Explicitly incorporating spatial dependence in predictive vegetation models in the form of explanatory variables: a Mojave Desert case study     

Jennifer Miller  Janet Franklin 《Journal of Geographical Systems》2006,8(4):411-435

Predictive vegetation modeling is defined as predicting the distribution of vegetation across a landscape based upon its relationship with environmental factors. These models generally ignore or attempt to remove spatial dependence in the data. When explicitly included in the model, spatial dependence can increase model accuracy. We develop presence/absence models for 11 vegetation alliances in the Mojave Desert with classification trees and generalized linear models, and use geostatistical interpolation to calculate spatial dependence terms used in the models. Results were mixed across models and methods, but in general, the spatial dependence terms more consistently increased model accuracy for widespread alliances. GLMs had higher accuracy in general.  相似文献   

COMPARISON OF HEAVY METAL CONCENTRATIONS IN SURFACE SEDIMENT OF TANJUNG PIAI WETLAND WITH OTHER SITES RECEIVING ANTHROPOGENIC INPUTS ALONG THE SOUTHWESTERN COAST OF PENINSULAR MALAYSIA     

Chee Kong Yap Mew Seong Choh Franklin Edward Berandah Ahmad Ismail Soon Guan Tan 《湿地科学》2006,4(1):48-57

1 INTRODUCTIONOur sampling trip to Tanjung Piai wetland in2002 showed that the site had not been developed andrecognized yet as a wetland of international importance(Ramsar). Recently, our field trip in January 2005to the same site to collect sediment sam…  相似文献   

An algorithm for generating stochastic cloud fields from radar profile statistics     

K. Franklin Evans  Warren J. Wiscombe 《Atmospheric Research》2004,72(1-4):263

An algorithm is described for generating stochastic three-dimensional (3D) cloud fields from time–height fields derived from vertically pointing radar. This model is designed to generate cloud fields that match the statistics of the input fields as closely as possible. The major assumptions of the algorithm are that the statistics of the fields are translationally invariant in the horizontal and independent of horizontal direction; however, the statistics do depend on height. The algorithm outputs 2D or 3D stochastic fields of liquid water content (LWC) and (optionally) effective radius. The algorithm is a generalization of the Fourier filtering methods often used for stochastic cloud models. The Fourier filtering procedure generates Gaussian stochastic fields from a “Gaussian” cross-correlation matrix, which is a function of a pair of heights and the horizontal distance (or “lag”). The Gaussian fields are nonlinearly transformed to give the correct LWC histogram for each height. The “Gaussian” cross-correlation matrix is specially chosen so that, after the nonlinear transformation, the cross-correlation matrix of the cloud mask fields approximately matches that derived from the input LWC fields. The cloud mask correlation function is chosen because the clear/cloud boundaries are thought to be important for 3D radiative transfer effects in cumulus.The stochastic cloud generation algorithm is tested with 3 months of boundary layer cumulus cloud data from an 8.6-mm wavelength radar on the island of Nauru. Winds from a 915-MHz wind profiler are used to convert the radar fields from time to horizontal distance. Tests are performed comparing the statistics of 744 radar-derived input fields to the statistics of 100 2D and 3D stochastic output fields. The single-point statistics as a function of height agree nearly perfectly. The input and stochastic cloud mask cross-correlation matrices agree fairly well. The cloud fractions agree to within 0.005 (the total cloud fraction is 18%). The cumulative distributions of optical depth, cloud thickness, cloud width, and intercloud gap length agree reasonably well. In the future, this stochastic cloud field generation algorithm will be used to study domain-averaged 3D radiative transfer effects in cumulus clouds.  相似文献   

Interaction of Vermiculite with Pb(II), Cd(II), Cu(II) and Ni(II) Ions in Single and Quaternary Mixtures          下载免费PDF全文

Kuppusamy Vijayaraghavan  Franklin D. Raja 《洁净——土壤、空气、水》2015,43(8):1174-1180

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Potassium Permanganate Doped Geopolymers for Remedial Applications     

Utku Solpuker  Zachary Cotter  Yongje Kim  Franklin W. Schwartz 《Ground Water Monitoring & Remediation》2014,34(4):93-101

This study investigates the use of KMnO₄ doped geopolymers as controlled‐release materials for remedial applications. The geopolymers were prepared by mixing alkali activated Na‐silicate solutions, metakaolin, and various amounts of granular KMnO₄. Samples were heat treated at 75 °C for 48 h. Concentrations of KMnO₄ in samples 1, 2, and 3 were 1.40 × 10^?1, 4.63 × 10^?1, and 6.07 × 10^?1 g/cm³, respectively. 1D column experiments showed that a high MnO₄^? release rate lasted for the first few hours, followed by a gradual decrease of MnO₄^? release. Neither cracks nor surface erosion of the geopolymers were observed throughout the experiments. Sample 1 approached exhaustion at the end of the Day 7. It took about 18 d for exhaustion of KMnO₄ releases in samples 2 and 3. Modeling of the observed KMnO₄ releases suggested diffusion and dissolution‐related fast transport as the most important mechanisms. This latter mechanism involves the creation of a connected secondary porosity in the geopolymers by dissolution of KMnO₄ granules. The contribution of Fickian diffusion to the total release decreased as the KMnO₄ content of the samples increased, and the dissolution mechanism became increasingly important.  相似文献   

Analysis of laboratory data on ultrasonic monitoring of permeability reduction due to biopolymer formation in unconsolidated granular media          下载免费PDF全文

J.G. Berryman  T.‐H. Kwon  S. Dou  J.B. Ajo‐Franklin  S.S. Hubbard 《Geophysical Prospecting》2016,64(2):445-455

We show how to estimate the fluid permeability changes due to accumulated biopolymer within the pore space of a granular material using laboratory measurements of overall permeability, together with various well‐known quantitative measures (e.g., porosity, specific surface area, and formation factor) of the granular medium microstructure. The main focus of the paper is on mutual validation of existing theory and a synthesis of new experimental results. We find that the theory and data are in good agreement within normal experimental uncertainties. We also establish quantitative empirical relationships between seismic and/or acoustic attenuation and overall permeability for these same systems.  相似文献   

Volume 50 and beyond     

Schwartz FW 《Ground water》2012,50(1):1-1

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Hydrologic connectivity of oxbow lakes along the lower Guadalupe River,Texas: The influence of geomorphic and climatic controls on the “flood pulse concept”     

Paul F. Hudson  Franklin T. Heitmuller  Maraigh B. Leitch 《Journal of Hydrology》2012

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An assessment of vessel traffic patterns in the Northwestern Hawaiian Islands between 1994 and 2004     

Franklin EC 《Marine pollution bulletin》2008,56(1):150-153

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Hurricane flood risk assessment for the Yucatan and Campeche State coastal area     

Rey  Wilmer  Mendoza  E. Tonatiuh  Salles  Paulo  Zhang  Keqi  Teng  Yi-Chen  Trejo-Rangel  Miguel A.  Franklin  Gemma L. 《Natural Hazards》2019,96(3):1041-1065

Natural Hazards - In this study, the first ever Sea, Lake, Overland Surges from Hurricanes (SLOSH) grid was built for the Yucatan Peninsula. The SLOSH model was used to simulate storm surges in the...  相似文献