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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Cross-cutting strategies to lower electricity use of miscellaneous electric loads in the domestic sector

Miscellaneous Electric Loads (MELs) account for roughly one quarter of building electricity use in most developed countries. A product-specific approach to lowering MELs electricity use in this category takes too long and costs too much because there are so many MELs, each providing unique services. An alternative approach focusing on key functionalities was therefore explored. These functionalities include: (1) power management, (2) power scaling, and (3) power conversion. Cross-cutting efficiency improvements to these functionalities can be incorporated into broad categories of MELs, thus saving electricity and lowering costs. Even though the population of MELs is diverse and rapidly evolving, major technical opportunities exist to improve their efficiency in these functionalities. Research into energy-saving solutions within the cross-cutting technologies will probably have larger savings than focusing on single products.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2018

Algebraic cutting equations

The cutting equations are diagrammatic identities that are used to prove perturbative unitarity in quantum field theory. In this paper, we derive algebraic, upgraded versions of them. Differently from the diagrammatic versions, the algebraic identities also holds for propagators with arbitrary, nonvanishing widths. In particular, the cut propagators do not need to vanish off shell. The new approach provides a framework to address unsolved problems of perturbative quantum field theory and a tool to investigate perturbative unitarity in higher-derivative theories that are relevant to the problem of quantum gravity, such as the Lee–Wick models and the fakeon models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Energy system analysis of cutting off Russian gas supply to the European Union

The reduction of European Union's pipeline gas imports from Russia as a consequence of the Russian war against Ukraine has had severe economy-wide implications for the EU. Using a multisector integrated assessment model (GCAM), we find that a potential complete cut-off of Russian pipeline gas exports to the EU unevenly impacts the energy mix, prices, and trade flows of different subregions within the EU, depending on their access to alternative gas pipelines and LNG infrastructure. Moreover, there are also large changes in the volume and geographical distribution of global gas infrastructure capacity additions and stranded assets. Our results show that by significantly reducing demand for natural gas, the EU Fit-for-55 policy framework already improves resilience against a complete and persistent cut-off of Russian pipeline gas. However, further improvements in energy efficiency and renewable targets could further soften impacts, while bringing climate objectives closer in sight.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2022

Use of a silver-based sanitizer to accelerate Escherichia coli die-off on fresh-cut lettuce and maintain produce quality during cold storage: Laboratory and pilot-plant scale tests

Outbreaks and product recalls involving romaine and iceberg lettuce are frequently reported in the United States. Novel technologies are needed to inactivate pathogens without compromising product quality and shelf life. In this study, the effects of a process aid composed of silver dihydrogen citrate, glycerin, and lactic acid (SGL) on Escherichia coli and Listeria monocytogenes concentrations on lettuce immediately after washing and during cold storage were evaluated. Sensory and quality attributes of fresh-cut iceberg lettuce were also evaluated. Laboratory results indicated that application of SGL solution for 30 s as a first step in the washing process resulted in a 3.15 log reduction in E. coli O157:H7 immediately after washing. For E. coli O157:H7 a significant difference between SGL treatment and all other treatments was maintained until day 7. On day zero, SGL led to a 2.94 log reduction of L. monocytogenes. However, there was no significant difference between treatments with or without SGL regardless of storage time. Pilot-plant results showed that samples receiving SGL spray followed by chlorinated flume wash exhibited a greater reduction (1.48 log) in nonpathogenic E. coli populations at the end of shelf life than other treatments (p < 0.05). Additional pilot plant tests were conducted to investigate the hypothesis that SGL residues could continue to impact microbial survival on the final washed lettuce. Results show that pathogens introduced subsequent to flume washing of lettuce pretreated with SGL solution were not affected by antimicrobial residues. Here, the final quality and shelf life of flume washed lettuce were also unaffected by pretreatment with SGL. In conclusion, the results of this study demonstrate that this new technology has the potential to accelerate E. coli die-off on fresh-cut lettuce during cold storage and improve product safety, while not affecting quality throughout the shelf life of the finished products.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

