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In order to improve the speed stability of tractors equipped with hydro-mechanical continuously variable transmission (HMCVT) during field operations, the speed regulation characteristics, torque characteristics, and power diversion characteristics of HMCVT are analyzed. And a comprehensive control strategy for HMCVT output speed is proposed by analyzing the factors affecting the fluctuation of output speed, which combines engine speed control and displacement ratio control of hydraulic speed control system. This strategy adopts fuzzy control to regulate the engine speed to maintain the stability of engine operation. Moreover, adopting feed forward compensation control for speed compensation enhances the anti-interference ability of the hydraulic speed control system. And combined with model predictive control, adjust the swash plate swing angle of the variable pump to reduce the fluctuation of HMCVT output speed. By establishing joint simulation model, the effectiveness of the control strategy was verified using tractor acceleration mode and step load disturbance mode. The results show that the strategy can reduce the fluctuation rate of engine speed and impact degree, shorten the adjustment time, and improve the stability of tractor operating speed. [ABSTRACT FROM AUTHOR]

To further improve the fuel economy of hybrid tractors, an energy management strategy based on model predictive control (MPC) solved by dynamic programming (DP) is proposed, taking into account the various typical operating conditions of tractors. A coupled dynamics model was constructed for a series diesel–electric hybrid tractor under three typical working conditions: plowing, rotary tillage, and transportation. Using DP to solve for the globally optimal SOC change trajectory under each operating condition of the tractor as the SOC constraint for MPC, we designed an energy management strategy based on DP-MPC. Finally, a hardware-in-the-loop (HIL) test platform was built using components such as Matlab/Simulink, NI-Veristand, PowerCal, HIL test cabinet, and vehicle controller. The designed energy management strategy was then tested using the HIL test platform. The test results show that, compared with the energy management strategy based on power following, the DP-MPC-based energy management strategy reduces fuel consumption by approximately 7.97%, 13.06%, and 11.03%, respectively, under the three operating conditions of plowing, rotary tillage, and transportation. This achieves fuel-saving performances of approximately 91.34%, 94.87%, and 96.69% compared to global dynamic programming. The test results verify the effectiveness of the proposed strategy. This research can provide an important reference for the design of energy management strategies for hybrid tractors. [ABSTRACT FROM AUTHOR]

In response to the problems of limited algorithms and low diagnostic accuracy for fault diagnosis in large tractor transmission systems, as well as the high noise levels in tractor working environments, a defect detection approach for tractor transmission systems is proposed using an enhanced convolutional neural network (CNN) and a bidirectional long short-term memory neural network (BILSTM). This approach uses a one-dimensional convolutional neural network (1DCNN) to create three feature extractors of varying scales, directly extracting feature information from different levels of the raw vibration signals. Simultaneously, in order to enhance the model's predicted accuracy and learn the data features more effectively, it presents the multi-head attention mechanism (MHA). To overcome the issue of high noise levels in tractor working environments and enhance the model's robustness, an adaptive soft threshold is introduced. Finally, to recognize and classify faults, the fused feature data are fed into a classifier made up of bidirectional long short-term memory (BILSTM) and fully linked layers. The analytical findings demonstrate that the fault recognition accuracy of the method described in this article is over 98%, and it also has better performance in noisy environments. [ABSTRACT FROM AUTHOR]

The FCDET is considered as a promising and advanced agricultural machinery due to its convenience and controllability. To enhance the control performance of the FCDET unit dynamic system, understanding the accurate position of the center of gravity (CoG) of the tractor unit in longitudinal motion and the operating environment is essential. In this paper, we proposed a real-time estimation method of CoG position of longitudinal motion for FCDET plowing and transportation conditions. CoG height and longitudinal axis distance distribution coefficients are used as state estimation variables, and the data obtained from displacement and velocity sensors are used as state observation variables, establishing a discrete system state space model and proving the observability. The proposed Derived UKF algorithm introduces the Sage-Husa adaptive noise equation within the Square-Root UKF framework to address the non-positive definite matrix problem. The research shows that the precise CoG longitudinal position effectively reflects changes in operational pavement load. The Derived UKF algorithm exhibits high state estimation accuracy in plowing and transportation conditions, with mean absolute errors of 14.2% and 5.0% of the state amplitude, respectively. This study supports the practical application of real-time state parameter estimation algorithms in controlling advanced agricultural machinery distributed drive systems. [ABSTRACT FROM AUTHOR]

To further enhance the crashworthiness of subway vehicle anti-climb energy-absorbing devices, this paper proposes a novel collapsible structure, which is embedded with honeycomb aluminum blocks and consists of an inner and outer double-layer square tube. An impact finite element model of the subway vehicle's anti-climb energy-absorbing device was established using LS-DYNA (v.17.2). The effects of the connecting diaphragm thickness, the inner and outer tube thicknesses of the thin-walled tubes, and the yield strength of the honeycomb aluminum on the energy absorption and impact force of the anti-climb energy-absorbing device were investigated. The results indicate that changes in the inner and outer tube thicknesses of the thin-walled tubes significantly affect the energy absorption and impact force of the anti-climb energy-absorbing device. However, changes in the connecting diaphragm thickness only increase the maximum energy absorption by up to 7.5% but have a significant impact on the maximum peak force. It was also found that the difference in energy absorption due to changes in the yield strength of the honeycomb aluminum is only 3.6%, suggesting that the yield strength of the honeycomb aluminum and the connecting diaphragm thickness have a limited influence on the crashworthiness design of the anti-climb energy-absorbing device. Furthermore, a multi-objective surrogate model characterizing the specific energy absorption and maximum peak force was established for the aforementioned four influential parameters using the response surface method. The model was then optimized using a genetic algorithm, resulting in optimal parameters that increased the energy absorption and specific energy absorption by 27.3% and 13.8%, respectively, compared to the original values, leading to a significant improvement in crashworthiness. The findings provide valuable references for and insights into the crashworthiness design and optimization of subway vehicles' anti-climb energy-absorbing devices. [ABSTRACT FROM AUTHOR]

