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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 829 records · Page 46
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Machine learning analysis of RB-TnSeq fitness data predicts functional gene modules in Pseudomonas putida KT2440

ABSTRACT There is growing interest in engineering Pseudomonas putida KT2440 as a microbial chassis for the conversion of renewable and waste-based feedstocks, and metabolic engineering of P. putida relies on the understanding of the functional relationships between genes. In this work, independent component analysis (ICA) was applied to a compendium of existing fitness data from randomly barcoded transposon insertion sequencing (RB-TnSeq) of P. putida KT2440 grown in 179 unique experimental conditions. ICA identified 84 independent groups of genes, which we call fModules (“functional modules”), where gene members displayed shared functional influence in a specific cellular process. This machine learning-based approach both successfully recapitulated previously characterized functional relationships and established hitherto unknown associations between genes. Selected gene members from fModules for hydroxycinnamate metabolism and stress resistance, acetyl coenzyme A assimilation, and nitrogen metabolism were validated with engineered mutants of P. putida . Additionally, functional gene clusters from ICA of RB-TnSeq data sets were compared with regulatory gene clusters from prior ICA of RNAseq data sets to draw connections between gene regulation and function. Because ICA profiles the functional role of several distinct gene networks simultaneously, it can reduce the time required to annotate gene function relative to manual curation of RB-TnSeq data sets. IMPORTANCE This study demonstrates a rapid, automated approach for elucidating functional modules within complex genetic networks. While Pseudomonas putida randomly barcoded transposon insertion sequencing data were used as a proof of concept, this approach is applicable to any organism with existing functional genomics data sets and may serve as a useful tool for many valuable applications, such as guiding metabolic engineering efforts in other microbes or understanding functional relationships between virulence-associated genes in pathogenic microbes. Furthermore, this work demonstrates that comparison of data obtained from independent component analysis of transcriptomics and gene fitness datasets can elucidate regulatory-functional relationships between genes, which may have utility in a variety of applications, such as metabolic modeling, strain engineering, or identification of antimicrobial drug targets.

09 BIOMASS FUELS↗
DOE OSTI2023

Genomad v1.0

Genomad aims to identify mobile genetic elements (namely, viruses and plasmids) from DNA sequence data. It uses a combination of marker gene identification and machine learning models to find likely virus/plasmid candidates in environmental DNA sequencing data. It has an improved classification performance over similar tools.

Camargo, Antonio↗
DOE OSTI2024

Machine Learning-Based Identification of the Interface Regions for Coupling Local and Nonlocal Models

Local-nonlocal coupling approaches provide a means to combine the computational efficiency of local models and the accuracy of nonlocal models. However, the coupling process can be challenging, requiring expertise to identify the interface between local and nonlocal regions. Here, this study introduces a machine learning-based approach to automatically detect the regions in which the local and nonlocal models should be used. The method uses loading functions evaluated at grid points to decide the model selection at those points. Training of the networks is based on datasets provided by classes of loading functions for which reference coupling configurations are computed using accurate coupled solutions, where accuracy is measured in terms of the relative error between the solution to the coupling approach and the solution to the nonlocal model. We study two approaches that vary in data structure. The first, the full-domain input data approach, uses the entire load vector and outputs a complete label vector, performing a global classification. The second, a window-based approach, processes loads into windows and addresses the problem as a node-wise classification where each window's central point is classified individually. The classification problems are solved via deep learning algorithms based on convolutional neural networks. The performance of these approaches is studied on one-dimensional numerical examples using F1-scores and accuracy metrics. Notably, the windowing approach achieves an accuracy of 0.96 and an F1-score of 0.97, highlighting its potential to automate coupling processes effectively and enhance computational efficiency in material science applications.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2017

Identifying and Correcting Timing Errors at Seismic Stations in and around Iran

A fundamental component of seismic research is the use of phase arrival times, which are central to event location, Earth model development, and phase identification, as well as derived products. Hence, the accuracy of arrival times is crucial. However, errors in the timing of seismic waveforms and the arrival times based on them may go unidentified by the end user, particularly when seismic data are shared between different organizations. Here, we present a method used to analyze travel-time residuals for stations in and around Iran to identify time periods that are likely to contain station timing problems. For the 14 stations with the strongest evidence of timing errors lasting one month or longer, timing corrections are proposed to address the problematic time periods. Finally, two additional stations are identified with incorrect locations in the International Registry of Seismograph Stations, and one is found to have erroneously reported arrival times in 2011.

