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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 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Collaborative Research: Tomographic imaging of laser-plasma structures

The interaction of intense short laser pulses with ionized gases, or plasmas, underlies many applications such as acceleration of elementary particles, production of energy by laser fusion, generation of x-ray and far-infrared “terahertz” pulses for medical and materials probing, remote sensing of explosives and pollutants, and generation of guide stars. Such laser-plasma interactions create tiny electron density structures (analogous to the wake behind a boat) inside the plasma in the shape of waves, bubbles and filaments that move at the speed of light, and evolve as they propagate. Prior to recent work by the PI of this proposal, detailed knowledge of such structures came exclusively from intensive computer simulations. Now “snapshots” of these elusive, light-velocity structures can be taken in the laboratory using dynamic variant of holography, the technique used to produce ID cards and DVDs, and dynamic variant of tomography, the technique used in medicine to image internal bodily organs. These fast visualization techniques are important for understanding, improving and scaling the above-mentioned applications of laser-plasma interactions. In this project, we accomplished three things: 1) We took holographic pictures of a laser-driven plasma-wave in the act of accelerating electrons to high energy, and used computer simulations to understand the pictures. 2) Using results from this experiment to optimize the performance of the accelerator, and the brightness of x-rays that it emits. These x-rays will be useful for medical and materials science applications. 3) We made technical improvements to the holographic technique that enables us to see finer details in the recorded pictures. Four refereed journal papers were published, and two students earned PhDs and moved on to scientific careers in US National Laboratories based on their work under this project.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

dV/dt - Accelerating the Rate of Progress towards Extreme Scale Collaborative Science

This report introduces publications that report the results of a project that aimed to design a computational framework that enables computational experimentation at scale while supporting the model of “submit locally, compute globally”. The project focuses on estimating application resource needs, finding the appropriate computing resources, acquiring those resources,deploying the applications and data on the resources, managing applications and resources during run.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Collaborative Project: Development of an Isotope-Enabled CESM for Testing Abrupt Climate Changes

One of the most important validations for a state-of-art Earth System Model (ESM) with respect to climate changes is the simulation of the climate evolution and abrupt climate change events in the Earth’s history of the last 21,000 years. However, one great challenge for model validation is that ESMs usually do not directly simulate geochemical variables that can be compared directly with past proxy records. In this proposal, we have met this challenge by developing the simulation capability of major isotopes in a state-of-art ESM, the Community Earth System Model (CESM), enabling us to make direct model-data comparison by comparing the model directly against proxy climate records. Our isotope-enabled ESM incorporates the capability of simulating key isotopes and geotracers, notably δ 18 O, δD, δ 14 C, and δ 13 C, Nd and Pa/Th. The isotope-enabled ESM have been used to perform some simulations for the last 21000 years. The direct comparison of these simulations with proxy records has shed light on the mechanisms of important climate change events.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Brazil-USA Collaborative Research: Modifications by Anthropogenic Pollution of the Natural Atmospheric Chemistry and Particle Microphysics of the Tropical Rain Forest During the GoAmazon Intensive Operating Periods (IOPs)

Manaus, a city of nearly two million people, represents an isolated urban area having a distinct urban pollution plume within the otherwise pristine Amazon Basin. The plume has high concentrations of oxides of nitrogen and sulfur, carbon monoxide, particle concentrations, and soot, among other pollutants. Critically, the distinct plume in the setting of the surrounding tropical rain forest serves as a natural laboratory to allow direct comparisons between periods of pollution influence to those of pristine conditions.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Collaborative Research: Centralized Activities in Support of the Radiative Forcing Model Intercomparison Project (Final Technical Report)

This final technical report summarizes the work accomplished by Atmospheric and Environmental Research in support of the Radiative Forcing Model Intercomparison Project, an international effort to assess sources of error and spread in the radiative forcing calculated by state-of-the-art climate models for historical and future climate studies. Our efforts on this project focused on the performing the line-by-line reference calculations for the gas forcing component of RFMIP. This included enhancing AER's line-by-line radiation model with the latest spectroscopic updates, completing the longwave and shortwave clear-sky high-resolution reference calculations using the line-by-line model, and an initial analysis of the reference calculations.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Collaborative Research: The Role of Grain Boundary Structure and Chemistry in Materials Failure

