Policy Iteration Based Online Adaptive Optimal Fault Compensation Control for Spacecraft

Yanbin Du,Bin Jiang,Yajie Ma 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.4

In this paper, a novel online adaptive optimal fault-tolerant control (FTC) scheme based on policy iteration (PI) algorithm is developed for the spacecraft attitude angular velocity tracking control with actuator faults. First, for the fault-free attitude dynamic model, an adaptive optimal controller is designed based on PI algorithm to solve the Hamilton-Jacobi-Bellman (HJB) equation. In this process of solving, the value function is approximated by means of a critic neural network (NN). Then, a novel adaptive compensation law is proposed for estimation of actuator faults. The closed-loop system is proved to be uniformly ultimately bounded (UUB) via the Lyapunov’s method. Finally, the effectiveness of the proposed control scheme is evaluated via simulation experiments.

ESPO Based Course-tracking Control of Ships with Input Delay

Yanbin Wu,Pengfei Gao,Rui Wu,Jialu Du 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.3

Consider the course-tracking control issue of ships with the dynamic parameter uncertainties, unknown time-varying ocean environment disturbance, and input delay. This paper creates a novel ship course-tracking control solution scheme under a uniformed framework such that the ship course tracks the desired course. Therein, an extended state predictor observer (ESPO) is constructed to estimate the course and the yaw rate of ships as well as the total disturbance caused by ship dynamic parameter uncertainties and unknown time-varying environment disturbance at the future instants, and whereby eventually contributes to compensating both the input delay and the total disturbance. Theoretical analyses indicate that our developed ship course-tracking control law with ESPO achieves the uniform stability of ship course-tracking closed-loop control system. Simulation results and simulation comparisons on a frigate demonstrate the effectiveness and superiority of our developed control law for ships with input delay.

Modeling and Optimization Method of Laser Cladding Based on GA-ACO-RFR and GNSGA-II

Guohua He,Yanbin Du,Qiang Liang,Zhijie Zhou,Linsen Shu 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.5

Laser cladding is an environmentally friendly and reliable surface modification technology. The quality characteristics of the coating are directly affected by the process parameters of laser cladding. The reasonable selection of process parameters is essential to obtain high-quality coating. In this study, the single-track 15-5PH alloy coating was fabricated on the surface of 12Cr13 stainless steel. In view of the hybrid Genetic Algorithm and Ant Colony Optimization (GA-ACO) can effectively improve the prediction ability and robustness of Random Forest Regression (RFR), a prediction method of cladding layer quality characteristics based on GA-ACO-RFR was proposed. The fast non-dominated ranking genetic algorithm with elite strategy by introducing the Gaussian distribution crossover operator (GNSGA-II) was used to optimize the process parameters of laser cladding. The results showed that the multi-objective optimization method of laser cladding process parameters proposed in this paper can obtain high-quality laser cladding coating. This work demonstrated the potential of the proposed method in laser cladding process prediction and optimization.

The Impact of Auditor-Client Traffic Convenience on Earnings Management in China

Hong YIN,Yanbin DU 한국유통과학회 2021 Asian Journal of Business Environment (AJBE) Vol.11 No.4

Purpose: This study aims to investigate the impact of auditor-client traffic convenience on accrual -based and real earnings management of the client firms. Research design, data and methodology: Using a sample of firms listed in Shanghai and Shenzhen Stock Exchanges over the period of 2007 to 2018, this paper empirically investigates the association between auditor-client traffic convenience and earnings management. We use three measures of auditor-client traffic convenience: railway traffic convenience, expressway traffic convenience, and air traffic convenience. The accrual-based earnings management is measured by abnormal accruals estimated by industry and year using the Modified Jones Model. Results: Findings indicate that traffic convenience is conducive to detecting and restraining positive accrual earnings management and real earnings management. After changing the measurement of independent variable and dependent variable, including potential omitted variables, the results are statistically unchanged. Further, the research shows that traffic convenience can not only improve audit quality, but also lead to higher fee premiums. Auditors didn’t share with clients the cost reduction benefits caused by traffic convenience. Conclusions: Traffic convenience provides auditors with easy access to the client firms, alleviating the information asymmetry and improving corporate earnings quality. The findings have implications for regulators, audit practitioners and stakeholders.

The Impact of Executive Pay Gap on Audit Pricing in China

Hong YIN,Yanbin DU 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.6

This study aims to test the economic consequences of the tournament incentive. First, we investigate the impact of the pay gap among top executives and the pay gap between executives and employees on audit pricing using a large sample of Chinese listed firms from 2008 to 2019. Then, we test the moderating role of ownership property, technological complexity and corporate governance in the association between the executive pay gap and audit fees. Findings indicate that the executive pay gap is positively associated with audit fees. The positive association between the executive pay gap and audit fees is more pronounced in private firms, firms with fewer R&D expenditures, and firms with smaller proportion of independent directors. Further studies suggest that large executive pay gap motivates managerial opportunistic behaviors, resulting in more accrual-based earnings management and real activities manipulation. Our results, consistent with managerial power theory, show that auditors assess firms with large executive pay gap as high risk and incorporate the audit risk and audit business risk associated with the executive pay gap into audit pricing. The results provide further evidence for regulators to strengthen supervision on the executive compensation, especially the executive compensation of state-owned enterprises and firms with weak corporate governance.

