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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Transfer functions

The vulnerability of electronic equipment to carbon fibers is studied. The effectiveness of interfaces, such as filters, doors, window screens, and cabinets, which affect the concentration, exposure, or deposition of carbon fibers on both (internal and external) sides of the interface is examined. The transfer function of multilayer aluminum mesh, wet and dry, polyurethane foam, and window screen are determined as a function of air velocity. FIlters installed in typical traffic control boxes and air conditioners are also considered.

Taback, I.↗
NASA NTRS1979

Surveys for sensitivity to fibers and potential impacts from fiber induced failures

The surveys for sensitivities to fibers and potential impacts from fiber induced failures begins with a review of the survey work completed to date and then describes an impact study involving four industrial installations located in Virginia. The observations and results from both the surveys and the study provide guidelines for future efforts. The survey work was done with three broad objectives: (1) identify the pieces of potentially vulnerable equipment as candidates for test; (2) support the transfer function work by gaining an understanding of how fibers could get into a building; and (3) support the economic analysis by understanding what would happen if fibers precipitated a failure in an item of equipment.

Butterfield, A. J.↗
NASA NTRS1978

Satellite Power System (SPS) military implications

The military implications of the reference satellite power system (SPS) were examined is well as important military related study tasks. Primary areas of investigation were the potential of the SPS as a weapon, for supporting U.S. military preparedness, and for affecting international relations. In addition, the SPS's relative vulnerability to overt military action, terrorist attacks, and sabotage was considered.

Bain, C. N.↗
NASA NTRS1978

FTMP - A highly reliable Fault-Tolerant Multiprocessor for aircraft

The FTMP (Fault-Tolerant Multiprocessor) is a complex multiprocessor computer that employs a form of redundancy related to systems considered by Mathur (1971), in which each major module can substitute for any other module of the same type. Despite the conceptual simplicity of the redundancy form, the implementation has many intricacies owing partly to the low target failure rate, and partly to the difficulty of eliminating single-fault vulnerability. An extensive analysis of the computer through the use of such modeling techniques as Markov processes and combinatorial mathematics shows that for random hard faults the computer can meet its requirements. It is also shown that the maintenance scheduled at intervals of 200 hr or more can be adequate most of the time.

Hopkins, A. L., Jr.↗
NASA NTRS1980

Shuttle Global Positioning (GPS) System design study

Investigations of certain aspects and problems of the shuttle global positioning system GPS, are presented. Included are: test philosophy and test outline; development of a phase slope specification for the shuttle GPS antenna; an investigation of the shuttle jamming vulnerability; and an expression for the GPS signal to noise density ratio for the thermal protection system.

Nilsen, P.↗
NASA NTRS1980

Assessment of Carbon Fiber Electrical Effects

The risks associated with the use of carbon fiber composites in civil aircraft are discussed along with the need for protection of civil aircraft equipment from fire-released carbon fibers. The size and number of carbon fibers released in civil aircraft crash fires, the downwind dissemination of the fibers, their penetration into buildings and equipment, and the vulnerability of electrical/electronic equipment to damage by the fibers are assessed.

Source record↗
NASA NTRS1980

Large-scale fiber release and equipment exposure experiments

Outdoor tests were conducted to determine the amount of fiber released in a full scale fire and trace its dissemination away from the fire. Equipment vulnerability to fire released fibers was assessed through shock tests. The greatest fiber release was observed in the shock tube where the composite was burned with a continuous agitation to total consumption. The largest average fiber length obtained outdoors was 5 mm.

Pride, R. A.↗
NASA NTRS1980

Perspective on the results

The results of studies on the risk due to the use of carbon fibers in aircraft are assessed. Assumptions such as additional fire protection in the aircraft, new structural concepts, and the development of unique carbon composites are evaluated. Some findings from the national risk profile including equipment vulnerability and economic impact are discussed.

Huston, R. J.↗
NASA NTRS1980

Risk Assessment of Carbon Fiber Composite in Surface Transportation

The vulnerability of surface transportation to airborne carbon fibers and the national risk associated with the potential use of carbon fibers in the surface transportation system were evaluated. Results show airborne carbon fibers may cause failure rates in surface transportation of less than one per year by 1995. The national risk resulting from the use of carbon fibers in the surface transportation system is discussed.

Hathaway, W. T.↗
NASA NTRS1980

Advanced risk assessment of the effects of graphite fibers on electronic and electric equipment

An assessment of the risk associated with accidents involving aircraft with carbon fiber composite structural components is examined. The individual fiber segments cause electrical and electronic equipment to fail under certain operating conditions. A Monte Carlo simulation model was used to computer the risk. Aircraft accidents with fire, release of carbon fiber material, entrainment of carbon fibers in a smoke plume transport of fibers downwind, transfer of some fibers/into the the interior of buildings, failures of electrical and electronic equipment, and economic impact of failures are discussed. Risk profiles were prepared for individual airports and the Nation. The vulnerability of electrical transmission equipment to carbon fiber incursion and aircraft accident total costs is investigated.