58 GEOSCIENCES↗
DOE OSTI2013

Energy Zones Study: A Comprehensive Web-Based Mapping Tool to Identify and Analyze Clean Energy Zones in the Eastern Interconnection

This report describes the work conducted in support of the Eastern Interconnection States’ Planning Council (EISPC) Energy Zones Study and the development of the Energy Zones Mapping Tool performed by a team of experts from three National Laboratories. The multi-laboratory effort was led by Argonne National Laboratory (Argonne), in collaboration with the National Renewable Energy Laboratory (NREL) and Oak Ridge National Laboratory (ORNL). In June 2009, the U.S. Department of Energy (DOE) and the National Energy Technology Laboratory published Funding Opportunity Announcement FOA-0000068, which invited applications for interconnection-level analysis and planning. In December 2009, the Eastern Interconnection Planning Collaborative (EIPC) and the EISPC were selected as two award recipients for the Eastern Interconnection. Subsequently, in 2010, DOE issued Research Call RC-BM-2010 to DOE’s Federal Laboratories to provide research support and assistance to FOA-0000068 awardees on a variety of key subjects. Argonne was selected as the lead laboratory to provide support to EISPC in developing a methodology and a mapping tool for identifying potential clean energy zones in the Eastern Interconnection. In developing the EISPC Energy Zones Mapping Tool (EZ Mapping Tool), Argonne, NREL, and ORNL closely collaborated with the EISPC Energy Zones Work Group which coordinated the work on the Energy Zones Study. The main product of the Energy Zones Study is the EZ Mapping Tool, which is a web-based decision support system that allows users to locate areas with high suitability for clean power generation in the U.S. portion of the Eastern Interconnection. The mapping tool includes 9 clean (low- or no-carbon) energy resource categories and 29 types of clean energy technologies. The EZ Mapping Tool contains an extensive geographic information system database and allows the user to apply a flexible modeling approach for the identification and analysis of potential energy zones and is publicly available at http://eispctools.anl.gov. In addition to enabling EISPC members and other stakeholders to identify areas with a high concentration of clean energy resources that could provide significant power generation in the future, another objective of the study was to promote open and transparent collaboration among state-level energy planning and regulatory agencies and to foster consistent and coordinated direction for regional and interconnection-level electricity analyses and planning. Funding for the project was provided by DOE’s Office of Electricity Delivery and Energy Reliability (DOE/OE) under the American Recovery and Reinvestment Act. Page

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2013

Real-Time Distribution Feeder Performance Monitoring, Advisory Control, and Health Management System

New data collection system equipment was installed in Xcel Energy substations and data was collected from 6 substations and 20 feeders. During Phase I, ABB collected and analyzed 793 real-time events to date from 6 Xcel Energy substations and continues today. The development and integration of several applications was completed during the course of this project, including a model-based faulted segment identification algorithm, with very positive results validated with field-gathered data discussed and included in this report. For mostly underground feeders, the success rate is 90% and the overreach rate is 90%. For mostly overhead feeders, the success rate is 74% and the overreach rate is 50%. The developed method is producing very accurate results for mostly underground feeders. For mostly overhead feeders, due to the bad OMS data quality and varying fault resistance when arcing, the developed method is producing good results but with much room for improvement. One area where the algorithm can be improved is the accuracy for sub-cycle fault events. In these cases, the accuracy of the conventional signal processing methods suffers due to most of these methods being based on a one-cycle processing window. By improving the signal processing accuracy, the accuracy of the faulted segment identification algorithm will also improve significantly. ABB intends to devote research in this area in the near future to help solve this problem.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2022

Ice processes in Antarctica: identification via multi-wavelength active and passive measurements and model evaluation (Final Report)

This project is based on new multi-frequency radar observations collected during the AWARE field campaign in 2016 at McMurdo Station by the ARM Mobile facility. Three scientific goals have been achieved. We have developed ice and mixed-phase cloud microphysics retrievals from multi-wavelength radar observations and ancillary observations, generally applicable at ARM sites. These technique generally better characterize the size of the ice crystals, their equivalent water content and the degree of riming better than using single wavelength techniques. We have characterized ice microphysical properties and ice processes via multi-frequency signatures. We have identified a unique mode in the McMurdo dataset appearing at quite cold temperature that we have attributed to riming processes. Triple frequency radar measurements unfortunately were available only for a short period but our work lays the foundation for building climatological and testing their replicability in models. Simultaneously case studies from the AWARE campaign have been exploited to evaluate and improve the NASA GISS ModelE3 climate model, including selection of case studies for combined goals of (i) running side-by-side using large-eddy simulation (LES) and ModelE3 in single-column model (SCM) mode and (ii) fingerprinting cloud processes in multi-wavelength radar observations. The different components of this work have contributed to 15 published papers with two currently under review.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Acoustic Research under the Source Physics Experiment

