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Microcosmic mechanism and correction of moisture effect on furfural diffusion and equilibrium in oil‐paper insulation

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High Voltage 2023年第4期8卷 772-780页

作者： dawei Feng Ge Chen Yuandi Lin Ruijin Liao Dayong Yuan State Key Lab of Reliability and Intelligence of Electrical Equipment School of Electrical EngineeringHebei University of TechnologyTianjinChina The MOE Key Laboratory of Special Machine and High Voltage Apparatus School of Electrical EngineeringShenyang University of TechnologyShenyangChina State Grid Jiangsu Electric Power Company Research Institute NanjingChina State Key Laboratory of Power Transmission Equipment&System Security and New Technology School of Electrical EngineeringChongqing UniversityChongqingChina TBEA Shenyang Transformer Group Co. LtdShenyangChina

Furfural content in oil is considered as an effective parameter to evaluate the ageing state of oil-immersed *** previous thermal ageing experiments at 130℃,we found that moisture increment in oil-paper system makes more furfural distribute in ***,the microcosmic mechanism of moisture effect on furfural diffusion from paper to oil is still unknown,and the furfural equilibrium law at transformers'typical operating temperatures is also unclear,resulting in the unreliability of the existed furfural evaluation *** elucidate the above problems,molecular dynamics simulation and furfural equilibrium experiments at 60℃ were carried out at different moisture *** results show that high moisture content makes part of furfural diffuse from paper to oil *** moisture content increases from 1% to 2%,mass fraction of furfural in oil may increase from 32.98% to 49.83%,leading to furfural content in oil increases from 0.76 mg/L to 1.06 mg/L when the degree of polymerisation of insulation paper is about 524,which increased by 39.5%.The increase in moisture content makes cellulose form hydrogen bonds with H_(2)O preferentially,decreasing the hydrogen bonds interaction between cellulose and ***,partial furfural falls off cellulose and diffuses into oil,leading to an increase in furfural content in *** eliminate the moisture interference,a corrected furfural assessment model based on the moisture equilibrium curve has been constructed,which can accurately evaluate the ageing state of insulation paper regardless of the moisture influence.

关键词： equilibrium insulation diffusion

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Finite-time synchronization of uncertain fractional-order multi-weighted complex networks with external disturbances via adaptive quantized control

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Chinese Physics B 2022年第10期31卷 341-351页

作者： Hongwei Zhang Ran Cheng dawei Ding School of Electronics and Information Engineering Anhui UniversityHefei 230601China

The finite-time synchronization of fractional-order multi-weighted complex networks(FMCNs)with uncertain parameters and external disturbances is ***,based on fractional calculus characteristics and Lyapunov stability theory,quantized controllers are designed to guarantee that FMCNs can achieve synchronization in a limited time with and without coupling delay,***,appropriate parameter update laws are obtained to identify the uncertain parameters in ***,numerical simulation examples are given to validate the correctness of the theoretical results.

关键词： fractional-order complex networks uncertain parameter finite-time synchronization quantized control

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Influences of characteristic parameters on starting-up process of an arcjet thruster

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Chinese Journal of Aeronautics 2020年第12期33卷 3011-3017页

作者： Yan SHEN Yinggang TONG Fuzhi WEI Zhaopu YAO dawei HU School of Aerospace and Astronautics Sun Yet-sen UniversityGuangzhou 510006China Lab of Space Propulsion Technology Beijing Institute of Control EngineeringBeijing 100094China

Arcjet thruster has been a widely used electrical propulsion technology on GEO satellites since *** its long history of technical development and commercial application,lifetime verification of an arcjet thruster is always one of the most important and expensive *** that the main life limitation of an arcjet thruster is electrode ablation and a significant share of the total ablation happens in its starting-up process,the starting-up process is studied with arc voltage *** interpretation of arc voltage signals,the transfer process of the arc root on the anode surface is identified,and?T(the duration of the arc root transfer process)is suggested to be a characteristic parameter for fast evaluation of lifetime assessment and design optimization for an arcjet *** this criterion,the influences of typical parameters on the starting-up process are established through comparison with a benchmark *** to experimental results,an increase of the gas flow will obviously reduce?T,while a smaller swirl aperture and a longer throat channel do not have a remarkable correlation with?***,with a sample of a smaller throat diameter to increase the flow velocity,a reduction of?T is ***,the modifications also affect the stability of arcjet thruster operation,which is also discussed.

