南极长城站地区卫星多普勒定位的数据处理及精度分析

本文论述了南极长城站地区卫星多普勒定位的数据处理工作。简要介绍定位的数学模型,并着重分析了南极地区卫星多普勒定位的结果。通过对预处理、仪器频漂、单点定位、联测定位、解的收敛状态以及广播星历误差等方面的分析,作者认为在南极地区利用卫星多普勒定位技术进行高精度大地测量或冰川运动监测等都是一种有效的定位手段。最后给出了一些有关数据与结论。     

用GPS监测城市地面沉降的可行性研究

研究了用GPS观测取代常规水准测量方法监测城市地面沉降变化的可行性。在宁波市进行了两期GPS测量和水准测量，观测中并采取一定的措施以获得高精度的高程分量。顾及到对流层延迟的影响，采用Saastamcinen模型改正对流层延迟的干分量部分，用分段线性方法来估计对流层的湿分量变化。用Bernese软件对数据进行处理，获得了毫米级的高程精度。实际算例证明，用GPS测量代替水准测量来监测城市地面沉降变化是可行的。     

Similar single-difference model and its algorithm for solving GPS monitoring deformation directly at single epoch

A new similar single-difference mathematical model (SS-DM) and its corresponding algorithm are advanced to solve the deformation of monitoring point directly in single epoch. The method for building the SSDM is introduced in detail, and the main error sources affecting the accuracy of deformation measurement are analyzed briefly, and the basic algorithm and steps of solving the deformation are discussed.     

中国农户可持续生计研究进展及趋向

开展农户可持续生计研究,对于解决农村贫困问题,促进农村社会经济可持续发展具有重要意义。在查阅大量相关文献的基础上,本文首先阐述了可持续生计的概念,并对国外农户可持续生计研究概况进行了简介;然后从生计资产(资本)研究、生计脆弱性分析、生计策略研究、政策、机构和过程对农户生计影响研究、农户生计与生态环境的相互关系研究等5 个方面对近年来国内农户生计的主要研究进展进行了归纳总结。最后,提出了中国农户可持续生计研究的主要趋向:跨学科综合性、系统性研究,新技术方法的综合与动态研究,农户可持续生计与贫困问题研究,城乡转型期农户可持续生计研究,重点区域的农户可持续生计研究。     

Predicting Global Seafloor Topography Using Multi-Source Data

A new one-minute global seafloor topography model was derived from vertical gravity gradient anomalies (VGG), altimetric gravity anomalies, and ship soundings. Ship soundings are used to constrain seafloor topography at wavelengths longer than 200 km and to calibrate the topography to VGG (or gravity) ratios at short wavelengths area by area. VGG ratios are used to predict seafloor topography for wavelength bands of 100–200 km and to suppress the effect of crust isostasy. Gravity anomalies are used to recover seafloor topography at wavelengths shorter than 100 km. The data processing procedure is described in detail in this paper. The accuracy of the model is evaluated using ship soundings and existing models, including General Bathymetric Charts of the Oceans (GEBCO), DTU10, ETOPO1, and SIO V15.1. The results show that, in the discussed regions, the accuracy of the model is better than ETOPO1, GEBCO, and DTU10. Additionally, the model is comparable with V15.1, which is generally believed to have the highest accuracy. In the north-central Pacific Ocean, the accuracy of the model increased by approximately 29.5% compared with the V15.1 model. This indicates that a more accurate seafloor topography model can be formed by combining gravity anomalies, VGG, and ship soundings.     

