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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 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Metrics as tools for bridging climate science and applications

In climate science and applications, the term “metric” is used to describe the distillation of complex, multifaceted evaluations to summarize the overall quality of a model simulation, or other data product, and/or as a means to quantify some response to climate change. Metrics provide insights into the fidelity of processes and outcomes from climate models and can assist with both differentiating models' representation of variables or processes and informing whether models are “fit for purpose.” Metrics can also provide a valuable reference point for co-production of knowledge between climate scientists and climate impact practitioners. Although continued metric developments enable model developers to better understand the impacts of decisions made in the model design process, metrics also have implications for the characterization of uncertainty and facilitating analyses of underlying physical processes. As a result, comprehensive evaluation with multiple metrics enhances usability of climate information by both scientific and stakeholder communities. Here, this paper presents examples of insights gained from the development and appropriate use of metrics, and provides examples of how metrics can be used to engage with stakeholders and inform decision-making.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Fragme∩t: An Open‐Source Framework for Multiscale Quantum Chemistry Based on Fragmentation

Fragment-based quantum chemistry offers a means to circumvent the nonlinear computational scaling of conventional electronic structure calculations, by partitioning a large calculation into smaller subsystems then considering the many-body interactions between them. Variants of this approach have been used to parameterize classical force fields and machine learning potentials, applications that benefit from interoperability between quantum chemistry codes. However, there is a dearth of software that provides interoperability yet is purpose-built to handle the combinatorial complexity of fragment-based calculations. To fill this void we introduce “Fragme∩t”, an open-source software application that provides a tool for community validation of fragment-based methods, a platform for developing new approximations, and a framework for analyzing many-body interactions. Fragme∩t includes algorithms for automatic fragment generation and structure modification, and for distance- and energy-based screening of the requisite subsystems. Checkpointing, database management, and parallelization are handled internally and results are archived in a portable database. Interfaces to various quantum chemistry engines are easy to write and exist already for Q-Chem, PySCF, xTB, Orca, CP2K, MRCC, Psi4, NWChem, GAMESS, and MOPAC. Applications reported here demonstrate parallel efficiencies around 96% on more than 1000 processors but also showcase that the code can handle large-scale protein fragmentation using only workstation hardware, all with a codebase that is designed to be usable by non-experts. Fragme∩t conforms to modern software engineering best practices and is built upon well established technologies including Python, SQLite, and Ray. The source code is available under the Apache 2.0 license.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Exploratory Visual Analysis of Anomalous Runtime Behavior in Streaming High Performance Computing Applications

Online analysis of runtime behavior is essential for performance tuning in streaming scientific workflows. Integration of anomaly detection and visualization is necessary to support human-centered analysis, such as verification of candidate anomalies utilizing domain knowledge. In this work, we propose an efficient and scalable visual analytics system for online performance analysis of scientific workflows toward the exascale scenario. Here, our approach uses a call stack tree representation to encode the structural and temporal information of the function executions. Based on the call stack tree features (e.g., execution time of the root function or vector representation of the tree structure), we employ online anomaly detection approaches to identify candidate anomalous function executions. We also present a set of visualization tools for verification and exploration in a level-of-detailed manner. General information, such as distribution of execution times, are provided in an overview visualization. The detailed structure (e.g., function invocation relations) and the temporal information (e.g., message communication) of the execution call stack of interest are also visualized. The usability and efficiency of our methods are verified in a real-world HPC application.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2023

Towards a Standard Process Management Infrastructure for Workflows Using Python

Orchestrating the execution of ensembles of processes lies at the core of scientific workflow engines on large scale parallel platforms. This is usually handled using platform-specific command line tools, with limited process management control and potential strain on system resources. The PMIx standard provides a uniform interface to system resources. The low level C implementation of PMIx has hampered its use in workflow engines, leading to the development of Python binding that has yet to gain traction. In this paper, we present our work to harden the PMIx Python client, demonstrating its usability using a prototype Python driver to orchestrate the execution of an ensemble of processes. We present experimental results using the prototype on the Summit supercomputer at Oak Ridge National Laboratory. This work lays the foundation for wider adoption of PMIx for workflow engines, and encourages wider support of more PMIx functionality in vendor provided system software stacks.

