Test & Measurement

Multimodal Friction Ignition Tester

Responses of material specimens to vibrational friction in pressurized oxygen are recorded. The multimodal friction ignition tester (MFIT) is a testbed for experiments on the thermal and mechanical effects of friction on material specimens in pressurized, oxygen-rich atmospheres. In simplest terms, a test involves recording sensory data while rubbing two specimens against each other at a controlled normal force, with either a random stroke or a sinusoidal stroke having controlled amplitude and frequency. The term “multimodal” in the full name of the apparatus refers to a capability for imposing any combination of widely ranging values of the atmospheric pressure, atmospheric oxygen content, stroke length, stroke frequency, and normal force. The MFIT was designed especially for studying the tendency toward heating and combustion of nonmetallic composite materials and the fretting of metals subjected to dynamic (vibrational) friction forces in the presence of liquid oxygen or pressurized gaseous oxygen — test conditions approximating conditions expected to be encountered in proposed composite-material oxygen tanks aboard aircraft and spacecraft in flight.

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Cryogenic Chamber for Servo-Hydraulic Materials Testing

A compact cryogenic test chamber can be cooled to approximately 5 to 6 Kelvin for materials testing. The system includes a temperature controller and multiple sensors to measure specimen temperature at different locations. The testing chamber provides a fast and easy method to perform materials testing at lower than liquid nitrogen temperature (77 K). The advantage of this chamber is that lower than 77 K temperatures are achievable, and the temperature can be controlled and stabilized during a test.

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Power Supply for Miniature Quadrupole Mass Spectrometer

This lightweight, low-power system is designed to operate unattended for a long time. A lightweight, low-power-consumption power supply has been developed to generate a combination of radio-frequency (RF) and dc voltages needed for the operation of a miniature quadrupole mass spectrometer that could operate unattended in the field for a long time, possibly using a battery as an energy source. More specifically, the circuit is designed to supply large, variable, frequency- and amplitude-stable RF voltages, variously floating or superimposed on positive or negative dc voltages, for application to primarily capacitive mass-spectrometer loads with capacitances of the order of 50 pF.

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Instrument Measures Fluorescence From Chlorophyll in Plants

Effective discrimination against solar background radiation is achieved without critical optical and mechanical parts. An optoelectronic instrument, known as a plant fluorescence sensor, is being developed for use as a working tool in agricultural settings. This instrument is a remote, passive monitor that provides a means of discerning plant stress at very early stages. With sufficient warning, the user could provide timely applications of fertilizer, water, and/or pesticide to achieve maximum crop yield at minimum cost. Figure 1 presents two views of the plant fluorescence sensor. The instrument is the subject of U. S. Patent 5,567,947.

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600-GHz Electronically Tunable Vector Measurement System

The design satisfies a complex set of technical and economic requirements. A compact, high-dynamic-range, electronically tunable vector measurement system that operates in the frequency range from ≈560 to ≈635 GHz has been developed as a prototype of vector measurement systems that would be suitable for use in nearly-real- time active submillimeter-wave imaging. A judicious choice of intermediate frequencies makes it possible to utilize a significant amount of commercial off-the-shelf communication hardware in this system to keep its cost relatively low. The electronic tunability of this system has been proposed to be utilized in a yet-to-bedeveloped imaging system in which a frequency- dispersive lens would be used to steer transmitted and received beams in one dimension as a function of frequency. Then acquisition of a complete image could be effected by a combination of frequency sweeping for scanning in the aforesaid dimension and mechanical scanning in the perpendicular dimension.

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Advances in Measurement of Skin Friction in Airflow

This system implements a combination of established experimental techniques and advanced image processing. The surface interferometric skin-friction (SISF) measurement system is an instrument for determining the distribution of surface shear stress (skin friction) on a wind-tunnel model. The SISF system utilizes the established oil-film interference method, along with advanced image-data-processing techniques and mathematical models that express the relationship between interferograms and skin friction, to determine the distribution of skin friction over an observed region of the surface of a model during a single wind-tunnel test.

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Improved Apparatus for Testing Monoball Bearings

Automated tests can be performed over wide ranges of conditions. A desk-sized apparatus for testing monoball bearings and their lubricants offers advantages, relative to prior such apparatuses, of (1) a greater degree of automation and (2) capability of operation under wider and more realistic ranges of test conditions. The ranges of attainable test conditions include load from 100 to >50,000 lb (445 to >2.22 ~ 105 N), resisting torque up to 30,000 lbin. (.3,390 N-m), oscillating rotation through an angle as large as 280‹, and oscillation frequency from 0 to 6 Hz. With addition of some components and without major modification of the apparatus, it is also possible to perform tests under environmental conditions that include temperature from .320 to 1,000 ‹F (.196 to +538 ‹C), relative humidity from 0 to 100 percent, and either air at ambient pressure, high vacuum, or an atmosphere of monatomic oxygen.

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