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201.
Andrea G. Fabbri Freek D. van der Meer Carlos R. Valenzuela Cornelius A. Kushigbor 《Mathematical Geology》1993,25(7):773-793
This paper discusses the usage of mathematical morphology in image processing of remotely-sensed data for geologic interpretation. Particular attention is given to noise-reducing transformations of spectral bands before and after different methods of classification, and to the usage of textural context. The development of a viable processing strategy requires a multidisciplinary approach and expert knowledge in different areas: (a) geology, geomorphology, and vegetation in a study area, (b) properties of the sensor for imagery photointerpretation, (c) spectral/spatial properties of the digital data within an integrated dataset (remote sensing and ancillary data), and (d) data-processing tools including mathematical morphology theory. Examples of geometric characterization of Canadian LANDSAT scenes are described in which shape measurements are obtained using a PC-based hybrid image-processing and geographic information system, termed ILWIS, which was developed at ITC, in the Netherlands. Classes from supervised and unsupervised classification are compared to guide in geological mapping. Classes over individual occurrences of broad vegetation-landform units are studied to aid in environmental mapping. Field knowledge is the context necessary to construct expert procedures to drive sequences of data-processing steps toward a target result such as optimal classification, enhancement, or feature extraction. The interaction between expert rules and the image-processing steps can be based on synthetic measurements of shape to quantize the information either spatially or spectrally. Many useful geometrical transformations of spatially-distributed data are extensions or generalizations of spatial analysis functions typical of geographic information systems. 相似文献
202.
A daily surface soil moisture model described and tested previously with data from the Phoenix, AR (USA) area, has been applied now to climate data collected in semi-arid Botswana over a multi-year period. The physically based model was calibrated with observed surface moisture data from one growing season and validated with data from another. Good overall agreement (r2 = .89) was found between the observed and modelled data. The seasonal variability of precipitation in this region is reflected in the simulated daily surface moisture. The response of the natural savanna vegetation as observed from monthly composites of satellite-derived Normalized Difference Vegetation Index (NDVI) is also monitored for the same period. It is seen that the NDVI peaks at different times during the rainy season from one year to the next, according not only to the total seasonal precipitation, but its temporal distribution as well. It is also seen that there is a delay in intraseasonal vegetation response. While the NDVI is poorly correlated with the current month's average soil moisture, a distinct relationship with the previous month's average soil moisture was found. 相似文献
203.
François Holtz Donald B. Dingwell Harald Behrens 《Contributions to Mineralogy and Petrology》1993,113(4):492-501
The effects of F, B2O3 and P2O5 on the H2O solubility in a haplogranite liquid (36 wt. % SiO2, 39 wt. % NaAlSi3O8, 25 wt. % KAlSi3O8) have been determined at 0.5, 1, 2, and 3 kb and 800, 850, and 900°C. The H2O solubility increases with increasing F and B content of the melt. The H2O solubility increase in more important at high pressure (2 and 3 kb) than at low pressure (0.5 kb). At 2 kb and 800°C, the H2O solubility increases from 5.94 to 8.22 wt. % H2O with increasing F content in the melt from 0 to 4.55 wt. %, corresponding to a linear H2O solubility increase of 0.53 mol H2O/mol F. With addition of 4.35 wt. % B2O3, the H2O solubility increases up to 6.86 wt. % H2O at 2 kb and 800°C, corresponding to a linear increase of 1.05 mol H2O/mol B2O3. The results allow to define the individual effects of fluorine and boron on H2O solubility in haplogranitic melts with compositions close to that of H2O-saturated thermal minima (at 0.5–3 kb). Although P has a dramatic effect on the phase relations in the haplogranite system, its effect on the H2O solubility was found to be negligible in natural melt compositions. The concominant increase in H2O solubility and F can not be interpreted on the basis of the available spectroscopic data (existence of hydrated aluminofluoride complexes or not). In contrast, hydrated borates or more probably boroxol complexes have been demonstrated in B-bearing hydrous melts. 相似文献
204.
