广东省地方防震减灾工作思路与实践     

邹波 《华南地震》1999,19(4):82-87

防震减灾的四个环节,包括地震重点监视防御区的工作和实现全省防震减灾十年目标的任务,最终实施都得依赖市,县地地震工作机构的落实。根据广东省的政治,经济,社会发展以有震情特点,介绍了近两个来地方防震减灾工作的思路与实践,为今后的工作有益的借鉴。  相似文献   

SS-Y型伸缩仪观测问题分析及优化方法探讨     

杨江  李静渊  余剑锋  李农发 《地震地磁观测与研究》2020,(1):91-98

SS-Y型伸缩仪在我国地震洞体形变监测台网中已安装使用多年.对地球固体潮观测而言,仪器观测资料精度高且长期稳定性较好,但从地震预测的观测需求来看,SS-Y型伸缩仪仍然存在很多不足,如高频信息缺失、抗干扰能力较弱、存在格值误差、自校验能力较差等.对伸缩仪存在的问题进行分析,并提出一种超宽频带短基线伸缩仪的设计思路,以期为后续新仪器的研制提供理论依据.  相似文献   

4A沸石吸附模拟核素Sr,Cs后的组分变化和结构表征   总被引：6，自引：2，他引：4  

易发成  金承黎  李玉香 《矿物岩石》2005,25(2):35-39

通过4A沸石吸附模拟核素Sr,Cs前后的化学成分分析、X衍射分析和红外光谱分析等手段方法,分析探讨了模拟核紊Sr,Cs在4A沸石的赋存状态,结果表明：4A沸石与模拟核素Sr,Cs之间主要以离子交换的方式发生作用,Sr^2 ,Cs^ 取代4A沸石中的可交换离子Na^ ,占据4A沸石a笼中的6元环和8元环。导致4A沸石的晶胞参数增大,晶格发生畸变。  相似文献   

基于全天空F-P干涉仪反演热层垂直中性风   总被引：4，自引：0，他引：4       下载免费PDF全文

胡国元  艾勇  张燕革  刘珏  顾健 《地球物理学报》2014,57(11):3695-3702

由于测量与计算的难度,对热层垂直中性风的观测还很不够,这影响了人们对热层及热层-电离层耦合的认识.本文基于全天空法布里-珀罗干涉仪(FPI)对热层风场的观测,提出了一种反演垂直中性风的方法.利用该方法,对北极黄河站全天空FPI观测数据进行了垂直中性风的反演计算,结果表明,高热层与低热层的垂直风平均幅值分别在40 m·s^-1和15 m·s^-1,且垂直风日变化表现出明显的时间演变特性,且与地磁ap指数的变化有一定的相关性,在地磁活动强烈时,低热层垂直风会出现高达100 m·s^-1的扰动,高热层甚至会达到300 m·s^-1的扰动,这些特征与其他学者的观测结果相一致.本文方法不需要假设垂直风均值为零,也不用限制FPI的观测方位,可用于垂直风的反演.  相似文献   

洪水预报中特征值预报的若干数学方法比较   总被引：1，自引：0，他引：1  

李致家  孔祥光 《湖泊科学》1997,9(2):117-122

讨论研究了水文特征值预报的数学方法,统计回归模型、神经网络模型和模糊回归模型。三个计处实例表明如果系统的线性关系较好,统计回归模型的结果最好;如果系统的线民生关系差,神经网络模型的结果最好;如果用于率定模型的资料太短,任何一个模型都不可靠。  相似文献   

Pore‐scale modeling of surface erosion in a particle bed     

Y. Abdelhamid  U. El Shamy 《国际地质力学数值与分析法杂志》2014,38(2):142-166

A fully coupled transient two‐dimensional model was employed to study fundamentals of flood‐induced surface erosion in a particle bed. The interaction of the liquid and solid phases is the key mechanism related to surface erosion. The solid phase was idealized at a particle scale by using the discrete element method. The fluid phase was modeled at a mesoscale level and solved using the lattice Boltzmann method. The fluid forces applied on the particles were calculated on the basis of the momentum the fluid exchanges with the particle. The proposed approach was used to model both single particles and particle beds subjected to Couette flow conditions. The behavior of both the single particle and the particle bed depended on particle diameter and surface shear fluid velocity. The conducted simulations show that the fluid flow profile penetrates the bed for a small distance. This penetration initiates sheet‐flow and surface erosion as the fluid interacts with particles. The effect of suppressing particle rotation on the fluid‐induced forces on the particle was also examined. Suppressing particle spinning may lead to underestimated erosion rate. Results of fluid and particle velocities were compared against experimental results and appeared to agree with the observed trends.Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

云南者桑金矿床富金矿石类型与地球化学特征研究          下载免费PDF全文

李国  皮桥辉  韦朝文  吴建标  杨雄  李林威 《山东国土资源》2019,35(3)

