Digitized by Kansas Correctional Industries

Thesis (M.S.)--Virginia Polytechnic Institute, 1964. / Vita. Abstract. Includes bibliographical references (leaves 65-66). Also available via the Internet.

Call number: LD2668 .T4 1978 K62 / Master of Science

Centrifugal distributors are used extensively for the broadcast application of granular materials such as seed, granular fertilizer, and agricultural chemicals. A major problem with this equipment is nonuniform spreading which frequently results in reduced crop yield. The object of this study is to provide information required for more satisfactory design of spreading equipment. The equations representing the motion of granular particles along the blades of three centrifugal distributor configurations were solved with the aid of an electronic analog computer. Straight, forward and backward-pitched blades and logarithmically spiraled blades, all on flat distributor bases, were studied. Straight radial blades on a concave, cone-shaped base were also investigated. The results of this study were presented in graphs. Displacement, velocity, and departure angle versus the angular rotation of the distributor were plotted for a large range of parameters for each configuration. These variables were expressed in dimensionless form. From a study of the graphs it was noted that of all configurations investigated, the radial-blade arrangement requires the smallest 1·rotational displacement of the distributor to impart a specified velocity to granular material. As the pitch is increased, greater rotation is required. For a given amount of distributor rotation, higher values of the coefficient of friction cause a reduction in both displacement of the particle along the blade and its final velocity. The effect of increasing the ratio of gravity induced friction force to centrifugal force is similar but smaller than the effect of increased friction alone. / Master of Science

Central-hopper spreaders are widely used to apply dry fertilizer. Uniformity of distribution is severely limited by the centrifugal-fan and boom-type distributors used on these spreaders. The purpose of this study was to investigate the application of automatic control principles to an experimental auger-boom-type distributor, To facilitate the use of automatic controls, a distributor of special design was developed, It consisted of an auger conveyor with a U-shaped cross section. Eighteen discharge openings were located on 6-inch centers along its length. Small compartments at the Location of each opening, agitators on the auger flighting, and a control slide along the length of the boom, controlled the discharge from the boom. The control system consisted of a flow-level detector at the outboard end of the boom and a controller and linear actuator to operate the control slide. Basic performance characteristics of the distributor were measured on a laboratory test stand using manual-remote control. Coefficients of variation for discharge patterns along the length of the boom varied from 4.63 to 12.22 percent under various combinations of auger speed, discharge opening size, and boom inclination. Discharge rate was more sensitive to opening size than auger speed. Regression coefficients and tests of independence indicated that discharge rate was not greatly influenced by fertilizer flow level. Minor segregation of dry-blended fertilizers was noted. In tests with automatic control, errors in slide position were corrected. However, slow oscillation of the slide occurred after the initial correction. An improved flow-level detector and controller are needed for acceptable field performance of the system. / Master of Science

The general objective of the research effort reported in this thesis was to develop the knowledge required to optimize the design and operation of solid and semi-solid manure handling and land application equipment. Selected physical and rheological properties of manure products deemed to have an influence on the performances of manure handling and land application equipment were measured and general trends were identified among the measured properties. Relationships were also established between the measured properties and the type of manure as well as its total solids concentration. Field experiments were carried out to evaluate the effects of selected mechanical configurations, operating parameters and product properties on the discharge of manure spreaders. The influence of the type of conveying system (scraper conveyor and system of four augers) and the velocity at which it is operated, the geometry of the holding system and the position of a flow-control gate were all included in the analysis. The discharge rates of the machines as well as the specific energy required by the unloading operations were measured. A numerical modeling method called discrete element method (DEM) was used to create virtual manure, a numerical model of the real product. The measured physical and flow properties were used to develop and validate the virtual manure models. It was found that manure products could successfully be represented in a DE framework and that several parameters defining the contact constitutive model in the DEM had an influence on the behaviour of the virtual products. The DEM was then used to study machine-product interactions taking place in handling and land application equipment. Results from field experiments carried out using various land application equipment were used in the development and validation of the interaction models. The predicted flow rates and power requirements were in good agreement with measured data. The results obtained allowed for a better understanding of the flow of manure products in manure handling and land application equipment. It was found that the constitutive model used for the product influenced the results of the machine-product interactions models. A precision banded applicator under development at the University of Saskatchewan was also modeled. The discharge rate of this equipment is influenced by a number of parameters. The predicted mass distribution across the width of the banded applicator was well correlated to the experimental results. The models developed in this thesis have the potential to become powerful engineering tools for the design of improved machines for the handling and land application of solid and semi-solid manure.

