Federal - Executive Branch
News releases, reports, statements and associated documents from the U.S. Executive Branch, covering all aspects of the Obama administration including cabinet departments, federal agencies, regulatory and independent agencies.
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Earth System Model Aerosol-Cloud Diagnostics (ESMAC Diags) package, Version 2: Assessing aerosols, clouds and aerosol-cloud interactions via field campaign and long-term observations
WASHINGTON, Nov. 16 (TNSres) -- The U.S. Department of Energy's Pacific Northwest National Laboratory issued the following abstract of a journal article:
Evaluating Earth System Models (ESMs) with observations reveals shortcomings in these models and provides directions for future model improvements. However, most well-established diagnostics packages focus on large-scale features and climatology, while a comprehensive evaluation of aerosols, clouds, and aerosol-cloud interactions is needed to increase the confidence of process representations in the models. We developed an ESM aerosol-cloud diagnostics
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WASHINGTON, Nov. 16 (TNSres) -- The U.S. Department of Energy's Pacific Northwest National Laboratory issued the following abstract of a journal article:
Evaluating Earth System Models (ESMs) with observations reveals shortcomings in these models and provides directions for future model improvements. However, most well-established diagnostics packages focus on large-scale features and climatology, while a comprehensive evaluation of aerosols, clouds, and aerosol-cloud interactions is needed to increase the confidence of process representations in the models. We developed an ESM aerosol-cloud diagnosticspackage (ESMAC Diags) to facilitate routine evaluation of aerosols, clouds and aerosol-cloud interactions simulated by the Department of Energy's (DOE) Energy Exascale Earth System Model (E3SM), and this paper documents its version 2 functionality, which has substantial differences from ESMAC Diags version 1 (Tang et al., 2022a). ESMAC Diags v2 produces comparisons of simulated aerosol and cloud properties with in-situ and remote-sensing measurements from aircraft, ship, surface and satellite platforms. It currently includes six field campaigns and two permanent sites covering four geographical regions: Eastern North Atlantic, Central U.S., Northeastern Pacific and Southern Ocean, where frequent liquid or mixed-phase clouds are present and extensive measurements are available from the DOE Atmospheric Radiation Measurement (ARM) user facility and other agencies. ESMAC Diags v2 includes various types of single-variable and multi-variable diagnostics, such as percentiles, histograms, joint histograms and heatmaps, to assess aerosols, clouds, and aerosol-cloud interactions. A few examples are shown when evaluating E3SM version 2 (E3SMv2) using ESMAC Diags. Overall E3SMv2 qualitatively reproduces the observed aerosol and cloud properties, with quantitative biases in some variables such as aerosol particle and cloud droplet numbers and sizes. The coupling of aerosol and cloud number concentrations may be too strong in E3SMv2, possibly indicating a bias in processes that control aerosol activation. In addition, the liquid water path adjustment to perturbed cloud droplet number concentration behaves differently in E3SMv2 and observations, indicating a need for further improvements to cloud microphysics parameterization in E3SMv2.
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Original text here: https://www.pnnl.gov/publications/earth-system-model-aerosol-cloud-diagnostics-esmac-diags-package-version-2-assessing
Advancing Radioactive Material Research Method: the Development of a Novel in situ Particle-attached Microfluidic Electrochemical Cell
WASHINGTON, Nov. 15 (TNSres) -- The U.S. Department of Energy's Pacific Northwest National Laboratory issued the following abstract of a journal article:
This work describes the development of a vacuum compatible microfluidic electrochemical cell (E-cell) for investigating the redox of uranium oxide (UO2). Conducting experiments on bulk amounts of radioactive material is costly and requires shielded hot cell facilities. By using microfluidic techniques, the amount of radioactive materials used in a single test can be significantly reduced, allowing for electrochemical experiments outside of a
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WASHINGTON, Nov. 15 (TNSres) -- The U.S. Department of Energy's Pacific Northwest National Laboratory issued the following abstract of a journal article:
This work describes the development of a vacuum compatible microfluidic electrochemical cell (E-cell) for investigating the redox of uranium oxide (UO2). Conducting experiments on bulk amounts of radioactive material is costly and requires shielded hot cell facilities. By using microfluidic techniques, the amount of radioactive materials used in a single test can be significantly reduced, allowing for electrochemical experiments outside of ashielded facility. The paper details several attempts to develop a microfluidic E-cell that uses UO2 as the working electrode and can be used for in situ chemical imaging analysis. The authors discuss the advantages of microfluidic E-cells over traditional electrochemical cells and the challenges of designing a microfluidic E-cell that uses solid material as a working electrode and is compatible with vacuum-based analytical instruments. The paper outlines the different methods proposed for attaching the UO2 electrode under a thin detection window of the E-cell, including Focused Ion Beam Scanning Electron Microscopy lift-out method, Au-coating attachment, and polyvinylidene fluoride (PVDF) binder method. The authors conclude that using PVDF binder method is the most effective approach and demonstrates that particle-based electrodes can provide an effective and low-cost solution for microfluidic electrochemical applications. The in situ microfluidic E-cell design with the integration of a radioactive material working electrode provides a promising and cost-effective approach for investigating spent nuclear fuel via reducing the amount of materials needed for analysis.