Improving thermal and electrochemical performances of LiCoO{sub 2} cathode at high cut-off charge potentials by MF{sub 3} (M=Ce, Al) coating

Highlights: • Fluoride metal is successfully coated on the surface of LiCoO{sub 2}. • Easy and scalable method is adopted for the synthesis of coated-LiCoO{sub 2}. • Appropriate amount of AlF{sub 3} or CeF{sub 3} is beneficial to reduce cation disorder. • The electrochemical performances of coated LiCoO{sub 2} is significantly enhanced at higher potential (cycling efficiency and reversible capacity). • The coated cathode exhibits excellent thermal stability highlighted by calorimetric technique. - Abstract: Surface coating of LiCoO{sub 2} remained one of the efficient methods to enhance its electrochemical and thermal performances, especially at high cut-off potential. In this work, MF{sub 3} (M = Ce, Al) coated LiCoO{sub 2} was synthesized via co-precipitation method followed by a solid state reaction at 400 °C. The morphology and structure of the modified cathode material were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the fluoride compound MF{sub 3} is successfully coated on the surface of LiCoO{sub 2} cathode particles with an average layer thickness about 12 nm and 40 nm for AlF{sub 3} and CeF{sub 3}, respectively. The electrochemical tests show that the AlF{sub 3}-coating layer significantly enhances the cycling performance of LiCoO{sub 2} cathode material, even at high cut-off potential. While the bare LiCoO{sub 2} cathode displays fast fading at 4.6 V vs. Li{sup +}/Li cutoff potential, the surface-modified electrode exhibits the great capacity of 160 mAh g{sup −1} with excellent capacity retention on several cycles. We concluded that the electrochemical and the thermal enhancement at high potential are ascribed to the presence of MF{sub 3} coating layer which prevent the side reaction during the charge discharge process, alleviate the attack by the acidic electrolyte and reduce the damage of electrode structure.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Plasmon-enhanced broad-band quantum-cutting of NaBaPO{sub 4}:Eu{sup 2+},Yb{sup 3+} phosphor decorated with Ag nano-particles

Highlights: • High quantum-cutting (QC) efficiency as 197.4% was obtained in NaBaPO{sub 4}:Eu{sup 2+},Yb{sup 3+}. • Strong and broad excitation band derived from Eu{sup 2+} was detected and analyzed. • Plasmon enhancement of broad-band QC emission was reported for the first time. - Abstract: The NaBaPO{sub 4}:Eu{sup 2+},Yb{sup 3+} quantum-cutting (QC) phosphors were prepared by the solid-state reaction. We confirm the luminescence of Yb{sup 3+} is mainly derived from QC rather than common down-conversion. The QC efficiency η{sub QE} calculated from the luminescence decay curves reached a maximum as high as 197.4%. Furthermore, the QC emission was enhanced by decorating with quasi-spherical and uniform (∼100 nm) Ag nano-particles, due to localized surface plasmon resonance. The enhancement factor reached a maximum as 1.2337.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Hybrid manufactured dynamometer for cutting force measurement

This paper describes a two-step (additive + subtractive) hybrid manufacturing approach for a laser powder bed fusion 316L stainless steel constrained-motion cutting force dynamometer (PBF CMD). The purpose of the research is to produce a near-net shape metallic dynamometer via additive manufacturing (AM) with post-processing by machining and wire-EDM to achieve the desired surface finish and performance. A cutting force comparison is presented with a commercially-available dynamometer.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Cut site preference allows influenza A virus PA-X to discriminate between host and viral mRNAs