The general objective of the research effort reported in this thesis was to develop the knowledge required to optimize the design and operation of solid and semi-solid manure handling and land application equipment. Selected physical and rheological properties of manure products deemed to have an influence on the performances of manure handling and land application equipment were measured and general trends were identified among the measured properties. Relationships were also established between the measured properties and the type of manure as well as its total solids concentration. Field experiments were carried out to evaluate the effects of selected mechanical configurations, operating parameters and product properties on the discharge of manure spreaders. The influence of the type of conveying system (scraper conveyor and system of four augers) and the velocity at which it is operated, the geometry of the holding system and the position of a flow-control gate were all included in the analysis. The discharge rates of the machines as well as the specific energy required by the unloading operations were measured. A numerical modeling method called discrete element method (DEM) was used to create virtual manure, a numerical model of the real product. The measured physical and flow properties were used to develop and validate the virtual manure models. It was found that manure products could successfully be represented in a DE framework and that several parameters defining the contact constitutive model in the DEM had an influence on the behaviour of the virtual products. The DEM was then used to study machine-product interactions taking place in handling and land application equipment. Results from field experiments carried out using various land application equipment were used in the development and validation of the interaction models. The predicted flow rates and power requirements were in good agreement with measured data. The results obtained allowed for a better understanding of the flow of manure products in manure handling and land application equipment. It was found that the constitutive model used for the product influenced the results of the machine-product interactions models. A precision banded applicator under development at the University of Saskatchewan was also modeled. The discharge rate of this equipment is influenced by a number of parameters. The predicted mass distribution across the width of the banded applicator was well correlated to the experimental results. The models developed in this thesis have the potential to become powerful engineering tools for the design of improved machines for the handling and land application of solid and semi-solid manure.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2004. / Härtill 4 uppsatser.

When provided with spatial niches by growth in static nutrient medium, Pseudomonas fluorescens diversifies through adaptive radiation into several well-defined phenotype classes. One of these classes, named wrinkly spreader (WS) for its morphology on agar medium, forms a biofilm at the air-liquid interface through mutations in one of several loci including the genes wspF and awsX. These genes code for negative regulators of di-guanylate cyclases (DGCs). These DGCs catalyse synthesis of cyclic-di-GMP, a second messenger, overproduction of which effects physiological changes leading to overproduction of a cellulose polymer and the WS phenotype. Intriguingly, a diverse range of wspF mutations leads to diversity both in colony morphology and strain fitness.In this study, I investigate genetic and fitness diversity in wrinkly spreaders with the aim of identifying the causal factors that link genetic diversity and physiological factors with diversity in fitness. I approach the subject from several directions, examining the historical context of genetic diversity in wspF and awsX, distribution of control over output in the Wsp pathway and overall fitness effects of different causal factors. I investigate the genetic basis of wrinkly spreader evolution through generation of a large number of novel WS strains and exploration of the distribution of mutations in the wspF and awsX genes. In combination with this I calculate estimates of the past rates of mutation in these genes, derived from a phylogenetic investigation of a group of orthologues. I examine the response of the Wsp pathway to change in WspF function through a novel computational analysis that is capable of revealing valuable information on control in a biological system based purely on model structure. In addition I show how this analysis can be refined through specification of broad estimates of system parameters, thereby avoiding issues related to over-reliance on specific parameter values. Finally, I investigate the fitness implications of these factors, as well as a variety of others, through assays of fitness in a group of WS strains combined with machine learning analyses of predictive relationships between protein and mutation characteristics and experimentally measured strain fitness, and consider the implications of this analysis in the context of intermediate physiological effects.I find that mutations in the WspF protein that lead to the WS phenotype tend to be located in regions of historically strong conservation, the first time that any such pattern to WS mutations has been identified. Mutations in AwsX, on the other hand, do not fit such a pattern. Computational analysis of the Wsp pathway shows that, regardless of model parameters, pathway output is always more sensitive to changes in methylesterase activity by WspF than to changes in phosphorylation of WspF, which may explain the greater frequency of mutations fixed in vivo seen in the methylesterase domain. Despite these patterns, none of a wide range of mutation and sequence-based biochemical characteristics, including local rates of past evolution and size and position of mutations, exhibited any predictive power over WS fitness. Overall, the findings in this study point towards an essential role for complex pleiotropic effects in strongly modulating the fitness effect of different mutations in wspF.

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