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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Tailoring High Hardness and Rigidity in Biodegradable Thermoplastic Polyurethanes

In response to escalating environmental concerns, there is a pressing demand for materials capable of delivering both sustainability and robust mechanical properties, thereby substituting nonrenewable counterparts in various applications. This study presents a comprehensive investigation into the synthesis and characterization of biobased aliphatic thermoplastic polyurethanes (TPUs) that exhibit impressive mechanical properties, including tensile strength in the range of 48–41 MPa and flexural modulus up to 2.2 GPa. These biodegradable TPUs displayed high shore A and D hardness between 95 and 98 and 51–42, respectively, and thus can be categorized as “extra hard” plastics according to the durometer scale for PUs. Herein, we have prepared a series of four 100% biobased polyester polyols from biobased diacid and chain-extender as precursors with molecular weights varying from 500 to 1400 g/mol. The corresponding TPUs that were prepared by using an aliphatic diisocyanate were evaluated for their thermal stability, microphase separation, mechanical properties, and biodegradation. By leveraging renewable feedstocks, these TPUs offer a sustainable alternative to petroleum-derived materials, with their mechanical performance meeting conventional benchmarks. Furthermore, postcomposting analysis revealed significant surface degradation, affirming their biodegradability and environmental compatibility.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Dry electrodes with a printed cellulose–graphene ink for low-profile strain sensors in electromyography

Dihydrolevoglucosenone, commonly known as Cyrene, is a renewable and fully biodegradable cellulose-waste derived, environmentally friendly solvent, presenting a non-toxic alternative to N-methyl-2-pyrrolidone (NMP). Currently, solution-based processing of graphene and other similar van der Waals solids favor toxic solvents such as NMP, limiting their use for biosensing. However, with the use of Cyrene, bio-compatible printable devices are possible, and studies have already demonstrated its use in temperature and other biosensing methods through screen-printing. Screen-printing unfortunately often requires masks that constrain the minimum acquirable feature size to be above hundreds of centimeters and wastes material, adding to process complexity and cost. Conversely, inkjet-printing is an attractive alternative for the maskless patterning of hierarchically assembled structures, with micron length scales attainable. Graphene's high conductivity positions it ideally for long-wear sensors such as dry electrodes or respiration monitors. Here, we demonstrate the potential of Cyrene-based graphene inks through few-layer inkjet printing on flexible substrates for the first time, to produce non-toxic conductors toward a strain-mediated mechanism for biosensing, used to detect bodily motion for wearable electronics. The challenges overcome in this study include engineering ink chemistry and printing parameters such that Cyrene's relatively high viscosity compared to typical inkjet solvents, still allows for droplet ejection in a conventional material printer, yielding well-resolved clean line-edges in contrast to other solvents that exhibit diffuse line-edges possibly from stray droplets and ink-splashing. Temperature-dependent transport measurements on the inkjet-printed Cyrene-based graphene films showed the conductivity to be largely temperature-invariant but at lower temperatures below 100 K, conductivity decreased, likely as a result of increased inter-membrane separation arising from thermal contraction. Additionally, temperature-dependent Raman spectroscopy showed the red-shift in the G-band, 2D-band and D-band peaks, as temperature increased. As a result, by validating flexion motion detection of the proximal interphalangeal joint demonstrated in this study, our work is the first of its kind to successfully additively manufacture inkjet-printed Cyrene-based graphene strain sensors on flexible substrates for bio-sensing and wearables.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Localized modes in the IR phase of QCD

Infrared (IR) dimension function d IR ( λ ) characterizes the space effectively utilized by QCD quarks at Dirac scale λ , and indirectly the space occupied by glue fields. It was proposed that its nonanalytic behavior in thermal reflects the separation of QCD system into an IR component and an independent bulk. Here we study the “plateau modes” in the IR component, whose dimensional properties were puzzling. Indeed, in the recent scenario of transition to IR phase, this low-dimensional plateau connects the Anderson-like mobility edge λ IR = 0 in Dirac spectrum with mobility edges ± λ A . For this structure to be truly Anderson-like, plateau modes have to be exponentially localized, implying that both the effective distances L eff ∝ L γ and the effective volumes V eff ∝ L d IR in these modes grow slower than any positive power of IR cutoff L . Although γ = 0 was confirmed in the plateau, it was found that d IR ≈ 1 . Here we apply the recently proposed technique to the problem. We conclude that a plateau mode of pure-glue QCD at UV cutoff a = 0.085 fm occupies a subvolume of IR dimension zero with probability at least 0.9999, substantiating this aspect of metal-to-critical scenario to a respective degree. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Micromechanical origin of heat transfer to granular flow

