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Acta Mechanica Solida Sinica 2019年第2期32卷 230-248页

作者： J.Vallepuga-Espinosa Lidia Sanchez-Gonzalez Ivan Ubero-Martinez departamento de Tecnologia Minera Topografiay de EstructurasUniversidad de LeonCampus de Vegazana s/n24071 LeonSpain departamento de Ingenierias mecanica Informatica y AeroespacialUniversidad de LeonCampus de Vegazana s/n24071 LeonSpain

This work presents a numerical methodology for modeling the Winkler supports and nonlinear conditions by proposing new boundary conditions. For the boundary conditions of Winkler support model, the surface tractions and the displacements normal to the surface of the solid are unknown, but their relationship is known by means of the ballast coefficient, whereas for nonlinear boundary conditions, the displacements normal to the boundary of the solid are zero in the positive direction but are allowed in the negative direction. In those zones, detachments of nodes might appear, leading to a nonlinearity, because the number of nodes that remain fixed or of the detached ones (under tensile tractions) is unknown. The proposed methodology is applied to the 3D elastic receding contact problem using the boundary element method. The surface t r actions and the displacements of the common int erface bet ween the two solids in contac t under the influence of different supports are calculated as well as the boundary zone of the solid where the new boundary conditions are applied. The problem is solved by a double-iterative met hod, so in the final solut ion, t here are no t r act ions or pene trations between the two solids or at the boundary of the solid where the nonlinear boundary conditions are Simula ted. The effectiveness of the proposed method is verified by examples.

关键词： Boundary element method Elastic contact problem Winkler support model Nonlinear boundary conditions

Reiterated homogenization of a laminate with imperfect contact:gain-enhancement of effective properties

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Applied Mathematics and Mechanics(English Edition) 2018年第8期39卷 1119-1146页

作者： F.E.ALVAREZ-BORGES J.BRAVO-CASTILLERO M.E.CRUZ R.GUINOVART-DIAZ L.D.PEREZ-FERNANdeZ R.RODRIGUEZ-RAMOS F.J.SABINA Facultad de Matematica y Computacion Departamento de MatematicaUniversidad de La HabanaSan Lazaro y LHabana 4La HabanaCP 10400Cuba departamento de Matematicas y mecanica Universidad Nacional Autonoma de MexicoInstituto de Investigaciones en Matematicas Aplicadas y en Sistemas01000 CDMXAP 20-126M′exico departamento de Engenharia mecanica Universidade Federal do Rio de JaneiroPolitecnica/COPPECaixa Postal 68503Rio de JaneiroRJCEP 21941-972Brasil departamento de Matematica e Estatistica Universidade Federal de PelotasCaixa Postal 354PelotasRio Grande do SulCEP 96010-900Brasil

A family of one-dimensional(1D) elliptic boundary-value problems with periodic and rapidly-oscillating piecewise-smooth coefficients is considered. The coefficients depend on the local or fast variables corresponding to two different structural scales. A finite number of imperfect contact conditions are analyzed at each of the scales. The reiterated homogenization method(RHM) is used to construct a formal asymptotic solution. The homogenized problem, the local problems, and the corresponding effective coefficients are obtained. A variational formulation is derived to obtain an estimate to prove the proximity between the solutions of the original problem and the homogenized problem. Numerical computations are used to illustrate both the convergence of the solutions and the gain of the effective properties of a three-scale heterogeneous 1D laminate with respect to their two-scale counterparts. The theoretical and practical ideas exposed here could be used to mathematically model multidimensional problems involving multiscale composite materials with imperfect contact at the interfaces.

关键词： reiterated homogenization method(RHM) imperfect contact variational formulation effective coefficient gain

DC Plasma Technology Applied to Powder Metallurgy: an Overview

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Plasma Science and Technology 2013年第1期15卷 70-81页

作者： A. N. KLEIN R. P. CARDOSO H. C. PAVANATI C. BINdeR A. M. MALISKA G. HAMMES D. FUSAO A. SEEBER S. F. BRUNATTO J. L. R. MUZART LabMat (Materials Laboratory) Departamento de Engenharia Mec~nica Universidade Federal de Santa Catarina (UFSC) 88040-900 FlorianSpolis - SC Brazil departamento de Engenharia mecanica Universidade Federal do Parana (UFPR) 81531-990 Curitiba- PR Brazil departamento Academico de Metal-mecanica Instituto Federal de Santa Catarina (IFSC) 88020-300 Florianopolis - SC Brazil Universidade Tecnologica Federal do Parana (UTFPR) 84016-210 Ponta Grossa - PR Brazil Centro de Ciencia e Tecnologia Universidade de Caxias do Sul 95070-560 Caxias do Sul- RS Brazil

