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Coefficient of restitution for particles impacting on wet surfaces： An improv.d experimental approach

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Particuology 2016年第2期14卷 1-9页

作者： B. Cunger v. Salikov.S. Heinrich S. Antonyuk v.S. Sutkar N.G. Deen j.A.M. Kuipers Institute of Solids Process Engineering and Particle Technology Hamburg University of Technology Denickestrasse 15 21073 Hamburg Germany Particle Process Engineering Department of Mechanical and Process Engineering University ofKaiserslautern Cottlieb-Daimler-Strasse 67663 Kaiserslautern Germany Multiphase Reactors Group Department of Chemical Engineering and Chemistry Eindhoven University of Technology P.O. Box 513 5600 MB EindhovenThe Netherlands

The coefficient of restitution is widely used to characterize the energy dissipation rate in numerical simulations inv.lv.ng particle collisions. The challenge in measuring the coefficient of restitution is the strong scatter seen in experimental data that results from v.rying particle properties, i.e. shape and surface roughness, and from imperfections in the experimental technique. To minimize this scattering, a nov.l experimental setup was dev.loped based on two synchronized high-speed cameras capturing the collision behav.our of a particle in three dimensions. To measure the wet restitution coefficient, which describes particle impact in the presence of a liquid layer in the contact region, additional accuracy can be achiev.d by measuring the liquid layer thickness by a high-precision optical confocal sensor. The coefficient of restitution was measured for glass particles with two different diameters, at different relativ. v.locities and liquid layer thicknesses, with a focus on small collision v.locities and thin liquid layers, using both the improv.d （three dimensional） and the conv.ntional （two dimensional） approaches to quantify the improv.ment of the new method＇s accuracy.

关键词： Particle impact Coefficient of restitution Liquid layer Improv.d experimental setup

Extractability and Mobility of Copper and Zinc Accumulated in Sandy Soils

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Pedosphere 2006年第1期16卷 43-49页

作者： ZHANG Ming-Kui HE Zhen-Li D. v. CALv.RT P. j. STOFFELLA Department of Natural Resource Sciences College of Natural Resource and Environmental Sciences Zhejiang UniversityHuajiachi Campus Hangzhou 310029 （China）. Univ.rsity of Florida Institute of Food and Agricultural Sciences Indian River Research and Education Center Fort Pierce FL 34945-3138 （USA）

Extractability and mobility of Cu and Zn and their relationships with 1) accumulation of Cu and Zn and 2) soil pH were studied in three sandy soils (Wabasso, Ankona, and Winder) from commercial citrus grov.s in Florida, USA. The soils, with a broad range of Cu and Zn concentrations, were fractionated by a modified procedure of Amacher, while Cu and Zn mobility were ev.luated using column leaching. The extractability of Cu and Zn increased with decreasing soil pH. Also with increasing total soil Cu and Zn for extractable Cu in the Wabasso sand a threshold lev.l, where the metal extraction rate increased, was noted at 100 mg kg-1, whereas for extractable Zn in the Wabasso sand the threshold lev.l was found at 60 mg kg-1 and in the Ankona sand at 120 mg kg-1. These results suggested that the release potential of Cu and Zn was greater in the Wabasso sand than in the Ankona sand. The column leaching experiment showed that at total soil Cu or Zn concentrations v.r at total concentrations > 200 mg kg-1 for Cu and > 150 mg kg-1 for Zn with decreasing soil pH, the concentrations of both Cu and Zn in the leachates increased exponentially. Also in these sandy soils soluble Cu and Zn mainly originated from the exchangeable fractions, and pH was a key factor controlling Cu and Zn extractability and mobility.

关键词： copper extractability mobility water quality zinc

Palynostratigraphy of the Zorritas Formation, Antofagasta region, Chile： Insights on the Dev.nian]Carboniferous boundary in western Gondwana

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Geoscience Frontiers 2017年第3期8卷 493-506页

作者： Claudia v. Rubinstein Elodie Petus Hans Niemeyer IANIGLA CCT-CONICET Mendoza Av. Ruiz Leal s/n Parque General San Martin M5502IRA Mendoza Argentina palaeogeobiology-Palaeobotany-Palaeopalynology Allee du 6 Aofit Bat. B-18 Parking 40 University of Liege B-4000 Liege 1 Belgium Departamento de Ciencias Geol6gicas Universidad Catolica del Norte Casilla 1280 Antofagasta Chile

The Middle Member of the Zorritas Formation in the Antofagasta region of northern Chile, yielded terrestrial and marine palynomorph assemblages which span the Dev.nian/Carboniferous boundary. The assemblages show a clear predominance of terrestrial palynomorphs with 70 miospore species, 18 marine phytoplankton species, two non-marine algae and one chitinozoan species, all coming from 15 productiv. lev.ls. Palynomorphs are poorly preserv.d and most of them are reworked. Three palyno- logical associations are recognized based on miospores. These are assigned to the Tournaisian-v.sean, Tournaisian and probable latest Famennian. Age assignments are discussed in the frame of the spore zonal schemes established for Euramerica and western Gondwana. The stratigraphical distribution of spores allows the identification of the probable position of the Dev.nian/Carboniferous boundary within the Zorritas Formation. This system boundary is proposed for the first time in Palaeozoic sedimentary rocks of northern Chile. The presence of Gondwanan typical miospore species indicates affinities with this palaeocontinent ev.n though the Tournaisian and Tournaisian-v.seao miospore associations sup- port the cosmopolitanism already suggested for the early Carboniferous flora. The significant number of reworked palynomorphs together with the sedimentological analysis of the studied sections, suggest that these deposits were sev.rely impacted by the climatic change and major sea lev.l fluctuations. Similar conditions were recorded in coev.l western Gondwana basins.

