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Flow characteristics in a parallel-plate porous channel under convective boundary conditions and triple diffusion for the non-Darcy porous matrix

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Propulsion and Power Research 2021年第4期10卷 396-411页

作者： j.c.Umavathi Department of Mathematics Gulbarga UniversityGulbarga585106KarnatakaIndia

This article inspects the effect of triple diffusion in a vertical conduit encapsulated with porous matrix and subjected to third kind boundary *** kind boundary condition is a combination of Dirichlet and Neumann boundary conditions which specifies a linear combination of function and its derivative values on the *** chemical reaction along with viscous and Darcy dissipation effects are *** the Boussinesq approximation,the soultal buoyancy effects due to concentration gradients of the dispersed components are taken into *** suitable transformations,the conservation equations are reduced into dimensionless form and the dimensionless parameters evolved are thermal Grashof number (0≤Λ_(1)≤20),solutal Grashof number(for species 1 and 2,0≤Λ_(2);Λ_(3)≤20),porous (2≤σ≤8) and inertial parameters (0≤Ι≤6),Biot numbers(at the left and right walls,1≤Bi_(1);Bi_(2)≤10),Brinkman number (0≤Br≤1),Schmidt numbers (0≤Sc_(1);Sc_(2)≤6),Soret numbers (Sr_(1) =Sr_(2) =1) and temperature difference ratio (R_(T) = 1).Adopting perturbation technique,the analytical solutions which are applicable only when the Brinkman number is less than one is *** for any values of the Brinkman number,Runge-Kutta shooting method is *** impact of selected parameters on the momentum,heat and dual species concentration fields are presented in the form of *** solutions computed by numerical method are justified by comparing with the analytical *** numerical and analytical solutions are equal in the absence of Darcy and viscous dissipations and the discrepancy advances as the Brinkman number *** the solutions obtained are also justified by comparing the results with Zanchini[1]in the absence of chemical reaction for clear *** thermal field is augmented with the Brinkman number for symmetric and asymmetric Biot *** the profiles are highly distinct at the cold plate for unequal Biot numbers

关键词： Mixed convection Robin boundary conditions Darcy-Forchheimer-Brinkman model Soret number Runge-Kutta shooting method

State of the Art on Micromilling of Materials,a Review

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journal of Materials Science & Technology 2012年第8期28卷 673-685页

作者： M.A.cmara j.c. campos Rubio A.M. Abro j.P. Davim Department of Mechanical Engineering Universidade Federal de Minas GeraisAv.Ant onio Carlos6627-Pampulha Belo Horizonte MGCEP:31.270-901Brazil Department of Mechanical Engineering University of AveiroCampus Universitrio de Santiago3810-193AveiroPortugal

The trend towards miniaturization has increased dramatically over the last decade, especially within the fields concerned with bioengineering, microelectronics, and aerospace. Micromillin8 is among the principal manu- facturing processes which have allowed the development of components possessing micrometric dimensions, being used to the manufacture of both forming tools and the final product. The aim of this work is to present the principal aspects related to this technology, with emphasis on the work material requirements, tool ma- terials and geometry, cutting forces and temperature, quality of the finished product, process modelling and monitoring and machine tool requirements. It can be noticed that size effect possesses a relevant role with regard to the selection of both work material （grain size） and tooling （edge radius）. Low forces and temper- ature are recorded during micromillin8, however, the specific cutting force may reach high values because of the ploughing effect observed as the uncut chip thickness is reduced. Finally, burr formation is the principal concern with regard to the quality of the finished part.

关键词： Micro-milling Micromachining Size effect Miniaturization

Effect of Solute contents of Al-Ni-Sr Alloy on Glass Forming Ability and Thermal Stability

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journal of Rare Earths 2004年第Z2期22卷 73-77页

作者： Taek Soo Kim j K Lee H j Kim j c Bae Advanced Materials R&D center Korea Institute of Industrial Technology994-32 Dongchun-dongYeonsu-kuIncheon 406-130Korea Advanced Materials R&D CenterKorea Institute of Industrial Technology994-32 Dongchun-dongYeonsu-kuIncheon 406-130Korea Advanced Materials R&D CenterKorea Institute of Industrial Technology994-32 Dongchun-dongYeonsu-kuIncheon 406-130Korea Advanced Materials R&D CenterKorea Institute of Industrial Technology994-32 Dongchun-dongYeonsu-kuIncheon 406-130Korea

Glass forming ability (GFA) and structural characterization of a new amorphous Al-Ni-Sr alloy melt spun were investigated on the theory of the factors for the glass formation. The GFA was varied with the ratio of Ni to Sr in detail and successful amorphous phase dispersed with 2 ～ 5 nm precipitates was prepared from Al-Ni5-Sr3. Thermal stability and crystallization behavior of the amorphous phase were determined by continuous and isothermal heating technique on DcS, resulting that the crystallization occurs by the growth of fcc Al nanocrystals on the preexistent nuclei.

