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This research study focuses on the experimental analysis of the three-dimensional (3D) surface topography and surface roughness of the workpiece machined with ultrasonic vibration assisted turning (UAT) in comparison to conventional turning (CT). For the challenge that machining difficulties of 304 austenitic stainless steel (ASS 304) and high demands for the machined surface quality and machining precision represent, starting with cutting principle and processing technology, the ultrasonic vibration method is employed to scheme out a machining system of ultrasonic vibration assisted turning (MS-UAT). The experiments for turning the workpiece of ASS 304 are conducted with and without ultrasonic vibration using the designed MS-UAT, and then the 3D morphology evaluation parametersSaandSqare applied to characterize and analyse the machined surface. The experimental results obtained demonstrate that the process parameters in UAT of ASS 304 have obvious effect on the 3D surface topography and surface roughness of machined workpiece, and the appropriate choice of various process parameters, including ultrasonic amplitude, feed rate, depth of cut, and cutting speed, can enhance the machined surface quality efficiently to make the machining effect of UAT much better than that of CT.

The generation mechanism of cutting force in ultrasonic vibration assisted turning (UAT), with the composition and decomposition of cutting force is discussed in this paper, and the model of cutting force in UAT is established based on the mechanism of UAT. The force measuring test system is designed on the basis of the established machining system of UAT. The contrast experiments for turning the workpiece of 304 austenitic stainless steel are conducted with and without ultrasonic vibration under different technological parameters. Furthermore, the relational model and correlation between technological parameters and cutting force is obtained by regression analysis and variance analysis. Thereby, the mutual relation among these technological parameters is effectively controlled, which contributes to achieving the high quality and high efficient processing. Simultaneously, the influences of single technological parameter with the interaction between technological parameters on cutting force are researched and analyzed. The results prove that the cutting force is reduced significantly with the aid of ultrasonic vibration in turning and the choice of the proper ultrasonic amplitude, there is an optimal range of ultrasonic amplitudes as well. Meanwhile, the cutting parameters have great influence on cutting force, among which depth of cut has the superior influence, then the cutting speed, and feed rate has the minimal influence. Moreover, cutting parameters should not be too large, UAT is mainly used for semi-finishing or finishing at medium-low speed. UAT will get more ideal machining effect if cutting parameters are chosen properly.

A magnetic catalyst could be applied in a fluidized bed to improve the catalytic efficiency in the methanation and selective hydrogenation processes. Its distributions play an important role in accelerating the reactions. Electromagnetic tomography (EMT) provides an effective solution for online monitoring of the distribution of a magnetic catalyst. However, most of the EMT systems were developed to investigate the conductivity distribution. A novel EMT for the reconstruction of permeability distribution is presented in this paper. The coils, of which the sensitivity are related to frequency and coil size, were used as receivers in conventional EMT systems. In this paper, a tunneling magnetoresistance (TMR) sensor is applied to take the place of the coil. Compared with coils, the advantages of a TMR sensor on the frequency-independence and spatial resolution were investigated. A coil-TMR array was designed, in which the coil geometry was optimized and the TMR sensor was selected. The sensitivity matrix of the novel system was calculated by the perturbation method in a 3D simulation model. A FPGA-based system was designed. The reconstruction results of the magnetic catalyst validated the practicability of the permeability EMT based on TMR sensors.

The aim of this paper is to present an experimental investigation of the cutting forces, surface quality, tool wear and chip shape in ultrasonic vibration assisted turning (UAT) of 304 austenitic stainless steel (ASS 304) in comparison to conventional turning (CT). This study focuses on the solution of the machining difficulties of ASS 304 and high demands for the processing quality and efficiency. The machining system of UAT is schemed out to assure the desired machining effect by utilizing ultrasonic vibration method. Meanwhile, a series of systematic experiments are performed with and without ultrasonic vibration using the designed machining system of UAT with cemented carbide coated cutting tool. The results obtained from the UAT and CT experiments demonstrate that the cutting effect of UAT is much better than that of CT. Furthermore, the results of this research indicate that the ultrasonic amplitude, cutting speed, feed rate and depth of cut in UAT of ASS 304 have visible influence on the cutting forces, surface quality and tool wear. And reasonable selection of various technological variables in UAT can obtain lower cutting forces, more superior surface roughness, advantageous surface topography, slow and less tool wear, thin and smooth chips.