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Ef.ect of.Alloying Additions on the Oxidation of.High Speed Steels under Dry and Wet Conditions

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中国腐蚀与防护学报 2009年第4期29卷 241-247页

作者： f. C. RIZZO M. j. MONTEIRO S. R. j. SAUNDERS DCMM PUC Rio de Janeiro Brazil Bentley Surrey UK

An investigation has been carried out into the ef.ects of.chromium and vanadium content on the oxidation rate and on the adhesion of.oxide scales grown on three dif.erent chemical compositions of.high speed steels under dry and wet *** oxidation tests were carried out in a thermobalance at 650℃f.r up to 14.4 *** mass gain of.the specimens increased with increasing contents of.water vapour. Alloy composition had no ef.ect on the oxidation rate in dry ***'adhesion'of.the oxide scale was determined using indentation with a Rockwell C diamond and the pull adhesion test to determine the interf.cial toughness and the tensile strength of.the oxide metal bond,***,the results of.the investigation indicated that oxide adhesion was lowest f.r the specimens exposed to dry conditions, and that with increasing water vapour content,the scale was more *** test results showed that an increase in the V concentration was deleterious to oxide adhesion in both the dry and wet environments,whereas an increase in the Cr-content had little ef.ect on adhesion.

关键词：合金腐蚀氧化金属材料

Implementation of.a Roughness Element to Trip Transition in Large-eddy Simulation

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j.urnal of.Thermal Science 2015年第1期24卷 30-36页

作者： j.Boudet j.-f.Monier f.Gao LMf. Ecole Centrale de Lyon Université de Lyon–UMR CNRS 5509 69134 Ecully Cedex France PhD.Candidate Université de Lyon–UMR CNRS 5509 69134 Ecully Cedex France

In aerodynamics, the laminar or turbulent regime of.a boundary layer has a strong inf.uence on f.iction or heat transf.r. In practical applications, it is sometimes necessary to trip the transition to turbulent, and a common way is by use of.a roughness element （e.g. a step） on the wall. The present paper is concerned with the numerical im- plementation of.such a trip in large-eddy simulations. The study is carried out on a f.at-plate boundary layer con- f.guration, with Reynolds number Rex=l.3x 106. f.rst, this work brings the opportunity to introduce a practical methodology to assess convergence in large-eddy simulations. Second, concerning the trip implementation, a volume source term is proposed and is shown to yield a smoother and f.ster transition than a grid step. Moreover, it is easier to implement and more adaptable. f.nally, two subgrid-scale models are tested： the WALE model of.Nic0ud and Ducros （f.ow Turbul. Combust., vol. 62, 1999） and the shear-improved Smagorinsky model of.Ldv^que et al. （j. f.uid Mech., vol. 570, 2007）. Both models allow transition, but the f.rmer appears to yield a f.ster transition and a better prediction of.f.iction in the turbulent regime.

关键词： large-eddy simulation boundary layer roughness element transition tripping

Multimedia model of.atrazine in plant-soil-groundwater system with a f.gacity approach

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j.urnal of.Environmental Sciences 2001年第4期13卷 466-471页

作者： Ye, C.-m. Lei, Z.-f. Wang, X.-j. Gong, A.-j. Zheng, H.-h. Res. Cntr. Eco-Environmental Sci. Chinese Academy of Sciences Beijing 100085 China

The application of.atrazine in China during the last ten years has led to some environmental problems. In this paper, the multimedia model of.atrazine in soil-plant-groundwater system at Baiyangdian Lake area in Northern China was established using a f.gacity approach, and verif.ed with observed values. The model involved 7 environmental compartments which are air, groundwater, soil, corn roots, corn stem, corn leaf.and kernel of.corn. The results showed that the relative errors between calculated and observed values have a mean value of.24.7%, the highest value is 48% and the lowest value is 1.4%. All these values indicated that this multimedia model can be used to simulate the environmental f.te of.atrazine. Both the calculated and observed values of.concentrations of.atrazine in plant compartments are in the f.llowing order: in corn roots > in corn stem > in kernel of.corn > in corn leaf. it exhibited a good regularity. The prediction results indicated that concentrations of.atrazine in the groundwater and kernel of.corn will override the limitation of.3 μg/L and 0.05 mg/kg respectively.

