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Study of Transition from Laminar to Turbulent Boundary Layer on a Tilted flat Plate Using Heat Transfer Measurements

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Journal of Thermal Science 2007年第2期16卷 186-191页

作者： E.Sanz c.Nicot R.Point f.Plaza Laboratoire de Mécanique des fluides et Acoustique LMFA(ECL-UCB-INSA Lyon-CNRS)36Avenue Guy de Collongue69134 Ecully.France.

The boundary layer transition over a flat tilted plate has been studied by means of heat transfer measurements. A heat flux sensor has been developed, in order to measure the efficiency of convective heat transfer for various types of surfaces or flows. Its operation at constant temperature allows direct and fast measurements of heat flux. The present paper reports the development of the sensor and presents its application to the study of transition in a boundary layer depending on the angle of incidence of the external flow. An exponential relationship between critical Reynolds number and pressure gradient parameter has been found.

关键词： convective heat flux boundary layer transition pressure gradient.

Modelling of internal ballistics of gun systems:A review

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Defence Technology（防务技术） 2024年第11期41卷 35-58页

作者： f.Ongaro c.Robbe A.Papy B.Stirbu A.chabotier Royal Military Academy Avenue de la Renaissance 30Bruxelles 1000Belgium

A deep understanding of the internal ballistic process and the factors affecting it is of primary importance to efficiently design a gun system and ensure its safe management. One of the main goals of internal ballistics is to estimate the gas pressure into the combustion chamber and the projectile muzzle velocity in order to use the propellant to its higher efficiency while avoiding over-pressure phenomena. Dealing with the internal ballistic problem is a complex undertaking since it requires handling the interaction between different constituents during a transient time lapse with very steep rise of pressure and temperature. Several approaches have been proposed in the literature, based on different assumptions and techniques. Generally, depending on the used mathematical framework, they can be classified into two categories: computational fluid dynamics-based models and lumped-parameter ones. By focusing on gun systems, this paper offers a review of the main contributions in the field by mentioning their advantages and drawbacks. An insight into the limitations of the currently available modelling strategies is provided,as well as some considerations on the choice of one model over another. Lumped-parameter models, for example, are a good candidate for performing parametric analysis and optimisation processes of gun systems, given their minimum requirements of computer resources. conversely, cfD-based models have a better capacity to address more sophisticated phenomena like pressure waves and turbulent flow effects. The performed review also reveals that too little attention has been given to small calibre guns since the majority of currently available models are conceived for medium and large calibre gun ***, aspects like wear phenomena, bore deformations or projectile-barrel interactions still need to be adequately addressed and our suggestion is to dedicate more effort on it.

关键词： Internal ballistics Numerical modelling Lumped-parameter model computational fluid dynamics Gun systems

New photo-thermal-synthesized polymer for self-compacting concrete to increase productivity, minimize pollution, and eliminate steam curing in precast concrete

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Journal of Harbin Institute of Technology(New Series) 2006年第5期13卷 518-524页

作者： f. c. Lai M. f. Mohd Zain 王宝民 K. c. Lee Dept. of civil and Structural Engineering Faculty of Engineering Universiti Kebangsaan Malaysia 43600 U.K.M Bangi Selangor Darul Ehsan Malaysia Dept. of civil Engineering Dalian University of Technology Dalian 116024 China Sime Darby Technology Petaling Jaya Kuala Lumpur Malaysia

The objective in this study is to apply the sustainable chemistry and photo-thermal synthesis technology to produce the sustainable eco-superplasticiser for the sustainable high performance Scc concrete especially in hot tropical countries. A photo-thermal synthesized eco-superplasticiser （PSES） was produced by using photo-thermal catalyst in a solar chemical reactor. In this preliminary study, an unique high early strength of Scc concrete has been successfully produced by imposing an unique proportion of the photo-thermal-synthesized eco- Superplasticiser （PSES）, local fly ash, sand and aggregate. The Scc concrete is preliminary tried in the precast concrete product to produce the complicated geometries as Tunnel segment, U-shape beam, and Box girder which have the critical reinforcement and thin section concrete. Surprisingly, this Scc provide the benefits as eliminating steaming energy, increased productivity, and minimize pollution. These unique properties of sustainable Scc concrete can not be achieved by the convention concrete by using ligno, naphthalene and melamine base superplasficiser. The synthesized sustainable eco-superplasticiser is a perfect choice to fully utilized the renewable energy and improve the concrete working environment.

