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Variations of shear-wave splitting parameters in the source region of the 2023 Türkiye doublet earthquakes

Earthquake Science 2024年第2期37卷 174-187页

作者： Xuelai Cao lijun chang Institute of Geophysics China Earthquake AdministrationBeijing 100081China

In this study,the shear-wave splitting parameters of local seismic events from the source regions of the 2023 Türkiye MW7.7 and MW7.6 doublet earthquakes(event 1 and event 2,respectively)were measured from June 1,2022,to April 25,2023,and their spatiotemporal characteristics were analyzed.The results revealed clear spatial and temporal differences.Spatially,the dominant fast-wave polarization direction at each station shows a strong correlation with the direction of the maximum horizontal principal compressive stress,as characterized by focal mechanism solutions of seismic events(MW≥3.5)near the station.The dominant fast-wave polarization direction and the regional stress field also showed a strong correlation with the intermovement of the Arabian Plate,African Plate,and Anatolian Block.Along the Nurdagi-Pazarcik fault zone,the seismic fault of event 1,stations closer to the middle of the fault where the mainshock occurred exhibited notably greater delay times than stations located towards the ends of the fault and far from the mainshock.In addition,the stations located to the east of the Nurdagi-Pazarcik fault and to the north of the Sürgüfault also exhibited large delay times.The spatial distribution of shear-wave splitting parameters obtained from each station indicates that the upper-crust anisotropy in the source area is mainly controlled by the regional stress field,which is closely related to the state of the block motion.During the seismogenic process of the MW7.7 earthquake,more stress accumulated in the middle of the Nurdagi-Pazarcik fault than at either end of the fault.Under the influence of the MW7.7 and MW7.6 events,the stress that accumulated during the seismogenic process of the earthquake doublet may have migrated towards some areas outside the aftershock intensive area after the earthquakes,and the crustal stress and its adjustment range near the outer stations increased significantly.With the exception of two stations with few effective events,all stations showed a consistent change in shear-wa

关键词： Türkiye doublet earthquakes shear-wave splitting upper crustal anisotropy stress field

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Study on cumulative effects of biological craniocerebral trauma underrepeated blast

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Theoretical & Applied Mechanics Letters 2024年第3期14卷 174-183页

作者： Xingyuan Huang Bingchen Xia lijun chang Zhikang Liao Hui Zhao Zhihua Cai Hunan Provincial Key Laboratory of Health Maintenance for Mechanical Equipment Hunan University of Science and TechnologyXiangtan 411201China School of Mechanical and Electrical Engineering Foshan UniversityFoshan 528231China Institute for Traffic Medicine PLA Army Characteristic Medical CenterChongqing 400042China

Repeated blast impacts on personnel in explosive environments can exacerbate craniocerebral trauma.Most ex-isting studies focus on the injury effects of a single blast,lacking in-depth analysis on the injury effects andcumulative effects of repeated blasts.Therefore,rats were used as the experimental samples to suffer from ex-plosion blasts with different peak air overpressures(167 kPa∼482 kPa)and varying number of repeated blasts.The cumulative effect of craniocerebral trauma was most pronounced for moderate repeated blast,showing ap-proximately 95%increase of trauma severity with penta blast,and an approximately 85%increase of traumaseverity with penta minor blast.The cumulative effect of craniocerebral trauma from severe,repeated blast has asmaller rate of change compared to the other two conditions.The severity of trauma from penta blast increasedby approximately 69%compared to a single blast.Comprehensive physiological,pathological and biochemicalanalysis show that the degree of neurological trauma caused by repeated blasts is higher than that of single blasts,and the pathological trauma to brain tissue is more extensive and severe.The trauma degree remains unchangedafter double blast,increases by one grade after triple or quadruple blast,and increases by two grades after pentablast.

