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Dynamic modeling and analysis of vortex filament motion using a novel curve-fitting method

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Chinese Journal of Aeronautics 2016年第1期29卷 53-65页

作者： chang-joo Kim Soo Hyung Park Sang Kyung Sung Sung-Nam Jung Department of Aerospace Information Engineering Konkuk UniversitySeoul 05029Republic of Korea

Applications of a novel curve-fitting technique are presented to efficiently predict the motion of the vortex filament, which is trailed from a rigid body such as wings and rotors. The gov- erning equations of the motion, when a Lagrangian approach with the present curve-fitting method is applied, can be transformed into an easily solvable form of the system of nonlinear ordinary dif- ferential equations. The applicability of Bezier curves, B-spline, and Lagrange interpolating polyno- mials is investigated. Local Lagrange interpolating polynomials with a shift operator are proposed as the best selection for applications, since it provides superior system characteristics with minimum computing time, compared to other methods. In addition, the Gauss quadrature formula with local refinement strategy has been developed for an accurate prediction of the induced velocity computed with the line integration of the Biot-Savart law. Rotary-wing problems including a vortex ring problem are analyzed to show the efficiency, accuracy, and flexibility in the applications of the pro- posed method.

关键词： Aerodynamics Biot-Savart law Curve-fitting method Free-vortex wake Rotary wing Vortex filament

The ALMA-QUARKS Survey.Ⅱ.The ACA 1.3 mm Continuum Source Catalog and the Assembly of Dense Gas in Massive Star-Forming Clumps

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Research in Astronomy and Astrophysics 2024年第6期24卷 119-139页

作者：许峰玮 Ke Wang Tie Liu Lei Zhu Guido Garay Xunchuan Liu Paul Goldsmith Qizhou Zhang Patricio Sanhueza Shengli Qin Jinhua He Mika Juvela Anandmayee Tej Hongli Liu Shanghuo Li Kaho Morii Siju Zhang Jianwen Zhou Amelia Stutz Neal JEvans kee-Tae Kim Shengyuan Liu Diego Mardones Guangxing Li Leonardo Bronfman Ken’ichi Tatematsu chang Won Lee Xing Lu Xiaofeng Mai Sihan Jiao James O.Chibueze Keyun Su Viktor L.Tóth Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China Department of Astronomy School of PhysicsPeking UniversityBeijing 100871China Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China Chinese Academy of Sciences South America Center for Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China Departamento de Astronomía Universidad de ChileLas Condes7591245 SantiagoChile Jet Propulsion Laboratory California Institute of Technology4800 Oak Grove DrivePasadena CA 91109USA Center for Astrophysics|Harvard&Smithsonian 60 Garden StreetCambridgeMA 02138USA National Astronomical Observatory of Japan National Institutes of Natural Sciences2-21-1 OsawaMitakaTokyo 181-8588Japan Astronomical Science Program The Graduate University for Advanced StudiesSOKENDAI2-21-1 OsawaMitakaTokyo 181-8588Japan School of Physics and Astronomy Yunnan UniversityKunming 650091China Yunnan Observatories Chinese Academy of SciencesKunming 650216China Department of Physics University of HelsinkiPO Box 64FI-00014 HelsinkiFinland Indian Institute of Space Science and Technology Thiruvananthapuram 695547KeralaIndia Max Planck Institute for Astronomy Königstuhl 17D-69117 HeidelbergGermany Department of Astronomy Graduate School of ScienceThe University of Tokyo7-3-1 HongoBunkyo-kuTokyo 113-0033Japan Max-Planck-Institut für Radioastronomie Auf dem Hügel 6953121 BonnGermany Departamento de AstronomÂıa Universidad de ConcepcionCasilla 160-CConcepci onChile Department of Astronomy The University of Texas at AustinTexas 78712-1205USA Korea Astronomy and Space Science Institute 776 Daedeokdae-roYuseong-guDaejeon 34055Republic of Korea Institute of Astronomy and Astrophysics Academia SinicaRoosevelt RoadTaipei 10617TaiwanChina South-Western Institute for Astronomy Research Yunnan UniversityKunming 650091China Korea Astronomy and Space Science Institute 776 Daedeok-daeroYuseong-guDaejeon 34055Republic of

