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Load models have a significant influence on power system simulation. However, current load modeling approaches can hardly satisfy the diversity and time- varying characteristics of loads [including electric vehicles (EVs) and battery storage] in terms of model accuracy and computing efficiency. An online modeling method for composite load models based on measurement information is proposed in this paper. Firstly, the dominant factors in load model output are analyzed based on the active subspace of parameter space. Then the clustering algorithm is applied to cluster the large number of underlying loads based on the characteristics of load daily output curves. Finally, the underlying loads are equivalently aggregated from the low voltage levels to the high voltage levels to construct the composite load model. Simulation results obtained based on PSCAD/EMTDC demonstrate that the load model constructed by the proposed approach can accurately reflect the actual load characteristics of a power system. [ABSTRACT FROM AUTHOR]

Although MXene has attracted great interest in diverse fields, it is susceptible to oxidation in water (H2O) with transition metal ions such as Co2+, Fe2+, and Cu2+, which is pronounced at high temperatures. This impedes the preparation of MXene‐based composites and their functional applications. Here, this study revealed that Co2+ increases the maximum and average atomic charge of H in H2O to improve the reactivity of H2O, which leads to the fact that Co2+ catalyzes the oxidation of Ti3C2Tx MXene. Furthermore, the addition of N,N‐dimethyl formamide (DMF) reduces the H2O activity and improves the oxidation stability of Ti3C2Tx in the presence of Co2+ via preferentially forming coordination bonds with Co2+. This strategy is also effective in enhancing the oxidation tolerance of Ti3C2Tx to Fe2+ in H2O. Moreover, it is feasible to enhance the oxidation stability of Ti2CTx MXene in H2O with the existence of Co2+. By virtue of these, the CoO/Ti3C2Tx composite was successfully prepared without obvious Ti3C2Tx oxidation, which is desirable to harness the advantages of Ti3C2Tx as the complementary component for lithium‐ion batteries. This work provides a straightforward paradigm to enhance the oxidation resistance of MXene in H2O in the presence of transition metal ions and at high temperatures, which opens a new vista to use MXene for target applications. [ABSTRACT FROM AUTHOR]

The Ministry of Ecology and Environment of the People ' s Republic of China formulated the " Differentiated Response Requirement Based on Performance Grading" measures for heavy air pollution alerts in July 2019 to promote air quality improvement and economic development. Eleven alerts (four yellow, six orange, and one red alert) in Langfang were classified into 8 pollution processes. The results showed that the mean concentration of PM2.5 was 41.4~129.0 µg/m³. The pollution processes were classified according to the backward trajectory analysis surface meteorological field changes, including southwest air masses, southeast air masses, northwest air masses and local air masses. The back of high pressure, bottom of low pressure, and weak pressure system might lead to the transport from southern regions. Moreover, uniform and weak pressure fields were the major meteorological fields in the northwest direction and during local pollution episodes. The mean and peak concentrations of PM2.5 in the southwest and local pollution processes were higher than those in the southeast and northwest, indicating that when these two types of pollution occur, the air quality is even worse. In addition, based on the emission reduction ratios of pollutants at various warning levels, the WRF-CMAQ model was used to evaluate the effectiveness of the differentiated response requirements based on performance grading during the 11 warning periods. The warning period, the mean concentration of PM2.5 during the warning period decreased by 2.6% to 5.9%, and the peak concentration of PM2.5 decreased by 0.7% to 7.7%. Overall, implementing emergency measures effectively improved the air quality and played a role in "peak shaving". [ABSTRACT FROM AUTHOR]

Evaluating the effect of the carbon emissions trading scheme (ETS) on the decarbonization of the power sector is a basic task in the construction of China’s ETS. We use the energy flow relationship between the power and heat sectors to develop a more accurate accounting framework for CO2 emissions in the power sector and employ the difference-in-differences method to evaluate the impact of China’s ETS on CO2 emissions in the power sector and its dynamic effect. On this basis, we explore the mechanisms by which the ETS facilitates the decarbonization of the power sector, as well as its heterogeneous impacts. We find that the ETS has significantly promoted the decarbonization of the power sector, reducing its CO2 emissions in the pilot provinces by approximately 24.53 Mt compared to the non-pilot provinces. The decarbonization effect of the ETS was continuous and strengthened. In addition, the ETS promotes decarbonization of the power sector through technological advances in power generation and electricity utilization. Finally, the ETS’s decarbonization effect on the power sector is influenced by the heterogeneity of regions, carbon prices and quota allocation methods. Our findings have beneficial implications for the construction of carbon markets in the context of carbon neutralisation and carbon peaking. [ABSTRACT FROM AUTHOR]

Zigzag graphene nanoribbons (GNRs) were selected as electrodes, and the electron transport properties, optical properties, and thermoelectric properties of four fullerene cluster-based molecular devices were studied. By applying different voltages on them, their I–V curves exhibited the multiple negative differential resistance (NDR) effect and the platform effect, which are described in more detail using their density of states (DOS) and projected density of states (PDOS). The results of rotating two types of (C60)4 molecules verify that both the NDR and the platform effects are essential characteristics of them. Furthermore, an examination is conducted on the photocurrent of the devices at the point of maximum light absorption, revealing that α-(C60)4 connected by a [2+2] ring addition bond in the transport direction exhibits superior optical properties and works better as a photoelectric device than β-(C60)4 connected via a C–C single bond in the transport direction. Finally, the thermoelectric current of the devices was studied. Our results contribute to the understanding and the potential application of single devices based on fullerene clusters in the area of molecular electronics. [ABSTRACT FROM AUTHOR]

The ability of composite cement materials to resist erosion by chloride ions is a critical factor in evaluating their dependability. This study aims to examine the influence of graphene oxide on the transportation of water molecules and chloride ions in modified cement composites. Molecular dynamics analysis suggests that graphene oxide can effectively bond to the substrate of hydrated calcium silicate gel pores, which forms a stronger confined fluid zone under the action of electrostatic interactions and van der Waals forces. Graphene oxide has negatively charged oxygen functional groups on its surface, and within a certain size range, it becomes more effective at restricting the penetration of water molecules and chloride ions. In addition, chloride solution immersion experiments were performed on graphene oxide modified cement mortar. The results demonstrated that a small quantity of graphene oxide can significantly improve the resistance of modified cement mortar to chloride ion erosion, whereas excessive amounts are detrimental, which aligns with the simulation results. It is hoped that this study will provide valuable insights into the use of graphene oxide nanoparticles in the corrosion protection of cement composites. [ABSTRACT FROM AUTHOR]

Room-temperature sodium–sulfur batteries are still hampered by severe shuttle effects and sluggish kinetics. Most of the sulfur hosts require high cost and complex synthesis process. Herein, a facile method is proposed to prepare a phosphorous doped porous carbon (CSBP) with abundant defect sites from camellia shell by oxidation pretreatment combined with H3PO4 activation. The pretreatment can introduce pores and adjust the structure of biochar precursor, which facilitates the further activation of H3PO4 and effectively avoids the occurrence of large agglomeration. Profiting from the synergistic effects of physical confinement and doping effect, the prepared CSBP/S cathode delivers a high reversible capacity of 804 mAh g−1 after 100 cycles at 0.1 C and still maintains an outstanding capacity of 458 mAh g−1 after 500 cycles at 0.5 C (1 C = 1675 mA g−1). This work provides new insights into the rational design of the microstructures of carbon hosts for high-performance room temperature sodium–sulfur batteries. [ABSTRACT FROM AUTHOR]