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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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

HATS-47b, HATS-48Ab, HATS-49b, and HATS-72b: Four Warm Giant Planets Transiting K Dwarfs

We report the discovery of four transiting giant planets around K dwarfs. The planets HATS-47b, HATS-48Ab, HATS-49b, and HATS-72b have masses of 0.369{sub −0.021}{sup +0.031} M{sub J}, 0.243{sub −0.030}{sup +0.022} M{sub J}, 0.353{sub −0.027}{sup +0.038} M{sub J}, and 0.1254±0.0039 M{sub J}, respectively, and radii of 1.117±0.014 R{sub J}, 0.800±0.015 R{sub J}, 0.765±0.013 R{sub J}, and 0.7224±0.0032 R{sub J}, respectively. The planets orbit close to their host stars with orbital periods of 3.9228 days, 3.1317 days, 4.1480 days, and 7.3279 days, respectively. The hosts are main-sequence K dwarfs with masses of 0.674{sub −0.012}{sup +0.016} M{sub ⊙}, 0.7279 ±0.0066 M{sub ⊙}, 0.7133±0.0075 M{sub ⊙}, and 0.7311±0.0028, and with V-band magnitudes of V=14.829±0.010, 14.35±0.11, 14.998±0.040 and 12.469±0.010. The super-Neptune HATS-72b (a.k.a. WASP-191b and TOI 294.01) was independently identified as a transiting planet candidate by the HATSouth, WASP, and TESS surveys, and we present a combined analysis of all of the data gathered by each of these projects (and their follow-up programs). An exceptionally precise mass is measured for HATS-72b thanks to high-precision radial velocity (RV) measurements obtained with VLT/ESPRESSO, FEROS, HARPS, and Magellan/PFS. We also incorporate TESS observations of the warm Saturn–hosting systems HATS-47 (a.k.a. TOI 1073.01), HATS-48A, and HATS-49. HATS-47 was independently identified as a candidate by the TESS team, while the other two systems were not previously identified from the TESS data. The RV orbital variations are measured for these systems using Magellan/PFS. HATS-48A has a resolved [[Formula]] neighbor in Gaia DR2, which is a common-proper-motion binary star companion to HATS-48A with a mass of 0.22 M{sub ⊙} and a current projected physical separation of ∼1400 au.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

HATS-60b–HATS-69b: 10 Transiting Planets from HATSouth

We report the discovery of 10 transiting extrasolar planets by the HATSouth survey. The planets range in mass from the super-Neptune HATS-62b, with M{sub p}<0.179 M{sub J}, to the super-Jupiter HATS-66b, with M{sub p}=5.33 M{sub J}, and in size from the Saturn HATS-69b, with R{sub p}=0.94 R{sub J}, to the inflated Jupiter HATS-67b, with R{sub p}=1.69 R{sub J}. The planets have orbital periods between 1.6092 days (HATS-67b) and 7.8180 days (HATS-61b). The hosts are dwarf stars with masses ranging from 0.89 M{sub ⊙} (HATS-69) to 1.56 M{sub ⊙} (HATS-64) and have apparent magnitudes between V=12.276±0.020 mag (HATS-68) and V=14.095±0.030 mag (HATS-66). The super-Neptune HATS-62b is the least massive planet discovered to date with a radius larger than Jupiter. Based largely on the Gaia DR2 distances and broadband photometry, we identify three systems (HATS-62, HATS-64, and HATS-65) as having possible unresolved binary star companions. We discuss in detail our methods for incorporating the Gaia DR2 observations into our modeling of the system parameters and into our blend analysis procedures.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

