Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “time migration”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Competing endogenous RNA network associated with oxygen-induced retinopathy: Expression of the network and identification of the MALAT1/miR-124–3p/EGR1 regulatory axis

Retinopathy of prematurity (ROP) is a severe retinal dysfunction in prematurely born babies. The relationship between non-coding RNAs and retinopathy of prematurity (ROP) remain unclear. Microarray analysis of lncRNAs, miRNAs, and mRNAs was conducted in a mouse model of ROP. A competing endogenous RNA (ceRNA) network was constructed. The relationship among MALAT1, miR-124–3p, and Early growth response protein 1 (EGR1) was assessed in hypoxia-induced primary human umbilical vein endothelial cells (HUVECs) and ROP mouse model. In the study, we found 2252 lncRNAs, 1239 mRNAs, and 36 miRNAs were differentially regulated. ceRNA network consisting of 21 lncRNAs, 10 miRNAs, and 19 mRNAs was established. Of the most down-regulated miRNAs, miR-124–3p was selected for additional study. miR-124–3p ceased the migration and proliferation of primary HUVECs in hypoxic conditions, and directly suppressed EGR1. Additionally, MALAT1 directly sponged miR-124–3p. Knockdown of MALAT1 decreased EGR1 expression and inhibited the migration and proliferation of primary HUVECs in hypoxia. Furthermore, these changes were rescued by depletion of miR-124–3p. In vivo, intravitreal injection of miR-124–3p, shMALAT1 decreased EGR1 expression and markedly suppressed retinal neovascularization in OIR models. Intravitreal injection of shMALAT1 and miR-124–3p antagomir at the same time can promote retinal neovascularization, which reversed the suppression of retinal neovascularization functioned by shMALAT1. In conclusion, the expression profiles of lncRNAs and miRNAs and the ceRNA network in a mouse model of ROP may be indicative of the underlying mechanisms of retinal angiogenesis and neural activity. The MALAT1/miR-124–3p/EGR1 regulatory axis is partly responsible for retinal neovascularization, which may provide a novel theoretical basis for the pathogenesis of ROP.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2020

Alcohol-Induced Low-Temperature Blockage of Supported-Metal Catalysts for Enhanced Catalysis

The partial or complete blockage of active sites of metal nanoparticles (NPs) on supported-metal catalysts has been of interest for tuning the stability, selectivity, and rate of reactions. In this study, we show that Au-sites in Au/TiO 2 surprisingly become blocked upon treatment in common alcohols (2-propanol and methanol), with 2-propanol causing a greater extent of blockage. Nearly 95% of Au-sites are covered after treatment in 2-propanol at room temperature, followed by desorption at 150 °C. Infrared spectroscopy of CO adsorption unambiguously confirms the occurrence of this phenomenon. Electron energy loss spectroscopy (EELS), temperature-programmed desorption (TPD), Raman spectroscopy, and DFT simulations suggest that the formation of carbon deposits from 2-propanol decomposition and/or the migration of a TiO x layer over the supported NPs may be responsible for the blockage of Au-sites. Nearly full coverage of Au NPs after treatment in 2-propanol led to negligible activity for catalytic CO oxidation, whereas partial retraction of the overlayer led to enhanced activity with time-on-stream, suggesting a self-activating catalytic performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Dissecting protein tyrosine phosphatase signaling by engineered chemogenetic control of its activity

Protein tyrosine phosphatases (PTPases) are critical mediators of dynamic cell signaling. A tool capable of identifying transient signaling events downstream of PTPases is essential to understand phosphatase function on a physiological time scale. We report a broadly applicable protein engineering method for allosteric regulation of PTPases. This method enables dissection of transient events and reconstruction of individual signaling pathways. Implementation of this approach for Shp2 phosphatase revealed parallel MAPK and ROCK II dependent pathways downstream of Shp2, mediating transient cell spreading and migration. Furthermore, we show that the N-SH2 domain of Shp2 regulates MAPK-independent, ROCK II-dependent cell migration. Engineered targeting of Shp2 activity to different protein complexes revealed that Shp2-FAK signaling induces cell spreading whereas Shp2-Gab1 or Shp2-Gab2 mediates cell migration. We identified specific transient morphodynamic processes induced by Shp2 and determined the role of individual signaling pathways downstream of Shp2 in regulating these events. Broad application of this approach is demonstrated by regulating PTP1B and PTP-PEST phosphatases.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

