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NASA NTRS2011

Share the Sky: Concepts and Technologies That Will Shape Future Airspace Use

The airspace challenge for the United States is to protect national sovereignty and ensure the safety and security of those on the ground and in the air, while at the same time ensuring the efficiency of flight, reducing the costs involved, protecting the environment, and protecting the freedom of access to the airspace. Many visions of the future NAS hold a relatively near-term perspective, focusing on existing uses of the airspace and assuming that new uses will make up a small fraction of total use. In the longer term, the skies will be filled with diverse and amazing new air vehicles filling our societal needs. Anticipated new vehicles include autonomous air vehicles acting both independently and in coordinated groups, unpiloted cargo carriers, and large numbers of personal air vehicles and small-scale point-to-point transports. These vehicles will enable new capabilities that have the potential to increase societal mobility, transport freight at lower cost and with lower environmental impact, improve the study of the Earth s atmosphere and ecosystem, and increase societal safety and security by improving or drastically lowering the cost of critical services such as firefighting, emergency medical evacuation, search and rescue, border and neighborhood surveillance, and the inspection of our infrastructure. To ensure that uses of the airspace can continue to grow for the benefit of all, a new paradigm for operations is needed: equitably and safely sharing the airspace. This paper is an examination of such a vision, concentrating on the operations of all types of air vehicles and future uses of the National Airspace. Attributes of a long-term future airspace system are provided, emerging operations technologies are described, and initial steps in research and development are recommended.

Ballin, Mark G.↗

NASA NTRS2015

Elastic and Piezoelectric Properties of Boron Nitride Nanotube Composites: Finite Element Model - Part II

This paper is the second part of a two-part series where the first part presents a molecular dynamics model of a single Boron Nitride Nanotube (BNNT) and this paper scales up to multiple BNNTs in a polymer matrix. This paper presents finite element (FE) models to investigate the effective elastic and piezoelectric properties of (BNNT) nanocomposites. The nanocomposites studied in this paper are thin films of polymer matrix with aligned co-planar BNNTs. The FE modelling approach provides a computationally efficient way to gain an understanding of the material properties. We examine several FE models to identify the most suitable models and investigate the effective properties with respect to the BNNT volume fraction and the number of nanotube walls. The FE models are constructed to represent aligned and randomly distributed BNNTs in a matrix of resin using 2D and 3D hollow and 3D filled cylinders. The homogenisation approach is employed to determine the overall elastic and piezoelectric constants for a range of volume fractions. These models are compared with an analytical model based on Mori-Tanaka formulation suitable for finite length cylindrical inclusions. The model applies to primarily single-wall BNNTs but is also extended to multi-wall BNNTs, for which preliminary results will be presented. Results from the Part 1 of this series can help to establish a constitutive relationship for input into the finite element model to enable the modeling of multiple BNNTs in a polymer matrix.

Kim, H. Alicia↗

DOE OSTI2020

Pore-Filled PEMs from Poly(Phenylene Sulfonic Acid)s and Electrospun Poly(Phenylene Sulfone) Fiber Mats

A novel, composite, non-PFSA-based fuel cell membrane has been fabricated using a pore filling technique. The membrane consists of a mechanically stabilizing skeleton from an electrospun poly(phenylene sulfone) (PPSU) fiber mat and a thermally crosslinkable poly(phenylene sulfonic acid) (cPPSA) proton conducting ionomer that fills the interfiber voids. cPPSA copolymer was synthesized using Ullmann coupling copolymerization of 4,4-dibromobiphenyl 3,3-disulfonic acid with 1,4-dibromobenzene-2,5-disulfonic, followed by grafting a certain fraction of backbone sulfonic acid groups with biphenyl linker. The PPSU fiber mat was electrospun from NMP/acetone solution. Pore-filling was carried out by pouring a solution of cPPSA in methanol over the mat, followed by heating at 70°C to evaporate solvent. The cPPSA was crosslinked by an additional heating step, in a vacuum oven at 210°C for 5 hours. Here the resultant membrane had excellent proton conductivity, 5 times greater than that of Nafion® 211 in the 40-90% RH range at 80°C.