关键词： Arc root Arcjet Electric propulsion Electrode ablation Starting-up process

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On the Two Successive Supercold Waves Straddling the End of 2020 and the Beginning of 2021

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Advances in Atmospheric Sciences 2022年第4期39卷 591-608页

作者： Cholaw BUEH Jingbei PENG dawei LIN Bomin CHEN International Center for Climate and Environment Sciences Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China State Key Laboratory of Severe Weather(LASW)&Key Laboratory for Cloud Physics of China Meteorological Administration Chinese Academy of Meteorological SciencesBeijing 100081China Shanghai Climate Center Shanghai 200030China

Two supercold waves straddling 2020 and 2021 successively hit China and caused record-breaking extremely low *** this study,the distinct features of these two supercold waves are analyzed on the medium-range time *** blocking pattern from the Kara Sea to Lake Baikal characterized the first cold wave,while the large-scale tilted ridge and trough over the Asian continent featured the second cold *** to the cold waves,both the northwest and hyperpolar paths of cold air contributed to a zonally extensive cold air accumulation in the key region of *** might be the primary reason why strong and extensive supercold waves occur even under the Arctic amplification *** two cold waves straddling 2020 and 2021 exhibited distinct features:(1)the blocking circulation occurred to the north or the east of the Ural Mountains and was not confined only to the Ural Mountains as it was for the earlier cold waves;(2)the collocation of the Asian blocking pattern and the polar vortex deflection towards East Asia preferred the hyperpolar path of cold air accumulation and the subsequent southward outburst;and(3)both high-and low-frequency processes worked in concert,leading to the very intense cold *** cold air advance along the northwest path,which coincides with the southeastward intrusion of the Siberian High(SH)front edge,is associated with the high-frequency process,while the cold air movement along the hyperpolar path,which is close to the eastern edge of the SH,is controlled by the low-frequency process.

关键词： cold wave Siberian high hyperpolar path blocking large-scale tilted ridge and trough

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Dual-quaternion-based satellite pose estimation and control with event-triggered data transmission

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Science China(Technological Sciences) 2023年第5期66卷 1214-1224页

作者： LI ChunHui ZOU HengGuang SHI dawei SONG JiLiang WANG JunZheng School of Automation Beijing Institute of TechnologyBeijing 100081China China Academy of Space Technology Beijing 100086China

This paper proposes an event-triggered active disturbance rejection control framework to achieve the simultaneous position and attitude control of a satellite in proximity ***,to facilitate the satellite motion description,we derive the relative kinematics and dynamics in terms of dual quaternions with the considerations of internal uncertainties and external ***,two kinds of event-triggered mechanisms in the sensor/observer and controller/actuator channels are proposed to reduce the utilization of onboard communication resources and to improve control performance,*** observation error and tracking error of both the attitude and orbit systems are theoretically proven to be asymptotically ***,the simulation results show that the proposed method can achieve simultaneous position and attitude tracking between target and chaser satellites with satisfactory control performance and reduced communication rates.

关键词： active disturbance rejection control framework event-triggered mechanisms estimate and control position and attitude satellite in proximity operations dual quaternions

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Effect of molybdenum content on the microstructure and corrosion behavior of FeCoCrNiMox high-entropy alloys

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Journal of Materials Science & Technology 2020年第11期42卷 64-73页

作者： Chunduo Dai Tianliang Zhao Cuiwei Du Zhiyong Liu dawei Zhang Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China Key Laboratory for Corrosion and Protection of The Ministry of Education(MOE) Beijing 100083China Beijing Advanced Innovation Center for Materials Genome Engineering University of Science and Technology BeijingBeijing 100083China Materials Genome Institute of Shanghai University Shanghai 200444China