关键词： Repeated blast Craniocerebral trauma Trauma severity grade Cumulative effects

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Teleseismic shear wave splitting and intracontinental collision deformation of the northern Tibetan Plateau and the eastern Tarim basin

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Science China Earth Sciences 2023年第7期66卷 1556-1568页

作者： lijun chang Chunyong WANG Institute of Geophysics China Earthquake AdministrationBeijing 100081China

Shear wave splitting measurement of teleseismic data has been used to determine the fast polarization directions and delay times for 38 temporary stations and 15 permanent stations from a NW linear seismic array across the eastern Tarim basin(ETB) and the northern Tibetan Plateau(NTP),and 10 permanent stations on both sides of the array.We present an image of upper mantle anisotropy in the ETB and NTP using the 63 new measurements.The results show that the fast directions and delay times have complex spatial distribution characteristics.The delay times within the interior of the Tarim basin are very small,with an average value of 0.6 s,which is not only smaller than that in the Altyn Tagh fault and Tianshan on the southern and northern margins of the basin,but also smaller than that in the NTP,reflecting that the delay time of stable blocks is smaller than that of active blocks.Along the array,from east to west,the fast directions contrarotate from NNW in the southern Songpan-Garze terrane to NW in the northern Songpan-Garze terrane,to near E-W or ENE in the north of the East Kunlun fault and southern margin of the Qaidam basin,then first abruptly rotate to NW in the Qiman Tagh fault on the northwestern margin of the Qaidam basin,second abruptly rotate to ENE in the Altyn Tagh fault and south of the ETB,and third abruptly rotate to NW in the north of the ETB,then finally rotate to WNW in the Tianshan.The comparative analysis between the fast wave directions measured by shear wave splitting and predicted from the surface deformation field shows that,with the exclusion of the five observations with larger misfits within the interior of the ETB(with an average misfit of 27°),the misfits in the NTP and northern and southern margins of the Tarim basin are relatively small(with an average misfit of 9°).In addition,the fast wave directions of the tectonic units such as the Altyn Tagh fault,East Kunlun fault,and Tianshan are parallel to the strikes of faults and mountains in the region,which indicates that the deep and s

关键词： Northern Tibetan Plateau Eastern Tarim basin Altyn Tagh fault East Kunlun fault Lithospheric deformation

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Study of Impact Resistance Based on Porcupine Quills Bionic Thin-walled Structure

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Journal of Bionic Engineering 2023年第5期20卷 1942-1955页

作者： Tianshu Huang Zhengyu Mao lijun chang Xingyuan Huang Zhihua Cai Hunan Provincial Key Laboratory of Health Maintenance for Mechanical Equipment Hunan University of Science and TechnologyXiangtanChina School of Mechanical Engineering Hunan University of Science and TechnologyXiangtanChina

Using an electron microscope to observe the microstructure of a porcupine quills cross-section and a bionic method,a new bionic structure was proposed.The performance of the structure in terms of energy absorption,maximum impact force withstood,and impact force efficiency was evaluated using Ansys finite element simulation software to simulate the structure's impact.To examine the impact of ribs on the structural performance of the bionic porcupine quills,a control structure was developed.According to the results of the finite element simulation,the presence of ribs in the Bionic porcupine quills structure can transfer stress uniformly to the overall structure and share stress for some of the rupture-prone regions.Ribs reduce stress concentration in specific areas and increase the impact force efficiency of the structure.The SEA and IFE values of bionic porcupine quills were 30.01 kJ/kg and 84.22%,respectively.The structure is then optimized for parameter design in order to find the optimal structure by response surface in order to improve the structure's SEA and decrease its MIF.In order to evaluate the precision of the response surface,the optimal structure predicted is validated using finite element simulation.

关键词： Bionic structure design Thin-walled structure Impact resistance Specific energy absorption Multi-objective optimization

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Multi-scale Analysis of the Relationships between Solar Activity, CO_(2) and Global Surface Temperature

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Research in Astronomy and Astrophysics 2022年第9期22卷 245-254页

作者： Zhen Li lijun chang Jiahui Lou Yi Shen Haoming Yan College of Surveying and Geo-informatics North China University of Water Resources and Electric PowerZhengzhou 450046China State Key Laboratory of Geodesy and Earth’s Dynamics Innovation Academy for Precision Measurement Science and TechnologyCASWuhan 430077 China Geological Disaster Prevention and Control Center of Henan Geological Bureau Zhengzhou 450003China School of Geographic Sciences Xinyang Normal UniversityXinyang 464000China

