The power ultrasonic generator (PUG) is the core device of power ultrasonic technology (PUT), and its performance determines the application of this technology in biomedicine, semiconductor, aerospace, and other fields. With the high demand for sensitive and accurate dynamic response in power ultrasonic applications, the design of PUG has become a hot topic in academic and industry. However, the previous reviews cannot be used as a universal technical manual for industrial applications. There are many technical difficulties in establishing a mature production system, which hinder the large-scale application of PUG for piezoelectric transducers. To enhance the performance of the dynamic matching and power control of PUG, the studies in various PUT applications have been reviewed in this article. Initially, the demand design covering the piezoelectric transducer application and parameter requirements for ultrasonic and electrical signals is overall summarized, and these parameter requirements have been recommended as the technical indicators of developing the new PUG. Then the factors affecting the power conversion circuit design are analyzed systematically to realize the foundational performance improvement of PUG. Furthermore, advantages and limitations of key control technologies have been summarized to provide some different ideas on how to realize automatic resonance tracking and adaptive power adjustment, and to optimize the power control and dynamic matching control. Finally, several research directions of PUG in the future have been prospected.

To study the influence of different processing parameters on the porosity and dynamic resistance of cigarettes and their impact on cigarette smoking smoothness (CSS), an improved microfocus x-ray CT method was used to scan the porosity characterization of cigarettes. The axial stability and distribution consistency of dynamic resistance were characterized by the standard deviation of dynamic resistance between cigarettes. A cigarette-smoking smoothness evaluation method was established. The effects of different processing parameters on CSS and the correlation between porosity, dynamic resistance, and CSS were investigated. The experimental results indicate that, first, variations in cut width, steam temperature, and flow rate of the high-speed drying tower (HDT) leaf silk drying, as well as changes in the splitting knife arc length and groove depth, significantly influence cigarette porosity, its distribution uniformity, axial stability of dynamic draw resistance, and inter-cigarette consistency, with each factor exhibiting distinct impact trends. Second, cigarette drawability deteriorates markedly with increased cut width, while it improves significantly with elevated HDT steam temperature and reduced steam flow rate. Finally, under different processing parameters, both the uniformity of cigarette porosity distribution and dynamic draw resistance exert highly significant influences on cigarette drawability. The research results of this study have significant guiding significance for improving the quality of cigarettes.