关键词： glass formation crystallization Al base amorphous alloys rapid solidification

Non-polynomial Zig-Zag and ESL shear deformation theory to study advanced composites

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chinese journal of Aeronautics 2019年第4期32卷 906-920页

作者： j.L.MANTARI I.A.RAMOS j.c.MONGE Faculty of Mechanical Engineering Instituto de investigación en ingeniería naval(IDIIN)National University of Engineering(UNI)Lima 15333Peru Department of Mechanical Engineering University of New Mexico Faculty of Mechanical Engineering Universidad de Ingeniería y Tecnología(UTEC)

The mechanical behavior of advanced composites can be modeled mathematically through unknown variables and Shear Strain Thickness Functions(SSTFs). Such SSTFs can be of polynomial or non-polynomial nature and some parameters of non-polynomial SSTFs can be optimized to get optimal results. In this paper, these parameters are called ‘‘r" and ‘‘s" and they are the argument of the trigonometric SSTFs introduced within the carrera Unified Formulation(cUF). The Equivalent Single Layer(ESL) governing equations are obtained by employing the Principle of Virtual Displacement(PVD) and are solved using Navier method solution. Furthermore, trigonometric expansion with Murakami theory was implemented in order to reproduce the Zig-Zag effects which are important for multilayer structures. Several combinations of optimization parameters are evaluated and selected by different criteria of average error. Results of the present unified trigonometrical theory with cUF bases confirm that it is possible to improve the stress and displacement results through the thickness distribution of models with reduced unknown variables. Since the idea is to find a theory with reduced numbers of unknowns, the present method appears to be an appropriate technique to select a simple model. However these optimization parameters depend on the plate geometry and the order of expansion or unknown variables. So, the topic deserves further research.

关键词： Analytical solution composite materials cUF ESL Plate Trigonometric functions Zig-Zag effects

Laser additive manufacturing of biodegradable Mg-based alloys for biomedical applications: A review

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journal of Magnesium and Alloys 2022年第4期10卷 915-937页

作者： c.L.Wu W.j.Xie H.c.Man Department of Industrial and Systems Engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina

Metallic implants are widely used in internal fixation of bone fracture in surgical *** are mainly used for providing mechanical support and stability during bone reunion,which usually takes a few months to *** implants made of stainless steels,Ti-based alloys and cocrMo alloys have been widely used for orthopedic reconstruction due to their high strength and high corrosion *** metallic implants will remain permanently inside the body after implantation,and a second surgery after bone healing is needed because the long-term presence of implant will lead to various *** implant removal surgery not only incurs expenditure,but also risk and psychological *** a consequence,studies on the development of biodegradable implants,which would degrade and disappear in vivo after bone reunion is completed,have drawn researchers’*** this connection,Mg-based alloys have shown great potentials as promising implant materials mainly due to their low density,inherent biocompatibility,biodegradability and mechanical properties close to those of ***,the high degradation rate of Mg-based implants in vivo is the biggest hurdle to *** from materials selection,a fixation implant is ideally tailor-made in size and shape for an individual case,for best surgical ***,laser additive manufacturing(LAM),with the advent of sophisticated laser systems and software,is an ideal process to solve these *** this paper,we reviewed the progress in LAM of biodegradable Mg-based alloys for biomedical *** effect of powder properties and laser processing parameter on the formability and quality was thoroughly *** microstructure,phase constituents and metallurgical defects formed in the LAMed samples were *** mechanical properties,corrosion resistance,biocompatibility and antibacterial properties of the LAMed samples were summarized and compared with samples fabricated by

关键词： Laser additive manufacturing Magnesium alloys Implant Biomedical applications Mechanical properties Biodegradability

Detection of Breaking Waves Using X-Band Pulse Radar in the Nearshore Region

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china Ocean Engineering 2013年第4期27卷 549-556页

