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  • 1
    Electronic Resource
    Electronic Resource
    Finite element modelling of heat transfer through permeable cracks in hydrothermal systems with upward throughflow (2001)
    Bradford : Emerald
    Engineering computations 18 (2001), S. 996-1011 
    Details
    ISSN: 0264-4401
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Technology
    Notes: We use the finite element method to model the heat transfer phenomenon through permeable cracks in hydrothermal systems with upward throughflow. Since the finite element method is an approximate numerical method, the method must be validated before it is used to solve any new kind of problem. However, the analytical solution, which can be used to validate the finite element method and other numerical methods, is rather limited in the literature, especially for the problem considered here. Keeping this in mind, we have derived analytical solutions for the temperature distribution along the vertical axis of a crack in a fluid-saturated porous layer. After the finite element method is validated by comparing the numerical solution with the analytical solution for the same benchmark problem, it is used to investigate the pore-fluid flow and heat transfer in layered hydrothermal systems with vertical permeable cracks. The related analytical and numerical results have demonstrated that vertical cracks are effective and efficient members to transfer heat energy from the bottom section to the top section in hydrothermal systems with upward throughflow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/02644400110404000
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  • 2
    Electronic Resource
    Electronic Resource
    Theoretical and numerical analysis of large-scale heat transfer problems with temperature-dependent pore-fluid densities (2005)
    Bradford : Emerald
    Engineering computations 22 (2005), S. 232-252 
    Details
    ISSN: 0264-4401
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Technology
    Notes: Purpose - In many scientific and engineering fields, large-scale heat transfer problems with temperature-dependent pore-fluid densities are commonly encountered. For example, heat transfer from the mantle into the upper crust of the Earth is a typical problem of them. The main purpose of this paper is to develop and present a new combined methodology to solve large-scale heat transfer problems with temperature-dependent pore-fluid densities in the lithosphere and crust scales. Design/methodology/approach - The theoretical approach is used to determine the thickness and the related thermal boundary conditions of the continental crust on the lithospheric scale, so that some important information can be provided accurately for establishing a numerical model of the crustal scale. The numerical approach is then used to simulate the detailed structures and complicated geometries of the continental crust on the crustal scale. The main advantage in using the proposed combination method of the theoretical and numerical approaches is that if the thermal distribution in the crust is of the primary interest, the use of a reasonable numerical model on the crustal scale can result in a significant reduction in computer efforts. Findings - From the ore body formation and mineralization points of view, the present analytical and numerical solutions have demonstrated that the conductive-and-advective lithosphere with variable pore-fluid density is the most favorite lithosphere because it may result in the thinnest lithosphere so that the temperature at the near surface of the crust can be hot enough to generate the shallow ore deposits there. The upward throughflow (i.e. mantle mass flux) can have a significant effect on the thermal structure within the lithosphere. In addition, the emplacement of hot materials from the mantle may further reduce the thickness of the lithosphere. Originality/value - The present analytical solutions can be used to: validate numerical methods for solving large-scale heat transfer problems; provide correct thermal boundary conditions for numerically solving ore body formation and mineralization problems on the crustal scale; and investigate the fundamental issues related to thermal distributions within the lithosphere. The proposed finite element analysis can be effectively used to consider the geometrical and material complexities of large-scale heat transfer problems with temperature-dependent fluid densities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/02644400510585501
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  • 3
    Electronic Resource
    Electronic Resource
    An upper-bound solution to the problem of plate tearing (1995)
    Springer
    Journal of marine science and technology 1 (1995), S. 46-51 
    Details
    ISSN: 1437-8213
