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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Dynamic balance control in elders: gait initiation assessment as a screening tool

OBJECTIVE: To determine whether measurements of center of gravity-center of pressure separation (CG-CP moment arm) during gait initiation can differentiate healthy from disabled subjects with sufficient specificity and sensitivity to be useful as a screening test for dynamic balance in elderly patients. SUBJECTS: Three groups of elderly subjects (age, 74.97+/-6.56 yrs): healthy elders (HE, n = 21), disabled elders (DE, n = 20), and elders with vestibular hypofunction (VH, n = 18). DESIGN: Cross-sectional, intact-groups research design. Peak CG-CP moment arm measures how far the subject will tolerate the whole-body CG to deviate from the ground reaction force's CP; it represents dynamic balance control. Screening test cutoff points at 16 to 18 cm peak CG-CP moment arm predicted group membership. RESULTS: The magnitude of peak CG-CP moment arm was significantly greater in HE than in DE and VH subjects (p<.01) and was not different between the DE and VH groups. The peak CG-CP moment arm occurred at the end of single stance phase in all groups. As a screening test, the peak moment arm has greater than 50% sensitivity and specificity to discriminate the HE group from the DE and VH groups with peak CG-CP moment arm cutoff points between 16 and 18 cm. CONCLUSIONS: Examining dynamic balance through the use of the CG-CP moment arm during single stance in gait initiation discriminates between nondisabled and disabled older persons and warrants further investigation as a potential tool to identify people with balance dysfunction.

NASA Discipline Neuroscience↗
NASA NTRS2004

CFD: A Castle in the Sand?

The computational simulation community is not routinely publishing independently verifiable tests to accompany new models or algorithms. A survey reveals that only 22% of new models published are accompanied by tests suitable for independently verifying the new model. As the community develops larger codes with increased functionality, and hence increased complexity in terms of the number of building block components and their interactions, it becomes prohibitively expensive for each development group to derive the appropriate tests for each component. Therefore, the computational simulation community is building its collective castle on a very shaky foundation of components with unpublished and unrepeatable verification tests. The computational simulation community needs to begin publishing component level verification tests before the tide of complexity undermines its foundation.

Kleb, William L.↗
NASA NTRS2007

50 Years of Electronic Check Out and Launch Systems at Kennedy Space Center

When NASA was created in 1958 one of the elements incorporated into this new agency was the Army Ballistic Missile Agency (ABMA) in Huntsville, AL and its subordinate Missile Firing Laboratory (MFL) in Cape Canaveral. Under NASA, the MFL became the Launch Operations Directorate of the George C. Marshall Space Flight Center in Huntsville, but expanding operations in the build up to Apollo dictated that it be given the status of a full fledged Center in July, 1 962[ 1]. The next year it was renamed the John F. Kennedy Space Center (KS C) after the president whose vision transformed its first decade of operation. The ABMA was under the technical leadership of Dr. Werner Von Braun. The MEL was run by his deputy Dr. Kurt Debus, an electrical engineer whose experience in the field began in the early days of V-2 testing in war time Germany. In 1952 a group led by Debus arrived in Cape Canaveral to begin test launches of the new Redstone missile [2]. During the 50's, The MFL built several launch complexes and tested the Redstone, Jupiter and Jupiter C missiles. This small experienced team of engineers and technicians formed the seed from which has grown the KSC team of today. This article briefly reviews the evolution of the KSC electronic technologies for integration, check-out and launch of space vehicles and payloads during NASA's first 50 years.

Starr, Stanley O.↗
NASA NTRS1977

Results of closed cycle MHD power generation tests with a helium-cesium working fluid

The cross-sectional dimensions of the MHD channel in the NASA Lewis closed loop facility have been reduced to 3.8 x 11.4 cm. Tests were run in this channel using a helium-cesium working fluid at stagnation pressures of 1.6 x 10 to the 5th N/sq m, stagnation temperatures of 2000-2060 K and an entrance Mach number of 0.36. In these tests Faraday open circuit voltages of 200 V were measured which correspond to a Faraday field of 1750 V/m. Power generation tests were run for different groups of electrode configurations and channel lengths. Hall fields up to 1450 V/m were generated. Power extraction per electrode of 183 W and power densities of 1.7 MW/cu m have been obtained. A total power output of 2 kW was generated for tests with 14 electrodes. The power densities obtained in this channel represent a factor of 3 improvement over those reported for the m = 0.2 channel at the last EAM Symposium.

