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Fragility of disconnect switch subjected to random earthquake ground motions 被引量:1
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作者 吕宝龙 陈玲俐 叶志明 《Journal of Shanghai University(English Edition)》 CAS 2011年第3期180-184,共5页
A fragility calculation scheme is estabtished in this paper for porcelain-type equipments subjected to random earthquake ground motions. All steps of the method are illustrated by the seismic damage analysis of GW4-11... A fragility calculation scheme is estabtished in this paper for porcelain-type equipments subjected to random earthquake ground motions. All steps of the method are illustrated by the seismic damage analysis of GW4-110 disconnect switch. The model of the equipment is built applying the finite element method with flexible joints, and the seismic response of the equipment is analyzed using elastic time history method. On the base, according to the strength damage index and Monte-Carlo Method, the seismic damage ratios are counted and the seismic fragility curves are presented. Then the seismic damage of GW4-110 disconnect switch can be predicted. 展开更多
关键词 disconnect switch FRAGILITY random earthquake ground motion strength damage index
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Measuring the Qatar-Kazeron Fault Dip Using Random Finite Fault Simulation of September 27, 2010 Kazeron Earthquake and Analytical Signal Map of Satellite Magnetic Data 被引量:1
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作者 Soraya Dana Mahmood Almasian +2 位作者 Abdolmajid Asadi Mohsen Pourkermani Manouchehr Goreshi 《Open Journal of Geology》 2015年第2期73-82,共10页
In this research the fault parameters causing the September 27, 2010 Kazeron Earthquake with a magnitude of MW = 5.8 (BHRC) were determined using the random finite fault method. The parameters were recorded by 27 acce... In this research the fault parameters causing the September 27, 2010 Kazeron Earthquake with a magnitude of MW = 5.8 (BHRC) were determined using the random finite fault method. The parameters were recorded by 27 accelerometer stations. Simulation of strong ground motion is very useful for areas about which little information and data are available. Considering the distribution of earthquake records and the existing relationships, for the fault plane causing the September 27, 2010 Kazeron Earthquake the length of the fault along the strike direction and the width of the fault along the dip direction were determined to be 10 km and 7 km, respectively. Moreover, 10 elements were assumed along the length and 7 were assumed along the width of the plane. Research results indicated that the epicenter of the earthquake had a geographic coordination of 29.88N - 51.77E, which complied with the results reported by the Institute of Geophysics Tehran University (IGTU). In addition, the strike and dip measured for the fault causing the Kazeron Earthquake were 27 and 50 degrees, respectively. Therefore, the causing fault was almost parallel to and coincident with the fault. There are magnetic discontinuities on the analytical signal map with a north-south strike followed by a northwest-southeast strike. The discontinuities are consistent with the trend of Kazeron fault but are several kilometers away from it. Therefore, they show the fault depth at a distance of 12 km from the fault surface. 展开更多
