Master of Science / Department of Biological & Agricultural Engineering / Danny H. Rogers / Center pivot irrigation systems are used in crop production across the state of Kansas. The American Society of Agricultural and Biological Engineers (ASABE) standard on uniformity testing of a center pivot system calls for collectors to be used to measure the water depth emitted by the irrigation system. The standard was designed without specially considering the low pressure sprinklers now commonly used on center pivot systems; the recommended collectors may not accurately measure the applied depth from these sprinklers. The collector size effect on measured water depth and measured depth variability was studied for spinning plate, fixed plate, and wobbling plate sprinkler systems. Five different collector sizes (C2 (5.5 cm), C4 (10.0 cm), C6 (14.8 cm), C8 (20.0 cm), and C10 (27.4 cm)) were studied using four 5x5 Latin squares. Each collector’s water depth was measured and statistically analyzed. Two analysis of variance (ANOVA) tests of the collector size effect were reported. Past experimental results were compared to this experiment’s results. The ANOVA for the measured water depth reported no collector size effect for the spinning plate and wobbling plate systems. The ANOVA of the variability of measured depths showed significant differences between collector sizes for the spinning plate system but not for the wobbling plate system. Previous studies of spinning plate and wobbling plate systems reported acceptable variability for all collector sizes. Although some collector sizes measured significantly different mean depths, the numerical difference in mean depths was small. Any studied collector size could be used to measure the water depth of wobbling plate systems, but the C4 collector is ideal. C4 and C6 collectors are ideal for measuring spinning plate systems. Significant differences between measured depths were reported for the fixed plate system. The C10 measured significantly lower water depths than all other collectors, and the C4 collector measured lower depths than the C2 and C8 collectors. The variability of mean depths was similar and high for all collector sizes. Previous experiments also indicated that different collector sizes measured different depths and had high variability of depth measurements for the fixed plate sprinkler systems. The distinct stream pattern provides a challenge for accurately measuring the water depth with these collector sizes; other methods of measuring uniformity should be considered for fixed plate sprinklers.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / In this paper are described the effects that solar and lunar intrusions have on statistical analysis of the data. The NASA ACTS experiment focuses on the 20 and 27 GHz radiometer and beacon. The experiment is currently compiling a database for the attenuation for these different channels. For the year of 1994 our sight obtained 86.5 hours of attenuation and for 1995 our sight obtained 77 hours of attenuation. The total amount of interference time for sun/lunar intrusions for 1994 and 1995 was respectively, 39 hours and 38.5 hours, which is nearly half the total amount of attenuation due to rain and cloud fades. It is clear to see why this data must be taken out for any type of statistical analysis of the data.

A most important aspect of effects of air pollutants on air quality is their impact upon visibility. As far as can be determined this is the first visibility study performed in the UK in which the influence of individual pollutants, the local microclimate and the long range transport of air pollutants have been simultaneously examined over the whole visibility range. Techniques were developed to analyse the influence of the relative humidity on the light scattering efficiency of hygroscopic particles, and to examine their nature and size distributions. A regression model that specifically included the influence of hygroscopic particles and the relative humidity accounted for over 80% of the total variance in visibility, and showed that over 50% of the visibility degradation was due solely to the presence of sulphate particles. The constant of the regression implied a background visibility of over 60km for Teesside, whereas a mean of 12km was recorded. Original results were obtained by examining the relationship of atmospheric stability and thermal structure to visibility and pollutant behaviour using an acoustic sounder. This was used to investigate the conditions created by the local sea breeze which was associated with a substantial proportion of the summertime hazes. Wind rose analysis of the role played by emissions from Teesside industries together with comparisons of visibility levels at nearby locations showed that 20-40% of the light extinction was due to local factors. An airstream categorisation scheme was developed to study the role of long range transport of air pollutants and other influences on visibility. The study was extended across the British Isles to produce convincing evidence of large scale visibility degradation, due principally to sulphates derived from sulphur dioxide emissions, from sources as distant as 1500km. At Teesside the elimination of local air pollutant emissions would result in a significant but limited visibility improvement. A most effective means of controlling visibility degradation would be the reduction of sulphur dioxide emission to the atmosphere on an international scale. The resulting improvement in the visibility levels experienced at Teesside and in the UK in general would be in the order of 100% or more.

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