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Effect of blade shape on hydraulic performance and vortex structure of vortex pumps

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Journal of Hydrodynamics 2018年第3期30卷 499-506页

作者： Ya-ping Ju Si Liu Chu-hua Zhang School of Energy and power engineering Xi ＇an Jiaotong University Xi ＇an 710049 China Shanghai Turbine Works Shanghai Electric Power Generation Equipment Co. Ltd. Shanghai 200240 China

The vortex pump has increasingly become an important alternative or supplement to the centrifugal pump, the positive displacement pump and the diffusion pump due to its capacity of developing a high head at a small flow rate within a single stage. However, the vortex pumps with various blade shapes such as the twisted blades or the 3-D blades are not well studied. In this paper, some new concepts of the 2-D and 3-D corner blades are introduced for the design of the vortex pumps. The mechanism behind the effect of the corner blade shapes on the pump hydraulic performance is numerically investigated and elucidated in terms of the internal vortex structures. The results show that both 2-D and 3-D forward corner blades can induce stronger well-organized longitudinal vortices as well as smaller axial and radial vortices within the impeller blade passage, which benefit a higher pump head and a higher efficiency in comparison with the traditional radial straight blade. This study provides useful guidelines for the design of advanced vortex pumps.

关键词： Vortex pump corner blade hydraulic performance vortex structure CFD simulation

Joint user pairing and power allocation in multi-slicing NOMA system

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The Journal of china Universities of Posts and Telecommunications 2021年第3期28卷 28-35页

作者： Bao Jie Zheng Weijun Shao Weiping Ma Tengteng Qie Wenbo Zhang Yong School of Electronic engineering Beijing University of Posts and TelecommunicationsBeijing 100876China Jiaxing power Supply company State Grid Zhejiang Electric Power Co.Ltd.Jiaxing 314033China State Grid Zhejiang electric power co. Ltd.Hangzhou 310007China

Joint user pairing and power allocation approach is investigated to meet the rate requirement of enhanced mobile broadband(eMBB)slicing and delay constraint of ultra-reliable low-latency communication(URLLC)slicing simultaneously in downlink non-orthogonal multiple access(NOMA)*** maximizing the proportional fairness among mobile terminals,a two-step algorithm is *** a given user sets,the optimal user pairing sets and the factor of the power allocation in a group were obtained to ensure the quality of service(QoS)and the isolation between different types of *** results show that the proposed joint algorithm can provide better throughput than orthogonal multiple access(OMA).

关键词： non-orthogonal multiple access(NOMA) network slicing power allocation user pairing

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End-to-end encrypted network traffic classification method based on deep learning

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The Journal of china Universities of Posts and Telecommunications 2020年第3期27卷 21-30页

作者： Tian Shiming Gong Feixiang Mo Shuang Li Meng Wu Wenrui Xiao Ding Department of power consumption and Energy Efficiency China Electric Power Research Institute Co.Ltd.Beijing 100192China School of com puter Science Beijing University of Posts and Telecom municationsBeijing 100876China State Grid corporation of china Beijing 100031China

Network traffic classification,which matches network traffic for a specific class of different granularities,plays a vital role in the domain of network administration and cyber *** the rapid development of network communication techniques,more and more network applications adopt encryption techniques during communication,which brings significant challenges to traditional network traffic classification *** the one hand,traditional methods mainly depend on matching features on the application layer of the ISO/OSI reference model,which leads to the failure of classifying encrypted *** the other hand,machine learning-based methods require human-made features from network traffic data by human experts,which renders it difficult for them to deal with complex network *** this paper,the convolution attention network(CAT)is proposed to overcom those *** an end-to-end model,CAT takes raw data as input and returns classification results automatically,with engineering by human *** CAT,firstly,the importance of different bytes with an attention mechanism of network traffic is ***,convolution neural network(CNN)is used to learn features automatically and feed the output into a softmax function to get classification *** enables CAT to learn enough information from network traffic data and ensure the classified *** experiments on the public encrypted network traffic dataset ISCX2016 demonstrate the effectiveness of the proposed model.

