大气电场异常作为地震短临预报标志研究进展   总被引：5，自引：0，他引：5  

郝建国  唐天明 《地震》1998,18(3):245-256

通过对华北地地区进行震前大气电场异常观测研究的较为全面分析和总结,验证和论述了震前大气电场异常的基本特征,用大量的震例证实了在每次较大的近场地震发生前都能观测到该类异常现象,以及当较长一段时间内观测不到该类异常时,近场近期也不会有较大地震发生的可能。  相似文献   

南京地区大气冰核浓度的测量及分析   总被引：5，自引：2，他引：3  

杨磊  银燕  杨绍忠  蒋惠  肖辉  陈倩  苏航  陈聪 《大气科学》2013,37(3):579-594

2011年5～8月期间使用5L混合型云室以及静力扩散云室对南京不同成核机制的大气冰核进行了观测,进而分析了近地层冰核浓度特征。结果表明:活化温度为－20°C时,5L混合型云室观测的总冰核浓度为20.11个/L,静力扩散云室模拟高水汽(计算的云室内水面过饱和度为5%)和低水汽(计算的云室内冰面过饱和度为5%)条件下冰核浓度分别为0.93个/L以及0.29个/L。晴好条件下冰核浓度具有明显的日变化特征,白天冰核浓度高于夜间;在下午时段冰核浓度达到全天最高值,这说明大气冰核可能与大气湍流强度、人类活动以及工业污染有关。降水对冰核的清除作用明显,台风系统过程中冰核浓度明显增加。南京地区冰核浓度随温度降低和湿度增加而增加。后向轨迹模式分析表明东北海洋气团冰核浓度最高,不同气团中冰核浓度的差异随着活化温度的降低而减小。个例分析秸秆燃烧生成的PM₁(大气中直径小于或者等于1 μm的颗粒物)与冰核关系发现燃烧产物对冰核有一定的贡献。  相似文献   

以静力触探为主提供土层承载力在淮安地区的初步验证          下载免费PDF全文

张学飞  赵建平 《江苏地质》2011,35(3):328-331

通过以淮安地区楚州园项目为例,介绍了该工程的概况、工程施工、检测结果、原因分析及其解决措施,从而验证以静力触探数据为土层承载力提供的主要依据而得出结果的准确性。  相似文献   

Empirical design of scour protections around monopile foundations: Part 1: Static approach     

Leen De Vos  Julien De Rouck  Peter Troch  Peter Frigaard 《Coastal Engineering》2011

Together with new opportunities, offshore wind farms raise new engineering challenges. An important aspect relates to the erosion of bottom material around the foundation of the wind turbines, caused by the local increase of the wave and current induced flow velocities by the pile's presence. Typically, the expected scour has a considerable impact on the stability and dynamic behavior of the wind turbine and a scour protection is placed to avoid erosion of the soil close to the foundation. Although much experience exists on the design of scour protections around bridge piers (which are placed in a current alone situation), at present, little design guidelines exist for the specific case of a scour protection around a monopile foundation subjected to a combined wave and current loading.  相似文献   

Perfect-fluid sources for the Levi-Civita metric     

Ramadan M. Ali 《Astrophysics and Space Science》2007,310(3-4):201-204

Cylindrically symmetric perfect fluid solutions are derived for the Levi-Civita metric. The pressure P is finite. The matter density is greater than the stresses in the material. The solutions are inside cylinders of bounded radius at which the pressure vanishes. The range of σ, for which the sources have been matched to the Levi-Civeta metric is ∞>σ>0. The solutions are regular and satisfy energy conditions  相似文献   

Coseismic deformation of the 2020 Yutian MW 6.4 earthquake from Sentinel-1A and the slip inversion     

