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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 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Hierarchical tapered bar elements undergoing axial deformation

A method is described to model the dynamics of tapered axial bars of various cross sections based on the well-known Craig/Bampton component mode synthesis technique. This element is formed in terms of the static constraint modes and interface restrained normal modes. This is in contrast with the finite elements as implemented in NASTRAN where the interface restrained normal modes are neglected. These normal modes are in terms of Bessel functions. Restoration of a few of these modes leads to higher accuracy with fewer generalized coordinates. The proposed models are hierarchical so that all lower order element matrices are embedded in higher order element matrices. The advantages of this formulation compared to standard NASTRAN truss element formulation are demonstrated through simple numerical examples.

Ganesan, N.↗
NASA NTRS1935

The Influence of Tip Shape on the Wing Load Distribution as Determined by Flight Tests

Pressure measurements were made in flight on the right upper wing of an M-3 airplane. The effects of tip plan form, washout, and transverse camber were investigated with eight tip forms in unyawed conditions through the range of positive lift coefficients from zero lift to the stall. The conclusion is that the tip plan form does not influence the span distribution of the coefficients of normal force and moment. It is shown inferentially that temperature, humidity, and the aging of the wood and fabric wing structure used on the M-3 airplane have an appreciable influence on the load distribution.

Rhode, Richard V↗
NASA NTRS1993

Cryogenic spray vaporization in high-velocity helium, argon and nitrogen gasflows

Effects of gas properties on cryogenic liquid-jet atomization in high-velocity helium, nitrogen, and argon gas flows were investigated. Volume median diameter, D(sub v.5e), data were obtained with a scattered-light scanning instrument. By calculating the change in spray drop size, -Delta D(sub v.5)(exp 2), due to droplet vaporization, it was possible to calculate D(sub v.5C). D(sub v.5C) is the unvaporized characteristic drop size formed at the fuel-nozzle orifice. This drop size was normalized with respect to liquid-jet diameter, D(sub O). It was then correlated with several dimensionless groups to give an expression for the volume median diameter of cryogenic LN2 sprays. This expression correlates drop size D(sub v.5c) with aerodynamic and liquid-surface forces so that it can be readily determined in the design of multiphase-flow propellant injectors for rocket combustors.

Ingebo, Robert D.↗
NASA NTRS1996

SNS Devices With Pinhole-Defined Active Regions

Superconductor/normal conductor/superconductor (SNS) microbridge devices with pinhole-defined active regions undergoing development. Device includes thin, electrically insulating layer deposited epitaxially, with controlled formation of pinholes, on one of two superconducting layers. Normally conducting metal deposited epitaxially in pinholes and on insulating layer, forming electrical contact between two superconducting layers. Junction resistances and maximum junction voltages expected to be increased.

Hunt, Brian D.↗
NASA NTRS1995

Integrin-extracellular matrix interactions in connective tissue remodeling and osteoblast differentiation

The differentiaton of bone cells is a complex multistep process. Bone is somewhat unusual in that it is very actively and continually remodeled in the adult and that maintenance of its mass in the mature organism is exquisitely sensitive to mechanical as well as chemical signals. Bone is also unique because it consists of a very large amount of extracellular matrix (ECM) that is mineralized. The integrin family of ECM receptors has been shown to play an important role in tissue morphogenesis in several systems. Our studies on the regulation of matrix remodeling enzymes by integrins in rabbit synovial fibroblasts show that two b1 integrin fibronectin (FN) receptor complexes (alpha 5 beta 1 and alpha 4 beta 1) cooperate in detecting subtle changes in the composition of the ECM. As a result of signal transduction by these integrins, the levels of mRNA and protein for several members of the metalloproteinase family are regulated in these cells. We have also used antibody and RGD peptide perturbation studies to determine the significance of cell/ECM interactions to normal osteogenesis. We found that interactions between the cell binding domain of FN and integrins are required for both normal morphogenesis and gene expression in cultured osteoblasts that differentiate to form bone-like tissue in culture. These data lead us to propose that beta 1 integrins play an important role in osteoblast differentiation as well as in bone remodeling.

NASA Discipline Number 26-10↗
NASA NTRS2006

Optical and Mechanical Properties of Glass Blown In Vacuo

Theoretically, the strength of glass processed in vacuum should be higher due to outgassing of contaminants normally present in the glass, such as bulk water in the form of OH bonds that tends to weaken the glass structure. In this research, small discs of a few types of glass have been subjected to various temperatures for extended periods of time in vacuum. Their strength was then tested using a standard flexure technique, facilitated by a custom-designed test fixture, and the results were compared to glass tested in air using the same fixture. The purpose of the glass blowing investigation was to prove the basic feasibility of a high-level concept for in-space manufacture of optical elements. The central requirement was that the glass bubble had to be blown into a support structure such that the bubble could be handled by manipulation of the structure. The blown bubble attached itself to a mullite ring geometrically and mechanically, as a demonstration in the initial experiments described here, by expanding through and around it. The vacuum system used was custom made, as were most of the components of the system, such as the heating element, the glass and ring support structure, and the gas inlet system that provided the pressure needed to blow the glass.

