Using Statistical Learning Algorithms in Regional Landslide Susceptibility Zonation with Limited Landslide Field Data   总被引：4，自引：3，他引：1  

WANG Yi-ting  SEIJMONSBERGEN Arie Christoffel  BOUTEN Willem  CHEN Qing-tao 《山地科学学报》2015,(2):268-288

Regional Landslide Susceptibility Zonation(LSZ) is always challenged by the available amount of field data, especially in southwestern China where large mountainous areas and limited field information coincide. Statistical learning algorithms are believed to be superior to traditional statistical algorithms for their data adaptability. The aim of the paper is to evaluate how statistical learning algorithms perform on regional LSZ with limited field data. The focus is on three statistical learning algorithms, Logistic Regression(LR), Artificial Neural Networks(ANN) and Support Vector Machine(SVM). Hanzhong city, a landslide prone area in southwestern China is taken as a study case. Nine environmental factors are selected as inputs. The accuracies of the resulting LSZ maps are evaluated through landslide density analysis(LDA), receiver operating characteristic(ROC) curves and Kappa index statistics. The dependence of the algorithm on the size of field samples is examined by varying the sizes of the training set. The SVM has proven to be the most accurate and the most stable algorithm at small training set sizes and on all known landslide sizes. The accuracy of SVM shows a steadilyincreasing trend and reaches a high level at a small size of the training set, while accuracies of LR and ANN algorithms show distinct fluctuations. The geomorphological interpretations confirm the strength of SVM on all landslide sizes. Our results show that the strengths of SVM in generalization capability and model robustness make it an appropriate and efficient tool for regional LSZ with limited landslide field samples.  相似文献   

The comparison between H2CO and OH in the Milky Way     

Wei Hua Guo  Jarken Esimbek  Xin Di Tang  Jian Jun Zhou  Willem A. Baan  Ye Yuan  Gang Wu  Yan Jun Zhang  Toktarkhan Komesh 《Astrophysics and Space Science》2016,361(8):264

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Adsorption and surface oxidation of Fe(II) on metal (hydr)oxides     

Tjisse Hiemstra  Willem H. van Riemsdijk 《Geochimica et cosmochimica acta》2007,71(24):5913-5933

The Fe(II) adsorption by non-ferric and ferric (hydr)oxides has been analyzed with surface complexation modeling. The CD model has been used to derive the interfacial distribution of charge. The fitted CD coefficients have been linked to the mechanism of adsorption. The Fe(II) adsorption is discussed for TiO₂, γ-AlOOH (boehmite), γ-FeOOH (lepidocrocite), α-FeOOH (goethite) and HFO (ferrihydrite) in relation to the surface structure and surface sites. One type of surface complex is formed at TiO₂ and γ-AlOOH, i.e. a surface-coordinated Fe²⁺ ion. At the TiO₂ (Degussa) surface, the Fe²⁺ ion is probably bound as a quattro-dentate surface complex. The CD value of Fe²⁺ adsorbed to γ-AlOOH points to the formation of a tridentate complex, which might be a double edge surface complex. The adsorption of Fe(II) to ferric (hydr)oxides differs. The charge distribution points to the transfer of electron charge from the adsorbed Fe(II) to the solid and the subsequent hydrolysis of the ligands that coordinate to the adsorbed ion, formerly present as Fe(II). Analysis shows that the hydrolysis corresponds to the hydrolysis of adsorbed Al(III) for γ-FeOOH and α-FeOOH. In both cases, an adsorbed M(III) is found in agreement with structural considerations. For lepidocrocite, the experimental data point to a process with a complete surface oxidation while for goethite and also HFO, data can be explained assuming a combination of Fe(II) adsorption with and without electron transfer. Surface oxidation (electron transfer), leading to adsorbed Fe(III)(OH)₂, is favored at high pH (pH > ∼7.5) promoting the deprotonation of two Fe_III-OH₂ ligands. For goethite, the interaction of Fe(II) with As(III) and vice versa has been modeled too. To explain Fe(II)-As(III) dual-sorbate systems, formation of a ternary type of surface complex is included, which is supposed to be a monodentate As(III) surface complex that interacts with an Fe(II) ion, resulting in a binuclear bidentate As(III) surface complex.  相似文献   

A kinematic study of the integral shaped filament:what roles do filaments play in forming young stellar clusters?     

