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The smooth motion profile with less oscillation ensures the processing quality of machined parts. Meanwhile, keeping feedrate under its limit as high as possible can reduce the processing time and save cost. In this paper, a novel feedrate scheduling algorithm with acceleration lookahead is presented. Through the sin2 acceleration profile, the continuity of jerk can be guaranteed. Based on the 4-phase profile, the look-ahead function is also extended for acceleration, which avoids the frequent changing of acceleration when scheduling short segments. On a designed benchmark, the effectiveness of the proposed algorithm is verified and compared with the state-of-the-art. The algorithm is implemented on a laser patterning machine with the galvanometric scanners as its feed drive system. The results confirm the effectiveness of the presented scheduling method. [ABSTRACT FROM AUTHOR]

Coalbed methane (CBM) reservoirs usually require stimulation to enhance the permeability, thereby promoting CBM production. Realized by the conversion of the electromagnetic energy into heat, microwave heating may be an effective CBM stimulation method. In this study, the effects of microwave heating on the damage of coal were investigated through scanning electron microscope and ultrasonic wave tests. The results indicate that the mineral grain in coal generally disappears after microwave heating. For low-permeable coals with highly mineralized fractures, the dissolution of mineral could potentially enhance permeability and improve stress resilience. Microwave selective heating can lead to the opening and extension of original fractures and the generation of secondary fractures, reducing P-wave and S-wave velocity of coal. The stronger the anisotropy of coal is, the greater the microwave fracturing effect becomes. In a word, microwave heating has potential for assisting coalbed methane exploitation. [ABSTRACT FROM AUTHOR]