《地震研究进展（英文）》2021,1(2):100027

A remarkable earthquake struck Yutian, China on June 26th, 2020. Here, we use Sentinel-1 images to investigate the deformation induced by this event. We invert the InSAR observations using a two-step approach: a nonlinear inversion to constrain fault geometries with uniform slip based on the rectangular plane dislocation in an elastic half-space, followed by a linear inversion to retrieve the slip distribution on the fault plane. The results show that the maximum LOS displacement is 22.6 ​cm, and the fault accessed to the ruptured characteristics of normal faults with the minor left-lateral strike-slip component. The fault model indicates a 210° strike. The main rupture zone concentrates in the depth of 5–15 ​km, and the fault slip peaks at 0.89 ​m at the depth of 9 ​km. Then, we calculate the variation of the static Coulomb stress based on the optimal fault model, the results suggest that the Coulomb stress of the Altyn Tagh fault and other neighboring faults has increased and more attention should be paid to possible seismic risks.  相似文献   

双桥静力触探成果估算单桩承载力在天津工程中的应用     

唐伯华 《西部资源》2014,(5):129-130

结合天津杰诺康园艺休闲用品有限公司年产5,000吨有色金属制品勘察项目,介绍运用静力触探成果估算天津软土地区单桩承载力在该工程中的应用。通过对比表明该方法的技术经济特点及可行性。  相似文献   

四川盆地一次当地排放和沙尘输送双重影响的区域空气重污染过程研究     

连俊标  王式功  罗彬  杜云松  张巍  蒋婉婷 《沙漠与绿洲气象(新疆气象)》2019,13(5):122-131

针对四川盆地大气污染及其成因的特殊性,本文使用四川盆地18个城市的大气污染监测和气象观测数据以及NCEP1°×1再分析资料,对2017年12月19日～2018年1月3日四川盆地由当地过量排放和外来沙尘输送双重影响的区域性大气污染过程进行分析。结果表明：2017年12月19～28日四川盆地环流场配置不利大气污染物扩散,垂直温度层结稳定,在当地污染源持续排放下污染物浓度缓慢上升,此阶段为静稳型大气污染。之后29日冷空气过程打破前期不利污染物扩散的环流场及垂直温度层结,导致气态污染物下降明显,但伴随冷空气活动的外来沙尘使PM10浓度迅速增大,使四川盆地部分城市出现沙尘型重污染;特别是广元地区受沙尘直接影响最严重,PM10浓度是原来的4.5倍;成都市虽没有通过沙尘天气的表观判断,但对颗粒物离子浓度和化学组分都有显著影响;因此,当时PM10和CO浓度24h比值变化受沙尘输送和天气条件共同影响,在不同时段和地区都存在明显差异,初步揭示出由静稳型大气污染向沙尘型污染转换阶段的内在变化特征,具有重要科学价值。  相似文献   

风廓线雷达回波参量估计算法验证及其地杂波抑制方法研究          下载免费PDF全文

张雯雯  刘黎平  阮征  葛润生 《高原气象》2011,30(4):1096-1101

估计天气状况的回波资料均由雷达厂家直接给出,其估计的准确性及精确度还有待验证。针对这一问题,改进了回波信号的模拟方法,给出了一套可行的检验目前估计各种雷达回波参数算法正确性的系统;同时为了减小地杂波对信号参数估计的影响,在静态小波变换的基础上,提出了一种抑制风廓线雷达地杂波的方法,这种方法通过计算各层小波系数上的二阶原...  相似文献   

Effect of physical parameters on static undrained resistance of sandy soil with low silt content     

M. Maleki  A. EzzatkhahM. Bayat  M. Mousivand 《Soil Dynamics and Earthquake Engineering》2011

Previous researches concerning the behavior of sand mixed with non-plastic fine show that the void ratio related to sand grains (e_c) plays a more important role in comparison with the total void ratio, where soil undrained resistance will be improved due to increase in FC at the constant e_c. In spite of this fact, the recent works indicate that e_c is unable to show perfectly the role of the non-plastic fines that are in voids between sand grains. For this reason, an equivalent void ratio (e_c)_eq has been defined that takes into account the non-plastic fine participation ratio in the soil bearing skeleton. In the present work, the generality of the expression of (e_c)_eq is verified. For this, a set of static undrained triaxial tests were performed. The results of tests indicate that the undrained behavior of a given sand mixed with different percentages of non-plastic fine can be described by (e_c)_eq. But if the grading curves of sand change, we cannot find a logic retention between (e_c)_eq and undrained resistance of soil, unless the physical and mechanical characteristics of soil are well introduced in expression of (e_c)_eq.  相似文献