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Original text here: https://www.pnnl.gov/publications/advancing-radioactive-material-research-method-development-novel-situ-particle
Determining the bubble nucleation efficiency of low-energy nuclear recoils in superheated C3F8 dark matter detectors
WASHINGTON, Nov. 10 (TNSres) -- The U.S. Department of Energy's Pacific Northwest National Laboratory issued the following abstract of a journal article:
The bubble nucleation efficiency of low-energy nuclear recoils in superheated liquids plays a crucial role in interpreting results from direct searches for weakly interacting massive particle (WIMP) dark matter. The PICO collaboration presents the results of the efficiencies for bubble nucleation from carbon and fluorine recoils in superheated C3F8 from calibration data taken with five distinct neutron spectra at various thermodynamic thresholds
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WASHINGTON, Nov. 10 (TNSres) -- The U.S. Department of Energy's Pacific Northwest National Laboratory issued the following abstract of a journal article:
The bubble nucleation efficiency of low-energy nuclear recoils in superheated liquids plays a crucial role in interpreting results from direct searches for weakly interacting massive particle (WIMP) dark matter. The PICO collaboration presents the results of the efficiencies for bubble nucleation from carbon and fluorine recoils in superheated C3F8 from calibration data taken with five distinct neutron spectra at various thermodynamic thresholdsranging from 2.1 to 3.9 keV.
Instead of assuming any particular functional forms for the nuclear recoil efficiency, a generalized piecewise linear model is proposed with systematic errors included as nuisance parameters to minimize model-introduced uncertainties. A Markov chain Monte Carlo routine is applied to sample the nuclear recoil efficiency for fluorine and carbon at 2.45 and 3.29 keV thermodynamic thresholds simultaneously.
The nucleation efficiency for fluorine was found to be =50% for nuclear recoils of 3.3 keV (3.7 keV) at a thermodynamic Seitz threshold of 2.45 keV (3.29 keV), and for carbon the efficiency was found to be =50% for recoils of 10.6 keV (11.1 keV) at a threshold of 2.45 keV (3.29 keV). Simulated datasets are used to calculate a p value for the fit, confirming that the model used is compatible with the data. The fit paradigm is also assessed for potential systematic biases, which although small, are corrected for. Additional steps are performed to calculate the expected interaction rates of WIMPs in the PICO-60 detector, a requirement for calculating WIMP exclusion limits.
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Original text here: https://www.pnnl.gov/publications/determining-bubble-nucleation-efficiency-low-energy-nuclear-recoils-superheated-c3f8
The Directional Unit Hydrograph Method: Connecting Streamflow Response to Storm Dynamics
WASHINGTON, Nov. 9 (TNSres) -- The U.S. Department of Energy's Pacific Northwest National Laboratory issued the following abstract of a journal article:
Storm direction and storm velocity play a critical role in streamflow response; and despite evidence of ongoing changes in storm tracks around the world, there is no practical approach to efficiently assess and quantify the role of these storm properties in streamflow magnitude. We address this technical gap by introducing the Directional Unit Hydrograph (Directional-UH) model to systematically evaluate the storm hydrograph as a function of storm
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WASHINGTON, Nov. 9 (TNSres) -- The U.S. Department of Energy's Pacific Northwest National Laboratory issued the following abstract of a journal article:
Storm direction and storm velocity play a critical role in streamflow response; and despite evidence of ongoing changes in storm tracks around the world, there is no practical approach to efficiently assess and quantify the role of these storm properties in streamflow magnitude. We address this technical gap by introducing the Directional Unit Hydrograph (Directional-UH) model to systematically evaluate the storm hydrograph as a function of stormdirection and storm velocity. The Directional-UH is based on the well-known theory of the unit hydrograph, which has served as a foundational block of multiple rainfall-runoff models for streamflow prediction.
