Particle Swarm Optimization Algorithm for Neuro-Fuzzy Prospectivity Analysis Using Continuously Weighted Spatial Exploration Data     

Roshanravan  Bijan  Aghajani  Hamid  Yousefi  Mahyar  Kreuzer  Oliver 《Natural Resources Research》2019,28(2):309-325

Natural Resources Research - Classification of spatial exploration data for exploration targeting using neuro-fuzzy models means that the many spatial values have to be simplified and assigned to a...  相似文献   

An Improved Prediction-Area Plot for Prospectivity Analysis of Mineral Deposits     

Roshanravan  Bijan  Aghajani  Hamid  Yousefi  Mahyar  Kreuzer  Oliver 《Natural Resources Research》2019,28(3):1089-1105

Natural Resources Research - In this paper an improved prediction-area plot has been developed. This type of plot includes performance measures similar to other existing methods (receiver operating...  相似文献   

Urban structures and daily mobility patterns in a city of long distances—the case of Muscat/Oman     

Maike Didero  Sonja Nebel  Carmella Pfaffenbach 《Singapore journal of tropical geography》2019,40(3):361-386

Population growth, urban sprawl and a high degree of car dependency as well as slowly rising petrol prices contribute towards increasing challenges for everyday urban mobility in Muscat, Oman. Until now, only a few empirical studies have dealt with urban mobility in Oman. Therefore, this article draws mainly on our own empirical findings to answer the following questions: What do daily and weekly mobility patterns look like in Muscat? How do these practices differ depending on the social position of the household, i.e. their nationality, income and education? Which interdependent effects can be discerned between everyday mobility practices and the fragmented and segregated urban structures? Since our research questions focus on the interrelations between urban structures and individual mobility, we chose a mixed‐methods approach including methods derived both from social and spatial research. This article in particular draws on our quantitative survey covering 850 households and extensive mappings of three selected case study areas and secondary data analysis.  相似文献   

Managed realignment as compensation for the loss of intertidal mudflat: A short term solution to a long term problem?     

Krysia Mazik  Will Musk  Oliver Dawes  Katya Solyanko  Sue Brown  Lucas Mander  Mike Elliott 《Estuarine, Coastal and Shelf Science》2010

Intertidal mudflats are critical to the functional ecology of estuaries yet large areas are being lost as a result of land claim, erosion and coastal squeeze. This study examines whether managed realignment (at Paull Holme Strays, Humber estuary) can realistically achieve compensation for the loss of intertidal mudflat in the long term. Typical estuarine species quickly colonised the site with the total number of species recorded from the site as a whole being almost equal to that in the reference area within one year. Comparable biomass between the two areas was achieved after 2 years. However, organism abundance remains an order of magnitude lower within the realignment site compared to outside. Community structure within the realignment has changed from one characterised by terrestrial/freshwater organisms and early colonising species to one composed of typically estuarine species. However, the developing benthic communities only represent those typical of the estuary in areas of low elevation and high inundation frequency. Rapid accretion has favoured saltmarsh colonisation in much of the realignment site and this is expected to increase as accretion proceeds with invertebrate colonisation being inhibited by increasing elevation. Hence, realignment to restore intertidal mudflats can only be a short term solution in sites of high tidal elevation and in a dynamic and turbid estuary with high natural accretion rates, such as the Humber.  相似文献   

Enhanced nondestructive characterization of ordinary chondrites using complex magnetic susceptibility measurements     

P. Oliver  M. Ralchenko  C. Samson  R. E. Ernst  P. J. A. McCausland  G. F. West 《Meteoritics & planetary science》2018,53(3):433-447

Ordinary chondrites have previously been nondestructively characterized using bulk magnetic susceptibility, broadly reflecting their Fe-Ni alloy content. We seek to expand the information that can be recovered from magnetic susceptibility by using the University of Toronto Electromagnetic Induction Spectrometer (UTEMIS) to measure the complex magnetic susceptibility tensor of 20 ordinary chondrites samples in addition to 16 Gao–Guenie (H5) chondrites at 35 frequencies from 90 Hz to 64 kHz, at variable low applied field strengths <10 A m⁻¹. Following removal of the field-dependent component of susceptibility, frequency dependence, in- and out-of-phase components, and bulk magnetic susceptibility were interpreted. Most meteorites showed no frequency-dependent in-phase responses, but had a frequency-dependent out-of-phase response attributed to eddy currents induced in conductive minerals. Greater in- and out-of-phase frequency dependence correlated with lower fayalite content in olivine and was, in turn, inversely proportional to Fe-Ni alloy content. The uncertainty in the UTEMIS measurements ranges from approximately 0.05% for low-frequency in-phase measurements to a maximum of 3% for low-frequency out-of-phase measurements. This uncertainty level was far lower than the intra-meteorite variability for the Gao–Guenie suite suggesting inhomogeneity at scales of approximately 10 g.  相似文献   

