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  • Articles  (17,405)
  • Springer  (14,167)
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  • 1995-1999
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  • 1993  (17,405)
  • Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics  (10,309)
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  • Articles  (17,405)
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  • 1995-1999
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  • 1
    Electronic Resource
    Electronic Resource
    On the control of an infinite capacity storage system (1993)
    Springer
    Stochastic environmental research and risk assessment 7 (1993), S. 195-204 
    Details
    ISSN: 1436-3259
    Keywords: Infinite dam ; resolvent operator ; Lévy process ; integrated Markov chain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract We consider an infinite-capacity storage system. The cumulative input to the system is assumed to be either (a) a non-decreasing Lévy process or (b) an integrated continuous-time Markov chain. Reward accumulates at a rate depending on the instantaneous release rate. The objective is to choose the release rule in such a way as to maximize the expected total discounted return. In this note we show how to determine the expected discounted return when the release rate is either constant or a linear function of the content.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01585598
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  • 2
    Electronic Resource
    Electronic Resource
    Stochastic perturbation analysis of groundwater flow. Spatially variable soils, semi-infinite domains and large fluctuations (1993)
    Springer
    Stochastic environmental research and risk assessment 7 (1993), S. 213-239 
    Details
    ISSN: 1436-3259
    Keywords: Stochastic hydrology ; perturbation ; random fields ; graph theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract As is well known, a complete stochastic solution of the stochastic differential equation governing saturated groundwater flow leads to an infinite hierarchy of equations in terms of higher-order moments. Perturbation techniques are commonly used to close this hierarchy, using power-series expansions. These methods are applied by truncating the series after a finite number of terms, and products of random gradients of conductivity and head potential are neglected. Uncertainty regarding the number or terms required to yield a sufficiently accurate result is a significant drawback with the application of power series-based perturbation methods for such problems. Low-order series truncation may be incapable of representing fundamental characteristics of flow and can lead to physically unreasonable and inaccurate solutions of the stochastic flow equation. To support this argument, one-dimensional, steady-state, saturated groundwater flow is examined, for the case of a spatially distributed hydraulic conductivity field. An ordinary power-series perturbation method is used to approximate the mean head, using second-order statistics to characterize the conductivity field. Then an interactive perturbation approach is introduced, which yields improved results compared to low-order, power-series perturbation methods for situations where strong interactions exist between terms in such approximations. The interactive perturbation concept is further developed using Feynman-type diagrams and graph theory, which reduce the original stochastic flow problem to a closed set of equations for the mean and the covariance functions. Both theoretical and practical advantages of diagrammatic solutions are discussed; these include the study of bounded domains and large fluctuations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01585600
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  • 3
    Electronic Resource
    Electronic Resource
    A KBES for integrated engineering (1993)
    Springer
    Engineering with computers 9 (1993), S. 1-16 
    Details
    ISSN: 1435-5663
    Keywords: Blackboard ; Expert systems ; Industrial structures ; Integrated engineering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The expert process of engineering involves application of knowledge fundamental to the engineering process at one end, and of compiled knowledge in the form of heuristics gained through many years of experience at the other. Developments in Artificial Intelligence have made the process of computer aided engineering richer by enabling the simulation of this human process of engineering, which until now has been difficult to capture. Knowledge Based Expert Systems (KBES) in engineering developed so far have addressed only narrow domains of the entire process of engineering. This paper discusses a KBES shell (IES) that integrates various AI technologies, which makes it possible to implement new problem-solving strategies required for efficient handling of the entire engineering process. Issues in the integrated process of engineering are discussed first, in order to evolve a specification for the shell. The blackboard architecture is shown to be the ideal backbone for such a shell. The details of inference techniques, the knowledge based backtracking mechanism and the DBMS used in the IES are presented. The application of the IES is demonstrated using the domain of integrated engineering of steel industrial structures as an example. This application encompasses the engineering activities of conceptual design, detailed design, documentation and construction planning.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01198249
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  • 4
    Electronic Resource
    Electronic Resource
    Structural synthesis under manufacturability constraints: A CAD system for the design of injection-molded product housings (1993)
    Springer
    Research in engineering design 5 (1993), S. 185-201 
    Details
    ISSN: 1435-6066
    Keywords: Computer-aided design ; Design for manufacture ; Injection molding ; Structural synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract We describe a computer-aided design system that automatically constructs the internal functional surface shapes of plastic injection molded product housings. Fundamental manufacturability constraints related to the geometry of injection mold parting and the solidification of molten plastic are identified. These constraints are embodied in structural synthesis operators that create the internal shapes given a set of functional requirements. An implementation, which is integrated with a system that automatically designs the external visible surface of the housing, is discussed. Algorithms for the structural synthesis operators are provided along with sample output demonstrating their operation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01608362
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  • 5
    Electronic Resource
    Electronic Resource
    A meta-model for mechanical products based upon the mechanical design process (1993)
    Springer
    Research in engineering design 5 (1993), S. 140-160 
    Details
    ISSN: 1435-6066
    Keywords: Design documentation ; Features ; Functional modeling ; Product modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This paper describes preliminary work toward the develoment of a framework and a system for modeling the “meta-physical” information of mechanical products. Meta-physical information is that information which describes the nature or reason for existence of objects in the physical product model. Such information includes product and feature functionality, design intent, relations, constraints and viewpoint-dependent definitions. This effort has resulted in an initial model structure and a prototype system. The product model consists of a meta-physical product model with attached physical product models containing, among other information, geometry, dimensions, tolerances, and features. The content and structure of the product model correspond directly to the information used and produced during the mechanical design process. The prototype system integrates a solid modeler, a feature modeler, a dimension and tolerance modeler, and a meta-physical modeler. This paper provides an overview of the meta-model structure, usage and potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01608360
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  • 6
    Electronic Resource
    Electronic Resource
    Announcements (1993)
    Springer
    Research in engineering design 5 (1993), S. 238-238 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF01608365
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  • 7
    Electronic Resource
    Electronic Resource
    Constraint-based design using an operational approach (1993)
    Springer
    Research in engineering design 5 (1993), S. 202-217 
    Details
    ISSN: 1435-6066
    Keywords: Constraint-based design ; Feature modeling ; Geometric reasoning ; Graph grammar ; Knowledge-based inference
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Constraint-based design, which explicitly represents and operates upon constraints, has been recognized as a promising tool for achieving intelligent support of design, particularly the design of mechanical parts or assemblies. It is essential for a constraint-based system to realize the constraint-solving capability. This paper presents an operational approach to constraint solving using incremental feature operations. The approach is based on an operational interpretation of constraints, i.e. the constraint satisfaction is carried out in terms of operations incrementally. A grammatic formalism is used for operational modeling of constraints. Each graph production within a graph grammar corresponds to an operation or a sequence of operations designated for constraint satisfaction that is related to a rule or a procedure. Therefore, a constraint satisfaction process can be represented by a graph grammar parsing process. The operation sequence is planned by graph grammar parsing and invocation of the related rules or procedures. Constraints are then evaluated by invoking the sequenced operations. Features are introduced as higher-level abstractions into the geometric constraints network. This enables reasoning about design validation from topological and manufacturing views.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01608363
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  • 8
    Electronic Resource
    Electronic Resource
    Announcements (1993)
    Springer
    Research in engineering design 5 (1993), S. 240-240 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF01608367
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis of 1,2-bis(2-oxazolinyl-2)ethane and its application as chain extender for poly(ethylene terephthalate) (1993)
    Springer