关键词： photo-chemical synthesis sustainable self-compacting concrete eco-superplasticiser eliminate steaming renewable solar energy

Thermal manipulation of plasmons in atomically thin films

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Light(Science & Applications) 2020年第1期9卷 1179-1189页

作者： Eduardo J.c.Dias Renwen Yu f.Javier Garcia de Abajo IcfO-Institut de ciencies fotoniques The Barcelona Institute of Science and Technology08860 Castelldefels(Barcelona)Spain IcREA-Institucio catalana de Recerca i Estudis Avançats Passeig Lluis Companys 2308010 BarcelonaSpain

Nanoscale photothermal effects enable important applications in cancer therapy,imaging and *** effects also induce substantial changes in the optical response experienced by the probing light,thus suggesting their application in all-optical ***,we demonstrate the ability of graphene,thin metal films,and graphene/metal hybrid systems to undergo photothermal optical modulation with depths as large as>70%over a wide spectral range extending from the visible to the terahertz frequency *** envision the use of ultrafast pump laser pulses to raise the electron temperature of graphene during a picosecond timescale in which its mid-infrared plasmon resonances undergo dramatic shifts and broadenings,while visible and near-infrared plasmons in the neighboring metal films are severely attenuated by the presence of hot graphene *** study opens a promising avenue toward the active photothermal manipulation of the optical response in atomically thin materials with potential applications in ultrafast light modulation.

关键词： pump visible films

Building a Novel future: connecting Peoples and cultures

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Social Sciences in china 2022年第1期43卷 194-208页

作者： Augustin f.c.Holl School of Sociology and Anthropology Xiamen University

current humanity is experiencing extraordinary levels of material and ideal *** being constant and stability exceptional and provisional;one has to expect a significant acceleration of change in the next hundred *** core question is therefore:What kind of future is being shaped for the next generations,our grandchildren and great-grand children?Without going too far back in time,it is fair to say that the current world was shaped by two different,successive and antinomic global processes:imperial expansion,colonization and domination on the one hand,and resistance,struggle for liberation,and the search for a more equitable world order on the other *** all the odds,European imperialism,civil war,wars of aggression,and Western ostracism,china was an influential actor in the struggle for liberation of Africa from colonialism,got its rightful place in the international world order and is now the second economy of the *** resulted in the emergence of a de facto multipolar world,with different models of societies and organizational *** are dialectic processes constantly in operation,but there is however a third crucial area of interest,generally taken granted,that of people and *** relations and sustainable economic development backed by greater cultural and demographic connectivity are better options for the construction of a novel future for *** and higher education institutions can play an important role in spearheading and implementing these new orientations for the construction of a future peaceful and sustainable human world in which war will be *** paper outlines what academics can do to promote such a vision.

关键词： Africa china social sciences alternative partnership connectivity people cultures sustainable future

Experimental Podophyllotoxin (Bajiaolian) Poisoning:——Ⅰ. Effects on the Nervous System

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Biomedical and Environmental Sciences 1992年第4期5卷 283-292页

作者： LOUIS W.cHANG c.M.YANG c.f.cHEN J.f.DENG Departments of Pathology Pharmacology and Toxicology University of Arkansas for Medical Sciences Little RockThe Chang-Gung Medical College Kwai-sanNational Research Institute of Chinese MedicineThe Veteran General Hospital AR 72205TaipeiTaipeiTaipei Taiwan China

Bajiaolian, one of the species in the Mayapple family ( Podophyllum pelatum ), has been widely used as a traditional chinese herbal medicine for the remedies of snake bites, general weakness, poisons, condyloma accuminata, lymphadenopathy, and certain tumors in china. In Western medicine, Podophyllum was first used medically as a laxative in the early 19th century. Since 1940, the resin of podophyllum has also been used topically for various skin lesions, such as warts and condyloma. Human poisonings have been reported.An animal model was established to investigate the neurotoxic effects of Bajiaolian. Podophyllotoxin, the major active ingredient in Podophyllum, was injected (ip) to young adult male rats at doses of 0, 5, 10, or 15 mg-kg-1 b.w.. The animals were sacrificed 72 h after injection.Neuronal changes were readily observable in animals treated with 10 or 15 mg-kg-1 of the toxin. Edematous changes of the anterior horn motoneurons were observed in the spinal cord. No neuronal necrosis was found. The type of neuronal swelling is believed to be only a transient change and would probably subside with time if no further assaults occur. More serious and perhaps longer term of changes were found in the dorsal ganglion neurons and the nerve fibers (axons) in the central and peripheral nervous system. Severe depletion of the Nissl substance (RNA/polyribosomes) was observed in the dorsal root ganglion neurons. Alterations in these sensory neurons would give rise to and correlate with the sensory disturbances experienced by the patients. Bodian staining also revealed a dose-related increase in the coarseness (thickness) of the nerve fibers (axons) in the cerebellum, cerebral cortex, brainstem, and spinal cord.This is the first scientific study showing the neurotoxicity of Bajiaolian, a commonly used chinese herbal medicine. Toxicities on other organ systems by this drug certainly exist. caution should be exercised in the dispensing and usa

关键词： Bajiaolian Effects on the Nervous System Experimental Podophyllotoxin Poisoning

Effect of ce-base mischmetal addition on the microstructure and mechanical properties of hot-rolled ZK60 alloy

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Journal of Magnesium and Alloys 2021年第3期9卷 995-1006页

