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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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Polaron catastrophe within quantum acoustics
The quantum acoustic framework has recently emerged as a nonperturbative, coherent approach to electron–lattice interactions, uncovering rich physics often obscured by perturbative methods with incoherent scattering events. Here, we model the strongly coupled dynamics of electrons and acoustic lattice vibrations within this framework, representing lattice vibrations as coherent states and electrons as quantum wave packets, in a manner distinctively different from tight-binding or discrete hopping-based approaches. We derive and numerically implement electron backaction on the lattice, providing both visual and quantitative insights into electron wave packet evolution and the formation of acoustic polarons. We investigate polaron binding energies across varying material parameters and compute key observables—including mean square displacement, kinetic energy, potential energy, and vibrational energy—over time. Our findings reveal the conditions that favor polaron formation, which is enhanced by low temperatures, high deformation potential constants, slow sound velocities, and high effective masses. Additionally, we explore the impact of external electric and magnetic fields, showing that while polaron formation remains robust under moderate fields, it is weakly suppressed at higher field strengths. These results deepen our understanding of polaron dynamics and pave the way for future studies into nontrivial transport behavior in quantum materials.
The Biermann catastrophe in numerical magnetohydrodynamics
The Biermann battery effect is frequently invoked in cosmic magnetogenesis and studied in high-energy density laboratory physics experiments. Generation of magnetic fields by the Biermann effect due to misaligned density and temperature gradients in smooth flow behind shocks is well known. We show that a Biermann-effect magnetic field is also generated within shocks. Direct implementation of the Biermann effect in MHD codes does not capture this physical process, and worse, it produces unphysical magnetic fields at shocks whose value does not converge with resolution. We show that this convergence breakdown is due to naive discretization, which fails to account for the fact that discretized irrotational vector fields have spurious solenoidal components that grow without bound near a discontinuity. We show that careful consideration of the kinetics of ion viscous shocks leads to a formulation of the Biermann effect that gives rise to a convergent algorithm. We note two novel physical effects: a resistive magnetic precursor, in which a Biermann-generated field in the shock “leaks” resistively upstream, and a thermal magnetic precursor, in which a field is generated by the Biermann effect ahead of the shock front owing to gradients created by the shock’s electron thermal conduction precursor. Both effects appear to be potentially observable in experiments at laser facilities. We reexamine published studies of magnetogenesis in galaxy cluster formation and conclude that the simulations in question had inadequate resolution to reliably estimate the field generation rate. Corrected estimates suggest primordial field values in the range B∼10{sup −22}–10{sup −19} G by z = 3.
Disc formation in turbulent cloud cores: is magnetic flux loss necessary to stop the magnetic braking catastrophe or not?
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Catastrophe theory classification of Fermi surface topological transitions in two dimensions
Not Available
An Investigation of Catastrophic Failure in Solid-State Lamps Exposed to Harsh Environment Operational Conditions
Today’s lighting technology is steadily becoming more energy efficient and less toxic to the environment since the passing of the Energy Independence and Security Act of 2007 (EISA) [1]. EISA has mandated a higher energy efficiency standard for lighting products and the phase out of the common incandescent lamp. This has led lighting manufacturers to pursue solid-state lighting (SSL) technologies for consumer lighting applications. However, two major roadblocks are hindering the transition process to SSL lamps: cost and quality. In order to cut cost, manufactures are moving towards cheaper packaging materials and a variety of package architecture construction techniques which may potentially erode the quality of the lamp and reduce its survivability in everyday applications. Typically, SSL lamps are given product lifetimes of over twenty years based off of the IES TM-21-11 lighting standard which does not include moisture effects or large operational temperatures [2]. A group of recently released off-the-shelf lamps have undergone a steady-state temperature humidity bias life test of 85°C/85%RH (85/85) to investigate the reliability in harsh environment applications. The lack of accelerated test methods for lamps to assess reliability prior to introduction into the marketplace does not exist in literature. There is a need for SSL physics based models for the assessment and prediction of a lamp’s lifetime which is being spearheaded by the DOE [3]. In order to be fully accepted in the marketplace, SSL lamps must be able to perform similarly to incandescent lamps in these environments, as well as live up to the lifetime claims of manufacturers. A lamp’s package architecture must be designed with performance factors in mind, as well as address some of the known and published package related failure mechanisms, such as carbonization of the encapsulant material, delamination, encapsulant yellowing, lens cracking, and phosphor thermal quenching [4]. Each failure mechanism produces the similar failure mode of lumen degradation predominately due to two contributing factors: high junction temperature and moisture ingress. The current state-of-the-art has focused on individual areas of the lamp, such as the LED chip, substrate material, electrical driver design and thermal management techniques. [5] – [16] Looking at the lamp as a whole is a novel approach and has not been seen before in literature. This work followed the JEDEC standard JESD22-A101C of 85/85 with a one hour interval of applied voltage followed by a one hour interval of no applied voltage [17]. This test was performed continuously for each SSL lamp until it became nonoperational, i.e. did not turn on. Periodically, photometric measurements were taken following the IES LM-79-08 standard at room temperature using an integrating sphere, a spectrometer, and lighting software. The overall health of the SSL lamps was assed using the relative luminous flux (RLF), correlated color temperature (CCT) and the color difference (Δu'v') using the Euclidean distance of the CIE 1976 color space coordinates. Finally, a Weibull analysis was completed to compare the characteristic lifetime of the SSL lamp to the actual rated lifetime. An important result from this work shows that the rated lifetime does not come close to the actual lifetime when the SSL lamps are used in a harsh humid environment which is fairly common in outdoor applications across the U.S. Also, the photometric results are presented for the entire lifetime of each SSL lamp under test.
