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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Integration of the ITER Tokamak C-model with the Building Model

The pellet injector system is designed to accommodate the requirement of continuous plasma refueling during ITER Tokamak operations. Through pellet flight tubes/injection lines, the pellets can directly reach the interior of the tokamak vacuum vessel. The pellet injector system is located at a port cell outside of the Tokamak bio-shield. The plasma radiation source in the tokamak vacuum vessel, together with the highly activated surrounding water in port cells, present major radiation challenges for the pellet injector system during ITER operation and after shutdown. These sources produce a radiation field encompassing the entire Tokamak complex. The ITER neutronics reference model C-model is an ITER radiation transport model. It represents a 40 deg. regular torus sector out to the bio-shield, which consists of 38 individual systems. The Monte Carlo N-Particle (MCNP) input of the C-model consists of more than a hundred thousand cell definitions and surface definitions, and over three hundred material compositions. The latest tokamak complex MCNP model is significantly more detailed than any previous releases. It consists of 36,863 cell definitions, 57,105 surface definitions, and a total of 21 different types of materials. The C-model and tokamak building model share the bio-shield as the boundary between them. In general, the radiation fields in the building due to the plasma source during tokamak operation are determined by generating the radiation source in the inner faces of the bio-shield. An inherent limitation of this approach is that it can only approximate the directions in which streaming paths are produced through the bio-shield plugs. To better estimate the shutdown dose rate for the pellet injector system due to the plasma source, we have decided to integrate the tokamak model (C-model) with the complex building model. Both MCNP models are provided by the ITER International Organization (IO) to the Oak Ridge National Laboratory (ORNL) Radiation Transport (RT) group.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

Mechanical Design Studies of the MQXF Long Model Quadrupole for the HiLumi LHC

The Large Hadron Collider Luminosity upgrade (HiLumi) program requires new low-β triplet quadrupole magnets, called MQXF, in the Interaction Region (IR) to increase the LHC peak and integrated luminosity. The MQXF magnets, designed and fabricated in collaboration between CERN and the U.S. LARP, will all have the same cross section. The MQXF long model, referred as MQXFA, is a quadrupole using the Nb3Sn superconducting technology with 150 mm aperture and a 4.2 m magnetic length and is the first long prototype of the final MQXF design. The MQXFA magnet is based on the previous LARP HQ and MQXFS designs. In this paper we present the baseline design of the MQXFA structure with detailed 3D numerical analysis. A detailed tolerance analysis of the baseline case has been performed by using a 3D finite element model, which allows fast computation of structures modelled with actual tolerances. Tolerance sensitivity of each component is discussed to verify the actual tolerances to be achieved by vendors. In conclusion, tolerance stack-up analysis is presented in the end of this paper.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

Secondary antiprotons as a Galactic Dark Matter probe

We present a novel determination of the astrophysical uncertainties associated to the secondary antiproton flux originating from cosmic-ray spallation on the interstellar gas. We select a set of propagation models compatible with the recent B/C data from PAMELA, and find those providing minimal and maximal antiproton fluxes in different energy ranges. We use this result to determine the most conservative bounds on relevant Dark Matter (DM) annihilation channels: we find that the recent claim of a DM interpretation of a gamma-ray excess in the Galactic Center region cannot be ruled out by current antiproton data. Finally, we discuss the impact of the recently released preliminary data from AMS-02. In particular, we provide a reference model compatible with proton, helium and B/C spectra from this experiment. Remarkably, the main propagation parameters of this model are in agreement with the best fit presented in our earlier statistical analyses. We also show that the antiproton-to-proton ratio does not exhibit any significant anomaly at high energy with respect to our predictions.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

Zero Trust Strategies for Chemical, Biological, Radiological, and Nuclear Detection Systems: D.1 Cyber Scenarios