To reveal whether the dynamics of solar activity precede those of global temperature, especially in terms of global warming, the relationship between total solar irradiance(TSI), which is treated as a proxy of solar activity, and global surface temperature(GST) is investigated in the frequency domain using wavelet coherence. The results suggest that the effect of TSI on GST is mainly reflected on the characteristic scale around 22 yr, and variations in TSI lead to changes in GST with some delay effect as shown by the phase difference arrows. However, this implicated relationship has been perturbed by excessive CO_(2) emissions since 1960. Through the combination of co-integration analysis and wavelet coherence, the hidden relationship between TSI and GST has been uncovered without the CO_(2) effect and the results further indicate that TSI has a positive effect on GST at the characteristic scale around 22 yr with a 3 yr lead.

关键词： Sun:activity planets and satellites:surfaces Earth

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青藏高原东南缘三维S波速度和径向各向异性及泸定M_(S)6.8和芦山M_(S)7.0地震孕震环境探讨

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地球物理学报 2024年第1期67卷 108-127页

作者：孙回归王兴臣常利军中国地震局地球物理研究所北京100081 中国地震局震源物理重点实验室北京100081

利用青藏高原东南缘布设的684个流动地震台和150个固定地震台的连续背景噪声波形数据,提取了周期5~50 s的Rayleigh波和Love波相速度频散,并反演获得了该区域下方0~70 km三维S波速度和径向各向异性结构.结果表明:(1)受川滇地块南部高速... 详细信息

利用青藏高原东南缘布设的684个流动地震台和150个固定地震台的连续背景噪声波形数据,提取了周期5~50 s的Rayleigh波和Love波相速度频散,并反演获得了该区域下方0~70 km三维S波速度和径向各向异性结构.结果表明:(1)受川滇地块南部高速体的阻挡,东南缘中下地壳内存在两条空间分布独立的低速带.西侧(L1)从川滇地块北部向南延伸至滇西南地块,其中下地壳平均V_(S)小于3.4 km·s^(-1)并表现为正径向各向异性结构,反映了高原中下地壳可能存在部分熔融和韧性变形;东侧低速带(L2)沿着小江断层南北分布,受到红河断层的阻挡,弱物质不太可能进入滇西南地块,该区域下地壳和上地幔顶部均显示较强的正各向异性,推测其更可能是沿小江断层相互驱动的块体在横向挤压过程中引起的地壳部分熔融而导致.(2)芦山M_(S)7.0地震位于龙门山逆冲断层南段,泸定M_(S)6.8地震位于鲜水河走滑断层东南段,两者都发生在地壳浅层高低速异常过渡带上,但其深部孕震环境有所不同.芦山震区西北部中下地壳低速体为负各向异性,推测韧性物质沿着龙门山下方陡倾断层向上运移,上地壳积累应力并通过薄弱区域释放导致了芦山地震的发生;泸定震区为正各向异性的中下地壳韧性变形促进了川滇地块SE向的水平运动,受刚性的四川盆地阻挡,加剧了上地壳发震断层的滑动变形和应力积累,脆性上地壳突然破裂导致了泸定地震的发生.

关键词：青藏高原东南缘背景噪声成像 S波速度径向各向异性泸定M_(S)6.8地震芦山M_(S)7.0地震

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A diagnostic prediction model for hypertension in Han and Yugur population from the China National Health Survey (CNHS)

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Chinese Medical Journal 2023年第9期136卷 1057-1066页

作者： Chengdong Yu Xiaolan Ren Ze Cui Li Pan Hongjun Zhao Jixin Sun Ye Wang lijun chang Yajing Cao Huijing He Jin’en Xi Ling Zhang Guangliang Shan Department of Epidemiology and Statistics Institute of Basic Medical SciencesChinese Academy of Medical SciencesSchool of Basic MedicinePeking Union Medical CollegeBeijing 100005China Institute of Chronic and Noncommunicable Disease Control and Prevention Gansu Provincial Centre for Disease Control and PreventionLanzhouGansu 730000China Hebei Provincial Center for Disease Control and Prevention ShijiazhuangHebei 050000China The State Key Lab of Respiratory Disease The First Affiliated HospitalThe School of Public HealthGuangzhou Medical UniversityGuangzhouGuangdong 510182China Department of Epidemiology and Health Statistics School of Public HealthCapital Medical UniversityBeijing 100069China