Elwasif, Wael↗
DOE OSTI2016

On Synchronisation and Memory Reuse in OpenSHMEM, In: OpenSHMEM 2016: OpenSHMEM and Related Technologies. Enhancing OpenSHMEM for Hybrid Environments

OpenSHMEM is an open standard for PGAS libraries that provides one-sided communication semantics. Since the standardisation process was completed in 2012, the OpenSHMEM API has seen a rapid succession of proposed extensions. Among these extensions is the addition of teams of processing element (PEs) for greater flexibility in defining PE subsets for problem decomposition. Adding further to this, spaces introduced the ability to manage memory exclusive to teams without the need for global synchronisation. However, one problem still remains that affects the usability of teams, and that is the need for the user to manage memory used internally by the implementation for synchronisation in collective operations. This paper explores the possibilities for moving this responsibility from the user to the implementation, as well as the consequences that may arise as a result. To this end, we describe three methods of implementation and discuss the implications of their use compared to traditional user management of synchronisation buffers.

Computer Science↗
DOE OSTI2021

Generic one-loop matching conditions for rare meson decays

Leptonic and semileptonic meson decays that proceed via flavour-changing neutral currents provide excellent probes of physics of the standard model and beyond. We present explicit results for the Wilson coefficients of the weak effective Lagrangian for these decays in any perturbative model in which these processes proceed via one-loop contributions. We explicitly show that our results are finite and gauge independent, and provide Mathematica code that implements our results in an easily usable form.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Microbial Enrichments Contribute to Characterization Of Desert Tortoise Gut Microbiota

Abstract Desert tortoises play ecologically significant roles, including plant seed dispersal and mineral cycling, and yet little is known about microbial members that are critical to their gut and overall health. Tortoises consume recalcitrant plant material, which their gut microbiota degrades and converts into usable metabolites and nutrients for the tortoise. Findings from tortoise gut microbiomes may translate well into biotechnological applications as these microbes have evolved to efficiently degrade recalcitrant substrates and generate useful products. In this study, we cultivated microbial communities from desert tortoise fecal samples following a targeted anaerobic enrichment for microbes involved in deconstruction and utilization of plant biomass. We employed 16S rRNA amplicon sequencing to compare cultivated communities to initial fecal source material and found high abundances of Firmicutes and Bacteroidota typically associated with biomass deconstruction in all cultivated samples. Significantly decreased microbial diversity was observed in the cultivated microbial communities, yet several key taxa thrived in lignocellulose enrichments, includingLachnospiraceaeandEnterococcus. Additionally, cultivated communities produced short-chain fatty acids under anaerobic conditions, and their growth and metabolic output provide evidence of their viability in the initial fecal communities. Overall, this study adds to the limited understanding of reptilian herbivore microbiota, and offers a path towards biotechnological translation based on the ability of the cultivated communities to convert lignocellulose directly to acetate, propionate, and butyrate.

Environmental Sciences & Ecology↗
DOE OSTI2019

A Review of the Current Status of Percutaneous Endovascular Arteriovenous Fistula Creation for Haemodialysis Access

Surgical fistulas were first described over 50 years ago and have revolutionized the outlook for millions of dialysis-dependent patients. Despite many developments, results remain sub-optimal with high rates of primary failure and re-intervention to maintain patency. Surgical fistulas are known to fail in part due to intimal hyperplasia leading to stenosis, and vessel manipulation during anastomosis creation can be contributory. New technology is emerging that allows the endovascular creation of fistulas with minimal vessel trauma and the initial results demonstrate encouraging outcomes with high technical success rates, low re-intervention, and failure rates and good usability for hemodialysis. Two such device systems are currently available, and here, we provide an overview of the current global status of endoAVF, patient selection criteria, trial results, technical aspects, re-interventions, and outlook for the future.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Experimental Assessment of a Novel Touchless Interface for Intraprocedural Imaging Review

