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Influence of span-to-depth ratio on dynamic response of vehicle-turnoutbridge system in high-speed railway
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作者 Chuanqing Dai Tao Xin +3 位作者 Shenlu Qiao Yanan Zhang Pengsong Wang Mahantesh M.Nadakatti 《High-Speed Railway》 2024年第1期30-41,共12页
For high-speed railways,the smoothness of the railway line significantly affects the operational speed of trains.When the train passes through the turnout on a long-span bridge,the wheel-rail impacts caused by the tur... For high-speed railways,the smoothness of the railway line significantly affects the operational speed of trains.When the train passes through the turnout on a long-span bridge,the wheel-rail impacts caused by the turnout structure irregularities,and the instability arising from the bridge's flexural deformation lead to a strong coupling effect in the vehicle-turnout-bridge system.This significantly affects both ride comfort and operational safety.For addressing this issue,the present study considered a long-span continuous rigid-frame bridge as an example and established a train-turnout-bridge coupled dynamic model of high-speed railway.Utilizing a selfdeveloped dynamic simulation program,the study analysed the dynamic response characteristics when the train passes through the turnouts on the bridge.It also investigated the influence of different span-to-depth ratios of the bridge on the vehicle dynamic response when the train passes through the main line and branch line of turnouts and then proposed a span-to-depth ratio limit value for a long-span continuous rigid-frame bridge.The research findings suggest that the changes in the span-to-depth ratio have a relatively minor impact on the train’s operational performance but significantly affect the dynamic characteristics of the bridge structure.Based on the findings and a comprehensive assessment of safety indicators,it is advisable to establish a span-to-depth ratio limit of 1/4500 for a long-span continuous rigid-frame bridge. 展开更多
关键词 Turnout on bridge Span-to-depth ratio Dynamic response Vehicle-turnout-bridge system High-speed railway
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Study on the Influence of Aspect Ratio on the Seismic Response and Overturning Resistance of a New Staggered Story Isolated Structure
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作者 Tiange Zhao Dewen Liu 《World Journal of Engineering and Technology》 2024年第3期617-634,共18页
The aspect ratio of the structure has a significant impact on the overall stability of the ultra high-rise building. A large aspect ratio of the structure increases the risk of overturning and reduces the lateral stif... The aspect ratio of the structure has a significant impact on the overall stability of the ultra high-rise building. A large aspect ratio of the structure increases the risk of overturning and reduces the lateral stiffness of the structure, leading to significant tensile and compressive stresses in the isolated bearings. To study the effect of aspect ratio on the seismic response and overturning resistance of a new staggered story isolated structure, three models with different aspect ratios were established. Nonlinear time-history analysis of the three models was conducted using ETABS finite element software. The results indicate that the overturning moment and overturning resistance moment of the superstructure in the new staggered story isolated structure increase with an increasing aspect ratio. However, the increase in the overturning moment of the superstructure is much greater than the increase in the overturning resistance moment, resulting in a decrease in the overturning resistance ratio of the superstructure with an increasing aspect ratio. The overturning moment and overturning resistance moment of the substructure in the new staggered story isolated structure decrease with an increasing aspect ratio. However, the decrease in the overturning moment of the substructure is greater than the decrease in the overturning resistance moment, leading to an increase in the overturning resistance ratio of the substructure with an increasing aspect ratio. The decrease in the overturning resistance ratio of the superstructure in the new staggered story isolated structure is much greater than the increase in the overturning resistance ratio of the substructure. Therefore, as the aspect ratio of the overall structure increases, the overturning resistance ratio of the superstructure and the entire structure decreases. 展开更多
关键词 Aspect ratio A New Staggered Story Isolated Structure Seismic response Overturning Resistance ratio Isolated Bearing
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Microtremor-based analysis of the dynamic response characteristics of a site containing grouped earth fissures 被引量:1
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作者 Deng Yahong Xuan You +5 位作者 Mu Huandong Chang Jiang Cao Ge He Nainan Zhao Xunchang Sun Longfei 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2023年第3期689-702,共14页
