Detection of water-ice transition using a lead zirconate titanate/brass transducer

Abstract

We have examined experimentally and theoretically the resonance frequency of a lead zirconate titanate ͑PZT͒/brass unimorph disk transducer with a water ͑ice͒ layer on the brass surface. We showed that the flexural resonance frequency decreased with the presence of a water layer and the decrease in resonance frequency increased with an increasing water amount. Upon lowering the temperature, the freezing transition of the deposited water layer was detected when the resonance frequency of the transducer increased abruptly at the freezing temperature. In contrast to water, an ice layer increased the resonance frequency and the increase in the resonance frequency increased with the ice layer thickness. Theoretically, an analytic expression for the flexural resonance frequency of a unimorph transducer in the presence of an ice ͑water͒ layer on the brass surface was obtained in terms of the Young's moduli, densities, and thickness of the PZT, brass, and ice ͑water͒ layers. The theoretical predictions were shown to agree with the experimental results.

New insight into the kinetic behavior of the structural formation process in agar gelation

“…In the present study, the kinetic behavior of the structural formation process in the agar-water gel system during natural cooling from ~80 o C to room temperature was investigated by a time-resolved measurement based on our custom built torsion resonator. We find that the agar sol-gel transition during natural cooling is a gradual and complicated process, quite different from the nucleation and crystallization of the typical water-ice transition[29e, [32][33] accompanied by abrupt changes in temperature and response strain (or tgφ). From the time (or temperature) evolution of SDR, the agar natural-cooling gelation process can be clearly divided into three stages: the sol stage (Stage I), gelation zone (Stage II) and gel stage (Stage III).…”

“…Based on Fig.2a and 2b, it is clear that both the measured temperature (T) of the gelling agar-water sample and the response strain (γ) of the oscillating cup (inserted into the measured agar solution under the constant applied-stress torque τ=193μNm) decrease gradually and continuously with increasing time during the gelation process. Such gradual and continuous decreases of the temperature and the response strain are distinctly different from the time-dependent temperature and strain behavior in the freezing process of water[29e, [32][33]. The water-to-ice freezing process usually shows an abrupt change at the freezing point, representative of a typical first-order phase transition or a nucleation and crystallization process [32][33].…”

“…Such gradual and continuous decreases of the temperature and the response strain are distinctly different from the time-dependent temperature and strain behavior in the freezing process of water[29e, [32][33]. The water-to-ice freezing process usually shows an abrupt change at the freezing point, representative of a typical first-order phase transition or a nucleation and crystallization process [32][33].…”

Numerical and experimental study on icing detection of wind turbine blade based on ultrasonic guided wave

“…光纤式结冰传感器探头尺寸小, 灵敏度高, 便 于安装, 但是对水、油污、灰尘的干扰较为敏感. 平 膜式结冰传感器 [6] 可以采用内埋式安装, 安装方便且 精度较高, 能区分冰和水及其他附着物, 缺点是需要 温度补偿, 最大可测冰厚度较小.…”

The piezoelectric road status sensor using the frequency scanning method and machine-learning algorithms

“…Ice sensors have been developed based on different kinds of physical principles, e.g., infrared or laser imaging [5]- [7], fiber optics [8], [9], resonance frequency [10]- [12], ultrasound [13], [14], conductivity [15], [16], capacitance effects [17], [18] and electromagnetic waves [19], [20]. These sensors are applied to meet specific needs in different fields.…”