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The rationality of powertrain parameter design has a significant influence on the traction performance and economic performance of electric tractor. At present, researches on powertrain parameter design mainly focus on electric vehicles, and electric agricultural machinery draw much less attention. Therefore, a method of powertrain parameter matching and optimization design for electric tractor was proposed in this paper, which was based on dual-motor coupling drive mode. The particle swarm optimization (PSO) algorithm based on mixed penalty function was used to solve the optimization problems. Parameter optimization design was programmed using MATLAB. A simulation dynamic model with optimization design variables of electric tractor powertrain was established based on MATLAB/Simulink. Compared with the simulation results before optimization, the objective functions had got optimized and the traction performance of electric tractor had been improved, which indicated the effectiveness of the proposed method.

This study systematically evaluates the thermal performance of serpentine-channel cold plates in high-capacity Li-ion battery modules, focusing on geometric parameters (depth/width) and coolant flow rate. Through orthogonal experimental design coupled with STAR-CCM +  computational fluid dynamics simulations, we identify optimal cooling configurations. The results indicate that both the maximum temperature ( T max ) and the maximum temperature difference (Δ T min ) of the battery module have reached their minimum values with a Liquid-cooling plate channel depth of 3 mm, channel width of 28 mm, and coolant flow rate of 2.826 L/min, and when the coolant temperature is within the range of 16 °C to 26 °C, a linear reduction in the T max of 2 °C is observed for every 2 °C decrease in coolant temperature. The results demonstrate that precise channel geometry design with active coolant temperature adjustment can effectively mitigate thermal inhomogeneity in large-format battery systems.

The single-stage dual active bridge (DAB) AC-DC converter has the advantages of high power density, low cost, and simple control; it has a broad potential for application in the field of onboard chargers (OBC). However, the lack of fast and accurate quantitative parameter optimization design methods in single-stage DAB AC-DC converters limits the overall efficiency of the converter. Based on the above problem, in order to improve the overall operating efficiency of the converter by optimizing the parameter transformer ratio and power inductance, this paper proposes a parameter design method considering a multi-timescale strategy by combining the steady-state analysis model of the converter in the line cycle and switching cycle and step-by-step reducing its design space through the constraints on the parameters. The first step is to obtain a safe design space for the parameters under the converter’s transmitted power and current stress constraints. The second step obtains the optimization design space of the parameters under the optimization of conduction loss and switching loss of the converter. Finally, the optimal parameters are determined by the loss analysis model. The proposed parameter optimization method entirely takes into account the steady-state characteristics of the DAB AC-DC converter during the line cycle, and the step-by-step constraints greatly accelerate the parameter design process. In addition, the proposed parameter optimization design method applies to all types of single-stage DAB AC-DC converters, which can be well applied to engineering practice.

A hybrid type magneto-rheological (MR) fluid damper based on electromagnet and two permanent magnets apart from electromagnet was designed and its characteristics were analyzed numerically. In the proposed MR damper, the magnetic field is generated by the permanent magnet and raised by the additional electromagnet. This combination provides a larger amount of damping force with lower consumption of electric energy. The proposed model has an additional advantage of providing a moderate damping force in case of electromagnet failure. The magnetic circuit of a hybrid MR valve was analyzed by applying Kirchhoff’s law and magnetic flux conservation rule. A 2D axisymmetric model of the proposed hybrid MR damper was developed in commercial software where magnetic field properties are analyzed by finite element method. The optimization process was developed to optimize the geometric parameters and generated damping force using design of experiment (DoE) technique. The damping force of the MR damper was selected as an objective function. The optimal solution to the optimization problem of the hybrid MR valve structure was evaluated and compared with the solution obtained from the initial parameters. It is demonstrated that the novel hybrid type provides higher damping force than the previous model.

In this paper, the optimization method of missile overall parameters design based on surrogate model and the trajectory simulation system of three degree of freedom(3-DOF) dual pulse missile are established. An adaptive sampling point update method including three stages of potential feasible region location sampling, exploration sampling and potential optimal sampling is established. The adaptive sampling is realized through the constraint of distance. The convergence end criterion is established based on the accuracy of surrogate model, which can achieve efficient and reliable global optimization. By deriving the objective function of the optimization problem, the minimum take-off mass is determined, and reasonable constraints are set to ensure the speed and range requirements of the missile. The optimization algorithm based on surrogate model solves the problem of overall parameter design optimization of dual pulse missile and summarizes it.

The optimization design of the face gear split-torque transmission (FGST) consumes a lot of modeling and calculation costs. Implementing closed-loop design for data generation optimization improves system design efficiency. However, there are two challenges: firstly, the lack of a mapping method for the tooth surface modification parameters to discrete mesh coordinates, which makes it difficult to generate data samples; secondly, a quantitative representation method for evaluating contact performance has not been proposed, making it difficult to achieve quantitative design. In this paper, we propose a fast integration method of analysis and optimization to the contact performance design of a face gear split-torque transmission. An efficient mapping method from FGST geometric parameters to discrete grids is established to achieve fast data generation. A quantitative evaluation method for contact performance based on image processing has been proposed to achieve rapid optimization. The time required for modeling and optimization is shortened to less than 0.5 h, significantly improving design efficiency.