关键词 Kazeron earthquake ANALYTICAL SIGNAL MAP random Finite FAULT Method earthquake Simulation
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Karhunen-loéve expansion for random earthquake excitations
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作者 He Jun 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2015年第1期77-84,共8页
This paper develops a trigonometric-basis-fimction based Karhunen-Loeve (KL) expansion for simulating random earthquake excitations with known covariance functions. The methods for determining the number of the KL t... This paper develops a trigonometric-basis-fimction based Karhunen-Loeve (KL) expansion for simulating random earthquake excitations with known covariance functions. The methods for determining the number of the KL terms and defining the involved random variables are described in detail. The simplified form of the KL expansion is given, whereby the relationship between the KL expansion and the spectral representation method is investigated and revealed. The KL expansion is of high efficiency for simulating long-term earthquake excitations in the sense that it needs a minimum number of random variables, as compared with the spectral representation method. Numerical examples demonstrate the convergence and accuracy of the KL expansion for simulating two commonly-used random earthquake excitation models and estimating linear and nonlinear random responses to the random excitations. 展开更多
关键词 Karhunen-loeve expansion trigonometric basis function Galerkin method random earthquake excitation random response
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Self-organized Criticality in an Earthquake Model on Random Network
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作者 ZHANG Duan-Ming SUN Fan YU Bo-Ming PAN Gui-Jun SUN Hong-Zhang YIN Yah-Ping LI Rui SU Xiang-Ying 《Communications in Theoretical Physics》 SCIE CAS CSCD 2006年第2期293-296,共4页
A simplified Olami-Feder-Christensen model on a random network has been studied. We propose a new toppling rule -- when there is an unstable site toppling, the energy of the site is redistributed to its nearest neighb... A simplified Olami-Feder-Christensen model on a random network has been studied. We propose a new toppling rule -- when there is an unstable site toppling, the energy of the site is redistributed to its nearest neighbors randomly not averagely. The simulation results indicate that the model displays self-organized criticality when the system is conservative, and the avalanche size probability distribution of the system obeys finite size scaling. When the system is nonconservative, the model does not display scaling behavior. Simulation results of our model with different nearest neighbors q is also compared, which indicates that the spatial topology does not alter the critical behavior of the system. 展开更多
关键词 self-organized criticality earthquake model finite size scaling random network
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Influence of Inhomogeneity on Critical Behavior of Earthquake Model on Random Graph
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作者 ZHANG Duan-Ming SUN Fan YU Bo-Ming PAN Gui-Jun YIN Yah-Ping LI Rui SU Xiang-Ying 《Communications in Theoretical Physics》 SCIE CAS CSCD 2006年第2X期261-264,共4页
