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Runoff change in the Yellow River Basin of China from 1960 to 2020 and its driving factors

Journal of Arid Land 2024年第2期16卷 168-194页

作者： WANG Baoliang WANG Hongxiang JIAO Xuyang HUANG Lintong CHEN Hao GUO Wenxian School of water Conservancy North China University of Water Resources and Electric PowerZhengzhou 450046China College of water Resources North China University of Water Resources and Electric PowerZhengzhou 450046China

Analysing runoff changes and how these are affected by climate change and human activities is deemed crucial to elucidate the ecological and hydrological response mechanisms of *** Indicators of Hydrologic Alteration and the Range of Variability Approach(IHA-RVA)method,as well as the ecological indicator method,were employed to quantitatively assess the degree of hydrologic change and ecological response processes in the Yellow River Basin from 1960 to *** Budyko's water heat coupling balance theory,the relative contributions of various driving factors(such as precipitation,potential evapotranspiration,and underlying surface)to runoff changes in the Yellow River Basin were quantitatively *** results show that the annual average runoff and precipitation in the Yellow River Basin had a downwards trend,whereas the potential evapotranspiration exhibited an upwards trend from 1960 to *** approximately 1985,it was reported that the hydrological regime of the main stream underwent an abrupt *** degree of hydrological change was observed to gradually increase from upstream to downstream,with a range of 34.00%-54.00%,all of which are moderate ***,significant differences have been noted among different ecological indicators,with a fluctuation index of 90.00%at the outlet of downstream hydrological stations,reaching a high level of *** the mutation,the biodiversity index of flow in the middle and lower reaches of the Yellow River was generally lower than that in the base *** research results also indicate that the driving factor for runoff changes in the upper reach of the Yellow River Basin is mainly precipitation,with a contribution rate of 39.31%-54.70%.Moreover,the driving factor for runoff changes in the middle and lower reaches is mainly human activities,having a contribution rate of 63.70%-84.37%.These results can serve as a basis to strengthen the protection and restoration efforts in the Yellow River Basin

关键词： Budyko theory hydrological regime attribution analysis ecological responses Yellow River climate change human activity runoff

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Research on Modeling and Parameter Identification of Comprehensive Load Model of Distribution Network in Industrial Park

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Chinese Journal of Electronics 2024年第1期33卷 264-273页

作者： Tingling WANG Xiaohe YAN School of Electric Engineering North China University of Water Resources and Electric Power Wenzhou Polytechnic

With the rapid development of industrial parks, its load model research has become a hot spot. In order to study the load of power system in industrial park, based on the characteristics of the industrial park load, a comprehensive load admittance static model with full voltage range adaptability is considered, and a comprehensive load model of distribution network of the industrial park is established. A complete parameter identification of the model is carried out through chaos particle swarm optimization. The simulation results show that the model can effectively describe the load characteristics of the distribution network in industrial parks.

关键词： Chaos Adaptation models Analytical models Parameter estimation Induction motors Simulation Distribution networks

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Effective removal of Sb(V)from aqueous solutions by micro-electrolysis with composite scrap iron-manganese as filler

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Journal of Zhejiang university-Science A(Applied Physics & Engineering) 2024年第6期25卷 516-524页

作者： Shangkun DING Saihua HUANG Yiping ZHANG Yongchao ZHOU Institute of Municipal Engineering Zhejiang UniversityHangzhou310058China Zhejiang university of water Resources and Electric power Hangzhou310018China

Micro-electrolysis(ME)technology is investigated for improving the efficiency of removal of pentavalent antimony(Sb(V))from the *** this study,an ME system composed of scrap iron filings,waste manganese fillings,and activated carbon(Fe-Mn-C ME)was used to efficiently remove Sb(V).The results proved that,compared with conventional iron-carbon micro-electrolysis(Fe-C ME),Fe-Mn-C ME significantly enhances the removal rate of Sb(V)when the hydraulic retention time is 10–24 *** Fe-Mn flocs produced by this system were analyzed using X-ray diffraction(XRD),energy-dispersive X-ray spectroscopy(EDS),X-ray photoelectron spectroscopy(XPS),and Brunauer-Emmett-Teller(BET)surface area analysis,which revealed that the flocs were mostly Mn-substituted FeOOH and had a relatively larger specific surface area,providing better adsorption ***,it was found that the removal rate of Sb(V)decreased as the iron-carbon mass ratio increased,while it first increased and then decreased as the manganese content *** reduction of Fe(III)was accelerated with an increase in the addition of manganese,leading to an increase in the concentration of Fe(II).The electron transfer and the formation of Fe(II)were facilitated by the potential difference between manganese and carbon,as well as by the formation of microcells between iron and manganese,which improved the reduction ability of Sb(V).From our thorough investigation and research,this is the first report that has proposed Fe-Mn-C ME for removing *** provides a novel approach and technological support for removing Sb(V)efficiently.

