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Acta Mechanica Sinica 2019年第4期35卷 828-838页

作者： X. Ji f. Zhu School of.Aerospace Engineering and Applied Mechanics Tongji University Shanghai 200092 China

The elastoplastic f.eld near crack tips is investigated through f.nite element simulation.A ref.ned mesh model near the crack tip is proposed. In the mesh ref.ning area, element size continuously varies f.om the nanometer scale to themicrometer scale and the millimeter scale. Graphics of.the plastic zone, the crack tip blunting, and the def.rmed crack tip elements are given in the *** on the curves of.stress and plastic strain, closely near the crack tip, the stresssingularity index and the stress intensity f.ctor,as well as the plastic strain singularity index and the plastic strain intensity f.ctor are *** and plastic strainsingular index vary with the load, while the dimensions of.the stress and the plastic strain intensity f.ctorsdependon the stress and the plastic strain singularity index, respectively. The singular f.eld near the elastoplastic crack tip is characterized by the stress singularity index and the stress intensity f.ctor, or alternativelythe plastic strain singularity index and the plastic strain *** the end of.the paper, f.llowing Irwin’s concept of.f.acture mechanics,σδKσδKcriterion andεδQεδQcriterion are ***, crack tip angle criterion is also presented.

关键词： Crack f.acture mechanics Elastoplasticity f.nite element method Geometry Nonlinearity

Local Entropy Production in Turbulent Shear f.ows:A Tool f.r Evaluating Heat Transf.r Perf.rmance

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Journal of.Thermal Science 2006年第2期15卷 159-167页

作者： H. HERWIG f. KOCK Hamburg University of.Technology 21073 Hamburg Germany. BMW 80788 Munich Germany

Perf.rmance evaluation of.heat transf.r devices can be based on the overall entropy production in these devices. In our study we theref.re provide equations f.r the systematic and detailed determination of.local entropy production due to dissipation of.mechanical energy and due to heat conduction, both in turbulent f.ows. Af.er turbulence modeling has been incorporated f.r the f.uctuating parts the overall entropy production can be determined by integration with respect to the whole f.ow domain. Since, however, entropy production rates show very steep gradients close to the wall, numerical solutions are f.r more ef.ective with wall f.nctions f.r the entropy production terms. These wall f.nctions are mandatory when high Reynolds number turbulence models are used. f.r turbulent f.ow in a pipe with an inserted twisted tape as heat transf.r promoter it is shown that based on the overall entropy production rate a clear statement f.om a thermodynamic point of.view is possible. f.r a certain range of.twist strength there is a decrease in overall entropy production compared to the case without insert. Also, the optimum twist strength can be determined. This inf.rmation is unavailable when only pressure drop and heat transf.r data are given.

关键词： entropy production turbulent heat transf.r wall f.nctions

Antibacterial properties of.copper-substituted cobalt f.rrite nanoparticles synthesized by co-precipitation method

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Particuology 2017年第1期15卷 158-163页

作者： Alireza Samavati A. f. Ismail Advanced Membrane Technology Research Centre (AMTEC) Universiti Teknologi Malaysia 81310 Skudai Johor Malaysia

Controlled growth and caref.l characterization of.cobalt f.rrite nanoparticles f.r antibacterial applica- tions are challenging. Copper-substituted cobalt f.rrite nanoparticles （CuxCo1-xf.2O4）, where x = 0.0, 0.3, 0.5, 0.7 and 1.0, were synthesized using an economical and simple co-precipitation technique. The crys- tal structure and antibacterial properties of.the samples as a f.nction of.Cu-substituted content were systematically studied. With increasing Cu concentration, the nanopartide size decreased f.om ~30 to ~20 nm. The f.urier transf.rm inf.a-red spectra exhibit two prominent f.ndamental absorption bands, at ~595 and 419 cm^-1. These bands correspond to intrinsic stretching vibrations of.metals at tetrahedral and octahedral sites, respectively. The Raman scattering results reveal that increasing the Cu content enhances the local disorder at both tetrahedral and octahedral sub lattices. The results indicate that the substitution of.Co with Cu in cobalt f.rrite nanoparticles strongly inf.uences the microstructure, crystal structure, and oarticle diameter, and also improves the antibacterial properties.