HATS-37Ab and HATS-38b: Two Transiting Hot Neptunes in the Desert

We report the discovery of two transiting Neptunes by the HATSouth survey. The planet HATS-37Ab has a mass of 0.099±0.042 M{sub J} (31.5 ± 13.4 M {sub ⊕}) and a radius of 0.606±0.016 R{sub J}, and is on a P=4.3315 day orbit around a V=12.266±0.030 mag, 0.843{sub −0.012}{sup +0.017} M{sub ⊙} star with a radius of 0.877{sub −0.012}{sup +0.019} R{sub ⊙}. We also present evidence that the star HATS-37A has an unresolved stellar companion HATS-37B, with a photometrically estimated mass of 0.654±0.033 M{sub ⊙}. The planet HATS-38b has a mass of 0.074±0.011 M{sub J} (23.5 ± 3.5 M {sub ⊕}) and a radius of 0.614±0.017 R{sub J}, and is on a P=4.3750 day orbit around a V=12.411±0.030 mag, 0.890{sub −0.012}{sup +0.016} M{sub ⊙} star with a radius of 1.105±0.016 R{sub ⊙}. Both systems appear to be old, with isochrone-based ages of 11.46{sub −1.45}{sup +0.79} Gyr, and 11.89±0.60 Gyr, respectively. Both HATS-37Ab and HATS-38b lie in the Neptune desert and are thus examples of a population with a low occurrence rate. They are also among the lowest-mass planets found from ground-based wide-field surveys to date.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Effects of HAT-CN Layer Thickness on Molecular Orientation and Energy-Level Alignment with ZnPc

Efficient energy-level alignment is crucial for achieving high performance in organic electronic devices. Because the electronic structure of an organic semiconductor is significantly influenced by its molecular orientation, comprehensively understanding the molecular orientation and electronic structure of the organic layer is essential. In this study, we investigated the interface between a 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HAT-CN) hole injection layer and a zinc-phthalocyanine (ZnPc) p-type organic semiconductor. To determine the energy-level alignment and molecular orientation, we conducted in situ ultraviolet and X-ray photoelectron spectroscopies, as well as angle-resolved X-ray absorption spectroscopy. We found that the HAT-CN molecules were oriented relatively face-on (40°) in the thin (5 nm) layer, whereas they were oriented relatively edge-on (62°) in the thick (100 nm) layer. By contrast, ZnPc orientation was not significantly altered by the underlying HAT-CN orientation. The highest occupied molecular orbital (HOMO) level of ZnPc was closer to the Fermi level on the 100 nm thick HAT-CN layer than on the 5 nm thick HAT-CN layer because of the higher work function. Consequently, a considerably low energy gap between the lowest unoccupied molecular orbital level of HAT-CN and the HOMO level of ZnPc was formed in the 100 nm thick HAT-CN case. This may improve the hole injection ability of the anode system, which can be utilized in various electronic devices.

42 ENGINEERING↗
DOE OSTI2019

Make the right measurement: Discovery of an allosteric inhibition site for p300-HAT

Histone acetyltransferases (HATs) and histone deacetylases (HDACs) catalyze the dynamic and reversible acetylation of proteins, an epigenetic regulatory mechanism associated with multiple cancers. Indeed, HDAC inhibitors are already approved in the clinic. The HAT paralogs p300 and CREB-binding protein (CBP) have been implicated in human pathological conditions including several hematological malignancies and androgen receptor-positive prostate cancer. Others have reported CoA-competitive inhibitors of p300 and CBP with cell-based activity. Here, we describe 2 compounds, CPI-076 and CPI-090, discovered through p300-HAT high throughput screening screening, which inhibit p300-HAT via binding at an allosteric site. We present the high resolution (1.7 and 2.3 Å) co-crystal structures of these molecules bound to a previously undescribed allosteric site of p300-HAT. Derivatization yielded actionable structure-activity relationships, but the full-length enzymatic assay demonstrated that this allosteric HAT inhibitor series was artifactual, inhibiting only the HAT domain of p300 with no effect on the full-length enzyme.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1989

Flexural fatigue life prediction of closed hat-section using materially nonlinear axial fatigue characteristics

Straight or curved hat-section members are often used as structural stiffeners in aircraft. For instance, they are employed as stiffeners for the dorsal skin as well as in the aerial refueling adjacent area structure in F-106 aircraft. The flanges of the hat-section are connected to the aircraft skin. Thus, the portion of the skin closing the hat-section interacts with the section itself when resisting the stresses due to service loads. The flexural fatigue life of such a closed section is estimated using materially nonlinear axial fatigue characteristics. It should be recognized that when a structural shape is subjected to bending, the fatigue life at the neutral axis is infinity since the normal stresses are zero at that location. Conversely, the fatigue life at the extreme fibers where the normal bending stresses are maximum can be expected to be finite. Thus, different fatigue life estimates can be visualized at various distances from the neural axis. The problem becomes compounded further when significant portions away from the neutral axis are stressed into plastic range. A theoretical analysis of the closed hat-section subjected to flexural cyclic loading is first conducted. The axial fatigue characteristics together with the related axial fatigue life formula and its inverted form given by Manson and Muralidharan are adopted for an aluminum alloy used in aircraft construction. A closed-form expression for predicting the flexural fatigue life is then derived for the closed hat-section including materially nonlinear action. A computer program is written to conduct a study of the variables such as the thicknesses of the hat-section and the skin, and the type of alloy used. The study has provided a fundamental understanding of the flexural fatigue life characteristics of a practical structural component used in aircraft when materially nonlinear action is present.