关键词： network traffic classification convolution neural network attention mechanism network management cyber security

FeWO4 nanorods with excellent UV–Visible light photocatalysis

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Progress in Natural Science:Materials International 2017年第5期27卷 556-560页

作者： Qunxiang Gao Zhijian Liu Department of power engineering North China Electric Power University

FeWO4nanorods were synthesized through a hydrothermal progress with the assistant of L-cysteine. The synthesized FeWO4nanorods were characterized by X-ray powder diffraction, Raman spectrometer, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy,energy-dispersive X-ray spectroscope and X-ray photoelectron spectroscopy. The optical property, photocatalytic activity and magnetic property of the synthesized FeWO4nanorods were investigated. The photodecomposition of Methyl orange for FeWO4nanorods depends on the wavelength of the irradiating light. Under ultraviolet-visible light irradiation, FeWO4nanorods show higher photocatalytic activity for the decomposition of Methyl orange than that of ultraviolet light irradiation. A possible mechanism of FeWO4on the decomposition of Methyl orange was proposed. The value of Néel temperature is lower than that of bulk FeWO4, which is associated with the size effects and the shape of the synthesized FeWO4nanorods.

关键词： FeWO4 Nanorods Photocatalysis

Impact of Long-Term Transactions on Strategic Bidding in the electricity Market

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CSEE Journal of power and Energy Systems 2023年第6期9卷 2090-2098页

作者： Tianyao Ji Yueyong Yang Zhaoxia Jing School of electric power engineering South China University of TechnologyGuangzhouChina

power producers'profits are determined by the market price in the electricity market and therefore they will adopt certain strategies in market transactions to achieve higher *** an electricity spot market that adopts uniform pricing,power producers with considerable generation capacity are able to exercise their market power,given that the market concentration is relatively high at the beginning of market *** has been proved that an effective bidding strategy can increase the market clearing prices,so as to increase the profits of the power ***,the introduction of long-term transactions may mitigate the impact of producers'market power,as a great amount of long-term volume is settled at the long-term contract price,which is determined in advance and is less fluctuating than the spot *** forms of long-term transactions,the fixed volume contract and the varied volume contract,are studied in this *** studies are conducted on a multi-agent platform,where both the long-term and spot transactions of power producers are included,and the total profits of a power producer with or without long-term transactions are analyzed to demonstrate their ***,the results clearly show that long-term transactions can effectively prevent power producers from exercising market power.

关键词： electricity market long-term transaction spot transaction strategic bidding

Evolutionary Game-theoretic Analysis for Residential Users considering Integrated Demand Response

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Journal of Modern power Systems and Clean Energy 2021年第6期9卷 1500-1509页

作者： Bingtuan Gao Chen Chen Yanhui Qin Xiaofeng Liu Zhenyu Zhu School of electrical engineering Southeast University electric power Research Institute of State Grid Xinjiang electric power co. Ltd. School of electrical engineering Nanjing Normal University

As an important part of demand side,residential users have the characteristics of imperfect rationality and strong randomness,which are rarely considered in the existing ***,to effectively improve the energy efficiency,integrated demand response(IDR)is proposed as an effective measure to reduce the local energy supply *** paper focuses on a scenario for IDR programs,in which the intelligent building aggregator(IBA)wants to encourage residential users to participate in IDR according to a proper contract price *** analyze how the participation degree tendency evolves over time,an evolutionary game approach is proposed considering residential users’bounded-rationality.A symmetric evolutionary game model and an asymmetric evolutionary game model are established,and the stability of equilibrium points in the above models is *** results show that different contract price policies will obviously influence residential users’strategy,and affect the stable equilibrium points of the evolutionary *** simulation results provide an effective reference for IBA to set proper and effective price incentives.

