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151.
152.
A new time-dependent model of chlorine chemistry in cold and warm TMC-1 and Orion clouds was constructed using results of recent laboratory and theoretical studies on the reaction of chlorine molecules. The chemistry of chlorine was found to be fairly simple in dense interstellar clouds. Only the species Cl and HCl have a significant fractional abundance. Our results for the HCl molecule are in agreement with those obtained from the observation and from theoretical values of Orion cloud.  相似文献   
153.
Through the PRODESDIGITAL Project, the National Institute for Space Research (INPE) has been mapping vegetal coverage in the Brazilian Legal Amazon using Landsat satellite images. INPE not only identifies deforested areas but also releases a daily map of burning areas. Burning is frequently used as the cheapest way to deforest, to clear areas for farming and to increase the soil’s fertility in a short period of time. In many instances, these fires get out of control and end up accidentally invading areas of forest exploited by the lumber industry, agricultural plantations and pastures. However, the deforestation and burning area maps alone are insufficient for monitoring and control on a regional scale. It is necessary to know in an analytical way how actions (deforestation and burnings) that characterize human occupation are occurring in a region. In this research, two methods are used that allow the inclusion of co-variation in the estimation of variables of interest: logistic regression, which is a statistical method that considers a categorical or discrete response variable and discrete and/or continuous co-variation; and fuzzy logic, which makes use of artificial intelligence methods to incorporate into computational models information based on the knowledge or experience of a specialist. In both methods, the response variable may be related to the probability of occurrence of the environmental variable under study.  相似文献   
154.
Fine-resolution population mapping using OpenStreetMap points-of-interest   总被引:1,自引:0,他引:1  
Data on population at building level is required for various purposes. However, to protect privacy, government population data is aggregated. Population estimates at finer scales can be obtained through areal interpolation, a process where data from a first spatial unit system is transferred to another system. Areal interpolation can be conducted with ancillary data that guide the redistribution of population. For population estimation at the building level, common ancillary data include three-dimensional data on buildings, obtained through costly processes such as LiDAR. Meanwhile, volunteered geographic information (VGI) is emerging as a new category of data and is already used for purposes related to urban management. The objective of this paper is to present an alternative approach for building level areal interpolation that uses VGI as ancillary data. The proposed method integrates existing interpolation techniques, i.e., multi-class dasymetric mapping and interpolation by surface volume integration; data on building footprints and points-of-interest (POIs) extracted from OpenStreetMap (OSM) are used to refine population estimates at building level. A case study was conducted for the city of Hamburg and the results were compared using different types of POIs. The results suggest that VGI can be used to accurately estimate population distribution, but that further research is needed to understand how POIs can reveal population distribution patterns.  相似文献   
155.
156.
Experiments on model and real soil blocks designed to assess the feasibility of using magnetic resonance imaging for three-dimensional mapping of the time-varying spatial distribution of water in structured soils are reported. The results show that, notwithstanding inherent problems in imaging natural soils with a significant iron content, experimental parameters can be identified which allow satisfactory images to be obtained. Magnetic resonance imaging may therefore provide important information on soil structure and water movement in dual porosity soils, with attendant benefits for the calibration of models of non-Darcian flow in such soils.  相似文献   
157.
Typical of Mediterranean countries, the Lebanese shoreline is well known for its littoral and offshore groundwater discharges, the so-called submarine springs. The tectonic framework of the terrain explains its interruption by dense geologic structures, i.e., fracturing, faulting, karstic routes, as well as acute dips of rock strata seaward. All of these structures serve as hydrologic agents transporting groundwater to the sea. The study aims to locate these groundwater discharges, and to interpret their geologic controls on land. For this purpose, two major lines of approach were followed. The first is an airborne thermal infrared (TIR) survey using radiometers to identify thermal anomalies, thereby determining the exact location of submarine groundwater discharges (SGDs). The second line of approach is the analysis of satellite images (Landsat 7ETM+) to delineate the geologic features that govern the mechanism of water flow, thereby determining their sources on land. Twenty-seven major SGDs were identified, 10 of these being offshore springs, the others littoral springs. The springs show a large variety of discharge configurations and extents, mainly parallel or perpendicular to the shoreline or rounded. Three major structural controls were identified to contribute to the transport of groundwater to the sea. These are karstic galleries, faults, and tilted rock strata, their contributions being 48, 37, and 15%, respectively. The SGDs associated with linear passageways, i.e., karstic galleries and faults, are connected with land aquifer formations several kilometers away from the shoreline. Moreover, the presence of impervious rock formations at many localities along the coastline results in a confined hydrologic system, promoting the flow of SGDs into the sea.  相似文献   
158.
Natural Resources Research - This study developed a new perspective of artificial neural networks using dimensional analysis to be applicable to certain prediction problems. To this end,...  相似文献   
159.
Planning versus youth: Stamping out spatial unruliness in Harare   总被引:1,自引:0,他引:1  
Amin Y. Kamete   《Geoforum》2008,39(5):1721-1733
The paper examines the illegal occupation and use of urban spaces by Harare’s youth and the ensuing tussles with the repressive machinery of the local authority and the nation-state. It analyses efforts by planning to contain rampant spatial unruliness. The paper maps the patterns of official hostile responses to the illegal activities of the youth whose daily routines inevitably entail the disregard of the spatial planning framework as reflected in existing legal and regulatory controls. The analysis reveals the reliance by the urban planning and management system on the use of force and violence, a feat made possible by the mobilisation of the repressive state apparatus. The discussion argues that what comes out in the relationship between the order-imposing planning system and the regulation-flouting youth is a situation that can largely be comprehended by turning to the non-progressive side of planning.  相似文献   
160.
Application of the copulas can be useful for the accurate multivariate frequency analysis of hydrological phenomena. There are many copula functions and some methods were proposed for estimating the copula parameters. Since the copula functions are mathematically complicated, estimating of the copula parameter is an effortful work. In the present study, an optimization-based method (OBM) is proposed to obtain the parameters of copulas. The usefulness of the proposed method is illustrated on drought events. For this purpose, three commonly used copulas of Archimedean family, namely, Clayton, Frank, and Gumbel copulas are used to construct the joint probability distribution of drought characteristics of 60 gauging sites located in East-Azarbaijan province, Iran. The performance of OBM was compared with two conventional methods, namely, method of moments and inference function for margins. The results illustrate the supremacy of the OBM to estimate the copula parameters compared to the other considered methods.  相似文献   
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