In order to improve the properties of calcium sulfate anhydrous whisker (ACSW) and polyester fiber composite reinforced asphalt mixture (ACPRA) to meet the service requirements of pavement materials in low-temperature environments, the central composite circumscribed design (CCC), a kind of response surface methodology, was chosen to optimize the design parameters. Three independence variables, asphalt aggregate ratio, ACSW content, and polyester fiber content were adopted to evaluate the design parameters. Four responsive variables, air voids, Marshall stability, splitting tensile strength, and failure tensile strain, were chosen to study the volumetric and mechanical characteristics, and the low-temperature behavior of ACPRA by the Marshall test and indirect tensile test at −10 °C. The results showed that, taking low-temperature behavior optimization as the objective, the CCC method was practicable to optimize design of ACPRA, and the optimization design parameters were asphalt aggregate ratio of 4.0%, ACSW content of 10.8%, and polyester fiber content of 0.4%. Furthermore, the impact of three independence variables interactions on four response variables was also discussed, and it was identified that the interaction between asphalt aggregate ratio and ACSW content, and between asphalt aggregate ratio and polyester fiber content, has greater bearing on the splitting tensile strength and failure tensile strain of APCRA. Meanwhile, ACSW and polyester fiber enhancing the low-temperature behavior of APCRA was primarily connected with their contents.

To meet the demand for constant current and constant voltage charging of batteries and to increase the system output power, the LCC-LCL/S-type self-switching wireless power transfer system is proposed. The system does not require communication between the primary and secondary circuits, and its output mode is controlled by simply changing the status of two switches on the secondary side. Notably, the system satisfies the zero phase angle characteristic before and after mode switching. The parameter design method is proposed based on the circuit topology and the maximum safe current constraint. To make the output voltage fluctuation as small as possible, the optimum load switching point for the system has been designed, and its optimality has been validated by simulation. Furthermore, the switching control strategy is proposed, considering the effects of the system no-load and load short-circuit in real situations. Finally, an experimental platform was built to achieve the high efficiency output of the system with the maximum output voltage of 46.21 V, the maximum output power of 180 W, and the maximum efficiency of 93.4%, which verified the applicability of the proposed method.

The variable valve mechanism, as a critical component for the efficient and low-carbon development of internal combustion engines, faces increasingly stringent requirements regarding its driving efficiency, output force, precision, and energy consumption. To address the limitations of existing technologies, a new composite electromagnetic valve train is proposed, characterized by a high force-to-power ratio, fast response, and high precision, along with a unique single/double drive mode, which offers greater flexibility in controlling valve timing parameters; however, it also introduces complex coupling relationships and increases the difficulty of optimization design. To this end, this paper establishes a thermodynamic model of the engine based on the composite electromagnetic valve mechanism. First, it analyzes the effects of different valve timing parameters and drive modes on engine performance; second, a multi-objective game theory optimization algorithm is employed to optimize the valve timing parameters and obtain the optimal solution set; finally, taking into account the energy consumption of the valve mechanism, engine emissions, and performance, a control strategy for valve timing parameters is developed based on an entropy-weighted method combined with a superiority and inferiority solution distance analysis. The results indicated that, under all the operating conditions of the engine, the average torque increased by 2.56%, the effective fuel consumption rate decreased by 6.23%, and nitrogen oxide emissions reduced by 9.86%. Meanwhile, an efficient and economical operational mode for the variable valve mechanism was obtained, providing new insights for the development of variable valve timing technology.

To deal with the problem of the difficult optimization search and expensive computational cost caused by large-scale design variables, the hierarchical optimization design system based on the global sensitivity analysis method is established in this paper. The M-OAT method is used to analyze the global sensitivity of the design variables, according to the sensitivity information to layer design variables, then optimize the design variables in each hierarchy. Through the study of the hierarchical optimization design of airfoils and wings, compared with the normal parameter optimization design system, the hierarchical optimization design system based on the global sensitivity analysis method can reduce effectively the number of design variables in a single optimization, reduce the difficulty of the optimization search, improve the convergence speed of the optimization, gain better optimization results at the same time. For optimization design with large-scale design variables, the hierarchical optimization design system based on the global sensitivity analysis method is a sort of effective ways of design. 针对气动设计中遇到的具有大规模设计变量的优化设计工程，造成优化搜索难度大，计算代价高等问题，提出了一种基于全局灵敏度分析方法的分层优化设计方法。即选取M-OAT方法对设计变量进行全局灵敏度分析，根据灵敏度信息对设计变量进行分层，随后分别对各层设计变量进行优化。对翼型及机翼进行分层优化设计之后，与普通全参数优化设计系统相比，建立的分层优化系统可以在单次优化过程中有效减小设计变量的数目，减小优化搜索的难度，加快优化收敛速度，同时也能获得较好的优化结果。