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2606.09020 2026-06-09 math-ph math.MP 新提交

On an $n-$Dimensional Travel Time Tomography Problem

关于一个$n$维走时层析成像问题

Michael V. Klibanov

AI总结 针对形式确定不完全输入数据的n维走时层析成像问题,提出半离散化方法并利用截断傅里叶级数展开,证明Lipschitz稳定性估计和唯一性。

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AI中文摘要

在他们的开创性工作中,Herglotz (1905) 和 Wiechert 与 Zoeppritz (1907) 解决了一维情况下的所谓走时层析成像问题(TTTP)。然而,对于具有形式确定不完全输入数据的 n 维(n≥2)TTTP,关于稳定性估计和唯一性定理的问题在一百多年后仍然基本未解决。“形式确定输入数据”意味着输入数据中自由变量的数量 p 等于未知的右端项(控制非线性程函偏微分方程)中自由变量的数量 n,即 p=n。先前的一些出版物表明,可以为形式确定输入数据的 TTTP 开发出性能良好的数值方法,这表明此类数据在实际应用中的重要性。这是第一篇解决上述问题的出版物。更精确地说,我们考虑一个半离散情况,其中由程函方程生成的偏微分方程关于 n-1 个变量用有限差分写出。此外,假设该半离散偏微分方程的解通过一个关于特殊正交函数基(仅依赖于点源位置)的截断傅里叶级数表示。在这些条件下,证明了 Lipschitz 稳定性估计,并且该估计蕴含唯一性。本文的一个重要工具是新的 Carleman 估计。引入了 Carleman 加权空间。此前,Carleman 估计未被应用于解决 TTTP 的稳定性估计和唯一性定理问题。

英文摘要

In their seminal works Herglotz (1905) and Wiechert and Zoeppritz (1907) have solved the so-called Travel Time Tomography Problem (TTTP) in the 1-D case. However, the question about stability estimates and uniqueness theorems for an n-D n>= 2 TTTP with formally determined incomplete input data still mostly stands open after more than one hundred years period. \textquotedblleft Formally determined input data" means that the number p of free variables in the input data equals the number $n$ of free variables in the unknown right hand side of the governing nonliniear eikonal PDE, p=n. Some previous publications demonstrate that it is possible to develop well performed numerical methods for the TTTP with formally determined input data, which indicates the importance of such data for practical applications. This is the first publication in which the above question is addressed. More precisely, we consider a semi-discrete case, in which a PDE generated by the eikonal equation is written in finite differences with respect to n-1 variables. In addition, it is assumed that the solution of that semi-discrete PDE is represented via a truncated Fourier-like series with respect to a special orthonormal basis of functions, which depend only on the position of the point source. Under these conditions, Lipschitz stability estimate is proven, and this estimate implies uniqueness. An important tool of this paper is a new Carleman estimate. Carleman Weighted Spaces are introduced. Carleman estimates were not applied previously to address questions about stability estimates and uniqueness theorems for the TTTP.

2606.09018 2026-06-09 cs.GR 新提交

MaterialClusterGS: Palette-Based Material Decomposition and Physically-Based Relighting with 2D Gaussian Splatting

MaterialClusterGS: 基于调色板的材质分解与基于物理的2D高斯泼溅重光照

Hao Zhang, Ang Li, Boyan Du, Junke Zhu, Fei Zhu, Meng Gai, Zhangjin Huang, Guoping Wang, Sheng Li

AI总结 提出MaterialClusterGS框架,通过共享BRDF原型调色板和连续空间材质场,实现2D高斯泼溅的物理重光照与材质编辑,解决逐基元分解的不一致问题。

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AI中文摘要

我们提出MaterialClusterGS,一个基于调色板的材质分解框架,用于2D高斯泼溅,实现基于物理的重光照和材质编辑。现有的高斯逆渲染方法通常为每个基元分配独立的BRDF参数。虽然灵活,但这种局部拟合策略使材质恢复高度欠约束:阴影、间接光照、几何误差和可见性残差可以被吸收到数千个略有不同的局部材质估计中。同时,最近的基于调色板的外观方法仅在RGB空间中操作,没有建模物理材质或光照。为弥合这一差距,我们使用一个紧凑的全局调色板来表示场景材质,该调色板由共享的BRDF原型组成,通过连续的空间材质场分配。没有共享的材质结构,编辑一个区域不会一致地传播到同一材质的其他区域,使得逐基元分解对于编辑不实用。我们在基于物理的渲染目标下联合优化材质场、调色板原型和环境光照。得到的框架恢复出紧凑、空间一致的属性,可直接用于材质编辑、重光照和迁移。

英文摘要

We present MaterialClusterGS, a palette-based material decomposition framework for 2D Gaussian Splatting that enables physically based relighting and material editing. Existing Gaussian inverse rendering methods typically assign independent BRDF parameters to individual primitives. While flexible, this local fitting strategy makes material recovery highly under-constrained: shadows, indirect illumination, geometric errors, and visibility residuals can be absorbed into thousands of slightly different local material estimates. Meanwhile, recent palette-based appearance methods operate solely in RGB space without modeling physical materials or illumination. To bridge this gap, we represent scene materials using a compact global palette of shared BRDF prototypes assigned via a continuous spatial material field. Without shared material structure, editing one region does not propagate consistently to others of the same material, making per-primitive decompositions impractical for editing. We jointly optimize the material field, palette prototypes, and environment lighting under a physically based rendering objective. The resulting framework recovers compact, spatially coherent attributes directly usable for material editing, relighting, and transfer.

2606.09017 2026-06-09 math.DG 新提交

The Ollivier Ricci flow with prescribed curvature on infinite graphs

具有预定曲率的无穷图上的Ollivier Ricci流

Bobo Hua, Yong Lin, Shuang Liu

AI总结 本文研究无穷图上具有预定曲率的Ricci流,建立了解的存在唯一性,并在两种条件下证明了围长至少为6的图的Ricci流收敛性,与Rodin和Sullivan的六边形圆填充结论一致。

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AI中文摘要

本文考虑无穷图上具有预定曲率的Ricci流,其形式为 \n\begin{equation*}\label{flow-equation3}\n \frac{d}{dt}\omega(t)=-(\kappa(t)-\kappa^*)\omega(t),~~ t>0,\n\end{equation*}\n其中$\omega$是边权,$\kappa$和$\kappa^*$分别是边集上的Lin-Lu-Yau Ricci曲率和预定曲率。首先,我们建立了Ricci流解的存在唯一性。此外,我们证明了在两种不同条件下围长至少为6的图的Ricci流收敛性。我们的收敛结果与Rodin和Sullivan (J Differ Geom, 26(2) 1987)的结论一致,即平面上具有六边形模式的圆填充是正六边形填充。

英文摘要

In this paper, we consider the Ricci flow with prescribed curvature on infinite graphs, which reads as \begin{equation*}\label{flow-equation3} \frac{d}{dt}ω(t)=-(κ(t)-κ^*)ω(t),~~ t>0, \end{equation*} where $ω$ is the edge weight, $κ$ and $κ^*$ are Lin-Lu-Yau Ricci curvature and the prescribed curvature on the set of edges, respectively. First, we establish the existence and uniqueness of the solution to the Ricci flow. Furthermore, we prove the convergence of the Ricci flow for graphs with girth at least 6 under two different conditions. Our convergence result aligns with the conclusion of Rodin and Sullivan (J Differ Geom, 26(2) 1987) that a circle packing in the plane with the hexagonal pattern is the regular hexagonal packing.

2606.09016 2026-06-09 math.AC 新提交

When is the strict closure of rings finitely generated?

环的严格闭包何时是有限生成的?

Ryotaro Isobe

AI总结 本文研究任意维数环的严格闭包的有限生成性,给出了诺特局部环的严格闭包作为模有限生成的充分条件,并刻画了优良环上严格闭包的有限生成性。

Comments Preprint version, 4 pages. The final authenticated version is to appear in Archiv der Mathematik

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AI中文摘要

本文研究了任意维数环的严格闭包的有限生成性。对于诺特局部环$(R, \mathfrak{m})$,我们给出了一个充分条件,使得严格闭包$R^*$作为$R$-模是有限生成的。利用这一结果,我们刻画了优良环上严格闭包的有限生成性。

英文摘要

This paper investigates the finite generation of the strict closure of rings in arbitrary dimension. For a Noetherian local ring $(R, \mathfrak{m})$, we provide a sufficient condition under which the strict closure $R^*$ is finitely generated as an $R$-module. Using this result, we characterize the finite generation of the strict closure over excellent rings.

2606.09015 2026-06-09 math.NT 新提交

Degenerate generalized Stirling operators of the first kind arising from generalized Heisenberg algebra

源于广义海森堡代数的第一类退化广义斯特林算子

Taekyun Kim, Dae San Kim

AI总结 研究第一类退化广义斯特林算子,填补广义海森堡代数运算微积与退化微积的空白,推导其乘积分解、递推关系和移位恒等式,并建立与第二类算子的正交关系。

Comments 9 pages

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AI中文摘要

本文研究了第一类退化广义斯特林算子,填补了统一退化微积的广义海森堡代数GHA运算微积中的空白。作为第二类退化广义斯特林算子的逆,这些算子将单项式算子乘积表示为退化阶乘算子。我们推导了这些算子的关键结构和组合性质,包括显式乘积分解、基本递推关系和运算移位恒等式。此外,我们建立了第一类和第二类退化广义斯特林算子之间的正交关系,为函数量子代数提供了完整的组合框架。

英文摘要

This paper investigates the degenerate generalized Stirling operators of the first kind bridging a gap in the operational calculus of the generalized Heisenberg algebra GHA unified with degenerate calculus. As they are the inverse of the degenerate generalized Stirling operators of the second kind, these operators express the monomial operator products in terms of the degenerate factorial operators. We derive key structural and combinatorial properties for these operators, including an explicit product factorization, a fundamental recurrence relation, and an operational shifting identity. Furthermore, we establish the orthogonality relations between the degenerate generalized Stirling operators of the first and second kinds, providing a complete combinatorial framework for functional quantum algebras.