Future field work tasks will require mountain tractors to pass through rough terrain with limited human supervision. The wheel–soil interaction plays a critical role in rugged terrain mobility. In this paper, an algorithm for the estimation of soil characteristic parameters based on the Simpson numerical integration method and Gauss–Newton iteration method is presented. These parameters can be used for passability prediction or in a traction control algorithm to improve tractor mobility and to plan safe operation paths for autonomous navigation systems. To verify the effectiveness of the solving algorithm, different initial values and soils were selected for simulation calculations of soil characteristic parameters such as internal friction angle, settlement index, and the joint parameter of soil cohesion modulus and friction modulus. The results show that the error was kept within 2%, and the calculation time did not exceed 0.84 s, demonstrating high robustness and real-time performance. To test the applicability of the algorithm model, further research was conducted using different wheel parameters of electric mountain tractors under wet clay conditions. The results show that these parameters also have high accuracy and stability with only a few iterations. Thus, the estimation algorithm can meet the requirements of quickly and accurately identifying soil characteristic parameters during tractor operation. A criterion for the passability of wheeled tractors through unknown terrain is proposed, utilizing identified soil parameters. [ABSTRACT FROM AUTHOR]

Hydrogen fuel cell tractors are emerging as a new power source for tractors. Currently, there is no mature energy management control method available. Existing methods mostly rely on engineers' experience to determine the output power of the fuel cell and the power battery, resulting in relatively low energy utilization efficiency of the energy system. To address the aforementioned problems, a power optimization method for the energy system of hydrogen fuel cell wheel-driven electric tractor was proposed. A dynamic model of tractor ploughing conditions was established based on the system dynamics theory. From this, based on the equivalent hydrogen consumption theory, the charging and discharging of the power battery were equivalent to the fuel consumption of the hydrogen fuel cell, forming an equivalent hydrogen consumption model for the tractor. Using the state of charge (SOC) of the power battery as a constraint, and with the minimum equivalent hydrogen consumption as the objective function, an instantaneously optimized power allocation method based on load demand in the energy system is proposed by using a traversal algorithm. The optimization method was simulated and tested based on the MATLAB simulation platform, and the results showed under ploughing conditions, compared with the rule-based control strategy, the proposed energy system power optimization method optimized the power output of hydrogen fuel cells and power batteries, allowing the energy system to work in a high-efficiency range, reducing the equivalent hydrogen consumption of the tractor by 7.79%, and solving the energy system power distribution problem. [ABSTRACT FROM AUTHOR]

In order to improve the interior sound quality of Electric Vehicles (EV), solve the problem of low sense of power and comfort of the interior sound as well as the large electromagnetic excitation order noise of motor and the sharp interior sound, this article designs a dynamic active sound control system for EV under accelerated driving conditions. Firstly, by comparing and analyzing the sound spectrum characteristics of fuel vehicle (FV) and EV during acceleration, a short-time Fourier transform (STFT) is adopted to extract and synthesize the engine sound. Secondly, the influence of the engine order composition and the energy distribution in the frequency domain on the sound quality of the vehicle is analyzed, and an active control system for sound quality is proposed. And the software and hardware development of the active control sound system is completed. Finally, through real-vehicle testing and verification, the sense of comfort and power of the EV interior sound has been greatly improved during acceleration, and the total value of interior sound can meet the requirement. The sound pressure level and loudness of interior sound have been increased, and the sharpness of the sound inside the vehicle has been improved, with a maximum reduction of 1.0acum. [ABSTRACT FROM AUTHOR]

To address the issues of tractors using too much fuel and not being energy efficient, a predictive control strategy based on Pontryagin's minimum principle integrating working condition prediction is proposed for agricultural hybrid tractors. The Dongfanghong 1804 tractor is being used for research. Firstly, the main parameters of the hybrid drive system are determined and modeled. Secondly, based on the adaptive cubic exponential forecasting method, the working condition information for a period of time in the future is predicted through historical working condition information. Furthermore, combining the predicted working conditions information, the goal is to minimize the total energy consumption cost of the entire machine. Motor power and diesel engine power are control variables. The battery state of charge is a state variable. Subsequently, a predictive control strategy based on Pontryagin's minimum principle integrating working condition prediction is proposed. Finally, the simulation test is carried out based on the MATLAB simulation platform. Research indicates: under plowing conditions, compared with the power following control strategy, the proposed predictive control strategy can effectively manage the performance of the diesel engine and motor, ensuring they operate at their most efficient level. The total energy consumption costs of the power following control and predictive control strategies are 37.17 China Yuan (CNY) and 33.67 CNY, respectively. The cost of energy used is decreased by 9. 42%, which helps make tractor field plowing more efficient and economical. [ABSTRACT FROM AUTHOR]

Unmanned tractors under ploughing conditions suffer from body tilting, violent shaking and limited hardware resources, which can reduce the detection accuracy of unmanned tractors for field obstacles. We optimize the YOLOv8 model in three aspects: improving the accuracy of detecting tilted obstacles, computational reduction, and adding a visual ranging mechanism. By introducing Funnel ReLU, a self-constructed inclined obstacle dataset, and embedding an SE attention mechanism, these three methods improve detection accuracy. By using MobileNetv2 and Bi FPN, computational reduction, and adding camera ranging instead of LIDAR ranging, the hardware cost is reduced. After completing the model improvement, comparative tests and real-vehicle validation are carried out, and the validation results show that the average detection accuracy of the improved model reaches 98.84% of the mAP value, which is 2.34% higher than that of the original model. The computation amount of the same image is reduced from 2.35 billion floating-point computations to 1.28 billion, which is 45.53% less than the model computation amount. The monitoring frame rate during the movement of the test vehicle reaches 67 FPS, and the model meets the performance requirements of unmanned tractors under normal operating conditions. [ABSTRACT FROM AUTHOR]

In recent years, more and more attention has been paid to fuel cell-based hybrid tractors. In order to optimize the global power distribution of tractors and further improve the fuel economy and fuel cell durability of the system, this paper designs an energy management strategy to maximize external energy efficiency based on fuel cell/lithium battery/supercapacitor hybrid tractors. This strategy aims to reduce the real-time hydrogen consumption of the system while maximizing the external energy output so as to reduce the impact of load randomness on the output power of the fuel cell. Under the typical ploughing conditions of the tractor, the simulation is compared with the state machine strategy and the equivalent hydrogen consumption minimization strategy. The results show that the proposed strategy meets the power requirements of a given ploughing condition, and compared with the two traditional strategy systems, the performance characteristics of auxiliary energy are more fully exerted. It reduces the burden on fuel cells and improves the durability of fuel cells. The hydrogen consumption of the system was reduced by 11.03 g and 16.54 g, respectively, improving the overall economy of the hybrid system. [ABSTRACT FROM AUTHOR]

