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Effects of nano-voids and nano-cracks on the elastic properties of a host medium: xfem modeling with level-set function and free surface energy

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Acta Mechanica Sinica 2019年第4期35卷 799-811页

作者： b.E. Hachi d. Hachi M. Haboussi Laboratoire de développement en Mécanique et Matériaux (LdMM) Université de Djelfa PB 3117 Djelfa Algérie Laboratoire d’Automatique Appliquée et diagnostics Industriels (LAAdI) Université de Djelfa PB 3117 Djelfa Algérie Laboratoire des Sciences des Procédés et des Matériaux (LSPM) Université Paris 13 UPR 3407 CNRS Paris France

This work deals with the influences of nano-heterogeneities in the form of voids/cavities or cracks on the elastic (please confirm which word is correct. effective or elastic? According to the title of paper, I choose elastic.) properties of a host medium. With a relatively large ratio of apparent-surface to volume and particularly strong physical interactions with the surrounding medium at nano-scale, nano-heterogeneities can potentially affect the elastic(effective or elastic?) properties of the parent medium (matrix) containing them in a significant manner. This has been reported by various theoretical and experimental studies, some of them are discussed in the present paper. To describe the positive (reinforcement) or negative (degradation) effect of the nano-heterogeneities from the modeling perspective, it is necessary to take into account the energy of interfaces/surfaces between nano-heterogeneities and the matrix which, by the fact of the relatively large extent of their apparent surface and their strong physical interaction with their neighborhood, can no longer be neglected compared to those of the volume energy. Thus, to account for the effects of interfaces/surfaces in a nanostructured heterogeneous medium, the coherent interface model is considered in the present investigation within a periodic homogenization procedure. In this interface/surface model, the displacement vector is assumed to be continuous across the interface while the stress vector is considered to be discontinuous and satisfying the Laplace-Young equations. To solve these equations coupled to the classical mechanical equilibrium problem, a numerical simulation tool is developed in a two-dimensional (2d) context using the eXtended Finite Element Method (XFEM) and the Level-Set functions. The developed numerical tool is then used to carry out a detailed analysis about the effect of nano-heterogeneities on the overall mechanical properties of a medium. The nano-heterogeneities are present

关键词： Interface/Surface energy XFEM Level-Set function Periodic homogenization Nano-voids/Nano-cavities Nano-cracks Nano-inclusions/Nano-heterogeneities

An approach to delineate groundwater recharge potential sites in Ambalantota,Sri Lanka using GIS techniques

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Geoscience Frontiers 2016年第1期7卷 115-124页

作者： i.p.senanayake d.m.d.o.k.dissanayake b.b.mayadunna w.l.weerasekera department of Earth Resources Engineering University of Moratuwa MoratuwaSri Lanka

The demand for fresh water in Hambantota district, Sri Lanka is rapidly increasing with the enormous amount of ongoing development projects in the region. Nevertheless, the district experiences periodic water stress conditions due to seasonal precipitation patterns and scarcity of surface water ***, management of available groundwater resources is critical, to fulfil potable water requirements in the area. However, exploitation of groundwater should be carried out together with artificial recharging in order to maintain the long term sustainability of water resources. In this study, a GIS approach was used to delineate potential artificial recharge sites in Ambalantota area within Hambantota. Influential thematic layers such as rainfall, lineament, slope, drainage, land use/land cover, lithology, geomorphology and soil characteristics were integrated by using a weighted linear combination method. Results of the study reveal high to moderate groundwater recharge potential in approximately 49% of Ambalantota area.

关键词： GIS Groundwater recharge Water management Weighted overlay Sri Lanka

Friction Stir Welding of discontinuously Reinforced Aluminum Matrix Composites:A Review

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Acta Metallurgica Sinica(English Letters) 2014年第5期27卷 816-824页

作者： d.Wang b.L.Xiao d.R.Ni Z.Y.Ma Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences

Friction stir welding （FSW） is considered a promising welding technique for joining the aluminum matrix composites （AMCs） to avoid the drawbacks of the fusion welding. High joint efficiencies of 60%-100% could be obtained in the FSW joints of AMCs. However, due to the existence of hard reinforcing particles in the AMCs, the wearing of welding tool during FSW is an unavoidable problem. Moreover, the low ductility of the AMCs limits the welding process window. As the hard materials such as Ferro-Titanit alloy, cermet, and WC/Co were applied to produce the welding tools, the wearing of the tools was significantly reduced and the sound joints could be achieved at high welding speed for the AMCs with low reinforcement volume fraction. In this article, current state of understanding and development of welding tool wearing and FSW parameters of AMCs are viewed. Furthermore, the factors affecting the microstructure and mechanical properties of the joints are evaluated in detail.

