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  • 1
    Electronic Resource
    Electronic Resource
    Modelling of transport phenomena in laser welding of dissimilar metals (2001)
    Bradford : Emerald
    International journal of numerical methods for heat & fluid flow 11 (2001), S. 156-174 
    Details
    ISSN: 0961-5539
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The transport phenomena (heat transfer, fluid flow and species distribution) are numerically modelled for the case of laser welding of dissimilar metals. The model involves convection in the weld pool along with melting and mixing. The associated metallurgical phenomenon is an extremely complex one, and the present work is a preliminary attempt to model the process after making suitable assumptions. The numerical study is performed using a pressure based finite volume technique after making appropriate modifications to the algorithm to include the associated phase change processes and dissimilarity in the metal properties. The phase change process is modelled using an enthalpy-porosity technique, while the dissimilar metal properties are handled using appropriate mixture theories. As a case study, we have used dissimilar couples of copper-nickel. It is observed that the weld pool shape becomes asymmetric even when the heat source is symmetrically applied on the two metals forming the couple. As the weld pool develops, the side melting earlier is found to experience more convection and better mixing. Corresponding experiments are performed using the same parameters as in the computations, showing a good qualitative agreement between the two results. A scale analysis is performed to predict the time scale of initiation of melting of each metal. The scale-analysis predictions show a good agreement with the numerical results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/09615530110381575
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  • 2
    Electronic Resource
    Electronic Resource
    Radiation in boundary layer flow of an absorbing, emmiting and anisotropically scattering fluid (2000)
    Bradford : Emerald
    International journal of numerical methods for heat & fluid flow 10 (2000), S. 530-540 
    Details
    ISSN: 0961-5539
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Radiative heat transfer in the laminar boundary layer flow of an absorbing, emitting and anisotropically scattering gray fluid over a flat plate, with the surface of the plate reflecting radiation in diffuse-cum-specular fashion is analyzed. The discrete ordinates method is used to model the radiative transfer. The governing dimensionless momentum and energy equations, in the form of a partial differential system, are solved by a finite difference method. The effect of various parameters like, emittance, the degree of anisotropy in scattering, scattering albedo and the nature of surface reflection on the total heat flux from the plate to the fluid are studied and results are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/09615530010338204
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  • 3
    Electronic Resource
    Electronic Resource
    Modelling of turbulent transport in arc welding pools (2003)
    Bradford : Emerald
    International journal of numerical methods for heat & fluid flow 13 (2003), S. 7-30 
    Details
    ISSN: 0961-5539
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this paper, we present a modified k-? model capable of addressing turbulent weld-pool convection in the presence of a continuously evolving phase-change interface during a gas tungsten arc welding (GTAW) process. The phase change aspects of the present problem are addressed using a modified enthalpy-porosity technique. The k-? model is suitably modified to account for the morphology of the solid-liquid interface. The two-dimensional mathematical model is subsequently utilised to simulate a typical GTAW process with high power, where effects of turbulent transport can actually be realised. Finally, we compare the results from turbulence modelling with the corresponding results from a laminar model, keeping all processing parameters unaltered. The above comparison enables us to analyse the effects of turbulent transport during the arc welding process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/09615530310456741
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  • 4
    Electronic Resource
    Electronic Resource
    Nondestructive characterization of oxygen-ion-implanted silicon- on-insulator using multiple-angle ellipsometry (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 2754-2756 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Silicon-on-insulator formed by high-dose and high-energy oxygen ion implantation in silicon, called SIMOX (separation by implanted oxygen), has been characterized nondestructively by multiple-angle ellipsometry using a He–Ne laser at 632.8 nm. A multilayered model exhibiting two interlayers, one between the top silicon layer and the buried oxide layer and the other between the buried oxide and the substrate silicon, offers a simple representation of SIMOX. The difference between low-temperature furnace anneal (1150 °C) and an additional high-temperature rapid thermal anneal (1150+1350 °C) on as-implanted wafers is shown by the better agreement between the theoretical model and the experimental results for the high-temperature annealed SIMOX sample.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341620
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  • 5
    Electronic Resource
    Electronic Resource
    Poly(sulfide sulfone) by activated nucleophilic displacement polymerization (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 211 (1993), S. 79-87 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein Poly(sulfidsulfon) wurde durch aktivierte nucleophile Substitution der Nitrogruppen von Bis(4-nitrophenyl)sulfon mit wasserfreiem Natriumsulfid bei 200 C in N-Methyl-2-pyrrolidon (NMP) hergestellt. Das Polymere löst sich in NMP, Dimethylformamid (DMF), Dimethylsulfoxid und anderen hochpolaren Lösungsmitteln. Das Molekulargewicht des Polymeren mit einer inhärenten Viskosität von 15 ml/g bei 30°C in DMF wurde mittels 1H-NMR-Spektroskopie zu Mn = 2500 bestimmt. Die Glastemperatur liegt bei ca. 73°C; der Veraschungsrückstand bei 600°C in Luft beträgt 36%, der Sauerstoffindex (LOI) ca. 37.
