Anthropogenic nitrogen inputs cause major negative environmental impacts, including emissions of the important greenhouse gas N
O. Despite their importance, shifts in terrestrial N loss pathways ...driven by global change are highly uncertain. Here we present a coupled soil-atmosphere isotope model (IsoTONE) to quantify terrestrial N losses and N
O emission factors from 1850-2020. We find that N inputs from atmospheric deposition caused 51% of anthropogenic N
O emissions from soils in 2020. The mean effective global emission factor for N
O was 4.3 ± 0.3% in 2020 (weighted by N inputs), much higher than the surface area-weighted mean (1.1 ± 0.1%). Climate change and spatial redistribution of fertilisation N inputs have driven an increase in global emission factor over the past century, which accounts for 18% of the anthropogenic soil flux in 2020. Predicted increases in fertilisation in emerging economies will accelerate N
O-driven climate warming in coming decades, unless targeted mitigation measures are introduced.
A likely important feature of the poorly understood aerosol‐cloud interactions over the Southern Ocean (SO) is the dominant role of sea spray aerosol, versus terrestrial aerosol. Ice nucleating ...particles (INPs), or particles required for heterogeneous ice nucleation, present over the SO have not been studied in several decades. In this study, boundary layer aerosol properties and immersion freezing INP number concentrations (nINPs) were measured during a ship campaign that occurred south of Australia (down to 53°S) in March–April 2016. Ocean surface chlorophyll a concentrations ranged from 0.11 to 1.77 mg/m3, and nINPs were a factor of 100 lower than historical surveys, ranging from 0.38 to 4.6 m−3 at −20 °C. The INP population included organic heat‐stable material, with contributions from heat‐labile material. Lower INP source potentials of SO seawater samples compared to Arctic seawater were consistent with lower ice nucleating site densities in this study compared to north Atlantic air masses.
Plain Language Summary
The Southern Ocean is known for a prevalence of clouds that contain both liquid and ice, which are one of the most poorly understood cloud regimes in the climate system. A large gap in understanding important processes in these clouds is a lack of knowledge regarding particles (e.g., sea spray) required for forming ice crystals, termed ice nucleating particles. In a ship‐based monthlong field study, several instruments were deployed in efforts to characterize the ice nucleating particles present over the Southern Ocean for the first time in over four decades. Abundances of ice nucleating particles throughout the voyage were extremely low compared to other ocean regions, and concentrations were 2 orders of magnitude lower than the most recent survey conducted in the 1970s. We report that the ocean‐derived ice nucleating particles observed in this study were organic in nature, supporting a hypothesized link between ice nucleating particles and organic particles associated with phytoplankton blooms. The data from this study provide a desperately needed benchmark for constraining the number of ice crystals that may form in the remote and poorly understood clouds occurring over the Southern Ocean.
Key Points
Number concentrations of ice nucleating particles over the Southern Ocean in March 2016 were a factor of 100 lower than historical surveys
The ice nucleating particle source strength of Southern Ocean seawater was lower than previous measurements in northern hemisphere seawater
Ice nucleation site densities were lower over the Southern Ocean compared to measurements of pristine air masses from other ocean basins
This paper presented the study of encapsulation process in 3D stacked chips with different microbump arrays. An experiment was carried out on two-stacked chips with bumps in perimeter array, and ...validated with numerical simulation done in FLUENT 6.3. In the numerical study, three different microbump arrays, namely full, semi-full and perimeter arrays, were studied. It was found that perimeter array provided the easiest route for epoxy molding compound (EMC) flow front advancement with the least EMC conversion and microbump impediment. Therefore, the air entrapment level was the lowest in perimeter array. For full and semi-full arrays, higher level of air entrapment was observed as there were more significant EMC conversion, microbump impediment and imbalanced EMC flow fronts. The data presentation in this paper provides a good understanding on EMC flow behavior, especially in various microbump arrays during the encapsulation process.
This work reports a precise measurement of the reactor antineutrino flux using 2.2 million inverse beta decay (IBD) events collected with the Daya Bay near detectors in 1230 days. The dominant ...uncertainty on the neutron detection efficiency is reduced by 56% with respect to the previous measurement through a comprehensive neutron calibration and detailed data and simulation analysis. The new average IBD yield is determined to be (5.91±0.09)×10−43 cm2/fission with total uncertainty improved by 29%. The corresponding mean fission fractions from the four main fission isotopes U235, U238, Pu239, and Pu241 are 0.564, 0.076, 0.304, and 0.056, respectively. The ratio of measured to predicted antineutrino yield is found to be 0.952±0.014±0.023 (1.001±0.015±0.027) for the Huber-Mueller (ILL-Vogel) model, where the first and second uncertainty are experimental and theoretical model uncertainty, respectively. This measurement confirms the discrepancy between the world average of reactor antineutrino flux and the Huber-Mueller model.
The figure shows the FSI implications to chip deformation during plastic encapsulation. The initial and final chip deformation is displayed.
•An experiment was carried out to validate the numerical ...studies.•A total of four models with through-silicon vias were studied numerically.•A constant ratio of inlet and outlet gate heights was applied.•Unfavorable deformation is anticipated when more stacked chips are employed.