DC plasma is a very promising technology for processing different materials, and is becoming especially interesting when low environmental impact and high-performance treatments are needed. Some of the intrinsic characteristics of DC plasma technology, which make it suitable for powder metallurgy （PM） and powder injection molding （PIM） parts production, are low- pressure processing and plasma environment high reactivity. Moreover it can be considered as a highly competitive green technology. In this work, an overview of some of the important DC plasma techniques applied to PM and PIM parts processing is presented. Emphasis is given to the descriptions of the main characteristics and the technique potentials of plasma-assisted nitriding, plasma-assisted thermal debinding, plasma-assisted sintering, and simultaneously plasma-assisted sintering and surface alloying. The aspects presented and discussed in this paper indicate that DC plasma processes are promising and competitive techniques for PM and PIM parts processing.

关键词： powder metallurgy DC glow discharge plasma nitriding plasma sintering,plasma-assisted thermal debinding surface alloying

Single droplet drying of detergents:Experimentation and modelling

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Particuology 2021年第5期19卷 35-47页

作者： Borja Hernandez Rosa Mondragon Mark A.Pintoa Leonor Hernandez J.Enrique Julia Juan Carlos Jarque Sergio Chiva Mariano Martin Newcastle Innovation Centre Procter&Gamble R&DNewcastle upon TyneUK departamento de Ingenieria Quimica y Textil.Universidad de Salamanca SalamancaSpain departamento de Ingenieria mecanica y Construccion Universitat Jaume ICastellon de la PlanaSpain Instituto de Tecnologia Ceramica Universitat Jaume ICastellon de la PlanaSpain

This study evaluates the single droplet drying(SDD)of *** data are used to validate a theoretical multistage *** experiments are carried out in an acoustic levitator analysing six different detergent formulations at 393 *** work is completed by developing a model based on conservation *** model is composed of the three stages observed in the drying *** the first stage,an external surface drying stage occurs until the surface is saturated and the crust is *** the next stage,the drying rate is governed by diffusion through the *** the same time,the particle heats up until boiling conditions are achieved in the core of the *** this point,the third stage *** the final stage,the droplet core is in boiling conditions which are governed by the pressure drop through the crust and the concentration of *** model has been evaluated for the different formulations being flexible to predict the drying of different mixtures with good accuracy.

关键词： Drying Single droplet Acoustic levitator detergents

Non-destructive microstructural analysis by electrical conductivity:Comparison with hardness measurements in different materials

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Journal of Materials Science & Technology 2019年第3期35卷 360-368页

作者： Gon?alo L.Sorger J.P.Oliveira Patrick L.Inácio Norbert Enzinger Pedro Vila? R.M.Miranda Telmo G.Santos department of Engineering design and Production School of Engineering Aalto University department of Materials Science and Engineering The Ohio State University UNIdeMI Departamento de Engenharia Mecanica e Industrial Faculdade de Ciências e Tecnologia Universidade Nova de Lisboa IMAT-Institute of Materials Science Joining and FormingTU Graz

The use of non-destructive evaluation(Nde) techniques for assessing microstructural changes in processed materials is of particular importance as it can be used to assess, qualitatively, the integrity of any material/structure. Among the several Nde techniques available, electrical conductivity measurements using eddy currents attract great attention owing to its simplicity and reliability. In this work, the electrical conductivity profiles of friction stir processed Ti6Al4 V, Cu, Pb, S355 steel and gas tungsten arc welded AISI 304 stainless steel were determined through eddy currents and four-point probe. In parallel, hardness measurements were also performed. The profiles matched well with the optical macrographs of the materials: while entering in the processed region a variation in both profiles was always observed. One particular advantage of electrical conductivity profiles over hardness was evident: it provides a better resolution of the microstructural alterations in the processed materials. Moreover, when thermomechanical processing induces microstructural changes that modify the magnetic properties of a material,eddy currents testing can be used to qualitatively determine the phase fraction in a given region of the material. A qualitative relation between electrical conductivity measurements and hardness is observed.