Background:The prevalence of hypertension is high among Chinese adults,thus,identifying non-hypertensive individuals at high risk for intervention will help to improve the efficiency of primary prevention strategies.Methods:The cross-sectional data on 9699 participants aged 20 to 80 years were collected from the China National Health Survey in Gansu and Hebei provinces in 2016 to 2017,and they were nonrandomly split into the training set and validation set based on location.Multivariable logistic regression analysis was performed to develop the diagnostic prediction model,which was presented as a nomogram and a website with risk classification.Predictive performances of the model were evaluated using discrimination and calibration,and were further compared with a previously published model.Decision curve analysis was used to calculate the standardized net benefit for assessing the clinical usefulness of the model.Results:The Lasso regression analysis identified the significant predictors of hypertension in the training set,and a diagnostic model was developed using logistic regression.A nomogram with risk classification was constructed to visualize the model,and a website(https://chris-yu.***.io/hypertension_risk_prediction/)was developed to calculate the exact probabilities of hypertension.The model showed good discrimination and calibration,with the C-index of 0.789(95%confidence interval[CI]:0.768,0.810)through internal validation and 0.829(95%CI:0.816,0.842)through external validation.Decision curve analysis demonstrated that the model was clinically useful.The model had a higher area under receiver operating characteristic curves in training and validation sets compared with a previously published diagnostic model based on Northern China population.Conclusion:This study developed and validated a diagnostic model for hypertension prediction in Gansu Province.A nomogram and a website were developed to make the model conveniently used to facilitate the individualized prediction of hypertension in the gene

关键词： Hypertension Diagnostic model Decision curve Yugur people The China National Health Survey

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Upper crustal anisotropy observed around the Longmenshan fault in the 2013 M_S7.0 Lushan earthquake region

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Earthquake Science 2018年第4期31卷 187-198页

作者： lijun chang Zhifeng Ding Chunyong Wang Institute of Geophysics China Earthquake Administration

Based on the shear wave splitting analysis of the seismic recordings at 17 temporary stations and three permanent stations, we measured the shear wave splitting parameters(i.e., the polarization direction of fast shear wave and the time delay of slow wave) to perform a systematic analysis of the crustal seismic anisotropy around the Longmenshan fault in the 2013 M7.0 Lushan earthquake region. We observed apparent spatio-temporal characteristics in the shear wave splitting parameters. The spatial distribution of fast polarization directions showed a clear partitioning in the characteristics from northwest to southeast in the focal region,which changed from NW-SE to NE-SW. In the northwest of the focal region, the fast polarization direction was oriented to NW-SE, which was parallel to the maximum horizontal compressive stress direction. However, the NE-SW fast polarization direction in the southeast of the focal region was parallel to the Longmenshan fault strike. For station BAX on the Central fault in the middle of the focal region, the distribution of fast polarization directions showed a bimodal pattern, with one dominant in the NE-SW direction and the other in the NW-SE direction. With regard to the temporal variation, the time delays were large in the initial stage after the mainshock but then gradually decreased over time and tended to be stable in the later period. This indicated that stress in the focal region increased to a maximum when the main shock occurred, with the stress release caused by the mainshock and aftershock activity, and the stress gradually decreased after a period of time. The scatter of fast polarization directions was large after the main shock, but over time the scatter gradually decreased, indicating that the Lushan earthquake caused a large perturbation in the local stress field. As the stress gradually decreased and was adjusted by the aftershock activity, the perturbation gradually weakened.

