Performance analysis of radial basis function networks and multi-layer perceptron networks in modeling urban change: a case study     

Hossein Shafizadeh-Moghadam  Julian Hagenauer  Manuchehr Farajzadeh  Marco Helbich 《International journal of geographical information science》2013,27(4):606-623

The majority of cities are rapidly growing. This makes the monitoring and modeling of urban change’s spatial patterns critical to urban planners, decision makers, and environment protection activists. Although a wide range of methods exists for modeling and simulating urban growth, machine learning (ML) techniques have received less attention despite their potential for producing highly accurate predictions of future urban extents. The aim of this study is to investigate two ML techniques, namely radial basis function network (RBFN) and multi-layer perceptron (MLP) networks, for modeling urban change. By predicting urban change for 2010, the models’ performance is evaluated by comparing results with a reference map and by using a set of pertinent statistical measures, such as average spatial distance deviation and figure of merit. The application of these techniques employs the case study area of Mumbai, India. The results show that both models, which were tested using the same explanatory variables, produced promising results in terms of predicting the size and extent of future urban areas. Although a close match between RBFN and MLP is observed, RBFN demonstrates higher spatial accuracy of prediction. Accordingly, RBFN was utilized to simulate urban change for 2020 and 2030. Overall, the study provides evidence that RBFN is a robust and efficient ML technique and can therefore be recommended for land use change modeling.  相似文献   

Galaxy Evolution tool: Construction and Applications     

Yeshe Fenner  Brad K. Gibson  Marco Limongi 《Astrophysics and Space Science》2002,281(1-2):537-538

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Microplate motions in the hotspot reference frame     

Marco Cuffaro  Donna M. Jurdy 《地学学报》2006,18(4):276-281

We have computed motions of the major plates (seven large plates and seven medium‐sized plates) and 38 microplates relative to the hotspot reference frame, and present velocities of these 52 plates. Moreover, using updated plate boundaries for the present, we have computed new geometrical factors for plates and microplates, useful for kinematic calculations and to obtain the net‐rotation of the lithosphere and plate velocities in the mean‐lithosphere reference frame. Instead of a continuum or gradational distribution of the plates by size, the plates clearly partition into three groups each having their own characteristics. For the seven large plates, rotation poles generally lie in high latitudes; the seven medium‐sized plates have rotation poles in a restricted equatorial area; the 38 small plates show the greatest scatter. Moreover subsets of the 52 plates reveal differing fractal behaviour: the large, middle and small groupings each have a characteristic fractal dimension, suggestive of microplate clustering. The highest angular velocities occur for some of the smallest plates, with the location of their rotation poles closeby. Terra Nova, 18, 276–281, 2006  相似文献   

Long term spectral variability in the soft gamma-ray repeater SGR 1900+14     

Andrea Tiengo  Paolo Esposito  Sandro Mereghetti  Lara Sidoli  Diego Götz  Marco Feroci  Roberto Turolla  Silvia Zane  Gian Luca Israel  Luigi Stella  Peter Woods 《Astrophysics and Space Science》2007,308(1-4):33-37

We present a systematic analysis of all the BeppoSAX data of SGR1900+14. The observations spanning five years show that the source was brighter than usual on two occasions: ～20 days after the August 1998 giant flare and during the 10⁵?s long X-ray afterglow following the April 2001 intermediate flare. In the latter case, we explore the possibility of describing the observed short term spectral evolution only with a change of the temperature of the blackbody component. In the only BeppoSAX observation performed before the giant flare, the spectrum of the SGR1900+14 persistent emission was significantly harder and detected also above 10 keV with the PDS instrument. In the last BeppoSAX observation (April 2002) the flux was at least a factor 1.2 below the historical level, suggesting that the source was entering a quiescent period.  相似文献   

A Geometric Interpretation of Integrable Motions     

Cecilia Clementi  Marco Pettini 《Celestial Mechanics and Dynamical Astronomy》2002,84(3):263-281

Integrability, one of the classic issues in galactic dynamics and in general in celestial mechanics, is here revisited in a Riemannian geometric framework, where Newtonian motions are seen as geodesics of suitable -mechanical- manifolds. The existence of constants of motion that entail integrability is associated with the existence of Killing tensor fields on the mechanical manifolds. Such tensor fields correspond to hidden symmetries of non-Noetherian kind. Explicit expressions for Killing tensor fields are given for the N = 2 Toda model, and for a modified Hénon-Heiles model, recovering the already known analytic expressions of the second conserved quantity besides energy for each model respectively.  相似文献   

First results from the H i Jodrell All Sky Survey: inclination-dependent selection effects in a 21-cm blind survey     

Robert H. Lang  Peter J. Boyce  Virginia A. Kilborn  Robert F. Minchin  Michael J. Disney  Christine A. Jordan  Marco Grossi  Diego A. Garcia  Ken C. Freeman  Steven Phillipps  Alan E. Wright 《Monthly notices of the Royal Astronomical Society》2003,342(3):738-758

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Geometry of Chaos in Models of Stellar Dynamics     

Guido Ciraolo  Marco Pettini 《Celestial Mechanics and Dynamical Astronomy》2002,83(1-4):171-190

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Uncertainties in limits on TeV-gravity from neutrino-induced showers     

Eun-Joo Ahn  Marco Cavagli  Angela V. Olinto 《Astroparticle Physics》2005,22(5-6):377-385

In models with TeV-scale gravity, ultrahigh energy cosmic rays can generate microscopic black holes in the collision with atmospheric and terrestrial nuclei. It has been proposed that stringent bounds on TeV-scale gravity can be obtained from the absence of neutrino cosmic ray showers mediated by black holes. However, uncertainties in the cross section of black hole formation and, most importantly, large uncertainties in the neutrino flux affects these bounds. As long as the cosmic neutrino flux remains unknown, the non-observation of neutrino induced showers implies less stringent limits than present collider limits.  相似文献   

Cosmological weak lensing with the HST GEMS survey     

Catherine Heymans  Michael L. Brown  Marco Barden  John A. R. Caldwell  Knud Jahnke  Chien Y. Peng  Hans-Walter Rix  y Taylor  Steven V. W. Beckwith  Eric F. Bell  rea Borch  Boris Häußler  Shardha Jogee  Daniel H. McIntosh  Klaus Meisenheimer  Sebastian F. Sánchez  Rachel Somerville  Lutz Wisotzki  Christian Wolf 《Monthly notices of the Royal Astronomical Society》2005,361(1):160-176

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Experiments and Numerical Simulations on the Mid-Term Evolution of Hypersonic Jets     

Marco Belan  Sergio de Ponte  Silvano Massaglia  Daniela Tordella 《Astrophysics and Space Science》2004,293(1-2):225-232

The experiment described here is focussed to the observation of underexpanded, hypersonic turbulent jets. The experiment is relevant to a few aspects concerning the dynamics of astrophysical phenomena such as the Herbig-Haro jets and to the interaction between the large-scale vortices and the system of shocks that determine the spreading and entrainment properties of highly compressible free-flows. A number of orifice jets with a ratio between the stagnation pressure and the ambient pressure of the order 10³-10⁴ have been studied by changing the stagnation/ambient density ratio. This has been realized using dissimilar gases in the jet and in the ambient medium: by using He, Ar and air the stagnation/ambient density ratio can be changed by one order of magnitude while keeping fixed the pressure ratio. It has been possible to visualize the near and mid-term evolution of the jets and measure the axial and transversal density distributions. A comparison relevant to the shock waves configuration in between the nozzle exit and the first Mach's disk is shown for an air in air laboratory jet and its numerical simulation.  相似文献