关键词： Non-destructive evaluation techniques Electrical conductivity Hardness Friction stir processing Gas tungsten arc welding

Production of Ca<sub>2</sub>AlNbO<sub>6</sub>Ceramics and Study of Their Stability in Crude Petroleum for the Conservation of Metallic Sensing Elements used in Petroleum Extraction

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Materials Sciences and Applications 2012年第6期3卷 408-413页

作者： Yogendra P. Yadava Marilaine M. de Lima José Carlos S. Oliveira Ricardo A. Sanguinetti Ferreira departamento de Engenharia mecanica Universidade Federal de Pernambuco Recife Brasil

In the present work a niobium based complex cubic perovskite oxide Ca2AlNbO6 ceramic was produced, characterized and studied its stability in crude petroleum environment for inert ceramic embedding for temperature sensors used in petroleum extraction. Ca2AlNbO6 ceramic powder was prepared through thermo-mechanical processing. Structural characteristics of calcined material was investigated by powder X-ray diffarctometry, which presented a single phase complex cubic perovskite structure with lattice parameter a = 7.6599 ?. Compacted discs of Ca2AlNbO6 ceramics were sintered in the temperature range 1250°C - 1350°C during 24 hours in ambient atmosphere. Microstructure of the sintered ceramics was studied by scanning electron microscopy and mechanical behavior was studied by Vicker’s microhardness testing. Ca2AlNbO6 ceramics sintered at 1350°C presented best results in terms of microstructural homogeneity and mechanical hardness. Therefore these sintered ceramics were submerged in crude petroleum for 60 days. Ceramics were taken out from the petroleum periodically and subjected to structural, microstructural and mechanical characterizations. Results showed that ceramics submerged in crude petroleum did not suffer any change at any stage of submersion. These characteristics make this material suitable for inert ceramic embedding for sensors used in petroleum extraction.

关键词： Ca2AlNbO6 Production Microstructure Mechanical Properties Stability in Crude Petroleum

Photolysis of a mixture of anthracene and benzo[a] pyrene at ultra-trace levels in natural water with disinfection purposes

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Journal of Environmental Sciences 2020年第6期32卷 79-94页

作者： Ainhoa Rubio-Clemente Edwin Chica Gustavo A.Penuela Facultad de Ciencias de La Salud.Universidad Catolica de Murcia(UCAM) Murcia 30107Spain Grupo GDCON Facultad de IngenieriaSede de Investigaciones Universitarias(SIU)Universidad de Antioquia(UdeA)Medellín 050010Colombia Facultad de Ingenieria Tecnologico de Antioquia-Institucion Universitaria(TdeA)Medellín 050034Colombia departamento de Ingenieria mecanica Facultad de IngenieriaUniversidad de Antioquia(UdeA)Medellín 050010Colombia

The photodegradation of anthracene(AN)and benzo[a]pyrene(BaP),two priority polycyclic aromatic hydrocarbons(PAHs),was examined at ultra-trace levels in surface water to elucidate their behaviour under several irradiance values and types of *** emitting flux and the spectrum of the lamps were found to develop a crucial role in AN and BaP degradation since removal efficiencies of the target contaminants higher than 99%were found after 15 min of irradiation under an ultraviolet C(UVC)irradiance of 0.63 mW/cm^2,corresponding to a fluence of 560.25 mJ/cm^*** the other hand,although ultraviolet A(UVA)lamps exhibited a higher irradiance compared to that of UVC lamps,they were not efficient for degrading the target *** removal kinetic studies corroborated these findings,being the AN elimination rate in surface water higher than that in deionized water at optimal operating *** potential was also measured.A rapid microbial load inactivation,in terms of total coliforms naturally contained in the water matrix studied,was evidenced within 15 min of treatment for the fluence ***,after 24 hr in the dark,a regrowth was ***,photolysis products more toxic than the parent compounds were found,which were not removed even by extending the treatment *** this regard,it can be concluded that the individual action of UVC light for removing AN and BaP with disinfection purposes is not an efficient treatment;therefore,the use of radiation in combination with other kinds of treatments is required.

关键词： Polycyclic aromatic hydrocarbon Photolysis Matrix constituent Intermediate product Disinfection Regrowth

An Investigation into the Isolation Performance of Mono-and Bi-stable Systems

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Journal of Marine Science and Application 2014年第3期13卷 291-298页

作者： Zeqi Lu Tiej un Yang Michael J. Brennan Xinhui Li Zhigang Liu College of Power and Energy Engineering Harbin Engineering University Harbin 150001 China departamento de Engenharia mecanica UNESP Ilha Solteira 03001-000 Brizal

由对改进隔离表演的需要激发了，许多研究研究与非线性的特征在隔离乾上被执行了。基于他们的阶段肖像的形状，如此的设备能作为也被设置单稳态或双稳态的隔离乾。这篇论文集中于在一样的刺激下面调查这二个班的相对表演。力量能递送被... 详细信息

由对改进隔离表演的需要激发了，许多研究研究与非线性的特征在隔离乾上被执行了。基于他们的阶段肖像的形状，如此的设备能作为也被设置单稳态或双稳态的隔离乾。这篇论文集中于在一样的刺激下面调查这二个班的相对表演。力量能递送被用来测量隔离表演，它以播送力量的比率的 RMS 被定义到刺激力量。当系统受到泛音刺激时，在隔离的力量能递送的最大的减小用伪变化，这被发现 -- 零僵硬被完成。当系统受到随机的刺激时，它有伪的一样的效果 -- 零僵硬。进一步，最佳抑制能与僵硬被改变并且有最小的价值。

