http://www.sciencedirect.com/science/article/pii/S1674987113000601     

Nicholas Arndt 《地学前缘(英文版)》2013,4(5):479-480

The intrusions of the Panzhihua-Xichang(Panxi) region in southwest China have become well known in the past decade because they host large and rich magmatic oxide deposits that are mined for Fe,Ti and V.These intrusions form part of the Emeishan large igneous province(ELIP),which is commonly believed to be the product of melting in a mantle plume.The ELIP was emplaced about 260 Ma ago,at the same time as the end-Guadalupian mass extinction.The investigation of the Panxi intrusions therefore provides information relevant to three broad areas of the earth sciences:(1)the petrogenesis of mafic magmas, (2) the impact of major magmatic events and global climate and  相似文献   

Analytical hydrologic models and the design of policy instruments for groundwater-quality management     

Yusuke Kuwayama  Nicholas Brozovi? 《Hydrogeology Journal》2012,20(5):957-972

This paper explores how analytical hydrologic models can inform the effective design and choice of policy instruments to manage groundwater quality by coupling a social-planner’s problem of optimal groundwater-quality management with analytical solutions from the hydrology literature. A theoretical analysis is performed in order to characterize the properties of an optimal emissions policy. The model is then applied in a numerical analysis of groundwater contamination by chloride from highway deicers, demonstrating the relevance of the theoretical results to practical management settings. This analytical approach can help determine which policy instruments are likely to be effective in controlling groundwater pollution, especially if costly numerical groundwater models are not available for the aquifer in question. Unlike previous economic studies of groundwater contamination, this approach defines optimal emissions policies as a function of geophysical parameters employed by hydrologists such as distance between source and sink, groundwater velocity, and aquifer dispersivity. The theoretical section of this paper also demonstrates that the relationship between geophysical parameters and optimal emissions levels may be ambiguous.  相似文献   

New <Superscript>40</Superscript>Ar/<Superscript>39</Superscript>Ar laser single-grain ages of muscovites from mylonitic schists in the Rodna Mountains,Eastern Carpathians,Romania: correlations with microstructure   总被引：2，自引：0，他引：2  

Nicholas Culshaw  Emilia Mosonyi  Peter Reynolds 《International Journal of Earth Sciences》2012,101(1):291-306

The Rodna Mountains afford the most internal structural window into the crystalline units of the Eastern Carpathians in Romania. The Rodna Mountains consist of Variscan metamorphic nappes that were restacked in the Alpine phase of Carpathian development forming the Subbucovinian and Infrabucovinian nappes. In order to evaluate age of deformation, ten samples were taken from the zone of greenschist facies mylonitic schist that marks the Alpine tectonic boundary between the Subbucovinian and Infrabucovinian nappes and ⁴⁰Ar/³⁹Ar laser single-grain ages determined for schistosity-forming muscovite. Microstructural assessment of quartz and muscovite distinguished two deformation events. Single-grain ages from the microstructurally most strongly reworked samples (four samples) give a tight clustering of ages at ca. 95 Ma. The least reworked schists have a broader clustering of ages spanning ca. 200–280 Ma with a late Permian peak and some samples showing outlier ages in the range 200–100 Ma. The relative development of the outliers, which correlates with evidence for increased microstructural reworking, is interpreted to mark progressive isotopic resetting. The ca. 95 Ma ages for the most reworked schists are estimates for the age of the Alpine nappe stacking. The ca. 200–280 Ma ages are similar to those of magmatism, metamorphism, and sedimentation thought to mark post-Variscan-pre-Alpine rifting and ocean basin formation in parts of the Alps and may be the thermal imprint of a related event in the Eastern Carpathians.  相似文献   

Corrected prediction intervals for change detection in paired watershed studies     

Nicholas A. Som  Nicolas P. Zégre  Lisa M. Ganio  Arne E. Skaugset 《水文科学杂志》2013,58(1):134-143

Abstract

Hydrological data may be temporally autocorrelated requiring autoregressive process parameters to be estimated. Current statistical methods for hydrological change detection in paired watershed studies rely on prediction intervals, but the current form of prediction intervals does not include all appropriate sources of variation. Corrected prediction intervals for the analysis of paired watershed study data that include variation associated with covariance and linear model parameter estimation are presented. We provide an example of their application to data from the Hinkle Creek Paired Watershed Study located in the western Cascade foothills of Southern Oregon, USA. Research implications of using the correct prediction limits and incorporating the estimation uncertainty of autoregressive process parameters are discussed.