Leveraging the high resolution,sensitivity,and wide frequency coverage of the Atacama Large Millimeter/submillimeter Array(ALMA),the QUARKS survey,standing for“Querying Underlying mechanisms of massive star formation with ALMA-Resolved gas Kinematics and Structures”,is observing 139 massive starforming clumps at ALMA Band 6(λ~1.3 mm).This paper introduces the Atacama Compact Array(ACA)7 m data of the QUARKS survey,describing the ACA observations and data *** multiwavelength data,we provide the first edition of QUARKS atlas,offering insights into the multiscale and multiphase interstellar medium in high-mass star *** ACA 1.3 mm catalog includes 207 continuum sources that are called ACA *** gas kinetic temperatures are estimated using three formaldehyde transitions with a non-LTE radiation transfer model,and the mass and density are derived from a dust emission *** ACA sources are massive(16–84 percentile values of 6–160 M_(⊙)),gravity-dominated(M∝R^(1.1))fragments within massive clumps,with supersonic turbulence(M>1)and embedded star-forming *** find a linear correlation between the masses of the fragments and the massive clumps,with a ratio of 6%between the *** considering fragments as representative of dense gas,the ratio indicates a dense gas fraction(DGF)of 6%,although with a wide scatter ranging from 1%to 10%.If we consider the QUARKS massive clumps to be what is observed at various scales,then the size-independent DGF indicates a self-similar fragmentation or collapsing mode in protocluster *** the ACA data over four orders of magnitude of luminosity-to-mass ratio(L/M),we find that the DGF increases significantly with L/M,which indicates clump evolutionary *** observed a limited fragmentation at the subclump scale,which can be explained by a dynamic global collapse process.

关键词： stars:formation ISM:kinematics and dynamics ISM:clouds stars:protostars

Lactobacillus plantarum inhibits epithelial barrier dysfunction and interleukin-8 secretion induced by tumor necrosis factor-a

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World Journal of Gastroenterology 2007年第13期13卷 1962-1965页

作者： Jae Sung Ko Hye Ran Yang Ju Young chang Jeong kee Seo Department of Pediatrics Seoul National University College of Medicine Seoul 110-744 Korea

AIM： To determine whether Lactobacillus plantarum can modify the deleterious effects of tumor necrosis factor-α （TNF-α） on intestinal epithelial cells. METHODS： Caco-2 cells were incubated with TNF-α alone or in the presence of L. plantarum. Transepithelial electrical resistance was used to measure epithelial barrier function. Interleukin 8 （IL-8） secretion by intestinal epithelial cells was measured using an ELISA. Cellular lysate proteins were immunoblotted using the anti-extracellular regulated kinase （ERK）, anti-phospho- ERK and anti-IκB-α. RESULTS： A TNF-α-induced decrease in transepithelial electrical resistance was inhibited by L. plantarum. TNF- α-induced IL-8 secretion was reduced by L. plantarum. L. plantarum inhibited the activation of ERK and the degradation of IκB-α in TNF-a-treated Caco-2 cells. CONCLUSION： Induction of epithelial barrier dysfunction and IL-8 secretion by TNF-α is inhibited byL. plantarum. Probiotics may preserve epithelial barrier function and inhibit the inflammatory response by altering the signal transduction pathway.

关键词： Lactobacillus plantarum Tumor necrosisfactor-α Epithelial barrier Interleukin-8 ERK IκB-α

Adaptive Model Predictive Control for Yaw System of Variable-speed Wind Turbines

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Journal of Modern Power Systems and Clean Energy 2021年第1期9卷 219-224页

作者： Dongran Song Qing chang Songyue Zheng Sheng Yang Jian Yang Young Hoon joo the School of Automation Central South Universityand Hunan Provincial Key Laboratory of Power Electronics Equipment and GridChangsha 410083China the School of Energy Science and Engineering Central South UniversityChangsha 410083China the School of IT Information and Control Engineering Kunsan National UniversityKunsan 54150Korea

Due to varying characteristics of the wind condition, the performance of the wind turbines can be optimized by adapting the parameters of the control system. In this letter, an adaptive technique is proposed for the novel model predictive control(MPC) for the yaw system of the wind turbines. The control horizon is adapted to the one with the best predictive performance among multiple control horizons. The adaptive MPC is demonstrated by simulations using real wind data, and its performance is compared with the baseline MPC at fixed control horizon. Results show that the adaptive MPC provides better comprehensive performance than the baseline ones at different preview time of wind directions. Therefore, the proposed adaptive technique is potentially useful for the wind turbines in the future.

