An efficient dynamic reliability method for maglev vehicle-bridge systems and its application in random controller parameters analysis

The purpose of this research is to prove the eventuality of using a novel adaptive surrogate model for optimization problems. The adaptive surrogate model is based on iteration sampling and extended radial basis function (ERBF). This method improves the precision by a means that new sample points is placed in the blank area and all the sample points is uniformly distributed in the design region. The precision of the surrogate model is checked using standard error measure to determine whether updating the surrogate model or not. Since the prediction of modal frequencies require structure modal simulations. In order to decrease the number of computer simulations, a Multi-Island GA approach is combined with the adaptive surrogate model to find the optimum modal frequencies of a strapdown inertial navigation system for electric helicopters. The strapdown inertial navigation system is comprised of damping material, counterweight material and inertial navigation sensor. This is a multi-objective functions optimization problem since the modal frequencies are considered from mode 1 to mode 6 in this paper. Several weights of multi-objective functions are utilized to research the modal frequencies. The whole number of 15 sampling points is picked to build the primary surrogate model using Latin hypercube sampling (LHS). The results of adaptive surrogate model show that two new sampling points are needed to reform the precision of the surrogate model under the condition of 2 % confidence bounds. The structure modal optimization results show that the choice of the weights for the multi-objective functions has a major effect on the final optimum modal frequencies. Time- and frequency-domain analysis indicated that the optimum modal frequencies are far away from the excitation frequencies to avoid strapdown inertial navigation system resonance as far as possible.

Probability density evolution method for seismic displacement-based assessment of earth retaining structures

Comparison of PDEM and MCS: Accuracy and efficiency

Dynamic reliability analysis of Aerial Building Machine under extreme wind loads using improved QBDC-based active learning

Dynamic reliability analysis of slopes based on the probability density evolution method

Reliability assessment of stochastic dynamical systems using physics informed neural network based PDEM

Surrogate modeling immersed probability density evolution method for structural reliability analysis in high dimensions

Structural design optimization under dynamic reliability constraints based on the probability density evolution method and highly-efficient sensitivity analysis

The Mean Time to Failure (MTTF) is a critical metric for assessing the reliability of non-repairable systems, and it plays a significant role in incident management. However, accurately estimating MTTF can be challenging due to the limited availability and quality of historical experimental data on a group of identical parts or systems. To address this challenge, we propose an adaptive surrogate modeling method, which approximate the system’s performance functions with a more computationally efficient model to predict the MTTF during the design stage. In this paper, we develop an adaptive Gaussian process (GP) approach that combines with Monte Carlo simulation (MCS) to predict MTTF. The proposed method initially trains a GP model for the system’s performance function, and then an MTTF surrogate model can be obtained. With a learning function, these models are updated dynamically based on new information as it becomes available. We demonstrate the effectiveness of our method on series system, parallel system, and mixed system with two examples, and the results show that the adaptive surrogate modeling method can accurately predict the MTTF of the system. Our method has the potential to improve the reliability and safety of complex system and reduces the need for costly performance testing.

An adaptive hybrid deep learning-based reliability assessment framework for damping track system considering multi-random variables

Adaptive modeling strategy for constrained global optimization with application to aerodynamic wing design

In a complex pressurized water diversion project (WDP), the combined optimal operation of multiple hydraulic facilities is computationally expensive owing to the requirement of massive mathematical simulation model runs. A parallel multi-objective optimization based on adaptive surrogate model (PMO-ASMO) was proposed in this study to alleviate the computational burden while maintaining its effectiveness. At the simulation level, an adaptive surrogate model was established, while a parallel non-dominated sorting genetic algorithm II (PNSGA-II) was utilized at the optimization level. Taking the successive shutdown of pumps as the operating process, the PMO-ASMO was applied to a complex pressurized diversion section of the Jiaodong WDP in China, and the results were compared with those obtained by NSGA-II and PNSGA-II. The results showed that the time consumption of PMO-ASMO was only 9.97% of that acquired by NSGA-II, which was comparable to that of PNSGA-II, in the case of 10-core parallelism. Moreover, compared with PNSGA-II, PMO-ASMO could find the optimal and stable Pareto front with the same number of simulation model runs, or even fewer runs. These results validated the effectiveness and efficiency of the PMO-ASMO. Therefore, the proposed framework based on multi-objective optimization is efficient for combined optimal operation of multiple hydraulic facilities.

Running trains on a long-span bridge under earthquake is an inevitable problem for the high-speed railway in seismic regions. This paper aims to investigate the seismically random dynamic behavior of train–cable stayed bridges interaction system using the probability density evolution method (PDEM). The system simultaneously involves the multi-effect of random multi-point earthquake excitations with traveling waves and random track irregularity. The multi-point earthquake excitations, composed of lateral and vertical positions, are generated by stochastic harmful functions (SHFs) and uniformly modulated into nonstationary random processes. The motion equation of such a system is established by coupling the 38-degree vehicles and bridges through the refined random wheel/rail contact relationship and accounting for the phase-lags of seismic travelling waves between pier excitations. PDEM is proven to be applicable to such time-dependent systems and is then used to transform the random excitations into a series of deterministic representative excitations with initial probability. By solving for the corresponding deterministic probability responses, various nonstationary random responses, including the time-dependent probability density evolution functions of random responses, mean values curves and standard deviations, can be obtained easily. A case study based on the cable-stayed bridge is then presented, and the results show the effectiveness and accuracy of the proposed method by comparison with Monte Carlo Simulation. Additionally, the influence of train speed and seismic intensity on the safety and reliability of trains is discussed.

Physics guided wavelet convolutional neural network for wind-induced vibration modeling with application to structural dynamic reliability analysis

Abstract. Parameter specification usually has significant influence on the performance of land surface models (LSMs). However, estimating the parameters properly is a challenging task due to the following reasons: (1) LSMs usually have too many adjustable parameters (20 to 100 or even more), leading to the curse of dimensionality in the parameter input space; (2) LSMs usually have many output variables involving water/energy/carbon cycles, so that calibrating LSMs is actually a multi-objective optimization problem; (3) Regional LSMs are expensive to run, while conventional multi-objective optimization methods need a large number of model runs (typically ~105–106). It makes parameter optimization computationally prohibitive. An uncertainty quantification framework was developed to meet the aforementioned challenges, which include the following steps: (1) using parameter screening to reduce the number of adjustable parameters, (2) using surrogate models to emulate the responses of dynamic models to the variation of adjustable parameters, (3) using an adaptive strategy to improve the efficiency of surrogate modeling-based optimization; (4) using a weighting function to transfer multi-objective optimization to single-objective optimization. In this study, we demonstrate the uncertainty quantification framework on a single column application of a LSM – the Common Land Model (CoLM), and evaluate the effectiveness and efficiency of the proposed framework. The result indicate that this framework can efficiently achieve optimal parameters in a more effective way. Moreover, this result implies the possibility of calibrating other large complex dynamic models, such as regional-scale LSMs, atmospheric models and climate models.