首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 578 毫秒
1.
研究应用地理信息系统构建广东省土壤资源信息系统的总体模式,建立了土壤资源信息系统的基本功能构成;探索了土壤资源空间信息与文献资料的Internet网络化这一土壤研究新领域,并实现了土壤资源空间信息Internet网络化.  相似文献   

2.
松嫩盆地资源环境信息系统空间数据库的设计与开发   总被引:6,自引:0,他引:6  
文章介绍了松嫩盆地资源环境信息系统空间数据库的设计思路,总体目标、构成及功能以及系统建立的关键技术。该系统的建立,使得对松嫩盆地资源开发管理和相关信息的查询、检索更方便,同时对松嫩盆地资源合理开发利用和管理决策提供了科学依据。  相似文献   

3.
丘陵红壤开发的水土资源保护及农业产业化经营模式   总被引:1,自引:1,他引:1  
以湖南省桃源县为例,针对目前丘陵红壤开发存在的主要问题,在探明季节性干旱成因和发生规律、水资源合理调蓄利用依据的基础上,提出了红壤丘陵区抗御季节性干旱的水分管理对策和主要措施;通过不同经营模式的水土资源动态观测、分析,提出了红壤丘陵区土壤允许流失值应≤200 t·km-2·a-1、相应的降水径流系数<0.25 等水土资源协调发展的关键技术指标,并在丘陵红壤坡地上建立了土壤侵蚀模数<100 t·km-2·a-1 的“土壤-水分-生物”资源互利型的高效利用模式。同时,以市场为导向,优化产业结构为中心,应用上述研究成果,建立了茶叶、苎麻、果业、庭园高效生态农业等四大科技先导型的产业化规模经营体系,为我国红壤丘陵区的农业产业化开发提供实用模式与示范样板。  相似文献   

4.
依据田间实测资料,在分析丘陵赤红壤水分性质的基础上,建立了土壤有效含水量与土壤物理粘粒含量之间的数学模型、土壤水分特征曲线数学模型、土壤月均贮水量与月降雨总量之间的数学模型和径流率与土壤表层初始含水量之间的数学模型,研究了土壤水分循环与平衡数学模型及各分量与参数的确定方法.  相似文献   

5.
简要介绍了土地定级信息系统和土地估价信息系统的软件和硬件配置、系统的结构与功能,并以通州市为例,阐述了土地定级信息系统的基本算法和模型参数的确定方法。  相似文献   

6.
简要介绍了土地定级信息系统和土地估价信息系统的软件和硬件配置、系统的结构与功能,并以通州市为例,阐述了土地定级信息系统的基本算法和模型参数的确定方法。  相似文献   

7.
应用大量的调查和试验数据,论述了红壤区耕地有机物质资源的种类、数量及分布状况;分析了目前有机物质利用的现状及存在问题;探讨了开发有机肥料资源的对策。  相似文献   

8.
李忠武  曾光明  张华  杨斌  焦胜 《生态环境》2004,13(3):358-361
遥感和地理信息系统技术的发展为研究区域生态环境变化提供了有效的手段。针对红壤丘陵区这一特定区域,在地理信息系统的支持下,建立了红壤丘陵区环境信息系统数据库;同时结合特尔斐法、层次分析法及环境质量综合指数法,对红壤丘陵区的典型区域——长沙市的生态环境质量进行综合评价。研究结果表明,由于人类活动的强烈影响,长沙市环境质量状况良好以上级别的区域面积仅有827.64km^2,占总面积的7.0%;而生态环境较差的区域其面积达到6187.14km^2,占总面积的52.4%,这说明长沙市总体生态环境质量有待进一步提高。  相似文献   

9.
根据红壤丘陵区土地利用的特点,研究有机物料良性循环利用,建立温柑—平菇—蚯蚓立体生态模式。通过分析系统的经济效益和生态功能,表明各环节是互利互补、互相促进的良性循环。在红壤丘陵区这一模式具有较高的实用价值。  相似文献   

10.
以江苏省溧阳市同官片流域为例,通过建立小流域管理与规划信息系统,探求流域治理新模式,以促进流域经济的良性发展。简要介绍了基于小流域的系统设计和建立方法,系统的功能及其应用实例。  相似文献   

