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Simulation of buoyancy-induced turbulent flow from a hot horizontal jet

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Journal of Hydrodynamics 2014年第1期26卷 104-113页

作者： El-AMIN M.f. SUN Shuyu SAlAM Amgad Computational Transport Phenomena laboratory (CTPl) Division of Physical Sciences and EngineeringKing Abdullah University of Science and Technology

Experimental visualizations and numerical simulations of a horizontal hot water jet entering cold water into a rectangular storage tank are described. Three different temperature differences and their corresponding Reynolds numbers are considered. Both experimental visualization and numerical computations are carried out for the same flow and thermal conditions. The realizable k-e model is used for modeling the turbulent flow while the buoyancy is modeled using the Boussinesq approximation. Polynomial approximations of the water properties are used to compare with the Boussinesq approximation. Numerical solutions are obtained for unsteady flow while pressure, velocity, temperature and turbulence distributions inside the water tank as well as the froude number are analyzed. The experimental visualizations are performed at intervals of five seconds for all different cases. The simulated results are compared with the visualized results, and both of them show the stratification phenomena and buoyancy force effects due to temperature difference and density variation. After certain times, depending on the case condition, the flow tends to reach a steady state.

关键词： turbulent flow realizablc k - e turbulence model heat transfer jet heat storage

Evaluation of stress concentration for planar tubular joints

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中国有色金属学会会刊：英文版 2006年第B01期16卷 1-10页

作者： M.f.GHANAMEH D.THE VENET A.ZEGHlOUl laboratory of Mechanics and Physics of Materials - U.M.R.CNRS N° 7554 University of MetzLPMM57045 MetzFrance laboratory of Mechanics of Naval Structures ENSIETA29806 BrestFrance Received 10 April 2006 accepted 25 April 2006

In offshore tubular structures, a typical tubular joint may be subjected to three different types of basic loadings: axial, in-plane bending and out-of-plane bending, through its brace members. Each type will cause a different stress distribution at the joint intersection of structures. Moreover, the actual load condition of a tubular joint can be any combination of the above three basic load cases, for this reason, a combined loading was investigated in addition to these three basic loadings. This load is composed of an axial loading combined with a continuation of rotational bending loading obtained while rotate center of the brace around a circle. Different types of planar joints such as T, Y, X, K, DT, DY, DX, TY, TK, DTX, DTDY, and DTDK, with braces subjected to combined loading, were numerically analyzed to study the effect of those different cases of loading and different types of joints, on the stress concentration zone and values.

关键词：管子接头焊接应力集中评价应力分布有限元法海洋平台

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为生坯加工用强化生坯强度的润滑系统的开发

粉末冶金技术 2003年第5期21卷 270-277页

作者： l.Tremblay J.E.Danaher f.Chagnon Y.Thomas 韩凤麟魁北克金属粉末公司加拿大国家研究委员会工业材料研究所

粉末冶金零件烧结后往往面要切削加工 ,以达到压制时无法成形的设计特征或窄小的尺寸公差。可是 ,随着高性能材料出现 ,鉴于这些材料烧结后表观硬度与强度高 ,采用生坯切削加工可减低切削加工费用与增强竞争性 ,因此 ,是一种很有吸引力... 详细信息

粉末冶金零件烧结后往往面要切削加工 ,以达到压制时无法成形的设计特征或窄小的尺寸公差。可是 ,随着高性能材料出现 ,鉴于这些材料烧结后表观硬度与强度高 ,采用生坯切削加工可减低切削加工费用与增强竞争性 ,因此 ,是一种很有吸引力的生产工艺。现在 ,采用新润滑系统可使零件在烧结前进行切削加工 ,这些新润滑系统和常用润滑剂相比 ,都是一些能大大增高零件生坯强度的聚合物润滑剂。在切削加工时 ,较高的生坯强度可减低生坯开裂和 /或棱边剥落的危险这篇论文对由新聚合物润滑系统或常用EBS蜡润滑剂压制的烧结硬化材料flC - 4 6 0 8的脱模特性与生坯特性进行了比较。这种比较是用实验室与生产规模压机压制成形的密度为 6 7～ 7 1g/cm3 的横向断裂试样和油泵齿轮进行的。还报告了油泵齿轮烧结后的性能和零件间性能的均一性。

关键词：粉末冶金切削加工润滑系统烧结聚合物润滑剂生坯强度

Stroke care in the ChatGPT era:Potential use in early symptom recognition

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Journal of Acute Disease 2023年第3期12卷 129-130,I0001,I0002页

作者： Wai Yan lam Sunny chi lik Au Department Ophthalmology Grantham HospitalHong KongChina Department Ophthalmology Tung Wah Eastern HospitalHong KongChina

Dear editor,Generative Pre-trained Transformer-based Chatbot(ChatGPT)[1]or similar natural language processing[2]and large language models[3]are artificial intelligence systems designed to understand and respond to human languages,allowing them to provide information,answer questions,and provide guidance on a wide range of *** of their key benefits is immediate access to information in a conversational format,as if a hotline call,which is essential in acute medical ***,medical utilization of ChatGPT is a hot research *** its intrinsic difference from search engines,ChatGPT has the potential to revolutionize our mode of information access.

