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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 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Collapse for the higher-order nonlinear Schrödinger equation

We examine conditions for finite-time collapse of the solutions of the higher-order nonlinear Schr odinger (NLS) equation incorporating third-order dispersion, self-steepening, linear and nonlinear gain and loss, and Raman scattering; this is a system that appears in many physical contexts as a more realistic generalization of the integrable NLS. By using energy arguments, it is found that the collapse dynamics is chiefly controlled by the linear/nonlinear gain/loss strengths. We identify a critical value of the linear gain, separating the possible decay of solutions to the trivial zero-state, from collapse. The numerical simulations, performed for a wide class of initial data, are found to be in very good agreement with the analytical results, and reveal long-time stability properties of localized solutions. The role of the higher-order effects to the transient dynamics is also revealed in these simulations.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Scaling of heat transport near onset in rapidly rotating convection

Here, we consider the scaling of heat transport in the geostrophic regime of rotating Rayleigh–Bénard convection near onset for small Ekman number Ek from the perspective of weakly nonlinear theory. We show that available heat transport data from numerical simulation [1] for Ek < 10 -5 for Pr = 1 are consistent with weakly nonlinear theory for ϵ = Ra / Ra c - 1 < 1. In particular, we show that the numerical data are consistent with Nu - 1 = aϵ + bϵ 2 with a ≈ 2 and b ≈ 3 with weak dependence of the coefficients on Ek. The coefficient a is consistent with calculations of weakly nonlinear theory and with experimental data at much higher Ek. The positive sign of b is also suggested by those experimental data. The magnitude and trend of the numerical data for larger Ra are consistent with experimental data with similar Pr ~ 1. The steep scaling of Nu ~ (Ra / Ra c ) 3 noted elsewhere for Ra / Ra c < 2 is shown to be an artifact of being close to onset where the effective power-law slope depends sensitively on the magnitude of the coefficients a and b. Similar arguments apply to Pr = 7 numerical data although the weakly nonlinear expansion appears valid for a smaller range of ϵ than in the Pr = 1 case.

58 GEOSCIENCES↗
DOE OSTI2011

Isospin Splittings of Doubly Heavy Baryons

The SELEX Collaboration has reported a very large isospin splitting of doubly charmed baryons. We show that this effect would imply that the doubly charmed baryons are very compact. One intriguing possibility is that such baryons have a linear geometry Q-q-Q where the light quark q oscillates between the two heavy quarks Q, analogous to a linear molecule such as carbon dioxide. However, using conventional arguments, the size of a heavy-light hadron is expected to be around 0.5 fm, much larger than the size needed to explain the observed large isospin splitting. Assuming the distance between two heavy quarks is much smaller than that between the light quark and a heavy one, the doubly heavy baryons are related to the heavy mesons via heavy quark-diquark symmetry. Based on this symmetry, we predict the isospin splittings for doubly heavy baryons including {Xi}{sub cc}, {Xi}{sub bb} and {Xi}{sub bc}. The prediction for the {Xi}{sub cc} is much smaller than the SELEX value. On the other hand, the {Xi}{sub bb} baryons are predicted to have an isospin splitting as large as (6.3 {+-} 1.7) MeV. An experimental study of doubly bottomed baryons is therefore very important to better understand the structure of baryons with heavy quarks.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Kinematics of current region fragmentation in semi-inclusive deeply inelastic scattering

Different kinematical regions of semi-inclusive deeply inelastic scattering (SIDIS) processes correspond to different underlying partonic pictures, and it is important to understand the transition between them. We find criteria in semi-inclusive deeply inelastic scattering (SIDIS) for identifying the current fragmentation region — the kinematical region where a factorization picture with fragmentation functions is appropriate, especially for studies of transverse-momentum-dependent (TMD) functions. This region is distinguished from the central (soft) and target fragmentation regions. The basis of our argument is in the errors in approximations used in deriving factorization. As compared with previous work, we show that it is essential to take account of the transverse momentum of the detected hadron, and we find a much more restricted range for genuine current fragmentation. We show that it is important to develop an extended factorization formulation to treat hadronization in the central region, as well as the current and target fragmentation regions, and to obtain a unified formalism spanning all rapidities for the detected hadron.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Theoretical underpinnings of CP-violation at the high-energy frontier

