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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS2022

Novel Processing, Testing and Characterization of Copper/Carbon Nanotube (Cu/CNT) Yarn Composite Conductor

Sustainable electrified aircraft propulsion (EAP) is likely to lead to an increase in the electrical wiring contained within a single aircraft. Since the electrical resistance and mass of copper (Cu) conductors are associated with power losses, it is desirable to design high-conductivity lightweight conductor materials, thus reducing the mass of components like motor windings, low-voltage signal cables, and transmission cables for data and power to improve the overall energy efficiency. This paper describes a unique framework for manufacturing metalized carbon nanotube (CNT) composite conductors, measuring their electrical conductivity and strength, and modeling the overall conductivity and current sharing within such composites. Tensile testing was conducted on the processed composite conductor cables with the use of acoustic emission and electrical resistivity to determine stress-dependent-failure mechanisms while monitoring the electrical conductivity. The average of measured electrical conductivities of annealed Cu/CNT samples from batch 5 was greater than theoretical predictions by 9.8 percent and was also greater than the conductivity of pure annealed Cu by 4.8 percent and had comparable ultimate tensile strengths. Additionally, those Cu/CNT samples provide a 13.5% weight saving over current state of the art copper wires. Theories explaining improved intrinsic conductivity are discussed.

Metalized CNT↗
NASA NTRS2014

Installation and Assembly, Electrical Ground Support Equipment (GSE), Specification for

This specification covers the general workmanship requirements and procedures for the complete installation and assembly of electrical ground support equipment (EGSE) such as terminal distributors, junction boxes, conduit and fittings, cable trays and accessories, interconnecting cables (including routing requirements), motor-control equipment, and necessary hardware as specified by the applicable contract and drawings.

Electrical and Electronics↗
NASA NTRS1989

Cable coupling lightning transient qualification

Simulated lightning strike testing of instrumentation cabling on the redesigned solid rocket motor was performed. Testing consisted of subjecting the lightning evaluation test article to simulated lightning strikes and evaluating the effects of instrumentation cable transients on cables within the system tunnel. The maximum short-circuit current induced onto a United Space Boosters, Inc., operational flight cable within the systems tunnel was 92 A, and the maximum induced open-circuit voltage was 316 V. These levels were extrapolated to the worst-case (200 kA) condition of NASA specification NSTS 07636 and were also scaled to full-scale redesigned solid rocket motor dimensions. Testing showed that voltage coupling to cables within the systems tunnel can be reduced 40 to 90 dB and that current coupling to cables within the systems tunnel can be reduced 30 to 70 dB with the use of braided metallic sock shields around cables that are external to the systems tunnel. Testing also showed that current and voltage levels induced onto cables within the systems tunnel are partially dependant on the cables' relative locations within the systems tunnel. Results of current injections to the systems tunnel indicate that the dominant coupling mode on cables within the systems tunnel is not from instrumentation cables but from coupling through the systems tunnel cover seam apertures. It is recommended that methods of improving the electrical bonding between individual sections of the systems tunnel covers be evaluated. Further testing to better characterize redesigned solid rocket motor cable coupling effects as an aid in developing methods to reduce coupling levels, particularly with respect to cable placement within the systems tunnel, is also recommended.

Cook, M.↗
NASA NTRS1968

Rectangular configuration improves superconducting cable

Superconducting cable for a cryogenic electromagnet with improved mechanical and thermal properties consists of a rectangular cross-sectioned combination of superconductor and normal conductor. The conductor cable has superconductors embedded in a metallic coating with high electrical and mechanical conductivity at liquid helium temperatures.

Foss, M.↗
NASA NTRS1988

Current waveforms analyses of lightning flashes triggered by the rocket and wire technique

Presented in this paper are the main results of the 1987 Rocket Triggered Lightning Program (RTLP) in Florida: I greater than 60 kA, DI/DT greater than 400 kA/micro-S. Optical and electrical observations from flashes triggered by grounded wire or insulating cable (200 m) rocket technique are presented. Correlation between I and DI/DT measurements are presented and discussed. These measurements were carried out with the same grounded wire rocket technique in Florida in 1985, 1987, and in France in 1986.