    Polymer bulletin 30 (1993), S. 13-18 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The reaction of ethanolamine (EA) with nitriles is a general route to prepare oxazolines. However, in case of vicinal nitrile groups, cyclic imidines are formed. It is shown, that succinonitrile gives with EA mainly 1-(hydroxyethyl)-2,5-bis-(hydroxyethylimine) azacyclopentane (= triol). The corresponding 1,2 bis-(2-oxazolinyl-2) ethane (BOXE) is formed by heating the triol. BOXE can be used as chain extender of poly(ethylene terephthalate) (PET). If PET is heated with BOXE at 270 °C the viscosity increases first. However, on prolonged heating the viscosity decreases again, which can not be ascribed to the normal degradation processes. Therefore, a mechanism is proposed in which the chain scission takes place in the newly formed bridge.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296228
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  • 10
    Electronic Resource
    Electronic Resource
    Chain transfer constants of some alipathic agents in the polymerization of styrene and methylmethacrylate (1993)
    Springer
    Polymer bulletin 30 (1993), S. 55-60 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The chain transfer constants of various aliphatic compounds in the free radical polymerization of styrene and methyl methacrylate have been determined at 60°C. It has been found that some cycloaliphatic compounds show a remarkable chain transfer activity, which can also be of practical interest.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296234
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  • 11
    Electronic Resource
    Electronic Resource
    Synthesis of comb-like graft copolyamides with rigid aromatic main-chains and long flexible side-chains (1993)
    Springer
    Polymer bulletin 30 (1993), S. 149-153 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary In this paper we report a novel method of preparing polyamide molecular composites (1) by synthesizing graft-copolymes with stiff aromatic polyamide main-chains and flexible high molecular weight (high-M) polyamides as the side chains. The unique feature of the present graft-copolyamides is that the side-chains are connected directly to the aromatic rings in the stiff polyamide chains through amide groups, and are not connected to the amide groups present in the stiff main-chains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296843
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  • 12
    Electronic Resource
    Electronic Resource
    Stereospecific synthesis of ditactic polymers (1993)
    Springer
    Polymer bulletin 30 (1993), S. 171-178 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Polymerizations of t-butyl crotonate (E-TBC) and t-butyl isocrotonate (Z-TBC) t-Butyl (E)-2-butenoate and t-butyl (Z)-2-butenoate were carried out in toluene at-78°C using t-BuMgBr as initiator. E-TBC gave polymers, whereas Z-TBC did not. The dimer of E-TBC isolated from the polymerization mixture by means of GPC contained predominatly one of the four possible diastereomers. X-ray crystallographic determination showed that the predominant dimer was the erythro-diisotactic isomer. t-BuLi/Et3Al polymerized effectively both E-TBC and Z-TBC in toluene. The poly(E-TBC)s prepared with t-BuMgBr and t-BuLi/Et3Al were insoluble in toluene, THF, and chloroform, but soluble in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP). Stereostructure of the poly(TBC)s was analyzed by the one- and two-dimensional NMR spectra measured in HFIP. The poly(E-TBC) prepared with t-BuMgBr was a 1:1 mixture of the erythro- and threo-diisotactic polymers with high stereoregularity. The poly(E-TBC) and poly(Z-TBC) obtained from the polymerizations with t-BuLi/Et3Al were rich in disyndiotactic structure. Polymerization of TBCs with t-BuLi in toluene and THF was also studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296846
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  • 13
    Electronic Resource
    Electronic Resource
    Emulsion copolymerization of styrene and sodium acrylate (1993)
    Springer
    Polymer bulletin 30 (1993), S. 207-214 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Poly(styrene-co-sodium acrylate) has been synthesized by emulsion polymerization of styrene and sodium acrylate at a ratio of 9:1 with the water-soluble initiator potassium persulfate. The reaction is fast, conversions are high, and the evolution of particle size follows the conversion curve. The final latex is stable and contains spherical particles 70 nm in diameter. The presence of the copolymer is confirmed by several methods including FTIR, and the copolymer evolves from rich in sodium acrylate to rich in styrene as the reaction proceeds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296851
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  • 14
    Electronic Resource
    Electronic Resource
    Supported BF3 catalyst on crystalline polyolefins; carbocationic polymerization of isobutylene (1993)
    Springer
    Polymer bulletin 30 (1993), S. 385-391 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary This paper describes a new supported Lewis acid catalyst which involves BF3 species chemically bonded to the crystalline polyolefins, such as polypropylene and poly(1-butene). The supported catalysts are active in the carbocationic polymerization of isobutylene and are recovered and reused for many reaction cycles without significantly losing their activity. Several advantages, such as chemical and physical stabilities of the substrate, convenient implantation to load high concentration of catalyst to the substrate and high catalyst reactivity, have been observed. In addition, polyisobutylene obtained in this process has high terminal unsaturation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00338470
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  • 15
    Electronic Resource
    Electronic Resource
    Grafting of polyesters onto carbon whisker surface (1993)
    Springer
    Polymer bulletin 30 (1993), S. 421-428 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Acylium perchlorate groups were successfully introduced onto the surface of carbon whisker, i.e., vapor grown carbon fiber, by the reaction of surface acyl chloride groups with silver perchlorate in nitrobenzene. It was found that the cationic ring-opening polymerization of lactones, such as ε-caprolactone, δ-valerolactone, and β-propiolactone, is initiated by acylium perchlorate groups introduced onto carbon whisker. During the polymerization, the corresponding polyesters were effectively grafted onto carbon whisker surface based on the propagation of polyester from the surface. The rate of polymerization increased with increasing polymerization temperature, but the percentage of grafting of polyester onto the surface decreased.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00338475
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  • 16
    Electronic Resource
    Electronic Resource
    Compatibilization in ionomer blends (1993)
    Springer
    Polymer bulletin 30 (1993), S. 449-453 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Two kinds of copolymers, i.e. poly(styrene-co-methacrylic acid) (SMaa) and poly(butyl methacrylate-co-methacrylic acid) (BmaMaa) containing a common but minor (10–20%) component of methacrylic acid, were synthesized. The blends of the corresponding ionomers of SMaa and BmaMaa neutralized with a series of metal-ions produced by solvent casting and moulding were examined by DSC and TEM. It has been shown that introducing metal-ions to the blends of copolymers apparently improves the miscibility. This miscibility enhancement depends on the nature and amount of the counter ions. In the case of SMaa-Na+/BmaMaa-Na+ even a singlephase blend can be produced. The results confirm compatibilization in the blends of similar-charged ionomers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00338479
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  • 17
    Electronic Resource
    Electronic Resource
    Index in current contents (1993)
    Springer
    Polymer bulletin 30 (1993), S. A3 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00338484
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  • 18
    Electronic Resource
    Electronic Resource
    Syntheses and thermal properties of aromatic and semi-aromatic polythioetheramides containing oligo(thio-1,4-phenylene) segments (1993)
    Springer
    Polymer bulletin 31 (1993), S. 129-136 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A family of aromatic and semi-aromatic polythioetheramides was prepared from well-defined diamine-terminated oligo(thio-1,4-phenylene)s (PPS-DA) containing n=1,2,3,4,5,6 thio-1,4-phenylene units. Polycondensation reactions with adipic, sebacic, terephthalic and isophthalic acid chlorides were carried out in N-methyl-2-pyrrolidone solution at room temperature to yield amorphous and semi-crystalline polythioetheramides. The influence of the oligo(thio-1,4-phenylene) segment lengths on phase transitions and thermal degradation of the polythioetheramides was investigated. As a function of the PPS segment lengths, glass transition temperatures vary between 120°C and 300°C, and melting temperatures between 290°C and 500°C. The thermal stabilities determined by thermogravimetric analysis under nitrogen increase with increasing PPS segment lengths. In the case of the higher molecular weight PPS segments, the resulting semi-aromatic polyamides exhibit two crystalline phase transitions.
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    URL: http://dx.doi.org/10.1007/BF00329957
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  • 19
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    An experimental study of the unperturbed chain dimensions of poly(tetramethyl-p-silphenylene-siloxane) (1993)
    Springer
    Polymer bulletin 31 (1993), S. 205-211 
    Details
    ISSN: 1436-2449
    Keywords: Intrinsic viscosities ; osmotic pressures ; unperturbed dimensions ; characteristic ratio ; chain stiffness ; poly(tetramethyl-p-silphenylene-siloxane)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Experimental values of the characteristic ratio of the unperturbed dimensions of poly (tetramethyl-p-silphenylene-siloxane) were obtained from intrinsic viscosities and osmotic pressures. It was found that the characteristic ratio of this polymer is 1.55±0.30 when the phenylene group is treated as a virtual bond, and 4.51±0.40 when the individual bonds in the phenylene group are taken into account separately. This value is unexpectedly low, considering the usual stiffening effect of the p-phenylene group. Apparently this group can also have a “buffering” effect which decreases stiffness, by reducing interactions among the atoms or groups preceding it and succeeding it along the chain backbone.
