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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Entanglement, trace anomaly, and confinement in QCD

We formulate confinement in quantum chromodynamics (QCD) as an entropic surface phenomenon. Quark and gluon quantum information is localized on a transverse, entangling two-sphere of radius 𝑅 𝐸⁢𝐸 ; at this radius the QCD vacuum—partitioned by a hadron into interior and exterior regions—reaches its maximal entanglement entropy. Lattice-QCD determinations of the scalar (trace) gravitational form factors fix both 𝑅 𝐸⁢𝐸 and the transverse trace-anomaly density 𝜌 ℎ ⁡(𝑅 𝐸⁢𝐸 ), yielding a parameter-free slope 𝑐 ℎ = 8⁢𝜋 2 ⁢𝑅𝑆$^2_{𝐸⁢𝐸}$𝜌 ℎ ⁡(𝑅 𝐸⁢𝐸 ) and a mechanical entropy 𝑆 𝐸⁢𝐸 ⁡(𝑦) = 𝑐 ℎ ⁢𝑦 that grows linearly with rapidity 𝑦. The entropy gradient ∂ 𝑅 𝑆 𝐸⁢𝐸 changes sign at 𝑅 𝐸⁢𝐸 : it pushes colored degrees of freedom outward for 𝑟 <𝑅 𝐸⁢𝐸 and pulls them inward for 𝑟 >𝑅 𝐸⁢𝐸 , thereby localizing them on the codimension-2 entangling two-sphere Σ ⊥ = 𝑆$^2_{𝑅_{𝐸⁢𝐸}}$ (which, in the infinite-momentum frame (IMF), projects onto the transverse plane)—the “information wall.” This provides a high-energy (large-𝑦) entropic confinement diagnostic that complements—rather than replaces—Wilson’s area-law criterion, which probes long-distance dynamics near the rest frame (𝑦 → 0). Imposing unitarity on an entropic ansatz for the amplitude yields 𝜎⁡(𝑠) ∝ 𝑦 𝛿 . World data favor 𝛿 = 2 for elastic 𝑝⁡𝑝⁡($𝑝\bar{⁡𝑝}$) scattering and heavy-quark photoproduction, whereas 𝜙 photoproduction favors a softer 𝛿 = 0.387. All extracted cross sections remain well below the Froissart-Martin bound. These results provide a confinement criterion quantified directly from nonperturbative QCD inputs, unifying the trace anomaly, entanglement entropy, and high-energy scattering within a single quantitative framework.

Color confinement↗
NASA NTRS1984

An experimental investigation of gas jets in confined swirling air flow

The fluid dynamics of jets in confined swirling flows which is of importance to designers of turbine combustors and solid fuel ramjets used to power missiles fired from cannons were examined. The fluid dynamics of gas jets of different densities in confined swirling flows were investigated. Mean velocity and turbulence measurements are made with a one color, one component laser velocimeter operating in the forward scatter mode. It is shown that jets in confined flow with large area ratio are highly dissipative which results in both air and helium/air jet centerline velocity decays. For air jets, the jet like behavior in the tube center disappears at about 20 diameters downstream of the jet exit. This phenomenon is independent of the initial jet velocity. The turbulence field at this point also decays to that of the background swirling flow. A jet like behavior in the tube center is noticed even at 40 diameters for the helium/air jets. The subsequent flow and turbulence field depend highly on the initial jet velocity. The jets are fully turbulent, and the cause of this difference in behavior is attributed to the combined action swirl and density difference. This observation can have significant impact on the design of turbine combustors and solid fuel ramjets subject to spin.

Mongia, H.↗
DOE OSTI2025

Solving the strong CP problem with massless grand-color quarks

We propose a solution to the strong CP problem that specifically relies on massless quarks and has no light axion. The QCD color group SU(3) c is embedded into a larger, simple gauge group (grand-color) where one of the massless, colored fermions enjoys an anomalous chiral symmetry, rendering the strong CP phase unphysical. The grand-color gauge group G GC is Higgsed down to SU(3) c × ${G}_{c^{\prime }}$, after which ${G}_{c^{\prime }}$ eventually confines at a lower scale, spontaneously breaking the chiral symmetry and generating a real, positive mass to the massless, colored fermion. Since the chiral symmetry has a ${G}_{c^{\prime }}$ anomaly, there is no corresponding light Nambu-Goldstone boson. The anomalous chiral symmetry can be an accidental symmetry that arises from an exact discrete symmetry without introducing a domain wall problem. Potential experimental signals of our mechanism include vector-like quarks near the TeV scale, pseudo Nambu-Goldstone bosons below the 10 GeV scale, light dark matter decay, and primordial gravitational waves from the new strong dynamics.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Primordial Black Holes with QCD Color Charge