Throughout the one year duration of this award significant progress was made in understanding the effect of grain boundaries in polycrystalline materials. The starting point of this work is that each grain boundary can be characterized by an interface energy and respective interface parameter, which depend on the boundary chemical composition and structure. As this is a new point of view for treating grain boundaries, an interdisciplinary approach was followed to prove the existence of such interface terms. Throughout the project, hence, theory, experiments and simulations were used. Molecular dynamics and dislocation density-function dynamics were performed to understand dislocation-grain boundary interactions in pure Al crystalline materials, as potentials for Al are well established. The formation of dislocation pile-ups was observed and the strain profiles were in agreement with interfacial gradient plasticity, which is the theoretical framework that allows the introduction of mechanically induced interface energies. After verifying numerically the existence of mechanically induced interface energies, nanoindentation experiments were performed near grain boundaries of Fe-Si crystals that contained three grain boundaries. By indenting in close proximity to the boundary these experiments allowed for measuring the critical stress at which deformation was transmitted across the boundary to the adjacent grains, either through dislocation transmission or absorption and subsequent emission. This critical stress, also termed grain boundary yield stress, was in accordance with the value predicted by interfacial gradient plasticity, further verifying that mechanically induced interface energies can help define the material response. In the Fe-Si crystals the Si content was kept constant at 3wt%, but three specimen were considered each of which was characterized by a different misorientation at the grain boundary. By relating the experiments with the analytical gradient plasticity expressions it was possible to obtain first estimates for the interface parameter as ~200N/m. This value was not proportional to the misorientation angle, but depended also on the grain boundary plane. The continuation of this project is performing more detailed experiments on additional Fe-Si and Fe-C systems (both nanoindentation and in-situ transmission electron microscopy) to further understand the physical origin of such interface parameters. Furthermore, molecular dynamics nanoindentation simulations are also performed on similar systems to better understand the dislocation grain boundary interactions.

36 MATERIALS SCIENCE↗
DOE OSTI2016

OIE Collaborating Centre for Biorisk Management Strategic Plan.

Due to efforts by individual nations and the international community to monitor and control natural occurring outbreaks of animal and zoonotic diseases, any number and variety of select agents and especially dangerous pathogens can be found at diagnostic laboratories around the world. Diagnostic testing is a crucial aspect of disease surveillance, but the organized collection and testing of diagnostic samples from the animal and human population at laboratories has created a repository of disease agents and toxins that could cause serious harm if released or acquired by nefarious means. The delicate balance between public health disease surveillance and the management of biorisks at facilities utilized in surveillance is a necessary goal of veterinary public health.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Final Technical Report for Collaborative Research: Developing and Implementing Ocean-Atmosphere Reanalyses for Climate Applications (OARCA)

As an important step toward a coupled data assimilation system for generating reanalysis fields needed to assess climate model projections, the Ocean Atmosphere Coupled Reanalysis for Climate Applications (OARCA) project assesses and improves the longest reanalyses currently available of the atmosphere and ocean: the 20th Century Reanalysis Project (20CR) and the Simple Ocean Data Assimilation with sparse observational input (SODAsi) system, respectively. In this project, we make off-line but coordinated improvements in the 20CR and SODAsi datasets, with improvements in one feeding into improvements of the other through an iterative generation of new versions. These datasets now span from the 19th to 21st centuries. We then study the extreme weather and variability from days to decades of the resulting datasets. A total of 24 publications have been produced in this project.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Nek5000 Simulations on Turbulent Coolant Flow in a Fuel Assembly Experiment - AREVA/ANL collaboration for advancing CFD tools

The NEAMS program aims to develop an integrated multi physics simulation capability “pellet to plant” for the design and analysis of future generations of nuclear power plants. In particular, the Reactor Product Line code suite’s multi resolution hierarchy is being designed to ultimately span the full range of length and time scales present in relevant reactor design and safety analyses, as well as scale from desktop to petaflop computing platforms.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2018

Collaborative study on "Earthquake Ground Motion Simulation Using Rupture Dynamics"

California (LLNL) and Disaster Prevention Research Institute, Kyoto University, Japan (DPRI) on rupture dynamics for crustal earthquakes, we carried out analyses of effects of several dynamic rupture parameters, such as stress drop, slip weakening distance and stress excess on fault rupture slip, slip velocity, and rupture velocity. In addition, we examined potential relationships between the assumed initial stress conditions, including asperities location, and rupture initiation and the final slip and slip velocity obtained from the spontaneous rupture modeling.