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    URL: http://dx.doi.org/10.1007/BF00329967
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  • 20
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    The effect of fibre diameter on the drawing behaviour of gel-spun ultra-high molecular weight polyethylene fibres (1993)
    Springer
    Polymer bulletin 31 (1993), S. 243-248 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary In the continuous drawing of gel-spun UHMWPE fibres, the diameter of the undrawn fibre appears to have a pronounced effect on its drawing behaviour and on the mechanical properties of the resulting hot-drawn fibres. A highly oriented structure is developed more efficiently upon drawing of thinner fibres, which may be attributed to differences in the deformation mechanism between as-spun fibres of various diameters. By drawing of thin fibres, UHMWPE filaments having a strength of 6.0 GPa and a Young's modulus of 222 GPa can be obtained at a relatively low draw ratio of λ=70.
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    URL: http://dx.doi.org/10.1007/BF00329972
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  • 21
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    Poly(butadiene-acrylic acid(g)acrylonitrile(g)acrylic acid) (1993)
    Springer
    Polymer bulletin 31 (1993), S. 293-296 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary In the present work we describe, the synthesis and characterization of a new gel obtained by crosslinking a cooligomer of butadiene-acrylic acid (BuAA), by reaction with acrylonitrile and acrylic acid. The purified product was characterized by FTIR, elemental analyses and scanning electronic microscopy. The thermal properties were studied and swelling indexes were determined in different solvents and at different pH values. The capacity of poly(butadiene-acrylic acid(g)acrylonitrile(g)acrylic acid) [gel A] to separate different organic substances, such as amino acids and colorants, was determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00692954
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  • 22
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    The synthesis and characterization of a mesomorphic brush type polycarbosilane: poly[1,1-bis(4′-biphenyl)silabutane] (1993)
    Springer
    Polymer bulletin 31 (1993), S. 279-283 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Poly[1,1-bis(4′-biphenyl)silabutane] (II) has been prepared by the anionic ring opening polymerization of 1,1-bis(4′-biphenyl)silacyclobutane. II shows mesomorphic behavior by DSC. The13C NMR T1 relaxation times have been measured. These are found to be smaller than those of poly(1,1-dimethylsilabutane)by an order of magnitude. This may result from interaction of the highly rigid biphenyl side chain moieties. The thermal stability of II is higher than that for other 1,1-disubstituted polysilabutanes.
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    URL: http://dx.doi.org/10.1007/BF00692952
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  • 23
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    From rigid rod to random walk. Some exact results (1993)
    Springer
    Polymer bulletin 30 (1993), S. 617-620 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The conformational behaviour of a macromolecule is described by a random walk of fixed contour length which consists of n straight segments, where n=1,2, .... Two cases are discussed: (i) the segments are of equal length; (ii) the points where the random walk changes its direction are randomly distributed along the contour. Analytical expressions for the mean squared end-to-end distance R and for the radius of gyration R g are presented. When deriving R g it is assumed that the mass of the chain is distributed uniformly along the contour.
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    URL: http://dx.doi.org/10.1007/BF00296483
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  • 24
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    Determination of the configuration of citraconic anhydride units in copolymers of p-chlorostyrene with citraconic anhydride via 13C NMR spectroscopy (1993)
    Springer
    Polymer bulletin 30 (1993), S. 641-645 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The configuration of citraconic anhydride units in p-chlorostyrene/citraconic anhydride copolymers prepared in methyl ethyl ketone at 50.0±0.1°C and the corresponding copolymer compositions and comonomer unit sequence distributions were determined over a range of comonomer feed mole fractions using 13C NMR spectroscopy. It was found that the ratio of Z (zusammen) to E (entgegen) configurations of citraconic anhydride units in these semi-alternating copolymers showed an overall tendency to increase with the degree of alternation of the monomer units.
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    URL: http://dx.doi.org/10.1007/BF00300031
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    Interactions between PVC and solvents by longitudinal nuclear relaxation times (1993)
    Springer
    Polymer bulletin 30 (1993), S. 677-684 
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    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract PVC/aliphatic ketone systems were investigated by NMR relaxation times such as proton and carbon-13 spin-lattice relaxation time (T1) and proton spin-lattice relaxation time in the rotating frame (T1ϱ). The proton T1 results showed that these systems are homogeneous, while proton T1ϱ indicates the existence of more than one domain.
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    URL: http://dx.doi.org/10.1007/BF00300036
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    Miscibility of PVA/EVA systems by viscometry (1993)
    Springer
    Polymer bulletin 30 (1993), S. 697-703 
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    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Viscometric data were applied to characterize the miscibility of poly(vinyl chloride) (PVC)/poly(ethylene-co-vinyl acetate) (EVA) mixtures using six samples of EVAs with different vinyl acetate content in the copolymer. Relative viscosity vs composition plots showed the imiscibility of PVC/EVA 31 and PVC/EVA 41 blends. The variation of the reduced viscosity, ηsp/C with the concentration, C, has been studied for 50:50 by weight blends of PVC/EVA 45, PVC/EVA 45A, PVC/EVA 50 and PVC/EVA 70 in tetrahydrofuran at 25°C. The presence of a sharp crossover and a consequent reduction of slope in ηsp/C vs C plots showed that these systems are miscible for a concentration range which corresponds to the regime of dilute solution.
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    URL: http://dx.doi.org/10.1007/BF00300039
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    Porous volume determination of styrene-divinylbenzene copolymers by water uptake measurements (1993)
    Springer
    Polymer bulletin 30 (1993), S. 725-728 
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    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A simple method of porous volume determination for styrenedivinylbenzene copolymers has been developed. This method is based on water uptake measurements after surface treatment with methanol in order to reduce the characteristic water repellance of the copolymer beads. The porous volume determined by water uptake is in good agreement with mercury porosimetry measurements.
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    URL: http://dx.doi.org/10.1007/BF00300043
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    2-Cyano-2-butylazoformamidoethyl 4-t-butylazo-4-cyanopentanoate synthesis and its behaviour in methyl methacrylate polymerization (1993)
    Springer
    Polymer bulletin 31 (1993), S. 15-21 
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    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Synopsis In the present paper the synthesis of a new bis-azo initiator, 2-cyano-2-butylazo-formamidoethyl 4-t-butylazo-4-cyanopentanoate, is reported. The structures of the intermediates and of the initiator were confirmed by the IR and 1H-NMR spectral measurements. The polymerization of methyl methacrylate (MMA) in the presence of this initiator was studied and the conversion-time dependence followed with different concentrations of the initiator and of the monomer.
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    URL: http://dx.doi.org/10.1007/BF00298758
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    Compatibilization in ionomer blends (1993)
    Springer
    Polymer bulletin 30 (1993), S. 455-460 
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    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Copolymers of poly(styrene-co-4-vinylpyridine) (SVp) and poly(butyl methacrylate-co-4-vinylpyridine) (BmaVp) containing common minor units of pyridine were prepared. The blends of BmaVp/SVp were reacted with a series of metal acetates and carboxylic acids respectively. Due to coordination complexation between the Vp units and metal-ions and proton-transfer from the acids to Vp units, in both cases the two component ionomers carry positive charge. DSC examination of the two kinds of blends show an apparent miscibility enhancement by introducing the ion groups although there is no favorable columbic interaction between the component ionomers. These results provide a new evidence of compatibilization in the blends of the ionomers with an identical charge.
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    URL: http://dx.doi.org/10.1007/BF00338480
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    Study of deblocking and crosslinking reactions of a blocked isocyanurate cationomer (1993)
    Springer
    Polymer bulletin 31 (1993), S. 75-82 
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    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A cationic adduct of a partly blocked hexamethylene isocyanurate and N-methyldiethanolamine was prepared and applied as a crosslinker in one-pack water-borne polyurethane system. The deblocking and crosslinking reactions were followed by FTIR, TGA and DSC techniques. Deblocking started at about 100°C, while at higher temperatures urethane, allophanate, and urea linkages were formed. The efficiency of the cationic crosslinker was evaluated by determining the insoluble part of the crosslinked polyurethane ionomer films. Films of a good solvent resistance were obtained using 15 wt% of the cationic crosslinker and 0.05 wt% of a catalyst at 130°C.