The limitations of the tractor virtual test system are evident in various aspects, including model reuse, system expansion, offsite interconnection, and virtual reality verification. To address these challenges, a distributed virtual test system for tractors based on the high-level architecture (HLA) is proposed. Involve analyzing the hardware structure and the tractor virtual test system, constructing the system federation and its members, and designing the federated object model (FOM) and simulation object model (SOM) tables. The system integrates multi-domain commercial software and enables real-time virtual testing through TCP/IP interconnection of multiple machines. To evaluate the system's performance, a virtual test of the tractor's reversing clutch engagement performance is conducted. The system's simulation performance and data transmission delay are thoroughly tested and analyzed. The results indicate that when the system's data volume reaches 5000KB, the data delay is 9.7ms, which satisfies the requirement of not exceeding 10ms for tractor virtual testing delay. The virtual test of the reversing clutch power reversal process demonstrates that it lasts 0.7s, with the vehicle speed changing from -3.5km/h to 3.5km/h, the forward gear piston oil pressure increasing from 0MPa to 5MPa, and the peak impact degree reaching 17m/s3. The slip work during the reversing process is measured to be 21kJ. Furthermore, the gray correlation method is employed to compare the virtual test results with the bench test results, confirming their consistency. The power reversal process exhibits relatively smooth speed changes overall. Therefore, the tractor power shift transmission (PST) reversing clutch virtual test model operates effectively within the HLA-based tractor virtual test system. [ABSTRACT FROM AUTHOR]

In light of the challenges posed by the complex structural characteristics and significant coupling of vibration signals in rotating machinery, this study proposes an adaptive noise reduction method called Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN). Additionally, an enhanced threshold screening Singular Value Decomposition (SVD) algorithm is introduced to address the issues pertaining to noise identification and feature extraction in the context of vibration signals from rotating machinery, which are subjected to complex noise interference. The effectiveness of the proposed approach is substantiated through the evaluation of key metrics, such as the signal-to-noise ratio (SNR), as well as the utilization of advanced signal analysis techniques, including Short Time Fourier Transform (STFT) and Continuous Wavelet Transform (CWT). The experimental results validate the finding that the combination of the improved CEEMDAN and the enhanced threshold screening SVD algorithm effectively reduces noise interference in vibration signals from rotating machinery. This integrated denoising approach successfully preserves the informative characteristics of the vibration signals, thereby laying a foundation for the subsequent fault diagnosis of rotating machinery. [ABSTRACT FROM AUTHOR]

Energy management strategies are crucial for improving fuel economy and reducing the exhaust emissions of hybrid tractors. The authors study a series diesel-electric hybrid tractor (SDEHT) and propose a multi-operating point Fuzzy PID control strategy (MOPFPCS) aimed to achieve better fuel economy and improved control. To further improve the vehicle economy, the adaptive particle swarm optimization method is used to optimize the key parameters of the Fuzzy PID controller. A co-simulation model in AVL-Cruise and Matlab/Simulink environment is developed for plowing mode and transportation mode. The simulation results show that under the two operation modes, the equivalent fuel consumption of the adaptive particle swarm optimization multi-operating points Fuzzy PID control strategy (APSO-MOPFPCS) is reduced by 18.3% and 15.0%, respectively, compared to the engine single-operating point control strategy (ESOPCS). Also, it was found to be reduced by 9.5% and 4.6%, respectively, compared to the MOPFPCS. [ABSTRACT FROM AUTHOR]

Based on the analysis of the operating conditions of the tractor, a Hybrid four-wheel drive tractor is proposed, and formulate the torque distribution control strategy based on fuzzy control, to control the driving wheel slip rate of the Hybrid four-wheel drive tractor in the high traction efficiency operating range of the tractor. The vehicle model of the Hybrid four-wheel drive tractor is established in AVL-CRUISE software, and the torque distribution control strategy based on fuzzy control is established in MATLAB/Simulink software. The AVL-CRUISE and MATLAB/Simulink co-simulation was carried out based on the plowing condition of the tractor. The simulation results show that the torque distribution control strategy based on fuzzy control can control the driving wheel slip rate of the Hybrid four-wheel drive tractor in the high traction efficiency operating range, the power performance of the Hybrid four-wheel drive tractor is improved, while the engine runs smoothly and is always in the high-efficiency range of engine operation, and the economy is better. [ABSTRACT FROM AUTHOR]

Aiming at the unreasonable determination of the power coupling device speed ratio and the power battery capacity in the initial design stage of the dual-motor electric tractor, a dual-motor drive system is designed, and a parameter optimization method based on driving cycles (POMBDC) is proposed. By analyzing the driving characteristics requirements and actual working conditions of the tractor, the dynamic model of the dual-motor drive system under different working modes is established, and the parameters of the dual-motor, transmission and maximum service mass are designed. On this basis, based on the driving cycles and aiming at the lowest power consumption, the POMBDC is formed, this method can collaboratively optimize the power coupling device speed ratio and the power battery capacity. In order to verify the rationality of the POMBDC, the instantaneous optimization-constant speed ratio design method (IO-CSRDM), rule-optimization speed ratio design method (R-OSRDM) and rule-constant speed ratio design method (R-CSRDM) are developed as comparison methods, and simulation experiments are carried out. Under plowing conditions, the power battery capacity of the POMBDC is 3.08%, 5.71%, and 8.73% lower than those of the IO-CSRDM, R-OSRDM, and R-CSRDM, respectively. The power consumption resulting from the POMBDC is reduced by 3.11%, 5.74%, and 8.8%, compared with those of the IO-CSRDM, R-OSRDM and R-CSRDM, respectively. Under rotary tillage conditions, the power battery capacity of the POMBDC is 6%, 8.64%, and 11.11% lower than those of the IO-CSRDM, R-OSRDM, and R-CSRDM, respectively. The power consumption resulting from the POMBDC is reduced by 6.05%, 8.66%, and 11.13%, compared with those of the IO-CSRDM, R-OSRDM and R-CSRDM, respectively. The POMBDC can effectively increase the operating mileage of pure electric tractors and reduce costs. [ABSTRACT FROM AUTHOR]

