km,正好位于龙门山推覆体的映秀-北川主中央断裂带上.