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At least 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Inspection of aging aircraft: A manufacturer's perspective

Douglas, in conjunction with operators and regulators, has established interrelated programs to identify and address issues regarding inspection of aging aircraft. These inspection programs consist of the following: Supplemental Inspection Documents; Corrosion Prevention and Control Documents; Repair Assessment Documents; and Service Bulletin Compliance Documents. In addition, airframe manufacturers perform extended airframe fatigue tests to deal with potential problems before they can develop in the fleet. Lastly, nondestructive inspection (NDI) plays a role in all these programs through the detection of cracks, corrosion, and disbonds. However, improved and more cost effective NDI methods are needed. Some methods such as magneto-optic imaging, electronic shearography, Diffractor-Sight, and multi-parameter eddy current testing appear viable for near-term improvements in NDI of aging aircraft.

Aging Aircraft↗
NASA NTRS1991

Aging aircraft NDI Development and Demonstration Center (AANC): An overview

A major center with emphasis on validation of nondestructive inspection (NDI) techniques for aging aircraft, the Aging Aircraft NDI Development and Demonstration Center (AANC), has been funded by the FAA at Sandia National Laboratories. The Center has been assigned specific tasks in developing techniques for the nondestructive inspection of static engine parts, assessing inspection reliability (POD experiments), developing testbeds for NDI validation, maintaining a FAA library of characterized aircraft structural test specimens, and leasing a hangar to house a high flight cycle transport aircraft for use as a full scale test bed.

Aging Aircraft↗
NASA NTRS1991

The FAA aging airplane program plan for transport aircraft

The FAA Aging Airplane Program is focused on five program areas: maintenance, transport airplanes, commuter airplanes, airplane engines, and research. These programs are complementary and concurrent, and have been in effect since 1988. The programs address the aging airplane challenge through different methods, including policies, procedures, and hardware development. Each program is carefully monitored and its progress tracked to ensure that the needs of the FAA, the industry, and the flying public are being met.

Aging Aircraft↗
NASA NTRS1991

Ageing aircraft research in the Netherlands

The problems of Ageing Aircraft are worldwide. Hence, actions to overcome or prevent these problems should be taken in international collaboration. The Federal Aviation Administration FAA and the Netherlands Civil Aviation Department RLD have signed a Memorandum of Cooperation in the area of structural integrity, with specific reference to research on problems in the area of Ageing Aircraft. This paper gives an overview of the Research currently carried out on this subject in the Netherlands. The work described is largely done at the National Aerospace Laboratory NLR. The major part is done under contracts with RLD and the FAA, as part of forementioned cooperation agreement.

Aging Aircraft↗
NASA NTRS1991

Aging commuter aeroplanes: Fatigue evaluation and control methods

The risks associated with old aeroplanes arise in the main from the difficulty of obtaining support from the manufacturer and other skilled people, and from a general loss of reliability caused by wear and other deterioration. The loss of reliability is caused by two broad classes of problem. There are those problems which are self evident, and hazardous rather than catastrophic. These are the problem areas where characteristically there have been multiple overhauls, repairs, and replacements, and where aging really means the results of repair ineffectiveness that accumulates. The other class of problem is the insidious and potentially catastrophic class. It includes the progressive deterioration of items which are not maintained, and often cannot be maintained because the deterioration cannot be seen. It includes loss of physical properties in adhesives and other organic compounds, corrosion, and the response to repeated loads. This paper deals with a currently unnecessarily troublesome aspect of that response. The present working definition of "commuter aeroplanes" encompasses a wide range of aging types, from the Fairchild F27, through deHavilland Canada Twin Otters to the smaller twin engined Piper and Cessna models. It includes such types as the Lockheed 10, the Beech 18, and the Grumman Mallard. Although we must remain concerned about those types which have been certificated under a design standard or operational rule which embodies the elementary fail-safe concept and which have not been subjected to a subsequent structural audit, this paper is directed, in the first instance, towards types for which fatigue and damage tolerance evaluation was not required as a condition of certification. It will be seen, however, that the principles are robust enough for more general application.

