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Numerical simulation of transient characteristics in a bulb turbine during the load rejection process

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Journal of Hydrodynamics 2024年第1期36卷 170-183页

作者： Yue Lu Yu-quan Zhang Zhong-wei he Yuan Zheng College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing210098China College of Energy and Electrical Engineering Hohai UniversityNanjing210098China Huadong Engineering Corporation Ltd. Hangzhou311122China

To evaluate the safety of the bulb tubular turbine,the dynamic hydraulic characteristics of a hydropower station system during the load rejection process are studied through numerical simulations and a prototype *** the developed model,a dynamic grid technology(DGT)controls the closure of the guide vane and the blade,whilst the moment balance equation and the user-defined function(UDF)provide the runner’s rotation *** 3-D transient simulation method can well predict the rotation speed and mass flow curves in the state of load *** simulation outcomes of the system performance are basically consistent with the measurement data of the *** observed,the runner is subjected to the reversely increased torque and axial force,the system is in a braking phase,and the maximum speed peaks at 144.6%of the rated ***,the internal flow of the runner is greatly affected by the closure of the guide vane,and the draft tube forms an eccentric spiral vortex *** breaks downstream,aggravating the instability of the draft ***,the transient characteristics span for the first five seconds,demonstrating the importance of establishing an efficient governing *** obtained results are useful for designing the turbine’s flow channel with a double regulating function and comprehending the turbine’s transient characteristics.

关键词： Bulb tubular turbine load rejection numerical simulation dynamic grid prototype test

Photoinduced bismuth vanadate-catalyzed C(sp^(2))-H functionalization

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Chinese Chemical Letters 2024年第3期35卷 1-2页

作者： Rong-Nan Yi wei-Min he Key Laboratory of Food&Environment&Drug Monitoring and Testing of Universities in Hunan Province Hunan Police AcademyChangsha 410138China School of Chemistry and Chemical Engineering University of South ChinaHengyang 421001China

Visible light-induced organic reactions have gained much attention in recent years due to their mild conditions and high efficiency[1,2].In this context,many efficient photocatalysts including transition metal complex... 详细信息

关键词： bismuth catalyzed gained

Copper-mediated assembly of SO_(2)F group via radical fluorine-atom transfer strategy

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Chinese Chemical Letters 2024年第9期35卷 4-5页

作者： Yu-Yu Tan Lin-heng he wei-Min he School of Electrical Engineering University of South ChinaHengyang 421001China

Because of the unique reactivity of sulfonyl fluoride(SO_(2)F)group,such compound has found increasing applications in the areas of organic synthesis,new drug development,pesticide,material science and click chemistry,*** is of current interest to develop novel strategies and methods for the facile preparation of sulfonyl fluorides in a green and highly efficient manner[1,2].Although the traditional approach for the synthesis of sulfonyl fluorides relies on the nucleophilic substitution of fluoride atom with sulfonyl chlorides.

关键词： fluoride synthesis fluorine

Photocatalytic Minisci-type multicomponent reaction for the synthesis of 1-(halo)alkyl-3-heteroaryl bicyclo[1.1.1] pentanes

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Chinese Chemical Letters 2024年第10期35卷 6-8页

作者： Rong-Nan Yi wei-Min he Key Laboratory of Food&Environment&Drug Monitoring and Testing of Universities in Hunan Province Hunan Police Academy.Changsha 410138China School of Chemistry and Chemical Engineering University of South ChinaHengyang 421001China

Bioisosteres play an important role in pharmaceutical and agricultural compound design that has been developed to enhance the properties of *** a sp3-rich small ring cage hydrocarbons,bicyclo[1.1.1]pentanes(BCPs)were commonly considered as a bioisostere of the para-substituted arenes,internal alkynes,and tert-butyl groups,and its introduction can significantly improve pharmacokinetic properties,including passive permeability,aqueous solubility,metabolic stability[1].Over the past decades,numerous pharmaceutically relevant molecules with biaryl frameworks were improved by the approach of bioisosteric *** strategies for the synthesis of such BCP-aryls derivatives mostly depend on the stepwise C-C formation via the direct addition to bridgehead C-C bond of[1.1.1]propellane to provide active BCP-intermediates and followed by a second transitionmetal cross-coupling ***,these pioneer works were limited by the low step economy,the use of unstable reagents,and harsh conditions in industrial productions.