Heat transfer across a granular flow is comprised of two resistances in series : near the wall and within the bulk particle bed, neither of which is well understood due to the lack of experimental probes to separate their respective contribution. Here, we use a frequency modulated photothermal technique to separately quantify the thermal resistances in the near-wall and the bulk bed regions of particles in flowing states. Compared to the stationary state, the flowing leads to a higher near-wall resistance and a lower thermal conductivity of bulk beds. As a result, coupled with discrete element method simulation, we show that the near-wall resistance can be explained by particle diffusion in granular flows.

14 SOLAR ENERGY↗
DOE OSTI2023

Artificial Magnetic Tripod Ice

We study the collective behavior of interacting arrays of nanomagnetic tripods. These objects have six discrete moment states, in contrast to the usual two states of an Ising-like moment. Our experimental data demonstrate that triangular lattice arrays form a “tripod ice” that exhibits charge ordering among the effective vertex magnetic charges, in direct analogy to artificial kagome spin ice. The results indicate that the interacting tripods have effective moments that act as emergent local variables, with strong connections to the well-studied Potts and clock models. In addition, the tripod moments display a tendency toward a nearest neighbor alignment in our thermalized samples that separates this system from kagome spin ice. In conclusion, our results open a path toward the study of the collective behavior of nonbinary moments that is unavailable in other physical systems.

36 MATERIALS SCIENCE↗
DOE OSTI2023

High Inlet Temperature Combustor for Direct-Fired Supercritical Oxy-Combustion

It is envisioned that supercritical CO 2 (sCO 2 ) electric power plant efficiencies can exceed 52% with 99% carbon capture using direct-fired oxy-combustion. Such efficiencies would be competitive with Natural Gas Combined Cycles (NGCC) and operate with nearly zero carbon emissions. To achieve high plant efficiencies, turbine inlet conditions must approach 1,200 °C at 250 bar. Such conditions, while desirable from a systems perspective, exceed the current state of the art in turbine design and materials qualification. The team of Southwest Research Institute ® (SwRI ® ), Georgia Institute of Technology (Georgia Tech), Spectral Energies, LLC (Spectral), GE Global Research (GE-GRC), and the University of Central Florida (UCF) sought to demonstrate an intermediate step toward these high efficiency plants with the development of a 1 MWth, subscale direct-fired oxy-fuel combustor. The efforts focused largely on the development of an auto-ignition based combustion system capable of providing the targeted 1200 °C and the pilot-scale plant to operate the combustor. While the project was stopped short of the commissioning and demonstration work, the advances made in this effort will reduce risks associated with chemical kinetics, thermal management, water separation, flue gas cleanup, materials selection, and corrosion in future demonstration efforts for the direct-fired oxy-fuel combustion cycles. The following report documents the design, analysis, and installation efforts completed during the project periods of performance.

03 NATURAL GAS↗
NASA NTRS1973

Development of and dynamic studies concerning a cable boom system prototype

The conception of a cable boom system for a scientific spin stabilized satellite led to a flat cable stowed on a drum with a flexlead without conversion to avoid slip rings and to facilitate automatic restowage from any state of deployment. Some dynamic features of the extended cable boom and especially the comparison between round and flat cables were investigated in a phenomenological study using a test rig capable of inducing lateral, torsional and thermal cycling disturbances separately or in any combination.

