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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Near-tail reconnection as the cause of cometary tail disconnections

In a cometary tail disconnection event the plasma tail appears to separate from the coma and to accelerate away from it. As this occurs a new tail begins to form. It is proposed that these disconnections arise in a manner analogous to geomagnetic substorms, i.e., by the formation of a strongly reconnecting region in the near tail that forms a magnetic island in the coma and ejects the plasma tail by strengthening the magnetic 'slingshot' within the tail. This reconnection process may be triggered by several different processes, such as interplanetary shocks or variations in the Alfven Mach number.

Russell, C. T.↗
NASA NTRS1988

Quick-Disconnect Valves For Modular Fluid Systems

Maintainable valves being developed for use as interfaces between modules or other separable components in maintainable fluid systems. Pair of valves joins two plumbing subsystems, connected to or disconnected from each other and enabling either or both to be isolated upon disconnection. Relief valve built into cartridge of maintainable valve, cartridge removes for replacement or inspection. New valves designed for temperature-regulating equipment aboard space station, used with or without modifications in variety of liquid and low-pressure-gas systems on Earth.

Fluger, Charles↗
NASA NTRS1987

Was the eclipse comet of 1893 a disconnected coronal transient?

The comet-like feature obsereved in the solar corona by the Lick Observatory eclipse expedition to Chile in 1893 bears an interesting resemblance to the disconnection coronal transient reported by Illing and Hundhausen. Reports of possibly-related limb activity are reviewed to see whether a pre-discovery observation of a relatively rare type of coronal mass ejection was mis-interpreted. The goal of this study is to learn more about the morphology of mass ejections by examining observations that extend down to the low corona of a disconnection event.

Cliver, E. W.↗
NASA NTRS1987

The cause of two plasma-tail disconnection events in comet P/Haley during the ICE-Halley radial period

The causes of two plasma-tail disconnection events (DEs), which occurred in Halley's comet on March 20-22 and April 11-12, 1986, during the ICE-Halley radial period, are analyzed using the ICE magnetometer and electron plasma data. It is concluded that the DE of March 20-22 was most likely caused by an IMF polarity reversal. The DE of April 11-12 on the other hand, is attributed to either a compression region in the solar wind, an IMF polarity reversal, or a combination of the two. Assuming that the two DEs are due to frontside reconnection after an IMF reversal, it was estimated that the time period between the onset of reconnection and the final disconnection of the tail is between 0.1 and 0.6 day, suggesting that the average speed at which reconnection proceeds through the cometary magnetic field pile-up region is between 1 and 6 km/sec, or several tenths of the local Alfven speed.

Brosius, J. W.↗
NASA NTRS1988

Flow Analysis of Space Shuttle Feed Line 17-inch Disconnect Valve

A steady incompressible three-dimensional viscous flow analysis has been conducted for the Space Shuttle External Tank/Orbiter propellant feed line disconnect flapper valves with upstream elbows. The full Navier-Stokes code, INS3D, is modified to handle interior obstacles. Grids are generated by SVTGD3D code. Two dimensional initial grids in the flow cross section with and without the flappers are improved by elliptic smoothing to provide better orthogonality, clustering and smoothness to the three dimensional grid. The flow solver is tested for stability and convergence in the presence of interior flappers. An under-relaxation scheme has been incorporated to improve the solution stability. Important flow characteristics such as secondary flows, recirculation, vortex and wake regions, and separated flows are observed. Computed values for forces, moments, and pressure drop are in satisfactory agreement with water flow test data covering a maximum tube Reynolds number of 3.5 x 10(exp 6). The results will serve as a guide to improved design and enhanced testing of the disconnect.

Kandula, Max↗
NASA NTRS1994

Nonthermal radio emission associated with a coronal disconnection event

We have found possible radio signatures of a coronal disconnection event observed by the Solar Maximum Mission Coronagraph/Polarimeter. The radio emission seems to be produced by charged particles accelerated during the same reconnection process which is responsible for the disconnection event. We discuss the implications of the radio emission characteristics to the reconnection process.

Gopalswamy, N.↗
NASA NTRS2009

High Pressure Quick Disconnect Particle Impact Tests

NASA Johnson Space Center White Sands Test Facility (WSTF) performed particle impact testing to determine whether there is a particle impact ignition hazard in the quick disconnects (QDs) in the Environmental Control and Life Support System (ECLSS) on the International Space Station (ISS). Testing included standard supersonic and subsonic particle impact tests on 15-5 PH stainless steel, as well as tests performed on a QD simulator. This paper summarizes the particle impact tests completed at WSTF. Although there was an ignition in Test Series 4, it was determined the ignition was caused by the presence of a machining imperfection. The sum of all the test results indicates that there is no particle impact ignition hazard in the ISS ECLSS QDs. KEYWORDS: quick disconnect, high pressure, particle impact testing, stainless steel

Rosales, Keisa R.↗
NASA NTRS2021

Multi-User Spaceport Umbilical Low Force Disconnect

This project designed and fabricated a prototype model of an Umbilical Low Force Disconnect (LFD). Traditional quick disconnects (QD) have a high separation force (SF) when pressurized due to the axial flow path through the QD.

