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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 1,423 records · Page 79
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Using AGNESS (A Generalized Network-based Expert System Shell) for matching images

The image correspondence problem is considered the most difficult step in both stereo and motion analysis. Stereo vision is useful in determining the 3-D positions of points on visible surface in a scene. Motion analysis is useful in determining the spatial and temporal relationships of objects in an environment. Besides stereo and motion analysis, there is the image correspondence problem. Most of this work is based on point or local area properties of the observed gray level values in 2-D images. A global and general approach to this problem is described by using a knowledge-based system. The knowledge it uses consists of both physical properties and spatial relationships of the edges and regions extracted from the given images. The physical component depends on features of the edge or region) in isolation. The spatial component involves the set of edges and regions adjacent to a given edge (or region) of the first image and the set of edges and regions adjacent to each potentially matching edge (or region) of the second image; thus the spatial context of each edge or region is considered. A computational network is used to represent this knowledge, it allows the computation of the likelihood of matching two edges or regions with logical and heuristic operators. An expert system shell called AGNESS (A Generalized Network-based Expert System Shell) is used to build a prototype system.

Pong, Ting-Chuen↗
NASA NTRS1993

An accelerated training method for back propagation networks

The principal objective is to provide a training procedure for a feed forward, back propagation neural network which greatly accelerates the training process. A set of orthogonal singular vectors are determined from the input matrix such that the standard deviations of the projections of the input vectors along these singular vectors, as a set, are substantially maximized, thus providing an optimal means of presenting the input data. Novelty exists in the method of extracting from the set of input data, a set of features which can serve to represent the input data in a simplified manner, thus greatly reducing the time/expense to training the system.

Shelton, Robert O.↗
NASA NTRS2010

Siderophilic Cyanobacteria for the Development of Extraterrestrial Photoautotrophic Biotechnologies

In-situ production of consumables (mainly oxygen) using local resources (In-Situ Resource Utilization-ISRU) will significantly facilitate current plans for human exploration and settlement of the solar system, starting with the Moon. With few exceptions, nearly all technologies developed to date have employed an approach based on inorganic chemistry. None of these technologies include concepts for integrating the ISRU system with a bioregenerative life support system and a food production system. Therefore, a new concept based on the cultivation of cyanobacteria (CB) in semi-closed biogeoreactor, linking ISRU, a biological life support system, and food production, has been proposed. The key feature of the biogeoreactor is to use lithotrophic CB to extract many needed elements such as Fe directly from the dissolved regolith and direct them to any technological loop at an extraterrestrial outpost. Our studies showed that siderophilic (Fe-loving) CB are capable to corrode lunar regolith stimulants because they secrete chelating agents and can tolerate [Fe] up to 1 mM. However, lunar and Martian environments are very hostile (very high UV and gamma-radiation, extreme temperatures, deficit of water). Thus, the selection of CB species with high potential for extraterrestrial biotechnologies that may be utilized in 15 years must be sponsored by NASA as soon as possible. The study of the genomes of candidate CB species and the metagenomes of the terrestrial environments which they inhabit is critical to make this decision. Here we provide preliminary results about peculiarities of the genomes of siderophilic CB revealed by analyzing the genome of siderophilic cyanobacterium JSC-1 and the metagenome of iron depositing hot spring (IDHS) Chocolate Pots (Yellowstone National Park, Wyoming, USA). It has been found that IDHS are richer with ferrous iron than the majority of hot springs around the world. Fe2+ is known to increase the magnitude of oxidative stress in prokaryotes through so called Fenton reaction. It is not surprising therefore that the CB inhabiting IDHS have larger sets of the proteins involved in the maintenance of Fe homeostasis and oxidative stress protection than non-siderophilic CB. This finding combined with our earlier results about the ability of some siderophilic CB to utilize chemical elements released from analogs of lunar and Martian regolith make them the most advanced candidates to be employed in advanced extraterrestrial biotechnologies.

