WikiEdge:ArXiv速递/2025-03-03

摘要

• 原文标题：Investigation of O interstitial diffusion in $β$-Ga$_2$O$_3$: direct approach via master diffusion equations
• 中文标题：$β$-Ga$_2$O$_3$中氧间隙扩散的研究：通过主扩散方程的直接方法
• 发布日期：2025-03-03 16:54:55+00:00
• 作者：Grace McKnight, Channyung Lee, Elif Ertekin
• 分类：cond-mat.mtrl-sci, physics.app-ph, physics.comp-ph
• 原文链接：http://arxiv.org/abs/2503.01735v1

中文摘要：单斜晶系的$\beta$-Ga$_2$O$_3$是一种有前景的宽带隙半导体材料，由于其低对称性的晶体结构，表现出复杂的各向异性扩散特性和质量传输行为。通过第一性原理计算结合主扩散方程，我们确定了中性氧间隙（$\text{O}_{\text{i}}^{0}$）和带2-电荷的氧间隙（$\text{O}_{\text{i}}^{2-}$）的三维扩散张量。通过对构型空间的系统探索，我们识别了这两种主要电荷态的稳定构型及其相应的形成能。通过考虑间隙或间隙跳跃，连接每一对低能构型，我们构建了三维扩散网络，并评估了网络中所有过渡路径的跳跃势垒。结合（i）缺陷构型及其形成能和（ii）连接它们的跳跃势垒，我们通过Onsager方法分别构建并求解了$\text{O}_{\text{i}}^{0}$和$\text{O}_{\text{i}}^{2-}$的主扩散方程，得到了相应的三维扩散张量D$_{\text{O}_{\text{i}}}^{0}$和D$_{\text{O}_{\text{i}}}^{2-}$。$\text{O}_{\text{i}}^{0}$和$\text{O}_{\text{i}}^{2-}$都表现出沿$b$轴的最快扩散，显示出显著的各向异性。沿[100]和[$\overline{2}01$]方向预测的自扩散系数与之前报道的同位素标记氧示踪实验值吻合良好，突出了该方法在捕捉复杂扩散机制方面的可靠性。

摘要

• 原文标题：Fire danger likely overestimated in future climate projections
• 中文标题：未来气候预测中火灾危险可能被高估
• 发布日期：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
• 分类：physics.ao-ph
• 原文链接：http://arxiv.org/abs/2503.01818v1

中文摘要：加拿大火灾天气指数（FWI）被广泛用于评估野火风险，并依赖于当地中午的气象数据。然而，气候模型通常仅提供每日汇总数据，这为气候变化研究中的准确FWI计算带来了挑战。本文研究了在1980年至2023年期间，使用每日近似值计算FWI95d（即超过当地每日FWI值第95百分位数的极端火灾天气日数的年计数）与标准基于中午的方法的比较。 我们的研究结果表明，使用中午特定数据计算的FWI95d在全球范围内增加了约65%，相当于44年内增加了11.66个极端火灾天气日。相比之下，每日近似值往往会高估这些趋势5-10%，其中涉及最低相对湿度的组合显示出最大的差异。在全球范围内，多达1500万平方公里的地区，特别是美国西部、南部非洲和亚洲部分地区，显示出显著的高估。在我们的每日近似方法中，偏差最小的代理是使用所有变量的每日平均值的方法。 我们建议：（i）在未来的气候模型比较项目中优先纳入次每日气象数据，以提高FWI的准确性；（ii）如果无法获得中午特定数据，则采用每日平均值近似作为偏差最小的替代方案。

摘要

• 原文标题：A COMSOL framework for predicting hydrogen embrittlement -- Part II: phase field fracture
• 中文标题：用于预测氢脆的COMSOL框架——第二部分：相场断裂
• 发布日期：2025-03-03 17:39:02+00:00
• 作者：A. Díaz, J. M. Alegre, I. I. Cuesta, E. Martínez-Pañeda
• 分类：cs.CE, physics.app-ph, physics.chem-ph
• 原文链接：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：预测氢脆需要一种稳健的建模方法，这将促进氢作为清洁能源载体的安全采用。本文提出了一种基于断裂相场描述的氢脆通用计算模型。结合本工作的第一部分，该部分描述了氢的吸收和传输过程，这使得模拟广泛的氢传输和氢脆现象成为可能。材料韧性被定义为氢含量的函数，并且结合了弹性和弹塑性材料行为，从而能够捕捉到韧性断裂和脆性断裂以及两者之间的转变。在单边裂纹板、边界层模型和三维容器案例研究中，数值评估了裂纹尖端附近氢的积累和随后的氢脆，展示了该框架的潜力。重点放在数值实现上，该实现是在有限元软件COMSOL Multiphysics中进行的，并且模型是免费提供的。