Many viruses block host gene expression to take over the infected cell. This process, termed host shutoff, is thought to promote viral replication by preventing antiviral responses and redirecting cellular resources to viral processes. Several viruses from divergent families accomplish host shutoff through RNA degradation by endoribonucleases. However, viruses also need to ensure expression of their own genes. The influenza A virus endoribonuclease PA-X solves this problem by sparing viral mRNAs and some host RNAs necessary for viral replication. Here, to understand how PA-X distinguishes between RNAs, we characterized PA-X cut sites transcriptome-wide using 5' rapid amplification of complementary DNA ends coupled to high-throughput sequencing. This analysis, along with RNA structure predictions and validation experiments using reporters, shows that PA-Xs from multiple influenza strains preferentially cleave RNAs at GCUG tetramers in hairpin loops. Importantly, GCUG tetramers are enriched in the human but not the influenza transcriptome. Moreover, optimal PA-X cut sites inserted in the influenza A virus genome are quickly selected against during viral replication in cells. This finding suggests that PA-X evolved these cleavage characteristics to preferentially target host over viral mRNAs in a manner reminiscent of cellular self versus non-self discrimination.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

Design of weak link channel-cut crystals for fast QEXAFS monochromators

A weak link channel-cut crystal, optimized for dedicated Quick EXAFS monochromators and measurements, was designed using finite element analysis. This channel-cut crystal offers precise detuning capabilities to enable suppression of higher harmonics in the virtually monochromatic beam. It was optimized to keep the detuning stable, withstanding the mechanical load, which occurs during oscillations with up to 50 Hz. First tests at DELTA (Dortmund, Germany), proved the design.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Surface ionization waves propagating over non-planar substrates: wavy surfaces, cut-pores and droplets

Atmospheric pressure plasmas intersecting with dielectric surfaces will often transition into surface ionization waves (SIWs). Several applications of these discharges are purposely configured to be SIWs. During propagation of an SIW over a dielectric surface, the plasma charges the surface while responding to changes in geometrical and electrical material properties. This is particularly important for non-planar surfaces where polarization of the dielectric results in local electric field enhancement. In this paper, we discuss results from computational investigations of negative and positive SIWs propagating over nonplanar dielectrics in three configurations—wavy surfaces, cuts through porous materials and water droplets on flat surfaces. Here we found that negative SIWs are particularly sensitive to the electric field enhancement that occurs at the crests of non-planar surfaces. The local increase in ionization rates by the electric field enhancement can result in the SIW detaching from the surface, which produces non-uniform plasma exposure of the surface. Positive SIWs tend to adhere to the surface to a greater degree. These trends indicate that treatment of pathogen containing droplets on surfaces may be best performed by positive SIWs. The same principles apply to the surfaces cut through pores. Buried pores with small openings to the SIW may be filled by plasma by either flow of plasma into the pore (large opening) or initiated by photoionization (small opening), depending on the size of the opening compared to the Debye length.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Microfluidic delivery of cutting enzymes for fragmentation of surface-adsorbed DNA molecules

We describe a method for fragmenting, in-situ, surface-adsorbed and immobilized DNAs on polymethylmethacrylate(PMMA)-coated silicon substrates using microfluidic delivery of the cutting enzyme DNase I. Soft lithography is used to produce silicone elastomer (Sylgard 184) gratings which form microfluidic channels for delivery of the enzyme. Bovine serum albumin (BSA) is used to reduce DNase I adsorption to the walls of the microchannels and enable diffusion of the cutting enzyme to a distance of 10mm. Due to the DNAs being immobilized, the fragment order is maintained on the surface. Possible methods of preserving the order for application to sequencing are discussed.

