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Abstract Titanium alloy with high corrosion resistance, high strength-to-density ratio, and excellent biocompatibility has a wide range of applications in the field of biomedical implants. Polishing experiments of titanium alloy with a small size and complex shapes were investigated using an ultrasonic assisted magnetorheological finishing (UMRF) device excited by a three-pole magnetic field generator. The models of the normal force and the shear force were first proposed based on the Preston equation to analyze the mechanism of material removal in the UMRF process. Subsequently, the single-factor experiments using titanium alloy nuts (M3) and the MR polishing fluid with silicon carbide abrasives were carried out. Furthermore, to improve the surface roughness and the change rate of surface roughness of nuts, orthogonal tests with a standard L9(34) orthogonal array were designed and performed based on the optimized process parameters obtained from the single-factor experiment. The results indicated the effect on surface roughness and change rate of surface roughness as applied current > roller speed > ultrasonic amplitude > spindle speed and applied current > roller speed > spindle speed > ultrasonic amplitude, respectively. Moreover, the surface roughness was improved from an initial 1.247 μm to a final 0.104 μm after the polishing for 80 min under these optimal process parameters.

Low productivity and high electricity consumption are considered problems of the hammer mill, which is widely used in current feed production. In this paper, a folded V-shaped hammer was designed to improve the performance of the hammer mill. To determine the optimal design parameters of the new hammer, the single-factor test and orthogonal tests were carried out with the inclination angle of hammer, the angle of hammer head, and the distance of hammer head as the influencing factors, and the productivity and output per kWh as evaluation indexes. The order of the influence on the productivity and output per kWh were the inclination angle of hammer>the angle of hammer head> the distance of hammer head. The parameters were optimized based on the orthogonal tests with the following results: the angle of hammer head was 160°, inclination angle of hammer was 110°, and the inclination distance of hammer head was 24 mm. The static analysis and modal analysis were carried out on the optimized hammer by using ANSYS software. The results showed that the new hammer satisfies the strength and stiffness requirements during working, does not resonate, and has good dynamic characteristics. The new hammer can effectively improve the performance of the hammer mill, and the research results can provide theoretical basis for the optimization design of the hammer mill. [ABSTRACT FROM AUTHOR]

Titanium alloy with high corrosion resistance, high strength-to-density ratio, and excellent biocompatibility has a wide range of applications in the field of biomedical implants. Polishing experiments of titanium alloy with a small size and complex shapes were investigated using an ultrasonic assisted magnetorheological finishing (UMRF) device excited by a three-pole magnetic field generator. The models of the normal force and the shear force were first proposed based on the Preston equation to analyze the mechanism of material removal in the UMRF process. Subsequently, the single-factor experiments using titanium alloy nuts (M3) and the MR polishing fluid with silicon carbide abrasives were carried out. Furthermore, to improve the surface roughness and the change rate of surface roughness of nuts, orthogonal tests with a standard L9(34) orthogonal array were designed and performed based on the optimized process parameters obtained from the single-factor experiment. The results indicated the effect on surface roughness and change rate of surface roughness as applied current > roller speed > ultrasonic amplitude > spindle speed and applied current > roller speed > spindle speed > ultrasonic amplitude, respectively. Moreover, the surface roughness was improved from an initial 1.247 μm to a final 0.104 μm after the polishing for 80 min under these optimal process parameters. [ABSTRACT FROM AUTHOR]

The climbing of trees to pick pinecones is a high-risk exercise. In this study, a mechanical gripper jaw was designed. Frictional characteristics between the pinecones and the mechanical gripper jaw during pinecone picking under different conditions were investigated using a workbench simulation, homemade inclined friction meter, and mass tester. Three-level orthogonal and one-factor tests were conducted. The relationship between the water content and friction properties and between the water content and hardness were investigated, and conclusions were drawn on how water content affected friction properties by influencing hardness. The results showed that the contact material greatly affected the friction properties. The pinecone water content was maintained between 24% and 28% to ensure that the coefficient of friction was maximized and that the pinecones were sufficiently hard to dislodge. Additionally, a prototype machine was used to perform pinecone-gripping experiments to validate the experimental and simulation results. Consequently, the results of this study provide a useful reference for the structural design of pinecone picking robots and the picking reason. [ABSTRACT FROM AUTHOR]

In this study, the effects of coal blending ratio, pyrolysis temperature, pyrolysis atmosphere and coal particle size on the quality of pyrolyzed char were investigated via a combination of orthogonal experimental design and grey relational analysis. Coal-XG and Coal-LL were pyrolyzed under various conditions to produce chars which were characterized to ascertain their properties such as chemical structure and reactivity. The results indicated that the pyrolysis temperature has the most significant impact on the quality of the char, followed by the pyrolysis atmosphere, coal blending ratio and coal particle size. The increase in pyrolysis temperature not only diminished char yield but also accelerated the consumption of oxygen-containing functional groups and the polycondensation of small aromatic ring structures throughout the reaction process. This led to a reduction in the reactivity of pyrolyzed char and the establishment of a more ordered structure. Meanwhile, the involvement of CO 2 and H 2 O prevented the condensation of small aromatic rings and fostered the generation of additional oxygen-containing functional groups, which resulted in lower yield and higher reactivity of the char under these two atmospheres. Through systematic analysis, only the Raman characteristic parameter I (Gr+VL+Vr) /I D exhibited a strong positive linear correlation with char reactivity, making it a reliable indicator for characterizing the reactivity of char. • The orthogonal design was used to study four response factors. • GRA was used to find optimal conditions and impact ranking of different factors. • Linear regression was applied to relate Raman/FTIR parameters to reactivity. • Blend experiments were conducted with two coking coals. [ABSTRACT FROM AUTHOR]