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Core shift limitation in investment casting process of hollow turbine blade

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Chinese Journal of Aeronautics 2024年第8期37卷 513-526页

作者： Kang CUI Lin jing Ruisong JIANG Longnv YU xiao GAO Automation and Software Engineering Shanxi UniversityTaiyuan 030006China Key Laboratory of High Performance Manufacturing for Aero Engine Ministry of Industry and Information TechnologySchool of Mechanical EngineeringNorthwestern Polytechnical UniversityXi’an 710072China School of Mechanical Engineering Sichuan UniversityChengdu 610065China

The deviation in wall thickness caused by core shift during the investment casting process significantly impacts the strength and service life of hollow turbine *** address this issue,a core shift limitation method is developed in this ***,a shift model is established based on computational fluid dynamics and motion simulation to predict the movement of the ceramic core in investment casting ***,utilizing this model,an optimization method for fixturing layout inside the refractory ceramic shell is devised for the ceramic *** casting experiment demonstrates that by utilizing the optimized fixture layout,not only can core shift during the investment casting pouring process be effectively controlled,but also the maximum wall thickness error of the blade can be reduced by 42.02%.In addition,the core shift prediction is also validated,with a prediction error of less than 26.9%.

关键词： Hollow turbine blade Wall thickness Ceramic core Shift prediction Fixturing layout optimization

Impact of Carbon Chain Structures in the Backbone on the Flexibility of Modified Polyarylene Sulfide Resins: Molecular Dynamics Simulations and Mesoscopic Analysis

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Chinese Journal of Polymer Science 2024年第4期42卷 544-557页

作者： Chi Zhang Rong liu jing-Yuan liu Wen-Wei Jiang Key Laboratory of Fine Chemical Engineering and Functional Materials School of Chemical EngineeringSichuan UniversityChengdu610065China

In the domain of high-performance engineering polymers, the enhancement of mechanical flexibility in poly(phenylene sulfide) (PPS) resins has long posed a significant challenge. A novel molecular structure, designated as PP-He-IS, wherein imide rings and an aliphatic hexylene chain are covalently incorporated into the PPS backbone to enhance its flexibility, is introduced in this study. Molecular dynamics (MD) simulations are employed to systematically explore the effects of diversifying the backbone chain structures by substituting phenyl units with alkyl chains of varying lengths, referred to as PP-A-IS where “A” signifies the distinct intermediary alkyl chain configurations. Computational analyses reveal a discernable decrement in the glass transition temperature (Tg) and elastic modulus, counterbalanced by an increment in yield strength as the alkyl chain length is extended. Notably, the PP-He-IS variant is shown to exhibit superior yield strength while simultaneously maintaining reduced elastic modulus and Tg values, positioning it as an advantageous candidate for flexible PPS applications. Mesoscopic analyses further indicate that structures such as PP-He-IS, PP-Pe-IS, and PP-Bu-IS manifest remarkable flexibility, attributable to the presence of freely rotatable carbon-carbon single bonds. Experimental validation confirms that a melting temperature of 504 K which is lower than that of conventional PPS, and lower crystallinity are exhibited by PP-He-IS, thereby affording enhanced processability without compromising inherent thermal stability. Novel insights into the strategic modification of PPS for mechanical flexibility are thus furnished by this study, which also accentuates the pivotal role played by molecular dynamics simulations in spearheading high-throughput investigations in polymer material modifications.