11.
● Advances, challenges, and opportunities for catalytic water pollutant reduction. ● Cases of Pd-based catalysts for nitrate, chlorate, and perchlorate reduction. ● New functionalities developed by screening and design of catalytic metal sites. ● Facile catalyst preparation approaches for convenient catalyst optimization. ● Rational design and non-decorative effort are essential for future work. In this paper, we discuss the previous advances, current challenges, and future opportunities for the research of catalytic reduction of water pollutants. We present five case studies on the development of palladium-based catalysts for nitrate, chlorate, and perchlorate reduction with hydrogen gas under ambient conditions. We emphasize the realization of new functionalities through the screening and design of catalytic metal sites, including (i) platinum group metal (PGM) nanoparticles, (ii) the secondary metals for improving the reaction rate and product selectivity of nitrate reduction, (iii) oxygen-atom-transfer metal oxides for chlorate and perchlorate reduction, and (iv) ligand-enhanced coordination complexes for substantial activity enhancement. We also highlight the facile catalyst preparation approach that brought significant convenience to catalyst optimization. Based on our own studies, we then discuss directions of the catalyst research effort that are not immediately necessary or desirable, including (1) systematic study on the downstream aspects of under-developed catalysts, (2) random integration with hot concepts without a clear rationale, and (3) excessive and decorative experiments. We further address some general concerns regarding using H2 and PGMs in the catalytic system. Finally, we recommend future catalyst development in both “fundamental” and “applied” aspects. The purpose of this perspective is to remove major misconceptions about reductive catalysis research and bring back significant innovations for both scientific advancements and engineering applications to benefit environmental protection.  相似文献   

12.
Rank-based sampling designs are powerful alternatives to simple random sampling (SRS) and often provide large improvements in the precision of estimators. In many environmental, ecological, agricultural, industrial and/or medical applications the interest lies in sampling designs that are cheaper than SRS and provide comparable estimates. In this paper, we propose a new variation of ranked set sampling (RSS) for estimating the population mean based on the random selection technique to measure a smaller number of observations than RSS design. We study the properties of the population mean estimator using the proposed design and provide conditions under which the mean estimator performs better than SRS and some existing rank-based sampling designs. Theoretical results are augmented with some numerical studies and a real-life example, where we also study the performance of our proposed design under perfect and imperfect ranking situations.  相似文献   

13.
以跨界融合子基因工程菌处理高浓度有机废水为研究对象,建立了处理系统投资最小化数学模型及相应的约束方程,探讨该处理系统的优化设计问题。研究中以进水BOD浓度S0、微生物浓度X和回流比R为初始控制变量,通过对跨界融合子降解豆制品废水实例验证,表明在给定的初始变量范围内有惟一的最优解,为处理工艺的合理设计提供了依据。  相似文献   

14.
The literature dealing with the use of ozone in wastewater treatment is extensive, but its reported applications to aquaculture are limited. The major limiting factors appear to be ozone toxicity and the cost of high-output ozone generators. Ozone toxicity may be circumvented by system design, thereby leaving generating equipment as the major obstacle. A small, high-output ozone generator, therefore, was designed utilizing the efficient Lowther plate-type principle. The unit, employing stainless-steel wire-mesh electrodes and mica dielectrics, may be used with air, oxygen, or oxygen-enriched air. Ozone production from air was evaluated at 0.125, 0.25 and 0.5 cfm (3.54, 7.08 and 14.2 l/min) and oxygen at 0.25 cfm (7.08 l/min). Maximum output from air (0.25 cfm; 2.95 kV) was 84.1 g/h. Oxygen under identical conditions resulted in a production rate of 142.7 g/h. The application of this new ozone-generator design is recommended for water treatment in both open-and closed-water systems.Contribution No. 343, Department of Biology.  相似文献   

15.
土壤石油污染物生物通风修复的研究进展   总被引:3,自引:0,他引:3  
隋红  茹旭  黄国强  李鑫钢 《生态环境》2003,12(2):216-219
生物通风是一种去污效果好、操作费用低的土壤原位修复技术。文章概述了生物通风系统的结构、设计目的、适用范围和优缺点,详细论述了生物通风的国内外研究现状,包括现场应用、影响因素和强化技术及理论研究,并展望了生物通风在我国的应用前景。  相似文献   

