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NASA NTRS1996

Speed estimates from grating patches are not contrast-normalized

We have previously shown that the perceived speed of a moving grating depends upon its contrast, with lower-contrast patterns appearing to move more slowly than otherwise identical higher-contrast patterns. To explain this finding while remaining consistent with the findings of McKee, Silverman and Nakayama [(1986) Vision Research, 26, 609-619], we proposed that this misperception might arise from a modified version of the contrast-normalization procedure, envisaged by Adelson and Bergen [(1986) The extraction of spatio-temporal energy in human and machine vision (pp. 135-139). Charleston, S.C.: IEEE Computer Society] as a necessary second stage of motion-energy models of human motion processing. Specifically, our previous results might be explained if the two gratings to be compared interfered with each other's normalization. To test this hypothesis we performed two experiments. Experiment 1 demonstrates that the contrast effects persist even when two grating patches to be compared are presented up to 5 sec apart so that they would not be expected to bias each other's normalization. Experiment 2 shows that the contrast effects are unchanged when the two grating patches are surrounded by a range of patterns whose contrast would be expected to interfere with any normalization process. These two results allow the rejection of the contrast-normalized motion-energy hypothesis as an explanation of human speed perception. We discuss the consequences of these results on models of speed processing in the human visual system.

NASA Center ARC↗
NASA NTRS2005

Two Dimensional Viscoelastic Stress Analysis of a Prototypical JIMO Turbine Wheel

The designers of the Jupiter Icy Moons Orbiter (JIMO) are investigating the potential of nuclear powered-electric propulsion technology to provide deep space propulsion. In one design scenario a closed-Brayton-cycle power converter is used to convert thermal energy from a nuclear reactor to electrical power for the spacecraft utilizing an inert gas as the working fluid to run a turboalternator as described in L.S. Mason, "A Power Conversion for the Jupiter Icy Moons Orbiter," Journal of Propulsion and Power, vol. 20, no. 5, pp. 902-910. A key component in the turboalternator is the radial flow turbine wheel which may be fabricated from a cast superalloy. This turbine wheel is envisioned to run continuously over the life of the mission, which is anticipated to be about ten years. This scenario places unusual material requirements on the turbine wheel. Unlike the case of terrestrial turbine engines, fatigue, associated with start-up and shut-down of the engine, foreign-object damage, and corrosion issues are insignificant and thus creep issues become dominate. The purpose of this paper is to present estimates for creep growth of a prototypical JIMO turbine wheel over a ten year life. Since an actual design and bill of materials does not exist, the results presented in this paper are based on preliminary concepts which are likely to evolve over time. For this reason, as well as computational efficiency, a simplified 2-D, in lieu of a 3-D, viscoelastic, finite element model of a prototypical turbine wheel will be utilized employing material properties for the cast superalloy MAR-M247. The creep data employed in this analysis are based on preliminary data being generated at NASA Glenn Research Center.

Gayda, John↗
NASA NTRS2005

Aerodynamic and Gasdynamic Effects in Cosmogony

Senior Scientist Stuart J. Weidenschilling presents his final administrative report for the research program entitled "Aerodynamic and Gasdynamic Effects in Cosmogony" on which he was the Principal Investigator. The research program produced the following publications: 1) Particle-gas dynamics and primary accretion. J . N. Cuzzi and S. J. Weidenschilling. In Meteorites and the Early Solar System II (D. Lauretta and H. Y . McSween, Eds.). Univ. Arizona Press. in press, 2005; 2) Timescales of the solar protoplanetary disk. S. Russell, L. Hartmann. J. N. Cuzzi. A. Krot. M. Gounelle and S . J Weidenschilling. In Meteorites and the Early Solar System II (D. Lauretta and H. Y. McSween, Eds.). Univ. Arizona Press, in press, 2005; 3) From icy grains to comets. In Comets II (M. Festou et al., Eds.). Univ. Arizona Press, pp. 97-104. 2004; 4) Gravitational instability and clustering in a disk of planetesimals. P. Tanga, S. J. N'eidenschilling, P. Michel and D. C. Richardson. Astron. Astrophys. 327, 1 105- 1 1 15, 2004.