The Source Physics Experiment series is a long-term research and development (R&D) effort under the U.S. Department of Energy’s National Nuclear Security Administration focused on improving the physical understanding of how chemical explosions generate seismoacoustic signals. Beginning in 2011, a series of subsurface chemical explosions in two different and highly contrasting geologies were conducted at the Nevada National Security Site in Nevada, USA with the objective of improving simulation and modeling approaches to explosion identification, yield estimation and other monitoring applications. The two executed phases of the series provide new explosion signature source data from a wide range of geophysical diagnostic equipment; recorded data from the test series is now openly available to the broader seismoacoustic community. This manuscript details the executed test series, deployed seismoacoustic networks, and summarizes major scientific achievements utilizing recorded signatures from the explosive tests.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2021

Image-Based Methods to Score Fungal Pathogen Symptom Progression and Severity in Excised Arabidopsis Leaves

Image-based symptom scoring of plant diseases is a powerful tool for associating disease resistance with plant genotypes. Advancements in technology have enabled new imaging and image processing strategies for statistical analysis of time-course experiments. There are several tools available for analyzing symptoms on leaves and fruits of crop plants, but only a few are available for the model plant Arabidopsis thaliana (Arabidopsis). Arabidopsis and the model fungus Botrytis cinerea (Botrytis) comprise a potent model pathosystem for the identification of signaling pathways conferring immunity against this broad host-range necrotrophic fungus. Here, we present two strategies to assess severity and symptom progression of Botrytis infection over time in Arabidopsis leaves. Thus, a pixel classification strategy using color hue values from red-green-blue (RGB) images and a random forest algorithm was used to establish necrotic, chlorotic, and healthy leaf areas. Secondly, using chlorophyll fluorescence (ChlFl) imaging, the maximum quantum yield of photosystem II (Fv/Fm) was determined to define diseased areas and their proportion per total leaf area. Both RGB and ChlFl imaging strategies were employed to track disease progression over time. This has provided a robust and sensitive method for detecting sensitive or resistant genetic backgrounds. A full methodological workflow, from plant culture to data analysis, is described.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2013

Optimal SCR Control Using Data-Driven Models

We present an optimal control solution for the urea injection for a heavy-duty diesel (HDD) selective catalytic reduction (SCR). The approach taken here is useful beyond SCR and could be applied to any system where a control strategy is desired and input-output data is available. For example, the strategy could also be used for the diesel oxidation catalyst (DOC) system. In this paper, we identify and validate a one-step ahead Kalman state-space estimator for downstream NOx using the bench reactor data of an SCR core sample. The test data was acquired using a 2010 Cummins 6.7L ISB production engine with a 2010 Cummins production aftertreatment system. We used a surrogate HDD federal test procedure (FTP), developed at Michigan Technological University (MTU), which simulates the representative transients of the standard FTP cycle, but has less engine speed/load points. The identified state-space model is then used to develop a tunable cost function that simultaneously minimizes NOx emissions and urea usage. The cost function is quadratic and univariate, thus the minimum can be computed analytically. We show the performance of the closed-loop controller in using a reduced-order discrete SCR simulator developed at MTU. Our experiments with the surrogate HDD-FTP data show that the strategy developed in this paper can be used to identify performance bounds for urea dose controllers.

diesel, emmissions, control, environment, modeling↗
NASA NTRS1972

Bounded state space

This investigation is divided functionally into three different areas: (1) study of bounded state space, (2) nonlinear smoothing theory, and (3) system identification. (1) Study of bounded state space: necessary and sufficient conditions for an optimal control are obtained for a bounded state space optimal control problem. The difficulty of determining the so-called jump conditions is eliminated; however, the problem of determining the points where the response either enters or leaves the boundary still remains unsolved. (2) Nonlinear smoothing theory: nonlinear fixed-interval, fixed-point and fixed-lag smoothing of a random signal generated by a stochastic differential equation are investigated. Results on the asymptotic stability of a linear constant-parameter fixed-interval smoothing filter are obtained. (3) System identification: a particular stochastic modelling problem is solved. An Ito stochastic integral equation is used to mathematically model a black box having multiple inputs and multiple outputs. A new method for identifying system parameters is presented.

