Landscape position and spatial patterns in the distribution of land use within the southern Appalachian Mountains   总被引：1，自引：1，他引：0  

Joshua S. Rice  Ryan E. Emanuel 《自然地理学》2014,35(5):443-457

Understanding the forces that influence the distribution of land use and land-use change (LUC) is an essential step in developing effective strategies for managing these issues. We examined the influence of landscape position on spatial patterns in land-use distribution within the Little Tennessee River Basin (LTRB) of the southern Appalachian Mountains. We show that landscape position, defined with respect to both natural and anthropogenic spatial variables, provides for the identification of statistically significant differences in the distribution of common forms of land use in the study region. Using the same variables, significant differences in the landscape positions subject to land-use change in the LTRB are also examined. These results suggest landscape position exerts a strong influence on the distribution of different forms of land use and the likeliness of given area undergoing LUC. The approach presented here, of considering land use as a function of landscape position that responds to both natural and anthropogenic forces, may prove useful in aiding the development of future strategies to address the consequences of land use in many regions.  相似文献   

A Comparative Analysis of Traveling Salesman Solutions from Geographic Information Systems     

Kevin M. Curtin  Gabriela Voicu  Matthew T. Rice  Anthony Stefanidis 《Transactions in GIS》2014,18(2):286-301

The Traveling Salesman Problem is one of the most prominent problems in combinatorial optimization, and is regularly employed in a wide variety of applications. The objective of this article is to demonstrate the extent of sub‐optimality produced by Traveling Salesman solution procedures implemented in the context of Geographic Information Systems and to discuss the consequences that such solutions have for practice. Toward that end, an analysis is made of Traveling Salesman solutions from implementations in four Geographic Information System packages. These implementations are tested against the optimal solution for a range of problem sizes. Computational results are presented in the context of a school bus routing application. This analysis concludes that no Traveling Salesman implementation in GIS is likely to find the optimal solution when problems exceed 10 stops. In contrast, optimal solutions can be generated with desktop linear programming software for up to 25 cities. Moreover, one GIS implementation consistently found solutions that were closer to optimal than its competitors. This research strongly suggests that for applications with fewer than 25 stops, the use of an optimal solution procedure is advised, and that GIS implementations can benefit from the integration of more robust optimization techniques.  相似文献   

Distribution and provenance of the Baginton Sand and Gravel in the Wreake Valley,northern Leicestershire,England: Implications for inter-regional correlation     

John Rice 《第四纪科学杂志》1991,6(1):39-54

The Baginton Sand and Gravel is traced along the lower Wreake Valley as a continuous water-laid stratum at the base of the drift succession. Its properties closely resemble those previously described from the proto-Soar valley, namely an upward fining sequence and a composition dominated by pebbles of Triassic and Carboniferous origin. Such a provenance is consistent with the idea that the proto-Soar once followed a route eastwards past Melton Mowbray, and that the drainage along the lower Wreake Valley has been reversed in the course of Pleistocene times. However, the slope of the sand and gravel train appears to be to the west rather than the east, and the rockhead relief is also inconsistent with an eastward-flowing proto-Soar. Until this enigma is resolved, it would be imprudent to use the Baginton Sand and Gravel as the basis for inter-regional correlations. The issue is further complicated by the preservation at Brooksby of earlier interglacial or interstadial deposits whose temporal affinities remain unclear.  相似文献   

Crust strength: a wind tunnel study of the effect of impact by saltating particles on cohesive soil surfaces   总被引：1，自引：0，他引：1  

M. A. Rice  I. K. McEwan 《地球表面变化过程与地形》2001,26(7):721-733

A wind tunnel study examined the effect of distributions of saltating particles on sediment surfaces which were characterized by distributions of their tensile strength. The sediments consisted of varying proportions of large sand‐sized particles with a fine particle cement. The energies of the impacting particles and the surface strengths were compared with the mass of material lost from the surface. It is important to consider distributions of parameters rather than mean values only, since abrasion and erosion may occur from surfaces not predicted from average strength and saltation velocities. At the impact velocities used in this study (mean velocity 4·4 m s^?1, with standard deviation of 0·51), surfaces containing less than 12 per cent fine material were easily eroded, but insignificant erosion occurred when the fine particle content exceeded 60 per cent. Small amounts of cementing material were easily ruptured, allowing the large sand grains to be moved (largely in creep) by the bombarding particles. A significant amount of energy was lost to the bed. As the percentage of fine material increased, the surface became more difficult to break up and less energy was lost to the bed. The probability that erosion will occur for known energy distributions of impacting particles and surface strength can be calculated and the mass loss increases exponentially with a decrease in the percentage of fine cementing particles. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Gravimetric ties, Europe-America     

Carlo Morelli  Donald A. Rice 《Journal of Geodesy》1955,29(4):35-41

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Symposium on the Reduction of Gravity Data     