Purpose: To examine the feasibility of a novel technology platform that enables real-time touchless interaction with radiology images in both a simulated and an actual clinical setting. Materials and Methods: This platform offers three different modes for image interaction. The gesture recognition mode uses a depth camera to detect the user’s hand gestures which are translated to image manipulation commands. The light projection mode uses the same camera to detect finger point-and-tap movements above the icons which are projected on a surface to activate the commands. The capacitive sensing mode is enabled by a handheld, portable device, over which finger movements are detected by capacitive sensors to control the image review. Following initial feedback, light projection and capacitive sensing modes were selected for further testing by comparing with the conventional mode of image interaction in time trials for performing a series of standardized image manipulation tasks. Finally, the usability of the technology platform was examined in actual clinical procedures. Results: The light projection and the capacitive sensing modes were evaluated in the time trials and exhibited 60% and 71% reduction in time, respectively, relative to the control mode (p < 0.001). Clinical feasibility for this platform was demonstrated in three actual interventional radiology cases. Conclusion: Accessing, navigating, and extracting relevant information from patient images intraprocedurally are cumbersome and time-consuming tasks that affect safety, efficiency, and decision-making during image-guided procedures. This study demonstrated that the novel technology addressed this issue by allowing touchless interaction with these images in the sterile field.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Building a sustained climate assessment process

The leaders and authors of the Third US National Climate Assessment (NCA3) developed new modes of engaging academia, the private sector, government agencies and civil society to support their needs for usable, rigorous, and timely information and better connect science and decision-making. A strategic vision for assessment activities into the future was built during the NCA3 process, including recommendations on how to establish a sustained assessment process that would integrate evolving scientific understanding into decision making to manage the risks of climate change over time. This vision includes a collaborative assessment process that involves partnerships across a diverse and widely distributed set of non-governmental and governmental entities. The new approach to assessments would produce timely, scientifically sound climate information products and processes, rather than focusing on the production of single quadrennial synthesis reports. If properly implemented, a sustained assessment would be more efficient and cost-effective, avoiding the painful and time-consuming process of beginning the assessment process anew every 4 years. This ongoing assessment would also encourage scientific and social innovations and explore new insights and opportunities, building the capacity to advance the development and delivery of climate information to meet societal requirements and benefit from scientific opportunities.

Buizer, James L.↗
DOE OSTI2024

Two-Stage Cryogenic HEMT-Based Amplifier for Low-Temperature Detectors

To search for dark matter candidates with masses below $\mathcal{O}$ (MeV), the SPLENDOR (Search for Particles of Light dark mattEr with Narrow-gap semiconDuctORs) experiment is developing novel narrow-bandgap semiconductors with electronic bandgaps on the order of 1–100 meV. In order to detect the charge signal produced by scattering or absorption events, SPLENDOR has designed a two-stage cryogenic HEMT-based amplifier with an estimated charge resolution approaching the single-electron level. A low-capacitance (~ 1.6 pF) HEMT is used as a buffer stage at T = 10 mK to mitigate effects of stray capacitance at the input. The buffered signal is then amplified by a higher-capacitance (~ 200 pF) HEMT amplifier stage at T = 4 K. Importantly, the design of this amplifier makes it usable with any insulating material—allowing for rapid prototyping of a variety of novel detector materials. Here, we present the two-stage cryogenic amplifier design, preliminary voltage noise performance, and estimated charge resolution of 7.2 electrons.