Gang Wu  Esimbek Jarken  Willem Baan  Jian-Jun Zhou  Dong-Dong Zhou  Xiao-Hong Han  Aldiyar Agishev 《天文和天体物理学研究(英文版)》2018,(7)

Young protoclusters(embedded stellar clusters) are responsible for the vast majority of star formation currently occurring in the Galaxy. Recent observations suggest a scenario in which filamentary structures in the interstellar medium represent the first step towards precluster clumps and eventually star formation. Whether filaments continuously fuel the star formation process when the cluster accretes material is still an open question. In this paper, we present a case study of the famous ‘integral shaped filament'(ISF) in the Orion A molecular cloud and we seek to study the kinematics which is truly originated from the ISF. We firstly define the central ridge of the ISF with NH_3,~(12) CO,~(13) CO and N_2H~+. Undulations are present in all the ridges. Moreover, a large scale offset is apparent in the ridges as derived by different tracers, which may be explained by the slingshot mechanism proposed by Stutz Gould. We fit the velocity field of the ISF and find the derived velocity gradient is about 0.7 km s~(-1) pc~(-1) which may come from an overall contraction. We propose a method to check the accretion flow along the ISF by using the velocity deviations of different molecular tracers, which is better than the common method of using the velocity distribution of one tracer alone. Using the velocity deviations, we also find that OMC-1 to 5 are located close to the local extrema of the fluctuations, which may demonstrate that gas flows toward each clump along the ISF.  相似文献   

Report on the eight UN/ESA Workshop on Basic Space Science: Scientific Exploration from Space     

Hans J. Haubold  Willem Wamsteker 《Astrophysics and Space Science》2000,273(1-4):331-341

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Reply on ‘Sequence stratigraphy of an argillaceous,deepwater basin plain succession: Vischkuil Formation (Permian), Karoo Basin,South Africa’ from van der Merwe,Flint and Hodgson (Marine and Petroleum Geology, 2010, 27, 321–333)     

Willem C. van der Merwe  Stephen S. FlintDavid M. Hodgson 《Marine and Petroleum Geology》2010

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Calibration facility for airborne imaging spectrometers     

Peter Gege  Jochen Fries  Peter Haschberger  Paul Schtz  Horst Schwarzer  Peter Strobl  Birgit Suhr  Gerd Ulbrich  Willem Jan Vreeling 《ISPRS Journal of Photogrammetry and Remote Sensing》2009,64(4):387-397

A new facility designed to perform calibration measurements of airborne imaging spectrometers was established at the German Aerospace Center (DLR) in Oberpfaffenhofen. This Calibration Home Base (CHB) is optimized to characterize radiometrically, spectrally, and geometrically the APEX (Airborne Prism Experiment) imaging spectrometer, which is currently being developed under the authority of the European Space Agency (ESA). It however can be used for other optical sensors as well. Computer control of major laboratory equipment allows automation of time consuming measurements. In APEX configuration (wavelength range: 380 to 2500 nm, instantaneous field of view: 0.48 mrad, field of view: ±14) spectral measurements can be performed to a wavelength uncertainty of ±0.15 nm, geometric measurements at increments of 0.0017 mrad across track and 0.0076 mrad along track, and radiometric measurements to an uncertainty of ±3% relative to national standard. The CHB can be adapted to similar sensors (including those with thermal infrared detectors) by exchanging the monochromator’s lamp, the gratings and the filters, and by adjusting the distance between the sensor and folding mirror.  相似文献   

The effect of a northward shift in the southern hemisphere westerlies on the global ocean     