云南富宁者桑金矿床位于我国滇黔桂"金三角"区域,是该区的大型卡林型金矿床之一。为了更为详细地了解卡林型金矿在富金矿石中的赋存状态以及地球化学特征,该文以者桑金矿床中几种不同类型赋金矿石:辉绿岩型矿石、泥质板岩或粉砂岩型矿石、泥灰岩型矿石的载金黄铁矿及毒砂为研究对象,进行矿物特征观察和地球化学特征分析。结果表明:辉绿岩型矿石中,破碎状毒砂、细粒自形毒砂、拉长菱形毒砂的尖端含金性较优;泥质板岩或粉砂岩型矿石中,脉状黄铁矿集合体、粗粒自形五角十二面体含金性较优;泥灰岩型矿石普遍含金,其中细粒菱形毒砂的含金性尤为显著。不同矿石类型中载金矿物的含金性与硅化、炭化、绢云母化等密切相关;黄铁矿w(Fe)、w(S)关系,黄铁矿、毒砂晶形特征以及微量元素Co/Ni关系,揭示者桑金矿床属中—低温热液成因;Au-As关系表明者桑金矿床金主要是以"不可见"形式的晶格金和纳米金赋存于赋金矿石中。  相似文献   

Comparison of scenario‐neutral approaches for estimation of climate change impacts on flood characteristics     

Luise Keller  Ole Rssler  Olivia Martius  Rolf Weingartner 《水文研究》2019,33(4):535-550

Scenario‐neutral assessments of climate change impact on floods analyse the sensitivity of a catchment to a range of changes in selected meteorological variables such as temperature and precipitation. The key challenges of the approach are the choice of the meteorological variables and statistics thereof and how to generate time series representing altered climatologies of the selected variables. Different methods have been proposed to achieve this, and it remains unclear if and to which extent they result in comparable flood change projections. Here, we compare projections of annual maximum floods (AMFs) derived from three different scenario‐neutral methods for a prealpine study catchment. The methods chosen use different types of meteorological data, namely, observations, regional climate model output, and weather generator data. The different time series account for projected changes in the seasonality of temperature and precipitation, in the occurrence statistics of precipitation, and of daily precipitation extremes. Resulting change in mean AMF peak magnitudes and volumes differs in sign between the methods (range of ?6% to +7% for flood peak magnitudes and ?11% to +14% for flood volumes). Moreover, variability of projected peak magnitudes and flood volumes depends on method with one approach leading to a generally larger spread. The differences between the methods vary depending on whether peak magnitudes or flood volumes are considered and different relationships between peak magnitude and volume change result. These findings can be linked to differing flood regime changes among the three approaches. The study highlights that considering selected aspects of climate change only when performing scenario‐neutral studies may lead to differing representations of flood generating processes by the approaches and thus different quantifications of flood change. As each method comes with its own strengths and weaknesses, it is recommended to combine several scenario‐neutral approaches to obtain more robust results.  相似文献   

A coupled 3‐dimensional bonded discrete element and lattice Boltzmann method for fluid‐solid coupling in cohesive geomaterials          下载免费PDF全文

Min Wang  Y.T. Feng  G.N. Pande  T.T. Zhao 《国际地质力学数值与分析法杂志》2018,42(12):1405-1424

This paper presents a 3D bonded discrete element and lattice Boltzmann method for resolving the fluid‐solid interaction involving complicated fluid‐particle coupling in geomaterials. In the coupled technique, the solid material is treated as an assembly of bonded and/or granular particles. A bond model accounting for strain softening in normal contact is incorporated into the discrete element method to simulate the mechanical behaviour of geomaterials, whilst the fluid flow is solved by the lattice Boltzmann method based on kinetic theory and statistical mechanics. To provide a bridge between theory and application, a 3D algorithm of immersed moving boundary scheme was proposed for resolving fluid‐particle interaction. To demonstrate the applicability and accuracy of this coupled method, a benchmark called quicksand, in which particles become fluidised under the driving of upward fluid flow, is first carried out. The critical hydraulic gradient obtained from the numerical results matches the theoretical value. Then, numerical investigation of the performance of granular filters generated according to the well‐acknowledged design criteria is given. It is found that the proposed 3D technique is promising, and the instantaneous migration of the protected soils can be readily observed. Numerical results prove that the filters which comply with the design criteria can effectively alleviate or eliminate the appearance of particle erosion in dams.  相似文献   

Selection of scale can reverse the importance of stochastic controls on community assembly     

Daehyun Kim 《自然地理学》2019,40(2):111-126

Reconciling the long-standing debate on the importance of niche-related and neutral factors on community assembly, recent research suggests that both deterministic and stochastic processes operate simultaneously along a continuum in many biogeographical systems. In particular, stochastic processes seem to lose importance under stressful conditions, which results in the increasing influence of deterministic counterparts. In this paper, I show that, at local scales, this stochasticity–stress relationship can be reversed along the environmental stress gradients within a salt marsh: stochasticity manifested under harshness. Here, low-lying, more stressful sites contained all of the plant species of the local pool (i.e. a greater chance of ecological drift), whereas high-elevation, less stressful sites exhibited reduced species richness due to competitive exclusion (i.e. a lower chance of ecological drift). I conclude that determining whether the importance of stochasticity in shaping community structure is greater under benign or harsh conditions depends on the scale of interest.  相似文献