关键词： contract price evolutionary game intelligent community energy consumption behavior integrated demand response(IDR)

Pitch control strategy before the rated power for variable speed wind turbines at high altitudes

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Journal of Hydrodynamics 2019年第2期31卷 379-388页

作者： Ming-wei Ge Wei-ming Ke Hong-xia Chen School of Renewable Energy North China Electric Power UniversityBeijingl 02206China School of Energy power and Mechanical engineering North China Electric Power UniversityBeijing 102206China

The wind turbines in the world's highest wind farm with an altitude of over 4 000 m in Naqu county of china were put into operation in *** with the wind turbines at lower altitudes,the rated wind speed of these wind turbines are much larger,and the corresponding tip-speed ratio at the rated power reduces significantly due to the lower air ***,the power coefficient at the point of the rated power is decreased to a rather low *** improve the performance of the wind turbines at very high altitudes,this paper proposes a new pitch control strategy for variable speed wind turbines at the constant-speed phase,especially at the rated-speed phase before the rated power is *** is shown that the new pitch control strategy works very well for the wind farms at very high altitude and with low air density,with the catch of the wind energy enhaneed and the aerodynamic loads significantly reduced.

关键词： Wind turbine pitch control strategy high altitudes

The bubble formation characteristics of oil‐paper insulation and its influence on insulation performance

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High Voltage 2023年第5期8卷 1030-1040页

作者： Yiyi Zhang Qianlun Du Wenchang Wei Wenqiang Wang Gang Wang Yansong Liu Qing Xie Guangxi power Transmission and Distribution Network Lightning Protection engineering Technology Research Center Guangxi UniversityNanningChina electric power Research Institute Guangxi Power Grid Co.Ltd.NanningChina State Key Laboratory of Alternate electrical power System with Renewable Energy Sources North china electric power University BaodingChina

engineering experience shows that for transformers with long service life and serious moisture exposure,the inter‐turn paper insulation inside the winding will precipitate bubbles under the condition of electric field and conductor heating,which will endanger the equipment *** order to explore the influence factors of bubbles formation in the moist insulating paper of transformers,based on the existing research on the influence of moisture content and gas dissolution in transformer oil,this study further considers the influence of air pressure(AP)and electric field and establishes an experimental platform to change the air pressure and electric field,thereby studying the formation characteristics of bubbles in oil‐paper *** results show that air pressure and electric field can affect the initial temperature,volume,and shape of bubble *** 0 to−0.05 MPa for air pressure,the initial temperature of bubble generation decreased by 41℃,its maximum two‐dimensional projected area increased by 418.4%with more severe distortion,and the breakdown voltage *** the AC voltage applied on the needle plate electrode increased from 0 to 10 kV,the initial temperature of bubble formation increased by 29℃,and the maximum two‐dimensional projection area increased by 336.6%.

关键词： bubble insulation characteristics

Quantum steerability of two qubits mediated by one-dimensional plasmonic waveguides

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Chinese Physics B 2022年第12期31卷 74-80页

作者： Ye-Qi Zhang Xiao-Ting Ding Jiao Sun Tian-Hu Wang Department of Mathematics and Physics North China Electric Power UniversityBeijing 102206China School of Energy power and Mechanical engineering North China Electric Power UniversityBeijing 102206China

We study the dynamics of the quantum steering between two separated qubits trapped in a one-dimensional plasmonic *** numerical methods,we calculate the quantum steerability and other quantum correlations,i.e.,entanglement,discord,and coherence,for both cases with and without laser driving *** is found that steerability may exhibit a sudden disappearance and sudden reappearance ***,there exist time windows with no steerability but finite *** effects of plasmon wavenumber and the distance between the two qubits on steerability are also ***,we show that quantum steerability is tunable by adjusting the laser driving fields.

关键词： quantum steering quantum correlations plasmonic waveguide