Sovie, R. J.↗
NASA NTRS1997

Development of an Antimicrobial Susceptibility Testing Method Suitable for Performing During Space Flight

Very little is known regarding the affects of the microgravity environment of space flight upon the action of antimicrobial agents on bacterial pathogens. This study was undertaken to develop a simple method for conducting antibacterial susceptibility tests during a Space Shuttle mission. Specially prepared susceptibility test research cards (bioMerieux Vitek, Hazelwood, MO) were designed to include 6-11 serial two-fold dilutions of 14 antimicrobial agents, including penicillins, cephalosporins, a Beta-lactamase inhibitor, vancomycin, erythromycin, tetracycline, gentamicin, ciprofloxacin, and trimethoprim/sulfamethoxazole. Minimal inhibitory concentrations (MICS) of the drugs were determined by visual reading of color endpoints in the Vitek research cards made possible by incorporation of a colorimetric growth indicator (alamarBlue(Trademark), Accumed International, Westlake, OH). This study has demonstrated reproducible susceptibility results when testing isolates of Staphylococcus aurezis, Group A Streptococcus, Enterococcusfaecalis, Escherichia coli (beta-lactamase positive and negative strains), Klebsiella pneumoniae, Enterobacter cloacae, and Pseudomoiias aeruginosa. In some instances, the MICs were comparable to those determined using a standard broth microdilution method, while in some cases the unique test media and format yielded slightly different values, that were themselves reproducible. The proposed in-flight experiment will include inoculation of the Vitek cards on the ground prior to launch of the Space Shuttle, storage of inoculated cards at refrigeration temperature aboard the Space Shuttle until experiment initiation, then incubation of the cards for 18-48 h prior to visual interpretation of MICs by the mission's astronauts. Ground-based studies have shown reproducible MICs following storage of inoculated cards for 7 days at 4-8 C to accommodate the mission's time schedule and the astronauts' activities. For comparison, ground-based control (normal gravity) MIC values will be generated by simultaneous inoculation and incubation of a second set of test cards in a laboratory at the launch site. This procedure can provide a safe and compact experiment that should yield new information on the affects of microgravity on the biological activities of various classes of antibiotics.

Jorgensen, James H.↗
NASA NTRS2002

Rodent Biocompatibility Test Using the NASA Foodbar and Epoxy EP21LV

Epoxy has been used successfully to affix NASA foodbars to the inner walls of the Animal Enclosure Module for past space flight experiments utilizing rodents. The epoxy used on past missions was discontinued, making it necessary to identify a new epoxy for use on the STS-108 and STS-107 missions. This experiment was designed to test the basic biocompatibility of epoxy EP21LV with male rats (Sprague Dawley) and mice (Swiss Webster) when applied to NASA foodbars. For each species, the test was conducted with a control group fed untreated foodbars and an experimental group fed foodbars applied with EP21LV. For each species, there were no group differences in animal health and no statistical differences (P<0.05) in body weights throughout the study. In mice, there was a 16% increase in heart weight in the epoxy group; this result was not found in rats. For both species, there were no statistical differences found in other organ weights measured. In rats, blood glucose levels were 15% higher and both total protein and globulin were 10% lower in the epoxy group. Statistical differences in these parameters were not found in mice. For both species, no statistical differences were found in other blood parameters tested. Food consumption was not different in rats but water consumption was significantly decreased 10 to 15% in the epoxy group. The difference in water consumption is likely due to an increased water content of the epoxy-treated foodbars. Finally, both species avoided consumption of the epoxy material. Based on the global analysis of the results, the few parameters found to be statistically different do not appear to be a physiologically relevant effect of the epoxy material, We conclude that the EP21LV epoxy is biocompatible with rodents.