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    URL: http://dx.doi.org/10.1007/BF00298767
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    Thermal transitions in poly(alkyl-4,4′-diphenoxy terephthalate)s (1993)
    Springer
    Polymer bulletin 31 (1993), S. 97-104 
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    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The thermal transitions of poly(alkyl-4,4′-diphenoxy terephthalate)s, in which the flexible spacer contains 5,6 and 7 methylene groups, have been studied by thermogravimetry, differential scanning calorimetry, X ray diffraction, thermoptical microscopy and small angle light scattering. The series shows a marked influence of the even and odd number of methylene groups on the crystal-liquid crystal transition temperatures and on the isotropization transition temperature. Nematic mesophases have been observed for the odd terms, and a transition from a smectic to a nematic mesophase has been observed for the even term.
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    URL: http://dx.doi.org/10.1007/BF00298770
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    Synthesis and electro-optical behaviour of a new chiral smectic side-chain polysiloxane (1993)
    Springer
    Polymer bulletin 31 (1993), S. 167-174 
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    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A new chiral side-chain polymer was prepared by hydrosilylation of a dimethylsilane-methyl-hydrosilane copolymer. The chiral group of the mesogenic side-chain was (+)2-chloro-3-(3-nitro-4-hydroxyphenyl)propionic acid butyl ester while the main part of the aromatic nucleus consisted of 4′-hydroxybiphenyl-4-carboxylic acid. Phase behaviour was studied by DSC and polarizing microscopy, and correlated with dielectric measurements. Alignment properties and ferroelectricity were studied in cells with surface-induced alignment and in shear cells. The polymer exhibits chiral C-and A-phases. The spontaneous polarization is 130 nC/cm2 at 60°C and the polymer shows ferroelectric switching at room temperature.
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    URL: http://dx.doi.org/10.1007/BF00329962
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    Enthalpy relaxation studies in isotactic polystyrene. Effects of crystallinity (1993)
    Springer
    Polymer bulletin 30 (1993), S. 609-616 
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    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The enthalpy relaxation of the amorphus isotactic polystyrene is strongly affected from the crystalline phase induced by annealing at temperatures between Tg and Tm. All the parameters describing the relaxation process, ΔΔH, Tmax and Tons depend also on the above Tg annealing conditions as the induced crystallinity alters the quantity and the quality (i.e.Tg, Tgons, ΔTg) of the remaining amorphous phase.
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    URL: http://dx.doi.org/10.1007/BF00296482
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    Polymer-supported copolymerization of poly(phenylene vinylene) (1993)
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    Polymer bulletin 30 (1993), S. 629-632 
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    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A series of phenyl ring di-substituted α,α′-dichloro-p-xylene monomers were copolymerized in situ onto a cross-linked chloromethylated polystyrene resin. A phase-transfer catalyst was employed to facilitate this multiphase heterogeneous polymerization. The electrical as well as the thermogravimetric properties of the conducting grafted resins are reported.
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    Influence of ester group size in PMAs on β phase crystallization of PVF2 in highly oriented films of PVF2/PMAs blends (1993)
    Springer
    Polymer bulletin 30 (1993), S. 655-661 
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    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Influence of ester group size in polymethacrylates (PMAs), including PMMA, PEMA and PBMA, on β phase crystallization of poly(vinylidene fluoride) (PVF2) in highly oriented films of PVF2 /PMAs=80/20 blends has been investigated by FTIR and TEM. The melt-drawn films of pure PVF2 consist of highly oriented lamellae, in which the α phase is predominant. Adding a given amount of PMAs (20 wt%) into PVF2 results in formation of fibrillar crystals and increase of relative amount of the β phase. The influence extent is in order of PMMA〉PEMA〉PBMA, regarding the ester group size in the PMAs.
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    Effect of soft segment on degradation kinetics in polyethylene glycol/poly(l-lactide) block copolymers (1993)
    Springer
    Polymer bulletin 30 (1993), S. 669-676 
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    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The hydrolytic degradation of polyethylene glycol(PEG)/poly (L-lactide)(PLLA) copolymers with various PEG wt% contents at 37°C and pH=7 was studied by differential scanning calorimetry(DSC) and gel permeation chromatography(GPC). The effect of PEG contents in PEG/PLLA copolymers on the crystalline morphology and hydrolytic degradation rate was investigated. Due to the hydrophilic PEG segments in PEG/PLLA copolymers, the exothermic recrystallization and the shoulder portion of melting endotherm appear immediately following the hydrolysis of copolymers. Moreover, after a period of hydrolysis of 100 h. the molecular weight distribution turn to a bimodal shape from a unimodal in the original, and the polydispersity becomes greater with a value from 1.5 up to 5, which are not observed for PLLA homopolymer. The rate constants of hydrolysis for the first-order auto-catalytic kinetics, increase with the PEG content over 0 to 18.3 wt%, ranging from 1 to 6x10-4hr-1.
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    URL: http://dx.doi.org/10.1007/BF00300035
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    The behaviour of poly(2-ethylhexyl acrylate) in dilute solution: viscosity measurements (1993)
    Springer
    Polymer bulletin 30 (1993), S. 713-718 
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    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Linear macromolecules of the poly(2-ethylhexyl acrylate) were prepared by solution polymerization in toluene at 12 °C, using azobisisobutyronitrile as initiator. The polymer was fractionated and the fractions characterized by the methods of light scattering, osmometry and viscometry. Mark-Houwink-Sakurada relations at 25°C in solvents of different thermodynamical quality have been determined.
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    Polymeric chiral crown ethers (1993)
    Springer
    Polymer bulletin 31 (1993), S. 37-42 
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    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Copolymerizations of (S)-3,3′-dimethyl-2,2′-bis[2-(2-vinyloxyethoxy)ethoxy]-1, 1′-binaphthyl (S-MVN) or 1,3:4,6-di-O-benzylidene-2,5-bis-O-[2-(2-vinyloxyethoxy)ethyl]-d-mannitol (D-BVM) with isobutyl vinyl ether (IBVE) were carried out with BF3·OEt2 in CH2Cl2 at 0 °C. The copolymers obtained were soluble in CHCl3 and THF, and consited of (S)-binaphtho-21-crown-6 or d-manno-21-crown-6 units and IBVE, i.e., poly(S-DVN-co-IBVE) and poly(D-BVM-co-IBVE). These host copolymers dominantly formed complexes with l-phenylglycine methyl ester, whose properties were similar to those for homopolymers of S-MVN and D-BVM.
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    URL: http://dx.doi.org/10.1007/BF00298761
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    Partial and complete hydrogenation of poly(1-methyl-1-phenyl-1-sila-cis-pent-3-ene) (1993)
    Springer
    Polymer bulletin 31 (1993), S. 305-309 
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    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Poly(1-methyl-1-phenyl-1-silapentane)(II), andblock copoly(1-methyl-1-phenyl-1-sila-cis-pent-3-ene/1-methyl-1-phenyl-1-silapentane) (block-III) have been prepared by catalytic hydrogenation of poly(1-methyl-1-phenyl-1-sila-cis-pent-3-ene)(I) over 5% palladium on carbon. These polymers have been characterized by1H,13C and29Si NMR as well as IR spectroscopy. Molecular weight distributions have been evaluated by gel permeation chromatography (GPC). Thermal stabilities have been measured by thermogravimetric analysis (TGA). Glass transition temperatures (Tg's) have been determined by differential scanning calorimetry (DSC).
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    Poly(glycolic acid) fiber-reinforced bioabsorbable composites with improved interfacial properties (1993)
    Springer
    Polymer bulletin 31 (1993), S. 331-338 
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    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Bioabsorbable composites, designed for use as rigid tissue scaffolds, were fabricated by reinforcing free radically cured poly(D,L-lactide) fumarate matrices with absorbable poly(glycolic acid) fibers. To investigate the benefits of an improved fiber/matrix interphase, fiber pretreatments were employed including surface-etching by exposure to mild acidic conditions and incorporation of 3-methacryloxypropyltrimethoxysilane as a coupling agent. SEM of composite fracture surfaces showed that fiber pretreatment yielded improved wetting and encapsulation of the fibers by the matrix resin. The composites fabricated with poly(glycolic acid) fibers which were acid-etched and pretreated with the coupling agent showed an average 41% increase in tensile strength; a representative sample displayed an increase from 73.9 MPa to 105.5 MPa, compared to the composite made from untreated fibers.
