Object-oriented data modelling for spatial databases     

MICHAEL F. WORBOYS  HILARY M. HEARNSHAW  DAVID J. MAGUIRE 《International journal of geographical information science》2013,27(4):369-383

Data modelling is a critical stage of database design. Recent research has focused upon object-oriented data models, which appear more appropriate for certain applications than either the traditional relational model or the entity-relationship approach. The object-oriented approach has proved to be especially fruitful in application areas, such as the design of geographical information systems which have a richly structured knowledge domain and are associated with multimedia databases. This article discusses the key concepts in object-oriented modelling and demonstrates the applicability of an object-oriented design methodology to the design of geographical information systems. In order to show more clearly how this methodology may be applied, the paper considers the specific object-oriented data model IFO. Standard cartographic primitives are represented using IFO, which are then used in the modelling of some standard administrative units in the United Kingdom. The paper concludes by discussing current research issues and directions in this area.  相似文献   

Use of an expert system to map forest soils from a geographical information system     

ANDREW K. SKIDMORE  PHILIP J. RYAN  WARWICK DAWES  DAVID SHORT  EMMETT O'LOUGHLIN 《International journal of geographical information science》2013,27(4):431-445

Abstract

Mapping forest soils using conventional methods is time consuming and expensive. An expert system is described and applied to the mapping of five forest soil-landscape units formed on a single granitoid parent material. Three thematic maps were considered important in influencing the distribution of soils. The first showed the distribution of nine classes of native eucalypt forests, and the second and third were derived from a digital elevation model and represented slope gradient and a soil wetness index combined with topographical position. These layers were input to a raster based geographical information system (GIS) and then geometrically co-registered to a regular 30 m grid. From a knowledge of soil distributions, the relationships between the soil-landscape units and the three data layers were quantified by an experienced soil scientist and used as rules in a rule based expert system. The thematic layers accessed from the GIS provided data for the expert system to infer the forest soil-landscape unit most likely to occur at any given pixel. The soil-landscape map output by the expert system compared favourably with a conventional soil-landscape map generated using interpretation of aerial photographs.  相似文献   

GROUND THERMAL CONDITIONS AT CHACHANI VOLCANO,SOUTHERN PERU     

NURIA ANDRÉS  DAVID PALACIOS  JOSE ÚBEDA  JESÚS ALCALÁ 《Geografiska Annaler: Series A, Physical Geography》2011,93(3):151-162

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CITYSCAPES AND FOOTPRINTS: DANCING THROUGH THE URBAN MILIEU WITH LARRY FORD*     

DAVID J. KEELING 《Geographical review》2011,101(3):423-434

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Geochemical diagenetic trends during phosphorite formation – economic implications: The case of the Negev Campanian phosphorites,Southern Israel     

DAVID SOUDRY  YAACOV NATHAN  SARAH EHRLICH 《Sedimentology》2013,60(3):800-819

Research on the Upper Campanian (Upper Cretaceous) Negev phosphorites (Mishash Formation), based on microprobe analyses, Fourier Transform Infrared spectroscopy, wet chemistry, microtextural (Scanning Electron Microscopy) studies and mineralogical analyses, together with quantified rates of sedimentation and P accumulation, enables the chemistry of these rocks to be better constrained across the Negev area and allows their suitability for the manufacture of P fertilizers to be better determined. Two phosphorite facies are differentiated: (i) a pristine phosphorite facies of low P content, more typical of basinal sections and (ii) a reworked, granular phosphorite facies commonly enriched in P, found predominantly near palaeo‐highs and forming most of the economic phosphates. The distribution of F/P₂O₅, CO₂/F, U(IV), Cd, Zn and other trace metals (Mo, Ni, Cr, Cu, V and Y), rare‐earth elements concentration, Ce and Eu anomalies and heavy rare earth elements enrichment, are controlled by these two facies. F/P₂O₅ in carbonate‐fluorapatite is much lower (0·090 to 0·107) in the pristine than in the reworked facies (0·107 to 0·120); in addition, the lower F/P₂O₅ in the pristine facies is coupled with: (i) higher Cd, Zn, Mo, Ni, Cr, Cu and V concentrations; (ii) a considerably reduced (< 10%) U(IV) fraction of total U; (iii) lower rare earth elements/P₂O₅ and Y/P₂O₅ ratios; (iv) less negative Ce and Eu anomalies and lower heavy rare earth elements (Lu/La) enrichment; (v) an increase in Fe‐rich smectites in the clay fraction; and (vi) presence of OH in the carbonate‐fluorapatite structure. Sedimentary reworking of previously formed pristine phosphate, together with its redeposition near structural highs in more oxic bottom conditions, results in considerable diagenetic changes in the chemistry of the phosphorites, making them more suitable for economic exploitation. The results presented here provide geochemical criteria for identifying pristine phosphate in other phosphorite sequences and may help to better locate phosphate strata chemically suitable for the phosphate industry elsewhere.  相似文献   

