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SWRC fit – a nonlinear fitting program with a water retention curve for soils having unimodal and bimodal pore structure  [PDF]
K. Seki
Hydrology and Earth System Sciences Discussions , 2007,
Abstract: The soil hydraulic parameters for analyzing soil water movement can be determined by fitting a soil water retention curve to a certain function, i.e., a soil hydraulic model. For this purpose, the program "SWRC Fit," which performs nonlinear fitting of soil water retention curves to 5 models by Levenberg-Marquardt method, was developed. The five models are the Brooks and Corey model, the van Genuchten model, Kosugi's log-normal pore-size distribution model, Durner's bimodal pore-size distribution model, and a bimodal log-normal pore-size distribution model propose in this study. This program automatically determines all the necessary conditions for the nonlinear fitting, such as the initial estimate of the parameters, and, therefore, users can simply input the soil water retention data to obtain the necessary parameters. The program can be executed directly from a web page at http://purl.org/net/swrc/; a client version of the software written in numeric calculation language GNU Octave is included in the electronic supplement of this paper. The program was used for determining the soil hydraulic parameters of 420 soils in UNSODA database. After comparing the root mean square error of the unimodal models, the van Genuchten and Kosugi's models were better than the Brooks and Corey model. The bimodal log-normal pore-size distribution model had similar fitting performance to Durner's bimodal pore-size distribution model.
Suitability of Soil Water Retention Characteristic Models (SWRC) in Regions and Soil Depth  [PDF]
Vitalis K. Too, Christian T. Omuto, Elijah K. Biamah, John P. O. Obiero
Journal of Water Resource and Protection (JWARP) , 2019, DOI: 10.4236/jwarp.2019.116044
Abstract: Soil Water Retention Characteristics (SWRC) models have been widely used in many applications. Presently, there are many models in the literature and many more still being developed so much so that it is confusing which model to prefer. The current choice of the appropriate model to use has not been well guided by any incisive research on the predictive performance of these models. Consequently, SWRC model applications have been largely moved by convenience. This study used a global dataset to evaluate 12 commonly used SWRC models. The measured data onto which the models were evaluated was grouped into different soil depths and different regions of the world. The evaluation used correlation, Nash-Sutcliffe efficiency, and residual standard error statistics to choose the best overall performing model and models for each category. It gives an indication of the type of SWRC models to use in different regions of the world and depths of sampling. The suitability of the models to regions showed that the Fredlund and Xing model had the best performance in subsoils in Africa; Omuto in Southern Asia; and van Genuchten in subsoils of the other regions. It is recommended that many more models be tested using the procedures in this study so that benchmarks can be established on SWRC model selection suitable for various regions.
Review of Soil Water Retention Characteristic (SWRC) Models between Saturation and Oven Dryness  [PDF]
Vitalis K. Too, Christian T. Omuto, Elijah K. Biamah, John P. Obiero
Open Journal of Modern Hydrology (OJMH) , 2014, DOI: 10.4236/ojmh.2014.44017
Abstract: Soil water retention characteristic is the key soil property used in many applications in the fields of irrigation, hydrology, geotechnical engineering and soil science in general. Since the advent of digital soil mapping and digital soil assessment paradigms, there has been an upsurge of development of soil inference models and the need to increase accurate application of soil mapping products. All soils can be partially saturated with water and also near oven dryness. Therefore, constitutive models for soils should ideally represent the soil behaviour over entire range. This paper reviewed commonly used SWRC models. In order to stem potential for biasness, the models were grouped into three categories depending on the number of fitting parameters, namely, five-parameter, four-parameter and three-parameter categories. The evaluation used correlation and residual standard error statistics to choose the best overall performing model and in each category. Its results serve as a guide for selecting the models to be preferred for fitting SWRC in case there are limitations to the number of suction potential levels in the measured data.
A software to calculate soil hydraulic conductivity in internal drainage experiments (SHC, Version 2.00)
Dourado Neto, Durval;Reichardt, Klaus;Silva, Adriana Lúcia da;Bacchi, Osny Oliveira Santos;Timm, Luis Carlos;Oliveira, Júlio César Martins;Nielsen, Donald R.;
Revista Brasileira de Ciência do Solo , 2007, DOI: 10.1590/S0100-06832007000500037
Abstract: a software for the calculation of unsaturated soil hydraulic conductivity k(q) is presented for commonly used methods found in the literature, based on field experiments in which a soil profile is submitted to water infiltration followed by internal drainage. the software is available at: dourado@esalq.usp.br.