Budassi, Julia↗
DOE OSTI2018

Substation Circuit Breaker SCADA Cut-Over

The electric power industry has a unique set of issues related to the infrastructure put in place since the 1880s. As methods of generation, delivery and protection evolve, so must the equipment used by the utility. Furthermore, the equipment in use has a finite life and must be replaced over time. The substation at which this project takes place was originally built in the 1950s, though most of the equipment had already gone through several updates. The issue presented was upgrading the Supervisory Control and Data Acquisition (SCADA) system for all the devices connected to the last SCADA system installed a few decades ago. Though the SCADA system being replaced was connected to substation transformers, breakers, disconnects, relays and other devices, the scope of this report will focus on the cut-over of a single gas circuit breaker. After connecting the circuit breaker to the new SCADA, a system and operability (SO) test would need to be designed and carried out to validate the proper function of the device before returning it to service. This report will follow the design approach, execution, testing, and troubleshooting for the substation circuit breaker SCADA cut-over.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2022

Quantum-Cutting Luminescent Coatings for High-Efficiency, Low-Cost Solar Cells (Final Technical Report)

The objective of the project is to optimize the deposition and post-deposition annealing conditions of quantum-cutting materials to enable coatings with high photoluminescence quantum yields and optimal absorption onset. These coatings will be integrated with commercial solar photovoltaic cells to enable improved power conversion efficiency, and the quantum-cutting cell stability will be ensured using industry-standard packaging methods.

14 SOLAR ENERGY↗
DOE OSTI2022

Cross-Cutting Metrology Tools for In Operando Characterization of Carrier Dynamics in Photovoltaic Devices (Final Technical Report)

Understanding the nature of recombination and its dependence on defects and interfaces is essential for engineering materials and contacts for higher V oc and photovoltaic (PV) efficiency. Time-resolved photoluminescence (TRPL) has conventionally been used to evaluate recombination, but not all materials are strongly emissive or otherwise suitable. Time-resolved terahertz spectroscopy is a pump – probe method that presents valuable complementary information, wherein an optical pump pulse photoexcites carriers within the absorber and the transient photoconductivity is probed with a terahertz pulse. Until now, experimental constraints have prohibited the use of terahertz probes to interrogate full device stacks, and measurements were instead made on exfoliated films or films grown on unconventional substrates. However, interfaces are critical to the behavior of photoexcited carriers in solar cells, and the substrates themselves often influence the film growth and bulk properties. Therefore, it is important to probe the behavior of PV absorbers as close as possible to their normal operating conditions. Here we have developed cross-cutting metrology that enable in operando characterization of carrier dynamics and recombination mechanisms in working PV devices. Through a combination of complementary non-contact TRTS and TRPL experiments and modeling, we have obtained key parameters including photoexcited carrier bulk lifetime and interface and back surface recombination velocities with greater precision and accuracy than can be achieved with conventional TRPL alone. By varying pulsed photoexcitation conditions, the contributions of interface and bulk recombination mechanisms can be determined. We have developed and refined this characterization approach by investigating CdTe PVs, which is a well-established technology but with significant margin for further improvements in efficiency. Results were published in Journal of Applied Physics (DOI: 10.1063/5.0064730) and Proceedings of the IEEE PVSC (DOI: 10.1109/PVSC43889.2021.9518559). After validating the approach, we have applied it to correlate recombination rates to processing conditions and material properties, including composition and defects as well as interfaces and surface treatments. Such feedback can inform processing and design choices to enable higher PV efficiency, not only for CdTe, but also CdSe x Te 1-x , CIGS, perovskites, kesterites, and future technologies. A perspective on predicting solar cell performance from terahertz spectroscopy was published in Advanced Energy Materials (DOI: 10.1002/aenm.202102776). The cross-cutting metrology tools developed here will enable determination of the locus and mechanism of performance-limiting recombination in thin film PV devices. This feedback can guide the engineering of PV devices with higher V oc and efficiency, thereby leading to reductions in levelized cost of electricity to meet the SunShot 2030 target of $0.03/kWh for utility-scale PV. Lower costs will enable rapid expansion of renewable electricity generation that is nearly free of carbon emissions. Reducing carbon emissions of the electricity sector is one of the most important solutions to climate change. The project’s specific focus on CdTe PV can benefit First Solar, the US company that is the global leader in CdTe technology, through both technology and workforce development.