Aging Aircraft↗
NASA NTRS1996

Power law behavior of RR-interval variability in healthy middle-aged persons, patients with recent acute myocardial infarction, and patients with heart transplants

BACKGROUND. The purposes of the present study were (1) to establish normal values for the regression of log(power) on log(frequency) for, RR-interval fluctuations in healthy middle-aged persons, (2) to determine the effects of myocardial infarction on the regression of log(power) on log(frequency), (3) to determine the effect of cardiac denervation on the regression of log(power) on log(frequency), and (4) to assess the ability of power law regression parameters to predict death after myocardial infarction. METHODS AND RESULTS. We studied three groups: (1) 715 patients with recent myocardial infarction; (2) 274 healthy persons age and sex matched to the infarct sample; and (3) 19 patients with heart transplants. Twenty-four-hour RR-interval power spectra were computed using fast Fourier transforms and log(power) was regressed on log(frequency) between 10(-4) and 10(-2) Hz. There was a power law relation between log(power) and log(frequency). That is, the function described a descending straight line that had a slope of approximately -1 in healthy subjects. For the myocardial infarction group, the regression line for log(power) on log(frequency) was shifted downward and had a steeper negative slope (-1.15). The transplant (denervated) group showed a larger downward shift in the regression line and a much steeper negative slope (-2.08). The correlation between traditional power spectral bands and slope was weak, and that with log(power) at 10(-4) Hz was only moderate. Slope and log(power) at 10(-4) Hz were used to predict mortality and were compared with the predictive value of traditional power spectral bands. Slope and log(power) at 10(-4) Hz were excellent predictors of all-cause mortality or arrhythmic death. To optimize the prediction of death, we calculated a log(power) intercept that was uncorrelated with the slope of the power law regression line. We found that the combination of slope and zero-correlation log(power) was an outstanding predictor, with a relative risk of > 10, and was better than any combination of the traditional power spectral bands. The combination of slope and log(power) at 10(-4) Hz also was an excellent predictor of death after myocardial infarction. CONCLUSIONS. Myocardial infarction or denervation of the heart causes a steeper slope and decreased height of the power law regression relation between log(power) and log(frequency) of RR-interval fluctuations. Individually and, especially, combined, the power law regression parameters are excellent predictors of death of any cause or arrhythmic death and predict these outcomes better than the traditional power spectral bands.

Non-NASA Center↗
NASA NTRS2016

Aging Will Amplify the Heat-Related Mortality Risk Under a Changing Climate: Projection for the Elderly in Beijing, China

An aging population could substantially enhance the burden of heat-related health risks in a warming climate because of their higher susceptibility to extreme heat health effects. Here, we project heatrelated mortality for adults 65 years and older in Beijing China across 31 downscaled climate models and 2 representative concentration pathways (RCPs) in the 2020s, 2050s, and 2080s. Under a scenario of medium population and RCP8.5, by the 2080s, Beijing is projected to experience 14,401 heat-related deaths per year for elderly individuals, which is a 264.9% increase compared with the 1980s. These impacts could be moderated through adaptation. In the 2080s, even with the 30% and 50% adaptation rate assumed in our study, the increase in heat-related death is approximately 7.4 times and 1.3 times larger than in the 1980s respectively under a scenario of high population and RCP8.5. These findings could assist countries in establishing public health intervention policies for the dual problems of climate change and aging population. Examples could include ensuring facilities with large elderly populations are protected from extreme heat (for example through back-up power supplies and/or passive cooling) and using databases and community networks to ensure the home-bound elderly are safe during extreme heat events.

age factor↗
NASA NTRS2018

The Little Ice Age and Human-Environmental Interactions in the Central Balkans: Insights from a New Serbian Paleorecord