关键词： conversational editor Chat

Plasmonic enhancement and polarization dependence of nonlinear upconversion emissions from single gold nanorod@SiO_(2)@Caf2:Yb^(3+),Er^(3+)hybrid core–shell–satellite nanostructures

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light(Science & Applications) 2016年第1期5卷 224-234页

作者： Jijun He Wei Zheng filip ligmajer chi-fai Chan Zhiyong Bao Ka-leung Wong Xueyuan Chen Jianhua Hao Jiyan Dai Siu-fung Yu Dang Yuan lei Department of Applied Physics The Hong Kong Polytechnic UniversityHong KongChina Key laboratory of Optoelectronic Materials Chemistry and Physics Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian 350002China Central European Institute of Technology Brno University of TechnologyBrno 61669Czech Republic Department of Chemistry Hong Kong Baptist UniversityHong KongChina

lanthanide-doped upconversion nanocrystals(UCNCs)have recently become an attractive nonlinear fluorescence material for use in bioimaging because of their tunable spectral characteristics and exceptional *** materials are often introduced into the vicinity of UCNCs to increase their emission intensity by means of enlarging the absorption cross-section and accelerating the radiative decay ***,plasmonic nanostructures(e.g.,gold nanorods,GNRs)can also influence the polarization state of the UC fluorescence—an effect that is of fundamental importance for fluorescence polarization-based imaging methods yet has not been discussed *** study this effect,we synthesized GNR@SiO_(2)@Caf2:Yb^(3+),Er^(3+)hybrid core–shell–satellite nanostructures with precise control over the thickness of the SiO_(2) *** evaluated the shell thicknessdependent plasmonic enhancement of the emission intensity in ensemble and studied the plasmonic modulation of the emission polarization at the single-particle *** hybrid plasmonic UC nanostructures with an optimal shell thickness exhibit an improved bioimaging performance compared with bare UCNCs,and we observed a polarized nature of the light at both UC emission bands,which stems from the relationship between the excitation polarization and GNR *** used electrodynamic simulations combined with förster resonance energy transfer theory to fully explain the observed *** results provide extensive insights into how the coherent interaction between the emission dipoles of UCNCs and the plasmonic dipoles of the GNR determines the emission polarization state in various situations and thus open the way to the accurate control of the UC emission anisotropy for a wide range of bioimaging and biosensing applications.

关键词： förster resonance energy transfer gold nanorods lanthanide-doped upconversion nanocrystals plasmon-enhanced nonlinear fluorescence polarization modulation

Design, Sonosynthesis, Quantum-Chemical Calculations, and Evaluation of New Mono-and Bis-pyridine Dicarbonitriles as Antiproliferative Agents

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chinese Journal of Chemistry 2020年第5期38卷 501-508页

作者： Wael Abdelgayd Ahmed Arafa Modather f.Hussein Chemistry Department College of ScienceJouf UniversityP.O.Box 2014SakakaAljoufKingdom of Saudi Arabia Chemistry Department Faculty of ScienceFayoum UniversityP.O.Box 63514Fayoum CityEgypt Chemistry Department Faculty of ScienceAl-Azhar UniversityAsyut branchEgypt

A highly efficient,simple,and clean single-step sonosynthetic procedure has been sophisticated for assembling new series of mono-and bis-pyridine dicarbonitriles from ketones,HCl,and *** presented protocol is applicable for the preparation of a broad range of uniquely substituted pyridine dicarbonitriles and seems to be superior in comparison with other previously reported *** antiproliferative impact of the newly synthesized derivatives was screened towards three representative cancer cell lines(MCf-7,A549,and HCT116).Most of the evaluated derivatives showed a moderate to excellent anti-proliferative activity towards the selected cell *** these,compounds 4h,4k,10,12a,and 12b showed both potent anticancer activity(ICs0lower cytotoxic effect(ICs0>58μM)on non-tumorigenic cells(MCf-10A and NCM460),suggesting their promising potential to be lead molecules for future antitumor drug *** structure-activity relationships have been also ***,quantum chemical studies based on Density functional Theory(DfT)of the synthesized compounds were investigated and found to be consistent with the in vitro inhibitory activities.