Analysis of land-based CSEM data for CO2 monitoring at Bell Creek, MT

Monitoring subsurface fluid migration is critical to any CO2 injection operation like enhanced oil recovery or carbon storage. The controlled-source electromagnetic (CSEM) method provides a promising low-cost, non-invasive alternative to conventional monitoring methods. To investigate the use of CSEM for monitoring CO2 injection, we are conducting a time-lapse charged well casing CSEM survey at the Bell Creek oil field. There, CO2 is injected into the reservoir for enhanced oil recovery, which also results in incidental carbon storage. From October 2017 to October 2018 we completed three field campaigns, and we plan to complete one more in July 2019. We have analyzed the signal strength and variance of the time-lapse CSEM data. Difference data signal strength well exceeds the standard deviation of the data, and it agrees with estimates of expected signal strength derived from numerical modeling. This analysis indicates that our survey can detect the change in conductivity within the reservoir due to fluid movement.

time-lapse, land CSEM, monitoring, processing↗
DOE OSTI2013

Model 9975 life extension package 3-Interim Report

Life extension package LE3 (9975-03203) has been instrumented and subjected to an elevated temperature environment for 259 weeks. During this time, the maximum fiberboard temperature was ~160 - 165 °F, and was established by a combination of internal (19 watts) and external heat sources. Several tests and parameters were used to characterize the package components. Results from these tests generally indicate agreement between this full-scale shipping package and small-scale laboratory tests on fiberboard samples. These areas of agreement include the rate of change of fiberboard weight and dimensions, and change in fiberboard thermal conductivity. Dimensional measurements of the shield indicate no consistent trend to suggest creep deformation has occurred. This is consistent with literature data that predicts a very small creep deformation for the time at temperature experienced by this package. This package provides an example of the extent to which moisture within a typical fiberboard assembly can redistribute in the presence of a temperature gradient such as might be created by a 19 watt internal heat load. The majority of water within the fiberboard migrated to the bottom layers of fiberboard, some of which eventually escaped from the package. Two conditions have developed that are not consistent with package certification requirements. The axial gap at the top of the package has increased to 1.48 inches, exceeding the 1 inch criterion. In addition, staining and/or corrosion have formed in a few spots on the drum. However, the package remains capable of performing its function.

36 MATERIALS SCIENCE↗
DOE OSTI2018

PARFUME Theory and Model Basis Report

The success of gas reactors depends upon the safety and quality of the coated particle fuel. The fuel performance modeling code PARFUME simulates the mechanical, thermal and physico-chemical behavior of fuel particles during irradiation. This report documents the theory and material properties behind vari¬ous capabilities of the code, which include: 1) various options for calculating CO production and fission product gas release, 2) an analytical solution for stresses in the coating layers that accounts for irradiation-induced creep and swelling of the pyrocarbon layers, 3) a thermal model that calculates a time-dependent temperature profile through a pebble bed sphere or a prismatic block core, as well as through the layers of each analyzed particle, 4) simulation of multi-dimensional particle behavior associated with cracking in the IPyC layer, partial debonding of the IPyC from the SiC, particle asphericity, and kernel migration (or amoeba effect), 5) two independent methods for determining particle failure probabilities, 6) a model for calculating release-to-birth (R/B) ratios of gaseous fission products that accounts for particle failures and uranium contamination in the fuel matrix, and 7) the evaluation of an accident condition, where a particle experiences a sudden change in temperature following a period of normal irradiation. The accident condi¬tion entails diffusion of fission products through the particle coating layers and through the fuel matrix to the coolant boundary. This document represents the initial version of the PARFUME Theory and Model Basis Report. More detailed descriptions will be provided in future revisions.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2016