In this study,the Beibu earth fissure site in the northeastern part of Weihe Basin,which contains four nearly parallel earth fissures,was studied.A long straight microtremor measuring line,containing 49 measuring poin... In this study,the Beibu earth fissure site in the northeastern part of Weihe Basin,which contains four nearly parallel earth fissures,was studied.A long straight microtremor measuring line,containing 49 measuring points across four earth fissures,was established to investigate the dynamic response of this site using Fourier spectrum,response acceleration spectrum,Arias intensity,and HVSR analyses.The main results are as follows:(1)The fundamental frequencies of 44 measuring points obtained from HVSR analysis are concentrated within 1.67 Hz-2.25 Hz,and the existence of the earth fissures has little effect on the fundamental frequency changes.(2)There is an amplification effect near a single earth fissure.The dynamic responses are large at the measuring points near the earth fissure,and the values decrease with increasing distance from the earth fissure.In areas between two adjacent earth fissures,these values decrease and are even lower than those in sites without amplification effects.(3)In this earth fissure site,the general area(or less affected area)and affected areas were delineated based on the amplification effect.In engineering applications,construction design should avoid these affected areas and existing structures should be reinforced to satisfy the seismic fortification requirements. 展开更多
关键词 earth fissure sites MICROTREMORS Fourier amplitude spectrum response spectrum arias intensity H/V spectral ratio fundamental frequency amplification effect
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Does the root to shoot ratio show a hormetic response to stress? An ecological and environmental perspective 被引量:9
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作者 Evgenios Agathokleous Regina G.Belz +2 位作者 Mitsutoshi Kitao Takayoshi Koike Edward J.Calabrese 《Journal of Forestry Research》 SCIE CAS CSCD 2019年第5期1569-1580,共12页
Root/shoot(R/S)ratio is an important index for assessing plant health,and has received increased attention in the last decades as a sensitive indicator of plant stress induced by chemical or physical agents.The R/S ra... Root/shoot(R/S)ratio is an important index for assessing plant health,and has received increased attention in the last decades as a sensitive indicator of plant stress induced by chemical or physical agents.The R/S ratio has been discussed in the context of ecological theory and its potential importance in ecological succession,where species follow different strategies for above-ground growth for light or below-ground competition for water and nutrients.We present evidence showing the R/S ratio follows a biphasic dose–response relationship under stress,typical of hormesis.The R/S ratio in response to stress has been widely compared among species and ecological succession classes.It is constrained by a variety of factors such as ontogeny.Furthermore,the current literature lacks dose-response studies incorporating the full dose–response continuum,hence limiting scientific understanding and possible valuable application.The data presented provide an important perspective for new-generation studies that can advance current ecological understanding and improve carbon storage estimates by R/S ratio considerations.Hormetic response of the R/S ratio can have an important role in forestry for producing seedlings with desired characteristics to achieve maximum health/productivity and resilience under plantation conditions. 展开更多
关键词 Biological plasticity Biphasic response HORMESIS Plant STRESS Root/shoot ratio
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Tunnel flexibility effect on the ground surface acceleration response 被引量:8
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作者 Mohammad Hassan Baziar asoud Rabeti Moghadam +1 位作者 Yun Wook Choo Dong-Soo Kim 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2016年第3期457-476,共20页
Flexibility of underground structures relative to the surrounding medium, referred to as the flexibility ratio, is an important factor that influences their dynamic interaction. This study investigates the flexibility... Flexibility of underground structures relative to the surrounding medium, referred to as the flexibility ratio, is an important factor that influences their dynamic interaction. This study investigates the flexibility effect of a box-shaped subway tunnel, resting directly on bedrock, on the ground surface acceleration response using a numerical model verified against dynamic centrifuge test results. A comparison of the ground surface acceleration response for tunnel models with different flexibility ratios revealed that the tunnels with different flexibility ratios influence the acceleration response at the ground surface in different ways. Tunnels with lower flexibility ratios have higher acceleration responses at short periods, whereas tunnels with higher flexibility ratios have higher acceleration responses at longer periods. The effect of the flexibility ratio on ground surface acceleration is more prominent in the high range of frequencies. Furthermore, as the flexibility ratio of the tunnel system increases, the acceleration response moves away from the free field response and shifts towards the longer periods. Therefore, the flexibility ratio of the underground tunnels influences the peak ground acceleration (PGA) at the ground surface, and may need to be considered in the seismic zonation of urban areas. 展开更多