2606.09014 2026-06-09 cs.IT math.IT 新提交

Deterministic versus Stochastic Optimization for Joint Path Planning and Dynamic Time Splitting in Multiple-UAV-Cached IoT Networks

多无人机缓存物联网网络中联合路径规划与动态时间分割的确定性优化与随机优化

Trinh Van Chien, Dinh Thanh Tung, Waqas Khalid, Ngo Cong Dung, Banh Thi Quynh Mai, Symeon Chatzinotas

AI总结 针对多无人机缓存物联网网络,提出基于块坐标下降和遗传算法的联合优化方法,实现动态时间分割、轨迹和传输功率的协同优化,吞吐量提升至少31%。

Comments 15 pages, 6 figures, and 7 tables. Accepted by the IEEE IoT Journal

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AI中文摘要

本文研究了无线供电的物联网网络,其中包含多架配备反向散射和缓存技术的无人机,用于中继和传输信号。对于数据通信和能量收集,源节点使用动态时间分割方法向无人机传输信息和功率。无人机利用收集的能量进行被动通信(反向散射)和主动通信(向目的地传输信息)。主要目标是通过联合优化动态时间分割比、轨迹和传输功率,并利用无人机的缓存能力,最大化总吞吐量。由于问题的非凸性,优化具有挑战性。因此,提出了一种使用块坐标下降法的高效交替算法,在固定其他参数值的情况下优化每个变量。通过应用Karush-Kuhn-Tucker条件,推导出最优动态时间分割比的闭式表达式,显著减少了计算时间。其他两个参数的最优值通过块坐标下降法确定。为了全面评估原始问题各种解决方案的有效性,本文引入了一种基于遗传算法的方法。该遗传算法采用单点交叉、值变异和基于适应度值的排名选择。数值结果表明,块坐标下降法和遗传算法相比基准实现了至少31%的吞吐量提升,且计算时间减少。这些结果证明了我们的解决方案在支持缓存的无人机辅助物联网网络中的性能增益和实际可行性。

英文摘要

This paper examines wireless-powered Internet of Things (IoT) networks involving multiple unmanned aerial vehicles (UAVs) equipped with backscatter and caching technologies to relay and transmit signals. For data communication and energy harvesting (EH), the source transmits information and power to UAVs using the dynamic time splitting (DTS) method. UAVs use harvested energy for passive communication (backscatter) and for active communication (transmitting information) to the destination. The primary objective is to maximize the total throughput by jointly optimizing the DTS ratio, trajectory, and transmission power, leveraging the UAVs' caching capability. This optimization problem is challenging due to its non-convexity. Therefore, an efficient alternating algorithm using the block coordinate descent (BCD) method is proposed to optimize each variable given the fixed values of the other parameters. By applying the Karush-Kuhn-Tucker (KKT) conditions, we derive a closed-form expression for the optimal DTS ratio, significantly reducing computation time. The optimal values for the other two parameters are determined using the BCD. In order to thoroughly assess the effectiveness of various solutions for the original problem, this paper introduces an approach leveraging a genetic algorithm (GA). The GA in this context employs a one-point crossover method, value mutation, and rank-based selection based on fitness values. Numerical results show that the BCD and GA achieve at least 31% throughput improvement over the benchmarks, with reduced computational time. These findings demonstrate the performance gain and practical feasibility of our solutions in caching-enabled UAV-aided IoT networks.

2606.09011 2026-06-09 physics.chem-ph 新提交

Static Electric Fields as a Model for Hydrogen-Bond-Induced Dissociation of HF and HCl

静电场作为氢键诱导HF和HCl解离的模型

Megan Grace, Avdhoot Datar

AI总结 通过量子化学计算研究静电场对极性双原子分子HF和HCl电子结构与解离行为的影响,发现电场强度增加导致键软化并最终解离,且HCl所需场强更低,揭示了分子极化率差异与宏观酸强度的关联。

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AI中文摘要

利用量子化学计算研究了静电场对极性双原子分子\ce{HF}和\ce{HCl}的电子结构和解离行为的影响。计算了基态和激发态势能面(PES)作为键距和外电场强度的函数,以考察电场引起的化学键修饰。计算显示,随着电场强度增加,两种分子均出现显著的键软化和逐步失稳。值得注意的是,\ce{HCl}的基态势能面在大约450 MV/cm的场强下完全变为解离型,而\ce{HF}需要接近700 MV/cm的更强电场才能诱导解离。这一差异反映了\ce{HCl}相对于\ce{HF}具有更大的极化率和更弱的键局域性,为两种物种在宏观尺度上酸强度的对比提供了分子层面的视角。场依赖的偶极矩进一步证明了\ce{HCl}对外部扰动更强的电子响应,突出了分子极化率驱动电场诱导键活化的作用。最终,这些结果描绘了卤化氢中电场控制解离的详细图景,支持了周围氢键网络产生的局域电场在调节键活化和凝聚相酸度中起关键作用的观点。

英文摘要

The influence of static electric fields on the electronic structure and dissociation behavior of the polar diatomics \ce{HF} and \ce{HCl} is investigated using quantum chemical calculations. Ground- and excited-state potential energy surfaces (PESs) are computed as a function of bond distance and external electric field strength to examine field-induced modifications of chemical bonding. The calculations reveal pronounced bond softening and progressive destabilization of both molecules with increasing field intensity. Notably, the ground-state PES of \ce{HCl} becomes entirely dissociative at field strengths of approximately 450 MV/cm, whereas \ce{HF} requires a substantially stronger field of nearly 700 MV/cm to induce dissociation. This difference reflects the greater polarizability and weaker bond localization in \ce{HCl} relative to \ce{HF}, providing a molecular-scale perspective on the contrasting macroscale acid strengths of the two species. Field-dependent dipole moments further demonstrate the stronger electronic response of \ce{HCl} to external perturbations, highlighting how molecular polarizability drives electric-field-induced bond activation. Ultimately, these results map out a detailed picture of field-controlled dissociation in hydrogen halides, supporting the view that local electric fields generated by surrounding hydrogen-bonding networks play a key role in modulating bond activation and condensed-phase acidity.

2606.09010 2026-06-09 astro-ph.IM gr-qc 新提交

Statistical Estimation and Correction of Model-Measurement Bias in Time-Dependent Correction Factors of KAGRA

KAGRA时间依赖校正因子中模型-测量偏差的统计估计与修正

Shingo Hido, Takahiro Yamamoto, Dan Chen, Takahiro Sawada, Shinji Miyoki

AI总结 提出统计框架,利用校准线频率处的重复测量-模型比估计并修正模型-测量偏差,通过限制最大似然滚动随机效应模型估计偏差校正因子,应用于KAGRA O4c数据后有效减小响应偏差。

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AI中文摘要

引力波探测器的校准从探测器输出重建应变h(t),重建中的偏差和不确定性直接影响下游分析。在地面干涉仪中,时间依赖校正因子(TDCF)通过校准线估计以跟踪探测器响应的时变,而底层模型参数则通过宽带扫频校准测量(SSCM)定期更新。然而,如果测量传递函数与参考模型之间存在模型-测量偏差,从校准线推断的TDCF会在重建应变中引入系统偏差。我们提出一个统计框架,利用校准线频率处的重复测量-模型比来估计和修正这一偏差。偏差校正因子通过基于限制最大似然(REML)的滚动随机效应模型估计,并纳入TDCF估计中,其不确定性传播到重建响应。将该方法应用于KAGRA O4c数据,我们发现,在代表性示例中,未校正的响应相对于基于SSCM的参考在幅度上偏差高达约7%,相位上偏差高达5度。校正减少了这些偏差,由于包含校正因子不确定性,传播的不确定性略有增加。该框架提供了一种在存在模型-测量偏差时结合宽带参考模型与基于校准线跟踪的实用方法。

英文摘要

Calibration of gravitational-wave detectors reconstructs the strain h(t) from the detector output, and bias and uncertainty in this reconstruction directly affect downstream analyses. In ground-based interferometers, time-dependent correction factors (TDCFs) are estimated from calibration lines to track temporal variations of the detector response, while the underlying model parameters are periodically updated using broadband swept-sine calibration measurements (SSCMs). However, if a model-measurement bias exists between the measured transfer function and the reference model, the TDCFs inferred from calibration lines can introduce a systematic deviation into the reconstructed strain. We propose a statistical framework to estimate and correct this bias using repeated measurement-to-model ratios at the calibration-line frequencies. The bias correction factors are estimated with a rolling random-effects model based on restricted maximum likelihood (REML) and incorporated into the TDCF estimation, with their uncertainty propagated to the reconstructed response. Applying the method to KAGRA O4c data, we find that the uncorrected response shows deviations of up to approximately 7% in magnitude and 5 degrees in phase relative to the SSCM-based reference in representative examples. The correction reduces these deviations, with a modest increase in the propagated uncertainty due to the included correction-factor uncertainty. This framework provides a practical way to combine broadband reference models with calibration-line-based tracking when model-measurement bias is present.