关键词： Antimony Iron Manganese Micro-electrolysis(ME) Electrochemistry Mechanism

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Research progresses of nanomaterials as lubricant additives

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Friction 2024年第7期12卷 1347-1391页

作者： Zhengquan JIANG Yankun SUN Bokang LIU Laigui YU Yuping TONG Mingming YAN Zhongzheng YANG Yongxing HAO Linjian SHANGGUAN Shengmao ZHANG Weihua LI School of Materials Science and Engineering North China University of Water Resources and Electric PowerZhengzhou 450045China Institute of Special Friction and Lubricating Materials North China University of Water Resources and Electric PowerZhengzhou 450045China Nanomaterials Engineering Research Center Henan UniversityKaifeng 475001China School of Mechanical Engineering North China University of Water Resources and Electric PowerZhengzhou 450045China

Friction and wear are unavoidable in mechanical *** use of lubricants with nano-additives can effectively reduce friction and wear,which is of great significance to saving energy and protecting the *** present,great progress has been made in the scientific research and industrial application of nano-additives for *** paper mainly introduces the types of nano-additives for lubricants(such as carbon nanomaterials,nano-metals,nano-oxides,sulfides,complexes,polymers,etc.),the tribological properties of lubricants with different components of nano-additives,and the lubrication mechanisms of the nano-additives(including tribofilm formation,rolling ball bearing effect,repairing effect,polishing effect,and synergistic effect).It also deals with the dispersion of nano-additives in lubricants and the influences of their particle size and microstructure on the tribological properties of *** review outlines the performance requirements of nano-additives in different lubrication states,discusses the use of nano-additives in challenging working conditions,and identifies various industrial oil nano-additives with reference to the appropriate options in diverse working ***,the existing problems of nano-additives and their application prospects are *** review,hopefully,would help to shed light on the design and synthesis of novel high-performance nano-additives and promote their application in engineering.

关键词： nanomaterials lubricant additive lubrication mechanism research progress

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Scattering of water Waves by Dual Symmetric Inclined Floating Porous Barriers Using the DBEM

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China Ocean Engineering 2024年第1期38卷 156-168页

作者： WANG Li-xian DENG Yan-wen YE Yang-sha DENG Zheng-zhi Key Laboratory of High Performance Ship technology(Wuhan university of technology) Ministry of EducationWuhan 430063China School of Naval Architecture Ocean and Energy Power EngineeringWuhan University of TechnologyWuhan 430063China Key Laboratory of water-Sediment Sciences and water Disaster Prevention of Hunan Province Changsha 410114China Institute of Port Coastal and Offshore EngineeringZhejiang UniversityZhoushan 316021China

The scattering of normally incident water waves by two surface-piercing inclined perforated barriers in water with a uniform finite depth is investigated within the framework of linear water wave *** that thin barriers are zero-thickness,a novel numerical method involving the the coupling of the dual boundary element method(DBEM)with damping layers is *** order to effectively damp out the reflected waves,two damping layers,instead of pseudoboundaries are implemented near the two side boundaries of the computational ***,the modified linearized free surface boundary conditions are formulated and used for solving both the ordinary boundary integral equation as well as the hypersingular boundary integral equation for degenerate *** newly developed numerical method is validated against analytical methods using the matched eigenfunction expansion method for the special case of two vertical barriers or the inclined angle to the vertical being *** influence of the length of the two damping layers has been ***,these findings are also validated against previous results for several *** validation,the numerical results for the reflection coefficient,transmission coefficient and dissipation coefficient are obtained by varying the inclination angle and porosity-effect *** effects of both the inclination angle and the porosity on the amplitudes of wave forces acting on both the front and rear barriers are also *** is found that the effect of the inclination angle mainly shifts the location of the extremal values of the reflection and the transmission ***,a moderate value of the porosity-parameter is quite effective at dissipating wave energy and mitigating the wave loads on dual barriers.