Brown, I. I.↗
NASA NTRS2017

GC13I-0860: An Assessment of Surface Water Detection Methods for the Tahoua Region, Niger

The recent release of several global surface water datasets derived from remotely sensed data has allowed for unprecedented analysis of the earth's hydrologic processes at a global scale. However, some of these datasets fail to identify important sources of surface water, especially small ponds, in the Sahel, an arid region of Africa that forms a border zone between the Sahara Desert to the north, and the savannah to the south. These ponds may seem insignificant in the context of wider, global-scale hydrologic processes, but smaller sources of water are important for local and regional hydrologic assessments. Particularly, these smaller water bodies are significant sources of hydration and irrigation for nomadic pastoralists and smallholder farmers throughout the Sahel. For this study, several methods of identifying surface water from Landsat 8 OLI, Sentinel 1 SAR, Sentinel 2 MSI, and Planet Dove data were compared to determine the most effective means of delineating these features in the Tahoua Region of Niger. The Automated Water Extraction Index (AWEInsh) had the best performance when validated against very high resolution Digital Globe imagery, with an overall accuracy of 98.6%. This study reiterates the importance of region-specific algorithms and suggests that the AWEInsh method may be the best for delineating surface water in the Sahelian ecozone, likely due to the nature of the exposed geology and lack of dense green vegetation.

Herndon, Kelsey E.↗
NASA NTRS2019

Analysis of WFPC-2 Core Samples for MMOD Discrimination

An examination of the Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC-2) radiator assembly was conducted at NASA Goddard Space Flight Center during the summer of 2009. Immediately apparent was the predominance of impact features, identified as simple or complex craters, resident only in the thermal paint layer; similar features were observed during a prior survey of the WFPC-1 radiator. Larger impact features displayed spallation zones, darkened areas, and other features not observed in impacts onto bare surfaces. Craters were extracted by coring the radiator in the NASA Johnson Space Center’s Space Exposed Hardware cleanroom and were subsequently examined using scanning electron microscopy/energy dispersive X-ray spectroscopy to determine the likely origin, e.g., micrometeoritic or orbital debris, of the impacting projectile. Recently, a selection of large cores was re-examined using a new technique developed to overcome some limitations of traditional crater imaging and analysis. This technique, motivated by thin section analysis, examines a polished, lateral surface area revealed by cross-sectioning the core sample. This paper reviews the technique, the classification rubric as extended by this technique, and results to date.

Anz-Meador, P.↗
NASA NTRS2023

BOLT II Forebody Surface Measurement Analysis

Surface impression molds of the nosetip/forebody interface, discrete tripping elements, and other surface imperfections were formed on the BOLT II flight vehicle prior to its launch in March 2022. The silicon-rubber molds cast on the interface between the nickel nosetip and the stainless steel forebody were measured using a 3D optical measurement system and a stylus profilometer and were evaluated for step direction and height. The step around the nosetip/forebody interface was found to vary in both magnitude and direction, but values were generally modest with most samples below 60 μm across the span and only two samples, both cast in the gutter, with step values larger than 100 μm. Impressions of the secondary-side tripping elements were strictly scanned with the optical device and similar methods were used to calculate trip height as step height. The measured centerline trip height was 2623 ±12 μm, while the leading-edge, quadrant 2 and 3, trip heights were 897 ±5 μm and 891 ±18 μm, respectively. Surface imperfections on the nose and forebody were also evaluated. Surface roughness values and spectra were estimated, and profiles were extracted across the imperfections to quantify the magnitude of those features.

Trip height↗
NASA NTRSDate not supplied

Enabling a Weight Efficient Power System for an Electrified Turbofan Through Gearbox Design and Control

Electrified Aircraft Propulsion (EAP) concepts could enable various benefits through a variety of use-cases. Benefits are sought in the form of reduced fuel burn and emissions. Many of these concepts involve the electrification of gas turbine engines. Electrification is accomplished through the integration of electric machines (EMs) with the engine shafts, providing the ability to inject and/or extract power as desired. Energy storage is also a common feature. An often-overlooked feature of the analysis is the means of integrating the EMs with the engine shafts. A trivial solution is to allow each shaft to have its own dedicated EM through independent geartrains. However, non-trivial mechanical integration solutions could provide benefits when considered in coordination with control logic to manage the operation of the propulsion system. Here, such a solution is considered and is shown to have the potential to reduce weight for a relevant conceptual electrified propulsion system. Weight saving benefits are demonstrated for various EAP use-cases. In particular, the mild hybrid application was shown to benefit from a power system weight reduction of 47% and an overall system weight reduction of 29%.