The Impact of Auditor-Client Traffic Convenience on Earnings Management in China

YIN, Hong,DU, Yanbin Korea Distribution Science Association 2021 Asian journal of business environment Vol.11 No.4

Purpose: This study aims to investigate the impact of auditor-client traffic convenience on accrual -based and real earnings management of the client firms. Research design, data and methodology: Using a sample of firms listed in Shanghai and Shenzhen Stock Exchanges over the period of 2007 to 2018, this paper empirically investigates the association between auditor-client traffic convenience and earnings management. We use three measures of auditor-client traffic convenience: railway traffic convenience, expressway traffic convenience, and air traffic convenience. The accrual-based earnings management is measured by abnormal accruals estimated by industry and year using the Modified Jones Model. Results: Findings indicate that traffic convenience is conducive to detecting and restraining positive accrual earnings management and real earnings management. After changing the measurement of independent variable and dependent variable, including potential omitted variables, the results are statistically unchanged. Further, the research shows that traffic convenience can not only improve audit quality, but also lead to higher fee premiums. Auditors didn't share with clients the cost reduction benefits caused by traffic convenience. Conclusions: Traffic convenience provides auditors with easy access to the client firms, alleviating the information asymmetry and improving corporate earnings quality. The findings have implications for regulators, audit practitioners and stakeholders.

A Study on Audit Regulation Engagement Interview and Audit Quality

Hong YIN,Yanbin DU 한국유통과학회 2021 The Journal of Industrial Distribution & Business( Vol.12 No.8

Outcomes of Posterior Lumbar Hemivertebra Resection and Short Fusion in Patients With Severe Sacral Tilt

Shengru Wang,Jianguo Zhang,Yanbin Zhang,You Du,Yang Yang,Guanfeng Lin 대한척추신경외과학회 2021 Neurospine Vol.18 No.3

Objective: To introduce surgical strategies to restore coronal balance during limited fusion for early lumbar hemivertebra resection in patients with severe sacral tilt. Methods: Sacral tilt was defined as a sacral tilt angle ≥5, and severe sacral tilt was defined as a sacral tilt angle >10. From July 2004 to December 2017, 73 consecutive patients treated with posterior hemivertebra resection and short fusion in our institution were evaluated. Severe sacral tilt was noted in 26 patients (14 boys and 12 girls), and all were enrolled in this study. Undercorrection of the primary lumbar curve as compensation for the sacral tilt and short fusion was performed in these patients. The medical charts and imaging data of the patients were retrospectively reviewed to evaluate the outcomes. Results: All patients were followed for at least 2 years. The mean age at the time of surgery was 3.7 (2–9) years old, with a total of 31 lumbar hemivertebra excised. On average, 2.8 (2–5) segments were fused for each patient. Sacral tilt minimally improved from 14.5° preoperatively to 13.6° postoperatively (p=0.15) and remained stable at the follow-up. The overall lumbar curve was 41.9° preoperatively, 11.7° immediately postoperatively, and 14.6° at the final follow-up. The segmental scoliosis curve was 39.1° preoperatively, 9.7° immediately postoperatively, and 11.2° at the final follow-up. Segmental kyphosis was corrected from 27.2° to 6.5° after the surgery and was 7.1° at the latest follow-up. Conclusion: Sacral tilt is seen in patients with congenital scoliosis in lumbar hemivertebra. Undercorrection of the lumbar curve and segmental scoliosis to compensate for sacral tilt and short fusion after hemivertebra resection may be helpful to restore coronal balance and preserve mobility in segments in patients with pronounced severe sacral tilt.

A novel flexible micro-ratchet/ZnO nano-rods surface with rapid recovery icephobic performance

왕만상,Wenbo Yu,Yupei Zhang,우재영,Yucheng Du,Bo Wang,Yanbin Yun,유계성,이중기,Lei Wang 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.62 No.-

In this communication, we present a significant method to fabricate a robust icephobic surface on a flexible polymer substrate. The flexible functional surface is obtained by integrating both soft-lithography and crystal growth methods. Modified by the materials with low surface free energy, the composite surface exhibits a robust superhydrophobicity at not only room temperature but also low temperature. After freezing test, the surface can recover to its original function quickly, which has achieved the level for industrial application, and also performed significant role for enhancing the icephobic theories.