基于MapObjects2、NetEngine利用VB实现最短路径分析     

迟文学 《华东地质学院学报》2005,28(3):282-285

最短路径分析是交通网络分析系统的一个基本问题,在理论上得到了广泛深入地研究.本文研究的目的是将理论分析应用于实践,主要利用NetEngine的网络分析功能来实现最短路径的分析,并在电子地图上显示路径.在开发首都国际机场应急救援与辅助决策系统的过程中,基于MapObjects2,NetEngine,利用Visual Basic来实现任意两点间最短路径分析功能,为首都机场的应急救援决策支持工作提供了最短路径信息,实践表明该方法简单、实用.  相似文献   

基于涡度相关技术估算植被/大气间净CO2交换量中的不确定性   总被引：7，自引：0，他引：7  

温学发  于贵瑞  孙晓敏 《地球科学进展》2004,19(4):658-663

近年来，涡度相关技术的进步使陆地生态系统CO2通量的长期和连续观测成为可能。目前，涡度相关技术是全球通量观测网络（FLUXNET）测定植被/大气间CO2通量的主要技术手段，但绝大部分CO2通量观测站点都处于非典型的理想条件下，不能完全满足涡度相关技术的基本假设条件，从而导致基于涡度相关技术估算植被/大气间净生态系统CO2交换量的不确定性。系统介绍了涡度相关技术的基本假设，基本理论公式和误差的类型与特征等理论问题，重点阐述了通量测定中仪器本身的物理限制、二维和三维的气流运动、数据处理的方法和夜间通量的低估等不确定性的主要来源，并据此对通量观测研究中需要优先考虑的问题提出一些建议。研究认为数据质量控制与分析以及误差评价是不同通量站点间的结果比较和全球尺度综合分析的过程中需重点考虑的问题。  相似文献   

中国震例数据库及其应用系统设计     

严蔼芬  张肇诚 《中国地震》1995,11(3):293-298

本文简单介绍了中国震例数据库及其应用系统的软件设计。该系统是用网状数据库管理系统ＶＡＸＤＢＭＳ的实现的，目前数据库内存入１９９６年后我国大陆５级以上地震６０个震例报告的详细资料，系统具有快速检索、统计计算及图形绘制等功能，是震例分析及有关研究的有关手段，该系统于１９９１年１２月通过专家鉴定。  相似文献   

ADVANCES IN SECOND-ORDER CALIBRATION     

ODDS.BORGEN  BRUCER.KOWALSKI  FRANTSEK TURECEK 《地理学报(英文版)》1993,(2)

Several multivariate methods are now available for the calibration of second-order or hyphenatedinstruments(e.g.GC/MS).When applied to bilinear data,it has been shown that calibration can beperformed in the presence of unknown interferences-a significant advantage over first-order calibration.In this paper,non-bilinear rank annihilation(NBRA),a method which has the potential of handling,second-order non-bi-linear data,is studied through theoretical analysis and computer simulation.It isfound that the second-order advantage can be carried over to non-bilinear data if a property defined asnet analyte rank(NAR)holds for the analyte of interest.The net analyte signal(NAS)is definedaccordingly for second-order calibration and the analogy to and difference from lower-order calibrationare discussed.With NAS,some analytical figures of merit such as signal-to noise ratio,selectivity,sensitivity and limit of determination can be calculated for second order calibration.An application toMS/MS data is also given.  相似文献   

On the relationship between the eddy covariance,the turbulent flux,and surface exchange for a trace gas such as CO<Subscript>2</Subscript>     

Andrew S. Kowalski  Penélope Serrano-Ortiz 《Boundary-Layer Meteorology》2007,124(2):129-141

In the context of CO₂ surface exchange estimation, an analysis combining the basic principles of diffusion and scalar conservation shows that the mixing ratio is the appropriate variable both for defining the (eddy covariance) turbulent flux and also for expressing the relationship between the turbulent flux and surface exchange in boundary-layer budget equations. Other scalar intensity variables sometimes chosen, both the CO₂ density and molar fraction, are susceptible to the influence of surface exchange of heat and water vapour. The application of a hypsometric analysis to the boundary-layer “control volume” below the tower measurement height reveals flaws in previously applied approaches: (a) incompressibility cannot be assumed to simplify mass conservation (the budget in terms of CO₂ density); (b) compressibility alone makes the analysis of mass conservation vulnerable to uncertainties associated with resultant non-zero vertical velocities too small to measure or model over real terrain; and (c) the WPL (Webb et al. (1980) Quart J Roy Meteorol Soc 106:85–100) “zero dry air flux” assumption is invalidated except at the surface boundary. Nevertheless, the definition and removal of the WPL terms do not hinge upon this last assumption, and so the turbulent CO₂ flux can be accurately determined by eddy covariance using gas analysers of either open- or closed-path design. An appendix discusses the necessary assumptions and appropriate interpretations for deriving the WPL terms.  相似文献   