This paper presents a proposed global optimal energy management strategy based on dynamic programming to enhance the energy consumption efficiency of an agricultural hybrid tractor that is equipped with a continuously variable transmission (CVT). Firstly, using a diesel-electric parallel agricultural hybrid tractor as the research object, a tractor-rotary tillage coupling dynamics model is constructed. Secondly, with the torque and speed of the motor, the torque and speed of the diesel engine, and the CVT speed ratio as the control variables, the state of charge (SOC) of the power battery as the state variable, and the goal of minimizing the total energy consumption of the whole machine, a global optimal energy management model based on dynamic programming is established. Finally, the field operation measured data is injected into the MATLAB simulation model, and experiments are carried out to verify the effectiveness of the energy management strategy. The results show that compared with the power-following energy management strategy, the proposed energy management strategy can make the diesel engine and electric motor work in the optimal area, and effectively reduce the total cost of energy consumption of the tractor during field operations. Under the condition of rotary tillage, the total cost of energy consumption is decreased by 16.89%. [ABSTRACT FROM AUTHOR]

For the poor working conditions of tractors, single-motor drive tractors usually choose a motor with large parameters, which leads to the lower efficiency of the motor under low-load conditions. Taking a wheeled tractor of YTO as the research object, a driving scheme of a dual-motor electric tractor was proposed, and the main components of the tractor electric drive system were matched. Based on MATLAB/Simulink, the electric tractor drive system model was established. On the premise of meeting the dynamic needs of the tractor, an optimization model was established with the tractor power consumption as the optimization goal and the power distribution coefficient of dual motors as the decision variable. The optimization model was solved by a genetic algorithm. The driving characteristics of the optimized electric tractor and the original tractor, as well as the instantaneous power consumption and total power consumption of the tractor before and after optimization, are compared and analyzed. The results show that the traction efficiency of the optimized electric tractor is about 2.7% higher than that of the original tractor, and the total power consumption of the electric tractor before and after optimization is reduced by 8.2%. The power performance and economy of the tractor after parameter matching and optimization are significantly improved. [ABSTRACT FROM AUTHOR]

In this study, an energy-saving control strategy based on instantaneous optimization is proposed to improve the energy efficiency of hybrid tractors. Using a parallel diesel–electric hybrid tractor as the research object, the topological and working characteristics were analyzed, and a coupled dynamic model of rotary tillage and tractor plow was constructed. Aiming to minimize the equivalent fuel consumption of the entire machine, the motor and diesel engine torques were taken as the control variables, and the state of charge of the power battery was taken as the state variable. Subsequently, an energy-saving control strategy based on instantaneous optimization is proposed. Finally, a simulation experiment was carried out using MATLAB to verify the effectiveness of the energy-saving control strategy based on instantaneous optimization. Compared with the energy-saving control strategy based on power-following, the results show that energy-saving control strategy based on instantaneous optimization can reasonably control the operating state of the diesel engine and motor. Therefore, the diesel engine and motor work in the high-efficiency area, and effectively reduce the equivalent fuel consumption of the tractor during field operation. Under rotary tillage and plowing conditions, equivalent fuel consumption is reduced by 4.70% and 6.31%, respectively. [ABSTRACT FROM AUTHOR]

The combination of characteristic parameters is the key and difficult point to improving the vibration attenuation of scissor seat suspension. This paper proposes a multi-objective optimization method based on entropy weight gray correlation to optimize the combination of characteristic parameters with better vibration attenuation. The differential equation of seat suspension motion is derived through mechanical analysis, and a simplified driver seat suspension single degree of freedom model is constructed. The range of spring stiffness and damper damping is calculated theoretically. Through main effect analysis and analysis of contribution, the main influencing factors of seat suspension vibration attenuation are studied, and the influence correlation of the main factors is analyzed. On this basis, the spring stiffness and damper damping are taken as control variables, and the upper plane acceleration, displacement, and transfer rate of the seat suspension are taken as optimization objectives. The Optimal Latin Hypercube Sampling (OLHS) was used to sample the Design of Experiments (DoE), fit the RBF surrogate model, and screen the optimal solution based on the MNSGA-II algorithm and entropy weight gray relation ranking method. The comparative analysis of the performance before and after optimization shows that the vibration reduction performance response indexes of the acceleration, displacement, and transmissibility of the optimized seats are increased by 66.41%, 2.31%, and 8.19%, respectively. The design and optimization method proposed in this study has a significant effect on the vibration reduction of seats, which provides a reference for the optimization of the vibration reduction performance of seat suspension. [ABSTRACT FROM AUTHOR]

With the application of new energy technology, hybrid agricultural machinery has been developed. This article designs a hybrid tractor energy management method to solve the problem of high energy consumption caused by significant load fluctuation of the tractor in field operation. This article first analyzes the characteristics of the hydrogen fuel cell, power battery, and ultracapacitor and designs a hybrid energy system for the tractor. Second, the energy management strategy (EMS) of multi-layer decoupling control based on the Haar wavelet and logic rule is designed to realize the multi-layer decoupling of high-frequency, low-frequency, and steady-state signals of load demand power. Then, the EMS redistributes the decoupled power signals to each energy source. Finally, a hardware-in-loop simulation experiment was carried out through the model. The results show that, compared with single-layer control strategies such as fuzzy control and power-following control, the multi-layer control strategy can allocate the demand power more reasonably, and the efficiency of the hydrogen fuel cell is the highest. The average efficiency of the hydrogen fuel cell was increased by 2.87% and 1.2%, respectively. Furthermore, the equivalent hydrogen consumption of the tractor was reduced by 17.06% and 5.41%, respectively, within the experimental cycle. It is shown that the multi-layer control strategy considering power fluctuation can improve the vehicle economy based on meeting the power demanded by the whole vehicle load. [ABSTRACT FROM AUTHOR]

The electric tractor has the advantages of zero-emission, high efficiency, and low noise, which is the direction of future development and transformation of agricultural power machinery. Aim at the problem that the simulation methods commonly used in the development of electric tractor drive system are poorly generalized and cannot meet the simulation needs of complex multi-domain physical systems. This paper proposes a modeling method for an electric tractor drive system, takes the YTO-500 tractor as the research object, designs and calculates the overall scheme and parameters of its drive system, divides the drive system into modules, establishes the energy system, motor system and mechanical parts model based on Modelica, and integrates the simulation model of electric tractor drive system on this basis. The traction performance and transportation working conditions were simulated and tested. With compared and analyzed, in the traction characteristics, the simulation and test results of maximum speed, maximum traction force, and maximum traction power of each gear are consistent; within 400s transportation simulation conditions, the speed range of electric tractor is 13~28km·h-1, which is consistent with the speed range of electric tractor transportation gear. The results show that the simulation and the test results are consistent, which verifies the credibility of the simulation and the correctness of the model built, providing a basis for future research and development of agricultural machinery. [ABSTRACT FROM AUTHOR]