Harald Rensvik 《Marine pollution bulletin》1994,29(6-12):277-278
The paper discusses the role of all parties involved in the debate about environmental standards, their relationships in an ideal situation, the weaknesses today and how these weaknesses could be corrected. The question of who should set the environmental standards is an important element on the way to this ideal situation. It is considered necessary that all parties, industry, consumers, government regulations and the green lobby, should contribute to the development of better environmental standards. 相似文献
205.
W. Schröder 《Annales Geophysicae》1994,12(8):808-809
It is shown that such data that exist on auroral activity in the period between 1450 and 1550 do not provide conclusive evidence that some authors have claimed for the existence of the so-called “Spörer minimum” in solar activity during this interval. 相似文献
206.
207.
208.
R. A. D. Pattrick G. van der Laan D. J. Vaughan C. M. B. Henderson 《Physics and Chemistry of Minerals》1993,20(6):395-401
L-edge X-ray absorption spectroscopy employing a synchrotron radiation source has been used to study the electronic structure and valency of Cu in the chemically and structurally complex tetrahedrite group of minerals. Mechanical mixtures of Cu2+O and Cu+FeS2 were used to estimate the relative cross sections of Cu2+ and Cu+; the absorption of Cu2+ at 931 eV is 25 times greater than that of Cu+ at 945 eV. Using this calibration, Cu2+/Cu ratios were found to vary from 0.00 to 0.054 in the tetrahedrite samples studied; the highest proportion of Cu2+ occurs in synthetic tetrahedrites with a composition close to Cu12Sb4S13. This study reveals the utility of the technique for determining the valence state of copper in complex minerals, allowing the crystal chemistry to be more fully characterised. 相似文献
209.
Hydrophobic and electrostatic parameters in bacterial adhesion 总被引:5,自引:0,他引:5
Mark C. M. van Loosdrecht Willem Norde Johannes Lyklema Alexander J. B. Zehnder 《Aquatic Sciences - Research Across Boundaries》1990,52(1):103-114
Recently it has been shown that the initial stages of bacterial adhesion to a model-surface of sulphated polystyrene can best be described using hydrophobic and electrostatic parameters. In the present study it is tested whether these parameters can generally be applied to predict bacterial adhesion by using (i) glass, as a model for hydrophilic and natural surfaces of silicates and oxides, (ii) polystyrene coated with proteins, as a model for a surface coated with an organic layer, and (iii) river Rhine sediment, as an example of a natural surface. Adhesion to glass was dominated by electrostatic interaction, whereas adhesion to polystyrene coated with various types of proteins depended on the surface characteristics of the bacteria and the type of protein. By relating Van der Waals interactions to hydrophobicity of the interacting species, the adhesion of bacteria to the various surfaces including the river Rhine sediments could be interpreted in terms of the DLVO-theory. It is therefore concluded that the conceptual principles of the DLVO-theory (interplay of Van der Waals and electrostatic interactions) are suitable to describe, at least qualitatively, the initial processes of bacterial adhesion to a wide range of surfaces. 相似文献
210.
The study examines the spatial relationships between sediment yield and 15 independent environmental variables in 54 catchments in South Africa. Rooseboom's (1978) data on the sediment yield from the catchments were standardized for a single time period. Bivariate regression analyses reveal no simple relationships. Multivariate regression analyses conducted for the whole and various sub-areas of South Africa indicate that latitude and longitude are the primary variables affecting spatial variations in sediment yield. This may be as a result of latitude and longitude being surrogate variables reflecting variation in other environmental variables (e. g. geology, vegetation). Within the sub-areas, 43.4% to 97.8% of the variation in sediment yield is explained by the combined variation in a number of different environmental variables. This study highlights a need for the collection and analysis of more sediment yield data, which would allow the analyses to be refined, to predict sediment yields from ungauged catchments in South Africa. 相似文献