关键词： Cobalt f.rrite nanoparticles X-ray dif.raction Raman spectroscopy Antibacterial properties

Evaluation of.f.MA-440 f.r including soil-structure interaction

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Earthquake Engineering and Engineering Vibration 2010年第3期9卷 397-408页

作者： Khoshnoudian f. Behmanesh I. f.culty of.Civil Engineering Amirkabir University of Technology f.culty of.Civil and Environmental Engineering Tufts University

Replacing the entire soil-structure system with a f.xed base oscillator to consider the ef.ect of.soil-structure interaction （SSI） is a common analysis method in seismic design. This technique has been included in design procedures such as NEHRP, ASCE, etc. by def.ning an equivalent f.ndamental period and damping ratio that can modif. the response of.the structure. However, recent studies indicate that the ef.ects of.SSI should be reconsidered when a structure undergoes a nonlinear displacement demand. In recent documents on Nonlinear Static Procedures （NSPs）, f.MA-440 （2005）, a modif.ed damping ratio of.the replacement oscillator was proposed by introducing the ductility of.the soil-structure system obtained f.om pushover analysis. In this paper, the damping def.ned in f.MA-440 to include the soil-structure interaction ef.ect is evaluated, and the accuracy of.the Coef.icient Method given in f.MA-440 and the Equivalent Linearization Method is studied. Although the improvements f.r Nonlinear Static Procedures （NSPs） in f.MA-440 are achieved f.r a f.xed base SDOf.structure, the soil ef.ects are not perf.ctly obtained. f.rthermore, the damping def.nition of.a soil-structure system is extended to structures to consider bilinear behavior.

关键词： soil-structure interaction f.undation damping inelastic behavior equivalent linearization

Seasonal size-segregated PM10 and PAH concentrations in a rural area of.sugarcane agriculture versus a coastal urban area in Southeastern f.orida, USA

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Particuology 2016年第5期14卷 52-59页

作者： Orhan Sevimoglu Wolf.ang f. Rogge Department of.Civil and Environmental Engineering Florida International University 10555 W. Flagier Street Miami FL 33174 USA School of.Engineering and Sierra Nevada Research Institute University of California at Merced 5200 North Lake Road Merced CA 95343 USA

Airborne particulate matter （PM） is of.health and environmental concern not only in highly urbanized areas, but also in rural areas that are used f.r intensive agricultural purposes, In this study, PM size- segregated samples were collected simultaneously f.r 12 months in a small town （Belle Glade, f.orida）, which is the center of.a vast sugarcane growing area and at Delray Beach, a coastal city in Palm Beach County, f.orida. During the winter sampling period, when sugarcane f.liage is burned just bef.re harvest- ing to reduce the amount of.plant matter to be handled, PM10 levels were 50% or higher than otherwise measured, indicating that sugarcane harvesting and processing is a major local source f.r PM10. f.r the rest of.the year, PM10 levels at both sites are similar, suggesting that ambient PM levels at both sites are impacted by the major urban centers in Southern f.orida. During late July and early August, the PM10 levels at both sites were substantially elevated and revealed the typical red-brownish color of.Saharan dust. This has been reported to occur f.equently with suitable meteorological conditions over the Atlantic Ocean coupled with a Sahara dust storm event. During the sugarcane harvesting season at Belle Glade, the concentrations of.PAHs associated with PM10 were up to 15 times higher than those measured during the summer growing season, indicating a substantially higher exposure of.the rural population to these of.en mutagenic and carcinogenic compounds.

关键词： Size segregated ambient particles PM10 PAHs Biomass burning Rural versus urban Saharan dust

Evidence f.r the ef.cacy and saf.ty of.herbal weight loss preparations

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Journal of.Integrative Medicine 2019年第2期17卷 87-92页

作者： Rachael f.rrington Ian f.Musgrave roger W.Byard Adelaide Medical School The University of Adelaide f.rensic Science SA

Rising rates of.obesity across the globe have been associated with an increase in the use of.herbal preparations f.r weight control. However, the mechanisms of.action f.r these substances are of.en not known,as is the potential f.r interaction with other herbal preparations or prescription pharmaceutical drugs. To investigate the reported ef.icacy and saf.ty of.herbal weight loss preparations, we conducted a review of.the literature f.cusing on herbs that are most commonly used in weight loss preparations, specif.cally,Garcinia cambogia, Camellia sinensis, Hoodia gordonii, Citrus aurantium and Coleus f.rskohlii. There was no clear evidence that the above herbal preparations would cause sustained long-term weight loss in humans in the long term. Serious illness and even death have occasionally resulted f.om the use of.herbal weight loss preparations. f.w clinical trials have been undertaken to evaluate the ef.icacy and/or saf.ty of.herbal weight loss preparations. In addition, potential issues of.herb–herb and herb–drug interactions are of.en not considered. Regulation of.these products is much less rigorous than f.r prescription medications, despite documented cases of.associated hepatotoxicity.

