STUDY ON THE INTERACTION BETWEEN NDVI PROFILE AND THE GROWING STATUS OF CROPS   总被引：5，自引：1，他引：4  

JIANGDong WANGNai-bin YANGXIao-huan WANGJi-hua 《中国地理科学(英文版)》2003,13(1):62-65

Daily and ten-day Normalized Difference Vegetation Index(NDVI) of crops were retrieved from meteorological statellite NOAA AVHRR images ,The temporal variations of the NDVI were analyzed during the whole growing season,and thus the principle of the interaction between NDIV profile and the growing status of crops was discussed,As a case in point,the relationship between integral NDVI and winter wheat yield of Henan Province in 1999 had been analyzed.By putting integral NDVI values of 60 sample counties into the winter wheat yield-integral NDVI coordination,scattering map was plotted. It demonstrated that integral NDVI had a close relation with winter wheat yield.These relation could be described with linear,cubic polynomial ,and exponential regression,and the cubic polynomial regression was the best way,In general ,NDVI reflects growing status of green vegetation ,so crop monitoring and crop yield estimation could be realized by using remote sensing technique on the basis of time serial NDVI data together with agriculture calendars.  相似文献   

Correlations between heavy metals and organic carbon extracted by dry oxidation procedure in urban roadside soils   总被引：1，自引：0，他引：1  

Xue Song Wang 《Environmental Geology》2008,54(2):269-273

The organic fraction in soils has a significant influence on heavy metal transport. In this study, the organic carbon content was measured by dry oxidation procedure from 21 Xuzhou urban roadside soils to assess the relationships between the concentrations of heavy metals (Pb, Cu, Zn, and Cr) and the amount of organic carbon. The anthropogenic heavy metals (e.g. Pb, Cu, Zn) were strongly correlated with organic carbon (denoted by C_org−c) extracted by dry oxidation while natural heavy metal (e.g. Cr) showed no correlation to the C_org−c. The anthropogenic heavy metals were also strongly correlated with the amount of the total carbon. These results show that the anthropogenic heavy metals are mainly enriched in the organic matter in the Xuzhou urban roadside soils.  相似文献   

Water and power networks and urban fragmentation in Los Angeles: Rethinking assumed mechanisms     

Fionn MacKillop  Julie-Anne Boudreau 《Geoforum》2008,39(6):1833-1842

Los Angeles is often described as the epitome of urban fragmentation, a notion which in this context is frequently connected to, or even conflated with urban sprawl. At the same time, the city features integrated water and power networks which have been under public ownership for over 70 years. We thus have an apparent paradox in the context of the debate on ‘splintering urbanism’, between socio-spatial fragmentation and the integration of networks. In discussing the idea that deregulation of infrastructural networks exacerbates urban fragmentation, the authors use the case of Los Angeles in order to highlight the central role of private interests in management decisions concerning infrastructure networks. The authors carry out their analysis in an historical perspective, revealing that network integration and universal access can often serve private interests more than the public good. Urban fragmentation in Los Angeles, they conclude, is the result of a complex process of instrumentalisation of network development and management.  相似文献   

Water and sanitation in the Buenos Aires metropolitan region: Fragmented markets, splintering effects?     

Sarah Botton  Bernard de Gouvello 《Geoforum》2008,39(6):1859-1870

This paper discusses the provision of water and sanitation services and the related urban impacts in Buenos Aires circa 2005. The first part of the paper focuses on the metropolitan region (BAMR) which is larger than the area served by the Aguas Argentinas S.A. (AASA) concession (i.e. the capital and its conurbano). It highlights a form of institutional fragmentation that is reflected in the diverse management practices of the numerous service providers and results in differentiated levels of and access to services. The paper discusses the technical, economic and regulatory factors that have historically resulted in this institutional fragmentation. The second part of the article focuses on AASA’s water concession agreement. It demonstrates that, although the agreement had an in-built splintering logic, its implementation led to a more “integrated approach” based on the “reality on the ground”. On the whole, the conclusion regarding the application of the splintering urbanism concept to Buenos Aires is a mixed one and depends on the scale of observation. Although at regional level (BAMR), a form of “institutional fragmentation” would appear to be obvious, it is the result of a long and complex historical process and, while recent neo-liberal reforms in service provisions have “cemented” this fragmentation, they did not actually cause it. If we take the AASA service area in isolation, the trend in the decade following the contracting out of the service has been one of improved service provision and access—although this was not achieved through increased integration of the supply system. Finally, in the case of the Buenos Aires metropolitan region, the splintering urbanism thesis defended by Marvin and Graham needs to be nuanced in several significant ways.  相似文献   

Water and power in Santiago de Chile: Socio-spatial segregation through network integration     

