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Journal of Modern Power Systems and Clean Energy 2024年第2期12卷 646-657页

作者： Juanjuan Wang Wei chen Yuekun Liu Chuang fu Yunming Ye Junjie Feng School of Electric Power South China University of TechnologyGuangzhouChina Guangdong Power Grid Co. Ltd.GuangzhouChina Electric Power Research Institute China Southern Power GridGuangzhouChina

In recent years, high-frequency resonance (HFR) events occurred in several modular multilevel converter based high-voltage direct current (MMC-HVDC) projects. The time delay of an MMC-HVDC system is the critical factor that induces HFR. The frequency coupling affects the impedance characteristics of an MMC and further deteriorates system stability. Therefore, in this paper, a multi-input multi-output admittance model of an MMC-HVDC system is developed to analyze its frequency characteristics. The effects of current loop, power loop, phase-locked loop, and operating point on the MMC frequency coupling degree are analyzed in detail. Meanwhile, to further suppress HFR in the MMC-HVDC system, an enhanced impedance reshaping control strategy based on the equivalent single-input single-output impedance model is proposed. Finally, the accuracy of the enhanced impedance model and the effectiveness of the impedance reshaping control are verified by electromagnetic transient simulations in PSCAD.

关键词： Modular multilevel converter based high-voltage direct current(MMC-HVDC) high-frequency resonance frequency coupling impedance model impedance reshaping control

Selective recovery of Th(Ⅳ) from radioactive rare earth waste residue by utilizing MoS_(2)-modified ion-absorbed type rare earth tailings

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Journal of Rare Earths 2024年第9期42卷 1782-1791,I0005页

作者： Xirong chen Xinyu fu Yun Gao Zhiyuan Zeng Bin Huang Xiaoqi Sun Faculty of Materials Metallurgy and Chemistry Jiangxi University of Science and TechnologyGanzhou341000China CAS Key Laboratory of Design and Assembly of functional Nanostructures Fujian Key Laboratory of NanomaterialsFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou350002China fujian Research Center for Rare Earth Engineering Technology Xiamen Institute of Rare Earth MaterialsHaixi InstituteChinese Academy of SciencesXiamen361021China fujian College University of Chinese Academy of SciencesFuzhou350002China Jiangxi Province Key Laboratory of Cleaner Production of Rare Earths Ganjiang Innovation AcademyChinese Academy of SciencesGanzhouJiangxi341000China

In the process of extracting ion-absorbed rare earth ore(IREO),the production of radioactive waste is a major environmental *** address this issue,MoS_(2) was used to modify ion-absorbed rare earth tailings(RET) to synthesize a novel MoS_(2)@RET composite material for the effective handling of radioactive waste generated in IREO separation *** composite material was thoroughly characterized using various analytical techniques,including X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),thermogravimetry(TG),Fourier-transform infrared(FTIR),scanning electron microscopy(SEM),Brunaue r-Emmett-Teller(BET) and energy dispersive spectroscopy(EDS).By optimizing the operating parameters,the optimal experimental conditions were determined to be pH=3,contact time=60 min,liquid-solid ratio=6 g/L,and initial concentration=150 mg/*** adsorption data fitted well with the pseudo second-order rate *** thermodynamic parameters concerning the adsorption of Th(Ⅳ) were analyzed and *** isotherm model is a more fitting choice for the adsorption process compared to the Freundlich isotherm ***_(2)@RET was used in the acid leachate of IREO waste residue,achieving the separation of Th and rare earth *** mechanism of Th(Ⅳ) adsorption by MoS_(2)@RET was investigated,revealing that the adsorption process involves electrostatic interactions,chemical bonding,and redox *** above research results indicate that MoS_(2)@RET composite materials have application potential in the sustainable treatment of IREO radioactive waste.

关键词： Rare earths Thorium Radioactive waste residue Adsorption Separation

Pore Formation Mechanism in W-C Hard Coatings Using Directed Energy Deposition on Tungsten Alloy

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Acta Metallurgica Sinica(English Letters) 2024年第1期37卷 89-101页

作者： Xinrui Zhang Weijie fu chen Wang Zhenglong Lei Haoran Sun Xudong Li State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin150001China

Porosity is a common phenomenon and can significantly hinder the quality of the ***,the pore formation mechanism and the characteristics of the single tracks of the W-C coating using directed energy deposition(DED)are systematically *** forming quality of the tracks,the distribution of the pores,and the elemental distribution near the pores are analyzed by the observations of the cross-sections of the *** temperature field of the melt pool is discussed comprehensively to reveal the pore formation *** results confirm that Ni and Co evaporated during the DED process due to the high temperature of the melt *** were continuously produced adjacent to the fusion line when the melt pool was about to solidify since the temperature at the solidification front was higher than the boiling point of *** vaporization area at the fusion line was proposed,where Ni could also evaporate at the time the melt pool started to *** relationship between the solidification rate,the size of the vaporization area and the DED parameters(laser power and scanning speed)was established to discuss the causes of severe pores above the fusion *** work contains a practical guide to reduce or eliminate the porosity in the coating preparation process on the surface of the tungsten alloy.