We describe a realistic mechanism whereby black holes with significant QCD color charge could have formed during the early Universe. Primordial black holes (PBHs) could make up a significant fraction of the dark matter if they formed well before the QCD confinement transition. Such PBHs would form by absorbing unconfined quarks and gluons and hence could acquire a net color charge. We estimate the number of PBHs per Hubble volume with near-extremal color charge for various scenarios and discuss possible phenomenological implications. Published by the American Physical Society 2024

Physics↗
DOE OSTI2023

Two-Factor Phase Separations in Mixed-Halide Quasi-2D Perovskite LEDs: Dimensionality and Halide Segregations

Quasi-2D halide perovskites have attracted much interest as a promising material for light-emitting diodes (LEDs) due to their tunability in quantum confinement and halide alloy formation to modulate the energy bandgap and emission color. However, two-factor phase separations with respect to heterogeneous quantum-well thicknesses and halide segregation are still crucial issues in quasi-2D perovskite LEDs, leading to low external quantum efficiencies (EQEs) and color shifts. In this work, we compare quasi-2D perovskite films using different cations to unveil the key contributions from the chemical design of organic cations. While mixing halide ions in conventional quasi-2D perovskite films induces micrometer-scale heterogeneity, new extended and twisted conjugated cations suppress the two-factor phase separations, leading to high EQEs of over 25% and controllable emission wavelengths across red and near-infrared regions. The fundamental insights in this work will provide guidance for advancing materials design and device performance in the future.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1984

Turbulent swirling combustion

The non-reacting flow produced by two confined, co- and/or counter-swirling jets wre measured by means of a two-color laser Doppler velocimeter. These results are compared with earlier experiments and with numerical predictions. It is shown that under both swirl conditions, a closed recirculation zone is created at the combustor center line. This zone is characterized by the presence of a one-cell toroidal vortex, low tangential velocities, high turbulent intensity, and large dissipation rates of the kinetic energy of turbulence.

Sommer, H. T.↗
NASA NTRS1990

Near-infrared mapping of spiral barred galaxies

In external galaxies, near-infrared emission originates from stellar populations, hot dust, free-free emission from H+ regions, gaseous emission, non-thermal nucleus if any. Because of the low extinction compared to the visible, infrared wavelengths are useful to probe regions obscured by dust such as central parts where starburst phenomena can occur because of the large quantity of matter. The results presented were obtained with a 32 x 32 InSb charge injection device (CID) array cooled at 4K, at the f/36 cassegrain focus of the 3m60 Canada-France-Hawaii telescope with a spatial resolution of 0.5 inches per pixel. The objects presented are spiral barred galaxies mapped at J(1.25 microns), H(1.65 microns) and K(2.2 microns). The non-axisymetric potential due to the presence of a bar induces dynamical processes leading to the confinement of matter and peculiar morphologies. Infrared imaging is used to study the link between various components. Correlations with other wavelengths ranges and 2-colors diagrams ((J-H), (H-K)) lead to the identification of star forming regions, nucleus. Maps show structures connected to the central core. The question is, are they flowing away or toward the nucleus. Observations of M83 lead to several conclusions. The star forming region, detected in the visible and the infrared cannot be very compact and must extend to the edge of the matter concentration. The general shape of the near-infrared emission and the location of radio and 10 micron peaks suggest the confinement of matter between the inner Linblad resonances localized from CO measurements about 100 and 400 pc. The distribution of color indices in the arc from southern part to the star forming region suggests an increasing amount of gas and a time evolution eventually triggered by supernova explosions. Close to the direction of the bar, a bridge-like structure connects the arc to the nucleus with peculiar color indices. Perhaps, this structure can be linked to a height velocity component seen in UV and we can attribute it to a jet and/or a matter flow along the bar toward the nucleus, fuelling it. NGC 1068 is the nearest Seyfert 2 galaxy. It has been a subject of many studies at all wavelengths. This object was mapped at J, H, K, L and M, and in polaro-imagery. Results are given.

