Phase change materials are widely used in our lives, and it is of great practical significance to learn and study the thermal properties of phase change. However, at present, most of the calorimetric devices on the market to measure the thermal properties of phase change materials are carried out in the sealed interval, and students cannot observe the complete phase change process. At the same time, it is rarely covered in teaching experiments because the instrumentation is too expensive and complex. In this paper, the relationship between the latent heat of phase change and temperature difference curves of phase change materials and the peak area enclosed by the baseline is obtained through theoretical derivation, and a simple open calorimetric device is constructed. The device uses the Peltier plate as the heat source, measures the temperature using the thermoelectric effect of the semiconductor zinc oxide film, and completely records the temperature change of the phase transition process through the data acquisition card and the LABVIEW program. In this paper, gallium metal was used as a sample, and the parameters h_T=0.52(J/(K·S)) and the latent heat of phase change of 10 groups of gallium metal of different masses between 0.206~0.692g were calibrated. The device has simple structure and convenient operation, which can provide technical reference for studying the thermal properties of phase change materials and university physics experiments.

Plane phased array technology is a method of arranging multiple transducers on a circuit board in the form of matrix, and independently controlling each transducer to emit sound waves by adjusting input signals to achieve acoustic suspension. It is a kind of standing wave method. In this paper, based on the basic theory of acoustics, the expression of the acoustic radiation potential is presented for all planar phased array elements with the same phase. Through MATLAB and COMSOL simulation, the possible suspended points in the space are given, and it is found that the arrangement of suspended points presents periodicity. The principle of realizing three-dimensional movement is explained by studying the width property of the suspended potential well. Finally, the reliability of the theory and simulation is verified by experiments.