Tatooine's future: the eccentric response of Kepler's circumbinary planets to common-envelope evolution of their host stars

Inspired by the recent Kepler discoveries of circumbinary planets orbiting nine close binary stars, we explore the fate of the former as the latter evolve off the main sequence. We combine binary star evolution models with dynamical simulations to study the orbital evolution of these planets as their hosts undergo common-envelope (CE) stages, losing in the process a tremendous amount of mass on dynamical timescales. Five of the systems experience at least one Roche-lobe overflow and CE stage (Kepler-1647 experiences three), and the binary stars either shrink to very short orbits or coalesce; two systems trigger a double-degenerate supernova explosion. Kepler’s circumbinary planets predominantly remain gravitationally bound at the end of the CE phase, migrate to larger orbits, and may gain significant eccentricity; their orbital expansion can be more than an order of magnitude and can occur over the course of a single planetary orbit. The orbits these planets can reach are qualitatively consistent with those of the currently known post-CE, eclipse-time variations circumbinary candidates. Our results also show that circumbinary planets can experience both modes of orbital expansion (adiabatic and nonadiabatic) if their host binaries undergo more than one CE stage; multiplanet circumbinary systems like Kepler-47 can experience both modes during the same CE stage. Additionally, unlike Mercury orbiting the Sun, a circumbinary planet with the same semimajor axis can survive the CE evolution of a close binary star with a total mass of 1 M{sub ⊙}.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2005

STS-114: Discovery L-2 Countdown Status Briefing

George Diller of NASA Public Affairs hosted this briefing. Pete Nickolenko, NASA Test Director; Scott Higgenbotham, STS-114 Payload-Mission Manager; Cathy Winters, Shuttle Weather Officer were present. Pete reports his team has completed the avionics system check ups, servicing of the cryogenic tanks will take about seven hours that day, and will perform engine system checks and pad close outs come evening. Pete also summarized other standard close out activities: check ups of the Orbiter and ground communications network, rotary service, structure retraction, and external tank load (ETL). Pete reported that the mission will be 12 days with two weather contingency days, and end of mission landing scheduled at Kennedy Space Center (KSC) at approximately 11:00 in the morning, Eastern time on July 25th. Scott briefly reported that all hardware is on board Discovery, closed out, and ready to fly. Cathy reported that hurricane Dennis moved to the North and looking forward to launch. She mentioned of a new hurricane looming and will be named Emily, spotted some crosswinds which will migrate to the west, there is 30% probability weather prohibiting launch. Cathy further gave current weather forecast supported with charts: the Launch Forecast, Tanking Forecast, SRB (Shuttle Solid Rocket Booster) Forecast, CONUS and TAL Launch Sites Forecast, and with 24 hours and 48 hours turn around plan. Launch constraints, weather, crosswinds, cloud cover, ground imagery system, launch countdown, launch crews, mission management simulations, launch team simulations were topics covered with the News Media.

Source record↗
NASA NTRS2010

Modelling the Future Hydroclimatology of the Lower Fraser River and its Impacts on the Spawning Migration Survival of Sockeye Salmon

Short episodic high temperature events can be lethal for migrating adult Pacific salmon (Oncorhynchus spp.). We downscaled temperatures for the Fraser River, British Columbia to evaluate the impact of climate warming on the frequency of exceeding thermal thresholds associated with salmon migratory success. Alarmingly, a modest 1.0 C increase in average summer water temperature over 100 years (1981-2000 to 2081-2100) tripled the number of days per year exceeding critical salmonid thermal thresholds (i.e. 19.0 C). Refined thresholds for two populations (Gates Creek and Weaver Creek) of sockeye salmon (Oncorhynchus nerka) were defined using physiological constraint models based on aerobic scope. While extreme temperatures leading to complete aerobic collapse remained unlikely under our warming scenario, both populations were increasingly forced to migrate upriver at reduced levels of aerobic performance (e.g. in 80% of future simulations, => 90% of salmon encountered temperatures exceeding population specific thermal optima for maximum aerobic scope; T(sub opt)) = 16.3 C for Gates Creek and T(sub sopt)=14.5 C for Weaver Creek). Assuming recent changes to river entry timing persist, we also predicted dramatic increases in the probability of freshwater mortality for Weaver Creek salmon due to reductions in aerobic, and general physiological, performance (e.g. in 42% of future simulations =>50% of Weaver Creek fish exceeded temperature thresholds associated with 0 - 60% of maximum aerobic scope). Potential for adaptation via directional selection on run-timing was more evident for the Weaver Creek population. Early entry Weaver Creek fish experienced 25% (range: 15 - 31%) more suboptimal temperatures than late entrants, compared with an 8% difference (range: 0 - 17%) between early and late Gates Creek fish. Our results emphasize the need to consider daily temperature variability in association with population-specific differences in behaviour and physiological constraints when forecasting impacts of climate change on migratory survival of aquatic species.

