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Objective To develop a nutritional formula on enhancing the endurance of heavy load exercise, and evaluate its efficacy comprehensively. Methods Sixty C57BL/6J male mice were randomly divided into control group (CON group) and low-, medium- and high-dose nutritional formula groups (LDF, MDF and HDF groups), with 15 mice in each group. Each group received intervention with nutritional formula at corresponding dose for 2 weeks, and underwent adaptive training and heavy load exercise in the 1st and 2nd weeks, respectively. Exhaustion exercise time, skeletal muscle antioxidant indicators (SOD, MDA, PC and GSH), fatigue related indicators (serum URA, LDH and LA), muscle glycogen, and serum exercise injury related indicators (ALT, AST, CK and CK-MB) were measured and detected in the mice, and comprehensive evaluation was conducted according to relevant evaluation standards. Results The LDF group, MDF group and HDF group had significantly prolonged running exhaustion time than the CON group (P < 0.05), with the HDF group showing the greatest improvement (P < 0.05). Compared with the CON group, the activities of SOD and GSH in the skeletal muscles were significantly increased (P < 0.05), while the levels of MDA and PC in skeletal muscles were obviously decreased in the 3 doses of nutritional formula groups (P < 0.05). PAS staining of the skeletal muscles displayed that the glycogen content was significantly increased in the MDF group and the HDF group than the CON group (P < 0.05), and the highest increase was observed in the HDF group (P < 0.05). Biochemical test revealed that the levels of LDH, LA, ALT, AST, CK, and CK-MB were remarkably lower in the 3 doses of nutritional formula groups than the CON group (P < 0.05). Conclusion The nutritional formula can significantly improve the endurance and skeletal muscle antioxidant capacity in mice under heavy load exercise, and has anti-fatigue and -injury protection effects. This nutritional formula can be used to support physical fitness during heavy load endurance exercise.

Objective To explore the effect and mechanism of n-3 polyunsaturated fatty acids (n-3 PUFAs) on skeletal muscle inflammation and fatigue in exhaustive exercise mice. Methods Using fish oil gavage to C57BL/6J mice for exogenous intervention of n-3 PUFAs and Fat-1 mice (endogenous synthesis of n-3 PUFAs), a 7-day exhaustive mice model was established. Forty C57BL/6J mice were divided into 4 groups (10 in each group): the blank resting group (CON group), the blank exercise group (EX group), the fish oil resting group (FO group) and fish oil exercise group (FO+EX group). Twenty Fat-1 mice were divided into 2 groups (10 in each group): the Fat-1 resting group (FA group) and the Fat-1 exercise group (FA+EX group). Serum levels of urinel UREA, glucose (GLU), creatine kinase (CK) and lactate dehydrogenase (LDH) were detected by automatic biochemical analyzer. Serum IL-1β and IL-18 levels were determined by enzyme-linked immunosorbent assay. The mRNA expression levels of IL-1β, IL-18, NLRP3, ASC and Caspase-1 in gastrocnemius muscle tissues were detected by RT-qPCR. The protein expression levels of NLRP3 and ASC in gastrocnemius muscle tissues were detected by Western blotting. Kits were used to detect the levels of malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), muscle glycogen and liver glycogen in gastrocnemius muscle. HE staining was used to observe the morphological and structural changes of gastrocnemius muscle. Results n-3 PUFAs decreased the levels of UREA, CK and LDH in exhaustive exercise mice (P < 0.05), and increased the level of GLU (P < 0.05). n-3 PUFAs decreased serum IL-1β and IL-18 levels in exhaustive exercise mice (P < 0.05). n-3 PUFAs inhibited the mRNA expression levels of NLRP3, ASC, Caspase-1, IL-1β and IL-18 in skeletal muscle of exhaustive exercise mice (P < 0.05), and the protein expression levels of NLRP3 and ASC in skeletal muscle of exhaustive exercise mice (P < 0.05). n-3 PUFAs increased the content of liver and muscle glycogen in exhaustive exercise mice (P < 0.05). n-3 PUFAs increased the activities of SOD and GSH-Px in gastrocnemius muscle of mice during exhaustive exercise (P < 0.05), and decreased the content of MDA (P < 0.05). Conclusion n-3 PUFAs can effectively improve the antioxidant capacity and fatigue of exhaustive exercise mice, and the mechanism may be related to n-3PUFAs inhibiting the overactivation of NLRP3 inflammatome in skeletal muscle of exhaustive exercise mice.

In order to improve the fuel economy of coaxial parallel hybrid electric vehicle, the driver intention is used as the input variable of the fuzzy design to realize the fuzzy recognition of the driver intention, with considering the structural characteristics, working process and energy flow mode of coaxial parallel hybrid system. Fuzzy control torque distribution strategy based on recognition of driving intention is established in Matlab/Simulink, and joint simulation is performed with Cruise under NEDC cycle condition. The results show that, under the premise of satisfying the dynamic performance, compared with the logic threshold based on torque distribution control strategy, the proposed control strategy can effectively improve the working point of the engine, and can reduce the comprehensive fuel consumption of 100 kilometers about 3.2%, which satisfies the vehicle dynamics, and further improves the fuel economy.

In order to study the engagement performance of engagement sleeve and engagement gear ring in the shifting process of without synchronous AMT transmission mounted on hybrid vehicle, improve the smoothness of gear shifting and shorten the shifting time, the theoretical analysis and the virtual prototype simulation analysis method are used to study the engagement process between engagement sleeve and engagement gear ring of AMT transmission. The engagement process is divided into four stages: free sliding stage, tooth tip collision stage, tooth tip friction stage and inter-tooth meshing stage, a mathematical model is established. The dynamics model of the engagement process is established by Adams. The simulation model is compared with the theoretical calculation value, and the error is 7.3%. The effects of the speed difference between the meshing sleeve and the engagement gear ring and the shift force acting on the meshing sleeve on the meshing process are studied, and the optimum range of the speed difference is obtained. The research results of the study can provide critical guidance for automatic shift control.

Because of the particularity of the design of double circular arc gears, the influence of tooth surface friction on the transmission of double circular arc gears is often neglected in the past research on the dynamic characteristics of double circular arc gears. The precise model of double circular arc gear is designed by parameterization, and the dynamics performance of double circular arc gear is simulated by Adams software combined with multi-body dynamics analysis theory. By setting different friction coefficients between tooth surfaces, the influence of tooth surface friction on the dynamic performance of double circular arc gear transmission is analyzed, which is further verified by the transmission test of double circular arc gear. The simulation results provide some reference for the correlation between the double circular arc gear transmission and the tooth surface friction.

Aiming at the abnormal sound issue of the non-load SUV rear axle when driving in 90 100 km/h speed,by using the noise transfer function,the theoretical analysis is carried out,combining with NVH and vibration noise hammer test,the noise and vibration identification is carried out. Then,by using finite element method,the vibration response of the vehicle under different frequencies is analyzed,the fourth the frame supports is the key point while transfer vibration is identified,the cavity modes and noise amplification is caused.The experimental results are consistent with the results of finite element simulation. A solution is implemented to optimize the fourth frame support and restrain the transformation of the vibration noise. The test result shows the effect of interior noise reduction is significant,a reference for later project development is provided.