关键词： Directed energy deposition(DED)process Tungsten alloy W-C coating Pores Binder phase

Reactive molecular dynamics insight into the thermal decomposition mechanism of 2,6-Bis(picrylamino)-3,5-dinitropyridine

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Defence Technology（防务技术） 2024年第3期33卷 134-146页

作者： Jianbo fu Hui Ren Xinzhou Wu Yongjin chen Mi Zhang Yazhi cheng State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

2,6-bis(picrylamino)-3,5-dinitropyridine(PYX)has excellent thermostability,which makes its thermal decomposition mechanism receive much *** this paper,the mechanism of PYX thermal decomposition was investigated thoroughly by the ReaxFF-lg force field combined with DFT-B3LYP(6-311++G)*** detailed decomposition mechanism,small-molecule product evolution,and cluster evolution of PYX were mainly *** the initial stage of decomposition,the intramolecular hydrogen transfer reaction and the formation of dimerized clusters are earlier than the denitration *** the progress of the reaction,one side of the bitter amino group is removed from the pyridine ring,and then the pyridine ring is *** final products produced in the thermal decomposition process are CO_(2),H_(2)O,N_(2),and H_(2).Among them,H_(2)O has the earliest generation time,and the reaction rate constant(k_(3))is the *** clusters are formed during the decomposition of PYX,and the formation,aggregation,and decomposition of these clusters are strongly affected by *** low temperatures(2500 K-2750 K),many clusters are *** high temperatures(2750 K-3250 K),the clusters aggregate to form larger *** 3500 K,the large clusters decompose and become *** the late stage of the reaction,H and N in the clusters escaped almost entirely,but more O was trapped in the clusters,which affected the auto-oxidation process of ***'s initial decomposition activation energy(E_(a))was calculated to be 126.58 kJ/*** work contributes to a theoretical understanding of PYX's entire thermal decomposition process.

关键词： PYX Thermal decomposition ReaxFF-lg MD simulations Excellent thermostable explosives

Initial precursor reaction mechanism of CVD-HfC coating based on density functional theory

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Chinese Journal of Aeronautics 2024年第7期37卷 511-521页

作者： Yunzhou LIN Yulei ZHANG Yanqin fu Jian ZHANG jing’an KONG Ruicong chen State Key Laboratory of Solidification Processing Carbon/Carbon Composites Research CenterNorthwestern Polytechnical UniversityXi’an 710072China Henan Key Laboratory of High Performance Carbon Fiber Reinforced Composites Carbon Matrix Composites Research InstituteHenan Academy of SciencesZhengzhou 450046China

Recently,the preparation of ultra-high temperature HfC ceramic coating has gained significant attention,particularly through the application of the HfCl_(4)-CH_(4)-H_(2)-Ar system via Chemical Vapor Deposition(CVD),which has been found widely applied to C/C ***,an analysis of the reactions that occur in the initial stage of the CVD-HfC coating process is presented using Density functional Theory(DFT)and Transition State Theory(TST)at the B3LYP/Lanl2DZ *** results reveal that HfCl4 can only cleave to produce hypochlorite,which will further react with methyl to synthesize intermediates to form *** to the analysis of the energy barrier and reaction constant,HfCl preferentially reacts with methyl groups to form complex adsorptive intermediates at 1573 *** a C—Hf bond production energy of 212.8 kcal/mol(1 kcal=4.18 kJ),the reaction rate constant of HfCl+CH is calculated to be 2.15×10^(-18) cm^(3)/s at 1573 ***,both the simulation and experimental results exhibit that the upward trend of reaction rate constants with temperature is also consistent with the deposition rate,indicating that the growth curve of the reaction rate constants tends to flatten *** proposed reaction model of the precursor’s decomposition and reconstruction during deposition process has significant implication for the process guidance.