Tillman, J.↗
NASA NTRS2005

Digital Audio Radio Broadcast Systems Laboratory Testing Nearly Complete

Radio history continues to be made at the NASA Lewis Research Center with the completion of phase one of the digital audio radio (DAR) testing conducted by the Consumer Electronics Group of the Electronic Industries Association. This satellite, satellite/terrestrial, and terrestrial digital technology will open up new audio broadcasting opportunities both domestically and worldwide. It will significantly improve the current quality of amplitude-modulated/frequency-modulated (AM/FM) radio with a new digitally modulated radio signal and will introduce true compact-disc-quality (CD-quality) sound for the first time. Lewis is hosting the laboratory testing of seven proposed digital audio radio systems and modes. Two of the proposed systems operate in two modes each, making a total of nine systems being tested. The nine systems are divided into the following types of transmission: in-band on-channel (IBOC), in-band adjacent-channel (IBAC), and new bands. The laboratory testing was conducted by the Consumer Electronics Group of the Electronic Industries Association. Subjective assessments of the audio recordings for each of the nine systems was conducted by the Communications Research Center in Ottawa, Canada, under contract to the Electronic Industries Association. The Communications Research Center has the only CCIR-qualified (Consultative Committee for International Radio) audio testing facility in North America. The main goals of the U.S. testing process are to (1) provide technical data to the Federal Communication Commission (FCC) so that it can establish a standard for digital audio receivers and transmitters and (2) provide the receiver and transmitter industries with the proper standards upon which to build their equipment. In addition, the data will be forwarded to the International Telecommunications Union to help in the establishment of international standards for digital audio receivers and transmitters, thus allowing U.S. manufacturers to compete in the world market.

Source record↗
DOE OSTI2019

The Role of Adjuvant Radiotherapy in the Treatment of Pleural Mesothelioma

Background: Pleural mesothelioma is a rare but aggressive form of cancer. Local recurrence represents the majority of treatment failures and overall survival (OS) outcomes remain dismal. Adding locoregional treatment with radiotherapy after surgical resection has been considered but its role remains uncertain. Objective: The purpose of this study was to evaluate the outcomes of adjuvant radiation therapy (RT) for patients with malignant pleural mesothelioma. Methods: The National Cancer Data Base (NCDB) was queried (2004–2013) for patients with malignant mesothelioma. Patients were divided into three groups: observation, surgery alone, and surgery followed by adjuvant RT. Statistics included Fisher’s exact or Chi square tests to analyze categorical proportions between groups, Kaplan–Meier analysis to evaluate OS, and Cox proportional hazards modeling to determine variables associated with OS. Propensity matching was performed to make comparisons between homogenous groups. Results: Overall, the surgery plus radiotherapy group had a higher median survival (21.4 months) compared with surgery alone (16.59 months) [p < 0.001]. RT was more likely to be delivered after extrapleural pneumonectomy than with lung-sparing surgical approaches. On multivariable analysis, receipt of surgery plus radiotherapy, chemotherapy administration, and higher socioeconomic status were associated with improved OS (p < 0.0001). After propensity matching, receipt of surgery plus radiotherapy and chemotherapy administration were still associated with improved OS (p < 0.05). Conclusions: In the treatment of malignant pleural mesothelioma, adjuvant radiotherapy after surgical intervention was associated with improved OS. This study is the largest study of adjuvant radiotherapy to date, and our findings highlight the need for additional prospective data.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
NASA NTRS2004

Test Planning Approach and Lessons

As NASA began technology risk reduction activities and planning for the next generation launch vehicle under the Space Launch Initiative (SLI), now the Next Generation Launch Technology (NGLT) Program, a review of past large liquid rocket engine development programs was performed. The intent of the review was to identify any significant lessons from the development testing programs that could be applied to current and future engine development programs. Because the primary prototype engine in design at the time of this study was the Boeing-Rocketdyne RS-84, the study was slightly biased towards LOX/RP-1 liquid propellant engines. However, the significant lessons identified are universal. It is anticipated that these lessons will serve as a reference for test planning in the Engine Systems Group at Marshall Space Flight Center (MSFC). Towards the end of F-1 and J-2 engine development testing, NASA/MSFC asked Rocketdyne to review those test programs. The result was a document titled, Study to Accelerate Development by Test of a Rocket Engine (R-8099). The "intent (of this study) is to apply this thinking and learning to more efficiently develop rocket engines to high reliability with improved cost effectivenes" Additionally, several other engine programs were reviewed - such as SSME, NSTS, STME, MC-1, and RS-83- to support or refute the R-8099. R-8099 revealed two primary lessons for test planning, which were supported by the other engine development programs. First, engine development programs can benefit from arranging the test program for engine system testing as early as feasible. The best test for determining environments is at the system level, the closest to the operational flight environment. Secondly, the component testing, which tends to be elaborate, should instead be geared towards reducing risk to enable system test. Technical risk can be reduced at the component level, but the design can only be truly verified and validated after engine system testing.

