Milk tea beverage is a drink widely loved by consumers. The astringency caused by the rich tea polyphenols in the tea soup is one of the key factors affecting the sensory quality of milk tea beverage. Existing research has shown that milk components, such as milk proteins, can reduce astringency. Milk fat, an important component in cow's milk, is composed of milk fat globules. However, the effect of its content and structure on astringency in milk tea systems remained unclear. It was aimed to investigate the impact of milk fat content and fat globule structure on astringency in milk tea systems. Firstly, it used descriptive sensory evaluation to explore whether milk fat and fat content affected the astringency of milk tea system. Next, three types of milk fat droplets with the same fat content but different structural characteristics were constructed by adjusting the heating intensity and homogenization pressure: milk fat droplet C, milk fat droplet T and milk fat droplet H, and the particle size,ζ-potential, microscopic structure, milk fat globule membrane protein content and composition, and milk fat globule membrane phospholipid content were measured, which characterized the characteristics of milk fat globules. Then different milk fat droplets were added to the simulated milk tea system to conduct sensory evaluation of astringency intensity, and quantify astringency through fluorescence spectroscopy analysis. The results showed that when the milk fat content reached above 4 g/(100 mL), the addition of milk fat can significantly reduce the astringency level in milk tea. In addition, changing the particle size and membrane structure of milk fat globules also had a significant impact on the astringency of the milk tea system. Compared with the other two milk fat droplets, the fat globule size in milk fat droplet H was the smallest (0.49 μm), the protein content per gram fat globule membrane was the highest (12.60 mg), and the astringency was the weakest. Milk fat droplet T had the largest particle size (4.20 μm), the lowest protein content per gram fat globule membrane (4.12 mg), and a strong astringency. Therefore, milk fat content, particle size and membrane structure would affect the astringency intensity of milk tea system. Smaller milk fat globule size and more milk fat globule membrane interface proteins had the greatest effect on reducing the astringency intensity of milk tea system. It was confirmed the impact of milk fat on the perception of astringency in the milk tea system, laying a theoretical foundation for the development of green and healthy milk tea drinks with a smoother taste.

In response to the problems of steep slopes and narrow roads, complex terrain and landforms, poor applicability of existing models on sloping land, and lack of design theory for mountain power machinery in hilly and mountainous areas, this paper proposes a “lateral swing longitudinal shift” center of gravity adjustment crawler tractor scheme suitable for hilly and mountainous areas. In order to reduce research and development costs and shorten the research and development cycle, a “lateral swing longitudinal shift” center of gravity adjustable remote control crawler proportional prototype is specially created for feasibility verification and slope stability research of the scheme. A mathematical model and force analysis were conducted for slope driving before and after adjusting the center of gravity, and a stability index that considers both lateral and longitudinal directions-the uniform distribution coefficient of track contact pressure-was proposed. Grounding pressure and passability tests were conducted, and the results showed that the “lateral swing longitudinal shift” center of gravity adjustable scheme proposed in this paper can greatly improve the uniformity of grounding pressure distribution for two tracks traveling on slopes; Under the slope conditions of 5°, 10°, 15°, and 20°, after adjusting the center of gravity of the whole machine longitudinally and laterally, the maximum traction force of the vehicle when inclined 45° uphill is 398.70 N, 339.41 N, 265.67 N, and 222.32 N, respectively. The maximum traction force has increased by 13.9%, 18.1%, 27.3%, and 50.5% compared to before regulation. A maximum rollover test was conducted, and the results showed that when the longitudinal distance of the upper body extended to a maximum of 150 mm, the static longitudinal maximum rollover angle increased from 39° to 46°, an increase of 17.9% compared to before the center of gravity adjustment; When the upper body sway angle is adjusted to the maximum value of 25°, the static lateral limit tilt angle is increased from 40.0° to 43.5°, an increase of 8.8% compared to before regulation; When passing obstacles on a slope, adjusting the horizontal or vertical center of gravity will increase the dynamic tipping coefficient of the vehicle on the slope, and the lifting effect will weaken with the increase of slope. Prove that the proposed solution is feasible and can significantly improve the driving stability and anti rollover ability of tracked vehicles on slopes, providing theoretical and data support for performance analysis and structural optimization design of tracked vehicles.

