.GIF)
To meet the requirements of a fast, thorough system that is operationally efficient and increases vehicle reliability, Martin Marietta has undertaken a development program using a rule-based expert system to automate data analysis tasks. Given the large amount of data that must be analyzed, it is not feasible to reason on each data sample. To function efficiently and to minimize demands on system engineers, automated analysis processes must be event driven. Specific system events can be identified by characteristic signatures of associated vehicle measurements. Once the events in the data stream have been identified, the expert system can be used to distinguish and resolve expected and unexpected events.
NASA Lewis has developed and demonstrated feature extraction algorithms for a post-test diagnostic system (PTDS). The PTDS is an off-line aid to engineers who are responsible for detecting and diagnosing space shuttle main engine (SSME) anomalies. Feature extraction algorithms are at the root of the PTDS. These algorithms provide events to the rule-based expert system in the PTDS. They identify deviations within the data stream during steady-state operation. The algorithms reduce sensor traces into peaks, level shifts, spikes, and drifts; detect excessive noise, exceedance violations, and erratic regions; and check for consistency among redundant channels.
The feature extraction algorithms, as developed for the SSME PTDS, are inherently independent of the system to which they are applied. A cooperative effort between Martin Marietta and Lewis was undertaken to demonstrate the flexibility of the algorithms and to transfer the feature extraction technology and code to Martin. The effort successfully applied four feature extraction algorithms (spikes, level shifts, drifts, and peaks) to 15 parameters from the Centaur pneumatic and electrical subsystems and was completed within four months.
The feature extraction algorithms are being validated and will be incorporated into a ground-based expert system to enable automated data monitoring and analysis in support of day-to-day test and checkout activities. This work, to be implemented at Cape Canaveral, will reduce diagnostic time by an order of magnitude and increase diagnostic accuracy. Activities are planned to complete transfer of the algorithms and to aid in applying them to Atlas-Centaur propulsion system parameters.
Bibliography
Erickson, T.J.; Zakrajsek, J.F.; Sue, J.J.; Jankovsky, A.L.; Fulton, C.E.; and Meyer, C.M.: Post-Test Diagnostic System Feature Extraction Applied to Martin Marietta Atlas-Centaur Data. AIAA Paper 94-3224, June 1994.
Zakrajsek, J.F.: The Development of a Post-Test Diagnostic System for Rocket Engines. AIAA Paper 91-2528, June 1991.
Zakrajsek, J.F.; Fulton, C.E.; and Meyer, C.M.: Feature Extraction for Post-Test Diagnostics. Advanced Earth-To-Orbit Propulsion Technology Conference 1994, May 1994.
Lewis contact: June F. Zakrajsek, (216) 977-7470
Headquarters program office: OSAT
Advanced Arcjet Technology Commercialized
First-generation arcjets are now operational on the AT&T Telstar 401
spacecraft and are baselined on three other geosynchronous satellite series.
The arcjet system (thruster, power processor, and gas generator) uses
electrical energy from the spacecraft batteries to increase the enthalpy of the
propellant before it is exhausted at high velocities through a conical
converging/diverging nozzle. Use of an arc discharge heating process is the
unique feature of the device. Although the arc reaches temperatures of 17,000
deg.C, the engine design ensures that critical internal surfaces are protected
by a cool gas boundary layer. Materials limits inherent to conventional
thrusters are thus avoided, and the first-generation devices, with an average
specific impulse level of 502 sec, have more than 1.5 times the fuel economy for north-south stationkeeping of state-of-the art chemical and resistojet systems (ref. 1). Following acceptance of the technology on commercial satellites, an industry requirement for higher performance arcjets was identified, and a 600-sec arcjet was baselined on a new (next generation) satellite series. A NASA Lewis/industry effort to develop next-generation hydrazine arcjets has just been completed. The program has developed and demonstrated a 2-kW arcjet with a mission-average specific impulse of 607 sec and a 1000-hr/1000-cycle life.