Axially deformed solution of the Skyrme-Hartree-Fock-Bogolyubov equations using the transformed harmonic oscillator basis (II) HFBTHO v2.00d: a new version of the program  [PDF]
M. V. Stoitsov,N. Schunck,M. Kortelainen,N. Michel,H. Nam,E. Olsen,J. Sarich,S. Wild
Physics , 2012, DOI: 10.1016/j.cpc.2013.01.013
Abstract: We describe the new version 2.00d of the code HFBTHO that solves the nuclear Skyrme Hartree-Fock (HF) or Skyrme Hartree-Fock-Bogolyubov (HFB) problem by using the cylindrical transformed deformed harmonic-oscillator basis. In the new version, we have implemented the following features: (i) the modified Broyden method for non-linear problems, (ii) optional breaking of reflection symmetry, (iii) calculation of axial multipole moments, (iv) finite temperature formalism for the HFB method, (v) linear constraint method based on the approximation of the Random Phase Approximation (RPA) matrix for multi-constraint calculations, (vi) blocking of quasi-particles in the Equal Filling Approximation (EFA), (vii) framework for generalized energy density with arbitrary density-dependences, and (viii) shared memory parallelism via OpenMP pragmas.
Measurement Scale Effect on Prediction of Soil Water Retention Curve and Saturated Hydraulic Conductivity  [PDF]
Behzad Ghanbarian,Vahid Taslimitehrani,Guozhu Dong,Yakov A. Pachepsky
Computer Science , 2015,
Abstract: Soil water retention curve (SWRC) and saturated hydraulic conductivity (SHC) are key hydraulic properties for unsaturated zone hydrology and groundwater. In particular, SWRC provides useful information on entry pore-size distribution, and SHC is required for flow and transport modeling in the hydrologic cycle. Not only the SWRC and SHC measurements are time-consuming, but also scale dependent. This means as soil column volume increases, variability of the SWRC and SHC decreases. Although prediction of the SWRC and SHC from available parameters, such as textural data, organic matter, and bulk density have been under investigation for decades, up to now no research has focused on the effect of measurement scale on the soil hydraulic properties pedotransfer functions development. In the literature, several data mining approaches have been applied, such as multiple linear regression, artificial neural networks, group method of data handling. However, in this study we develop pedotransfer functions using a novel approach called contrast pattern aided regression (CPXR) and compare it with the multiple linear regression method. For this purpose, two databases including 210 and 213 soil samples are collected to develop and evaluate pedotransfer functions for the SWRC and SHC, respectively, from the UNSODA database. The 10-fold cross-validation method is applied to evaluate the accuracy and reliability of the proposed regression-based models. Our results show that including measurement scale parameters, such as sample internal diameter and length could substantially improve the accuracy of the SWRC and SHC pedotransfer functions developed using the CPXR method, while this is not the case when MLR is used. Moreover, the CPXR method yields remarkably more accurate soil water retention curve and saturated hydraulic conductivity predictions than the MLR approach.