关键词： Carbon composite HfC coating Chemical vapor deposition Density functional theory Precursor reaction mechanism

Low-temperature NH_(3) abatement via selective oxidation over a supported copper catalyst with high Cu^(+) abundance

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Journal of Environmental Sciences 2024年第9期143卷 12-22页

作者： Zhiming Yang Lin Peng Leneng Yang Mingli fu Daiqi Ye Peirong chen Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control National Engineering Laboratory for VOCs Pollution Control Technology and EquipmentSchool of Environment and EnergySouth China University of TechnologyGuangzhou 510006China Guangdong chengyi Environmental Technology Corp. Shaoguan 512158China

Selective catalytic NH_(3)-to-N_(2) oxidation(NH_(3)-SCO)is highly promising for abating NH_(3) emissions slipped from stationary flue gas after-treatment *** practical application,however,is limited by the non-availability of low-cost catalysts with high activity and N_(2) ***,using defect-rich nitrogen-doped carbon nanotubes(NCNT-AW)as the support,we developed a highly active and durable copper-based NH_(3)-SCO catalyst with a high abundance of cuprous(Cu^(+))*** obtained Cu/NCNT-AW catalyst demonstrated outstanding activity with a T_(50)(*** temperature to reach 50% NH_(3) conversion)of 174℃ in the NH_(3)-SCO reaction,which outperformed not only the Cu catalyst supported on N-free O-functionalized CNTs(OCNTs)or NCNT with less surface defects,but also those most active Cu catalysts in open *** kinetics measurements and temperature-programmed surface reactions using NH_(3)as a probe molecule revealed that the NH_(3)-SCO reaction on Cu/NCNT-AW follows an internal selective catalytic reaction(i-SCR)route involving nitric oxide(NO)as a key *** to mechanistic investigations by X-ray photoelectron spectroscopy,Raman spectroscopy,and X-ray absorption spectroscopy,the superior NH_(3)-SCO performance of Cu/NCNT-AW originated from a synergy of surface defects and ***,surface defects promoted the anchoring of Cu O nanoparticles on N-containing sites and,thereby,enabled efficient electron transfer from N to Cu O,increasing significantly the fraction of SCR-active Cu^(+)sites in the *** study puts forward a new idea for manipulating and utilizing the interplay of defects and N-dopants on carbon surfaces to fabricate Cu^(+)-rich Cu catalysts for efficient abatement of slip NH_(3)emissions via selective oxidation.

关键词： NH_(3)-SCO XANES Localized etching N-doping N_(2) selectivity i-SCR

Reactive Transport Process of Earthquake-induced Hydrochemical Changes in Guanding Thermal Spring,Western Sichuan,China

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Acta Geologica Sinica(English Edition) 2024年第1期98卷 241-249页

作者： NA jin JIANG Xue SHI Zheming chen Yanmei Hubei Key Laboratory of Petroleum Geochemistry and Environment(Yangtze University) Wuhan 430100China School of Environmental Studies China University of GeosciencesWuhan 430074China School of Water Resources and Environment China University of GeosciencesBeijing 100083China State Key Laboratory of Water Resource Protection and Utilization in Coal Mining Beijing 100000China

Earthquake-related hydrochemical changes in thermal springs have been widely observed;however,quantitative modeling of the reactive transport process is *** the present study,we apply reactive transport simulation to capture the hydrochemical responses in a thermal spring following the Wenchuan Ms 8.0 and Lushan Ms 7.0 *** first constrain deep reservoir geothermal fluid compositions and temperature by multicomponent geothermometry,and then a reactive geochemical transport model is constructed to reproduce the hydrochemical evolution *** results show that the recharge from the shallow aquifer increases gradually until it reaches a peak because of the permeability enhancement caused by the Lushan earthquake,which may be the mechanism to explain the earthquake-related hydrochemical *** contrast to the postseismic effect of the Wenchuan earthquake,the chemical evolution can be considered as hydrochemical anomalies related to the Lushan *** study proves that the efficient simulation of reactive transport processes is useful for investigating earthquake-related signals in hydrochemical time series.

关键词： earthquake hydrochemical changes reactive geochemical transport model Kangding area

Effects of Atmospheric Pressure on Developmental Characteristics and the Stability of Air Entraining Agent for Concrete

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Journal of Wuhan University of Technology(Materials Science) 2024年第4期39卷 979-989页

作者：李立辉牛开民 TIAN Bo chen Xin fu Ziqian ZHU Xuwei School of Civil Engineering Chongqing Jiaotong UniversityChongqing 400074China Transportation Science and Engineering Harbin Institute of TechnologyHarbin 150090China Research Institute of Highway Ministry of TransportBeijing 100088China

In order to ascertain the effects of atmospheric pressure on developmental characteristics and the stability of AEA(air-entraining agent)solution bubbles,AEA solution experiments and AEA solution bubble experiments were,respectively,conducted in Peking(50 m,101.2 kPa)and Lhasa(3,650 m,63.1 kPa).Surface tensions and inflection-point concentrations were tested based on AEA solutions,whilst developmental characteristics,thicknesses and elastic coefficients of liquid films were tested based on air bubbles of AEA *** study involved three types of AEAs,which were TM-O,226A,and *** experimental results show that initial sizes of TM-O,226A,and 226S are,respectively,increased by 43.5%,17.5%,and 3.8%.With the decrease of ambient pressure,the drainage rate and the drainage index of AEA solution bubbles *** experiments show that the liquid film thicknesses of all tested AEA solution bubbles are in micron *** the atmospheric pressure decreases from 101.2 to 63.1 kPa,the liquid film thicknesses of three types of AEA solutions decrease in various degrees;and film elasticities at critical thicknesses *** film of 226S solution bubbles is the most stable,presenting as a minimum thickness *** should be noted that elastic coefficient of liquid film only represents the level at critical thickness,thus it can not be applied as the only evaluating indicator of bubble *** a type of AEA,factors affecting the stability of its bubbles under low atmospheric pressure include initial bubbles size,liquid film thickness,liquid film elasticity,ambient temperature,etc.