In order to improve the comfort and dynamic sense of the interior sound of PEVs when driving at a constant speed, this paper carried out research on the evaluation method of the interior sound quality of EVs and the development of an active sound generation system (ASGS). The investigation and research on the sound development trend of EV interiors were carried out. Combined with subjective evaluation methods and test results, a constant-speed vehicle interior sound design method was proposed, which focused on three dimensions: engine order composition, spectral energy distribution, and sound amplitude enhancement in the typical vehicle speed range. The internal sound spectrum of FVs was analyzed, and the engine order sound simulation analysis was completed. It is verified that the short-time Fourier transform and synthesis technology based on Kaiser window function can meet the requirements of engine order sound fitting accuracy. To formulate the sound design plan, control objectives and control methods of an A-class pure electric SUV with both comfort and dynamic sense during accelerated driving, the correlation between the engine order sound amplitude and dynamic sense in the vehicle was analyzed, and the setting of active sound parameters of EVs was clarified. The control hardware and software of ASGS in the vehicle was developed, the construction of ASGS based on the vehicle sound system completed, and test verification was conducted. The objective test of the real vehicle shows that ASGS ensures a low-amplitude interior noise level. When the vehicle speed is 28.6 km/h, the sharpness is reduced by 0.52 acum, and the subjective evaluation test of the real vehicle further verifies that ASGS can improve the comfort and dynamic sound quality of EVs driving at a constant speed. [ABSTRACT FROM AUTHOR]

In order to improve the lightweight level of the automotive floor, reduce material application cost, and improve integrated process manufacturing performance through structural design and optimization, this article proposes a design method to link conceptual design and detailed design and optimize the composite floor by combining free size optimization and size optimization methods. The basic theory of composite mechanics is expounded from the stress-strain theory of single-layer plates, and the stiffness and strength theory of laminated plates, which provides theoretical support for the structural design, material design, and allowable value design of composites. The mechanical properties of CFRP were tested to obtain the basic material parameters of CFRP T300/5208. With the material parameters, the CFRP floor super layers are established in Optistruct software. The shape of the floor super layers is optimized by using the free size optimization method, with the body-in-white (BIW) lightweight coefficient as the objective and the BIW performance as the constraints. The BIW lightweight coefficient is reduced from 4.35 to 4.20 after free size optimization, and the layer blocks shape is obtained and clipped based on engineering application. With the floor mass as the objective and the BIW performance as the constraints, the size optimization of the floor layer blocks thickness is optimized. Then the number of floor layers is obtained, and the CFRP floor is established in Fibersim software. Use the simulation analysis method to compare and verify the performance of the floor before and after optimization. The results show that the failure index of the floor is far less than the failure standard, while the mass of the CFRP floor is reduced by 6.8 kg compared with the original steel floor, which an improvement rate reaching 27.5%. The design and optimization methods presented in this article provide a reference for the design and application of the CFRP floor. [ABSTRACT FROM AUTHOR]

Introduction: This study was designed to compare the outcomes of standard cardiopulmonary resuscitation (STD-CPR) and combined chest compression and abdominal compression–decompression cardiopulmonary resuscitation (CO-CPR) with a new device following out-of-hospital cardiac arrest (OHCA). Moreover, we investigated whether patient prognosis improved with this combination treatment. Methods: This trial was a single-centre, prospective, randomized trial, and a blinded assessment of the outcomes was performed. A total of 297 consecutive patients with OHCA were initially screened, and 278 were randomized to the STD-CPR group (n = 135) or the CO-CPR group (n = 143). We compared the proportions of patients who achieved a return of spontaneous circulation (ROSC), survived to hospital admission and survived to hospital discharge. In addition, we also performed the Kaplan–Meier analysis with a log-rank test at the end of the follow-up period to compare the survival curves of the two groups. Results: The differences were not statistically significant in the proportion of patients who achieved ROSC [31/135 (23.0%) versus 35/143 (24.5%)] and survived to hospital admission [28/135 (20.7%) versus 33/143 (23.1%)] between the CO-CPR group and STD-CPR group. However, there was a significant difference in the proportion of patients who survived to hospital discharge [16/135 (11.9%) versus 7/143 (4.9%)] between the two groups. Nine patients (6.7%) in the CO-CPR group and 2 patients (1.4%) in the STD group showed good neurological outcomes according to the cerebral performance category (CPC) scale score, and the difference was statistically significant (P = 0.003). The Kaplan–Meier curves showed that the patients in the CO-CPR group achieved better survival benefits than those in the STD-CPR group at the end of the follow-up period (log-rank P = 0.007). Conclusion: CO-CPR was more beneficial than STD-CPR in terms of survival benefits in patients who have suffered out-of-hospital cardiac arrest. Trial registration Chinese Clinical Trial Registry, registered number: ChiCTR2100049581. Registered 30 July 2021- Retrospectively registered. http://www.medresman.org.cn/uc/index.aspx. [ABSTRACT FROM AUTHOR]

To solve the problems of the Bouc-Wen model with multi-identification parameters, low accuracy, complex methods, and difficulty in implement, this study proposes a new way for parameter identification of the Bouc-Wen model of the magnetorheological (MR) damper by parameter sensitivity analysis and modified PSO algorithm. The one-at-a-time method (OAT) of local sensitivity analysis is utilized to analyze the unknown parameters in the Bouc-Wen model to complete the model simplification. Then, the modified PSO algorithm is used to identify the parameters of the simplified Bouc-Wen model. Finally, with the relationship between the currents and identified parameters, a Bouc-Wen model for current control is constructed by the curve fitting method. The results confirm that the parameter identification efficiency achieved via the parameter sensitivity analysis is improved by 50% by reducing the parameters of the Bouc-Wen model from 8 to 4. Then, compared with the standard PSO (SPSO) algorithm, the modified one is accurate and stable, and the convergence speed is increased by 17.65% on average. At last, compared with the test data under three different sinusoidal excitations, the model's accuracy is 89.11%, 92.56%, and 87.45%, respectively. The method proposed in this research can rapidly and accurately identify the Bouc-Wen model and lays a theoretical foundation for applying the MR damper model in vibration control. [ABSTRACT FROM AUTHOR]