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    Preparation of polyaniline particles in an inverse microemulsion (1993)
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    Polymer bulletin 31 (1993), S. 347-350 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Aniline has been successfully polymerised in a stable inverse microemulsion. The microemulsion polymerization of aniline produced ultrafine particles of conducting polyaniline. The particles were rather spherical and they ranged from 10 to 35 nm in diameter. The electrical conductivity of the polyaniline was about 8 S cm-1, which has been improved to several hundred S cm-1 recently based on the similar process filed for an US patent.
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    A mechanochromic smart material (1993)
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    Polymer bulletin 31 (1993), S. 367-374 
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    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A mechanochromic polyurethane elastomer was synthesized and demonstrated. Azobenzene chromophores were introduced into a copolyamide oligomer to provide conformational latches which stabilized thecis-azobenzenes by the formation of intramolecular hydrogen bonds. The copolyamide oligomer was chemically inserted into a polyurethane copolymer. The chromophores in the resulting copolymer were transformed to thecis-form by ultraviolet (UV) irradiation (λ=365 nm) and then succesively stretched and relaxed to strains of 100%, 200%, and 300%. After 100% strain and relaxation, the absorbance of polyurethane copolymer at λ=380 nm, which indicates transformation to the trans form, was not significantly increased. However, the absorbance increased with 200% and 300% tensile strain followed by relaxation. A mechanochromic relationship between absorbance increase at λ=380 nm in the relaxed sample and the maximum strain to which the sample was subjected was thus demonstrated.
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    In vitro sodium salicylate release from chitosan films (1993)
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    Polymer bulletin 31 (1993), S. 375-379 
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    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary In order to evaluate the applicability of chitosan membranes in controlled release systems, a reservoir-type device was designed. Sodium salicylate was chosen as model drug. The rate of release was measured in water at 37°±0.5° C and the amount of drug released was determined by spectrophotometric analysis. The results showed that sodium salicylate release followed a zero order kinetics.
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    Preparation and characterization of novel biodegradable tri- and tetraacrylate intermediates (1993)
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    Polymer bulletin 31 (1993), S. 401-407 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Two biodegradable polymer intermediates, triacrylate 4 and tetraacrylate 7, were prepared by polycondensation reaction of ethyl β-hydroxybutyrate using glycerol and pentaerythritol as initiators and dibutyltin oxide as a catalyst, followed by functionalization of the hydroxyl end groups with acryloyl chloride in the presence of triethyl amine. These polymer intermediates were characterized using 1H-NMR and IR spectroscopic analysis and were employed as crosslinking agents during polymerization of partially neutralized acrylic acid to obtain the corresponding potentially biodegradable polyacrylates.
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    Curing of epoxy resins with dicyandiamide (1993)
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    Polymer bulletin 31 (1993), S. 429-435 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The mechanism of the epoxy resin curing with dicyandiamide was studied using the model phenyl glycidyl ether and different substituted dicyandiamides. Some reaction products were isolated by HPLC and characterized by FTIR and Carbon-13 NMR spectroscopy. A reaction pathway is proposed discussing the formation of cyclic structures, carbonyl groups and oligomerization products of the glycidyl ether.
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    Announcement (1993)
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    Polymer bulletin 31 (1993), S. XII 
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    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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    URL: http://dx.doi.org/10.1007/BF00300135
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    Hydroboration polymerization of dicyano compounds (1993)
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    Polymer bulletin 31 (1993), S. 553-558 
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    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Hydroboration polymerization of various α,ω-dicyanoalkanes with thexylborane produced the corresponding poly(cyclodiborazane)s, that consist of boron-nitrogen four-membered rings. The structures of the obtained polymers were confirmed by spectroscopic analyses such as 1H-, 11B-NMR and IR spectra. From the result of thermogravimetric analysis of the polymer prepared from adiponitrile and thexylborane, 12% of the inorganic materials remained after heating at 900°C. *** DIRECT SUPPORT *** AEB03051 00003
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    Preparation and morphology of electrically conductive and transparent poly(vinylchloride)-polypyrrole composite films (1993)
    Springer
    Polymer bulletin 31 (1993), S. 593-599 
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    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The chemical process of preparing poly(vinylchloride)-polypyrrole composite films with high electrical conductivity and transparency has been studied. Pyrrole has been diffused into the poly(vinylchloride) matrix in the swelling medium of n-hexane and acetone mixture. The oxidative polymerization of the diffused pyrrole in the binary solvent system of acetonitrile and methanol gives high conductivity of the polypyrrole as well as the good penetration of the oxidant into the PVC polymer matrix. The analytical testing of the composite film shows the formation of homogeneous mixture of polypyrrole and poly(vinylchloride) conductive layer within the 1.0μm of thickness on the film surface. The transparency of the composite film showed about 50–60% at 500 nm. The electrical conductivity of the composite was about 20 s/cm.
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    A method for rubber toughening powder coatings (1993)
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    Polymer bulletin 31 (1993), S. 715-721 
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    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract This paper describes a new method for rubber toughening brittle powder coatings. The design involves the use of toughening agents with specific physical and chemical properties. The modifiers are low-to-medium molecular weight polymers with polymerizable end groups (macromonomers). To achieve the physical properties required for fabrication into fine powders for subsequent deposition using conventional powder coating equipment, semi-crystalline polymers with Tg's well below room temperature and melting points above ≈70°C were required. Upon copolymerization with a thermosetting resin, crystallization of the modifier was precluded provided that low ethylene oxide compositions were employed. This scheme, in principle, yields an amorphous low Tg modifier chemically bound to the cured network. Poly(ethylene oxide), PEO, was found to be an excellent candidate, since it has a Tg of -68°C and a Tm of 70°C, sufficient crystallinity for friability and functional end groups for copolymerization. Free radical polymerization of 2,2-bis[4-vinylbenzoyloxyphenyl] hexafluoropropane and step-growth polymerization of 4,4′-(hexafluoroisopropylidene)diphenyl cyanate were utilized to demonstrate the feasibility of this approach. An electrostatic powder coater was used to co-deposit the PEO macromonomers with either of the thermosetting precursor monomers, followed by thermal curing to produce the modified networks. The resulting networks showed multiphase morphologies with improved toughness.
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    URL: http://dx.doi.org/10.1007/BF00300132
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    Development of unbiased plotting position formula for General Extreme Value distributions (1993)
    Springer
    Stochastic environmental research and risk assessment 7 (1993), S. 1-13 
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    ISSN: 1436-3259
    Keywords: Unbiased plotting position ; General Extreme Value distribution ; order statistics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Expressions for the expected values of GEV order statistics have been derived in simple summation form and in terms of probability weighted moments. Using exact plotting positions from GEV order statistics a new unbiased plotting position formula has been developed for the General Extreme Value distribution. The formula can, explicitly, take into account the coefficient of skewness, γ (or the shape parameter, k), of the underlying distribution. The developed formula better approximates the exact plotting positions as compared to other existing formulae and is quite easy to use.
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    URL: http://dx.doi.org/10.1007/BF01581563
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    The development of stochastic space transformation and diagrammatic perturbation techniques in subsurface hydrology (1993)
    Springer
    Stochastic environmental research and risk assessment 7 (1993), S. 14-32 
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    ISSN: 1436-3259
    Keywords: Stochastic hydrology ; random fields ; space transformation ; perturbation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract This paper develops concepts and methods to study stochastic hydrologic models. Problems regarding the application of the existing stochastic approaches in the study of groundwater flow are acknowledged, and an attempt is made to develop efficient means for their solution. These problems include: the spatial multi-dimensionality of the differential equation models governing transport-type phenomena; physically unrealistic assumptions and approximations and the inadequacy of the ordinary perturbation techniques. Multi-dimensionality creates serious mathematical and technical difficulties in the stochastic analysis of groundwater flow, due to the need for large mesh sizes and the poorly conditioned matrices arising from numerical approximations. An alternative to the purely computational approach is to simplify the complex partial differential equations analytically. This can be achieved efficiently by means of a space transformation approach, which transforms the original multi-dimensional problem to a much simpler unidimensional space. The space transformation method is applied to stochastic partial differential equations whose coefficients are random functions of space and/or time. Such equations constitute an integral part of groundwater flow and solute transport. Ordinary perturbation methods for studying stochastic flow equations are in many cases physically inadequate and may lead to questionable approximations of the actual flow. To address these problems, a perturbation analysis based on Feynman-diagram expansions is proposed in this paper. This approach incorporates important information on spatial variability and fulfills essential physical requirements, both important advantages over ordinary hydrologic perturbation techniques. Moreover, the diagram-expansion approach reduces the original stochastic flow problem to a closed set of equations for the mean and the covariance function.