Rapidly expanding nuclear arsenals in Pakistan and India portend regional and global catastrophe
Pakistan and India may have 400 to 500 nuclear weapons by 2025 with yields from tested 12- to 45-kt values to a few hundred kilotons. If India uses 100 strategic weapons to attack urban centers and Pakistan uses 150, fatalities could reach 50 to 125 million people, and nuclear-ignited fires could release 16 to 36 Tg of black carbon in smoke, depending on yield. The smoke will rise into the upper troposphere, be self-lofted into the stratosphere, and spread globally within weeks. Surface sunlight will decline by 20 to 35%, cooling the global surface by 2° to 5°C and reducing precipitation by 15 to 30%, with larger regional impacts. Recovery takes more than 10 years. Net primary productivity declines 15 to 30% on land and 5 to 15% in oceans threatening mass starvation and additional worldwide collateral fatalities.
Planned Destruction of Metal-Core Reactor: Simulation of Catastrophic Accidents and New Experimental Possibilities
A reactor with a destructible core (RIR reactor) generating a pulse with an output of ~1.5 × 10{sup 19} fissions and a full width at half maximum of ~2.5 μs was developed and tested at VNIIEF. In the course of investigation, a computational-experimental method for laboratory calibration of the reactor was created and worked out. This method ensures a high accuracy of predicting the energy release in a real experiment with excess reactivity of ~3β{sub eff} above prompt criticality. A transportable explosion-proof chamber was also developed, which ensures the safe localization of explosion products of the core of small-sized nuclear devices and charges of high explosives with equivalent mass of up to 100 kg of TNT.
Risk Assessment of Catastrophic Leak Of R-452b From Package Unit into A Residential Space
With the effort to find alternative refrigerants with lower global warming potential (GWP), challenges have arisen due to the flammability risk for many of the alternatives. One of the new alternatives is R-452B, which is recommended as a replacement for R410A. R-452B is classified as a mildly flammable refrigerant (A2L) by ANSI/ASHRAE Standard 34. This paper summarizes a computational fluid dynamic (CFD) simulation study of a leak incident of R-452B from a 3-ton packaged unit which serves a 167 m 2 residence. The R-452B leak is assumed to be downstream of the evaporator coil. The simulated residence has four rooms and a hallway. The packaged unit distributes the conditioned air through a supply duct system delivering the air through registers. The dispersion of R-452B is characterized for two scenarios: one with underfloor supply air ducts and another with ceiling supply air ducts. The mass flow rate of R-452B exiting the duct outlets is quantified and the refrigerant volume fraction is monitored inside the residential space.
“Catastrophic Hail Storm & Lightning Characteristics From It” for NWSFO Amarillo June 19, 2020
The storm developed along an outflow boundary. Daytime heating helped break two capping inversions noted on the morning weather balloon launch from KAMA. The storm appears to have reached a 35-40 dbz threshold quickly around 15:20. Pantex’s LMA detects “source densities” at 15:20. The first intra-cloud (CC) strikes occur simultaneously at 15:26 just west of 34th & Soncy. The first cloud-to-ground (CG) lightning strike occurred 7 minutes later at15:33 just west of Jason’s Deli (34th and Coulter Shopping Center).
Comparison of Side-on Peak Overpressure Predictions and Measurements for Type IV Composite Overwrapped Pressure Vessel Catastrophic Failure
This development of empirical data to support realistic and science-based input to safety regulations and transportation standards is a critical need for the hazardous material (HM) transportation industry. Current regulations and standards are based on the TNT equivalency model. However, real world experience indicates that use of the TNT equivalency model to predict composite overwrapped pressure vessel (COPV) potential energy release is unrealistically conservative. The purpose of this report is to characterize and quantify rupture events involving damaged COPV’s of the type used in HM transportation regulated by the Department of Transportation (DOT). This was accomplished using a series of five tests; 2 COPV tests for compressed natural gas (CNG), 2 COPV tests for hydrogen, and 1 COPV test for nitrogen. Measured overpressures from these tests were compared to predicted overpressures from a TNT equivalence model and blast curves. Comparison between the measurements and predictions shows that the predictions are generally conservative, and that the extent of conservatism is dominated by predictions of the chemical contribution to overpressure from fuel within the COPVs.
Innovative Technology for Continuous, Online (in situ) Monitoring of Corrosivity of Molten Salts to Prevent Catastrophic Failure of Solar Thermal Plants
This project aims to evaluate and develop the concept of optical basicity to solar molten salts, design an online monitoring system for implementation in commercial plants, and train a diverse workforce for the CSP industry. This is the final report.
Catastrophic volcanism and its implication for agriculture in the Maya Lowlands
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Thresholds of catastrophe in the Earth system
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In-flight detection of non-catastrophic equipment failures in a space vehicle guidance- and-navigation system.
Noncatastrophic guidance and navigation equipment failures detected in flight, using two separate statistical tests
Catastrophic degradation in GaAs laser diodes
GaAs laser diodes thermal degradation, observing nature, extent and occurrence of permanent damage