A scoping review on the multiplicity of scale in spatial analysis     

Oshan  Taylor M.  Wolf  Levi J.  Sachdeva  Mehak  Bardin  Sarah  Fotheringham  A. Stewart 《Journal of Geographical Systems》2022,24(3):293-324

Journal of Geographical Systems - Scale is a central concept in the geographical sciences and is an intrinsic property of many spatial systems. It also serves as an essential thread in the fabric...  相似文献   

Winter storm structure and melting‐induced circulations     

Ronald E. Stewart  Stephen R. Macpherson 《大气与海洋》2013,51(1):5-23

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An analytical description of three-dimensional heliocentric solar sail orbits     

Brian Stewart  Phil Palmer  Mark Roberts 《Celestial Mechanics and Dynamical Astronomy》2017,128(1):61-74

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The XMM–Newton/2dF survey – V. The radio properties of the X-ray population     

A. Georgakakis  I. Georgantopoulos  I. Leonidaki  A. Akylas  G. C. Stewart  C. Goudis 《Monthly notices of the Royal Astronomical Society》2004,352(3):1005-1014

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A neural network approach to classification of sidescan sonarimagery from a midocean ridge area     

Stewart  W.K. Min Jiang Marra  M. 《Oceanic Engineering, IEEE Journal of》1994,19(2):214-224

A neural-network approach to classification of sidescan-sonar imagery is tested on data from three distinct geoacoustic provinces of a midocean-ridge spreading center: axial valley, ridge flank, and sediment pond. The extraction of representative features from the sidescan imagery is analyzed, and the performance of several commonly used texture measures are compared in terms of classification accuracy using a backpropagation neural network. A suite of experiments compares the effectiveness of different feature vectors, the selection of training patterns, the configuration of the neural network, and two widely used statistical methods: Fisher-pairwise classifier and nearest-mean algorithm with Mahalanobis distance measure. The feature vectors compared here comprise spectral estimates, gray-level run length, spatial gray-level dependence matrix, and gray-level differences. The overall accurate classification rates using the best feature set for the three seafloor types are: sediment ponds, 85.9%; ridge flanks, 91.2%; and valleys, 80.1%. While most current approaches are statistical, the significant finding in this study is that high performance for seafloor classification in terms of accuracy and computation can be achieved using a neural network with the proper combination of texture features. These are preliminary results of our program toward the automated segmentation and classification of undersea terrain  相似文献   

Properties of metre-wavelength solar bursts associated with coronal mass ejections     

R. D. Robinson  R. T. Stewart  N. R. Sheeley Jr.  R. A. Howard  J. Koomen  D. J. Michels 《Solar physics》1986,105(1):149-171

An investigation is made to determine the relationship between a coronal mass ejection (CME) and the characteristics of associated metre-wave activity. It is found that (1) the CME width and leading edge velocity can be highly influential in determining the intensity, spectral complexity and frequency coverage of both type II and continuum bursts; (2) the presence of a CME is possibly a necessary condition for the production of a metric continuum event and (3) metric continuum bursts as well as intense, complex type II events are preferentially associated with strong, long lasting soft X-ray events.  相似文献   

Compliance costs and the small fisher: A study of exiters from the New Zealand fishery     

James Stewart  Kim Walshe 《Marine Policy》2008

Over 3000 predominantly small-scale fishers have exited the New Zealand's quota management system (QMS) between its inception in 1986 and 2000. This study, based on the Ministry of Fisheries database and a questionnaire sent to the exiters, establishes that compliance costs in general, and those specifically related to the QMS, were one of the most consistent reasons for exit. Uncertainty about future QMS policy and the high cost of quota were also significant factors. It appears that the small fishers’ perception of high compliance cost can be supported by industry data.  相似文献   

The XMM–Newton/2dF survey – IV. The X-ray spectral properties of the hard sources     

I. Georgantopoulos  A. Georgakakis  A. Akylas  G. C. Stewart  O. Giannakis  T. Shanks  S. Kitsionas 《Monthly notices of the Royal Astronomical Society》2004,352(1):91-100

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Saqqar: A 34 km diameter impact structure in Saudi Arabia          下载免费PDF全文

Thomas Kenkmann  Abdulkader M. Afifi  Simon A. Stewart  Michael H. Poelchau  Douglas J. Cook  Allen S. Neville 《Meteoritics & planetary science》2015,50(11):1925-1940

Here we present the first proof of an impact origin for the Saqqar circular structure in northwestern Saudi Arabia (Neville et al. 2014 ), with an apparent diameter of 34 km, centered at 29°35′N, 38°42′E. The structure is formed in Cambrian–Devonian siliciclastics and is unconformably overlain by undeformed Cretaceous and Paleogene sediments. The age of impact is not well constrained and lies somewhere between 410 and 70 Ma. The subsurface structure is constrained by 2‐D reflection seismic profiles and six drilled wells. First‐order structural features are a central uplift that rises approximately 2 km above regional datums, surrounded by a ring syncline. The crater rim is defined by circumferential normal faults. The central uplift and ring syncline correspond to a Bouguer gravity high and an annular ring‐like low, respectively. The wells were drilled within the central uplift, the deepest among them exceed 2 km depth. Sandstone core samples from these wells show abundant indicators of a shock metamorphic overprint. Planar deformation features (PDFs) were measured with orientations along (0001), {103}, and less frequently along {101} and {104}. Planar fractures (PFs) predominantly occur along (0001) and {101}, and are locally associated with feather features (FFs). In addition, some shocked feldspar grains and strongly deformed mica flakes were found. The recorded shock pressure ranges between 5 and 15 GPa. The preserved level of shock and the absence of an allochthonous crater fill suggest that Saqqar was eroded by 1–2 km between the Devonian and Maastrichtian. The documentation of unequivocal shock features proves the formation of the Saqqar structure by a hypervelocity impact event.  相似文献   

A note on the extreme intensity of ground‐based temperature inversions at Canadian micrometeorological towers     

I.M. Stewart 《大气与海洋》2013,51(3):23-28

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