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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Security Assessment of an LBP16-Protocol-Based Computer Numerical Control Machine

Subtractive manufacturing systems, specifically, computer numerical control machines, have revolutionized the manufacturing industry. Computer numerical control machining is the preferred method for producing finished parts due to its efficiency, speed and suitability for high-volume production. Securing computer numerical control machines is a priority. Compromises or disruptions of these machines can result in significant downtime, loss of productivity and financial loss. This study examines the vulnerabilities and risks associated with computer numerical control machines, in particular, systems utilizing the LBP16 protocol for controller-machine communications. The study reveals that an adversary can execute cyber-physical attacks such as sabotage and denial of service. The potential security threats emphasize the importance of implementing robust security measures to mitigate the cyber risks to computer numerical control machines.

Forihat, Yahya [Virginia Commonwealth University, ↗
DOE OSTI2022

aphBO-2GP-3B: a budgeted asynchronous parallel multi-acquisition functions for constrained Bayesian optimization on high-performing computing architecture

High-fidelity complex engineering simulations are often predictive, but also computationally expensive and often require substantial computational efforts. The mitigation of computational burden is usually enabled through parallelism in high-performance cluster (HPC) architecture. Optimization problems associated with these applications is a challenging problem due to the high computational cost of the high-fidelity simulations. In this paper, an asynchronous parallel constrained Bayesian optimization method is proposed to efficiently solve the computationally expensive simulation-based optimization problems on the HPC platform, with a budgeted computational resource, where the maximum number of simulations is a constant. The advantage of this method are three-fold. Firstly, the efficiency of the Bayesian optimization is improved, where multiple input locations are evaluated parallel in an asynchronous manner to accelerate the optimization convergence with respect to physical runtime. This efficiency feature is further improved so that when each of the inputs is finished, another input is queried without waiting for the whole batch to complete. Second, the proposed method can handle both known and unknown constraints. Third, the proposed method samples several acquisition functions based on their rewards using a modified GP-Hedge scheme. The proposed framework is termed aphBO-2GP-3B, which means asynchronous parallel hedge Bayesian optimization with two Gaussian processes and three batches. The numerical performance of the proposed framework aphBO-2GP-3B is comprehensively benchmarked using 16 numerical examples, compared against other 6 parallel Bayesian optimization variants and 1 parallel Monte Carlo as a baseline, and demonstrated using two real-world high-fidelity expensive industrial applications. The first engineering application is based on finite element analysis (FEA) and the second one is based on computational fluid dynamics (CFD) simulations.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2021

The effect of WAAM process parameters on process conditions and production metrics in the fabrication of single-pass multi-layer wall artifacts

The present work seeks to understand the impact of varying dwell time and input deposition power on part quality and overall production time for wire arc additive manufacturing. In this work, multi-layer wall geometries were deposited under different input power conditions without affecting the material deposition rate by setting traverse speed and wire feed speed constant and varying the contact tip-to-workpiece distance and the deposition power settings. Current and voltage data and optical imaging of the deposition zone were captured in situ, and wall geometry was characterized using laser scanning, so to understand the applicability of these methods for determining part height in situ. Furthermore, the present results demonstrate that alternating dwell times with lower input deposition power can result in significantly reduced overall production time and minimal material underbuilding, despite increased deposition geometry width. Furthermore, it is shown that while elimination of process dwell results in severe underbuilding of the deposition, it also yields the highest production rate for a hybrid-finished (e.g., deposited, machined) wall in terms of mm in build direction per minute and the highest buy-to-fly ratio.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Embedding ceramic components in metal structures with hybrid directed energy deposition