2606.09008 2026-06-09 math.AC 新提交

Construction and finite generation of the strict closure of rings

环的严格闭包的构造与有限生成

Ryotaro Isobe

AI总结 研究一维Cohen-Macaulay半局部环的严格闭包结构,给出其有限生成的特征刻画。

Comments Preprint version, 13 pages

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Journal ref
Journal of Pure and Applied Algebra, 228, Issue 9, 107663, 2024
AI中文摘要

Arf环和严格闭包环的构造已被广泛研究;然而,当R的整闭包不是有限生成R-模时,严格闭包R^*的结构尚无清晰描述。本文研究环的严格闭包的构造与有限生成。我们确定了当R是一维Cohen-Macaulay半局部环且对每个极大理想M有dim R_M=1时其结构。利用这一结果,给出了严格闭包有限生成的特征刻画。

英文摘要

The construction of Arf rings and strictly closed rings has been studied widely; however, there has been no clear description of the structure of the strict closure R^* when the integral closure of R is not a finitely generated R-module. In this paper, we investigate the construction and finite generation of the strict closure of rings. We determine its structure when R is a Cohen-Macaulay semi-local ring of dimension one, with dim R_M=1 for every Maximal ideal M in R. Using this, a characterization of the finite generation of the strict closure is given.

2606.09007 2026-06-09 math.NA cs.NA 新提交

High-Order Regularity and a Fully Discrete Fourier Spectral Method for a Partially Dissipative Viscoelastic Timoshenko System with Memory

具有记忆的部分耗散粘弹性Timoshenko系统的高阶正则性与全离散Fourier谱方法

Zhenyang Zhong, Hui Liang

AI总结 研究一类由Volterra型记忆项仅作用于剪切变量的部分耗散粘弹性Timoshenko系统,建立弱解和强解的适定性,构造Fourier谱全离散格式并证明其能量正性和收敛性。

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AI中文摘要

本文研究了一类具有记忆的部分耗散粘弹性Timoshenko系统,其中耗散由仅作用于剪切变量的Volterra型记忆项引起。在有限时间区间上建立了弱解和强解的适定性,包括存在性、唯一性、稳定性以及与混合边界条件相容的相容性条件下的高阶正则性。对于数值逼近,构造了Fourier谱全离散格式:在空间上,对满足Dirichlet和Neumann边界条件的未知量分别使用正弦和余弦基展开;在时间上,对二阶导数应用中心差分格式,并使用复合梯形公式逼近记忆卷积项。基于离散能量方法,证明了所构造离散能量的正性,并建立了全离散格式的误差估计,时间方向二阶收敛,空间方向对任意q∈N达到q阶收敛。数值实验验证了理论收敛速度,并比较了局部和非局部模型的动态响应,表明记忆项有效捕捉了粘弹性材料中的能量耗散和振动衰减行为。

英文摘要

This paper investigates a class of partially dissipative viscoelastic Timoshenko systems with memory, where dissipation is induced by a Volterra-type memory term acting only on the shear variable. The well-posedness of weak and strong solutions is established on finite time intervals, including existence, uniqueness, stability, and higher-order regularity under compatibility conditions consistent with mixed boundary conditions. For the numerical approximation, a Fourier spectral fully discrete scheme is constructed: sine and cosine basis expansions are used in space for unknowns satisfying Dirichlet and Neumann boundary conditions, respectively; in time, a central difference scheme is applied to the second-order derivatives, and the composite trapezoidal rule is used to approximate the memory convolution term. Based on a discrete energy method, the positivity of the constructed discrete energy is proved, and the error estimate for the fully discrete scheme with second-order convergence in time and \(q\)-th order in space is established for any q \in \mathbb{N}. Numerical experiments are given to verify the theoretical convergence rates and to compare the dynamic responses of the local and nonlocal models, demonstrating that the memory term effectively captures energy dissipation and vibration attenuation behavior in viscoelastic materials.

2606.09003 2026-06-09 q-fin.MF math.OC q-fin.TR 新提交

Proof of Stake economy under centralized exchanges--a mean field model

中心化交易所下的权益证明经济——一个平均场模型

Wenpin Tang

AI总结 本文通过连续时间平均场模型,研究中心化交易所交易活动对PoS区块链的质押行为、代币分配和去中心化的影响,发现中心化交易可能增强质押参与并促进去中心化。

Comments 18 pages

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AI中文摘要

我们考虑中心化交易与去中心化权益证明(PoS)区块链生态系统之间的相互作用。受中心化交易所日益占据主导地位以及加密市场机构化的推动,我们研究了中心化交易所上的交易活动如何影响PoS区块链内的质押行为、代币分配和去中心化。我们构建了一个连续时间平均场模型,其中矿工同时充当PoS协议中的验证者和具有价格影响的中心化市场中的交易者。在适当假设下,我们建立了平均场系统的局部适定性,并推导出均衡交易策略的半显式刻画。数值结果表明,中心化交易活动可能增强质押参与,并通过市场激励促进质押分布的去中心化。我们还研究了交易成本和代币供应机制对均衡质押比率和集中度的影响。这些结果说明了市场微观结构和中心化流动性提供如何对去中心化区块链协议产生显著影响。

英文摘要

We consider the interaction between centralized trading and decentralized Proof of Stake (PoS) blockchain ecosystems. Motivated by the increasing dominance of centralized exchanges and the institutionalization of crypto markets, we study how trading activities on centralized exchanges affect staking behavior, token allocation, and decentralization within a PoS blockchain. We formulate a continuous-time mean field model, where the miners simultaneously act as validators in the PoS protocol and traders in a centralized market with price impact. Under suitable assumptions, we establish the local well-posedness of the mean field system, and derive a semi-explicit characterization of the equilibrium trading strategy. Numerical results suggest that centralized trading activities may enhance staking participation, and promote decentralization of the staking distribution through market incentives. We also study the effects of transaction costs and token supply mechanisms on the equilibrium staking ratio and concentration profile. These results illustrate how market microstructure and centralized liquidity provision can exert significant influence on decentralized blockchain protocols.

2606.09001 2026-06-09 cs.MS physics.comp-ph 新提交

JAX-AMG: A GPU-Accelerated Differentiable Sparse Linear Solver Library for JAX

JAX-AMG:一个用于JAX的GPU加速可微分稀疏线性求解器库

Yi Liu, Xiantao Fan, Jian-Xun Wang

AI总结 提出JAX-AMG,通过封装Nvidia AmgX求解器套件,为JAX生态提供GPU加速的代数多重网格求解器,支持自动微分、分布式多GPU执行,适用于PDE约束优化和反问题。

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AI中文摘要

来自PDE离散化的稀疏线性系统是科学计算的核心,然而现有的JAX生态系统求解器无法同时提供GPU加速的代数多重网格(AMG)、自动微分(AD)和分布式多GPU执行。JAX-AMG通过将Nvidia AmgX求解器套件封装为原生JAX原语来填补这一空白,通过统一接口暴露AMG和Krylov方法及可配置预处理器,兼容JIT编译、通过伴随方法实现反向模式AD、批量求解以及基于MPI的分布式执行。求解器缓存可摊销重复求解的建立成本,使JAX-AMG适用于PDE约束优化和反问题。结果是一个稳健、可扩展的稀疏线性代数层,可无缝集成到可微仿真和科学机器学习流水线中。

英文摘要

Sparse linear systems from PDE discretizations are central to scientific computing, yet no existing JAX-ecosystem solver simultaneously provides GPU-accelerated algebraic multigrid (AMG), automatic differentiation (AD), and distributed multi-GPU execution. JAX-AMG fills this gap by wrapping the Nvidia AmgX solver suite as a native JAX primitive, exposing AMG and Krylov methods with configurable preconditioners through a unified interface compatible with JIT compilation, reverse-mode AD via adjoint methods, batched solves, and MPI-based distributed execution. Solver caching amortizes setup costs across repeated solves, making JAX-AMG practical for PDE-constrained optimization and inverse problems. The result is a robust, scalable sparse linear algebra layer that integrates seamlessly into differentiable simulation and scientific machine learning pipelines.

2606.09000 2026-06-09 quant-ph 新提交

The Transformation-Response Framework: An Operational Reformulation of Quantum Mechanics

变换-响应框架:量子力学的操作重构

Meng-Jun Hu

AI总结 提出变换-响应框架,将量子态定义为系统对局部群变换的响应函数,通过正定性公设导出标准量子力学形式,包括希尔伯特空间、玻恩规则、薛定谔方程和费曼路径积分,具有背景无关和时间中性特点。

Comments Part I of series work. Comments are welcome!

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AI中文摘要

我们提出变换-响应框架,这是量子力学的操作重构。量子态不是希尔伯特空间对象,而是系统对所有物理变换的响应目录:对于来自系统局部群 $G$ 的每个操作 $g$,一个干涉实验给出一个复数值 $χ(g)$。集合 $\{χ(g): g\in G \}$ 是特征函数并定义了态。唯一的公设是 $χ$ 是正定的,编码了没有变换的叠加会产生负概率的要求。从这个单一假设出发,推导出整个标准形式:通过 GNS 构造的希尔伯特空间,通过 Bochner 定理的玻恩规则,来自群自同构的薛定谔方程,特别是作为 Trotter 极限的费曼路径积分。该框架是背景无关和时间中性的:时间是沿着 $G$ 的一个单参数子群的坐标。它还揭示了一个新的物理约束,即乘积序正定性,这可能导致可检验的预测。该框架为量子理论提供了一个统一、经济且可证伪的基础,根植于操作原语。

英文摘要

We present the transformation-response framework, an operational reformulation of quantum mechanics. A quantum state is not a Hilbert space object but the catalog of a system's responses to all physical transformations: for each operation $g$ from the system's local group $G$, an interference experiment gives a complex value $χ(g)$. The collection $\{χ(g): g\in G \}$ is the characteristic function and defines the state. The only postulate is that $χ$ is positive-definite, encoding the requirement that no superposition of transformations yields negative probability. From this single assumption, the entire standard formalism is derived: Hilbert space via GNS construction, Born rule via Bochner theorem, Schrödinger equation from group automorphisms, and especially Feynman path integral as a Trotter limit. The framework is background-independent and time-neutral: time is a coordinate along a one-parameter subgroup of $G$. It also reveals a new physical constraint, product order positivity, which may lead to testable predictions. The framework provides a unified, economical, and falsifiable foundation for quantum theory rooted in operational primitives.