    Keywords: plate tearing ; rupture ; upper-bound solution ; plasticity ; grounding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract An upper-bound solution is derived for the problem of the tearing of a metal plate by a rigid wedge. These newly proposed formulas, with no fracture parameters being used, provide an explanation to the problem of plate tearing, which is a phenomenon that occurs in the process of ship grounding. This paper starts with the proposition of a new kinematic model. Based on the fact that in many experiments there is no evidence of cracks extending ahead of the wedge tip, this new kinematic model assumes no separation between the wedge tip and the crack tip in the plate. Another characteristic of this model is that out-of-plane deformation is assumed for the region around the tip, which correlates well with the experimental observations. Rupture of the metal plate is assumed to occur ahead of the wedge tip due to ductile failure. In the case of longitudinally stiffened panels, an equivalent plate thickness is employed to take the effect of stiffeners into consideration. From comparisons of calculations with existing experimental results, it is clear that the present upper-bound solution is effective in predicting resistance force and energy absorption in the process of plate tearing, and that it can provide predictions that are close to those obtained from empirical formulas and from the theoretical formulas of Wierzbicki and Thomas, who assume that cracks run ahead of the wedge tip.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01240012
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  • 4
    Electronic Resource
    Electronic Resource
    Numerical modelling of double diffusion driven reactive flow transport in deformable fluid-saturated porous media with particular consideration of temperature-dependent chemical reaction rates (2000)
    Bradford : Emerald
    Engineering computations 17 (2000), S. 367-385 
    Details
    ISSN: 0264-4401
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Technology
    Notes: Numerical methods are used to solve double diffusion driven reactive flow transport problems in deformable fluid-saturated porous media. In particular, the temperature dependent reaction rate in the non-equilibrium chemical reactions is considered. A general numerical solution method, which is a combination of the finite difference method in FLAC and the finite element method in FIDAP, to solve the fully coupled problem involving material deformation, pore-fluid flow, heat transfer and species transport/chemical reactions in deformable fluid-saturated porous media has been developed. The coupled problem is divided into two sub-problems which are solved interactively until the convergence requirement is met. Owing to the approximate nature of the numerical method, it is essential to justify the numerical solutions through some kind of theoretical analysis. This has been highlighted in this paper. The related numerical results, which are justified by the theoretical analysis, have demonstrated that the proposed solution method is useful for and applicable to a wide range of fully coupled problems in the field of science and engineering.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/02644400010334801
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  • 5
    Electronic Resource
    Electronic Resource
    Finite element modelling of reactive fluids mixing and mineralization in pore-fluid saturated hydrothermal/sedimentary basins (2002)
    Bradford : Emerald
    Engineering computations 19 (2002), S. 364-387 
    Details
    ISSN: 0264-4401
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Technology
    Notes: We present the finite element simulations of reactive mineral-carrying fluids mixing and mineralization in pore-fluid saturated hydrothermal/sedimentary basins. In particular we explore the mixing of reactive sulfide and sulfate fluids and the relevant patterns of mineralization for lead, zinc and iron minerals in the regime of temperature-gradient-driven convective flow. Since the mineralization and ore body formation may last quite a long period of time in a hydrothermal basin, it is commonly assumed that, in the geochemistry, the solutions of minerals are in an equilibrium state or near an equilibrium state. Therefore, the mineralization rate of a particular kind of mineral can be expressed as the product of the pore-fluid velocity and the equilibrium concentration of this particular kind of mineral. Using the present mineralization rate of a mineral, the potential of the modern mineralization theory is illustrated by means of finite element studies related to reactive mineral-carrying fluids mixing problems in materially homogeneous and inhomogeneous porous rock basins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/02644400210423990
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  • 6
    Electronic Resource
    Electronic Resource
    Recent Developments of Magnetic SMA (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Advances in science and technology Vol. 59 (Sept. 2008), p. 1-10 
    Details
    ISSN: 1662-0356
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Natural Sciences in General , Technology
    Notes: In the shape memory alloys (SMAs) the thermal triggering induces reversible dimensionalchange by the phase transformation – these materials may also be ferriorferromagnetic, however,here only the ferromagnetic SMAs are discussed. In certain SMAs the austenitemartensitephasetransformation is influenced by the magnetic field as either austenite or martensite is promoted by thefield and this is exploited for the dimensional changes. However, in the magnetic shape memory(MSM) alloys no phase transformation occurs as the remarkable dimensional changes take place bythe twin variant changes in the martensitic phase activated by the external magnetic field at constanttemperature. In addition to the phase transformation or magnetic shape memory effect, the appliedmagnetic field may also result in the conventional magnetostriction (MS), enhance the superelasticity(magneticfieldassistedsuperelasticity MFAS) or induce the giant magnetocaloric effect (GMCE).Certain alloys such as NiMnGamay even be multifunctional showing more than one of theseeffects. The present paper gives an overview of the different types of the magnetically activated SMAalloys, their properties as well as their potentials for applications in the frameworks of the recentstudies
