连云港地震台BBVS-120、CTS-1E型地震计系统性能对比     

立凯  秦磊  曾智  孙雷 《地震地磁观测与研究》2021,43(1):106-110

通过对连云港地震台BBVS-120、CTS-1E型地震计台基噪声功率谱分析,正弦标定和脉冲标定计算分析,近震和远震震级对比分析,研究在实际工作中2种地震计性能差异,对比观测数据质量,检验稳定性,以期为地震监测及相关研究工作提供依据。  相似文献   

腮腺良性肿瘤容积穿梭CT灌注时间-密度曲线特征分析          下载免费PDF全文

杨振兴  郝粉娥  赵磊  杨晓光  刘挨师 《CT理论与应用研究》2021,30(5):575-582

目的:探讨容积穿梭CT灌注时间-密度曲线特征结合形态学参数对腮腺良性肿瘤鉴别诊断的价值。方法:收集我院拟诊腮腺肿瘤患者100例,术前均行容积穿梭CT灌注成像检查,术后经手术病理证实。将所得影像数据传送至工作站及pacs系统,观察分析不同病理类型腮腺肿瘤的形态学参数（位置、大小、密度、边界、颈部淋巴结、增强扫描强化幅值）及时间-密度曲线（TDC）类型,计数资料比较采用χ2检验,计量资料符合正态分布采用两独立样本t检验,不符合正态分布的采用秩和检验,检验水准α=0.05。结果:腮腺良性肿瘤（多行性腺瘤、腺淋巴瘤、基底细胞瘤及肌上皮瘤）间的形态学参数无统计学差异;时间-密度曲线类型差异有统计学差异。结论:CT灌注时间-密度曲线特征结合形态学参数对腮腺良性肿瘤的鉴别诊断有重要价值,为患者术式的选择有重要指导意义。   相似文献   

基于机器学习的地震动特征提取与模拟以2021年云南漾濞6.4级地震为例          下载免费PDF全文

靳超越  胡进军  胡磊  王中伟 《世界地震工程》2021,(4):073-80

随着地震动数据数量的增长和质量的提高,将基于数据驱动的机器学习方法应用到地震动模拟中有重要意义。以2021年5月21日云南漾濞M_S6.4地震为例,利用主成分析方法从前震及余震地震动记录中提取特征母波时程,将地震动三要素作为模拟误差约束,在求解母波的线性组合系数时使用多目标优化算法寻优,最终找到帕累托最优解作为模拟目标台站记录时的组合系数,得到模拟地震动时程。结果表明:主成分析法在对实际地震动记录进行特征提取后,得到的特征母波时程可以在一定程度上保留原始数据的主要信息;考虑幅值、频谱和持时这三要素的角度去控制模拟误差,可以使得模拟的地震动时程更加接近真实记录。提出的基于特征提取的地震动模拟方法可以为基于小震数据合成大震地震动提供参考。  相似文献   

Statistics of long-crested extreme waves in single and mixed sea states     

Wang  Lei  Li  Jinxuan  Liu  Shuxue  Ducrozet  Guillaume 《Ocean Dynamics》2021,71(1):21-42

Ocean Dynamics - Most of the studies on extreme waves are focused on the systems with single-peak wave spectra. However, according to the statistics of occurrence, the bimodal spectral system is...  相似文献   

The Responses of the Deformable Earth to Different Driving Forces     

Han-wei Zhang  Qiong-xian Tie  Lei Yang 《Chinese Astronomy and Astrophysics》2008,32(2):209-215

The spatial and temporal variations of the Earth deformation and the gravitational field are important both in the theoretical research and in the construction of geospatial database. The Earth deforms due to various mechanisms and the deformation further induces changes in the gravitational potential of the Earth, i.e. the deformation-induced additional potential or the Euler gravitational increment. Based on the theory of vector spherical harmonics, we discuss in this paper the Earth deformation and gravitational increment resulting from the tidal force, loading force and the stress of the Earth's surface. We write out the expression for the Euler gravitational potential increment and the relations between different Love numbers. These are all important points in the research on Earth deformation.  相似文献   

Calculation of the Intensity Ratio and Intrinsic Redshift Ratio of the Cerenkov Iron K_α and K_β Lines and Its Possible Application in the Study of AGNs     

