二阶不稳定型中立型微分方程解的振动准则

改进不稳定型二阶中立型微分方程的最后结果,进一步研究该类方程解的振动条件。     

Three dimensional numerical simulation of residential building on shrink–swell soils in response to climatic conditions

Shrink–swell soils can cause distresses in buildings, and every year, the economic loss associated with this problem is huge. This paper presents a comprehensive system for simulating the soil–foundation–building system and its response to daily weather conditions. Weather data include rainfall, solar radiation, air temperature, relative humidity, and wind speed, all of which are readily available from a local weather station or the Internet. These data are used to determine simulation flux boundary conditions. Different methods are proposed to simulate different boundary conditions: bare soil, trees, and vegetation. A coupled hydro‐mechanical stress analysis is used to simulate the volume change of shrink–swell soils due to both mechanical stress and water content variations. Coupled hydro‐mechanical stress‐jointed elements are used to simulate the interaction between the soil and the slab, and general shell elements are used to simulate structural behavior. All the models are combined into one finite element program to predict the entire system's behavior. This paper first described the theory for the simulations. A site in Arlington, Texas, is then selected to demonstrate the application of the proposed system. Simulation results are shown, and a comparison between measured and predicted movements for four footings in Arlington, Texas, over a 2‐year period is presented. Finally, a three‐dimensional simulation is made for a virtual residential building on shrink–swell soils to identify the influence of various factors. Copyright © 2015 John Wiley & Sons, Ltd.     

兴1井水位的映震特征

兴1井是辽宁省内最早建成的静水位观测井，已有近20年的观测历史。系统分析预测以来的资料，发现该井水位有很强的映震能力并有一定的映震规律，可进行单井水位异常预报地震震级与发震时间的科学试验。     

Permian radiolarians,chert and basalt from the Daxinshan Formation in Lancangjiang belt of southwestern Yunnan,China

The stratigraphical sequences composed of chert and basalt were found in the Daxinshan area of Simao and the Manbie area of Jinghong, southwestern Yunnan. The Middle Permian to ealiest Late Permian radiolarians, such as Follicucullus and Pseudoalbaillella, have been identified from the chert. The chert from the Manbie area of Jinghong is characterized by high SiO₂content (over 92%), large ratios of MnO/TiO₂ (2.15) and low ratios of Al/(Al+Fe+Mn) (≤0.1) and Ce/Ce*(0.4), which indicate that the chert was deposited in pelagic basin. The chert from the Daxinshan area of Simao, however, is characterized by low SiO₂ content, low ratios of MnO/TiO₂ (0.27) and high ratios of Al/(Al+Fe+Mn) (0.49) and Ce/Ce*(0.88), which imply that the chert was deposited in continental margin basin. The basalts from the both areas belong to tholeiite series, and the chemical compositions of their major, rare earth and trace elements show the characteristics of MORB. These results evidence that there are volcanic rocks and chert sequences representing pelagic basin and oceanic basin near continent. These sequences and the formerly reported island-arc volcanic rock sequences imply that the Daxinshan Formation in the Lancangjiang belt represents a sedimentary assemblage formed in active continental margin basin.     

基于局部一维模型与走时标定的区域三维速度模型构建技术研究

构建区域介质三维速度模型并以之获得准确的区域震相走时,是提高区域地震定位精度的重要手段之一.为充分利用已有的一维模型、GT事件、地质资料等实现三维模型构建,尝试基于目标区域内已有的部分局部一维模型,通过克里金空间插值建立初始三维模型,然后利用GT事件走时数据并参考其它地震地质资料对其不断进行修正,使得其走时偏差图与GT事件走时偏差图一致,进而获得能够提高区域地震定位精度的三维模型.使用不同模型进行的地震定位实验表明,以此方法建立的三维模型的定位偏差较初始模型减少约20％,较好地起到了减小区域震相走时残差,提高区域地震定位精度的作用.     

鹤岗地震台DSQ型水管仪观测系统日常问题分析及维护

针对鹤岗地震台在实际工作中遇到的各种问题,结合台站实际情况,分别从主机系统、电子记录系统等方面,提出仪器运行中经常出现的问题.并总结DSQ水管仪在日常问题中系统维护的具体解决办法,以此提高观测质量和工作效率.     

关于Barban定理的推广

本文将Barban定理中和式形式加以推广,得到关于函数μ(n)的这种和式的估计。     

Deep Structure and Dynamics of Passive Continental Margin from Shelf to Ocean of the Northern South China Sea

To study the deep dynamic mechanism leading to the difference in rifting pattern and basin structure from shelf to oceanic basin in passive continental margin,we constructed long geological sections across the shelf,slope and oceanic basin using new seismic data.Integrated gravity-magnetic inversion and interpretation of these sections were made with the advanced dissection method.Results show that the basement composition changes from intermediate-acid intrusive rocks in the sheff to intermediate-basic rocks in the slope.The Moho surface shoals gradually from 31 km in the sheff to 22.5 km in the uplift and then 19 km in the slope and finally to 13 km in the oceanic basin.The crust thickness also decreases gradually from 30 km in the northern fault belt to 9 km in the oceanic basin.The crustal stretching factor increases from the shelf toward the oceanic basin,with the strongest extension under the sags and the oceanic basin.The intensity of mantle upwelling controlled the style of basin structures from sheff to oceanic basin.In the Zhu 1 depression on the shelf,the crust is nearly normal,the brittle and cold upper crust mainly controlled the fault development;so the combinative grabens with single symmetric graben are characteristic.In the slope,the crust thinned with a large stretching factor,affected by the mantle upwelling.The ductile deformation controlled the faults,so there developed an asymmetric complex graben in the Baiyun (白云) sag.     

