According to a field test, power transmission efficiency of a tractor drive train varied from 56% to 86% with a mean value of 72.5%. This indicates that a constant-power transmission efficiency model used commonly for the simulation of a power drive train performance may not properly represent the variability that exists. To simulate the actual power transmission efficiency, a drag torque was introduced, and a new model based on the transmission input torque was proposed. The model involves two components, one of which is associated with torque load acting on the wheel axle and the other with the drag torque regardless of the torque load. The power loss by the drag torque, about 61% of the entire power loss occurring during the transporting operation, must be considered in the evaluation of power transmission efficiency of tractor drive trains. The power transmission efficiency predicted by the model agreed well with the experimentally determined power transmission efficiency within a 1.5% difference on average. Although more experimental data may be required before the model can be used practically, a drag torque must be taken into consideration for a better understanding of the power train performance of tractors.

A clear understanding of a model is important for its appropriate use. In this article, eleven watershed scale hydrologic and nonpoint-source pollution models are reviewed: AGNPS, AnnAGNPS, ANSWERS, ANSWERS-Continuous, CASC2D, DWSM, HSPF, KINEROS, MIKE SHE, PRMS, and SWAT. AnnAGNPS, ANSWERS-Continuous, HSPF, and SWAT are continuous simulation models useful for analyzing long-term effects of hydrological changes and watershed management practices, especially agricultural practices. AGNPS, ANSWERS, DWSM, and KINEROS are single rainfall event models useful for analyzing severe actual or design single-event storms and evaluating watershed management practices, especially structural practices. CASC2D, MIKE SHE, and PRMS have both long-term and single-event simulation capabilities. Mathematical bases, the most important and critical elements of these mathematical models, were identified and compiled. In this article, a comprehensive summary of the compilation is presented in tabular form. The flow-governing equations and their solution methods used in each of the eleven models are discussed. The compilation of the mathematical bases of these models would be useful to determine the problems, situations, or conditions for which the models are most suitable, the accuracies and uncertainties expected, their full potential uses and limitations, and directions for their enhancements or new developments. AGNPS, AnnAGNPS, DWSM, HSPF, MIKE SHE, and SWAT were found to have all the three major components (hydrology, sediment, and chemical) applicable to watershed-scale catchments. SWAT is a promising model for continuous simulations in predominantly agricultural watersheds, and HSPF is promising for mixed agricultural and urban watersheds. Among the single-event models, DWSM provides a balance between the simple but approximate and the computationally intensive models and, therefore, is a promising storm event model for agricultural watersheds.

Acetylated starch and 15% cellulose acetate were pretreated with acetone solution, and the pretreated mixture was extruded as a composite. The tensile strength and water resistance were effectively improved due to addition of cellulose acetate as compared to the acetylated starch plastic. The composite had a uniform phase, based on observations using scanning electron microscopy, because the acetylated starch and cellulose acetate combined during pretreatment and later extrusion to form a uniform structure. In addition, the tensile and thermal properties of the composite depended on its equilibrium moisture content in relation to various relative humidity environments. The Halsey equation can be applied to describe the relationship between the equilibrium moisture content and various relative humidity conditions, and the Gordon-Taylor equation was found to predict the glass transition temperature of the composite in various equilibrium moisture content conditions.

Odors are a major result of inadequately sized and mismanaged anaerobic lagoons. However, purple or pink colored lagoons, indicating the presence of phototrophic purple bacteria, are less likely to be an odor nuisance than are non-purple lagoons. Eight swine lagoons were studied to quantify critical parameters thought to allow purple lagoons to be a more reliable odor control alternative. Bacteriochlorophyll a (Bchl a), which indirectly measures the abundance of phototrophic bacteria, was greater in purple lagoons than in non-purple lagoons (P = 0.01). Oxidation-reduction potential (ORP) was less negative for purple lagoons than for non-purple lagoons in both spring (lagoon temperatures of 6.7°C to 8.8°C) and during summer (temperatures of 22°C to 25°C), indicating conditions favoring phototrophism (P = 0.04). Dissolved oxygen levels were near zero and light penetration was minimal in all lagoons. Average sulfide concentrations of all the lagoons were in the range of 1.6 to 6.5 mg/L, which is below the preferred range for purple sulfur bacteria (PSB) growth. Purple lagoons appeared to have lower concentrations of ammonia, alkalinity, chemical oxygen demand, and electrical conductivity among the lagoons studied. Copper and zinc concentrations of all lagoons were not in the range considered to be toxic for anaerobic bacteria. Calculated volatile solids loading rates did not explain differences in Bchl a levels in the lagoons.

An intact core extraction procedure was tested that might be used in the field for real-time prediction of soil nitrates. An extraction solution was pushed through a soil core held between two filters, and an ion-selective field-effect transistor/flow injection analysis (ISFET/FIA) system was used to sense soil nitrates in real time. Laboratory tests were conducted using four soil types and two levels of nitrate concentration, soil moisture, core density, core length, core diameter, and extraction solution flow rate. The extraction solution flow was sampled at the exit face of the core and routed to the ISFET/FIA system. The ISFET output voltage was sampled at 100 Hz. Results of the test indicate that nitrate extraction of the soil cores was successful, and that data descriptors based on response curve peak and slope of the ISFET nitrate response curve might be used in tandem in a real-time prediction system.

