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1. Simple method for determining cable length resistance in time domain reflectometry systems [1998]

Reece, C.F.
 Soil Science Society of America (USA), MarApr 1998, v. 62(2) p. 314317.
 Subjects

Soil chemistry and physics, Mathematical and statistical methods, ANALYTICAL METHODS, ELECTRICAL CONDUCTIVITY, SOIL TESTING, MEASUREMENT, SOIL SALINITY, MATHEMATICS, CORRECTION FACTORS, DETERMINATION, ERRORS, and CALCULATION
 Abstract

references
Time domain reflectometry (TDR) based electrical conductivity (EC) measurements underestimate solution conductivity as salinity increases unless a correction parameter, R(cable), is incorporated into the EC calculation. The parameter R(cable) accounts for series resistance of cable, connectors, and cable tester. The main objective of this study was to propose and verify a simple method of directly measuring R(cable) from the load resistance on waveguides that are shorted together. Also, the dependence of R(cable) on cable length vs. other resistances was investigated. The parameter R(cable) was found to be a function of cable length and a constant probe resistance. Errors caused by ignoring R(cable) in EC determinations increased with both salinity and series resistance. Although there may be cases where R(cable) has a negligible effect on EC determinations, there are also situations where it is important. This study shows that the measurement of R(cable) is so simple that there is little reason not to routinely incorporate it in all TDRbased EC determinations
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Wang, D., Yates, S.R., and Ernst, F.F.
 Soil Science Society of America (USA), MarApr 1998, v. 62(2) p. 318325.
 Subjects

Soil chemistry and physics, Mathematical and statistical methods, SOIL TESTING, SOIL WATER CONTENT, SOIL WATER POTENTIAL, SOIL WATER RETENTION, INFILTRATION, SOIL CHEMICOPHYSICAL PROPERTIES, MEASUREMENT, MEASURING INSTRUMENTS, ANALYTICAL METHODS, MATHEMATICAL MODELS, MATHEMATICS, SORPTIVITY, MATRIC POTENTIAL, SATURATED HYDRAULIC CONDUCTIVITY, ESTIMATION, DETERMINATION, and CALCULATION
 Abstract

references
Tension infiltrometers have become a popular instrument for field determination of soil hydraulic properties. To develop and test different models for parameter estimation based on tension infiltrometer measurement, we obtained simultaneous measurements of transient tension infiltration rate, soil water content, and tension using small time domain reflectometry (TDR) probes and tensiometers installed at fixed locations relative to the infiltrometer disk. Infiltration was made with 10 and 20cmdiam. disks under 1 and 5 cm of water supply tensions. The soil is an Arlington fine sandy loam (coarseloamy, mixed, thermic Haplic Durixeralf). Wooding's steadystate approximate solution for water flow from a surface circular pond was used to estimate the saturated hydraulic conductivity (K(s)) and an empirical parameter (alpha G) used in Gardner's exponential hydraulic conductivity function. These two parameters (i.e., K(s) and alpha G) were then independently estimated using an integral form of the steadystate DarcyBuckingham flux law. A sorptivity method was also proposed as an alternative to Wooding's steadystate approach. Calculated K(s) and alpha G with the DarcyBuckingham flux law method was in good agreement with estimates using Wooding's steadystate approximation. The sorptivity method produced K(s) estimates that were statistically similar to those obtained with Wooding's method. The K(h) inferred from measured theta(h) underestimated the conductivity close to saturation compared with estimates obtained from the infiltrometer measurements
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Smith, J.E., Robin, M.J.L., and Elrick, D.E.
 Soil Science Society of America (USA), NovDec 1997, v. 61(6) p. 15631568.
 Subjects