The evolving landscape of cybersecurity necessitates a paradigm shift to a Zero Trust (ZT) model, which assumes breaches and continuously verifies trust. This approach reshapes how trust boundaries are established, focusing on identities, devices, networks, applications, and data, rather than solely relying on perimeter defenses such as firewalls. Central to this transformation is the National Institute of Standards and Technology's (NIST) Special Publication 800-207, outlining the Zero Trust Architecture (ZTA), along with Executive Order 14028, which mandates federal agencies to adopt ZT principles. Complementary to these efforts, the Cybersecurity and Infrastructure Security Agency (CISA) developed the Zero Trust Maturity Model (ZTMM), providing a framework with five pillars and three cross-cutting capabilities to guide agencies toward enhanced cybersecurity maturity. In support of these initiatives, the DHS Countering Weapons of Mass Destruction Office (CWMD) is applying ZT principles to secure Chemical, Biological, Radiological, and Nuclear (CBRN) detection systems. Recognizing the diverse deployment models and network connectivity of these systems—from stationary, non-networked units to mobile, cloud-connected devices—the Pacific Northwest National Laboratory (PNNL) is developing cybersecurity scenarios specifically for CBRN environments. These scenarios examine various configurations and technological capabilities, offering insights into the application of ZTMM pillars in enhancing the security postures of CBRN devices. The cybersecurity scenarios presented by PNNL are hypothetical, crafted to explore theoretical situations and stimulate discussion on the potential use or compromise of CBRN detection systems in varied contexts. These narratives are illustrative and do not reference any real events or actual networks. Instead, they employ generalized reference models to highlight concepts and potential issues within CBRN security, focusing on how Zero Trust strategies can be adapted to address these challenges effectively.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2015

On the need for the light elements primary process (LEPP)

Extant chemical evolution models underestimate the galactic production of Sr, Y, and Zr as well as the solar system abundances of s-only isotopes with 90 < A < 130. To solve this problem, an additional (unknown) process has been invoked, the so-called light element primary process (LEPP). In this paper we investigate possible alternative solutions. Based on Full Network Stellar evolutionary calculations, we investigate the effects on the solar system s-only distribution induced by the inclusion of some commonly ignored physical processes (e.g., rotation) or by the variation of the treatment of convective overshoot, mass loss, and the efficiency of nuclear processes. Our main findings are (1) at the epoch of the formation of the solar system, our reference model produces supersolar abundances for the whole s-only distribution, even in the range 90 < A < 130, (2) within errors, the s-only distribution relative to {sup 150}Sm is flat, (3) the s-process contribution of the less massive AGB stars (M < 1.5 M {sub ⊙}) as well as of the more massive ones (M > 4.0 M {sub ⊙}) are negligible, (4) the inclusion of rotation implies a downward shift of the whole distribution with a higher efficiency for the heavy s-only isotopes, leading to a flatter s-only distribution, (5) different prescriptions on convection or mass loss produce nearly rigid shifts of the whole distribution. In summary, a variation of the standard paradigm of AGB nucleosynthesis would allow reconciliation of model predictions with solar system s-only abundances. Nonetheless, the LEPP cannot be definitely ruled out because of the uncertainties still affecting stellar and galactic chemical evolution models.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

Radiography benchmark 2014

The purpose of the 2014 WFNDEC RT benchmark study was to compare predictions of various models of radiographic techniques, in particular those that predict the contribution of scattered radiation. All calculations were carried out for homogenous materials and a mono-energetic X-ray point source in the energy range between 100 keV and 10 MeV. The calculations were to include the best physics approach available considering electron binding effects. Secondary effects like X-ray fluorescence and bremsstrahlung production were to be taken into account if possible. The problem to be considered had two parts. Part I examined the spectrum and the spatial distribution of radiation behind a single iron plate. Part II considered two equally sized plates, made of iron and aluminum respectively, only evaluating the spatial distribution. Here we present the results of above benchmark study, comparing them to MCNP as the assumed reference model. The possible origins of the observed deviations are discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2014

The beauty of simple adaptive control and new developments in nonlinear systems stability analysis

Although various adaptive control techniques have been around for a long time and in spite of successful proofs of stability and even successful demonstrations of performance, the eventual use of adaptive control methodologies in practical real world systems has met a rather strong resistance from practitioners and has remained limited. Apparently, it is difficult to guarantee or even understand the conditions that can guarantee stable operations of adaptive control systems under realistic operational environments. Besides, it is difficult to measure the robustness of adaptive control system stability and allow it to be compared with the common and widely used measure of phase margin and gain margin that is utilized by present, mainly LTI, controllers. Furthermore, customary stability analysis methods seem to imply that the mere stability of adaptive systems may be adversely affected by any tiny deviation from the pretty idealistic and assumably required stability conditions. This paper first revisits the fundamental qualities of customary direct adaptive control methodologies, in particular the classical Model Reference Adaptive Control, and shows that some of their basic drawbacks have been addressed and eliminated within the so-called Simple Adaptive Control methodology. Moreover, recent developments in the stability analysis methods of nonlinear systems show that prior conditions that were customarily assumed to be needed for stability are only apparent and can be eliminated. As a result, sufficient conditions that guarantee stability are clearly stated and lead to similarly clear proofs of stability. As many real-world applications show, once robust stability of the adaptive systems can be guaranteed, the added value of using Add-On Adaptive Control along with classical Control design techniques is pushing the desired performance beyond any previous limits.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Persistence and memory timescales in root‐zone soil moisture dynamics

