The mine ventilator plays a role in protecting the life safety of underground workers, which is very significant to the production and development of coal mines. In total, 70% of ventilator failures are mechanical failures, and bearing failures are the most likely to occur in mechanical failures, which are also difficult to find. In order to identify fan bearing faults accurately, this paper proposes a fault diagnosis method based on improved variational mode decomposition and density peak clustering. First, the variational mode decomposition’s modal number K and secondary penalty factor α are chosen employing the improved sparrow optimization process. The bearing vibration signal is decomposed by the variational mode decomposition algorithm with optimized parameters. To create the characteristic vector, the multi-scale permutation entropy of the fourth order intrinsic mode function is determined. Then, the characteristic matrix is dimensionally reduced by kernel principal component analysis, and the two-dimensional matrix after dimensionality reduction is divided by density peak clustering method to find the clustering center of the training sample features. Lastly, the membership degree is assessed using the normalized clustering distance between the characteristic matrix of the test sample and the cluster center of the training sample. The accuracy of bearing fault identification on the self-constructed experimental platform can reach 100%, which verifies the effectiveness and potential of the proposed method.

Figuring out the thermal response and damage features of fabricated steel structures under fire conduces to enhancing the fire resistance of steel structures and lowering the probability of fire accidents. Available methods are able to simulate complex fire situations, but their accuracy is affected by the adopted models and calculation methods. For this reason, this paper researched the thermal response and damage features of fabricated steel structures under fire. At first, the thermal response of fabricated steel structures under fire was analyzed, the ultimate bearing capacity and the fire resistance was calculated and checked. Then, the evolution of fatigue damage of fabricated steel structures under fire was analyzed, and the fatigue damage evolution method and its flow were given. At last, combining with actual cases, the thermal response and damage features of fabricated steel structures under fire were examined experimentally, and the results verified the validity of the proposed analysis method.