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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 91 records · Page 5

Long-lived particles: theory and experimental probes

Long-lived particles (LLPs) are particles that are stable or that live long enough for their decays to be experimentally distinguishable in time or position from their production point. We provide an overview of the phenomenology and experimental signatures of LLPs, focusing on LLPs at the Large Hadron Collider (LHC). We explain what determines a particle's lifetime and we show that LLPs are ubiquitous both within the Standard Model and beyond. We survey the methods used to experimentally detect and characterize particles at collider-based experiments, and discuss how searches for LLPs present both experimental challenges and exciting new possibilities for detection. Finally, we situate LHC searches for LLPs within the broader experimental landscape with a brief overview of searches for LLPs at lower-energy experiments and a discussion of astrophysical and cosmological probes offering complementary insight into the physics of LLPs beyond the Standard Model.

Jeanty, Laura [University of Oregon]↗

Steady-state temperature distribution in living tissue modeled as cylindrical shells.

Closed form, analytical solutions to the problem of steady-state heat transfer in living tissue modeled as cylindrical shells are presented and discussed. These solutions are particularly useful for the study of temperature distributions in the extremities. Metabolic heat generation, conduction, and heat transported by the blood perfusing the tissue are considered in the model. The results demonstrate the important role that the blood stream plays in the transfer of heat inside living tissue. Solutions are also presented for the limiting cases of diminishing blood flow that would occur during vasoconstriction or occlusion of blood by external means.

Shitzer, A.↗

Studies of images of short-lived events using ERTS data

The author has identified the following significant results. Significant results are the continued detection of short-lived events. The following have been detected and analyzed: forest fires, oil spills, vegetation damage, volcanoes, storm ridges, and earthquakes. It is hoped that the Mississippi River flood scenes will arrive shortly and then floods be added to the list of identified short-lived events.

Deutschman, W. A.↗

Informational biopolymer structure in early living forms.

Some studies devoted to the search in various organisms for 'relics' of the biochemical nature of ancient organisms, preserved by the conservative nature of the evolutionary process in all living species, are reviewed. Investigations of five families of informational molecules constituting such 'relics' in very diverse organisms are reported. They include: cytochrome c, ferredoxin, trypsin, transfer ribonucleic acid (RNA), and 5S ribosomal RNA. It is shown that, even from these few informational molecules, some interesting inferences about early living organisms can be drawn.

Dayhoff, M. O.↗

Skylab short-lived event alert program

During the three manned Skylab missions, the Center for Short-Lived Phenomena (CSLP) reported a total of 39 significant events to the Johnson Space Center (JSC) as part of the Skylab Short-Lived Event Alert Program. The telegraphed daily status reports included the names and locations of the events, the track number and revolution number during which the event could be observed, the time (GMT) to within plus or minus 2 sec when Skylab was closest to the event area, and the light condition (daylight or darkness) at that time and place. The messages sent to JSC during the Skylab 4 mission also included information pertaining to ground-truth studies and observations being conducted on the events. Photographic priorities were assigned for each event.

Citron, R. A.↗

Production of a short-lived filament by a surge

An unusual solar event is investigated in which a short-lived cloud, very much like a filament, was formed by ejecta from a large surge. The temporal evolution of this surge is described, and evidence is presented which indicates that the short-lived cloud was a bona fide filament. The energetics of this event and the mass of the surge are estimated from radio and X-ray data obtained at the onset.

Zirin, H.↗

A long-lived coronal arch system observed in X-rays

A large long-lived soft X-ray emitting arch system was observed during the last Skylab mission. This arcade stayed in the same approximate position for several solar rotations. It is suggested that these long-lived arches owe their stability to the stable coronal magnetic-field configuration. A global constant-alpha force-free magnetic-field analysis, as developed by Nakagawa et al. (1977), is used to describe the arches, and results in a marked resemblance between the theoretical magnetic-field configuration and the observed X-ray emitting feature.

Mcguire, J. P.↗

Application of space remote sensing technology to living marine resources in coastal zones

This paper describes a compilation of new Landsat satellite remote sensing techniques for treatment of Coastal Zone Living Marine Resource problems. The techniques have been developed over the past three to five years using optimized digital analysis procedures and evaluated in limited coastal areas of the United States. However, most of the techniques are directly applicable to other areas of the world, particularly in those areas where Landsat satellite data are available. Each technique presented herein has been documented and published separately as a NASA report within the last three years. The data required to substantiate the conclusion that 'significant new space remote sensing techniques are now available for the treatment of Coastal Zone Living Marine Resource problems' are contained within these reports and are referenced herein.

Tilton, E. L., III↗

Summary results from the NASA Tech House one year live-in

The NASA Tech House was designed and constructed at the Langley Research Center, Hampton, Va., to demonstrate and evaluate new technology potentially applicable for conservation of energy and resources and for improvements in safety and security in a single-family residence. All technology items, including solar energy systems and a waste water reuse system, were evaluated under actual living conditions for a one-year period with a family of four living in the house in their normal life style. Results are presented which show overall savings in energy and resources compared to requirements for a defined similar conventional house under the same conditions. Also included are general operational experience and performance data for all the various items and systems of technology incorporated into the house design.