Gallais, P.↗
DOE OSTI2024

Large $$N_c$$ QCD phase diagram at $$\mu _B=0$$

Abstract Lattice studies suggest that at zero baryon chemical potential and increasing temperature there are three characteristic regimes in QCD that are connected by smooth analytical crossovers: a hadron gas regime at$$T < T_{ch}\sim 155$$ T < T ch ∼ 155 MeV, an intermediate regime, called stringy fluid, at$$T_{ch}< T < \sim 3 T_{ch}$$ T ch < T < ∼ 3 T ch , and a quark-gluon plasma regime at higher temperatures. These regimes have been interpreted to reflect different approximate symmetries and effective degrees of freedom. In the hadron gas the effective degrees of freedom are hadrons and the approximate chiral symmetry of QCD is spontaneously broken. The intermediate regime has been interpreted as lacking spontaneous chiral symmetry breaking along with the emergence of new approximate symmetry, chiral spin symmetry, that is not a symmetry of the Dirac Lagrangian, but is a symmetry of the confining part of the QCD Lagrangian. While the high temperature regime is the usual quark-gluon plasma which is often considered to reflect “deconfinement” in some way. This paper explores the behavior of these regimes of QCD as the number of colors in the theory,$$N_c$$ N c , gets large. In the large$$N_c$$ N c limit the theory is center-symmetric and notions of confinement and deconfinement are unambiguous. The energy density is$$\mathcal{O}(N_c^0)$$ O ( N c 0 ) in the meson gas,$${{\mathcal {O}}}(N_c^1)$$ O ( N c 1 ) in the intermediate regime and$${{\mathcal {O}}}(N_c^2)$$ O ( N c 2 ) in the quark-gluon plasma regime. In the large$$N_c$$ N c limit these regimes may become distinct phases separated by first order phase transitions. The intermediate phase has the peculiar feature that glueballs should exist and have properties that are unchanged from what is seen in the vacuum (up to$$1/N_c $$ 1 / N c corrections), while the ordinary dilute gas of mesons with broken chiral symmetry disappears and approximate chiral spin symmetry should emerge.

Physics↗
DOE OSTI2025

Confinement-Driven Segregation Enables Glassy Polymer Hybrid Materials Featuring Disordered Hyperuniformity and Integrated Self-Healing

The blending of glassy copolymer-brush modified colloids with a viscoelastic linear copolymer featuring intrinsic self-healing enabled disordered hyperuniform hybrid materials that combined mechanical robustness with structural color, processability, environmental stability, and the ability to recover structure and properties after incurring physical damage via ‘integrated self-healing’. Symmetric linear n-butyl acrylate/methyl methacrylate (BA/MMA) were co-assembled with asymmetric glassy BA/MMA statistical copolymer brush (silica) particles. ‘Confinement-driven segregation’ resulted in a microphase-separated morphology in which the linear copolymer resided within the interstitial regions of a rigid (∼1 GPa) copolymer brush particle template with disordered hyperuniform microstructure. Diffusion of the self-healing copolymer additive into damage regions drove the recovery after damage, along with the restoration of structural color due to the materials hyperuniform microstructure. The synergistic action of intrinsic and extrinsic healing mechanisms could provide a versatile platform for the bottom-up fabrication of multifunctional hybrid materials with increased damage resistance and functional longevity.

36 MATERIALS SCIENCE↗
NASA NTRS1995

Four-Spot Time-Of-Flight Laser Anemometer For Turbomachinery

Two-color, four-spot time-of-flight laser anemometer designed for measuring flow velocity within narrow confines of small centrifugal compressor. Apparatus well suited for measuring fast (typical speeds 160 to 700 m/s), highly turbulent gas flows in turbomachinery. Other potential applications include measurement of gas flows in pipelines and in flows from explosions.

Wernet, Mark P.↗
NASA NTRS2009

Further Studies on the Physical and Biogeochemical Causes for Large Interannual Changes in the Patagonian Shelf Spring-Summer Phytoplankton Bloom Biomass

A very strong and persistent phytoplankton bloom was observed by ocean color satellites during September - December 2003 along the northern Patagonian shelf. The 2003 bloom had the highest extent and chlorophyll a (Chl-a) concentrations of the entire Sea-viewing Wide Field-of-view Sensor (SeaWiFS) period (1997 to present). SeaWiFS-derived Chl-a exceeded 20 mg/cu m in November at the bloom center. The bloom was most extensive in December when it spanned more than 300 km across the shelf and nearly 900 km north-south (35degS to 43degS). The northward reach and the deep penetration on the shelf of the 2003 bloom were quite anomalous when compared with other years, which showed the bloom more confined to the Patagonian shelf break (PSB). The PSB bloom is a conspicuous austral spring-summer feature detected by ocean color satellites and its timing can be explained using the Sverdrup critical depth theory. Based on high-resolution numerical simulations, in situ and remote sensing data, we provide some suggestions for the probable mechanisms responsible for that large interannual change of biomass as seen by ocean color satellites. Potential sources of macro and micro (e.g., Fe) nutrients that sustain the high phytoplankton productivity of the Patagonian shelf waters are identified, and the most likely physical processes that maintain the nutrient balance in the region are discussed.