We consider the earthquake model on a random graph. A detailed analysis of the probability distribution of the size of the avalanches will be given. The model with different inhomogeneities is studied in order to comp... We consider the earthquake model on a random graph. A detailed analysis of the probability distribution of the size of the avalanches will be given. The model with different inhomogeneities is studied in order to compare the critical behavior of different systems. The results indicate that with the increase of the inhomogeneities, the avalanche exponents reduce, i.e., the different numbers of defects cause different critical behaviors of the system. This is virtually ascribed to the dynamical perturbation. 展开更多
关键词 self-organized criticality earthquake model critical behavior POWER-LAW finite size scaling random network
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Modal identification to non-stationary random excitation based on wavelet transform and co-integration theory
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作者 杜秀丽 汪凤泉 《Journal of Southeast University(English Edition)》 EI CAS 2007年第4期583-587,共5页
A kind of method of modal identification subject to ambient excitation is presented. A new synthesis stationary signal based on structural response wavelet transform and wavelet coefficient processes co-integration is... A kind of method of modal identification subject to ambient excitation is presented. A new synthesis stationary signal based on structural response wavelet transform and wavelet coefficient processes co-integration is obtained. The new signal instead of structural response is used in identifying the modal parameters of a non- stationary system, combined with the method of modal identification under stationary random excitation-the NExT method and the adjusted continuous least square method. The numerical results show that the method can eliminate the non-stationarity of structural response subject to non-stationary random excitation to a great extent, and is highly precise and robust. 展开更多
关键词 modal identification wavelet transform non-stationary random excitation CO-INTEGRATION NExT method
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Spatio-temporal point pattern analysis on Wenchuan strong earthquake 被引量:3
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作者 Peijian Shi Jie Liu Zhen Yang 《Earthquake Science》 CSCD 2009年第3期231-237,共7页
For exploring the aftershock occurrence process of the 2008 Wenchuan strong earthquake, the spatio-temporal point pattern analysis method is employed to study the sequences of aflershocks with magnitude M≥4.0, M≥4.5... For exploring the aftershock occurrence process of the 2008 Wenchuan strong earthquake, the spatio-temporal point pattern analysis method is employed to study the sequences of aflershocks with magnitude M≥4.0, M≥4.5, and M≥5.0. It is found that these data exhibit the spatio-temporal clustering on a certain distance scale and on a certain time scale. In particular, the space-time interaction obviously strengthens when the distance is less than 60 km and the time is less than 260 h for the first two aftershock sequences; however, it becomes strong when the distance scale is less than 80 km and the time scale is less than 150 h for the last aftershock sequence. The completely spatial randomness analysis on the data regardless of time component shows that the spatial clustering of the aftershocks gradually strengthens on the condition that the distance is less than 60 km. The results are valuable for exploring the occurrence rules of the Wenchuan strong earthquake and for predicting the aftershocks. 展开更多
