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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 847 records · Page 47
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Developing Smart Building Technology Modules to Enhance Workforce Preparedness: A Case for AI-Driven Academic and Professional Education

Smart building technologies are resources that improve building energy efficiency and resilience, reduce carbon emissions, and provide load flexibility to the grid. However, in both academic curricula and building professionals’ continuing education, there is a lack of systematic instruction on methods to integrate multiple energy systems including distributed energy resources (DER), smart building technologies, AI (Artificial Intelligence) tools and key concepts, components, and controls, including “Internet of Things” (IoT) devices. In today’s dynamic workforce, this major gap in smart building technology education prevents stakeholders from being able to attract talent with an understanding and preparation to adopt smart building technologies in building design and operations. A federally funded project included a partnership between Slipstream and Texas A&M University (TAMU) to develop a semester-long smart building curriculum for engineering college students with the ability to adapt the contents for workforce development of professionals in building services. The final product consists of 16 training videos adapted for building professionals and the public. The educational content and training materials cover the benefits of building energy systems, the latest sensor technologies and IoT devices, all with a focus on smart building technologies. The key drivers are on topics related to smart building controls (i.e., energy management information systems), smart building control platforms, cybersecurity, grid-interactive-efficient buildings (GEBs), smart building control methods, and occupant-centric control. Although not explicitly included the technologies nod to the need for AI driven technologies to prepare engineers and industry professionals to be future ready. This paper describes the project approach, provides outlines of the training materials, and identifies lessons learned in creating the content for this course. The authors suggest ways to scale the instruction of smart building concepts to empower the workforce to accelerate the adoption of smart building technologies and AI-based teaching and learning in higher education and building sector.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2023

Bias-pulsed atomic layer etching of 4H-silicon carbide producing subangstrom surface roughness

A new approach to atomic layer etching (ALE) has been demonstrated, and its application to 4H-SiC is reported here. By pulsing only the DC bias for an Ar/Cl2 inductively coupled plasma-reactive ion etching system, the etch cycle duration is reduced by more than an order of magnitude relative to conventional ALE processes. Gas flows are not changed throughout the ALE process. With this process protocol, we achieved an etch rate of 2.48±0.09 Å/cycle with 6 s cycles, an RMS surface roughness (Rq) of 0.83±0.08 Å, and an ALE synergy value of S = 99%. The parameters explored within this ALE process demonstrate effective subangstrom smoothening of 4H-SiC surfaces and is well-suited for a variety of classical and quantum device nanofabrication.

42 ENGINEERING↗
DOE OSTI2024

Impact Analysis of High-Altitude Electromagnetic Pulse Coupling Effects on Power Grid Protection Relays

Protection relays are important equipment used for protection, control, and metering functions in the power grid. These relays are used to protect critical and difficult-to-replace equipment, like generators, transformers, and capacitor banks. Once the protection devices are disturbed or damaged, a high risk of power generation interruption occurs. Therefore, it is important and necessary to study the relay’s immunity to electromagnetic pulse (EMP) events. As a preliminary step toward empirical experimentation on actual equipment, this manuscript outlines an economical and efficient methodology for evaluating the impact of an EMP. An impedance measurement strategy was employed to model the equipment, setting the stage for subsequent immunity analyses. These analyses included the pulse current injection (PCI) method, which utilized an injecting probe to introduce the transient, and frequency domain electromagnetic (FEKO) simulation, which integrated electromagnetic coupling effects into the transient simulation. The impedance measurement and simulation results in this paper provide a reliable basis for gauging equipment performance in the face of HEMP threats. The results obtained using the PCI and FEKO simulations demonstrated the performance of different port responses under a high-altitude EMP, indicating the requirement for some protection to ensure the reliable operation of relays.