Soil chemistry and physics, Mathematical and statistical methods, SOIL AIR, PERMEABILITY, MEASUREMENT, AIR FLOW, MATHEMATICS, PRESSURE, AIR TEMPERATURE, AIR DU SOL, PERMEABILITE, MESURE, FLUX D'AIR, MATHEMATIQUE, PRESSION, TEMPERATURE DE L'AIR, AIRE DEL SUELO, PERMEABILIDAD, MEDICION, FLUJO DE AIRE, MATEMATICAS, PRESION, TEMPERATURA DEL AIRE, DETERMINATION, CALCULATION, and TEMPORAL VARIATION
 Abstract

references
The data from transientflow air permeameters often exhibit curvature in the theoretically linear plots of the natural log of pressure vs. time. This was originally attributed to errors in water manometer data caused by the inertia of the water in the manometer. The resulting recommendation was to ignore the early time data when calculating the air permeability of a soil by these methods. We have demonstrated and quantified that the exhibited curvature is a direct consequence of small changes in temperature in the source air tank as a result of the cooling of the expanding air during the permeability determination. This was accomplished by interfacing the air permeameter with a computer to collect pressure and temperature data at a relatively high frequency. The data acquisition procedure facilitated the calculation of the change in pressure and temperature with respect to time, which allowed the direct solution of the differential form of the equations describing the mass flux of air from the tank through the core. The data is compared with the theoretical relationship expected for the core based on air permeability determined using a steadystate method
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Zhang, R.
 Soil Science Society of America (USA), NovDec 1997, v. 61(6) p. 15971603.
 Subjects

Soil chemistry and physics, Mathematical and statistical methods, SOIL TESTING, SOIL WATER, WATER, FLOW RATE, SOIL CHEMICOPHYSICAL PROPERTIES, INFILTRATION, MEASUREMENT, MEASURING INSTRUMENTS, MATHEMATICS, MATHEMATICAL MODELS, ANALYSE DE SOL, EAU DU SOL, EAU, DEBIT, PROPRIETE PHYSICOCHIMIQUE DU SOL, MESURE, INSTRUMENT DE MESURE, MATHEMATIQUE, MODELE MATHEMATIQUE, ANALISIS DEL SUELO, AGUA DEL SUELO, AGUA, GASTO, PROPIEDADES FISICOQUIMICAS SUELO, INFILTRACION, MEDICION, INSTRUMENTOS DE MEDICION, MATEMATICAS, MODELOS MATEMATICOS, SOIL SORPTIVITY, SOIL HYDRAULIC PROPERTIES, HYDRAULIC CONDUCTIVITY, DETERMINATION, EQUATIONS, and CALCULATION
 Abstract

references
The disk infiltrometer is becoming a widely used device for determining soil hydraulic properties in the field. To describe the infiltration process from the disk infiltrometer, a twoterm equation was developed. The first and second terms characterize water flow out of the disk due to capillary forces and gravity, respectively. The parameter of the first term in the equation was a product of a nondimensional coefficient and soil sorptivity. The parameter of the second term was a product of another nondimensional coefficient and soil hydraulic conductivity. Timedependent relationships were obtained from numerical models to determine the coefficients based on physical parameters of the infiltrometer, such as the radius and tension used; and soil retention parameters. The cumulative infiltration and steadystate infiltration rate calculated using the twoterm equation were in excellent agreement with numerically simulated results for various soils, and radii and tensions of disk infiltrometers. Absolute relative errors of predicted infiltration were 5% for soils ranging from clay to sand. The infiltration solution is an accurate, yet simple approach to estimate fluxes from an axisymmetric source. It can also be applied to estimate soil sorptivity and hydraulic conductivity using inverse methods
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Skidmore, E.L.
 Soil Science Society of America (USA), SepOct 1997, v. 61(5) p. 15321535.
 Subjects

Soil chemistry and physics, Soil erosion, conservation and reclamation, Mathematical and statistical methods, SOIL, RIDGING, ORIENTATION, MATHEMATICS, WIND EROSION, MEASUREMENT, SOL, BILLONNAGE, MATHEMATIQUE, EROSION EOLIENNE, MESURE, SUELO, ALOMADO, ORIENTACION, MATEMATICAS, EROSION EOLICA, MEDICION, SURFACE ROUGHNESS, ESTIMATION, RIDGES, EQUATIONS, and CALCULATION
 Abstract

references. Original articles: "Soil roughness measurement: Chain method", A. Saleh, Journal of Soil and Water Conservation, 48 (6), 1993, p. 527529 and "Measuring and predicting ridge: orientation effect on soil surface roughness", A. Saleh, Soil Science Society of America Journal, 58 (4), 1994, p. 12281230. Reply by A. Saleh, p. 15331535
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6. Effect of thermal processing and addition of carriers on water sorption isotherms in baker's yeast [1996]

