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  1. Energy Impact of Radiative Cooling Paints in Warehouses Under Various United States Climates

    Barber, Emily ; Kishore, Ravi Anant ; Bianchi, Marcus V. A. ; ... - Journal of Engineering for Sustainable Buildings and Cities
    Although radiative cooling research is widely found in the literature, no comprehensive study has yet been conducted on the impact of novel radiant cooling (>0.91 reflectance) on the energy efficiency of warehouses. Here, in this work, we develop three building models based on a Department of Energy prototype warehouse model using trnsys, representing a typical warehouse with a black roof, a typical warehouse with a white roof, and a warehouse with novel radiative cooling (RC) paint on its roof. These models are run for 15 different cities, each representative of a different ASHRAE climate zone, to better understand the impactmore » of RC in many different climates. It was found that an RC-coated roof in a warehouse could reduce the building's annual heating, ventilation, and air conditioning (HVAC) loads by up to 14.11 kWh/m2 of the roof area compared to a black roof, resulting in a maximum reduction in energy costs of 0.55 $$\$$$$/m2 or $$\$$$$2646/year for a large 4835 m2 warehouse. Similarly, replacing the typical white roof coating with an RC coating could reduce the warehouse's energy consumption by up to 8.17 kWh/ m2 of roof area, thus reducing energy costs by as much as 0.29 $$\$$$$/m2 or $$\$$$$1386/year for a 4835 m2 warehouse. In addition, applying RC paint to an unconditioned warehouse could reduce the building's ASHRAE Standard 55 indoor temperature exceedance by up to 1330 h/year compared to a black roof and up to 532 h/year compared to a white roof.« less

  2. Grain boundary metastability controls irradiation resistance in nanocrystalline metals

    El-Atwani, Osman ; Barnett, Annie K. ; Martínez, Enrique ; ... - Materials & Design
    Grain boundaries (GBs) in polycrystalline materials are powerful sinks for irradiation defects. While standard theories assume that a GB’s efficiency as a sink is defined solely by its character before irradiation, recent evidence conclusively shows that the irradiation sink efficiency is a highly dynamic property controlled by the intrinsic metastability of GBs under far-from-equilibrium irradiation conditions. In this paper, we reveal that the denuded (i.e., defect-free) zone, typically the signature of a strong sink, can collapse as irradiation damage accumulates. We propose a radiation damage evolution model that captures this behavior based on the emergence of a series of irradiationmore » defect-enabled metastable GB microstate changes that dynamically alter the ability of the GB to absorb further damage. We show that these microstate changes control further defect absorption and give rise to the formation of a defect network that manifests itself as a net Nye-tensor signal detectable via lattice curvature experiments.« less

  3. Using Radioactive Material to Evaluate Decontamination of Contaminated Electronics

    Heiden, Zachariah M. ; Hines, C. Corey ; Kazi, Zakir H. ; ... - Journal of Radioanalytical and Nuclear Chemistry
    Electronic materials are used everywhere and can get easily contaminated by their use in the field/laboratory. With electronic devices getting smaller and smaller, electronic devices become harder to clean when they become contaminated. The goal of this project was to use radioactive material to track the effectiveness of a cleaning procedure for contaminated electronics using an of-the-shelf cleaning gel. Radioactive potassium bromide (KBr) was used as a model contaminant in four contamination scenarios to gauge the effectiveness of a cleaning gel in the decontamination of contaminated raspberry pi’s. The investigated decontamination technique was found to be 75 - 97 %more » effective in removing the loose and adhered contamination from the tested electronic devices. 95% of the contaminated electronic devices retained their functionality post-decontamination.« less