42 ENGINEERING↗
DOE OSTI2025

Colossal Terahertz Emission with Ultrafast Tunability Based on Van der Waals Ferroelectric NbOI 2

Abstract Terahertz (THz) technology is critical for quantum material physics, biomedical imaging, ultrafast electronics, and next‐generation wireless communications. However, standing in the way of widespread applications is the scarcity of efficient ultrafast THz sources with on‐demand fast modulation and easy on‐chip integration capability. Here the discovery of colossal THz emission is reported from a van der Waals (vdW) ferroelectric semiconductor NbOI 2 . Using THz emission spectroscopy, a THz generation efficiency an order of magnitude higher than that of ZnTe, a standard nonlinear crystal for ultrafast THz generation is observed. The underlying generation mechanisms associated are further uncovered with its large ferroelectric polarization by studying the THz emission dependence on excitation wavelength, incident polarization, and fluence. Moreover, the ultrafast coherent amplification and annihilation of the THz emission and associated coherent phonon oscillations by employing a double‐pump scheme are demonstrated. These findings combined with first‐principles calculations, inform a new understanding of the THz light–matter interaction in emergent vdW ferroelectrics and pave the way to develop high‐performance THz devices on them for quantum materials sensing and ultrafast electronics.

Subedi, Sujan [Department of Materials Science and↗
DOE OSTI2021

Recent developments on 2D magnetic materials: challenges and opportunities

The emergence of two-dimensional (2D) magnetic materials exhibiting strong magnetization at ultrathin limits above room temperature are promising for miniaturization of devices beyond Moore’s law for future energy efficient nano-electronic devices. Here, the current status, different mechanisms for the existence of magnetism, spin current injection and other magnetic properties of monolayer to few-layers of various 2D magnetic materials are reviewed. Some of the promising applications of these materials are spintronics devices such as spin valves, spin tunnel field-effect transistors, and spin filtering magnetic tunnel junctions. Due to the tunable electronic properties of these 2D materials, it's quite interesting to inject the spin current with suitable ferromagnetic contacts. For instance,black phosphorus is a layered material with a small Schottky barrier height capable of injecting spin current. This review includes many recently explored 2D magnetic materials ranging from exfoliated 2D crystals to CVD grown materials from single to several layers, demonstrating tunable layer dependent magnetic properties. We also explore some of the promising theoretical study based on 2D magnetic compounds such as 2D alkali-based chromium chalcogenides, which shows ferromagnetic as well as semiconducting behavior. The layer-dependent magnetic ordering has been observed in layered compounds like 1T-CrTe 2 , VSe 2 , CrI 3 , and Fe 3 GeTe 2 , which have great potential for the future applications in magnetic based electronic devices. Finally, we emphasize the challenges, opportunities and future directions of the 2D magnetic materials, where new discoveries might have outstanding impact in transformational scientific breakthroughs towards memory, spintronics, optoelectronics and other multifunctional device applications.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Will Stochastic Devices Play Nice With Others in Neuromorphic Hardware?: There’s More to a Probabilistic System Than Noisy Devices

Achieving brain-like efficiency in computing requires a co-design between the development of neural algorithms, brain-inspired circuit design, and careful consideration of how to use emerging devices. The recognition that leveraging device-level noise as a source of controlled stochasticity represents an exciting prospect of achieving brain-like capabilities in probabilistic neural algorithms, but the reality of integrating stochastic devices with deterministic devices in an already-challenging neuromorphic circuit design process is formidable. Here, we explore how the brain combines different signaling modalities into its neural circuits as well as consider the implications of more tightly integrated stochastic, analog, and digital circuits. Further, by acknowledging that a fully CMOS implementation is the appropriate baseline, we conclude that if mixing modalities is going to be successful for neuromorphic computing, it will be critical that device choices consider strengths and limitations at the overall circuit level.

42 ENGINEERING↗
DOE OSTI2024

Postfault Operation of Three-Level Inverter Driven Six-Phase PMSM With Enhanced Torque–Speed Region

This article presents an open-switch postfault operational technique with enhanced torque–speed region for three-level (3L) active neutral point clamped (ANPC) inverter-driven symmetrical six-phase (SSP) permanent magnet synchronous machines (PMSMs). Maximum torque (MT), minimum loss (ML), and single three-phase (STP) operations are commonly used for the postfault operations of six-phase drives. The maximum possible torque and speed in these operations are generally limited by voltage, current ratings, and the neutral point configuration of the motor. To enhance the postfault torque and speed operating region, the torque and speed limits in different postfault operational techniques are determined based on the voltage, current constraints, and neutral point configuration of the SSP-PMSM. In this work, a unified postfault operation is proposed that increases the postfault operational limits by combining MT, ML, and STP operations and modifying the neutral point configuration of the SSP-PMSM. In addition, a technique is also presented that modifies the pulsewidth modulation technique to enable full torque operation below 0.5 p.u. speed. The proposed postfault operational technique enables full-speed (1 p.u.) operation by operating in STP mode and full torque operation (1 p.u.) below 0.5 p.u. speed. Furthermore, the postfault operational technique is experimentally validated using a Gallium Nitride (GaN) device-based3L-ANPC inverter-driven SSP-PMSM.