Géraldine Pflieger  Sarah Matthieussent 《Geoforum》2008,39(6):1907-1921

The analysis of the history of the management and distribution of electricity, water and sanitation networks in Santiago de Chile throws light on a problem which is central to thinking on the relationship between urban services management and territorial splintering: what is the impact of urban policy, in particular housing policy and urban planning, on access to services and on the potential levels of social segregation and institutional splintering of metropolises?The Chilean example is eminently anchored in its political and institutional history. We shall see, for example, that the authoritarian urban policy of the military government, associated with early liberal reform, enabled the improvement of access to networks in every municipality of the Greater Santiago area. However, this success, leading to the integration by urban services of a large territory, does not signify that networks remained neutral as regards the process of spatial segregation. Inversely, we can defend the theory that the presence of an integrated service was a necessary condition and a reinforcing factor of the process of urban spread and residential segregation. This paradoxical argument is a result of the ambivalent liberal network and urban policies of the military government. Urban expansion was largely sustained by the development of integrated infrastructures and universal services. The processes of liberalising land and urban services were mutually sustaining and provided the necessary conditions for the birth of an extremely intense movement of urban sprawl and segregation between 1985 and 2000.  相似文献   

Exurbia from the bottom-up: Confronting empirical challenges to characterizing a complex system   总被引：2，自引：0，他引：2  

Daniel G. Brown  Derek T. Robinson  Li An  Moira Zellner  William Rand  Rick Riolo  Bobbi Low 《Geoforum》2008,39(2):805-818

We describe empirical results from a multi-disciplinary project that support modeling complex processes of land-use and land-cover change in exurban parts of Southeastern Michigan. Based on two different conceptual models, one describing the evolution of urban form as a consequence of residential preferences and the other describing land-cover changes in an exurban township as a consequence of residential preferences, local policies, and a diversity of development types, we describe a variety of empirical data collected to support the mechanisms that we encoded in computational agent-based models. We used multiple methods, including social surveys, remote sensing, and statistical analysis of spatial data, to collect data that could be used to validate the structure of our models, calibrate their specific parameters, and evaluate their output. The data were used to investigate this system in the context of several themes from complexity science, including have (a) macro-level patterns; (b) autonomous decision making entities (i.e., agents); (c) heterogeneity among those entities; (d) social and spatial interactions that operate across multiple scales and (e) nonlinear feedback mechanisms. The results point to the importance of collecting data on agents and their interactions when producing agent-based models, the general validity of our conceptual models, and some changes that we needed to make to these models following data analysis. The calibrated models have been and are being used to evaluate landscape dynamics and the effects of various policy interventions on urban land-cover patterns.  相似文献   

Urban consolidation and house prices: a case study of Melbourne 1990–2004     

Sun Sheng Han  Kevin O’Connor 《GeoJournal》2008,73(4):285-295

This paper explores the links between a strategic policy, urban consolidation, and house prices by examining the changes in the mix of housing and in house price for the period 1991–2004. We contend that urban consolidation could be seen as a source of additional supply, (which might be expected to be felt in lower prices and so contribute to a local policy objective) but also as a stimulus to demand (by developers who could bid up the price of lots where it was understood more housing could be built). Analyses were carried out at the metropolitan and sub-regional scales using correlation tests. The research finds very weak statistical connections, and concludes that this policy has not been associated with price changes.  相似文献   

南海北部主要经济鱼类体长与体重关系   总被引：7，自引：1，他引：7  

王雪辉  杜飞雁  邱永松 《台湾海峡》2006,25(2):262-266

文中根据1997～1999年和2001～2002年期间在南海北部底拖网调查的43种共33 389尾鱼的体长（叉长、肛长）和体重数据,应用统计分析方法对各鱼种体长与体重关系进行分析.结果表明,43种鱼分别隶属于4目16科25属,相关系数R^2的范围为0.764～0.993,相关系数R^2值相对较高,其中58%的R^2值超过0.95.幂指数b值范围为2.50～3.44,平均2.90.盒须图分析表明,50%的b值在2.79～3.01范围.经初步分析,43种主要经济鱼类中,有16种为等速生长、22种负的异速生长和5种正的异速生长.  相似文献   

中国对虾镰刀菌病的细胞病理研究   总被引：2，自引：0，他引：2  

吴友吕  陈波 《海洋学研究》1992,10(4):21-26

本文报导中国对虾养成期病原体茄类镰刀菌Fusarium solani(Mart)的细微结构及其引起宿主的细胞病理变化,以便为该病的正确诊断和有效防治提供依据。  相似文献   

Delaunay三角网增点生长构造法研究   总被引：5，自引：0，他引：5  

刘晓红  李树军  朱颖  黄文骞 《海洋测绘》2005,25(3):48-50

论述了一种由计算机自动生成Delaunay三角网的增点生长构造法。该方法属于不规则三角网的动态构网法，它借鉴了静态构网法中递归生长算法的部分思想，并利用Lawson提出的最大最小(MAX—MIN)角度法则对三角网进行即时的局部优化，从而达到了快速、有效地构建Delaunay三角网的目的。该方法对快速生成海底DEM数据，进行海底仿真具有重要的作用。  相似文献