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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 98 (1994), S. 5778-5783 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    The international journal of advanced manufacturing technology 16 (2000), S. 370-375 
    ISSN: 1433-3015
    Keywords: Keywords: Die design optimisation; Hybrid intelligent system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Die design is heavily experience based and the die design process is an iterative procedure of trial and error in order to obtain a final die design for the successful manufacture of stampings. Most automotive industries use internal guidelines and past experience for die design. Even though powerful computer-aided design systems are being used in automotive industry, the lack of adequate analysis tools at the initial die geometry design stage hinders the die manufacturing process, and also necessitates lead times of the order of 5–30 weeks [1]. At the concept design stage, and during the initial die development process, the variations in geometry and process conditions are so large that it is prohibitively expensive to use 3D finite element analysis. The complexity of die design heuristic knowledge hinders the development and application of knowledge-based systems. Hybrid intelligent systems are computer programs in which at least one of the constituent models simulates intelligent behaviour [2]. These models could be knowledge-based systems, artificial neural networks, fuzzy logic systems, etc. In this approach both artificial neural networks, knowledge-based systems and finite-element analysis (FEA) for modelling the design process are used. A simulation-based design approach [3] for the die design process is followed. Artificial neural networks (ANNs) are preliminary design tools which indicate the formability of the component geometry, for the selected process and material conditions. The ANN module is trained from FEA results for a generic set of component geometries, process conditions, and material properties. The final die design validation is carried out by FEA. The intelligent frame-work incorporates rules for material selection, process parameter selection and their modification. Component geometry is a critical parameter which affects the manufacturability of the given part. Hence, an intelligent geometry handling module, which automatically modifies and optimises the geometry of the designed die, is implemented in the present system. Knowledge-based blackboard architecture is used for the integration of various analysis models such as CAD, FEA, and ANN, as an intelligent framework for die design [4]. The hybrid intelligent system provides an integrated decision support environment for simulation and analysis of the forming process, both during the initial die design phase and during the die tryout phase. The hybrid intelligent systems approach supports the capability for automatic evaluation of prospective die design for manufacturability, and performs automatic modification of design inputs. Applications of the hybrid intelligent system for die design are described together with a comparison with shop floor data.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Computational mechanics 25 (2000), S. 358-375 
    ISSN: 1432-0924
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  Various boundary element method (BEM) based approaches to solve crack problems are discussed. The displacement method, J-integral method and the modified crack closure integral (MCCI) method for the evaluation of the stress intensity factors (SIFs) are reviewed. Effects of partial and total modelling of singularities on the accuracy of the results have been presented. Elements capable of partial and total modelling of the wellknown square root singularities, variable order singularities, neighbouring variable order singularities, etc., are also reviewed. Case studies are included to illustrate the effectiveness of the various methods of calculation of the SIFs and the performance of the special elements.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Computational mechanics 7 (1991), S. 329-339 
    ISSN: 1432-0924
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A formulation for incorporating two singular points (TSP) of variable orders in a single finite element is presented. Though the element does not satisfy any of the convergence criterion, its performance is found to be good, which has been demonstrated by considering number of examples on kinked cracks. In each case only one such element is incorporated in the whole discretization. These examples illustrate the usefulness of the element to analyse kinked cracks of various sizes and shapes and subjected to different loading and boundary conditions. Computed J-integrals are compared with analytical solutions, wherever possible, and the accuracy appears quite good. Effect of size of the element on, and the path independence of, J are also examined.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-1561
    Keywords: (9z,11Z) ; (9E.11E) ; (9E,11Z) ; (9Z,11E)-9 ; 11-Hexadecadienals ; (9E)-hexadecen-11-yn-1-yl acetate ; syntheses ; aldehydes ; ester ; conjugated dienes ; dienals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The title compounds were prepared by six different routes, and recommendations are given for the more convenient procedures in laboratory-scale syntheses. Modifications in the literature preparations of the 9E,11E and 9E,11Z isomers are described. Baseline separation of a prepared mixture of all four isomers of the (9Z, 11Z), (9E, 11E), (9E, 11Z), and (9Z, 11E)-9,11-hexadecadienals was achieved using GC methods with standard capillary columns. [13C]NMR spectroscopy of the alkene carbon atoms clearly differentiates between theZ,Z, E,E and eitherE,Z orZ,E isomers of the precursor dienols and thus of the dienals.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    International journal of fracture 17 (1981), S. 477-482 
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Résumé On étudie de manière analytique la distribution des pressions nécessaires à l'ouverture d'une fissure de Griffith dans un solide orthotrope de forme prescrite. L'analyse est appliquée au cas particulier de formes d'ouverture de fissure pour lesquelles les résultats numériques sont présentés de manière graphique.
