土壤水分常数测定之我见   总被引：3，自引：0，他引：3  

黄中雄 《广西气象》2005,26(2):27-28,8

通过对土壤容重、田间持水量、凋萎湿度测定方法的研究，提出了土壤水分常数测定规范中存在和应注意的问题，以利做好当前的土壤水分常数测定工作。  相似文献   

Exploration for dimensional stone — implications and examples from the Precambrian of southern Finland     

O. Selonen  H. Luodes  C. Ehlers   《Engineering Geology》2000,56(3-4):275-291

Dimension stone is a natural rock that must fulfil high qualitative standards defined by both geology-based factors and non-geological factors. The stone itself (appearance/soundness) and the market demand are the two most important aspects in the quality assessment. The process of geological dimension stone exploration is a systematic and stepwise procedure, including individual steps of desk study, field mapping, detailed examination, geo-radar survey, and core drilling. The location of all economically feasible dimension stone deposits is strictly controlled by geological factors. Knowledge of these factors is fundamental in identifying new sites with potential for dimension stone. In this work the geological constraint on the occurrence of dimension stone in three areas, in the Precambrian of southern Finland, has been investigated. The deposits are localized to part of an area in which different geological features in combination have produced rock of good dimension stone quality. The study shows that, for example, vertical movements in the crust, magmatic evolution of an intrusion, and metamorphic grade define the location of rocks suitable for dimension stone.  相似文献   

液相色谱法测定城市自来水中的苯并(a)芘   总被引：5，自引：0，他引：5       下载免费PDF全文

曲仪 《气象与环境学报》2006,22(6):43-45

针对目前测定生活饮用水中的苯并(a)芘(简称Bap),采用的是国家标准《生活饮用水标准检验法》GB5750-85中的纸层析—荧光分光光度法,其准确度、精密度很难令人满意,提出了使用高效液相色谱法来定量检测城市自来水中的Bap。实验结果表明:该方法快速、准确,具有优异的重现性,线性范围为4.0～30.0 ng/L,线性系数为0.9999。日内(5 h)、日间(5 d)精密度均小于4.0%(n=5),Bap的回收率为89.0%～93.4%。由于Bap见光极容易分解,影响测定结果,因此采样后应尽快分析。  相似文献   

Hydrodynamic evolutions at the Yangtze Estuary from 1998 to 2009     

《Applied Ocean Research》2014

Over the past decade, the Yangtze Estuary has witnessed an unprecedented scale of human interventions and modifications through extensively varied resource utilizations. During the processes, mankind has obtained various resources and benefits via the “golden waterway”, such as navigation channel, harbor, shipping industry, shoreline, reclaimed land, freshwater and fishery resource. At the same time, the estuary and coast have also experienced a series of gradual changes in characteristics, such as sedimentation, erosion, sand hungry, water pollution, intertidal area loss, self-purification capacity decrease, and biological reduction. With the help of measurement data and numerical modeling, this study analyzed the response and feedback mechanisms between hydrodynamic evolutions and morphological processes in the Yangtze Estuary from 1998 to 2009. The results of this study indicate the following. (i) The water level along the main outlet of the Yangtze Estuary increased from 1998 to 2009. This increase was induced by the variation of the whole river regime (including natural geomorphodynamic process and local topography feedbacks from extreme metrological events and human activities). (ii) The decrease of the flow partition ratio at the 3rd bifurcation is directly induced by the Deepwater Navigational Channel (DNC) project and the corresponding morphological changes in the North Passage. (iii) The estuarine environmental gradients (salinity and suspended sediment concentration) were compressed, and the fresh-salt gradient became steeper. This has the indirect effect of backfilling in the waterway, i.e., strengthening the stratification effect near the ETM area and enhancing the tendency of up-estuary sediment transport. The results of this study give insights into explaining other phenomena such as deposition in the middle reach of the DNC, bathymetry evolutions, variations in vertical velocity and sediment concentration profiles, waterway backfilling and delta reclamation.  相似文献   

