WikiEdge:ArXiv速遞/2025-03-03
摘要
- 原文標題：Investigation of O interstitial diffusion in $β$-Ga$_2$O$_3$: direct approach via master diffusion equations
- 中文標題：$β$-Ga$_2$O$_3$中氧間隙擴散的研究：通過主擴散方程的直接方法
- 發布日期：2025-03-03 16:54:55+00:00
- 作者：Grace McKnight, Channyung Lee, Elif Ertekin
- 分類：cond-mat.mtrl-sci, physics.app-ph, physics.comp-ph
- 原文鏈接：http://arxiv.org/abs/2503.01735v1
中文摘要：單斜晶系的$\beta$-Ga$_2$O$_3$是一種有前景的寬帶隙半導體材料，由於其低對稱性的晶體結構，表現出複雜的各向異性擴散特性和質量傳輸行為。通過第一性原理計算結合主擴散方程，我們確定了中性氧間隙（$\text{O}_{\text{i}}^{0}$）和帶2-電荷的氧間隙（$\text{O}_{\text{i}}^{2-}$）的三維擴散張量。通過對構型空間的系統探索，我們識別了這兩種主要電荷態的穩定構型及其相應的形成能。通過考慮間隙或間隙跳躍，連接每一對低能構型，我們構建了三維擴散網絡，並評估了網絡中所有過渡路徑的跳躍勢壘。結合（i）缺陷構型及其形成能和（ii）連接它們的跳躍勢壘，我們通過Onsager方法分別構建並求解了$\text{O}_{\text{i}}^{0}$和$\text{O}_{\text{i}}^{2-}$的主擴散方程，得到了相應的三維擴散張量D$_{\text{O}_{\text{i}}}^{0}$和D$_{\text{O}_{\text{i}}}^{2-}$。$\text{O}_{\text{i}}^{0}$和$\text{O}_{\text{i}}^{2-}$都表現出沿$b$軸的最快擴散，顯示出顯著的各向異性。沿[100]和[$\overline{2}01$]方向預測的自擴散係數與之前報道的同位素標記氧示蹤實驗值吻合良好，突出了該方法在捕捉複雜擴散機制方面的可靠性。
摘要
- 原文標題：Fire danger likely overestimated in future climate projections
- 中文標題：未來氣候預測中火災危險可能被高估
- 發布日期：2025-03-03 18:42:50+00:00
- 作者：Aurora Matteo, Ginés Garnés-Morales, Alberto Moreno, Ribeiro Andreia, César Azorín-Molina, Joaquín Bedia, Francesca Di Giuseppe, Robert J. H. Dunn, Sixto Herrera, Antonello Provenzale, Yann Quilcaille, Miguel Ángel Torres Vázquez, Marco Turco
- 分類：physics.ao-ph
- 原文鏈接：http://arxiv.org/abs/2503.01818v1
中文摘要：加拿大火災天氣指數（FWI）被廣泛用於評估野火風險，並依賴於當地中午的氣象數據。然而，氣候模型通常僅提供每日匯總數據，這為氣候變化研究中的準確FWI計算帶來了挑戰。本文研究了在1980年至2023年期間，使用每日近似值計算FWI95d（即超過當地每日FWI值第95百分位數的極端火災天氣日數的年計數）與標準基於中午的方法的比較。 我們的研究結果表明，使用中午特定數據計算的FWI95d在全球範圍內增加了約65%，相當於44年內增加了11.66個極端火災天氣日。相比之下，每日近似值往往會高估這些趨勢5-10%，其中涉及最低相對濕度的組合顯示出最大的差異。在全球範圍內，多達1500萬平方公里的地區，特別是美國西部、南部非洲和亞洲部分地區，顯示出顯著的高估。在我們的每日近似方法中，偏差最小的代理是使用所有變量的每日平均值的方法。 我們建議：（i）在未來的氣候模型比較項目中優先納入次每日氣象數據，以提高FWI的準確性；（ii）如果無法獲得中午特定數據，則採用每日平均值近似作為偏差最小的替代方案。
摘要
- 原文標題：A COMSOL framework for predicting hydrogen embrittlement -- Part II: phase field fracture
- 中文標題：用於預測氫脆的COMSOL框架——第二部分：相場斷裂
- 發布日期：2025-03-03 17:39:02+00:00
- 作者：A. Díaz, J. M. Alegre, I. I. Cuesta, E. Martínez-Pañeda
- 分類：cs.CE, physics.app-ph, physics.chem-ph
- 原文鏈接：http://arxiv.org/abs/2503.01765v1
原文摘要：Prediction of hydrogen embrittlement requires a robust modelling approach and this will foster the safe adoption of hydrogen as a clean energy vector. A generalised computational model for hydrogen embrittlement is here presented, based on a phase field description of fracture. In combination with Part I of this work, which describes the process of hydrogen uptake and transport, this allows simulating a wide range of hydrogen transport and embrittlement phenomena. The material toughness is defined as a function of the hydrogen content and both elastic and elastic-plastic material behaviour are incorporated, enabling to capture both ductile and brittle fractures, and the transition from one to the other. The accumulation of hydrogen near a crack tip and subsequent embrittlement is numerically evaluated in a single-edge cracked plate, a boundary layer model and a 3D vessel case study, demonstrating the potential of the framework. Emphasis is placed on the numerical implementation, which is carried out in the finite element package COMSOL Multiphysics, and the models are made freely available. 中文摘要：預測氫脆需要一種穩健的建模方法，這將促進氫作為清潔能源載體的安全採用。本文提出了一種基於斷裂相場描述的氫脆通用計算模型。結合本工作的第一部分，該部分描述了氫的吸收和傳輸過程，這使得模擬廣泛的氫傳輸和氫脆現象成為可能。材料韌性被定義為氫含量的函數，並且結合了彈性和彈塑性材料行為，從而能夠捕捉到韌性斷裂和脆性斷裂以及兩者之間的轉變。在單邊裂紋板、邊界層模型和三維容器案例研究中，數值評估了裂紋尖端附近氫的積累和隨後的氫脆，展示了該框架的潛力。重點放在數值實現上，該實現是在有限元軟件COMSOL Multiphysics中進行的，並且模型是免費提供的。
