Characteristics and Analysis of the Seismic Damage from the M_S7.0 Jiuzhaigou Earthquake in the Area between Songpan and Jiuzhaigou     

Yan Zhaolun  Peng Xiaobo  Li Shuguang  Hong Haichun 《中国地震研究》2018,32(2):173-188

This paper expounds the features of the buildings and analyzes the seismic disaster characteristics of the Jiuzhaigou M_S7. 0 earthquake in the area between Songpan and Jiuzhaigou. New buildings (especially the frame structure) had good anti-seismic performance,but brick-wood structures and brick-concrete structures sustained large amounts of damage in the earthquake. By computing the seismic damage index,we found that the seismic damage index of the frame structure was far less than that of civil structures and brick-wood structures. The seismic damage index of frame structures were all zero in the Ⅵ area,and increased rapidly with the increase of intensity,but the increasing range was reduced. We also discussed how to evaluate the intensity in areas where there was a lack of buildings or there was only one structure type,which can be referenced in future field work.  相似文献   

天津滨海爆炸事件检测与相对定位研究     

邓莉  谭毅培  刘双庆  马婷  卞真付  曹井泉 《地震》2018,38(3):158-169

2015年8月12日发生在天津滨海新区的化学品爆炸事故造成了严重的人员伤亡和财产损失。 基于区域地震台网记录的数字化连续地震波形资料, 对爆炸发生过程的精细分析是深入调查爆炸事故发生原因、 快速估计事故所造成灾害与损失的重要手段之一。 本文首先利用震相到时和质点运动轨迹信息对记录波形中能量较强的震相性质进行分析, 再通过模板匹配算法检测爆炸过程中是否存在两次大爆炸以外的小爆炸事件, 并对检测方法的效能进行检验, 最后依据波形互相关得到的震相到时差估计两次较大爆炸的相对位置。 计算结果显示区域台网记录波形中能量最大的体波震相可能为沿沉积层顶部传播的Pg震相, 垂直向能量最强的面波震相为Rg震相, 而能量较弱的初至震相可能为结晶基底首波; 爆炸过程中除了两次能量较大的爆炸以外还能检测到两次较小的爆炸事件, 其当量相当于约M_L0.5的地震; 基于两次大爆炸Pg震相相对到时信息得到第二次大爆炸发生在第一次大爆炸的北西侧, 两次爆炸位置距离约50~55 m。 本文研究结果为爆炸事故的调查分析提供了地震学依据。  相似文献   

Transcriptome assembly of Modiolus modiolus and comparative analysis with Bathymodiolus platifrons     

MENG Jie  YANG Mei  XU Fei  LI Xinzheng  LI Li 《海洋学报(英文版)》2018,(8)

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机载条纹管成像激光雷达在拍岸区探测水雷          下载免费PDF全文

王力  刘峡  王玥  吴中平 《数字海洋与水下攻防》2018,1(1):30-33

为了解决拍岸区水雷探测的问题，以无人机为载体的条纹管成像蓝绿激光雷达可以用来扫描、识别水雷，蓝绿激光成像雷达白天和夜晚均可以稳定成像，机载探测方式相对于水下、水面等传统探测方式效率也可以提高，机载激光雷达可由小型船舶、小型汽车等多平台携带使用。  相似文献   

Relation of Velocity Distribution and Mass for DA White Dwarfstwo     

Xiao-bo Gong  Li-fang Li 《Chinese Astronomy and Astrophysics》2018,42(2):202-212

White dwarfs are the evolutionary endpoint of the low-and-medium mass stars. In the studies of white dwarfs, the mass of white dwarf is an important physical parameter. In this paper, we give an analysis about the velocity distribution of DA white dwarfs in the Sloan Digital Sky Survey (SDSS), and hope to find the relation between mass and velocity distribution of white dwarfs. We get the radial velocity and tangential velocity of every DA white dwarf according to their proper motion and spectral shift. Through analyzing the velocity distribution of DA white dwarfs, we find that the small-mass white dwarfs, which are produced from the single-star evolution channel, have a relatively large velocity dispersion.  相似文献   

Retrieval of atmospheric mass densities in lower thermosphere below 200 km from precise orbit of re-entry object CZ-3B R/B by analytical and numerical methods     

Ming-Jiang Zhang  Hong-Bo Wang  Chang-Yin Zhao  Jian-Ning Xiong  Dong Wei  Wei Zhang  Sheng-Xian Yu 《Astrophysics and Space Science》2018,363(8):175

Taking the re-entry object CZ-3B R/B (COSPAR identifier 2012-018D, NORAD catalog number 38253) as an example, retrieval of atmospheric mass densities in lower thermosphere below 200 km from its rebuilt precise orbit is studied in this paper. Two methodologies, i.e. analytical and numerical methods, are adopted in the retrieval. Basic principles of these two methodologies are briefly introduced. Based on the short-arc sparse observational data accumulated in the high accuracy re-entry prediction, orbit determinations of re-entry object CZ-3B R/B are performed sectionally, and then its precise orbit is rebuilt. According to the orbit theory, the variation of orbital semi-major axis of re-entry object CZ-3B R/B induced by atmospheric drag perturbation only is derived from the rebuilt precise orbit. In the derivation of secular change of the orbital semi-major axis of re-entry object CZ-3B R/B induced by atmospheric drag perturbation only, the time-span is set as one minute tentatively. And then retrieval results of atmospheric mass densities in lower thermosphere below 200 km by analytical and numerical methods are presented, as well as their bias deviations from the calculated results of the NRLMSISE-00 empirical model of the atmosphere. Setting bias deviation bands, the corresponding ‘confidence coefficients’ of the retrieved atmospheric mass densities with respect to the model values are given. Average bias deviations of the retrieved atmospheric mass densities by analytical and numerical methods from the model values are also calculated respectively. On the whole, the retrieved atmospheric mass densities by numerical method approach to the model values more closely; the differences between the retrieved results and the model values are relatively smaller at the peaks of atmospheric mass densities than the other places.  相似文献   