Eyman, E. D.↗
NASA NTRS1977

Simplified unsteady aerodynamic concepts, with application to parameter estimation

A simplified aerodynamic force model based on the physical principle of Prandtl's lifting line theory and trailing vortex concept has been developed to account for unsteadiness in the aircraft dynamics. The wake is assumed to be compressed to a single shed vortex element of appropriate strength moving downstream at a speed sufficient to approximate the Wagner function. Results are presented illustrating the ability of the simplified theory to duplicate exact solutions in unsteady aerodynamics. Further, consideration is given to the utility of the model in a parameter identification application.

Wells, W. R.↗
NASA NTRS1979

Millimeter wave satellite concepts. Volume 1: Executive summary

The objectives of the program were: (1) development of methodology based on the technical requirements of potential services that might be assigned to millimeter wave bands for identifying the viable and appropriate technologies for future NASA millimeter research and development programs, and (2) testing of this methodology with user applications and services. The scope of the program included the entire communications network, both ground and space subsystems. The reports include: (1) cost, weight, and performance models for the subsystems, (2) conceptual design for point-to-point and broadcast communications satellites, (3) analytic relationships between subsystem parameters and an overall link performance, (4) baseline conceptual systems, (5) sensitivity studies, (6) model adjustment analyses, (7) identification of critical technologies and their risks, (8) brief R&D program scenarios for the technologies judged to be moderate or extensive risks.

Hilsen, N. B.↗
NASA NTRS1980

Solar-pumped gas laser development

A survey of gas properties through detailed kinetic models led to the identification of critical gas parameters for use in choosing appropriate gas combinations for solar pumped lasers. Broadband photoabsorption in the visible or near UV range is required to excite large volumes of gas and to insure good solar absorption efficiency. The photoexcitation density is independent of the absorption bandwidth. The state excited must be a metastable state which is not quenched by the parent gas. The emission bandwidth must be less than 10 A to insure lasing threshold over reasonable gain lengths. The system should show a high degree of chemical reversibility and an insensitivity to increasing temperature. Other properties such as good quantum efficiency and kinetic efficiency are also implied. Although photoexcitation of electronic vibrational transitions is considered as a possible system if the emission bands sufficiently narrow, it appears that photodissociation into atomic metastables is more likely to result in a successful solar pumped laser system.

Wilson, J. W.↗
NASA NTRS1985

Simulated Microgravity as a Probe for Understanding the Mechanisms of Early Pattern Specification

Early pattern specification (e.g., axial structure morphogenesis, doreal ventral polarity, etc.) is monitored in amphibian eggs which were subjected to microgravity simulation by constant rotation on a horizontal clinostat. In contrast to previous clinostat experiments, rotation is initiated either prior to fertilization or immediately thereafter. Large proportions of clinostated eggs developed normal axial structures. A model which employs a multiple set of signals for specifying early pattern is discussed. Effects of microgravity simulation on the earliest post fertilization pattern specification event dorsal/ventral polarization is analyzed in detail. Other models are developed and they are discussed. As a general mechanism for explaining the manner in which regional developmental patterns emerge from the initial, radially symmetrial egg, the density compartment model is described. The identification of the various zones or compartments of egg cytoplasm using inverted eggs is explained.

Neff, A. W.↗
NASA NTRS1985

Control of flexible structures

The requirements for future space missions indicate that many of these spacecraft will be large, flexible, and in some applications, require precision geometries. A technology program that addresses the issues associated with the structure/control interactions for these classes of spacecraft is discussed. The goal of the NASA control of flexible structures technology program is to generate a technology data base that will provide the designer with options and approaches to achieve spacecraft performance such as maintaining geometry and/or suppressing undesired spacecraft dynamics. This technology program will define the appropriate combination of analysis, ground testing, and flight testing required to validate the structural/controls analysis and design tools. This work was motivated by a recognition that large minimum weight space structures will be required for many future missions. The tools necessary to support such design included: (1) improved structural analysis; (2) modern control theory; (3) advanced modeling techniques; (4) system identification; and (5) the integration of structures and controls.

Russell, R. A.↗
NASA NTRS1987

Dynamic performance of squeeze-film bearings

Earlier work has shown that oil-film forces can be modelled by linear coefficients. Identification techniques were used to generate numerical values for these coefficients. This paper has shown the invalidity of applying the perturbation techniques normally used in bearing studies to derive expressions for linearized coefficients to represent a cavitated oil-film. An alternative approach was developed based upon energy techniques to obtain estimates for linearized coefficients. Some current work being undertaken suggests that an alternative analytical approach is possible. These results will be reported in due course.

Burrow, C. R.↗