The combined benefit of both additive and subtractive manufacturing within the same gantry system enables hybrid directed energy deposition to create complex geometries with smooth surface finish and superior dimensional accuracy. Moreover, with layer-by-layer access to the structure during both the addition and subtraction of material, the insertion of components is now possible, assuming the components can survive the high temperatures associated with the subsequent metal deposition. Ceramic inserts are of interest for a variety of reasons including (1) to create complex interwoven ductile/brittle composites for ballistics or high-temperature applications or (2) to integrate high-temperature strain or temperature sensors protected within ceramic substrate subsumed into a larger metal structure. Here, in this work, stainless steel substrates were machined to create an internal cavity for the insertion of a ceramic component. During the investigation of several different over-the-ceramic deposition strategies, components were inserted, and different process sequences were allowed to continue to envelop the inserted ceramic with varying success. Unmelted powder was used to serve both as a thermal buffer and to provide a flush surface upon which the laser cladding could continue. Subsequent depositions were attempted with both dry and wet powder (addition of machining coolant to wet). The wet powder has previously been demonstrated to not significantly impact the mechanical properties of a final structure and provided a thermal barrier to protect the ceramic piece from the extreme temperatures of the final metal deposition. The wetting of the powder provided stability and minimized displacement caused by the powder flow from the laser cladding head. Finally, the use of an oblique angle for laser cladding allowed for the redirection of some fraction of the introduced thermal energy away from the ceramic component and, consequently, improved the survival of the ceramic inserts. With this combination of techniques, ceramic inserts survived full embedding within a 3D-printed stainless steel structure.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Influence of printing parameters on the mechanical behavior of 3D-printed SS316L parts manufactured using laser hot wire directed energy deposition

Hybrid manufacturing combines the simultaneous benefits of additive manufacturing (complex geometries, part consolidation, and mass customization) with the advantages of subtractive manufacturing (superior surface finish and enhanced dimensional accuracies) by integrating a suite of complementary traditional processes into a base platform of additive manufacturing. The use of hybrid technology has grown in recent years given its capabilities on repairing metallic structures, producing parts with conformal cooling features, and manufacturing functionally graded products. These kinds of capabilities are of great interest to the medical implant, energy, automotive, maritime, and aerospace industry sectors, among many other fields. This work investigated the mechanical properties of stainless steel (SS) 316L as a function of different tool paths strategies using an integrated 5-axis CNC hybrid Mazak system with a laser hot wire deposition system (LHWDS). This study includes the evaluation of different printing parameters and their impact on the quality of the printed bead as well as the incorporation of a structure–property material relationship based on the mechanical performance of the manufactured coupons.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Using GANs to predict milling stability from limited data

Milling is a key manufacturing process that requires the selection of operating parameters that provide efficient performance. However, the presence of chatter, a self-excited vibration causing poor surface finish and potential damage to the machine and cutting tool, makes it challenging to select the appropriate parameters. To predict chatter, stability maps are commonly used, but their generation requires expensive data, making it difficult to employ these maps in industry. Therefore, there is a pressing need for an approach that can accurately predict stability maps using limited experimental data. This study introduces the new Encoder GAN (EGAN) approach based on Generative Adversarial Networks (GANs) that predicts stability maps using limited experimental data. The approach consists of the encoder, generator, and discriminator subnetworks and uses the trained encoder and generator to predict the target stability map. This versatile method can be applied to various tool setups and can accurately predict stability maps with limited experimental data (five to 10 cutting tests) even when there is little information available for unknown parameters. In conclusion, the study evaluates the proposed approach using both numerical data and experiments and demonstrates its superior performance compared to state-of-the-art benchmarks.

42 ENGINEERING↗
DOE OSTI2023

Impact of lowering potassium contamination in liquid scintillation cocktails for ultra-sensitive radiation detection

Intrinsic 40 K radioactive backgrounds from impurities of natural K in liquid scintillation cocktails have previously been demonstrated to limit their use in ultra-sensitive applications. Here, this work explores two methodologies in parallel for the reduction of 40 K backgrounds in the cocktails, and lays the groundwork for use in ultra-sensitive applications. In one method, alternative low-K liquid scintillation matrix constituents were identified and in the other, a simple purification method for single components and finished cocktails was developed. Both methods were verified via ICP-MS analysis. Liquid scintillation counting of selected purified cocktails demonstrated background reduction, improved stability, and enhanced performance. The best performing purified cocktail was also counted on a custom-built ultra-low background liquid scintillation counter, with results below the detector background.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2022

Impact of Gold Thickness on Interfacial Evolution and Subsequent Embrittlement of Tin–Lead Solder Joints