关键词 box-shaped tunnel flexibility ratio acceleration response ground surface centrifuge modeling numericalsimulation
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Vertical-to-horizontal response spectral ratio for offshore ground motions:Analysis and simplified design equation 被引量:12
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作者 陈宝魁 王东升 +2 位作者 李宏男 孙治国 李超 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第1期203-216,共14页
In order to study the differences in vertical component between onshore and offshore motions,the vertical-to-horizontal peak ground acceleration ratio(V/H PGA ratio) and vertical-to-horizontal response spectral ratio(... In order to study the differences in vertical component between onshore and offshore motions,the vertical-to-horizontal peak ground acceleration ratio(V/H PGA ratio) and vertical-to-horizontal response spectral ratio(V/H) were investigated using the ground motion recordings from the K-NET network and the seafloor earthquake measuring system(SEMS).The results indicate that the vertical component of offshore motions is lower than that of onshore motions.The V/H PGA ratio of acceleration time histories at offshore stations is about 50%of the ratio at onshore stations.The V/H for offshore ground motions is lower than that for onshore motions,especially for periods less than 0.8 s.Furthermore,based on the results in statistical analysis for offshore recordings in the K-NET,the simplified V/H design equations for offshore motions in minor and moderate earthquakes are proposed for seismic analysis of offshore structures. 展开更多
关键词 offshore ground motion vertical component simplified design equation vertical-to-horizontal response spectral ratio (V/H) vertical-to-horizontal peak ground acceleration ratio (V/H PGA ratio K-NET network seafloor earthquake measuring system (SEMS)
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Influence of porosity distribution on nonlinear free vibration and transient responses of porous functionally graded skew plates 被引量:5
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作者 Naveen Kumar H S Subhaschandra Kattimani TNguyen-Thoi 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2021年第6期1918-1935,共18页
This article deals with the investigation of the effects of porosity distributions on nonlinear free vibration and transient analysis of porous functionally graded skew(PFGS)plates.The effective material properties of... This article deals with the investigation of the effects of porosity distributions on nonlinear free vibration and transient analysis of porous functionally graded skew(PFGS)plates.The effective material properties of the PFGS plates are obtained from the modified power-law equations in which gradation varies through the thickness of the PFGS plate.A nonlinear finite element(FE)formulation for the overall PFGS plate is derived by adopting first-order shear deformation theory(FSDT)in conjunction with von Karman’s nonlinear strain displacement relations.The governing equations of the PFGS plate are derived using the principle of virtual work.The direct iterative method and Newmark’s integration technique are espoused to solve nonlinear mathematical relations.The influences of the porosity distributions and porosity parameter indices on the nonlinear frequency responses of the PFGS plate for different skew angles are studied in various parameters.The effects of volume fraction grading index and skew angle on the plate’s nonlinear dynamic responses for various porosity distributions are illustrated in detail. 展开更多
关键词 Porous functionally graded skew plates Porosity distributions Nonlinear transient response Nonlinear frequency ratio Nonlinear frequency parameter
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Theoretical analyses on bed topography responses in large depth-to-width ratio river bends with constant curvatures 被引量:2
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作者 Shuxian GAO Haijue XU Yuchuan BAI 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2018年第5期747-766,共20页
Bed morphology is the result of a dynamic response to a complex meandering river system. It is an important factor for the further development of river. Based on the meandering river characterized by a large depth-to-... Bed morphology is the result of a dynamic response to a complex meandering river system. It is an important factor for the further development of river. Based on the meandering river characterized by a large depth-to-width ratio, a theoretical model is established with the coupling of Navier-Stokes (N-S)~ sediment transport, and bed deformation equations. The flow characteristics and bed response of river are obtained with the perturbation method. The research results show that, under the effect of two- dimensional flow disturbance, the bars and pools present the regular response. For a given sinuousness, the amplitude of the bed response can be used as a criterion to judge the bedform stability. The effects of the Reynolds number, disturbance wavenumber, sinuousness, and bed morphology gradient on the bed response development are described. 展开更多
关键词 meandering river large depth-to-width ratio channel disturbance wave bed response