We present a general analysis for the discovery potential of CP-violation (CPV) searches in scattering processes at TeV-scale colliders in an effective field theory framework, using the SMEFT basis for higher dimensional operators. In particular, we systematically examine the CP-violating sector of the SMEFT framework in some well motivated limiting cases, based on flavour symmetries of the underlying heavy theory. We show that, under naturality arguments of the underlying new physics (NP) and in the absence of (or suppressed) flavour-changing interactions, there is only a single operator, Q tΦ = Φ † Φ($\overline{q}$ 3 t) $\tilde{\phi}$ which alters the top-Yukawa coupling, that can generate a non-vanishing CP-violating effect from tree-level SM×NP interference terms. We find, however, that CPV from Q tΦ = Φ † Φ($\overline{q}$ 3 t) $\tilde{\phi}$ is expected to be at best of Ο (1%) and, therefore, very challenging if at all measurable at the LHC or other future high-energy colliders. We then conclude that a potentially measurable CP-violating effect of Ο (10%) can arise in high-energy scattering processes only if flavour-changing interactions are present in the underlying NP; in this case a sizable CPV can be generated at the tree-level by pure NP×NP effects and not from SM×NP interference. We provide several examples of CPV at the LHC and at a future e + s - collider to support these statements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

Unpolarized GPDs at small x and non-zero skewness

We study the small-x asymptotics of unpolarized generalized parton distributions (GPDs) and generalized transverse momentum distributions (GTMDs). Unlike the previous works in the literature, we consider the case of non-zero (but small) skewness while allowing for non-linear contributions to the evolution equations. We first show that unpolarized GPDs and GTMDs at small x are related to the eikonal dipole amplitude N, whose small-x evolution is given by the BK/JIMWLK evolution equations, and to the odderon amplitude $\mathscr{O}$, whose evolution is also known in the literature. We then show that the effect of non-zero skewness ξ ≠ 0 is to modify the value of the evolution parameter (rapidity) in the arguments for the dipole amplitudes N and $\mathscr{O}$ from Y = ln(1/x) to Y = ln min{1/|x|, 1/|ξ|}.

Generalized parton distributions (GPDs)↗
DOE OSTI2019

Nanoparticle emissions from residential wood combustion: A critical literature review, characterization, and recommendations

The increased use of wood as a heating fuel in residential and small commercial buildings has increased concern about potential environmental and safety impacts, specifically particulate matter (PM) emissions in the nanometer range. Larger particles (> 2.5 µm) can be effectively removed from exhaust streams by emission control devices. However, nanoparticles (NP), due to their size, are more difficult to capture in exhaust flue gases. In addition, NPs have a higher surface to volume ratio, allowing them to absorb organic compounds, causing them to be more reactive than their larger counterparts. This review focuses here on the NPs produced from residential wood heating devices. Current emission regulations do not reflect the NP count or type produced from residential wood combustion, although most published studies show that a significant portion of the particles produced during combustion is in the nano-size range. Fuel type, device type and combustion periods have all shown to impact, at various degrees, the NPs produced. Contrary to common expectations, it appears that modern units may generate a higher count of NPs, although emitting less particulate mass than older units. This investigation supports arguments of needed particle type and count regulations in addition to the current mass based emission regulations. In addition to a critical review and analysis, recommendations are made regarding future testing, monitoring and environmental impact studies that address the significance of NP emissions.