Hybrid Electric Propulsion↗
NASA NTRSDate not supplied

Enabling a Weight Efficient Power System for an Electrified Turbofan Through Gearbox Design and Control

Electrified Aircraft Propulsion (EAP) concepts could enable various benefits through a variety of use-cases. Benefits are sought in the form of reduced fuel burn and emissions. Many of these concepts involve the electrification of gas turbine engines. Electrification is accomplished through the integration of electric machines (EMs) with the engine shafts, providing the ability to inject and/or extract power as desired. Energy storage is also a common feature. An often-overlooked feature of the analysis is the means of integrating the EMs with the engine shafts. A trivial solution is to allow each shaft to have its own dedicated EM through independent geartrains. However, non-trivial mechanical integration solutions could provide benefits when considered in coordination with control logic to manage the operation of the propulsion system. Here, such a solution is considered and is shown to have the potential to reduce weight for a relevant conceptual electrified propulsion system. Weight saving benefits are demonstrated for various EAP use-cases. In particular, the mild hybrid application was shown to benefit from a power system weight reduction of 47% and an overall system weight reduction of 29%.

Hybrid Electric Propulsion↗
DOE OSTI2022

Support Vector Machines for Classification of Direct Energy Deposition Standoff Distance for Improved Process Control

A critical factor in the implementation of direct energy deposition is the ability to maintain the standoff distance between the nozzle and the build surface, as this influences powder capture efficiency and overall part quality. Due to process-related variations, layer height may vary, causing unintended variation in standoff distance and poor build quality. While prior work has utilized contact probing to qualify standoff distance during processing, in situ methods for qualification of standoff distance are of major interest. The present work seeks to understand efficacy of image-based methods for classifying standoff distance variation in real-time using support vector machines (SVMs). It was hypothesized that the size of the melt pool and the amount of spatter will have significant correlations with deviations in the standoff distance; thus, SVMs were used on a dataset that is comprised of morphological features of melt pool size and image entropy. The SVM model was used to classify melt pool images into categories according to standoff distance variation from nominal. K-folds cross validation was used to find the optimal hyperparameters for the SVM model. To understand the impact of the selected features on the classification performance and inference speed, multiple models were trained with differing numbers of included features. Results for classification score, inference time, and image preprocessing/feature extraction from these data are reported. The present results show that the SVM model was able to predict the standoff distance classification with an accuracy of 97 percent and a speed of 0.122 s per image, making it a viable solution for real-time control of standoff distance.

Klesmith, Zoe↗
DOE OSTI2023

Multiphysics Analysis of the MSRE Experiment Using Griffin-SAM Coupled Code System

Molten salt reactors (MSRs) with flowing fuel have the unique feature of utilizing the fuel salt for heat generation and extraction at the same time since the fuel salt is circulating through the whole primary loop of the reactor. This movement of the fuel salt results in a partial decay of the delayed neutron precursors (DNPs) outside the core and corresponding redistribution in the active core region. To capture this phenomenon accurately, neutronics and thermal hydraulics computational tools need to be modified to handle the movement of the DNPs and their decay. Idaho and Argonne National Laboratories are actively working on developing neutronics and thermal hydraulics tools to model MSRs with flowing fuel. The neutronics code Griffin and the thermal hydraulics code SAM were extended to handle flowing fuel with the drift of the DNPs under the MOOSE framework. In this work, a simplified Multiphysics model of the Molten Salt Reactor Experiment (MSRE) is developed and utilized to perform steady-state and transient analyses. The MSRE experiments were designed to show the impact of the DNPs losses on core reactivity. The following section provides a description of the MSRE experiment with the core main parameters used to develop the model. Then, the developed Multiphysics model of the MSRE is presented. Finally, steady-state verification tests and unprotected loss of flow transient tests are discussed followed by a summary and conclusions.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2023

CNRS Molten Salt Reactor Benchmark Analysis Using Griffin-Pronghorn Coupled Multi-physics Code System