Kaminski, W., Mitura, E., and Tomczak, E.
 Drying technology (USA), 1996, v. 14(2) p. 245258.
 Subjects

Processing of nonfood or nonfeed agricultural products, Food processing and preservation, Mathematical and statistical methods, SACCHAROMYCES CEREVISIAE, BAKERS' YEAST, INOCULATION METHODS, CHEMICOPHYSICAL PROPERTIES, WATER, SORPTION, MEASUREMENT, MATHEMATICS, DRYING, LEVURE DE BOULANGERIE, INOCULATION, PROPRIETE PHYSICOCHIMIQUE, EAU, MESURE, MATHEMATIQUE, SECHAGE, LEVADURAS DE PANADERIA, INOCULACION, PROPIEDADES FISICOQUIMICAS, AGUA, SORCION, MEDICION, MATEMATICAS, SECADO, MIXTURES, DETERMINATION, and CALCULATION
 Abstract

references. Paper presented at the 8th Polish drying symposium held June, 1994, Warsaw, Poland
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Kolin, B., Danon, G., and Janezic, T.S.
 Drying technology (USA), 1995, v. 13(8/9) p. 21332139.
 Subjects

Processing of forest products, Mathematical and statistical methods, WOOD, QUERCUS ROBUR, FAGUS SYLVATICA, PICEA ABIES, HYGROSCOPICITY, MEASUREMENT, WOOD ANATOMY, CHEMISTRY, CELLULOSES, MOISTURE CONTENT, STRENGTH, TEMPERATURE, DENSITY, MATHEMATICS, WOOD PROPERTIES, BOIS, HYGROSCOPICITE, MESURE, ANATOMIE DU BOIS, CHIMIE, CELLULOSE, TENEUR EN EAU, RESISTANCE MECANIQUE, DENSITE, MATHEMATIQUE, PROPRIETE DU BOIS, MADERA, HIGROSCOPICIDAD, MEDICION, ANATOMIA DE LA MADERA, QUIMICA, CELULOSA, CONTENIDO DE HUMEDAD, RESISTENCIA MECANICA, TEMPERATURA, DENSIDAD, MATEMATICAS, PROPIEDADES DE LA MADERA, FIBER SATURATION POINT, CELLULOSE CONTENT, DETERMINATION, COMPRESSIVE STRENGTH, and CALCULATION
 Abstract

references
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Fryrear, D.W., Krammes, C.A., Williamson, D.L., and Zobeck, T.M.
 Journal of soil and water conservation (USA), MarApr 1994, v. 49(2) p. 183188.
 Subjects

Soil erosion, conservation and reclamation, Mathematical and statistical methods, WIND EROSION, EROSION, MEASUREMENT, METHODS, SOIL TEXTURE, SOIL SEPARATES, SOIL, ORGANIC MATTER, CARBON, CALCIUM CARBONATE, MATHEMATICS, MATHEMATICAL MODELS, EROSION CONTROL, EROSION EOLIENNE, MESURE, METHODE, TEXTURE DU SOL, FRACTION DU SOL, SOL, MATIERE ORGANIQUE, CARBONE, CARBONATE DE CALCIUM, MATHEMATIQUE, MODELE MATHEMATIQUE, LUTTE ANTIEROSION, EROSION EOLICA, MEDICION, METODOS, TEXTURA DEL SUELO, FRACCIONES DEL SUELO, SUELO, MATERIA ORGANICA, CARBONO, CARBONATO DE CALCIO, MATEMATICAS, MODELOS MATEMATICOS, CONTROL DE LA EROSION, ERODIBILITY, DETERMINATION, METHODOLOGY, CALCULATION, and CORRELATION
 Abstract

references
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Perkins, P.V.
 Communications in soil science and plant analysis (USA), 1994, v. 25(15/16) p. 26492664.
 Subjects

