Thesis (M.S.)--Ohio University, March, 1989. / Title from PDF t.p.

Thesis (M.S.)--Ohio University, August, 1992. / Title from PDF t.p.

Thesis (Ph. D.)--University of Florida, 2005. / Title from title page of source document. Document formatted into pages; contains 277 pages. Includes vita. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2007. / Full text release at OhioLINK's ETD Center delayed at author's request

Thesis (Ph. D.)--Ohio State University, 1987. / Includes vita. Includes bibliographical references (leaves 399-417). Available online via OhioLINK's ETD Center.

The seasonality of avocado production leads to over-supplied markets during peak periods followed by shortages of fruit during other periods. The production of out of season avocado fruit was seen by Westfalia Estate as an opportunity to increase their profits. As the Estate is committed to supply Woolworths with fruit for 12 months of the year, this study was undertaken to investigate the production of out of season avocado fruit through chemical and physical manipulation of trees. Gibberellins (GA) are known to have many regulatory functions on various processes in plants, including flowering. Trials were conducted during 1999 in which the effect of gibberellic acid (G3) sprays on flowering of avocado was evaluated. A microscopic study revealed that the first signs of inflorescence development were already present in 'Hass' buds sampled in mid March. Secondary inflorescence axis meristems could be seen as small axillary meristems in the axils of the inner terminal bud bracts. GAJ sprays delayed the development of these secondary inflorescence axis meristems. In a more comprehensive study, the effect of single and multiple GAJ treatments (50 and 250 mg.L-1) on flowering of potted 'Fuerte', 'Hass' and 'Ryan' trees was evaluated. Depending on the timing of the application, single GA3 treatments did not affect (February), delayed (mid March and early April) or enhanced (late April and May) inflorescence development of avocado trees. However, none of these effects were significant. Multiple GA3 treatments applied over a four month period significantly inhibited inflorescence development. The effect on inflorescence development tended to increase with increasing number of sprays applied and with an increase in the concentration used. Timing of GA3 sprays proved to be crucial and determined what kind of effect was obtained. In order to inhibit flowering reliably, the first application must be applied before floral initiation and the last application during advanced stages of inflorescence development. In another trial, 'Fuerte' trees were de-flowered during the normal flowering period (August/September 1999) by the application of an Ethrel® spray. Three months after the de-flowering treatment, out of season flowering was induced by cincturing the trees. Out of season flowering and fruit set were observed in January/February 2000. Normal season fruit were harvested in April 2000 at a moisture content of 70%, whereas the out of season fruit were harvested in November 2000 at a moisture content of 62%. Although, the out of season yield (17.7 kg.tree-1) was significantly lower than the normal season yield (45.8 kg. tree-1), the extremely good prices obtained out of season makes this a highly profitable venture. Out of season fruit quality proved to be equal to or even better than the normal season fruit quality. The de-flowering treatment resulted in unnecessary stress being inflicted onto the trees and may be a limiting factor in the long term sustainability of out of season fruit production. In this regard, the use of G3 sprays to inhibit flowering during the normal season may eliminate the problems associated with the de-flowering treatment. / Dissertation (MSc (Agric) Horticultural Science)--University of Pretoria, 2005. / Plant Production and Soil Science / unrestricted

The general production control practices of the shoe industry are basically similar to the production planning of other small businesses in the consumer field. This study will reduce to concrete form the types of production control used by the shoe industry of Texas.

No description available.

published_or_final_version / Industrial and Manufacturing Systems Engineering / Doctoral / Doctor of Philosophy

This dissertation addresses the "multi-machine carryover sequence dependent group-scheduling problem with anticipatory setups," which arises in the printed circuit board (PCB) manufacturing. Typically, in PCB manufacturing different board types requiring similar components are grouped together to reduce setup times and increase throughput. The challenge is to determine the sequence of board groups as well as the sequence of individual board types within each group. The two separate objectives considered are minimizing the makespan and minimizing the mean flow time. In order to quickly solve the problem with each of the two objectives, highly effective metasearch heuristic algorithms based on the concept known as tabu search are developed. Advanced features of tabu search, such as the long-term memory function in order to intensify/diversify the search and variable tabu-list sizes, are utilized in the proposed heuristics. In the absence of knowing the actual optimal solutions, another important challenge is to assess the quality of the solutions identified by the proposed metaheuristics. For that purpose, methods that identify strong lower bounds both on the optimal makespan and the optimal mean flow time are proposed. The quality of a heuristic solution is then quantified as its percentage deviation from the lower bound. Based on the minimum possible setup times, this dissertation develops a lower bounding procedure, called procedure Minsetup, that is capable of identifying tight lower bounds. Even tighter lower bounds are identified using a mathematical programming decomposition approach. Novel mathematical programming formulations are developed and a branch-and-price (B&P) algorithm is proposed and implemented. A Dantzig-Wolfe reformulation of the problem that enables applying a column generation algorithm to solve the linear programming relaxation of the master problem is presented. Single-machine subproblems are designed to identify new columns if and when necessary. To enhance the efficiency of the algorithm, approximation algorithms are developed to solve the subproblems. Effective branching rules partition the solution space of the problem at a node where the solution is fractional. In order to alleviate the slow convergence of the column generation process at each node, a stabilizing technique is developed. Finally, several implementation issues such as constructing a feasible initial master problem, column management, and search strategy, are addressed. The results of a carefully designed computational experiment for both low-mix high-volume and high-mix low-volume production environments confirm the high performance of tabu search algorithms in identifying extremely good quality solutions with respect to the proposed lower bounds. / Graduation date: 2006