Abstract The memory timescale that characterizes root‐zone soil moisture remains the dominant measure in seasonal forecasts of land‐climate interactions. This memory is a quasi‐deterministic timescale associated with the losses (e.g., evapotranspiration) from the soil column and is often interpreted as persistence in soil moisture states. Persistence, however, represents a distribution of time periods where soil moisture resides above or below some prescribed threshold and is therefore inherently probabilistic. Using multiple soil moisture data sets collected at high resolution (subhourly) across different biomes and climates, this paper explores the differences, underlying dynamics, and relative importance of memory and persistence timescales in root‐zone soil moisture. A first‐order Markov process, commonly used to interpret soil moisture fluctuations derived from climate simulations, is also used as a reference model. Persistence durations of soil moisture below the plant water‐stress level (chosen as the threshold), and the temporal spectrum of upcrossings and downcrossings of this threshold, are compared to the memory timescale and spectrum of the full time series, respectively. The results indicate that despite the differences between meteorological drivers, the spectrum of threshold‐crossings is similar across sites, and follows a unique relation with that of the full soil moisture series. The distribution of persistence times exhibits an approximate stretched exponential type and reflects a likelihood of exceeding the memory at all sites. However, the rainfall counterpart of these distributions shows that persistence of dry atmospheric periods is less likely at sites with long soil moisture memory. The cluster exponent, a measure of the density of threshold‐crossings in a time frame, reveals that the clustering tendency in rainfall events (on‐off switches) does not translate directly to clustering in soil moisture. This is particularly the case in climates where rainfall and evapotranspiration are out of phase, resulting in less ordered (more independent) persistence in soil moisture than in rainfall.

Ghannam, Khaled↗
DOE OSTI2026

Dynamic analysis of fully constrained Cable-Driven Parallel Robots for automated prefabricated component installation

This paper presents a dynamic analysis and validation framework to assess a fully constrained six-anchor Cable-Driven Parallel Robot (CDPR) for automated installation of prefabricated facade components. Compared with conventional eight-anchor systems, the six-anchor configuration simplifies setup and reduces cost, but it also reduces control authority, shrinks the wrench-feasible workspace, and tightens orientation limits. Consequently, it is unclear a priori whether dynamically feasible trajectories exist to move the end effector from pickup to the facade. A constrained trajectory optimization is formulated to enforce the system dynamics, cable-tension bounds, and pose/velocity limits, and the framework is evaluated in simulation at three levels: (i) an idealized reference model, (ii) a lab-scale prototype model incorporating measured anchor misalignments and identified damping, and (iii) a full-scale three-story building model with load decomposition for structural feasibility checks. Across these scenarios, the analysis shows that optimal, constraint-satisfying trajectories exist that move the end effector from pickup to installation while maintaining a near-plumb, level orientation at the final pose. Collectively, this multi-scale dynamic analysis and validation framework supports the deployment readiness of the six-anchor CDPR and provides a prototype-based sensitivity case study of how measured anchor placement deviations affect feasibility.

CDPR↗
DOE OSTI2021

A simulation-based assessment of technologies to reduce heat emissions from buildings

Heat emissions from buildings are part of anthropogenic heat leading to urban overheating. This paper aims to assess how technologies (i.e., energy conservation measures - ECMs), used to decrease energy use, may also reduce heat emissions from buildings. This study employs the physics-based engine EnergyPlus to simulate the main components of heat emissions from buildings to ambient air: envelope, zone, and systems. Hourly simulations are run for IECC single- and multi-family reference models with three representative climates: Miami, Baltimore, and Chicago. The results show that the performance of ECMs varies among weather, seasons, and residential typologies. Particularly, some ECMs (i.e., cool coatings, heat pumps, additional insulation, energy-awareness occupants) show a strong decrease in heat emissions, yet they are not always correlated with proportional decreases in energy use. When all ECMs are combined, the reductions are larger on heat emissions (89%) than on site energy (65%) from the base cases. During summer in Miami, the combination of ECMs shows a decrease in heat emissions from the building surface component of 80% during daytime, 92% for the HVAC component and a counterbalanced increase in the zone component of 88%, bringing to a daily decrease in total heat emissions. The main contributions of this study are quantifying how typical ECMs influence residential building heat emissions using EnergyPlus simulations and informing urban planners and stakeholders on prioritizing measures for mitigating urban overheating problems.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2015

