An evaluation of devices for reducing dry bean harvesting losses

Non-Peer ReviewedA preliminary evaluation of three concepts for reducing dry bean harvest (gathering) losses and a more detailed field evaluation of the air-jet guard concept were completed in 1992. Preliminary concept evaluations included the effectiveness of the air reel as a harvest aid, the feasibility of stripping bean pods and seed from the plant, and the effectiveness of three crop lifters under field test conditions. Field testing of the air-jet guard concept was undertaken at six commercial pinto bean sites in Saskatchewan. The air-jet guards did not reduce gathering losses below ten percent, which is considered the minimum acceptable commercial loss level. Losses were variable, but averaged 460 kg/ha (410 lbs/acre). The variability encountered during field testing was investigated by collecting plant samples from each site to determine moisture content. Plant height measurements for the samples were obtained using image processing

Scattering of elastic waves by periodic arrays of spherical bodies

We develop a formalism for the calculation of the frequency band structure of a phononic crystal consisting of non-overlapping elastic spheres, characterized by Lam\'e coefficients which may be complex and frequency dependent, arranged periodically in a host medium with different mass density and Lam\'e coefficients. We view the crystal as a sequence of planes of spheres, parallel to and having the two dimensional periodicity of a given crystallographic plane, and obtain the complex band structure of the infinite crystal associated with this plane. The method allows one to calculate, also, the transmission, reflection, and absorption coefficients for an elastic wave (longitudinal or transverse) incident, at any angle, on a slab of the crystal of finite thickness. We demonstrate the efficiency of the method by applying it to a specific example.Comment: 19 pages, 5 figures, Phys. Rev. B (in press

Seed and fertilizer separation under till-planting system

Non-Peer ReviewedThree prototypes of till-planting unit were developed with which tilling strips, application of fertilizer with separation below the seed, and seeding was accomplished simultaneously. Therefore, the number of field operations required was decreased. The separation between seed and fertilizer was determined for till-planting units in an indoor soil bin facility at three speeds, three depths, three levels of soil compaction, and three levels of soil moisture content. Field tests were also conducted at three speeds and three depths. Results of the soil bin tests indicated that the most favorable condition in terms of high vertical separation between seed and fertilizer occurred with unit two at medium level of soil moisture, low level of soil compaction, 100 mm depth, 3-5 km/h speed of operation. However, in the field tests, the best results were obtained at 125 mm depth and at 3 km/h speed with unit two

Seeding trials with three till-planting units

Non-Peer ReviewedThree prototypes of a single till-planting unit system suitable for Egyptian agriculture were evaluated in clay soil by determining seedling emergence with three crops. Tillplanting units were tested in the field at three speeds and three depths. Crop emergence data were collected on the 7, 14, and 20th days following seeding. Results indicated that the highest values of seedling emergence were obtained with unit two, which was equipped with a Barton angle disc opener, at 3 or 5 km/h speed, and 125 mm depth of operation for pea or corn crops

A model for the energy bands of an "open"-type periodic structure:A periodic viaduct coupled with the half-space

The periodic viaduct in this study was defined as a new kind of periodic structure-the "open"-type periodic structure-for the first time. Knowledge about the energy bands of this kind of "open" periodic viaduct is important for its aseismic design. Using the transfer matrix method and the compliances for the pile foundations, the impedances for the piers were obtained. Based on the Bloch theorem and the transfer matrix method, the nonlinear polynomial eigenvalue equation for the energy bands of the periodic viaduct undergoing in-plane motion was derived using the impedance of the piers. Based on the obtained nonlinear eigenvalue equation, the approximate linear eigenvalue equation for the periodic viaduct was obtained, and numerical results for the energy bands of the periodic viaduct were presented. The numerical results in this paper demonstrate that when the periodic viaduct is undergoing in-plane motion, there exist three lattice waves: the first kind of wave is a highly decaying wave; the second kind of lattice wave can propagate only at some frequency ranges; and the third kind of lattice wave can propagate at most frequencies.No Full Tex