Encounters with Mackinder: a personal memoir     

DAVID HOOSON 《The Geographical journal》2004,170(4):377-379

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H2O Abundance in Depleted to Moderately Enriched Mid-ocean Ridge Magmas; Part I: Incompatible Behaviour, Implications for Mantle Storage, and Origin of Regional Variations   总被引：1，自引：0，他引：1  

DANYUSHEVSKY  LEONID V.; EGGINS  STEPHEN M.; FALLOON  TREVOR J.; CHRISTIE  DAVID M. 《Journal of Petrology》2000,41(8):1329-1364

The H₂O contents and trace-element abundances are presentedfor two well-studied suites of mid-ocean ridge basalt (MORB)glasses from the Northern East Pacific Rise (EPR, 9–11°N)and the South East Indian Ridge (SEIR, 127–129°E).Exactly the same region of the glass samples has been analysedfor these components using microbeam techniques. Our data allowexamination of the fine details of H₂O geochemical behaviourduring MORB genesis. We demonstrate that relative H₂O contents[i.e. H₂O/(another incompatible element)] vary systematicallywith increasing (La/Sm)_N in MORB glasses from both the EPR andSEIR. This indicates that H₂O behaves like other incompatible(in peridotite mineralogies) elements during MORB petrogenesis,and is primarily controlled by solid–melt partitioning.However, the relative H₂O contents of MORB glasses from theSEIR are higher than in glasses from the EPR at a given (La/Sm)_N,demonstrating global variations in the H₂O contents of MORB.Despite regional differences in relative H₂O contents, the incompatiblebehaviour of H₂O is similar in both studied regions. The relativeincompatibility of H₂O varies systematically with increasing(La/Sm)_N: in depleted MORB, H₂O is similar to La whereas inEMORB, H₂O is similar to Ce. Similar patterns of varying relativeincompatibility (to REE) are displayed by Zr, Hf, and P. Ourdata are best explained if H₂O is stored in the mantle in thesame phase with LREE (clinopyroxene?) at sub-solidus. Regionalvariations in relative H₂O contents in EMORB that have moreradiogenic Sr, Nd and Pb isotopes might be explained by differencesin the nature of enriched components recycled via subductionprocesses. However, when EMORB have the same radiogenic isotopecompositions as NMORB within a segment, relative H₂O contentsin EMORB probably reflect local processes that lead to enrichmentin incompatible elements. Regional differences in relative H₂Ocontents of NMORB may reflect either initial variations in theEarth’s mantle or inhomogeneities left after formationof the continental crust. KEY WORDS: glass; geochemistry; H₂O; MORB; petrology  相似文献   

Historical Constraints on Slope Movement Age: a Case Study at Broadway, United Kingdom     

MALCOLM WHITWORTH  WILLIAM MURPHY  DAVID GLLES  DAVID PETLEY 《The Geographical journal》2000,166(2):139-155

