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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 973 records · Page 54
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

THE EVOLUTION OF ASTEROIDS IN THE JUMPING-JUPITER MIGRATION MODEL

In this work, we investigate the evolution of a primordial belt of asteroids, represented by a large number of massless test particles, under the gravitational effect of migrating Jovian planets in the framework of the jumping-Jupiter model. We perform several simulations considering test particles distributed in the Main Belt, as well as in the Hilda and Trojan groups. The simulations start with Jupiter and Saturn locked in the mutual 3:2 mean motion resonance plus three Neptune-mass planets in a compact orbital configuration. Mutual planetary interactions during migration led one of the Neptunes to be ejected in less than 10 Myr of evolution, causing Jupiter to jump by about 0.3 AU in semimajor axis. This introduces a large-scale instability in the studied populations of small bodies. After the migration phase, the simulations are extended over 4 Gyr, and we compare the final orbital structure of the simulated test particles to the current Main Belt of asteroids with absolute magnitude H < 9.7. The results indicate that, in order to reproduce the present Main Belt, the primordial belt should have had a distribution peaked at ∼10° in inclination and at ∼0.1 in eccentricity. We discuss the implications of this for the Grand Tack model. The results also indicate that neither primordial Hildas, nor Trojans, survive the instability, confirming the idea that such populations must have been implanted from other sources. In particular, we address the possibility of implantation of Hildas and Trojans from the Main Belt population, but find that this contribution should be minor.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Kinematics and dynamics of disclination lines in three-dimensional nematics

An exact kinematic law for the motion of disclination lines in nematic liquid crystals as a function of the tensor order parameter Q is derived. Unlike other order parameter fields that become singular at their respective defect cores, the tensor order parameter remains regular. Following earlier experimental and theoretical work, the disclination core is defined to be the line where the uniaxial and biaxial order parameters are equal, or equivalently, where the two largest eigenvalues of Q cross. This allows an exact expression relating the velocity of the line to spatial and temporal derivatives of Q on the line, to be specified by a dynamical model for the evolution of the nematic. By introducing a linear core approximation for Q, analytical results are given for several prototypical configurations, including line interactions and motion, loop annihilation, and the response to external fields and shear flows. Behaviour that follows from topological constraints or defect geometry is highlighted. Finally, the analytic results are shown to be in agreement with three-dimensional numerical calculations based on a singular Maier–Saupe free energy that allows for anisotropic elasticity.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Particle- γ coincidence spectroscopy of the N = 90 nucleus 154 Gd by ( p,tγ )

A segmented Si-telescope and HPGe array, STARS-LIBERACE, was used to study the 156 Gd(p, tγ) 154 Gd direct reaction by particle- γ coincidence spectroscopy. New cross sections with a 25MeV proton beam are reported and compared to previous (p,t) and (t,p) studies. Furthermore, additional evidence for coexisting K π =0$_1^+$,2$_1^+$ and 0$_2^+$, 2$_2^+$ configurations at N = 90 is presented. Direct and indirect population patterns of the low-lying states are also explored. Review of the new and existing evidence favors an interpretation based on a configuration-dependent pairing interaction. The weakening of monopole pairing strength and an increase in quadrupole pairing strength could bring 2p-2h 0 + states below 2 Δ. This may account for a large number of the low-lying 0 + states observed in two-nucleon transfer reactions. A hypothesis for the origin of the 0$_2^+$ and 0$_3^+$ states is provided.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

N-S3 Cellular Vehicle-to-Everything (C-V2X) Cosimulation Framework [SWR-24-54]

This is a vehicular networking simulator designed to enable synchronized network simulation with vehicle traffic simulation software. The communications model is based on the 3GPP LTE-V2X Mode 4 protocol, but includes several other wireless network protocol models as well. This simulator includes both a V2X network simulation implemented in ns-3 as well as an interface to automatically configure, run, and interact with a set of ns-3 instances based on network size and available hardware. This software has been tested with Aimsun NEXT 2.0 simulator (with V2X SDK), but uses a generic interface for compatibility with any comparable vehicle traffic simulator across the HELICS co-simulation framework. This software is intended as a generalized extension to vehicle traffic simulation, and does not model any vehicle traffic on its own.

Wang, Qichao↗
NASA NTRS1973

Space Shuttle External Tank.

During the quarter hour of its operational life, the External Tank must provide the propellants and propellant conditioning for the Orbiter Main Engines, provide the structural support for the two Solid Rocket Boosters, withstand the natural and induced environments, and effect a safe disposal. The External Tank is twice the size of the S-II Stage used in the Saturn V Booster for the Apollo and Skylab Spacecrafts. The External Tank is 182 feet long, 27 feet in diameter, and carries 1,700,000 pounds of liquid oxygen and liquid hydrogen propellants. The Shuttle System configuration and the interaction of the system elements pose an intricate system sensitivity which must be analyzed to establish the performance and sizing requirements for the External Tank.