Parkinson, Douglas A.↗
NASA NTRS1991

Effect of two synthetic lubricants on life of AISI 9310 spur gears

Spur-gear fatigue tests were conducted with two lubricants using a single lot of consumable-electrode vacuum-melted (CVM) AISI 9310 spur gears. The gears were case carburized and hardened to Rockwell C60. The gear pitch diameter was 8.89 cm. The lot of gears was divided into two groups, each of which was tested with a different lubricant. The test lubricants can be classified as synthetic polyol-ester-based lubricants. One lubricant was 30 percent more viscous that the other. Both lubricants have similar pressure viscosity coefficients. Test conditions included a bulk gear temperature of 350 K, a maximum Hertz stress of 1.71 GPa at the pitch line, and a speed of 10,000 rpm. The surface fatigue life of gears tested with one lubricant was approximately 2.4 times that for gears tested with the other lubricant. The lubricant with the 30 percent higher viscosity gave a calculated elastohydrodynamic (EHD) film thickness that was 20 percent higher than the other lubricant. This increased EHD film thickness is the most probable reason for the improvement in surface fatigue life of gears tested with this lubricant over gears tested with the less viscous lubricant.

Townsend, Dennis P.↗
DOE OSTI2023

Ampaire ARPA-e Electric Flight Testbed

A hybrid-electric aircraft flying testbed was developed in this program with the intent to serve as a dedicated, enduring testbed to test and evaluate ARPA-e CIRCUITS Program and other electrified aviation technologies in relevant flight environments. This testbed enabled rapid development cycles of novel and innovative technologies in the electrified aviation space, maturing them from a research lab environment to flying in an aircraft. By providing research groups with the means to test their transformative technologies in a real-world, aircraft environment, the path to validating the safety and reliability of their technologies for future commercial opportunities was greatly accelerated. Three core technologies were integrated and tested: an inverter/motor drive built by the University of Arkansas, a solid-state circuit breaker (iBreaker) built by the Illinois Institute of Technology, and a Flying Capacitor Multi-level (FCML) DC/DC converter built by the University of California, Berkeley. In each of these cases, the requirements established for safety of flight resulted in a holistic approach to the designs, evoking a deeper understanding of the potential failure modes and mitigations necessary to build a robust and flightworthy system. Further, the integration into a hybrid-electric aircraft de-risked the potential electrical and mechanical issues that cannot easily be experienced or replicated in a lab environment. The experiments were also required to undergo representative temperature, shock, and vibration testing as the FAA prescribes for this category of aircraft, facilitating familiarity with the relevant design and test guidelines necessary to commercialize the technologies. This testbed unlocks the massive potential of core power electronics technologies necessary for a safe, robust, and efficient electric aviation future. With quick iterative design, test, and flight cycles, these core technologies are on a quicker path to technology readiness level maturity and commercialization, enabling a more sustainable future for the aviation industry.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS2000

Autogenic-feedback training exercise is superior to promethazine for control of motion sickness symptoms