作者： E.P.Silva R.H.Buzolin f.Marques f.Soldera U.Alfaro H.c.Pinto Institute of Engineering Science and Technology(IECT)Federal University of Vales do Jequitinhonha e Mucuri(UFVJM)JanaúbaMGBrazil São carlos School of Engineering(EESc) University of São Paulo(USP)Department of Materials EngineeringCEP 13563-120 São Carlos-SPBrazil christian Doppler Laboratory for Design of high-performance alloys by thermomechanical processing Kopernikusgasse 24/I8010 GrazAustria Technische Universität Graz(TU Graz) Institute of Materials ScienceJoining and FormingKopernikusgasse 24/I8010 GrazAustria Institute of functional Materials Department of Materials Science and EngineeringSaarland UniversitySaarbrueckenGermany German Aerospace center(DLR)Institute of Materials Research Linder Höhe51147 CologneGermany

Mg-Zn-Zr(ZK)alloys exhibit notably high mechanical strength amongst all magnesium alloy ***,due to the formation of low melting point Mg_3Zn_7-precipitates,these alloys are susceptible to hot cracking,thus compromising their metallurgical *** addition of rare earths to ZK alloys is an alternative to form higher melting point intermetallic compounds,speed up dynamic recrystallization,refine grain size,enhance corrosion resistance and extend the service temperature due to improved creep *** work deals with the effect of ce-base mischmetal addition on the hot rolling behaviour of as-cast ZK60 *** microstructure investigation conducted using electron microscopy and X-Ray diffraction shows that precipitation of Mg_(7)Zn_(3) intermetallics occur during hot rolling,whereas no further precipitation is observed for the ZK60-Mm *** fragmentation of the intermetallic compounds occur during hot rolling and finer particles of Mg_(7)Zn_(3) are observed for the ZK60,whereas Mg_(7)Zn_(3) and Mg Zn_(2) ce intermetallics are formed in the alloy modified with mischmetal addition.A higher fraction of dynamically recrystallized grains is observed for the ZK60-Mm in comparison to the *** recrystallization takes place in ZK60 with the formation of sub-grains near to the intermetallics and the addition of mischmetal promotes the occurrence of discontinuous recrystallization with the nucleation of new grains close to the *** mechanical strength and,in particular,the ductility of the hot-rolled alloys are notably improved when compared to the same alloys in the as-cast *** mechanical strength is,however,higher for the ZK60 *** solid solution strengthening,softer Mg Zn_(2) ce intermetallics and more extensive recrystallization contribute to reduce the mechanical strength of *** in both alloys are initiated at coarse intermetallics and propagate through intermetallic-rich regions.

关键词： Magnesium alloys Hot rolling Mischmetal Recrystallization Microstructure Mechanical properties

Effect of natural organic matter on thallium and silver speciation

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Journal of Environmental Sciences 2020年第7期32卷 185-192页

作者： Loïc A.Martin caroline Simonucci Sétareh Rad Marc f.Benedetti Universitéde Paris Institut de physique du globe de ParisCNRSF-75005 ParisFrance IRSN PSE-ENV/SIRSE/LER-NordBP 1792262 Fontenay-aux-Roses CedexFrance catchment and Eco-Hydrology Research Group Luxembourg Institute of Science and TechnologyL-4422 BelvauxLuxembourg BRGM Unitéde Géomicrobiologie et Monitoring Environnemental45060 Orléans Cedex 2France

Natural organic matter(NOM)is known to play an important role in the transport and binding of trace metal elements in aquatic and soil *** is a pollutant for which the extent of the role played by NOM is poorly ***,this study investigates thallium(Ⅰ)and its complexation to a purified humic substance as proxy for *** were performed with the Donnan Membrane Technique to separate,for the first time,the free Tl^+ion from its complexed form in the bulk *** pH and concentrations were investigated at constant ionic strength and constant NOM proxy concentrations in *** results were described with NIcA-Donnan *** complexation was compared to silver complexation using literature data and using the same NIcA-Donnan *** for these two cations(Tl^+and Ag^+)are reported in this article,for the first *** display low thallium complexation to the NOM proxy while silver competes with divalent cations for the NOM binding *** speciation for dissolved thallium highlights the dominance of free thallium(Tl^+)in solution whereas Tl-NOM complexes contribute roughly 15%to total Tl(Ⅰ)species in river and lake type *** results are obtained for soil solutions,Tl-bound to NOMf total,from UK soils with different land use and geochemistry.

关键词： Thallium Organic matter Speciation NIcA-Donnan model Soil Water

The imaging and dissecting of pBR322 plasmid DNA by AfM

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chinese Science Bulletin 1997年第13期42卷 1093-1096页

作者： Tian, f Li, JW Wang, c Bai, cL Institute of chemistry Chinese Academy of Sciences Beijing 100080 China

THE intra- and intermolecular forces of DNA are essential to understanding its structure andfunctional behavior. However, direct measurement of interaction forces requires that the stateof a system be monitored simultaneously while an independent force is applied. Until now, on-ly X-ray crystallography, light scattering, and nuclear magnetic resonance spectroscopy havebeen used to measure these molecular forces using indirect physical and thermodynamic meth-

关键词： atomic force microscope plasmid DNA probe force.