Hamlet, I. L.↗

An evaluation of the NASA Tech House, including live-in test results, volume 1

The NASA Tech House was designed and constructed at the NASA Langley Research Center, Hampton, Virginia, to demonstrate and evaluate new technology potentially applicable for conservation of energy and resources and for improvements in safety and security in a single-family residence. All technology items, including solar-energy systems and a waste-water-reuse system, were evaluated under actual living conditions for a 1 year period with a family of four living in the house in their normal lifestyle. Results are presented which show overall savings in energy and resources compared with requirements for a defined similar conventional house under the same conditions. General operational experience and performance data are also included for all the various items and systems of technology incorporated into the house design.

Abbott, I. H. A.↗

Aromatic proteinaceous surfactants stabilize long-lived gas microbubbles from natural sources

Three different types of protein-specific chemical tests were performed on long-lived gas microbubbles derived from aqueous solutions of agarose powder and from filtered aqueous extracts of Hawaiian forest soil. The separate protein-specific tests involved use of either 0.3% (w/v) ninhydrin, 100 microM methylene blue dye, or 0.7-1.0 M 2-hydroxy-5-nitrobenzyl bromide. The chemical test results obtained with each of the two natural substances, i.e., agarose powder and Hawaiian forest soil, were very similar and indicate that the biological surfactants which surround and stabilize long-lived gas microbubbles are proteinaceous compounds that contain, and whose surface activity depends upon, aromatic amino acid residues, particularly tryptophan.

Darrigo, J. S.↗

Numerical model of long-lived Jovian vortices

The extension of the measured zonal velocity profile into the adiabatic interior of Jupiter, while eddies and large oval structures are confined to a shallow stably-stratified upper layer, are assumed in a nonlinear numerical model of long-lived Jovian vortices. In agreement of the observed flows of Jupiter, each vortex is stationary with respect to the shear flow at a critical latitude that is close to the latitude of the vortex center. The solutions obtained are strongly nonlinear, in contrast to the solitary wave solutions that are the weakly nonlinear extensions of ultralong linear waves. The merging of two stable vortices upon collision, rather than the non-interaction predicted by solitary wave theory, is in keeping with Jovian vortex observations. It is suggested that long-lived vortices maintain themselves against dissipation by absorbing smaller vortices produced by convection.

Ingersoll, A. P.↗

Prediction of fatigue crack-growth patterns and lives in three-dimensional cracked bodies

Fatigue crack growth patterns and lives for surface cracks, surface cracks at holes, and corner cracks at holes in three dimensional bodies were predicted using linear-elastic fracture mechanics concepts that were modified to account for crack-closure behavior. The predictions were made by using stress intensity factor equations for these crack configurations and the fatigue crack-growth (delta K against rate) relationship for the material of interest. The crack configurations were subjected to constant-amplitude fatigue loading under either remote tension or bending loads. The predicted crack growth patterns and crack growth lives for aluminum alloys agreed well with test data from the literature.

Newman, J. C., Jr.↗

A minimal living system and the origin of a protocell

The essential molecular attributes of a minimal living system are discussed, and the evolution of a protocell from such a system is considered. Present thought on the emergence and evolution of life is summarized, and the complexity of biological systems is reviewed. The five fundamental molecular attributes considered are: informational molecules, catalytic peptides, a decoding and translation system, protoribosomes, and protomembranes. Their functions in a primitive cell are discussed. Positive feedback interaction between proto-RNA, proto-AA-tRNA, and protoenzyme are identified as the three major steps to the formation of a primitive living cell.

Oro, J.↗

Prediction of fatigue crack-growth patterns and lives in three-dimensional cracked bodies

Fatigue crack growth patterns and lives for surface cracks, surface cracks at holes, and corner cracks at holes in three dimensional bodies were predicted using linear-elastic fracture mechanics concepts that were modified to account for crack-closure behavior. The predictions were made by using stress intensity factor equations for these crack configurations and the fatigue crack-growth (delta K against rate) relationship for the material of interest. The crack configurations were subjected to constant-amplitude fatigue loading under either remote tension or bending loads. The predicted crack growth patterns and crack growth lives for aluminum alloys agreed well with test data from the literature.

Newman, J. C., Jr.↗

Fatigue Lives of Materials Cut by Lasers

Laser machining helps to balance high-speed rotating machinery. Report describes continuing studies of fatigue lives of materials cut by lasers. One long-term objective of such studies is use of laser machining to balance rotors operating at high speeds. To achieve objective, necessary to know relationship between effects of conventional and laser machining on fatigue lives of machined materials.

Martin, Michael R.↗

Extending Fatigue Lives Of Selected Alloys

Rejuvenating treatments demonstrated. Experiments with three alloys show some combinations of heat treatment, hot isostatic pressing, and/or surface treatment extends cycle lives of fatigue-damaged or fatigue-precracked specimens. For each alloy, tests were first done to determine "baseline" high-cycle-fatigue lives and high-cycle-fatigue failure modes over range of test conditions. Controlled fatigue damage introduced into specimens. Damaged specimens subjected to candidate rejuvenating treatments, then tested to failure. Effectiveness of each treatment judged by comparing fatigue data of damaged and treated specimens to "baseline" fatigue and data taken at same test conditions.

Matejczyk, D. E.↗

Predicting Fatigue Lives Of Metal-Matrix/Fiber Composites

Method of prediction of fatigue lives of intermetallic-matrix/fiber composite parts at high temperatures styled after method of universal slopes. It suffices to perform relatively small numbers of fatigue tests. Data from fatigue tests correlated with tensile-test data by fitting universal-slopes equation to both sets of data. Thereafter, universal-slopes equation used to predict fatigue lives from tensile properties.

Bartolotta, Paul A.↗