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2. On the quantification of the dissolved hydroxyl radicals in the plasma-liquid system using the molecular probe method

Author

Ma, Yupengxue, Gong, Xinning, He, Bangbang, Li, Xiaofei, Cao, Dianyu, Li, Junshuai, Xiong, Qing, Chen, Qiang, Chen, Bing Hui, and Liu, Qing Huo

Subjects
Physics - Chemical Physics, Physics - Plasma Physics
Abstract

Hydroxyl (OH) radical is the most important reactive species produced by the plasma-liquid interactions, and the OH in the liquid phase (dissolved OH radical, OHdis) takes effect in many plasma-based applications due to its high reactivity. Therefore, the quantification of the OHdis in the plasma-liquid system is of great importance, and a molecular probe method usually used for the OHdis detection might be applied. Herein we investigate the validity of using the molecular probe method to estimate the [OHdis] in the plasma-liquid system. Dimethyl sulfoxide is used as the molecular probe to estimate the [OHdis] in an air plasma-liquid system, and the partial OHdis is related to the formed formaldehyde (HCHO) which is the OHdis-induced derivative. The analysis indicates that the true concentration of the OHdis should be estimated from the sum of three terms: the formed HCHO, the existing OH scavengers, and the OHdis generated H2O2. The results show that the measured [HCHO] needs to be corrected since the HCHO destruction is not negligible in the plasma-liquid system. We conclude from the results and the analysis that the molecular probe method generally underestimates the [OHdis] in the plasma-liquid system. If one wants to obtain the true concentration of the OHdis in the plasma-liquid system, one needs to know the destruction behavior of the OHdis-induced derivatives, the information of the OH scavengers (such as hydrated electron, atomic hydrogen besides the molecular probe), and also the knowledge of the OHdis generated H2O2., Comment: 17 pages, 4 figures,3 tables

Published
2017
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4. Establishment and analysis of energy consumption model of heavy haul train on large long slope

Author

Lu Qiwei, He Bangbang, Wu Mingzhe, Zhang Zhichun, Luo Jiantao, and Zhang Yankui

Subjects
large long slope, heavy haul train, energy consumption, regenerative braking, Engineering geology. Rock mechanics. Soil mechanics. Underground construction, TA703-712, Mining engineering. Metallurgy, TN1-997
Abstract

AC heavy haul trains could produce a huge of regenerative braking energy when they are running on the long heavy down hill sections.It could reduce costs of coal transportation and improve the power quality if the regeneration braking energy can be used by uphill train in the same power supply section.In order to accurately predict the energy consumption and regenerative braking energy of heavy-haul trains on the large long slope, the single-particle dynamics model of train incoorpatrated with the simplification theory of railway longitudinal section, was used to establish the energy consumption and regenerative braking energy prediction model of a single train based on the train attributes, line condition and running speed.The model had been applied and verified in Shenshuo Railway.The results indicate that the error of the proposed model is generally less than 10%.The model lays a theoretical foundation for the follow-up train diagram layout work with the goal of reducing the total train energy consumption.

Published
2018
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5. Impedance Specifications for Stability Design of Grid-Connected DC Distribution Power Systems

Author

He, Bangbang, Chen, Wu, Zhang, Chun, Yuan, Yubo, and Zhang, Chenyu

Abstract

In practical application, it is more expected that the impedance-based stability criteria can provide intuitive system design guidance. However, the existing stability criteria for the complicated systems always aggregate all equipment/subsystem impedances. As a result, it is difficult to determine the port impedance specification that each equipment/subsystem should meet to ensure the system stability and a certain stability margin. In this article, the impedance specifications for the stability design of grid-connected dc distribution power systems are proposed. First, the stability conditions for impedance specification design are presented based on the dc-side subsystem impedance ratio criterion. On this basis, the ac-side admittance specifications and dc-side impedance specifications are proposed to ensure system stability. The former is used to constrain the ac-side admittance of voltage-source converter (VSC), and the latter restricts the dc-side impedance of grid-connected VSC and the input impedance of each converter-based load. The proposed impedance specifications are mainly related to grid impedance, transmission power, dc-bus voltage, two specific frequencies, and the required stability margin. As long as the proposed impedance specifications are met, the whole system must be stable and has sufficient stability margin. Finally, the case studies and experiments validate the proposed impedance specifications.

Published
2024
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6. Impedance-Based Stability of Grid-Connected DC Distribution Power Systems: AC- and DC-Side Stability Criteria, Equivalence, and Difference

Author

He, Bangbang, Chen, Wu, Zhang, Chun, Yuan, Yubo, and Zhang, Chenyu

Abstract

The impedance-based stability analysis methods for ac or dc electronic power systems are always separately reported. Even in hybrid ac–dc systems, few studies adopt both ac and dc stability criteria simultaneously, let alone discuss their correlation and differences. In this article, the small-signal stability of grid-connected dc distribution power systems is investigated at both ac and dc sides. First, by modeling the system’s input-to-output transfer functions, two equivalent-minor-loop-gain-based stability criteria without right-half-plane (RHP) poles are proposed, and their equivalence is mathematically proved. Then, the existing subsystems-based stability criteria are further proven to be equivalent to each other and to the equivalent-minor-loop-gain-based stability criteria. Meanwhile, the differences of all the aforementioned stability criteria are analyzed and discussed. Finally, sufficient case studies and experiments validate the proposed methods and viewpoints.

Published
2023
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