42 ENGINEERING↗
DOE OSTI2020

Controlled removal of hydrogen atoms from H-terminated silicon surfaces

The controlled formation of dangling bond structures on a H-terminated silicon surface is the first step in an atomically precise method of fabrication of silicon quantum electronic devices. An ultrahigh vacuum scanning tunneling microscope (STM) tip is used to selectively desorb hydrogen atoms from a Si(100)-2x1:H surface by injecting electrons with the sample held at a positive bias voltage. The authors propose a lithography method that allows the STM to operate under negative bias imaging conditions and simultaneously desorb H atoms as required. A high frequency signal is added to the negative bias voltage to deliver the required energy for hydrogen removal. The resulting current at this frequency and its harmonics are filtered to minimize their effect on the operation of the STM’s feedback control loop. The authors show that the chance of tip-sample crash during the lithography process is reduced by employing this method. They also demonstrate that this approach offers a significant potential for controlled and precise removal of H atoms from a H-terminated silicon surface and thus may be used for the fabrication of practical silicon-based atomic-scale devices.

42 ENGINEERING↗
DOE OSTI2020

Methods and systems for authenticating identity

Systems and methods are disclosed that provide for secure communications between a user device and an authentication system. The systems and methods create a dynamic identification for the device that is stored in both the device and authentication system.

42 ENGINEERING↗
DOE OSTI2023

Electrochemical Reduction of Flue Gas Carbon Dioxide to Commercially Viable C2-C4 Products (Final Report)

This is the final scientific/technical report for a DOE project focused on the electrochemical conversion of CO 2 in non-aqueous solvents to novel products. Electrochemical reduction of CO 2 provides an attractive route to produce valuable fuels and chemicals that can simultaneously lower greenhouse gas emissions when powered by renewable electricity. While recent technological advances have shown the feasibility of industrial CO 2 electroreduction, many challenges remain to improve this technology and expand the list of economically viable products. The vast majority of electrochemical CO 2 reduction research has been conducted in aqueous media under neutral to alkaline conditions, leading to commonly reported products including carbon monoxide, formic acid, methane, methanol, ethylene, acetic acid, and ethanol. In comparison, non-aqueous media for CO 2 reduction has been underexplored but represents a possible avenue to yield new products and improved operating conditions. The aim of the project was to convert waste CO 2 in the form of flue gas to a multicarbon C2 - C4 chemical product in a reactor designed to achieve economically competitive values of current density and selectivity. The project strived to advance the technology readiness of an electrochemical CO 2 reduction process in alcohol solvents from the proof-of-concept stage to a device capable of meeting performance metrics for commercial viability. In the initial plan, the University of Louisville researchers were to focus on investigating the electrochemical process and improving the faradaic efficiency for novel C2 – C4 species, while also working on a parallel effort to build a practical electrolysis reactor to markedly increase the CO 2 reduction current density. The reactor development effort also aimed to engineer a dual-electrolyte feed strategy with non-aqueous catholyte and aqueous anolyte to promote water oxidation as the coupling anodic half-reaction to enable a sustainable and economical overall process. At the outset, the University of North Dakota was to investigate the feasibility of operating directly from coal-derived flue gas without separate capture and purification. The research team sought to determine impurity effects and test mitigation strategies, as well as engineer the gaseous feed system for high reactor tolerance to lower CO 2 concentration. In the last half year of the project, the focus was planned to shift to integrating the advances in the catalysis, electrochemical conditions, reactor design, and flue gas compatibility into a fully functional device and improve it for maximum current density and faradaic efficiency for C2 – C4 species. Knowledge of the full system components, constraints, and maximum performance was then to be used as the basis for a thorough technoeconomic analysis (TEA) and life cycle analysis (LCA) at the end of the project.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2022

Adaptive Fault Detection Based on Neural Networks and Multiple Sampling Points for Distribution Networks and Microgrids