2606.08999 2026-06-09 cond-mat.supr-con cond-mat.mes-hall 新提交

Superconducting diode effect in magnetic superconductors realized by nonreciprocal domain-wall dynamics

磁性超导体中由非互易畴壁动力学实现的超导二极管效应

Dong Hui Han, Suk Bum Chung, Se Kwon Kim

AI总结 本文发现铁磁超导体中磁畴壁的非互易动力学可产生超导二极管效应,通过分析非互易Walker击穿及其与相位滑移的映射,为单一均匀材料中实现纳米级超导二极管提供了新机制。

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AI中文摘要

研究表明,在铁磁超导体中,通过磁畴壁的非互易动力学可以产生超导二极管效应。具体来说,我们展示了在特定外场下,磁畴壁的电流驱动动力学可以表现出非互易的Walker击穿,具有两个不同的方向依赖的临界电流,超过该临界电流后畴壁会持续进动。在铁磁超导体中,畴壁的持续旋转会引起相位滑移,打开耗散通道,从而将非互易Walker击穿映射到超导二极管效应。对于磁畴壁的非互易Walker击穿,我们解析地研究了其对磁场和Gilbert阻尼的依赖性,并通过微磁模拟验证了理论结果。然后,我们通过考虑超导电性的附加效应,将分析扩展到铁磁超导体,并确定了实现预测的超导二极管效应的实验条件标准。我们的工作表明,磁性超导体中的拓扑缺陷(如畴壁)可以在单一均匀材料中作为非线性非互易超导功能的固有纳米级平台,避免了复杂工程异质结构的需要,从而使得超导器件的微型化达到纳米尺度,这是传统约瑟夫森结难以实现的。

英文摘要

A superconducting diode effect is shown to arise in ferromagnetic superconductors through the nonreciprocal dynamics of magnetic domain walls. Specifically, we show that current-driven dynamics of a magnetic domain wall under a certain external field can exhibit a nonreciprocal Walker breakdown, possessing two distinct direction-dependent critical currents beyond which the domain wall precesses continuously. In ferromagnetic superconductors, the constant rotation of a domain wall is shown to give rise to phase slips, opening up dissipation channels, whereby the nonreciprocal Walker breakdown is mapped to the superconducting diode effect. For the nonreciprocal Walker breakdown of a magnetic domain wall, we analytically examine its dependence on the magnetic field and the Gilbert damping and verify the theoretical results with micromagnetic simulations. We then extend the analysis to ferromagnetic superconductors by considering additional effects from the superconductivity and identify criteria for experimental conditions to realize the predicted superconducting diode effect. Our work demonstrates that topological defects, such as domain walls, in magnetic superconductors can serve as an intrinsic nanoscale platform for nonlinear nonreciprocal superconducting functionalities within a single homogeneous material, circumventing the need for complicated engineered heterostructures and thereby enabling the miniaturization of superconducting devices down to the nanometer scale that is challenging to achieve with conventional Josephson junctions.

2606.08996 2026-06-09 astro-ph.EP 新提交

Parameter Effects in Circumplanetary Disk Spectra and Prospects for Spectral Fitting

环行星盘光谱中的参数效应及光谱拟合前景

Xilei Sun, Gabriel-Dominique Marleau, Shang-Fei Liu

AI总结 系统研究环行星盘物理参数对红外光谱的影响,通过参数网格和辐射传输模拟揭示光谱特征与参数简并,为JWST等观测提供理论框架。

Comments 12 pages, 7 figures, resubmitted to A&A

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AI中文摘要

随着詹姆斯·韦伯太空望远镜(JWST)的投入使用,近红外和中红外观测正迅速扩展到环行星盘(CPDs)中小尘埃颗粒辐射主导的波长范围。我们旨在系统研究CPDs的各个物理参数如何塑造其红外光谱,并提高当前和未来观测的光谱拟合鲁棒性和物理解释。基于我们之前的参数化CPD模型,我们采用参数网格方法结合辐射传输模拟,探索可观测光谱对盘结构和尘埃特性的依赖性。我们识别了主要光谱特征和参数简并背后的物理机制,并展示了参数研究中出现的全局趋势。我们还通过拟合代表性观测数据展示了模型的适用性。我们的结果为用JWST及相关设施解释CPDs的近红外和中红外观测提供了结构化的理论框架。

英文摘要

With the commissioning of the James Webb Space Telescope (JWST), near- and mid-infrared observations are rapidly extending into the wavelength regime where emission from small dust grains in circumplanetary disks (CPDs) is expected to dominate. We aim to systematically investigate how individual physical parameters of CPDs shape their infrared spectra and to improve the robustness of spectral fitting and physical interpretation of current and future observations. Building on our previous parametric CPD models, we employ a parameter-grid approach combined with radiative transfer simulations to explore the dependence of observable spectra on disk structure and dust properties. We identify the physical mechanisms responsible for the main spectral features and parameter degeneracies, and present the global trends emerging from the parameter study. We also demonstrate the applicability of the models by fitting representative observational data. Our results provide a structured theoretical framework for interpreting near- and mid-infrared observations of CPDs with JWST and related facilities.

2606.08995 2026-06-09 quant-ph hep-ph hep-th 新提交

Relativistic Effects in Spin Correlations Induced by QED Scattering and Wigner Rotations

QED散射和Wigner旋转引起的自旋关联中的相对论效应

Juan D. Fonseca, B. Hiller, I. G. da Paz, M. Sampaio

AI总结 研究Møller散射及含见证粒子C的过程中,树图级自旋关联的相对论本质,通过非相对论近似揭示偶极相互作用,并分析Wigner旋转对熵和量子相干性的影响。

Comments 13 pages, 12 figures

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AI中文摘要

我们研究了在树图级上,Møller散射以及涉及见证粒子$C$的扩展过程中,两个电子之间产生自旋相互作用的相对论性质。相应的过程,$e^{-}e^{-}\rightarrow e^{-}e^{-}$和$e^{-}e^{-}C\rightarrow e^{-}e^{-}C$,在质心系中进行分析,对于前者,还在洛伦兹助推系中进行分析,其中出现Wigner旋转。发现通过散射振幅的非相对论近似,偶极-偶极和电流-偶极相互作用是这些关联产生的原因。这通过一个电子(对于初始可分离态)和$C$(对于初始制备的三粒子纠缠W态)的von Neumann熵的变化得到证实。在Wigner旋转中,熵在局部幺正变换下的不变性得以保持,但代价是在大快度下密度矩阵中出现量子相干性。因此,评估了两个粒子的最终态,并显示它们通过自旋期望值编码了散射过程的信息。然后利用这个框架评论了非弹性过程$e^{-}e^{+}\rightarrow\mu^{-}\mu^{+}$中的关联,一些研究报告了不同的结果。

英文摘要

We study the relativistic nature of the interactions that, at tree level, generate spin correlations between two electrons in Møller scattering, as well as in an extended process involving a witness particle $C$. The corresponding processes, $e^{-}e^{-}\rightarrow e^{-}e^{-}$ and $e^{-}e^{-}C\rightarrow e^{-}e^{-}C$, are analyzed both in the center-of-mass frame and, for the former process, in a Lorentz-boosted frame where Wigner rotations arise. It is found that, through a nonrelativistic approximation of the scattering amplitudes, dipole-dipole and current-dipole interactions are responsible for the emergence of these correlations. This is evidenced by the variation of the von Neumann entropy of one electron for initially separable states, and of $C$ for an initially prepared three-particle entangled W-state. In Wigner rotations, the invariance of entropy under local unitary transformations is maintained at the expense of the emergence of quantum coherence in the density matrix at large rapidities. As a consequence, the final states of both particles are evaluated and shown to encode information about the scattering process through their spin expectation values. This framework is then used to comment on the correlations in the inelastic process $e^{-}e^{+}\rightarrowμ^{-}μ^{+}$, for which some research has reported differing results.

2606.08991 2026-06-09 math.CO 新提交

Binary necklaces with minimum nontrivial rotational Hamming distance 2

最小非平凡旋转汉明距离为2的二进制项链

Mykola Makhynko

AI总结 本文分类并计数了最小非平凡旋转汉明距离为2的二进制项链,给出了半转、单对和子群模式类的闭式公式以及|D_2(n)|的显式Möbius-欧拉除数求和公式。

Comments 45 pages, 2 tables, no figures; includes supplemental material

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AI中文摘要

我们分类并计数了二进制项链[w],其代表独立的最小非平凡旋转汉明距离minDist(w)等于2,即周期情况后的第一个正层。采用固定的优先级约定,达到距离2的非零移位集合确定了分类:半转(HT)类、单对(SP)类和子群模式(SUB)类,而剩余的多对(MP)类为空。我们给出了HT、SP和SUB计数的闭式公式,以及|D_2(n)|的显式Möbius-欧拉除数求和公式。我们还描述了更大的子群形状分支,该分支包含SUB情况以及由优先级分配给HT和SP的边界情况,通过商背景规范形式及其边界计数。对于奇素数长度p,每个距离-2项链旋转等价于素数循环上的算术区间,且|D_2(p)| = (p^2 - 4p + 7)/2。

英文摘要

We classify and count binary necklaces [w] for which the representative-independent minimum nontrivial rotational Hamming distance minDist(w) equals 2, the first positive layer after the periodic case. With a fixed priority convention, the set of nonzero shifts attaining distance 2 determines a classification into half-turn (HT), single-pair (SP), and subgroup-pattern (SUB) classes, while the residual multi-pair (MP) class is empty. We give closed formulas for the HT, SP, and SUB counts and an explicit Mobius-totient divisor-sum formula for |D_2(n)|. We also describe the larger subgroup-shaped branch, which contains the SUB cases together with boundary cases assigned by priority to HT and SP, by a quotient-background normal form and its boundary counts. For odd prime lengths p, every distance-2 necklace is rotation-equivalent to an arithmetic interval on the prime cycle, and |D_2(p)| = (p^2 - 4p + 7)/2.