关键词： Wind turbine yaw system wind direction adaptive model predictive control

Influence of Tropical Cyclone Landfalls on Spatiotemporal Variations in Typhoon Season Rainfall over South China

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Advances in Atmospheric Sciences 2010年第2期27卷 443-454页

作者： Min-Hee LEE chang-Hoi HO joo-Hong KIM Computational Science and Technology Seoul National University School of Earth and Environmental Sciences Seoul National University Met Office Hadley Centre

This study examined the impact of tropical cyclone (TC) landfalls on the spatiotemporal variations in the rainfall over South China for the period 1957–2005. The target region was selected to show the noteworthy contribution of TC landfalls to the total rainfall during the typhoon season (July–October). Two prevailing spatial variations in the rainfall were obtained from an EOF analysis. The first EOF mode displays singlesign variability over South China with an explained variance of 23.4%. The associated time series of this mode fluctuates on a decadal timescale and was found to be correlated with TC genesis in the South China Sea. The second EOF mode shows a seesaw pattern between Hainan Island/Guangdong Province and the remaining regions with an explained variance of 11.4%. This seesaw pattern results from an anti-correlation in seasonal TC landfalls between the two regions, which was found in previous studies. This is related to the strengthening (weakening) of the upper tropospheric jets and the corresponding development of a massive anticyclonic (cyclonic) circulation over East Asia. The EOF analysis was also conducted using just the data for rainfall caused by landfalling TCs. This revealed that the first EOF mode using just the TC-induced rainfall is nearly identical to the second mode from the total rainfall. The obvious seesaw pattern of the first mode when employing just the TC-induced rainfall in the EOF analysis implies that this pattern has larger temporal variability than the single-signed pattern (i.e., the first EOF mode using the total rainfall) in terms of TC landfalls. This study suggests that TC landfalls over South China and the accompanying rainfall significantly modulate the spatial variation of the typhoon season rainfall there.

关键词： rainfall tropical cyclone South China typhoon season

Electrophoretic Deposition of Oxide Nanoparticles for Electron Emission Enhancement

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Journal of Materials Science & Technology 2010年第11期26卷 1032-1036页

作者： Jong Rok Ahn Gil Seon Kang Hwack joo Lee chang joon Park Korea Research Institute of standards and Science

Four oxide nanoparticles,such as yttrium oxide,lanthanum oxide,cerium oxide and zirconium oxide were coated on rhenium filaments by an electrophoretic deposition *** oxide coatings were examined by scanning electron microscopy,and electron emission characteristics of the oxide-coated rhenium were studied to find alternative oxide materials for replacing the hazardous thorium *** four oxides tested in this work,yttrium oxide and lanthanum oxide coated rhenium showed enhanced electron emission compared with an uncoated ***,lanthanum oxide coating evaporated too quickly in a vacuum chamber,and hence yttrium oxide was found to be the only alternative material for use in a routine mass *** optimum coating thickness of the yttrium oxide and lanthanum oxide was around 20 μm.

关键词： Electrophoretic deposition Oxide nanoparticles Scanning electron microscopy (SEM) Electron emission

Microstructure analyses and phase-field simulation of partially divorced eutectic solidification in hypoeutectic Mg-Al Alloys

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Journal of Magnesium and Alloys 2022年第6期10卷 1672-1679页

作者： joo-Hee Kang Jiwon Park Kyung Song chang-Seok Oh Oleg Shchyglo Ingo Steinbach Korea Institute of Materials Science Changwon 51508Republic of Korea Interdisciplinary Centre for Advanced Materials Simulation Ruhr-University Bochum44801 BochumGermany

In this study the partially divorced eutectic microstructure ofα-Mg andβ-Mg17Al12was investigated by electron backscatter diffraction,transmission electron microscopy,and phase-field modeling in hypoeutectic Mg-Al *** orientation relationships between the individual eutecticαgrains,eutecticβphase,and primaryαgrains were *** the amount of eutectic morphology is primarily determined by the Al content,the in-depth microstructure analyses and the phase-field simulation suggest non-interactive nucleation and growth of eutecticαphase in theβphase grown on the interdendritic primaryα***,phase-field simulations showed a preferred nucleation sequence where theβphase nucleates first and subsequently triggers the nucleation of eutecticαphase at the movingβphase solidification front,which supports the microstructural analysis results.

