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Dynamic thermal rating assessment of oil-immersed power transformers for multiple operating conditions

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High Voltage 2024年第1期9卷 195-205页

作者： Chen Zhang Xuzhu dong Jiangjun ruan Yongqing Deng School of Electrical Engineering and Automation Wuhan UniversityWuhanHubeiChina

In this article,the dynamic thermal rating assessment method of oil-immersed power transformer with multiple operating conditions is proposed,considering the constraints of hot spot temperature(HST),top oil temperature,losses of life and the maximum allowable current of on-load tap changer(OLTC)or bushing,which can determine the dynamic load curves under different operating conditions and give the most sensitive constraints to limit the dynamic load *** improve the accuracy of HST estimation,the temperature estimation model is also improved and the thermal parameters are optimised using the HST measured by optical ***,several application examples are studied for transformers in different *** results show that the normal cyclic dynamic transformer rating(DTR)is mainly limited by the losses of life when the ambient temperature is high,and the average load factor can be increased to 0.82 with a maximum load capacity of *** main limiting factor of short-term DTR is the OLTC or bushing current constraint,and the average load factor can be increased to *** maximum load capacity of the transformer under both operating conditions is 23%and 50%higher than its rated load capacity,indicating that the transformer still has a large load potential available.

关键词： load thermal power

Finite Difference-Peridynamic Differential Operator for Solving Transient Heat Conduction Problems

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Computer Modeling in Engineering & Sciences 2024年第9期140卷 2707-2728页

作者： Chunlei ruan Cengceng dong Zeyue Zhang Boyu Chen Zhijun Liu School of Mathematics&Statistics Henan University of Science&TechnologyLuoyang471023China Longmen Laboratory Luoyang471023China

Transient heat conduction problems widely exist in *** previous work on the peridynamic differential operator(PDDO)method for solving such problems,both time and spatial derivatives were discretized using the PDDO method,resulting in increased complexity and programming *** this work,the forward difference formula,the backward difference formula,and the centered difference formula are used to discretize the time derivative,while the PDDO method is used to discretize the spatial *** new schemes for solving transient heat conduction equations have been developed,namely,the forward-in-time and PDDO in space(FT-PDDO)scheme,the backward-in-time and PDDO in space(BT-PDDO)scheme,and the central-in-time and PDDO in space(CT-PDDO)*** stability and convergence of these schemes are analyzed using the Fourier method and Taylor’s *** show that the FT-PDDO scheme is conditionally stable,whereas the BT-PDDO and CT-PDDO schemes are unconditionally *** stability conditions for the FT-PDDO scheme are less stringent than those of the explicit finite element method and explicit finite difference *** convergence rate in space for these three methods is *** constructed schemes are applied to solve one-dimensional and two-dimensional transient heat conduction *** accuracy and validity of the schemes are verified by comparison with analytical solutions.

关键词： Peridynamic differential operator finite difference method stability transient heat conduction problem

A 10-yr Rainfall and Cloud-to-Ground Lightning Climatology over Coastal and Inland Regions of Guangdong,China during the Pre-Summer Rainy Season

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Journal of Meteorological Research 2024年第3期38卷 469-488页

作者： Yuqing ruan Rudi XIA Xinghua BAO dong ZHENG Yan SHEN Jinfang YIN State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing100081China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science&TechnologyNanjing210044China National Meteorological Information Centre China Meteorological AdministrationBeijing100081China