Although gold remains a preferred surface finish for components used in high-reliability electronics, rapid developments in this area have left a gap in the fundamental understanding of solder joint gold (Au) embrittlement. Furthermore, as electronic designs scale down in size, the effect of Au content is not well understood on increasingly smaller solder interconnections. As a result, previous findings may have limited applicability. The current study focused on addressing these gaps by investigating the interfacial microstructure that evolves in 63Sn-37Pb solder joints as a function of Au layer thickness. Those findings were correlated to the mechanical performance of the solder joints. Increasing the initial Au concentration decreased the mechanical strength of a joint, but only to a limited degree. Kirkendall voids were the primary contributor to low-strength joints, while brittle fracture within the intermetallic compounds (IMC) layers is less of a factor. The Au embrittlement mechanism appears to be self-limiting, but only once mechanical integrity is degraded. Sufficient void evolution prevents continued diffusion from the remaining Au.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Experimental Evaluation of Interfacial Bonding Strength Between 304 Stainless Steel Substrate and Electrodeposited Nickel Coating Using Mesoscale Mechanical Testing Methods

Electrodeposition is a commonly used method for depositing a metal layer on a metallic substrate, to provide a decorative finish or for functional purposes including wear and corrosion resistance. The interfacial bonding strength is a critical factor in determining the quality of electrodeposition, as it ensures the adhesion of the deposited layer to the substrate. Despite its importance, there has not previously been a suitable mechanical testing method to quantitatively characterize the bonding strength between the electrodeposited layers and the substrate, due to the high strength of the materials and to restrictions imposed by the geometry (due to the small thickness of the plating layer) to manufacture tensile bars. In this study, we introduce a novel mesoscale mechanical testing method to overcome these limitations. This technique was applied to assess the bonding strength between a 304 stainless steel (SS) substrate and electrodeposited nickel with three different plating formulae (nickel sulfamate, Watts bath, and hard nickel). The thickness of the pure nickel coatings achieved for each of the three electrolyte solutions was approximately 1 mm on each side of the substrate. Mesoscale tensile bars of 1 mm length were manufactured by a femtosecond laser, with the material interface at the center of the gauge section, and then tensile-tested with digital image correlation. Further, the results proved that the electrodeposition technique is able to produce a very high bonding strength that is close to the yield strength of both the substrate material and the electrodeposited nickel layer. Additionally, in the case of the Watts bath formula, the interfacial bonding strength between the SS 304 and electrodeposited nickel can exceed that of the nickel layer. This method is expected to be useful for quantifying the interfacial bonding strength in numerous applications.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Recent developments in mathematical aspects of relativistic fluids

Abstract We review some recent developments in mathematical aspects of relativistic fluids. The goal is to provide a quick entry point to some research topics of current interest that is accessible to graduate students and researchers from adjacent fields, as well as to researches working on broader aspects of relativistic fluid dynamics interested in its mathematical formalism. Instead of complete proofs, which can be found in the published literature, here we focus on the proofs’ main ideas and key concepts. After an introduction to the relativistic Euler equations, we cover the following topics: a new wave-transport formulation of the relativistic Euler equations tailored to applications; the problem of shock formation for relativistic Euler; rough (i.e., low-regularity) solutions to the relativistic Euler equations; the relativistic Euler equations with a physical vacuum boundary; relativistic fluids with viscosity. We finish with a discussion of open problems and future directions of research.

Disconzi, Marcelo (ORCID:0000000234497778)↗
DOE OSTI2023

Ion Beam Figuring System for Synchrotron X-Ray Mirrors Achieving Sub-0.2-µrad and Sub-0.5-nm Root Mean Square

Abstract Optics with high-precision height and slope are increasingly desired in numerous industrial fields. For instance, Kirkpatrick–Baez (KB) mirrors play an important role in synchrotron X-ray applications. A KB system is composed of two aspherical, grazing-incidence mirrors used to focus an X-ray beam. The fabrication of KB mirrors is challenging due to the aspherical departure of the mirror surfaces from base geometries and the high-quality requirements for slope and height residuals. In this paper, we present the process of manufacturing an elliptical cylinder KB mirror using our in-house-developed ion beam figuring (IBF) and metrology technologies. First, the key aspects of figuring and finishing processes with IBF are illustrated in detail. The effect of positioning error on the convergence of the residual slope error is highlighted and compensated. Finally, inspection and cross-validation using different metrology instruments are performed and used as the final validation of the mirror. Results confirm that relative to the requested off-axis ellipse, the mirror has achieved 0.15-µrad root mean square (RMS) and 0.36-nm RMS residual slope and height errors, respectively, while maintaining the initial 0.3-nm RMS microroughness.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Parametrically designed surface topography on CAD models of additively manufactured lattice structures for improved design validation

