关于"生态旅游"概念的探讨   总被引：6，自引：0，他引：6  

王家骏 《地理与地理信息科学》2002,18(1):103-106

该文选取国外44个生态旅游定义作为研究对象,通过确认关键词、对关键词进行聚类分析,将定义内容归纳为6大类11组分,进而构建生态旅游概念模型.在检验模型理论上的可靠性和实践上的适应性后,笔者依据模型提出生态旅游定义.  相似文献   

Atmospheric input of nitrogen into the North Sea: ANICE project overview     

Gerrit de Leeuw  Leo Cohen  Lise Marie Frohn  Gary Geernaert  Ole Hertel  Bjarne Jensen  Tim Jickells  Laura Klein  Gerard J. Kunz  Soren Lund  Marcel Moerman  Frank Müller  Britta Pedersen  Knut von Salzen  K. Heinke Schlünzen  Michael Schulz  Carsten A. Skjth  Lise-Lotte Sorensen  Lucinda Spokes  Susanne Tamm  Elisabetta Vignati 《Continental Shelf Research》2001,21(18-19)

The aim of the atmospheric nitrogen inputs into the coastal ecosystem (ANICE) project is to improve transport–chemistry models that estimate nitrogen deposition to the sea. To achieve this, experimental and modelling work is being conducted which aims to improve understanding of the processes involved in the chemical transformation, transport and deposition of atmospheric nitrogen compounds. Of particular emphasis within ANICE is the influence of coastal zone processes. Both short episodes with high deposition and chronic nitrogen inputs are considered in the project. The improved transport–chemistry models will be used to assess the atmospheric inputs of nitrogen compounds into the European regional seas (the North Sea is studied as a prototype) and evaluate the impact of various emission reduction strategies on the atmospheric nitrogen loads. Assessment of the impact of atmospheric nitrogen on coastal ecosystems will be based on comparisons of phytoplankton nitrogen requirements, other external nitrogen inputs to the ANICE area of interest and the direct nitrogen fluxes provided by ANICE. Selected results from both the experimental and modelling components are presented here. The experimental results show the large spatial and temporal variability in the concentrations of gaseous nitrogen compounds, and their influences on fluxes. Model calculations show the strong variation of both concentrations and gradients of nitric acid at fetches of up to 25 km. Aerosol concentrations also show high temporal variability and experimental evidence for the reaction between nitric acid and sea salt aerosol is provided by size-segregated aerosol composition measured at both sides of the North Sea. In several occasions throughout the experimental period, air mass back trajectory analysis showed connected flow between the two sampling sites (the Weybourne Atmospheric Observatory on the North Norfolk coast of the UK and Meetpost Noordwijk, a research tower at 9 km off the Dutch coast). Results from the METRAS/SEMA mesoscale chemistry transport model system for one of these cases are presented. Measurements of aerosol and rain chemical composition, using equipment mounted on a commercial ferry, show variations in composition across the North Sea. These measurements have been compared to results obtained with the transport–chemistry model ACDEP which calculates the atmospheric inputs into the whole North Sea area. Finally, the results will be made available for the assessment of the impact of atmospheric nitrogen on coastal ecosystems.  相似文献   

基于同步数据项组和碎分拓扑弧段时间标记的时态地理数据模型   总被引：1，自引：0，他引：1  

杜道生  舒红 《武汉大学学报(信息科学版)》1997,(2)

从地理数据模型的定义出发，阐述时间作为地理实体的基本特征及ＧＩＳ中地理时间的模拟方法，指出传统地理数据模型在地理环境变化快且应用强调细节变化分析的场合，表现出不变数据的冗余存储、局部变化信息提取困难及地理实体的时间特征表现不明显等缺陷。基于现实世界中存在诸多同步变化的细小单元这一规律，提出一种基于属性同步数据项组和空间碎分拓扑弧段时间标记的时态地理数据模型，它降低了存储冗余且较好地表现了时间特征  相似文献   

基于流形拓扑的三维空间实体形式化描述   总被引：1，自引：0，他引：1  

郭薇  陈军 《武汉大学学报(信息科学版)》1997,(3)

阐述了三维空间实体语义概念及空间实体之间拓扑性质形式化描述的意义，以组合及点集拓扑理论为基础，给出了基于ｋ－维伪流形的三维空间实体的语义定义。将单纯同调理论用于流形，通过单纯形和单纯复形间的几何构造关系，揭示出三维空间实体的拓扑性质并给出三维空间实体的形式化描述方法。  相似文献   