Smart networks such as microgrid (MG) and active distribution networks (ADN) have been recently playing an important role in power system operation. The design and implementation of appropriate protection systems for such networks must be addressed, which imposes new technical challenges. This paper presents the implementation and validation aspects of an adaptive fault detection strategy based on neural networks (NNs) and multiple sampling points for ADN and MG. The solution is implemented on an edge device. Artificial NNs are used to derive a data-driven model that uses only local measurements to detect fault states of the network without the need for communication infrastructure. Multiple sampling points are used to derive a data-driven model, which allows the generalization considering the implementation in physical systems. The adaptive fault detector model is implemented on a Jetson Nano system, which is a single-board computer (SBC) with a small Graphic Processing Unit (GPU) intended to run machine learning loads at the edge. The proposed method is tested in a physical, real-life, low-voltage network located at Universidad del Norte, Colombia. This testing network is based on the IEEE-13 Node Test Feeder scaled down to 220 V. The validation in a simulation environment shows the accuracy and dependability above 99.6%, while the real-time tests show the accuracy and dependability of 95.5% and 100%, respectively. Without hard-to-derive parameters, the easy-to-implement embedded model highlights the potential for real-life applications.

42 ENGINEERING↗
DOE OSTI2025

Tunneling Barrier-Integrated Gold Nanofilms for Negative Strain Gauging with Near-Zero Energy Consumption

Wireless strain sensors with minimal power needs are essential for long-term monitoring in energy-limited environments. We present a soft tunneling barrier-integrated gold thin film for negative strain sensing with near-zero energy consumption. The device features a strain-induced transition from an insulating to a metallic state, increasing conductivity by 9 orders of magnitude under a controlled strain. It consists of Au-PDMS-Au nanofilm layers, where the Au structures are near the percolation threshold and the PDMS layer acts as a tunneling barrier. Under strain, thinning due to the Poisson effect lowers the barrier’s potential height, enabling electron tunneling and forming an electrical path. Further, with a standby power consumption of ~10 –5 mW over 10 6 times lower than conventional sensors (~12.5 mW), this device is ideal for real-time, long-term stationary structural monitoring in multiple locations.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2021

High efficiency compact microwave sources using electrostatic potential depression

In this article, we report theoretical and design studies on the application of an electrostatic potential depression (EPD) on two types of traditional microwave sources, the klystron and the inductive output tube (IOT), both operating in the UHF band. Additionally, the EPD is implemented by a section of the metallic beam pipe on which a direct current (dc) negative high voltage is applied. Inside the EPD section, the modulated electron beam develops into bunches over a very short longitudinal distance, indicating a possible design approach for a compact device. With the application of an EPD, the peak value of the first harmonic current in a microwave tube can be further increased compared to that in a conventional design, suggesting higher circuit efficiency. As the electron beam leaves the EPD section, the reacceleration of the beam provides a longitudinal cooling effect. With the addition of an EPD, circuit power extraction efficiency above 80% is achieved in both the modified design of the IOT and the novel conceptual circuit design of the klystron.

42 ENGINEERING↗
DOE OSTI2025

Non-Markovian dynamics of a superconducting qubit in a phononic bandgap

Reducing decoherence in quantum computers rapidly decreases the overhead needed to construct a logical qubit from physical qubits. In solid-state systems, a class of defects known as two-level systems is a major source of decoherence. Currently, superconducting qubit experiments reduce dissipation due to the two-level systems by using large device dimensions. However, this approach only provides partial protection and results in a trade-off between qubit size and dissipation. In this work, we instead engineer the interactions between a qubit and the surrounding two-level systems using phononics. We fabricate a superconducting qubit on a phononic-bandgap metamaterial that suppresses phonon emission mediated by the two-level systems. The phonon-engineered bath of two-level systems shows increased lifetime and affects the thermalization dynamics of the qubit. Within the phononic bandgap, we observe the emergence of a non-Markovian qubit behaviour. Further, combined with qubit miniaturization, our approach could substantially extend the qubit relaxation times.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Synthetic antiferromagnet-based spin Josephson oscillator

Two easy-plane ferromagnetic layers, antiferromagnetically coupled through a thin nonmagnetic metal layer, form the magnetic analog of a Josephson junction. Additionally, a current driven spin chemical potential drives a 2π precession of the in-plane magnetization of each ferromagnet. The participation of the full magnetic moment in the 2π precession maximizes the giant magnetoresistance and the ac output power. The frequency can be continuously tuned by a dc bias. An applied ac bias results in a time-averaged magnetoresistance with Shapiro-like steps. The multistate mode-locking behavior exhibited by the Shapiro steps may be exploited for applications such as microwave detectors and neuromorphic computing. They may also serve as an experimental signature of spin superfluidity.

