T. C. Bridges

Thin-Layer Drying Model for Soybeans

ABSTRACT RELATIVELY little research has been reported in the literature on the thin-layer drying characteristics of soybeans in comparison to that published on corn and other cereal grains. Lee (1959) investigated the thin-layer drying of rewetted soybeans and fitted his data to a diffu-sion-type drying model. He employed the concept of a dynamic equilibrium moisture content and presented graphical techniques for determining the constants in his drying model as a function of drying temperature, relative humidity, initial moisture content, and soybean size. Alam (1972) used an equilibrium model to simulate the drying of soybeans with natural air at relatively low air flow rates (1-2 mVmin-tonne). Overhults et al. (1973) studied the thin-layer drying characteristics of soybeans with initial moisture contents ranging from 20 percent* to 33 percent and drying air temperatures from 38 ° to 140 °C. Dew point tempera-ture was held constant at 8 °C. A modified form of Pages drying equation (Page, 1949) was employed to describe the experimental data. This equation was of the form.

AN OPTIMAL MISTING METHOD FOR COOLING LIVESTOCK HOUSING

ABSTRACT The stress ratio (K) used in Janssens equation for calculating grain pressure was determined for soybeans by four different methods. Static stresses were measured in a 0.91 m diameter x 2.743 m high model galvanized smooth steel bin. The four methods were: 1) measure vertical loads on the floor and wall separately; 2) measure vertical and hoop strains in the bin walls with six, two-element, rosette gages evenly spaced around the bin circumference at 15.2 cm above floor, 3) measure horizontal and shear loads at the bin wall with three ring load cells placed at different heights on the model bin wall (15.2, 61.0, and 106.7 cm above the floor); and 4) directly measure vertical and horizontal stresses within the grain mass using in-mass transducers (IMTs) at four different heights at the bin center (15.2, 61.0, 106.7, and 152.4 cm above the floor). A total of 18 replications were performed. For grain depths less than H/D = 2.8, K-ratio decreased with increasing depth of soybeans. At depths about three times the bin diameter (U/D = 3.0), the K-ratio approached a constant value that may be approximated by KQ = 1 - sin p, where p is the angle of internal friction of grain to grain.

Modeling the Physiological Growth of Swine Part I: Model Logic and Growth Concepts

This article is Part 1 in a series of three articles describing the computer model (NCPIG) that was developed to simulate the physiological growth of swine. The methods and techniques used to simulate the interaction of feed intake and the various metabolic processes for the growing swine are presented. These processes include nutrient digestion, nutrient storage in the blood, body maintenance, lean mass growth, excess fat growth, and waste and urine production. Animal heat production and thermal energy balance is described in Part 3 of this series. The model was shown to provide reasonable predictions of the empty body weights used to develop the supporting body component growth curves

ECONOMIC EVALUATION OF MISTING-COOLING SYSTEMS FOR GROWING/FINISHING SWINE THROUGH MODELING

The economics of investing in a misting-cooling system for growing-finishing swine [20-107 kg, (44-236 lb)] were evaluated for central Kentucky summer environments using the NC-204 swine growth model (Bridges et al., 1992a,b; Usry et al., 1992). The economic returns to misting were compared for different weather years (1995 and 1983) and two initial starting dates of 15 June and 5 July. The results of the simulation model found that for all instances the use of a misting-cooling system reduced the time of growth to market and produced a pig with less backfat. Depending on the potential for evaporative cooling in the weather year and the starting date in the facility, the economic returns for the misting-cooling system varied from

Modeling the Physiological Growth of Swine Part III: Heat Production and Interaction With Environment

0.49 per pig in 1995 to

GI TRACT SIMULATION MODEL OF THE GROWING PIG

3.40 per pig in 1983.

Dynamic Simulation of Animal Growth and Reproduction

Part 3 of this series presents the development and validation of the relationships used in the NCPIG computer model to simulate heat production and interaction with the thermal environment of growing swine. The model was developed to simulate transient, diurnal energy flows for growing pigs considering metabolic heat production, sensible and radiant heat gains and losses, latent heat losses and heat storage within the animal body. The relationships used in the model are described and the results of comparisons between predicted heat production and observed data for individually housed pigs are presented. The predicted and observed data were for crossbred gilts ranging in weight from 30-100 kg and for three levels of environmental temperature: lower critical temperature (LCT), LCT+58 C, and LCT-58 C. The simulated heat production values for the LCT experiment were within the observed mean minus one standard deviation while those for the LCT+5 and LCT-5 treatments were approximately one standard deviation above and below their respective means.

Seed coat damage in thin-layer drying of soybeans.

ABSTRACT A physiological computer model of digesta flow (DIGEST) in the GI tract of the growing pig is discussed. Dry matter, as well as liquid flow, is simulated through three compartments of the GI tract (stomach, small intestine and cecum-colon). Absorption of material (solid and liquid) is also simulated by the model. The calibration procedure, sensitivity analysis and validation results are also presented.

Slip-stick Frictional Behavior of Wheat on Galvanized Steel

ABSTRACT A rather unique systems analysis approach has been made to simulate the utilization of dry matter by ruminant animals, and the natural breeding and reproduction process within a herd. Physiological factors occurring over time and the time related effects of these factors are simulated.

A Simulation Model for Assessing Alternate Strategies for Beef Production with Land, Energy and Economic Constraints

ABSTRACT THIN-LAYER drying experiments have been carried out to establish a clearer understanding of how dry-ing conditions affect the development of seed coat and cotyledon cracks in soybeans dried with heated air. Dry-ing rate was found to be highly dependent on initial moisture content and the relative humidity of the drying air.