Dang-bo Liu  Lei Chen  Jun-han You 《Chinese Astronomy and Astrophysics》2008

We have pointed out that, when thermal relativistic electrons with an isotropic velocity distribution move through a region of dense gas or impinge upon its surface, the Cerenkov effect will produce a particular kind of atomic or ionic emission line, which we have called the “Cerenkov line-like radiation”. This prediction for the optical wavebands has been verified by laboratory experiments. In this paper, we extend this line-like radiation theory to the X-ray waveband and give the basic formulae for calculating the intensity ratio and intrinsic redshift ratio of the Cerenkov iron K_α and K_β lines, for different ionization orders of iron. Potential application of this calculated result may be found in the study of AGNs. The recent observations of NGC3783 show that besides the iron K_α line at ∼6.4 keV, there is also a very strong iron Kβ line at ∼7.0 keV, and that the ratio of equivalent widths between the two is anomalous: EWK_α/EWK_β ≈ 3.43. It is difficult to explain this by the conventional mechanism of “photoelectric absorption-fluorescence emission”. We suggest that the mechanism of Cerenkov line-like radiation can provides a way of solving this puzzle. Besides, we expect that the calculated intrinsic redshift ratio of Cerenkov iron K_α and K_β lines could be tested in future observations. If our suggestion is further supported by observations, then our view on the physical environment around the central massive black hole of an AGN will be greatly modified: the activity becomes more energetic and violent, and the gas, much denser than previously thought.  相似文献   

The Effect of AGN and SNe Feedback on Star Formation, Reionization and the Near Infrared Background     

Lei Wangt Ji-Rong Mao Shou-Ping Xiang Ye-Fei Yuan 《中国天文和天体物理学报》2008,8(6)

Feedback from supernovae (SNe) and from active galactic nuclei (AGN) accom-panies the history of star formation and galaxy evolution. We present an analytic model to explain how and when the SNe and AGN exert their feedback effects on the star formation and galaxy evolution processes. By using SNe and AGN kinetic feedback mechanisms based on the Lambda Cold Dark Matter (LCDM) model, we explore how these feedback mecha-nisms affect the star formation history (SFH), the Near-Infrared Background (NIRB) flux and the cosmological reionization. We find the values of the feedback strengths, ∈AGN =1.0+0.50.3and ∈SN=0.04+0.02-0.02, can provide a reasonable explanation of most of the observational re-suits, and that the AGN feedback effect on star formation history is quite different from the SNe feedback at high redshifts. Our conclusions manifest quantitatively that these feedback effects decrease star formation rate density (SFRD) and the NIRB flux (in 1.4 - 4.0μm), and postpone the time of completion of the cosmological reionization.  相似文献   

中国优质碎屑岩深层储层控制因素综述   总被引：18，自引：2，他引：16  

李会军  吴泰然  吴波  朱雷  郭光立 《地质科技情报》2004,23(4):76-82

根据中国深层储层分布广,地质条件差异大的实际情况,认为沉积环境、地温、深埋藏时间、溶解与胶结作用、烃类充注、异常压力、绿泥石环边为深层储层的主要控制因素,并对每一种因素作了具体分析,指出深层储层的分布可以用3种模式来进行预测。  相似文献   

并行电法在大坝爆破振动评价中的应用   总被引：1，自引：0，他引：1  

谭磊  江晓益  江树 《地质论评》2019,65(Z1):27-29

正钻爆法是硬质岩地区隧道施工的重要工艺,但爆破振动对周围建筑物的破坏损伤也越成为不容忽视的问题(邓成发等,2012)。对爆破振动的安全评估的方法较多,包括有限元的数值模拟分析、构建相似物理模型以及现场的爆破振动监测等技术手段。其中,原位质点振动仪的速度或加速度的动态采集及分析为施工爆破的控制提供重要的依据,但不能反映结构体内部的应力状态和特性,无法揭示建筑物爆破前后的破坏机理。  相似文献   

秦岭岩群中斜长角闪岩的年代学及地质意义     

柏治安  时毓  刘希军  刘磊  赵增霞  黄倩雯 《地质论评》2019,65(Z1):41-42

正秦岭造山带是华北陆块和扬子陆块及其间的微陆块经历了多期拼合而形成的,具有复杂的构造演化史,前人已对其形成与演化过程进行了大量的研究工作,但在许多方面的研究仍未获得统一的认识(张国伟等,1988;张本仁等2002)。秦岭岩群是北秦岭造山带的主体,保存了复杂的变质变形记录,准确有效地获取和判断其基底岩石的形成和变质时代是探讨秦岭岩群乃至整个秦岭造山带形成  相似文献