The Broadway area of the Cotswolds has been extensively investigated in an attempt to delineate areas of slope instability, including'relict'landslides, which may have been initiated under periglacial climatic conditions. It is, therefore, useful both in terms of the geomorphology and of the understanding of the evolution of the area, to investigate the rates and timing of any reactivation and subsequent movements of landslides in this area. The remains of ridge and furrow cultivation can be seen extensively throughout the Cotswolds. This particular agricultural practice, which documentary evidence suggests dates back to Anglo-Saxon times (approximately 10th century AD), has been disturbed in many places by slope movements. A detailed study of Parish Records and other local his-torical sources has revealed that ridge and furrow cultivation ceased on Parliamentary Enclosure, which in this area, occurred in 1771. Therefore, it is possible to identify patterms of slope movement between these dates. Landslides have been identified by ground mapping and aerial photography, and can be divided into three categories. Firstly, active landslides which are those which have shown evidence of movement during the study period. Secondly, suspended landslides, which show evidence of movement, but have not been observed to move during the study period. In this context, this has been taken to mean landslides, which have shown evidence of movement since 1771. Thirdly, relict landslides which have shown no evidence of movement since 1771 and thus were probably active under a different climatic regime. By incorporating historical data with the geomorphological survey it has been possible to identify areas of potentially difficult ground for engineering geomorphological purposes.  相似文献   

MOUNTAIN GEOGRAPHY     

DAVID SMETHURST 《Geographical review》2000,90(1):35-56

ABSTRACT. Although mountains have been studied for centuries, they are the subject of only a slender body of formal literature. Instead, those who study high places in specific regions construct working definitions and continually recraft bibliographies. Studies of mountains often focus on comparatively limited themes: physical processes, ecology, or sacred spaces, for example. As scholars become interested in environmental degradation and the development of mountains, there is all the more need to develop a mountain geography literature that expands the study of mountains to include the political, economic, cultural, and social dimensions of their environments and peoples. Three areas‐cultural geography, political ecology, and conservation theory‐are suggested for additional research.  相似文献   

ANABRANCHING RIVERS: THEIR CAUSE,CHARACTER AND CLASSIFICATION     

GERALD C. NANSON  A. DAVID KNIGHTON 《地球表面变化过程与地形》1996,21(3):217-239

Anabranching rivers consist of multiple channels separated by vegetated semi-permanent alluvial islands excised from existing floodplain or formed by within-channel or deltaic accretion. These rivers occupy a wide range of environments from low to high energy, however, their existence has never been adequately explained. They occur concurrently with other types of channel pattern, although specific requirements include a flood-dominated flow regime and banks that are resistant to erosion, with some systems characterized by mechanisms to block or constrict channels, thereby triggering avulsion. The fundamental advantage of an anabranching river is that, by constructing a semi-permanent system of multiple channels, it can concentrate stream flow and maximize bed-sediment transport (work per unit area of the bed) under conditions where there is little or no opportunity to increase gradient. On the basis of stream energy, sediment size and morphological characteristics, six types of anabranching river are recognized; types 1–3 are lower energy and types 4–6 are higher energy systems. Type 1 are cohesive sediment rivers (commonly termed anastomosing) with low w/d ratio channels that exhibit little or no lateral migration. They are divisible into three subtypes based on vegetative and sedimentary environment. Type 2 are sand-dominated, island-forming rivers, and type 3 are mixed-load laterally active meandering rivers. Type 4 are sand-dominated, ridge-forming rivers characterized by long, parallel, channel-dividing ridges. Type 5 are gravel-dominated, laterally active systems that interface between meandering and braiding in mountainous regions. Type 6 are gravel-dominated, stable systems that occur as non-migrating channels in small, relatively steep basins. Anabranching rivers represent a relatively uncommon but widespread and distinctive group that, because of particular sedimentary, energy-gradient and other hydraulic conditions, operate most effectively as a system of multiple channels separated by vegetated floodplain islands or alluvial ridges.  相似文献