Razzaq, Zia↗
NASA NTRS1996

Thermal and Mechanical Buckling Analysis of Hypersonic Aircraft Hat-Stiffened Panels With Varying Face Sheet Geometry and Fiber Orientation

Mechanical and thermal buckling behavior of monolithic and metal-matrix composite hat-stiffened panels were investigated. The panels have three types of face-sheet geometry: Flat face sheet, microdented face sheet, and microbulged face sheet. The metal-matrix composite panels have three types of face-sheet layups, each of which is combined with various types of hat composite layups. Finite-element method was used in the eigenvalue extractions for both mechanical and thermal buckling. The thermal buckling analysis required both eigenvalue and material property iterations. Graphical methods of the dual iterations are shown. The mechanical and thermal buckling strengths of the hat-stiffened panels with different face-sheet geometry are compared. It was found that by just microdenting or microbulging of the face sheet, the axial, shear, and thermal buckling strengths of both types of hat-stiffened panels could be enhanced considerably. This effect is more conspicuous for the monolithic panels. For the metal-matrix composite panels, the effect of fiber orientations on the panel buckling strengths was investigated in great detail, and various composite layup combinations offering, high panel buckling strengths are presented. The axial buckling strength of the metal-matrix panel was sensitive to the change of hat fiber orientation. However, the lateral, shear, and thermal buckling strengths were insensitive to the change of hat fiber orientation.

Ko, William L.↗
DOE OSTI2022

Universality (beyond leading log) of soft radiative corrections to $\hat q$ in $p_\perp$ broadening and energy loss

It has been known for many years that soft radiation can give potentially large double-logarithm corrections to $p_\perp$ broadening of a high-energy particle traveling through QCD matter, but that this soft radiation correction can be absorbed into an effective value $\hat q_{eff}$ for the medium $p_\perp$-broadening parameter $\hat q$. Here ``soft'' means high energy compared to medium scales but soft compared to the original high-energy particle traveling through the medium. A similar situation arises in the case of soft corrections to hard splitting of a high-energy particle, such as hard g → gg, where double logarithms can also be absorbed using the same effective $\hat q_{eff}$. In this paper, I study whether the same holds true for potentially large, subleading, {\it single}-logarthim corrections. The correspondence is more indirect for single logarithms, but I show (in the large-$N_c$ limit) that single logarithms from soft radiation in the case of $p_\perp$ broadening also determine the single logarithms from soft radiative corrections to hard g → gg splitting. Along the way, there is an interesting variation of the original BDMPS-Z calculation of splitting rates in the q(hat) approximation. I also discuss how, for soft-radiative corrections to hard splitting processes, there are two different types of ''$\hat q_{eff}$'' that come into play, which differ by ''$i\pi$'' terms that multiply single logarithms.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS2011

Application of Human-Autonomy Teaming (HAT) Patterns to Reduce Crew Operations (RCO)

Unmanned aerial systems, advanced cockpits, and air traffic management are all seeing dramatic increases in automation. However, while automation may take on some tasks previously performed by humans, humans will still be required to remain in the system for the foreseeable future. The collaboration between humans and these increasingly autonomous systems will begin to resemble cooperation between teammates, rather than simple task allocation. It is critical to understand this human-autonomy teaming (HAT) to optimize these systems in the future. One methodology to understand HAT is by identifying recurring patterns of HAT that have similar characteristics and solutions. This paper applies a methodology for identifying HAT patterns to an advanced cockpit project.

design patterns↗
NASA NTRS2016

Application of Human-Autonomy Teaming (HAT) Patterns to Reduce Crew Operations (RCO)

