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Flow Fields with Vortex in a Small Semi-open Axial Fan

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Journal of Thermal Science 2009年第4期18卷 294-300页

作者： Norimasa. Shiomi Yoichi Kinoue ying zi jin Toshiaki Setoguchi Kenji Kaneko Department of Mechanical Engineering Saga University 1 Honjo-machi Saga 840-8502 Japan Institute of Mechatronics Zhejiang Sci-Tech University Xiasha Higher Educational Zone Hangzhou 310018 China

In order to clarify the effect of tip clearance （TC） size on fan performance and the flow field at rotor outlet in a small semi-open axial fan, the experimental investigation was carried out. The tip diameter of test fan rotor was 180mm and test TC sizes were lmm （TC=1mm） and 4mm （TC=4mm）. Fan characteristics tests were carried out for two cases of TC size and three-dimensional velocity fields at rotor outlet were measured using a single slant hot-wire probe at four flow-rate conditions. As a result, it was found that the pressure - flow-rate characteristics curves for two cases showed almost the same tendency. However, the ensemble averaged velocity profiles along radial measurement stations of TC-4mm largely changed compared with that of TC=1mm in cases of small flow-rate condition. From the phase-locked averaging results, it was also found that the vortex existed in the rotor outlet flow field of high flow-rate condition for each TC case. Compared with the vortices for TC=1mm and TC=4mm, the vortex for TC=4mm was stronger than that for TC=1mm.

关键词： fan semi-open type vortex tip clearance

Flow Fields with Tip Leakage Vortex in a Small Axial Cooling Fan

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Journal of Thermal Science 2008年第2期17卷 156-162页

作者： Norimasa Shiomi ying zi jin Kenji Kaneko Yoichi Kinoue T. Setoguchi Department of Mechanical Engineering Saga University 1 Honjo-machi Saga 840-8502 Japan Institute of Mechatromcs Zhejiang Sci-Tech University Hangzhou 310018 China

In order to improve the fan characteristics, especially efficiency and noise level of a small axial cooling fan with a large tip clearance, the internal flow measurements with tip leakage vortex were carried out at fan rotor outlet us- ing an I-type hot-wire probe. The probe was set toward two directions, parallel and normal to the meridional plane of test fan, and the two directional velocity components were measured. From the result of fan test it was found that the test fan didn＇t have the unstable characteristic with a positive gradient on its pressure - flow-rate curve. From the results of velocity measurement it was observed that the tip leakage vortex exited at maximum efficiency flow-rate and large flow-rate conditions. However, at small flow-rate conditions the tip leakage vortex was not observed and it was found that the flow field were enlarged toward radial outwards

关键词： Axial fan cooling fan internal flow and tip leakage vortex

Analysis of choked two-phase flows of gas and particle in a C-D nozzle

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Theoretical & Applied Mechanics Letters 2017年第6期7卷 331-338页

作者： Guang Zhang Heuy Dong Kim ying zi jin Department of Mechanical Engineering Andong National University College of Mechanical Engineering & Automation Zhejiang Sci-Tech University

Particle-gas two-phase flows show significantly different behaviors compared to single gas flow through a convergent-divergent nozzle. Non-equilibrium effects, thermal and velocity lag results to the inefficiency of nozzle performance. In the present studies, theoretical analysis and numerical simulations were carried out to investigate particle-gas flows in a C-D nozzle. Homogeneous equilibrium model that no lag in velocity and temperature occurs between particles and gas phase was used to derive mass flow rate and sound speed of multiphase flows. Two-phase flows are regarded as isentropic flows that isentropic relations can be used for homogeneous equilibrium model. Discrete phase model （DPM） where interaction with continuous phase and discrete random walk model were considered was used to calculate particle- gas flows. Particle mass loadings were varied to investigate their effects on choking phenomena of particle-gas flows. Mass flow rate and sound speed of mixture flows were theoretically calculated by homogeneous equilibrium model and compared with numerical results. Shock wave structure and particle number density were also obtained to be different at different particle mass loading and operating pressure conditions.