Molten salt reactors (MSRs) with flowing fuel have the unique feature of utilizing the fuel salt for heat generation and extraction at the same time, since the fuel salt is circulating through the whole primary loop. This movement of fuel salt results in a partial decay of the delayed neutron precursors (DNPs) outside the core and the corresponding redistribution of the DNPs in the active region of the core. To capture this effect, neutronics and thermal-hydraulics (T/H) codes need to be able to handle the movement of DNPs and their decay [1, 2]. Idaho National Laboratory (INL) is actively working on developing the neutronics and T/H codes to model the MSRs with flowing fuel. As one of the efforts, the neutronics code Griffin [3] and the T/H code Pronghorn [4] that are built upon the MOOSE framework [5] have been extended to handle the flowing fuel involving the drift of DNPs, and this capability is being tested and verified with MSR benchmark problems including the CNRS benchmark problem [6]. Additionally, a multi-physics analysis of the molten salt reactor experiment (MSRE) is being conducted to verify and validate the codes against available experimental data [7]. This work presents the analysis of the CNRS benchmark problem using the Griffin-Pronghorn coupled multi-physics code system of INL. Both steady-state and transient problems are analyzed, and the results are compared with those of other participants presented in [6]. The following section provides a description of the benchmark, along with input parameters and observables for each step. Then, the results for each step are presented in comparison with other participants’ results, followed by summary and conclusion.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2025

Hydropower Fish Passage Webmap

The National Fish Passage Webmap application provides an environment that allows users to visualize information information on fish passage facility existence, type, and direction at hydropower developments across the conterminous United States. It was developed through collaborative partnerships with fish passage engineers and biologists at both the US Fish and Wildlife Service (USFWS) and the National Marine Fisheries Service (NMFS), and hydropower experts at the Low Impact Hydropower Institute (LIHI). Data on fish passage facilities at hydropower features were compiled from numerous sources including published and non-published datasets, published reports, email communications with federal and state resource managers and hydropower operators, and by extracting information from regulatory documents within the FERC eLibrary. The number of sources for a given feature varied, which occasionally resulted in conflicting information regarding the existence of fish passage facilities or in the type or sub-type of passage technologies. Such discrepancies were reviewed and resolved individually, based on the weight of evidence or, when available, on direct observations from information providers or aerial imagery.

13 HYDRO ENERGY↗
DOE OSTI2013

Peptidome analysis of human skim milk in term and preterm milk

Highlights: •A method was developed for preparation of peptide extracts from human milk. •Analysis of the extracts by LC–MS/MS resulted in the detection of 1000–3000 peptide-like features. •419 Peptides were identified by LC–MS/MS from 34 proteins. •Isotope dimethyl labeling analysis revealed 41 peptides differentially expressed. -- Abstract: The abundant proteins in human milk have been well characterized and are known to provide nutritional, protective, and developmental advantages to both term and preterm infants. Due to the difficulties associated with detection technology of the peptides, the expression of the peptides present in human milk is not known widely. In recent years, peptidome analysis has received increasing attention. In this report, the analysis of endogenous peptides in human milk was done by mass spectrometry. A method was also developed by our researchers, which can be used in the extraction of peptide from human milk. Analysis of the extracts by LC–MS/MS resulted in the detection of 1000–3000 Da peptide-like features. Out of these, 419 peptides were identified by MS/MS. The identified peptides were found to originate from 34 proteins, of which several have been reported. Analysis of the peptides’ cleavage sites showed that the peptides are cleaved with regulations. This may reflect the protease activity and distribution in human body, and also represent the biological state of the tissue and provide a fresh source for biomarker discovery. Isotope dimethyl labeling analysis was also used to test the effects of premature delivery on milk protein composition in this study. Differences in peptides expression between breast milk in term milk (38–41 weeks gestation) and preterm milk (28–32 weeks gestation) were investigated in this study. 41 Peptides in these two groups were found expressed differently. 23 Peptides were present at higher levels in preterm milk, and 18 were present at higher levels in term milk.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

High Brightness Room Temperature III-Nitride Based Single Photon Source

Single photon sources (SPS) are quantum light sources where photons are emitted one at a time instead of randomly (e.g. lasers) or in a bunch (e.g. thermal) that can significantly impact quantum information science (computing and secure communications) and quantum metrology. Some highly desirable features of SPS are low second order correlation (g 2 ),controllable emission, electrically injected room temperature operation with high photon rate, high extraction efficiency and controllable directionality. Approaches taken thus far using different material systems have only addressed a subset of these features. III-nitride based approach offers a clear pathway to deterministic, room temperature (R.T.), electrically injected practical SPS as one can potentially also leverage the knowledge and technology from the light emitting diode (LED) world. Here we will describe a hybrid approach wherein a TiO2 based photonic crystal (PC) cavity is fabricated around an InGaN quantum dot (QD) embedded nanoscale post deterministically placed inside a photonic crystal cavity. This project takes the initial steps necessary to achieve a practical, compact SPS. We have used finite difference time domain simulations to optimize the cavity design to achieve high quality factor, mode overlap with QD and high extraction. We have fabricated InGaN quantum dots using a top-down approach involving dry etch and photoelectrochemical etch followed by electron beam lithography based nanofabrication of photonic crystal cavities.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Modeling occupancy distribution in large spaces with multi-feature classification algorithm