Weidenschilling, Stuart J.↗
NASA NTRS2005

Fractionation and Accretion of Meteorite Parent Bodies

Senior Scientist Stuart J. Weidenschilling presents his final administrative report for the research program on which he was the Principal Investigator. The research program resulted in the following publications: 1) Particle-gas dynamics and primary accretion. J. N. Cuzzi and S. J . Weidenschilling. To appear in Meteorites and the Early Solar System 11 (D. Lauretta et a]., Eds.), Univ. Arizona Press. 2005; 2) Timescales of the solar protoplanetary disk. S. Russell, L. Hartmann, J . N. Cuzzi, A. Krot, M. Gounelle and S. J. Weidenschilling. To appear in Meteorites and the Early Solar System II (D. Lauretta et al., Eds.), Univ. Arizona Press, 2005; 3) Nebula evolution of thermally processed solids: Reconciling astrophysical models and chondritic meteorites. J. N. Cuzzi, F. J. Ciesla, M. I. Petaev, A. N. Krot, E. R. D. Scott and S . J. Weidenschilling. To appear in Chondrites and the Protoplanetary Disk (A. Krot et a]., Eds.), ASP Conference Series, 2005; 4) Possible chondrule formation in planetesimal bow shocks: Physical processes in the near vicinity of the planetesimal. L. L. Hood, F. J. Ciesla and S. J. Weidenschilling. To appear in Chondrites and the Protoplanetary Disk (A. Krot et al., Eds.), ASP Conference Series, 2005; 5) From icy grains to comets. In Comets II (M. Festou et al., Eds.), Univ. Arizona Press, pp. 97- 104, 2005; 6) Evaluating planetesimal bow shocks as sites for chondrule formation. F. J . Ciesla, L. L. Hood and S. J. Weidenschilling. Meteoritics & Planetary Science 39, 1809-1 821, 2004; and 7) Radial drift of particles in the solar nebula: Implications for planetesimal formation. Icarus 165, 438-442, 2003.

Weidenschilling, Stuart J.↗
NASA NTRS1949

Lame's Wave Functions of the Ellipsoid of Revolution

It has recently Miss Gertrude Blanch that errors exist in been brought to the attention of the NACA by of the Bureau of Standards, Department of Commerce the tabulated values appearing in tables 11 to 17 of TM 1224. Miss Blanch notes that C. J. Bouwkamp~ from whom Meixner obtained the values presented, subsequently corrected them in tables. appearing in the Journal of Mathematics and Physics, vol. XXVI, no. 2, JULY 1947, pp. 88-91. In spite of the difference in symbols and notation in the two papers, reprints of tables I to IX included in the July 1947 issue of the Journal of Mathematics and Physics are attached for the use of those interested in receiving them. The NACA wishes to express its appreciation to the Journal of Mathematics and Physics for permitting these tables to be reproduced for this purpose.

Meixner, J.↗
NASA NTRS2005

Down-to-Earth Benefits of Space Exploration: Past, Present, Future

A ventricular device that helps a weakened heart keep pumping while awaiting a transplant. A rescue tool for extracting victims from dangerous situations such as car wrecks. A video analysis tool used to investigate the bombing at the 1996 Olympics in Atlanta. A sound-differentiation tool for safer air traffic control. A refrigerator that run without electricity or batteries. These are just a few of the spin-offs of NASA technology that have benefited society in recent years. Now, as NASA sets its vision on space exploration, particularly of the moon and Mars, even more benefits to society are possible. This expansion of societal benefits is tied to a new emphasis on technology infusion or spin-in. NASA is seeking partners with industry, universities, and other government laboratories to help the Agency address its specific space exploration needs in five areas: (1) advanced studies, concepts, and tools; (2) advanced materials; (3) communications, computing, electronics, and imaging; (4) software, intelligent systems, and modeling; and (5) power, propulsion, and chemical systems. These spin-in partnerships will offer benefits to U.S. economic development as well as new products for the global market. As a complement to these spin-in benefits, NASA also is examining the possible future spin-outs of the innovations related to its new space exploration mission. A matrix that charts NASA's needs against various business sectors is being developed to fully understand the implications for society and industry of spin-in and spin-out. This matrix already has been used to help guide NASA s efforts to secure spin-in partnerships. This paper presents examples of NASA spin-offs, discusses NASA s present spin-in/spin-out projects for pursuing partnerships, and considers some of the future societal benefits to be reaped from these partnerships. This paper will complement the proposed paper by Frank Schowengerdt on the Innovative Partnerships Program structure and how to work with the PP.