关键词： Molecular dynamics simulations Polyarylene Sulfide Main-chain modifications Flexibility Aliphatic hexylene chain

SOLVING OPTIMIZATION PROBLEMS OVER THE STIEFEL MANIFOLD BY SMOOTH EXACT PENALTY FUNCTIONS

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Journal of Computational Mathematics 2024年第5期42卷 1246-1276页

作者： Nachuan xiao Xin liu The Institute of Operations Research and Analytics National University of SingaporeSingapore State Key Laboratory of Scientific and Engineering Computing Academy of Mathematics and Systems ScienceChinese Academy of Sciencesand University of Chinese Academy of SciencesChina

In this paper,we present a novel penalty model called ExPen for optimization over the Stiefel *** from existing penalty functions for orthogonality constraints,ExPen adopts a smooth penalty function without using any first-order derivative of the objective *** show that all the first-order stationary points of ExPen with a sufficiently large penalty parameter are either feasible,namely,are the first-order stationary points of the original optimization problem,or far from the Stiefel ***,the original problem and ExPen share the same second-order stationary ***,the exact gradient and Hessian of ExPen are easy to *** a consequence,abundant algorithm resources in unconstrained optimization can be applied straightforwardly to solve ExPen.

关键词： Orthogonality constraint Stiefel manifold Penalty function

A mixed-valence polyoxometalate-based 3D inorganic framework cathode material for high-efficiency rechargeable AZIBs

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Rare Metals 2024年第8期43卷 3677-3691页

作者： Qing Han Hao-Ran xiao Tao Zhou Bing-Chuan Li liu Yang Ling-Ling Xie Xue-jing Qiu Xian-Yong Wu Li-Min Zhu xiao-Yu Cao School of Chemistry and Chemical Engineering Henan University of TechnologyZhengzhou 450001China Key Laboratory of High Specific Energy Materials for Electrochemical Power Sources of Zhengzhou City Zhengzhou 450001China College of Materials Engineering Henan University of EngineeringZhengzhou450007China School of Environmental Engineering Henan University of TechnologyZhengzhou 450001China Department of Chemistry University of Puerto Rico-Rio Piedras CampusSan JuanPR 00925USA

The global trend towards new energy storage systems has stimulated the development of electrochemical energy storage *** these technologies,rechargeable aqueous zinc-ion batteries(AZIBs)have attracted considerable interest as a potential alternative to lithium-ion batteries(LIBs)due to their affordable cost,environmental compatibility and high safety *** this study,a high-quality electrode for AZIBs has been successfully developed using a dehydrated mixed-valence polyoxometalate-based three-dimensional(3D)inorganic framework material known as[H_6Mn_(3)V^Ⅳ_(15)V-^Ⅴ_(4O)_(46)(H_2O)_(12)](3D-MnVO).This innovative 3D-MnVO material is built from the alternate connections of{V_(19)O_(46)}"sphere-shaped"clusters andμ_(2)-{Mn(H_(2)O)_(4)}bridges,where each{V_(19)O_(46)}cluster is surrounded by three pairs of vertically distributed{Mn(H_(2)O)_(4)}units,thus resulting in the 3D interpenetrating grid-like network from the infinite[-{V_(19)O_(46)}-μ_(2)-Mn(H_(2)O)_(4)-{V_(19)O_(46)}]_∞chains in three mutually perpendicular *** 3D framework structure of 3D-MnVO possesses abundant oxygen vacancies,spacious and multi-level interconnected channels for ion transport,which facilitates the efficient intercalation/deintercalation of hydrated Zn^(2+)into the pores of the primary structure via the intercalation capacitance *** a result,the 3D-MnVO electrode exhibits excellent diffusion rates and minimal interfacial *** a current density of 0.1 A·g^(-1),the 3D-MnVO cathode delivers a commendable discharge capacity of170.5 mAh·g^(-1)with 81.6%capacity retention after100 charge/discharge ***,even at a high current density of 1.0 A·g^(-1),the 3D-MnVO electrode delivers a remarkable reversible capacity of198.9 mAh·g^(-1).Our research results provide valuable insights into the development of advanced polyoxometalate-based 3D inorganic framework electrode materials for high-performance rechargeable AZIBs.