Propensity-Weighted Comparison of Long-Term Risk of Urinary Adverse Events in Elderly Women Treated For Cervical Cancer

Purpose: Cervical cancer treatment is associated with a risk of urinary adverse events (UAEs) such as ureteral stricture and vesicovaginal fistula. We sought to measure the long-term UAE risk after surgery and radiation therapy (RT), with confounding controlled through propensity-weighted models. Methods and Materials: From the Surveillance, Epidemiology, and End Results (SEER)-Medicare database, we identified women ≥66 years old with nonmetastatic cervical cancer treated with simple surgery (SS), radical hysterectomy (RH), external beam RT plus brachytherapy (EBRT+BT), or RT+surgery. We matched them to noncancer controls 1:3. Differences in demographic and cancer characteristics were balanced by propensity weighting. Grade 3 to 4 UAEs were identified by diagnosis codes plus treatment codes. Cumulative incidence was measured using Kaplan-Meier methods. The hazard associated with different cancer treatments was compared using Cox models. Results: UAEs occurred in 272 of 1808 cases (17%) and 222 of 5424 (4%) controls; most (62%) were ureteral strictures. The raw cumulative incidence of UAEs was highest in advanced cancers. UAEs occurred in 31% of patients after EBRT+BT, 25% of patients after RT+surgery, and 15% of patients after RH; however, after propensity weighting, the incidence was similar. In adjusted Cox models (reference = controls), the UAE risk was highest after RT+surgery (hazard ratio [HR], 5.07; 95% confidence interval [CI], 2.32-11.07), followed by EBRT+BT (HR, 3.33; 95% CI, 1.45-7.65), RH (HR, 3.65; 95% CI, 1.41-9.46) and SS (HR, 0.99; 95% CI, 0.32-3.01). The higher risk after RT+surgery versus EBRT+BT was statistically significant, whereas, EBRT+BT and RH were not significantly different from each other. Conclusions: UAEs are common after cervical cancer treatment, particularly in patients with advanced cancers. UAEs are more common after RT, but these women tend to have the advanced cancers. After propensity weighting, the risk after RT was similar to that after surgery.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2020

Measurement of the $\Upsilon$(1S) pair production cross section and search for resonances decaying to $\Upsilon$(1S)$\mu^+\mu^-$ in proton-proton collisions at $\sqrt{s} =$ 13 TeV

The fiducial cross section for Y(1S) pair production in proton-proton collisions at a center-of-mass energy of 13 TeV in the region where both Y(1S) mesons have an absolute rapidity below 2.0 is measured to be 79±11(stat)±6(syst)±3(B) pb assuming the mesons are produced unpolarized. The last uncertainty corresponds to the uncertainty in the Y(1S) meson dimuon branching fraction. The measurement is performed in the final state with four muons using proton-proton collision data collected in 2016 by the CMS experiment at the LHC, corresponding to an integrated luminosity of 35.9 fb−1 . This process serves as a standard model reference in a search for narrow resonances decaying to Y(1S)μ+μ− in the same final state. Such a resonance could indicate the existence of a tetraquark that is a bound state of two b quarks and two b¯ antiquarks. The tetraquark search is performed for masses in the vicinity of four times the bottom quark mass, between 17.5 and 19.5 GeV, while a generic search for other resonances is performed for masses between 16.5 and 27 GeV. No significant excess of events compatible with a narrow resonance is observed in the data. Limits on the production cross section times branching fraction to four muons via an intermediate Y(1S) resonance are set as a function of the resonance mass.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Testing NeuralGCM's capability to simulate future heatwaves based on the 2021 Pacific Northwest heatwave event

