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Lawrence, K.C., Windham, W.R., and Nelson, S.O.
 Transactions of the ASAE (USA), JanFeb 1998, v. 41(1) p. 135142.
 Subjects

Food composition, Feed composition, Mathematical and statistical methods, WHEATS, GRAIN, MOISTURE CONTENT, MEASUREMENT, DIELECTRIC PROPERTIES, DENSITY, RADIATION, SPECTROMETRY, MATHEMATICS, STATISTICAL METHODS, BLE, TENEUR EN EAU, MESURE, PROPRIETE DIELECTRIQUE, DENSITE, SPECTROMETRIE, MATHEMATIQUE, METHODE STATISTIQUE, TRIGO, GRANOS, CONTENIDO DE HUMEDAD, MEDICION, PROPIEDADES DIELECTRICAS, DENSIDAD, RADIACION, ESPECTROMETRIA, MATEMATICAS, METODOS ESTADISTICOS, DENSITYINDEPENDENT MEASUREMENT, BULK DENSITY, RADIO WAVES, SPECTRAL ANALYSIS, ACCURACY, EQUATIONS, MULTIVARIATE ANALYSIS, and PRINCIPAL COMPONENT ANALYSIS
 Abstract

references
A technique is presented for rapidly determining the moisture content of hard red winter wheat, Triticum aestivum L., independent of grain bulk density. Complex admittance measurements from 1 to 110 MHz on bulk wheat samples were collected for predicting moisture contents ranging from about 9% to 20%, wet basis, in samples with densities ranging from 0.620 to 0.790 g/cm3. The data were transformed to densityindependent function (DIF) values, and multivariate analysis was used to eliminate spectral and statistical outliers. Principal component analysis was also used to determine the optimum frequencies for predicting moisture content with the DIF values. Partial leastsquares regression was then used to develop a calibration based on measurements at three frequencies of about 2, 25, and 80 MHz. Calibration was performed with 47 wheat samples representing six cultivars harvested in 1991 and 1992 with a standard error of cross validation of 0.34% moisture content, and validation was tested on 146 different samples from the same cultivars. Predicted moisture contents compared well with values determined by air oven drying with a standard error of performance of 0.39% moisture content and a bias of +0.03%
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Lawrence, K.C., Nelson, S.O., and Bartley, P.G. Jr.
 Transactions of the ASAE (USA), JanFeb 1998, v. 41(1) p. 143150.
 Subjects

Food composition, Feed composition, Mathematical and statistical methods, WHEATS, GRAIN, DIELECTRIC PROPERTIES, MEASUREMENT, RADIATION, SENSORS, DESIGN, MATHEMATICS, MATHEMATICAL MODELS, BLE, PROPRIETE DIELECTRIQUE, MESURE, CAPTEUR, CONCEPTION, MATHEMATIQUE, MODELE MATHEMATIQUE, TRIGO, GRANOS, PROPIEDADES DIELECTRICAS, MEDICION, RADIACION, SENSORES, DISENO, MATEMATICAS, MODELOS MATEMATICOS, RADIO WAVES, FREQUENCY, and EQUATIONS
 Abstract

references
A system for measuring the dielectric properties of cereal grains from 1 to 350 MHz with a coaxial sample holder is presented. Several polar alcohols were used to calibrate and verify permittivity measurements obtained with a signalflow graph model from the full twoport Sparameter measurements. At the lowest frequencies (125 MHz), where the phase measurements are less accurate, a lumped parameter model was used for the dielectric loss factor measurements. The system was calibrated with measurements on air and decanol and verified with measurements on octanol, hexanol, and pentanol. The standard error for the polar alcohols used for verification was 2.3% for the dielectric constant and 7.6% for the dielectric loss factor. Although measurements were taken on static samples, the sample holder is designed to accommodate flowing grain. Dielectric properties measurements at 25 degrees C were taken on four hard red winter wheat cultivars ranging in moisture content from about 9% to 21% with bulk densities varying from 0.66 to 0.83 g/cm3. Most of the data agreed with measurements reported in the literature
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Yang, C., Shropshire, G.J., and Peterson, C.L.
 Transactions of the ASAE (USA), NovDec 1997, v. 40(6) p. 17691776.
 Subjects

Meteorology and climatology, Agricultural machinery and equipment, Mathematical and statistical methods, FIELDS, TOPOGRAPHY, MEASUREMENT, EQUIPMENT, MICROCOMPUTERS, GEOGRAPHICAL INFORMATION SYSTEMS, COMBINE HARVESTERS, TRACTORS, MATHEMATICS, CHAMP, TOPOGRAPHIE, MESURE, MATERIEL, MICROORDINATEUR, SYSTEME D'INFORMATION GEOGRAPHIQUE, MOISSONNEUSE BATTEUSE, TRACTEUR, MATHEMATIQUE, CAMPO, TOPOGRAFIA, MEDICION, EQUIPO, MICROCOMPUTADOR, SISTEMAS DE INFORMACION GEOGRAFICA, SEGADORASTRILLADORAS, TRACTORES, MATEMATICAS, GLOBAL POSITIONING SYSTEMS, ACCURACY, and PORTABLE INSTRUMENTS
 Abstract

references
Slope and aspect are two important topographic attributes affecting crop production. In order to quantitatively describe the influence of slope and aspect, two electronic inclinometers and a GPS (Global Positioning System) receiver were installed on two combines and a tractor to measure ground slope and aspect under actual field working conditions. A computerized data acquisition system was used to sample angle data and position information. The general case of a vehicle moving on ground having both direct and cross slopes was examined and algorithms were developed to calculate ground slope and aspect based on the angles measured by the inclinometers and the position data from GPS. Field tests showed the system performed well under severe conditions. A comparison between the calculated slope and aspect values and those derived from a contour map showed that the procedures and algorithms presented in this article were correct and accurate
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4. A note on sampling errors in the rainfall and runoff data collected using tipping bucket technology [1997]

Yu, B., Ciesiolka, C.A.A., Rose, C.W., and Coughlan, K.J.
 Transactions of the ASAE (USA), SepOct 1997, v. 40(5) p. 13051309.
 Subjects

Soil chemistry and physics, Meteorology and climatology, Mathematical and statistical methods, RUNOFF, RAIN, SAMPLING, MEASUREMENT, EQUIPMENT, DESIGN, MATHEMATICS, RUISSELLEMENT, PLUIE, ECHANTILLONNAGE, MESURE, MATERIEL, CONCEPTION, MATHEMATIQUE, ESCORRENTIA, LLUVIA, MUESTREO, MEDICION, EQUIPO, DISENO, MATEMATICAS, and EQUATIONS
 Abstract

ref.
Data precision for rainfall intensity and runoff rate using tipping bucket technology is controlled by the bucket volume, V, the catchment area, A, and the sampling interval, t. The maximum absolute error is less than V(A delta t)(1) and the standard error is given by V(square root of 6 A delta t)(1), both of which are independent of the magnitude of rainfall intensity and runoff rate being measured. Therefore, the relative error can be quite large during events with low rainfall intensity or runoff rate. The magnitude of the sampling error given above can be used to assist in experiment and equipment design and in data analysis
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