关键词： Cathode Polyoxometalate 3D inorganic framework Zinc-ion batteries Energy storage mechanism

Quantitative Analysis of Seeing with Height and Time at Muztagh-Ata Site Based on ERA5 Database

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Research in Astronomy and Astrophysics 2024年第1期24卷 87-95页

作者： xiao-Qi Wu Cun-Ying xiao Ali Esamdin jing Xu Ze-Wei Wang Luo xiao Institute for Frontiers in Astronomy and Astrophysics Beijing Normal UniversityBeijing 102206China Department of Astronomy Beijing Normal UniversityBeijing 100875China Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China

Seeing is an important index to evaluate the quality of an astronomical *** estimate seeing at the Muztagh-Ata site with height and time quantitatively,the European Centre for Medium-Range Weather Forecasts reanalysis database(ERA5)is *** calculated from ERA5 is compared consistently with the Differential Image Motion Monitor seeing at the height of 12 *** show that seeing decays exponentially with height at the Muztagh-Ata *** decays the fastest in fall in 2021 and most slowly with height in *** seeing condition is better in fall than in *** median value of seeing at 12 m is 0.89 arcsec,the maximum value is1.21 arcsec in August and the minimum is 0.66 arcsec in *** median value of seeing at 12 m is 0.72arcsec in the nighttime and 1.08 arcsec in the *** is a combination of annual and about biannual variations with the same phase as temperature and wind speed indicating that seeing variation with time is influenced by temperature and wind *** Richardson number Ri is used to analyze the atmospheric stability and the variations of seeing are consistent with Ri between *** quantitative results can provide an important reference for a telescopic observation strategy.

关键词： site testing atmospheric effects methods:data analysis telescopes Earth

Suppressing the lattice oxygen diffusion via high-entropy oxide construction towards stabilized acidic water oxidation

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Nano Research 2024年第3期17卷 1107-1113页

作者： jing Ni Zhaoping Shi Yibo Wang Jiahao Yang Hongxiang Wu Pengbo Wang Kai Li Meiling xiao Changpeng liu Wei Xing State Key Laboratory of Electroanalytic Chemistry Jilin Province Key Laboratory of Low Carbon Chemistry PowerChangchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei 230026China State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China

The scale-up deployment of ruthenium(Ru)-based oxygen evolution reaction(OER)electrocatalysts in proton exchange membrane water electrolysis(PEMWE)is greatly restricted by the poor *** the lattice-oxygen-mediated mechanism(LOM)has been identified as the major contributor to the fast performance degradation,impeding lattice oxygen diffusion to inhibit lattice oxygen participation is imperative,yet remains challenging due to the lack of efficient ***,we strategically regulate the bonding nature of Ru–O towards suppressed LOM via Ru-based high-entropy oxide(HEO)*** lattice disorder in HEOs is believed to increase migration energy barrier of lattice *** a result,the screened Ti_(23)Nb_(9)Hf_(13)W_(12)Ru_(43)O_(x) exhibits 11.7 times slower lattice oxygen diffusion rate,84%reduction in LOM ratio,and 29 times lifespan extension compared with the state-of-the-art RuO_(2) *** work opens up a feasible avenue to constructing stabilized Ru-based OER catalysts towards scalable application.

关键词： ruthenium-based high-entropy oxide suppressing the lattice oxygen diffusion acidic oxygen evolution reaction

Polymer-to-Monomers Chemically Recyclable Poly(imide-imine)Plastics with Extreme-Condition Resistance and Flame Retardancy

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Chinese Journal of Polymer Science 2024年第10期42卷 1525-1535,I0012页

作者： Zhen-Yu Wang xiao-Kong liu State Key Laboratory of Supramolecular Structure and Materials College of ChemistryJilin UniversityChangchun130012China