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Dynamic response analysis of liquefiable ground due to sinusoidal waves of different frequencies of shield construction
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作者 Wang Jingyue Ge Xinsheng +4 位作者 Sun Jingyuan Liu Yasheng Shang Zhuo Wang Zhiqiang Tian Maoguo 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2023年第3期637-646,共10页
Vibration induced by shield construction can lead to liquefaction of saturated sand.Based on FLAC3D software,a numerical model of tunnel excavation is established and sinusoidal velocity loads with different frequenci... Vibration induced by shield construction can lead to liquefaction of saturated sand.Based on FLAC3D software,a numerical model of tunnel excavation is established and sinusoidal velocity loads with different frequencies are applied to the excavation face.The pattern of the excess pore pressure ratio with frequency,as well as the dynamic response of soil mass under different frequency loads before excavation,is analyzed.When the velocity sinusoidal wave acts on the excavation surface of the shield tunnel with a single sand layer,soil liquefaction occurs.However,the ranges and locations of soil liquefaction are different at different frequencies,which proves that the vibration frequency influences the liquefaction location of the stratum.For sand-clay composite strata with liquefiable layers,the influence of frequency on the liquefaction range is different from that of a single stratum.In the frequency range of 5-30 Hz,the liquefaction area and surface subsidence decrease with an increase in vibration frequency.The research results in this study can be used as a reference in engineering practice for tunneling liquefiable strata with a shield tunneling machine. 展开更多
关键词 shield tunnel liquefiable formation FLAC3D numerical simulation excess pore pressure ratio dynamic response analysis
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Parametric Study on the Effect of Aspect Ratio of Selected Cooling Hole Geometries on the Mechanical Response of an Automobile Aluminium Alloy Wheel 被引量:2
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作者 S. O. Igbudu D. A. Fadare 《Open Journal of Applied Sciences》 2021年第1期41-57,共17页
Aluminium alloy wheels are increasingly popular for their light weight and good thermal conductivity. Cooling Holes (CH) are introduced to reduce their weight without compromising structural integrity. Literature is s... Aluminium alloy wheels are increasingly popular for their light weight and good thermal conductivity. Cooling Holes (CH) are introduced to reduce their weight without compromising structural integrity. Literature is sparse on the effect of aspect ratio (AR) of CHs on wheels. This, work, therefore, attempts to undertake a parametric study of the effect of aspect ratio (AR) on the mechanical response of an aluminium alloy wheel with triangular, quadrilateral and oval-shaped CHs. Three-dimensional wheel models (6JX14H2ET42) with triangular, quadrilateral and oval shaped CH (each with CH area of 2229 mm<sup>2</sup>) were generated, discretized, and analyzed by FEM using Creo Elements/Pro 5.0 to determine the mechanical response at the inboard bead seat at different ARs of 1, 0.5, 0.33 and 0.25, each for quadrilateral-CH and oval-CH, at a static Radial Load of 4750 N and Inflation Pressures of 0.3 and 0.15 MPa, respectively. The study shows that the magnitude of stress and displacement is affected by shape and AR of CH. From the results, it could be established that oval-shaped-CH wheel at AR of 0.5 offers greater prospect in wheel design as it was least stressed and deformed and, that the CH combination with highest integrity was the oval-CH and quadrilateral-CH at AR of 0.5. 展开更多
关键词 Aspect ratio Mechanical response. Aluminum alloy wheel
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The Experimental Simulation of Rocks on Load/Unload Response Ratio for Earthquake Prediction 被引量:3
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作者 Wang Yucang, Yin Xiangchu, and Wang HaitaoLaboratory for Non-linear Mechanics of Continuous Media (LNM), Institute of Mechanics,Chinese Academy of Sciences, Beijing 100080, ChinaLaboratory for Non-linear Mechanics of Continuous Media (LNM), Institute of Mechanics,Chinese Academy of Sciences, Beijing 100080, ChinaCenter for Analysis and Prediction , CSB, Beijing 100036, China 《Earthquake Research in China》 1998年第4期40-45,共6页
The load/unload experiments on rock failure under pressure have been carried out in Material Test System (MTS) in the Laboratory for Non-linear Mechanics of Continuous Media (LNM), Institute of Mechanics, Chinese Acad... The load/unload experiments on rock failure under pressure have been carried out in Material Test System (MTS) in the Laboratory for Non-linear Mechanics of Continuous Media (LNM), Institute of Mechanics, Chinese Academy of Sciences, and load/unload response ratio (LURR) values with strain as response (i.e. inverse elastic constant as response rate) have been obtained. The experimental results are in accordance with theoretical results and those in real earthquakes: LURR rises just before rock failure. So LURR can be used as the precursor of rock failure and earthquake prediction. 展开更多
关键词 Load\Unload response ratio Experiment of ROCK FAILURE EARTHQUAKE prediction.