Manning, andrew↗
NASA NTRS1988

Enhancement of superplastic formability in a high strength aluminum alloy

A 7475 aluminum alloy was developed for superplastic forming (SPF). By lowering the Fe and Si contents in this alloy significantly below their normal levels and optimizing the thermomechanical processing to produce sheet, over 2000 percent thickness strain to failure was obtained. The microstructure, elevated-temperature uniaxial and biaxial tension, and cavitation behavior of the alloy were determined. In addition, a constitutive model was used to form a generic structural shape from which mechanical test specimens were removed and post-SPF characteristics were evaluated. The constitutive model included both material strain hardening and strain rate hardening effects, and was verified by accurately predicting forming cycles which resulted in successful component forming. Stress-life fatigue, stress rupture, and room and elevated temperature tensile tests were conducted on the formed material.

Agrawal, S. P.↗
NASA NTRS2003

Gravitational Influences on Flame Propagation Through Non-Uniform, Premixed Gas Systems

Flame propagation through non-uniformly premixed (or layered) gases has importance both in useful combustion systems and in unintentional fires. As summarized recently and in previous Microgravity Workshop papers, non-uniform premixed gas combustion receives scant attention compared to the more usual limiting cases of diffusion or uniformly premixed flames, especially regarding the role gravity plays. This paper summarizes our recent findings on gravitational effects on layered combustion along a floor, in which the fuel concentration gradient exists normal to the direction of flame spread. In an effort to understand the mechanism by which the flames spread faster in microgravity (and much faster, in laboratory coordinates, than the laminar burning velocity for uniform mixtures), we have begun making pressure measurements across the spreading flame front that are described here. Earlier researchers, testing in 1g, claimed that hydrostatic pressure differences could account for the rapid spread rates. Additionally, we present the development of a new apparatus to study flame spread in free (i.e., far from walls), non-homogeneous fuel layers formed in a flow tunnel behind an airfoil that has been tested in normal gravity.

Miller, Fletcher J.↗
NASA NTRS1996

Structural relations between collagen and mineral in bone as determined by high voltage electron microscopic tomography

Aspects of the ultrastructural interaction between collagen and mineral crystals in embryonic chick bone have been examined by the novel technique of high voltage electron microscopic tomography to obtain three-dimensional information concerning extracellular calcification in this tissue. Newly mineralizing osteoid along periosteal surfaces of mid-diaphyseal regions from normal chick tibiae was embedded, cut into 0.25 microns thick sections, and documented at 1.0 MV in the Albany AEI-EM7 high voltage electron microscope. The areas of the tissue studied contained electron dense mineral crystals associated with collagen fibrils, some marked by crystals disposed along their cylindrically shaped lengths. Tomographic reconstructions of one site with two mineralizing fibrils were computed from a 5 degrees tilt series of micrographs over a +/- 60 degrees range. Reconstructions showed that the mineral crystals were platelets of irregular shape. Their sizes were variable, measured here up to 80 x 30 x 8 nm in length, width, and thickness, respectively. The longest crystal dimension, corresponding to the c-axis crystallographically, was generally parallel to the collagen fibril long axis. Individual crystals were oriented parallel to one another in each fibril examined. They were also parallel in the neighboring but apparently spatially separate fibrils. Crystals were periodically (approximately 67 nm repeat distance) arranged along the fibrils and their location appeared to correspond to collagen hole and overlap zones defined by geometrical imaging techniques. The crystals appeared to be continuously distributed along a fibril, their size and number increasing in a tapered fashion from a relatively narrow tip containing smaller and infrequent crystals to wider regions having more densely packed and larger crystals. Defined for the first time by direct visual 3D imaging, these data describe the size, shape, location, orientation, and development of early crystals in normal bone collagen. The results suggest that platelet-shaped crystals are arranged in channels or grooves which are formed by collagen hole zones in register and that crystal sizes may exceed the dimensions of hole zones. Such data agree with those from mineral-matrix interaction in normally calcifying avian tendon obtained by similar high voltage tomographic means, but in addition they indicate a possible gradual and continuous deposition of crystals in collagen of bone unlike tendon and imply that individual collagen fibrils in local regions of osteoid are organized such that they all may be aligned in a coherent manner.