D. A. Rice 《Journal of Geodesy》1962,36(1):7-14

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Comparisons of ²¹⁰Pb and pollen methods for determining rates of estuarine sediment accumulation     

Grace S. Brush  E.Ann Martin  Ruth S. DeFries  Cynthia A. Rice 《Quaternary Research》1982,18(2):196-217

Comparisons of sedimentation rates obtained by ²¹⁰Pb and pollen analyses of 1-m cores collected throughout the Potomac Estuary show good agreement in the majority of cores that can be analyzed by both methods. Most of the discrepancy between the methods can be explained by the analytical precision of the ²¹⁰Pb method and by the exactness with which time horizons can be identified and dated for the pollen method. X-radiographs of the cores and the distinctness of the pollen horizons preclude significant displacement by reworking and/or mixing of sediments. Differences between the methods are greatest where uncertainties exist in assigning a rate by one or both methods (i.e., ²¹⁰Pb trends and/or “possible” horizon assignments). Both methods show the same relative rates, with greater sediment accumulation more common in the upper and middle estuary and less toward the mouth. The results indicate that geochronologic studies of estuarine sediments should be preceded by careful observation of sedimentary structures, preferably by X-radiography, to evaluate the extent of mixing of the sediments. Time horizons, whether paleontologic or isotopic, are generally blurred where mixing has occurred, precluding precise identification. Whenever possible, two methods should be used for dating sediments because a rate, albeit erroneous, can be obtained isotopically in sediments that are mixed; accurate sedimentation rates are also difficult to determine where the time boundary is a zone rather than a horizon, where the historical record does not provide a precise date for the pollen horizon, or where scouring has removed some of the sediment above a dated pollen horizon.  相似文献   

Infrared Spectroscopy of V4334 Sgr (Sakurai's Object)     

David K. Lynch  Richard J. Rudy  Ray W. Russell  Carl J. Rice  Stephan Mazuk  Catherine Venturini  Richard C. Puetter  Michael L. Sitko  Roc Cutri 《Astrophysics and Space Science》2002,279(1-2):57-64

IR spectroscopy and photometry in the 0.8–2.4 and 3–14 mregions are reported for seven dates between March 21 1998 and July20 2000 UT. The shorter wavelength region displays a smooth continuum increasing to longerwavelengths that is indicative of the Wien tail of a Planck function. Only theHe I 1.0830 line is present early and it shows a P-Cygni profile which laterdisappears. The long wave spectra show a smooth continuum between 3 and 13m that was well fit by a gray body at 1000 K. A weak, unidentifiedemission feature appears between 8 and 10 m.  相似文献   

A casting procedure for reproducing coarse‐grained sedimentary surfaces     

Thomas Buffin‐Blanger  Ian Reid  Stephen Rice  Jim H. Chandler  Jill Lancaster 《地球表面变化过程与地形》2003,28(7):787-796

In the ?eld, the measurement of near‐bed hydraulics remains problematic. Greater precision is possible in the laboratory, but, in the case of gravels, it is dif?cult to create a water‐worked channel‐bed that is realistic enough to replicate faithfully the conditions found in nature. In this paper, a technique to reproduce coarse‐grained sedimentary fabrics of large areal extent is described. It involves moulding natural river‐bed surfaces from which facsimiles are cast. Remarkably realistic casts with dimensions of 1 m by 2 m have been produced and their quality assessed using spatial data derived using automated digital photogrammetry. The casts reproduce the prototype surfaces with errors at millimetre scale (0·5 per cent of the microrelief). The technique has facilitated the introduction of sedimentary surfaces that incorporate natural, complex structures of grains up to cobble size into experimental channels where detailed studies of near‐bed hydraulics can be carried out. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

The accuracy of a river bed moulding/casting system and the effectiveness of a low-cost digital camera for recording river bed fabric     

Jim H. Chandler  Tom Buffin-Bélanger  Steve Rice  Ian Reid  David J. Graham 《The Photogrammetric Record》2003,18(103):209-223

Digital photogrammetry has been used to develop and test an artificial river bed moulding and casting system, which allows the pebbles within a coarse-grain river bed to be recreated for hydraulic research in a laboratory flow channel or flume. Imagery of both the original streambed and the cast facsimile was acquired using a non-metric Kodak DCS460 digital camera and digital elevation models and orthophotographs were derived and compared to assess the accuracy of the moulding and casting system. These comparative tests proved to be critical in modifying and developing the system.
Additional imagery was obtained in the field using a non-metric Olympus C3030 'compact' digital camera to assess whether far cheaper camera technology could deliver data appropriate for such comparative examinations. Internal calibration parameter sets and data that were generated were compared with data obtained by the non-metric Kodak DCS460. These tests demonstrate that digital sensors built around high-quality 35 mm professional camera bodies and lenses are required for comparative examinations and for similar system development.  相似文献