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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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Investigation of the solidification, structure and properties of eutectic alloys including consideration of properties control Progress report
Solidification, structure, and properties of nickel and niobium eutectic alloys
Experimental and analytical studies of plasma transport properties Semiannual progress report, 1 Dec. 1967 - 31 May 1968
Research progress in plasma transport properties, wave interaction, electron density measurements, thermal conductivity of argon and helium, heat transfer and pressure gages
Novel pre-alloyed powder processing of modified alnico 8: Correlation of microstructure and magnetic properties
Progress is reviewed on development of an improved near-final bulk magnet fabrication process for alnico 8, as a non-rare earth permanent magnet with promise for sufficient energy density and coercivity for electric drive motors. This study showed that alnico bulk magnets in near-final shape can be made by simple compression molding from spherical high purity gas atomized pre-alloyed powder. Dwell time at peak sintering temperature (1250 °C) greatly affected grain size of the resulting magnet alloys. This microstructure transformation was demonstrated to be useful for gaining partially aligned magnetic properties and boosting energy product. While a route to increased coercivity was not identified by these experiments, manufacturability of bulk alnico magnet alloys in near-final shapes was demonstrated, permitting further processing and alloy modification experiments that can target higher coercivity and better control of grain anisotropy during grain growth.
Novel Transition Metal Compounds with Promising Thermoelectric Properties
Progress in the search for new high temperature thermoelectric materials at the Jet Propulsion Laboratory is reviewed. Novel transition metal compounds were selected as potential new high performance thermoelectric materials and criteria of selection are presented and discussed. Samples of these new compounds were prepared at JPL by a variety of techniques. Encouraging experimental results obtained on several of these compounds are reported and show that they have the potential to be the next generation of thermoelectric materials.
US Progress on Property Characterization to Support LEU U-10 Mo Monolithic Fuel Development
The US High Performance Research Reactor program is pursuing development and qualification of a new high density monolithic LEU fuel to facilitate conversion of five higher power research reactors located in the US (ATR, HFIR, NBSR, MIT and MURR). In order to support fabrication development and fuel performance evaluations, new testing capabilities are being developed to evaluate the properties of fuel specimens. Residual stress and fuel-cladding bond strength are two characteristics related to fuel performance that are being investigated. In this overview, new measurement capabilities being developed to assess these characteristics in both fresh and irradiated fuel are described. Progress on fresh fuel testing is summarized and on-going hot-cell implementation efforts to support future PIE campaigns are detailed. It is anticipated that benchmarking of as-fabricated fuel characteristics will be critical to establishing technical bases for specifications that optimize fuel fabrication and ensure acceptable in-reactor fuel performance.
Development of a 425 Foot Diameter Passive Communication Satellite with Self Erecting Properties Monthly Progress Report No. 21m, Feb. 1966
Processing equipment modifications and product development of glass fibers for passive communication satellite
Development of a 425 foot diameter passive communication satellite with self-erecting properties Quarterly progress report no. 8 and monthly progress report, May 1966
Large diameter self-erecting passive communication satellite
Development of a 425 foot diameter passive communication satellite with self-erecting properties Quarterly progress report no. 9
Flexure rigidity and tensile strength of Dacron- glass yarn and fiberglass
Planck 2015 results: XI. CMB power spectra, likelihoods, and robustness of parameters
This study presents the Planck 2015 likelihoods, statistical descriptions of the 2-point correlationfunctions of the cosmic microwave background (CMB) temperature and polarization fluctuations that account for relevant uncertainties, both instrumental and astrophysical in nature. They are based on the same hybrid approach used for the previous release, i.e., a pixel-based likelihood at low multipoles (ℓ< 30) and a Gaussian approximation to the distribution of cross-power spectra at higher multipoles. The main improvements are the use of more and better processed data and of Planck polarization information, along with more detailed models of foregrounds and instrumental uncertainties. The increased redundancy brought by more than doubling the amount of data analysed enables further consistency checks and enhanced immunity to systematic effects. It also improves the constraining power of Planck, in particular with regard to small-scale foreground properties. Progress in the modelling of foreground emission enables the retention of a larger fraction of the sky to determine the properties of the CMB, which also contributes to the enhanced precision of the spectra. Improvements in data processing and instrumental modelling further reduce uncertainties. Extensive tests establish the robustness and accuracy of the likelihood results, from temperature alone, from polarization alone, and from their combination. For temperature, we also perform a full likelihood analysis of realistic end-to-end simulations of the instrumental response to the sky, which were fed into the actual data processing pipeline; this does not reveal biases from residual low-level instrumental systematics. Even with the increase in precision and robustness, the ΛCDM cosmological model continues to offer a very good fit to the Planck data. The slope of the primordial scalar fluctuations, n s , is confirmed smaller than unity at more than 5σ from Planck alone. We further validate the robustness of the likelihood results against specific extensions to the baseline cosmology, which are particularly sensitive to data at high multipoles. For instance, the effective number of neutrino species remains compatible with the canonical value of 3.046. For this first detailed analysis of Planck polarization spectra, we concentrate at high multipoles on the E modes, leaving the analysis of the weaker B modes to future work. At low multipoles we use temperature maps at all Planck frequencies along with a subset of polarization data. These data take advantage of Planck’s wide frequency coverage to improve the separation of CMB and foreground emission. Within the baseline ΛCDM cosmology this requires τ = 0.078 ± 0.019 for the reionization optical depth, which is significantly lower than estimates without the use of high-frequency data for explicit monitoring of dust emission. At high multipoles we detect residual systematic errors in E polarization, typically at the μK 2 level; we therefore choose to retain temperature information alone for high multipoles as the recommended baseline, in particular for testing non-minimal models. Finally and nevertheless, the high-multipole polarization spectra from Planck are already good enough to enable a separate high-precision determination of the parameters of the ΛCDM model, showing consistency with those established independently from temperature information alone.