In a battery management system, the accurate estimation of the battery's state of health (SOH) and state of capacity (SOC) are vital functions. The traditional estimation methods have limitations. To accurately estimate the SOC and SOH of power battery and improve the performance of the long-term estimation of a battery's SOC, a joint estimation method based on a Kalman filter is proposed in this work. First, a second-order RC equivalent circuit model of a ternary lithium battery was built, whose parameters were identified online, and the model's accuracy was verified. Then, the battery data under actual working conditions were collected. The SOC and SOH were estimated based on the Kalman filter algorithm, and the simulation was implemented using MATLAB. Finally, according to a time scale transformation, the battery state was jointly estimated, the SOC was estimated at a short-time scale, the SOH was estimated at a long-time scale, and the SOH estimation results were updated to the model parameters for SOC estimation. The results show that the accuracy of the method is very good, and it can effectively improve estimation accuracy and ensure batteries' long-term estimation performance. [ABSTRACT FROM AUTHOR]

Nowadays, parallel mechanisms are widely used in many fields because of their excellent structural performance. In order to improve the comprehensive performance of 6-UPS parallel mechanism, this article proposes a multi-objective optimization design method for parallel mechanism based on the Taguchi method and entropy-weighted gray relational analysis (EGRA) method. By establishing a parametric model of the 6-UPS parallel mechanism, taking the peak force on the drive pair of the drive branch chain of the mechanism, the minimum value of the projection angle of the body-fixed coordinate system (BCS) relative to the inertial coordinate system (ICS), and the minimum value of the average projected angle of the BCS relative to the ICS as the objective functions, the relationship between the design variables and the objective function is investigated under the condition that the constraints are satisfied. Using the optimization method proposed in this article, the multi-objective optimization problem is transformed into a single-objective optimization problem based on gray relational grade (GRG). Compared with the non-optimized 6-UPS parallel mechanism, the simulation results show that the peak force on the drive pair of the drive branch chain is reduced by 17.73%, and the minimum value of the projected angle and the minimum value of the average projected angle of the BCS relative to the ICS are increased by 27.36% and 36.17%, respectively, which effectively improves the load-bearing capacity and motion range of the 6-UPS parallel mechanism and verifies the reliability of the optimized design method. [ABSTRACT FROM AUTHOR]

To solve the problems of low identification accuracy and complex identification methods in the Bouc-Wen model of the magnetorheological (MR) damper, a new parameter identification method using the fireworks algorithm (FWA) is proposed. According to the experimental results of the dynamic characteristics of the MR damper and the simulation data of the Bouc-Wen model, the FWA is used to identify the seven parameters of the Bouc-Wen model. On the basis of the relationship between the identification results and the command current, the current-controlled Bouc-Wen model (I-Bouc-Wen model) is constructed and compared with the experimental results under different sinusoidal excitation frequencies. Compared with the genetic algorithm (GA), differential evolution (DE) algorithm, and particle swarm optimization (PSO) algorithm, the FWA has the advantage of faster convergence, shorter calculation time, and higher stability in solving the parameter identification problem of the highly nonlinear hysteretic model. Under three harmonic excitations, the average calculation accuracies of the I-Bouc-Wen model reache 88.64 %, 90.45 %, and 81.28 %, respectively, and the dynamic characteristic curve of the model is in basic agreement with the experimental results. It can be used for the subsequent controller design and simulation research and lay a foundation for applying the parameterized model of the MR damper in vibration reduction control. [ABSTRACT FROM AUTHOR]

The tractor power-shift transmission (PST) research and development is a design process that incorporates many disciplines such as mechanical, control, and electronics. Modeling and simulation are typically dependent on various commercial tools for each discipline, making simulation, integration, and verification of system-level models problematic. Aiming at this, we propose a PST multi-domain co-simulation method based on the functional mock-up interface (FMI) standard, analyze the FMI-based simulation mechanism and the PST simulation system logical structure, and established the PST mechanical system model, control system model, tractor engine model, and tractor dynamic model. Based on FMI, these models are integrated into a PST co-simulation model. The starting speed, final drive half shaft speed and torque were simulated and tested. Among them, the simulation and the test starting time are 2.7s and 2.8s respectively, and the two speed curves are consistent; the simulation and the test final drive half shaft torque are approximately equal with a value of 1.5kN·m; the average Theil's inequality coefficients (TIC) value of the simulation and the test final drive half shaft speed is 0.1375, which is less than 0.25. The results show that the simulation and the test results are consistent, the PST co-simulation model is accurate, and the co-simulation method is feasible, which can improve the efficiency of tractor PST system development. [ABSTRACT FROM AUTHOR]

In order to detect the assembly quality of the combine harvester accurately and effectively, a method for the assembly quality inspection of the combine harvester based on the improved whale algorithm (IWOA) to optimize the least square support vector machine is proposed. Aiming at the characteristics of whale optimization algorithm's weak search ability and easy maturity, this paper introduces the cosine control factor and the sine time-varying adaptive weight to improve it and uses the benchmark function to verify the general adaptability of the algorithm. Combined with the local mean decomposition (LMD), the assembly quality inspection model of the combine harvester was established and applied to the Dongfanghong 4LZ-9A2 combine harvester for experimental verification. The experimental results show that the IWOA proposed in this paper has better optimization ability and adaptability. The average accuracy of the IWOA model proposed in this paper reaches 90.5%, which is 4% higher than that of the WOA model, and the standard deviation of the average accuracy is reduced by 0.15%, which indicates that the IWOA model has better stability. [ABSTRACT FROM AUTHOR]

A method for parameter identification of the magnetorheological damper (MRD) model with an improved firefly algorithm (IFA) is proposed, and a semi-active seat control system with three-degree-of-freedom (3-DOF) is established by combining with a quarter car model to investigate the ride comfort. The dynamic characteristics of the MRD were analyzed by experimental method. Combined with the IFA, the parameters of the MRD phenomenon model were identified, and the forward model of the MR damper was constructed. The semi-active control model of a 3-DOF seat suspension was established. The MRD controller and suspension system controller were designed. The passive control, PID control, and Fuzzy-PID control on the vibration reduction of the semi-active seat suspension were compared and analyzed, under different road excitation. The simulation results show that the semi-active seat suspension controlled by the PID and Fuzzy-PID can effectively reduce the seat acceleration and dynamic stroke, which significantly improve the ride comfort and operation safety compared to the passive seat suspension. [ABSTRACT FROM AUTHOR]

