Symmetry

Accurate crack segmentation is important for intelligent infrastructure inspection and has potential applications in railway infrastructure monitoring. However, cracks usually exhibit thin, elongated, irregular, and spatially asymmetric morphologies, while weak boundaries and complex surface textures further increase segmentation difficulty. To address these challenges, this paper proposes HLGCrack, a lightweight hierarchical CNN-Mamba-attention network for efficient crack segmentation. The network adopts a stage-wise representation strategy in which shallow asymmetric convolution and large-kernel modeling enhance directional edge responses and local crack structures, while deeper visual state-space and local–global attention modules capture long-range dependencies and contextual information. A Lightweight Progressive Fusion decoder progressively aggregates multi-level features to recover fine crack boundaries with low computational cost, and BCE, Dice, and clDice losses are jointly employed to improve region overlap and structural continuity. HLGCrack is evaluated on CamCrack789 and four additional public pavement and structural crack datasets covering diverse crack morphologies, surface textures, and interference conditions. On CamCrack789, it achieves Dice and IoU scores of 0.860 and 0.755, respectively, with only 3.53 M parameters and 4.03 G FLOPs. The results demonstrate its effectiveness and robustness for general crack segmentation and provide a basis for subsequent adaptation to railway-specific inspection scenarios.

The Minimum Hitting Set (MinHS) problem is a classic NP-hard problem in combinatorial optimization, widely applied across fields such as artificial intelligence diagnosis, bioinformatics, and network monitoring. This paper proposes a local search algorithm with Dual-evaluation mode, named DemHS (Dual-evaluation mode search algorithm), tailored for large-scale hitting set instances. The evaluation employs two types of functions: strong and weak. Strong evaluation accurately calculates the exchange gain by introducing a cross-correction term within the local neighborhood defined by an inserted vertex; meanwhile, weak evaluation quickly estimates the gain through global random sampling to broaden the search scope. These two functions synergistically guide the search process. Furthermore, we introduce an age strategy to break ties and enhance the diversity of the search path. When no improvements are made for extended iterations, a large-scale random perturbation is executed to help the algorithm escape local stagnation. Comparative experiments were conducted using 200 public hitting set instances (100 metaheuristic and 100 exact cases) from PACE-2025. The results show that, in the metaheuristic case group, DemHS improves the record on 62 instances and in the precise case group, DemHS obtains optimal solutions across all tested instances. The ablation studies demonstrate a significant positive gain from the dual-evaluation neighborhood structure on optimization results.

Blasting in open-pit mines can disturb permanent underground structures. This study examines an underground water sump in medium–hard dolomite at Kunyang Phosphate Mine. A detailed three-dimensional model was built in ANSYS Workbench. The Drucker–Prager (D-P) yield criterion was used. Measured acceleration time histories were applied throughout the model in three directions. Six cases were identified by representative peak vibration velocities of 6.4–27.1 cm/s. Transient dynamic analyses examined stress, displacement, vibration velocity and local safety reserve. High stresses occurred at junctions of the roof and walls, bottom corners and sump–shaft connections. The peak equivalent stress increased almost linearly from 8.08 to 12.90 MPa. The maximum principal stress showed local tension and compression. Its tensile peak increased from 0.72 to 3.56 MPa. This was below the static tensile reference of 9.44 MPa for intact laboratory specimens. The minimum principal stress was mainly compressive. The peak compressive stress in the deep surrounding rock reached −15.10 MPa. Positive displacement peaks increased from 0.69 to 2.51 mm. Negative peaks changed from −0.80 to −2.71 mm. These values describe transient model responses. Positive velocity peaks increased from 6.36 to 26.74 cm/s. Cases P2–P6 exceeded the project control reference of 8.5 cm/s. The local indicator FS was greater than one for the extracted states at all nine monitoring locations. At high vibration levels, FS was about 1.25 at the arch baseline and the middle of the bottom side wall. These locations had relatively low reserves. The results provide a quantitative basis for blast parameter optimisation and vibration control for the water sump.