复合地震源模拟强地面运动-以1679年三河-平谷Memssub8.0地震为例

利用复合震源模型和人工合成地震图的算法, 以1679年三河——平谷Ms8.0地震为例,计算了北京地区的宽频带强地面运动. 其结果可为今后该地区的地震危险性评估和工程抗震提供一定的物理参数. 通过考察该地区的地质与地球物理区域背景, 利用计算机数值模拟的方法, 对北纬39.3deg;~41.1deg;东经115.35deg;~117.55deg;所围限的北京范围进行了设定地震的仿真模拟,并合成了强地面运动. 通过分析影响强地面运动的几个关键因素,给出了北京地区强地面运动峰值加速度和速度分布特征,比较了合成强地面运动记录与通过衰减关系计算所得的结果. 同时,还对复合震源模型的优点和局限性给出了充分的讨论. 利用数值模拟方法所得的较为真实的强地面运动参数,即加速度、速度、位移和时程特征,可为北京地区工程建设的抗震设计、救援设施的选址、以及金融及保险部门的风险性评估提供一定的依据.     

Constructing geo-information sharing architecture

Along with the development of Internet, geo-information sharing and Open GIS are of increasing importance for GIS application fields. Southwestern China consists of several provinces or districts, they are Sichuan, Guizhou, Yunnan, Chongqing, etc. The economic and information cooperation among them are of significance. The pilot platform for resource and environment geo-information sharing for the southwestern China based on Web services, OGC (Open GIS Consortium) WFS (Web feature service) is constructed. Via this pilot platform, a loose information sharing mode can be implemented to improve their cooperation level.     

汶川MW7.9地震余震序列触发机制研究

余震触发机制的Dieterich解析模型被广泛应用于区域地震活动性的定量分析以及依赖时间的概率地震预测模型的建立等方面. 基于滑移速率和状态相依赖的摩擦定律和弹簧-滑块模型, 从Dieterich断层滑移速率方程出发, 给出了静态应力扰动下触发地震的时钟提前或推后的近似解, 从而明确地阐明了触发地震的产生机制与断层的演化过程密切相关, 并与传统位错模型下库仑应力扰动时间提前或推后量作了比较. 采用对数线性拟合方法求得了汶川M_W7.9主震后余震序列持续时间, 符合Dieterich理论结果. 以汶川余震序列为例, 给出了两种不同的应力扰动模式在该余震序列中的应用. 结果表明, 经典Dieterich扰动解无法给出主震发生后即时余震数量的异常增加, 而考虑主震前后剪应力速率变化的Dieterich分段解则可反映出余震发生率及个数随时间的演化特征.      

Three-Dimensional Structural Geological Modeling Using Graph Neural Networks

Mathematical Geosciences - Three-dimensional structural geomodels are increasingly being used for a wide variety of scientific and societal purposes. Most advanced methods for generating these...     

河北南网架空导线载流量相关气象参数分析

传统上架空线路允许最大载流量是依据固化的、苛刻的气象参数组合来确定的,其计算结果往往偏于保守。为使允许最大载流量设定更接近实际气象情况,本研究结合河北南部94个自动气象站点逐时观测数据驱动导线热平衡方程进行载流量分析,将传统恒定载流量转换为季节变动的载流量,以充分挖掘河北南网架空导线输电能力。在分析允许最大载流量对环境风速和气温变化的敏感程度基础上,确定了环境气温和风速两种气象参数的概率密度分布,并获取了区域允许最大载流量的概率分布,评估了不同安全运行概率下的输电能力。结果表明,在95%的安全运行保障下,河北南部LGJ-400/35型架空导线最大载流量在春夏秋冬四季可分别设定为945、774、795和1012A,显著高于传统载流量定值。在季节尺度上,基于实际气象参数调整的河北南部架空导线载流量设定有效地挖掘了电网输电能力。     

A brief discussion on the relationship between apparent stress and slip-weakening law based on the energy partition criteria

According to the representation theorem of seismic energy radiation,we know that,at any point on the fault,the instantaneous seismic radiation energy,ES,the seismic moment M0,and the apparent stress σa=μES /M0(μ is the shear modulus on the fault plane) should be positive values at any time during an earthquake faulting.However,we have noticed that,in recent source parameter inversion scheme for deriving the critical slip-weakening distance,the apparent stress used as a constraint condition on the fault plan...     