Liebermannite,KAlSi3O8, a new shock-metamorphic,high-pressure mineral from the Zagami Martian meteorite          下载免费PDF全文

Chi Ma  Oliver Tschauner  John R. Beckett  George R. Rossman  Clemens Prescher  Vitali B. Prakapenka  Hans A. Bechtel  Alastair MacDowell 《Meteoritics & planetary science》2018,53(1):50-61

In this paper, we discuss the occurrence of liebermannite (IMA 2013-128), KAlSi₃O₈, a new, shock-generated, high-pressure tetragonal hollandite-type structure silicate mineral, in the Zagami basaltic shergottite meteorite. Liebermannite crystallizes in space group I4/m with Z = 2, cell dimensions of a = 9.15 ± 0.14 (1σ) Å, c = 2.74 ± 0.13 Å, and a cell volume of 229 ± 19 Å³ (for the type material), as revealed by synchrotron diffraction. In Zagami, liebermannite likely formed via solid-state transformation of primary igneous K-feldspar during an impact event that achieved pressures of ~20 GPa or more. The mineral name is in honor of Robert C. Liebermann, a high-pressure mineral physicist at Stony Brook University, New York, USA.  相似文献   

Kalman-filter-based GPS clock estimation for near real-time positioning   总被引：11，自引：4，他引：7  

André Hauschild  Oliver Montenbruck 《GPS Solutions》2009,13(3):173-182

In this article, an algorithm for clock offset estimation of the GPS satellites is presented. The algorithm is based on a Kalman-filter and processes undifferenced code and carrier-phase measurements of a global tracking network. The clock offset and drift of the satellite clocks are estimated along with tracking station clock offsets, tropospheric zenith path delay and carrier-phase ambiguities. The article provides a brief overview of already existing near-real-time and real-time clock products. The filter algorithm and data processing scheme is presented. Finally, the accuracy of the orbit and clock product is assessed with a precise orbit determination of the MetOp satellite and compared to results gained with other real-time products.

André HauschildEmail:

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Antenna phase center calibration for precise positioning of LEO satellites   总被引：6，自引：3，他引：3  

Oliver Montenbruck  Miquel Garcia-Fernandez  Yoke Yoon  Steffen Schön  Adrian Jäggi 《GPS Solutions》2009,13(1):23-34

Phase center variations of the receiver and transmitter antenna constitute a remaining uncertainty in the high precision orbit determination (POD) of low Earth orbit (LEO) satellites using GPS measurements. Triggered by the adoption of absolute phase patterns in the IGS processing standards, a calibration of the Sensor Systems S67-1575-14 antenna with GFZ choke ring has been conducted that serves as POD antenna on various geodetic satellites such as CHAMP, GRACE and TerraSAR-X. Nominal phase patterns have been obtained with a robotic measurement system in a field campaign and the results were used to assess the impact of receiver antenna phase patterns on the achievable positioning accuracy. Along with this, phase center distortions in the actual spacecraft environment were characterized based on POD carrier phase residuals for the GRACE and TerraSAR-X missions. It is shown that the combined ground and in-flight calibration can improve the carrier phase modeling accuracy to a level of 4 mm which is close to the pure receiver noise. A 3.5 cm (3D rms) consistency of kinematic and reduced dynamic orbit determination solutions is achieved for TerraSAR-X, which presumably reflects the limitations of presently available GPS ephemeris products. The reduced dynamic solutions themselves match the observations of high grade satellite laser ranging stations to 1.5 cm but are potentially affected by cross-track biases at the cm-level. With respect to the GPS based relative navigation of TerraSAR-X/TanDEM-X formation, the in-flight calibration of the antenna phase patterns is considered essential for an accurate modeling of differential carrier phase measurements and a mm level baseline reconstruction.

Oliver MontenbruckEmail:

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Vertebrate taphonomy. R. Lee Lyman, 1994, Cambridge University Press,xxvi + 524 pp., $79.95 (hardback), $34.95 (softbound)     

James S. Oliver 《Geoarchaeology》1996,11(3):265-268

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