Design and analysis of impedance matching for a radial standing wave piezoelectric ultrasonic motor.

Impedance matching circuits are capable of tuning and wave filtering, which is beneficial to performance improvement of piezoelectric ultrasonic motors. At present, impedance matching for piezoelectric ultrasonic motors is usually realized through a series inductance, which has the problem of poor wave filtering effect. Different from the previous series inductance matching method for ultrasonic motors, a series inductance and capacitance matching method is proposed for a radial standing wave piezoelectric ultrasonic motor. The series capacitance is added to adjust the quality factor of the resonance tank so that a desired wave filtering effect can be obtained. The values of the series inductance and capacitance are derived based on the Butterworth-Van Dyke model of the piezoelectric ultrasonic motor. Simulations are conducted to verify the feasibility of the proposed matching method. Finally, the waveforms of voltages and currents as well as torque-speed curves of the motor are measured. The results validate the proposed matching method. In addition, the previous series inductance matching method is compared. The results show that the proposed series inductance and capacitance matching method not only achieves tuning function but also obtains a significantly improved wave filtering effect. Moreover, the torque-speed characteristics of the motor are also improved with the proposed matching method.

Antipyretic effects of Xiangqin Jiere granules on febrile young rats revealed by combining pharmacodynamics, metabolomics, network pharmacology, molecular biology experiments and molecular docking strategies.

Xiangqin Jiere granules (XQJRG) is a proprietary Chinese medicine treating children's colds and fevers, but its mechanism of action is unclear. The aim of this study was to explore the antipyretic mechanisms of XQJRG based on pharmacodynamics, non-targeted metabolomics, network pharmacology, molecular biology experiments, molecular docking, and molecular dynamics (MD) simulation. Firstly, the yeast-induced fever model was constructed in young rats to study antipyretic effect of XQJRG. Metabolomics and network pharmacology studies were performed to identify the key compounds, targets and pathways involved in the antipyretic of XQJRG. Subsequently, MetScape was used to jointly analyze targets from network pharmacology and metabolites from metabolomics. Finally, the key targets were validated by enzyme-linked immunosorbent assay (ELISA), and the affinity and stability of key ingredient and targets were evaluated by molecular docking and MD simulation. The animal experimental results showed that after XQJRG treatment, body temperature of febrile rats was significantly reduced, 13 metabolites were significantly modulated, and pathways of differential metabolite enrichment were mainly related to amino acid and lipid metabolism. Network pharmacology results indicated that quercetin and kaempferol were the key active components of XQJRG, TNF, AKT1, IL6, IL1B and PTGS2 were core targets. ELISA confirmed that XQJRG significantly reduced the plasma concentrations of IL-1ß, IL-6, and TNF-α, and the hypothalamic concentrations of COX-2 and PGE2. Molecular docking demonstrated that the binding energies of kaempferol to the core targets were all below -5.0 kcal/mol. MD simulation results showed that the binding free energies of TNF-kaempferol, IL6-kaempferol, IL1B-kaempferol and PTGS2-kaempferol were -87.86 kcal/mol, -70.41 kcal/mol, -69.95 kcal/mol and -106.67 kcal/mol, respectively. In conclusion, XQJRG has antipyretic effects on yeast-induced fever in young rats, and its antipyretic mechanisms may be related to the inhibition of peripheral pyrogenic cytokines release by constituents such as kaempferol, the reduction of hypothalamic fever mediator production, and the amelioration of disturbances in amino acid and lipid metabolism.Communicated by Ramaswamy H. Sarma.

Contact analysis and performance evaluation of ring type traveling wave ultrasonic motors based on a surface contact model.

A surface contact model of ring type traveling wave ultrasonic motors is proposed in this paper in order to describe the circular three-dimensional contact and friction problem between the stator and rotor accurately. Differing from previous contact models of traveling wave ultrasonic motors, the flexibility of the rotor, which results in the irregular shape of contact area and inhomogeneous distribution of contact pressure along radial direction, is taken into account in the proposed model. The normal contact between the stator and rotor is analyzed with finite element method and the tangential force transmission on the contact surface is investigated with analytical method. The contact pressures and the tangential stresses on the contact surface are obtained. Mechanical performances of the motor are also studied based upon the proposed model. Finally, torque-speed curves of a prototype motor are measured and compared with the calculated results of the proposed model, and good agreements are obtained. In addition, the proposed surface contact model is compared with previous line contact models. It is found that the calculated results of the surface contact model are closer to measured results than those of line contact models. The comparison results verify the accuracy of the proposed surface contact model.

Contact modeling and performance evaluation of ring type traveling wave ultrasonic motors considering stator teeth.

