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Abstract Antireflective (AR) coatings with high transmittance and enhanced abrasion-resistance were prepared by a base/acid two-step catalyzed sol–gel process using tetraethylorthosilicate (TEOS) as precursor. These AR coatings exhibit both high transmittance and enhanced abrasion-resistance when the mole ratio of acid-catalyzed silica to base-catalyzed silica was 0.5. The experimental results revealed that the acid-catalyzed silica was covalently bonded to base-catalyzed silica particles, which greatly increased the abrasion-resistance. Hexamethyldisiloxane (HMDS) treatment was further used to improve the hydrophobicity of the AR coatings. The water contact angles of pure silica AR coatings and AR coatings treated with 16% HMDS were 21.3° and 72.5°, respectively, indicating a significant increase in hydrophobicity. FTIR spectra revealed the existence of –Si (CH 3 ) 3 after HMDS treatment, showing that the hydroxyl groups of AR coatings were replaced by –OSi (CH 3 ) 3 , affording the AR coatings treated with HMDS excellent environmental resistance.

Abstract Electric vehicles (EVs), as an efficient and environmentally friendly method for reducing fossil fuel use and air pollution, are becoming more popular as governments seek to implement sustainable development. Initial concerns about the high cost and limited travel range of EVs have now been mitigated through the convenient and efficient deployment of electric vehicle charging stations (EVCSs). The State Grid Sichuan Electric Power Company intends to construct six EVCSs in Tianfu New district, which is expected to play a significant role in the sustainable development of western China. As proper siting is the foundation for EVCS construction, in this paper, a multi-criteria group decision making (MCGDM) framework with linguistic information is proposed to deal with the EVCS siting in Tianfu New district. Thirteen criteria from four influencing aspects are identified to estimate the impact of EVCS construction. To address imprecise information and vague concepts in human language, interval type-2 fuzzy numbers (IT2 FNs), which can effectively reduce information leakage, are applied to model the linguistic terms. The entropy weight method and a rough consensus reaching process are introduced to ensure the rationality of final decision. The results show that the proposed MCGDM is feasible and efficient for EVCS site selection.

Abstract Wind energy has gained significant support to be one of the primary sources of near-zero-emission energy systems. Based on the technological paradigm theory and employing a novel data analysis system (DAS), this paper provides an overview of wind energy technological developments. With key energy law and policy decisions highlighted, the visualization process clearly identified the three technological paradigmatic stages; competition, diffusion and shift; from which it is found that wind-based hybrid energy systems appear to give better promising trajectory in the future than wind energy technologies that rely only on onshore or offshore winds. However, with market maturation, the challenges associated with increasing share, energy storage, motivational conflicts, demand responses and optimal scheduling emerge and are expected to be resolved. From the paradigm shift investigation, a comprehensive sustainable framework for a six-stage hybrid wind-photovoltaic energy system is proposed. Recommendations on policy shifts to encourage technological innovation, regional differentiation, improve monitoring & evaluation systems and the implementation of smart grid are also given to address the incentives that need to be provided.

Abstract Compared with traditional photovoltaic (PV) cells, bifacial PV cells can generate electricity on both sides. The study aims to research the electricity generation improvement of bifacial PV module as building envelope, and to find factors affecting its power generation performance in order to optimize it. A prefabricated building was renovated with two facades and the roof installed with bifacial PV modules. A test rig was established to monitor the electricity generation of the bifacial PV facades and roof, as well the indoor illuminance. It was found that the roof had the highest power generation per unit area. The electricity generation of bifacial PV module was simulated and validated. Through the simulation, the electricity improvement of the bifacial PV module was about 4.7%–18.8%. Then the simulation model was used to research the important factors to improve bifacial PV modules. The correlation between indoor light environment and bifacial PV power generation improvement is found. With the increase of reflectivity of the inner surface properly, the improvement of electricity was increased until the reflectivity of the ceiling reaches 0.8. In addition, the best coverage of bifacial PV was found. This study will provide optimization guidance for the application of bifacial PV modules in buildings envelope.