关键词： Lushan earthquake crustal anisotropy crustal stress fast polarization direction time delay

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脑组织压缩力学性能和本构模型

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医用生物力学 2024年第1期39卷 55-61页

作者：蔡志华刘春平常利军湖南科技大学机械设备健康维护湖南省重点实验室湖南湘潭411201

目的研究脑组织在不同应变率下的压缩力学性能和本构模型。方法使用电子万能试验机对猪脑组织白质和灰质开展准静态压缩和中速压缩试验,获得脑组织不同应变率下的应力-应变曲线。采用Ogden本构模型对试验曲线进行拟合,确定本构模型参... 详细信息

目的研究脑组织在不同应变率下的压缩力学性能和本构模型。方法使用电子万能试验机对猪脑组织白质和灰质开展准静态压缩和中速压缩试验,获得脑组织不同应变率下的应力-应变曲线。采用Ogden本构模型对试验曲线进行拟合,确定本构模型参数,并在有限元软件中进行仿真验证。结果脑组织应力-应变曲线呈现非线性特征,具有较强的应变率相关性和敏感性。压缩至0.6应变时,在5×10^(-4)~5×10^(-2) s^(-1)应变率下,白质和灰质的应力分别增加102%和129%,在1~1.5 s^(-1)应变率下则分别增加50.7%和54.6%;1.5 s^(-1)应变率下白质、灰质应力比5×10^(-4) s^(-1)应变率下分别增加347%、413%。Ogden模型拟合下的R~2>0.99,仿真结果与试验结果误差在15%以内,验证了模型的有效性。结论研究结果有助于实现对脑组织变形的预测,为建立更加科学合理的人体模拟靶标以及在设计和改进颅脑防护装备上提供准确的理论依据。

关键词：脑组织压缩性能 Ogden本构模型数值仿真

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Upper crustal velocity and seismogenic environment of the M7.0 Jiuzhaigou earthquake region in Sichuan, China

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Earth and Planetary Physics 2021年第4期5卷 348-361页

作者： DaHu Li ZhiFeng Ding Yan Zhan PingPing Wu lijun chang XiangYu Sun Chengdu Institute of the Tibetan Plateau Earthquake Research China Earthquake AdministrationChengdu 610041China Institute of Geophysics China Earthquake AdministrationBeijing 100081China Institute of Geology China Earthquake AdministrationBeijing 100029China

On August 8,2017,a magnitude 7.0 earthquake occurred in Jiuzhaigou County,Sichuan Province,China.The deep seismogenic environment and potential seismic risk in the eastern margin of Tibetan Plateau have once again attracted the close attention of seismologists and scholars at home and abroad.The post-earthquake scientific investigation could not identify noticeable surface rupture zones in the affected area;the complex tectonic background and the reason(s)for the frequent seismicity in the Jiuzhaigou earthquake region are unclear.In order to reveal the characteristics of the deep medium and the seismogenic environment of the M7.0 Jiuzhaigou earthquake region,and to interpret the tectonic background and genesis of the seismicity comprehensively,in this paper,we have reviewed all available observation data recorded by the regional digital seismic networks and large-scale,dense mobile seismic array(China Array)for the northern section of the North-South Seismic Belt around Jiuzhaigou earthquake region.Using double-difference seismic tomography method to invert the three-dimensional P-wave velocity structure characteristics of the upper crust around the Jiuzhaigou earthquake region,we have analyzed and discussed such scientific questions as the relationship between the velocity structure characteristics and seismicity in the Jiuzhaigou earthquake region,its deep tectonic environment,and the ongoing seismic risk in this region.We report that:the P-wave velocity structure of the upper crust around the Jiuzhaigoug earthquake region exhibits obvious lateral inhomogeneity;the distribution characteristics of the shallow P-wave velocity structure are closely related to surface geological structure and formation lithology;the M7.0 Jiuzhaigou earthquake sequence is closely related to the velocity structure of the upper crust;the mainshock of the M7.0 earthquake occurred in the upper crust;the inhomogeneous variation of the velocity structure of the Jiuzhaigou earthquake area and its surrounding medium appears to be the deep s

关键词： the M7.0 Jiuzhaigou earthquake 3D P-wave velocity structure deep tectonic seismogenic environment

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