AI-based weather and climate models are emerging as accurate and computationally efficient tools. Beyond weather forecasting, they also show promise to accelerate storyline analyses. We evaluate NeuralGCM’s ability to simulate an extreme heatwave against the Energy Exascale Earth System Model (E3SM), a physics-based climate model. NeuralGCM accurately replicates the targeted event, and generates stable and realistic mid-century projections. However, due to the absence of land feedbacks, NeuralGCM underestimates the projected warming amplitude compared to physics-based model references.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Black hole–neutron star mergers: The first mass gap and kilonovae

Observations of X-ray binaries indicate a dearth of compact objects in the mass range from ~2 –5 M ⊙ . The existence of this (first mass) gap has been used to discriminate between proposed engines behind core-collapse supernovae. From LIGO/Virgo observations of binary compact remnant masses, several candidate first mass gap objects, either neutron stars (NSs) or black holes (BHs), were identified during the O3 science run. Motivated by these new observations, we study the formation of BH-NS mergers in the framework of isolated classical binary evolution, using population synthesis methods to evolve large populations of binary stars (Population I and II) across cosmic time. We present results on the NS to BH mass ratios (q = M NS /M BH ) in merging systems, showing that although systems with a mass ratio as low as q = 0.02 can exist, typically BH-NS systems form with moderate mass ratios q = 0.1 –0.2. If we adopt a delayed supernova engine, we conclude that ~30% of BH-NS mergers may host at least one compact object in the first mass gap (FMG). Even allowing for uncertainties in the processes behind compact object formation, we expect the fraction of BH-NS systems ejecting mass during the merger to be small (from ~0.6 –9%). In our reference model, we assume: (i) the formation of compact objects within the FMG, (ii) natal NS/BH kicks decreased by fallback, (iii) low BH spins due to Tayler-Spruit angular momentum transport in massive stars. We find that ≲1% of BH-NS mergers will have any mass ejection and about the same percentage will produce kilonova bright enough to have a chance of being detected with a large (Subaru-class) 8 m telescope. Interestingly, all these mergers will have both a BH and an NS in the FMG.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

Fuel assembly design for APR1400 with low CBC

APR 1400 is a PWR (Pressurized Water Reactor) with rated power of 3983 MWth and 241 assemblies. Recently, demand for extremely longer cycle up to 24 months is increasing with challenge of higher critical boron concentration (CBC). In this paper, assembly design method of selecting Gd-rods is introduced to reduce CBC. The purpose of the method is to lower the critical boron concentration of the preliminary core loading pattern (PLP), and consequently to achieve more negative or less positive moderator temperature coefficient (MTC). In this method, both the ratio of the number of low-Gd rod to the number of high-Gd rod (r) and assembly average Gd wt% (w) are the decision variables. The target function is the amount of soluble boron concentration reduction, which can be converted to Δk{sub TARGET}. A set of new designed fuel assembly satisfies an objective function, min [f=∑{sub i}(Δk{sub FA}−Δk{sub i})], and enables a final loading pattern to reach a target CBC. The constraints required to determine a set of Δk are physically realizable pair, (r,w), and the sum of Δk of new designed assemblies as close to Δk{sub TARGET} as possible. New Gd-bearing assemblies selected based on valid pairs of (r,w) are replaced with existing assemblies in a PLP. This design methodology is applied to Shin-Kori Unit 3 Cycle 1 used as a reference model. CASMO-3/MASTER code is used for depletion calculation. CASMO-3/MASTER calculations with new designed assemblies produce lower CBC than the expected CBC, proving that the proposed method works successful.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2024

The development of thermodynamically consistent and physics-informed equation-of-state model through machine learning

Ab initio molecular dynamics (AIMD) simulations have become an important tool used in the construction of equations of state (EOS) tables for warm dense matter. Due to computational costs, only a limited number of system state conditions can be simulated, and the remaining EOS surface must be interpolated for use in radiation-hydrodynamic simulations of experiments. In this work, we develop a thermodynamically consistent EOS model that utilizes a physics-informed machine learning approach to implicitly learn the underlying Helmholtz free-energy from AIMD generated energies and pressures. The model, referred to as PIML-EOS, was trained and tested on warm dense polystyrene producing a fit within a 1% relative error for both energy and pressure and is shown to satisfy both the Maxwell and Gibbs–Duhem relations. In addition, we provide a path toward obtaining thermodynamic quantities, such as the total entropy and chemical potential (containing both ionic and electronic contributions), which are not available from current AIMD simulations.

74 ATOMIC AND MOLECULAR PHYSICS↗