The effect of Mo content on the microstructure revolution and corrosion behavior of cast FeCoCrNiMox high-entropy alloys in chloride environments were *** indicate that FeCoCrNi and FeCoCrNiMo0.1 alloys are in single FCC solid *** precipitates form in FeCoCrNiMo0.3 and increase in FeCoCrNiMo0.6 *** occurs on FeCoCrNi and FeCoCrNiMo0.1 alloys while FeCoCrNiMo0.3 and FeCoCrNiMo0.6 alloys suffer from preferential localized corrosion at the regions depleted in Cr and *** higher Cr2O3/Cr(OH)3 ratio and the incorporation of Mo oxides make the passive film more protective and the corrosion resistance of the FeCoCrNiMo0.1 alloy is thus *** correlation between microstructure and corrosion behavior and the corresponding corrosion mechanism were clarified.

关键词： High-entropy alloys Corrosion behavior Precipitate

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Dissolution of TiO_(2) and TiN inclusions in CaO–SiO_(2)–B_(2)O_(3)-based fluorine-free mold flux

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International Journal of Minerals,Metallurgy and Materials 2023年第9期30卷 1740-1747页

作者： dawei Cai Li Zhang Wanlin Wang Lei Zhang Il Sohn School of Metallurgy and Environment Central South UniversityChangsha 410083China National Center for International Research of Clean Metallurgy Central South UniversityChangsha 410083China Materials Science and Engineering Department Yonsei UniversitySeoul 120-749Rep.of Korea

Mold flux serves the crucial metallurgical function of absorbing inclusions, directly impacting the smoothness of the casting process as well as the cast slab quality. In this study, the dissolution behavior and mechanism of Ti O_(2)and Ti N inclusions in molten Ca O–Si O_(2)–B_(2)O_(3)-based fluorine-free mold flux were explored by in situ single hot thermocouple technology combined with X-ray photoelectron *** results showed that Ti O_(2) inclusions are effectively dissolved by the molten slag within 76 s, during which the original octahedral [Ti O_(6)]^(8-)structures are destroyed and convert to the networker tetrahedral [Ti O_(4)]^(4-)structures. However, the dissolution rate is much lower for Ti N inclusions than for Ti O_(2)inclusions. This can be attributed to the fact that the Ti N particles need to be oxidized and then dissolved in the molten slag to form tetrahedral [Ti O4]4-and octahedral [Ti O_(6)]^(8-)structures during the Ti N inclusion dissolution process, which is accompanied by the generation of a large amount of N_(2)gas. Moreover, Ca Ti O_(3)crystals tend to nucleate and grow on bubble surfaces with sufficient octahedral [Ti O_(6)]^(8-)structures and Ca^(2+)ions, eventually resulting in the molten slag being in a solid–liquid mixed state.

关键词： TiO_(2)inclusion TiN inclusion mold flux fluorine-free continuous casting

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Distribution characteristics and controlling factors of typical heavy metals in Huanghe River estuary,China

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Journal of Oceanology and Limnology 2023年第1期41卷 150-165页

作者： Yuxi LU dawei PAN Tingting YANG Chenchen WANG Institute of Oceanology Chinese Academy of SciencesQingdao 266071China CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation Shandong Key Laboratory of Coastal Environmental ProcessesResearch Center for Coastal Environment Engineering Technology of Shandong ProvinceYantai Institute of Coastal Zone ResearchChinese Academy of SciencesYantai 264003China University of Chinese Academy of Sciences Beijing 100049China College of Chemistry and Chemical Engineering Yantai UniversityYantai 264005China