NASA Discipline Number 40-40↗
NASA NTRS1984

Twinning of amphibian embryos by centrifugation

In the frog Xenopus laevis, the dorsal structures of the embryonic body axis normally derive from the side of the egg opposite the side of sperm entry. However, if the uncleaved egg is inclined at lg or centrifuged in an inclined position, this topographic relationship is overridden: the egg makes its dorsal axial structures according to its orientation in the gravitational/centrifugal field, irrespective of the position of sperm entry. Certain conditions of centrifugation cause eggs to develop into conjoined twins with two sets of axial structures. A detailed analysis of twinning provided some insight into experimental axis orientation. First, as with single-axis embryos, both axes in twins are oriented according to the direction of centrifugation. One axis forms at the centripetal side of the egg and the other forms at the centrifugal side, even when the side of sperm entry is normal to the centrifugal force vector. Second, if eggs are centrifuged to give twins, but are inclined at lg to prevent post-centrifugation endoplasmic redistributions, only single-axis embryos develop. Thus, a second redistribution is required for high-frequency secondary axis formation. This can be accomplished by lg (as in the single centrifugations) or by a second centrifugation directed along the egg's animal-vegetal axis.

Black, S. D.↗
NASA NTRS1987

IUE observations of Mg2 emission form Miras

A total of 61 well exposed low dispersion LWP observations were obtained from the brightest normal M-type Mira variables around their pulsation cycles. By observing Mg II throughout the cycle, the intent is to determine the shock luminosity and duration, and the density in the upper atmospheres of Miras. The data also provide a mechanism for probing the radiative cooling in postshock regions of the atmosphere as a function of time. A summary of data acquired for IUE programs SRHLW and MGIEB is presented.

Brugel, Edward W.↗
DOE OSTI2020

Efficient Organic Solar Cell with 16.88% Efficiency Enabled by Refined Acceptor Crystallization and Morphology with Improved Charge Transfer and Transport Properties

Abstract Single‐layered organic solar cells (OSCs) using nonfullerene acceptors have reached 16% efficiency. Such a breakthrough has inspired new sparks for the development of the next generation of OSC materials. In addition to the optimization of electronic structure, it is important to investigate the essential solid‐state structure that guides the high efficiency of bulk heterojunction blends, which provides insight in understanding how to pair an efficient donor–acceptor mixture and refine film morphology. In this study, a thorough analysis is executed to reveal morphology details, and the results demonstrate that Y6 can form a unique 2D packing with a polymer‐like conjugated backbone oriented normal to the substrate, controlled by the processing solvent and thermal annealing conditions. Such morphology provides improved carrier transport and ultrafast hole and electron transfer, leading to improved device performance, and the best optimized device shows a power conversion efficiency of 16.88% (16.4% certified). This work reveals the importance of film morphology and the mechanism by which it affects device performance. A full set of analytical methods and processing conditions are executed to achieve high efficiency solar cells from materials design to device optimization, which will be useful in future OSC technology development.

Zhu, Lei↗
DOE OSTI2023

Higher-order SPOP assembly reveals a basis for cancer mutant dysregulation

The speckle-type POZ protein (SPOP) functions in the Cullin3-RING ubiquitin ligase (CRL3) as a receptor for the recognition of substrates involved in cell growth, survival, and signaling. SPOP mutations have been attributed to the development of many types of cancers, including prostate and endometrial cancers. Prostate cancer mutations localize in the substrate-binding site of the substrate recognition (MATH) domain and reduce or prevent binding. However, most endometrial cancer mutations are dispersed in seemingly inconspicuous solvent-exposed regions of SPOP, offering no clear basis for their cancer-causing and peculiar gain-of-function properties. Herein, we present the first structure of SPOP in its oligomeric form, uncovering several new interfaces important for SPOP self-assembly and normal function. Given that many previously unaccounted-for cancer mutations are localized in these newly identified interfaces, we uncover molecular mechanisms underlying dysregulation of SPOP function, with effects ranging from gross structural changes to enhanced self-association, and heightened stability and activity.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Evidence of a liquid–liquid transition in a glass-forming ionic liquid