机载POS系统中惯性测量单元精度检校方法     

曲直  卢秀山  左建章  马东洋 《测绘科学》2011,36(5):131-133,97

本文简要介绍了GPS/INS组合技术的优势和特点,分析了惯性测量单元(IMU)的工作原理及精度影响因素,系统阐述了机载POS系统中IMU的检校方法和精度评定方法,包括初始对准重复性检测、跟踪姿态角精度的标定和静态漂移检测等,并利用双轴数控转台,对3台不同类型的国产POS系统进行了数据采集、处理和对比分析,实验初步表明,...  相似文献   

西藏四江流域生态环境遥感解译标志的建立及应用     

管磊  杨晏立  彭培好  马飞  陈文德 《地理空间信息》2011,9(2):103-105

在充分掌握四江流域自然地理特征的基础之上,通过对四江流域地区的TM影像和相关资料的对比,采用事先建立好的分类系统建立了12个生态环境类型的解译标志并提取了相关信息,为在四江流域及藏东南地区的生态环境或土地资源遥感调查提供依据。  相似文献   

精密三角高程测量在公路测量中的应用     

昝峰 《测绘与空间地理信息》2011,34(1):186-187,191

近几年,西部公路建设快速发展,但公路常规水准测量工作量大、进度慢等问题,严重影响公路建设效率.对精密三角高程测量的数学模型进行分析,并通过实际工程来论述它在公路测量中的应用和注意的问题.  相似文献   

土氡测量在广从断裂探测中的初步应用     

李洪艺  张澄博  陈国能  彭卓伦  张永定 《华南地震》2011,31(2):61-70

在广从断裂带共布置5条氡气测量剖面,利用FD-3017RaA和CDI-2000两种氡探测仪快速测定其浓度,得到土氡含量曲线图和等值线图,并分析氡异常曲线的特征,得到如下结论:广从断裂上土壤氡具有明显的峰值异常特征,通过异常峰值位置能很好地圈定断裂或隐伏断裂的位置和断裂带的宽度;利用峰值异常的几何形态能很好地判断断层的倾...  相似文献   

台风“温比亚”影响山东期间GPM资料的降水分析          下载免费PDF全文

李芳  李南  万瑜 《山东气象》2020,40(4):69-76

为研究GPM（Global Precipitation Measurement）资料对台风雨带降水结构的探测能力,利用GPM卫星资料、地基雷达资料和地面降水实况对2018 年第18号台风“温比亚”影响山东期间的降水结构进行分析。结果表明：台风螺旋雨带造成的降水远大于台风外围云系产生的降水;台风螺旋雨带的雨顶高度大于外围云系的雨顶高度,基本在7 km以上,最大雨顶高度达到15 km;台风螺旋雨带及其外围云系都以层云和对流云降水为主,其中螺旋雨带中对流云降水所占比例高于外围云系,对流云的平均降水率是层云的3倍左右,对流云降水对应近地面降水率和雨顶高度的大值区;台风螺旋雨带的降水柱与外围云系中的降水柱相比,具有数量多、密度大、高度高的特点,这与台风螺旋雨带中对流发展旺盛有关;2A DPR数据产品对降水估测具有较好的指示意义。研究结果为用GPM产品估测降水结构提供了参考依据。  相似文献   

Measuring the internal velocity of debris flows using impact pressure detecting in the flume experiment   总被引：2，自引：0，他引：2  

Sergey CHERNOMORETS 《山地科学学报》2011,8(2):109-116

Measuring the internal velocity of debris flows is very important for debris flow dynamics research and designing debris flow control works. However, there is no appropriate method for measuring the internal velocity because of the destructive power of debris flow process. In this paper, we address this problem by using the relationship between velocity and kinetic pressure, as described by surface velocity and surface kinetic pressure data. Kinetic pressure is the difference of impact pressure and static pressure. The former is detected by force sensors installed in the flow direction at the sampling section. Observations show that static pressure can be computed using the formula for static water pressure by simply substituting water density for debris flow density. We describe the relationship between surface velocity and surface kinetic pressure using data from seven laboratory flume experiments. It is consistent with the relationship for single phase flow, which is the measurement principle of the Pitot tube.  相似文献