We present that occupancy information enables robust and flexible control of heating, ventilation, and air-conditioning (HVAC) systems in buildings. In large spaces, multiple HVAC terminals are typically installed to provide cooperative services for different thermal zones, and the occupancy information determines the cooperation among terminals. However, a person count at room-level does not adequately optimize HVAC system operation due to the movement of occupants within the room that creates uneven load distribution. Without accurate knowledge of the occupants’ spatial distribution, the uneven distribution of occupants often results in under-cooling/heating or over-cooling/heating in some thermal zones. Therefore, the lack of high-resolution occupancy distribution is often perceived as a bottleneck for future improvements to HVAC operation efficiency. To fill this gap, this study proposes a multi-feature k-Nearest-Neighbors (k-NN) classification algorithm to extract occupancy distribution through reliable, low-cost Bluetooth Low Energy (BLE) networks. An on-site experiment was conducted in a typical office of an institutional building to demonstrate the proposed methods, and the experiment outcomes of three case studies were examined to validate detection accuracy. One method based on City Block Distance (CBD) was used to measure the distance between detected occupancy distribution and ground truth and assess the results of occupancy distribution. Finally, the results show the accuracy when CBD = 1 is over 71.4% and the accuracy when CBD = 2 can reach up to 92.9%.

42 ENGINEERING↗
DOE OSTI2023

gRNA-SeqRET: a universal tool for targeted and genome-scale gRNA design and sequence extraction for prokaryotes and eukaryotes

High-throughput genetic screening is frequently employed to rapidly associate gene with phenotype and establish sequence-function relationships. With the advent of CRISPR technology, and the ability to functionally interrogate previously genetically recalcitrant organisms, non-model organisms can be investigated using pooled guide RNA (gRNA) libraries and sequencing-based assays to quantitatively assess fitness of every targeted locus in parallel. To aid the construction of pooled gRNA assemblies, we have developed an in silico design workflow for gRNA selection using the gRNA Sequence Region Extraction Tool (gRNA-SeqRET). Built upon the previously developed CCTop, gRNA-SeqRET enables automated, scalable design of gRNA libraries that target user-specified regions or whole genomes of any prokaryote or eukaryote. Additionally, gRNA-SeqRET automates the bulk extraction of any regions of sequence relative to genes or other features, aiding in the design of homology arms for insertion or deletion constructs. We also assess in silico the application of a designed gRNA library to other closely related genomes and demonstrate that for very closely related organisms Average Nucleotide Identity (ANI) > 95% a large fraction of the library may be of relevance. The gRNA-SeqRET web application pipeline can be accessed at https://grna.jgi.doe.gov. The source code is comprised of freely available software tools and customized Python scripts, and is available at https://bitbucket.org/berkeleylab/grnadesigner/src/master/ under a modified BSD open-source license (https://bitbucket.org/berkeleylab/grnadesigner).

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

Identifying local structural states in atomic imaging by computer vision

Abstract The availability of atomically resolved imaging modalities enables an unprecedented view into the local structural states of materials, which manifest themselves by deviations from the fundamental assumptions of periodicity and symmetry. Consequently, approaches that aim to extract these local structural states from atomic imaging data with minimal assumptions regarding the average crystallographic configuration of a material are indispensable to advances in structural and chemical investigations of materials. Here, we present an approach to identify and classify local structural states that is rooted in computer vision. This approach introduces a definition of a structural state that is composed of both local and nonlocal information extracted from atomically resolved images, and is wholly untethered from the familiar concepts of symmetry and periodicity. Instead, this approach relies on computer vision techniques such as feature detection, and concepts such as scale invariance. We present the fundamental aspects of local structural state extraction and classification by application to simulated scanning transmission electron microscopy images, and analyze the robustness of this approach in the presence of common instrumental factors such as noise, limited spatial resolution, and weak contrast. Finally, we apply this computer vision-based approach for the unsupervised detection and classification of local structural states in an experimental electron micrograph of a complex oxides interface, and a scanning tunneling micrograph of a defect-engineered multilayer graphene surface.

74 ATOMIC AND MOLECULAR PHYSICS↗