关键词： pyridine nitrile synthesis

Calculation of the VKI turbine blade with lES and DES

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Journal of Thermal Science 2007年第4期16卷 321-327页

作者： f.Magagnato B.Pritz M.Gabi fSM University of KarlsruheGermany

The prediction of the laminar to turbulent transition is essential in the calculation of turbine blades, compressor blades or airfoils of airplanes since a non negligible part of the flow field is laminar or transitional. In this paper we compare the prediction capability of the Detached Eddy Simulation （DES） with the large Eddy Simulation （lES） using the high-pass filtered （HPf） Smagorinsky model （Stolz et al.[1]） when applied to the calculation of transitional flows on turbine blades. Detailed measurements from Canepa et al.[2] of the well known VKI-turbine blade served to compare our results with the experiments. The calculations have been made on a fraction of the blade （10%） using non-reflective boundary conditions of freund at the inlet and outlet plane extended to internal flows by Magagnato et al.[3] in combination with the Synthetic Eddy Method （SEM） proposed by Jarrin et al.[4]. The SEM has also been extended by Pritz et al.[5] for compressible flows. It has been repeatedly shown that hybrid approaches can satisfactorily predict flows of engineering relevance. In this work we wanted to investigate if they can also be used successfully in this difficult test case.

关键词： Turbine blade lES DES transition

Precise integration methods based on the Chebyshev polynomial of the first kind

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Earthquake Engineering and Engineering Vibration 2008年第2期7卷 207-216页

作者： Wang Mengfu f. T. K. Au Department of Civil Engineering Hunan University Changsha 410082 China Department of Civil Engineering The University of Hong Kong China

This paper introduces two new types of precise integration methods based on Chebyshev polynomial of the first kind for dynamic response analysis of structures, namely the integral formula method （IfM） and the homogenized initial system method （HISM）. In both methods, nonlinear variable loadings within time intervals are simulated using Chebyshev polynomials of the first kind before a direct integration is performed. Developed on the basis of the integral formula, the recurrence relationship of the integral computation suggested in this paper is combined with the Crout decomposed method to solve linear algebraic equations. In this way, the IfM based on Chebyshev polynomial of the first kind is constructed. Transforming the non-homogenous initial system to the homogeneous dynamic system, and developing a special scheme without dimensional expansion, the HISM based on Chebyshev polynomial of the first kind is able to avoid the matrix inversion operation. The accuracy of the time integration schemes is examined and compared with other commonly used schemes, and it is shown that a greater accuracy as well as less time consuming can be achieved. Two numerical examples are presented to demonstrate the applicability of these new methods.

关键词： structural dynamics Chebyshev polynomial of the first kind the Crout decomposed method integral formula method homogenized initial system method

Photoproduction of J/ψ in non-single-diffractive p+p collisions

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chinese Physics C 2019年第6期43卷 38-44页

作者： Ze-Hua Cao li-Juan Ruan Ze-Bo Tang Zhang-Bu Xu chi Yang Shuai Yang Wang-Mei Zha State Key laboratory of Particle Detection and Electronics University of Science and Technology of China. Hefei 230026 China Department of Modem Physics University of Science and Technology of China Hefei 230026 China Brookhaven National laboratory New York USA Shandong University Jinan 250100 China

Significant enhancements of J/ψ production at very low transverse momenta were recently observed by the AlICE and STAR collaborations in peripheral hadronic A+A collisions. The anomalous excess points to coherent photon-nucleus interactions in violent hadronic heavy-ion collisions, which were conventionally studied only in ultra-peripheral collisions. Assuming that the coherent photoproduction is the underlying mechanism responsible for the excess observed in peripheral A+A collisions, its contribution in p+p collisions with nuclear overlap, i.e. nonsingle-diffractive collisions, is of particular interest. In this paper, we perform a calculation of exclusive J/ψ photoproduction in non-single-diffractive p+p collisions at the RHIC and lHC energies based on the pQCD motivated parametrization using the world-wide experimental data, which could be further employed to improve the precision of the phenomenological calculations for photoproduction in A+A collisions. The differential rapidity and transverse momentum distributions of J/ψ from photoproduction are presented. In comparison with the J/ψ production from hadronic interactions, we find that the contribution of photoproduction is negligible.

关键词： photoproduction jpsi RHIC lHC