Zoller, L. K.↗
NASA NTRS1976

Three-dimensional interplanetary stream magnetism and energetic particle motion

Cosmic rays interact with mesoscale configurations of the interplanetary magnetic field. A technique is presented for calculating such configurations in the inner solar system, which are due to streams and source conditions near the sun, and maps of magnetic field are constructed for some plausible stream and source conditions. One effect of these mesoscale configurations on galactic cosmic rays is shown to be an out-of-the-ecliptic gradient drift sufficient to explain Forbush decreases. The effects on solar energetic particles include small polar drifts due to the field gradients and a possibly large modification of the time-intensity profiles and anisotropy characteristics due to the formation of mirror configurations in space. If a diffusion model is applicable to solar particles, the true diffusion coefficient will be masked by the effects of streams. A conceptual model which incorporates these ideas and those of several other models is presented.

Barouch, E.↗
NASA NTRS1979

Investigation of effects of temperature, salinity, and electrode design on the performance of an electrochemical coliform detector

The results of two research programs to determine the optimum detector design for measuring fecal coliforms in saline waters for operational systems are presented. One program was concerned with the effects of temperature and salinity on endpoint response time, and the other, the interaction between electrode configurations and the test organisms. Test results show that the endpoint response time is related to salinity and seawater temperature; however, these results can be minimized by the correct choice of growth media. Electrode configurations were developed from stainless steel, Parlodion-coated stainless steel, and platinum that circumvented problems associated with the commercial redox electrodes.

Grana, D. C.↗
NASA NTRS1980

A polymorphic reconfigurable emulator for parallel simulation

Microprocessor and arithmetic support chip technology was applied to the design of a reconfigurable emulator for real time flight simulation. The system developed consists of master control system to perform all man machine interactions and to configure the hardware to emulate a given aircraft, and numerous slave compute modules (SCM) which comprise the parallel computational units. It is shown that all parts of the state equations can be worked on simultaneously but that the algebraic equations cannot (unless they are slowly varying). Attempts to obtain algorithms that will allow parellel updates are reported. The word length and step size to be used in the SCM's is determined and the architecture of the hardware and software is described.

Parrish, E. A., Jr.↗
NASA NTRS1984

Integrated optical signal processing with magnetostatic waves

Magneto-optical devices based on Bragg diffraction of light by magnetostatic waves (MSW's) offer the potential of large time-bandwidth optical signal processing at microwave frequencies of 1 to 20 GHz and higher. A thin-film integrated-optical configuration, with the interacting MSW and guided-optical wave both propagating in a common ferrite layer, is necessary to avoid shape-factor demagnetization effects. The underlying theory of the MSW-optical interaction is outlined, including the development of expressions for optical diffraction efficiency as a function of MSW power and other relevant parameters. Bradd diffraction of guided-optical waves by transversely-propagating magnetostatic waves and collinear TE/TM mode conversion included by MSW's have been demonstrated in yttrium iron garnet (YIG) thin films. Diffraction levels as large as 4% (7 mm interaction length) and a modulation dynamic range of approx 30 dB have been observed. Advantages of these MSW-based devices over the analogous acousto-optical devices include: much greater operating frequencies, tunability of the MSW dispersion relation by varying either the RF frequency or the applied bias magnetic field, simple broad-band MSW transducer structures (e.g., a single stripline), and the potential for very high diffraction efficiencies.

Fisher, A. D.↗
NASA NTRS1984

Flight evaluation of Spacelab 1 payload thermal/ECS interfaces

The Spacelab (SL-1) thermal/Environmental Control Systems (ECS) are discussed. Preflight analyses and flight data are compared in order to validate payload to Spacelab interfaces as well as corroborate modeling/analysis techniques. In doing so, a brief description of the Spacelab 1 payload configuration and the interactive Spacelab thermal/ECS systems are given. In particular, these interfaces address equipment cooling air, thermal and fluid conditions, humidity levels, both freon and water loop temperatures and load states, as well as passive radiant environment interfaces.

Ray, C. D.↗
NASA NTRS1986

A rule based computer aided design system

A Computer Aided Design (CAD) system is presented which supports the iterative process of design, the dimensional continuity between mating parts, and the hierarchical structure of the parts in their assembled configuration. Prolog, an interactive logic programming language, is used to represent and interpret the data base. The solid geometry representing the parts is defined in parameterized form using the swept volume method. The system is demonstrated with a design of a spring piston.

Premack, T.↗
NASA NTRS1992

Analysis of composite structures with delaminations under combined bending and compression

A methodology had been developed for strength prediction of composite structures with delaminations under combined bending and compression loads. The methodology is an extension of the delamination analysis method developed under the USAF/Boeing/Northrop 'Damage Tolerance of Composites' program. Delamination buckling and strain energy release rate analyses are used as basic tools in the strength prediction. In addition, failure mode interaction and structural configuration effects are considered. The influence of fasteners on the strength of a delaminated structure is incorporated to evaluate assembly-caused delaminations. The capabilities and limitations of the analysis method are shown by correlating the analytical results with the existing experimental data. The failure load, failure mode and failure sequence of a structure containing delaminations are predicted and the analytical results are compared with test data.