关键词： Multiphase flows Particle number density Shock wave Sound speed of mixture Flow choking

A Computational Study of the Gas-Solid Suspension Flow through a Supersonic Nozzle

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Open Journal of Fluid Dynamics 2012年第4期2卷 242-247页

作者： Jian Guo Sun Heuy Dong Kim jin Ouk Park ying zi jin College of Mechanical Engineering & Automation Zhejiang Sci-Tech University Hangzhou China School of Mechanical Engineering Andong National University Andong Korea

The present study focuses on numerical simulation of the gas-solid suspension flow in a supersonic nozzle. The Euler- Lagrange approach using a Discrete Phase Model (DPM) has been used to solve the compressible Navier-Stokes equa- tions. A fully implicit finite volume scheme has been employed to discretize the governing equations. Based upon the present CFD results, the particle loading effect on gas-solid suspension flow was investigated. The results show that the presence of particles has a big influence on the gas phase behavior. The structure of shock train, the separation point, and the vortex of the backflow are all related to particle loading. As the particle loading increases the flow characteris- tics behave differently such as 1) the strength of shock train decreases, 2) the separation point moves toward the nozzle exit, 3) the number and strength of vortex increase, 4) the strength of first shock also increases while the other pseudo shocks decreases. The change of gas flow behavior in turn affects the particle distribution. The particles are concen- trated at the shear layers separated from the upper wall surface.

关键词： Gas-Solid Suspension Flow Supersonic Nozzle Flow Choking Internal Flow Shock Wave

Computational Analysis of Mixing Guide Vane Effects on Performance of the Supersonic Ejector-Diffuser System

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Open Journal of Fluid Dynamics 2012年第3期2卷 45-55页

作者： Fan Shi Kong Heuy Dong Kim ying zi jin Toshiaki Setoguchi College of Mechanical Engineering & Automation Zhejiang Sci-Tech University Hangzhou China Department of Mechanical Engineering Saga University Saga Japan School of Mechanical Engineering Andong National University Andong Korea

The flow field in the ejector-diffuser system and its optimal operation condition are hardly complicated due to the complicated turbulent mixing, compressibility effects and even flow unsteadiness which are generated inside the ejector- diffuser system. This paper aims at the improvement in ejector-diffuser system by focusing attention on entrainment ratio and pressure recovery. Several mixing guide vanes were installed at the inlet of the secondary stream for the purpose of the performance improvement of the ejector system. A Computational Fluid Dynamics (CFD) method based on Fluent has been applied to simulate the supersonic flows and shock waves inside the ejector. A finite volume scheme and density-based solver with coupled scheme were applied in the computational process. Standard k-ω turbulent model, implicit formulations were used considering the accuracy and stability. Previous experimental results showed that more flow vortexes were generated and more vertical flow was introduced into the stream under a mixing guide vane influence. Besides these effects on the secondary stream, the mixing guide vane effects on the shock system of the primary stream were also investigated in this paper. Optimal analysis results of the mixing guide vane effects were also carried out in detail in terms of the positions, lengths and numbers to achieve the best operation condition. The comparison of ejector performance with and without the mixing guide vane was obtained. The ejector-diffuser system performance is discussed in terms of the entrainment ratio, pressure recovery as well as total pressure loss.

关键词： Ejector-Diffuser System Mixing Guide Vane Shock Wave Compressible Flow Supersonic Flow

Broadband and perfect terahertz absorber based on multilayer metamaterial with cross-ring patterned structures

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Optoelectronics Letters 2025年第1期21卷 1-6页

作者： WEN jin LIU Zhanzhi WU Zhengwei PAN Yu ZHANG ying School of Science Xi'an Shiyou University Shaanxi Key Laboratory of Measurement and Control Technology for Oil and Gas Wells

Broadband and perfect terahertz absorber based on multilayer metamaterial using cross-ring patterned structures is proposed and investigated. The structure of the absorber is double absorption layers consisting of a chromium cross ring and eight isosceles right triangles. The unique structure of the double absorbing layers excites the electric dipole multimode resonance, giving rise to high absorption performance. Meanwhile, the influence of construal parameters on absorber behavior is also discussed. The numerical results show that the absorption achieves over 90% ranging from 2.45 THz to 6.25 THz and 99% absorption in the range of 3.7—5.3 THz. The realization of broadband and perfect absorber is described using the impedance matching principle. It is obviously found that the absorber is insensitive to the high angle of incidence for both transverse electric(TE) and transverse magnetic(TM) polarizations. Compared with the former reports, this absorber has remarkable improved absorption efficiency and smaller period. The terahertz absorber may be found applications in the fields of energy capture and thermal detection.

