Showing papers by "Sidney A. Thompson published in 2006"

Fine Particle Measurements Inside and Outside Tunnel-Ventilated Broiler Houses

Abstract: Emissions from animal feeding operations have become a growing concern. Although many studies describe occupational exposures and exhaust concentrations associated with animal facilities, very little information has been provided about the ambient air around the houses. This study investigates real-time and primarily 24-h time-integrated levels of particulate matter ≤2.5 μm in diameter inside and outside (up to 500 ft from the house) of commercial tunnel-ventilated broiler houses on a farm in northeast Georgia. None of the 24-h particulate matter measures collected when the houses were tunnel ventilated exceeded the Environmental Protection Agency's 24-h National Ambient Air Quality Standard of 65 μg/m3.

In-House Composting of Layer Manure in a High-Rise, Tunnel-Ventilated Commercial Layer House During an Egg Production Cycle

Abstract: In-house composting has the potential to improve the viability of the high-rise house for commercial egg production by producing a value-added product from the manure without requiring a separate composting facility. The feasibility of in-house composting depends in part on having the ability to handle the manure mass that accumulates over an extended period. This field study showed that in-house composting is possible for the length of an egg production cycle. Beginning with windrows of a carbon source, fresh pine sawdust or shredded yard waste, upon which manure fell from the cage rows above, compost volume grew rapidly in the first few weeks, but slowed after composting activity peaked, as indicated by compost temperatures. In cold weather, when ventilation rates were low, compost remixing temporarily produced high ammonia levels in the house, but ammonia levels at other times were comparable to or lower than those in an undisturbed house. The final compost was friable and nutrient-rich, although the handling quality of the yard waste compost was reduced by persistence of elongated woody pieces of the original carbon source. The ability to access the manure storage area of a high-rise house over a cycle of production gives potential to deliver manure amendments to improve nitrogen retention in the compost, which would have the effect of improving its fertilizer value and reducing ammonia emission from the house.

Vertical Loads Due to Wheat on Obstructions Located on the Floor of a Model Bin

Abstract: Tests were conducted in a model grain bin to evaluate the vertical loads acting on differently shaped obstructions embedded in wheat during filling, detention, and discharge. The bin had corrugated galvanized steel walls with a 1.83 m diameter and a flat bottom. All tests were conducted in a bin that was centrically loaded and unloaded. Three differently shaped obstructions (disc, cone, and cylinder) were tested; each had a circular base equivalent to 6% of the bin floor area. The obstructions were supported in the bin using a three-legged support structure. Each leg of the support structure rested on a load cell attached to the bin floor. Tests were conducted with the obstructions located in the bin at three different eccentricity ratios (ratio of the centerline of the obstruction to the bin radius, ER = 0, 0.5, and 0.67) and at two different grain heights (height of grain depth to bin diameter ratio, H/D = 0.4 and 0.75). The radial distribution of vertical pressures in the bin varied, with the highest pressure in the center of the bin and the lowest at the bin wall. The largest vertical load on the disc and cone obstructions was measured at the end of filling. The largest load on the cylindrical obstruction was observed immediately after the initiation of bin discharge. At the end of filling and detention, the vertical loads on the disc, cone, and cylinder were 4.8, 3.7, and 4.9 kN, respectively, for obstructions located at ER = 0 and H/D = 0.4. At a location closest to the bin wall (ER = 0.67), the vertical loading on the disc, cone, and cylinder were 4.4, 3.4, and 4.4 kN, respectively. The greatest difference in vertical loading between the location and type of obstruction was on the order of 50%. Bending moments were also observed to act on these obstructions. Bending moments at ER = 0.67 were much larger than those determined at ER = 0.5. For the disc and cone, moments at ER = 0.67 were three times as large as those determined for tests conducted at ER = 0.0. At the onset of discharge, the vertical loading on both the disc and cone decreased significantly, while the vertical loading on the cylinder increased significantly. Recommendations based on Eurocode I were used to predict the vertical loading on the disc and cylinder embedded in grain. This technique did an adequate job of predicting the maximum loading on both obstructions within the bin; however, it did not take into account the effect of unloading on the obstruction forces.