Kan, Han-Pin↗
NASA NTRS1994

Motion of the heliospheric termination shock. 4: MHD effects

In this paper we generalize earlier gasdynamic analyses of the motion of the heliospheric termination shock in response to upstream disturbances (Barnes, 1993, 1994; Naidu and Barnes, 1994), to include magnetohydrodynamic (MHD) phenomena. We assume that the termination shock is a strong, perpendicular shock and that the initial upstream disturbance is a tangential discontinuity. The resulting configuration after the interaction is very similar to that in the gasdynamic models after an interaction with a contact discontinuity or interplanetary shock, and for an increase (decrease) in dynamic pressure consists of an outward (inward) propagating termination shock and an outward propagating shock (MHD rarefraction wave) that carries the signal of the disturbance into the far downstream plasma. The plasma immediately behind the new termination shock is separated from the downstream signal by a tangential discontinuity. The results of the model show that the speed of the new termination shock depends mainly on the magnitude of the change in dynamic pressure and are typically of order approximately 100 km/s, comparable to the results of the gasdynamic models.

Naidu, Kamcilla↗
NASA NTRS1994

Motion of the Heliospheric Termination Shock: MHD Effects - 4

In this paper we generalize earlier gasdynamic analyses of the motion of the heliospheric termination shock in response to upstream disturbances to include magnetohydrodynamic (MHD) phenomena. We assume that the termination shock is a strong, perpendicular shock and that the initial upstream disturbance is a tangential discontinuity. The resulting configuration after the interaction is very similar to that in the gasdynamic models after an interaction with a contact discontinuity or interplanetary shock, and for an increase (decrease) in dynamic pressure consists of an outward (inward) propagating termination shock and an outward propagating shock (MHD rarefaction wave) that carries the signal of the disturbance into the far downstream plasma. The plasma immediately behind the new termination shock is separated from the downstream signal by a tangential discontinuity. The results of the model show that the speed of the new termination shock depends mainly on the magnitude of the change in dynamic pressure and are typically of order -100 km/s, comparable to the results of the gasdynamic models.

Naidu, Kamcilla↗
NASA NTRS1998

Shock Wave Boundary Layer Interactions in High Mach Number Flows: A Critical Survey of Current Numerical Prediction Capabilities

The report assesses the capability for numerical simulation of 2-D and 3-D shock wave laminar and turbulent boundary layer interactions Three fundamental configurations are considered: single fin, double fin, and hollow cylinder flare. Thirteen separate cases were examined by a distinguished international group of researchers using the Reynolds-averaged Navier-Stokes (RANS) equations with a wide range of turbulence models from zero equation to full Reynolds Stress Equation formulations. The report presents an extensive comparison of computations and experimental data, summarizes the results, and makes recommendations for future research.

Doyle D. Knight↗
NASA NTRS2000

Reusable Launch Vehicle Tank/Intertank Sizing Trade Study

A tank and intertank sizing tool that includes effects of major design drivers, and which allows parametric studies to be performed, has been developed and calibrated against independent representative results. Although additional design features, such as bulkheads and field joints, are not currently included in the process, the improved level of fidelity has allowed parametric studies to be performed which have resulted in understanding of key tank and intertank design drivers, design sensitivities, and definition of preferred design spaces. The sizing results demonstrated that there were many interactions between the configuration parameters of internal/external payload, vehicle fineness ratio (half body angle), fuel arrangement (LOX-forward/LOX-aft), number of tanks, and tank shape/arrangement (number of lobes).

Dorsey, John T.↗
NASA NTRS2003

Alloy Design Workbench-Surface Modeling Package Developed

NASA Glenn Research Center's Computational Materials Group has integrated a graphical user interface with in-house-developed surface modeling capabilities, with the goal of using computationally efficient atomistic simulations to aid the development of advanced aerospace materials, through the modeling of alloy surfaces, surface alloys, and segregation. The software is also ideal for modeling nanomaterials, since surface and interfacial effects can dominate material behavior and properties at this level. Through the combination of an accurate atomistic surface modeling methodology and an efficient computational engine, it is now possible to directly model these types of surface phenomenon and metallic nanostructures without a supercomputer. Fulfilling a High Operating Temperature Propulsion Components (HOTPC) project level-I milestone, a graphical user interface was created for a suite of quantum approximate atomistic materials modeling Fortran programs developed at Glenn. The resulting "Alloy Design Workbench-Surface Modeling Package" (ADW-SMP) is the combination of proven quantum approximate Bozzolo-Ferrante-Smith (BFS) algorithms (refs. 1 and 2) with a productivity-enhancing graphical front end. Written in the portable, platform independent Java programming language, the graphical user interface calls on extensively tested Fortran programs running in the background for the detailed computational tasks. Designed to run on desktop computers, the package has been deployed on PC, Mac, and SGI computer systems. The graphical user interface integrates two modes of computational materials exploration. One mode uses Monte Carlo simulations to determine lowest energy equilibrium configurations. The second approach is an interactive "what if" comparison of atomic configuration energies, designed to provide real-time insight into the underlying drivers of alloying processes.

Abel, Phillip B.↗