关键词 Wenchuan earthquake completely spatial randomness spatio-temporal point pattern K-FUNCTION
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Research on the Application of Time Structure Variation Analysis to the Jiashi-Bachu Earthquake Swarm Sequence 被引量:2
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作者 Yang Xin Long Haiying +1 位作者 Shangguan Wenming Nie Xiaohong 《Earthquake Research in China》 2008年第3期251-264,共14页
In 1997 - 2003, 27 earthquakes with M≥ 5.0 occurred in the Jiashi-Bachu area of Xinjiang. It was a rare strong earthquake swarm activity. The earthquake swarm has three time segments of activity with different magnit... In 1997 - 2003, 27 earthquakes with M≥ 5.0 occurred in the Jiashi-Bachu area of Xinjiang. It was a rare strong earthquake swarm activity. The earthquake swarm has three time segments of activity with different magnitudes in the years 1997, 1998 and 2003. In different time segments, the seismic activity showed strengthenin-qguiet changes in various degrees before earthquakes with M ≥ 5.0. In order to delimitate effectively the precursory meaning of the clustering (strengthening) quiet change in sequence and to seek the time criterion for impending prediction, the nonlinear characteristics of seismic activity have been used to analyze the time structure characteristics of the earthquake swarm sequence, and further to forecast the development tendency of earthquake sequences in the future. Using the sequence catalogue recorded by the Kashi Station, and taking the earthquakes with Ms≥ 5.0 in the sequence as the starting point and the next earthquake with Ms = 5.0 as the end, statistical analysis has been performed on the time structure relations of the earthquake sequence in different stages. The main results are as follows: (1) Before the major earthquakes with M ≥ 5.0 in the swarm sequence, the time variation coefficient (δ-value) has abnormal demonstrations to different degrees. (2) Within 10 days after δ= 1, occurrence of earthquakes with M ≥ 5.0 in the swarm is very possible. (3) The time variation coefficient has three types of change. (4) The change process before earthquakes with M5.0 is similar to that before earthquakes with M6.0, with little difference in the threshold value. In the earthquake swarm sequence, it is difficult to delimitate accurately the attribute of the current sequences (foreshock or aftershock sequence) and to judge the magnitude of the follow-up earthquake by δ-value. We can only make the judgment that earthquakes with M5.0 are likely to occur in the sequence. (5) The critical clustering characteristics of the sequence are hierarchical. Only corresponding to a certain magnitude can the sequence have the variation state of critical clustering. (6) The coefficient of the time variation has a clear meaning in physics. After the clustering-quiet state of earthquake activity has appeared, it can describe clearly the randomness of the seismogenic system. Furthermore, it can efficiently clarify whether or not the clustering quiescence variation is of some prognostic meaning. In the case that the earthquake frequency attenuation is essentially normal (h 〉 1 ) and there is no remarkable clustering-quiescence state, it is still possible to discover the abnormal change of the sequence from the time variation coefficient. On the contrary, in the later period of swarm activity, after the appearance of many seismic quiescence phenomena, this coefficient did not appear abnormally, even when h 〈 1, suggesting that the δ-value diagnosis is more universal. 展开更多