.GIF)
The high-performance arcjet program was conducted through in-house efforts and a contract with Olin Aerospace Co. The successful completion of the program has resulted in the technology being added to Olin's product line. Early program efforts demonstrated that state-of-the-art materials used for the anode have unacceptable throat deformation at the higher temperatures encountered at higher performance levels. After an extensive search a high-strength, high-temperature material was identified. This tungsten-based alloy containing rhenium, hafnium, and carbon was first developed at NASA Lewis. Initial tests of an anode made from the material indicated that its performance would exceed program goals (ref. 2). A commercial source for the new alloy was established, and a flight-representative system was fabricated. After 1000 hr of operation at an average specific impulse level of 607 sec, the test was voluntarily terminated. Post-test examination showed minimal erosion.
The long-term program goal is to ensure U.S. competitiveness in low-thrust arcjets. The program is investigating strengthening the new tungsten alloy to increase thruster performance even further. Also, efforts have been redirected toward lower power level thrusters to provide propulsion options for smaller, power-limited spacecraft.
References
Paint Sampling Automated for Art Restoration
A Lewis resource developed to advance space age materials has been used to
better understand ancient works of art.
The Paintings Conservation Laboratory at the Cleveland Museum of Art has as its major role the preservation and restoration of the museum's renowned paintings collection, which ranges from the 13th century to the present day. An essential part of this task is preventive conservation. In some cases deteriorated original canvases have to be infused with adhesive and/or supported by new fabric. Old layers of dirt, discolored varnish, and former restorations are removed, followed by revarnishing and in-painting of losses, to dramatically improve the visual appearance of paintings.
The conservators at the Cleveland Museum of Art often undertake technical research to analyze an artist's technique. The resulting information is used both by conservators and art historians and can sometimes provide the vital clue in questions of authenticity. Important discoveries are added to the growing body of literature on artists' techniques. In paintings with complex layering, cross-sectional analysis is done before attempting a conservation treatment--for instance, when deciding whether a certain paint layer is original or a restoration.
Cross-sectional analysis of paint layers is one of the most valuable methods available to the painting conservator. A cross section displays a chronology of the artist's working methods, from the initial preparatory layers through the paint and varnish layers. The painter builds up the paint layers to develop subtle effects of tone, color, and surface texture, resulting in a complex three-dimensional structure. In addition to being viewed in normal light under a microscope, cross sections can be viewed by using ultraviolet light excitation in association with a variety of filters. Under these different lighting conditions, restoration layers can be distinguished visually from original layers.
The composition of medium-rich layers can often be determined by using biological staining tests, which can be important when deciding whether to remove surface coatings. Where further analysis is necessary to solve a particular cleaning problem or to understand the techniques of a certain artist, cross sections can be analyzed with the scanning electron microscope. This method determines the element content in the various layers, which gives an indication of pigments present and is a guide to binding media.
Polishing a cross section is difficult because of small sample size and paint chemistries and solubilities. Samples are rarely flat enough for viewing magnifications, and final surfaces are marked by scratches and other flaws. Results of the analyses are rarely of a quality suitable for publication. At the museum cross sections have traditionally been prepared by a hand-operated process from start to finish. First, a chip of paint, no bigger than a pinhead, is removed from the painting with a scalpel. This fragment is mounted and the layers are exposed by sanding and polishing.
Cross-sectional paint samples from an oil painting on canvas by John Harrison Witt (1840-1901) were given to NASA Lewis for experimentation. These samples posed particular difficulties for preparation as one of the lower paint layers is water soluble. During initial attempts to mount specimens in epoxy resin and polyester, we observed contamination from the mounting media on the surface of the cross section. An alternative medium composed of a modified polyester resin eliminated the contamination. The paint specimens were then mounted in standard mounts for automated preparation. All preparation steps were performed using standard NASA polishing techniques. Optical microscopy, with both bright field and polarized light, was used to locate and measure the position of the paint specimen during grinding and polishing. The resulting cross section was perfectly flat, intact, and suitable for photography and further analysis. Automated repolishing of samples after biological staining is also possible.