Background: Histone modification plays essential roles in hepatocellular carcinoma (HCC) pathogenesis, but the regulatory mechanisms remain poorly understood. In this study, we aimed to analyze the roles of Megakaryoblastic leukemia 1 (MKL1) and its regulation of COMPASS (complex of proteins associated with Set1) in HCC cells.Methods: MKL1 expression in clinical tissues and cell lines were detected by bioinformatics, qRT-PCR and western blot. MKL1 expression in HCC cells were silenced with siRNA, followed by cell proliferation evaluation via Edu staining and colony formation, migration and invasion using the Transwell system, and apoptosis by Hoechst staining. HCC cell tumorigenesis was assessed by cancer cell line-based xenograft model, combined with H&E staining and IHC assays.Results: MKL1 expression was elevated in HCC cells and clinical tissues which was correlated with poor prognosis. MKL1 silencing significantly repressed proliferation, migration, invasion and colony formation but enhanced apoptosis in HepG2 and Huh-7 cells. MKL1 silencing also inhibited COMPASS components and p65 protein expression in HepG2 and Huh-7 cells. HepG2 cell tumorigenesis in nude mice was severely impaired by MKL1 knockdown, resulted into suppressed Ki67 expression and cell proliferation.Conclusion: MKL1 promotes HCC pathogenesis by regulating hepatic cell proliferation, migration and apoptosis via the COMPASS complex and NF-κB signaling. [ABSTRACT FROM AUTHOR]

According to the characteristics of differential steering problem of wheel drive electric tractor, the three degree of freedom dynamic model was established, and the slip rate-speed solving model and steering trajectory model were derived. By constructing the driver input model, the system simulation model was established. The effects of differential speed on yaw rate, roll angle, slip rate and steering radius was analyzed. The results show that the recommended range of differential speed rate under heavy load and low speed condition is 21% ~ 23%, and the turning radius is 4. 57 ~ 5. 01 m. The range of differential speed rate under light load and high speed condition is 6% ~8%, and the turning radius is 13. 13 ~ 17. 50 m. [ABSTRACT FROM AUTHOR]

This paper proposes a control strategy of dual-motor independent drive electric tractor with cooperative control power take-off (PTO) and driving systems by investigating its structural characteristics to meet the field operation requirements. In the following operation mode, the vehicle speed is taken as the input signal, and the PTO motor speed is followed by the vehicle speed at a proportional ratio. Four different principles of collaborative control strategy-based stability control, namely, general closed-loop, conventional PID, adaptive fuzzy PID, and fuzzy neural network adaptive PID controls, are proposed to meet the requirements during speed change. Hardware design is divided into modules in accordance with circuit function. Software design is divided into application layer and underlying software, where the application software realizes the control strategy of the entire machine. The underlying software is based on the hardware driver of MC9S12XEP100 that connects the application layer software and hardware. A hardware-in-the-loop test platform based on dSPACE/DS1007 is built to test the function of the collaborative controller. Results show that the stabilization time of fuzzy neural network adaptive PID control is 0.024 s. Compared with the three other control modes, the settling time decreases by 0.256, 0.034, and 0.028, respectively, and the overshoot decreases to 1.6%. Root locus analysis results show that the stability of the system is the best. Under the entire machine cooperative operation mode hardware in the loop test, the PTO motor maintains the fixed target speed under the fixed speed output mode, and the PTO speed in the following mode has a good follow-up to the vehicle speed. The controller realizes the control of the power output shaft to cut between the following and standard speeds. It also meets the requirement of cooperative control in the operation of dual-motor independent drive electric tractor. [ABSTRACT FROM AUTHOR]

To improve the efficiency of agricultural production, it is necessary to use Automated Mechanical Transmission(AMT) system to tractors. The required functions of the AMT system are analysed though some YTO-LX series tractors. Taking the difference between real and target speeds and the change percentage of difference as control parameters, the engine's control strategy is determined based on fuzzy control theory. The control strategy of clutch engaging during gear shifting is made with tractor driving dynamics. The integrated control strategy of shifting is developed though closed-loop control. The simulation model of the tractor is developed by Cruise software, and the power and fuel economy of tractors is determined. The correctness and feasibility of the control strategy and system parameters are verified. Simulation results show that the tractor AMT system is controlled effectively, and several working modes are achieved. When the tractor ploughs in the low IV gear to middle IV gear, the maximum traction is 43.62 kN, the top speed is 13.65 km/h, the max shift time is 0.95 s, the max shifting shock extent is 14.75 m/s3 and the fuel consumption is about 25 kg/h. [ABSTRACT FROM AUTHOR]

Background: Leukocyte immunoglobulin-like receptor B2 (LILRB2) has recently been considered a promising tumor promoter in human cancers.Materials and Methods: In this study, the expression of LILRB2 was assessed in 82 samples of surgically resected human hepatocellular carcinoma (HCC) tissues using immunohistochemistry (IHC).Results: LILRB2 was overexpressed in HCC tissues and its expression was positively and significantly correlated with poor prognostic features of HCC patients, including poor cell differentiation, larger primary tumor size, and shorter overall survival. In addition, there was a positive correlation between the expression of LILRB2 and its classical ligand human leukocyte antigen G in human HCC tissues.Conclusion: LILRB2 might play an important role in HCC progression and correlate with poor prognosis of HCC. [ABSTRACT FROM AUTHOR]

Peridynamics is a formulation of the classical elastic theory that is targeted at simulating deformable objects with discontinuities, especially fractures. Till now, there are few studies that have been focused on how to model general hyperelastic materials with peridynamics. In this paper, we target at proposing a general strain energy function of hyperelastic materials for peridynamics. To get an intuitive model that can be easily controlled, we formulate the strain energy density function as a function parameterized by the dilatation and bond stretches, which can be decomposed into multiple one‐dimensional functions independently. To account for nonlinear material behaviors, we also propose a set of nonlinear basis functions to help design a nonlinear strain energy function more easily. For an anisotropic material, we additionally introduce an anisotropic kernel to control the elastic behavior for each bond independently. Experiments show that our model is flexible enough to approximately regenerate various hyperelastic materials in classical elastic theory, including St. Venant‐Kirchhoff and Neo‐Hookean materials. [ABSTRACT FROM AUTHOR]