关键词： synthesis substituted alkyl

Precision tuning of highly efficient Pt-based ternary alloys on nitrogen-doped multi-wall carbon nanotubes for methanol oxidation reaction

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Journal of Energy Chemistry 2024年第1期88卷 242-251,I0006页

作者： Xingqun Zheng Zhengcheng Wang Qian Zhou Qingmei Wang wei he Shun Lu College of Safety Engineering Chongqing University of Science&TechnologyChongqing 401331China College of Chemistry and Chemical Engineering Chongqing UniversityChongqing 400044China School of Chemistry and Chemical Engineering Guizhou UniversityGuizhou 550025GuiyangChina Department of Chemistry University of Rhode IslandKingston 02881Rhode IslandUnited States Chongqing Institute of Green and Intelligent Technology Chinese Academy of SciencesChongqing 400714China

The electrochemical methanol oxidation is a crucial reaction in the conversion of renewable *** enable the widespread adoption of direct methanol fuel cells(DMFCs),it is essential to create and engineer catalysts that are both highly effective and robust for conducting the methanol oxidation reaction(MOR).In this work,trimetallic PtCoRu electrocatalysts on nitrogen-doped carbon and multi-wall carbon nanotubes(PtCoRu@NC/MWCNTs)were prepared through a two-pot synthetic *** acceleration of CO oxidation to CO_(2) and the blocking of CO reduction on adjacent Pt active sites were attributed to the crucial role played by cobalt atoms in the as-prepared *** precise control of Co atoms loading was achieved through precursor *** physicochemical techniques were employed to analyze the morphology,element composition,and electronic state of the *** investigations and theoretical calculations confirmed that the Pt_(1)Co_(3)Ru_(1)@NC/MWCNTs exhibit excellent electrocatalytic performance and durability for the process of *** enhanced MOR activity can be attributed to the synergistic effect between the multiple elements resulting from precisely controlled Co loading content on surface of the electrocatalyst,which facilitates efficient charge *** interaction between the multiple components also modifies the electronic structures of active sites,thereby promoting the conversion of intermediates and accelerating the MOR ***,achieving precise control over Co loading in PtCoRu@NC/MWCNTs would enable the development of high-performance catalysts for DMFCs.

关键词： Ternary alloys Electrocatalysts Methanol oxidation reaction Electron transfer Theoretical calculations

A strategy to synthesize phosphorus-containing nickel phyllosilicate whiskers to enhance the flame retardancy of epoxy composites with excellent mechanical and dry-friction properties

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Frontiers of Chemical Science and Engineering 2024年第3期18卷 39-50页

作者： Shibin Nie Zongquan Zhao Yuxuan Xu wei he Wenli Zhai Jinian Yang School of Public Security and Emergency Management Anhui University of Science and TechnologyHefei231131China School of Safety Science and Engineering Anhui University of Science and TechnologyHuainan232001China School of Materials Science and Engineering Anhui University of Science and TechnologyHuainan232001China Institute of Energy Hefei Comprehensive National Science CenterHefei230000China

To enhance the fire safety and wear resistance of epoxy,phosphorus-containing nickel phyllosilicate whiskers(FP-NiPS)were synthesized using a facile hydrothermal technology,with 9,10-dihydro-9-oxa-10-phosphaphenanthrene as the organic *** impacts of FP-NiPS on the thermal stability,flame retardancy,and mechanical and tribological properties of EP composites were *** findings demonstrated that 5 wt%FP-NiPS elevated the limiting oxygen index of the EP composite from 23.8%to 28.4%,achieving a V-0 rating during vertical burning ***-NiPS could enhance the thermal stability of epoxy resin(EP)and facilitate the development of a dense and continuous carbon layer,thereby significantly improving the fire safety of the EP *** FP-NiPS led to an 8.2%increase in the tensile strength and a 38.8%increase in the elastic modulus of the EP composite,showing outstanding mechanical ***,FP-NiPS showed remarkable potential in enhancing the wear resistance of *** wear rate of 1 wt%FP-NiPS is 2.34×10^(−5) mm^(3)·N^(−1)·m^(−1),a decrease of 66.7%compared to *** work provides a novel promising modification method to enhance the fire safety,mechanical and wear resistance properties of EP.