Signorini, Sergio R.↗
DOE OSTI2024

Emergent Properties from Three-Dimensional Assemblies of (Nano)particles in Confined Spaces

The assembly of (nano)particles into compact hierarchical structures yields emergent properties not found in the individual constituents. The formation of these structures relies on a profound knowledge of the nanoscale interactions between (nano)particles, which are often designed by researchers aided by computational studies. These interactions have an effect when the (nano)particles are brought into close proximity, yet relying only on diffusion to reach these closer distances may be inefficient. Recently, physical confinement has emerged as an efficient methodology to increase the volume fraction of (nano)particles, rapidly accelerating the time scale of assembly. Specifically, the high surface area of droplets of one immiscible fluid into another facilitates the controlled removal of the dispersed phase, resulting in spherical, often ordered, (nano)particle assemblies. In this review, we discuss the design strategies, computational approaches, and assembly methods for (nano)particles in confined spaces and the emergent properties therein, such as trigger-directed assembly, lasing behavior, and structural photonic color. Finally, we provide a brief outlook on the current challenges, both experimental and computational, and farther afield application possibilities.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Qualitative Risk Assessment of Legacy Wells within the Estimated Prairie State Generating Company Area of Review

This report details the digitization of a legacy wellbore database, including data processing assumptions, parameter estimation, and risk assessment methodology. The database, comprising 6,454 documents, was provided by ISGS. It includes valuable data from the Prairie State Generating Company (PSGC) and One Earth Energy (OEE) sites of the CarbonSAFE Phase III – Illinois Storage Corridor project. The report focuses on wells within a 15-mile radius from the Lively Grove #1 (LG#1) well at PSGC site, evaluating subsurface conditions and potential risks. A total of 4,386 wellbores within 15 miles of the LG#1 well were filtered based on depth and formation codes. LG#1 is the stratigraphic well at the PSGC site drilled in 2021. Ninety-four (94) wells penetrating the Maquoketa Shale Group (the primary confining unit) within the estimated area-of-review (AoR) for the PSGC site were evaluated using a qualitative risk assessment (QRA) methodology. The QRA developed by Arbad et al. 2022 focuses on legacy wells within the AoR and categorizes them based on well construction details. The QRA identifies wells that need immediate attention by categorizing them based on penetration depth and protection. Wells within the AoR were categorized into nine groups based on penetrations and protections. These categories range from Type 1 wells, with no documentation, to Type 9 wells, which do not penetrate the primary confining unit or storage reservoir (unit). Well accessibility within the AoR varies based on well status, including Dry & Abandoned (DA), Plugged & Abandoned (PA), Injection (INJ), Oil/Gas Producing (PROD), and Observation (Obs) wells. Accessibility levels were determined by well construction, with DA wells being the least accessible and Observation wells the most accessible, impacting gas leakage detection possibilities. Remedial action priority of wells decreases from Type 1 to Type 9 wells. Type 1 to Type 6 wells with status DA and PA require immediate attention, while Type 7 and Type 8 wells are low priority. A risk matrix used to prioritize corrective actions for legacy wells is proposed to categorize wells within an AoR based on penetrations, protections, and accessibility. The methodology involves data acquisition, well categorization into nine types, and determining CO 2 leakage pathways using well schematics and geospatial mapping. This approach is particularly useful for managing the integrity of legacy wells throughout the lifecycle of a Carbon Capture and Storage (CCS) project. A qualitative risk assessment of 94 wells within the AoR of the PSGC site identified 54 wells with high priority for corrective action due to penetration of the primary containment seal. The assessment utilizes color-coded maps to categorize well types and prioritize corrective actions, providing a comprehensive analysis. Schematics of wells penetrating the primary confining unit were drawn, and leakage pathways were identified. Details of all wells penetrating the confining zone are provided in the appendix, including information on well types, plugging, and casing status.