关键词： Metamaterials

Neuroprotective potential for mitigating ischemia-reperfusion-induced damage

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Neural Regeneration Research 2025年第8期20卷 2199-2217页

作者： zi Ye Runqing Liu Hangxing Wang Aizhen Zuo Cen jin Nan Wang Huiqi Sun Luqian Feng Hua Yang The Clinical Medical College Guizhou Medical UniversityGuiyangGuizhou ProvinceChina Division of Infectious Diseases Department of Internal MedicinePeking Union Medical College HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijingChina School of Medical Imaging Guizhou Medical UniversityGuiyangGuizhou ProvinceChina Division of Gastroenterology First Affiliated Hospital of Zhengzhou UniversityZhengzhouHenan ProvinceChina The Second Clinical Medical College Lanzhou UniversityLanzhouGansu ProvinceChina Department of Neurosurgery Affiliated Hospital of Guizhou Medical UniversityGuiyangGuizhou ProvinceChina

Reperfusion following cerebral ischemia causes both structural and functional damage to brain tissue and could aggravate a patient's condition;this phenomenon is known as cerebral ischemia-reperfusion *** studies have elucidated the neuroprotective role of the sirtuin protein family(Sirtuins)in modulating cerebral ischemia-reperfusion ***,the potential of utilizing it as a novel intervention target to influence the prognosis of cerebral ischemia-reperfusion injury requires additional *** this review,the origin and research progress of Sirtuins are summarized,suggesting the involvement of Sirtuins in diverse mechanisms that affect cerebral ischemia-reperfusion injury,including inflammation,oxidative stress,blood-brain barrier damage,apoptosis,pyroptosis,and *** therapeutic avenues related to Sirtuins that may improve the prognosis of cerebral ischemia-reperfusion injury were also investigated by modulating Sirtuins expression and affecting representative pathways,such as nuclear factor-kappa B signaling,oxidative stress mediated by adenosine monophosphate-activated protein kinase,and the forkhead box *** review also summarizes the potential of endogenous substances,such as RNA and hormones,drugs,dietary supplements,and emerging therapies that regulate Sirtuins *** review also reveals that regulating Sirtuins mitigates cerebral ischemia-reperfusion injury when combined with other risk *** Sirtuins show promise as a potential target for the treatment of cerebral ischemiareperfusion injury,most recent studies are based on rodent models with circadian rhythms that are distinct from those of humans,potentially influencing the efficacy of Sirtuinstargeting drug ***,this review provides new insights into the role of Sirtuins in the pathology and treatment of cerebral ischemia-reperfusion injury.

关键词： apoptosis autophagy blood-brain barrier dietary supplements drug hormones inflammation neuroprotection oxidative stress prognosis pyroptosis reperfusion injury risk factors RNA therapeutics

Deciphering fungal metabolon coupling tandem inverse-electrondemand Diels-Alder reaction and semipinacol rearrangement for the biosynthesis of spiro polycyclic alkaloids

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Science China Chemistry 2025年第1期68卷 288-296页

作者： Shuai Liu Wen-Qiang Xu ying-Tong Di Man-Cheng Tang Ding-Kang Chen Ming-Ming Cao Yao-Wen Chang Hong-Yu Tang Chun-Mao Yuan Jun-Bo Yang Zhi-Li Zuo Han Guo zi-Fei Xu ying Zeng Yun-Dong Wu Xiao-Jiang Hao Key Laboratory of Phytochemistry and Natural Medicines (Chinese Academy of Sciences) Kunming Institute of Botany Chinese Academy of Sciences University of Chinese Academy of Sciences Lab of Computational Chemistry and Drug Design State Key Laboratory of Chemical Oncogenomics Peking University Shenzhen Graduate School Shenzhen Bay Laboratory State Key Laboratory of Microbial Metabolism School of Life Sciences & Biotechnology Shanghai Jiao Tong University State Key Laboratory of Functions and Applications of Medicinal Plants Guizhou Medical University Molecular Biology Experimental Center Germplasm Bank of Wild Species in Southwest China Kunming Institute of Botany Chinese Academy of Sciences Yunnan Key Laboratory for Wild Plant Resources Kunming Institute of Botany Chinese Academy of Sciences Research Unit of Chemical Biology of Natural Anti-Virus Products Chinese Academy of Medical Sciences