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Experimental Research on the Load/Unload Response Ratio (LURR) Theory 被引量:1
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作者 YuHuaizhong YinXiangchu +8 位作者 LiangNaigang XiaMengfen LiMin XuZhaoyong PengKeyin VictorKukshenko WuZhishen QiLi SurgueiElizarov 《Earthquake Research in China》 2003年第3期227-235,共9页
Implementing acoustic emission experiments with large rock samples, LURR (Load/Unload Response Ratio) theory was studied. The loading conditions in the experiments were designed to simulate the complicated loading pro... Implementing acoustic emission experiments with large rock samples, LURR (Load/Unload Response Ratio) theory was studied. The loading conditions in the experiments were designed to simulate the complicated loading process of underground rocks. The damages emerging inside the rock samples were recorded by the acoustic emission technique during the loading process. The experimental results were consistent with prediction by LURR theory. Integrating the changing processes of LURR value Y and the location process of acoustic emission events showed agreement between the variation of LURR value Y and the damage evolution inside the rocks. Furthermore, the high value of Y emerged before the complete breakdown of materials. Therefore, the damage evolution of rock specimen can be quantitatively analyzed with LURR theory, thus the failure of the rock materials and the earthquake occurrence may be predicted. The experimental results gave a further verification of LURR theory. 展开更多
关键词 Load/Unload response ratio Acoustic emission Circling load Large sample Critical sensitivity
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Short-term and imminent anomalies of earthquake of load and unload response ratio of the well level to earth tides
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作者 张昭栋 陈学忠 +5 位作者 吴子泉 王梅 程烨 苏鸾声 王忠民 石荣会 《Acta Seismologica Sinica(English Edition)》 CSCD 1997年第2期73-81,共9页
In this paper, through the nonlinear response of rock strain and stress, we have analized the physical mechanism of loading and unloading response ratio of the well level to the earth tides,the respouse of an aquife... In this paper, through the nonlinear response of rock strain and stress, we have analized the physical mechanism of loading and unloading response ratio of the well level to the earth tides,the respouse of an aquifer of confined well to bulk strain tide and showed two methods of the calculation of loading and unloading response ratio of the well level to the earth tides. We took the example of the Yu 01 well, which is near the epicenter of Heze M S 5.9 earthquake, calculated the response rate and loading and unloading response ratio of two kinds of the earth tides of it. The response rate and response ratio before the earthquake had the variation of increase. 展开更多
关键词 loading and unloading response ratio earth tide well level Heze earthquake Yu 01 well
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Relative spectral response calibration using Ti plasma lines
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作者 费腾 潘从元 +2 位作者 曾强 王秋平 杜学维 《Plasma Science and Technology》 SCIE EI CAS CSCD 2018年第4期145-151,共7页
This work introduces the branching ratio(BR) method for determining relative spectral responses,which are needed routinely in laser induced breakdown spectroscopy(LIBS). Neutral and singly ionized Ti lines in the 250... This work introduces the branching ratio(BR) method for determining relative spectral responses,which are needed routinely in laser induced breakdown spectroscopy(LIBS). Neutral and singly ionized Ti lines in the 250–498 nm spectral range are investigated by measuring laser-induced micro plasma near a Ti plate and used to calculate the relative spectral response of an entire LIBS detection system. The results are compared with those of the conventional relative spectral response calibration method using a tungsten halogen lamp, and certain lines available for the BR method are selected. The study supports the common manner of using BRs to calibrate the detection system in LIBS setups. 展开更多
关键词 branching ratio relative spectral response calibration TITANIUM laser-induced breakdown spectroscopy
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Physical meaning and prediction efficiency of the load/unload response ratio of rocks in strain-weakening phase before failure
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作者 许昭永 杨润海 +3 位作者 王彬 赵晋明 王赟赟 梅世蓉 《Acta Seismologica Sinica(English Edition)》 CSCD 2002年第1期47-55,共9页