摘要
- 原文標題：Improved sensitivity in the search for rare decays of Gd isotopes
- 中文標題：改進的Gd同位素稀有衰變搜索靈敏度
- 發布日期：2025-03-03 15:20:27+00:00
- 作者：B. Lehnert, S. S. Nagorny, M. Thiesse, F. Ferella, M. Laubenstein, E. Meehan, S. Nisi, P. R. Scovell
- 分類：nucl-ex, hep-ex
- 原文鏈接：http://arxiv.org/abs/2503.01641v1
原文摘要：Gadolinium is widely used in multiple low-background experiments, making its isotopes accessible for rare decay searches both in-situ and through radiopurity screening data. This study presents an improved search for rare alpha and double-beta decay modes in $^{152}$Gd, $^{154}$Gd, and $^{160}$Gd isotopes using ultra-low background HPGe detectors at the Boulby Underground Screening (BUGS) facility. A total exposure of 6.7 kg$\cdot$yr of natural gadolinium was achieved using gadolinium sulfate octahydrate $(\text{Gd}_2(\text{SO}_4)_3 \cdot 8\text{H}_2\text{O})$ samples, originally screened for radiopurity prior to their deployment in the Super-Kamiokande neutrino experiment. Due to the detection methodology, only decays into excited states accompanied by gamma-ray emission were accessible. A Bayesian analysis incorporating prior experimental results was employed, leading to new lower half-life limits in the range of $10^{19} - 10^{21}$ years - an improvement of approximately two orders of magnitude over previous constraints. No statistically significant decay signals were observed. These results demonstrate the effectiveness of repurposing large-scale radiopurity screening campaigns for fundamental physics research. 中文摘要：釓被廣泛應用於多種低本底實驗中，使其同位素在原位和通過放射性純度篩選數據中進行稀有衰變搜索成為可能。本研究利用Boulby地下篩選設施（BUGS）的超低本底高純鍺探測器，對$^{152}$Gd、$^{154}$Gd和$^{160}$Gd同位素的稀有α衰變和雙β衰變模式進行了改進的搜索。使用硫酸釓八水合物$(\text{Gd}_2(\text{SO}_4)_3 \cdot 8\text{H}_2\text{O})$樣品，實現了總計6.7 kg$\cdot$年的天然釓暴露量，這些樣品最初在部署到超級神岡中微子實驗之前進行了放射性純度篩選。由於檢測方法的原因，只有伴隨γ射線發射的激發態衰變是可檢測的。採用了結合先前實驗結果的貝葉斯分析，得出了$10^{19} - 10^{21}$年範圍內的新下限半衰期——比之前的限制提高了大約兩個數量級。未觀察到統計上顯著的衰變信號。這些結果證明了將大規模放射性純度篩選活動重新用於基礎物理研究的有效性。
摘要
- 原文標題：A COMSOL framework for predicting hydrogen embrittlement -- Part I: coupled hydrogen transport
- 中文標題：用於預測氫脆的COMSOL框架——第一部分：耦合氫傳輸
- 發布日期：2025-03-03 16:57:26+00:00
- 作者：A. Díaz, J. M. Alegre, I. I. Cuesta, E. Martínez-Pañeda
- 分類：cs.CE, physics.app-ph, physics.chem-ph
- 原文鏈接：http://arxiv.org/abs/2503.01736v1
原文摘要：Hydrogen threatens the structural integrity of metals and thus predicting hydrogen-material interactions is key to unlocking the role of hydrogen in the energy transition. Quantifying the interplay between material deformation and hydrogen diffusion ahead of cracks and other stress concentrators is key to the prediction and prevention of hydrogen-assisted failures. In this work, a generalised theoretical and computational framework is presented that for the first time encompasses: (i) stress-assisted diffusion, (ii) hydrogen