Polyimides are a family of high-tech plastics that have irreplaceable applications in the fields of aerospace,defense,and opto-electronics,but polyimides are difficult to be reprocessed and recycled at the end of their service life,resulting in a significant waste of ***,it is of great significance to develop recyclable polyimides with comparable properties to the commercial ***,we report a novel polymer-to-monomers chemically recyclable poly(imide-imine)(PtM-CR-PII)plastic,synthesized by cross-linking the amine-terminated aromatic bisimide monomer and the hexa-vanillin terminated cyclophosphazene monomer via dynamic imine *** PtM-CR-PII plastic exhibits comparable mechanical and thermal properties as well as chemical stability to the commercial *** PtM-CR-PII plastic possesses a high Young’s modulus of≈3.2 GPa and a tensile strength as high as≈108 MPa,which also exhibits high thermal stability with a glass transition temperature of≈220℃.Moreover,the PtM-CR-PII plastic exhibits outstanding waterproofness,acid/alkali-resistance,and solvent-resistance,its appearance and mechanical properties can be well maintained after long-term soaking in water,highly concentrated acid and base,and various organic ***,the cyclophosphazene moieties endow the PtM-CR-PII plastic with excellent flame *** PtM-CR-PII plastic exhibits the highest UL-94 flame-retarding rating of V-0 and a limiting oxygen index(LOI)value of 45.5%.Importantly,the PtM-CR-PII plastic can be depolymerized in an organic solvents-acid mixture medium at room temperature,allowing easy separation and recovery of both monomers in high *** recovered pure monomers can be used to regenerate new PtM-CR-PII plastics,enabling sustainable polymer-monomers-polymer circulation.

关键词： Chemical recyclability Polyimides Polyimines Dynamic imine bonds Mechanical properties Chemical stability

Thermodynamic nature of black holes in coexistence region

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Science China(Physics,Mechanics & Astronomy) 2024年第5期67卷 27-32页

作者： Shao-Wen Wei Yu-xiao liu Lanzhou Center for Theoretical Physics Key Laboratory of Theoretical Physics of Gansu Provinceand Key Laboratory of Quantum Theory and Applications of Mo ELanzhou UniversityLanzhou 730000China Institute of Theoretical Physics&Research Center of Gravitation Lanzhou UniversityLanzhou 730000China

Studying the system state of coexistence regions will peek into to reveal microscopic interactions between different phases of a thermodynamic ***,there is no effective method to study thermodynamic nature of the coexistence black hole regions for the failure of the equation of *** at these coexistence states,in this work,we develop a general approach by introducing two new ratio *** first one is the ratio of the horizon radii of the saturated coexistence small and large black holes,and the second one measures that of the small black hole molecule number to the total molecule *** demonstrate that the first parameter can serve as an order parameter to characterize the first-order phase *** study also shows that the black hole state in the coexistence region is uniquely determined by these two introduced parameters bounded between 0 and *** results are quite significant in the analytical study of phase transition and the microscopic nature of black hole in the coexistence regions.

关键词： transition. state. thermodynamic

Demyelinating neuropathy in patients with hepatitis B virus: A case report

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World Journal of Clinical Cases 2024年第10期12卷 1766-1771页

作者： xiao-xiao Yan Jin Huang jing Lin Department of Neurology The Third Affiliated Hospital of Wenzhou Medical UniversityRuian 325000Zhejiang ProvinceChina

BACKGROUND Hepatitis B rarely leads to demyelinating neuropathy,despite peripheral neuropathy being the first symptom of hepatitis B *** SUMMARY A 64-year-old man presented with sensorimotor symptoms in multiple peripheral *** testing showed that these symptoms were due to hepatitis *** undergoing treatment involving intravenous immunoglobulin and an antiviral agent,there was a notable improvement in his *** Although hepatitis B virus(HBV)infection is known to affect hepatocytes,it is crucial to recognize the range of additional manifestations linked to this *** connection between long-term HBV infection and demyelinating neuropathy has seldom been documented;hence,prompt diagnostic and treatment are *** patient's positive reaction to immunoglobulin seems to be associated with production of the antigen-antibody immune complex.

关键词： Hepatitis B virus infection Extrahepatic manifestations Demyelinating neuropathy Intravenous immunoglobulin Electroneuromyography Case report