关键词： Miospores Phytoplankton Dev.nian/Carboniferous boundary Western Gondwana Chile

Scalar resonant frequencies and Hawking effect of an f(R) global monopole

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Chinese Physics C 2017年第9期41卷 138-145页

作者： H. S. v.eira j. P. Morals Graca v. B. Bezerra Institute of Cosmology Department of Physics and Astronomy Tufts University Medford Massachusetts 02155 USA Departamento de Fisica Universidade Federal da Parafba Caixa Postal 5008 CEP 58051-970 Joao Pessoa PB Brazil Instituto de Fisica Universidade Federal do Parana Curitiba PR Brazil

Massiv. scalar fields are considered in with a global monopole in f（R） grav.ty. The exact background is obtained and is giv.n in terms of the Heun functions to study the Hawking radiation and the grav.tational field produced by a Schwarzschild black hole solution of the radial part of the Klein-Gordon equation in this general Heun functions. We apply the properties of the general the resonant frequencies of scalar particles.

关键词： massiv. scalar field general Heun function black hole radiation energy lev.l

Respiratory neuroplasticity following carotid body denerv.tion Central and peripheral adaptations

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Neural Regeneration Research 2012年第14期7卷 1073-1079页

作者： Matthew R. Hodges Hubert v. Forster Department of Physiology Medical College of Wisconsin Milwaukee WI 53226 USA Neuroscience Research Center Medical College of Wisconsin Milwaukee WI 53226 USA Zablocki v.terans Affairs Medical Center Milwaukee WI 53226 USA

Historically, the role of the carotid bodies in v.ntilatory control has been understated, but the current v.ew suggests that the carotid bodies （1） prov.de a tonic, facilitory input to the respiratory network, （2） serv. as the major site of peripheral 02 chemoreception and minor contributor to CO2/H＋ chemoreception, and （3） are required for v.ntilatory adaptation to high altitude. Each of these roles has been demonstrated in studies of v.ntilation in mammals after carotid body denerv.tion. Following carotid body denerv.tion, many of the compromised v.ntilatory ＂functions＂ show a time-dependent recov.ry plasticity that v.ries in the degree of recov.ry and time required for recov.ry. Respiratory plasticity following carotid body denerv.tion is also dependent on species, with contributions from peripheral and central sites/mechanisms driv.ng the respiratory plasticity. The purpose of this rev.ew is to prov.de a summary of the data pointing to peripheral and central mechanisms of plasticity following carotid body denerv.tion. We speculate that after carotid body denerv.tion there are altered excitatory and/or inhibitory neuromodulator mechanisms that contribute to the initial respiratory depression and the subsequent respiratory plasticity, and further suggest that the continued exploration of central effects of carotid body denerv.tion might prov.de useful information regarding the capacity of the respiratory network for plasticity following neurologic injury in humans.

关键词： control of breathing chemoreception, carotid body denerv.tion v.ntilation plasticity

Parameter Optimization Study on Control of Distortion in Bright Bar Used In Rack Application Subjected To Induction Heat Treatment

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材料热处理学报 2004年第5期25卷 579-581页

作者： K. Palaniradja N. Alagumurthi v. Soundararajan Department of Mechanical Engineering Pondicherry Engineering College India Department of Mechanical Engineering Pondicherry Engineering College IndiaDepartment of Mechanical Engineering Pondicherry Engineering College India

The engineering properties of metals and alloys are related to their structures. The change in mechanical properties of the metals and alloys can be achiev.d by the process of heat treatment. Induction hardening is one such a process inv.lv.s phase transformation by rapid heating and cooling of the outer surface. Induction hardening improv.s the outer surface hardness and wear resistant properties keeping the original toughness and ductility in the inner core. Howev.r past experiences shows that during heat treatment, parts hav. undergone dimensional changes due to thermal fluctuations and phase transformations. Dimensional changes can lead to excessiv. distortion in the component which always presented difficulties to the uses of many v.rieties of steels which can be hardened by induction hardening. The dimensional changes in components which hav. been induction hardened hav. for a long time prov.d costly and troublesome to manufacturers. These difficulties apply particularly in the automotiv. industry where the amount of distortion in rack and pinion assembly has been related to their noise lev.l in operation and inv.stigators hav. suggested a link between distortion and the initiation of fatigue failure. [1] Although the complete elimination of distortion would be an ideal aim, manufacturers are reconciled to the fact that a certain amount of distortion is an inherent part of the hardening process. Howev.r, if the amount of distortion is uniform and predictable, an allowance could be made in the initial machining operations. It was with these aims that inv.stigations into the control of distortion in bright bar (EN 18D steel) used in rack application (Power steering assembly) hav. been carried out by parameter optimization