25 ENERGY STORAGE↗

DOE OSTI2020

Theoretical phase diagram of two-component composite fermions in double-layer graphene

Theory predicts that double layer systems realize “two-component composite fermions,” which are formed when electrons capture both intra- and inter-layer vortices, to produce a wide variety of new strongly correlated liquid and crystal states as a function of the layer separation. Recent experiments in double layer graphene have revealed a large number of layer-correlated fractional quantum Hall states in the lowest Landau level, many of which have not been studied quantitatively in previous theoretical works. We consider the competition between various liquid and crystal states at several of these filling factors (specifically, the states at total filling factors ν = 3/7, 4/9, 6/11, 4/7, 3/5, 2/3, and 4/5) to determine the theoretical phase diagram as a function of the layer separation. We compare our results with experiments and identify various observed states. In particular, we show that at small layer separations the states at total fillings ν = 3/7 and ν = 3/5 are partially pseudospin polarized, where pseudospin refers to the layer index. For certain fractions, such as ν = 3/7, interlayer correlations are predicted to survive to surprisingly large interlayer separations.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

NASA NTRS1981

A UBV photometric study of the 5.2 hour X-ray binary 4U 2129+47

The paper presents results derived from UBV photometric observations of the 5.2 X-ray binary 4U 2129+47 which were made on 11 nights between 1978 October and 1979 August. The light curves observed during this period are relatively stable in shape and amplitude (Delta B = 1.5 mag) and are a surprisingly close match to the time-averaged light curves observed for HZ Her. There is a significant asymmetry in their shape which is independent of color and varies in amplitude by a factor of approximately 2. The UBV colors at minimum light suggest a considerably earlier spectral type (G or earlier) than is inferred by assuming that the star fills its Roche lobe (late K or early M). Optical pulsations were studied, and a 3 sigma limit of 0.5% was set on the fraction of the flux which is pulsed for periods between 60 ms and 300 s. Assuming that the optical companion is a normal main-sequence star filling its Roche lobe, its mass is approximately 0.65 solar mass. Assuming also that the compact object has a mass of 1.3 solar masses and that the orbital inclination of the system is approximately 90 deg, it is found that the orbital separation is approximately 1.9 solar radii and K-opt is approximately 300 km/s.

Mcclintock, J. E.↗

NASA NTRSDate not supplied

A Chlorine Isotope Transect Across the Sudbury Impact Deposits Reveals Enigmatic Isotopic Fractionation

Volatile elements play an important role in a variety of cosmochemical and geochemical processes. As such, there has been significant interest in their abundance and isotopic composition. Chlorine is an important element for tracing these processes because it is incompatible in nearly all minerals, extremely volatile, and strongly hydrophilic [1]. The Cl isotope composition ( 37 Cl/ 35 Cl) of meteoritic components, therefore, can provide useful information regarding the isotopic reservoirs that were present in the early Solar System and any secondary processes that may have occurred on different parent bodies (e.g., [2-4]). There is a relatively narrow range in the Cl isotope compositions of terrestrial, Martian, and chondritic meteorites (δ 37 Cl ~ −6 to +4‰) (e.g., [2,3,5,6]), with exceptions to this being the Moon and Vesta (up to ~ +81‰ and ~ +40‰, respectively) [4, 5, 7-10]. One hypothesis for the extreme Cl isotope fractionation observed on the Moon is degassing following large-scale (possibly even crust-breaching) impact events [7-9]. The role of hypervelocity impacts and impact-generated magmatism in the isotopic evolution of planetary materials, however, has been until recently an area of limited published research with the majority of works focusing on the effects of impact shock (e.g., [10-13]). The ~ 1.85 Ga Sudbury impact crater [14] located in Ontario, Canada, is one of the three largest impact craters on Earth with good exposures of its impact melt sheet and overlying breccias [15,16]. The impact melt sheet, called the Sudbury Igneous Complex (SIC), is up to 5 km thick [17], with an estimated original volume of >10 4 km 3 [18], and differentiated. Recent work demonstrated evaporative loss and isotope fractionation of the moderately volatile element zinc and suggest melt sheets produced by impacts could have a significant effect on the Earth’s volatile inventory [19]. In this study we investigate the abundance and isotopic composition of Cl as well the water abundance of apatite from the SIC and the overlying crater-fill to test the hypothesis that large-scale impacts may have generated the extensive Cl isotopic fractionation observed on the Moon.

Sudbury↗

NASA NTRS2016

Heat Exchanger Performance Impacts on Optimum Cost Conditions in Thermoelectric Energy Recovery Designs