This paper presented a method of estimating voltage stability for an AC/DC system based on nonlinear programming analysis of voltage stability for an AC system, and built the AC /DC model. This method converts the calculation of point of collapse (PoC) of AC/DC systems to a problem of optimizing load, which is solved by Sequential Quadratic Programming method (SQP). The method can handle various inequality constraints with strong robustness and good convergence and consider the effects of different High Voltage Direct Current (HVDC) transmission control modes on voltage stability. Finally numerical examples proved the validity of the proposed model and algorithm.

The transverse-flux motor, which has the advantage of high torque density, has become one of the research focuses of direct-drive motors for low speed and high-torque industrial applications. This paper aimed to propose a transverse-flux flux-reversal motor with consequent-pole configuration (TF-CFRM), which has a robust rotor structure and provides high torque density by using fewer expensive NdFeB permanent magnets. Firstly, the basic structure and running work principle of the TF-CFRM are introduced. Secondly, the analytical expression of electromagnetic torque is derived from a simplified 3D-equivalent magnetic-circuit model. Then, the preliminary optimization of the basic dimension is accomplished by the finite element method to improve the torque density. At last, the electrical performances, e.g., the torque density, overload capability, and power factor of the proposed TF-CFRM are analyzed and compared with those of the transverse-flux flux-reversal motor (TF-FRM) and traditional flux-reversal motor (FRM).

Nowadays, the fine particle pollution is still severe in some megacities of China, especially in the Sichuan Basin, southwestern China. In order to understand the causes, sources, and impacts of fine particles, we collected PM2.5 samples and analyzed their chemical composition in typical months from July 2018 to May 2019 at an urban and a suburban (background) site of Chengdu, a megacity in this region. The daily average concentrations of PM2.5 ranged from 5.6-102.3 µg/m3 and 4.3-110.4 µg/m3 at each site. Secondary inorganics and organic matters were the major components in PM2.5 at both sites. The proportion of nitrate in PM2.5 has exceeded sulfate and become the primary inorganic component. SO2 was easier to transform into sulfate in urban areas because of Mn-catalytic heterogeneous reactions. In contrast, NO2 was easily converted in suburbs with high aerosol water content. Furthermore, organic carbon in urban was much greater than that in rural, other than elemental carbon. Element Cr and As were the key cancer risk drivers. The main sources of PM2.5 in urban and suburban areas were all secondary aerosols (42.9%, 32.1%), combustion (16.0%, 25.2%) and vehicle emission (15.2%, 19.2%). From clean period to pollution period, the contributions from combustion and secondary aerosols increased markedly. In addition to tightening vehicle controls, urban areas need to restrict emissions from steel smelters, and suburbs need to minimize coal and biomass combustion in autumn and winter.

Polymer flooding is an effective method widely applied for enhancing oil recovery (EOR) by reducing the mobility ratio between the injected water and crude oil. However, traditional polymers encounter challenges in high salinity reservoirs due to their salt sensitivity. To overcome this challenge, we synthesized a zwitterion polymer (PAMNS) with salt-induced tackifying property through copolymerization of acrylamide and a zwitterion monomer, methylacrylamide propyl-N, N-dimethylbutylsulfonate (NS). NS monomer is obtained from the reaction between 1,4-butanesultone and dimethylamino propyl methylacrylamide. In this study, the rheological properties, salt responsiveness, and EOR efficiency of PAMNS were evaluated. Results demonstrate that PAMNS exhibits desirable salt-induced tackifying characteristics, with viscosity increasing up to 2.4 times as the NaCl concentration reaches a salinity of 30 × 104 mg L−1. Furthermore, high valence ions possess a much stronger effect on enhancing viscosity, manifested as Mg2+ > Ca2+ > Na+. Molecular dynamics simulations (MD) and fluid dynamics experiment results demonstrate that PAMNS molecules exhibit a more stretched state and enhanced intermolecular associations in high-salinity environments. It is because of the salt-induced tackifying, PAMNS demonstrates superior performance in polymer flooding experiments under salinity ranges from 5 × 104 mg L−1 to 20 × 104 mg L−1, leading to 10.38–19.83% higher EOR than traditional polymers.

Chinese heating method has gradually shifted from small fragments to centralized regional heating. This heating method has achieved obvious energy-saving benefits. The article establishes an economic model of the energy utilization rate of the central heating system and installs the system exergy balance equation at the same time. The simulation found that the energy utilization coefficient of the heating system is high and has a high energy-saving potential. The effect of energy utilization is poor, and it has great potential for energy saving.