关键词： dual boundary element method inclined perforated floating breakwater reflection coefficient transmission coefficient damping layer

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Modeling and Simulation of Lithium Vacuum Evaporation Process Using COMSOL Multiphysics

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Journal of Thermal Science 2024年第1期33卷 86-100页

作者： LIAN Xuexin ZHONG Dawen Beijing Key Laboratory of Passive Nuclear power Safety and technology North China Electric Power UniversityBeijing 102206China

Based on the COMSOL Multiphysics simulation software,this study carried out modeling and numerical simulation for the evaporation process of liquid metal lithium in the vacuum free molecular flow *** motion of lithium atoms in the evaporation process was analyzed through a succession of *** on the available experimental values of the saturated vapor pressure of liquid metal lithium,the relationship between saturated vapor pressure and temperature of liquid lithium in the range of 600 K-900 K was obtained.A two-dimensional symmetric model(3.5 mm×20 mm) was established to simulate the transient evaporation process of liquid lithium at wall temperatures of 750 K,780 K,800 K,810 K,825 K,and 850 K,*** effects of temperature,the evaporation coefficient,back pressure,and length-to-diameter ratio on the evaporation process were studied;the variation trends and reasons of the molecular flux and the pressure during the evaporation process were *** the same time,the evaporation process under variable wall temperature conditions was *** research made the evaporation process of liquid lithium in vacuum molecular flow clearer,and provided theoretical support for the space reactor and nuclear fusion related fields.

关键词： free molecular flow saturated vapor pressure vacuum evaporation liquid lithium metal

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High power Density EV Integrated Fast Battery Chargers Based on the General Torque Cancelation Law for Three-Phase Motors

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CSEE Journal of power and Energy Systems 2024年第2期10卷 756-766页

作者： Yanxiong Lei Guiping Du Tuhuan Li Wenjie Ma Xueyi Wang School of Electric power South China University of TechnologyGuangzhou 510641China

Integrated battery chargers are highly effective for saving costs and improving the power density of on-board chargers in electric vehicles (EVs), However, achieving torque elimination of the commonly used three-phase (3p) motors during the fast-charging process is challenging. In this paper, the general torque cancelation law applied in 3p permanent magnet synchronous motors (PMSMs) and induction motors (IMs) is derived to design high power density integrated fast battery chargers. Two novel integrated systems with fast-charging and vehicle-to-grid (V2G) capabilities are proposed based on this law. The main advantages of the proposed systems are: (1) Two filter inductors are constituted by the stator windings while charging, and only one external inductor and several contactors are supplemented to the motor-drive circuit. Therefore, the proposed integrated systems possess high power density;(2) The 3p open-winding (OW) motor is employed, with no need to modify the propulsion system or redesign the interior structure of the motor;(3) Employing an individual controller for each phase of the inner current loop control, the proposed systems realize unity power factors and low current harmonics in the fast-charging and V2G mode. Simulation and experimental results verify the feasibility of the proposed topologies and control strategies.

关键词： Electric vehicles(EVs) fast charging integrated battery charger 3p PMSM/IM torque cancelation

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Removal of pathogenic indicator microorganisms during partial nitrification:the role of free nitrous acid

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Frontiers of Environmental Science & Engineering 2024年第3期18卷 93-102页

作者： Jiaojiao Xu Xiaotian Chen Rui Tang Jingwei Feng Shoujun Yuan Wei Wang Zhen-Hu Hu Anhui Engineering Laboratory of Rural water Environment and Resource School of Civil EngineeringHefei University of TechnologyHefei 230009China Hefei 168 High School Hefei 230025China Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric power Shanghai University of Electric PowerShanghai 200090China

Digested wastewater contains pathogenic microorganisms and high ammonia concentrations,which can pose a potential risk to public *** removal of pathogens and nitrogen is crucial for the post-treatment of digested *** nitrification-anammox is an energy-saving nitrogen removal *** nitrous acid(FNA),an intermediate product of partial nitrification,has the potential to inactivate ***,the efficiency and mechanisms of FNA-related inactivation in pathogens during partial nitrification remains *** this study,Enterococcus and Escherichia coli(***)were selected to investigate the efficiency and mechanisms of FNA-related inactivation in partial nitrification *** results revealed that 83%±13%and 59%±27%of *** and Enterococcus were removed,respectively,in partial nitrification process at FNA concentrations of 0.023−0.028 mg/*** the concentration of FNA increased from 0 to 0.5 mg/L,the inactivation efficiencies of *** and Enterococcus increased from 0 to 99.9%and 89.9%,*** exhibited a higher resistance to FNA attack compared to ***.3D-laser scanning microscopy(3D-LSM)and scanning electron microscopy(SEM)revealed that FNA exposure caused the surface collapse of *** and Enterococcus,as well as visible pore formation on the surface of *** cells.4',6-Diamidino-2-phenylindole dihydrochloride n-hydrate(DAPI)/propidium iodide(PI)and biomolecule leakage confirmed that inactivation of *** and Enterococcus occurred due to breakdown of cell walls and cell *** findings indicate that partial nitrification process can be used for the removal of residual pathogenic microorganisms.

