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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS2015

NASA Engineering and Safety Center Technical Bulletin No. 15-01: Preventing Incorrect Installation of Polarized Capacitors

Even though NASA’s Lessons Learned Information System has an entry on the reverse installation of polarized capacitors, this error keeps reoccurring and is a “lesson not learned.” The purpose of this bulletin is to discuss some of the reasons this keeps happening as well as offer best practices to prevent this error in the future.

Preventing Incorrect Installation of Polarized Cap↗
DOE OSTI2026

Influence of the broadly neutralizing antibody VRC01 on HIV breakthrough virus populations in antibody-mediated prevention trials

In the antibody mediated prevention (AMP) trials, the broadly neutralizing antibody (bNAb) VRC01 demonstrated protective efficacy against susceptible HIV strains. To understand how VRC01 shaped breakthrough infections, deep sequencing was performed on 172 participants (>100,000 gag-Δpol and rev-env-Δnef sequences), at diagnosis and over time, in the placebo and treatment arms of the African (HVTN703/HPTN081; NCT02568215) and Americas/Europe (HVTN704/HPTN085; NCT02716675) cohorts. A high frequency of multilineage infections was detected (38%), including co-infection with both VRC01 sensitive and resistant viruses. This high frequency is largely accounted for by low-abundance lineages. Although VRC01 does not significantly affect the genetic transmission bottleneck compared to placebo, higher VRC01 doses trend towards greater VRC01 neutralization differences among co-infecting lineages. Two-thirds of multilineage infections showed evidence of recombination at the diagnostic timepoint. In the treatment group there is evidence of recombinant viruses preferentially inheriting resistance-associated mutations. This study provides critical insights into viral genetic and antigenic diversity that needs to be targeted to achieve protection, and highlights the role of recombination in facilitating escape.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Prevention of resistive wall tearing mode major disruptions with feedback

Resistive wall tearing modes (RWTMs) can cause major disruptions. A signature of RWTMs is that the rational surface is sufficiently close to the wall to interact with it. For (m,n) = (2,1) modes, a RWTM requires normalized minor radius of the rational surface ρ q2 ≥ 0.75, which can also be expressed as q 75 ≤ 2. Major disruptions can occur when the criterion is satisfied. This is confirmed in simulations and theory and in a DIII-D locked mode disruption database. The q 75 < 2 criterion is valid at high β as well as at low β. A very important feature of RWTMs is that they can be feedback stabilized. If the ρ q2 criterion is not satisfied, or if the wall is ideally conducting, then the mode does not produce a major disruption, although it can produce a minor disruption. Feedback, or rotation of the mode at the wall by complex feedback, can emulate an ideal wall, preventing major disruptions. The ρ q2 criterion depends weakly on the wall radius. A simple geometric model of its dependence on wall radius is given.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Cost-optimal selection of pH control for mineral scaling prevention in high recovery reverse osmosis desalination

Conference proceedings for Foundations of Computer Aided Process Design (FOCAPD) 2024 that details a cost optimization model for pH control to prevent mineral scaling in high recovery reverse osmosis. This work applies a framework for incorporating detailed water chemistry predictions such as precipitation, pH change, and mineral scaling tendencies with process-scale optimization. It demonstrates that the acid choice for pH control can have a significant impact on pretreatment costs.

Amusat, Oluwamayowa↗
NASA NTRS1964

Vented piston seal prevents fluid leakage between two chambers

To prevent fluid leakage around piston seals separating two fluids under differential pressure, a venting system has been devised. Two methods may be used for venting seals through internal passages to an external low-pressure area, O-ring or split-ring seals.

Mac Glashan, W. F.↗
NASA NTRS1964

High-pressure regulating system prevents pressure surges

Gas flow is controlled by means of a pressure regulating system which prevents pressure surges. A high-pressure fluid source, a spring-loaded fluid-damped regulator valve, an accumulator, a conventional normally closed command valve, and a control valve are the main components.

Keller, O. F.↗
NASA NTRS1964

Fine-particle filter prevents damage to vacuum pumps

A filter system for mechanical pumps is designed with a baffle assembly that rotates in a circulating oil bath which traps destructive particles. This prevents severe damage to the pump and is serviceable for long periods before it requires cleaning.

Harlamert, P., Jr.↗
NASA NTRS1964

Problems of Fire Prevention and Extinguishment in Space Cabins

The problems of prevention and extinguishment of fires in space cabins are, except for a few specific situations, not much different from those at sea level or in aircraft conditions. The unusual atmospheric environment and limitations of space and firefighting equipment compound the general problem. The zero-gravity environment modifies firefighting procedures in a rather profound way and will be given detailed treatment in this report.

CHEMICAL EXTINGUISHER↗
NASA NTRS1954

A Method for Prevention of Screaming in Rocket Engines

Lateral and longitudinal combustion-pressure oscillations that occurred in screaming combustion of a 1000-pound-thrust rocket engine using white fuming nitric acid and JP-4 fuel as propellants were successfully prevented by means of longitudinal fins in the combustion chamber. Fin position was critical, and complete attenuation was achieved only when the fins were located in a zone approximately 8 to 16 inches from the injector. Fins located in other zones, that is, near the injector or far downstream from the injector, did not stop the oscillations. When oscillations occurred in finned chambers, the longitudinal mode seemed more dominant than the lateral mode; in chambers without fins, the lateral mode tended to be dominant. The lateral oscillation was distorted and its intensity diminished by the fins. Fins, however, did not affect the frequencies; the longitudinal frequency varied inversely with chamber length, and lateral frequencies varied only slightly from an average of 6000 cycles per second.

ROCKET ENGINE NOISE↗
NASA NTRS1966

Insert sleeve prevents tube soldering contamination

Teflon sleeve insert prevents contamination of internal tube surfaces by solder compound during soldering operations that connect and seal the tube ends. The sleeve insert is pressed into the mating tube ends with a slight interference fit.

Stein, J.↗
NASA NTRS1966

Polarizing keys prevent mismatch of connector plugs and receptacles

Keying prevents mismatching of plugs and receptacles in connector patching of instrumentation involving several thousand leads. Each receptacle and plug contains three polarizing keys that must mate in a complementary mode before the connector pins and sockets will engage.

Chiapuzio, A.↗
NASA NTRS1965

Adapter assembly prevents damage to tubing during high pressure tests

Portable adapter assembly prevents damage to tubing and injury to personnel when pressurizing a system or during high pressure tests. The assembly is capable of withstanding high pressure. It is securely attached to the tubing stub end and may be removed without brazing, cutting or cleaning the tube.

Stinett, L. L.↗
NASA NTRS1966

Large diameter metal ring seal prevents gas leakage at 5000 psi

Large metal ring seal prevents gas leakage in hydrogen, helium, or nitrogen storage bottles at pressures up to 5,000 psi. The grooved ring seal which contains elastomer O-rings is installed between the mating faces of the access cover and the storage bottle.

Middelkoop, J. H.↗
NASA NTRS1966

Circuit prevents overcharging of secondary cell batteries

Circuit prevents battery cell overcharging by detecting and reducing the charging voltage to the open-circuit voltage of the battery when this current falls to a predetermined value. The voltage control depends on the fact that the charging current falls significantly when the battery nears its fully charged state.

Hennigan, T. J.↗
NASA NTRS1966

Controlled release device prevents damage from dynamic stresses

Controlled release device that retards motion by extruding or drawing a tapered ductile pin through a die will control launch vehicle motion at liftoff. The device prevents the damaging dynamic stresses that are imposed on the vehicle when it is instantaneously released at full thrust.

Burcham, T. W.↗