关键词： air-entraining agent surface tension bubble size liquid film thickness liquid film elasticity atmospheric pressure

Towards Sustainable Grinding of Difficult-to-Cut Alloys-A Holistic Review and Trends

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 1-28页

作者： Ning Qian Jiajia chen Aqib Mashood Khan Biao Zhao Yurong chen Wenfeng Ding Yucan fu Jiuhua Xu Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China College of Mechanical and Electronic Engineering Nanjing Forestry UniversityNanjing 210037China JITRI Institute of Precision Manufacturing Nanjing 211805China

Grinding,a critical precision machining process for difficult-to-cut alloys,has undergone continual technological advancements to improve machining ***,the sustainability of this process is gaining heightened attention due to significant challenges associated with the substantial specific grinding energy and the extensive heat generated when working with difficult-to-cut alloys,renowned for their exceptional physical and mechanical *** response to these challenges,the widespread application of massive coolant in manufacturing industries to dissipate grinding heat has led to complex post-cleaning and disposal ***,in turn,has resulted in issues such as large energy consumption,a considerable carbon footprint,and concerns related to worker health and safety,which have become the main factors that restrict the development of grinding *** paper provides a holistic review of sustainability in grinding difficult-to-cut alloys,encompassing current trends and future *** examination extends to developing grinding technologies explicitly tailored for these alloys,comprehensively evaluating their sustainability ***,the exploration delves into innovative sustainable technologies,such as heat pipe/oscillating heat pipe grinding wheels,minimum quantity lubrication,cryogenic cooling,and *** groundbreaking technologies aim to reduce dependence on hazardous coolants,minimizing energy and resource consumption and carbon emissions associated with coolant-related or subsequent disposal *** essence of these technologies lies in their potential to revolutionize traditional grinding practices,presenting environmentally friendly ***,future development trends and research directions are put forward to pursue the current limitation of sustainable grinding for difficult-to-cut *** paper can guide future research and development efforts toward more environmentally friendly

关键词： Grinding Sustainability Cooling Energy consumption Carbon footprint Difficult-to-cut alloys

Quantitative prediction model for the depth limit of oil accumulation in the deep carbonate rocks:A case study of Lower Ordovician in Tazhong area of Tarim Basin

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Petroleum Science 2024年第1期21卷 115-124页

作者： Wen-Yang Wang Xiong-Qi Pang Ya-Ping Wang Zhang-Xin chen fu-Jie Jiang Ying chen State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing100029China State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum(Beijing)Beijing102249China College of Geosciences China University of Petroleum(Beijing)Beijing102249China Research Institute of Exploration and Development PetroChina Southwest Oil&Gas Field CompanyChengdu610041SichuanChina Chemical and Petroleum Engineering Schulich School of EngineeringUniversity of CalgaryCalgaryT2N 1N4Canada

With continuous hydrocarbon exploration extending to deeper basins,the deepest industrial oil accumulation was discovered below 8,200 m,revealing a new exploration ***,the extent to which oil exploration can be extended,and the prediction of the depth limit of oil accumulation(DLOA),are issues that have attracted significant attention in petroleum *** it is difficult to characterize the evolution of the physical properties of the marine carbonate reservoir with burial depth,and the deepest drilling still cannot reach the ***,the DLOA cannot be predicted by directly establishing the relationship between the ratio of drilling to the dry layer and the *** this study,by establishing the relationships between the porosity and the depth and dry layer ratio of the carbonate reservoir,the relationships between the depth and dry layer ratio were obtained *** depth corresponding to a dry layer ratio of 100%is the *** on this,a quantitative prediction model for the DLOA was finally *** results indicate that the porosity of the carbonate reservoir,Lower Ordovician in Tazhong area of Tarim Basin,tends to decrease with burial depth,and manifests as an overall low porosity reservoir in deep *** critical porosity of the DLOA was 1.8%,which is the critical geological condition corresponding to a 100%dry layer ratio encountered in the *** depth of the DLOA was 9,000 *** study provides a new method for DLOA prediction that is beneficial for a deeper understanding of oil accumulation,and is of great importance for scientific guidance on deep oil drilling.

关键词： Deep layer Tarim Basin Hydrocarbon accumulation Depth limit of oil accumulation Prediction model