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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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Energy Literacy: Essential Principles and Fundamental Concepts for Energy Education presents energy concepts that, if understood and applied, will help individuals and communities make informed energy decisions.
This White Paper describes recent progress and future opportunities in the area of fundamental symmetries and neutrinos.
The Network Fundamental Diagram (NFD) is increasingly used in traffic monitoring and control. One obstacle to a wider application of NFDs in network control is the difficulty of obtaining data from all vehicles traveling in the network to construct an accurate NFD. One solution is to estimate the NFD using data from only a fraction of vehicles (i.e., probe vehicles), where the probe vehicle market penetration rate (MPR) needs to be estimated. A previous study conducted by the authors demonstrated that a distance or time weighted harmonic mean was needed to estimate the flow- and density-based MPRs, respectively using a pairing k-mean clustering approach. This paper proposes another approach that utilizes probe vehicle and observed link volume data to estimate the MPR. A heuristic model is proposed to identify the optimum locations from which to collect link traffic volume data for use in the MPR estimation. The estimated MPR can then be used to construct the NFD. Results show that these models can accurately estimate the NFD with limited probe vehicle and link traffic volume data. Accordingly, the models can be used in the field to estimate the NFD using readily available loop detector and probe vehicle data. The ideal locations for traffic volume data collection can also be proactively chosen to generate optimum estimation results. Since the models proposed here show no significant gains with an increased magnitude of collected data after a certain threshold, they will be helpful, particularly when large-scale data collection is not affordable or realistic.
Design-level performance of each energy conservation measure (ECM) in an awarded utility energy service contract (UESC) is fundamental to achieving the projected results through the term of the contract and over the life of the measure. Because the authority for a UESC does not require contractual guarantees of energy, water, or cost savings, FEMP developed a protocol for emphasizing sustained performance to help ensure projected savings are realized. The information and templates offered within this paper reflect responsible project management and oversight, align with UESC best practices, and satisfy the conditions for annual scoring provided by the Office of Management and Budget (OMB). OMB memorandum M-12-21 requires, 'energy savings performance assurances,' 'measurement and verification (M&V) of savings through commissioning and retrocommissioing,' and 'competition or an alternatives analysis as part of the selection process.'
As building technologies become more advanced, the need for highly skilled and qualified workers has increased. Both residential and commercial building industries struggle to capture the full benefit of these new technologies because of the limited building science knowledge base of the professionals researching, designing, building, and selling these structures. To help address this need, the U.S. Department of Energy’s (DOE’s) Residential Building Integration (RBI) program initiated the Guidelines for Building Science Education (GBSEs). These guidelines provide guidance on the fundamental building science knowledge base that is helpful for a wide range of building industry jobs. This effort provides a mechanism for training organizations to align core curriculum that can be applied to any building type. At the same time, DOE’s Commercial Building Integration (CBI) program has been spearheading a full suite of impactful initiatives including the Better Buildings Workforce Guidelines (BBWGs), which provide voluntary national guidelines from which select stakeholders can develop high-quality and nationally recognized training and certification programs. The BBWG framework helps to improve quality and scalability issues for five energy efficiency-related jobs: Building Energy Auditor, Building Commissioning Professional, Building Operations Professional, Building Operations Journey-Worker and Energy Manager. The residential and commercial building programs are both interested in helping to create better buildings through an improved workforce. The two program initiatives complement each other in many ways. The GBSEs pave the way for more specialized training and education offered by industry and academia, which lead to credentials that signify competency. The BBWGs cover credentialing for energy efficiency jobs—a critical area that DOE believed could benefit from incentives for credentialing bodies and building operators that would improve the energy efficiency of commercial buildings. This paper summarizes the steps DOE programs have taken to work together and the outcome of this symbiotic relationship.
The ability to tie structural features to a fuel candidate’s ignition properties provides a path for rational design of advantaged fuels that facilitate higher-efficiency, lower-emitting combustion in engines. The time evolution of a fuel’s radical population directly correlates with global combustion parameters, and because the generated radicals depend on the initial structure and reaction pathways of the fuel molecule, it follows that the molecular structure of a fuel has a direct impact on this cascade, and therefore salient ignition-tied fuel properties. This work aims to understand the impact of structural features in the context of global combustion properties for direct application to emerging engine technologies. Specifically, we highlight the ability to identify potential fuel blendstocks for specific engine strategies by examining and elucidating the radical cascade tied to ignition. A representative subset of alcohols possessing a variety of structural features (e.g. branching, chain length) was selected for study using a robust combination of experimental and computational methods. The approach begins with identifying short-lived radicals and likely abstraction sites upon pyrolysis in a microreactor coupled with photoionization mass spectrometry for direct detection of product species. In tandem, electronic structure calculations were performed to calculate the relevant potential energy surfaces for fuel pyrolysis as well as the subsequent O2 addition-isomerization reactions, which govern ignition behavior. Furthermore, the theoretical energetic and ro-vibrational data are used to calculate rate constants for direct ignition modeling to explore how structural effects impact NTC behavior. The microreactor data combined with electronic structure theory calculations provide a well-informed picture of the reactions relevant to ignition for each fuel in this study, as well as the most likely radicals generated under engine conditions. This thorough fundamental picture of fuel decomposition and ignition chemistry is used to correlate the observed ignition behavior to molecular structural effects.
