. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. DRAG ON A MODEL OF AN ARTEMIA LIMB 159 steel shjm. << A/D 1 low pass filler - .Illinium, IlliUlRjMl}' strain gauges brass mounftjig rod glycerine Figure 2. Apparatus used for measuring thrust of the model of Ar- lemia larval antenna. The mounting carnage translates along an axis perpendicular to the plane of the page. The strain gauge frame is seen in planar view to the left of the diagram. (V = voltage; A/D = analog to digital.) The model was attached to the end of a long, thin, brass rod that extended into a 50-gallo
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. DRAG ON A MODEL OF AN ARTEMIA LIMB 159 steel shjm. << A/D 1 low pass filler - .Illinium, IlliUlRjMl}' strain gauges brass mounftjig rod glycerine Figure 2. Apparatus used for measuring thrust of the model of Ar- lemia larval antenna. The mounting carnage translates along an axis perpendicular to the plane of the page. The strain gauge frame is seen in planar view to the left of the diagram. (V = voltage; A/D = analog to digital.) The model was attached to the end of a long, thin, brass rod that extended into a 50-gallon tank of glycerine (Fig. 2). The model rode in the middle of the tank approxi- mately six model-lengths to the sides of the tank and seven to the bottom. The model limb could oscillate and trans- late independently at various speeds and frequencies. A modified pen plotter (Houston Instruments. Omni- graphic), controlled directly by a computer, translated the limb at speeds ranging from cm s~' to cm s~'. A rotating cam, driven by a small motor connected to the base of the brass rod, swung the limb in a 100° arc in an oscillating manner. A potentiometer documented the po- sition of the model in the cycle. Frequencies ranged from Hz to Hz. Two opposing 350-ohm semiconductor, strain gauges (Entran), aligned perpendicular to the direction of thrust, measured displacement. I calibrated the force required to yield these displacements by hanging a series of small weights, g, from the aluminum block between the two strain gauges (planar view of strain gauge frame: see Fig. 2, strain gauge frame). From this, I calculated a re- lationship between force and voltage. The response of the strain gauges was linear for the displacements I measured. The signal was amplified by a Gould bridge amplifier and filtered with a Krohn-Hite variable filter. Low-pass filter- ing with a 10-Hz cutoff removed the mechanical and other high-frequency noise caused by translating the m
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
