Experimental determination of pressures and velocities in plant xylem

This study reports on the experimental modeling of fluid flow in plant xylem. Three experiments were conducted to determine pressures and velocities in the conducting vessels of the xylem portion of a plant using corn syrup as the working fluid and Plexiglas tubing as the test section. The first experiment was performed using a straight duct to model the flow in a xylem vessel without any obstructions. The second experiment was performed using a 5-pore perforation plate as an obstruction in a straight duct. This perforation plate was kept at an angle of 23 degrees relative to the vessel axis to match the fluid flow through a perforation plate found in the plant species Liriodendron tulipifera. In the third experiment, a 20-pore perforation plate was used to match the vessels of Liquidambar styraciflua. This plate was placed at an angle of 12.7 degRees To verify the flow behavior, the experimental results were compared with a numerical simulation using NEKTON, a computational fluid dynamics package. Experimental results and the numerical results agreed with each other. In the experiments involving the 20-pore perforation plate, the average loss coefficient was 86,300 over the range {dollar}\rm 0.2 \u3c Re\sb{D} \u3c 0.5.{dollar} The results of this work also consisted of plots of streamlines, velocity distributions, and pressure within the xylem

Piloted simulation study of an ILS approach of a twin-pusher business/commuter turboprop aircraft configuration

A six-degree-of-freedom nonlinear simulation of a twin-pusher, turboprop business/commuter aircraft configuration representative of the Cessna ATPTB (Advanced turboprop test bed) was developed for use in piloted studies with the Langley General Aviation Simulator. The math models developed are provided, simulation predictions are compared with with Cessna flight-test data for validation purposes, and results of a handling quality study during simulated ILS (instrument landing system) approaches and missed approaches are presented. Simulated flight trajectories, task performance measures, and pilot evaluations are presented for the ILS approach and missed-approach tasks conducted with the vehicle in the presence of moderate turbulence, varying horizontal winds and engine-out conditions. Six test subjects consisting of two research pilots, a Cessna test pilot, and three general aviation pilots participated in the study. This effort was undertaken in cooperation with the Cessna Aircraft Company

Aeronautical engineering: A continuing bibliography with indexes (supplement 304)

This bibliography lists 453 reports, articles, and other documents introduced into the NASA scientific and technical information system in May 1994. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

Aeronautical enginnering: A cumulative index to a continuing bibliography (supplement 312)

This is a cumulative index to the abstracts contained in NASA SP-7037 (301) through NASA SP-7073 (311) of Aeronautical Engineering: A Continuing Bibliography. NASA SP-7037 and its supplements have been compiled by the Center for AeroSpace Information of the National Aeronautics and Space Administration (NASA). This cumulative index includes subject, personal author, corporate source, foreign technology, contract number, report number, and accession number indexes

1976-77 Teacher Salary Schedules, Scattergram, December 1976

This report contains 1976-77 teacher salary schedules, the placement of teachers on the salary schedule (known as a scattergram) and the average teacher salary exclusive of supplemental pay. The scattergrams and average salary figures include teacher lane changes resulting from summer school credits as of mid-October 1976