This paper presents a 600-year well-dated, high-resolution Central Balkan paleo-record including the Little Ice Age (LIA; 1450-850 CE). Utilizing pollen-based REVEALS modelling estimates, geochemical indicators, rarefaction analyses and the AMS 14C-based Bacon age model, this first-hand record from the Sava Basin reveals the transformation of the Central Balkan landscape involving linkages between changing climatic and socio-political regimes. The pre-LIA interval (1370-1418 CE) in the Sava Region reveals a wooded steppe and increased cultivation under warmer/stable climatic and socio-political conditions. In contrast, the LIA interval in the region is expressed through continuous transitions between forest and grassland, extensive land erosion and stressed agriculture, potentially as a collective artifact of the climatic variability and human impact associated with socio- political stressors of the time. The post-LIA/Industrial Era interval (1850-2012 CE) in the Sava Region shows an overall increase in woodland as well as agriculture following the exit of the Ottomans. However, increased population pressures and the subsequent onset of the Industrial Revolution as well as increased trade led to intense deforestation throughout the 20th Century, which continued during the Socialist period.

Societal impacts of climate change↗
NASA NTRS1963

Proceedings of the Conference on Space-Age Planning: A Part of the Third National Conference on the Peaceful Uses of Space, Chicago, May 1-9, 1963

The Space-Age Planning sessions of the Third National Conference on the Peaceful Uses of Space have been planned by its principal sponsors-the National Aeronautics and Space Administration and the Mayor's Committee for Economic and Cultural Development of Chicago-and the 17 regional participating agencies to meet varied interests and contribute to future planning and profit. Its objectives are as follow: (1) To develop widespread local and regional interest in every phase of man's relationship to outer space (2) To bring about maximum utilization of regional industrial and educational resources in the Nation's space program (3) To obtain full utilization by regional industries and universities of the spin-off research that the Space Age is generating. The papers presented herein are concerned with exploration of space, man in space, the university-industry partnership in space programs, how space activities are changing the economy, business opportunities from space research, the placement and management of research and development projects, and the opportunities and challenges in space procurement.

NASA PROGRAM↗
NASA NTRS1972

U, Th, Pb and REE abundances and Pb 207/Pb 206 ages of individual minerals in returned lunar material by ion microprobe mass analysis.

Results of ion microprobe analyses of Apollo 11, 12 and 14 material, showing that U, Th, Pb and REE are concentrated in accessory minerals such as apatite, whitlockite, zircon, baddeleyite, zirkelite, and tranquillityite. Th/U ratios are found to vary by over a factor of 40 in these minerals. K, Ba, Rb and Sr have been localized in a K rich, U and Th poor glass phase that is commonly associated with the U and Th bearing accessory minerals. Li is observed to be fairly evenly distributed between the various accessory phases. The phosphates have been found to have REE abundance patterns (normalized to the chondrite abundances) that are fairly flat, while the Zr bearing minerals have patterns that rise steeply, by factors of ten or more, from La to Gd. All the accessory minerals have large negative Eu anomalies. Radiometric age dates (Pb 207/Pb 206) of the individual U and Th bearing minerals compare favorably with the Pb 207/Pb 206 age of the bulk rocks.

Andersen, C. A.↗
NASA NTRS1972

Study of X-ray diffraction on aging alloys with different degrees of volume discrepancy between the precipitation phase and the matrix

Study of the diffraction patterns of X rays diffracted by dispersion-hardened alloys with various degrees of difference between the specific atomic volumes of their precipitation phases and matrices. Experiments were performed on aging alloys KhN77TIuR (nimonic) and KhN67VMTIuO, which have the same types of gamma solid solutions and precipitating gamma prime phases, but differ considerably with respect to the volume factor. It is found that in the decay of supersaturated solid solutions for which the difference between the specific atomic volumes of the precipitation phase and the matrix is small (alloy KhN67VMTIuO) the nature of the intensity distribution of the diffraction lines remains practically unchanged regardless of the aging, while in cases where the volume discrepancy is large (alloy KhN77TIuR) significant changes in the appearance of the diffraction lines are recorded.-

Gitgarts, M. I.↗
NASA NTRS1972

Effect of set size, age, and mode of stimulus presentation on information-processing speed.

