Flutter Derivatives Identification and Uncertainty Quantification for Bridge Decks Based on the Artificial Bee Colony Algorithm and Bootstrap Technique

This paper presents a novel parameter identification and uncertainty quantification method for flutter derivatives estimation of bridge decks. The proposed approach is based on free-decay vibration records of a sectional model in wind tunnel tests, which consists of parameter identification by a heuristic optimization algorithm in the sense of weighted least squares and uncertainty quantification by a bootstrap technique. The novel contributions of the method are on three fronts. Firstly, weighting factors associated with vertical and torsional motion in the objective function are determined more reasonably using an iterative procedure rather than preassigned. Secondly, flutter derivatives are identified using a hybrid heuristic and classical optimization method, which integrates a modified artificial bee colony algorithm with the Powell’s algorithm. Thirdly, a statistical bootstrap technique is used to quantify the uncertainties of flutter derivatives. The advantages of the proposed method with respect to other methods are faster and more accurate achievement of the global optimum, and refined uncertainty quantification in the identified flutter derivatives. The effectiveness and reliability of the proposed method are validated through noisy data of a numerically simulated thin plate and experimental data of a bridge deck sectional model.

Determinants of Corporate Environment, Social and Governance (ESG) Reporting among Asian Firms

Departing from previous studies, which have mostly focused on Western countries, our work investigates the determinants of the corporate environment, social and governance (ESG) reporting among Asian firms. Examining Asian public listed firms from 2005 to 2017, our cross-sectional model results indicate that firm characteristics (economic performance, profitability, leverage and size) are found to disclose additional ESG information. The outcome is consistent with the legitimacy theory, which posits that firms provide higher ESG reporting to legitimize and justify the firm’s continuous existence. The findings are important for firms, stakeholders and policymakers. While firms may formulate ways to improve ESG reporting to compete in the international market, the stakeholders may pressure firms to disclose more information on ESG and policymakers to designalegal framework on ESG that suits firms in Asia.