Stepped-plate ultrasonic transducer used as a source of harmonic radiation force optimized by genetic algorithm

Exploring the coupled vibration behavior of Cylindrical-Conical and Cylindrical-Exponential ultrasonic concentrators for efficient energy transfer

In this paper, the coupled vibration behavior of cylindrical-conical and cylindrical-exponential ultrasonic concentrators for efficient energy transfer is investigated. A theoretical model is developed to overcome the limitations of traditional one-dimensional theories that neglect the influence of height in the study of cylindrical concentrator vibration. Employing the equivalent elasticity method, the coupled vibration is considered as an interaction between longitudinal and plane radial vibrations. By establishing radial and longitudinal equivalent circuits with their corresponding input impedances, resonance frequency equations and the radial displacement amplification factor are derived. The effects of the radial thickness and the height-to-radius ratio on the characteristic parameters are presented for optimization designs. Numerical simulations are conducted to analyze vibrational modes and validate the theoretical findings. This study enhances the understanding of the vibration mechanism of cylindrical concentrators and provides valuable insights for selecting suitable cross-sections to improve performance and effectiveness in practical applications.

An improved analytic model for designing the polymer-composite stepped-plate transducer using the modified Mindlin plate theory

A stepped-plate transducer (SPT) uses an extensive radiating plate to produce highly-directional ultrasound beams. In this paper, we present an improved analytical model for designing the polymer-composite stepped-plate transducer (PCSPT). The polymer-composite features the lightweight and flexible properties, and there can be little change in the resonant frequency and mode shape when the steps are attached. With the outstanding merit, it is feasible to construct SPTs with polymer-composite steps without taking the steps into consideration. The modified Mindlin plate theory (MMPT) is applied to improve the accuracy in the equivalent circuit model (ECM) that is used to predict the high-frequency vibratory responses. Our analytical model can be used to design well-tuned SPTs to achieve the desired dynamic responses such as resonant frequencies, mode shape and bandwidth for various high-power ultrasonic applications. We use several numerical design examples to illustrate that the design of the transducer can be accomplished without analyzing the sophisticated stepped-plate's behavior. We also perform a series of experiments to verify that the PCSPT is capable of functioning as a high-power ultrasonic transducer.

Influence of Percutaneous Drainage Surgery and the Interval to Perform Laparoscopic Cholecystectomy on Acute Cholecystitis through Genetic Algorithm-Based Contrast-Enhanced Ultrasound Imaging

To discuss the optimal interval time between genetic algorithm-based ultrasound imaging-guided percutaneous drainage surgery (PTGD) and laparoscopic cholecystectomy (LC), 64 cholecystitis patients were selected as the research objects and evenly divided into experimental group (intelligent algorithm was adopted to recognize patients’ ultrasonic images) and control group (professional doctors carried out diagnosis). 92 acute cholecystitis patients undergoing PTGD were divided into three groups. 30 out of the 92 patients received LC within 2 months and were defined as the early group. 32 were performed with LC within 2 to 4 months and were defined as the metaphase group. 28 underwent LC over 4 months and were defined as the late-stage group. The average operation time, the transition from LC to laparotomy, the average postoperative hospital stay, and the incidence of complications of the three groups were compared. The results revealed that the comparison of the diagnostic accuracy and comprehensive effectiveness between experimental group and control group demonstrated that the differences were statistically significant ( $P<0.05$ ). When the optimal interval of implementing LC after PTGD was realized, the corresponding values of the early group were 88.5 minutes, 16.67%, 8.13 days, and 13.75%. Those of the metaphase group were 49.91 minutes, 3.13%, 4.97 days, and 9.52%. Those of the late stage group were 68.78 minutes, 10.71%, 7.09 days, and 11.96%. To sum up, the diagnostic accuracy and comprehensive effectiveness of intelligent algorithm were higher than those of conventional ultrasound, and the optimal interval time of implementing LC after PTGD was 2 to 4 months.

Study on multi-frequency characteristics of a longitudinal ultrasonic transducer with stepped horn

In power ultrasonic and underwater acoustic fields, the ultrasonic treatment efficiency of vibration system can be improved significantly when vibration system is driven by the multi-frequency longitudinal transducer, and the performance of vibration system is determined by the multi-frequency characteristics of transducer. In this paper, using electromechanical equivalent circuit method, the multi-frequency characteristics of a longitudinal ultrasonic transducer with a stepped horn are studied for the ultrasonic vibration system optimal design. The expressions of the input impedance and the velocity amplification ratio of the transducer are obtained. The relationships between the electromechanical coupling coefficients, the velocity amplification of the multi-frequency transducer and the excitation position of the piezoelectric stack, the size of the stepped horn are analyzed. Combined with the finite element analysis of the transducer's key performance, the optimal design parameters of the multi-frequency transducer are given. Finally, the electromechanical properties of the multi-frequency transducer are tested experimentally, the theoretical analysis and finite element results are verified well.