Piezoelectric Glass-Fiber-Reinforced Polymer Sensor for Structural Health Monitoring and Stiffness Sensing

Strengthening and repairing infrastructure with fiber-reinforced polymers while achieving low-cost, real-time monitoring of cracks in engineering structures is highly challenging. Herein, a piezoelectric glass-fiber-reinforced polymer (piezo-GFRP) sensor is used to monitor the mechanical behavior of cement beams with cracks under cyclic bending. The output voltage and frequency of the sensor are shown to be effective feedback signals for determining the mechanical behavior. The thin piezo-GFRP sensor shows sufficient piezoelectric sensitivity to monitor the slight variations in the mechanical behavior of the cement beams during the early stages of cracking. It is indicated in this result that such sensors have the potential for the multifunctional structural health monitoring of engineering structures.     

Pretreatment with fine bubbles for effective zinc ion precipitation and removal from zinc electroplating wastewater

Heavy metals such as zinc are widely used in plating plants for the processing of material surfaces; therefore, an adequate wastewater treatment is required afterwards to comply with wastewater regulations. However, the presence of chemicals such as degreasing agents in the wastewater generated from the plating process inhibits the formation of hydroxides, thereby making treatment of wastewater and compliance with the stipulated regulations difficult. Herein, the effects of fine bubbles on oil cleaning and wastewater treatment were investigated for developing an alternative cleaning technology to degreasing agents. The concentration of fine bubbles significantly affected the oil cleaning. The fine bubbles demonstrated remarkable cleaning of highly viscous oil, which was difficult to remove using pure water. The high cleaning effect of fine bubbles on oil was achieved because of the hydrophobic interaction of the bubbles. Furthermore, a decrease in cleaning effect was observed for samples with uneven shapes, which was attributed to the difficulty in penetration of fine bubbles in materials with irregularities. Furthermore, fine bubble cleaning exhibited better efficiency for wastewater treatment than degreaser cleaning. Therefore, fine bubble cleaning is speculated to be an excellent cleaning technology with high oil cleaning effectiveness and improved wastewater treatability.