Pocinki, L.↗
NASA NTRS1980

Carbon/graphite fiber risk analysis and assessment study: An assessment of the risk to Douglas commercial transport aircraft

The potential hazard to electrical and electronic devices should there be a release of free carbon fibers due to an aircraft crash and fire was assessed. Exposure and equipment sensitivity data were compiled for a risk analysis. Results are presented in the following areas: DC-9/DC-10 electrical/electronic component characterization; DC-9 and DC-10 fiber transfer functions; potential for transport aircraft equipment exposure to carbon fibers; and equipment vulnerability assessment. Results reflect only a negligible increase in risk for the DC-9 and DC-10 fleets either now or projected to 1993.

Schjelderup, H. C.↗
NASA NTRS1980

On the security of the Merkle-Hellman cryptographic scheme

Cryptanalysis applied to a simple Merkle-Hellman (1978) public key cryptographic system (described within a standard-parameter knapsack problem) reveals the high vulnerability of the system. However, a cryptanalytic attack becomes ineffective when the knapsack problem with two or more iterations is used in order to obscure the structure of the superincreasing sequence. To enhance the security of a cryptographic system structured numbers can be used, while the multiple iterations of the modular multiplications technique can produce a safer Merkle-Hellman knapsack system.

Shamir, A.↗
NASA NTRS1980

Fiber release from impacted graphite reinforced epoxy composites

Carbon fibers released from composites by aircraft fires and crashes can cause electrical shorts and consequent equipment damage. This report investigates less vigorous release mechanisms than that previously simulated by explosive burn/blast tests. When AS/3501-6 composites are impacted by various head and weight configurations of a pendulum impactor, less than 0.2 percent by weight of the original sample is released as single fibers. Other fiber release mechanisms studied were air blasts, constant airflow, torsion, flexural, and vibration of composite samples. The full significance of the low single fiber release rates found here is to be evaluated by NASA in their aircraft vulnerability studies.

Babinsky, T. C.↗
NASA NTRS1980

Development of a solvent processed insensitive propellant

Two types of low vulnerability propellants are studied which are distinguished by whether the binder is a rubber, such as polyurethane or CTBN, or a plasticizable polymer such as ethyl cellulose or cellulose acetate. The former propellants are made by a partial cure extrusion process while the latter are made by the conventional solvent process. Emphasis is given to a cellulose binder (plasticizer) RDX composition. The type of binder used, the particle size of the RDX and the presence of small quantities of nitrocellulose in the solvent processed compositions have important influences on the mechanical and combustion characteristics of the propellant. The low temperature combustion is of particular concern because of potential breakup of the grains that can lead to instability.

Trask, R.↗
NASA NTRS1980

Assessment of risk to Boeing commerical transport aircraft from carbon fibers

The possible effects of free carbon fibers on aircraft avionic equipment operation, removal costs, and safety were investigated. Possible carbon fiber flow paths, flow rates, and transfer functions into the Boeing 707, 727, 737, 747 aircraft and potentially vulnerable equipment were identified. Probabilities of equipment removal and probabilities of aircraft exposure to carbon fiber were derived.

Clarke, C. A.↗
NASA NTRS1981

Application of the epidemiological model in studying human error in aviation

An epidemiological model is described in conjunction with the analytical process through which aviation occurrence reports are composed into the events and factors pertinent to it. The model represents a process in which disease, emanating from environmental conditions, manifests itself in symptoms that may lead to fatal illness, recoverable illness, or no illness depending on individual circumstances of patient vulnerability, preventive actions, and intervention. In the aviation system the analogy of the disease process is the predilection for error of human participants. This arises from factors in the operating or physical environment and results in errors of commission or omission that, again depending on the individual circumstances, may lead to accidents, system perturbations, or harmless corrections. A discussion of the previous investigations, each of which manifests the application of the epidemiological method, exemplifies its use and effectiveness.

Cheaney, E. S.↗
NASA NTRS1981

Carbon/graphite composite material study, appendix A and appendix B

A comprehensive assessment of the possible damage to electrical and electronic equipment caused by accidental release of carbon fibers from burning civil aircraft with carbon composite parts was completed. The study concluded that the amount of fiber likely to be released is much lower than initially predicted. Carbon fiber released from an aircraft crash fire was found (from atmospheric dissemination models) to disperse over a much larger area than originally estimated, with correspondingly lower fiber concentrations. Long term redissemination of fiber was shown to be insignificant if reasonable care is exercised in accident cleanup. The vulnerability of electrical equipment to structural fibers in current use was low. Consumer appliances, industrial electronics, and avionics were essentially invulnerable to carbon fibers. Shock hazards (and thus potential injury or death) were found to be extremely unlikely.

Source record↗
NASA NTRS1980

Contamination control of the Infrared Astronomical Satellite

The Infrared Astronomical Satellite, to be launched in August 1981, will perform an all-sky survey in the 8-120 micron wavelength region. High sensitivity to thermal radiation and the low operating temperature of optics and thermal control surfaces make the IRAS telescope extremely vulnerable to contamination. Four special topics of importance are discussed in this paper: (1) deposition of atmospheric gases; (2) sighting of particles released from the satellite; (3) functions of a deployable aperture cover; and (4) degradation of a radiatively cooled sunshade from spacecraft outgassing. These topics demonstrate how mission strategy, ground cleaning and handling, and hardware design are used to avoid contamination which would degrade telescope performance.

Andreozzi, L. C.↗