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The research focuses on the various methods that could be used in the laboratory to determine the values of production from a model cutter suction dredge. The values of production obtained from different methods are compared to estimate the best value. The tests were conducted in an attempt to pave the way to find spillage from the cutter suction dredge. The development of these methods is useful for evaluating the sediment spillage and residuals during dredging. The more accurate the values of production the more accurate would be the values of spillage. For this purpose, the laboratory dredge carriage and dredge/tow tank located at the Haynes Coastal Engineering Laboratory at Texas A&M University is used. During the summer of 2007 and 2008, the laboratory dredge carriage was used to dredge sand (d50 = 0.27 mm) in the sediment pit that is 7.6 m (25 feet) long, 3.7 m (12 feet) wide and 1.5 m (5 feet) deep. A laser profiler, a model hopper barge attached with pressure gauges, a flowmeter and density gauge aid in determining the production from the laboratory model of the cutter suction dredge were used. The before and after bathymetry measurements using a laser profiling system are used to determine the amount of sediment remaining after dredging. The hopper is instrumented with pressure gauges to measure the amount of sediment contained in the hopper. The laboratory dredge system has a magnetic flowmeter and nuclear density gauge that provide data to calculate the amount of sand delivered to the hopper. The difference between the sand volume from the before and after bathymetry is the amount of sand that is resuspended and subsequently resettles in the dredging area (residual) and the sand that is not picked up by the dredge (spillage). Many issues in laboratory testing were found during the course of testing and solutions were found. The production values are compared with reasoning as to why the differences occur. The results demonstrate the ability and difficulty of measuring the amount of material that is dredged and the amount of spillage and residuals that occurs during dredging.

Field experiments were conducted to determine the impact of threecornered alfalfa hopper, Spissistilus festinus, (Say), in reproductive growth stage soybeans. High densities of threecornered alfalfa hoppers were examined in field cages to understand feeding on soybean. No significant yield losses were observed from threecornered alfalfa hopper feeding during reproductive growth stages. Sweep net efficiency studies were conducted in order to convert the densities used in field cages to a sweep net threshold. Field experiments were also conducted to determine the impact of threecornered alfalfa hopper injury to seedling cotton. Threecornered alfalfa hopper injury to seedling cotton plants impacts individual plant yield, but further research is needed to understand the ability for undamaged cotton plants to compensate for neighboring damaged plants.

A numerical model based on the discrete element (DE) method, for modelling the flow of irregularly shaped, smooth-surfaced particles in a 3-D system is presented. An existing DE program for modelling the contact between spherical particles in periodic space (without real walls or boundaries) was modified to model non-spherical particles in a system with containing walls. The new model was validated against analytical calculations of single particle movements and also experimentally against data from physical experiments using synthetic non-spherical particles at both a particle and bulk scale. It was then used to study the effect of particle shape on the flow behaviour of assemblies of particles with various aspect ratios discharging from a flat-bottomed hopper. The particles were modelled using the Multi-Sphere Method (MSM) which is based on the CSG (Constructive Solid Geometry) technique for construction of complex solids by combining primitive shapes. In this method particle geometry is approximated using overlapping spheres of arbitrary diameter which are fixed in position relative to each other. The contact mechanics and contact detection method are the same as those used for spheres, except that translation and rotation of element spheres are calculated with respect to the motion of the whole particle. Numerical simulations of packing and flow of particles from a flat-bottomed hopper with a range of aspect ratios were performed to investigate the effect of particle shape on packing and flow behaviour of a particulate assembly. It was found that the particle shape influenced both bed structure and flow characteristics such as flow pattern, shear band strength and the occurrence of bridging. The flow of the bed of spherical particles was smoother than the flow of beds of elongated particles in which flow was fluctuating and there was more resistance to shear.

Thesis (M.A.)--Ohio University, August, 2007. / Title from PDF t.p. Includes bibliographical references.

Thesis (M.A.)--University of Wisconsin--Madison, 1971. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

It is hypothesized that Rex Hopper's model for the development of a South American political revolution will apply equally to the development of a social movement which is not a South American political revolution, namely, the Ku Klux Klan. The general purpose of this study was to test the generalizability of Hopper's model.

Threecornered alfalfa hopper, Spissistilus festinus (Say), is a pest of soybean during vegetative and reproductive stages. The primary damage from this pest is girdling of the main stem during vegetative stages and girdling of the petioles during reproductive stages. Previous research determined that yield losses are greater during reproductive stages than vegetative stages. I hypothesized that some reproductive stages are more vulnerable to damage than other stages. I used field cages infested with different pest densities at five reproductive stages of group IV soybean. A greenhouse study compared the injury and damage caused by the adults and nymphs. The field study showed that the threecornered alfalfa hopper did not significantly impact yields at the growth stages studied. Adults preferred to feed on leaf petioles while nymphs fed mostly on stems. Significant yield reduction was noticed at growth stage R4 in the greenhouse due to adult and nymphs compared to control.

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