The Directional-UH relaxes the assumption of spatial uniform rainfall prescribed in the original concept of the unit hydrograph, by incorporating storm direction and storm velocity into the unit hydrograph function. The storm structure within the Directional-UH is represented by rectangular storms moving with constant velocity over a linear trajectory. We demonstrated, based on observations of extreme rainfall events, that rectangular storm representations can reproduce streamflow responses similar to those expected from actual radar rainfall observations. The Turkey River basin located in Iowa, USA, is used as a testbed to illustrate three practical applications of the Directional-UH model. First, the storm trajectory that produces the highest peak flow response is identified. Second, the conditions that lead to the rainfall-runoff resonance are determined, which occurs when the storm motion and the flood wave are in sync to maximize the peak flow response.
Third, streamflow responses from consecutive storm events are quantified, allowing exploration and identification of critical combinations of storm events that exacerbate the magnitude of flood events. Overall, the simple hydrological inference offered by the Directional-UH makes this model a unique and essential hydrological tool that provides new perspectives to expand our understanding of rainfall-runoff dynamics through the lenses of storm direction and storm velocity.
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Original text here: https://www.pnnl.gov/publications/directional-unit-hydrograph-method-connecting-streamflow-response-storm-dynamics
Coating Developments Towards Enabling Aluminum as a Bipolar Plate Material for PEM Fuel Cells
WASHINGTON, Nov. 8 (TNSres) -- The U.S. Department of Energy's Pacific Northwest National Laboratory issued the following abstract of a journal article:
Bipolar plates represent a significant portion of the cost and weight of a proton exchange membrane (PEM) fuel cell stack. As a result, there has been significant interest in using low weight and cost materials, such as aluminum as a material for bipolar plates. Aluminum is advantageous and has properties that can potentially allow it to attain technical targets required for bipolar plates such as high electrical conductivity, low contact resistance,
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WASHINGTON, Nov. 8 (TNSres) -- The U.S. Department of Energy's Pacific Northwest National Laboratory issued the following abstract of a journal article:
Bipolar plates represent a significant portion of the cost and weight of a proton exchange membrane (PEM) fuel cell stack. As a result, there has been significant interest in using low weight and cost materials, such as aluminum as a material for bipolar plates. Aluminum is advantageous and has properties that can potentially allow it to attain technical targets required for bipolar plates such as high electrical conductivity, low contact resistance,good formability, and flexural strength.
However, aluminum performs poorly in the corrosive environment within the fuel cell stack, prohibiting it from being used as bipolar plate material by itself. To overcome the corrosion performance issue, there have been efforts towards developing coating processes to enable aluminum to attain corrosion targets. In previous efforts to develop a coating process for aluminum, only melt-based coating processes have been investigated which shows a common issue of the existence of pores that eventually allow corrosive media to contact the aluminum. In an effort to develop a means to allow aluminum as a viable bipolar plate material, an alternative approach using a solid phase process (diffusion bonding) for bonding a thin layer titanium foil to aluminum was investigated in this study. Diffusion bonding of titanium to aluminum has the potential to overcome the shortcomings of other attempts to coat aluminum for the PEM fuel cell bipolar plates.
The microstructure, corrosion performance, mechanical properties and electrical resistance were investigated. The effect of addition of highly conductive gold particles after diffusion bonding, on contact resistance and corrosion behavior, was also studied and compared with diffusion bonded Ti to Al. The results indicate that diffusion bonded Ti to Al provides a viable alternative material combination for bipolar plate that avoids the micro pores and crevasses that are associated with fusion (melt) based coating processes.