Bring, G.↗
NASA NTRS1975

Automated space processing payloads study. Volume 2, book 2: Technical report, appendices A through E

Experiment hardware and operational requirements for space shuttle experiments are discussed along with payload and system concepts. Appendixes are included in which experiment data sheets, chamber environmental control and monitoring, method for collection and storage of electrophoretically-separated samples, preliminary thermal evaluation of electromagnetic levitation facilities L1, L2, and L3, and applicable industrial automation equipment are discussed.

Source record↗
NASA NTRS1980

Seismic velocity, attenuation and rheology of the upper mantle

Seismic and rheological properties of the upper mantle in the vicinity of the low-velocity zone are expressed in terms of relaxation by dislocation glide. Dislocation bowing in the glide plane explains seismic velocities and attenuation. Climbing at higher stresses for longer periods of time give the observed viscosity, and explain the low velocity and high temperature attenuation found at seismic frequencies. Due to differing parameters, separate terms for thermal, seismic and rheological lithospheres are proposed. All three lithospheres, however, are related and are functions of temperature, and must be specified by parameters such as period, stress, and stress duration.

Anderson, D. L.↗
NASA NTRS1986

Wall temperature control of low-speed body drag

The use of thermal means to control drag under turbulent boundary layer conditions is examined. Numerical calculations are presented for both skin friction and (unseparated) pressure drag for turbulent boundary-layer flows over a fuselage-like body with wall heat transfer. In addition, thermal control of separation on a bluff body is investigated. It is shown that a total drag reduction of up to 20 percent can be achieved for wall heating with a wall-to-total-freestream temperature ratio of 2. For streamlined slender bodies, partial wall heating of the forebody can produce almost the same order of total drag reduction as the full body heating case. For bluff bodies, the separation delay from partial wall cooling of the afterbody is approximately the same as for the fully cooled body.

Lin, J. C.↗
NASA NTRS1987

On the heating of electrons in the tail of Giacobini-Zinner

Computations for the temperature and density of electrons for Comet Giacobini-Zinner are presented which differ from those of Marconi and Mendis (1986) in the use of recently calculated cooling rates, and in the treating of photoelectrons separately from the thermalized electrons with respect to their collisions with the neutrals. The present temperatures are found to be high relative to the ICE observations, though the calculated densities are consistent with these observations.

Marconi, M. L.↗
NASA NTRS1992

Orbiter attitude design for the Astro-1 Spacelab mission

The methods utilized to design orbiter attitudes that satisfied the various Space Shuttle program and payload constraints of the Astro-1 Spacelab astronomy mission are described. The premission methods developed for attitude design and how those methods were applied to accomplish the large amount of real-time replanning required during the flight are presented. Some of the attitude concerns for Astro-1 included orbiter window thermal constraints, two separate telescope fields-of-view, tracking and data relay satellite Ku-band access, and telescope sun avoidance.

Olsen, C. D.↗
NASA NTRS2002

The Multi-Component Nature of the Vela Pulsar Nonthermal X-ray Spectrum

We report on our analysis of a 274 ks observation of the Vela pulsar with the Rossi X-Ray Timing Explorer (RXTE). The double-peaked, pulsed emission at 2 - 30 keV, which we had previously detected during a 93 ks observation, is confirmed with much improved statistics. There is now clear evidence, both in the spectrum and the light curve, that the emission in the RXTE band is a blend of two separate non-thermal components. The spectrum of the harder component connects smoothly with the OSSE, COMPTEL and EGRET spectrum and the peaks in the light curve are in phase coincidence with those of the high-energy light curve. The spectrum of the softer component is consistent with an extrapolation to the pulsed optical flux, and the second RXTE pulse is in phase coincidence with the second optical peak. In addition, we see a peak in the 2-8 keV RXTE pulse profile at the radio phase.

Harding, Alice K.↗
NASA NTRS2015

Surface Acoustic Wave Monitor for Deposition and Analysis of Ultra-Thin Films

A surface acoustic wave (SAW) based thin film deposition monitor device and system for monitoring the deposition of ultra-thin films and nanomaterials and the analysis thereof is characterized by acoustic wave device embodiments that include differential delay line device designs, and which can optionally have integral reference devices fabricated on the same substrate as the sensing device, or on a separate device in thermal contact with the film monitoring/analysis device, in order to provide inherently temperature compensated measurements. These deposition monitor and analysis devices can include inherent temperature compensation, higher sensitivity to surface interactions than quartz crystal microbalance (QCM) devices, and the ability to operate at extreme temperatures.