2606.08990 2026-06-09 math.RT 新提交

Associated varieties of simple affine vertex algebras at rational levels

有理水平下简单仿射顶点代数的相伴簇

Peng Shan, Wenbin Yan, Qixian Zhao

AI总结 提出关于单李代数(单连通型)在有理水平大于临界水平时简单仿射顶点代数相伴簇的猜想,利用覆盖对偶性映射提供证据。

Comments 17 pages, 3 tables

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AI中文摘要

我们提出了关于简单仿射顶点代数 $L_k(\mathfrak{g})$ 的相伴簇的一个猜想,其中 $\mathfrak{g}$ 是单连通型的单李代数,$k$ 是大于临界水平的任意有理水平。与整数情形相比,关键的新要素是由 Gao-Liu-Lo-Shahidi 引入的覆盖对偶性映射。我们为该猜想提供了证据。

英文摘要

We present a conjecture for associated varieties of simple affine vertex algebras $L_k(\mathfrak{g})$ attached to a simple Lie algebra $\mathfrak{g}$ of simply-laced type and any rational level $k$ greater than the critical level. The key new ingredient compared to the integral case is the covering duality map introduced by Gao-Liu-Lo-Shahidi. We provide evidence for the conjecture.

2606.08989 2026-06-09 math.RT 新提交

From Characters to Matrices: An Elementary Construction of Irreducible Representations of Finite Groups

从特征标到矩阵:有限群不可约表示的一个初等构造

Yu Hsuan Hsieh, Ming-Hsuan Kang

AI总结 提出一个初等算法,通过最大化对角矩阵系数的范数平方,从特征标构造有限群的不可约矩阵表示,并给出数值实现和S4例子。

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AI中文摘要

设 \(G\) 为有限群,\(χ\) 为通常的不可约特征标。我们给出一个初等算法,构造出实现 \(χ\) 的显式矩阵。正则表示提供了典范的 ambient 表示,通常的中心幂等元投影到 \(χ\)-等型分支。主要步骤是在该分支的单位球面上最大化对角矩阵系数的范数平方。最大值是 \(1/χ(1)\),且恰好由那些循环张成不可约子表示(实现 \(χ\))的向量达到。因此,该构造将特征标到矩阵的转化归结为一个具体的优化问题。同样的提取方法适用于任何包含 \(χ\) 的更小的 ambient 表示,例如从子群诱导的表示。我们辅以关于降维、稳健数值实现的讨论,并给出一个显式的 \(S_4\) 例子。

英文摘要

Let \(G\) be a finite group and let \(χ\) be an ordinary irreducible character. We give an elementary algorithm which constructs explicit matrices affording \(χ\). The regular representation provides a canonical ambient representation, and the usual central idempotent projects onto the \(χ\)-isotypic component. The main step is then to maximize the squared norm of a diagonal matrix coefficient on the unit sphere of this component. The maximum is \(1/χ(1)\), and it is attained precisely by vectors whose cyclic span is an irreducible subrepresentation affording \(χ\). Thus the construction reduces the passage from characters to matrices to a concrete optimization problem. The same extraction method applies inside any smaller ambient representation containing \(χ\), such as an induced representation from a subgroup. We complement the theory with a discussion on dimension reduction, robust numerical implementation, and an explicit \(S_4\) example.

2606.08987 2026-06-09 astro-ph.GA 新提交

The origin of WHAM Point Source~46

WHAM点源46的起源

S. R. Kulkarni, Zeren Lin, Charles Beichman, Alex S. Hill, Xihan Deng, Tryston Raecke, Mateusz Matuszewski, Drew M. Miles, Marty Anderson, D. Christopher Martin

AI总结 研究WHAM点源WPS 46的起源,通过Keck Cosmic Web Imager观测发现其发射线比和形态更符合AGN或LI(N)ER电离,而非亚矮星PG 0931+691电离,提出其与中速云相关,可能由激波产生Hα和星云发射。

Comments accepted by PASP

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AI中文摘要

威斯康星Hα测绘仪(WHAM)以约0.1 Rayleigh的灵敏度,但使用1度波束,对整个银河系天空进行了Hα(|v_LSR| ≲ 100 km/s)巡天。Reynolds等人(2005)报告了在空间和速度上从银河背景中突出的“点源”。其中一半源与合理的行星状星云和OB星相关。Reynolds等人(2005)建议四分之一的源为亚矮星。这里,我们研究其中一个源WPS 46,Reynolds等人(2005)建议亚矮星PG 0931+691提供电离源。利用凯克宇宙网成像仪,我们在WPS 46附近发现了许多星云发射线,但在PG 0931+691的角分范围内未能找到Hα发射。线比(BPT图和[S II]/Hα)结合形态更符合AGN或LI(N)ER类电离,而非纯温电离介质或H II区类光致电离。此外,我们提出令人信服的理由论证PG 0931+691不可能是WPS 46的电离源。我们认为WPS 46与一个中速云(IVC)相关,Hα和星云发射可能由激波产生。最后,我们概述了利用SDSS的局部体积测绘仪以及业余天文学家获得的深窄带图像,在亚度尺度上探索和研究电离天空的行动计划,特别是IVC和高速云的研究。

英文摘要

The Wisconsin H$α$ Mapper (WHAM) surveyed the entire Galactic sky in H$α$ ($\vert v_{\rm LSR}\vert \lesssim 100\, {\rm km\,s^{-1}}$) to approximately 0.1\,Rayleigh (R), albeit with a 1-degree beam. %The resulting WHAM Sky Survey, along with large area %imaging in [\ion{S}{2}] and [\ion{N}{2}], laid the foundation for Warm Ionized %Medium (WIM) science. \cite{rcm+05} reported ``point sources" which stood out against the Galactic background in space and velocity. Half of the sources are associated with plausible planetary nebulae and OB stars. Reynolds et al (2005) suggested sub dwarfs for one quarter of the sources. Here, we investigate one such source, WPS\,46, for which Reynolds et al (2005) suggested the sub-dwarf PG\,0931+691 to provide the source of ionization. With the Keck Cosmic Web Imager we found numerous nebular emission lines within the vicinity of WPS\,46, but we failed to find H$α$ emission in the arc-minute vicinity of PG\,0931+691. The line ratios (BPT diagram and [\ion{S}{2}]/H$α$) combined with the morphology are more consistent with AGN or LI(N)ER-like ionization than with pure warm ionized medium or \ion{H}{2} region-like photoionization. Separately, we offer compelling reasons to argue that PG\,0931+691 cannot be the source of ionizing power for WPS\,46. We suggest that WPS\,46 is associated with an intermediate velocity complex (IVC) and that H$α$ and nebula emission may arise as a result of a shock. We conclude by outlining a plan of action of using SDSS's Local Volume Mapper along with deep narrow band imagery obtained by amateur astronomers to explore and study the ionized sky on sub-degree scales, in general, and specifically studies of IVC and high-velocity complexes.

2606.08986 2026-06-09 physics.ed-ph 新提交

Discovering Misconceptions and Misunderstandings From Administrations of Research-Designed Multiple Choice Instruments

从研究设计的多项选择测试中发现误解与错误理解

Martin Segado, Aaron Adair, John Stewart, David Pritchard

AI总结 利用多维项目反应模型分析约34,000份力概念量表数据,识别出22个稳健维度,按历史时期分类误解,并提出计算学生和班级误解分数的方法,揭示教学后误解的修复模式。

Comments An earlier version of this paper appeared in Chapter 3 of the first author's PhD thesis, "Intuitive but Wrong: Uncovering Student Misconceptions About Force and Motion With Bayesian Item-Response Methods" (Segado, 2025; https://hdl.handle.net/1721.1/165584)

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AI中文摘要

误解是“替代假设”,根据关于世界如何运作的既定理论是不正确的。学生通常对其持有信心,它们相对不依赖于情境,看起来像常识观点,并且以难以通过传统教学纠正而著称。为了发现牛顿力学中的误解,我们使用灵活的多维项目反应模型分析了约34,000份开创性的力概念量表的管理数据。与大多数早期工作不同,我们允许每个问题中的答案选择在学生知识的多维空间中具有不同方向,这对于干扰项通常编码不同误解的概念清单至关重要。我们发现了22个稳健的、部分重叠的维度,其干扰项共享一个连贯的主题,可识别为误解或错误理解。受许多镜像先前接受的力学理论的启发,我们按历史时期大致分类:古代(婴儿学习但由希腊人编纂)、中世纪(亚里士多德思想的反应和扩展)和后牛顿(包括已知的现代误解以及两个看似新颖的误解)。我们还提出了一种计算学生和班级“误解分数”的简单方法。检查教学前后的这些分数揭示了样本中令人惊讶的多样化修复模式:一些误解在教学中基本保持不变,而另一些则在低于或高于平均水平的学生中得到更好的修复。总的来说,我们发现许多误解对于平均或较低能力的学生来说修复效果不佳。我们希望我们的工作能够作为开发、评估和改进这些干预措施的指南,同时为物理教师提供有价值的班级形成性评估工具。

英文摘要

Misconceptions are "alternate hypotheses" that are incorrect according to established theories of how the world works. Often held with confidence by students, they are relatively context-insensitive, can seem like common-sense views, and are noted for being resistant to remediation using traditional instruction. To find misconceptions in Newtonian mechanics, we analyze ~34,000 administrations of the pioneering Force Concept Inventory using a flexible multidimensional item-response model for multiple-choice data. In contrast to most earlier work, we allow answer choices within each question to have different directions in the multidimensional space of student knowledge, essential for concept inventories in which distractors often codify distinct misconceptions. We uncover 22 robust, partly-overlapping dimensions whose distractors share a coherent theme identifiable with a misconception or misunderstanding. Motivated by the realization that many mirror previously-accepted theories of mechanics, we broadly sort these by historical era: Ancient (learned by infants but codified by Greeks), Medieval (reactions and extensions of Aristotelian ideas), and Post-Newtonian (including known modern misconceptions as well as two which appear novel). We also present a simple approach for computing "misconception scores" for students and classes. Examining these scores before and after instruction reveals surprisingly varied patterns of remediation in our sample: some misconceptions persist largely unchanged by instruction, while others are better remediated in below- or above-average students. In general, we find that many misconceptions are poorly remediated for students of average or lower ability. We hope our work will serve as a guide for developing, evaluating, and improving interventions for these while providing physics instructors with a valuable tool for class-level formative assessment.