    Notes: Abstract The distribution of pressure necessary for opening a Griffith crack to a prescribed shape in an orthotropic solid, is studied analytically. The analysis is applied to a particular class of crack opening shapes for which numerical results are presented graphically.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    The international journal of advanced manufacturing technology 16 (2000), S. 376-381 
    ISSN: 1433-3015
    Keywords: Keywords: Artificial neural network; Springback; Vee air bending
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Springback is a serious problem in the air vee bending process because of its inconsistency. An on-line tool to control spring-back is more reliable than an analytical model which might not be able to control the stroke of the machine in real-time. Therefore, one might resort to adaptive control or use an artificial neural network (ANN) trainer, either using experimental data or analytical predictions (or both), and use it for real-time control of the machine tool. The inconsistency in springback is then reduced to within acceptable limits. Adaptive control would need several strokes to complete the job, but it is envisaged that the job could be completed in a single stroke with the ANN. The present paper discusses the development of an ANN which can be used to train and later to predict the springback, as well as the punch travel, to achieve the desired angle in a single stroke in an air vee bending process.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 268 (1990), S. 901-910 
    ISSN: 1435-1536
    Keywords: Copolyamides ; synthesis ; cross-linking ; thermal analysis ; thermaldegradation ; solubility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Some new flexible and cross-linkable copolyimides containing rubbery unsaturated aliphatic chain moiety (CPLA) were prepared by low temperature polycondensation betweenm-phenylene diamine,bis- 3(4 carboxy phthalimido) benzene, and liquidα,Ω bis [2-(4 piperazinyl) ethyl aminocarbonyl] poly-(butadiene-co-acrylonitrile) (ATBN) in (DMAC) solution. The effect of rubbery aliphatic moiety in these copolyimides on the polymer properties has been reported. A comparative study on the properties of these copolyimides (CPLA) with the mixture of ATBN and a low molecular-weight cross-linkable copolyimide possessing the same molecular structure as the aromatic moiety of CPLA polymers has been made.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 272 (1994), S. 1203-1207 
    ISSN: 1435-1536
    Keywords: Polyazoxyphosphonate ; XPS-L01 ; 31P-NMR ; Flame retardancy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A new polyazoxyphosphonate was synthesized by reaction of 4-4′-dihydroxyazoxybenzene and dichlorophenyl phospine oxide by interfacial polycondensation using a phase transfer catalyst. The polymer was characterized and the results obtained by various analytical techniques indicate that it is mostly amorphous, low molecular weight and soluble in organic solvents such as DMF, DMAC, NMP, etc. The high char residue (∼40%) and limiting oxygen index indicate flame retardancy of the polymer which is due to phosphorus. Thermal stability of this polymer is moderate. TheT g appears to be at 152°C.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    International journal of theoretical physics 22 (1983), S. 363-368 
    ISSN: 1572-9575
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The paper presents a static spherically symmetric viscous fluid solution of Einstein field equation, assuming an equation of statep=(γ−1)ρ. Though static, the solution has expansion, shear, and acceleration and can explain cosmological red shift. Also it has a particle horizon. The singularity at the origin and larger viscosity make it unfit to represent a real universe.
    Type of Medium: Electronic Resource
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