Neumann, Benjamin↗
NASA NTRS2004

Hematopoietic Stem Cell Therapy to Countermeasure Cancer in Astronauts during Exploration of Deep Space

Exposure to cosmic radiation can cause chromosomal mutations, which may lead to cancer in astronauts engaged in space exploration. Therefore, our goals are to develop countermeasures to prevent space-induced cancer using hematopoietic stem cell therapy (HSCT) and gene therapy. This presentation focuses on HSCT for cancer. Our previous experiments on a simulated, space-induced immuno-deficiency model (mouse hind limb unloading ) indicated that transplanted hematopoietic stem cells (HSCs) could enhance the host's immunity by effectively eliminating bacterial infection (Ohi S, et. al. J Grav Physiol 10, P63-64, 2003; Ohi S, et. al. Proceedings of the Space Technology and Applications International Forum (STAIF) . American Institute of Physics, New York, pp. 938-950, 2004). Hence, we hypothesized that the HSCs might be effective in combating cancer as well. Studies of cocultured mouse HSCs with beta-galactosidase marked rat gliosarcoma spheroids (9L/lacZ), a cancer model, indicated antagonistic interactions , resulting in destruction of the spheroids by HSCs. Trypan Blue dye-exclusion assays were consistent with the conclusion. These results show potential usehlness of HSCT for cancer. Currently, the NASA Hydrodynamic Focusing Bioreactor (HFB), a space analog tissue/cell culture system, is being used to study invasion of the gliosarcoma (GS) spheroids into mouse brain with or without co-cultured HSCs. This may simulate the metastasis of gliosarcoma to brain. There is a tendency for the HSCs to inhibit invasion of GS spheroids into brain, as evidenced by the X-gal staining.

Ohi, S.↗
NASA NTRS2007

An Attempt to Observe Debris from the Breakup of a Titan 3C-4 Transtage

In February 2007 dedicated observations were made of the orbital space predicted to contain debris from the breakup of the Titan 3C-4 transtage back on February 21, 1992. These observations were carried out on the Michigan Orbital DEbris Survey Telescope (MODEST) in Chile with its 1.3deg field of view. The search region or orbital space (inclination and right ascension of the ascending node (RAAN) was predicted using NASA#s LEGEND (LEO-to-GEO Environment Debris) code to generate a Titan debris cloud. Breakup fragments are created based on the NASA Standard Breakup Model (including fragment size, area-to-mass (A/M), and delta-V distributions). Once fragments are created, they are propagated forward in time with a subroutine GEOPROP. Perturbations included in GEOPROP are those due to solar/lunar gravity, radiation pressure, and major geopotential terms. Barker, et. al, (AMOS Conference Proceedings, 2006, pp. 596-604) used similar LEGEND predictions to correlate survey observations made by MODEST (February 2002) and found several possible night-to-night correlations in the limited survey dataset. One conc lusion of the survey search was to dedicate a MODEST run to observing a GEO region predicted to contain debris fragments and actual Titan debris objects (SSN 25000, 25001 and 30000). Such a dedicated run was undertaken with MODEST between February 17 and 23, 2007 (UT dates). MODEST#s limiting magnitude of 18.0 (S\N approx.10) corresponds to a size of 22cm assuming a diffuse Lambertian albedo of 0.2. However, based on observed break-up data, we expect most debris fragments to be smaller than 22cm which implies a need to increase the effective sensitivity of MODEST for smaller objects. MODEST#s limiting size can be lowered by increasing the exposure time (20 instead of 5 seconds) and applying special image processing. The special processing combines individual CCD images to detect faint objects that are invisible on a single CCD image. Sub-images are cropped from six consecutive CCD images with pixel shifts between images being consistent with the predicted movement of a Titan object. A median image of all the sub-images is then created leaving only those objects with the proper Titan motion. Limiting the median image in this manner brings the needed computer time to process all images taken on one night down to about 50 hours of CPU time.