Hague, M. J.↗
NASA NTRSDate not supplied

Using OPeNDAP In The Cloud to Connect NASA Data Centers and Support Open Data Access

NASA DAACs (Distributed Active Archive Centers), including the Goddard Earth Sciences Data Information and Services Center (GES DISC), are currently transitioning from on-premises servers to a shared Earthdata Cloud in order to build more interoperability, cross-collaboration, and streamlined services between their data centers. Migrating its on-premises OPeNDAP service to the cloud is a critical component of making this interconnectedness between NASA DAACs possible. To improve their cloud services, GES DISC is leveraging open-source platforms like Github to collect user feedback, create use cases, and develop resources to enable real-time learning for users about OPeNDAP in the cloud. This presentation gives an overview of the OPeNDAP in the cloud, resources developed to access this service, and considerations for improved user guidance and experience to further support NASA's commitment to the Open-Source Science Initiative (OSSI).

Christopher Battisto↗
DOE OSTI2022

Snowmass Computational Frontier: Topical Group Report on Experimental Algorithm Parallelization

The substantial increase in data volume and complexity expected from future experiments will require significant investment to prepare experimental algorithms. These algorithms include physics object reconstruction, calibrations, and processing of observational data. In addition, the changing computing architecture landscape, which will be primarily composed of heterogeneous resources, will continue to pose major challenges with regard to algorithmic migration. Portable tools need to be developed that can be shared among the frontiers (e.g., for code execution on different platforms) and opportunities, such as forums or cross-experimental working groups, need to be provided where experiences and lessons learned can be shared between experiments and frontiers. At the same time, individual experiments also need to invest considerable resources to develop algorithms unique to their needs (e.g., for facilities dedicated to the experiment), and ensure that their specific algorithms will be able to efficiently exploit external heterogeneous computing facilities. Common software tools represent a cost-effective solution, providing ready-to-use software solutions as well as a platform for R&D work. These are particularly important for small experiments which typically do not have dedicated resources needed to face the challenges imposed by the evolving computing technologies. Workforce development is a key concern across frontiers and experiments, and additional support is needed to provide career opportunities for researchers working in the field of experimental algorithm development. Finally, cross-discipline collaborations going beyond high-energy physics are a key ingredient to address the challenges ahead and more support for such collaborations needs to be created. This report targets future experiments, observations and experimental algorithm development for the next 10-15 years.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Phenyl radical + propene: a prototypical reaction surface for aromatic-catalyzed 1,2-hydrogen-migration and subsequent resonance-stabilized radical formation

The C 9 H 11 potential energy surface (PES) was experimentally and theoretically explored because it is a relatively simple, prototypical alkylaromatic radical system. Although the C 9 H 11 PES has already been extensively studied both experimentally (under single-collision and thermal conditions) and theoretically, new insights were made in this work by taking a new experimental approach: flash photolysis combined with time-resolved molecular beam mass spectrometry (MBMS) and visible laser absorbance. The C 9 H 11 PES was experimentally accessed by photolytic generation of the phenyl radical and subsequent reaction with excess propene (C 6 H 5 + C 3 H 6 ). The overall kinetics of C 6 H 5 + C 3 H 6 was measured using laser absorbance with high time-resolution from 300 to 700 K and was found to be in agreement with earlier measurements over a lower temperature range. Five major product channels of C 6 H 5 + C 3 H 6 were observed with MBMS at 600 and 700 K, four of which were expected: hydrogen (H)-abstraction (measured by the stable benzene, C 6 H 6 , product), methyl radical (CH 3 )-loss (styrene detected), H-loss (phenylpropene isomers detected) and radical adduct stabilization.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