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    URL: http://dx.doi.org/10.1007/BF01581564
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    Two kinds of moment ratio diagrams and their applications in hydrology (1993)
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    Stochastic environmental research and risk assessment 7 (1993), S. 41-65 
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    ISSN: 1436-3259
    Keywords: Moment ratio diagrams ; Log-Pearson Type III ; Generalized Gamma ; geometric mean ; harmonic mean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract We refocus attention on moment ratio diagrams and their uses in hydrology with four major objectives: (1) to summarize the information available in the literature about possible uses of the traditional moment ratio diagram introduced by Karl Pearson, which uses the coefficient of skewness and of kurtosis to compare the shapes of various distributions commonly used in hydrology; (2) to complete this traditional MRD by integrating into it the regions occupied by the log-Pearson Type III and generalized gamma distributions which are more and more used in hydrology; (3) to present another MRD which uses ratios of moments of orders −1 (harmonic mean), quasi zero (geometric mean) and 1 (arithmetic mean); (4) to stress the need to consider the different MRD's (along with the more recently introduced L-moment ratio diagrams) as complementary tools for choosing between distributions fitted to hydrologic data. Finally, using Monte Carlo simulation we compare the two types of diagrams as tools to identify and discriminate between different distributions.
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    URL: http://dx.doi.org/10.1007/BF01581566
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    Parameter identification in particle models (1993)
    Springer
    Stochastic environmental research and risk assessment 7 (1993), S. 109-130 
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    ISSN: 1436-3259
    Keywords: Particle models ; transport equations ; parameter identification ; adjoint modelling ; cost function ; gradient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract For the simulation of the transport of dissolved matter particle models can be used. In this paper a technique is developed for the identification of uncertain parameters in these models. This model calibration is formulated as an optimization problem and is solved with a gradient based algorithm. Here adjoint particle tracks are used for the calculation of the gradient of the cost function. The performance of the calibration method is illustrated by simulations and an application to a river Rhine water quality calamity in November 1986.
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    URL: http://dx.doi.org/10.1007/BF01581420
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    Empirical Orthogonal Function (EOF) analysis of spatial random fields: Theory, accuracy of the numerical approximations and sampling effects (1993)
    Springer
    Stochastic environmental research and risk assessment 7 (1993), S. 146-160 
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    ISSN: 1436-3259
    Keywords: EOF analysis ; numerical approximations ; sampling effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Empirical Orthogonal Function (EOF) analysis of spatial random fields involves calculation of the eigenfunctions of the covariance kernel of the field. For real-world applications, a numerical approximation is necessary because the process is spatially discretized. An approximation for two-dimensional fields is proposed and then, analytical solutions of the integral problem are derived and used to study the accuracy of the numerical approximations. Sampling effects are also considered.
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    URL: http://dx.doi.org/10.1007/BF01581422
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    Multiscale adaptive estimation of the conductivity field from head and tracer data (1993)
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    Stochastic environmental research and risk assessment 7 (1993), S. 66-82 
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    ISSN: 1436-3259
    Keywords: Parameter identification ; multiscale ; transport ; adaptive
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Large scale fluctuations in the conductivity field are regionalized and estimated via a maximum likelihood, adjoint-state methodology. Small-scale fluctuations within each region are estimated adaptively via a Kalman-like stochastic filter. The variance and integral scale within each region are assumed to control the small-scale fluctuations. A Monte Carlo technique is used to examine the distribution of large-scale conductivity estimates.
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    Announcements (1993)
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    Stochastic environmental research and risk assessment 7 (1993), S. 83-83 
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    ISSN: 1436-3259
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
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    URL: http://dx.doi.org/10.1007/BF01581568
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    A scale-invariant approach to flood-frequency analysis (1993)
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    Stochastic environmental research and risk assessment 7 (1993), S. 33-40 
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    ISSN: 1436-3259
    Keywords: Fractal ; flood-frequency ; scale-invariant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract In order to study historical flood-frequency records we plot the log of the number of floods on a river per unit time in which the peak discharge exceeds a specified value against the log of that value. For ten benchmark stations we find good correlations with scale-invariant (fractal) statistics. We suggest that the underlying physical processes associated with the generation of floods are sufficiently scale invariant over time scales from one to one hundred years that they provide a rational basis for the application of scale-invariant statistics. Our results fall within the range of flood-frequency estimates made by other statistical techniques. We propose that the ratio of the ten-year peak discharge to the one-year peak discharge β is a quantitative measure of flood potential. With scale invariance β is also the ratio of the one-hundred year flood to the ten-year flood. We find that the values of β for ten stations on rivers throughout the country range from 2.04 to 8.11 and find strong regional variations that can be correlated in terms of climate. Our results are consistent with the observed fractal statistics in sedimentary sections. We have also carried out R/S analyses for the ten stations and have obtained values of the Hurst exponent. We find that the Hurst exponent cannot be used for flood-frequency forecasting.
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    Evaluation of safety of hydraulic structures affected by migrating pits (1993)
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    Stochastic environmental research and risk assessment 7 (1993), S. 131-145 
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    ISSN: 1436-3259
    Keywords: Safety ; reliability analysis ; uncertainty analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Because it can be carried by flowing water, a sand/gravel pit on the river bed could migrate downstream. Consequently, the presence of pits on river beds could pose a safety threat to in-stream hydraulic structures such as bridge piers. A pit migration model can be used to predict progressive changes of pit geometry as it migrates downstream. However, due to the existence of many uncertainties, the maximum pit depth cannot be predicted with certainty. This paper adopted a simple pit migration model and evaluated the uncertainty associated with the calculated maximum pit depth. Such information is essential for evaluating the probability that a migrating pit could pose a safety threat to a downstream hydraulic structure. Three reliability analysis techniques were applied and their performances were compared.
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    URL: http://dx.doi.org/10.1007/BF01581421
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    Evaluating the effect of land development on sediment transport using a probability density function (1993)
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    Stochastic environmental research and risk assessment 7 (1993), S. 102-108 
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    ISSN: 1436-3259
    Keywords: Sedimentation ; probability density function ; synthetic study ; development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract An important problem in sedimentation analysis is the development of a channel section that preserves, as best as possible, the current sedimentation regime even though the flood frequency tendencies have been altered due to land development within the catchment. In order to accomplish this task, a methodology is needed that estimates sediment transport capacity for various channel configurations. Such a procedure is described which allows the computation of the total sediment transport capacity for each of several T-year return frequency runoff hydrographs. This information is used to obtain an approximate probability distribution for the total sediment transport capacity, and the mean and standard deviation of this distribution are computed. Comparing the results for the catchment in its present state with a future developed state, using a selection of new channel parameters, indicates how to improve the channel to control changes in sedimentation due to development. The analysis procedure provides a basis for estimating a new channel configuration such that the new flow conditions retain, as best as possible, the existing condition sedimentation effects, and hence retain the natural sediment supply and transport trends even though runoff flow rates have changed due to land development within the catchment. The results of Wilson Creek are typical of the several sites examined, see Table 3 below. The T=2, T=5, T=25, and T=100 year values for total sediment transport capacity, in kilotons, are 6.9, 39.4, 61.3, and 96.7 with a mean of 17.1 and standard deviation of 19.3. After development with no change in the channel the respective values increase to: 17.9, 84.6, 128.1, and 258.0 with a mean of 39.1 and standard deviation of 44.3. A new channel can be constructed which will reduce these sediment transport capacity values, after development, to 5.2, 41.0, 62.0, and 124.8 with a mean of 17.4 and standard deviation of 22.0.