09 BIOMASS FUELS↗
DOE OSTI2021

High-throughput characterization of Lu-doped zirconia

Lu-doped zirconia (LuDZ) was reported in the 1960s to be a poor oxygen ion conductor. However, we identified this system as worthy of reexamination based on the results of a machine learning-based screen for promising oxygen ion conductors, further supported by a physical argument: because Lu is the heaviest and smallest of the lanthanides, it should offer the possibility of high conductivity due to its high polarizability and size compatibility with the zirconia structure. Here the relationship between dopant concentration and conductivity in the LuDZ system was determined using a high throughput experimental methodology in which spatially resolved conductivity was measured across a compositionally graded film, spanning from Zr 0.93 Lu 0.07 O 1.965 to Zr 0.82 Lu 0.18 O 1.91 . The conductivity broadly peaks with composition at 15 cation % Lu, coinciding with the approximate phase boundary of the fully stabilized cubic phase. The composition-dependent conductivity measurements reveal a surprising increase in activation energy for ion transport with increasing Lu content with no change in this trend at the composition of the conductivity maximum. The pre-exponential factor increases sharply with Lu content, but displays a distinct plateau once the conductivity maximum composition is attained. At 500 °C, the conductivity of Zr 0.85 Lu 0.15 O 1.925 is 2 × 10 –3 S cm –1 , approaching that of optimally doped Sc-stabilized zirconia, which has the highest reported conductivity among zirconia compounds. In comparison to other oxide ion conductors, Lu-stabilized zirconia offers the advantage over ceria of negligible electronic conductivity and is easier to process than (La,Sr)(Ga,Mg)O 3-δ .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

Understanding the mechanism of conductivity at the LaAlO3/SrTiO3(001) interface

The observation of conductivity at (001)-oriented interfaces of the two band insulators LaAlO3 and SrTiO3 is both fascinating and potentially useful for next-generation electronics. The reigning paradigm to explain the conductivity phenomenon is an electronic reconstruction resulting from the instability created by forming an interface of polar and nonpolar perovskites, leading to the formation of a two-dimensional electron gas. However, the complexities introduced by the strong tendency of the cations to mix across the interface also manifest themselves in the electronic structure, and this mixing gives rise to other ways for the interface to stabilize and become conductive. In this Prospective, arguments for and against these two explanations are explored and strategies for resolving the issue are suggested.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2013

Extremum seeking with bounded update rates

In this work, we present a form of extremum seeking (ES) in which the unknown function being minimized enters the system’s dynamics as the argument of a cosine or sine term, thereby guaranteeing known bounds on update rates and control efforts. We present general n-dimensional optimization and stabilization results as well as 2D vehicle control, with bounded velocity and control efforts. For application to autonomous vehicles, tracking a source in a GPS denied environment with unknown orientation, this ES approach allows for smooth heading angle actuation, with constant velocity, and in application to a unicycle-type vehicle results in control ability as if the vehicle is fully actuated. Our stability analysis is made possible by the classic results of Kurzweil, Jarnik, Sussmann, and Liu, regarding systems with highly oscillatory terms. In our stability analysis, we combine the averaging results with a semi-global practical stability result under small parametric perturbations developed by Moreau and Aeyels.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2011

Signal transduction profile of chemical sensitisers in dendritic cells: An endpoint to be included in a cell-based in vitro alternative approach to hazard identification?

The development of non-animal testing methods for the assessment of skin sensitisation potential is an urgent challenge within the framework of existing and forthcoming legislation. Efforts have been made to replace current animal tests, but so far no alternative methods have been developed. It is widely recognised that alternatives to animal testing cannot be accomplished with a single approach, but rather will require the integration of results obtained from different in vitro and in silico assays. The argument subjacent to the development of in vitro dendritic cell (DC)-based assays is that sensitiser-induced changes in the DC phenotype can be differentiated from those induced by irritants. This assumption is derived from the unique capacity of DC to convert environmental signals encountered at the skin into a receptor expression pattern (MHC class II molecules, co-stimulatory molecules, chemokine receptors) and a soluble mediator release profile that will stimulate T lymphocytes. Since signal transduction cascades precede changes in surface marker expression and cytokine/chemokine secretion, these phenotypic modifications are a consequence of a signal transduction profile that is specifically triggered by sensitisers and not by irritants. A limited number of studies have addressed this subject and the present review attempts to summarise and highlight all of the signalling pathways modulated by skin sensitisers and irritants. Furthermore, we conclude this review by focusing on the most promising strategies suitable for inclusion into a cell-based in vitro alternative approach to hazard identification.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2012

