Facile Synthesis of Ag-Doped Urchin-like MnO2 on Carbon Cloth for Supercapacitors.

Based on MnO2/carbon cloth (CC) composite materials, an Ag-doped MnO2 nanowire, self-assembled, urchin-like structure was synthesized in situ on the surface of CC using a simple method, and a novel and efficient flexible electrode material for supercapacitors was developed. The morphology, structure, elemental distribution, and pore distribution of the material were analyzed using SEM, TEM, XRD, XPS, and BET. The electrochemical performance was tested using cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD). In the three-electrode system, GCD testing showed that the specific capacitance of the material reached 520.8 F/g at 0.5 A/g. After 2000 cycles at a current density of 1 A/g, the capacitance retention rate was 90.6%, demonstrating its enormous potential in the application of supercapacitor electrode materials.

A Simplified Method for the Preparation of Highly Conductive and Flexible Silk Nanofibrils/MXene Membrane.

Silk nanofibers (SNF) have great applications in high-performance functional nanocomposites due to their excellent mechanical properties, biocompatibility, and degradability. However, the preparation of SNF by traditional methods often requires the use of some environmentally harmful or toxic reagents, limiting its application in green chemistry. In this paper, we successfully prepared SNF using natural silk as raw material and solvent stripping technology by adjusting the solvent concentration and solution ratio (the diameter of about 120 nm). Using the above SNFs as raw materials, SNF membranes were prepared by vacuum filtration technology. In addition, we prepared an SNF/MXene nanocomposite material with excellent humidity sensitivity by simply coating MXene nanosheets with silk fibers. The conductivity of the material can approach 1400.6 S m-1 with excellent mechanical strength (51.34 MPa). The SNF/MXene nanocomposite material with high mechanical properties, high conductivity, and green degradability can be potentially applied in the field of electromagnetic interference (EMI) shielding, providing a feasible approach for the development of functional nanocomposite materials.

Dynamic modeling and analysis of a bonded-type ultrasonic motor considering the load transfer in adhesive interlayer.

This paper proposes a dynamic numerical model for the bonded-type ultrasonic motor considering the load transfer in the adhesive interlayer between the piezoceramics and the host structure. The finite element method and an extended shear-lag theory are used to derive the dynamic equation. The effectiveness of this model is validated by comparing the dynamic response of the stator in frequency and time domains between simulation and experimental results, with a maximum relative error of less than 4%. The dynamic load transfer in the adhesive interlayer is analyzed when the stator is excited electrically, and the results show that the interfacial load transfer is concentrated near the bonding edges. The effects of partially bonded piezoceramics on the dynamic characteristics of the motor are investigated, where two partially bonded conditions including edge and inner debonded cases are considered. The results indicate that both the inner and edge debonded conditions could reduce the vibration amplitude of the stator and then reduce the output performance of the motor.

Modeling and verification of life prediction of a V-shaped linear ultrasonic motor.

In this paper, a wear model is established for a V-shaped linear ultrasonic motor. The influence of the change in the dynamic friction coefficient and the roughness parameters of the contact surface of the stator/slider on the output performance of the motor is considered in this model. The wear mechanism of the motor and the variation rules of the morphology of the contact surface during the operation of the motor are studied, as well as the relation of the wear height of the driving tip with the preload force and the relation of the preload force with the resonance frequency of the stator. The accuracy of the model is verified by numerical simulation and experimental methods. A test platform for friction and wear experiments is constructed, and the wear characteristics and the output performance of the motor are tested. The obtained results indicated that the model can accurately predict the dynamic changes during the wear process and the service life and output performance of the motor.

Three-core fiber Bragg grating probe force estimation model for micromanipulation applications.

This paper proposed a three-core fiber Bragg grating (FBG) probe for sub-millinewton contact force measurement of a micromanipulator system. The probe comprises a bundle of three single-core FBGs assembled under the effect of capillary self-assembly. Theoretical relationships between Bragg wavelength and force are calculated based on the assumption of material mechanics. The experimental results show that the probe has a good linear relationship for the measurement of the radial two degrees of freedom contact force, and it is suitable for measuring the radial contact force of 0.1-1 mN. The proposed three-core FBG probe has the characteristics of simple structure, low cost, and better forming stability and sensitivity compared with the four-core structure.

Theoretical analysis and experimental investigation on a linear ultrasonic motor with a compact slider.

A compact slider for linear ultrasonic motors (LUMs) to improve the ability of LUMs for precision positioning is proposed in this article. The compact slider can avoid the effect of variable stiffness of the traditional slider on ultra-precision positioning, which consists of two pieces of ceramic with little lubricating oil on the sliding interface. Based on contact theory and lubrication theory, the contact mechanism and the lubricating state between the slider and the support plate are analyzed. Subsequently, a dynamic model for LUMs considering the lubricating state and the ultrasonic vibration condition is obtained. Furthermore, the output speed and output force of the motor are analyzed under the influence of film lubrication. Moreover, some experiments are designed to test the feasibility and effectiveness of the compact slider for precision positioning. The results indicate that the compact slider is more effective in inhibiting the fluctuation of the output speed compared to the traditional slider, and it can improve the displacement resolution of LUMs up to 7 nm.