Additively Manufactured (AM) lattice structures of the laser powder bed fusion (LPBF) process generally have different surface geometries depending on the overhang angle and location. This means that the design validation stage is often challenging, considering it is based on an ideal Computer Aided Design (CAD) model that is not truly representative, since the AM part will be different in terms of dimensional accuracy and surface finish. Previous studies have relied on the design of surface textures that are independent of the overhang angle, or techniques based on directly using X-ray Computed Tomography (XCT) data. In this paper, a new technique for designing surface texture on the CAD of lattices has been investigated and correlated with areal surface roughness parameters. After extracting areal surface parameters from the XCT data of the lattice, the method allowed for the design of this surface texture on the part CAD taking in consideration if its up skin or down skin, without using XCT data as the main input. By applying this method, it is possible to obtain a lattice CAD model with a designed surface texture and geometry that is more representative of the actual AM lattice. The mean deviation between the CAD model with the designed surface and the XCT was a third of the one between the XCT and the initial CAD. The proposed method allows for designing and replicating LPBF AM surfaces on the CAD of a lattice, taking into consideration the dimensional deviation caused by AM surfaces, especially on overhangs. Assuming that an LPBF AM process is stable and produces approximately the same AM surface, this method can be used to predict the geometry of a lattice, providing a cost-effective and efficient methodology that minimizes the time needed for design validation.

42 ENGINEERING↗
DOE OSTI2020

Life-cycle analysis of soybean meal, distiller-dried grains with solubles, and synthetic amino acid-based animal feeds for swine and poultry production

Swine and poultry meat production are two important sectors in the U.S. economy. They play an important role in environmental sustainability because they contribute to the greenhouse gas (GHG) emissions as the result of agricultural and production activities. To improve the sustain ability of swine and poultry meat production, it is important to understand the environmental effects and identify the key drivers of the production activities. In this work, we presented an environmental assessment of the production of swine (i.e., pork) and poultry (i.e., broiler chicken). We conducted a life-cycle analysis of formulating animal feeds using soybean meal, corn, distiller-dried grains with solubles (DDGS), and synthetic amino acids as candidate ingredients to produce swine and poultry. We evaluated GHG emissions, fossil fuel consumption, and water consumption from formulating and utilizing a variety of animal feeds based on these ingredients for swine and poultry production, using an expanded version of the Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET (R)) model. With pork and broiler chicken as the finished products, the functional unit was defined as one kg of live-weight animal at the farm gate. Feed production was the major contributor to the life-cycle GHG emissions (88 % and 91 % of the total GHG emissions for swine and poultry production, respectively) and fossil fuel consumption (79 % and 84 % of the total fossil fuel consumption for swine and poultry process, respectively). Among the four ingredient types, amino acids had the biggest GHG emission footprint; however, DDGS had the largest effect on increasing GHG emissions of swine and poultry production.

animal feed production↗
DOE OSTI2020

Superconductivity in dilute SrTiO 3 : A review

Doped SrTiO 3 , one of the most dilute bulk systems to display superconductivity, is perhaps the first example of an unconventional superconductor, as it does not fit into the standard BCS paradigm. More than five decades of research has revealed a rich temperature-carrier concentration phase diagram that showcases a superconducting dome, proximity to a putative quantum critical point, Lifshitz transitions, a multi-gap pairing state and unusual normal-state transport properties. Research has also extended beyond bulk SrTiO 3 , ushering the new field of SrTiO 3 -based heterostructures. Because many of these themes are also featured in other quantum materials of contemporary interest, recent years have seen renewed interest in SrTiO 3 . Here, we review the challenges and recent progress in elucidating the superconducting state of this model system. At the same time that its extreme dilution requires to revisit several of the approximations that constitute the successful Migdal–Eliashberg description of electron–phonon superconductivity, including the suppression of the Coulomb repulsion via the Tolmachev–Anderson–Morel mechanism, it opens interesting routes for alternative pairing mechanisms whose applicability remains under debate. For instance, pairing mechanisms involving longitudinal optical phonons have to overcome the hurdles created by the anti-adiabatic nature of the pairing interaction, whereas mechanisms that rely on the soft transverse optical phonons associated with incipient ferroelectricity face challenges related to the nature of the electron–phonon coupling. Proposals in which pairing is mediated by plasmons or promoted locally by defects are also discussed. In conclusion, we finish by surveying the existing evidence for multi-band superconductivity and outlining promising directions that can potentially shed new light on the rich problem of superconductivity in SrTiO 3 .