Cost is just as important as power density or efficiency for the adoption of waste heat recovery thermoelectric generators (TEG). Prior work [1] has shown that the system design that minimizes cost (e.g., the $/W value) can be close to the designs that maximize the system’s efficiency or power density, however, it is important to understand the relationship between those designs to optimize TEG performance-cost compromises. Expanding on recent work [1, 2, 3] the impact of heat exchanger conditions on the optimum TEG fill factors and cost scaling of a waste heat recovery thermoelectric generator with a detailed treatment of the hot side exhaust heat exchanger has been investigated further. The effect of the heat lost to the environment and updated relationships between the hot-side and cold-side conductances [4] that maximize power output are considered. The optimum fill factor to minimize TEG energy recovery system costs is strongly dependent on the heat leakage fraction, σ, the mass flow rate of the exhaust, the hot-side heat exchanger effectiveness, heat exchanger UAh, and heat flux. These relationships are explored and characterized for typical exhaust gas-flow conditions to show the inherent design complexities. The heat exchanger costs often dominate the TEG cost equation and it is critical to fully understand the tradeoff between heat exchanger performance, optimum TEG fill factors, and cost to establish potentially optimum design points within the cost-performance design space. This work will explore the design tradeoffs and relationships within the cost-efficiency-power density design space for a typical thermoelectric energy recovery system application. The interplay between optimum TEG fill factors and heat exchanger design can impact system footprint, volume, and mass in weight-sensitive applications. Less-effective, low-cost heat exchangers may outperform higher cost alternatives from a market adoption perspective. This shift of emphasis acknowledging the interdependence of optimum TEG fill factors and heat exchanger performance has significant implications on thermoelectric waste heat recovery systems designs and their operation. In addition, preferred TEG design regimes exist that accommodate reasonable compromises in TE performance and cost. This effort highlights how the optimum fill factor–heat exchanger performance relations couple to these optimum TEG performance-cost domains based on TEG-system-level analyses and provides a focus for future system research and development efforts.

Energy recovery↗

NASA NTRS2011

Molecular Gas in Young Debris Disks

Gas-rich primordial disks and tenuous gas-poor debris disks are usually considered as two distinct evolutionary phases of the circumstellar matter. Interestingly, the debris disk around the young main-sequence star 49 Ceti possesses a substantial amount of molecular gas and possibly represents the missing link between the two phases. Motivated to understand the evolution of the gas component in circumstellar disks via finding more 49 Ceti-like systems, we carried out a CO J = 3-2 survey with the Atacama Pathfinder EXperiment, targeting 20 infrared-luminous debris disks. These systems fill the gap between primordial and old tenuous debris disks in terms of fractional luminosity. Here we report on the discovery of a second 49 Ceti-like disk around the 30 Myr old A3-type star HD21997, a member of the Columba Association. This system was also detected in the CO(2-1) transition, and the reliable age determination makes it an even clearer example of an old gas-bearing disk than 49 Ceti. While the fractional luminosities of HD21997 and 49 Ceti are not particularly high, these objects seem to harbor the most extended disks within our sample. The double-peaked profiles of HD21997 were reproduced by a Keplerian disk model combined with the LIME radiative transfer code. Based on their similarities, 49 Ceti and HD21997 may be the first representatives of a so far undefined new class of relatively old > or approx.8 Myr), gaseous dust disks. From our results, neither primordia1 origin nor steady secondary production from icy planetesima1s can unequivocally explain the presence of CO gas in the disk ofHD21997.

Moor, A.↗

DOE OSTI2021

Fractional chiral hinge insulator

We propose and study a wave function describing an interacting three-dimensional fractional chiral hinge insulator (FCHI) constructed by Gutzwiller projection of two noninteracting second-order topological insulators with chiral hinge modes at half filling. We use large-scale variational Monte Carlo computations to characterize the model states via the entanglement entropy and charge-spin fluctuations. We show that the FCHI possesses fractional chiral hinge modes characterized by a central charge c = 1 and Luttinger parameter K = 1/2, like the edge modes of a Laughlin 1/2 state. The bulk and surface topology is characterized by the topological entanglement entropy (TEE) correction to the area law. While our computations indicate a vanishing bulk TEE, we show that the gapped surfaces host an unconventional two-dimensional topological phase. In a clear departure from the physics of a Laughlin 1/2 state, we find a TEE per surface compatible with (ln √2 )/2, half that of a Laughlin 1/2 state. This value cannot be obtained from topological quantum field theory for purely two-dimensional systems. For the sake of completeness, we also investigate the topological degeneracy.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2020

SFAI and Related Technologies

Researchers at Los Alamos have developed Swept-Frequency Acoustic Interferometry (SFAI) a technology that enables businesses to have greater control over their industrial processes, allowing for significantly improved efficiency by giving operators vital composition and flow rate information in real-time. This technology fills the information gap by providing this data non-invasively and at a fraction of the cost of traditional composition meters. SFAI uses engineered ultrasound and advanced signal processing to characterize multiphase flow (e.g., liquids, gasses, multi-phase mixtures) and other flows inside sealed containers and flow pipes. By being both low-cost and non-invasive, this technology is set to disrupt the current oil field monitoring state-of-the-art by providing individual well-level composition data, compared to the multi-well macroscopic information that is currently available. We are seeking a commercialization partner to license the technology or fund us through a Cooperative Research and Development Agreement (CRADA) to a further develop a usable product for commercial purposes.