The geochemical characteristics and potential controlling factors of colloidal Zn,Cd,and Pb in Huanghe(Yellow)River estuary(HRE),China were *** three metals were highly variable over a range of spatiotemporal scales,comprehensively forced by various physical and biological *** dissolved Zn,Cd,and Pb varied from 200.1 to 321.7,2.6 to 4.1,and 0.5 to 1.0 nmol/L,*** one near-estuarine station of Zn had contamination factor values>1,which indicate the lower contaminant *** dissolved species of Zn,Cd and Pb were fractionated,namely<1 kDa,1-3 kDa,3-10 kDa,10-100 kDa,and 100 kDa-0.45μ***<1 kDa truly dissolved phase was the main fraction of the three dissolved metals(50%-62%),while the 100-kDa-0.45-μm high molecular weight colloidal fraction was dominant in their respective colloidal *** input and sediment acted as important sources of strong ligands and natural colloids for the HRE water system.<3-kDa Zn and Pb were susceptible to the dissolved oxygen,the behaviors of colloidal Zn and 3-10-kDa Pb were related to dissolved organic carbon(DOC).However,no significant correlation between each dissolved fraction of Cd and salinity,pH,temperature,colloidal organic carbon,and DOC was found in this ***,these findings,completed by the evaluation of the dissolved species of Zn,Cd,and Pb at 10 sites over the river-sea mixing zone,provided new insights into the colloidal heterogeneity that affect metals geochemical features,migration and fate in estuaries.

关键词： colloidal heavy metal size fraction Huanghe(Yellow)River estuary geochemical feature

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Variation of the friction conditions in cold ring compression tests of medium carbon steel

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Friction 2020年第2期8卷 311-322页

作者： dawei ZHANG Bingkun LIU Jingxiang LI Minchao CUI Shengdun ZHAO School of Mechanical Engineering Xi'an Jiaotong UniversityXi'an 710049China Key Laboratory of High Performance Complex Manufacturing Central South UniversityChangsha 410083China

Lubrication and friction conditions vary with deformation during metal forming *** macro-variations can be observed when a threshold of deformation is *** study shows that during the cold compression processing of#45(AISI 1045)steel rings,the magnitude of friction and surface roughness(Ra)changes significantly upon reaching a 45%reduction in ring *** example,the Ra of compressed ring specimens increased by approximately 55%immediately before and after reaching this threshold,compared to an 18% or 25%variation over a 35%-45%or a 45%-55%reduction in height,*** ring compression test conducted by this study indicates that the Coulomb friction coefficient and Tresca friction factor mare 0.105 and 0.22,respectively,when the reduction in height is less than 45%;and 0.11 and 0.24,respectively,when the reduction in height is greater than 45%.

关键词： friction condition ring compression test friction calibration curve surface topography

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Optimal Intelligence Planning of Wind Power Plants and Power System Storage Devices in Power Station Unit Commitment Based

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Energy Engineering 2022年第5期119卷 2081-2104页

作者： Yuchen Hao dawei Su Zhen Lei Control Center of State Grid of Jiangsu Electric Power Co. Ltd.Nanjing210000China

Renewable energy sources(RES)such as wind turbines(WT)and solar cells have attracted the attention of power system operators and users alike,thanks to their lack of environmental pollution,independence of fossil fuels,and meager marginal *** the introduction of RES,challenges have faced the unit commitment(UC)problem as a traditional power system optimization problem aiming to minimize total costs by optimally determining units’inputs and outputs,and specifying the optimal generation of each *** output power of RES such as WT and solar cells depends on natural factors such as wind speed and solar irradiation that are riddled with *** a result,the UC problem in the presence of RES faces *** grid consumed load is not always equal to and is randomly different from the predicted values,which also contributes to uncertainty in solving the aforementioned *** current study proposes a novel two-stage optimization model with load and wind farm power generation uncertainties for the security-constrained UC to overcome this *** new model is adopted to solve the wind-generated power uncertainty,and energy storage systems(ESSs)are included in the problem for further *** problem is written as an uncertain optimization model which are the stochastic nature with security-constrains which included undispatchable power resources and storage *** solve the UC programming model,a hybrid honey bee mating and bacterial foraging algorithm is employed to reduce problem complexity and achieve optimal results.

关键词： Unit commitment security-constrained programming wind farms uncertainty honey bee mating algorithm bacterial foraging algorithm

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