关键词： Metal matrix composite Friction stir welding Particle, microstructure Wear

Asymptotic Approximations of Apostol-Tangent Polynomials in Terms of Hyperbolic Functions

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Computer Modeling in Engineering & Sciences 2022年第7期132卷 133-151页

作者： Cristina b.Corcino Wilson d.Castaneda Jr Roberto b.Corcino Research Institute for Computational Mathematics and Physics Cebu Normal UniversityCebu City6000Philippines Mathematics department Cebu Normal UniversityCebu City6000Philippines department of Mathematics Cebu Technological UniversityCebu City6000Philippines

The tangent polynomials Tn(z)are generalization of tangent numbers or the Euler zigzag numbers *** particular,Tn(0)=*** polynomials are closely related to bernoulli,Euler and Genocchi *** of the extensions and analogues of special polynomials that attract the attention of several mathematicians is the Apostol-type *** of these Apostol-type polynomials is the Apostol-tangent polynomials Tn(z,λ).Whenλ=1,Tn(z,1)=Tn(z).The use of hyperbolic functions to derive asymptotic approximations of polynomials together with saddle point method was applied to the bernoulli and Euler polynomials by Lopez and *** same method was applied to the Genocchi polynomials by Corcino et *** essential steps in applying the method are(1)to obtain the integral representation of the polynomials under study using their exponential generating functions and the Cauchy integral formula,and(2)to apply the saddle point *** is found out that the method is applicable to Apostol-tangent *** a result,asymptotic approximation of Apostol-tangent polynomials in terms of hyperbolic functions are derived for large values of the parameter n and uniform approximation with enlarged region of validity are also ***,higher-order Apostol-tangent polynomials are *** the same method,asymptotic approximation of higherorder Apostol-tangent polynomials in terms of hyperbolic functions are derived and uniform approximation with enlarged region of validity are also *** is important to note that the consideration of Apostol-type polynomials and higher order Apostol-type polynomials were not done by Lopez and *** part is first done in this *** accuracy of the approximations are illustrated by plotting the graphs of the exact values of the Apostol-tangent and higher-order Apostol-tangent polynomials and their corresponding approximate values for specific values of the parameters n,λand m.

关键词： Apostol-tangent polynomials tangent polynomials Genocchi polynomials Hermite polynomials asymptotic approximation

Conclusions about testosterone therapy and cardiovascular risk

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Asian Journal of Andrology 2018年第2期20卷 152-153页

作者： bradley d Anawalt bu b Yeap division of Medicine University of Washington School of Medicine Seattle Washington 98195 United States School of Medicine University of Western Australia Perth Western Australia 6009 Australia department of Endocrinology and diabetes Fiona Stanley Hospital Perth Western Australia 6150 Australia

In this issue of Asian Journal of Andrology （AJA）, several experts have reviewed L the latest data on the potential and known effects of endogenous and exogenous testosterone （T） on cardiovascular risk. In the review by Meyer and Wittert, low endogenous serum T appears to be associated with higher risk of cardiovascular disease and overall mortality in certain populations such as Klinefelter syndrome and older men,

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Why is understanding the relationship of testosterone to cardiovascular risk so important？

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Asian Journal of Andrology 2018年第2期20卷 107-108页

作者： bu b Yeap bradley d Anawalt School of Medicine University of Western Australia Perth Western Australia 6009 Australia department of Endocrinology and diabetes Fiona Stanley Hospital Perth Western Australia 6150 Australia department of Medicine University of Washington School of Medicine Seattle Washington 98195 United States

Epidemiological studies hint at a beneficial influence of endogenous circulating testosterone （T）, or its metabolite dihydrotestosterone （dHT）, such that men with lower concentrations of T or dHT appear to have po...

