Test & Measurement

Comparison of Three Methods for Measuring Distortion in Optical Windows

A new method for quantifying distortion based on phase-shifting interferometry has been developed. John F. Kennedy Space Center, Florida The primary function of a window is to allow observation of, and protection from, a potentially hazardous environment. Yet, from the window designer’s point of view, ensuring protection from weather conditions in home windows; from wind, temperature, and airborne debris in automotive windows; and from extreme pressures and temperatures in aircraft and spacecraft windows has almost always taken precedence over image quality. It is more important to protect an astronaut from the vacuum of space than to provide clear imagery, yet these are not exclusive requirements. Advances in materials and material processing allow the designer to attain better optical performance while not sacrificing important material specifications such as strength. In addition, increased performance demands on spacecraft windows — which are now used for photography, telescope observation, and laser communications — require greater consideration of optical clarity.

Posted in: Briefs, TSP, Test & Measurement, Windows and windshields, Finite element analysis, Visibility, Spacecraft


Measurement of O-phthalaldehyde (OPA)

This analytical process uses high-pressure liquid chromatography (HPLC) with post-column derivatization. Stennis Space Center, Mississippi O-phthalaldehyde (OPA) is a high-level disinfectant commonly used, for example, for sterilization of heat-sensitive medical instruments; it demonstrates effective microbicidal activity against a wide range of microorganisms (including mycobacteria, gramnegative bacteria, and spores). On the International Space Station (ISS), to achieve thermal control and maintain components at acceptable temperatures, systems that produce waste heat need to have that heat transferred from the ISS to space. To accomplish this, the ISS has an Internal Active Thermal Control System (IATCS) — a water-based system that works in conjunction with the EATCS (External ATCS), an ammoniabased system — to facilitate this heat transfer process.

Posted in: Briefs, Test & Measurement, Thermal management, Chemicals, Waste materials, Coolants, Spacecraft


Improved Combustion Products Monitor for the ISS

Applications include fire and environmental analyzers in aircraft, submarines, and industrial plants. John H. Glenn Research Center, Cleveland, Ohio Fire safety in space vehicles is of utmost importance, especially for manned flight. On the International Space Station (ISS), events that may lead to fires, especially smoldering, must be detected quickly and their location found. The analyzer used on the ISS must be automated, portable, and sensitive to the gases that are most likely to indicate the presence of a fire or pre-ignition event. In addition, after any fire event, the monitor must be useful to indicate that toxic gas levels have subsided for safe reentry of the crew to the affected area. Gases of interest may originate from the smoldering of Teflon wires, polyurethane foams, Delrin, and other plastics and furnishings in the ISS.

Posted in: Briefs, TSP, Test & Measurement, Fire detection, Protective equipment, Spacecraft


Decomposition Technique for Remaining Useful Life Prediction

This invention has applications in electronic systems, mining, medical equipment, power generation, smart buildings, transportation vehicles, and industrial machinery. Ames Research Center, Moffett Field, California Technology has been developed that provides a way to compute the remaining useful life (RUL) of a component or system. The estimation of the RUL of a degraded or faulty component is at the center of condition-based maintenance, and prognostics and health management. It gives operators a potent tool in decision-making by quantifying how much time is left until functionality is lost. This is especially important for aerospace systems, where unanticipated subsystem or component failure may lead to failure of the system as a whole, which in turn may adversely affect the safety of operation.

Posted in: Briefs, Test & Measurement, Failure modes and effects analysis, Life cycle analysis, Prognostics


Strain Gage for Highly Elastic, Low-Modulus Materials

This gage surpasses conventional foil technology, measuring elastic strain range greater than 100 percent while reducing measurement error. Armstrong Flight Research Center, Edwards, California Researchers at NASA’s Armstrong Flight Research Center have developed and tested a new strain gage that makes significant strides in the state of the art, particularly salient given the requirements of new structural components on aerospace vehicles. Conventional foil technology presents a significant shortcoming for these vehicles, since it is limited to less than 20 percent strains while newer vehicles include highly elastic, low-Young’s-modulus materials that require higher strain measurements. For example, fabric-reinforced rubbers and elastomers have a nonlinear stressstrain relationship with extreme rupture strains — some greater than 500 percent.

Posted in: Briefs, Test & Measurement, Elastomers, Materials properties


Improved Detection of Kidney Stones Using S-mode Ultrasound

Steps were developed to improve kidney stone detection relative to surrounding tissue.Ultrasound has been a useful tool in the detection of kidney stones. It is a low-cost solution that does not require ionizing radiation that would be harmful to vulnerable populations such as children and recurrent stone formers. However, it suffers from a broad range of sensitivity (78 to 96%) and specificity (31 to 100%) in the detection of stones.

Posted in: Briefs, Test & Measurement


Vector Network Analyzer Calibration for Quasi-Optical Dual Ports

Goddard Space Flight Center, Greenbelt, Maryland It is desirable to measure the electromagnetic properties of devices and materials in the millimeter part of the spectrum. For guided wave-based devices and materials (waveguides, coaxial devices), a vector network analyzer (VNA) is an excellent tool for this purpose since it provides full reflection and transmission characterization at high precision.

Posted in: Briefs, TSP, Test & Measurement


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