The nature of the L chondrite parent body's disruption as deduced from high-pressure phases in the Sixiangkou L6 chondrite          下载免费PDF全文

Shaolin Li  Weibiao Hsu 《Meteoritics & planetary science》2018,53(10):2107-2122

The disruption of the L chondrite parent body (LCPB) at ~470 Ma is currently the best-documented catastrophic celestial impact event, based on the large number of L chondritic materials associated with this event. Uranium-lead (U-Pb) dating of apatite and its high-pressure decomposition product, tuite, in the Sixiangkou L6 chondrite provides a temporal link to this event. The U-Pb system of phosphates adjacent to shock melt veins was altered to varying degrees and the discordance of the U-Pb system correlates closely with the extent of apatite decomposition. This suggests that the U-Pb system of apatite could be substantially disturbed by high-temperature pulse during shock compression from natural impacts, at least on the scale of mineral grains. Although many L chondrites can be temporally related to the catastrophic LCPB impact event, the shock conditions experienced by each individual meteorite vary. This could be due to the different geologic settings of these meteorites on their parent body. The shock pressure and duration derived from most meteorites may only reflect local shock features rather than the impact conditions, although they could provide lower limits to the impact conditions. The Sixiangkou shock duration (~4 s), estimated from high-pressure transformation kinetics, provides a lower limit to the high-pressure pulse of the LCPB disruption impact. Combined with available literature data of L chondrites associated with this impact event, our results suggest that the LCPB suffered a catastrophic collision with a large projectile (with a diameter of at least 18–22 km) at a low impact velocity (5–6 km s⁻¹). This is consistent with astronomical estimates based on the dynamical evolution of L chondritic asteroids.  相似文献   

Analytical study of ground motion caused by seismic wave propagation across faulted rock masses          下载免费PDF全文

J.C. Li  N.N. Li  S.B. Chai  H.B. Li 《国际地质力学数值与分析法杂志》2018,42(1):95-109

Studying seismic wave propagation across rock masses and the induced ground motion is an important topic, which receives considerable attention in design and construction of underground cavern/tunnel constructions and mining activities. The current study investigates wave propagation across a rock mass with one fault and the induced ground motion using a recursive approach. The rocks beside the fault are assumed as viscoelastic media with seismic quality factors, Q_p and Q_s. Two kinds of interactions between stress waves and a discontinuity and between stress waves and a free surface are analyzed, respectively. As the result of the wave superposition, the mathematical expressions for induced ground vibration are deduced. The proposed approach is then compared with the existing analysis for special cases. Finally, parametric studies are carried out, which includes the influences of fault stiffness, incident angle, and frequency of incident waves on the peak particle velocities of the ground motions.  相似文献   

Implementation of a coupled plastic damage distinct lattice spring model for dynamic crack propagation in geomaterials          下载免费PDF全文

Chao Jiang  Gao‐Feng Zhao 《国际地质力学数值与分析法杂志》2018,42(4):674-693

This paper studies dynamic crack propagation by employing the distinct lattice spring model (DLSM) and 3‐dimensional (3D) printing technique. A damage‐plasticity model was developed and implemented in a 2D DLSM. Applicability of the damage‐plasticity DLSM was verified against analytical elastic solutions and experimental results for crack propagation. As a physical analogy, dynamic fracturing tests were conducted on 3D printed specimens using the split Hopkinson pressure bar. The dynamic stress intensity factors were recorded, and crack paths were captured by a high‐speed camera. A parametric study was conducted to find the influences of the parameters on cracking behaviors, including initial and peak fracture toughness, crack speed, and crack patterns. Finally, selection of parameters for the damage‐plasticity model was determined through the comparison of numerical predictions and the experimentally observed cracking features.  相似文献   

Photometric Follow-up Transit (Primary Eclipse) Observations of WASP-43 b and TrES-3b and A Study on Their Transit Timing Variations     

Sun Zhao  Ji Jiang-hui  Dong Yao 《Chinese Astronomy and Astrophysics》2018,42(1):101-128

Two photometric follow-up transit (primary eclipse) observations on WASP-43 b and four observations on TrES-3 b are performed using the Xuyi Near-Earth Object Survey Telescope. After differential photometry and light curve analysis, the physical parameters of the two systems are obtained and are in good match with the literature. Combining with transit data from a lot of literature, the residuals (O ? C) of transit observations of both systems are fitted with the linear and quadratic functions. With the linear fitting, the periods and transit timing variations (TTVs) of the planets are obtained, and no obvious periodic TTV signal is found in both systems after an analysis. The maximum mass of a perturbing planet located at the 1:2 mean motion resonance (MMR) for WASP-43 b and TrES-3 b is estimated to be 1.826 and 1.504 Earth mass, respectively. By quadratic fitting, it is confirmed that WASP-43 b may have a long-term TTV which means an orbital decay. The decay rate is shown to be P? = (?0.005248 ± 0.001714) s·yr^?1, and compared with the previous results. Based on this, the lower limit of the stellar tidal quality parameter of WASP-43 is calculated to be ${Q^{\prime }}_{*}\ge 1.5\times {10}^5$, and the remaining lifetimes of the planets are presented for the different ${Q^{\prime }}_{*}$ values of the two systems, correspondingly.  相似文献