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During drilling in coal mines, sticking of drill rod (referred to as SDR in this work) is a potential threat to underground safety. However, no practical measures to deter SDR have been developed yet. The purpose of this study is to develop an anti-SDR strategy using proportional-integral-derivative (PID) and compliance control (PIDC). The proposed strategy is compatible with the drilling process currently used in underground coal mines using drill rigs. Therefore, this study aims to contribute to the PIDC strategy for solving SDR.

A hydraulic circuit to reduce SDR was built based on a load-independent flow distribution system, a PID controller was designed to control the inlet hydraulic pressure of the rotation motor and a typical compliance control approach was adopted to control the feed force and displacement. Moreover, the weight and optimal combination of the alternative admittance control parameters for the feed cylinder were obtained by adopting the orthogonal experiment approach. Furthermore, a fuzzy admittance control approach was proposed to control the feed displacement. Experiments were conducted to test the effectiveness of the proposed method.

The experimental results indicated that the PIDC strategy was appropriate and effective for controlling the rotation motor and feed cylinder; thus, the proposed method significantly reduces the SDR during drilling operations in underground coal mines.

As the PIDC strategy solves the SDR problem in underground coal mines, it greatly improves the safety of coal mine operation and decreases the power cost. Consequently, it brings the considerable benefits of coal mine production and vast application prospects in other corresponding fields. Actual drilling conditions are difficult to accurately simulate in a laboratory; thus, for future work, drilling experiments can be conducted in actual underground coal mines.

The PIDC-based anti-SDR strategy proposed in this study satisfactorily controls the rotation motor and feed cylinder and facilitates the feed and rotation movements. Furthermore, the tangible novelty of this study results is that it improves the frequency response of the entire drilling system. The drilling process with PIDC decreased the occurrence of SDR by 50%; therefore, the anti-SDR strategy can significantly improve the safety and efficiency of underground coal mining.

This study aims to explore the influence of information presentation conditions on the flow experience of digital reading for high school students.

Firstly, a survey determines the preferred reading medium and the types of texts that high school students frequently read. Secondly, Experiment 1 focuses on the effects of the text type and reading medium on flow experience and reading comprehension. Finally, Experiment 2 addresses a narrative text presented on a smartphone, and discusses the influence of advance organizer, presentation format and page layout on flow experience and reading comprehension.

In digital reading, the narrative text has a stronger flow experience than explanatory text; the flow experience of reading narration on smartphones is more evident than on computers. The advance organizer and text combined with pictures are more conducive to a flow experience when a smartphone is used as a reading medium. From the perspective of reading comprehension, scrolling is more suitable for reading text combined with pictures and paging best suits pure text.

Through experimental methods, this study reveals the influence of information presentation conditions on the digital reading flow experience, which is a meaningful and innovative topic. The findings can provide more enlightenment and reference for the design and promotion of digital resources and digital reading by teenagers.