In the intricate process of natural product biosynthesis, a metabolon can enhance metabolic flux by associating sequential enzymes. A fungal metabolon, comprising of flavin-dependent monooxygenase Spe F and P450 monooxygenase Spe G, is identified in the biosynthesis of spiro polycyclic alkaloids(+)-notoamide B and its diastereomer(+)-versicolamide B. Using notoamide E as a substance, Spe F/Spe G metabolon can control the stereoselectivity of its 2,3-epoxidation, followed by hydrogen atom ion at C-17 to generate reactive epoxide tau-m A with dienyl iminium unit. Subsequently,(+)-notoamide B and(+)-versicolamide B are produced via tandem nonenzymatic inverse-electron-demand Diels-Alder reaction and semipinacol rearrangement. This provides the first example of metabolon in the biosynthesis of spiro-prenylated indole alkaloids.

关键词： metabolon Diels-Alder reaction semipinacol rearrangement biosynthesis notoamides spiro polycyclic alkaloids

Tuning the porosity of {Co12IICo8III（μ3-OH）24（X）}11+ supramolecular frameworks by reaction time for D2/H2 separation

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Science China Chemistry 2025年

作者： Zhuozhou Xie Zhu Zhuo zi-Ang Nan Qing Li Xiufang Li zi-Xiu Lu Linzhe Lü jin Liu Luyao Liu Wenjing Wang Wei Wang Daqiang Yuan You-Gui Huang State Key Laboratory of Structure Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences University of Chinese Academy of Sciences Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials Xiamen Institute of Rare Earth Materials Haixi InstitutesChinese Academy of Sciences State Key Laboratory of Physical Chemistry of Solid Surfaces Department of Chemistry College of Chemistry and Chemical EngineeringXiamen University

Systematicly tuning the porosities of porous materials is crucial for targeted gas mixture separation,yet it remains a longstanding *** a common strategy,altering the phenylene ring count in the organic building units has been exploited to adjust pore apertures in metal organic frameworks （MOFs） and covalent organic frameworks （COFs）,resulting in only a stepwise pore size variation of approximately 2.8?.Unlike MOFs and COFs,the porosities for supramolecular assembly frameworks are highly dependent on the packings of the molecular building units in the *** above strategy cannot be applied to supramolecular assembly frameworks and other strategies are required to adjust pore apertures in supramolecular frameworks,especially to achieve porous materials with the optimal pore size for D2/H2separation （～3?）.Here,we successfully modulate the porosity of supramolecular frameworks of[CoII1+12CoIII8L12（μ3-OH）24（X）]1clusters （L=mono-deprotonated 1-iminoisoindole-3-amine,X=ClO?4or Cl?） by controlling the duration of self-assembly *** simply adjusting the reaction time,we obtain three[CoII12CoIII8L12（μ3-OH）24（X）]11+supramolecular frameworks:[CoII12CoIII8（μ3-OH）24（ClO4）L12)]·（Cl）4·（HCO2）7（1）,[CoII12CoIII8L12（μ3-OH）24（Cl）]·（ClOI4）4·（Cl）6·（HCO2）·（H2O）10（2）,and[CoI12CoIII8L12（μ3-OH）24（Cl）]·（Cl）11·（H2O）12（3）.The different stacking patterns of the[CoII12CoIII8L12（μ3-OH）24（X）]11+clusters in these frameworks lead to significantly varied stabilities and *** 1 exhibits permanent porosity with interconnected channels and maintains stability under harsh *** contrast,compound 2 is nearly nonporous,and compound 3 becomes unstable upon *** pores of compound 1 show higher affinity to D2than H2,and the pore aperture diameter of compound 1 （～3.06?） meets the optimal porosity for D2/***,compound 1 demonstrates moderate D2/H2separation at 77 K (retention time:～7 min/g for D2/H2/Ne （10/10/80 vol%） in a flow of 5 mL

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