Unmanned aerial systems, robotics, advanced cockpits, and air traffic management are all examples of domains that are seeing dramatic increases in automation. While automation may take on some tasks previously performed by humans, humans will still be required, for the foreseeable future, to remain in the system. The collaboration with humans and these increasingly autonomous systems will begin to resemble cooperation between teammates, rather than simple task allocation. It is critical to understand this human-autonomy teaming (HAT) to optimize these systems in the future. One methodology to understand HAT is by identifying recurring patterns of HAT that have similar characteristics and solutions. This paper applies a methodology for identifying HAT patterns to an advanced cockpit project.

design patterns↗
NASA NTRS2016

Application of Human-Autonomy Teaming (HAT) Patterns to Reduced Crew Operations (RCO)

As part of the Air Force - NASA Bi-Annual Research Council Meeting, slides will be presented on recent Reduced Crew Operations (RCO) work. Unmanned aerial systems, robotics, advanced cockpits, and air traffic management are all examples of domains that are seeing dramatic increases in automation. While automation may take on some tasks previously performed by humans, humans will still be required, for the foreseeable future, to remain in the system. The collaboration with humans and these increasingly autonomous systems will begin to resemble cooperation between teammates, rather than simple task allocation. It is critical to understand this human-autonomy teaming (HAT) to optimize these systems in the future. One methodology to understand HAT is by identifying recurring patterns of HAT that have similar characteristics and solutions. A methodology for identifying HAT patterns to an advanced cockpit project is discussed.

Human-Autonomy Teaming (HAT)↗
DOE OSTI2020

Energy and scale dependence of $\hat{q}$ and the “JET puzzle”

Here, we present an attempt to probe the underlying structure of the quark-gluon plasma (QGP) at high resolution, based on the extracted jet transport coefficient $\hat{q}$. We argue that the exchanged momentum $\textit{k}$ between the hard parton and the medium varies over a range of scales, and for $\textit{k}$ ≥ 1 GeV, $\hat{q}$ can be expressed in terms of a parton distribution function (PDF). Because the mass of a QGP constituent is unknown, we define a scaling variable $x_N$ to represent the ratio of the parton momentum to the momentum of a self-contained section of the plasma which has a mass of 1 GeV. This scaling variable is used to parametrize the QGP-PDF. Calculations based on this reconstructed $\hat{q}$ are compared to data sensitive to the hardcore of jets, i.e., the single hadron suppression in terms of the nuclear modification factor $R_{ A A}$ and the azimuthal anisotropy parameter $v_2$ as a function of transverse momentum $p_T$, centrality, and energy of the collision. It is demonstrated that the scale evolution of the QGP-PDF is responsible for the reduction in the normalization of $\hat{q}$ between fits to the Relativistic Heavy-Ion Collider and the Large Hadron Collider data; a puzzle, first discovered by the JET Collaboration.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Determining the jet transport coefficient $\hat{q}$ from inclusive hadron suppression measurements using Bayesian parameter estimation

We report a new determination of $\hat{q}$, the jet transport coefficient of the quark-gluon plasma. We use the JETSCAPE framework, which incorporates a novel multistage theoretical approach to in-medium jet evolution and Bayesian inference for parameter extraction. The calculations, based on the Matter and Lbt jet quenching models, are compared to experimental measurements of inclusive hadron suppression in Au + Au collisions at the BNL Relativistic Heavy Ion Collider (RHIC) and Pb + Pb collisions at the CERN Large Hadron Collider (LHC). The correlation of experimental systematic uncertainties is accounted for in the parameter extraction. The functional dependence of $\hat{q}$ on jet energy or virtuality and medium temperature is based on a perturbative picture of in-medium scattering, with components reflecting the different regimes of applicability of Matter and Lbt. In the multistage approach, the switch between Matter and Lbt is governed by a virtuality scale Q 0 . Comparison of the posterior model predictions to the RHIC and LHC hadron suppression data shows reasonable agreement, with moderate tension in limited regions of phase space. The distribution of $\hat{q}/T^3$ extracted from the posterior distributions exhibits weak dependence on jet momentum and medium temperature T, with 90% credible region (CR) depending on the specific choice of model configuration. The choice of Matter + Lbt, with switching at virtuality Q 0 , has 90% CR of $2<\hat{q}/T^3<4$ for p T jet > 40 GeV=c. The value of Q 0 , determined here for the first time, is in the range 2.0-2.7 GeV.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1990