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Original text here: https://www.pnnl.gov/publications/coating-developments-towards-enabling-aluminum-bipolar-plate-material-pem-fuel-cells
Availability of State-Level Climate Change Projection Resources for use in Site-Level Risk Assessment
WASHINGTON, Nov. 8 (TNSres) -- The U.S. Department of Energy's Pacific Northwest National Laboratory issued the following abstract of a journal article:
In recent years, incorporating climate change considerations has become an important focus of organizations' resilience planning and risk assessment efforts, including United States federal agencies. This has led to an increasing demand for higher resolution and higher quality climate projection information that is easy to understand for non-expert users.
In particular, there is a demand for information about how climate change may affect high-impact,
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WASHINGTON, Nov. 8 (TNSres) -- The U.S. Department of Energy's Pacific Northwest National Laboratory issued the following abstract of a journal article:
In recent years, incorporating climate change considerations has become an important focus of organizations' resilience planning and risk assessment efforts, including United States federal agencies. This has led to an increasing demand for higher resolution and higher quality climate projection information that is easy to understand for non-expert users.
In particular, there is a demand for information about how climate change may affect high-impact,low-frequency hazards that are central to risk assessments focused on infrastructure. While national-level resources like the National Climate Assessment provide information on climate impacts for different sectors and regions in the United States, more location-specific information is often required for site-level resilience planning.
Here, we review the availability of state-level climate change resources in the United States that can inform site-level resilience planning. We discuss the types of resources available for different states, including some examples of regional and national resources that provide higher-resolution information for multiple states. Finally, we identify key policy and stakeholder drivers influencing the development of state-level climate resources.
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Original text here: https://www.pnnl.gov/publications/availability-state-level-climate-change-projection-resources-use-site-level-risk
Assessing Multi-Dimensional Impacts of Achieving Sustainability Goals by Projecting the Sustainable Agriculture Matrix into the Future
WASHINGTON, Nov. 8 (TNSres) -- The U.S. Department of Energy's Pacific Northwest National Laboratory issued the following abstract of a journal article:
The concept of sustainability inherently spans multiple spatial scales, sectors, variables, and time horizons. This study links a recently developed method of assessing present-day agricultural sustainability across environmental, economic, and social dimensions with a process-based integrated assessment model, in order to allow forward-looking analysis of sustainability by region and scenario.
The Sustainable Agriculture Matrix (SAM) estimates
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WASHINGTON, Nov. 8 (TNSres) -- The U.S. Department of Energy's Pacific Northwest National Laboratory issued the following abstract of a journal article:
The concept of sustainability inherently spans multiple spatial scales, sectors, variables, and time horizons. This study links a recently developed method of assessing present-day agricultural sustainability across environmental, economic, and social dimensions with a process-based integrated assessment model, in order to allow forward-looking analysis of sustainability by region and scenario.
The Sustainable Agriculture Matrix (SAM) estimatespresent-day agricultural sustainability at the national level using 18 indicator variables, of which this study estimates nine to the year 2100, using an enhanced version of the Global Change Analysis Model (GCAM). Scenarios include a reference scenario, and scenarios that apply the following measures, both individually and in combination, that are thought to improve sustainability: yield intensification, transition towards more plant-based ("flexitarian") diets, and economy-wide greenhouse gas emissions mitigation. The scenarios illustrate considerable complexity and tradeoffs inherent to efforts to improve agricultural sustainability in all regions globally. For example, yield intensification typically increases nitrogen pollution, flexitarian diets often reduce agricultural labor productivity, and greenhouse gas mitigation efforts may either increase deforestation or crowd out crop and livestock production due to consequent bioenergy demands.
However, there is considerable inter-regional heterogeneity in the responses, and the importance of such secondary responses also differs by region. The analysis and post-processing methods developed in this study allow quantification and visualization of the absolute and relative magnitude of the tradeoffs between agricultural sustainability indicator variables across regions, time periods, and scenarios.
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Original text here: https://www.pnnl.gov/publications/assessing-multi-dimensional-impacts-achieving-sustainability-goals-projecting