Core body temperature (t(b) of market–size male broilers (46 ± 3 d; 2.8 ± 0.1 kg; Ross x Ross breed) was continuously measured by telemetry during acute, 90– to 240–min exposures to 18 thermally challenging conditions. The thermal conditions consisted of 18 factorial combinations of three dry–bulb air temperatures (t(db); 35°C, 38°C, and 41°C), two dewpoint temperatures (t (dp); 19.4°C and 26.1°C), and three air velocities (V; 0.2, 0.7, and 1.2 m s–1). Based on t(b) rise after 90–min exposures to the thermal conditions, a temperature–humidity–velocity index (THVI) was developed to delineate the synergistic effects of the thermal components on the birds, having the form of THVI = (0.85t(db) + 0.15t(wb)) x V–0.058, where t(wb) = wet–bulb temperature. The homeostasis state of the bird was classified as normal, alert, danger, or emergency, which correspond to a t(b) rise threshold of 1.0°C, 2.5°C, 4.0°C, or >4.0°C, respectively. These different homeostasis states were functionally and graphically expressed in terms of THVI and exposure time. For example, if the broilers were acutely exposed to a thermal condition for 90 min, then the THVI threshold for the normal, alert, danger, and emergency state would be about 35°C, 38°C, 40°C, and >40°C, respectively. If the exposure duration was increased to 120 min, the THVI threshold would drop to 34°C, 37°C, 38°C, and >38°C, respectively. The results of this study serve as a scientific basis for making management decisions and risk assessment associated with market–size broiler production and handling under thermally challenging conditions.

An experimental vacuum coating system was developed. Liquid vitamin was sprayed into pellets of different diameters under vacuum. A special mixing paddle was developed and incorporated into the coating chamber to improve the mixing uniformity. The effects of vacuum pressure and spray pressure on the mixing uniformity were studied using the methylene violet tracing method. A proper spray pressure needs to be selected to obtain the best mixing uniformity. No effect of vacuum pressure on the mixing uniformity among pellets was observed. The effects of liquid dosing, vacuum release time, and pellet size on the gradient of liquid concentration between the central and the outer region of pellet were studied. Decreasing the vacuum release time reduced the gradient of liquid concentration. Increasing liquid dosing caused a decrease of the gradient of liquid concentration. The smaller the pellets, the smaller the gradient of liquid concentration.

The penetration of a sprayer air jet into an apple tree canopy was measured. An air-assisted sprayer with two vertical, cross-flow fan units, moving past the tree (without spraying liquid) provided the air jet. Treatments included three fan positions (fans vertical [0/0], top fan inclined 20° [20/0], and top fan inclined 15° with bottom fan inclined 12° [15/12]), three travel speeds (4.8, 6.4, and 8 km/h), two fan speeds (18 and 24.5 r/s), and three canopy conditions (south to north [SNT], north to south [NST], and north to south without a tree [NSO]). Vertical air velocities profiles were measured with hot-film anemometers in the center of the tree row and in the drive lane beyond the tree row. Maximum measured velocity, velocity integrated over the time of the air velocity pulse, air power (velocity cubed), and integrated power over the velocity pulse were measured or computed. The passing air jet produced distinct velocity pulses at elevations of 0.6 (except for [15/12]), 1.2, and 1.8 m within the tree and at elevations 0.6 and 1.8 m in the center of the drive row beyond the tree. Only fan position [0/0] produced distinct velocity pulses at the 3.0 m elevation, and no treatment produced visible pulses at the 4.2 m elevation. Fan positions had great and significant influence on air velocities inside tree canopies. At the 1.8 m elevation in the tree center, converging air jets [15/12] produced the highest velocities, followed by the [20/0] treatment. The plane jet [0/0] produced the lowest velocities at this position. Fan position had little significant difference on air velocities at the 1.2 m elevation in the tree. Fan speed had great and significant influence on air velocities. Travel speed produced little difference among treatments when maximum velocities were considered; however, there were greater differences when integrated velocities were considered. For the canopy conditions, greater velocities were measured for the treatments without canopy; however, velocities for the SNT treatment were nearly as great. Velocities for NST treatments were significantly less. This illustrates the effect of velocity sensor position (local canopy differences) on measured velocities. In general, converging air jets, low travel speed, and high fan output power improved penetration velocity and power into the tree canopy.

A near-infrared (NIR) and mid-infrared (MIR) dual-camera imaging approach for online apple stem-end/calyx detection is presented in this article. How to distinguish the stem-end/calyx from a true defect is a persistent problem in apple defect sorting systems. In a single-camera NIR approach, the stem-end/calyx of an apple is usually confused with true defects and is often mistakenly sorted. In order to solve this problem, a dual-camera NIR/MIR imaging method was developed. The MIR camera can identify only the stem-end/calyx parts of the fruit, while the NIR camera can identify both the stem-end/calyx portions and the true defects on the apple. A fast algorithm has been developed to process the NIR and MIR images. Online test results show that a 100% recognition rate for good apples and a 92% recognition rate for defective apples were achieved using this method. The dual-camera imaging system has great potential for reliable online sorting of apples for defects.

Moisture content is an important property to be managed in the harvesting, storage, marketing, and processing of dates. Because the determination of moisture content is usually destructive, laborious, and time–consuming, this article introduces a quick method for measuring date moisture content using a simple and inexpensive electronic circuit. The developed circuit senses the voltage response (output voltage) as the whole date is held in contact between the moisture sensors. This circuit is a modification of a Colpitts oscillator using a 2N743 transistor. Four types of dates (Sokary, Nabtit–Aly, Rawthana, and Om Al–Khashab) were collected and maintained in the refrigerator until the time of measurement. The vacuum oven method was used to calibrate the circuit performance; about 5–g samples of dates were placed in the oven for 48 h at 65.C under a vacuum pressure of 762 mm Hg. The relationship between the measured voltage response and the moisture content of dates was developed. The coefficient of determination (R2) was found to be 0.95. This new technique is rapid, accurate, and simple. Thus, it can be recommended as a quick method for measuring date moisture content.