  4. A kinetic line-driven radiation operator and its application to Gyrokinetics

    Roeltgen, Jonathan ; Juno, James ; Kotschenreuther, Mike ; ... - Nuclear Fusion
    A velocity dependent, kinetic model for line radiation is developed for continuum kinetic codes. It has been implemented in the full-f gyrokinetic code Gkeyll. The total radiation for a charge state is modeled as an advection in velocity space with a form of $$\nabla_v \cdot(v\nu(v)f(v))$$, guaranteeing particle conservation. The velocity dependence (in the form of an effective frequency $$\nu(v)$$) is found through fitting the energy loss of the operator, i.e. the second velocity moment, to the radiation data in the OpenADAS database. Therefore, each individual transition does not need to be evaluated every time step, significantly reducing the computational costmore » of including line radiation in a kinetic model. The dependence on velocity instead of the usual, temperature, allows the radiation to be computed from non-Maxwellian electron distribution functions: We benchmark the model against a collisional radiative model using isotropic non-Maxwellian distribution functions. A velocity dependent model of radiation can more accurately describe the radiation in the more kinetic regimes expected in reactor-scale devices. The velocity dependence qualitatively captures the quantum mechanical need for a minimum velocity before any radiation occurs.« less

  5. Long-Range Transport of Biomass Burning Aerosols from Southern Africa: A Case Study Using Layered Atlantic Smoke Interactions with Clouds Observations

    Ajoku, Osinachi F. ; Wilkins, Joseph L. ; Abdulahi, Mumin - Atmosphere
    A case study of an incoming biomass burning aerosol plume at Ascension Island is analyzed for the peak of the 2017 fire season using satellites, reanalysis and in situ observations. Measurements from the Atmospheric Radiation Measurement Mobile Facility 1 reveal an abrupt change from relatively clean conditions (~70 parts per billion by volume of carbon monoxide) to a more polluted state (~150 parts per billion by volume of carbon monoxide). Corresponding changes in aerosol size reveal a broadening of size distributions toward larger optical diameters, consistent with the arrival of aged aerosols. Within a 24 h period, black carbon fractionmore » increases ~500% from ~300 ng me to ~1500 ng m3, while light absorption coefficients increase ~300%. Long-range transport of these aerosols is primarily confined between 2 and 5 km above sea level along the northwesterly trade winds. Our results show that the primary driver of increases in aerosol loading over Ascension Island is an intensification of the St. Helena high-pressure system (anticyclone) that leads to a weakening of trade winds and increases westward transport on its northern flank. A better understanding of the complex interactions between air quality, meteorology and long-range aerosol transport is important for future modeling studies focused on aerosol–cloud–radiation interactions over the open ocean and reducing its associated uncertainties.« less

  6. The Efficiency of Water Vapor on Top‐of‐Atmosphere Radiation

    Feng, Jing ; Paynter, David ; Feldl, Nicole ; ... - Geophysical Research Letters
    Earth's climate sensitivity is greatly affected by the compensation between temperature feedback and water vapor (WV) feedback. Using abrupt 4xCO2 experiments, we show that the global-mean WV feedback is nearly a linear function of the temperature feedback, the slope of which is explained by the longwave radiative efficiency of WV (ϵ). Although ϵ remains constant across models in the global mean, it exhibits substantial spatial variations and is particularly weak in Antarctica, where near-surface inversions decouple the surface from the free troposphere. We introduce a surface–free troposphere temperature difference (SFTD) metric, showing that positive SFTD (e.g., high lifting condensation level)more » amplifies ϵ, while negative SFTD (e.g., strong surface inversion) suppresses it. These findings provide a clear explanation of how local climate conditions modulate the radiative compensation between temperature and WV feedbacks.« less

  7. Special Issue: National Laboratories’ Safety Successes, Challenges, Research, and Approaches

    MacKenzie, Cheryl - Journal of Chemical Health and Safety
    In today’s world, volatility, uncertainty, complexity, and ambiguity─collectively referred to as VUCA─is demonstrably greater than before. VUCA is a concept first documented in U.S. Army War College records in the late 1980s to describe challenging and rapidly changing environments. In the VUCA world in which we work, we aim to leverage our colleagues’ knowledge as we push the envelope further. And we must do it now. I urge you to explore these invited articles, as well as those in the larger ACS Chemical Health & Safety collection, and continue innovating.