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    Parameter estimation for 3-parameter log-logistic distribution (LLD3) by Pome (1993)
    Springer
    Stochastic environmental research and risk assessment 7 (1993), S. 163-177 
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    ISSN: 1436-3259
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract The principle of maximum entropy (POME) was employed to derive a new method of parameter estimation for the 3-parameter log-logistic distribution (LLD3). Monte Carlo simulated data were used to evaluate this method and compare it with the methods of moments (MOM), probability weighted moments (PWM), and maximum likelihood estimation (MLE). Simulation results showed that POME's performance was superior in predicting quantiles of large recurrence intervals when population skew was greater than or equal to 2.0. In all other cases, POME's performance was comparable to other methods.
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    On the validity of empirical power laws (1993)
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    Stochastic environmental research and risk assessment 7 (1993), S. 179-194 
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    ISSN: 1436-3259
    Keywords: Hydrological processes ; power laws ; spurious self-correlation ; lake hydrology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Empirical power laws are frequently used to relate parameters in complex hydrological and hydrometeorological processes. The validity of power laws relating two parameters with a common variable may be compromised by spurious influences of the common variable. Theoretical results are presented that allow both the spurious self-correlation coefficient and the slope of a spurious self-correlation to be determineda priori. Raising a common variable to a higher power in either parameter amplifies the spurious effects. Power law regression equations are not single-valued analytical functions and must not be treated as such. Because of the strong influence of a common variable on the correlation coefficient, the transfer of a common variable from one side of a power-law regression equation to another (by cross-multiplying) may severely distort the results. Examples from lake hydrology are presented.
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    A master equation for reactive solute transport in porous media (1993)
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    Stochastic environmental research and risk assessment 7 (1993), S. 255-268 
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    ISSN: 1436-3259
    Keywords: Groundwater hydrology ; solute transport ; master equation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract The mean value of a density of a “cloud of points” described by a generalized Liouville equation associated with a convection dispersion equation governing adsorbing solute transport yields a joint concentration probability density. The general technique can be applied for either linear or nonlinear adsorption; here the application is restricted to linear adsorption in one-dimensional transport. The equation generated for the joint concentration probability density is in the general form of a Fokker-Planck equation, but with a suitable coordinate transformation, it is possible to represent it as a diffusion equation with variable coefficients.
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    Comparisons of Weibull- and exponential-based partial duration stochastic flood models (1993)
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    Stochastic environmental research and risk assessment 7 (1993), S. 283-297 
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    ISSN: 1436-3259
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract A stochastic flood model with a Weibull distribution for flood exceedances is examined and compared to the traditional exponential-based model in terms of predictive and descriptive properties. The model is based upon the traditional representation of the flood mechanism as a Poisson counting process. It is expected that the more flexible Weibull distribution will be capable of modeling flood series which exhibit a wider range of variability than the exponential model. The Weibull-based model is shown to possess predictive properties which are superior to the exponential model when samples exhibit coefficients of variation less than 1.5 and sample sizes are on the order of 2 events per year. These characteristics are shown to exist in many observed flood series in the Gulf Coast of the United States.
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    Interpolation of runoff applying objective methods (1993)
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    Stochastic environmental research and risk assessment 7 (1993), S. 269-281 
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    ISSN: 1436-3259
    Keywords: Runoff ; stochastic interpolation ; objective analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract The paper treats the problem of interpolating annual runoff from regular streamflow measurements in a regional scale applying objective methods. These methods are adapted to point processes like temperature and precipitation. Modifications are needed to account for the fact that streamflow is an integrated process following the hierarchical structure of river systems. The most straightforward method is therefore to relate the interpolation to the existing river network. For theoretical reasons it is preferable to interpolate the lateral inflow rather than the flow in the river itself. Procedures for the interpolation with the different approaches are developed and discussed. Special attention is put on the question how the equation of continuity can be satisfied. The Laagen drainage basin in southern Norway is used as a test area. The data consist of annual observations of streamflow and digital map information on river networks and drainage basin boundaries.
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    A design environment for laminated fiber-reinforced thick composite materials (1993)
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    Engineering with computers 9 (1993), S. 36-48 
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    ISSN: 1435-5663
    Keywords: Composite Materials ; Composites ; Computer-aided design ; Computer integrated manufacturing ; Database ; Design database ; Material property database
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The research described herein concerns the integration of several components of engineering software using a relational database. More specifically, a conceptual finite element material preprocessing system for laminated fiber-reinforced thick composite materials is studied. In this computer-aided analysis (CAA) system, a materials database is integrated with several software components, including commercially available finite element analysis (FEA) programs and preprocessors, and tools for the design of laminated composite materials. The system focuses on assembling, manipulating and using composite materials data, resulting in the transfer of 2-D and 3-D composite materials property data into a finite element analysis program. The system is life-cycle in nature, supporting a composite through testing, analysis and design. it offers great versatility in its ability to use raw ply data from any source, design layups, and generate laminate properties and FEA materials data files. Despite the fact that such integrated systems are not new in many domains, they have not been successfully introduced to the redlm of composite materials analysis and design. This outcome is due largely to the nature of the materials themselves and the overhead they bring to the development of a successful life-cycle model.
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    Computational methods for blending surface approximation (1993)
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    Engineering with computers 9 (1993), S. 49-62 
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    ISSN: 1435-5663
    Keywords: Approximation ; Data exchange ; Geometric modeling ; NURBS ; Surface blends
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Blending surfaces form a smooth transition between two distinct, intersecting surfaces or smoothly join two or more disconnected surfaces and are normally procedural surfaces which are difficult to exchange and to interrogate in a reliable and efficient manner. In this paper, an approximation method for blending surfaces which are curvature continuous to the underlying surfaces with a non-uniform rational B-spline (NURBS) surface is presented. The use of NURBS is important since it facilitates the exchange of geometric information between various computer aided design and manufacturing systems. In the method, linkage curves on the underlying surfaces are approximated to within a specified tolerance and cross-link curves are created using the linkage curves, a directional curve and the parametric partial derivatives of the underlying surfaces. Cross-link curves are lofted to form the blending surface and an adaptive sampling procedure is used to test the blending surface against specified tolerances. Cross-link curves are added, where necessary, and the surface relofted until the continuity conditions are satisfied to within specified tolerances. Examples illustrate the applicability of the method.
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    Arbitrary crack representation using solid modeling (1993)
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    Engineering with computers 9 (1993), S. 63-82 
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    ISSN: 1435-5663
    Keywords: Computational fracture mechanics ; Crack propagation ; Three-dimensional fracture mechanics ; Topological data structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This paper describes the fundamental modeling approaches adopted for crack nucleation and propagation in a software system that is specifically designed to simulate problems with evolutionary geometry. Only the topological and geometrical aspects of crack modeling, and how these aspects affect the database representation in the system, are addressed in the present discussion. The following are the innovative features of the present crack modeling approach: (a) crack simulation is done with a true geometric representation of the structure, via solid modeling; (b) crack modeling relies on the sophisticated, topology-based data structure of this system to support linkage to the solid model, fast interaction and accurate representation of evolving flaw shapes; (c) the system provides the ability to specify flaws of arbitrary shape (including non-planar flaws), size and orientation at arbitrary locations in the geometric model; (d) the flaw is specified at the desired location in the actual structure geometry, rather than at a location in the mesh; (e) the system uses all its automatic and local remeshing capabilities for the simulation of flaw initiation and growth.
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    Announcement (1993)
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    Engineering with computers 9 (1993), S. 124-124 
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    ISSN: 1435-5663
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
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    Agent-based framework for integrated facility engineering (1993)
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    Engineering with computers 9 (1993), S. 94-107 
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    ISSN: 1435-5663
    Keywords: Communications standards ; Integrated design environments ; Software integration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract An agent-based framework for the development of integrated facility engineering environments in support of collaborative design is introduced. This framework aims at integrating design software by allowing better software interoperability. Within their framework, design agents represent various existing design and planning systems that communicate their design information and knowledge partially and incrementally using the Agent Communication Language (ACL). ACL is a formal language proposed as a communication standard for disparate software. It is based on a logic-based language called Knowledge Interchange Format (KIF) and a message protocol called Knowledge Query Manipulation Language (KQML). Design agents are linked and their communication of design information is coordinated via system programs called facilitators in a federation architecture. The federation architecture specifies the way design agents and facilitators communicate in an integrated software environment. In concert with pursuing fundamental research concepts, we have been developing an integrated design software environment that spans different phases of the facility life cycle. This environment serves to demonstrate the primary aspects of this research methodology. In this paper, we first discuss the integration problem and review related research projects. We then present the major aspects of agent-based software engineering methodology and its application to integrated facility engineering. A highlight of the current integrated design environment development is given to illustrate the advantages of this approach. Finally, we summarize and discuss some of the important research issues in light of previous research.
