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Periodic inspection of bridge cables is essential, and cable-climbing robots can replace human workers to perform risky tasks and improve inspection efficiency. However, cable inspection robots often fail to surmount large obstacles and cable clamps. The purpose of this paper is to develop a practical cable inspection robot with stronger obstacle-surmounting performance and circumferential rotation capability.

A cable inspection robot with novel elastic suspension mechanisms and circumferential rotation mechanisms is designed and proposed in this study. The supporting force and spring deformation of the elastic suspension are investigated and calculated. Dynamic analysis of obstacle surmounting and circumferential rotation is performed. Experiments are conducted on vertical and inclined cables to test the obstacle-surmounting performance and cable-clamp passing of the robot. The practicality of the robot is then verified in field tests.

With its elastic suspension mechanisms, the cable inspection robot can carry a 12.4 kg payload and stably climb a vertical cable. The maximum heights of obstacles surmounted by the driving wheels and the passive wheels of the robot are 15 mm and 13 mm, respectively. Equipped with circumferential rotation mechanisms, the robot can flexibly rotate and successfully pass cable clamps.

The novel elastic suspension mechanism and circumferential rotation mechanism improve the performance of the cable inspection robot and solve the problem of surmounting obstacles and cable clamps. Application of the robot can promote the automation of bridge cable inspection.

The paper aims to examine the corporate social responsibility (CSR) activity of audit firms.

Using hand-collected data on all Chinese audit firms’ CSR activities from 2007 to 2020, this study constructs two measures to proxy for audit firms’ CSR engagement: a dummy variable to indicate whether an auditor engages in CSR activities in year t and the frequency with which auditors conduct CSR activities in year t. The authors use ordinary least squares regression as a baseline methodology, along with the entropy balancing method and instrumental variable approach to alleviate potential endogeneity concerns.

The baseline results show that socially responsible audit firms provide higher quality audit services than their counterparts. In particular, the authors find that clients audited by socially responsible audit firms are less likely to receive an aggressively clean opinion. Moreover, the findings suggest that CSR activities related to community and employees are more relevant in improving audit quality compared with those related to other dimensions of CSR. Further analyses show that capital markets and audit clients react positively to audit-firm CSR activity. Audit firms engaging in CSR increase their audit inputs in response to risky clients, as compared with their counterparts. Finally, cross-sectional analyses show that the positive relationship is more pronounced for non-Big 4 and non-industry experts and is attenuated by within-firm geographic dispersion. In terms of client characteristics, the positive effect of audit-firm CSR is stronger when their clients face the higher financial risk or have lower CSR awareness than others. Taken together, these findings are consistent with the ethical view of audit-firm CSR engagement.

The study advances investors’ understanding of audit-firm CSR engagement and helps them evaluate the credibility of audited financial reports. Besides, the findings may also help guide the audit firms to conduct more CSR activities and help guide the audit clients to choose CSR audit firms.

To the best of the authors’ knowledge, this study provides the first large-sample evidence by empirically examining the association between audit-firm CSR activity and audit service performance. Besides, this paper also explores audit-firm CSR activity from two competing perspectives, thereby providing a comprehensive understanding of this issue. Finally, this work responds to the call for more CSR research in emerging markets.