2606.08984 2026-06-09 math.OC cs.SY eess.SY 新提交

Not All Warm Starts Help: Benchmarking Primal-Dual Initializations for ACOPF Algorithms

并非所有热启动都有帮助:ACOPF 算法原始-对偶初始化的基准测试

Babak Taheri, Daniel K. Molzahn

AI总结 本文系统评估了AC最优潮流(ACOPF)问题中不同原始-对偶初始化策略对内点法求解性能的影响,发现大部分部分重启会降低求解速度或收敛可靠性,仅完整重启稳定有效,并提出了学习型热启动的目标优先级。

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AI中文摘要

热启动被广泛用于加速交流最优潮流(ACOPF)求解,但不同初始化策略的影响,尤其是对于主导大规模ACOPF算法的原始-对偶内点法,尚未得到系统研究。本文在19个PGLib-OPF实例(5至30000母线)上,使用内点求解器IPOPT对ACOPF的初始化策略进行基准测试,测试了原始块$\{P_g, Q_g, V_m, V_a\}$的所有15个非空子集在oracle条件下的情况,以及实际设置中的三种直流(DC)种子组合。实验表明,大多数部分原始-对偶重启会增加求解时间或降低收敛可靠性。在oracle原始-对偶(O-PD)配置中,只有完整重启能在每个基线收敛案例上可靠收敛,达到47.6%的中位求解时间加速。14个部分O-PD组合中有12个的中位加速比为负,且多个在较大网络上反复失败。将对偶分解为约束乘子和边界乘子表明,决定鲁棒性的是“覆盖范围”而非对偶本身的存在:完整的边界乘子向量达到90.7%的收敛率和+26.8%的中位加速比,而块匹配覆盖(某些边界上的oracle乘子,其余使用默认值)则降至70.4%和-31.1%。实际DC种子有时有助于AC求解,但一旦将DCOPF预求解成本纳入端到端比较,该收益不再具有统计显著性(p = 0.4171)。对于学习型热启动方法,结果支持以下目标优先级:首先预测完整原始向量;如果只能部分覆盖,优先考虑电压变量;除非原始估计几乎完整,否则避免部分或不一致的对偶预测。

英文摘要

Warm starts are widely used to accelerate AC optimal power flow (ACOPF) solves, but the impact of different initialization strategies has received limited systematic study, particularly for the primal-dual interior-point methods that dominate large-scale ACOPF algorithms. This paper benchmarks initialization strategies for ACOPF solved with the interior-point solver IPOPT on 19 PGLib-OPF instances (5 to 30,000 buses), testing all 15 non-empty subsets of the primal blocks $\{P_g, Q_g, V_m, V_a\}$ under oracle conditions and three DC-seeded combinations in a practical setting. The experiments show that most partial primal-plus-dual restarts increase solve time or reduce convergence reliability. Among the oracle primal-plus-dual (O-PD) configurations, only the complete restart reliably converges on every baseline-convergent case, reaching a $47.6\%$ median solve-time speedup. Twelve of the 14 partial O-PD combinations have negative median speedups, and several fail repeatedly on larger networks. Decomposing the dual into constraint and bound multipliers shows that \emph{coverage}, not the presence of duals per se, governs robustness: the full bound-multiplier vector reaches 90.7\% convergence and a $+26.8$\% median speedup, whereas block-matched coverage (oracle multipliers on some bounds, defaults on the rest) drops to 70.4\% and $-31.1$\%. Practical DC seeding sometimes helps the AC solve, but the benefit is no longer statistically significant once the DCOPF presolve cost is included in the end-to-end comparison ($p = 0.4171$). For learned warm-start methods, the results support the following target ordering: predict the full primal vector first; if only partial coverage is possible, prioritize voltage variables; and avoid partial or inconsistent dual predictions unless the primal estimate is nearly complete.

2606.08983 2026-06-09 nlin.CG cs.FL 新提交

Dynamics in a Low-Rank Separable Field Cellular Automaton

低秩可分离场元胞自动机中的动力学

Xiaorui Shi, Mengsha Huang

AI总结 提出可分离场元胞自动机(SFCA),通过秩一行列场替代局部邻域计数,发现存活与出生区间几何关系决定四种动力学类别,长瞬态区域位于部分重叠与无重叠边界,由两个周期吸引子族的延迟选择形成。

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AI中文摘要

元胞自动机中复杂的集体动力学通常与局部邻域组合学相关,但尚不清楚长寿命动力学组织是否需要这种显式的局部相互作用结构。这里,我们引入可分离场元胞自动机(SFCA),一种归一化场元胞自动机,其中局部邻居计数被秩一型行列场替代。每个元胞根据归一化场更新,存活和出生由两个阈值区间控制。对区间宽度和位置进行系统扫描揭示了四种结果类别:灭绝、不动点、周期和长瞬态。结果相图由存活和出生区间的相对几何结构组织:当出生区间包含在存活区间内时,不动点占主导,而长瞬态集中在部分重叠与无重叠边界附近。沿此过渡的精细扫描显示,长瞬态区域形成一条狭窄但持久的脊,分隔两个性质不同的周期主导区域。一侧产生密集、高变化率的周期,近似全局周期-2交替,而另一侧产生稀疏、低变化率的条纹状周期。损伤扩散进一步支持了盆地竞争解释,其中长瞬态脊反映了两个周期吸引子族之间的延迟选择,而非随机不收敛,而有限尺寸分析表明,长瞬态脊在测试网格尺寸上保持稳健。这些结果表明,在压缩的可分离场耦合下可以出现结构化的长瞬态动力学,暗示非平凡的集体组织不一定需要完整的局部邻域组合学。

英文摘要

Complex collective dynamics in cellular automata are usually associated with local-neighborhood combinatorics, yet it remains unclear whether long-lived dynamical organization requires such explicit local interaction structure. Here, we introduce a Separable-Field Cellular Automaton (SFCA), a normalized-field cellular automaton in which local neighbor counting is replaced by a rank-one-like row-column field. Each cell is updated according to a normalized field, with survival and birth governed by two threshold intervals. Systematic scans over interval widths and positions revealed four outcome classes: extinction, fixed points, cycles, and long transients. The outcome phase diagram was organized by the relative geometry of the survival and birth intervals: fixed points dominated when born interval was contained in survival interval, whereas long transients concentrated near the boundary between partial overlap and no overlap. A fine scan along this transition showed that the long-transient region forms a narrow but persistent ridge separating two qualitatively distinct cycle-dominated regimes. One side produced dense, high-change-rate cycles approximating global period-2 alternation, whereas the other produced sparse, low-change-rate, stripe-like cycles. Damage-spreading further supported a basin-competition interpretation, in which the long-transient ridge reflects delayed selection between two cyclic attractor families rather than random nonconvergence, while finite-size analysis shows that the long-transient ridge remains robust across tested grid sizes. These results show that structured long-transient dynamics can arise under compressed separable field coupling, suggesting that nontrivial collective organization does not necessarily require full local-neighborhood combinatorics.

2606.08981 2026-06-09 stat.ME 新提交

Divide-and-shrink: An efficient and heterogeneity-agnostic approach for transfer estimation using summary statistics

Divide-and-shrink: 一种利用汇总统计量进行迁移估计的高效且异质性无关的方法

Ruoyu Wang, Xihong Lin

AI总结 提出Divide-and-shrink方法,利用目标与外部总体的汇总统计量闭式估计目标参数,保证任意异质性下均优于仅用目标数据的估计,且无需模型或调参。

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AI中文摘要

跨数据源的知识转移通过利用来自不同来源的数据日益增长的可用性,有望改善目标总体参数的估计。然而,知识转移的有效性常常受到数据源之间复杂且普遍的异质性以及无法访问个体层面数据的挑战。本文提出了divide-and-shrink (dShrink) 方法,这是一种迁移估计方法,它利用来自目标总体和一些外部源总体的汇总统计量以闭式形式估计目标总体参数,同时考虑总体异质性。dShrink估计器在任意总体异质性下,保证在期望二次误差方面优于仅基于目标总体的估计器。当目标总体与源总体相似或潜在真实参数值接近零时,增益可能很大。值得注意的是,dShrink是无模型的,不需要用户指定的调优参数,对数据源之间的各种异质性具有鲁棒性,并适用于广泛的参数估计问题。即使外部汇总统计量的协方差矩阵不可访问,dShrink仍然有效,并提供了整合来自多个源总体的辅助信息和汇总统计量的灵活性。模拟和真实数据分析展示了dShrink估计器的优越性能及其作为迁移估计的稳健工具的潜力。

英文摘要

Knowledge transfer across data sources holds great promise for improving the estimation of target population parameters by leveraging the growing availability of data from different sources. However, the effectiveness of knowledge transfer is often challenged by the complex and pervasive heterogeneity between data sources and the lack of access to individual-level data. This paper proposes the divide-and-shrink (dShrink) method, a transfer estimation method that estimates target population parameters in a closed form using summary statistics from a target population and some external source populations while accounting for population heterogeneity. The dShrink estimator is guaranteed to outperform the estimator based solely on the target population in terms of expected quadratic error under arbitrary population heterogeneity. The gain can be substantial when the target and source populations are similar, or the underlying true parameter values are near zero. Notably, dShrink is model-free, requires no user-specified tuning parameters, robust to various types of heterogeneity between data sources, and applies to a broad range of parameter estimation problems. dShrink remains effective even when the covariance matrix is not accessible for the external summary statistics and offers flexibility in incorporating side information and summary statistics from multiple source populations. Simulations and real data analyses demonstrate the superior performance of the dShrink estimator and its potential as a robust tool for transfer estimation.