01 COAL, LIGNITE, AND PEAT↗
NASA NTRS1986

LDV measurements in an annular combustor model

The design and setup of a Laser Doppler Velocimeter (LDV) system used to take velocity measurements in an annular combustor model are covered. The annular combustor model is of contemporary design using 60 degree flat vane swirlers, producing a strong recirculation zone. Detailed measurements are taken of the swirler inlet air flow and of the downstream enclosed swirling flow. The laser system used is a two color, two component system set up in forward scatter. Detailed are some of the special considerations needed for LDV use in the confined turbulent flow of the combustor model. The LDV measurements in a single swirler rig indicated that the flow changes radically in the first duct height. After this, a flow profile is set up and remains constant in shape. The magnitude of the velocities gradually decays due to viscous damping.

Barron, Dean A.↗
NASA NTRS1996

LDV Measurements in an Annular Combustor Model

This thesis covers the design and setup of a laser doppler velocimeter (LDV) system used to take velocity measurements in an annular combustor model. The annular combustor model is of contemporary design using 60 degree flat vane swirlers, producing a strong recirculation zone. Detailed measurements are taken of the swirler inlet air flow and of the downstream enclosed swirling flow. The laser system used is a two color, two component system set up in forward scatter. Detailed are some of the special considerations needed for LDV use in the confined turbulent flow of the combustor model. LDV measurements in a single swirler rig indicated that the flow changes radically in the first duct height. After this, a flow profile is set up and remains constant in shape. The magnitude of the velocities gradually decays due to viscous damping.

Barron, Dean A.↗
NASA NTRS1994

The stellar population in the core of M15

The inner core of the globular cluster M15 within approximately 2 sec of the geometrical center has been explored with high-resolution images taken through several broad-band UV filter with the Faint Object Camera (FOC) on board the Hubble Space Telescope (HST). Approximately 210 stars in this region down to a 5 sigma detection limit of m(sub 220) = 21.5 were reliably identified and located on a UV - U color magnitude diagram for the first time. A majority of stars (about 70% of the total) observed this way lie above the expected main-sequence turn-off of this cluster and below the sparsely populated horizontal branch. The extension of the main sequence above the turn-off separates this population in two roughly equal components situated to the right and left of this line. Most of the former must be classical blue stragglers while the rest belong to a new, as yet unidentified, population of very blue stars. Possibilities include, but are not restricted to, well-mixed single stars, subdwarfs, and helium white dwarfs. Similar objects are also found just outside the core out to approximately 6 sec from the center, but the brighter, presumably more massive ones, are sharply confined to the core itself. The measured excess of bright blue stars and the relative deficiency of bright red giants in the core are consistent with the blue inward color gradient measured from the ground and imply that dynamical evolution can significantly affect the stellar population in the very dense central regions of a high-concentration globular cluster like M15.

De Marchi, Guido↗
NASA NTRS1984

Characteristics of inhomogeneous jets in confined swirling air flows

An experimental program to study the characteristics of inhomogeneous jets in confined swirling flows to obtain detailed and accurate data for the evaluation and improvement of turbulent transport modeling for combustor flows is discussed. The work was also motivated by the need to investigate and quantify the influence of confinement and swirl on the characteristics of inhomogeneous jets. The flow facility was constructed in a simple way which allows easy interchange of different swirlers and the freedom to vary the jet Reynolds number. The velocity measurements were taken with a one color, one component DISA Model 55L laser-Doppler anemometer employing the forward scatter mode. Standard statistical methods are used to evaluate the various moments of the signals to give the flow characteristics. The present work was directed at the understanding of the velocity field. Therefore, only velocity and turbulence data of the axial and circumferential components are reported for inhomogeneous jets in confined swirling air flows.

So, R. M. C.↗
DOE OSTI2022

Electrical Switching of Nematic Plasmonic Nanocolloids for Infrared Solar Gain Control

Controlling solar gain is essential to reduce the energy consumption by residential and commercial buildings, which are responsible for ≈40% of all energy generated globally. However, the dynamic control of solar gain in the near-infrared that corresponds to ≈50% of the overall Sun's energy at the Earth's surface, separately from the visible spectral range has been a challenge, albeit commercial coatings provide passive control while retaining highly visible transmission. To address this problem, in this paper switchable silver colloids (SSCs) are demonstrated, colloidal analogs of the common silver coatings used for solar gain control. When dispersed in a nematic liquid crystal, orientations of such plasmonic silver nanoplates are controlled by ≈1 V low-voltage electric fields, allowing for sub-second switching of the near-infrared-based solar gain. Installed and retrofit products made from thin films of such nanoplate dispersions confined between glass and plastic substrates, respectively, exhibit electrically controlled infrared-based solar gain while retaining high visible-range transparency, low haze, and high color rendering index. Furthermore, this study's findings reveal a great potential of soft-matter systems in addressing energy-related problems.

36 MATERIALS SCIENCE↗