The Integrated Use of Biological and Chemical Control on the Noxious Weed Canada Thistle
MetadataShow full item record
Showing items related by title, author, creator and subject.
Control of mixing in a nonreactive plane shear layer: I. Open-loop control. II. Feedback control.Wiltse, John Michael.; Glezer, Ari; Champagne, Francis H. (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.
Teaching Authority Control [English version] presented at the International Conference Teaching Authority Control. In Proceedings International Conference Authority Control: Definition and International Experiences, FlorenceTaylor, Arlene (2003)The teaching of authority control in schools of library and information science is alive and well, even though it is not perceived this way by some former students. Many professors are fervently attempting to imbue the next generation of librarians with an understanding of the necessity for authority control. Unfortunately, they have to fight the nonunderstanding of colleagues, the lack of course time to be as thorough as desired, and the perception that information technology is uppermost in importance among courses to be taught. However, because the chaotic environment of the Web has brought attention to the need for authority control (e.g., the "semantic web"), we have a new opportunity to teach these concepts to a new generation of information professionals.