  8. The Two Arctic Wintertime Boundary Layer States: Disentangling the Role of Cloud and Wind Regimes in Reanalysis and Observations During MOSAiC

    Dahlke, Sandro ; Rinke, Annette ; Shupe, Matthew D. ; ... - Atmospheric Science Letters
    The wintertime central Arctic atmosphere comprises a radiatively clear and a radiatively opaque state, which are linked to synoptic forcing and mixed-phase clouds. Weather and climate models often lack process representations surrounding these states, but prior work mostly treated the problem as an aggregate of synoptic conditions, resulting in partially overlapping biases. Here, we disaggregate the Arctic states and confront ERA5 reanalysis with observations from the MOSAiC campaign over the central Arctic sea ice during winter 2019/2020. Low-level winds and liquid water path (LWP) are combined to derive different synoptic classes. Results show that the clear state is primarily formedmore » by weak/moderate winds and the absence of liquid-bearing clouds, while strong winds and enhanced LWP primarily form the radiatively opaque state. ERA5 struggles to reproduce these basic statistics, shows too weak sensitivity of thermal radiation to synoptic forcing, and overestimates thermal radiation for similar LWP amounts. The latter is caused by a warm bias, which has a pronounced inversion structure and is largest in clear and calm conditions. Under strong synoptic forcing, the warm bias is constant with height and discrepancies in mixed-phase cloud altitude appear. Separating synoptic conditions is regarded as useful for process-oriented evaluation of the Arctic troposphere in models.« less

  9. Role of E × B Drift in Divertor Detachment Control via Boron Powder Injection on EAST

    Peng, Lei ; Sun, Zhen ; Sun, Jizhong ; ... - Journal of Fusion Energy (Online)
    Here, the effects of B powder injection on plasma detachment about EAST discharge were studied by using SOLPS-ITER code package with the effects of E × B drifts considered. The simulation results show that plasma detachment occurs at the inner target in favourable toroidal magnetic field (Bt) direction at a relatively low B powder flow rate, one order of magnitude lower than that at the outer target. In a similar scenario with unfavourable Bt, it is found that the detachment thresholds of B flow rate for both the inner and outer targets are close and of the same order asmore » that for the outer target with favourable Bt. In favourable Bt direction at B powder flow rate of 1.2 × 1021 atoms/s, a localized, broadened high-density region is formed near the inner target benefitted by the injection location and the E × B drift, and a radiation-intensified zone, mostly contributed by B1+ and B2+, occurs there. The E × B drift facilitates plasma detachment at the inner target and simultaneously amplifies the in–out divertor asymmetry. In addition, the simulation results with three different injection locations show that the injection from outer strike point leads to the lowest Zeff inside the separatrix and has an intermediate flow rate for detachment at the outer target, comparing with the X-point and upstream locations.« less

  10. A 291-day Evaluation of the Performance of a Consumer-grade Temporal Radon Detector

    Evans, Carly E. ; Kearfott, Kimberlee J. - Health Physics (Online)
    Affordable, accurate, and robust temporal measurement devices are desirable for screening and assessment of radon levels in private homes and workplaces. This research expands upon prior research, using the RadonFTlab RadonEye device through a comparison of multiple samples of this instrument with a laboratory-grade instrument, the Saphymo AlphaGUARD, over a more extensive period than reported previously. Data were collected over 291 d in a poorly ventilated basement space in an occupied building. Environmental conditions varied naturally, changing both the radon source term and radon entry into the space approximating typically deployed conditions. The R-squared linear regression correlation coefficient and relativemore » sensitivities of each RadonEye with the AlphaGUARD were computed. Altogether temporal and diurnal variations were also studied. The sensitivities of all RadonEyes and the AlphaGUARD agreed to within 22% throughout the entire deployment period.« less
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