RSRM top hat cover simulator lightning test, volume 1

The test sequence was to measure electric and magnetic fields induced inside a redesigned solid rocket motor case when a simulated lightning discharge strikes an exposed top hat cover simulator. The test sequence was conducted between 21 June and 17 July 1990. Thirty-six high rate-of-rise Marx generator discharges and eight high current bank discharges were injected onto three different test article configurations. Attach points included three locations on the top hat cover simulator and two locations on the mounting bolts. Top hat cover simulator and mounting bolt damage and grain cover damage was observed. Overall electric field levels were well below 30 kilowatts/meter. Electric field levels ranged from 184.7 to 345.9 volts/meter and magnetic field levels were calculated from 6.921 to 39.73 amperes/meter. It is recommended that the redesigned solid rocket motor top hat cover be used in Configuration 1 or Configuration 2 as an interim lightning protection device until a lightweight cover can be designed.

Source record↗
NASA NTRS1996

Design and evaluation of a bolted joint for a discrete carbon-epoxy rod-reinforced hat section

The use of prefabricated pultruded carbon-epoxy rods has reduced the manufacturing complexity and costs of stiffened composite panels while increasing the damage tolerance of the panels. However, repairability of these highly efficient discrete stiffeners has been a concern. Design, analysis, and test results are presented in this paper for a bolted-joint repair for the pultruded rod concept that is capable of efficiently transferring axial loads in a hat-section stiffener on the upper skin segment of a heavily loaded aircraft wing component. A tension and a compression joint design were evaluated. The tension joint design achieved approximately 1.0% strain in the carbon-epoxy rod-reinforced hat-section and failed in a metal fitting at 166% of the design ultimate load. The compression joint design failed in the carbon-epoxy rod-reinforced hat-section test specimen area at approximately 0.7% strain and at 110% of the design ultimate load. This strain level of 0.7% in compression is similar to the failure strain observed in previously reported carbon-epoxy rod-reinforced hat-section column tests.

Rousseau, Carl Q.↗
NASA NTRS1996

Test and Analysis of Composite Hat Stringer Pull-off Test Specimens

Hat stringer pull-off tests were performed to evaluate the delamination failure mechanisms in the flange region for a rod-reinforced hat stringer section. A special test fixture was used to pull the hat off the stringer while reacting the pull-off load through roller supports at both stringer flanges. Microscopic examinations of the failed specimens revealed that failure occurred at the ply termination in the flange area where the flange of the stiffener is built up by adding 45/-45 tape plies on the top surface. Test results indicated that the as-manufactured microstructure in the flange region has a strong influence on the delamination initiation and the associated pull-off loads. Finite element models were created for each specimen with a detailed mesh based on micrographs of the critical location. A fracture mechanics approach and a mixed mode delamination criterion were used to predict the onset of delamination and the pull-off load. By modeling the critical local details of each specimen from micrographs, the model was able to accurately predict the hat stringer pull-off loads and replicate the variability in the test results.

Li, Jian↗
NASA NTRS1996

Design and Evaluation of a Bolted Joint for a Discrete Carbon-Epoxy Rod-Reinforced Hat Section

The use of pre-fabricated pultruded carbon-epoxy rods has reduced the manufacturing complexity and costs of stiffened composite panels while increasing the damage tolerance of the panels. However, repairability of these highly efficient discrete stiffeners has been a concern. Design, analysis, and test results are presented in this paper for a bolted-joint repair for the pultruded rod concept that is capable of efficiently transferring axial loads in a hat-section stiffener on the upper skin segment of a heavily loaded aircraft wing component. A tension and a compression joint design were evaluated. The tension joint design achieved approximately 1.0 percent strain in the carbon-epoxy rod-reinforced hat-section and failed in a metal fitting at 166 percent of the design ultimate load. The compression joint design failed in the carbon-epoxy rod-reinforced hat-section test specimen area at approximately 0.7 percent strain and at 110 percent of the design ultimate load. This strain level of 0.7 percent in compression is similar to the failure strain observed in previously reported carbon-epoxy rod-reinforced hat-section column tests.

Baker, Donald J.↗