关键词： Concentration (process) Error detection Groundwater Lakes Plants (botany) Soils

The integrated use of.chemical insecticides and the entomopathogenic nematode, Steinemema carpocapsae （Nematoda： Steinernematidae）, f.r the control of.sweetpotato whitef.y, Bemisia tabaci （Hemiptera： Aleyrodidae）

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Insect Science 2008年第5期15卷 447-453页

作者： Andrew G. S. Cuthbertson j.mes j. Mathers Phil Northing Anthony j. Prickett Keith f. A. Waiters Central Science Laboratory Sand Hutton York YO41 1LZ UK

The integration of.chemical insecticides and inf.ctive j.veniles of.the entomopathogenic nematode Steinernema carpocapsae （Wesier）（Nematoda： Steinernematidae）, to control second instars of.the sweetpotato whitef.y, Bemisia tabaci Gennadius （Hemiptera： Aleyrodidae） was investigated. Using a sand bioassay, the ef.ects of.direct exposure of.S. carpocapsae f.r 24 h to f.eld rate dilutions of.f.ur insecticides （spiromesif.n, thiacloprid, imidacloprid and pymetrozine） on inf.ctivity to Galleria mellonella larvae were tested. Although all chemicals tested, except spiromesif.n, produced acceptable nematode inf.ctivity rates, they were all signif.cantly less than the water control. The ef.ect of.insecticide treatment （dry residues of.spiromesif.n, thiacloprid and pymetrozine and soil drench of.imidacloprid） on the ef.icacy of.the nematode against B. tabaci was also investigated. Nematodes in combination with thiacloprid and spiromesif.n gave higher B. tabaci mortality （86.5% and 94.3% respectively） compared to using nematodes alone （75.2%） on tomato plants. There was no signif.cant dif.erence in B. tabaci mortality when using the chemicals imidacloprid, pymetrozine and spiromesif.n in conj.nction with nematodes compared to using the chemicals alone. However, using thiacloprid in combination with the nematodes produced signif.cantly higher B. tabaci mortality than using the chemical alone. The integration of.S. carpocapsae and these chemical agents into current integrated pest management programmes f.r the control of.B. tabaci is discussed.

关键词： entomopathogenic nematode inf.ctivity insecticide residue pest management

Diameter-dependent in vitro perf.rmance of.biodegradable pure zinc wires f.r suture application

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j.urnal of.Materials Science & Technology 2019年第8期35卷 1662-1670页

作者： H. Guo R.H. Cao Y.f. Zheng j. Bai f. Xue C.L. Chu State Key Laboratory f.r Turbulence and Complex System and Department of.Materials Science and Engineering College of Engineering Peking University Beijing 100871 China School of.Materials Science and Engineering Southeast University Nanjing 211189 China Key Laboratory f.r Advanced Metallic Materials Southeast University Nanjing 211189 China

In this study, biodegradable pure zinc wires with 3.0 mm and 0.3 mm in diameter were prepared via hot-extrusion and subsequent cold-drawing process respectively. The microstructure, mechanical perf.rmance, corrosion behavior, in vitro cytocompatibility and antibacterial ef.ect were comparatively *** cold-drawing, the mechanical property, especially the elongation of.the ф0.3 mm pure Zn wire was improved signif.cantly compared with the ф3.0 mm pure Zn wire. The in vitro corrosion study including immersion and electrochemical test showed acceptable corrosion resistance of.these two materials in Hank's solution. The in vitro Human Umbilical Vein Endothelial Cells(HUVECs) viability assay showed obviously dif.erent results, in which the ф0.3 mm pure Zn wire demonstrated f.vorable cytocompatibility, while the ф3.0 mm wire exhibited severe cytotoxic ef.ect with 100% extract concentration. Both of.them exhibited partly antibacterial ef.ect on S. aureus. These results demonstrated the f.asibility of.the prepared 0.3 mm pure Zn wire as the potential suture material with good absorbability.

关键词： Pure zinc Wire Biodegradable metal Suture

Towards an understanding of.Type Ia supernovae f.om a synthesis of.theory and observations

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f.ontiers of.physics 2013年第2期8卷 116-143页

作者： W. Hillebrandt M. Kromer f. K. Ropke A. j. Ruiter Max-Planck-Institut f.ir Astrophysik Karl-Schwarzschild-Str. 1 D-85741 Garching Germany Institut f.ir Theoretische Physik und Astrophysik Universit~it Wiirzburg Am Hubland D-97074 Wiirzburg Germany

Motivated by the f.ct that calibrated light curves of.Type Ia supernovae （SNe Ia） have become a maj.r tool to determine the expansion history of.the Universe, considerable attention has been given to, both, observations and models of.these events over the past 15 years. Here, we summarize new observational constraints, address recent progress in modeling Type Ia supernovae by means of.three-dimensional hydrodynamic simulations, and discuss several of.the still open questions. It will be be shown that the new models have considerable predictive power which allows us to study observable properties such as light curves and spectra without adj.stable non-physical parameters. This is a necessary requisite to improve our understanding of.the explosion mechanism and to settle the question of.the applicability of.SNe Ia as distance indicators f.r cosmology. We explore the capabilities of.the models by comparing them be applied to study the origin of.the diversity with observations and we show how such models can of.SNe Ia.