关键词： Weight loss Hepatotoxicity Complementary medicine Traditional Chinese medicine

Prof.le and Secondary f.ow Losses in a High-Lif. LPT Blade Cascade at Dif.erent Reynolds Numbers under Steady and Unsteady Inf.ow Conditions

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Journal of.Thermal Science 2012年第6期21卷 483-491页

作者： Satta f. Simoni D. Ubaldi M. Zunino P. Bertini f. DIMSET-Università di Genova Via Montallegro 1I-16145 GenovaItaly Avio S.p.A. Viale I Maggio 56I-10040 Rivalta(TO)-Italy

The aerodynamic f.ow f.eld downstream of.a Low-Pressure High-Lif.(HL)turbine cascade has been experimentally investigated f.r dif.erent Reynolds numbers under both steady and unsteady inf.ows,in order to analyse the cascade perf.rmance under real engine operating *** Reynolds number has been varied in the range 100000f.cruise and take-of./landing conditions,*** ef.ects induced by the incoming wakes at the reduced f.equency f.=0.62 on both prof.le and secondary f.ow losses have been *** pressure,velocity and secondary kinetic energy distributions at the downstream tangential plane have been measured by means of.a miniaturized 5-hole *** quantities provide inf.rmation on both blade wake and secondary f.ow structures(passage and horse-shoe vortices).The analysis of.the results allows the evaluation of.the aerodynamic perf.rmance of.the HL f.ont-loaded blade in terms of.both prof.le and secondary losses.

关键词： prof.le losses secondary f.ow losses high-lif. prof.es unsteady inf.ow LPT blade.

Approaching nuclei through multiple perspectives and diverse models： Patterns, symmetries, interactions

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f.ontiers of.physics 2018年第6期13卷 29-38页

作者： R. f. Casten Wright Nuclear Structure Laboratory Yale University New Haven CT 06520 USA Michigan State University- f.IB East Lansing MI USA

Nuclei are complex objects yet display remarkable simplicities and regular patterns. The study of.these and their origins has long been one of.the twin pillars of.nuclear structure research. We will discuss the behavior of.atomic nuclei f.om this point of.view. A key element will be the advantages of.looking at the same data f.om dif.erent perspectives and of.inter-relating these perspectives.

关键词： nuclear structure simple patterns and symmetries diverse perspectives and models emergence of.collectivity residual interactions

Prediction of.Soil Depth f.om Digital Terrain Data by Integrating Statistical and Visual Approaches

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Pedosphere 2010年第3期20卷 361-367页

作者： f. M. ZIADAT International Center f.r Agricultural Research in the Dry Areas (ICARDA) P.O. Box 5466Aleppo (Syria)

Inf.rmation about the spatial distribution of.soil attributes is indispensable f.r many land resource management applications; however, the ability of.soil maps to supply such inf.rmation f.r modern modeling tools is questionable. The objectives of.this study were to investigate the possibility of.predicting soil depth using some terrain attributes derived f.om digital elevation models （DEMs） with geographic inf.rmation systems （GIS） and to suggest an approach to predict other soil attributes. Soil depth was determined at 652 f.eld observations over the A1-Muwaqqar Watershed （70 km2） in Jordan. Terrain attributes derived f.om 30-m resolution DEMs were utilized to predict soil depth. The results indicated that the use of.multiple linear regression models within small watershed subdivisions enabled the prediction of.soil depth with a dif.erence of.50 cm f.r 77% of.the f.eld observations. The spatial distribution of.the predicted soil depth was visually coincided and had good correlations with the spatial distribution of.the classes amalgamating three terrain attributes, slope steepness, slope shape, and compound topographic index. These suggested that the modeling of.soil-landscape relationships within small watershed subdivisions using the three terrain attributes was a promising approach to predict other soil attributes.

关键词： compound topographic index digital elevation model GIS watershed

Modelling of.Gettering by Mechanical Damage of.Metallic Impurities in Silicon

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Chinese Physics Letters 2006年第11期23卷 3058-3060页

作者： f. Ayad M. Remram Department of.Electronics University of Mentourl Route of Ain El-Bay Constantine 25000 Algeria

Reducing the concentration of.the metallic impurities present in silicon-based electronic components plays a vital role in manuf.ctures. Gettering by induced mechanical damage is one of.the methods used in neutralizing these impurities. To simulate this type of.gettering, we explicitly include the role of.the traps due to mechanical damage, based on the mechanism of.kick-out. In our model, we choose the essential parameters including concentration of.impurities, thickness, temperature, time, etc. The dif.usion coef.icient and equilibrium concentration of.the silicon interstitials estimated f.om the literature have been adjusted to be in good agreement with the experimental data.

关键词： DIf.USION GOLD