Barker, E. S.↗
NASA NTRS2005

Planetary Protection Technologies: Technical Challenges for Mars Exploration

The search for life in the solar system, using either in situ analysis or sample return, brings with it special technical challenges in the area of planetary protection. Planetary protection (PP) requires planetary explorers to preserve biological and organic conditions for future exploration and to protect the Earth from potential extraterrestrial contamination that could occur as a result of sample return to the Earth-Moon system. In view of the exploration plans before us, the NASA Solar System Exploration Program Roadmap published in May 2003 identified planetary protection as one of 13 technologies for "high priority technology investments." Recent discoveries at Mars and Jupiter, coupled with new policies, have made this planning for planetary protection technology particularly challenging and relevant.New missions to Mars have been formulated, which present significantly greater forward contamination potential. New policies, including the introduction by COSPAR of a Category IVc for planetary protection, have been adopted by COSPAR in response. Some missions may not be feasible without the introduction of new planetary protection technologies. Other missions may be technically possible but planetary protection requirements may be so costly to implement with current technology that they are not affordable. A strategic investment strategy will be needed to focus on technology investments designed to enable future missions and reduce the costs of future missions. This presentation will describe some of the potential technological pathways that may be most protective.

planetary protections↗
NASA NTRS2006

Eastern European Science Needs Sweeping Changes

Sir - Two years ago your Editorial "Eastern Promise" (vol. 426, p.369, 2003) and the News Feature "Dreaming on Danube" (vol. 427, p.94-95,2004) as well as several subsequent correspondence letters (vol. 427, pp. 196 and 677, vol. 428, p.17) touched on the situation and potential growth in scientific research in the former Soviet block countries. I would like to revisit this topic. Right now the facts are sobering: while the average GNP per capita in those countries is a few times lower than the average for the rest of Europe, their average university ranking is another order of magnitude poorer (in the latest ARWU, of the first 123 European universities only 4, and that in the second half of the list only, are from the former Soviet block). That situation calls for drastic measures. Pumping extra money into the system would change little. The only real hope is in a new generation of young dynamic scientists setting the pace for academic life. That requires selection and promotion of the best of the best. Unfortunately much of the old guard, who is not up to scientific challenges of today and who attained their positions and influence under the old regime (often due to other than professional qualifications) resist any real changes. I believe that a major change for better could be achieved by implementation into law two key requirements: transparency and competitiveness. That means a transparency of every scientist achievements (particularly in terms of publications), and wide open and fair competition for academic positions. Those two conditions should be complemented by implementation of the position of academic ombudsman (to encourage/facilitate open discussions), special grant opportunities for young scientists, and transparency of the process of awarding research grants. I, as well as a number of my colleagues concerned with the future of science and higher education in Poland, discussing many important academic issues at the Independent Academic Forum (an Association with a non-commercial website, http://www.naukaedukacia. tubaza.pl/, with tens of thousands of visits last year), strongly believe that the above postulated changes in the academic environment would lead to a major improvement in the quality and standing of scientific research and higher education in Poland and other post-communist countries (which suffer similar problems). It is symptomatic that the voice of at least hundreds of the most active and usually younger scientists heard at our NFA forum is totally ignored by the old establishment and their decision making representatives who "know better". Major political and legislative decisions are called for. We are doing our best to press for such changes.