Ensemble filter methods with perturbed observations applied to nonlinear problems

The ensemble Kalman filter (EnKF) has been shown repeatedly to be an effective method for data assimilation in large-scale problems, including those in petroleum engineering. Data assimilation for multiphase flow in porous media is particularly difficult, however, because the relationships between model variables (e.g., permeability and porosity) and observations (e.g., water cut and gas–oil ratio) are highly nonlinear. Because of the linear approximation in the update step and the use of a limited number of realizations in an ensemble, the EnKF has a tendency to systematically underestimate the variance of the model variables. Various approaches have been suggested to reduce the magnitude of this problem, including the application of ensemble filter methods that do not require perturbations to the observed data. On the other hand, iterative least-squares data assimilation methods with perturbations of the observations have been shown to be fairly robust to nonlinearity in the data relationship. In this paper, we present EnKF with perturbed observations as a square root filter in an enlarged state space. By imposing second-order-exact sampling of the observation errors and independence constraints to eliminate the cross-covariance with predicted observation perturbations, we show that it is possible in linear problems to obtain results from EnKF with observation perturbations that are equivalent to ensemble square-root filter results. Results from a standard EnKF, EnKF with second-order-exact sampling of measurement errors that satisfy independence constraints (EnKF (SIC)), and an ensemble square-root filter (ETKF) are compared on various test problems with varying degrees of nonlinearity and dimensions. The first test problem is a simple one-variable quadratic model in which the nonlinearity of the observation operator is varied over a wide range by adjusting the magnitude of the coefficient of the quadratic term. The second problem has increased observation and model dimensions to test the EnKF (SIC) algorithm. The third test problem is a two-dimensional, two-phase reservoir flow problem in which permeability and porosity of every grid cell (5,000 model parameters) are unknown. The EnKF (SIC) and the mean-preserving ETKF (SRF) give similar results when applied to linear problems, and both are better than the standard EnKF. Although the ensemble methods are expected to handle the forecast step well in nonlinear problems, the estimates of the mean and the variance from the analysis step for all variants of ensemble filters are also surprisingly good, with little difference between ensemble methods when applied to nonlinear problems.     

Tectonic evolution of the Late Paleozoic Early Mesozoic orogenic belt in the eastern segment of the northern margin of the North China Block: Evidence from meta volcanic rocks of Jianshanzi,northern Liaoning ProvinceSCIEI北大核心CSCD

LA-ICP-MS U-Pb dating, whole -rock geochemistry and Hf isotopic analyses for the Jianshanzi volcanic rocks in the Kaiyuan area are presented to explore the Late Paleozoic -Early Mesozoic tectonic evolution history of the eastern segment of the northern margin of the North China block. The detailed research indicates that the protolith of Jianshanzi metamorphic volcanic rocks includes rhyolite, dacite and andesite, they are calc-alkaline series and metaluminous-weak peraluminous rocks. According to the zircon U-Pb dating, the metamorphic rhyolite and metamorphic andesite formed in the Late Permian (256. 1 +/- 1. 5Ma, 252.4 +/- 1. 7Ma) and the Late Triassic (222. 4 +/- 1. 8Ma, 227. 9 +/- 1. 2Ma), respectively. They are characteristized by enrichment in light rare earth elements and large ion lithophile elements, and depletion of heavy rare earth elements and high field strength elements. Metamorphic rhyolite has an obvious negative Eu anomaly with epsilon(Hf) ( t) values of 10. 83 + 8. 10 and the second -stage model are 698 similar to 1967Ma. They are mainly due to the partial melting of the juvenile basaltic lower crust and the contamination of a small amount of ancient crustal materials. Metamorphic andesite has no obvious Eu anomaly, and the epsilon(Hf)( t) value and the second -stage model are +4.54 similar to + 6. 79 and 825 similar to 968 Ma, which may be the product of partial melting of basic lower crust. There are two periods of magmatism in Jianshanzi volcanic rocks: Late Permian -Early Triassic (247 similar to 256Ma) and Late Triassic (similar to 225Ma). The material composition of the Jianshanzi volcanic rocks is characterized by different times and different tectonic backgrounds. It is comprehensively believed that the eastern segment of the northern margin of the North China block was in an active continental margin tectonic environment during the Permian, and the Palaeo-Asian Ocean subducted in both directions; Mantle -derived magma ascends and emplaces, forming a nascent crust and causing crustal thickening. The Paleo-Asian Ocean finally closed in the early Middle Triassic, and the impact of collisional orogeny may have continued until the early Late Triassic.