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Abstract The increased demand for energy has led to the development of innovative drilling methods and technologies in the oil and gas industry. Inefficient transportation of cuttings causes downhole cleanliness issues, which have drawn widespread attention. One way to overcome cuttings transport inefficiency is to use suitable modeling methods to determine capable drilling parameters that will ensure the effective removal of cuttings particles. In this paper, Computational Fluid Dynamics (CFD) and Discrete Element Method (DEM) are combined to deeply investigate the impact of various drill parameters on cutting transport. The effects of cuttings particle size, eccentricity, fluid velocity, drill pipe/bit rotation speed, and bit offset angle are analyzed by studying the velocity of cuttings particles and the spatial distribution of particles in the annulus and bottom-hole. The results show that an increase in eccentricity and particle size reduces the velocity of cuttings particles, with the velocity decreasing more significantly when the eccentricity is greater than 0.5 and the particle size exceeds 2 mm. An increase in fluid velocity and speed of drill pipe/bit significantly increases the velocity of cuttings particles, which has a positive feedback effect on the migration of cuttings particles in the downhole. Bit offset angle leads to changes in the bottom-hole spatial structure and reduces the cuttings transport efficiency. These findings provide a useful strategy for improving cuttings migration and downhole cleaning. [ABSTRACT FROM AUTHOR]

Against the backdrop of privatization experienced by Chinese state-owned enterprises (SOEs) in recent years, this study investigates how privatized firms change cash dividend payments. Using a difference-in-differences (DiD) research design, we find an increase in cash dividends following privatization. Additional analyses reveal two channels underlying the increase in dividend payouts – that is, reduced insider tunnelling and agency problems associated with cash holding, and improved information environment after privatization. Our findings enrich the literature on privatization by providing new insights into the underlying mechanisms explaining the increased cash dividends from the agency theory and information environment perspectives. • China has deepened the privatization of its SOEs in recent years. • The privatization process allows a difference-in-differences research design. • We find that privatized firms increase cash dividends following the privatization. • Reduced insider tunnelling and free cash flow problem explain the increase. • Enhanced information environment post privatization also explains the increase. [ABSTRACT FROM AUTHOR]

Object detection with high accuracy is becoming increasingly important for industrial processes, such as producing printed circuit boards (PCBs). A false or missed detection during production can lead to serious quality issues. Therefore, an efficient detector that can maintain high quality is required for industrial applications. This paper proposes a method for improving detection accuracy while supporting real-time operations using the baseline YOLOv4. A new loss function for box regression called Gaussian intersection of union (GsIoU) is explored, which merges the predicted boxes under different anchors at the same position using a Gaussian function to calculate the box regression loss, improving the accuracy of the final box regression. The proposed PCB Component (PCBC) dataset is a benchmark comprising 18,948 images, 24 categories (containing the same component in different directions), and 508,313 components. Taking YOLOv4 as the experimental baseline on the PCBC dataset, the mean average precision (mAP) using the GsIoU has reached 86.9%, which is improved by 3.3% and 2.2% compared to using the CIoU and GIoU loss functions, respectively. The experiments were conducted on the COCO dataset to verify the generalization of the GsIoU. The detection accuracy of the GsIoU exceeds that GIoU and CIoU by 0.6% on AP 50 and 0.6% on AP 50:95 , achieving 65.6% and 46.0% on the COCO test-val2017, respectively. The detection efficiency of the proposed method is the same as that of the baseline in the testing process and is slightly reduced in the training process owing to the synchronous calculation of the IoU, variance, and Gaussian operations on the network output. The experiments indicate that GsIoU is effective and efficient. • A novel Gaussian intersection over union is designed for box regression. • An adaptive weight strategy is introduced for loss function. • A new dataset of circuit board components (PCBC dataset) is created. • The proposed method achieves good performance on COCO dataset and PCBC dataset. [ABSTRACT FROM AUTHOR]

This study examines how state subsidies to firms affect corporate investment efficiency. Using archival data from a sample of Chinese listed firms over the 2007–2015 period, we find that government subsidies have a negative effect on firms' investment efficiency, and this negative effect is more pronounced for firms that are less financially constrained. Further analyses suggest that government subsidies are positively associated with firms' over-investment, although they alleviate under-investment. Our findings are robust to a series of tests to alleviate concerns about potential endogeneity and self-selection bias. • We ask if financial subsidies received from the state affect investment efficiency. • A negative effect is found that is more pronounced for less financially constrained firms. • Subsidies do alleviate under-investment. • But subsidies are positively associated with over-investment. [ABSTRACT FROM AUTHOR]