An equiatomic CoCrFeNiMn high entropy alloy (HEA) was produced by powder metallurgy method. Cold rolling followed by subsequent annealing was conducted to further optimize the microstructure and mechanical properties. The results show that the SPSed CoCrFeNiMn HEA has an equiaxed single fcc phase microstructrue. Cold rolling results in extensive dislocation pile-up and twinning within the grains. The 80% cold-rolled alloy shows very high yield strength of 1292 MPa, but a limited elongation of 3%. Subsequent annealing produces recrystallization and precipitation of fine σ particles with particle size of 30-100 nm. The annealed alloy has a yield strength of 540 MPa, which is about two to three times of the cast CoCrFeNiMn HEA, while still maintains a high tensile ductility of 41%. The improvement of the tensile properties is caused by the grain boundary strengthening, solid solution strengthening, and precipitation strengthening. [ABSTRACT FROM AUTHOR]

To solve the problems of low loading precision, slow response speed, and poor adaptive ability of a mobile dynamometer in a tractor traction test, a PID control strategy based on a radial basis function neural network with self-learning and adaptive ability is proposed. The mathematical model of the loading system is established, the algorithm of adaptive control is described, and the loading control method is simulated with MATLAB software. The system, which uses the NN-PID (neural network PID) control strategy, is used to test a YTO-MF554 tractor. Then, the proposed control strategy is validated. Results show that when the traction increases from 0 to 10 kN, the response time of the test system is 1.5 s, the average traction force in the stability range is 10.13 kN, and the maximum relative error of traction force is 2.2%. This control strategy can improve the response speed and steady-state accuracy and enhance the adaptive ability of the mobile dynamometer vehicle loading system. This study provides a reference for designing the adaptive controller of the mobile dynamometer vehicle loading system. [ABSTRACT FROM AUTHOR]

In order to improve the electrical conversion efficiency of an electric tractor motor, a load torque based control strategy (LTCS) is designed in this paper by using a particle swarm optimization algorithm (PSO). By mathematically modeling electric-mechanical performance and theoretical energy waste of the electric motor, as well as the transmission characteristics of the drivetrain, the objective function, control relationship, and analytical platform are established. Torque and rotation speed of the motor’s output shaft are defined as manipulated variables. LTCS searches the working points corresponding to the best energy conversion efficiency via PSO to control the running status of the electric motor and uses logic and fuzzy rules to fit the search initialization for load torque fluctuation. After using different plowing forces to imitate all the common tillage forces, the simulation of traction experiment is conducted, which proves that LTCS can make the tractor use electrical power efficiently and maintain agricultural applicability on farmland conditions. It provides a novel method of fabricating a more efficient electric motor used in the traction of an off-road vehicle. [ABSTRACT FROM AUTHOR]

Aimed at the drawbacks of traditional tractors, such as complicated transmissions, inefficient transmission systems, heavy fuel consumption rates, and high exhaust gas emissions, the design method of the tractor's series hybrid electric drive systems was put forward by calculating its plough operation rated traction. A feasible formation was given and included design methods of the electric tractive motor, weight parameters, and prime energy systems, which consist of a diesel engine and a generator of the powerful tractor's hybrid electric drive systems. Transmission ratios of the series hybrid electric tractor drive systems were designed to follow with differences of working load rates under commonly used working conditions, while making sure of the efficiency and capacity of transmission systems. Its storage battery parameters were designed to fill the traction power requirement, which is from the changing load situation when the tractor worked under a light gear. The YTO-1804 wheeled tractor has been taken as the investigative object, its series hybrid electric drive systems have been designed by using the aforementioned method. Upon analysis of its tractive characteristics, the results conveyed that the installed tractor's working adaptability and tractive characteristics are better when it compared with the original tractor. Output of the electric motor is suitable with the requirements of a heavy load working circumstance. The curve portrayed that the relation between the traction force and the traction power of the installed tractor could cover the original tractor's working area. The installed tractor's transmission is more efficient and its structure is simpler. Combined with the relevant slippage test results to analyze the installed tractor's slippage situation, changes in slippage rate followed with changes in driving force are acceptable. Based on the analysis of the difference of equivalent fuel consumption rates between the two types of drive systems, the analysis of the relevant curve, the relevant status of the installed tractor were on the bottom of original tractor's curve. The result proved that the installed tractor has a better fuel economy. Continuously variable function can be reached under a definitional gear. When the tractor is on the working model or the driving model, the most important performance parameter has a wide regulation range. Based on plough operation, furrow plow number and the product of tilling depth value with specific resistance value was seen as an index of the tractor's working load, the result proved that the original tractor's common working area can be distinguished with the relevant gears setting intention, and it has higher efficiency when the load rate is higher. As well, the traction efficiency can be improved 2.98% on average. So, different working requirements of investigative objects can be reached well. The design method laid the foundation for the following study of the powerful tractor's series hybrid electric tractor drive systems. [ABSTRACT FROM AUTHOR]

The design objectives of the structural parameters of the tractor drive motor are diverse, and the constraints are complex. It is difficult to optimize the overall performance of the unit by using the empirical method and single-objective optimization method. This paper proposes a multi-objective optimization method for tractor drive motors based on an improved Non-dominated Sorting Genetic Algorithm II (NSGA-II). Constraints are formulated according to the inherent characteristics of the motor itself and the characteristics of the tractor's working conditions. The objective function was established with the heat loss of the drive motor and the total efficiency of the drive system. Based on the designed solution process of NSGA-II algorithm, an example optimization was carried out, and the tractor electromechanical drive system was carried out with the single-objective optimization results of the optimal energy use efficiency of the drive motor and the optimal mechanical transmission efficiency of the transmission system as the control group. The test results show that compared with the control group, the proposed multi-objective optimization method can make the overall tractor system efficiency the highest, and the maximum and rated values of the total efficiency η q of the drive system of the multi-objective optimization design scheme. Compared with the optimal design scheme with η me as a single objective, it was increased by 2% and 1.4%, respectively, and compared with the optimal design scheme with η tr as a single objective, it is improved by 26.5% and 73.6%, respectively. It can provide an effective calculation method for the motor design problem in the subsequent development of the tractor electromechanical drive system. [ABSTRACT FROM AUTHOR]