Palosz, Witold↗
NASA NTRS2008

Final Report on NASA Portable Laser Coating Removal Systems Field Demonstrations and Testing

Processes currently used throughout the National Aeronautics and Space Administration (NASA) to remove corrosion and coatings from structures, ground service equipment, small parts and flight components result in waste streams consisting of toxic chemicals, spent media blast materials, and waste water. When chemicals are used in these processes they are typically high in volatile organic compounds (VOC) and are considered hazardous air pollutants (HAP). When blast media is used, the volume of hazardous waste generated is increased significantly. Many of the coatings historically used within NASA contain toxic metals such as hexavalent chromium, and lead. These materials are highly regulated and restrictions on worker exposure continue to increase. Most recently the Occupational Safety and Health Administration (OSHA) reduced the permissible exposure limit (PEL) for hexavalent chromium (CrVI) from 52 to 5 micrograms per cubic meter of air as an 8-hour time-weighted average. Hexavalent chromium is found in numerous pretreatment and primer coatings used within the Space Shuttle Program. In response to the need to continue to protect assets within the agency and the growing concern over these new regulations, NASA is researching different ways to continue the required maintenance of both facility and flight equipment in a safe, efficient, and environmentally preferable manner. The use of laser energy to prepare surfaces for a variety of processes, such as corrosion and coating removal, weld preparation, and non destructive evaluation (NDE) is a relatively new application of the technology that has been proven to be environmentally preferable and in many cases less labor intensive than currently used removal methods. The novel process eliminates VOCs and blast media and captures the removed coatings with an integrated vacuum system. This means that the only waste generated are the coatings that are removed, resulting in an overall cleaner process. The development of a Portable Laser Coating Removal System (PLCRS) started as the goal of a Joint Group on Pollution Prevention (JG-PP) project, led by the Air Force, where several types of lasers in several configurations were thoroughly evaluated. Following this project, NASA decided to evaluate the best performers on processes and coatings specific to the agency. Laser systems used during this project were all of a similar design, between 40 and 500 Watts, most of which had integrated vacuum systems in order to collect materials removed from substrate surfaces during operation.

Rothgeb, Matthew J↗
NASA NTRS2008

Final Report on Portable Laser Coating Removal Systems Field Demonstrations and Testing

Processes currently used throughout the National Aeronautics and Space Administration (NASA) to remove corrosion and coatings from structures, ground service equipment and small components results in waste streams consisting of toxic chemicals, spent media blast materials, and waste water. When chemicals are used in these processes they are typically high in volatile organic compounds (VOC) and are considered hazardous air pollutants (HAP). When blast media is used, the volume of hazardous waste generated is increased significantly. Many of the coatings historically used within NASA contain toxic metals such as hexavalent chromium, and lead. These materials are highly regulated and restrictions on worker exposure continue to increase. Most recently the EPA reduced the permissible exposure limit (PEL) for hexavalent chromium. The new standard lowers OSHA's PEL for hexavalent chromium from 52 to 5 micrograms of Cr(V1) per cubic meter of air as an 8-hour time-weighted average. Hexavalent chromium is found in the pretreatment and primer coatings used within the Shuttle Program. In response to the need to continue to protect assets within the agency and the growing concern over these new regulations, NASA is researching different ways to continue the required maintenance of both facility and flight equipment in a safe, efficient and environmentally preferable manner. The use of laser energy to remove prepare surfaces for a variety of processes, such as corrosion and coating removal, weld preparation and non destructive evaluation is a relatively new technology that has shown itself to be environmentally preferable and in many cases less labor intensive than currently used removal methods. The development of a Portable Laser Coating Removal System (PLCRS) started as the goal of a Joint Group on Pollution Prevention (JG-PP) project, led by the Air Force, where several types of lasers in several configurations were thoroughly evaluated. Following this project, NASA decided to evaluate the best performers on processes and coatings specific to the agency. Laser systems used during this project were all of a similar design, most of which had integrated vacuum systems in order to collect materials removed from substrate surfaces during operation. Due to the fact that the technology lends itself to a bide variety of processes, several site demonstrations were organized in order to allow for greater evaluation of the laser systems across NASA. The project consisted of an introductory demonstration and a more in-depth evaluation at Wright-Patterson Air Force Base. Additionally, field demonstrations occurred at Glenn Research Center and Kennedy Space Center. During these demonstrations several NASA specific applications were evaluated, including the removal of coatings within Orbiter tile cavities and Teflon from Space Shuttle Main Engine gaskets, removal of heavy grease from Solid Rocket Booster components and the removal of coatings on weld lines for Shuttle and general ground service equipment for non destructive evaluation (NDE). In addition, several general industry applications such as corrosion removal, structural coating removal, weld-line preparation and surface cleaning were evaluated. This included removal of coatings and corrosion from surfaces containing lead-based coatings and applications similar to launch-structure maintenance and Crawler maintenance. During the project lifecycle, an attempt was made to answer process specific concerns and questions as they arose. Some of these initially unexpected questions concerned the effects lasers might have on substrates used on flight equipment including strength, surface re-melting, substrate temperature and corrosion resistance effects. Additionally a concern was PPE required for operating such a system including eye, breathing and hearing protection. Most of these questions although not initially planned, were fully explored as a part of this project. Generally the results from tesng were very positive. Corrosion was effectively removed from steel, but less successfully from aluminum alloys. Coatings were able to be removed, with varying results, generally dark, matte and thin coatings were easier to remove. Steel and aluminum panels were able to be cleaned for welding, with no known deleterious effects and weld-lines were able to have coatings removed in critical areas for NDE while saving time as compared to other methods.