This automated preparation method has been used successfully on cross-sectional samples from a wide range of paintings in the Cleveland Museum of Art's collection. These include Titian's Adoration of the Magi (ca. 1508), Abbott Handerson Thayer's Self Portrait (1920), and Martin Johnson Heade's Point Judith, Rhode Island (ca. 1867-68).
Lewis contact: William Waters, (216) 433-5564
Headquarters program office: OSAT
New Material Removes Toxic Metals From Waste Water
NASA Lewis is developing a new innovative ion exchange material (IEM), a
polymer that removes toxic metals from water. This IEM, a spinoff from research
on space battery separators, is a blend of readily available, inexpensive
chemicals. It can be made as thin films, fine beads, coated magnetite beads,
porous sheets, and fine fibers and as a coating on screens and fibers. Since
1991 the Technology Utilization Office in partnership with Lewis' Office of
Environmental Programs has been working to bring this IEM technology from the
laboratory to a mature state that will encourage industry to license and market
it. (A patent is to be issued in late 1994.)
With the funding assistance of the Lewis Director's Discretionary Fund, the U.S. Environmental Protection Agency (EPA), and the U.S. Army Corps of Engineers, this IEM technology has been significantly advanced. The film form is near maturity. A production run of a 4000-ft-long strip of film was successfully achieved under contract by a small Cleveland-area company, Chemsultants International, Inc. The Southwest Research Institute (SWRI) in San Antonio, Texas, has been conducting research, under a grant, to develop the fine porous bead form of the IEM. Thus far SWRI has successfully produced IEM powder, magnetic particles encapsulated in IEM, and hollow IEM beads. Developing the process to make porous beads is their next project. The technology of fine fibers is still at the laboratory stage.
The uptake performance of the film form has been measured in laboratory tests, with the assistance of Baldwin-Wallace College in Berea, Ohio, and the University of South Florida, using water contaminated with a single toxic metal. Among the 20 metals tested were lead, copper, zinc, cadmium, and mercury. Lead in water was reduced in concentration from 150 parts per billion (ppb) to less than 2 ppb, well below the EPA action limit. Tests to measure the uptake performance of the beads are under way. Other tests have shown that the IEM is easy to use and inexpensive to make; strong, flexible, and not easily torn; and chemically stable in storage, in aqueous solutions, and in acidic or basic solutions. Although no toxicity tests have been performed, it is anticipated that this IEM is safe and nontoxic to handle.
Because the commercialization potential for the IEM appears to be very large, the Lewis Technology Utilization Office has been actively working with industry partners to test and evaluate it in industrial applications and to commercialize the technology. The IEM can be used in many industries--electroplating, electronics, and mining, which produces large amounts of waste water containing hazardous amounts of mercury, lead, cadmium, silver, copper, and zinc ions. The TU Office has written agreements with five companies to work with Lewis in joint demonstration tests and evaluations. All say they will use the IEM if its performance and cost effectiveness is acceptable. At least two companies wish to license the technology to make and market it for profit. One important demonstration test scheduled for late 1994 will determine the feasibility of removing the zinc dissolved in the rinse water of a zinc plating operation at the Aetna Plating Co. in Cleveland, Ohio. Cleveland State University and its affiliate the Advanced Manufacturing Center, under a cooperative agreement, are developing the test apparatus and conducting the test.
The research done to develop the IEM has produced a number of papers that were delivered at conferences and published. Two were award-winning papers by student interns, one from Baldwin-Wallace College and one from the University of Akron.
Bibliography
Hill, C.M.; Street, K.W.; Philipp, W.H.; and Tanner, S.P.: Determination of Copper in Tap Water Using Solid Phase Spectrophotometry. Analytical Letters, vol. 27, no. 13, 1994, p. 2589. (Also NASA TM-106480.)
Hill, C.M.; Street, K.W.; Philipp, W.H.; and Tanner, S.P.: Spectrophotometric Method for Determining Metal Ion Concentrations in Water Systems Using Ion Exchange Membranes. 44th Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Atlanta, GA, Mar. 1993.