58 GEOSCIENCES↗
DOE OSTI2015

Open Collaboration and Research Capabilities on the LVOC/CREATE/High Performance Computing Innovation Center

While Lawrence Livermore National Laboratory (LLNL) and Sandia National Laboratories (SNL) have remained committed to their core nuclear weapons (NW) mission, the world has changed greatly since the opening of these national labs in the mid-20th century. During this era, U.S. universities were ranked as the top science centers in the world in essentially all fields, and the national laboratories were able to recruit the top graduates - who were predominantly U.S. citizens - from the nation's best academic institutions.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Collaborative Project: Contributions of organic compounds to the growth of freshly nucleated atmospheric nanoparticles. Final Report

New-particle formation (NPF) is a significant source of aerosol particles into the atmosphere. However, these particles are initially too small to have climatic importance and must grow, primarily through net uptake of low-volatility species and more volatile gases that react in particles to form stable compounds, from diameters of ~1 nm to 30–100 nm in order to potentially impact climate. At the present time there are uncertainties in the physical and chemical processes associated with the growth of these freshly formed particles that lead to uncertainties in model predictions of aerosol-climate interactions. In this project, we used a combination of field, laboratory, and modelling studies to understand the processes leading to nanoparticle growth and evaluated and improved growth in global aerosol models. During this period this research team has either participated in, or analyzed observations from, four DOE-funded campaigns: the 2013 New Particle Formation Study (NPFS) at the ARM Southern Great Plains (SGP) site; the 2013 Biogenic Aerosols – Effects on Clouds and Climate campaign (BAECC) in Hyytiala, Finland; Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) in central Amazonia, Brazil; and, most recently, the 2016 Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems (HI-SCALE) campaign at the SGP site. In addition, the research team explored nanoparticle growth mechanisms in laboratory experiments at the National Center for Atmospheric Research, University of California, Irvine, and the CLOUD chamber in Geneva, Switzerland. Modeling efforts resulted in a process-level model that incorporated both salt formation and the uptake of low-volatility organic compounds, which was able to connect measurements of gas and nanoparticle phase compounds observed during NPFS. In total, the results of this work have been described in 32 peer-reviewed publications and 34 invited or conference presentations.

58 GEOSCIENCES↗
DOE OSTI2018

Final Report: Collaborative Project: Contributions of organic compounds to the growth of freshly nucleated atmospheric nanoparticles

New-particle formation (NPF) is a significant source of aerosol particles into the atmosphere. However, these particles are initially too small to have climatic importance and must grow, primarily through net uptake of low-volatility species and more volatile gases that react in particles to form stable compounds, from diameters of ~1 nm to 30–100 nm in order to potentially impact climate. At the present time there are uncertainties in the physical and chemical processes associated with the growth of these freshly formed particles that lead to uncertainties in model predictions of aerosol-climate interactions. In this project, we used a combination of field, laboratory, and modelling studies to understand the processes leading to nanoparticle growth and evaluated and improved growth in global aerosol models. During this period this research team has either participated in, or analyzed observations from, four DOE-funded campaigns: the 2013 New Particle Formation Study (NPFS) at the ARM Southern Great Plains (SGP) site; the 2013 Biogenic Aerosols – Effects on Clouds and Climate campaign (BAECC) in Hyytiala, Finland; Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) in central Amazonia, Brazil; and, most recently, the 2016 Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems (HI-SCALE) campaign at the SGP site. In addition, the research team explored nanoparticle growth mechanisms in laboratory experiments at the National Center for Atmospheric Research, University of California, Irvine, and the CLOUD chamber in Geneva, Switzerland. Modeling efforts resulted in a process-level model that incorporated both salt formation and the uptake of low-volatility organic compounds, which was able to connect measurements of gas and nanoparticle phase compounds observed during NPFS. In total, the results of this work have been described in 32 peer-reviewed publications and 34 invited or conference presentations.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

STP/TAMU/INL Collaboration Update: LWRS Risk-Informed Safety Margin Characterization (RISMC) Lead

Present a preliminary RISMC model, including plant model interfaces for Best Estimate Plus Uncertainty Loss-Of-Coolant Accident analysis using riskinformed analysis tools. Analysis results for a coupled core design, fuel/clad and systems analysis framework (LOTUS) will be presented for existing baseline codes (RELAP5-3D, FRAPCON) to Large Break Loss-Of-Coolant Accident scenarios

22 GENERAL STUDIES OF NUCLEAR REACTORS↗