关键词： nickel phyllosilicate epoxy resin flame retardant wear resistance mechanical property

Simulation of random fiber Bragg grating array in polarization-maintaining fiber based on photonic localization effect

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Optoelectronics Letters 2024年第8期20卷 460-471页

作者： LI Zhihan he wei LI Shaode Key Laboratory of the Ministry of Education for Optoelectronic Measurement Technology and Instrument Beijing Information Science and Technology UniversityBeijing 100192China Beijing Laboratory of Optical Fiber Sensing and System Beijing Information Science and Technology UniversityBeijing 100192China

Mid-infrared wavelength switchable and dual-wavelength random laser output has many potential applications.A polarization-maintaining random fiber Bragg grating(PMRFBG)array based on the photonic localization effect of longitudinal invariant transverse disorder in fiber structure is proposed,which can be used as random feedback of dual-wavelength and wavelength switchable output of random fiber laser(RFL).The random fiber Bragg grating(RFBG)array was designed on the panda-type polarization-maintaining fiber(PMF),and the two center wavelengths were 2151.60 nm and 2152.22 nm,*** RFBG array was designed on the bow tie-type PMF,and the two center wavelengths were obtained,which were 2153.08 nm and 2153.96 nm,*** RFBG array with a center wavelength of 2139.27 nm was designed on single-mode fiber(SMF).The length of individual fiber Bragg grating(FBG)and PMRFBG,the refractive index modulation depth,the number of cascaded gratings,and the distance between gratings have different effects on the full width at half maximum(FWHM)and reflectance of the RFBG and PMRFBG array,but not on the central wavelength,as obtained by simulation using the transmission matrix *** designed PMRFBG array provides theoretical support for the design of the feedback mechanism of RFL.

关键词： fiber polarization random

Acute Bacillus cereus endophthalmitis caused by ocular perforation injury and occult intravitreal cilium implantation:a case report

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International Journal of Ophthalmology(English edition) 2024年第5期17卷 976-978页

作者： Ling Zhang Bin Chen wei-Min he Department of Ophthalmology West China HospitalSichuan UniversityChengdu 610041Sichuan ProvinceChina Department of Ophthalmology the People’s Hospital of LeshanLeshan 614000Sichuan ProvinceChina

Dear Editor,We present a case of acute Bacillus cereus(***)endophthalmitis in a patient with an intraocular perforation injury combined with occult intravitreal cilium *** endophthalmitis is a severe intraocular infection commonly caused by post-traumatic *** often leads to significant vision loss or even eye loss within 12-48h[1].The presence of an intraocular foreign body(IOFB)increases the risk of infection,while early surgical removal of IOFBs can prevent endophthalmitis,some IOFBs are difficult to detect *** Medical Ethics Review Board of West China Hospital of Sichuan University waived application for a clinical study because this was a retrospective report of a single patient based on imaging and because no human experimentation was *** patient provided written informed consent to use the imaging data for publication.

关键词： endophthalmitis ilium injuries

Fast and Accurate Predictor-Corrector Methods Using Feedback-Accelerated Picard Iteration for Strongly Nonlinear Problems

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Computer Modeling in Engineering & Sciences 2024年第5期139卷 1263-1294页

作者： Xuechuan Wang wei he Haoyang Feng Satya N.Atluri School of Astronautics Northwestern Polytechnical UniversityXi’an710072China Department of Mechanical Engineering Texas Tech UniversityLubbock79409USA

Although predictor-corrector methods have been extensively applied,they might not meet the requirements of practical applications and engineering tasks,particularly when high accuracy and efficiency are necessary.A novel class of correctors based on feedback-accelerated Picard iteration(FAPI)is proposed to further enhance computational *** optimal feedback terms that do not require inversion of matrices,significantly faster convergence speed and higher numerical accuracy are achieved by these correctors compared with their counterparts;however,the computational complexities are comparably *** advantages enable nonlinear engineering problems to be solved quickly and accurately,even with rough initial guesses from elementary *** proposed method offers flexibility,enabling the use of the generated correctors for either bulk processing of collocation nodes in a domain or successive corrections of a single node in a finite difference *** our method,the functional formulas of FAPI are discretized into numerical forms using the collocation *** collocated iteration formulas can directly solve nonlinear problems,but they may require significant computational resources because of the manipulation of *** address this,the collocated iteration formulas are further converted into finite difference forms,enabling the design of lightweight predictor-corrector algorithms for real-time *** generality of the proposed method is illustrated by deriving new correctors for three commonly employed finite-difference approaches:the modified Euler approach,the Adams-Bashforth-Moulton approach,and the implicit Runge-Kutta ***,the updated approaches are tested in solving strongly nonlinear problems,including the Matthieu equation,the Duffing equation,and the low-earth-orbit tracking *** numerical findings confirm the computational accuracy and efficiency of the derived predictor-correc

关键词： Predictor-corrector method feedback-accelerated Picard iteration nonlinear dynamical system real-time computation