An analysis of hydrated proton diffusion in ab initio molecular dynamics

A detailed understanding of the inherently multiscale proton transport process raises a number of scientifically challenging questions. For example, there remain many (partially addressed) questions on the molecular mechanism for long-range proton migration and the potential for the formation of long-lived traps giving rise to burst-and-rest proton dynamics. Using results from a sizeable collection of ab initio molecular dynamics (AIMD) simulations (totaling ∼2.7 ns) with various density functional approximations (Becke-Lee-Yang-Parr (BLYP), BLYP–D3, Hamprecht-Cohen-Tozer-Handy, B3LYP) and temperatures (300–330 K), equilibrium and dynamical properties of one excess proton and 128 water molecules are studied. Two features in particular (concerted hops and weak hydrogen-bond donors) are investigated to identify modes in the system that are strongly correlated with the onset of periods of burst-and-rest dynamics. The question of concerted hops seeks to identify those time scales over which long-range proton transport can be classified as a series of sequential water hopping events or as a near-simultaneous concerted process along compressed water wires. The coupling of the observed burst-and-rest dynamics with motions of a fourth neighboring water molecule (a weak hydrogen-bond donor) solvating the protonated water molecule is also investigated. The presence (absence) of hydrogen bonds involving this fourth water molecule before and after successful proton hopping events is found to be strongly correlated with periods of burst (rest) dynamics (and consistent with pre-solvation concepts). By analyzing several realizations of the AIMD trajectories on the 100-ps time scale, convergence of statistics can be assessed. For instance, it was observed that the probability for a fourth water molecule to approach the hydronium, if not already proximal at the beginning of the lifetime of the hydronium, is very low, indicative of the formation of stable void regions. Furthermore, the correlations of the neighboring water atoms are identified as the fourth water approaches the hydronium. Finally, the temperature effects on structural and dynamical properties are studied.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2020

Suppressing Cation Migration in Triple-Cation Lead Halide Perovskites

Ion migration represents an intrinsic instability of metal halide perovskite solar cells. In this work, we show that triple-cation FA x MA y Cs 1–x–y PbI 3 [FA + = (NH 2 ) 2 CH + , MA + = CH 3 NH 3 + ] active layers with mixed orthorhombic, post-perovskite (δ ortho -CsPbI 3 ), and cubic perovskite (α) phases (i.e., α/δ-phase FA x MA y Cs 1–x–y PbI 3 ) exhibit improved cation stability against applied bias relative to pure α-phase perovskites (i.e., FA 0.85 Cs 0.15 PbI 3 and FA 0.76 MA 0.15 Cs 0.09 PbI 3 ). Infrared photothermal heterodyne imaging and time-of-flight secondary ion mass spectrometry are used to visualize exclusive α-phase perovskite lateral device A + cation accumulation (depletion) at perovskite negative (positive) electrode interfaces. The resulting compositional heterogeneities lead to degradation. Operational stability testing of solar cells reveals similar degradation behavior; α/δ-phase FA x MA y Cs 1–x–y PbI 3 lateral devices/solar cells, by contrast, show improved stabilities. Enhanced α/δ-FA x MA y Cs 1–x–y PbI 3 stability is rationalized by δortho-phase inclusions, acting as barriers through which A + cations do not easily migrate. This study thus provides new insights into cation migration in FA x MAyCs 1–x–y PbI 3 perovskites and suggests a materials design strategy toward suppressing cation instabilities in hybrid perovskites.

