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  • 1
    ISSN: 1520-6041
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 728 (1994), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Notes: : Boolean algebras of regular closed sets, continuous functions, tame homeomorphisms, and Betti numbers are representative of the spectrum of topological tools that have been useful within computer aided geometric design (CAGD). The history of mathematics is rich with examples where the investigation of applications leads to extensions of existing theory. In that spirit, representative applications of topology to CAGD are presented. The intent is to present these examples in mathematical language within their larger mathematical context, so that other topologists might be encouraged to simultaneously enrich CAGD practice and mathematical theory. The authors' own research has benefited from such synergy, in that preparation of this article has resulted in new findings, which are presented herein.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Research in engineering design 4 (1992), S. 195-201 
    ISSN: 1435-6066
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Feature recognition can be characterized as enhancing the geometric database representation of a mechanical artifact to include some design intent. A number of feature recognition systems have successfully demonstrated the ability to capture such design knowledge. To determine if any such system could “scale-up” to large industrial part databases, it is appropriate to analyze the computational complexity of the recognition system-an issue which appears to have generally been ignored by the feature recognition community. A naive combinatorial analysis, generally applicable over all design domains, suggests that the combinatorial complexity would be exponential, hence intractable within most modern computing environments. Such a theoretical mathematical analysis ignores critical domain-specific engineering knowledge. It is argued that this theoretical potential for combinatorial explosion can be addressed by combining domain-specific mechanical engineering heuristics with a detailed combinatorial analysis. An example of such a heuristically guided combinatorial analysis will be presented for the domain of sheet-metal parts. This example presents combinatorial upper bounds which indicate that feature recognition upon large sheet-metal databases will be computationally tractable. In order to extend the analysis to other domains, it may be necessary to develop other domain-specific heuristics. However, the example presented should serve as a guide to incorporating design heuristics with combinatorial analysis.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Research in engineering design 4 (1992), S. 147-158 
    ISSN: 1435-6066
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract One of the fundamental axioms of concurrent engineering is that undertaking functional design without foreseeing the manufacturing process leads to production delays and increased costs. This widely accepted concurrent engineering principle is given a formal basis by development of a mathematical model for the conversion of a feature-based design representation to a manufacturing representation. Within the domain of thin-walled components, it is shown that the conversion to tooling cost representations can result in a discontinuous function when the sets of design and manufacturing representations have been formulated as topological spaces. This discontinuity formally reflects the folklore that a small design change can significantly increase product cost. The mathematical sophistication required within this model is suggestive of why manufacturability evaluations can be quite difficult.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Research in engineering design 5 (1993), S. 123-124 
    ISSN: 1435-6066
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Research in engineering design 4 (1992), S. 67-74 
    ISSN: 1435-6066
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Within mechanical computer-aided design (CAD), pattern-recognition techniques are fundamental to feature recognition. The use of neural net software as the pattern-recognition element depends upon encoding schemes which extract critical information from candidate geometric subsets. The trained memory can then determine if a particular candidate geometric subset corresponds to a feature of interest. Successful experiments with particular encoding schemes over a restricted class of features will be presented. Neural nets were chosen with the long-term view toward a feature-recognition architecture where the end-user could customize the domain of features that can be recognized. The training of the neural net memory would be achieved through a graceful graphics interface. Extensive programming and knowledge bases would be avoided. This envisioned architecture will be presented to provide a context for the encoding schemes.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-5001
