确定先期固结压力的数学模型法

地基土的先期固结压力是判断土体应力历史的一个指标。在不同应力历史状况的土体变形分析中它也是一个重要的计算参数。因此,方便、准确地确定先期固结压力就显得尤为重要。依据理论研究和试验分析,提出了一种新的确定方法：数学模型法。润扬大桥土样试验的结果证明了此法的可行性。     

利用CFP技术解决复杂近地表问题综述

复杂近地表条件会降低地震数据的质量,通常采用基于地表一致性的时移静校正消除其影响.但静校正与速度是密不可分的,而确定复杂近地表速度是非常困难的.基于CFP技术处理复杂近地表问题时避免了对速度的直接操作,使得静校正和速度的确定相互独立.首先根据叠前数据估算出波场的传播算子,然后依据等时原理在DTS模板中进行算子更新,再用这些更新的算子重建基准面和实现近地表单程时间成像.获得正确的算子振幅也是重建基准面的关键.     

Hydrodynamical simulations of Galactic fountains – I. Evolution of single fountains

The ejection of the gas out of the disc in late-type galaxies is related to star formation and is due mainly to Type II supernovae. In this paper, we studied in detail the development of the Galactic fountains in order to understand their dynamical evolution and their influence on the redistribution of the freshly delivered metals over the disc. To this aim, we performed a number of 3D hydrodynamical radiative cooling simulations of the gas in the Milky Way where the whole Galaxy structure, the Galactic differential rotation and the supernova explosions generated by a single OB association are considered. A typical fountain powered by 100 Type II supernovae may eject material up to ∼2 kpc which than collapses back mostly in the form of dense, cold clouds and filaments. The majority of the gas lifted up by the fountains falls back on the disc remaining within a radial distance  Δ R = 0.5 kpc  from the place where the fountain originated. This localized circulation of disc gas does not influence the radial chemical gradients on large scale, as required by the chemical models of the Milky Way which reproduce the metallicity distribution without invoking large fluxes of metals. Simulations of multiple fountains fuelled by Type II supernovae of different OB associations will be presented in a companion paper.     

Radiation pressure — a stabilizing agent of dust clouds in comets?

The internal dynamics of an illuminated dust cloud of finite optical thickness is investigated. The dependence of the radiation pressure on the optical depth makes the individual particles oscillate, in one dimension, around the accelerated centre of gravity of the cloud. The cloud moves as an entity, irrespectively of the velocity dispersion of the particles and their efficiency for radiation pressure. If the optical depth does not change, i.e. if the cloud does not expand laterally, its lifetime is unlimited. A contraction caused by energy dissipation in mechanical collissions between the dust particles is expected. The range of particle sizes which can be transported by such a “coherent cloud” is estimated, as well as the acceleration of the whole cloud. The structure of the cloud in real space and in velocity space is investigated. A comparison with the “striae” observed in the dust tails of great comets shows that the parent clouds of these striae may have been of the kind considered.     

The composition of nutrient fluxes from contrasting UK river basins

Accurate estimates of N and P loads were obtained for four contrasting UK river basins over a complete annual cycle. The fractionation of these loads into dissolved and particulate, and inorganic and organic components allowed a detailed examination of the nutrient load composition and of the factors influencing both the relative and absolute magnitude of these components. The particulate phosphorus (TPP) loads account for 26–75% of the annual total phosphorus (TP) transport and are predominantly inorganic. The inorganic (PIP) and organic (POP) fractions of the TPP loads represent 20–47% and 6–28% of the annual TP transport, respectively. In contrast, the particulate nitrogen loads (TPN) represent 8% or less of the annual total nitrogen (TN) loads and are predominately organic. For dissolved P transport, the dissolved inorganic fraction (DIP) is more important, representing 15–70% of the TP loads, whereas the dissolved organic fraction (DOP) represents only 3–9% of the TP loads. The TN loads are dominated by the dissolved component and more particularly the total oxidized fraction (TON), which is composed of nitrate and nitrite and represents 76–82% of the annual TN transport. The remaining dissolved N species, ammonium (NH₄-N) and organic N (DON) account for 0·3–1·2% and 13–16% of the annual TN transport, respectively. The TPN and TPP fluxes closely reflect the suspended sediment dynamics of the study basins, which are in turn controlled by basin size and morphology. The dissolved inorganic nutrient fluxes are influenced by point source inputs to the study basins, especially for P, although the TON flux is primarily influenced by diffuse source contributions and the hydrological connectivity between the river and its catchment area. The dissolved organic fractions are closely related to the dissolved organic carbon (DOC) dynamics, which are in turn influenced by land use and basin size. The magnitude of the NH₄-N fraction was dependent on the proximity of the monitoring station to point source discharges, because of rapid nitrification within the water column. However, during storm events, desorption from suspended sediment may be temporarily important. Both the magnitude and relative contribution of the different nutrient fractions exhibit significant seasonal variability in response to the hydrological regime, sediment mobilization, the degree of dilution of point source inputs and biological processes. © 1998 John Wiley & Sons, Ltd.     