14 SOLAR ENERGY↗
DOE OSTI2014

Thermal drawdown and late‐stage seismic‐slip fault reactivation in enhanced geothermal reservoirs

Abstract Late‐stage seismic slip in geothermal reservoirs has been shown as a potential mechanism for inducing seismic events of magnitudes to ~2.6 as late as two decades into production. We investigate the propagation of fluid pressures and thermal stresses in a prototypical geothermal reservoir containing a centrally located critically stressed fault from a doublet injector and withdrawal well to define the likelihood, timing, and magnitude of events triggered by both fluid pressures and thermal stresses. We define two bounding modes of fluid production from the reservoir. For injection at a given temperature, these bounding modes relate to either low‐ or high‐relative flow rates. At low relative dimensionless flow rates the pressure pulse travels slowly, the pressure‐driven changes in effective stress are muted, but thermal drawdown propagates through the reservoir as a distinct front. This results in the lowest likelihood of pressure‐triggered events but the largest likelihood of late‐stage thermally triggered events. Conversely, at high relative non‐dimensional flow rates the propagating pressure pulse is larger and migrates more quickly through the reservoir but the thermal drawdown is uniform across the reservoir and without the presence of a distinct thermal front, and less capable of triggering late‐stage seismicity. We evaluate the uniformity of thermal drawdown as a function of a dimensionless flow rate Q D that scales with fracture spacing s ( m ), injection rate q ( kg/s ), and the distance between the injector and the target point L ∗ ( Q D ∝ qs 2 / L ∗ ). This parameter enables the reservoir characteristics to be connected with the thermal drawdown response around the fault and from that the corresponding magnitude and timing of seismicity to be determined. These results illustrate that the dimensionless temperature gradient adjacent to the fault dT D / dx D is exclusively controlled by the factor Q D . More significantly, this temperature gradient correlates directly with both the likelihood and severity of triggered events, enabling the direct scaling of likely magnitudes and timing to be determined a priori and directly related to the characteristics of the reservoir. This dimensionless scaling facilitates design for an optimum Q D value to yield both significant heat recovery and longevity of geothermal reservoirs while minimizing associated induced seismicity.

Gan, Quan↗
DOE OSTI2022

Density functional theory study of formation and diffusion of hydrogen, deuterium, and tritium in Pd-V intermetallic compounds

Permeation of hydrogen isotopes in palladium/vanadium bimetallic membranes is known to deteriorate over time because of Pd-V interdiffusion. Additionally, intermetallic compounds may form in the interdiffusion region. Density functional theory is employed to study how Pd-V compounds may affect the permeation. Three compounds Pd 8 V, alpha-Pd 2 V, and PdV 4 are explored in this study. Formation and migration energies of hydrogen, deuterium, and tritium are calculated and subsequently compared to the data in pure Pd and V metals. The calculations show that both the formation and migration energies in the compounds are higher than in the pure metals. Thus, the permeation of these isotopes in the compounds is lower than in the pure metals. In addition, the least permeable compound is the one near the middle of the composition range, i.e. the alpha-Pd 2 V. The results provide atomistic insight for the permeation reduction in Pd/V membranes as interdiffusion progresses.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Non-equilibrium insertion of lithium ions into graphite

Graphite has been regarded as the most important anode material for currently used lithium-ion batteries due to its two-dimensional (2D) nature hosting ionic intercalations. However, the kinetic insertion of Li ions is still not well known microscopically. In this work, we investigate the real-time intercalation process of Li ions using in situ transmission electron microscopy. We observe the lithium insertion process at the atomic scale, in which the graphite layers undergo expansion, forming wrinkles and finally inhomogeneous cracks as the Li ions accumulate, different from the proposed models. Leveraging on theoretical simulations, Li-ion migration driven by an external electrical field is suggested to be induced into the irreversible wrinkled structures. This non-equilibrium behavior that occur in lithium-ion batteries can be more pronounced at a high charging rate, which will practically degrade the capacity of graphite. Furthermore, this work unveils the reaction scenario of the non-equilibrium Li-ion insertion, which benefits the understanding of the performance of graphite-based energy-storage devices.

25 ENERGY STORAGE↗