This paper presents the effect of chip stacking in a 3D integrated circuit package during plastic encapsulation. An experiment was conducted on four stacked chips with bumps in a perimeter array. The flow front advancement and chip displacement in the experiment were validated by using FLUENT 6.3 and ABAQUS 6.9, respectively. A total of four models, which consist of two, three, four, and five stacked chips with through-silicon vias, were studied numerically. A simultaneous or direct solution procedure was employed to solve the variables of the fluid/structural domain. This approach provides better visualization of the actual plastic encapsulation process by considering the fluid–structure interaction phenomenon during the process. A constant ratio of inlet and outlet gate heights was applied to create a more uniform flow front advancement among the models. Results indicate that the highest displacement occurred in Model 4, which contains the most stacked chips. The highest von Mises stress was also detected in Model 4. Therefore, unfavorable deformation is anticipated when more stacked chips are employed. The experimental and numerical studies provide useful information in understanding the fluid flow of epoxy resin and subsequent structural deformation under the effect of chip stacking.
We present the organization, instrumentation, datasets, data interpretation, modeling, and accomplishments of the multinational global atmospheric measurement program AGAGE (Advanced Global ...Atmospheric Gases Experiment). AGAGE is distinguished by its capability to measure globally, at high frequency, and at multiple sites all the important species in the Montreal Protocol and all the important non-carbon-dioxide (non-CO2) gases assessed by the Intergovernmental Panel on Climate Change (CO2 is also measured at several sites). The scientific objectives of AGAGE are important in furthering our understanding of global chemical and climatic phenomena. They are the following: (1) to accurately measure the temporal and spatial distributions of anthropogenic gases that contribute the majority of reactive halogen to the stratosphere and/or are strong infrared absorbers (chlorocarbons, chlorofluorocarbons – CFCs, bromocarbons, hydrochlorofluorocarbons – HCFCs, hydrofluorocarbons – HFCs and polyfluorinated compounds (perfluorocarbons – PFCs), nitrogen trifluoride – NF3, sulfuryl fluoride – SO2F2, and sulfur hexafluoride – SF6) and use these measurements to determine the global rates of their emission and/or destruction (i.e., lifetimes); (2) to accurately measure the global distributions and temporal behaviors and determine the sources and sinks of non-CO2 biogenic–anthropogenic gases important to climate change and/or ozone depletion (methane – CH4, nitrous oxide – N2O, carbon monoxide – CO, molecular hydrogen – H2, methyl chloride – CH3Cl, and methyl bromide – CH3Br); (3) to identify new long-lived greenhouse and ozone-depleting gases (e.g., SO2F2, NF3, heavy PFCs (C4F10, C5F12, C6F14, C7F16, and C8F18) and hydrofluoroolefins (HFOs; e.g., CH2 = CFCF3) have been identified in AGAGE), initiate the real-time monitoring of these new gases, and reconstruct their past histories from AGAGE, air archive, and firn air measurements; (4) to determine the average concentrations and trends of tropospheric hydroxyl radicals (OH) from the rates of destruction of atmospheric trichloroethane (CH3CCl3), HFCs, and HCFCs and estimates of their emissions; (5) to determine from atmospheric observations and estimates of their destruction rates the magnitudes and distributions by region of surface sources and sinks of all measured gases; (6) to provide accurate data on the global accumulation of many of these trace gases that are used to test the synoptic-, regional-, and global-scale circulations predicted by three-dimensional models; and (7) to provide global and regional measurements of methane, carbon monoxide, and molecular hydrogen and estimates of hydroxyl levels to test primary atmospheric oxidation pathways at midlatitudes and the tropics. Network Information and Data Repository: http://agage.mit.edu/data or http://cdiac.ess-dive.lbl.gov/ndps/alegage.html (https://doi.org/10.3334/CDIAC/atg.db1001).
The fluid/structure interaction (FSI) investigations of stacked chip in encapsulation process of moulded underfill packaging using the two-way Coupling method with ANSYS Fluent and ANSYS Structural ...solvers are presented. The FSI study is executed with different aspect ratio of stacked chip on the mould filling during the encapsulation process. The simulation results in the FSI study is well validated with experimental setup. The epoxy moulding compound (EMC) and structure (chip) interaction is analyzed for better understanding the FSI phenomenon.Von Mises stresses experienced by the chip also be monitored for risk of chip cracking. The proposed analysis is anticipated to be a recommendation in the chip design and improvement of 3D integration packages.
In this paper, an efficient numerical approach has been adopted to analyze the fluid/structure interaction (FSI) implications to 3D IC with through-silicon via (TSV) structures during plastic ...encapsulation process, under the effect of different EMC rheological properties. A simultaneous or direct solution procedure is employed to solve the solution variables of fluid/structural domain together. Therefore, this approach can provide better visualization of the actual plastic encapsulation process by considering FSI phenomenon during the process. Different epoxy molding compound (EMC) rheological properties have resulted dissimilar fluid flow characteristics, pressure distribution, air void entrapment level, structural displacement and von Mises stress, which are discussed in the paper. Unfavorable results are obtained when higher viscous flow takes place. EMC flow front prediction has been validated with the experimental results from literature. The numerical approach and results presented in this paper are able to provide useful information for the works in optimizing plastic encapsulation process.
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