Relative sensitivity of developmental and immune parameters in juvenile versus adult male rats after exposure to di(2-ethylhexyl) phthalate

The developing immune system displays a relatively high sensitivity as compared to both general toxicity parameters and to the adult immune system. In this study we have performed such comparisons using di(2-ethylhexyl) phthalate (DEHP) as a model compound. DEHP is the most abundant phthalate in the environment and perinatal exposure to DEHP has been shown to disrupt male sexual differentiation. In addition, phthalate exposure has been associated with immune dysfunction as evidenced by effects on the expression of allergy. Male wistar rats were dosed with corn oil or DEHP by gavage from postnatal day (PND) 10–50 or PND 50–90 at doses between 1 and 1000 mg/kg/day. Androgen-dependent organ weights showed effects at lower dose levels in juvenile versus adult animals. Immune parameters affected included TDAR parameters in both age groups, NK activity in juvenile animals and TNF-α production by adherent splenocytes in adult animals. Immune parameters were affected at lower dose levels compared to developmental parameters. Overall, more immune parameters were affected in juvenile animals compared to adult animals and effects were observed at lower dose levels. The results of this study show a relatively higher sensitivity of juvenile versus adult rats. Furthermore, they illustrate the relative sensitivity of the developing immune system in juvenile animals as compared to general toxicity and developmental parameters. This study therefore provides further argumentation for performing dedicated developmental immune toxicity testing as a default in regulatory toxicology. -- Highlights: ► In this study we evaluate the relative sensitivities for DEHP induced effects. ► Results of this study demonstrate the age-dependency of DEHP toxicity. ► Functional immune parameters were more sensitive than structural immune parameters. ► Immune parameters were affected at lower dose levels than developmental parameters. ► Findings demonstrate the susceptibility of the developing immune system for DEHP.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Controlling the structure and ferroic properties of strained epitaxial NiTiO3 thin films on sapphire by post-deposition annealing

Ferroelectrically induced weak ferromagnetism had been predicted earlier in compounds MTiO3 (M = Fe, Mn, Ni) with the LiNbO3-type structure. In order to stabilize this metastable structure by oxide heteroepitaxy, we attempted to grow epitaxial NiTiO3 films on the nonpolar, non-magnetic substrate Al2O3 by pulsed laser deposition. Given the structural imperfections of the as-deposited films arising from the large lattice mismatch, which resulted in weak ferroic ordering, we investigated the effect of post-synthesis annealing on the films’ properties. Our structural data from x-ray diffraction and electron microscopy suggest that the crystalline quality of the NiTiO3 films was greatly improved by annealing the films at 600-1000 oC for 8 hours, with new phase formation along the interface at 1000 oC. Our physical property characterization indicates increased ferromagnetism and polarization after 600 oC, but a change in the magnetic state to likely ferrimagnetism, and a loss of polarization after the 1000 oC treatment. Our results suggest that the ferroic domain properties of the NiTiO3 films can be favorably altered by post-synthesis heat treatment at the proper temperature to manipulate interfacial strain and enhance the multiferroic properties. Improvement in the ferroic properties can be explained by a combination of crystallite growth, interfacial strain relief, and thermodynamic phase stability arguments. At the same time, exceeding temperatures may drive the system to a thermodynamically more favored crystalline order, and eventually to phase segregation and decomposition.

Varga, Tamas↗
DOE OSTI2016

Quantitative 3D electromagnetic field determination of 1D nanostructures from single projection

One-dimensional (1D) nanostructures have been regarded as the most promising building blocks for nanoelectronics and nanocomposite material systems as well as for alternative energy applications. Although they result in confinement of a material, their properties and interactions with other nanostructures are still very much three-dimensional (3D) in nature. In this work, we present a novel method for quantitative determination of the 3D electromagnetic fields in and around 1D nanostructures using a single electron wave phase image, thereby eliminating the cumbersome acquisition of tomographic data. Using symmetry arguments, we have reconstructed the 3D magnetic field of a nickel nanowire as well as the 3D electric field around a carbon nanotube field emitter, from one single projection. The accuracy of quantitative values determined here is shown to be a better fit to the physics at play than the value obtained by conventional analysis. Moreover the 3D reconstructions can then directly be visualized and used in the design of functional 3D architectures built using 1D nanostructures.