Motion sickness symptoms affect approximately 50% of the crew during space travel and are commonly treated with intramuscular injections of promethazine. The purpose of this paper is to compare the effectiveness of three treatments for motion sickness: intramuscular injections (i.m.) of promethazine, a physiological training method (autogenic-feedback training exercise [AFTE]), and a no-treatment control. An earlier study tested the effects of promethazine on cognitive and psychomotor performance and motion sickness tolerance in a rotating chair. For the present paper, motion sickness tolerance, symptom reports, and physiological responses of these subjects were compared to matched subjects selected from an existing database who received either AFTE or no treatment. Three groups of 11 men, between the ages of 33 and 40 years, were matched on the number of rotations tolerated during their initial rotating-chair motion sickness test. The motion sickness test procedures and the 7-day interval between tests were the same for all subjects. The drug group was tested under four treatment conditions: baseline (no injections), a 25 mg dose of promethazine, a 50 mg dose of promethazine, and a placebo of sterile saline. AFTE subjects were given four 30-minute AFTE sessions before their second, third, and fourth motion sickness tests (6 hours total). The no-treatment control subjects were only given the four rotating-chair tests. Motion sickness tolerance was significantly increased after 4 hours of AFTE when compared to either 25 mg (p < 0.00003) or 50 mg (p < 0.00001) of promethazine. The control and promethazine groups did not differ. AFTE subjects reported fewer or no symptoms at higher rotational velocities than subjects in the control or promethazine groups. The primary physiological effect of promethazine was an inhibition of skin conductance level. The AFTE group showed significantly less heart rate and skin conductance variability during motion sickness tests administered after training.

Clinical Trial↗
NASA NTRS2005

Simulated Space Environment Effects on the Blocking Force of Silicone Adhesive

The International Space Station (ISS) solar arrays utilize MD-944 diode tape to protect the underlying diodes in the solar array panel circuit and also provide thermal conditioning and mechanical support. The diode tape consists of silicone pressure sensitive adhesive (Dow Coming QC-7725) with a protective Kapton over-layer. On-orbit, the Kapton over-layer will erode under exposure to atomic oxygen (AO) and the underlying exposed silicone adhesive will ultimately convert, under additional AO exposure, to a glass like silicate. The current operational plan is to retract ISS solar array P6 and leave it stored under load for a long duration (6 months or more) during ISS assembly. With the Kapton over-layer eroded away, the exposed silicone adhesive must not cause the solar array to stick to itself or cause the solar array to fail during redeployment. Previous testing by Lockheed-Martin Space Systems (LMSS) characterized silicone blocking following exposure to low energy atomic oxygen (AO) in an asher facility, but this is believed to be conservative. An additional series of tests was performed by the Environmental Effects Group at MSFC under direction from the ISS Program Office Environments Team. This test series included high energy AO (5 eV), near ultraviolet (NUV) radiation and ionizing radiation, singly and in combination. Additional samples were exposed to thermal energy AO (<0.1 ev) for comparison to the LMSS tests. Diode tape samples were exposed to each environment constituent individually, put under preload for seven days and then the resulting blocking force was measured using a tensile machine. Additional samples were exposed to AO, NUV and electrons in series and then put under long term (three to ten months) preload to determine the effect of preload duration on the resulting blocking force of the silicone-to-silicone bond. Test results indicate that high energy AO, ultraviolet radiation and electron ionizing radiation exposure all reduce the blocking force for a silicone-to-silicone bond. AO exposure produces the most significant reduction in blocking force.

Boeder, Paul↗
NASA NTRS1996

Advanced Failure Determination Measurement Techniques Used in Thermal Fatigue Life Testing of Electronic Packaging

Thermal fatigue life testing of various electronic packaging technologies is being performed by the Reliability Technology Group at the Jet Propulsion Laboratory. These testing efforts are in progress to improve uderstanding of the reliability issues associated with low volume packaging technologies for space applications and to develop qualification and acceptance approaches for these technologies. The work described here outlines the electrical failure detection techniques used during testing by documenting the circuits and components used to make these measurements, the sensitivity of the measurements, and the applicability of each specific measurement.

fatigue surface mount measurement testing thermal ↗
DOE OSTI2020

Improving PGM-free ORR Electrocatalyst Activity: Suggestions from DFT Studies

In this opinion, the limitations of platinum group metal–free oxygen reduction reaction electrocatalyst activity based on scaling laws and resulting Balandin-Sabatier volcano plots are presented. Previous theoretical work aimed at overcoming this limitation is discussed. In this work, a theoretical study of a novel approach toward catalyst activity improvement, dynamic strain engineering, is proposed and tested for a possible platinum group metal–free oxygen reduction reaction active site. It is shown that not only can this approach produce thermodynamic limiting potentials well beyond scaling law relationship limits but also be capable of doing so in an energy-efficient manner.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Laboratory Infection of Novel Akhmeta Virus in CAST/EiJ Mice

