BRUSH CONTROL, FORAGE PRODUCTION AND TEBUTHIURON RESIDUES IN SOILS AND PLANTS AT FOUR CREOSOTEBUSH (LARREA TRIDENTATA) SITES IN THE CHIHUAHUAN AND SONORAN DESERTS.
KeywordsBrush -- Control -- Arizona -- Pima County.
Brush -- Control -- Mexico -- Chihuahua.
Brush -- Control -- Mexico -- Chihuahua (State)
Creosote bush -- Control -- Arizona -- Pima County.
Creosote bush -- Control -- Mexico -- Chihuahua.
Creosote bush -- Control -- Mexico -- Chihuahua (State)
Forage plants -- Arizona -- Pima County.
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PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Degree ProgramGraduate College
Renewable Natural Resources
Degree GrantorUniversity of Arizona
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Control of mixing in a nonreactive plane shear layer: I. Open-loop control. II. Feedback control.Wiltse, John Michael. (The University of Arizona., 1993)A control system for the enhancement and regulation of mixing in a nonreactive plane shear layer has been developed in a two-stream closed-return water facility. Mixing of a passive scalar is estimated using a thermal analog in which the two streams have uniform, steady temperatures differing by 3°C. The position of the temperature interface between the two streams is measured in the plane of its cross stream Schlieren image by an optical sensor which is placed upstream of the rollup of the primary vortices. Control is effected via an array of surface heaters flush-mounted on the flow partition and cross-stream temperature distributions are measured with a resolution of 0.03°C using an array of closely-spaced cold wire sensors. In closed-loop experiments the output from the interface position sensor is fed back to the surface heaters. A transfer function is used to predict the effect of feedback on the interface motion. The dependence of various measures of mixing on the feedback gain k and the total delay time Δ between the actuators and the sensors is studied. The feedback gain k is adaptively modified to maximize mixing at a given streamwise station. These experiments indicate that feedback control of the motion of the temperature interface can be used for controlling the nominally 2D entrainment by the primary vortices and thus enhancing mixing.
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