关键词： Mg-Al alloy Partially divorced eutectic Solidification Electron backscatter diffraction Phase-Field modeling

Nitric oxide synthase 2 gene polymorphisms are associated with prostatic volume in Korean men with benign prostatic hyperplasia

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Asian Journal of Andrology 2010年第5期12卷 690-696页

作者： Koo Han Yoo Su Kang Kim joo-Ho Chung Sung-Goo chang Department of Urology School of Medicine Kyung Hee University Seou1130-702 Korea Kohwang Medical Research Institute School of Medicine Kyung Hee University Seoul 130-702 Korea

The precise aetiology of benign prostatic hyperplasia （BPH） remains unclear; however, it is known that immunological inflammatory processes have a role in the pathogenesis of BPH initiation and progression. Nitric oxide synthase 2 （NOS2） inducible expression is closely correlated with prostatic disease, including prostate cancer and BPH. The aim of this study was to investigate the relationship between NOS2 polymorphisms and BPH. With a cohort of 205 controls and 229 BPH subjects, we genotyped three single nucleotide polymorphisms （SNPs） in the NOS2 gene, including rs2779248 （promoter, -278 T/C）, rs 10459953 （5＇-untranslated region） and rs2297518 （exon 16, missense, Ser608Leu）, using direct sequencing and restriction fragment length polymorphism. The genotypic and allelic frequencies between control and BPH subjects were compared, and the associations among the BPH subjects were analyzed. SNPStats, SNPAnalyzer and HelixTree programmes were used to analyze SNPs. There was no association on SNPs between control and BPH subjects. When BPH subjects were analyzed, there was no association on SNPs between the low and high prostate-specific antigen groups. However, one SNP （rs 10459953, odds ratio [OR] = 0.44, 95% confidence interval [CI] = 0.29-0.65, P 〈 0.0001, in codominant model; OR = 0.23, 95% CI = 0.12-0.46, P 〈 0.0001, in dominant model; and OR = 0.46, 95% CI = 0.24-0.86, P = 0.015, in recessive model） was associated with prostatic volume in BPH. We detected a strong association in genotype frequencies of NOS2 SNP （rs10459953） between subjects with small and large prostatic volume in BPH. The result suggests that NOS2 may be associated with prostatic volume in BPH.

关键词： benign prostatic hyperplasia nitric oxide synthase 2 single nucleotide polymorphism

Turbulent vortex trains in narrow square arrayed rod bundles of a dual-cooled nuclear reactor

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Science China(Technological Sciences) 2013年第9期56卷 2143-2149页

作者： KIM Taehwan KIM Kyung Min BAE Ji-Yeul SHIN chang Hwan IN Wang-kee CHO Hyung Hee School of Mechanical Engineering Yonsei University Korea Atomic Energy Research Institute

The dual-cooled nuclear reactor is currently considered for improving the designs of current/future nuclear reactors. Investigation of the thermal-hydraulic characteristics of the nuclear reactor via experiments is essential for commercializing the dual-cooled nuclear reactor. In this paper, the turbulent flow in square arrayed six-rod bundles in the form of magnified copies of the dual-cooled and current OPR-1000 nuclear reactor is experimentally investigated by means of hot-wire anemometry and smoke-wire generation methods. Vortex trains which do not exist in an ordinary reactor subchannel are presented in the subchannel of the dual-cooled reactor. The vortices are induced by a span-wise velocity gradient. This flow pulsation phenomenon increases the inter-channel mixing of the subchannel. To understand the periodic feature of the pulsation, axial/cross velocities are measured and the periodic characteristic frequencies are obtained by a Fast Fourier Transform (FFT) analysis. The peak frequency that represents the quasi-periodic pulsation of the flow is increased with an increase in the axial velocity while the wavelength of the pulsation remains constant within a tested range of the Reynolds number (9000 51000). The vortex trains are highly synchronized with each other, as confirmed by means of visualization.

关键词： dual-cooled nuclear reactor vortex train flow pulsation turbulent mixing rod bundles