1D nanostructures↗
DOE OSTI2019

Planning for sustained water-electricity resilience over the U.S.: Persistence of current water-electricity operations and long-term transformative plans

The electricity system relies upon the availability and predictability of water to support hydropower operations and cooling of thermoelectric plants, implying that water plays a fundamental role in power operations and that water-related stresses may have a critical effect on the electricity system. Designing for electricity system resilience to changing societal demands and environmental conditions is a complex and urgent endeavor, one that requires robust diagnosis and an articulation of interdependencies among key system components. Here we consider the argument that water may help to navigate that complexity, revealing thresholds for system change and the transformations that may be required for enduring resilience of the electricity sector. To assess this thesis, we apply a framework for understanding resilient systems following Folke et al., that is extended in this special issue, by which resilience comprises three capabilities: system persistence, adaptability, and transformation. We apply this resilience diagnosis approach to the bulk electricity system of the contiguous United States, with particular attention to water-driven stressors. We provide a qualitative narrative that discusses the spectrum of resilience capabilities (persistence, adaptability, and transformability) of the water-electricity system in the United States over three scales of inter-dependencies: individual power plant, urban and grid scales.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2011

Bridging legal and economic perspectives on interstate municipal solid waste disposal in the US

Research highlights: {yields} Legal and economic opinions of free interstate trade of MSW in the US are reviewed. {yields} Economic theory of landfill space as the article of commerce can align opinions. {yields} Waste management policies implied by this economic theory are compared/contrasted. - Abstract: Managing municipal solid waste (MSW) within and across regions is a complex public policy problem. One challenge regards conceptualizing precisely what commodity is to be managed across space and time. The US Supreme Court view is that waste disposal is the article of commerce per se. Some justices, however, have argued that while waste disposal is the article of commerce, its interstate flow could be impeded by states on the grounds that they have the authority to regulate natural resource quality within their boundaries. The argument in this paper is that adopting the economic theory view of the article of commerce as landfill space brings the majority and dissenting US Supreme Court views-and the resulting sides of the public policy dispute-into closer alignment. We discuss waste management policy tools that emerge from this closer alignment that are more likely to both withstand judicial scrutiny and achieve economic efficiency.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2012

Screening tests for hazard classification of complex waste materials - Selection of methods

In this study we describe the development of an alternative methodology for hazard characterization of waste materials. Such an alternative methodology for hazard assessment of complex waste materials is urgently needed, because the lack of a validated instrument leads to arbitrary hazard classification of such complex waste materials. False classification can lead to human and environmental health risks and also has important financial consequences for the waste owner. The Hazardous Waste Directive (HWD) describes the methodology for hazard classification of waste materials. For mirror entries the HWD classification is based upon the hazardous properties (H1-15) of the waste which can be assessed from the hazardous properties of individual identified waste compounds or - if not all compounds are identified - from test results of hazard assessment tests performed on the waste material itself. For the latter the HWD recommends toxicity tests that were initially designed for risk assessment of chemicals in consumer products (pharmaceuticals, cosmetics, biocides, food, etc.). These tests (often using mammals) are not designed nor suitable for the hazard characterization of waste materials. With the present study we want to contribute to the development of an alternative and transparent test strategy for hazard assessment of complex wastes that is in line with the HWD principles for waste classification. It is necessary to cope with this important shortcoming in hazardous waste classification and to demonstrate that alternative methods are available that can be used for hazard assessment of waste materials. Next, by describing the pros and cons of the available methods, and by identifying the needs for additional or further development of test methods, we hope to stimulate research efforts and development in this direction. In this paper we describe promising techniques and argument on the test selection for the pilot study that we have performed on different types of waste materials. Test results are presented in a second paper. As the application of many of the proposed test methods is new in the field of waste management, the principles of the tests are described. The selected tests tackle important hazardous properties but refinement of the test battery is needed to fulfil the a priori conditions.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