trapping due to multiple trap types, rigorously accounting for the rate of creation of dislocation trap sites, (iii) hydrogen transport through dislocations, (iv) equilibrium (Oriani) and non-equilibrium (McNabb-Foster) trapping kinetics, (v) hydrogen-induced softening, and (vi) hydrogen uptake, considering the role of hydrostatic stresses and local electrochemistry. Particular emphasis is placed on the numerical implementation in COMSOL Multiphysics, releasing the relevant models and discussing stability, discretisation and solver details. Each of the elements of the framework is independently benchmarked against results from the literature and implications for the prediction of hydrogen-assisted fractures are discussed. The second part of this work (Part II) shows how these crack tip predictions can be combined with crack growth simulations. 中文摘要：氫對金屬的結構完整性構成威脅，因此預測氫與材料的相互作用是揭示氫在能源轉型中作用的關鍵。量化裂紋和其他應力集中點前材料變形與氫擴散之間的相互作用是預測和預防氫輔助失效的關鍵。在這項工作中，提出了一個廣義的理論和計算框架，首次涵蓋了：(i) 應力輔助擴散，(ii) 由於多種陷阱類型導致的氫捕獲，嚴格考慮了位錯陷阱位點的生成速率，(iii) 通過位錯的氫傳輸，(iv) 平衡（Oriani）和非平衡（McNabb-Foster）捕獲動力學，(v) 氫誘導軟化，以及 (vi) 氫吸收，考慮了靜水應力和局部電化學的作用。特別強調了在 COMSOL Multiphysics 中的數值實現，發布了相關模型並討論了穩定性、離散化和求解器細節。框架的每個元素都與文獻中的結果進行了獨立基準測試，並討論了其對氫輔助斷裂預測的影響。本工作的第二部分（第二部分）展示了如何將這些裂紋尖端預測與裂紋擴展模擬相結合。
摘要
- 原文標題：Entropic learning enables skilful forecasts of ENSO phase at up to two years lead time
- 中文標題：熵學習能夠在長達兩年的提前時間內對ENSO相位進行熟練預測
- 發布日期：2025-03-03 11:06:10+00:00
- 作者：Michael Groom, Davide Bassetti, Illia Horenko, Terence J. O'Kane
- 分類：physics.comp-ph, physics.ao-ph
- 原文鏈接：http://arxiv.org/abs/2503.01412v1
原文摘要：This paper builds on previous work in applying the entropy-optimal Sparse Probabilistic Approximation (eSPA) machine learning algorithm to the task of classifying the phase of ENSO, as determined by the Ni\~no3.4 index (Groom et al., Artif. Intell. Earth Syst., 2024). In this study, only observations and reanalyses from the satellite era are employed when training and validating the entropic learning models, and a full set of hindcasts are performed over the period from 2012 to 2022 (with a maximum lead time of 24 months) in order to determine out-of-sample skill. The features used for prediction are the leading principal components from a delay-embedded EOF analysis of global sea surface temperature, the vertical derivative of temperature at the equator in the tropical Pacific (a proxy for thermocline variability) and the zonal and meridional wind stresses in the tropical Pacific. Despite the limited number of data instances available for training (ranging from 350 monthly averages for the earliest hindcast to 520 as of December 2024), eSPA is shown to avoid overfitting in this small data regime and produces probabilistic forecasts with comparable skill to the combined (model-based) probabilistic forecasts produced from the International Research Institute for Climate and Society (IRI) ENSO prediction plume. At lead times longer than those available from the IRI plume, eSPA maintains skill out to 23 months in terms of the ranked probability skill score and 24 months in terms of the area under the ROC curve, all at a small fraction of the computational cost of running a dynamical ensemble prediction system. Furthermore, eSPA is shown to successfully forecast the 2015/16 and 2018/19 El Ni\~no events at 24 months lead time, the 2016/17, 2017/18 and 2020/21 La Ni\~na events at 24 months lead time and the 2021/22 and 2022/23 La Ni\~na events at 12 and 9 months lead time. 