2606.08979 2026-06-09 cs.IR 新提交

EviProp: Seeded Relevance Diffusion on Chunk-Page Graphs for Long Multimodal Document Retrieval

EviProp: 基于种子相关性扩散的块-页图用于长多模态文档检索

Hongwei Zhang, Xiaoman Wang, Zehui Ling, Ruicheng Zhu, Yue Zhang, Pinlong Cai, Fuke Shen, Botian Shi, Tongquan Wei, Guohang Yan

AI总结 提出EviProp方法,通过构建多模态块-页图并利用个性化PageRank扩散相关性,解决长文档中证据页检索的独立匹配局限,提升检索准确率。

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AI中文摘要

从视觉丰富的长文档中检索证据页是文档问答中的一个关键挑战。现有的页面级视觉检索器在独立匹配范式下运行:每个页面基于查询-页面相似性单独评分。这种范式可能会低估那些信号位于细粒度块中或依赖于文档内部关联的证据页。我们提出EviProp,一种通过种子相关性扩散来恢复此类页面的检索方法。EviProp将每个文档建模为一个具有层次、顺序和相似性链接的多模态块-页图。给定查询,它结合密集的视觉页面先验和稀疏的块种子,然后运行个性化PageRank在图上扩散相关性。在MMLongBench-Doc和LongDocURL上的实验表明,与独立的视觉检索和文本-视觉融合基线相比,在证据页检索上取得了持续改进。下游QA结果进一步表明,改进的检索转化为更好的答案准确性,且在线检索开销可忽略不计。我们的代码发布在https://github.com/Flyecnu/EviProp。

英文摘要

Retrieving evidence pages from visually rich long documents is a key challenge in document question answering. Existing page-level visual retrievers operate under an independent matching paradigm: each page is scored in isolation based on query-page similarity. This paradigm can under-rank evidence pages whose signals are localized in fine-grained chunks or depend on document-internal associations. We propose EviProp, a retrieval method that recovers such pages via seeded relevance diffusion. EviProp models each document as a multimodal Chunk-Page graph with hierarchical, sequential, and similarity links. Given a query, it combines dense visual page priors with sparse chunk seeds, then runs Personalized PageRank to diffuse relevance over the graph. Experiments on MMLongBench-Doc and LongDocURL show consistent gains in evidence-page retrieval over independent visual retrieval and text-visual fusion baselines. Downstream QA results further show that improved retrieval translates into better answer accuracy, with negligible online retrieval overhead. Our code is released at https://github.com/Flyecnu/EviProp.

2606.08975 2026-06-09 stat.OT 新提交

Strong Likelihood Principle: Strengthening a Principle or Misunderstanding the Likelihood Function

强似然原理:强化原理还是误解似然函数

Paul William Vos

AI总结 本文重新审视强似然原理,指出其源于对似然函数定义域的混淆,通过二项分布与负二项分布族的比较及Fisher信息度量几何结构,论证强似然原理退化为弱似然原理。

Comments 15 pages, 3 figures

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AI中文摘要

强似然原理(SLP)通常由Birnbaum的论证从充分性原理和条件性原理推导而来,大量文献对此推导的合理性存在争议。我们采取不同的方法。我们仔细解读SLP的术语,认为该原理的通常表述反映了对似然函数定义域的混淆。似然自然地被定义为一个分布族$M$上的函数,而非参数空间上的函数,一旦如此定义,SLP便退化为其弱版本,即弱似然原理。通过类比货币价值,具体地通过比较共享参数的二项分布族和负二项分布族来阐明这一诊断,并通过Fisher信息度量与$M$的几何结构相联系。相同的标准化来自关于跨总体比较测量的统计论证和关于流形距离的几何论证;这种收敛为弱似然原理提供了正面内容。

英文摘要

The strong likelihood principle (SLP) is conventionally derived from the sufficiency principle and a conditionality principle in an argument due to Birnbaum, and much of the literature contests whether the derivation is sound. We take a different approach. We ask what the SLP says when its terms are read carefully, and argue that the principle as ordinarily stated reflects a confusion about the domain of the likelihood function. The likelihood is naturally defined as a function on a family of distributions $M$, not on a parameter space, and once it is so defined the SLP collapses into its weak counterpart, the weak likelihood principle. The diagnosis is illustrated by analogy with monetary value, developed concretely through a comparison of the binomial and negative binomial families that share a parameter, and connected to the geometric structure of $M$ through the Fisher information metric. The same standardization emerges from a statistical argument about comparing measurements across populations and from a geometric argument about manifold distance; this convergence supplies the positive content of the weak likelihood principle.

2606.08971 2026-06-09 astro-ph.GA astro-ph.EP 新提交

The complex kinematics of the young stars orbiting the supermassive black hole in the Galactic center can be explained by the presence of an intermediate mass companion of Sgr A$^\star$

银河系中心超大质量黑洞周围年轻恒星的复杂运动学可通过Sgr A$^\star$存在中等质量伴星来解释

Xiaochen Zheng, Long Wang, Douglas N. C. Lin, Andreas Burkert, Shude Mao

AI总结 本文提出统一模型,通过中等质量伴星的长期扰动和耗散气体盘中恒星的共振弛豫,同时解释了银河系中心Sgr A$^\star$周围S星、CWS和ODS三类年轻恒星的共存及其轨道分布特征。

Comments 33 pages, 15 figures, accepted for publication in the Astrophysical Journal

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AI中文摘要

银河系中心Sgr A$^\star$超大质量黑洞(SMBH)周围亚秒差距区域内包含一个内星团,由轨道随机取向的偏心S星组成;一个中间盘,包含顺时针旋转的恒星(CWSs);以及一个周围盘外恒星(ODSs)群体。尽管运动学性质多样,这三类恒星似乎都是大质量(WR/O/B型)且寿命有限($τ_\star \sim 6-15$ Myr)。已有几种场景被提出,分别解释S星、CWSs、ODSs以及银河系超高速星的起源和动力学演化,包括SMBH与一个或多个气体云近距离相遇引发的恒星形成,以及Sgr A$^\star$可能的中等质量伴星(IMC,可能是一个中等质量黑洞)的脉冲式近距离散射。然而,它们的共存以及最近发现的S星偏心距-近心距分布中的回避区起源仍是个谜。在此,我们构建了一个统一模型,综合考虑这些恒星之间的相互作用、它们共同的诞生盘以及一个独立的IMC。我们证明,在IMC的长期扰动和这些恒星在耗散气体盘环境中的共振弛豫的共同作用下,它们当前迥异的轨道只有在数百万年的年龄内才能同时实现。

英文摘要

The sub-parsec proximity around the Sgr A$^\star$ supermassive black hole (SMBH) in the center of the Milky Way contains an inner cluster of eccentric S-stars with randomly oriented orbits, a midway-disk of clockwise-rotating stars (CWSs), and a surrounding population of off-the-disk stars (ODSs). Despite their diverse kinematic properties, all three-populations appear to be massive (WR/O/B types) and have similarly limited life span $τ_\star \sim 6-15$ Myr. Several scenarios, including star formation induced by SMBH's close encounters with one or more gas clouds as well as impulsive close scattering by a putative intermediate-mass companion (IMC) of Sgr A$^\star$ possible an intermediate-mass black hole (IMBH), have been proposed to explain piecemeal for the origin and dynamical evolution of S-stars, CWSs, ODSs, as well as hyper-velocity stars in the Galaxy. But, their coexistence and the origin of a recently discovered zone of avoidance in S-stars' eccentricity-peri-centric-distance distribution remain enigmatic. Here, we construct a unified model to comprehensively take into account these stars' interaction with each other, their single natal disk, and an independent IMC. We show their disparate present-day orbits would only be concurrently attainable, within their multi-Myr age, under the combined influence of IMC's secular perturbation and these stars' resonant relaxation in a depleting gaseous-disk environment.