Editor D. Koutsoyiannis

Citation Som, N.A., Zégre, N.P., Ganio, L.M. and Skaugset, A.E., 2012. Corrected prediction intervals for change detection in paired watershed studies. Hydrological Sciences Journal, 57 (1), 134–143.  相似文献   

Dredging displaces bottlenose dolphins from an urbanised foraging patch     

Enrico Pirotta  Barbara Eva Laesser  Andrea Hardaker  Nicholas Riddoch  Marianne Marcoux  David Lusseau 《Marine pollution bulletin》2013

The exponential growth of the human population and its increasing industrial development often involve large scale modifications of the environment. In the marine context, coastal urbanisation and harbour expansion to accommodate the rising levels of shipping and offshore energy exploitation require dredging to modify the shoreline and sea floor. While the consequences of dredging on invertebrates and fish are relatively well documented, no study has robustly tested the effects on large marine vertebrates. We monitored the attendance of common bottlenose dolphins (Tursiops truncatus) to a recently established urbanised foraging patch, Aberdeen harbour (Scotland), and modelled the effect of dredging operations on site usage. We found that higher intensities of dredging caused the dolphins to spend less time in the harbour, despite high baseline levels of disturbance and the importance of the area as a foraging patch.  相似文献   

Geomorphology from space: A global overview of regional landforms     

Nicholas M. Short  Robert W. Blair Jr. 《国际地球制图》2013,28(4)

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Object-based classification with features extracted by a semi-automatic feature extraction algorithm – SEaTH     

Yan Gao  Prashanth Marpu  Imgard Niemeyer  Daniel Miller Runfola  Nicholas M. Giner  Thomas Hamill 《国际地球制图》2013,28(3):211-226

Object-based image analysis (OBIA) uses object features (or attributes) that relateto the pixels contained by the image object to assist in image classification. These object features include spectral, shape, texture and context features. With hundreds of available features, the identification of those that can improve separability between classes is critical for OBIA. The Separability and Thresholds (SEaTH) algorithm calculates the SEaTH of object–classes for the given features. The SEaTH algorithm avoids time-consuming trial-and-error practice for seeking important features and thresholds. This article tests the SEaTH algorithm on Landsat-7 Enhanced Thematic Mapper (ETM+) imagery in a heterogeneous landscape with multiple land cover classes. The results suggest SEaTH is a strong alternative to other automated approaches, yielding an agreement of 79% with reference data. In comparison, an object-based nearest neighbour classifier yielded 66% agreement and a pixel-based maximum likelihood classifier yielded 69% agreement.  相似文献   

Object-based classification with features extracted by a semi-automatic feature extraction algorithm – SEaTH     

Yan Gao  Prashanth Marpu  Imgard Niemeyer  Daniel Miller Runfola  Nicholas M. Giner  Thomas Hamill 《国际地球制图》2013,28(5)

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The Effect of Data Inaccuracy on Tests of Space‐Time Interaction     

Nicholas Malizia 《Transactions in GIS》2013,17(3):426-451

Space‐time event data are often subject to deficiencies in: (1) locational accuracy; (2), temporal accuracy; and (3) completeness. This work explores how these failings in the quality of input data may affect the results of global space‐time interaction tests. While previous work has partially investigated the impact of locational inaccuracy on the results of these tests, more work remains. The impacts of temporal inaccuracy and incomplete data reporting on the results of these tests remain completely unexplored. This study examines the influence of these problems individually and collectively, using a series of simulations. Findings demonstrate that even in cases of slight inaccuracy or underreporting, the consequences on results are potentially severe. Although the study is couched in terms of data inaccuracy, its relevance to situations where inaccuracy is replaced with uncertainty is self‐evident.  相似文献   

Satellite clock bias estimation for iGPS   总被引：4，自引：0，他引：4  

John Pratt  Penina Axelrad  Kristine M. Larson  Bruno Lesage  Richard Gerren  Nicholas DiOrio 《GPS Solutions》2013,17(3):381-389

The High Integrity GPS program seeks to provide enhanced navigation performance by combining conventional GPS with a communications and ranging broadcast from the Iridium^® Communications System. Through clock and message aiding, it would enable existing GPS receivers to acquire and track in more challenging environments. As is the case for standard GPS, accurate and precise timing is key to performance. An approach is presented for estimating the bias of each Iridium satellite clock using satellite-to-ground and satellite-to-satellite measurements. The satellite clock bias estimates are based on a Kalman filter that incorporates code-type observations from the measurements at 10 s intervals. Filter parameters are set based on the expected behavior of the clocks, allowing for discontinuous bias and frequency adjustments due to ground commands. Typical results show the current filter to be accurate to within 200 ns while always meeting the initial system specification of half a microsecond.  相似文献