关键词 Time variation coefficient earthquake clustering randomNESS Time structure ofearthquake sequence Jiashi earthquake swarm
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Probability forecast of earthquake magnitude in Chinese mainland before A.D. 2005
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作者 王晓青 傅征祥 蒋铭 《Acta Seismologica Sinica(English Edition)》 CSCD 1996年第4期13-20,共8页
A probability forecast method of earthquake magnitude, based on the earthquake frequency magnitude relation and the model of Bernoulli′s random independent trial, is applied to the earthquake risk assessmen... A probability forecast method of earthquake magnitude, based on the earthquake frequency magnitude relation and the model of Bernoulli′s random independent trial, is applied to the earthquake risk assessment of seismic zones in China's Mainland before A.D.2005 in the paper. The forecasting results indicate that the probabilities of earthquake occurrence with magnitude 5 in seismic zones before 2005 are estimated to be over 0.7 in common and 0.8 in most zones; and from 0.5 to 0.7 with M =6; the maximum probability of earthquake occurrence with magnitude 7 is estimated at 0.858, which is also expected in Shanxi seismic zone. In west China's Mainland, earthquakes with magnitude 6 are expected to occur in most seismic zones with high probability (over 0.9 in general) ; the relatively high probabilities of earthquake occurrence (more than 0.7) with magnitude 7 are expected in the seismic zones surrounding the Qinghai Tibet plateau and south Tianshan seismic zone. A discussion about the result confidence and the relationship between the estimated probability and the possible annual rate of earthquake occurrence is made in the last part of the paper. 展开更多
关键词 probability forecast of earthquake magnitude Bernoulli′s random independent trial.
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Parameters Identification of Stochastic Nonstationary Process Used in Earthquake Modelling
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作者 Giuseppe Carlo Marano Mariantonietta Morga Sara Sgobba 《International Journal of Geosciences》 2013年第2期290-301,共12页
This paper proposes a new deterministic envelope function to define non-stationary stochastic processes modeling seismic ground motion accelerations. The proposed envelope function modulates the amplitude of the time ... This paper proposes a new deterministic envelope function to define non-stationary stochastic processes modeling seismic ground motion accelerations. The proposed envelope function modulates the amplitude of the time history of a stationary filtered white noise to properly represent the amplitude variations in the time histories of the ground motion accelerations. This function depends on two basic seismological indices: the Peak Ground Acceleration (PGA) and the kind of soil. These indices are widely used in earthquake engineering. Firstly, the envelope function is defined analytically from the Saragoni Hart’s function. Then its parameters are identified for a set of selected real records of earthquake collected in PEER Next Generation Attenuation database. Finally, functions of the parameters depending on the Peak Ground Acceleration and the kind of soil are defined from these identified values of the parameters of the envelope function through a regression analysis. 展开更多