关键词：双稳系统性能力传递率非线性特性谐波激励随机激励隔离器激励力

A Robust, Fully Adaptive Hybrid Level-Set/Front-Tracking Method for Two-Phase Flows with an Accurate Surface Tension Computation

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Communications in Computational Physics 2010年第6期8卷 51-94页

作者： Hector D.Ceniceros Alexandre M.Roma Aristeu Silveira-Neto Millena M.Villar department of Mathematics University of California Santa BarbaraCA 93106USA departamento de Matematica Aplicada Universidade de Sao PauloCaixa Postal 66281CEP 05311-970Sao Paulo-SPBrasil Faculdade de Engenharia mecanica Universidade Federal de UberlandiaCEP 38400-902Uberlandia-MGBrasil

We present a variable time step,fully adaptive in space,hybrid method for the accurate simulation of incompressible two-phase flows in the presence of surface tension in two *** method is based on the hybrid level set/front-tracking approach proposed in[*** and ***,***.,205,391-400,2005].Geometric,interfacial quantities are computed from front-tracking via the immersed-boundary setting while the signed distance(level set)function,which is evaluated fast and to machine precision,is used as a fluid *** surface tension force is obtained by employing the mixed Eulerian/Lagrangian representation introduced in[***,***-Khalik,*** and ***,***.,203,493-516,2005]whose success for greatly reducing parasitic currents has been *** use of our accurate fluid indicator together with effective Lagrangian marker control enhance this parasitic current reduction by several orders of *** resolve accurately and efficiently sharp gradients and salient flow features we employ dynamic,adaptive mesh *** spatial adaption is used in concert with a dynamic control of the distribution of the Lagrangian nodes along the fluid interface and a variable time step,linearly implicit time integration *** present numerical examples designed to test the capabilities and performance of the proposed approach as well as three applications:the long-time evolution of a fluid interface undergoing Rayleigh-Taylor instability,an example of bubble ascending dynamics,and a drop impacting on a free interface whose dynamics we compare with both existing numerical and experimental data.

关键词： Front-tracking immersed boundary method level set method adaptive mesh re-finements semi-implicit methods multilevel multigrid closest point transform semi-backward difference formula

Submegahertz spectral width photon pair source based on fused silica microspheres

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Photonics Research 2021年第11期9卷 2237-2252页

作者： ERASTO ORTIZ-RICARDO CESAR BERTONI-OCAMPO MONICA MALDONADO-TERRON ARTURO GARCIA ZURITA ROBERTO RAMIREZ-ALARCON HECTOR CRUZ RAMIREZ R.CASTRO-BELTRAN ALFRED B.U’REN Instituto de Ciencias Nucleares Universidad Nacional Autonoma de MexicoApartado Postal 70-54304510 MexicoD.F.Mexico Centro de Investigaciones en Optica A.C. Loma del Bosque 115Colonia Lomas del Campestre37150 LeonGuanajuatoMexico departamento de Ingenieria Fisica Cuerpo Academico de Mecanica EstadisticaDivison de Ciencias e IngenieriasUniversidad de Guanajuato37150 LeonGuanajuatoMexico

High-efficiency submegahertz bandwidth photon pair generators will enable the field of quantum technology to transition from laboratory demonstrations to transformational applications involving information transfer from photons to *** spontaneous parametric processes are able to achieve high-efficiency photon pair generation,the spectral bandwidth tends to be relatively large,as defined by phase-matching *** solve this fundamental limitation,we use an ultrahigh quality factor(Q)fused silica microsphere resonant cavity to form a photon pair *** present the full theory for the spontaneous four-wave mixing(SFWM)process in these devices,fully taking into account all relevant source characteristics in our *** exceptionally narrow(down to kilohertz-scale)linewidths of these devices result in a reduction in the bandwidth of the photon pair generation,allowing submegahertz spectral bandwidth to be ***,using a pump source centered around 1550 nm,photon pairs with the signal and idler modes at wavelengths close to 1540 and 1560 nm,respectively,are *** herald a single idler-mode photon by detecting the corresponding signal photon,filtered via transmission through a wavelength division multiplexing channel of *** demonstrate the extraction of the spectral profile of a single peak in the single-photon frequency comb from a measurement of the signal–idler time of emission *** improvements in device design and experimental methods enabled the narrowest spectral width(Δν=366 k Hz)to date in a heralded single-photon source based on SFWM.

关键词： fused silica spectral