Development of electric construction machinery in China:a review of key technologies and future directions

The issues of energy shortage and environmental pollution have accelerated the electrification of construction ma-chinery(CM)industry globally.In China,the amount of electric construction machinery(ECM)has been growing across the industry.The sales of ECM are estimated to reach 600000 vehicles by the end of 2025,while the total demand for battery power will reach 60 GWh.However,the development of ECM still faces critical challenges including reliable power supply and energy distribution among various components.In this review,we primarily focus on important technological breakthroughs and the difficulties faced by the CM industry in China.An overview of ECM including classification and characteristics is given at the beginning.Next,the selection of key components such as the electric motor and the energy storage units,and the control strategy in the pure electric drive system are discussed.The characteristics of the hybrid electric drive system such as structure design and power matching are analyzed in detail.The battery management system(BMS)is critical to ensure appropriate battery health for reliable power supply.Here,we extensively review technical developments in various BMSs.In addition,we roughly estimate the national total of CM emissions and the potential environmental benefits of employing ECMs in China.Finally,we set out future research directions and industrial development of ECM.

Evaluation of multidimensional simulations of summer air temperature in China from CMIP5 to CMIP6 by the BCC models: From trends to modes

To determine whether the capability of the CMIP6 version of Beijing Climate Center(BCC)models(BCC-ESMI and BCC-CSM2-MR)in simulating China summer surface air temperature(SAT)has improved,we presented a multidimensional evaluation of the summer SAT in China including the trends,modes,and influencing factors.Critical comparisons are also made with the results of CMIP5(BCC-CSM1.1 and BCC-CSMl.lm).In general,the CMIP6,especially BCC-CSM2-MR,has smaller deviations in the trends,the means,the mutations,the maximum centers,the variances,and the spatial patterns of the dominant modes from observatio relative to those of CMIP5.However,the BCC CMIP6 models still underestimate the SAT variation in the Qinghai-Tibetan Plateau and the northeastern regions of China,and the performance is unsatisfactory with respect to the physical drivers of the dominant modes.Importantly,all the BCC models can capture the spatio-temporal characteristics of the first mode well and can,in general,characterize the spatial pattern of the second mode,but none of the models perform well in the principal component of the second mode(PC2)due to the low performance with respect to the interannual variation of PC2.Furthermore,the factors influencing the leading two modes are evaluated.The two CMIP6 can simulate better the Northern Hemisphere subtropical high northern boundary affecting the first mode.Another factor,the Asia polar vortex area,can only be simulated better by two low-resolution models(BCC-CSM1.1 and BCC-ESM I).For the second mode,all four models simulate the influence of Asian zonal circulation well,but poorly simulate that of the southern Indian Ocean dipole due to a large deviation in the Indian Ocean surface temperature.