贺兰山三叠纪盆地构造属性再分析

摘要：对贺兰山北段三叠系构造背景的理解具有重要的理论和实践意义,本文通过对该地区周边同期构造事件的分析,结合最近的研究成果,认为贺兰山北部三叠纪沉积的构造背景类似于新生代早、中期莺歌海拉分盆地形成的环境。晚三叠世－早侏罗世由于巴彦乌拉山－狼山韧性剪切带的左行走滑,致使巴彦乌拉山崛起,它类似于目前的红河－哀牢山剪切带中的哀牢山,而在贺兰山北部由于该断层的左行走滑形成了走滑拉分盆地,堆积了巨厚的上三叠统延长组和侏罗系碎屑岩。虽然在三叠纪地理上贺兰山地区与鄂尔多斯盆地可能相连,但两者的沉降机制并不相同,它们的关系可能类似与目前的莺歌海盆地与南海盆地的关系。在晚侏罗世,该地区的拉分盆地由于受到阿拉善地块的东向挤压而反转。造成巴彦乌拉山－狼山韧性剪切带左行活动的原因是晚三叠世－早侏罗世鄂尔多斯盆地相对于阿拉善地块的左行压扭运动,其动力则可能来自中朝板块与扬子板块的碰撞。该模型不仅可以解释贺兰山北段三叠纪区别于鄂尔多斯盆地本部的强烈伸展,还能解释该地区分布局限的板内拉斑玄武岩的原因,而且也能够将晚三叠世巴彦乌拉山的隆起与该地区同时期的沉积以及阿拉善地块南缘的变形联系起来,而从区域上也可以解释同时期南蒙古地区的发育的左行走滑构造及其相关沉积。     

Interaction between risk perception and sense of place in disaster-prone mountain areas: a case study in China’s Three Gorges Reservoir Area

Residents of rural mountain settlements are constantly threatened by disasters such as landslides. Their risk perception directly or indirectly affects their behavioral choices. Introducing the concept of sense of place, this paper details its interactions with the risk perception of mountain hazards. Rural residents (n = 348) in landslide-threatened areas of the Three Gorges Reservoir Area were questioned about their sense of place and risk perception. Partial least squares structural equation modeling was used to explore the interactions between various dimensions, and hypothetical tests were conducted. We found that dimensions of risk perception, such as Possibility and Unknown, had direct, negative impacts on the dimensions of sense of place, such as Society bond and Place dependence. Possibility had an indirect, yet more significant effect on Place attachment and Place identity, acting through Society bond. Rural residents often overestimate disaster risks due to fatalism, and a fear of the unknown stemming from low scientific literacy, which reduces their Place dependence. A complex interaction between sense of place and risk perception was observed. The findings provide a scientific basis for the government to formulate integrated policies regarding settlement relocation, disaster prevention and mitigation, and sustainable development.     

藏北高原土壤的温湿特征

通过藏北高原两个站点(D110和安多)土壤温湿特性的分析,表明浅层土壤温度的变化幅度明显的比深层的要大,而且浅层土壤温度受地表随机天气过程的影响较大。浅层(20cm)土壤在未冻结前湿度的变化幅度不但受形成降水的地表随机天气过程的影响,而且受其下层土壤湿度状况的影响。下层土壤湿度越小,浅层(20cm)土壤湿度的变化幅度越大。土壤湿度和土壤温度之间存在着明显的相互关系,土壤的湿度状况能够影响土壤温度变化的幅度和土壤温度变化的趋势。     

地下地膜截水墙--一种新的节水农业技术

简要分析了西北黄土梯地和四川紫色土旱坡地土壤水侧向运移的特点,介绍了地下水地膜截水墙阻断土壤水分侧向支移,保持耕地土壤水分,抗旱增产的基本原理和建设技术。陕北米脂黄土梯田的试验结果表明,该技术可以有效地减少梯田梯坎蒸发,增产效益显著。     

能谱CT最佳单能量成像在胃底静脉曲张出血内镜术前的应用价值

目的:通过对肝门静脉、胃底静脉曲张及胃肾分流等的显示情况,评价能谱CT最佳单能量成像在胃底静脉曲张出血患者内镜术前的参考应用价值.方法:选取2016年9月至2021年1月期间收治的60例胃底静脉曲张出血患者,进行肝门静脉能谱CTA检查.比较最佳单能量、70 keV及混合能量(QC)3组图像肝门静脉CT值、图像噪声(IN...