Rock experiment results indicate that the load/unload response ratio (LURR) of rocks expressed via strain energy may have singular or negative value after the stress in the rock reaches its maximum before rock failure... Rock experiment results indicate that the load/unload response ratio (LURR) of rocks expressed via strain energy may have singular or negative value after the stress in the rock reaches its maximum before rock failure or when the rock goes into the strain-weakening phase. The universality of this phenomenon is discussed. Expressed via strain or strain energy and the travel time of P wave, the variation form of the reciprocal of LURR during the process of rock failure preparation is derived. The results show that after a sharp decrease the reciprocal of LURR reaches its minimum when the main fracture of the rock is about to appear. This feature can be taken as an indication that the rock main fracture is impending. 展开更多
关键词 strain-weakening phase load/unload response ratio prediction efficiency
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The tempo-spatial evolution characteristics of the load/unload response ratio before strong earthquakes in California of America and its predicting implications
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作者 宋治平 尹祥础 +2 位作者 王裕仓 徐平 薛艳 《Acta Seismologica Sinica(English Edition)》 EI CSCD 2000年第6期628-635,共8页
In this paper, the tempo-spatial evolution characteristics of the load/unload response ratio (namely LURR or Y value) before strong earthquakes with magnitude over 6 during 1976~1994 in California of America are studi... In this paper, the tempo-spatial evolution characteristics of the load/unload response ratio (namely LURR or Y value) before strong earthquakes with magnitude over 6 during 1976~1994 in California of America are studied in detail. The results show that there appear some high-Y regions cohering with the regional tectonic trend in a great area 3~4 years before strong earthquakes and these high-Y regions migrate from the periphery to the epicenter region at a speed of tens of kilometers per year. The load/unload response ratio (LURR) anomalies near the epicenter region characterizes a type of (ascend ? descend( and appear and increase steeply until one year or less before most earthquakes. (Positive( earthquakes form usually a concentration area; in and near which the main shock occurs. We have analyzed the different and same characters of earthquakes between California of American and the Chinese mainland. Basing on these results, we discuss the approach and method how to predict and estimate the three parameters (place, time and magnitude) of a strong earthquake in California of American by applying the characteristics of the LURR. 展开更多
关键词 California of American the load/unload response ratio prediction method
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Effect of Mass Ratio on Hydrodynamic Response of a Flexible Cylinder
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作者 Haoyang Cen Rupp Carriveau David S-K Ting 《Journal of Marine Science and Application》 CSCD 2016年第1期50-62,共13页
The effect of the mass ratio on the flow-induced vibration (FIV) of a flexible circular cylinder is experimentally investigated in a towing tank. A Tygon tube with outer and inner diameters of 7.9 mm and 4.8 mm, res... The effect of the mass ratio on the flow-induced vibration (FIV) of a flexible circular cylinder is experimentally investigated in a towing tank. A Tygon tube with outer and inner diameters of 7.9 mm and 4.8 mm, respectively, was employed for the study. The tube was connected to a carriage and towed from rest to a steady speed up to 1.6 m/s before slowing down to rest again over a distance of 1.6 m in still water. Reynolds number based on the cylinder's outer diameter was 800-13,000, and the reduced velocity (velocity normalized by the cylinder's natural frequency and outer diameter) spanned from 2 to 25. When connected, the cylinder was elongated from 420 mm to 460 mm under an axial pre-tension of 11 N. Based on the cylinder's elongated length, the aspect ratio (ratio of the cylinder's length to outer diameter) was calculated as 58. Three mass ratios (ratio of the cylinder's structural mass to displaced fluid mass, m*) of 0.7, 1.0, and 3.4 were determined by filling the cylinder's interior with air, water, and alloy powder (nickel-chromium-boron matrix alloy), respectively. An optical method was adopted for response measurements. Multi-frequency vibrations were observed in both in-line (IL) and cross-flow (CF) responses; at high Reynolds number, vibration modes up to the 3rd one were identified in the CF response. The mode transition was found to occur at a lower reduced velocity for the highest tested mass ratio. The vibration amplitude and frequency were quantified and expressed with respect to the reduced velocity. A significant reduced vibration amplitude was found in the IL response with increasing mass ratios, and only initial and upper branches existed in the IL and CF response amplitudes. The normalized response frequencies were revealed to linearly increase with respect to the reduced velocity, and slopes for linear relations were found to be identical for the three cases tested. 展开更多