The design parameters of the transmission directly affect the dynamics and fuel economy of the vehicle, due to the complexity of the tractor's working conditions and a variety of operating modes, so in the optimization of the design parameters of the tractor transmission cannot be directly borrowed from the automobile based on the optimization of the standard cycle of working conditions. An independently designed hydro-mechanical continuously variable transmission (HMCVT) was taken as the research object, and a transmission design parameter optimization method based on the whole life cycle speed usage rate of the tractor was proposed, and a multi-objective genetic algorithm (MOGA) was used for optimization and solution. Fuel consumption rate and climbing ability were used as the optimization objective functions, and parameters significantly affecting the optimization objectives were selected as design variables. Constraints were determined, and a multi-objective optimization model for the transmission device was established by using modeFrontier, combining MOGA based on Pareto optimal principles and experimental design, to perform a global search for optimization, resulting in Pareto optimal solutions. The research results obtained the optimal solutions under the constraints, reflecting the contradictory characteristics between dynamic performance and fuel economy. The design variables of the Pareto optimal solutions obtained through optimization iterations well met the matching requirements of the transmission device.

A multi-mode mobile parallel mechanism with over constrained branch chains was designed, and its degrees of freedom and kinematics were deeply analyzed. When exploring the motion of the parallel mechanism, the influence of the over constrained branch chain on its motion stability was studied, and the motion simulation and physical production were carried out to verify the motion of the mechanism and the realization of each mode. Firstly, according to the analysis of the connection between the constrained branch chain and the platform branch chain, a multi-mode mobile parallel mechanism with constrained branch chain was obtained according to its configuration design. The degree of freedom of the two modes of the mechanism, quadrilateral rolling mode and spherical rolling mode, was analyzed by means of the bar group model. The comparative analysis of the mechanism with or without over constrained branch chains was carried out, the centroid coordinates were solved according to ZMP theory, the relationship between the mechanism with or without over constrained branch chains and the angle was compared and analyzed, and Matlab was used to carry out comparative analysis of the centroid situation of the mechanism with motion. Finally, the kinematic simulation of the mechanism was carried out by ADAMS, and the prototype was made to verify the movement of the mechanism and the realization of each mode.

A novel structure model of 2-RRC/1-RRS parallel manipulator mechanism was proposed for the screening of agricultural materials, and its kinematics and dynamic characteristics were studied. Firstly, based on the motion characteristics of each branch chain in the 2-RRC/1-RRS parallel manipulator mechanism, the manipulator structure characteristics and the coupling relationship between the motion variables were analyzed. Secondly, the kinematics of the 2-RRC/1-RRS parallel mechanism was deduced, and the analytical expression of the inverse kinematics of the robot was given. Then based on the discussion of kinetic energy and potential energy of the 2-RRC/1-RRS parallel manipulator, the dynamic equation of the manipulator was derived by Lagrange equation method of classical mechanics. Finally, the dynamic characteristics of the 2-RRC/1-RRS parallel manipulator mechanism, such as motion parameters, driving torque and energy consumption, were discussed by an example. The results showed that the parameters of moment of inertia in the dynamics equation of the 2-RRC/1-RRS parallel manipulator system were closely related to the structure size of the manipulator, the mass size and mass distribution of each component, and the motion configuration of the manipulator, so as to determine the kinematics and dynamics characteristics of the 2-RRC/1-RRS parallel manipulator. The research content was of great significance to deeply understand the kinematics and dynamic characteristics of 2-RRC/1-RRS parallel manipulator, as well as the structural optimization design and the high-precision control of the manipulator, which can provide an idea for the innovative design of new equipment for agricultural material screening.