关键词： Partial nitrification Free nitrous acid Pathogenic indicator microorganism Inactivation Cell structure

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Features and formulae of sediment incipient motion in vegetated flow environment

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Journal of Hydrodynamics 2024年第2期36卷 331-339页

作者： Yu-xuan Xu Wei-jie Wang Shi-bao Zhang Han-qing Zhao Xue-kai Chen Hai-ping Zhang School of water Conservancy North China University of Water Resources and Electric PowerZhengzhou450045China State Key Laboratory of Simulation and Regulation of water Cycle in River Basin China Institute of Water Resources and Hydropower ResearchBeijing100038China China Three Gorges Corporation Wuhan430010China

Aquatic vegetation is a vital component of natural river ecosystems,playing a crucial role in maintaining ecological balance,providing habitat and improving water ***,the presence of vegetation results in increased resistance in vegetated channels compared with non-vegetated channels,rendering traditional sediment movement predictions inadequate for the ***,the concept of a vegetation influence factor,denoted by CDah,has been proposed by previous researchers to represent the effect of vegetation on sediment movement in *** this study,we focus on exploring the vegetation resistance coefficient(CD)among the vegetation influence factors,evaluating two different calculation methods for vegetation resistance coefficient,and presenting two expressions through genetic algorithm analysis to predict the incipient flow velocity of sediment in vegetated *** predicted values from the new formulae show excellent agreement with measured data,highlighting the high accuracy of the proposed methods in predicting the incipient flow velocity of *** results provide a solid theoretical basis for understanding the influence of aquatic vegetation on sediment particle movement.

关键词： Vegetation flow vegetation resistance coefficient genetic algorithm sediment initiation

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Energy Planning of Beijing Towards Low-carbon,Clean and Efficient Development in 2035

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CSEE Journal of power and Energy Systems 2024年第3期10卷 913-928页

作者： Chengzhou Li Ningling Wang Xiaohu Shen Yumeng Zhang Zhiping Yang Xiaofeng Tong François Maréchal Ligang Wang Yongping Yang Institute of Energy power Innovation North China Electric Power UniversityBeijing 102206China School of Energy Power and Mechanical Engineering and National Research Center for Thermal Power Engineering and TechnologyNorth China Electric Power UniversityBeijing 102206China Industrial Process and Energy Systems Engineering Swiss Federal Institute of Technology in LausanneSionSwitzerland

Energy transition towards clean,efficient energy supply has been a common sense of the government and public in ***,lacking reasonable planning will lead to undisciplined development,resource waste,and excessive *** this context,this paper investigates potential pathways of Beijing energy transition towards a high-level low-carbon,clean and efficient energy system in 2035 with an extended energysocpe ***,based on available data,future energy demands are predicted by a newly proposed hybrid forecasting method,which combines the traditional regression model,grey model,and support vector machine model with an entropy-based weighted ***,the superstructure-based optimization model is employed to investigate the system configuration and operation strategy of the future Beijing energy ***,the uncertainty impact of electricity price,natural gas price,hydrogen price,and the capital expenditures of electrolyzer and steam methane reforming for hydrogen applications are *** forecasting results show that all walks of life will witness a continuously increasing energy demand in multiple sectors of Beijing towards *** planning results suggest that the imported electricity and natural gas will dominate the energy supply of Beijing in 2035 with a contribution of 86%of the energy resources consumption of 384 ***,the energy system presents a high end-use electrification level of 65%and high penetration of efficient technologies,which supply 119 TWh via combined heat and power,26 TWh via heat pump and 95 TWh via district heating *** energy use of various sectors of energy resources,technologies and end-use are closely *** will have an increased penetration in the private mobility sector,but the locally generated hydrogen is mainly from steam methane reforming technology.

关键词： Energy transition energy planning carbonneutral demand forecasting energyscope

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