建立潮汐汊道P-A关系的沉积动力学方法   总被引：6，自引：0，他引：6  

贾建军  高抒 《海洋与湖沼》2005,36(3):268-276

在均衡状态下，潮汐汉道系统的纳潮量(P)与口门面积(A)之间存在着较稳定的关系，通常用幂函数形式来表达。计算P-A关系的传统O’Brien方法因其统计性质无法给出单一潮汐汉道的P-A关系。根据沉积动力学原理，每个潮汐汉道的P-A关系都受涨落潮历时、断面平均流速、口门形态、纳潮量、淡水径流量、沿岸毛输沙量和沉积物粒度等因素的控制，对上述因素的每一种组合，都有对应的均衡态P-A关系。作者在前人工作的基础上，尝试着建立了计算单一潮汐汊道P-A关系的沉积动力学方法，并以山东半岛月湖为算例对该方法的应用进行了讨论。结果表明，均衡态潮汐汉道的P-A关系的指数n稳定在1．15左右，而系统C的变化较大。  相似文献   

Levy trajectories of Peruvian purse-seiners as an indicator of the spatial distribution of anchovy (Engraulis ringens)     

Bertrand  Sophie; Burgos  Julian M.; Gerlotto  Francois; Atiquipa  Jaime 《ICES Journal of Marine Science》2005,62(3):477-482

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Relationship between mn nodule abundance and other geological factors in the northeastern pacific: Application of gis and probability method     

Youngtak Ko  Saro Lee  Jonguk Kim  Ki-Hyune Kim  Mee-Sook Jung 《Ocean Science Journal》2006,41(3):149-161

The aims of this study are 1) to construct a database using geostatistics and Geographic Information System (GIS), and 2) to derive the spatial relationships between manganese nodule abundance and other geological factors such as metal grade, slope, water depth, topography, and acoustic characteristics of the sub-bottom. Using GIS, it is possible to analyze a large amount of data efficiently, and to maximize the practical application, to increase specialization, and to enhance the accuracy of the analyses. The greater the copper and nickel grade, the higher the rating. The distribution pattern of nickel grade is similar to that of copper grade. The slopes are generally less than 3° except for seamounts and cliff areas. The rating shows no correlation with slope. The rating is highest for slopes between 2.5 and 3.5° in block N1 and between 4.0 and 4.5° in block N3. The topography is classified into five groups: seamount, hill crest, hill slant, hill base or plain, and seafloor basin or valley. The rating proves lowest for seamount and hill crest. Our results show that the rating increases with the water depth in the study area. Nodule abundance dose not show any significant relationship with the thickness of the upper transparent layer in the study area.  相似文献   

A modified profile method for determining the vertical fluxes of NO,NO2, ozone,and HNO3 in the atmospheric surface layer     

Gerhard Kramm  Hans Müller  David Fowler  Klaus D. Höfken  Franz X. Meixner  Eberhard Schaller 《Journal of Atmospheric Chemistry》1991,13(3):265-288

A modified profile method for determining the vertical deposition (or/and exhalation) fluxes of NO, NO₂, ozone, and HNO₃ in the atmospheric surface layer is presented. This method is based on the generally accepted micrometeorological ideas of the transfer of momentum, sensible heat and matter near the Earth's surface and the chemical reactions among these trace gases. The analysis (aerodynamic profile method) includes a detailed determination of the micrometeorological quantities (such as the friction velocity, the fluxes of sensible and latent heat, the roughness length and the zero plane displacement), and of the height-invariant fluxes of the composed chemically conservative trace gases with group concentrations c ₁=[NO]+[NO₂]+[HNO₃], c ₂=[NO₂]+[O₃]+3/2·[HNO₃], and c ₃=[NO]–[O₃]–1/2·[HNO₃]. The fluxes of the individual species are finally determined by the numerical solution of a system of coupled nonlinear ordinary differential equations for the concentrations of ozone and HNO₃ (decoding method). The parameterization of the fluxes is based on the flux-gradient relationships in the turbulent region of the atmospheric surface layer. The model requires only the vertical profile data of wind velocity, temperature and humidity and concentrations of NO, NO₂, ozone, and HNO₃.The method has been applied to vertical profile data obtained at Jülich (September 1984) and collected in the BIATEX joint field experiment LOVENOX (Halvergate, U.K., September 1989).  相似文献   

球面栅格空间中的Jordan曲线性质及其拓扑矛盾分析   总被引：2，自引：1，他引：2  

侯妙乐  赵学胜  陈军 《武汉大学学报(信息科学版)》2006,31(2):148-151

定义了球面栅格空间的拓扑元素，给出球面栅格空间中邻近、连通和空间目标的内部、边界和外部等空间目标的拓扑定义及形式化描述，讨论了Jordan曲线在球面栅格空间中的性质及由此引起的拓扑矛盾。  相似文献   

空间方向关系形式化描述模型研究   总被引：12，自引：1，他引：12  

闫浩文  郭仁忠 《测绘学报》2003,32(1):42-46

空间方向关系形式化描述模型是空间关系研究的难点和重点，目前尚无完善的模型出现，因此进行其模型的研究意义重大。首先论述运用平面目标Voronoi图描述方向关系在理论上的可行性；然后详细阐述基于Voronoi图的空间方向关系形式化描述模型建立；为了验证模型的正确性，给出几个典型的算例；最后指出模型的优、缺点。  相似文献