关键词： supernovae nucleosynthesis stellar evolution binary and multiple stars nuclearreactions

EXPERIMENTAL RESEARCH AND NUMERICAL SIMULATION Of.LASER SHOCK f.RMING Of.TA2 TITANIUM SHEET

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Acta Metallurgica Sinica(English Letters) 2006年第5期19卷 347-354页

作者： f. Wang Z. Q. Yao j. Hu Q.L. Deng School of.Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200030 China

Laser shock f.rming （ISf. was a new technique realized by applying an impulsive pressure generated by laser-induced shock wave on the surf.ce of.metal sheet. LSf.of.metal sheet was investigated with experiments and numerical simulation. The basic theories were introduced; the surf.ce quality and def.rmation of.the processed titanium sample （TA2） were examined; ABAQUS was used to simulate ISf.and the central displacement of.the shocked region was measured and compared with the simulation. Overlapped ISf.treatment was experimentally carried out to produce groove and simulation. The results showed that the surf.ce quality and the microstructure with single laser pulse had no remarkable change, and ablation was observed on the surf.ce of.the sample with overlapped pulses. The def.rmation observed in the numerical simulation agreeed with that observed in the experimental measurement quite well.

关键词： laser shock f.rming numerical simulation surf.ce quality def.rmation

Prevention of.gob ignitions and explosions in longwall mining using dynamic seals

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International j.urnal of.Mining Science and Technology 2017年第6期27卷 999-1003页

作者： Brune j.rgen f. Saki Saqib A. Department of.Mining Engineering Colorado School of Mines CO 80401 USA Aldea Services LLC Frederick MD 21704 USA

Most, if.not all longwall gob areas accumulate explosive methane-air mixtures that pose a deadly hazard to miners. Numerous mine explosions have originated f.om explosive gas zones(EGZs) in the longwall gob. Since 2010, researchers at the Colorado School of.Mines(CSM) have studied EGZ f.rmation in longwall gobs under two long-term research proj.cts f.nded by the National Institute f.r Occupational Saf.ty and Health. Researchers used computational f.uid dynamics along with in-mine measurements. f.r the f.rst time, they demonstrated that EGZs f.rm along the f.inge areas between the methane-rich atmospheres and the f.esh air ventilated areas along the working f.ce and present an explosion and f.re hazard to mine workers. In this study, researchers f.und that, f.r progressively sealed gobs, a targeted inj.ction of.nitrogen f.om the headgate and tailgate, along with a back return ventilation arrangement, will create a dynamic seal of.nitrogen that ef.ectively separates the methane zone f.om the f.ce air and eliminates the EGZs to prevent explosions. Using this f.rm of.nitrogen inj.ction to create dynamic seals should be a consideration f.r all longwall operators.

关键词： Mine explosions f.ce ignitions Coal mining Longwall mining Methane

The role of.latitudinal, genetic and temperature variation in the induction of.diapause of.Papilio glaucus （Lepidoptera： Papilionidae）

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Insect Science 2018年第2期25卷 328-336页

作者： Sean f. Ryan Patti Valella Gabrielle Thivierge Matthew L. Aardema j. Mark Scriber Department of.Biological Sciences University of Notre Dame Notre Dame Indiana USA USDA-ARS Center f.r Medical Agricultural and Veterinary Entomology 1600/1700 Southwest 23rd Drive Gainesville Florida USA Department of.Entomology Michigan State University East Lansing Michigan USA Lif. Science Department Long Beach City College Long Beach California USA Sackler Institute f.r Comparative Genomics American Museum of Natural History New York New York USA McGuire Centerf.r Lepidoptera and Diversity University of Florida Gainesville Florida US

A key adaptation in insects f.r dealing with variable environmental conditions is the ability to diapause. The tiger swallowtail butterf.ies, Papilio glaucus and P. canadensis are ideal species to explore the genetic causes and population genetic consequences of.diapause because divergence in this trait is believed to be a salient f.ctor in maintaining a hybrid zone between these species. Yet little is known about the f.ctors that inf.uence diapause induction in this system. Here we explored how spatial （latitudinal）, environmental （temperature） and genetic （hybridization） f.ctors af.ect diapause induction in this system. Specif.cally, a series of.growth chamber experiments using wild caught individuals f.om across the eastern United States were perf.rmed to：（1） evaluate how critical photoperiod varies with latitude, （2） isolate the stage in which induction occurs, （3） test whether changes in temperature af.ected rates of.diapause induction, and （4） explore how the incidence of.diapause is af.ected in hybrid of.spring. We f.nd that induction occurs in the larval stage, is not sensitive to a relatively broad range of.temperatures, appears to have a complex genetic basis （i.e., is not simply a dominant trait f.llowing a Mendelian inheritance pattern） and that the critical photoperiod increases by 0.4 h with each increasing degree in latitude. This work deepens our understanding of.how spatial, environmental and genetic variation inf.uences a key seasonal adaptation （diapause induction） in a well-developed ecological model system and will make possible f.ture studies that explore how climatic variation af.ects the population dynamics and genetics of.this system.

关键词： adaptation critical photoperiod development diapauses f.cultative hybridization