42 ENGINEERING↗
DOE OSTI2022

Computational Elucidation of Mechanical Degradation in NMC Cathodes: Impact on Cell Performance

Next-generation lithium ion batteries are expected to demonstrate superior energy and power density with longer cycle life for successful electrification of the automobile, aviation, and marine industries. Adoption of lithium metal anodes with solid electrolytes can help to achieve that goal given that the dendrite-related issues are solved eventually. Another possibility is to use Ni-rich high-capacity NMC cathode materials with liquid and/or solid electrolytes, which presently experiences rapid capacity fade while charged to higher voltages. Several mechanical and chemical degradation mechanisms are active within these NMC-based cathode particles. Recent experimental research activities attempted to correlate the mechanical damage with the capacity fade experienced by Ni-rich LiNi x Mn y Co z O 2 (x+y+z = 1) (NMC) cathodes. Here, a computational framework is developed in this study capable of quantifying the evolution of inter primary particle and cathode/electrolyte interfacial fracture experienced by the poly- and single-crystalline NMC cathodes during charge/discharge operation. Influences of mechanical degradation on the overall cell capacity, while operating with liquid and/or solid electrolytes, are successfully characterized. Decreasing the size of the cathode primary particles, or the size of the single-crystalline cathodes, can mitigate the overall mechanical degradation, and subsequent capacity fade, experienced by NMC cathodes. The developed theoretical methodology can help the engineers and scientists to better understand the mechanical degradation mechanism prevalent in Ni-rich NMC cathodes and build superior lithium ion-based energy storage devices for the application in next-generation devices.

25 ENERGY STORAGE↗
DOE OSTI2025

Low-cost buffer storage for solar industrial steam applications

Motivation and importance: Many industrial process heat consumers operate throughout the day, and deep decarbonization with solar energy requires thermal energy storage. Thermal energy storage provides an additional operational benefit of firm delivery of steam – essential to reducing the risk of costly production interruptions. The group of process heat consumers that use steam for biofuels production for the California transportation fuels market is incentivized through the Low Carbon Fuel Standard (LCFS) to reduce their carbon intensity through the use of solar steam. Examples include ethanol and dimethyl ether production. The production of these and other fuels involves distillation driven by steam reboilers with steam pressures in the range 100-280 psig. These pressures can be delivered from the type of thermal energy storage that has been the focus of this project – a steam accumulator Sunvapor, Inc. (SVI) calls a “Bullet Steam Accumulator” or “BSA TM ”. Our project adds to the understanding of the design and integration of steam accumulators charged by solar thermal energy in a biofuels production facility, and similar facilities that consume process steam. The fuel application requires a demanding level of Process Safety Management not found in other steam applications. The type of steam accumulator SVI engineered and built integrates steam generation and storage in one vessel to reduce cost. Achieving a first of a kind permit to operate such a first device has also added to the understanding of the industrial application of such systems. Goals: The overall goal of the project has been to demonstrate the advantages that a “Bullet Steam Accumulator” (BSA™) can provide to solar steam integration with a manufacturing process. The industrial host has already been convinced of the potential of the available solar steam to lower than carbon intensity score. They have been interviewed for a number of publications such as that tout the advantages SVI’s system brings to their operations. Accomplishments: At the end of 2023 Sunvapor placed in service the country’s first industrial solar boiler with thermal energy storage. At the same time, this placement in service represents the first pilot commercial system to decarbonize biofuels production through the use of solar thermal energy. While the full technical effectiveness will be shown as soon as the customer’s plant is able to consume the available steam, the economic feasibility was indicated early in the project when the combination of costs and steam pricing required to meet investor expectations was determined. The project represents a reference pilot from which a full-scale commercial system may be expanded. This pilot is a necessary first step in providing the full potential benefits to the public, including decarbonization of transportation fuels. The decarbonization of the separation steps in fuels production may be the most cost-effective and nearest term solar fuel. Co-benefits include a reduction of air pollutants such as NOx and particulate matter, and job creation for the construction, operation and maintenance of industrial solar facilities.

14 SOLAR ENERGY↗