Development of the universal and simplified soil model coupling heat and water transport

It is very important to develop a universal soil model with higher simplicity and more accuracy, which can be widely applied to very general cases such as wet or dry soil, frozen or unfrozen soil and homogeneous or heterogeneous soil. Firstly in this study, based on analysis of both magnitude order and the numerical simulation results, the universal and simplified soil model (USSM) coupling heat and mass transport processes is developed. Secondly, in order to avoid the greater uncertainty caused by the phase change term in numerical iteration process for the model solution obtaining, new version of the universal simplified soil model (NUSSM) is further derived through variables transformation, and accordingly a more efficient numerical scheme for the new version is designed well. The simulation results from the NUSSM agree with the results from more complicated and accurate soil model very well, also reasonably reproduce the observed data under widely real conditions. The new version model, because of its simplicity, will match for the development of land surface model.     

Ephemrides of visual binaries in universal variables

In this paper, universal formulations of the two‐body problem are established for ephemerides of visual binary systems, whatever the type of their orbits may be. A computational algorithm is also given and applied to the binaries ADS 9159, ADS 2959 and ADS 11632 as typical examples of elliptic, parabolic and hyperbolic binaries, respectively.     

区域模式的嵌套边界条件研究

在对现今常用的几种嵌套边界条件进行对比研究的基础上，提出一种普遍边界条件，它可以在不同的假定转变成各种常用的嵌套侧边界条件。由此可清晰地分析对比各种常用嵌套边界条件作用时的优缺点以及应注意的问题。     

GPS平面控制网的模拟设计计算方法及其应用

基于全边角网和全边方位角网模拟法设计的计算思想和"科傻系统"中的控制网通用平差软件包,提出了一种GPS平面控制网的模拟设计计算方法,给出了该方法的计算步骤,并结合实例进行了计算分析。     

香港地区电离层垂向电子含量的变化规律

根据香港GPS永久跟踪站的长期GPS观测资料,估计出了香港地区电离层垂向电子含量,并分析了垂向电子含量的周日变化规律,对建立香港地区实用的电离层模型有重要的指导意义。     

主要是地区经验还是具有通用性——论土体原位测试的应用范围

土体原位测试在工程勘察中应用很广,但其应用范围主要是地区性的还是全国性的一直是个未解决的问题。作者认为,由于所测试的对象是土,同一时代、同一成因、同一类别的土在不同地区的工程性质是大同小异的,同一种测试方法的机理在不同地区的同类土中也是相同的;作者还根据大量的实际资料证明土体原位测试的应用具有通用性。作者建议,应进行大范围研究,提出更多适合全国乃至全世界的土体原位测试应用公式和图表,以扩大其应用广度和提高其应用精度。     

地质统计学方法在地下水水位估值中应用

对于许多区域水资源或水环境问题,地下水水流模拟往往要采用数值方法,需给出每个节点上初始水位值,以反映流场的初始状态。另外,地下水水位动态长期监测分析,需由观测点水位估计任一点的水位。文中阐述了地下水水位估值的地质统计学方法－泛克立格法原理,以河南省焦作市修武段地下水数值模拟分析区为例,分析了用一次、二次漂移的泛克立格方法模拟地下水初始流场的估值情况和对真实流场特征的反映情况。指出在进行区域地下水位     

The use of SfM-photogrammetry to quantify and understand gully degradation at the temporal scale of rainfall events: an example from the Ethiopian drylands

Abstract

With the recent technological advances offered by SfM-photogrammetry, we now have the possibility to study gully erosion at very high spatial and temporal scales from multi-temporal DEMs, and thus to enhance our understanding of both gully erosion processes and controls. Here, we examine gully degradation and aggradation at a gully headcut and at four re-incisions along a gully reach in Northern Ethiopia. Environmental controls recorded are topography rainfall, runoff, land use and cover, land management, and soil characteristics. The overall vulnerability of the catchment to erosion is low as calculated from the RUSLE (average 11.83 t ha^?1 y^?1). This reflects the successful land management of the past years. The runoff coefficient was on average 7.3% (maximum 18.2%). Runoff events caused most geomorphic change in the gully, but slumping of the gully bank also occurred on dry days. Most geomorphic change was caused by one major rainfall event of 54.8 mm d^?1, and smaller runoff events caused both degradation and aggradation, often asynchronous between studied sites. Although most research focuses on gully heads alone, re-incisions at lower locations can still cause important gully degradation, which ultimately will reach the gully head and cause instability.     

全面二孩政策对中国人口结构及区域人口空间格局的影响

从“单独二孩”到“全面二孩”,近几年中国生育政策的连续调整,不仅引起了社会的强烈反响,而且也将对中国未来的人口结构和空间格局产生重要影响。本文利用人口学的队列元素法对全面放开二孩政策实施后,中国未来总人口及人口结构的变化趋势进行预测,并从地理学的角度分析了全面放开二孩对中国区域人口空间格局的影响。结果表明：①全面放开二孩可以有效延缓中国总人口的递减趋势、老龄化的趋势以及未来劳动人口不断走低的趋势;②全面放开二孩政策前后,中国的区域人口空间分布均呈现东部人口密度最高、中部次之、东北再次、西部最低的总体格局,全面放开二孩将会增加胡焕庸线东南侧的人口密度,中国人口分布东南集聚、西北相对稀疏的格局将会长期存在并进一步加剧;③根据各省全面放开二孩政策后未来15年人口变化强度,可划分为人口快速变化区、人口中速变化区、人口缓慢变化区和人口平稳区。     

通用EIV平差模型及其加权整体最小二乘估计

以平差基本理论为基础,提出了EIV(errors-in-variables)平差模型的通用形式,涵盖了间接平差、条件平差、附有参数的条件平差及附有限制条件的间接平差等基本EIV模型形式。基于整体最小二乘估计准则,研究了通用EIV模型的加权整体最小二乘算法,并推导了估计结果的近似精度公式。通用EIV模型及其整体最小二乘算法是对EIV模型估计理论的进一步完善,统一的整体最小二乘算法有利于软件的编程实现,有助于推动EIV模型估计理论的应用。