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Low-frequency and Moiré–Floquet engineering: A review

Highlights: • Review of theoretical and experimental advances in Floquet engineering. • Review of theories to derive effective Floquet Hamiltonians, with a focus on the low-frequency regime. • Review of the theoretical effects of light in Moiré materials. We review recent work on low-frequency Floquet engineering and its application to quantum materials driven by light, focusing on van der Waals systems hosting Moiré superlattices. These non-equilibrium systems combine the twist-angle sensitivity of the band structure with the flexibility of light drives. The frequency, amplitude, and polarization of light can be tuned in experimental setups, leading to platforms with on-demand properties. First, we review recent theoretical developments to derive effective Floquet Hamiltonians, emphasizing the low-frequency regime. We then review applications of some of these theories to study twisted graphene and transition metal dichalcogenide systems irradiated by light in free space and inside a waveguide. We study the changes induced in the quasienergies and steady-states, which can lead to topological transitions. Next, we consider van der Waals magnetic materials driven by low-frequency light pulses in resonance with the phonons. We discuss the phonon dynamics induced by the light and the resulting magnetic transitions from a Floquet perspective. We finish by outlining new directions for Moiré–Floquet engineering in the low-frequency regime and their relevance for technological applications.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2021

The repulsive Casimir-type forces in binary mixture of weakly interacting Bose–Einstein condensates gases

Highlights: • The equations of the state of a binary mixture weakly interacting Bose gases are established based on the Lagrangian of the system. • The formulae of the Casimir-type energy and the resulting Casimir-type force are produced from the quantum part of the grand canonical energy. • The results for the Casimir-type effect in the one-field case can be re-obtained by using the results of the two-field case. Within the framework of the quantum field theory (QFT) in the one-loop approximation, we investigate the Casimir-type effect in a mixture of two-component weakly interacting Bose-Einstein condensates (BECs) gases confined between two parallel plates at zero temperature. The Casimir-type forces in the miscible state of BECs for different boundary conditions (BCs) are discovered and compared to each other. The repulsive nature of the Casimir-type force in BECs is defined for the first time. Our calculations are finished in both grand canonical ensemble (GCE) and canonical ensemble (CE).

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

On silica's roles in controlling americium migration in contaminated sediments

Two studies in the early 1980s described the leaching behavior of americium (Am) disposed as part of acidic high-salt processing wastes from the Hanford Site’s Plutonium Finishing Plant to nearby ground sediments. Here these batch leach experiments showed that the Am concentrations followed a linear log [Am] versus pH relationship with a slope of –1. Column leach experiments in the second study, however, did not follow this relationship and only ~30% of the americium desorbed even after extensive column leaching. Here, the 1980s research is re-examined along with previously unpublished information and, in light of recent published work, a plausible mechanism is proposed to explain these phenomena. Amorphous silica in the contaminated sediments is postulated to be the substrate responsible for both the exchangeable Am available for leaching and the retained low-leachable Am made evident in the column leach experiments. The exchangeable Am 3+ in the contaminated sediment leach experiments behaves with pH dependence similar to that observed for uptake onto amorphous silica of sodium (Na + ), calcium (Ca 2+ ), barium (Ba 2+ ), cadmium (Cd 2+ ), uranyl (UO 2 2+ ), ferric (Fe 3+ ), chromic (Cr 3+ ), cupric (Cu 2+ ), plumbous (Pb 2+ ), uranium(IV) (U 4+ ), plutonium(IV) (Pu 4+ ), zirconium (Zr 4+ ), analogue lanthanide (gadolinium, Gd 3+ , europium, Eu 3+ , and lutetium, Lu 3+ ) and curium (Cm 3+ ) ions as well as other studies with Am 3+ . Correspondingly, the residual low-leachable Am 3+ revealed in the column leach experiments is attributed to incorporation of Am 3+ within amorphous silica by dynamic Am 3+ sorption and silica precipitation processes.

58 GEOSCIENCES↗