摘要

• 原文标题：Improved sensitivity in the search for rare decays of Gd isotopes
• 中文标题：改进的Gd同位素稀有衰变搜索灵敏度
• 发布日期：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
• 分类：nucl-ex, hep-ex
• 原文链接：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：钆被广泛应用于多种低本底实验中，使其同位素在原位和通过放射性纯度筛选数据中进行稀有衰变搜索成为可能。本研究利用Boulby地下筛选设施（BUGS）的超低本底高纯锗探测器，对$^{152}$Gd、$^{154}$Gd和$^{160}$Gd同位素的稀有α衰变和双β衰变模式进行了改进的搜索。使用硫酸钆八水合物$(\text{Gd}_2(\text{SO}_4)_3 \cdot 8\text{H}_2\text{O})$样品，实现了总计6.7 kg$\cdot$年的天然钆暴露量，这些样品最初在部署到超级神冈中微子实验之前进行了放射性纯度筛选。由于检测方法的原因，只有伴随γ射线发射的激发态衰变是可检测的。采用了结合先前实验结果的贝叶斯分析，得出了$10^{19} - 10^{21}$年范围内的新下限半衰期——比之前的限制提高了大约两个数量级。未观察到统计上显著的衰变信号。这些结果证明了将大规模放射性纯度筛选活动重新用于基础物理研究的有效性。

摘要

• 原文标题：A COMSOL framework for predicting hydrogen embrittlement -- Part I: coupled hydrogen transport
• 中文标题：用于预测氢脆的COMSOL框架——第一部分：耦合氢传输
• 发布日期：2025-03-03 16:57:26+00:00
• 作者：A. Díaz, J. M. Alegre, I. I. Cuesta, E. Martínez-Pañeda
• 分类：cs.CE, physics.app-ph, physics.chem-ph
• 原文链接：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：氢对金属的结构完整性构成威胁，因此预测氢与材料的相互作用是揭示氢在能源转型中作用的关键。量化裂纹和其他应力集中点前材料变形与氢扩散之间的相互作用是预测和预防氢辅助失效的关键。在这项工作中，提出了一个广义的理论和计算框架，首次涵盖了：(i) 应力辅助扩散，(ii) 由于多种陷阱类型导致的氢捕获，严格考虑了位错陷阱位点的生成速率，(iii) 通过位错的氢传输，(iv) 平衡（Oriani）和非平衡（McNabb-Foster）捕获动力学，(v) 氢诱导软化，以及 (vi) 氢吸收，考虑了静水应力和局部电化学的作用。特别强调了在 COMSOL Multiphysics 中的数值实现，发布了相关模型并讨论了稳定性、离散化和求解器细节。框架的每个元素都与文献中的结果进行了独立基准测试，并讨论了其对氢辅助断裂预测的影响。本工作的第二部分（第二部分）展示了如何将这些裂纹尖端预测与裂纹扩展模拟相结合。

摘要

• 原文标题：Entropic learning enables skilful forecasts of ENSO phase at up to two years lead time
• 中文标题：熵学习能够在长达两年的提前时间内对ENSO相位进行熟练预测
• 发布日期：2025-03-03 11:06:10+00:00
• 作者：Michael Groom, Davide Bassetti, Illia Horenko, Terence J. O'Kane
• 分类：physics.comp-ph, physics.ao-ph
• 原文链接：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：本文基于先前的工作，将熵最优稀疏概率近似（eSPA）机器学习算法应用于ENSO相位的分类任务，该任务由Niño3.4指数确定（Groom等人，Artif. Intell. Earth Syst., 2024）。在本研究中，训练和验证熵学习模型时仅使用了卫星时代的观测和再分析数据，并在2012年至2022年期间进行了一整套后报（最大提前期为24个月），以确定样本外技能。用于预测的特征包括全球海表温度的延迟嵌入EOF分析中的主要主成分、热带太平洋赤道处温度的垂直导数（作为温跃层变化的代理）以及热带太平洋的纬向和经向风应力。尽管可用于训练的数据实例数量有限（从最早的后报的350个月平均值到截至2024年12月的520个月平均值），eSPA在这种小数据情况下避免了过拟合，并生成了与国际气候与社会研究所（IRI）ENSO预测羽流生成的组合（基于模型的）概率预测具有可比技能的概率预测。在比IRI羽流更长的提前期下，eSPA在排名概率技能评分方面保持了23个月的技能，在ROC曲线下面积方面保持了24个月的技能，且计算成本仅为运行动态集合预测系统的一小部分。此外，eSPA成功预测了2015/16和2018/19年厄尔尼诺事件（提前24个月）、2016/17、2017/18和2020/21年拉尼娜事件（提前24个月）以及2021/22和2022/23年拉尼娜事件（提前12和9个月）。