A liquid–liquid transition (LLT) is a transformation from one liquid to another through a first-order transition. The LLT is fundamental to the understanding of the liquid state and has been reported in a few materials such as silicon, phosphorus, triphenyl phosphite, and water. Furthermore, it has been suggested that the unique properties of materials such as water, which is critical for life on the planet, are linked to the existence of the LLT. However, the experimental evidence for the existence of an LLT in many molecular liquids remains controversial, due to the prevalence and high propensity of the materials to crystallize. In this work, we show evidence of an LLT in a glass-forming trihexyltetradecylphosphonium borohydride ionic liquid that shows no tendency to crystallize under normal laboratory conditions. We observe a step-like increase in the static dielectric permittivity at the transition. Furthermore, the sizes of nonpolar local domains and ion-coordination numbers deduced from wide-angle X-ray scattering also change abruptly at the LLT. We independently corroborate these changes in local organization using Raman spectroscopy. The experimental access to the evolution of local order and structural dynamics across a liquid–liquid transition opens up unprecedented possibilities to understand the nature of the liquid state.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Modelling and simulation of brinicle formation

Below the Arctic sea ice, under the right conditions, a flux of icy brine flows down into the sea. The icy brine has a much lower fusion point and is denser than normal seawater. As a result, it sinks while freezing everything around it, forming an ice channel called a brinicle (also known as ice stalactite). In this paper, we develop a mathematical model for this phenomenon, assuming cylindrical symmetry. The fluid is considered to be viscous and quasi-stationary. The heat and salt transport are weakly coupled to the fluid motion and are modelled with the corresponding conservation equations, accounting for diffusive and convective effects. Finite-element discretization is employed to solve the coupled system of partial differential equations. We find that the model can capture the general behaviour of the physical system and generate brinicle-like structures while also recovering dendrite composition, which is a physically expected feature aligned with previous experimental results. This represents, to our knowledge, the first complete model proposed that captures the global structure of the physical phenomenon even though it has some discrepancies, such as brine accumulation.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2022

Interplay of itinerant electrons and Ising moments in a hybrid honeycomb quantum magnet TmNi 3 Al 9

The interplay between itinerant electrons and local magnetic moments in quantum materials brings about rich and fascinating phenomena and stimulates various developments in the theoretical framework. In this work, thermodynamic, electric transport, and neutron diffraction measurements were performed on a newly synthesized honeycomb lattice magnet TmNi 3 Al 9 . Based on the experimental data, a magnetic-field–temperature phase diagram was constructed, exhibiting three essentially different magnetic regions. Below T N =2.97±0.02KTm 3+ , moments order antiferromagnetically in zero field. We found that the Tm 3+ ions form a pseudodoublet ground state with the Ising-like moments lying normal to the two-dimensional honeycomb layers. Application of a magnetic field along the easy axis gradually suppresses the antiferromagnetic order in favor of an induced ferromagnetic state above the critical field B c =0.92±0.05T. In the vicinity of B c , a strong enhancement of the quantum spin fluctuations was observed. The quantum Ising nature of the local moments and the coupling to itinerant electrons are discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Using DAPPER to extract the photon strength function of 58 Fe using the inverse Oslo and shape methods

The photon strength function of 58 Fe has been extracted using both the Oslo and Shape methods from particle–γ coincidence data measured using the Detector Array for Photons, Protons, and Exotic Residues, which probes nuclei utilizing (d,p) reactions in inverse kinematics. Four particle–γ coincidence matrices, each constructed with different treatments of the γ–ray energies, are explored in order to observe the impact on the resulting nuclear level density and photon strength. The final photon strength function reported is found to agree well with previous Oslo measurements of other iron isotopes. Systematic uncertainties are included, using different model parameters and their reported errors to perform the Oslo method normalization. The model-independent Shape method is explored and the functional form of the photon strength function obtained is in agreement with the Oslo method results. A low-energy enhancement is not reported for 58 Fe in this work given possible subtraction issues originating from strongly populated states.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Operational Technology Behavioral Analytics (OTBA) (Final Technical Report DE-FE0031640)

This final report provides a summary of the methodology, findings, lessons learned, and insights from an investigation into the feasibility of the Operational Technology Behavioral Analytics (OTBA) cybersecurity approach. The concept was evaluated with data from the National Carbon Capture Center (NCCC) – a U.S. Department of Energy (DOE) funded facility that is managed and operated by Southern Company Services, Inc. at Alabama Power Company’s E. C. Gaston generating power plant in Wilsonville, Alabama. Appropriate data sources for the post-combustion carbon capture system were identified. Infrastructure was deployed to monitor, capture and archive data for the system. Critical parameters for each subsystem were identified and analyzed. Machine-learning algorithms were used to establish and characterize normal operations and subsequently identify anomalies. This effort yielded valuable insights and formed the basis of a data-centric strategy for detecting cyber-attacks along with a coordinated response philosophy. A significant takeaway is that the OTBA cybersecurity approach is quite portable; it can be applied to other critical infrastructure beyond fossil power generation.

20 FOSSIL-FUELED POWER PLANTS↗