The question I am examining in this article is whether the value of the speed of electromagnetic and gravitational waves is a fundamental constant of nature or whether it can be derived from theory.
This talk describes the fundamentals underlying defect-free growth of large-area III-V devices on oxide-nanopatterned GaAs substrates, and applies them to the growth of 24.8% efficient GaAs solar cells with a dislocation density less than 5 x 10^5 cm^-2. In this application the nanopatterned oxide layer serves as a mechanically-weak layer for substrate separation and reuse, but in other applications it could serve as an optical element to diffract or redirect light. This presentation focuses on how the topology and dimensions of the oxide mask must be controlled to avoid defect formation wherever the epilayer coalesces over a mask feature.
This presentation is an introduction to foundational concepts for integrating variable renewable energy (VRE) into bulk power systems, with a focus on the Greater Mekong Subregion. It contains fundamentals on challenges and solutions for VRE integration (e.g., wind and solar PV), as well as deep dives on energy storage, floating solar PV (FPV), and cross-border energy trade (CBET). Case studies are contained throughout.
All used nuclear fuel (UNF) reprocessing technologies must operate efficiently in the presence of an intense, multi-component (predominantly alpha, beta, and gamma) radiation field. Consequently, radiation-induced degradation of reprocessing systems is of concern, as it negatively impacts process performance over time due to the destruction of both active compounds (ligands, phase modifiers, holdback agents, etc.) and the formation of degradation products. Reprocessing solvent system radiolysis has been linked to changes in separation efficiency and physical properties of solvent mixtures, solvent-recycle longevity, crud formation, and other unexpected outcomes that impact the efficient recovery of valuable materials (e.g., the actinides) and the volume of hazardous radioactive waste for final disposal, i.e., in a geological repository. Consequently, a fundamental understanding of radiolytic processes and their effects on reprocessing solvent system performance is critical for: (i) the cost-effective development and innovation of separation technologies; (ii) the design and implementation of predictive radiation chemical models for process monitoring and lifetimes; and (iii) potentially the ability to exploit radiolytic phenomenon to our benefit, e.g., strategic radiolysis of active molecules to liberate specific degradation products that aid subsequent process stages. Despite extensive investigation into the radiolytic behavior of active solvent system compounds, little attention has been given to understanding (i) the radiation chemical behavior and modification of the organic diluent and (ii) the effect of metal ion complexation on the radiochemical behavior of active compounds.
In order to meet aggressive decarbonization goals, photovoltacs (PV) need to expand substantially. The current technology that heavily dominates the market, silicon (Si), comprises 95% of the world's PV production, is energy intensive to make, and can take up a substantial portion of the remaining carbon budget if expanded. Conversely, cadmium telluride (CdTe) comprises much of the remaining 5% of the global PV market and has a significantly lower carbon footprint than Si, historically costs less to produce, and is critically important to U.S. competitiveness in the global market. Importantly, CdTe still has room to grow, particularly related to efficiency because voltage has historically been much lower than what we calculate it should be. My research is focused in part on understanding this voltage deficit from a fundamental perspective by studying bulk materials and interfaces. One of the most important regions of the device is buried within the stack, so I developed a technique to cleave and reveal buried interfaces. This cleave technique has enabled a much better scientific understanding and allows us to make lightweight, flexible PV while maintaining low costs, high efficiency, and high throughput associated with standard module processing.
Niobium is a widely accepted material for quantum computing device as well as superconducting radio frequency (SRF) technology. Superconducting niobium is a marginal type II superconductor which has a very narrow gap (~20-30 mT) of the mixed state at 2K, even showing the intermediate state (IMS) at the early stage of magnetic vortex penetration. Tremendous progress has been made in understanding the impact of the Nb surface and bulk superconductivities on SRF resonator performance. However, the effect of thin superconducting Nb films for quantum computing applications requires further examination. In this study, we explore the fundamental superconducting properties of various thin Nb films and compare them with respect to the energy relaxation time, T1, measured from superconducting qubit fabricated with these films. The Nb films are fabricated both with or without a surface protective layer that prevents the formation of lossy Nb2O5. Electromagnetic properties are characterized by means of bulk magnetization, electromagnetic transport, and dynamics of surface superconductivity. In addition, analytical electron microscopy is implemented to further connect the superconducting properties to microstructure.