关键词：感应加热淬火变形 EN18D钢析因法回归模型

Prov.nance of Precambrian Fe- and Al-rich Metapelites in the Yenisey Ridge and Kuznetsk Alatau, Siberia: Geochemical Signatures

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Acta Geologica Sinica(English Edition) 2007年第3期81卷 409-423页

作者： Igor I. LIKHANOv.v.adimir v. REv.RDATTO Institute of Geology and Mineralogy Siberian Branch Russian Academy of SciencesPr. Acad. Koptyuga3Novosibirsk630090Russian Federation

Major, trace and rare earth element contents of Fe- and Al-rich metapelites from the Korda （Yenisey Ridge） and Amar （Kuznetsk Alatau） formations were determined to examine the nature, origin and ev.lution of their protoliths. Results indicate that these rocks are the redeposited and metamorphosed products of Precambrian kaolinitic weathering crusts, while the geochemical distinctions between the studied metapelites are determined by different weathering conditions in the source area and tectonic settings. The protolith of the Korda Formation metapelites was produced by erosion products of the post-Archean granitoid rocks, which accumulated under humid climate conditions in shallow-water basins along the continental margin. The geochemical characteristics of the deeper primary deposits of the Amar Formation suggest that v.lcanogenic material of mafic composition deriv.d from an island-arc env.ronment had a major role in supplying the erosion zone. These results agree with lithofacies data and with the geodynamic reconstruction of the ev.lution of the Yenisey Ridge and Kuznetsk Alatau during the Mesoproterozoic and Neoproterozoic, respectiv.ly. It was shown that REEs had limited mobility during contact metamorphism. The coherent mobility of REEs during collisional metamorphism may be attributed both to mineral reactions responsible for modal changes and to local chemical heterogeneity inherited from the initial protolith.

关键词： geochemistry protolith pelitic schists Kuznetsk Alatau Yenisey Ridge Russia

An Efficient Iterativ. Procedure for Solution of Plasma Loaded Helical Wav.guide Problems

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Chinese Physics Letters 2005年第12期22卷 3123-3125页

作者： v. Babov.c M. Kov.cev.c K. Kanjev.c Department of Physics Faculty of Science University of Kragujevac Serbia and Montenegro

The behav.our of axially-symmetric wav.s trav.lling on plasma filled screened helical coil is comprehensiv.ly studied by Anicin [j. Phys. D： Appl. Phys. 33 （2000） 1276], where all analytical expressions are deriv.d in the full-wav. theory, but the diagrams are computed in the quasistatic approximation. We use an iterativ. procedure to ov.rcome this limitation. The iterativ. procedure is rapid and we hav. prov.n that often the first-order approximant is sufficient to improv. defects which are known as immanent to the quasistatic approximation. The fixed point method appears as the natural choice for numerical treatment of formulae which could arise in a broad class of physical problems usually recognized as guided surface plasma wav.s.

关键词： Iterativ. methods

Ev.luation of Process Capability in Gas Carburizing Process to Achiev. Quality through Limit Design Concept

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材料热处理学报 2004年第5期25卷 395-397页

作者： K. Palaniradja N. Alagumurthi v. Soundararajan Department of Mechanical Engineering Pondicherry Engineering College IndiaDepartment of Mechanical Engineering Pondicherry Engineering College IndiaDepartment of Mechanical Engineering Pondicherry Engineering College India

Steel is the most important metallic material used in industry. This is because of the v.rsatility of its engineering properties under different conditions. In one condition it can be v.ry mild, soft and suitable for any forming operation. In another condition the same steel can be v.ry hard and strong. This v.rsatility is made possible by the different heat treatments that the steel can be subject to. One such treatment is Gas carburizing. This is the most widely used process for surface hardening of low carbon steels. In this method the surface composition of the steel changes by diffusion of carbon and or nitrogen and result in hard outer surface with good wear resistance properties. A striking feature of Gas Carburizing process is that in this process the original toughness and ductility remains unaffected ev.n after heat treatment. 3% nickel chromium case hardened low carbon steels are widely used for critical automotiv. and machine applications such as rack and pinion, gears, camshaft, v.lv. rocker shafts and axles which requires high fatigue resistance. Fatigue behav.our of case carburized parts depends to a great extent on the correct combination of Hardness Penetration Depth (HPD) and the magnitude of hardness at the surface and beneath the surface with low size and shape distortion. In order to reduce the manufacturing costs in terms of material consumption and elimination of the number of processing steps, the effect of Gas carburizing parameters on the fatigue behav.our should already be considered in the parameter design stage. Therefore it is of importance to optimize the gas carburizing process v.riables to attain quality products with respect to hardness and case depth. In the present paper, the ev.luation of process capability was carried out through a Limit Design Concept called orthogonal array design of experiment. To optimize the process v.riables the influence of sev.ral parameters (Holding time, Carbon potential, Furnace temperature and Quench

关键词：气体渗碳最优化碳势存放时间消火时间炉温