Nathan G. Johnson

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Recent advancements in digital imaging systems have provided means for greater definition in photography. These technologies have brought high-resolution pictures that show greater clarity and allow for a ‘deeper’ analysis of information. This occurs through decreased distortion that may have otherwise resulted in features becoming ‘blurred’ or ‘hidden’.(More)
This paper uses the Hybrid Optimization Model for Electric Renewables (HOMER) to model a domestic power system for a single family household in Boulder, Colorado. HOMER has been used to model systems as large as the aggregate electric grid in Boulder and as small as individual premises-based power systems at the point of energy use. Premisesbased power(More)
The high number of mates of honeybee queens has lead to the proposal of several adaptive explanations. The competing hypotheses to explain multiple mating in honeybees and some other social insects have been mostly evaluated empirically with comprehensive theoretical analysis lacking behind. We report on the mathematical analysis of the diploid drone(More)
Research has been undertaken to explore the possibility of using smart materials for the actuation of screw-in cartridge valves. Four types were considered and a piezoelectric (PZT) stack was selected as the most appropriate actuator. The concept of a spool valve piloted by a PZT valve was chosen for investigation. A mathematical model of a hydraulic system(More)
The over- or under-prediction of risk in moderately contaminated sediments can have a large impact on the nature of applied management strategies since concentrations border on being toxic or not toxic. Project managers should give significant consideration as to how moderate levels of contaminants in native sediments and dredged material used for(More)
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