Soil chemistry and physics, Mathematical and statistical methods, SOIL, SOIL PARENT MATERIALS, WATER, MOISTURE CONTENT, BORON, SOIL SOLUTION, MEASUREMENT, SOIL WATER CONTENT, MATHEMATICAL MODELS, ADSORPTION, SORPTION, NUTRIENT AVAILABILITY, MATHEMATICS, SOL, ROCHE MERE, EAU, TENEUR EN EAU, BORE, SOLUTION DU SOL, MESURE, TENEUR EN EAU DU SOL, MODELE MATHEMATIQUE, DISPONIBILITE D'ELEMENT NUTRITIF, MATHEMATIQUE, SUELO, ELEMENTO PRIMARIO DEL SUELO, AGUA, CONTENIDO DE HUMEDAD, BORO, SOLUCIONES DEL SUELO, MEDICION, CONTENIDO DE AGUA EN EL SUELO, MODELOS MATEMATICOS, ADSORCION, SORCION, DISPONIBILIDAD DE NUTRIENTES, MATEMATICAS, CONCENTRATIONADSORPTIONMOISTURE EQUATIONS, MINE SPOIL, DETERMINATION, CALCULATION, and EQUATIONS
 Abstract

references
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10. Applying the right amount of herbicide [1992]

Langeland, K.A.
 Pub (USA), Oct 1992, (no. 2506) p. 3049.
 Subjects

Weeds, Mathematical and statistical methods, Agricultural machinery and equipment, SOUTH EASTERN STATES (USA), HERBICIDES, APPLICATION RATES, MATHEMATICS, VOLUME, MEASUREMENT, WATER, AQUATIC ENVIRONMENT, SPRAYERS, SOLUTIONS, STANDARDIZING, ETATS DU SUD EST (EU), HERBICIDE, DOSE D'APPLICATION, MATHEMATIQUE, MESURE, EAU, MILIEU AQUATIQUE, PULVERISATEUR, SOLUTION, NORMALISATION, ESTADOS DEL SUDESTE (EUA), HERBICIDAS, DOSIS DE APLICACION, MATEMATICAS, VOLUMEN, MEDICION, AGUA, AMBIENTE ACUATICO, PULVERIZADORES, SOLUCION, NORMALIZACION, CALCULATION, SURFACE AREA, and CALIBRATION
 Abstract

In the series analytic: Training manual for aquatic herbicide applicators in the southeastern United States / edited by K. A. Langeland
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Shibayama, M. and Akiyama, T.
 Remote sensing of environment (USA), Apr 1991, v. 36(1) p. 4553.
 Subjects

Crop husbandry, Mathematical and statistical methods, ORYZA SATIVA, GRAIN, CROP YIELD, MATURITY, CANOPY, SPECTROMETRY, OPTICAL PROPERTIES, MEASUREMENT, MATHEMATICS, STATISTICAL ANALYSIS, REMOTE SENSING, ANALYTICAL METHODS, RENDEMENT DES CULTURES, MATURITE, COUVERT, SPECTROMETRIE, PROPRIETE OPTIQUE, MESURE, MATHEMATIQUE, ANALYSE STATISTIQUE, TELEDETECTION, TECHNIQUE ANALYTIQUE, GRANOS, RENDIMIENTO DE CULTIVOS, MADUREZ, CUBIERTA DE COPAS, ESPECTROMETRIA, PROPIEDADES OPTICAS, MEDICION, MATEMATICAS, ANALISIS ESTADISTICO, TELEDETECCION, TECNICAS ANALITICAS, MULTIPLE LINEAR REGRESSIONS, MATURITY STAGE, SPECTRAL DATA, CALCULATION, MULTIPLE REGRESSION, EQUATIONS, and RADIOMETRY
 Abstract

references
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LeBaron, B.A., Michalsky, J.J., and Perez, R.
 Proceedings of the ... Annual Meeting, American Solar Energy Society, Inc (USA), 1989, p. 433438.
 Subjects

Renewable energy resources, Mathematical and statistical methods, SOLAR ENERGY, ENERGY SOURCES, MEASUREMENT, MATHEMATICS, MODELS, ENERGIE SOLAIRE, SOURCE D'ENERGIE, MESURE, MATHEMATIQUE, MODELE, ENERGIA SOLAR, FUENTE DE ENERGIA, MEDICION, MATEMATICAS, MODELOS, HORIZONTAL DIFFUSE IRRADIANCE, INSTRUMENTATION, CALCULATION, and EQUATIONS
 Abstract

references. Meeting held June 1922, 1989, Denver, Colorado
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