FR (Fast Reactor) is widely recognized to effectively burn plutonium and MA (Minor Actinides) (i.e., TRU: Transuranic) due to its higher fission-to-neutron-capture ratio compared to LWR. When TRU in LWR (Light Water Reactor) spent fuel is recycled into FR cycle, the radiotoxicity of the residual nuclear wastes from LWR spent fuel is reduced to natural uranium level after several hundred years instead of more than hundreds of thousand years for no recycling case. It could significantly improve public perception to nuclear waste disposal and might reduce the burden of the disposal. However, U-TRU-fueled fast reactors also produce TRU while burning TRU because they use uranium together with TRU. For example, FR, even with low conversion ratio of 0.75, burns only 0.18 t TRU/GWe/y, while LWRs produces about 0.22 t TRU/GWe/y. It is not a realistic scenario which needs almost the same capacity of fast reactors as that of LWRs to continuously burn TRU at LWR-dominant era in the near term at least. Therefore, a FR system to burn TRU from LWR with the minimum reactor units is desirable. The most effective way is to use uranium-free TRU fuel since it does not produce any new TRU. It can reduce the capacity of the TRU burner units and the associated fuel cycle facilities to about 1/5 and 1/8 respectively. Metal fuel FR cycle is considered to be one of the most promising ways because uranium-free TRU metal fuel could be recycled by pyro-process for U-Pu-Zr metal fuel without large modifications. This paper shows the recent research progress on fundamental properties of uranium-free TRU metal fuel. (authors)
Lattice simulations have observed a novel strong coupling symmetric mass generation (SMG) phase for the SU(3) gauge system with $N_f=8$ fundamental fermions (represented by two sets of staggered fields) at very large renormalized coupling ($g^2_{GF} \gtrsim 25$). The results of Phys.Rev.D 106 (2022) 014513 suggest that the SMG phase is separated from the weak coupling, conformal phase by a continuous phase transition, implying that the SMG phase exists in the continuum limit. To scrutinize these findings, we are generating a set of large volume zero temperature ensembles using nHYP improved staggered fermions with additional Pauli-Villars fields to tame gauge field fluctuations. We consider the low-lying meson spectrum and verify the existence of the SMG phase. Based on a finite size scaling analysis we predict that the phase transition between the strong and weak coupling phases is likely governed by a merged fixed point that is ultraviolet in the strong coupling but infrared in the weak coupling side. This finding suggests that the SU(3) 8-flavor system sits at the opening of the conformal window
Extrusion-based additive manufacturing processes begin with a software program, called a slicer, that generates layer geometry and fits toolpaths to each layer to define where material is to be extruded or deposited. Before the toolpaths are output as g-code for the additive manufacturing system to execute, the toolpaths should be optimized. Many complex optimization approaches using graph theory, Chinese postman problem, and other complex mathematical models exist, but these approaches are rarely used in daily printing operations and are not available through common slicing programs such as Cura and PrusaSlicer. Instead, path planning and optimization typically revolves around simpler, fully automated approaches such as inside out and next closest. This paper will explore the fundamental optimization strategies for toolpath planning and document a new implementation, available via open-source slicing software, that allows for greater control of the path planning process.
The PARADIGM project aims at accelerating progress in science by quantitatively answering the following question: What is the optimal combination of fundamental-science and application driven experiments to maximally reduce pertinent data uncertainties? Hence, we are bridging between microscopic experiments and data, and macroscopic simulations and experiments. Answering this question entails solving a high-dimensional and complex optimization problem which we solve with machine learning techniques.
Measurements of peculiar velocities in the local Universe are a powerful tool to study the nature of dark energy at low ($z < 0.1$) redshifts. Here we present the largest single set of $z<0.1$ peculiar velocity measurements to date, obtained using the Fundamental Plane (FP) of galaxies in the first data release (DR1) of the Dark Energy Spectroscopic Instrument (DESI). We describe the photometric and spectroscopic selection criteria used to define the sample, as well as extensive quality control checks on the photometry and velocity dispersion measurements. Additionally, we perform detailed systematics checks for the many analysis parameters in our pipeline. Our DESI DR1 catalogue contains FP-based distances and peculiar velocities for $98,292$ unique early-type galaxies, increasing the total number of $z < 0.1$ FP distances ever measured by a factor of $\sim2$. We achieve a precision of $26\%$ random error in our distance measurements which is comparable to previous surveys. A series of companion DESI papers use the distances and peculiar velocities presented in this paper to measure cosmological parameters.
Fundamentals of Structural Materials for Nuclear Energy