EVALUATION OF THE PERFORMANCE OF FLOCCULATION TO ENHANCE SEDIMENT TRAP EFFICIENCY

Weathered sandstone materials have seen increased use in reclamation due to the wide-spread adoption of the Forest Reclamation Approach (FRA) in Appalachia. Runoff from these newly FRA reclaimed sites has the potential to adversely impact aquatic environments without fine sediment retention. To reduce the size and capital investment of settling ponds, flocculant utilization was investigated. Preliminary jar tests were conducted using composite weathered mine spoil samples acquired from a surface coal mine in eastern Kentucky. Four flocculants from the Magnafloc family of products were investigated during the initial screening-level testing. Experiments were conducted at three initial sediment concentrations (500 mg/L, 2,500 mg/L and 5,000 mg/L). A nonionic flocculant, Magnafloc 351, performed best, reducing total suspended sediment to below 50 mg/L. Large scale experiments confirmed that Magnafloc 351 was effective in reducing sediment concentrations. Jar tests were expanded to determine age and environmental effects on a Magnafloc 351 solution. Magnafloc 351 performance was slightly reduced after storage in a controlled building environment for 30 days and significantly decreased after 120 days. Magnafloc 351 solution exposed to UV and high heat (111°F) was ineffective after 30 days, while storage at 4°F and 36°F for 30 days did not adversely influence performance

Visual search and VDUS

This wide-ranging study explored various parameters of visual search in relation to computer screen displays. Its ultimate goal was to help identify factors which could result in improvements in commercially available displays within the 'real world’. Those improvements are generally reflected in suggestions for enhancing efficiency of locatabolity of information through an acknowledgement of the visual and cognitive factors involved. The thesis commenced by introducing an ergonomics approach to the presentation of information on VDUs. Memory load and attention were discussed. In the second chapter, literature on general and theoretical aspects of visual search (with particular regard for VDUs) was reviewed. As an experimental starting point, three studies were conducted involving locating a target within arrays of varying configurations. A model concerning visual lobes was proposed. Two text-editing studies were then detailed showing superior user performances where conspicuity and the potential for peripheral vision are enhanced. Relevant eye movement data was combined with a keystroke analysis derived from an automated protocol analyser. Results of a further search task showed icons to be more quickly located within an array than textual material. Precise scan paths were then recorded and analyses suggested greater systematicity of search strategies for complex items. This led on to a relatively 'pure' search study involving materials of varying spatial frequencies. Results were discussed in terms of verbal material generally being of higher spatial frequencies and how the ease of resolution and greater cues available in peripheral vision can result in items being accessed more directly. In the final (relatively applied) study, differences in eye movement indices were found across various fonts used. One main conclusion was that eye movement monitoring was a valuable technique within the visual search/VDU research area in illuminating precise details of performance which otherwise, at best, could only be inferred

Introduction of formal assessment criteria into Anatomy Honours dissection exercises

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