关键词 flow-induced vibration low mass ratio flexible cylinder multi-frequency response hydrodynamic response
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The spatial temporal evolution characteristics of the load/unload response ratio(LURR) and its implications for predicting the three elements of earthquakes
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作者 宋治平 尹祥础 陈学忠 《Acta Seismologica Sinica(English Edition)》 CSCD 1996年第2期235-244,共10页
The spatial temPOral evolution characteristics of the load/unload response ratio (Y) before strong earthquakes is studied in this paper. The results show that the regions of high value of Y migrate and converge to the... The spatial temPOral evolution characteristics of the load/unload response ratio (Y) before strong earthquakes is studied in this paper. The results show that the regions of high value of Y migrate and converge to the impending earthquake epicenter from different directions before the occurrence of the event. Basing on this discovery, it is proposed that the method can be used to predict the three elements of an earthquake. It was applied to predict that an earthquake would occur in the western part of Yunnan Province, southwestern China. The three elements (time, space and magnitude) of the Menglian earthquake with Ms7.3 which occurred on July 12, 1995 in Yunnan Province tallied with our prediction. 展开更多
关键词 load/unload response ratio (LURR ) time-space evolution of LURR three elements of earthquakes earthquake prediction.
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Investigation on the Load/Unload Response Ratio With Coda Q-1 as Response
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作者 Chen Xuezhong,Yin Xiangchu,Aki K,Ouyang H,Jin A.,Song Zhiping,and Wang YucangCenter tor Analysis and Prediction,SSB,Beijing 100036,ChinaSouthern California Eanhquake Center,University of Southern California,Los Angeles,USAInstitute of Geophysics,SSB,Beijing 100081,China 《Earthquake Research in China》 1996年第4期38-45,共8页
The load/unload response ratio YQ with the geophysical parameter coda Q-1 of the crust as response is denned in this study.The variation in YQ-1 before and after the Northridge earthquake of January 17,1994(California... The load/unload response ratio YQ with the geophysical parameter coda Q-1 of the crust as response is denned in this study.The variation in YQ-1 before and after the Northridge earthquake of January 17,1994(California)has been investigated by using the data of coda Q-1 with frequencies of 1.5,3.0,6.0,12.0,and 24.0 Hz in the Southern California from 1987 to 1994.It can be found that YQ-1 for coda waves with all frequencies,the frequency of 12.0 Hz excluded,ascended to a certain extent prior to the occurrence of the rnainshock and returned to normality after the main shock. 展开更多
关键词 CODA Q-1 THEORY of the load/unload response ratio Load/unload response ratio YQ The Northridge EARTHQUAKE EARTHQUAKE PREDICTION
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The Natural Probability Distribution of Load and Unload Response Ratio
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作者 Chen Qifu,Yin Xiangchu,and Ma LiCenter for Analysis and Prediction,SSB,Beijing 100036,China 《Earthquake Research in China》 1997年第1期43-49,共7页
In this paper,the Gutenberg-Richter model is used to generate seismic events.The events that satisfy the random distribution are also generated.With those events,the natural probability distribution of Load and Unload... In this paper,the Gutenberg-Richter model is used to generate seismic events.The events that satisfy the random distribution are also generated.With those events,the natural probability distribution of Load and Unload Response Ratio(LURR),which measures quantitatively the degree of instability of a nonlinear system,is discussed.The study is based on stress energy release,which is chosen as the response of nonlinear system F3.The comparative results from the observation catalogue and generating data are also studied.It is revealed that the natural probability of LURR is mostly stable when the sample number is sufficient.The lower the natural probability of LURR,the more the precursory is information it may contain.The influence of Y3 resulting from the sample number and the magnitude range of events is also discussed. 展开更多
关键词 NATURAL PROBABILITY Distribution System EVENT load-unload response ratio.
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