47 OTHER INSTRUMENTATION↗
DOE OSTI2018

Adsorption Studies of PVA Based Thermosensitive Polymers in Heavy Metal Removal

Thermosensitive copolymers were synthesized by grafting of N-isopropyl acrylamide (NIPAM) monomer onto crosslinked poly(vinyl alcohol) (PVA) and characterized by FTIR, XRD, elemental and SEM-EDS analysis. Also, the swelling capacities, water release values and cloud points of the copolymers were determined. The removal of Cu(II), Ni(II) and Cd(II) ions was studied by using of the copolymers as solid phase extractor. Dodecyltrimethylammonium chloride (DTAC) was the extractant to complex with ions in the process. The copolymer adsorbs the metal–extractant complexes above its lower critical solution temperature (LCST) by hydrophobic interaction. Increasing the time and initial metal ion concentration caused an increase in the adsorption capacities, and the copolymer displayed S-type adsorption in Giles’s classification. The experimental data followed pseudo-second-order model, and the dominated adsorption mechanism was external mass diffusion. In addition, adsorption/desorption cycles presented the usability of the synthesized copolymer as sorbent for environmentally friendly processes.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Real-time dispatch optimization for concentrating solar power with thermal energy storage

Concentrating solar power (CSP) plants present a promising path towards utility-scale renewable energy. The power tower, or central receiver, configuration can achieve higher operating temperatures than other forms of CSP, and, like all forms of CSP, naturally pairs with comparatively inexpensive thermal energy storage, which allows CSP plants to dispatch electricity according to market price incentives and outside the hours of solar resource availability. Currently, CSP plants commonly include a steam Rankine power cycle and several heat exchange components to generate high-pressure steam using stored thermal energy. The efficiency of the steam Rankine cycle depends on the temperature of the plant's operating fluid, and so is a main concern of plant operators. However, the variable nature of the solar resource and the conservatism with which the receiver is operated prevent perfect control over the receiver outlet temperature. Therefore, during periods of solar variability, collection occurs at lower-than-design temperature. To support operator decisions in a real-time setting, we develop a revenue-maximizing non-convex mixed-integer, quadradically-constrained program which determines a dispatch schedule with sub-hourly time fidelity and considers temperature-dependent power cycle efficiency. The exact nonlinear formulation proves intractable for real-time decision support. Here we present exact and inexact techniques to improve problem tractability that include a hybrid nonlinear and linear formulation. Our approach admits solutions within approximately 3% of optimality, on average, within a five-minute time limit, demonstrating its usability for decision support in a real-time setting.

14 SOLAR ENERGY↗
DOE OSTI2022

Science of the Van Allen Probes Science Operations Centers

The Van Allen Probes mission operations materialized through a distributed model in which operational responsibility was divided between the Mission Operations Center (MOC) and separate instrument specific SOCs. The sole MOC handled all aspects of telemetering and receiving tasks as well as certain scientifically relevant ancillary tasks. Each instrument science team developed individual instrument specific SOCs proficient in unique capabilities in support of science data acquisition, data processing, instrument performance, and tools for the instrument team scientists. In parallel activities, project scientists took on the task of providing a significant modeling tool base usable by the instrument science teams and the larger scientific community. With a mission as complex as Van Allen Probes, scientific inquiry occurred due to constant and significant collaboration between the SOCs and in concert with the project science team. Planned cross-instrument coordinated observations resulted in critical discoveries during the seven-year mission. Instrument cross-calibration activities elucidated a more seamless set of data products. Specific topics include post-launch changes and enhancements to the SOCs, discussion of coordination activities between the SOCs, SOC specific analysis software, modeling software provided by the Van Allen Probes project, and a section on lessons learned. One of the most significant lessons learned was the importance of the original decision to implement individual team SOCs providing timely and well-documented instrument data for the NASA Van Allen Probes Mission scientists and the larger magnetospheric and radiation belt scientific community.

