Unlike the traditional traction power supply system which enables the electrified railway traction sub- station to be connected to power grid in a way of phase rotation, a new generation traction power supply system w...Unlike the traditional traction power supply system which enables the electrified railway traction sub- station to be connected to power grid in a way of phase rotation, a new generation traction power supply system without phase splits is proposed in this paper. Three key techniques used in this system have been discussed. First, a combined co-phase traction power supply system is applied at traction substations for compensating negative sequence current and eliminating phase splits at exits of substations; design method and procedure for this system are presented. Second, a new bilateral traction power supply technology is proposed to eliminate the phase split at section post and reduce the influence of equalizing current on the power grid. Meanwhile, power factor should be adjusted to ensure a proper voltage level of the traction network. Third, a seg- mental power supply technology of traction network is used to divide the power supply arms into several segments, and the synchronous measurement and control technology is applied to diagnose faults and their locations quickly and accurately. Thus, the fault impact can be limited to a min- imum degree. In addition, the economy and reliability of the new generation traction power supply system are analyzed.展开更多
In large cities,multi-source and multi-plant water supply,while effectively alleviating water shortage,poses notable challenges.In such systems,source switching alters dissolved organic matter(DOM)and microbial commun...In large cities,multi-source and multi-plant water supply,while effectively alleviating water shortage,poses notable challenges.In such systems,source switching alters dissolved organic matter(DOM)and microbial communities,whose interaction can destabilize water quality,cause pipe corrosion,form biofilms,and generate harmful by-products,thus threatening supply safety.However,the impact of DOM on microbial communities in water supply systems(WSS)has been less studied.To address this problem,EEM-PARAFAC,bioinformatics,and multivariate statistical analysis were used to get an in-depth understanding of the interaction between DOM and microbial communities.In this study,by analyzing the fluorescence index in the whole process,the DOM from source to tap showed weak humification and a strong autochthonous source.The flocculation process preferentially removed humus components.Moreover,water treatment processes(particularly chlorination)were found to significantly reduce microbial richness by 60.88%and alter community structure composition.Community assembly was largely explained by stochastic processes in subgroups.This stochasticity leads to diverse community structures under different environmental conditions,highlighting the complexity of microbial community formation.In water distribution network,microorganisms were the most stable(lowest AVD index,0.029),followed by raw water(0.046)and the water treatment plant(0.065).The variations of fulvic-like acid and humic-like acid were considered the key components that need to be paid attention to in the whole process of WSS.This study provided insights into monitoring and managing multi-source multi-water plants WSS schemes.展开更多
基金supported by the National Natural Science Funds of China (Nos. 51307143 and 51307142)Technology Research and Development Program of China Railway Corporation (No. 2014J009-B)
文摘Unlike the traditional traction power supply system which enables the electrified railway traction sub- station to be connected to power grid in a way of phase rotation, a new generation traction power supply system without phase splits is proposed in this paper. Three key techniques used in this system have been discussed. First, a combined co-phase traction power supply system is applied at traction substations for compensating negative sequence current and eliminating phase splits at exits of substations; design method and procedure for this system are presented. Second, a new bilateral traction power supply technology is proposed to eliminate the phase split at section post and reduce the influence of equalizing current on the power grid. Meanwhile, power factor should be adjusted to ensure a proper voltage level of the traction network. Third, a seg- mental power supply technology of traction network is used to divide the power supply arms into several segments, and the synchronous measurement and control technology is applied to diagnose faults and their locations quickly and accurately. Thus, the fault impact can be limited to a min- imum degree. In addition, the economy and reliability of the new generation traction power supply system are analyzed.
基金the National Key R&D Program of China(No.2023YFC3207000)the National Natural Science Foundation of China(No.52470183)the Natural Science Foundation of Jiangsu Province,China(No.BK20240085)for the support of this work.
文摘In large cities,multi-source and multi-plant water supply,while effectively alleviating water shortage,poses notable challenges.In such systems,source switching alters dissolved organic matter(DOM)and microbial communities,whose interaction can destabilize water quality,cause pipe corrosion,form biofilms,and generate harmful by-products,thus threatening supply safety.However,the impact of DOM on microbial communities in water supply systems(WSS)has been less studied.To address this problem,EEM-PARAFAC,bioinformatics,and multivariate statistical analysis were used to get an in-depth understanding of the interaction between DOM and microbial communities.In this study,by analyzing the fluorescence index in the whole process,the DOM from source to tap showed weak humification and a strong autochthonous source.The flocculation process preferentially removed humus components.Moreover,water treatment processes(particularly chlorination)were found to significantly reduce microbial richness by 60.88%and alter community structure composition.Community assembly was largely explained by stochastic processes in subgroups.This stochasticity leads to diverse community structures under different environmental conditions,highlighting the complexity of microbial community formation.In water distribution network,microorganisms were the most stable(lowest AVD index,0.029),followed by raw water(0.046)and the water treatment plant(0.065).The variations of fulvic-like acid and humic-like acid were considered the key components that need to be paid attention to in the whole process of WSS.This study provided insights into monitoring and managing multi-source multi-water plants WSS schemes.