03 NATURAL GAS↗

NASA NTRS1993

Broad-band linear polarization in cool stars. II - Amplitude and wavelength dependence for magnetic and scattering regions

We have developed a model to estimate the amplitude and wavelength dependence of broad-band linear polarization (BLP) from magnetic regions on cool stars. The model includes corrections both for line blends and for the partial cancellation of polarization in the vector sum over the stellar disk. Our results agree with recent calculations of BLP in the red, but show larger amplitudes and a different wavelength dependence in the blue. We find that the detailed wavelength dependence of the polarization is complex and varies with effective temperature and gravity due to changes in line blanketing. The BLP amplitudes depend strongly on field strength, blanketing, and magnetic region filling factor and geometry. We make rough estimates of the maximum BLP for stars of various spectral types and demonstrate a method for deriving a lower limit to the filling factor from the maximum observed BLP. This lower limit is related to the fractional area covered by the spatially asymmetric component of magnetic regions.

Saar, Steven H.↗

NASA NTRS2002

Left ventricular outflow tract mean systolic acceleration as a surrogate for the slope of the left ventricular end-systolic pressure-volume relationship

OBJECTIVE: The goal of this study was to analyze left ventricular outflow tract systolic acceleration (LVOT(Acc)) during alterations in left ventricular (LV) contractility and LV filling. BACKGROUND: Most indexes described to quantify LV systolic function, such as LV ejection fraction and cardiac output, are dependent on loading conditions. METHODS: In 18 sheep (4 normal, 6 with aortic regurgitation, and 8 with old myocardial infarction), blood flow velocities through the LVOT were recorded using conventional pulsed Doppler. The LVOT(Acc) was calculated as the aortic peak velocity divided by the time to peak flow; LVOT(Acc) was compared with LV maximal elastance (E(m)) acquired by conductance catheter under different loading conditions, including volume and pressure overload during an acute coronary occlusion (n = 10). In addition, a clinically validated lumped-parameter numerical model of the cardiovascular system was used to support our findings. RESULTS: Left ventricular E(m) and LVOT(Acc) decreased during ischemia (1.67 +/- 0.67 mm Hg.ml(-1) before vs. 0.93 +/- 0.41 mm Hg.ml(-1) during acute coronary occlusion [p < 0.05] and 7.9 +/- 3.1 m.s(-2) before vs. 4.4 +/- 1.0 m.s(-2) during coronary occlusion [p < 0.05], respectively). Left ventricular outflow tract systolic acceleration showed a strong linear correlation with LV E(m) (y = 3.84x + 1.87, r = 0.85, p < 0.001). Similar findings were obtained with the numerical modeling, which demonstrated a strong correlation between predicted and actual LV E(m) (predicted = 0.98 [actual] -0.01, r = 0.86). By analysis of variance, there was no statistically significant difference in LVOT(Acc) under different loading conditions. CONCLUSIONS: For a variety of hemodynamic conditions, LVOT(Acc) was linearly related to the LV contractility index LV E(m) and was independent of loading conditions. These findings were consistent with numerical modeling. Thus, this Doppler index may serve as a good noninvasive index of LV contractility.

Non-NASA Center↗

NASA NTRSDate not supplied

Effect of Injection Dynamics on Wave Propagation in a Linear Detonation Combustor

Injector response to self-excited and sustained detonation wave propagation in an optically-accessible nonpremixed natural gas-oxygen linear detonation combustor is investigated. 100 kHz measurements of planar laser induced fluorescence (PLIF) of trace quantities of acetone injected into the fuel supply and simultaneous OH∗ chemiluminescence measurements were used to correlate the effect on injection dynamics on detonation wave structure and propagation. Measurements over a range of equivalence ratios (0.61-1.48) revealed wave propagation through regions of high fuel stratification in the axial and transverse direction of reactant injection. Consequently, the propagation of the detonation wave along the channel is through a flow-field with significant variation in fuel mass fraction, reactivity, and sound speeds. At lean conditions, wave propagation frequency is generally lower (∼6 kHz) resulting in longer time between wave passages for mixing and pre-heat resulting in steeper detonation wave-fronts anchored near the injector exit plane. Conversely, at rich equivalence ratios the wave frequency is higher (∼10 kHz) resulting in shorter intra-cycle period for reactant fill and mixing resulting waves lifted from the injection plane that are more compact. Higher chemiluminescence intensity in the post-wave region with deflagrative combustion is observed in these cases. Phase averaged representation of the acetone-PLIF measurements indicate that the fraction of time between wave passages available for reactant fill, mixing and pre-heat is consistent across all equivalence ratios.