中文摘要：本文基於先前的工作，將熵最優稀疏概率近似（eSPA）機器學習算法應用於ENSO相位的分類任務，該任務由Niño3.4指數確定（Groom等人，Artif. Intell. Earth Syst., 2024）。在本研究中，訓練和驗證熵學習模型時僅使用了衛星時代的觀測和再分析數據，並在2012年至2022年期間進行了一整套後報（最大提前期為24個月），以確定樣本外技能。用於預測的特徵包括全球海表溫度的延遲嵌入EOF分析中的主要主成分、熱帶太平洋赤道處溫度的垂直導數（作為溫躍層變化的代理）以及熱帶太平洋的緯向和經向風應力。儘管可用於訓練的數據實例數量有限（從最早的後報的350個月平均值到截至2024年12月的520個月平均值），eSPA在這種小數據情況下避免了過擬合，並生成了與國際氣候與社會研究所（IRI）ENSO預測羽流生成的組合（基於模型的）概率預測具有可比技能的概率預測。在比IRI羽流更長的提前期下，eSPA在排名概率技能評分方面保持了23個月的技能，在ROC曲線下面積方面保持了24個月的技能，且計算成本僅為運行動態集合預測系統的一小部分。此外，eSPA成功預測了2015/16和2018/19年厄爾尼諾事件（提前24個月）、2016/17、2017/18和2020/21年拉尼娜事件（提前24個月）以及2021/22和2022/23年拉尼娜事件（提前12和9個月）。
摘要
- 原文標題：Scanning HTML at Tens of Gigabytes per Second on ARM Processors
- 中文標題：在ARM處理器上以每秒數十GB的速度掃描HTML
- 發布日期：2025-03-03 15:38:20+00:00
- 作者：Daniel Lemire
- 分類：cs.DS, cs.AR
- 原文鏈接：http://arxiv.org/abs/2503.01662v1
原文摘要：Modern processors have instructions to process 16 bytes or more at once. These instructions are called SIMD, for single instruction, multiple data. Recent advances have leveraged SIMD instructions to accelerate parsing of common Internet formats such as JSON and base64. During HTML parsing, they quickly identify specific characters with a strategy called vectorized classification. We review their techniques and compare them with a faster alternative. We measure a 20-fold performance improvement in HTML scanning compared to traditional methods on recent ARM processors. Our findings highlight the potential of SIMD-based algorithms for optimizing Web browser performance. 中文摘要：現代處理器具有一次性處理16字節或更多字節的指令。這些指令被稱為SIMD，即單指令多數據。最近的進展利用SIMD指令加速了常見互聯網格式（如JSON和base64）的解析。在HTML解析過程中，它們通過一種稱為向量化分類的策略快速識別特定字符。我們回顧了這些技術，並將其與一種更快的替代方案進行了比較。我們在最新的ARM處理器上測量到，與傳統方法相比，HTML掃描的性能提高了20倍。我們的研究結果突顯了基於SIMD的算法在優化Web瀏覽器性能方面的潛力。
摘要
- 原文標題：Unveiling temperature and phase boundaries in laser-driven shocked and released copper: insights from ultra-fast X-ray Absorption Spectroscopy up to 300 GPa
- 中文標題：揭示激光驅動衝擊和釋放銅中的溫度和相邊界：來自高達300 GPa的超快X射線吸收光譜的見解
- 發布日期：2025-03-03 09:23:22+00:00
- 作者：Sofia Balugani, Jean-Alexis Hernandez, Fabien Brieuc, James Boust, Philipp Hesselbach, Nicolas Sévelin-Radiguet, Vanina Recoules, Olivier Mathon, Daniel E. Eakins, Hugo Doyle, Alessandra Ravasio, Raffaella Torchio
- 分類：cond-mat.mtrl-sci, physics.plasm-ph
- 原文鏈接：http://arxiv.org/abs/2503.01939v1
原文摘要：Cu is an ubiquitous material used in industry for its great thermal and electrical properties. Studying the high-pressure high temperature properties of copper (Cu) is relevant for nuclear fusion research as projectiles and flyers used in hypervelocity impacts are generally made of copper, where it is used also in the design of the nuclear fusion targets. Recently, a solid (fcc)-solid (bcc) phase transition has been detected in shock compressed Cu with X-Ray Diffraction. Here, we present a study on shock compressed copper up to 300 GPa and 7100 K probed by single pulse (100 ps FWHM) X-ray Absorption Spectroscopy (XAS). Based