A contact model of ring type traveling wave ultrasonic motors is proposed in this paper in order to investigate the dynamic contact and friction drive mechanism between the stator and rotor. Differing from previous contact models of ring type traveling wave ultrasonic motors, the Dahl friction model is adopted and the stator teeth are taken into account in the proposed model. The normal stress, the tangential stress, and the torque-speed characteristics of the motor are evaluated in detail based on the proposed model. Finally, the torque-speed values of the prototype motor are measured and compared with the calculation ones. The results show that the calculation values are in good agreement with the experimental values, which validates the proposed model. Moreover, the proposed contact model is compared with previous contact models that adopt Coulomb friction law and meanwhile ignore stator teeth by assuming teeth surfaces to be continuous. The comparison results show that the proposed model is more accurate than previous models.

A single-modal linear ultrasonic motor based on multi vibration modes of PZT ceramics.

We have developed a single-modal linear motor which contains two kinds of PZT ceramics. The linear motor works by exciting the transverse vibration mode of the PZT ceramic on the upper surface of stator elastomer and the shear vibration mode of PZT ceramics at two ends simultaneously. The operation principle of the motor is analyzed in detail. And the rule of the driving foot amplitude varies with the size of the end protruding structure has been further researched by FEM analysis. The prototype is manufactured, and its operating characteristics are experimentally studied and analyzed. The no-load velocity and the maximum output force are tested to be 169.4 mm/s and 1.1 N, respectively. The results show that extra arrangement of PZT ceramics which works on shear vibration mode can efficiently improve the output of motor.

Inherent Loss Analysis of Piezoelectrics in Radial Vibration and its Application in Ultrasonic Motor.

High-efficiency energy conversion, primarily limited by internal losses of piezoelectric materials, is an important target for piezoelectric actuators or sensors. There are three internal losses in piezoelectric materials: dielectric, elastic, and piezoelectric. In this article, a new equivalent circuit of a piezoelectric ring in radial vibration mode is proposed considering three types of fundamental losses. First, the decoupled equivalent circuit with inherent losses is derived based on the conventional electromechanical equivalent circuit. In order to verify the feasibility of the new circuit, an ultrasonic motor operating in radial vibration mode is explored and simulated. The resonance and antiresonance frequencies and their corresponding mechanical quality factors are obtained from the new circuits and then compared with those of an actual stator sample. The simulation results match well with the experimental measurements of the stator. Finally, a prototype is fabricated due to the simulation results and a maximum torque of 270 mNm is acquired.

A standing wave ultrasonic stepping motor using open-loop control system.

We propose a standing wave ultrasonic stepping motor with blades and grooves for positioning. The step-by-step movements are achieved by applying the square wave driving voltage and the high-voltage pulse in turn. The prototype with a diameter of 30mm, a height of 10mm is experimentally characterized. The motor is superior to those previously reported due to the positioning mechanism for eliminating displacement cumulative error when using an open-loop control system. Also, the operating mode and the metal-to-metal friction drive ensure a stall torque of 0.055Nm under a relatively low operating voltage of 100Vpp at a resonance frequency of 74kHz.

H2-EB1 Molecule Alleviates Allergic Rhinitis Symptoms of H2-Eb1 Knockout Mice.

BACKGROUND: H2-EB1 molecule which is the homolog of Human HLA-DRB1 is proposed to be associated with allergic rhinitis (AR). Construction of H2-Eb1 knockout animal models provides a tool to elucidate the role of H2-EB1 and AR pathogenesis. OBJECTIVE: To establish the H2-Eb1 knockout model and investigate the H2-EB1 functions in H2-Eb1 knockout mice as a model of AR. METHODS: The Cre/LoxP system and ES gene knockout technology were applied to create heterozygous H2-Eb1 (+/-) knockout mice and their offspring of knockout homozygous(-/-), heterozygous (+/-) and wild type (+/+) H2-Eb1 mice. After identification, offspring of heterozygous (+/-) and homozygous (-/-) H2-Eb1 knockout mice were randomly selected to establish AR models to demonstrate the role of H2-Eb1 in AR pathogenesis. RESULTS: The H2-Eb1 knockout mice model was successfully established. The reproduction and feeding of the homozygous (-/-) H2-Eb1 knockout mice were successful. Compared with the control group, the serum OVA-IgE and IL-4 levels significantly increased, while IFN-γ levels significantly dropped (p<0.05) in the experimental groups. For the two experimental groups, the homozygous (-/-) mice group had lower serum OVA-IgE and IL-4 levels, and higher IFN-γ levels than their heterozygous (+/-) counterparts (p<0.05), concomitant with slighter allergic symptoms (gentle behavior and less eosinophils in nasal mucosa). CONCLUSION: Our study demonstrated that knockout of H2-Eb1 gene could alleviate mouse AR Symptoms, indicating H2-Eb1 may play an important role in regulating Th1/Th2 balance during the pathogenesis of AR.