    Notes: A poly(sulfide sulfone) was synthesized by activated nucleophilic displacement reaction between bis(4-nitrophenyl)sulfone and anhydrous sodium sulfide at 200°C in N-methyl-2-pyrrolidone (NMP). The polymer is soluble in NMP, dimethylformamide, dimethylsulfoxide and other highly polar solvents. The molecular weight of the polymer (M̄n = 2.500) having an inherent viscosity of 15 mL/g at 30°C in DMF was determined by 1H-NMR spectroscopy. The polymer has a glass transition at approx. 73°C and char residue of 36% at 600°C in air. The limiting oxygen index of the polymer is ∼37.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052110107
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  • 6
    Electronic Resource
    Electronic Resource
    A novel synthesis of poly(pyridinylene sulfide) by nucleophilic displacement polymerization (1992)
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 13 (1992), S. 505-509 
    Details
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1992.030131105
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  • 7
    Electronic Resource
    Electronic Resource
    Mixed convection about a non-isothermal vertical surface in a porous medium (1988)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 8 (1988), S. 723-735 
    Details
    ISSN: 0271-2091
    Keywords: Porous medium ; Mixed convection ; Nonisothermal vertical surface ; Boundary layer type analysis ; Perturbation technique ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The problem of mixed convection about non-isothermal vertical surfaces in a saturated porous medium is analysed using boundary layer approximations. The analysis is made assuming that the surface temperature varies as an arbitrary function of the distance from the origin. A perturbation technique has been applied to obtain the solutions. Using the differentials of the wall temperature, which are functions of distance along the surface, as perturbation elements, universal functions are derived for various values of the governing parameter Gr/Re. Both aiding and opposing flows are considered. The universal functions obtained can be used to estimate the heat transfer and fluid velocity inside the boundary layer for any type of wall temperature variation. As a demonstration of the method, heat transfer results have been presented for the case of the wall temperature varying as a power function of the distance from the origin. The results have been studied for various combinations of the parameters Gr/Re and the power index m, taking both aiding and opposing flows into consideration. On comparing these results with those obtained by a similarity analysis, the agreement is found to be good.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650080608
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  • 8
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    Numerical studies on columnar-to-equiaxed transition in directional solidification of binary alloys (2009)
    Springer
    Details
    Publication Date: 2009-05-26
    Print ISSN: 0022-2461
    Electronic ISSN: 1573-4803
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Springer
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  • 9
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    Effect of semi-solid heat treatment on elevated temperature plasticity of 304L stainless steel (2016)
    Springer
    Details
    Publication Date: 2016-01-21
    Print ISSN: 0022-2461
    Electronic ISSN: 1573-4803
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Springer
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  • 10
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    Modeling growth of hydrogen bubbles in aluminum castings using the level-set method (2009)
    Elsevier
    Details
    Publication Date: 2009-07-01
    Print ISSN: 1359-6462
    Electronic ISSN: 1872-8456
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Elsevier
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