Modelling Soil Water Retention for Weed Seed Germination Sensitivity to Water Potential  [PDF]
W. John Bullied,Paul R. Bullock,Rene C. Van Acker
Applied and Environmental Soil Science , 2012, DOI: 10.1155/2012/812561
Abstract: Soil water retention is important for the study of water availability to germinating weed seeds. Six soil water retention models (Campbell, Brooks-Corey, four- and five-parameter van Genuchten, Tani, and Russo) with residual soil water parameter derivations were evaluated to describe water retention for weed seed germination at minimum threshold soil water potential for three hillslope positions. The Campbell, Brooks-Corey, and four-parameter van Genuchten model with modified or estimated forms of the residual parameter had superior but similar data fit. The Campbell model underestimated water retention at a potential less than ?0.5?MPa for the upper hillslope that could result in underestimating seed germination. The Tani and Russo models overestimated water retention at a potential less than ?0.1?MPa for all hillslope positions. Model selection and residual parameter specification are important for weed seed germination by representing water retention at the level of minimum threshold water potential for germination. Weed seed germination models driven by the hydrothermal soil environment rely on the best-fitting soil water retention model to produce dynamic predictions of seed germination. 1. Introduction The soil water retention characteristic (SWRC) is a basic hydrophysical property of the soil that relates the water content of soil water to its energy state [1]. The water content-potential function is fundamental to the characterization of water holding capacity, water retention, and water flow in soil [2, 3]. The SWRC is necessary for modelling fluxes in soil water and is needed for germination studies where soil water is measured on a content basis. The timing of seed germination is a function of soil water potential [4]. As the soil dries, soil water potential is reduced, and it becomes increasingly difficult for seeds to imbibe water. At the minimum threshold (base) water potential, seeds do not imbibe sufficient water to initiate embryo growth and complete the germination process. The minimum threshold water potential at which germination ceases to occur in many agricultural weeds ranges from ?0.1 to ?1.5?MPa [5, 6]. Accurate representation of the SWRC over a wide range of water potential minimum thresholds is required for predictive modelling of seed germination. One of the greatest challenges in characterizing the SWRC for the shallow depth of the seedling recruitment zone (soil layer from which seeds germinate and emerge) across field topography is obtaining the parameters of the soil hydrological property. Determining the SWRC by direct
IVOA Recommendation: IVOA Astronomical Data Query Language Version 2.00  [PDF]
Inaki Ortiz,Jeff Lusted,Pat Dowler,Alexander Szalay,Yuji Shirasaki,Maria A. Nieto-Santisteban,Masatoshi Ohishi,William O'Mullane,Pedro Osuna,the VOQL-TEG Working Group,the VOQL Working Group
Physics , 2011,
Abstract: This document describes the Astronomical Data Query Language (ADQL). ADQL has been developed based on SQL92. This document describes the subset of the SQL grammar supported by ADQL. Special restrictions and extensions to SQL92 have been defined in order to support generic and astronomy specific operations.
N-Version Obfuscation: Impeding Software Tampering Replication with Program Diversity  [PDF]
Hui Xu,Yangfan Zhou,Michael R. Lyu
Computer Science , 2015,
Abstract: Tamper-resistance is a fundamental software security research area. Many approaches have been proposed to thwart specific procedures of tampering, e.g., obfuscation and self-checksumming. However, to our best knowledge, none of them can achieve theoretically tamper-resistance. Our idea is to impede the replication of tampering via program diversification, and thus increasing the complexity to break the whole software system. To this end, we propose to deliver same featured, but functionally nonequivalent software copies to different machines. We formally define the problem as N-version obfuscation, and provide a viable means to solve the problem. Our evaluation result shows that the time required for breaking a software system is linearly increased with the number of software versions, which is O(n) complexity.
2.00 μm Emission Properties of Tm3+/Ho3+ Co-doped Chalcohalide Glasses
WEI Shu-Lin, XU Yin-Sheng, ZHANG Pei-Qing, CHEN Fei-Fei, NIE Qiu-Hua, XU Tie-Feng, DAI Shi-Xun
无机材料学报 , 2012, DOI: 10.3724/sp.j.1077.2012.11483
Abstract: 2 μm laser has many potential applications on the medical surgery, laser radar, and pollution monitoring etc. Tm3+ and Ho3+ ions co-doped 70GeS2-20In2S3-10CsI chalcohalide glasses were synthesized by vacuumed melting- quenching technique. The DSC curves and Raman spectra showed that these glasses had good thermal stability and low phonon energy, respectively. The absorption and emission characteristics were evaluated with an emphasis on the 2.00 μm fluorescence from Ho3+: 5I7→5I8 transition. Under 808 nm excitation, the infrared emission bands extending from 1.80 μm to 2.10 μm can be seen on the emission spectra of the Tm3+ and Ho3+ ions co-doped glasses. This broad emission was consisted of two emission bands centered at 1.86 and 2.00 μm, corresponding to the optical transitions Tm3+:3F4→3F5 and Ho3+:5I7→5I8, respectively. At fixed Tm3+ ions concentration, the intensity of 2.00 μm emission increased with Ho3+ ions concentration increasing from 0.05mol% to 0.125mol%. The enhanced emission of Ho3+ ions gives another route to obtain the 2.00 μm infrared laser.
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