GPS作业过程中的质量控制初探   总被引：1，自引：0，他引：1  

黄勇  王伟  刘卫国  唐枢 《北京测绘》2007,(3):50-53,42

从GPS作业过程的网形设计、外业观测和基线解算等方面简述了在GPS静态定位测量中影响质量的主要因素,并对网形设计、外业观测和基线解算进行了分析,详细分析了影响GPS基线解算结果的主要因素,给出了判别这些因素方法,并对如何消除这些因素的影响提出了相应的处理措施。  相似文献   

Physical processes that drive the seasonal evolution of the Southwestern Tropical Atlantic Warm Pool     

《Dynamics of Atmospheres and Oceans》2015

The thermodynamics of the seasonal evolution of the Southwestern Tropical Atlantic Warm Pool (hereafter SWTAWP), which is delimited by the 28 °C isotherm, is investigated using the Regional Ocean Modeling System (ROMS). Results indicate that the net heat flux is responsible for the appearance and extinction of the SWTAWP. From March to May, the SWTAWP attains its maximum development and sometimes merges with equatorial warm waters towards the African continent, whose development follows the same period. Along the equator, the combination of oceanic terms (i.e., advection and diffusion) is important to promote the separation – when it occurs – of equatorial warm waters from southwestern tropical waters, which develops off the Brazilian coast. An analysis of the relative contribution of the temperature tendency terms of the mixed layer (ML) heat budget over the appearance, development and extinction of the SWTAWP is also done. The most important term for warming and cooling inside of the ML is the net heat flux at the sea surface. The ML is heated by the atmosphere between October and April, whereas the upper ocean cools down between May and September. The highest heat content values occur during the lower-temperature period (August to October), which is linked to the deepening of the ML during this time period. The horizontal advection along the equator is important, particularly at the eastern domain, which is influenced by the cold tongue. In this area, the vertical diffusive term is also significant; however, it presents values near zero outside the equator. These results contribute to a better understanding of the behavior of the heat budget within the tropical Atlantic, as previous studies over this region focused along the equator only.  相似文献   

呼伦贝尔市NPP时空变化及其对气候的响应     

曲学斌  窦华山  林聪  高绍鑫  王涵 《沙漠与绿洲气象(新疆气象)》2019,13(5):100-105

利用2000—2015年MOD17A3数据和气象站点资料,分析呼伦贝尔市NPP的时空变化特征及其对气候变化的响应情况。研究表明,呼伦贝尔市平均植被NPP为261.02 gC/(m~2·a),总体呈自西向东依次递增的分布格局。NPP的年际变化呈波动增长趋势,平均变化率为5.51gC/(m~2·a),线性增长达到显著的区域主要位于呼伦贝尔草原、大兴安岭南部林地和大兴安岭与松嫩平原过渡的耕地。16个气象站周边的NPP与各站年降水量均呈正相关,且除莫力达瓦达斡尔族自治旗(简称莫旗)外均通过了0.01水平的显著性检验,NPP与年平均气温均呈负相关,但除海拉尔区外均未通过显著性检验,NPP与日照时数正、负相关的台站同时存在。由此可知,降水是影响呼伦贝尔市NPP变化的主要因素。  相似文献   

Bargaining a net gain compensation agreement between a marine renewable energy developer and a marine protected area manager     

《Marine Policy》2015

When the development of marine renewable energy (MRE) is only possible inside already established marine protected areas (MPAs), and there is a risk of ecosystem loss, environmental or monetary compensation -being the last step in a hierarchy of mitigation measures- might be an option for working out a trade-off between energy production and nature protection. In this article, it is argued that for this type of siting situation, instead of the well-established strategy of no net loss, a net gain should be provided from the MRE developer to the MPA manager, which acts as an incentive for the manager to cooperate and covers future potentially lost conservation benefits due to MRE potential damages. Based on this argument, a hypothetical example is used to demonstrate that a net gain is ensured only when there is a societal surplus from a combined MRE-MPA arrangement that can be divided between the players through bargaining. However, when asymmetric information is involved, it is shown that cooperative solution concepts are more sufficient for leaving both players better off after coexistence than before.  相似文献   

基于ObjectARX.Net的Jig技术及其应用研究   总被引：2，自引：0，他引：2  

韦忠 《现代测绘》2010,33(3):45-47

论述了通过继承DrawJig类的所有方法、过程和事件,重载Sampler和WorldDraw函数,实现用户定制CAD互动命令的步骤和方法。详细介绍了动态坐标标注实例,通过DrawJig类控制拖动序列接受用户的选定坐标点,从而确定坐标标注各要素的标注位置,最后采用AddEntity函数向CAD数据库添加实体对象的方法实现了数字化成图软件中的动态标注功能。  相似文献