摘要

• 原文标题：Scanning HTML at Tens of Gigabytes per Second on ARM Processors
• 中文标题：在ARM处理器上以每秒数十GB的速度扫描HTML
• 发布日期：2025-03-03 15:38:20+00:00
• 作者：Daniel Lemire
• 分类：cs.DS, cs.AR
• 原文链接：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：现代处理器具有一次性处理16字节或更多字节的指令。这些指令被称为SIMD，即单指令多数据。最近的进展利用SIMD指令加速了常见互联网格式（如JSON和base64）的解析。在HTML解析过程中，它们通过一种称为向量化分类的策略快速识别特定字符。我们回顾了这些技术，并将其与一种更快的替代方案进行了比较。我们在最新的ARM处理器上测量到，与传统方法相比，HTML扫描的性能提高了20倍。我们的研究结果突显了基于SIMD的算法在优化Web浏览器性能方面的潜力。

摘要

• 原文标题：Unveiling temperature and phase boundaries in laser-driven shocked and released copper: insights from ultra-fast X-ray Absorption Spectroscopy up to 300 GPa
• 中文标题：揭示激光驱动冲击和释放铜中的温度和相边界：来自高达300 GPa的超快X射线吸收光谱的见解
• 发布日期：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
• 分类：cond-mat.mtrl-sci, physics.plasm-ph
• 原文链接：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：铜（Cu）因其优异的热学和电学性能在工业中被广泛应用。研究铜在高压高温下的性质对于核聚变研究具有重要意义，因为在超高速撞击中使用的弹丸和飞片通常由铜制成，铜也被用于核聚变靶的设计中。最近，通过X射线衍射在冲击压缩的铜中检测到了固相（fcc）-固相（bcc）相变。本文中，我们通过单脉冲（100 ps FWHM）X射线吸收光谱（XAS）研究了冲击压缩铜在高达300 GPa和7100 K条件下的性质。基于XAS光谱的分析，我们提供了沿Hugoniot线的结构识别和体温度测量，直至熔化。在释放条件下（即冲击波突破后的较晚时间）收集的XAS光谱有助于约束实验中的fcc-bcc和固液相边界。特别是，我们首次报告了冲击压缩铜在熔化平台上的体温度测量结果，该平台位于237(40) GPa和5750(1130) K之间以及261(27) GPa和6240(1155) K之间，并在300 GPa和7100 K条件下对液态铜进行了测量。

摘要

• 原文标题：Improving the Efficiency of VVC using Partitioning of Reference Frames
• 中文标题：通过参考帧划分提高VVC的效率
• 发布日期：2025-03-03 11:10:37+00:00
• 作者：Kamran Qureshi, Hadi Amirpour, Christian Timmerer
• 分类：cs.MM
• 原文链接：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：为了应对高质量视频日益增长的需求，多功能视频编码（VVC）于2020年发布，基于其前身HEVC的混合编码架构，在相同视觉质量下实现了约50%的码率降低。VVC引入了更灵活的块划分，以增加编码复杂度为代价提升了压缩效率。为了在实际应用中高效使用VVC，优化是必不可少的。VVenC是一个优化的开源VVC编码器，引入了多种预设以解决压缩效率与编码器复杂度之间的权衡问题。尽管为每个预设选择了一组优化的编码工具，但编码器预设中的率失真（RD）搜索空间仍然对高效编码器实现提出了挑战。在本文中，我们提出了基于参考帧的早期终止（ETRF），它改善了编码效率与时间复杂度之间的权衡，并定位为中等和快速预设之间的新预设。通过利用较低时间层中参考帧的CTU划分图，加速了较高时间层中帧的编码。结果显示，与中等预设相比，编码时间减少了约21%。特别是对于具有高空间和时间复杂度的视频，这些视频通常需要更长的编码时间，所提出的方法在码率节省和编码时间之间实现了比快速预设更好的权衡。