Eybert-Berard, A.↗
NASA NTRS1989

Cascaded resonant bridge converters

A converter for converting a low voltage direct current power source to a higher voltage, high frequency alternating current output for use in an electrical system where it is desired to use low weight cables and other circuit elements. The converter has a first stage series resonant (Schwarz) converter which converts the direct current power source to an alternating current by means of switching elements that are operated by a variable frequency voltage regulator, a transformer to step up the voltage of the alternating current, and a rectifier bridge to convert the alternating current to a direct current first stage output. The converter further has a second stage series resonant (Schwarz) converter which is connected in series to the first stage converter to receive its direct current output and convert it to a second stage high frequency alternating current output by means of switching elements that are operated by a fixed frequency oscillator. The voltage of the second stage output is controlled at a relatively constant value by controlling the first stage output voltage, which is accomplished by controlling the frequency of the first stage variable frequency voltage controller in response to second stage voltage. Fault tolerance in the event of a load short circuit is provided by making the operation of the first stage variable frequency voltage controller responsive to first and second stage current limiting devices. The second stage output is connected to a rectifier bridge whose output is connected to the input of the second stage to provide good regulation of output voltage wave form at low system loads.

Stuart, Thomas A.↗
NASA NTRS2007

SpaceWire Cable and Connector Variations. Session: SpaceWire Components

This viewgraph presentation reviews issues about SpaceWire cable and connectors. Discussion in the talk concerned connector specifications and cable specifications. The Connector Specification issues are: (1) Not impedance matched to the cable (2) Handling (Mechanical) issues (3) Need space-qualified matched impedance connector (4) alternative space-qualified connector and Electrical Issues (5) Only a single ground pin which does not pass through (6) Near-end Crosstalk (NEXT) at the SpaceWire connector Cable Specification issue concerns the use of larger gauge cable in non-standard applications or to meet tight specifications

Allen, Shaune S.↗
NASA NTRS1991

Intramuscular Contact Lead Filled With Conductive Solution

Proposed sheath for braided-wire intramuscular conductor preserves electrical continuity even if wire breaks. Plastic sheath surrounds conductive solution in which braided wire immersed. At end of cable, wire and sheath crimped together and press-fit in porous titanium electrode. Implanted surgically with aid of device resembling catheter. Used to deliver electrical stimuli to muscles in biomedical research on human and animal physiology, development of prostheses, regeneration of nerves and muscles, and artificial implants.

Bamford, Robert M.↗
NASA NTRS1974

Testing of flat conductor cable to Underwriters Laboratory standards UL719 and UL83

The flat conductor cable (FCC) which was tested consisted of three AWG No. 12 flat copper conductors laminated between two films of polyethylene terephthalate (Mylar) insulation with a self-extinguishing polyester adhesive. Results of the tests conducted on this cable, according to specifications, warrants the use of this FCC for electrical interconnections in a surface nonmetallic protective covering.

Loggins, R. W.↗
NASA NTRS2008

Structural Analysis of Lightning Protection System for New Launch Vehicle

This project includes the design and specification of a lightning protection system for Launch Complex 39 B (LC39B) at Kennedy Space Center, FL in support of the Constellation Program. The purpose of the lightning protection system is to protect the Crew Launch Vehicle (CLV) or Cargo Launch Vehicle (CaLV) and associated launch equipment from direct lightning strikes during launch processing and other activities prior to flight. The design includes a three-tower, overhead catenary wire system to protect the vehicle and equipment on LC39B as described in the study that preceded this design effort: KSC-DX-8234 "Study: Construct Lightning Protection System LC3 9B". The study was a collaborative effort between Reynolds, Smith, and Hills (RS&H) and ASRC Aerospace (ASRC), where ASRC was responsible for the theoretical design and risk analysis of the lightning protection system and RS&H was responsible for the development of the civil and structural components; the mechanical systems; the electrical and grounding systems; and the siting of the lightning protection system. The study determined that a triangular network of overhead catenary cables and down conductors supported by three triangular free-standing towers approximately 594 ft tall (each equipped with a man lift, ladder, electrical systems, and communications systems) would provide a level of lightning protection for the Constellation Program CLV and CaLV on Launch Pad 39B that exceeds the design requirements.