Willem P. Sijp  Matthew H. England 《Progress in Oceanography》2008,79(1):1-19

We examine the effect of a northward shift in the position of the southern hemisphere subpolar westerly winds (SWWs) on the vertical and horizontal distribution of temperature and salinity in the world ocean. A northward shift of the SWWs causes a latitudinal contraction of the subpolar gyres in the southern hemisphere (SH). In the Indian and Pacific, this leads to subsurface warming in the subtropical thermocline. As the southern margins of the gyres move into latitudes characterised by warmer surface air temperature (SAT), the layers at mid-depth below 400 m depth become ventilated by warmer water. We characterize the approximation of the ventilated thermocline in our coarse resolution model using a set of passive tracer experiments, and illustrate how the northward shift in the SWWs causes an equatorward shift in the latitude of origin of water ventilating layers deeper than 400 m in the Indian and Pacific, leaving the total surface ventilation of the upper 1200 m unchanged. In contrast, the latitudinal constraint on the Antarctic Circumpolar Current posed by the Drake Passage causes a cooling and freshening throughout the Atlantic thermocline; here, subsurface thermocline water originates from higher latitudes under the wind shift. On longer timescales Atlantic cooling and freshening is reinforced by a reduction in North Atlantic Deep Water (NADW) formation and surface salinification of the Indian and Pacific Oceans. In effect, the latitude of zero wind stress curl in the SWWs regulates the relative importance of the “cold water route” via the Drake Passage and the “warm water route” associated with thermocline water exchange via the Indian Ocean. Thus, a more northward location of the SWWs corresponds with a reduced salinity contrast between the Indian/ Pacific Oceans and the Atlantic. This results in reduced NADW formation. Also, a more northward location of the SWWs facilitates the injection of cool fresh Antarctic Intermediate Water into the South Atlantic subtropical gyre. Beyond these changes, on a millennial timescale, the deep ocean warms throughout the water column in response to the wind shift. Global salinity stratification also becomes less stable, as more saline water remains at the surface and accumulates in the Indian and Pacific thermocline. The freshening of the deep ocean reflects a reduced stirring of the global ocean due to reduced net circulation arising from a misalignment between the westerlies and the topographically constrained ACC. Our results lend support to the idea that a more equatorward location of the SWW maximum during glacial climates contributed to cooler and fresher conditions in the Atlantic, inhibiting NADW.  相似文献   

Startle response of captive North Sea fish species to underwater tones between 0.1 and 64 kHz     

Kastelein RA  Heul Sv  Verboom WC  Jennings N  Veen Jv  de Haan D 《Marine environmental research》2008,65(5):369-377

World-wide, underwater background noise levels are increasing due to anthropogenic activities. Little is known about the effects of anthropogenic noise on marine fish, and information is needed to predict any negative effects. Behavioural startle response thresholds were determined for eight marine fish species, held in a large tank, to tones of 0.1-64 kHz. Response threshold levels varied per frequency within and between species. For sea bass, the 50% reaction threshold occurred for signals of 0.1-0.7 kHz, for thicklip mullet 0.4-0.7 kHz, for pout 0.1-0.25 kHz, for horse mackerel 0.1-2 kHz and for Atlantic herring 4 kHz. For cod, pollack and eel, no 50% reaction thresholds were reached. Reaction threshold levels increased from approximately 100 dB (re 1 microPa, rms) at 0.1 kHz to approximately 160 dB at 0.7 kHz. The 50% reaction thresholds did not run parallel to the hearing curves. This shows that fish species react very differently to sound, and that generalisations about the effects of sound on fish should be made with care. As well as on the spectrum and level of anthropogenic sounds, the reactions of fish probably depend on the context (e.g. location, temperature, physiological state, age, body size, and school size).  相似文献   

Determining water requirements for Black Box (Eucalyptus largiflorens) floodplain woodlands of high conservation value using drip-irrigation     

Tanya M. Doody  Susan L. Gehrig  R. Willem Vervoort  Matthew J. Colloff  Rebecca Doble 《水文研究》2021,35(7):e14291

Black Box (Eucalyptus largiflorens F. Muell.), is a keystone tree species of lowland semi-arid floodplain ecosystems in south-eastern Australia. E. largiflorens woodlands are of high conservation value and threatened by climate change-induced drought and irrigation water diversions due to their location on upper floodplain areas where flood frequency has declined. Water requirements of E. largiflorens have not been well quantified using empirical data. Accordingly, knowledge gaps exist in relation to volumes of environmental water required to maintain and improve ecological condition for disconnected floodplain woodlands. To further assist conservation and water resource management, we tested the use of drip irrigation to provide a variety of water regimes to experimental plots in order to monitor tree responses. Water was provided via irrigation delivery across four regimes representing known volumes of water, referred to as an environmental water provision, applied over a 22-week period for two Austral summers. Benefits to trees were identified by measuring transpiration and plant water status using sap flow sensors and a Scholander pressure chamber, respectively. Results indicate that volumes of 0.3, 0.4, 0.7 and 0.8 ML increased transpiration and improved plant water status in comparison to a control, with delivery recommended to commence early autumn. Greater volumes (1.4 ML), substantially increased transpiration and improved water status, especially when delivered at a rate of ~25 mm week⁻¹ compared to a monthly 'burst' which broadly represented natural, sporadic summer rainfall in the region. For an environmental watering provision of 25 mm week⁻¹, ~178 ha of E. largiflorens woodland can be watered with a 1 GL environmental water allocation. The study methods presented are relevant worldwide and our results further the collective understanding of the benefits environmental water provides to E. largiflorens.  相似文献