Street, K.W.; Philipp, W.H.; Hill, C.M.; and Tanner, S.P.: Luminescence Technique for Determining Metal Ion Concentrations After Preconcentrating on Ion Exchange Membranes. Abstract 52, Federation of Analytical Chemistry and Applied Spectroscopy Societies, 20th Annual Meeting, Detroit, MI, Oct. 1993.
Philipp, W.H.; Street, K.W.; and Savino, J.: A New Material for Removing Heavy Metals From Waste Water. Technology 2003, Anaheim, CA, Dec. 1993.
Street, K.W.; Philipp, W.H.; Tanner, S.P.; and Hill, C.M.: Preparation and Characterization of a New, Weak Acid Ion Exchange Film. Cleveland Section of American Chemical Society Meeting in Miniature, Cleveland, OH, Mar. 1994.
Talu, O.; Shah, D.B.; Street, K.W.; Philipp, W.H.; and Wan, W.: A New Ion-Exchange Medium for the Removal of Heavy Metal Ions From Aqueous Solution. Presented at American Chemical Society National Meeting, San Diego, CA, Mar. 1994.
Talu, O.; Shah, D.B.; Sun, S.; Street, K.W.; Philipp, W.H.; and Wan, W.: A New Ion-Exchange Media for Heavy Metal Removal From Solutions and Slurries. Presented at American Institute of Chemical Engineers National Meeting, San Diego, CA, Nov. 1994.
Talu, O.; Shah, D.B.; Sun, S.; Street, K.W.; Philipp, W.H.; and Wan, W.: Continuous Heavy Metal Removal From Solutions and Slurries by Films of a New Ion-Exchange Medium. Presented at American Institute of Chemical Engineers National Meeting, San Diego, CA, Nov. 1994.
Lewis contact: Dr. Joseph M. Savino, (216) 433-5531
Consortium on Advanced Coatings and Surface Modifications Formed
The Great Lakes Industrial Technology Center (GLITeC) formed the Consortium on
Advanced Coatings and Surface Modifications to help transfer advanced coating
and surface modification technologies developed at NASA Lewis to its member
companies. NASA Lewis' participation in the consortium will consist of private
consultations by Lewis researchers with member companies and the preparation of
samples for evaluation by member companies. All NASA work will be reimbursed
through a reimbursable Space Act Agreement between NASA Lewis and GLITeC.
GLITeC manages the consortium, collects member fees, and arranges with NASA
Lewis the various activities for each industry member.
In addition to NASA's services each member receives a comprehensive report that describes selected surface-treatment and coating technologies and their potential applications. This report is prepared by researchers and consultants at the Battelle Memorial Institute in Columbus, Ohio. GLITeC is a division of Battelle.
The first companies joined the consortium in January 1994. (Of the basic membership fee of $10,000, $7500 is earmarked for reimbursable services performed by NASA Lewis.) Included in this group are companies involved in the manufacture of ion sources for industrial processes and companies investigating advanced coatings for potential processing equipment, consumer products, and medical applications.
Lewis contact: Stephen M. Riddlebaugh, (216) 433-5565
Headquarters program office: OSAT
Lewis Technologies Selected for Evaluation by Federal Laboratory Consortium
The Midwest Region of the Federal Laboratory Consortium (FLC) for Technology
Transfer is conducting the Strategic Technology Evaluation Program (STEP) to
evaluate the marketability of candidate technologies submitted by all Federal
laboratories in the six-state region. The FLC STEP is patterned after the NASA
STEP conducted at Lewis in 1993.
FLC member laboratories in the Midwest Region states (Ohio, Michigan, Indiana, Illinois, Wisconsin, and Minnesota) submitted candidate technologies to the Regional Advisory Panel of the FLC. Of the 10 technologies selected by the panel for market evaluation, two came from NASA Lewis: "Guanadine, a Unique Strong Organic Base," by Warren H. Philipp and Joseph M. Savino; and "Gas Chromatic Mass Spectrometer," by Chowen C. Wey.
The FLC contracted the Great Lakes Industrial Technology Center to conduct market surveys for each technology.
Lewis contact: Stephen M. Riddlebaugh, (216) 433-5565
Headquarters program office: OSAT
Last updated 1995
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