Tech Briefs

A Portable, Projection Focusing Schlieren System

Heating, ventilation, and air conditioning systems can be monitored using this system, especially those used in commercial kitchens and industrial ventilation. John H. Glenn Research Center, Cleveland, Ohio A new type of projection schlieren camera system (schlierenscope) is more portable, easier to align, and more versatile than existing systems. The schlierenscope is a projection focusing schlieren camera system that can acquire images of shock waves, vortices, gas jets, and other disturbances that create gradients in the refractive index of a transparent medium. These gradients appear as streaks (called schlieren in German) in the resulting image. Thus, a schlierenscope is an apparatus for looking at disturbances in transparent media. The schlierenscope constructed in the project utilizes fast strobes that freeze motion and capture images with a scientific CCD (charge-coupled device) camera. The schlierenscope is unique among schlieren instruments because all of the critical controls are contained within the instrument housing.

Posted in: Test & Measurement, Briefs, TSP

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Cryogenic and Non-Cryogenic Optical Liquid Level Instrument for Stratified Conditions

Marshall Space Flight Center, Alabama Typical cryogenic tank metering systems use a series of thermocouple, RTD, or other temperature or resistive devices in a rake or array configurations. Since these operate using the thermal change between the liquid and gas fluid phases, they are limited by thermal latency (the time it takes the sensing element to respond to the temperature). In addition, cryogenic fluids often create a volatile boundary or sloshing layer. This layer causes uncertainties of the true fluid boundary in a tank. Finally, accuracy and resolution are determined by the number of sensing segments used. These are typically tied to individual data channels, which puts a strain on data acquisition systems to achieve continuous and high-accuracy values.

Posted in: Test & Measurement, Briefs

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Low-Pressure Ion Chromatography for Planetary Exploration

NASA’s Jet Propulsion Laboratory, Pasadena, California Ion chromatography is the state-of-the-art technique for anion separation and analysis on Earth, but it typically requires a large, powerful pump to operate at high pressures in order to speed up analysis time. The weight and power requirements of the pump interfere with creating an ideal instrument for flight. The solution is to run the ion chromatography system at low pressure to allow the use of a smaller, lower-power pump for flight, but at the expense of longer analysis time.

Posted in: Test & Measurement, Briefs

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Ultra-Low-Maintenance Portable Ocean Power Station

These fuel cell systems can be used for remote power generation, transportation applications, or in offshore wells. NASA’s Jet Propulsion Laboratory, Pasadena, California The goals of this research are to develop a relatively inexpensive, compact, and modular power package for deep offshore oil drilling or other undersea applications that provides 2 to 5 MW electricity, minimal maintenance, and at least 30 years of life.

Posted in: Physical Sciences, Briefs, TSP

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Mars-Optimized Solar Cells

NASA’s Jet Propulsion Laboratory, Pasadena, California Commercial triple junction solar cell designs were modified in their junction thicknesses, contact grid densities, and anti-reflective (AR) coating thicknesses to better match the Mars surface solar spectrum. Resulting cells show up to approximately 8% relative improvement in efficiency under the Mars solar spectrum, compared to non-optimized space solar cells, in testing performed at JPL.

Posted in: Physical Sciences, Briefs

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Alternating Magnetic Field Forces for Satellite Formation Flying

John F. Kennedy Space Center, Florida Orbiting a large number of satellites in fixed formations will be critical to many future space missions, especially large-scale interferometers, telescopes, antennas, and gravity wave detectors. Consequently, extensive research has been devoted over the last 20 years to formation flying architectures, concentrating not only on the mission objective, but also on the technologies required to achieve a stable satellite formation. Several proposals have been suggested for determining the location of the satellites, but the more difficult problem is developing a system that can hold the satellites at those desired locations and orientations. The two most common solutions are to use microthrusters, though these require propellant and will eventually be depleted, or to choose orbital patterns that minimize relative perturbations, but for highly precise positioning, this is not adequate. Neither of these approaches solves the problem for long-duration missions such as a multi-element telescope where the mirrors must be located and oriented to a tolerance less than an optical wavelength.

Posted in: Physical Sciences, Briefs, TSP

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Peak-Seeking Control Method

An algorithm optimizes performance of complex operations in real time. Neil A. Armstrong Flight Research Center, Edwards, California Peak-seeking algorithms optimize physical processes in real time and are widely used throughout a variety of industries. However, measuring associated parameters in changing conditions, and responding to them appropriately, is difficult because the measurements are typically distorted by noise. This technology addresses that problem by employing a time-varying Kalman filter. The filter is an algorithm previously developed to estimate unknown parameters within systems that are intrinsically random and uncertain. The Kalman filter is excellent at finding estimates when it encounters noisy signals. As a minimal-variant filter, it inherently produces the best estimates of a function with the smallest amount of variation from the true value. Thus, the filter can help accurately determine the optimal coordinates of the peak- seeking function as conditions in the environment change.

Posted in: Electronics & Computers, Software, Briefs, TSP

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