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In order to carry out early warning for the abnormal state of engineering structures in time and optimize early warning interval (WI), a new construction of WI method based on relevance vector machine (RVM) and particle swarm optimization (PSO) under the framework of lower upper bound estimation (LUBE) is proposed. First, extract time-domain features of structural monitoring data and then two RVM models are trained using time-domain features to construct lower and upper bound of WI. Kernel parameters of RVM are optimized by PSO algorithm to minimize the loss function of LUBE and obtain the best optimal evaluation indices of WI. The LUBE based on PSO-RVM interval warning method is verified through a numerical simulation and a case study on structural monitoring data of quayside container crane (QCC), and the performance of WI is compared with other prediction methods. The results indicate that the proposed construction of WI method can effectively improve the quality of WI, realize early warning damage, and provide better performance for early WI.

Industrial brakes pose the dilemma of weighing brake capability against brake impact since the brake torque cannot be adjusted. On the one hand, the brake torque may be insufficient to stop the movement within a limited distance or parking position. On the other hand, the brake torque may be so high it can damage the transmission chain. In this study, the traditional brake strategy and the field oriented control (FOC) brake strategy were compared through simulation and a rotational inertia test. The influence of the rated brake torque and the open-closed ratio were obtained. Based on the test and simulation results, a semi-empirical formula that defines the relationship between relative brake capability and open-closed ratio was developed. Additional simulations were performed to analyze the performance of the brake in a flexible transmission chain. As an industrial application example, the benefits and the cost of a 'smart brake' based on the FOC brake strategy were analyzed. The results indicate that the equivalent brake torque with the FOC brake strategy is a function of the realtime controllable input and open-closed ratio, which can be conducted during the braking procedure. This can be an efficient way to solve the above problems.