Akhmeta virus is a zoonotic Orthopoxvirus first identified in 2013 in the country of Georgia. Subsequent ecological investigations in Georgia have found evidence that this virus is widespread in its geographic distribution within the country and in its host-range, with rodents likely involved in its circulation in the wild. Yet, little is known about the pathogenicity of this virus in rodents. We conducted the first laboratory infection of Akhmeta virus in CAST/EiJ Mus musculus to further characterize this novel virus. We found a dose-dependent effect on mortality and weight loss (p < 0.05). Anti-orthopoxvirus antibodies were detected in the second- and third-highest dose groups (5 × 104 pfu and 3 × 102 pfu) at euthanasia by day 10, and day 14 post-infection, respectively. Anti-orthopoxvirus antibodies were not detected in the highest dose group (3 × 106 pfu), which were euthanized at day 7 post-infection and had high viral load in tissues, suggesting they succumbed to disease prior to mounting an effective immune response. In order of highest burden, viable virus was detected in the nostril, lung, tail, liver and spleen. All individuals tested in the highest dose groups were DNAemic. Akhmeta virus was highly pathogenic in CAST/EiJ Mus musculus, causing 100% mortality when ≥3 × 102 pfu was administered.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1993

Double Cantilever Beam and End Notched Flexure Fracture Toughness Testing of Two Composite Materials

Two different unidirectional composite materials were provided by NASA Langley Research Center and tested by the Composite Materials Research Group within the Department of Mechanical Engineering at the University of Wyoming. Double cantilever beam and end notched flexure tests were performed to measure the mode I (crack opening) and mode II (sliding or shear) interlaminar fracture toughness of the two materials. The two composites consisted of IM7 carbon fiber combined with either RP46 resin toughened with special formulation of LaRC IA resin, known as JJS1356; or PES chain extended thermoplastic resin known as JJS1361. Double Cantilever Beam Specimen Configuration and Test Methods As received from NASA, the test specimens were nominally 0.5 inch wide, 6 inches long, and 0.2 inch thick. A 1 inch long Kapton insert at the midplane of one end of the specimen (placed during laminate fabrication) facilitated crack initiation and extension. It was noted that the specimens provided were smaller than the nominal 1.5 inch wide, 9.0 inch long configuration specified. Similarly, the Kapton inserts were of greater length than those in the present specimens. Hence, the data below should not be compared directly to those generated with the referenced methods. No preconditioning was performed on the specimens prior to testing. In general, the methodology was used for the present work. Crack opening loads were introduced to the specimens via piano hinges attached to the main specimen faces at a single end of each specimen. Hinges were bolted to the specimens using the technique presented. The cracks were extended a small distance from the end of the Kapton insert prior to testing. Just before precracking, the sides of the specimens were coated with water-soluble typewriter correction fluid to aid in crack visualization. Scribe marks were then made in the coating at half-inch intervals.

Kessler, Jeff A.↗
NASA NTRS1991

Evaluation of advanced lubricants for aircraft applications using gear surface fatigue tests

Surface pitting fatigue life tests were conducted with five lubricants, using spur gears made from a single lot of consumable-electrode vacuum melted (CVM) AISI 9310 steel. The gears were case carbonized and hardened to a Rockwell c-60 and finish ground. The gear pitch diameter was 8.89 cm. The lot of gears was divided into five groups, each of which was tested with a different lubricant. The test lubricants can be classified as synthetic polyol-esters with various viscosities and additive packages. Test conditions included bulk gear temperature of 350 K, a maximum Hertz stress of 1.71 GPa (248 ksi) at the pitch line, and a speed of 10,000 RPM. The lubricant with a viscosity that provided a specific film thickness greater than one and with an additive package produced far greater gear surface fatigue lives than lubricants with a viscosity that provided specific film thickness less than one. A low viscosity lubricant with an additive package produced gear surface fatigue lives equivalent to a similar base stock lubricant with 30 percent higher viscosity, but without an additive package. Lubricants with the same viscosity and similar additive packages gave equivalent gear surface fatigue lives.

Townsend, Dennis P.↗