Gabor J Tamasy↗
DOE OSTI2023

Optimizing shift selection in multilevel Monte Carlo for disconnected diagrams in lattice QCD

The calculation of disconnected diagram contributions to physical signals is a computationally expensive task in Lattice QCD. To extract the physical signal, the trace of the inverse Lattice Dirac operator, a large sparse matrix, must be stochastically estimated. Because the variance of the stochastic estimator is typically large, variance reduction techniques must be employed. Multilevel Monte Carlo (MLMC) methods reduce the variance of the trace estimator by utilizing a telescoping sequence of estimators. Frequency Splitting is one such method that uses a sequence of inverses of shifted operators to estimate the trace of the inverse lattice Dirac operator, however there is no a priori way to select the shifts that minimize the cost of the multilevel trace estimation. Here we present a sampling and interpolation scheme that is able to predict the variances associated with Frequency Splitting under displacements of the underlying space time lattice. The interpolation scheme is able to predict the variances to high accuracy and therefore chooses shifts that correspond to an approximate minimum of the cost for the trace estimation. We show that Frequency Splitting with the chosen shifts displays significant speedups over multigrid deflation, and that these shifts can be used for multiple configurations within the same ensemble with no penalty to performance.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2025

Data-driven results for light-quark connected and strange-plus-disconnected hadronic g − 2 short- and long-distance windows

A key issue affecting the attempt to reduce the uncertainty on the Standard Model prediction for the muon anomalous magnetic moment is the current discrepancy between lattice-QCD and data-driven results for the hadronic vacuum polarization. Progress on this issue benefits from precise data-driven determinations of the isospin-limit light-quark-connected (lqc) and strange-plus-light-quark-disconnected ( s + lqd ) components of the related RBC/UKQCD windows. In this paper, using a strategy employed previously for the intermediate window, we provide data-driven results for the lqc and s + lqd components of the short- and long-distance RBC/UKQCD windows. Comparing these results with those from the lattice, we find significant discrepancies in the lqc parts but good agreement for the s + lqd components. We also explore the impact of recent CMD- 3 e + e − → π + π − cross section results, demonstrating that an upward shift in the ρ -peak region of the type seen in the CMD-3 data serves to eliminate the discrepancies for the lqc components without compromising the good agreement between lattice and data-driven s + lqd results. Published by the American Physical Society 2025

Benton, Genessa (ORCID:0009000515763654)↗
NASA NTRS1965

Device disconnects several couplings simultaneously

Actuator assembly disconnects electric cable and fluid-line coupling from a rocket. The disconnector incorporates interconnected hydraulic cylinders which effect an equal and simultaneous displacement of pistons upon admission of compressed air through a solenoid control valve.

Forsythe, A. K.↗
NASA NTRS1965

Improved solderless connector is easily disconnected

Compression type solderless connector is easily disconnected and reassembled and resists vibration. The connector, which uses a tapered split sleeve that is tightened by a nut into a mating bug, is used in place of standard solder lugs and to connect unsolderable wire.

Source record↗
NASA NTRS1967

Quick-disconnect at countdown.

Umbilical carriers and quick-disconnect facilities of Saturn V ground support equipment noting location, ejecting methods, etc

UMBILICAL TOWER↗
NASA NTRS1969

Connect-disconnect coupling for preadjusted rigid shafts

Coupling device enables a rigid shaft to be connected to or disconnected from a fixed base without disturbing the point of adjustment of the shaft in a socket or causing the shaft to rotate. The coupling consists of an externally threaded, internally slotted boss extending from the fixed base.

Bajkowski, F. W.↗
NASA NTRS1970

Umbilical disconnect actuator

Contamination of sensitive equipment when squibs are fired is prevented by O-rings which retain the debris of squib discharge within the disconnect device.

Davis, D. P.↗
NASA NTRS1970

Self-sealing, easily purged quick-disconnect hose coupling

Coupling for pressurized hoses handles gas or liquid, is easily purged, and automatically seals the hose when disconnected. Volatile or toxic materials can be isolated before the connection is broken. This device may interest food processors and manufacturers of fluid delivery systems.

Leyerle, R. B.↗