arXiv subjects

Zhihua Xiong

Publications and source records attributed to Zhihua Xiong.

6 recordsLinked to original sources

arXiv2026

High performance construction materials fracture and high cycle fatigue assessment based on accelerated PF-CZM

Given the widespread application of high-performance materials in cyclic loaded infrastructure, a thorough understanding of the fracture and high-cycle fatigue behavior of high-performance materials is of critical importance. However, these behaviors predominantly rely on experimental methods, which are often costly, time-consuming and limited in generalizability. To address these issues, this paper proposes the constitution and high-cycle fatigue of Ultra-High Performance Concrete (UHPC) and High Strength Steel (HSS) within the Phase-Field Cohesive Zone Model (PF-CZM) framework. A generic stress-based failure criterion for UHPC is derived from the biaxial tensile test results to calculate crack driving force. Furthermore, a fatigue degradation function and an acceleration algorithm are integrated into the PF-CZM framework to enable efficient high-cycle fatigue simulations. In the acceleration algorithm, the envelope load is used to approximate the real cyclic load to avoid the simulation of each cycle, and the three-stage fatigue process is simulated through adjusting the cyclic increment adaptively. The proposed model successfully captures mixed-mode fracture and high-cycle fatigue behavior of UHPC and HSS, with validation provided through relevant experimental comparisons.

physics.app-ph↗

arXiv2025

Observing the exponential growth of the eigenmodes in the absence of coalescence for a non-Hermitian circuit with an unavoidable inductor dissipation

We investigate, both experimentally and theoretically, the eigenmodes of an electronic circuit in which gain and loss $RLC$ resonators are coupled through a capacitor. Due to the unavoidable magnetic loss in the inductors, we find that the eigenmode coalescence no longer emerges in contrast to the conventional non-Hermitian systems with the spontaneous $\cal{PT}$-symmetry breaking. In particular, we find a transition from the exponential decay to exponential growth in the amplitude of the periodic voltage oscillations of the resonators. The transition occurs near the exceptional points of the non-Hermitian circuit without considering the dissipations in inductors. We introduce a small resistor of three orders of magnitude smaller than that of the $RLC$ resonators to mimic the energy dissipation in inductors and numerically solve the equivalent non-Hermitian Schr{\" o}dinger equation. The numerical results can well reproduce experimental observations. Our above findings unambiguously indicate that the exponential growth behavior beyond the exceptional points is robust against some unavoidable dissipative perturbations.

quant-ph↗

arXiv2025

Experimental and Theoretical Study of Thin-covered Composite Dowels considering Multiple Load Conditions

With the widespread application of composite structures in the fields of building and bridge constructions, thin-covered composite dowels are increasingly adopted in various engineering scenarios. This paper presents a design methodology for thin-covered composite dowels, supported by both experimental and theoretical investigations. In the experiment, a novel test rig and specimens are designed to facilitate tensile-shear coupling loading. The study identifies a new failure mode: Restricted Cone Failure (RCF) in thin-covered composite dowels under tensile-shear coupling load, which distinct from conventional composite dowels. This RCF mode is attributed to the thin thickness of the side concrete cover, which restricts the development of the failure cone in the thickness direction. Additionally, a parametric analysis is conducted to evaluate the effects of key factors--such as steel dowel thickness, effective embedment depth, and the tensile strength of steel fiber reinforced concrete--on the bearing capacity and ductility of thin-covered composite dowels. Based on the theoretical findings, comprehensive tensile, shear, and tensile-shear coupling capacity models along with an engineering design model are developed to aid in the practical application of thin-covered composite dowels.

physics.app-ph↗

arXiv2024

CAMBranch: Contrastive Learning with Augmented MILPs for Branching

Recent advancements have introduced machine learning frameworks to enhance the Branch and Bound (B\&B) branching policies for solving Mixed Integer Linear Programming (MILP). These methods, primarily relying on imitation learning of Strong Branching, have shown superior performance. However, collecting expert samples for imitation learning, particularly for Strong Branching, is a time-consuming endeavor. To address this challenge, we propose \textbf{C}ontrastive Learning with \textbf{A}ugmented \textbf{M}ILPs for \textbf{Branch}ing (CAMBranch), a framework that generates Augmented MILPs (AMILPs) by applying variable shifting to limited expert data from their original MILPs. This approach enables the acquisition of a considerable number of labeled expert samples. CAMBranch leverages both MILPs and AMILPs for imitation learning and employs contrastive learning to enhance the model's ability to capture MILP features, thereby improving the quality of branching decisions. Experimental results demonstrate that CAMBranch, trained with only 10\% of the complete dataset, exhibits superior performance. Ablation studies further validate the effectiveness of our method.

cs.LG↗

arXiv2022

Dynamic mutation enhanced greedy strategy for wavefront shaping

Optical focusing through scattering media has important implications for optical applications in medicine, communications, and detection. In recent years, many wavefront shaping methods have been successfully applied to the field, among which the population optimization algorithm has achieved remarkable results. However, the current population optimization algorithm has some drawbacks: 1. the offspring do not fully inherit the good genes from the parent. 2. more efforts are needed to tune the parameters. In this paper, we propose the mutate greedy algorithm. It combines greedy strategies and real-time feedback of mutation rates to generate offspring. In wavefront shaping, people can realize high enhancement and fast convergence without a parameter-tuning process.

physics.optics↗

arXiv2014

Energetics and magnetism of Co-doped GaN(0001) surfaces: A first-principles stud

A comprehensive first-principles study of the energetics, electronic and magnetic properties of Co-doped GaN(0001) thin films are presented and the effect of surface structure on the magnetic coupling between Co atoms is demonstrated. It is found that Co atoms prefer to substitute the surface Ga sites in different growth conditions. In particular, a CoN/GaN interface structure with Co atoms replacing the first Ga layer is preferred under N-rich and moderately Ga-rich conditions, while CoGax/GaN interface is found to be energetically stable under extremely Ga-rich conditions. It's worth noted that the antiferromagnetic coupling between Co atoms is favorable in clean GaN(0001) surface, but the existence of FM would be expected to occur as Co concentration increased in Ga-bilayer GaN(0001) surface. Our study provides the theoretical understanding for experimental research on Co-doped GaN films and might promise the Co:GaN system potential applications in spin injection devices.

physics.comp-ph↗