47 OTHER INSTRUMENTATION↗
DOE OSTI2017

Agent-Based Socio-Hydrological Hybrid Modeling for Water Resource Management

Hybrid socio-hydrological modeling has become indispensable for managing water resources in an increasingly unstable ecology caused by human activity. Most work on the subject has been focused on either qualitative socio-political recommendations with an unbounded list of vague factors or complex sociological and hydrological models with many assumptions and specialized usability. Here in this paper, we propose a simple agent-based socio-hydrological decision modeling framework for coupling dynamics associated with social behavior and groundwater contamination. The study shows that using social health risk, instead of contaminant concentration, as an optimization variable improves water management decisions aimed at maximizing social wellbeing. The social models and computational framework are designed with enough flexibility and simplicity to encourage extensions to more general socio-hydrological dynamics without compromising either computability or complexity for better data-/model-driven environmental management.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Friction Extrusion: Solid-State Metal Synthesis and Recycling in Sustainable Manufacturing

Friction extrusion (FE) is a novel solid-state process for synthesis and recycling of metals and alloys. The novelty of FE is that it utilizes the frictional heating and extensive plastic deformation intrinsic in the process to stir, mechanically alloy, consolidate, and convert powders, chips, and other recyclable feedstock metals into a usable product form of highly engineered materials. FE represents a potentially transformational sustainable manufacturing technology. Being a solid-state process, it eliminates the energy-intensive melting and solidification steps, which are necessary in the conventional metal recycle and synthesis processes. Therefore, FE is a highly energy-efficient, practically zero-emission, and economically competitive process. Here, in this work, the concept and configuration of FE are introduced, the energy-saving advantage of FE is analyzed, the feasibility of FE is demonstrated with synthesizing Al alloys, and the results of some metallographic and mechanical properties studies are presented. A prognosis of the friction extrusion technology is outlined.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Laboratory-Based Micro-X-ray Computed Tomography of Energy Materials at Idaho National Laboratory

Abstract The Idaho National Laboratory (INL) has implemented laboratory-based micro-X-ray computed tomography in a laboratory equipped for the examination of highly radioactive samples. This capability provides nondestructive three-dimensional volumetric information on samples to inform subsequent traditional destructive examinations as well as real-world inputs for high-fidelity scientific modeling. Samples can be imaged with spatial resolutions ranging from several hundred nm/voxel up to ~ 100 µm/voxel. The best usable spatial resolution achieved to date is 384 nm/voxel with this instrument, while the highest radiological dose rate of a sample imaged is ~ 60 R/h β/γ on contact. Advanced data analysis, including custom tomographic reconstruction and segmentation methods, have also been developed to support this capability. In addition to traditional digital X-ray radiography and tomography, this instrument is also able to visualize in situ tensile and compression testing as well as perform diffraction contrast tomography. This work describes the X-ray computed tomography post-irradiation examination capabilities at INL, as well as detailing a variety of applications this instrument has examined.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Pyrrolizidine Alkaloids-Free Extract from the Cell Culture of Lithospermum officinale with High Antioxidant Capacity

The benefits of Lithospermum officinale has encouraged people to continue using its extract (CAS 90063-58-4) in both medicinal and cosmetic industries despite the fact that chemical analysis confirms the presence of pyrrolizidine alkaloids (PAs) in the extract. While the cultivation of L. officinale takes, at least, 2 years to produce usable crops, its callus culture proliferated 8.3 times with 4.9-fold biomass in less than 30 days under the applied conditions in this study. Under the applied conditions, the cell extract contained no toxic PAs while phenylpropanoid pathway was active toward phenolic acids formation not toward naphthoquinone derivatives. Rosmarinic acid was produced as the main constituent. Total phenolic content and antioxidant capacity of the proliferated cell extracts were similar to those of the extracts of the natural plant tissues, in particular from the root. These results support the idea that the extract of L. officinale cells can be a reliable substitute for the extract of the natural plant tissues.

60 APPLIED LIFE SCIENCES↗