关键词 SEISMIC Analysis random Vibrations non-stationary Process
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Non-Stationary Random Process for Large-Scale Failure and Recovery of Power Distribution
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作者 Yun Wei Chuanyi Ji +3 位作者 Floyd Galvan Stephen Couvillon George Orellana James Momoh 《Applied Mathematics》 2016年第3期233-249,共17页
This work applies non-stationary random processes to resilience of power distribution under severe weather. Power distribution, the edge of the energy infrastructure, is susceptible to external hazards from severe wea... This work applies non-stationary random processes to resilience of power distribution under severe weather. Power distribution, the edge of the energy infrastructure, is susceptible to external hazards from severe weather. Large-scale power failures often occur, resulting in millions of people without electricity for days. However, the problem of large-scale power failure, recovery and resilience has not been formulated rigorously nor studied systematically. This work studies the resilience of power distribution from three aspects. First, we derive non-stationary random processes to model large-scale failures and recoveries. Transient Little’s Law then provides a simple approximation of the entire life cycle of failure and recovery through a queue at the network-level. Second, we define time-varying resilience based on the non-stationary model. The resilience metric characterizes the ability of power distribution to remain operational and recover rapidly upon failures. Third, we apply the non-stationary model and the resilience metric to large-scale power failures caused by Hurricane Ike. We use the real data from the electric grid to learn time-varying model parameters and the resilience metric. Our results show non-stationary evolution of failure rates and recovery times, and how the network resilience deviates from that of normal operation during the hurricane. 展开更多
关键词 RESILIENCE non-stationary random Process Power Distribution Dynamic Queue Transient Little’s Law Real Data
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非平稳随机地震激励下多层框架-摇摆墙结构的响应分析
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作者 宋英华 马建 张远进 《中国安全科学学报》 CAS CSCD 北大核心 2024年第6期48-56,共9页
框架-摇摆墙是一种可有效提高建筑抗震性和韧性的组合自复位结构,为充分了解其在地震下的随机响应特性,构建多自由度框架-摇摆墙结构的简化非线性方程,并利用等效线性化,基于响应的伪谐波行为假设,构建含时变参数的等效线性动力方程;基... 框架-摇摆墙是一种可有效提高建筑抗震性和韧性的组合自复位结构,为充分了解其在地震下的随机响应特性,构建多自由度框架-摇摆墙结构的简化非线性方程,并利用等效线性化,基于响应的伪谐波行为假设,构建含时变参数的等效线性动力方程;基于随机平均的原理,得出控制响应幅值概率密度函数(PDF)的时间演变形式的福克-普朗克-科尔莫哥洛夫(FPK)方程,最终得出随机响应时间相关方差的一阶微分方程;并以某教学楼一榀框架为样本构建算例模型进行验证。结果表明:近似解析方法具有优异的精确度,在保证随机响应时间相关方差准确性的前提下,相对于传统的蒙特卡罗模拟(MCS)方法可提高分析的效率;在可分离形式和不可分离形式的非平稳地震动功率谱模型的结果中,随机响应方差曲线趋势与随机地震激励的形式相关,且在分段式调制非平稳谱作用下其分段点表现出很明显的不平滑现象;不同类型的随机地震激励扰动下的结果证明了此方法优异的适用性。 展开更多
关键词 非平稳 随机地震 框架-摇摆墙结构 响应分析 随机平均
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随机地震下耗能构件关键参数对自复位桥墩地震响应的影响
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作者 蒋丽忠 付豪 +5 位作者 周旺保 聂磊鑫 王晓婵娟 蒋智勇 赵坚 蒋星宇 《中南大学学报(自然科学版)》 EI CAS CSCD 北大核心 2024年第10期3779-3786,共8页