Rothgeb, Matthew J.↗
NASA NTRS2009

Combined MODIS/AMSR-E SST Composites for Regional Weather Applications

Recent applications of a high resolution MODlS composite SST product have clearly shown the importance of developing high-resolution SST data sets for coastal applications and modeling. In general, coupling between the oceans and atmospheres has been closely linked to SST gradients and fronts, indicating a need for high resolution SSTs, specifically in the areas of large gradients associated with coastal regions. Thus an accurate determination of SST gradients has become critical for determining the appropriate air-sea coupling and the influence on ocean modeling. Recent research is focused on improving the accuracy and spatial coverage of the current operational MODIS SST composite product provided by the Short-term Prediction Research and Transition (SPORT) project and distributed to the community. GHRSST-PP MODlS data and microwave AMSR-E data are being combined to produce composite data sets for both the West Coast and East Coast of the United States, including the Gulf of Mexico. The use of 1 km MODIS data has explicit advantages over other SST products including its global coverage and high resolution. The AMSR-E data will reduce the latency of the composites. A strategy for utilizing the error characteristics contained in the GHRSST data has been developed. This strategy will include using the error characteristics directly to calculate weights in the SST composites, uncertainty maps based on the composite biases and RMS errors, and latency products calculated in the compositing process. Recent accomplishments include the development of an enhanced compositing approach based on the error-weighted combination of recent clear MODIS SST values, where the error contributions come from measurement error, potential cloud contamination, and data latency sources. Future plans call for the inclusion of AMSR-E SST values with appropriate weights based upon measurement accuracy, MODIS-AMSR-E SST bias, and latency.

Jedlovec, Gary↗
NASA NTRS2008

The Photogrammetry Cube

We can determine distances between objects and points of interest in 3-D space to a useful degree of accuracy from a set of camera images by using multiple camera views and reference targets in the camera s field of view (FOV). The core of the software processing is based on the previously developed foreign-object debris vision trajectory software (see KSC Research and Technology 2004 Annual Report, pp. 2 5). The current version of this photogrammetry software includes the ability to calculate distances between any specified point pairs, the ability to process any number of reference targets and any number of camera images, user-friendly editing features, including zoom in/out, translate, and load/unload, routines to help mark reference points with a Find function, while comparing them with the reference point database file, and a comprehensive output report in HTML format. In this system, scene reference targets are replaced by a photogrammetry cube whose exterior surface contains multiple predetermined precision 2-D targets. Precise measurement of the cube s 2-D targets during the fabrication phase eliminates the need for measuring 3-D coordinates of reference target positions in the camera's FOV, using for example a survey theodolite or a Faroarm. Placing the 2-D targets on the cube s surface required the development of precise machining methods. In response, 2-D targets were embedded into the surface of the cube and then painted black for high contrast. A 12-inch collapsible cube was developed for room-size scenes. A 3-inch, solid, stainless-steel photogrammetry cube was also fabricated for photogrammetry analysis of small objects.