16.
《Ecological modelling》2003,169(1):73-87
Robust prediction models for the spatial distribution of grassland vegetation, molluscs and carabids in a study area at the Middle Elbe (Germany) had to be generated by means of multivariate statistical methods. An appropriate study design has been developed. Data of all three taxons as well as numerous parameters of the abiotic environment were ascertained. Canonical correspondence analysis (CCA) detected clear dependencies between the occurrence of biotic objects and mainly hydrological parameters. By use of Arc/Info applications CANOGEN and CANORES, it was possible to extrapolate the models from the sample plots to the whole study area. The predicted spatial distribution of nearly all in the field studies examined species could be depicted with these instruments. Comparison between investigated and predicted distribution of species showed high correspondence.Robustness of the models was proved by interchanging model parameters for different study years and also in applying models at a second study area located 40 km upstream of the original study area.As a second method for further investigation, logistic regression was used to build generalised linear models (GLM) for potential indicator species in the study area.  相似文献   

17.
天津市医疗垃圾管理信息系统设计研究   总被引:3,自引:0,他引:3  
从用户需求分析、数据库结构设计、系统功能设计和用户界面设计四个方面 ,比较详细的介绍了天津市医疗垃圾管理信息系统 (MWMIS)的设计思想与设计方法及其主要功能特点。  相似文献   

18.
State-and-transition models (STMs) can represent many different types of landscape change, from simple gradient-driven transitions to complex, (pseudo-) random patterns. While previous applications of STMs have focused on individual states and transitions, this study addresses broader-scale modes of spatial change based on the entire network of states and transitions. STMs are treated as mathematical graphs, and several metrics from algebraic graph theory are applied—spectral radius, algebraic connectivity, and the S-metric. These indicate, respectively, the amplification of environmental change by state transitions, the relative rate of propagation of state changes through the landscape, and the degree of system structural constraints on the spatial propagation of state transitions. The analysis is illustrated by application to the Gualalupe/San Antonio River delta, Texas, with soil types as representations of system states. Concepts of change in deltaic environments are typically based on successional patterns in response to forcings such as sea level change or river inflows. However, results indicate more complex modes of change associated with amplification of changes in system states, relatively rapid spatial propagation of state transitions, and some structural constraints within the system. The implications are that complex, spatially variable state transitions are likely, constrained by local (within-delta) environmental gradients and initial conditions. As in most applications, the STM used in this study is a representation of observed state transitions. While the usual predictive application of STMs is identification of local state changes associated with, e.g., management strategies, the methods presented here show how STMs can be used at a broader scale to identify landscape scale modes of spatial change.  相似文献   

19.
The Application of Neutral Landscape Models in Conservation Biology   总被引:14,自引:0,他引:14  
Neutral landscape models, derived from percolation theory in the field of landscape ecology, are grid-based maps in which complex habitat distributions are generated by random or fractal algorithms. This grid-based representation of landscape structure is compatible with the raster-based format of geographical information systems (GIS), which facilitates comparisons between theoretical and real landscapes. Neutral landscape models permit the identification of critical thresholds in connectivity, which can be used to predict when landscapes will become fragmented. The coupling of neutral landscape models with generalized population models, such as metapopulation theory, provides a null model for generating predictions about population dynamics in fragmented landscapes. Neutral landscape models can contribute to the following applications in conservation: (1) incorporation of complex spatial patterns in (meta)population models; (2) identification of species' perceptions of landscape structure; (3) determination of landscape connectivity; (4) evaluation of the consequences of habitat fragmentation for population subdivision; (5) identification of the domain of metapopulation dynamics; (6) prediction of the occurrence of extinction thresholds; ( 7) determination of the genetic consequences of habitat fragmentation; and (8) reserve design and ecosystem management. This generalized, spatially explicit framework bridges the gap between spatially implicit, patch-based models and spatially realistic GIS applications which are usually parameterized for a single species in a specific landscape. Development of a generalized, spatially explicit framework is essential in conservation biology because we will not be able to develop individual models for every species of management concern.  相似文献   

20.
针对我国农村地籍管理的现状 ,探讨了建立农村地籍管理信息系统的必要性。以江苏省农村地籍管理信息系统软件的开发为例 ,详细阐述了系统的框架结构、数据库建设、功能构成和系统特色 ,探讨了系统的应用前景。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号