自复位桥墩具有能够在震后快速恢复桥梁的使用功能。为了得到不同参数下耗能构件对于自复位桥墩地震响应指标的影响,取8度区的高速铁路双线简支箱梁桥作为研究对象,从Peer数据库中筛选出具有随机特征的40条地震波对有限元模型进行非线... 自复位桥墩具有能够在震后快速恢复桥梁的使用功能。为了得到不同参数下耗能构件对于自复位桥墩地震响应指标的影响,取8度区的高速铁路双线简支箱梁桥作为研究对象,从Peer数据库中筛选出具有随机特征的40条地震波对有限元模型进行非线性时程分析,通过假设检验的统计学方法得到地震响应指标的分布规律和具有95%保证率的桥墩地震响应指标上界值。研究结果表明:在随机地震作用下,自复位桥墩各地震响应指标均服从正态分布;自复位桥墩在地震过程中具有较小的残余位移,随着耗能构件初始刚度和屈服力增加,墩顶最大位移逐渐减小,混凝土压应变和钢筋拉应变逐渐增大;在考虑地震随机性基础上,提出基于概率保证率的自复位桥梁耗能构件初始刚度和屈服力的合理取值范围,可为合理设置自复位桥墩耗能构件关键参数提供参考。 展开更多
关键词 震后快速修复 铁路自复位桥墩 耗能构件 随机地震 地震响应指标
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高速铁路自复位摇摆桥墩抗震性能分析
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作者 周旺保 王晓婵娟 +3 位作者 聂磊鑫 蒋丽忠 付豪 蒋智勇 《中国铁道科学》 EI CAS CSCD 北大核心 2024年第3期38-49,共12页
基于OpenSEES平台分别建立4跨高速铁路传统简支梁桥和摇摆桥墩简支梁桥系统的有限元模型,并依据摇摆桥墩的基本抗震设防目标,设计摇摆桥墩耗能构件的面积和承载力。在考虑地震动随机性基础上,进行自复位摇摆桥墩在高铁桥梁系统中的抗震... 基于OpenSEES平台分别建立4跨高速铁路传统简支梁桥和摇摆桥墩简支梁桥系统的有限元模型,并依据摇摆桥墩的基本抗震设防目标,设计摇摆桥墩耗能构件的面积和承载力。在考虑地震动随机性基础上,进行自复位摇摆桥墩在高铁桥梁系统中的抗震性能研究。结果表明:罕遇地震下自复位摇摆耗能装置能够有效降低墩底最大弯矩,减震率达20.26%,进而减少墩身损伤,但碰撞效应使墩底最大轴力放大了74.7%;墩底耗能构件基本进入塑性但未完全被破坏,可实现震后快速修复;摇摆桥墩的最大墩顶位移比传统桥墩增加了66%,但位移组成中可自复位的刚体旋转变形远大于弯曲变形,因此震后残余位移减少了35%;摇摆耗能机制对支座最大变形的减震率达12.3%,使主梁最大变形增大了约49%,但对其残余变形的影响在1 mm内;轨道约束会削弱桥墩摇摆行为,使墩顶最大位移减少了14%,但对墩顶残余位移无明显影响。 展开更多
关键词 高速铁路 自复位摇摆桥墩 随机地震 韧性抗震设计 抗震性能
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甘肃积石山县M_(S)6.2地震同震地质灾害发育特征与易发性评价 被引量:3
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作者 刘帅 何斌 +11 位作者 王涛 刘甲美 曹佳文 王浩杰 张帅 李坤 李冉 张永军 窦晓东 吴中海 陈鹏 丰成君 《地质力学学报》 CSCD 北大核心 2024年第2期314-331,共18页
2023年12月18日,甘肃积石山县发生M_(S)6.2地震,诱发的同震地质灾害严重威胁到人民生命和财产安全,因此及时总结分析同震地质灾害发育规律并进行县域易发性评价,对支撑震后恢复重建至关重要。通过应急排查、野外调查与结果分析,对同震... 2023年12月18日,甘肃积石山县发生M_(S)6.2地震,诱发的同震地质灾害严重威胁到人民生命和财产安全,因此及时总结分析同震地质灾害发育规律并进行县域易发性评价,对支撑震后恢复重建至关重要。通过应急排查、野外调查与结果分析,对同震地质灾害发育特征进行分析总结;以震后排查的同震新增和加剧隐患点为分析样本,采用Pearson相关性系数与随机森林Gini系数分析方法,筛选了15个影响因子,并运用机器学习-随机森林模型对积石山县进行同震地质灾害易发性评价。结果表明,震区同震地质灾害总体发育程度不强,规模以小型为主,崩滑流地质灾害隐患可分为3大类、8个亚类,绝大部分分布在黄土丘陵区;积石山县同震地质灾害随机森林模型易发性评价(AUC=0.961)结果显示,极高易发区面积占比约8.67%,主要分布在胡林家乡、徐扈家乡、柳沟乡等乡镇,且县域及各乡镇易发性分级结构与隐患点密度分布吻合程度高。评价结果对已有排查隐患点以外的震裂山体或潜在崩滑流灾害具有重要指示作用,可为积石山县灾后恢复重建规划提供决策支撑,同时将Pearson相关性系数与随机森林Gini系数的影响因子筛选方法及机器学习模型——随机森林应用于易发性评价中,可为其他山地丘陵区地质灾害易发性评价提供参考。 展开更多
关键词 积石山地震 同震 地质灾害 易发性 随机森林 影响因子
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基于随机森林的地震灾害直接经济损失评估研究——以中国西部地区为例 被引量:1
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作者 刘金平 姜立新 +1 位作者 杨天青 刘钦 《中国地震》 北大核心 2024年第2期355-367,共13页
为快速评估地震直接经济损失,针对我国西部地区,尝试采用随机森林机器学习回归算法,以1993—2017年震害数据为基础,结合各年份经济数据与抗震设计数据,经特征选择与参数优化后,进行模型的训练与测试。实验结果表明,在减少模型输入特征... 为快速评估地震直接经济损失,针对我国西部地区,尝试采用随机森林机器学习回归算法,以1993—2017年震害数据为基础,结合各年份经济数据与抗震设计数据,经特征选择与参数优化后,进行模型的训练与测试。实验结果表明,在减少模型输入特征的情况下,优化后的随机森林模型可得到更优的评估结果。通过删除含有缺失特征样本的数据预处理方法,评估模型的决定系数R2达到0.86,优于中值补齐缺失特征数据预处理下的评估模型,更适用于地震直接经济损失的评估。实例验证表明该模型评估结果与实际经济损失有较好的一致性,可为抗震救灾提供决策支持。 展开更多
关键词 地震直接经济损失 随机森林 特征选择 超参数优化
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TVAR Time-frequency Analysis for Non-stationary Vibration Signals of Spacecraft 被引量:7
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作者 杨海 程伟 朱虹 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2008年第5期423-432,共10页