Source record↗
NASA NTRS2004

OCEANIDS: Autonomous Data Acquisition, Management and Distribution System

OCEANIDS is a clearinghouse for mission essential and near-real-time satellite data streams. This viewgraph presentation describes this mission, and includes the following topics: 1) OCEANIDS Motivation; 2) High-Level Architecture; 3) OCEANIDS Features; 4) OCEANIDS GUI: Nodes; 5) OCEANIDS GUI: Cluster; 6) Data Streams; 7) Statistics; and 8) GHRSST-PP.

automated monitoring↗
NASA NTRS2006

Noninvasive Diagnosis of Coronary Artery Disease Using 12-Lead High-Frequency Electrocardiograms

A noninvasive, sensitive method of diagnosing certain pathological conditions of the human heart involves computational processing of digitized electrocardiographic (ECG) signals acquired from a patient at all 12 conventional ECG electrode positions. In the processing, attention is focused on low-amplitude, high-frequency components of those portions of the ECG signals known in the art as QRS complexes. The unique contribution of this method lies in the utilization of signal features and combinations of signal features from various combinations of electrode positions, not reported previously, that have been found to be helpful in diagnosing coronary artery disease and such related pathological conditions as myocardial ischemia, myocardial infarction, and congestive heart failure. The electronic hardware and software used to acquire the QRS complexes and perform some preliminary analyses of their high-frequency components were summarized in Real-Time, High-Frequency QRS Electrocardiograph (MSC- 23154), NASA Tech Briefs, Vol. 27, No. 7 (July 2003), pp. 26-28. To recapitulate, signals from standard electrocardiograph electrodes are preamplified, then digitized at a sampling rate of 1,000 Hz, then analyzed by the software that detects R waves and QRS complexes and analyzes them from several perspectives. The software includes provisions for averaging signals over multiple beats and for special-purpose nonrecursive digital filters with specific low- and high-frequency cutoffs. These filters, applied to the averaged signal, effect a band-pass operation in the frequency range from 150 to 250 Hz. The output of the bandpass filter is the desired high-frequency QRS signal. Further processing is then performed in real time to obtain the beat-to-beat root mean square (RMS) voltage amplitude of the filtered signal, certain variations of the RMS voltage, and such standard measures as the heart rate and R-R interval at any given time. A key signal feature analyzed in the present method is the presence versus the absence of reduced-amplitude zones (RAZs). In terms that must be simplified for the sake of brevity, an RAZ comprises several cycles of a high-frequency QRS signal during which the amplitude of the high-frequency oscillation in a portion of the signal is abnormally low (see figure). A given signal sample exhibiting an interval of reduced amplitude may or may not be classified as an RAZ, depending on quantitative criteria regarding peaks and troughs within the reduced-amplitude portion of the high-frequency QRS signal. This analysis is performed in all 12 leads in real time.

Schlegel, Todd T.↗
NASA NTRS2006

Mars Technology Program: Planetary Protection Technology Development

This slide presentation reviews the development of Planetary Protection Technology in the Mars Technology Program. The goal of the program is to develop technologies that will enable NASA to build, launch, and operate a mission that has subsystems with different Planetary Protection (PP) classifications, specifically for operating a Category IVb-equivalent subsystem from a Category IVa platform. The IVa category of planetary protection requires bioburden reduction (i.e., no sterilization is required) The IVb category in addition to IVa requirements: (i.e., terminal sterilization of spacecraft is required). The differences between the categories are further reviewed.

Mars Technology Program↗
NASA NTRS2010

The Effect of Cross Flow on Slat Noise

This paper continues the computational examination (AIAA Journal, Vol. 45, No. 9, 2007, pp. 2174-2186) of the unsteady flow within the slat cove region of a multi-element high-lift airfoil configuration. Two simulations have been performed to examine the effect of cross flow on the near-field fluctuations and far-field acoustics. The cross flow was imposed by changing the free-stream velocity vector and modifying the Reynolds number. The cross flow does appear to alter the dynamics in the cove region, but the impact on the noise seems to be more dependent on the flow conditions. However, separating out the true effects of the cross flow from those of the Mach and Reynolds number would require additional calculations to isolate those effects.

Lockard, David P.↗