Lipid Rafts: Buffers of Cell Membrane Physical Properties
Lateral organization of lipids in the cell membrane appears to be an ancient feature of the cell, given the existence of lipid rafts in both eukaryotic and prokaryotic cells. Currently seen as platforms for protein partitioning, we posit that lipid rafts are capable of playing another role: stabilizing membrane physical properties over varying temperatures and other environmental conditions. Membrane composition defines the mechanical and viscous properties of the bilayer. The composition also varies strongly with temperature, with systematic changes in the partitioning of high and low melting temperature membrane components. In this way, rafts function as buffers of membrane physical properties, progressively counteracting environmental changes via compositional changes; i.e., more high melting lipids partition to the fluid phase with increasing temperature, increasing the bending modulus and viscosity, as thermal effects decrease these same properties. To provide an example of this phenomenon, we have performed neutron scattering experiments and atomistic molecular dynamics simulations on a phase separated model membrane. The results demonstrate a buffering effect in both the lateral diffusion coefficient and the bending modulus of the fluid phase upon changing temperature. Furthermore, this demonstration highlights the potentially advantageous stabilizing effect of complex lipid compositions in response to temperature and potentially other membrane destabilizing environmental conditions.
Numerical simulation of powered-lift flows
This article presents work performed at NASA Ames involving the application of computational fluid dynamics (CFD) to the prediction of flows encountered by powered-lift aircraft operating in ground effect. These flows are characterized by jet and jet-induced flows interacting with the ground and aerodynamic surfaces. Over the last five years, work has progressed from simulating the interaction of a single jet impacting on a ground plane, through the simulation of a delta planform with multiple jets in ground effect, to an ongoing effort to simulate the complete flow about a Harrier AV-8B in ground effect. Efforts have also been made to predict the thermal interaction between hot propulsive jets and a landing surface of arbitrary thermal properties. Progress to data in each of these areas is outlined.
Numerical simulation of powered-lift flows
This article presents work performed at NASA's Ames Research Center involving the application of Computational Fluid Dynamics (CFD) to the prediction of flows encountered by powered-lift aircraft operating in ground effect. These flows are characterized by jet and jet-induced flows interacting with the ground and aerodynamic surfaces. Over the last five years, work has progressed from simulating the interaction of a single jet impacting on a ground plane, through the simulation of a delta planform with multiple jets in ground effect, to an ongoing effort to simulate the complete flow about a Harrier AV-8B in ground effect. Efforts have also been made to predict the thermal interaction between hot propulsive jets and a landing surface of arbitrary thermal properties. Progress to date in each of these areas will be outlined.
Quantitative characterization of the spatial distribution of particles in materials: Application to materials processing
Inhomogeneities in the spatial distribution of second phase particles in engineering materials are known to affect certain mechanical properties. Progress in this area has been hampered by the lack of a convenient method for quantitative description of the spatial distribution of the second phase. This study intends to develop a broadly applicable method for the quantitative analysis and description of the spatial distribution of second phase particles. The method was designed to operate on a desktop computer. The Dirichlet tessellation technique (geometrical method for dividing an area containing an array of points into a set of polygons uniquely associated with the individual particles) was selected as the basis of an analysis technique implemented on a PC. This technique is being applied to the production of Al sheet by PM processing methods; vacuum hot pressing, forging, and rolling. The effect of varying hot working parameters on the spatial distribution of aluminum oxide particles in consolidated sheet is being studied. Changes in distributions of properties such as through-thickness near-neighbor distance correlate with hot-working reduction.
Synthesizing a protocol converter from executable protocol traces
Communicating finite state machines (CFSM's) with FIFO (first in, first out) queues are used to model a protocol converter. A protocol conversion algorithm is developed and presented for the CSFM model of the protocols A and B. A converter H for protocols A = (A0, A1) and B = (B0, B1) is viewed as a black box such that H is between sender A0 and receiver B1. This gives a resulting protocol X = (A0, H, B1). The conversion algorithm requires a specification of the message relationships between the messages of protocols A and B. It is assumed that protocols A and B have the required progress properties. The algorithm includes a search for related messages from the two protocols in an FIFO from a composite space formed by a Cartesian cross-product of state spaces A1 and B0. The search produces finite-length traces which are combined to form a state machine H, which is examined for freedom from unspecified receptions, deadlocks, and livelocks. A protocol conversion example demonstrates the applicability of the algorithm.
Evaluation of high-temperature gas transport properties first quarterly progress report, 29 apr. - 28 jul. 1965
High temperature gas transport properties - arc column temperature distributions and voltage gradients determined in nitrogen
Investigation of the Solidification, Structure and Properties of Eutectic Alloys Including Consideration of Properties Control Semiannual Progress Report
Ambient temperature fatigue and fracture, elevated temperature, and physical property research on highly anisotropic binary eutectic alloys
Progress on matrix SiC processing and properties for fully ceramic microencapsulated fuel form
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