14 SOLAR ENERGY↗
DOE OSTI2024

Sequential Monte Carlo for Cut-Bayesian Posterior Computation

We propose a sequential Monte Carlo (SMC) method to efficiently and accurately compute cut-Bayesian posterior quantities of interest, variations of standard Bayesian approaches constructed primarily to account for model misspecification. We prove finite sample concentration bounds for estimators derived from the proposed method along with a linear tempering extension and apply these results to a realistic setting where a computer model is misspecified. We then illustrate the SMC method for inference in a modular chemical reactor example that includes submodels for reaction kinetics, turbulence, mass transfer, and diffusion. The samples obtained are commensurate with a direct-sampling approach that consists of running multiple Markov chains, with computational efficiency gains using the SMC method. Overall, the SMC method presented yields a novel, rigorous approach to computing with cut-Bayesian posterior distributions.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2021

“Seeing Is Believing”—In-Depth Analysis by Co-Imaging of Periodically-Poled X-Cut Lithium Niobate Thin Films

Nonlinear and quantum optical devices based on periodically-poled thin film lithium niobate (PP-TFLN) have gained considerable interest lately, due to their significantly improved performance as compared to their bulk counterparts. Nevertheless, performance parameters such as conversion efficiency, minimum pump power, and spectral bandwidth strongly depend on the quality of the domain structure in these PP-TFLN samples, e.g., their homogeneity and duty cycle, as well as on the overlap and penetration depth of domains with the waveguide mode. Hence, in order to propose improved fabrication protocols, a profound quality control of domain structures is needed that allows quantifying and thoroughly analyzing these parameters. In this paper, we propose to combine a set of nanometer-to-micrometer-scale imaging techniques, i.e., piezoresponse force microscopy (PFM), second-harmonic generation (SHG), and Raman spectroscopy (RS), to access the relevant and crucial sample properties through cross-correlating these methods. Based on our findings, we designate SHG to be the best-suited standard imaging technique for this purpose, in particular when investigating the domain poling process in x-cut TFLNs. While PFM is excellently recommended for near-surface high-resolution imaging, RS provides thorough insights into stress and/or defect distributions, as associated with these domain structures. In this context, our work here indicates unexpectedly large signs for internal fields occurring in x-cut PP-TFLNs that are substantially larger as compared to previous observations in bulk LN.

Reitzig, Sven (ORCID:0000000286970379)↗
DOE OSTI2022

A Realistic Full-Scale 3D Modeling of Turning Using Coupled Smoothed Particle Hydrodynamics and Finite Element Method for Predicting Cutting Forces

Computational modelling is an effective technique for understanding the complex physics of machining. Large deformations, material separation, and high computational requirements are the key challenges faced while simulating machining. This work introduces a full-scale three-dimensional model of turning operations using a combined approach based on the Smoothed Particle Hydrodynamics (SPH) and Finite Element (FE) methods. By exploiting the advantages of each method, this approach leads to high-fidelity coupled SPH-FE machining models. Cutting forces and chip morphology are the primary results of interest. The machining models are validated with the results of turning experiments. Two-dimensional machining model underpredicts the cutting force and feed force by approximately 49% and 70%, respectively. Moreover, passive force cannot be predicted using the two-dimensional model. On the other hand, with the three-dimensional models developed in this manuscript, the difference between the total simulated force and experimentally measured force is ∼17%. The chip morphologies correlate with experiments in terms of the direction of the chip movement and the “long” continuous chips observed while turning Al 6061. This work expands the realm of machining simulations from two-dimensional orthogonal machining or sectional three-dimensional model to a full-scale realistic simulation. The encouraging simulation results show the potential to study more complex phenomena, such as machining stability and tool path modulation.

42 ENGINEERING↗
NASA NTRS1969

Microwave interferometer controls cutting depth of plastics

Microwave interferometer system controls the cutting of plastic materials to a prescribed depth. The interferometer is mounted on a carriage with a spindle and cutting tool. A cross slide, mounted on the carriage, allows the interferometer and cutter to move toward or away from the plastic workpiece.

Heisman, R. M.↗