In this paper, a macroslip detection method is proposed for a metal V-belt continuously variable transmission, and a clamping force control strategy is suggested on the basis of a macroslip detection method. Using the rotational accelerations of the primary and secondary pulleys, the velocity of the secondary pulley and the speed ratio of the continuously variable transmission variator, observation signals are defined. The characteristics of the observation signals are investigated by simulations in a vehicle-driving environment. It is found that two observation signals became unsynchronized when macroslip occurs. Considering the oscillations of the acceleration signal and the noise from the sensors or the differentiating process, a signal-processing method for the observation signals is suggested. Based on the signal-processing results, a variable called the ‘amplitude difference rate’ is introduced for slip evaluation. A macroslip detection method that uses the amplitude difference rate is proposed. The effectiveness of the macroslip detection method is validated by experiments. It is found from the experiments that the proposed method can effectively detect macroslip with an acceptable time delay. In addition, a clamping force control strategy based on the macroslip detection method is developed. In this strategy, the clamping force is maintained at a minimum value with a safety factor of 1 in normal driving conditions but an additional clamping force is applied when macroslip is detected. It is found from the simulation results that macroslip is eliminated by clamping force control. It is expected that the efficiency of the continuously variable transmission system can be improved by reducing the marginal clamping force using the proposed macroslip detection method and the clamping force control strategy.

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In this study, a macroslip detection method is proposed for a metal V-belt continuously variable transmission. The macroslip detection method was developed using the instantaneous periods of the primary pulley's acceleration and the secondary pulley's acceleration, which can be obtained from the existing speed sensors. To obtain the instantaneous periods of the accelerations of the pulleys in real time, a signal-processing method was developed on the basis of zerocross detection. Using the instantaneous periods, the period difference is introduced, and a threshold value b is defined to evaluate the slip state. The characteristics of the period difference and b were investigated by a three-dimensional analysis, in which a three-dimensional model of the continuously variable transmission including the blocks, the bands and the pulleys was constructed, and the velocity of each element and the slip rate were obtained. From the simulation results, it was found that the period difference stays below the threshold value b in the microslip region and begins to increase over the threshold value b in the macroslip region. The macroslip detection method proposed in this study was validated by experiments, which showed that the method is effective for detecting the occurrence of macroslip, independently of the input torque and the speed ratio.

Airport pavements are prone to early defects during the construction phase, and their early performance during the construction phase is significantly affected by the external temperature field. This article takes the concrete pavement of Xiamen Xiang’an New Airport as an example and uses a three-dimensional (3D) humidity simulation program for cement concrete pavement to study the evolution behavior of the early stage humidity field of the pavement in a humid and hot climate environment. The results indicate that the evolution law of the humidity field of the concrete pavement slab was consistent with the environmental field, presenting a 24 h periodic variation. The environmental field had a significant impact on the humidity of the surface layer of the pavement slab, and the humidity decreased rapidly with time. There was a humidity gradient on both the horizontal plane and the cutting plane of the slab, the horizontal humidity was concentrated from the boundary into the middle of the slab, and the sectional humidity was concentrated from the top to the bottom of the slab. Environmental parameters, construction parameters, and material and structural parameters all influenced humidity through humidity exchange or by changing the saturated vapor pressure inside the slab. The humidity field was most sensitive to environmental humidity and maintenance methods, but less sensitive to material parameters and structural parameters. Through analysis, it is advisable to avoid hot seasons, choose periods of increased environmental humidity, adopt appropriate maintenance methods during construction to reduce humidity stress on the slab, and therefore decrease early stage deterioration and improve service life.

Compaction directly affects concrete’s strength and durability. In this paper, the relationship between vibration parameters and compactness is modeled by using colored aggregates and image methods to analyze the compactness of concrete characterized by pore structure. Experiments were conducted to investigate the effects of vibrating frequency and duration on the aggregate distribution coefficient, segregation rate, and porosity of slipform concrete. The test results showed that the smaller the aggregate size under high-frequency pounding, the better the concrete compactness. In addition, the aggregate segregation rate and concrete strength increased and then decreased with the pounding length, and the greater the pounding frequency, the more pronounced the trend. Lastly, the concrete’s internal porosity increased and then decreased with the pounding length. This study obtained the control range of aggregate segregation rate and porosity through analysis, and established equations for the optimal vibration parameters and paving speed of sliding form concrete to guide the reasonable control of actual sliding form paving and vibration construction processes.