作者： Y.c.Lin c.c.chang M.c.Lee H.c.chan j.M.Leu Department of Hydraulic and Ocean Engineering National Cheng-Kung University Department of Soil and Water conservation National Chung Hsing University Department of Hospitality Management Taiwan Shoufu University

An X-band pulsed Doppler microwave radar has been used to determine the characteristics of breaking waves. Field experiments were conducted at the Shuang-Si estuary in the north of Taiwan in the winter of 2005. Analyses on maxima radar cross section and Doppler frequency shift are done to characterize wave breaking zones. Based on observations of breaking waves, the wave breaking zones are shown to be located at water depths of 1.8 to 2.2 m in the experimental site. In general, the results indicate that a radar system has the potential to delineate the spatial variation of breaking waves clearly and that this is sufficient to achieve a measurement operation for near-shore air-sea interaction events.

关键词： radar Doppler effect wave breaking coastal zone

Numerical study of flow and heat transfer during oscillatory blood flow in diseased arteries in presence of magnetic fields

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Applied Mathematics and Mechanics(English Edition) 2012年第5期33卷 649-662页

作者： A.SINHA j.c.MISRA School of Medical Science and Technology Indian Institute of TechnologyKharagpur 721302India Department of Mathematics Institute of Technical Education and ResearchSiksha O Anusandhan UniversityBhubaneswar 751030India

A problem motivated by the investigation of the heat and mass transfer in the unsteady magnetohydrodynamic （MHD） flow of blood through a vessel is solved numerically when the lumen of the vessel has turned into the porous structure. The time-dependent permeability and the oscillatory suction velocity are considered. The computational results are presented graphically for the velocity, the temperature, and the concentration fields for various values of skin friction coefficients, Nusselt numbers, and Sherwood numbers. The study reveals that the flow is appreciably influenced by the presence of a magnetic field and also by the value of the Grashof number.

关键词： mass transfer radiation suction velocity skin-friction

Molecular level simulations on multi-component systems --a morphology prediction method

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Frontiers of chemical Science and Engineering 2013年第1期7卷 49-54页

作者： c. ScHMIDT j. ULRIcH center for Engineering Science Thermal Process Engineering Martin Luther University Halle-Wittenberg D-06099 Halle (Saale) Germany

The crystal morphology grown from a solution composed of an organic solvent, solute and additive can be predicted reliably by a computational method. Modeling the supersaturated solution as liquid phase is achieved by employing commercial software. The molecular composition of this solution is a required input parameter. The face specific diffusion coefficient of the solid （crystal surface） and liquid （solution） system is determined using the molecular dynamics procedure. The obtained diffusion coefficient is related to the specific face growth rate via the attachment energy of the pure morphology. The significant improvements are achieved in the morphology prediction because the investigation on the face growth rates in a complex growth environment （as multi-component solutions with additives） can be carried out based on the diffusion coefficients.

关键词： crystallization morphology molecular dynamics solution

Sphincter preservation for distal rectal cancer - a goal worth achieving at all costs?

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World journal of Gastroenterology 2011年第7期17卷 855-861页

作者： jürgen Mulsow Des c Winter Institute for clinical Outcomes Research and Education St. Vincent’s University Hospital

To assess the merits of currently available treatment options in the management of patients with low rectal cancer, a review of the medical literature pertaining to the operative and non-operative management of low rectal cancer was performed, with particular emphasis on sphincter preservation, oncological outcome, functional outcome, morbidity, quality of life, and patient preference. Low anterior resection (AR) is technically feasible in an increasing proportion of patients with low rectal cancer. The cost of sphincter preservation is the risk of morbidity and poor functional outcome in a significant proportion of patients. Transanal and endoscopic surgery are attractive options in selected patients that can provide satisfactory oncological outcomes while avoiding the morbidity and functional sequelae of open total mesorectal excision. In complete responders to neo-adjuvant chemoradiotherapy, a non-operative approach may prove to be an option. Abdominoperineal excision (APE) imposes a permanent stoma and is associated with significant incidence of perineal morbidity but avoids the risk of poor functional outcome following AR. Quality of life following AR and APE is comparable. Given the choice, most patients will choose AR over APE, however patients following APE positively appraise this option. In striving toward sphincter preservation the challenge is not only to achieve the best possible oncological outcome, but also to ensure that patients with low rectal cancer have realistic and accurate expectations of their treatment choice so that the best possible overall outcome can be obtained by each individual.

关键词： Rectal cancer Survival Local recurrence Morbidity Anorectal function Quality of life Patient preference