一种基于Hough变换的对极几何稳健估计算法

从基本矩阵的性质和作用出发,首先从理论上证明了如果在一条2维直线上有多于给定的3个以上的匹配点,多余的点将被视为冗余点不能用作匹配点;然后针对该问题引入了Hough变换算法,在建立匹配点对应关系的同时剔除冗余的共线点。实验表明,用改进后的算法估计出的基本矩阵在平均余差和对极距离上都小于改进前的算法,提高了基本矩阵的估计精度和稳定性。     

基层土地登记档案管理实践及开发利用

土地登记档案在基层土地管理活动中发挥着重要作用,是地籍档案中的重中之重。做好土地登记档案的规范化管理及有效开发利用,是档案管理工作的基础,也是国土资源管理工作的基础。工作中需制订合理的土地登记档案归档制度、规范档案管理工作流程,并积极开展档案的公开查询、做好档案宣传、汇编等工作。     

Shortwave cloud radiative forcing on major stratus cloud regions in AMIP-type simulations of CMIP3 and CMIP5 models

Cloud and its radiative effects are major sources of uncertainty that lead to simulation discrepancies in climate models. In this study, shortwave cloud radiative forcing (SWCF) over major stratus regions is evaluated for Atmospheric Models Intercomparison Project (AMIP)-type simulations of models involved in the third and fifth phases of the Coupled Models Intercomparison Project (CMIP3 and CMIP5). Over stratus regions, large deviations in both climatological mean and seasonal cycle of SWCF are found among the models. An ambient field sorted by dynamic (vertical motion) and thermodynamic (inversion strength or stability) regimes is constructed and used to measure the response of SWCF to large-scale controls. In marine boundary layer regions, despite both CMIP3 and CMIP5 models being able to capture well the center and range of occurrence frequency for the ambient field, most of the models fail to simulate the dependence of SWCF on boundary layer inversion and the insensitivity of SWCF to vertical motion. For eastern China, there are large differences even in the simulated ambient fields. Moreover, almost no model can reproduce intense SWCF in rising motion and high stability regimes. It is also found that models with a finer grid resolution have no evident superiority than their lower resolution versions. The uncertainties relating to SWCF in state-of-the-art models may limit their performance in IPCC experiments.     

应用地震资料设计水平井轨迹

应用三维地震资料设计水平井的轨迹,用人工合成记录标定层位和岩性并进行精细的构造解释和储层横向预测,对测区速度场进行研究,利用Geoquest 人机联作解释系统编绘层拉平图、转弯测线剖面图,不整合面构造图,各套油层顶面构造图,沿地层倾向设计水平井的轨迹.经两口井钻探,钻遇不整合面的误差0.19%—0.39%,一口井平均钻遇油层204m,相当9口直井的效益.用地震资料设计巷道水平井的关键是油层标定、深度标定和确定油层走向,用人机联作系统绘制水平切片图、反射波振幅图、油层顶构造图,设计了在油层内钻探的巷道井.经钻探,钻遇不整合面的误差0.07%,在真厚度8.23m 的油层内钻进563m.