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Numerical Solution of Fractional Partial differential Equations by discrete Adomian decomposition Method

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Advances in Applied Mathematics and Mechanics 2014年第1期6卷 107-119页

作者： d.b.dhaigude Gunvant A.birajdar department of Mathematics Dr.Babasaheb Ambedkar Marathwada UniversityAurangabad-431004(M.S.)India

In this paper we find the solution of linear as well as nonlinear fractional partial differential equations using discrete Adomian decomposition *** we develop the discrete Adomian decomposition method to find the solution of fractional discrete diffusion equation,nonlinear fractional discrete Schrodinger equation,fractional discrete Ablowitz-Ladik equation and nonlinear fractional discrete burger’s *** obtained solution is verified by comparison with exact solution whenα=1.

关键词： discrete Adomian decomposition method Caputo fractional derivative fractional discrete Schrodinger equation fractional discrete burger’s equation.

Continued surprises in the cytochrome c biogenesis story

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Protein & Cell 2012年第6期3卷 405-409页

作者： Elizabeth b.Sawyer Paul d.barker National Laboratory of biomacromolecules Institute of BiophysicsChinese Academy of SciencesBeijing 100101China University Chemical Laboratory University of CambridgeCambridgeCB21EWUnited Kingdom

Cytochromes c covalently bind their heme prosthetic groups through thioether bonds between the vinyl groups of the heme and the thiols of a CXXCH motif within the *** Gramnegative bacteria,this process is catalyzed by the Ccm(cytochrome c maturation)proteins,also called System *** Ccm proteins are found in the bacterial inner membrane,but some(CcmE,CcmG,CcmH,and CcmI)also have soluble functional domains on the periplasmic face of the *** of the mechanisms involved in the transport and relay of heme and the apo-cytochrome from the bacterial cytosol into the periplasm,and their subsequent reaction,has proved challenging due to the fact that most of the proteins involved are membrane-associated,but recent progress in understanding some key components has thrown up some *** this Review,we discuss advances in our understanding of this process arising from a substrate’s point of view and from recent structural information about individual components.

关键词： cytochrome c heme Ccm post-transla-tional modification cytochrome b562 heme binding

Phenotypic differences between coryneform bacteria isolated from seminal fluid of healthy men and men with chronic prostatitis syndrome

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Asian Journal of Andrology 2009年第4期11卷 517-520页

作者： Iuri b Ivanov Viktor A Gritsenko Michael d Kuzmin department of Human Microbiology Institute of Cellular and Intracellular Symbiosis Russian Academy of Sciences Orenburg 460056 Russia

We compared the potential phenotypic properties of coryneform bacteria associated with chronic prostatitis syndrome （CPS）, such as secretory inhibitor of lysozyme （SIL） and secretory inhibitor of platelet microbicidal protein （SIPMP）. A total of 110 clinical isolates of coryneform bacteria isolated from the seminal fluid of healthy men and men with CPS were tested. SIPMP production was tested by inhibiting platelet microbicidal protein （PMP） bioactivity against bacillus subtilis, and was expressed as percentage of inhibition of PMP bactericidal activity. SIL production was tested by inhibiting lysozyme activity against Micrococcus lysodeikticus and was expressed in microgram per millilitre of inactivated lysozyme. A significantly higher proportion of CPS strains （58.7% vs. 19.2 %） was SIPMP-positive compared with non-CPS strains （P 〈 0.01）. Of the CPS strains tested, 77.8% were SIL-positive compared with 34% of the non- CPS isolates （P 〈 0.05）. These results suggest that the diagnosis of CPS should not rely solely on classical parameters, for example, the identification and counting of microorganisms, but the functional significance of these parameters must be estimated, possibly by the concentration of different bacterial substrains, detection of opportunistic microorganisms with pathogenic properties, such as pronounced resistance to the cationic antimicrobial peptides, and/or the ability to inhibit the antimicrobial host defence factors.

关键词： Corynebacterium spp lysozyme platelet microbicidal protein prostatitis