A comparative analysis of the spatiotemporal distribution characteristics of rainfall and lightning in coastal and inland areas of Guangdong Province of China during the pre-summer rainy season(PSRS)from 2008 to 2017 reveals distinct *** the inland target region(ITR),rainfall is concentrated in the central and eastern mountainous *** exhibits a bimodal diurnal variation,with peaks in the afternoon and *** afternoon peak becomes more pronounced during the post-monsoon-onset period because of the increased rainfall ***,in the coastal target region(CTR),rainfall concentrates around mountainous ***,CTR’s rainfall is weaker than ITR’s during the pre-monsoon-onset period,primarily associated with the lower-level moisture outflow in CTR,but it strengthens significantly during the post-monsoon-onset period owing to enhanced moisture ***’s diurnal rainfall variation transitions from bimodal to a single broad peak during the post-monsoon-onset period,influenced by changes in both rainfall frequency and *** contrast to rainfall,the spatiotemporal distribution of lightning centers remains relatively stable during the *** strongest center is located over ITR’s plains west of the rainfall center,with a secondary center in the western plains of *** activity significantly increases during the post-monsoon-onset period,particularly in ITR,primarily because of the increased lightning *** diurnal lightning flash density and lightning hours show a single afternoon peak in the two target regions,and the timing of the peak in ITR is approximately two hours later than in *** circulation analysis indicates that during early morning,the lower atmosphere is nearly neutral in *** advected warm,moist,unstable airflow,combined with topography,favors convection *** the afternoon,solar radiation increases thermal instability,further enhancing the convection frequency and in

关键词： rainfall lightning spatiotemporal distribution diurnal variation pre-summer rainy season

Burst-mode pulse generation in passively mode-locked all-fiber green/orange lasers at 543 nm and 602 nm

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Photonics Research 2024年第6期12卷 1231-1238页

作者： QIUJUN ruan JINHai ZOU CHUNNA FENG TINGTING CHEN HANG WANG ZHIPENG dong ZHENGQIAN LUO Fujian Key Laboratory of Ultrafast Laser Technology and Applications School of Electronic Science and EngineeringXiamen UniversityXiamen 361005China Shenzhen Research Institution of Xiamen University Shenzhen 518000China

We report on the experimental realization of,to the best of our knowledge,the first green and orange passively mode-locked all-fiber *** mode-locking in the burst-pulse status is achieved at the wavelengths of 543.3 nm and 602.5 *** figure-9 cavity comprises the fiber end-facet mirror,gain fiber(Ho^(3+):ZBLAN fiber or Pr^(3+)/Yb^(3+):ZBLAN fiber),and fiber loop mirror(FLM).The FLM with long 460 HP fiber is not only used as an output mirror,but also acts as a nonlinear optical loop mirror for initiating visible-wavelength *** green/orange mode-locked fiber lasers with the fundamental repetition rates of 3.779/5.662 MHz produce long bursts containing ultrashort pulses with the 0.85/0.76 GHz intra-burst repetition rates,*** ultrashort intra-burst pulses stem from the dissipative four-wave-mixing effect in the highly nonlinear FLM as well as the intracavity Fabry–Perot *** bursts of 22.2/11.6 ns with ultrashort pulses of 87/62 ps are obtained in our *** visible-wavelength passively mode-locked lasers in an all-fiber configuration and burst-mode would represent an important step towards miniaturized ultrafast fiber lasers and may contribute to the applications in ablation-cooling micromachining,biomedicine imaging,and scientific research.

关键词： fiber passive pulse

Molecule aging induced by electron attacking

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Journal of Energy Chemistry 2024年第6期93卷 519-525,I0013页

作者： Ping Song Yining dong Xue Gong Mingbo ruan Baoxin Ni Xuanhao Mei Kun Jiang Weilin Xu State Key Laboratory of Electroanalytical Chemistry and Jilin Province Key Laboratory of Low Carbon Chemical Power Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022JilinChina School of Applied Chemistry and Engineering University of Science and Technology of Chin1Hefei 230026AnhuiChina Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Collaborative Innovation Center of Chemistry for Energy MaterialsDepartment of ChemistryFudan UniversityShanghai 200438China