2606.08968 2026-06-09 physics.ins-det hep-ex 新提交

Study on the shielding efficiency of water, HDPE, and boron-loaded HDPE for neutron background of plastic scintillator neutrino detector

水、HDPE 和硼掺杂 HDPE 对塑料闪烁体中微子探测器中子本底的屏蔽效率研究

D. X. Lu, Y. H. Liu, X. S. Zhang, F. P. An, G. Luo, W. Wang

AI总结 针对浅层反应堆反中微子实验的宇宙线中子本底,测试了水、HDPE 和 40% 硼掺杂 HDPE 对快中子和热中子的屏蔽性能,30 cm 厚硼掺杂 HDPE 对两种中子的屏蔽效率均超过 95%。

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AI中文摘要

地表反应堆反中微子实验通常有大量的宇宙线诱发中子本底,尤其是在浅覆盖层下。反中微子反应堆监测阵列(ALARM)是一个基于塑料闪烁体的实验,用于反应堆功率监测。它将被部署在台山核电站距堆芯约 44 米处。放置在地下 9.6 米深处,宇宙线诱发的快中子构成了显著的本底,因此有效的屏蔽系统对实验至关重要。针对 ALARM 的屏蔽设计,我们测试了三种材料(水、HDPE 和 40% 硼掺杂 HDPE)对快中子和热中子的屏蔽性能。首先使用由 EJ426 闪烁体组成的热中子探测器,测量了这些材料在不同厚度下对 Am-Be 源中子的屏蔽效率。30 cm 厚的硼掺杂 HDPE 对快中子和热中子的屏蔽效率均超过 95%。EJ426 装置的蒙特卡洛模拟结果与实验数据一致。还给出了完整 ALARM 屏蔽组件的屏蔽性能模拟结果。

英文摘要

Surface-level reactor antineutrino experiments usually have substantial cosmic ray induced neutron backgrounds, particularly with shallow overburden. The Array of Lattice for Anti-neutrino Reactor Monitoring (ALARM) is a plastic scintillator based experiment designed for reactor power monitoring. It will be deployed about 44 m from the core of a reactor at the Taishan Nuclear Power Plant. Placed at a depth of 9.6 meters below the surface, cosmic ray induced fast neutrons constitute a significant background, making an effective neutron shielding system essential for the experiment. For the shielding design of ALARM, we tested the shielding performance of three materials water, HDPE, and 40\% boron-doped HDPE (BHDPE) against both fast and thermal neutrons. A thermal neutron detector composed of an EJ426 scintillator setup was first used to measure the shielding efficiency of these materials at various thicknesses using neutrons from an Am-Be source. A 30-cm thickness of BHDPE achieved a shielding efficiency exceeding 95\% for both fast and thermal neutrons. Monte Carlo simulations of the EJ426 setup yielded results consistent with the experimental data. Simulation results for the shielding performance of the full ALARM shielding assembly are also presented.

2606.08967 2026-06-09 astro-ph.HE astro-ph.CO astro-ph.GA 新提交

Precise scaling relations for self-interacting bosonic dark matter stars

自相互作用玻色子暗物质星的精确标度关系

Zhaorui Zhang, Xudong Wang, Bin Qi

AI总结 通过复标量场理论推导暗物质状态方程,系统研究玻色子暗物质星的结构,给出质量、半径、中心密度及粒子性质的精确标度关系,并首次提出临界半径和中心密度的标度公式。

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AI中文摘要

系统研究了玻色子暗物质星的结构性质,给出了质量、半径、中心密度以及暗物质粒子性质的精确标度关系。暗物质状态方程源自具有四次自相互作用势 $V(ϕ) = \fracλ{4} |ϕ|^4$ 的复标量场理论,考虑了玻色子质量 $m_ϕ$ 从 $10^{-9}$ 到 $10^{3}$ GeV 以及自耦合常数 $λ$ 从 $0.01π$ 到 $100π$ 的范围。得到了玻色子暗物质星最大质量、相应临界半径和临界中心密度的标度关系:\[ M_{\text{max}} = 0.1 \frac{\sqrtλ}{m_ϕ^2} M_\odot, \qquad R(M_{\text{max}}) = 0.9 \frac{\sqrtλ}{m_ϕ^2} \ \text{km}, \qquad \varepsilon_{\text{max}} = 2.1 \times 10^5 \frac{m_ϕ^4}λ \ \mathrm{MeV/fm^3}, \] 其中 $m_ϕ$ 以 GeV 为单位,$R(M_{\text{max}})$ 和 $\varepsilon_{\text{max}}$ 的关系是首次提出。拟合相对误差小于 $4\%$。基于这些标度关系,我们进一步提供了稳定分支的全局解析拟合。质量与中心密度以及半径与中心密度之间的关系可以用统一形式的函数描述:\[ \tilde{Y} = \frac{A}{\left[1 + \left(5\tilde{\varepsilon}\right)^h\right]^s}, \] 其中对于 $Y=M$,$\tilde{M} \equiv M/M_{\text{max}}$,$A=1$,$h=-2$,$s=0.42$;对于 $Y=R$,$\tilde{R} \equiv R/R(M_{\text{max}})$,$A=1.634$,$h=1$,$s=0.28$;$\tilde{\varepsilon} \equiv \varepsilon_0/\varepsilon_{\text{max}}$。拟合相对误差小于 $0.1\%$。此外,我们发现了玻色子暗物质星的简单二次多项式质量-半径关系。

英文摘要

The structural properties of bosonic dark matter stars are systematically investigated, presenting precise scaling relations for the mass, radius, central density, and the properties of dark matter particles. The dark matter equation of state is derived from a complex scalar field theory with a quartic self-interaction potential $V(ϕ) = \fracλ{4} |ϕ|^4$, considering boson masses $m_ϕ$ ranging from $10^{-9}$ to $10^{3}$ GeV and self-coupling constants $λ$ ranging from $0.01π$ to $100π$. The scaling relation for the maximum mass of bosonic dark matter stars, the corresponding critical radius and critical central density are obtained as \[ M_{\text{max}} = 0.1 \frac{\sqrtλ}{m_ϕ^2} M_\odot, \qquad R(M_{\text{max}}) = 0.9 \frac{\sqrtλ}{m_ϕ^2} \ \text{km}, \qquad \varepsilon_{\text{max}} = 2.1 \times 10^5 \frac{m_ϕ^4}λ \ \mathrm{MeV/fm^3}, \] where $m_ϕ$ is in GeV, the relations for $R(M_{\text{max}})$ and $\varepsilon_{\text{max}}$ are first put forward. The fitting relative error is less than $4\%$. Based on these scaling relations, we further provide global analytical fits for the stable branch. The relationships between mass and central density as well as radius and central density can be described by a unified function of the form: \[ \tilde{Y} = \frac{A}{\left[1 + \left(5\tilde{\varepsilon}\right)^h\right]^s}, \] where for $Y=M$, $\tilde{M} \equiv M/M_{\text{max}}$, $A=1$, $h=-2$, $s=0.42$; for $Y=R$, $\tilde{R} \equiv R/R(M_{\text{max}})$, $A=1.634$, $h=1$, $s=0.28$; and $\tilde{\varepsilon} \equiv \varepsilon_0/\varepsilon_{\text{max}}$. The fitting relative error is less than $0.1\%$. Furthermore, we find a simple quadratic polynomial mass-radius relation for bosonic dark matter stars.

2606.08966 2026-06-09 stat.ME 新提交

Class Imbalance Corrections Failed to Enhance Discrimination, Model Calibration, and Prediction Stability: An Empirical Simulation Study Based on Clinical Dataset

类别不平衡校正未能提升判别能力、模型校准和预测稳定性:基于临床数据集的实证模拟研究

Wachiranun Sirikul, Natthanaphop Isaradech, Wuttipat Kiratipaisarl, Pakpoom Wongyikul, Noraworn Jirattikanwong, Phichayut Phinyo

AI总结 本研究通过模拟临床预测模型开发,发现类别不平衡校正(如重采样和算法级调整)不能改善模型判别能力,反而导致校准不良和预测不稳定,建议不应常规进行不平衡校正。

Comments 47 pages

详情
AI中文摘要

类别不平衡在开发临床预测模型(CPMs)时很常见,通常被认为会导致预测性能不佳。已有多种方法被提出来在CPM开发过程中校正数据不平衡。然而,校正类别不平衡是否改善或损害CPM性能仍不清楚。本研究调查了不平衡校正如何影响分类性能和预测稳定性。我们使用惩罚逻辑回归模拟了CPM的开发与内部验证,采用了不同的不平衡校正策略,包括算法级重平衡、数据级过采样重平衡以及过采样与欠采样的组合。模拟数据集来自GUSTO-I试验,包含40,830名患者和2,851个事件。所有不平衡校正策略在样本量从500到40,830的场景下进行了评估。使用200次bootstrap重抽样评估模型性能和预测稳定性,包括判别能力、校准、校准稳定性、平均绝对预测误差(MAPE)和分类不稳定性指数(CII)。类别不平衡校正并未显著改善模型判别能力。与未校正的模型相比,数据级和算法级校正均导致校准不良、风险高估以及预测不稳定性增加,如预测稳定性、MAPE和CII图所示。这些发现表明,类别不平衡校正不一定能改善CPM性能,反而可能损害校准和预测稳定性。类别不平衡不应被视为需要自动校正的病理状态。在临床预测建模中,默认进行常规不平衡校正通常不可取。

英文摘要

Class imbalance is common when developing clinical prediction models (CPMs) and is often assumed to lead to poor predictive performance. Several methods have been proposed to correct data imbalance during CPM development. However, it remains unclear whether correcting class imbalance improves or harms CPM performance. This study investigated how imbalance correction affects classification performance and prediction stability. We simulated the development and internal validation of CPMs using penalised logistic regression under different imbalance-correction strategies, including algorithm-level rebalancing, data-level rebalancing by oversampling, and combined over- and under-sampling. The simulation dataset was derived from the GUSTO-I trial, which included 40,830 patients and 2,851 events. All imbalance-correction strategies were evaluated across sample-size scenarios ranging from 500 to 40,830. Model performance and prediction stability were assessed using 200 bootstrap resamples, including discrimination, calibration, calibration stability, mean absolute prediction error (MAPE), and classification instability index (CII). Class imbalance correction did not meaningfully improve model discrimination. Both data-level and algorithm-level correction led to miscalibration, risk overestimation, and increased prediction instability, as shown by prediction stability, MAPE, and CII plots, compared with models developed without correction. These findings suggest that class imbalance correction does not necessarily improve CPM performance and may compromise calibration and prediction stability. Class imbalance should not be treated as a pathology that automatically requires correction. In clinical prediction modelling, routine imbalance correction by default is generally not advisable.