    Keywords: 1D transient NOE ; Metropolis Monte Carlo simulations ; Flexibility of glycosidic linkages ; Maltose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary One-dimensional transient NOE build-up curves were measured for the synthetic disaccharide α-d-Fuc-(1→4)-β-d-GlcNAc 1 utilizing Gaussian shaped pulses. Simulated build-up curves from Metropolis Monte Carlo simulations were compared to the experimental data. Disaccharide 1 is structurally related to methyl β-d-maltoside in that it also contains an α-(1→4) linkage, and it has the same configuration of groups around the glycosidic linkage. Analysis of NOEs in methyl β-d-maltoside is restricted to those observed upon selective excitation of H1′ because of severe spectral overlap. The situation is different in 1 where 1H-NMR signals are well separated. Several interglycosidic NOEs were observed. The corresponding build-up curves allowed an accurate determination of the conformational preferences at the glycosidic linkage in 1. Comparison of experimental and theoretical NOE build-up curves showed clearly that rigid minimum-energy models cannot account for the experimental data. The best fit of experimental NOE build-up curves was obtained with theoretical curves from a 2×106 step Metropolis Monte Carlo simulation with the temperature parameter set at 1000 K. Finally, it was observed that only the interglycosidic NOE H5′/H6-pro-S significantly depends upon varying conformation distributions at the α-(1→4)-glycosidic linkage, induced by choosing different temperature parameters for the Metropolis Monte Carlo simulations.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-5001
    Keywords: Glycosidic linkage flexibility ; Branching in saccharides ; 1D NOE curves ; Metropolis Monte Carlo simulations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary A detailed conformational analysis was performed for the synthetic branched trisaccharide β-d-Man-NAc-(1→4)-[α-d-Glc-(1→3)]-l-Rha 1 which represents the repeating unit of the O-antigenic polysaccharide of Aeromonas salmonicida. The study was based on 26 experimental NOE curves from 1D transient NOE experiments, employing Gaussian-shaped inversion pulses at 600 MHz. Eight of the NOE curves were interglycosidic and thus useful for an analysis of glycosidic linkage orientations. Metropolis Monte Carlo (MMC) simulations and minimum-energy calculations with the program GEGOP were used to obtain theoretical NOE curves which were compared to the experimental ones. MMC simulations with different temperature parameters of 310, 600, 900 and 2000 K allowed identification of NOEs which are sensitive towards different conformation distributions-not only different conformations-at both glycosidic linkages in 1. A comparison of trisaccharide 1 with the constituent disaccharides β-d-ManNAc-(1→4)-l-Rha 2 and α-d-Glc-(1→3)-l-Rha 3 revealed effects of branching on glycosidic linkage flexibility. A quantitative evaluation was facilitated by the introduction of entropy-related flexibility parameters. Our study indicates a notable restriction of flexibility, especially at the (1→3) linkage in 1. Although overall flexibility in 1 is reduced as compared to the constituent disaccharides 2 and 3, it cannot be neglected altogether. In summary, combined transient NOE experiments and MMC simulations provide a simple approach to analyse glycosidic linkage flexibility.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Research in engineering design 6 (1994), S. 223-233 
    ISSN: 1435-6066
    Keywords: Design theory ; Features ; Topology ; Manufacturing ; Design for manufacturing (DFM)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Design for manufacturing (DFM) is a methodology that requires the use of specific manufacturing information at all stages of design. The method relies on a collection of informal and often controversial principles that seem to have eluded the benefits of formal analysis. The transition from design to manufacturing can be modeled as a mathematical mapping, and it has been previously shown how the discontinuity of this mapping formally captures the folklore that “small design changes can lead to significantly increased manufacturing cost”. We study the properties of the transition map in the presence of design and manufacturing variations, and show that its continuity is closely related to the structure of design and manufacturing topological spaces. The main result of this paper establishes conditions on these spaces under which design for manufacturing cannot be described by any continuous transition map. In practical terms, our study reveals the limitations of many DFM systems and approaches in their ability to relate design and manufacturing knowledge, and explains these limitations in terms of a basic incompatibility between the underlying design and manufacturing representations. We discuss how our model applies to DFM relative to traditional manufacturing methods (such as casting and stamping) and we speculate what changes might occur for alternative manufacturing technologies (such as electrical discharge machining (EDM), stereolithography, laser machining, and particle deposition).
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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