Hines, Jacqueline H.↗
NASA NTRS2018

Passive Thermal Management Systems Employing Shape Memory Alloys

A thermal management system includes a first substrate having a first conductive inner surface. A second substrate has a second conductive inner surface. A connecting structure is attached to the first and second substrates to space apart the first and second inner surfaces defining an insulating space for a single architecture. One or more passively-acting elements are attached to the inner surface of at least one substrate and including a shape memory material such as a shape memory alloy (SMA). The SMA passively reacts to the temperature of the first substrate by thermally contacting or separating from the second inner surface of the second substrate for the control of the conduction of heat energy in either direction.

Trigwell, Steven↗
DOE OSTI2024

Hydrogen infused nuclear reactor core monoliths

Hydrogen infused nuclear reactor core monoliths and processes for their production are disclosed. Such monoliths may function as both a core monolith and a moderator, providing structure and at least some moderation. Hydrogen infused monoliths may be complementary to or be used in lieu of separate moderators for thermalizing neutrons.

Shivprasad, Aditya↗
DOE OSTI2021

Simultaneously Blocking Chemical Crosstalk and Internal Short Circuit via Gel-Stretching Derived Nanoporous Non-Shrinkage Separator for Safe Lithium-Ion Batteries

The separator, an ionic permeable and electronic insulating membrane between cathode and anode, plays a crucial role in the electrochemical and safety performance of batteries. However, the commercial polyolefin separators not only suffer from inevitable thermal shrinkage at elevated temperature, but also fail to inhibit the hidden chemical crosstalk of reactive gases such as O 2 , leading to often reported thermal runaway (TR) and hence preventing large-scale implementation of high-energy-density lithium-ion batteries. Herein, a nanoporous non-shrinkage separator (GS-PI) was fabricated via a novel gel-stretching orientation approach to eliminate TR. In situ synchrotron small angle X-ray scattering during heating clearly showed that the as-prepared thin GS-PI separator exhibits superior mechanical tolerance at high temperature, thus effectively preventing internal short circuit. Meanwhile, the unique nanoporous structure design further blocks chemical crosstalk and the associated exothermic reactions. Accelerating Rate Calorimetry test revealed that the practical 1 Ah LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622)/graphite pouch cell using GS-PI nanoporous separator show a maximum temperature rise (dT/dt max ) of only 3.7 °C s -1 compared to 131.6 °C s -1 in the case of Al 2 O 3 @PE macroporous separator. Furthermore, despite the reduced pore size, the GS-PI separator demonstrates better cycling stability than conventional Al 2 O 3 @PE separator at high temperature without sacrificing specific capacity and rate capability.

25 ENERGY STORAGE↗
NASA NTRS2013

An Update on the Non-Mass-Dependent Isotope Fractionation under Thermal Gradient

Mass flow and compositional gradient (elemental and isotope separation) occurs when flu-id(s) or gas(es) in an enclosure is subjected to a thermal gradient, and the phenomenon is named thermal diffusion. Gas phase thermal diffusion has been theoretically and experimentally studied for more than a century, although there has not been a satisfactory theory to date. Nevertheless, for isotopic system, the Chapman-Enskog theory predicts that the mass difference is the only term in the thermal diffusion separation factors that differs one isotope pair to another,with the assumptions that the molecules are spherical and systematic (monoatomic-like structure) and the particle collision is elastic. Our previous report indicates factors may be playing a role because the Non-Mass Dependent (NMD) effect is found for both symmetric and asymmetric, linear and spherical polyatomic molecules over a wide range of temperature (-196C to +237C). The observed NMD phenomenon in the simple thermal-diffusion experiments demands quantitative validation and theoretical explanation. Besides the pressure and temperature dependency illustrated in our previous reports, efforts are made in this study to address issues such as the role of convection or molecular structure and whether it is a transient, non-equilibrium effect only.

Sun, Tao↗