Here we propose a new concept of"molecule aging":with some special treatment,a molecule could be"aged"by losing some unknown tiny particles or pieces from atoms in the molecule,Such"aging"or loss of unknown tiny particles does not change apparently its molecular structure or chemical composition,but some physicochemical properties could be changed *** further confirm such"molecule aging"via a long-term electron attacking to age water(H_(2)O)*** IR spectra show no structural difference between the fresh water and the aged one,while the NMR spectra show that the electron attacking can decrease the size of water *** facts indicate that the electron attacking indeed can"affect"the structure of water molecule slightly but without damaging to its basic molecule *** exploration reveals that the hydrogen evolution reaction(HER)activity of the aged water molecule is lower than the fresh water on the same Pt/C *** density functional theory calculations indicate that the shortened O-H bond in H_(2)O indeed can present lower HER activity,so the observed size decrease of water clusters from NMR probably could be attributed to the shortening of O-H bond in water *** results indicate significantly that the molecule aging can produce materials with new functions for new possible applications.

关键词： Aging of molecules Electron attacking Full width at half maxima Hydrogen evolution reaction

Euler’s First-Order Explicit Method–Peridynamic Differential Operator for Solving Population Balance Equations of the Crystallization Process

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Computer Modeling in Engineering & Sciences 2024年第3期138卷 3033-3049页

作者： Chunlei ruan Cengceng dong Kunfeng Liang Zhijun Liu Xinru Bao Mathematics&Statistics School Henan University of Science&TechnologyLuoyang471023China Longmen Laboratory Luoyang471023China College of Vehicle and Traffic Engineering Henan University of Science&TechnologyLuoyang471023China

Using Euler’s first-order explicit(EE)method and the peridynamic differential operator(PDDO)to discretize the time and internal crystal-size derivatives,respectively,the Euler’s first-order explicit method–peridynamic differential operator(EE–PDDO)was obtained for solving the one-dimensional population balance equation in *** different conditions during crystallization were studied:size-independent growth,sizedependent growth in a batch process,nucleation and size-independent growth,and nucleation and size-dependent growth in a continuous *** high accuracy of the EE–PDDO method was confirmed by comparing it with the numerical results obtained using the second-order upwind and HR-van *** method is characterized by non-oscillation and high accuracy,especially in the discontinuous and sharp crystal size *** stability of the EE–PDDO method,choice of weight function in the PDDO method,and optimal time step are also discussed.

关键词： Population balance equation crystallization peridynamic differential operator Euler’s first-order explicit method

Aza-BODIPY dye with unexpected bromination and high singlet oxygen quantum yield for photoacoustic imaging-guided synergetic photodynamic/photothermal therapy

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Chinese Chemical Letters 2024年第6期35卷 445-450页

作者： Leichen Wang Anqing Mei Na Li Xiaohong ruan Xu Sun Yu Cai Jinjun Shao Xiaochen dong Key Laboratory of Flexible Electronics(KLOFE)&Institute of Advanced Materials(IAM) Nanjing Tech University(NanjingTech)Nanjing 211800China School of Chemistry&Materials Science Jiangsu Normal UniversityXuzhou 221116China Center for Rehabilitation Medicine Rehabilitation&Sports Medicine Research Institute of Zhejiang ProvinceDepartment of Rehabilitation MedicineZhejiang Provincial People’s Hospital(Affiliated People’s HospitalHangzhou Medical College)Hangzhou 310014China

Introducing heavy halogen atoms into organic small molecules is a practical strategy for efficient singlet oxygen(^(1)O_(2))***,bromine or iodine atoms are introduced on the aza-borondipyrromethene(aza-BODIPY)core,rather than on the periphery aryl rings for efficient~1O_(2) ***,an aza-BODIPY dye NBDPBr with unexpected bromination on the periphery aryl rings was synthesized for photoacoustic(PA)imaging-guided synergistic photothermal therapy(PTT)and photodynamic therapy(PDT)in tumor *** to unexcepted bromination at the periphery aryl rings,NBDPBr demonstrated an outstanding singlet oxygen quantum yield(Φ_(Δ))of 66% which was superior to similar brominated photosensitizers previously *** encapsulation with amphiphilic polymer F-127,hydrophilic NBDPBr nanoparticles(NPs)were fabricated and exhibited an excellent photothermal conversion efficiency(η)of 43.0% under 660 nm *** vivo PA imaging results demonstrated that NBDPBr NPs could specifically accumulate at tumor sites and realized the maximum tumor retention at 7 h *** the in vitro and in vivo results indicated the significant potence of NBDPBr with unexpected bis-bromination for PA imaging-guided synergetic PDT/PTT.