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/42/transtech_doi~10.4028%252Fwww.scientific.net%252FAST.59.1.pdf
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesis of acrylate functional telechelic poly(lactic acid) oligomer by transesterification (2000)
    Springer
    Journal of materials science 11 (2000), S. 505-510 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The controlled synthesis of low molecular weight (Mn from 700 to 10 000 g/mol) poly(lactic acid) (PLA) telechelic oligomers end-capped with acrylate groups by a one-step reaction was investigated. A transesterification reaction was carried out in solution with a Lewis acid titanium catalyst using a high molecular weight PLA and a low molar mass diacrylate. End-functionalization was demonstrated by proton NMR spectroscopy which was also used for quantitative analysis and number average molecular weight determination using the ratio between the acrylic chain ends to the main groups of poly(D,L-lactic acid). The formation of low molar mass oligomers from high molecular weight poly(lactic acid) was verified by gel permeation chromatography. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry showed that the above oligomerization was accompanied by the formation of cyclic compounds. By these means the feasability of a simple transesterification for a controlled synthesis of telechelic oligomers with molecular mass being a function of the added amount of diacrylate has been demonstrated. The glass transition temperatures of the elaborated oligomers varied from −35 to −5 °C. Subsequent thermal crosslinking was performed using benzoyl peroxide which enabled the formation of amorphous networks with Tg’s close to the body temperature of 40 °C. Upon storage in a humid atmosphere the initially fairly hard and brittle networks became, due to hydrolysis, progressively more flexible thus demonstrating the potential biodegradability of these materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008948325177
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  • 8
    Electronic Resource
    Electronic Resource
    Static analysis of bevel gears using finite element method (1998)
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 14 (1998), S. 367-380 
    Details
    ISSN: 1069-8299
    Keywords: bevel gears ; instantaneous mesh stiffness ; load distribution ; FEM ; Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A new method, namely the normal stiffness matrix along contact line (NSMACL) method, for analysing gears, is proposed. The new method uses the static coagulation technique to coagulate the global stiffness matrix of all contact teeth into a lower-order NSMACL. By adding the concert deformation condition and equilibrate condition, the relation between the torque acting on the driving gear and the load along the contact lines can be established, and the contact stress and gear tooth deformation can also be obtained. Three-dimensional (3D) highly accurate solid models of gear teeth have been established, in which the contact range and the whole finite element model can be automatically adjusted with the change of meshing process. Spur and helical bevel gears can be analysed using these models. Example models and results are presented. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    A dynamic programming method for analysis of bridges under multiple moving loads (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 1265-1282 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A dynamic programming (DP) method is presented for analysis of statically determinate and indeterminate bridges subjected to moving loads such as those specified by the American Association of State Highway and Transportation Officials (AASHTO) specifications. These loads consist of uniform lane loading, two-axle truck loading and two-axle truck plus one-axle semitrailer loading. The solution of the DP problem is based on the use of influence line diagrams and extremum functions. Recurrence formulae have been developed for various types of AASHTO live loads. The procedure presented in this article is quite general and can be applied to any type of structures with linear behaviour and any type of moving loads. Six examples are presented: a simply-supported beam, a simply-supported Pratt truss, an arch bridge, a continuous Pratt truss, a continuous frame and a cable-stayed bridge.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620280604
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  • 10
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    Study on the Explicit Formula of the Triangular Flat Shell Element Based on the Analytical Trial Functions for Anisotropy Material (2013)
    Hindawi
    Details
    Publication Date: 2013-09-17
    Description: This paper presents a novel way to formulate the triangular flat shell element. The basic analytical solutions of membrane and bending plate problem for anisotropy material are studied separately. Combining with the conforming displacement along the sides and hybrid element strategy, the triangular flat shell elements based on the analytical trial functions (ATF) for anisotropy material are formulated. By using the explicit integral formulae of the triangular element, the matrices used in proposed shell element are calculated efficiently. The benchmark examples showed the high accuracy and high efficiency.
    Print ISSN: 1024-123X
    Electronic ISSN: 1563-5147
    Topics: Mathematics , Technology
    Published by Hindawi
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