中国地区IPCC A1B情景下21世纪中期气候变化的数值模拟试验

利用MM5V3区域气候模式单向嵌套ECHAM5全球环流模式的结果,对中国地区实际温室气体浓度下当代气候(1981—2000年)及IPCC A1B情景下21世纪中期气候(2041—2060年)分别进行了水平分辨率为50 km的模拟试验。首先检验全球和区域模式对当代气候的模拟情况,结果表明:区域模式对中国地区地面温度和降水空间分布的模拟能力优于全球模式;与实际观测相比,区域模式模拟的地面温度在中国大部分地区偏低,模拟的降水量偏多,降水位置偏北。IPCCA1B情景下中国地区21世纪中期气候变化的模式结果显示:各季节地面温度在全国范围内都将比当代升高1.2～3.9℃,且升温幅度具有北方大于南方、冬季大于夏季的时空分布特征;降水变化具有一定的区域性和季节性,秋季和冬季降水在全国大部分地区都将增加10%～30%,春季和夏季降水则呈现"北方减少、南方增多"的趋势,变化幅度在-10%～10%之间。21世纪中期地面温度和降水变化还具有一定的年际特征:地面温度在中国地区各子区域均表现为上升趋势,升温速率在0.7～0.9℃/10a之间,温度变率也比当代有所增大;降水在西北地区略呈下降趋势,在其它子区域均为上升,降水变率的变化具有区域性特征。     

The retrieval of the Asian dust depolarization ratio in Korea with the correction of the polarization-dependent transmission

The linear particle depolarization ratios were retrieved from the observation with a multiwavelength Raman lidar at the Gwangju Institute of Science and Technology (GIST), Korea (35.11°N, 126.54°E). The measurements were carried out in spring (March to May) 2011. The transmission ratio measurements were performed to solve problems of the depolarization-dependent transmission at a receiver of the lidar and applied to correct the retrieved depolarization ratio of Asian dust at first time in Korea. The analyzed data from the GIST multiwavelength Raman lidar were classified into three categories according to the linear particle depolarization ratios, which are pure Asian dust on 21 March, the intermediate case which means Asian dust mixed with urban pollution on 13 May, and haze case on 10 April. The measured transmission ratios were applied to these cases respectively. We found that the transmission ratio is needed to be used to retrieve the accurate depolarization ratio of Asian dust and also would be useful to distinguish the mixed dust particles between intermediate case and haze. The particle depolarization ratios of pure Asian dust were approximately 0.25 at 532 nm and 0.14 at 532 nm for the intermediate case. The linear particle depolarization ratios of pure Asian dust observed with the GIST multiwavelength Raman lidar were compared to the linear particle depolarization ratios of Saharan dust observed in Morocco and Asian dust observed both in Japan and China.     

Finding Science with Science: Evaluating a Domain and Scientific Ontology User Interface for the Discovery of Scientific Resources

Current approaches to the discovery of scientific resources (publications, data sets and web services) are dominated by keyword search. These approaches do not allow scientists to search on the deeper semantics of scientific resources, or to discover resources on the basis of the scientific approaches taken. This article evaluates a user interface that allows users to discover scientific resources through structured knowledge in the form of ontologies describing the domain and the scientific knowledge inherent within the scientific resource, and also through informal user tags. These combined capabilities provide scientists with new and powerful options for resource discovery. A qualitative user evaluation explored how scientists felt about the approach for resource discovery in the context of their scientific work. The study showed that marine scientists were enthusiastic about the capabilities of such an approach and appreciated the ability to browse the visual structure of the knowledge and query on scientific method but, overall, preferred the use of tags over ontologies. The exploratory nature of the user study was used to identify future directions for such improvements.     

Characterizing and representing inference histories in geologic mapping

Evaluation of the utility of a geologic map can require understanding of its knowledge evolution. In such cases, online usage further requires machine representation of both the knowledge and the evolution. To meet these needs, an informal structure is developed here that involves the interaction of the three reasoning forms of abduction, induction, and deduction. Empirical results are presented that support the structure, and a foundational ontology for science knowledge is adapted to represent the structure. These results lead to a new understanding of the role of the three reasoning forms in geologic mapping and constitute a new approach to the machine representation of geologic knowledge evolution. The approach also has potential to characterize the mapping of many types of geographic regions.