on the analysis of the XAS spectra, we provide structural identification and bulk temperature measurements along the Hugoniot up to the melting. The collection of XAS spectra under release conditions, i.e. at later times than the breakout time of the shock wave, helped constraining the experimental fcc-bcc and solid-liquid phase boundaries. In particular, we report the first bulk temperature measurement in shock compressed copper on the melting plateau located between 237(40) GPa and 5750(1130) K and 261 (27) GPa and 6240 (1155) K and on liquid copper at 300 GPa and 7100 K. 中文摘要：銅（Cu）因其優異的熱學和電學性能在工業中被廣泛應用。研究銅在高壓高溫下的性質對於核聚變研究具有重要意義，因為在超高速撞擊中使用的彈丸和飛片通常由銅製成，銅也被用於核聚變靶的設計中。最近，通過X射線衍射在衝擊壓縮的銅中檢測到了固相（fcc）-固相（bcc）相變。本文中，我們通過單脈衝（100 ps FWHM）X射線吸收光譜（XAS）研究了衝擊壓縮銅在高達300 GPa和7100 K條件下的性質。基於XAS光譜的分析，我們提供了沿Hugoniot線的結構識別和體溫度測量，直至熔化。在釋放條件下（即衝擊波突破後的較晚時間）收集的XAS光譜有助於約束實驗中的fcc-bcc和固液相邊界。特別是，我們首次報告了衝擊壓縮銅在熔化平台上的體溫度測量結果，該平台位於237(40) GPa和5750(1130) K之間以及261(27) GPa和6240(1155) K之間，並在300 GPa和7100 K條件下對液態銅進行了測量。
摘要
- 原文標題：Improving the Efficiency of VVC using Partitioning of Reference Frames
- 中文標題：通過參考幀劃分提高VVC的效率
- 發布日期：2025-03-03 11:10:37+00:00
- 作者：Kamran Qureshi, Hadi Amirpour, Christian Timmerer
- 分類：cs.MM
- 原文鏈接：http://arxiv.org/abs/2503.01415v1
原文摘要：In response to the growing demand for high-quality videos, Versatile Video Coding (VVC) was released in 2020, building on the hybrid coding architecture of its predecessor, HEVC, achieving about 50% bitrate reduction for the same visual quality. It introduces more flexible block partitioning, enhancing compression efficiency at the cost of increased encoding complexity. To make efficient use of VVC in practical applications, optimization is essential. VVenC, an optimized open-source VVC encoder, introduces multiple presets to address the trade-off between compression efficiency and encoder complexity. Although an optimized set of encoding tools has been selected for each preset, the rate-distortion (RD) search space in the encoder presets still poses a challenge for efficient encoder implementations. In this paper, we propose Early Termination using Reference Frames (ETRF), which improves the trade-off between encoding efficiency and time complexity and positions itself as a new preset between medium and fast presets. The CTU partitioning map of the reference frames in lower temporal layers is employed to accelerate the encoding of frames in higher temporal layers. The results show a reduction in the encoding time of around 21% compared to the medium preset. Specifically, for videos with high spatial and temporal complexities, which typically require longer encoding times, the proposed method achieves a better trade-off between bitrate savings and encoding time compared to the fast preset. 中文摘要：摘要：為了應對高質量視頻日益增長的需求，多功能視頻編碼（VVC）於2020年發布，基於其前身HEVC的混合編碼架構，在相同視覺質量下實現了約50%的碼率降低。VVC引入了更靈活的塊劃分，以增加編碼複雜度為代價提升了壓縮效率。為了在實際應用中高效使用VVC，優化是必不可少的。VVenC是一個優化的開源VVC編碼器，引入了多種預設以解決壓縮效率與編碼器複雜度之間的權衡問題。儘管為每個預設選擇了一組優化的編碼工具，但編碼器預設中的率失真（RD）搜索空間仍然對高效編碼器實現提出了挑戰。在本文中，我們提出了基於參考幀的早期終止（ETRF），它改善了編碼效率與時間複雜度之間的權衡，並定位為中等和快速預設之間的新預設。通過利用較低時間層中參考幀的CTU劃分圖，加速了較高時間層中幀的編碼。結果顯示，與中等預設相比，編碼時間減少了約21%。特別是對於具有高空間和時間複雜度的視頻，這些視頻通常需要更長的編碼時間，所提出的方法在碼率節省和編碼時間之間實現了比快速預設更好的權衡。