First, second, and third grade pupils served as subjects in an experiment designed to show the effect of age, mode of stimulus presentation, and information value on recognition time. Stimuli were presented in picture and printed word form and in groups of 2, 4, and 8. The results of the study indicate that first graders are slower than second and third graders who are nearly equal. There is a gross shift in reaction time as a function of mode of stimulus presentation with increase in age. The first graders take much longer to identify words than pictures, while the reverse is true of the older groups. With regard to set size, a slope appears in the pictures condition in the older groups, while for first graders, a large slope occurs in the words condition and only a much smaller one for pictures.

Norton, J. C.↗
NASA NTRS1972

Metallurgical evaluation of factors influencing the ductility of aged T-111

The metallurgical factors influencing the ductility of T-111 (Ta-8W-2Hf) alloy following long-time exposures of GTA welds and tubing in the temperature range 982 C (1800 F) through 1316 C (2400 F) were evaluated by means of scanning and transmission electron microscopy, Auger electron emission spectroscopy, and optical metallographic procedures. No classical aging response occurs in the alloy over the temperature range studied. The ductility impairment implied by previous investigations is not the result of microstructural response of the alloy to thermal exposures. Intergranular failure in the GTA sheet welds appears the result of random contamination by silicon, potassium, and/or fluorine at the grain boundaries of the fusion zones. Exposure to lithium at high temperatures had no adverse effects on the ductility of T-111 tubing. These materials were, however, sensitive to post-age handling and testing procedures.

Gold, R. E.↗
NASA NTRS1972

The Rb-Sr age of a crystalline rock from Apollo 16.

Sample 68415 is one of the few large crystalline rocks returned from Apollo 16. A meaningful age may be obtained if the sample studied represents silicate material which was isotopically homogenized at the last time it was melted. It is also assumed that the constituent phases of the sample have remained closed systems subsequent to that time. The material was crushed and separated into different fractions with the aid of heavy liquids. It was found that the mineral separates are mixtures of at least three distinct phases with intrinsically different Rb/Sr ratios. An age of 3.84 aeon was determined.

Papanastassiou, D. A.↗
NASA NTRS1972

The ages of lunar material from Fra Mauro, Hadley Rille, and Spur Crater.

Ar-40/Ar-39 dating techniques were applied to estimate the age of twelve crystalline and fragmented Fra Mauro rock samples and six Hadley Rille and Spur Crater rock samples provided by the Apollo 14 and 15 missions. Genesis histories of some associated lunar surface features are traced back on the basis of obtained rock age values.

Husain, L.↗
NASA NTRS1972

Exposure ages and neutron capture record in lunar samples from Fra Mauro.

Cosmic-ray exposure ages of Apollo 14 rocks and rock fragments obtained by the Kr81-Kr83 method range from 27 to 700 m.y. Rock 14321, collected near the Cone crater rim, is one of the many approximately 27 m.y. old ejecta which were reported at the Third Lunar Science Conference. All the other rocks have considerably higher exposure ages. Isotopic anomalies from neutron capture in gadolinium, bromine, and barium are used to obtain information on the lunar neutron spectrum at various depths below the lunar surface. The flux ratio of resonance and slow (less than 0.3 eV) neutrons is found to be nearly constant in the topmost approximately 100 g/sq cm.

Lugmair, G. W.↗
NASA NTRS1973

Crater frequency age determinations for the proposed Apollo 17 site at Taurus-Littrow.

On the assumption that the vast majority of craters are of impact origin, relative age dates can be obtained by counting craters. Returned lunar samples are helping to resolve problems regarding the magnitude of the meteoritic flux. The samples provide a means for empirically calibrating crater count data. The characteristics of the Taurus-Littrow area are considered, giving attention to four different units. The crater frequency distribution is discussed, together with its significance for the age of the corresponding lunar features.

Greeley, R.↗