Cope, Anne↗
NASA NTRS2008

TEM Cell Testing of Cable Noise Reduction Techniques From 2 MHz to 200 MHz - Part 1

This paper presents empirical results of cable noise reduction techniques as demonstrated in a TEM cell operating with radiated fields from 2 - 200 MHz. It is the first part of a two-paper series. This first paper discusses cable types and shield connections. In the second paper, the effects of load and source resistances and chassis connections are examined. For each topic, well established theories are compared to data from a real-world physical system. Finally, recommendations for minimizing cable susceptibility (and thus cable emissions) are presented. There are numerous papers and textbooks that present theoretical analyses of cable noise reduction techniques. However, empirical data is often targeted to low frequencies (e.g. <50 KHz) or high frequencies (>100 MHz). Additionally, a comprehensive study showing the relative effects of various noise reduction techniques is needed. These include the use of dedicated return wires, twisted wiring, cable shielding, shield connections, changing load or source impedances, and implementing load- or source-to-chassis isolation. We have created an experimental setup that emulates a real-world electrical system, while still allowing us to independently vary a host of parameters. The goal of the experiment was to determine the relative effectiveness of various noise reduction techniques when the cable is in the presence of radiated emissions from 2 MHz to 200 MHz. The electronic system (Fig. 1) consisted of two Hammond shielded electrical enclosures, one containing the source resistance, and the other containing the load resistance. The boxes were mounted on a large aluminium plate acting as the chassis. Cables connecting the two boxes measured 81 cm in length and were attached to the boxes using standard D38999 military-style connectors. The test setup is shown in Fig. 2. Electromagnetic fields were created using an HP8657B signal generator, MiniCircuits ZHL-42W-SMA amplifier, and an EMCO 5103 TEM cell. Measurements were taken using an Agilent E4401B spectrum analyzer and HP1141a differential probes.

Bradley, Arthur T.↗
NASA NTRS1971

Electromagnetic compatibility design guideline for STADAN

Procedures for achieving electromagnetic compatibility in electronic and electrical equipment for aerospace ground stations are investigated. The application of shielding theory to good design is treated and standards of good practice are outlined for bonding, grounding, wiring, and cabling. Some aspects of filter design are explained, and suggestions are given for the application of filters to electronic and electrical equipment.

Cowdell, R. B.↗
NASA NTRS1972

HALAR fluoropolymer: A versatile insulation material

Research directed toward developing materials for the wire and cable industry has resulted in a new product, E-CTFE copolymer, which has an outstanding combination of electrical, thermal, and mechanical properties. The properties of E-CTFE are discussed and compared with those of other commercial fluoropolymers. Particular attention is given to the utility of E-CTFE as a wire and cable insulation.

Robertson, A. B.↗
NASA NTRS1986

Input impedance of a probe-fed circular microstrip antenna with thick substrate

A method of computing the input impedance for the probe fed circular microstrip antenna with thick dielectric substrate is presented. Utilizing the framework of the cavity model, the fields under the microstrip patch are expanded in a set of modes satisfying the boundary conditions on the eccentrically located probe, as well as on the cavity magnetic wall. A mode-matching technique is used to solve for the electric field at the junction between the cavity and the coaxial feed cable. The reflection coefficient of the transverse electromagnetic (TEM) mode incident in the coaxial cable is determined, from which the input impedance of the antenna is computed. Measured data are presented to verify the theoretical calculations. Results of the computation of various losses for the circular printed antenna as a function of substrate thickness are also included.

Davidovitz, M.↗
NASA NTRS1988

Expert systems applications for space shuttle payload integration automation

Expert systems technologies have been and are continuing to be applied to NASA's Space Shuttle orbiter payload integration problems to provide a level of automation previously unrealizable. NASA's Space Shuttle orbiter was designed to be extremely flexible in its ability to accommodate many different types and combinations of satellites and experiments (payloads) within its payload bay. This flexibility results in differnet and unique engineering resource requirements for each of its payloads, creating recurring payload and cargo integration problems. Expert systems provide a successful solution for these recurring problems. The Orbiter Payload Bay Cabling Expert (EXCABL) was the first expert system, developed to solve the electrical services provisioning problem. A second expert system, EXMATCH, was developed to generate a list of the reusable installation drawings available for each EXCABL solution. These successes have proved the applicability of expert systems technologies to payload integration problems and consequently a third expert system is currently in work. These three expert systems, the manner in which they resolve payload problems and how they will be integrated are described.

Morris, Keith↗
NASA NTRS1992

Portable Power And Digital-Communication Units

Conceptual network of electronic-equipment modules provides electrical power and digital radio communications at multiple sites not served by cables. System includes central communication unit and portable units powered by solar photovoltaic arrays. Useful to serve equipment that must be set up quickly at remote sites or buildings that cannot be modified to provide cable connections.

Levin, Richard R.↗