关键词： Unexpected bromination Aza-BODIPY Photodynamic therapy Photothermal therapy Synergetic therapy

Magnetic Bistability in the Crystaline Fullerene Radical Salt

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Chinese Journal of Chemistry 2024年第17期42卷 2043-2048页

作者： Huapeng ruan Ke Li Quanchun Sun Min Liu Zhongtao Feng Xue dong Yue Zhao Xinping Wang State Key Laboratory of Coordination Chemistry School of Chemistry and Chemical EngineeringCollaborative Innovation Center of AdvancedMicrostructuresNanjing UniversityNanjingJiangsu210023China Department College of Materials and Chemical Engineering Pingxiang UniversityPingxiangJiangxi 337055China State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryChinese Academy of ScienceShanghai 200032China

Compounds with magnetic bistability is highly attractive for the construction of switches,thermal sensors,information-storage media and memory ***,we report a crystalline fullerene radical anion salt[Na(THF)_(5)]C_(60)(1),obtained by the reduction of C_(60) with Na in solution,which exhibits magnetic bistability accompanied with one magnetostructural transition,giving low temperature(LT),high temperature(HT)phases and a metastable phase.

关键词： Magnetic bistability Fullerene radical Structural transition Crystal structure Chain distortion Fullerene Magnetic materials π-πstacking

Dynamic Response of Foundations during Startup of High-Frequency Tunnel Equipment

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Computer Modeling in Engineering & Sciences 2024年第7期140卷 821-844页

作者： Dawei ruan Mingwei Hu College of Civil and Transportation Engineering Shenzhen UniversityShenzhen518060China State Key Laboratory of Intelligent Geotechnics and Tunnelling Shenzhen UniversityShenzhen518060China Key Laboratory of Coastal Urban Resilient Infrastructures of Ministry of Education Shenzhen UniversityShenzhen518060China Underground Polis Academy Shenzhen UniversityShenzhen518060China Shenzhen Key Laboratory of Green Efficient and Intelligent Construction of Underground Metro StationShenzhen UniversityShenzhen518060China

The specialized equipment utilized in long-line tunnel engineering is evolving towards large-scale,multifunctional,and complex *** vibration caused by the high-frequency units during regular operation is supported by the foundation of the units,and the magnitude of vibration and the operating frequency fluctuate in different engineering contexts,leading to variations in the dynamic response of the *** high-frequency units yield significantly diverse outcomes under different startup conditions and times,resulting in failure to meet operational requirements,influencing the normal function of the tunnel,and causing harm to the foundation structure,personnel,and property in severe *** article formulates a finite element numerical computation model for solid elements using three-dimensional elastic body theory and integrates field measurements to substantiate and ascertain the crucial parameter configurations of the finite element *** proposing a comprehensive startup timing function for high-frequency dynamic machines under different startup conditions,simulating the frequency andmagnitude variations during the startup process,and suggesting functions for changes in frequency and magnitude,a simulated startup schedule function for high-frequency machines is created through *** into account the selection of the transient dynamic analysis step length,the dynamic response results for the lower dynamic foundation during its fundamental frequency crossing process are *** validation checks if the structural magnitude surpasses the safety threshold during the critical phase of unit startup traversing the structural resonance *** design recommendations for high-frequency units’dynamic foundations are provided,taking into account the startup process of the machine and ensuring the safe operation of the tunnel.

关键词： Tunnel equipment high-frequency units startup conditions transient dynamics dynamic response foundation design