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For power batteries used in the electric vehicle, accurate state-of-charge estimation is important. However, as one of the most commonly used estimation method, the least square support vector regression is hard to balance the accuracy and efficiency. To solve this problem, the fuzzy information granulation based on asymmetric Gaussian membership function is proposed to improve the utilization efficiency of the effective data and enhance the prediction accuracy of battery states. In addition, the performance of the proposed method is compared with that of other commonly used member -ship functions. In experiments, the dynamic stress test condition and the urban dynamometer driving schedule condition are used to verify the effectiveness. Compared with the most commonly used triangle membership function, the proposed method improves the accuracy of estimation by 6.47% and 2.18% under two current conditions, respectively.

The energy crisis combined with increasingly severe environment pollution have highlighted the significance of the energy conservation and emission reduction in shipping industry. To improve the energy utilization rate and reduce pollution, a dual-pressure organic Rankine cycle system is proposed to reuse the heat of exhaust gas in marine engines. Many researches focused on the thermodynamics and thermos-economics of the waste heat recovery system, and optimized it from these two goals to recover more energy and decrease cost. However, the impact of the system itself on the environment, which was significant to assess the greenness, was often neglected in these studies. The system with high energy recovery rate may also cause serious environment pollution in the manufacturing or operation process, hence the environmental factor should be taken into account in the optimization. To solve the problems, an evaluation method combined thermodynamics, economics and environment is proposed. The parametric study of the dual-pressure organic Rankine cycle system with six common used working fluids is assessed by this method. Finally, taking the indicators of evaluation method as objective function, the multi-objective optimization method is conducted to figure out the optimum operation conditions for the system. Results show cyclopentane is the optimal working fluid considering thermodynamic, economic and environmental properties. Under the conditions of the evaporation pressure in high-pressure circuit 2.79 MPa, the evaporation pressure in low-pressure circuit 1.97 MPa, the condensation temperature 35 °C, the superheating temperature 1.2 °C, the system obtains a good performance with exergy efficiency 60.24%, electricity production cost 0.167 $/kWh and the environmental impact of net power output 11831.9 mPts/GJ.

Facing the energy shortage and environmental pollution problems in the world, a high-efficiency fuel cell scheme combined with waste heat recovery is regarded as an optimal selection of auxiliary power generation equipment for ships. In this study, a novel system, comprising solid-oxide-fuel-cell-preheating subsystem, homogeneous charge compression ignition engine and organic Rankine cycle, is designed and analysed. First, the mathematical model is established and verified to ensure the reliability of simulation results. Then, the effect of relevant parameters on homogeneous charge compression ignition engine performance is observed, and the optimal zeotropic working fluid of organic Rankine cycle is determined according to the exhaust temperature. Finally, the thermodynamic and economic analysis are carried out. The results indicate that the performance of the new system is better than that of the traditional combined system using gas turbine. Thermal efficiency and exergy efficiency of the system are more than 63.6% and 61.3%, which is about 18.76% and 17.95% higher than that of simple cell. In addition, the payback time is about 2.98 years, which is about half of the traditional combined system and can fully meet the economic requirements. This novel system can be a new selection of marine auxiliary power generation equipment.