Predicting the time-varying auto-spectral density of a spacecraft in high-altitude orbits requires an accurate model for the non-stationary random vibration signals with densely spaced modal frequency. The traditional... Predicting the time-varying auto-spectral density of a spacecraft in high-altitude orbits requires an accurate model for the non-stationary random vibration signals with densely spaced modal frequency. The traditional time-varying algorithm limits prediction accuracy, thus affecting a number of operational decisions. To solve this problem, a time-varying auto regressive (TVAR) model based on the process neural network (PNN) and the empirical mode decomposition (EMD) is proposed. The time-varying system is tracked on-line by establishing a time-varying parameter model, and then the relevant parameter spectrum is obtained. Firstly, the EMD method is utilized to decompose the signal into several intrinsic mode functions (IMFs). Then for each IMF, the PNN is established and the time-varying auto-spectral density is obtained. Finally, the time-frequency distribution of the signals can be reconstructed by linear superposition. The simulation and the analytical results from an example demonstrate that this approach possesses simplicity, effectiveness, and feasibility, as well as higher frequency resolution. 展开更多
关键词 non-stationary random vibration time-frequency distribution process neural network empirical mode decomposition
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基于随机森林方法的地震损失预测
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作者 梁梓豪 苗鹏宇 +1 位作者 Wang Jianming 王自法 《地震学报》 CSCD 北大核心 2024年第4期649-662,共14页
针对现有的基于实际震害评估的大多研究仅限于某特定区域和某种结构类型,且所采用的数据样本量也十分有限,本文基于随机森林模型,采用2011年3月11日东日本MW9.0地震的37万8037条建筑物实际震害数据,利用美国应用技术协会发布的地震震害... 针对现有的基于实际震害评估的大多研究仅限于某特定区域和某种结构类型,且所采用的数据样本量也十分有限,本文基于随机森林模型,采用2011年3月11日东日本MW9.0地震的37万8037条建筑物实际震害数据,利用美国应用技术协会发布的地震震害等级划分标准(ATC-13)预测了建筑物地震破坏所引起的损失,对建筑物损失的影响因素进行了特征重要性分析。结果显示:通过合成少数类过采样技术(SMOTE)解决数据不均衡和贝叶斯优化超参数之后,得到了基于随机森林的预测模型测试集的准确率为68.8%,轻微破坏、中等破坏、严重破坏、倒塌等四种破坏等级的召回率分别为65.0%,53.6%,74.8%,81.8%;考虑生命安全性能将模型转换为二分类之后,模型准确率进一步提高至87.5%,极大地改善了现有研究应用于建筑损失预测中数据样本量受限、数据不均衡等导致的最严重破坏等级精度低等问题。对随机森林模型特征重要性的研究表明:震中距、峰值加速度和vS30是最影响模型输出的特征。 展开更多
关键词 建筑损失数据 随机森林算法 地震损失预测 特征重要性
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基于机器学习随机森林算法的地震序列类型判定研究
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作者 王锦红 蒋海昆 《中国地震》 北大核心 2024年第3期517-531,共15页
基于1970-2021年中国内地地震目录、地震序列目录和历史地震震源机制资料,构建地震序列类型判定训练、检验特征样本数据集,将地震序列标签分为多震型、主余型、孤立型三类。采用特征递归消除-随机森林(RFE-RF)机器学习算法建立地震特征... 基于1970-2021年中国内地地震目录、地震序列目录和历史地震震源机制资料,构建地震序列类型判定训练、检验特征样本数据集,将地震序列标签分为多震型、主余型、孤立型三类。采用特征递归消除-随机森林(RFE-RF)机器学习算法建立地震特征参数和地震序列类型之间的非线性映射关系,对震后3个不同时间节点的地震序列类型进行早期预测,并对特征重要性进行讨论。结果显示,数据预处理方法对模型分类性能有重要影响,同类样本中位值补齐缺失特征并采用随机重采样方法预处理可达到较高的分类预测效果。对分类结果的交叉检验结果显示,在震后1天,三类样本的总体报准率可达0.93。考察模型最优特征子集随时间的变化可见,在地震刚发生时(即缺乏地震序列资料数据的情况下),相对于传统的历史地震序列类比,主震震源机制相关参数以及主震震源机制P轴方位相对于附近区域应力场的偏差等相关参数具有更大的分类贡献率。随着震后时间的延长,序列相关特征成为地震序列类型判定的主要因素。在震后3天,在可能已发生最大余震的地震序列数据集中,主震与最大余震震级差成为判定地震序列类型的关键因素。相较于单一的随机森林(RF)模型,RFE-RF模型的在震后1天测试集中报准率提高了0.41,能够更有效地对地震序列类型加以区分。 展开更多
关键词 地震序列类型判定 中国内地 随机森林 递归消除
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日本海沟S-net台网水平向海域板缘地震动模型研究
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作者 谭景阳 颜仕龙 +2 位作者 陈灯红 张齐 陈柳灼 《振动与冲击》 EI CSCD 北大核心 2024年第18期186-200,共15页
地震动反应谱预测模型是概率地震危险性分析的基础,该文基于日本海沟大型海底台网S-net的海域俯冲带板缘地震动数据库,建立了俯冲带地区的水平向海域板缘地震动预测模型,分析了板缘地震的海陆地震动模型差异。在地震动模型中考虑了与场... 地震动反应谱预测模型是概率地震危险性分析的基础,该文基于日本海沟大型海底台网S-net的海域俯冲带板缘地震动数据库,建立了俯冲带地区的水平向海域板缘地震动预测模型,分析了板缘地震的海陆地震动模型差异。在地震动模型中考虑了与场地信息有关的台站水深和沉积层厚度。由于海底台站的埋设方式不同,在模型中将台站按埋设和未埋设进行区分,通过回归分析和参数平滑建立了考虑震源类型、矩震级、震源深度、断层距、水深、沉积层厚度和埋设方式的水平向海域板缘地震动预测模型。通过对事件内残差进行分离,给出了研究区域的海底板缘模型单台标准差,可用于特定场点的概率地震危险性分析。该文的水平向海域板缘地震动模型可为考虑震源类型的海域区划和海域概率地震危险性分析提供参考。 展开更多
关键词 海域地震动 俯冲带板缘地震 预测模型 随机效应模型 海域工程
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