Propulsion↗

NASA NTRSDate not supplied

Effect of Injection Dynamics on Detonation Wave Propagation in a Linear Detonation Combustor

Propulsion↗

DOE OSTI2023

Composite Fermi Liquid at Zero Magnetic Field in Twisted MoTe 2

Here, the pursuit of exotic phases of matter outside of the extreme conditions of a quantizing magnetic field is a long-standing quest of solid state physics. Recent experiments have observed spontaneous valley polarization and fractional Chern insulators in zero magnetic field in twisted bilayers of MoTe 2 , at partial filling of the topological valence band (ν =-2/3 and -3/5). We study the topological valence band at half filling, using exact diagonalization and density matrix renormalization group calculations. We discover a composite Fermi liquid (CFL) phase even at zero magnetic field that covers a large portion of the phase diagram near twist angle ~3.6°. The CFL is a non-Fermi liquid phase with metallic behavior despite the absence of Landau quasiparticles. We discuss experimental implications including the competition between the CFL and a Fermi liquid, which can be tuned with a displacement field. The topological valence band has excellent quantum geometry over a wide range of twist angles and a small bandwidth that is, remarkably, reduced by interactions. These key properties stabilize the exotic zero field quantum Hall phases. Finally, we present an optical signature involving “extinguished” optical responses that detects Chern bands with ideal quantum geometry.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2025

Amphiphilic nanopores that condense undersaturated water vapor and exude water droplets

Condensation of water vapor in confined geometries, known as capillary condensation, is a fundamental phenomenon with far-reaching implications. While hydrophilic pores enable liquid formation from undersaturated vapor without energy input, the condensate typically remains confined, limiting practical utility. Here, we explore the use of amphiphilic nanoporous polymer-infiltrated nanoparticle films that condense and release liquid water under isothermal and undersaturated conditions. By tuning the polymer fraction and nanoparticle size, we optimize condensation and droplet formation. As vapor pressure increases, voids fill with condensate, which subsequently exudes onto the surface as microscopic droplets. This behavior, enabled by a balance of polymer hydrophobicity and capillarity, reveals how amphiphilic nanostructures can drive accessible water collection. Our findings provide design insights for materials supporting energy-efficient water harvesting and heat management without external input.

Science & Technology - Other Topics↗

NASA NTRS1972

Crater shadowing effects at low sun angles, part Q

A comparison of Apollo 15 lunar surface photographs taken at low sun-elevation angles with photographs of an experimentally cratered surface at low lighting angles is discussed. The comparison revealed marked similarities, the most significant being that the smallest craters in both sets of photographs are filled with shadows that form beadlike chains and clusters. It was also found that the fraction of area covered by shadows within the smaller craters is so large that 30 to 40 percent of the total field of view is covered by shadow. It is concluded that: the fraction of area covered by resolvable craters, which should be somewhat less than the fraction of area covered by shadow for photographs with very low sun elevation angles, may be calculated using the steady state crater frequency distribution for craters from 20 to 100 m in diameter and then adding the area covered by larger craters for which the crater frequency distribution has the form of the crater-production frequency distribution.

Moore, H. J.↗

DOE OSTI2024

Noncommutative gauge symmetry in the fractional quantum Hall effect

Abstract We show that a system of particles on the lowest Landau level can be coupled to a probe U(1) gauge field$$ \mathcal{A} $$ A μ in such a way that the theory is invariant under a noncommutative U(1) gauge symmetry. While the temporal component$$ \mathcal{A} $$ A 0 of the probe field is coupled to the projected density operator, the spatial components$$ \mathcal{A} $$ A i are best interpreted as quantum displacements, which distort the interaction potential between the particles. We develop a Seiberg-Witten-type map from the noncommutative U(1) gauge symmetry to a simpler version, which we call “baby noncommutative” gauge symmetry, where the Moyal brackets are replaced by the Poisson brackets. The latter symmetry group is isomorphic to the group of volume preserving diffeomorphisms. By using this map, we resolve the apparent contradiction between the noncommutative gauge symmetry, on the one hand, and the particle-hole symmetry of the half-filled Landau level and the presence of the mixed Chern-Simons terms in the effective Lagrangian of the fractional quantum Hall states, on the other hand. We outline the general procedure which can be used to write down effective field theories which respect the noncommutative U(1) symmetry.

Physics↗