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    An Object-Logic model for the representation and processing of design standards (1993)
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    Engineering with computers 9 (1993), S. 133-159 
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    ISSN: 1435-5663
    Keywords: Conformance checking ; Design standards ; Object-logic model ; Representation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract There are two distinct categories of knowledge in a design standard: (1) knowledge of the organization of design objects and (2) knowledge of the methods used in reasoning about the design objects. The object-oriented paradigm lends itself naturally to representing the organizational aspect of the design standard. The logic programming paradigm, on the other hand, is well suited to implementing the reasoning mechanisms for design and conformance checking. The object-oriented and logic programming paradigms are combined to provide a unified Object-Logic model for the representation of design codes and the processing of design standards. By storing the design provisions in a knowledge base, the model is capable of performing conformance checking and component design. To evaluate the feasibility and practicality of this model, a prototype system, HyperLRFD++, has been implemented for parts of the American Institute of Steel Construction (AISC) Load and Resistance Factor Design (LRFD) specification and tested on sample problems.
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    Development of the object-oriented finite element modeling system — MODIFY (1993)
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    Engineering with computers 9 (1993), S. 187-197 
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    ISSN: 1435-5663
    Keywords: CAD ; FEM ; Mesh generation ; Modeling ; Object-Oriented programming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract In this paper we present a new concept of FE modeling, based on the object-oriented principle, and develop the prototype program MODIFY (MODeling tool for Integrated Finite element analYsis). MODIFY has three novel features: (1) FE modeling by the part object concept, (2) a fully object-oriented data structure, and (3) a part-by-part fully automated mesh subdivision. When using MODIFY it is necessary to define and assemble part objects, which consist of geometry objects, analytical condition objects and relation objects, to describe the continuity between adjacent part objects. MODIFY automatically generates an appropriate FE model for each geometry object, satisfying continuity conditions with adjacent parts by referring to relation objects. If some part of the model is to be modified, the user needs only to change the corresponding part objects. Because of the object-oriented data structure, MODIFY also has a powerful capability for adaptive meshing. The existing version of MODIFY is applicable to FE models for3-D shell structures.
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    URL: http://dx.doi.org/10.1007/BF01201899
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    Low-degree approximation of high-degree B-spline surfaces (1993)
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    Engineering with computers 9 (1993), S. 198-209 
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    ISSN: 1435-5663
    Keywords: Data exchange ; Surface approximation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract In this paper, a method for approximate conversion of high degree Bezier and B-spline surfaces to lower degree representations is presented to facilitate the exchange of surface geometry between different geometric modeling systems. Building on previous work on curve approximation, the method uses adaptive sampling to compute approximation error and lofting of isoparametric curves to produce the approximating surface. In addition, a bound for the approximation accuracy is computed using convex hulls.
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    URL: http://dx.doi.org/10.1007/BF01201900
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    An integrated NMT-based CAE environment — Part I: Boundary-based feature modeling utility (1993)
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    Engineering with computers 9 (1993), S. 210-219 
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    ISSN: 1435-5663
    Keywords: Features ; Geometry-Based reasoning ; Geometry modeling utility ; Non-Manifold topology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The integration of CAD, CAM and CAE is far from a commercial reality. Feature technology has been identified as a key element in bridging many of the integration gaps. This two-part paper emphasizes an integrated NMT-based environment that serves the needs of both geometry and feature-based applications. Part I describes a feature modeling utility that coexists with commercial CAD systems by providing external feature-based functionality and making it available to application programs. A non-manifold topologybased system, called TAGUS, is used to represent the model geometry and provide the foundation for features representation. The architecture of a feature-based analysis system is described and, finally, the automated design of the feed system for injection molds is presented as an example to illustrate the application of the feature modeling utility. A detailed description of this application is the focus of the companion paper (Part II).
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    URL: http://dx.doi.org/10.1007/BF01201901
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    Computation of stationary points of distance functions (1993)
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    Engineering with computers 9 (1993), S. 231-246 
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    ISSN: 1435-5663
    Keywords: CAD ; CAGD ; CAM ; interrogation ; geometric modeling ; solid modeling ; intersection ; distance computation ; symmetry transforms ; robotics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This paper presents an algorithm for computation of the stationary points of the squared distance functions between two point sets. One point set consists of a single space point, a rational B-spline curve, or a rational B-spline surface. The problem is reformulated in terms of solution of n polynomial equations with n variables expressed in the tensor product Bernstein basis. The solution method is based on subdivision relying on the convex hull property of the n-dimensional Bernstein basis and minimization techniques. We also cover classification of the stationary points of these distance functions, and include a method for tracing curves of stationary points in case the solution set is not zerodimensional. The distance computation problem is shown to be equivalent to the geometrically intuitive problem of computing collinear normal points. Finally, examples illustrate the applicability of the method
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    URL: http://dx.doi.org/10.1007/BF01201903
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    Nippondenso Co. Ltd: A case study of strategic product design (1993)
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    Research in engineering design 5 (1993), S. 1-20 
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    ISSN: 1435-6066
    Keywords: Product design ; Assembly automation ; Concurrent engineering ; Japanese manufacturing methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Nippondenso Co. Ltd (NDCL) is Japan's foremost manufacturer of automotive components. Over the past twenty-five years it has developed a variety of approaches to automating the assembly of products in order to meet the high-variety, just-in-time production requirements of its customers, notably Toyota. The approach evolved by NDCL is to design the product intelligently and to make massive use of the simplest automation technology possible consistent with the technical challenges of the product and its production strategy. The result is the capability to manufacture products with considerable model mix at high volume, with little or no changeover time between models. This is essentially a technological response to a business environment challenge. In pursuit of this strategy, NDCL has categorized the problems of assembly automation into distinct classes, identified applicable solutions for each class, and successively attacked and solved increasingly difficult problems. This paper describes this strategy, gives examples of its evolution, and indicates how NDCL has managed production technology, notably robots, as part of the overall attack. NDCL's approaches to concurrent engineering (CE) and new product risk management are also described. The paper is based both on seven personal visits to NDCL during the period 1974 to 1991, which included extensive interviews with NDCL engineers and managers and plant tours, and on papers published by NDCL and interviews with their authors.
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    URL: http://dx.doi.org/10.1007/BF01608394
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    Conference announcements (1993)
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    Research in engineering design 5 (1993), S. 120-120 
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    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
    URL: http://dx.doi.org/10.1007/BF02032581
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    A framework for performance-based design (1993)
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    Research in engineering design 5 (1993), S. 105-118 
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    ISSN: 1435-6066
    Keywords: Axiomatic design ; Building design ; Decision-making ; Systems integration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The international competitiveness of the US construction industry is linked to its strategic ability to design and build quality projects. This means delivering facilities that satisfy all the needs of the client. Correct decision-making during design and construction planning is the best means for assuring a quality project. Performance-based design is a framework that enables the project team to approach the project delivery process systematically and provides basic principles for evaluating and comparing alternative solutions. The principles of axiomatic design (as previously advanced by Suh) and the concept of an interface index are key elements of the framework. Axiomatic design provides an operational structure for the design process as well as a set of basic principles or axioms for guiding each decision-maker. The interface index complements the design axioms by quantifying the effort associated with integrating the contributions of multiple decision-makers into a total system. Elements of the framework are demonstrated through application to an actual facility.
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    URL: http://dx.doi.org/10.1007/BF02032579
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    Special issue: Advances in representation and reasoning for mechanical CAD (1993)
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    Research in engineering design 5 (1993), S. 123-124 
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    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
    URL: http://dx.doi.org/10.1007/BF01608358
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    A knowledge-based approach to design for manufacturability (1993)
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    Journal of intelligent manufacturing 4 (1993), S. 355-366 
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    ISSN: 1572-8145
    Keywords: Manufacturability ; cost estimation ; knowledge-based systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In the light of growing global competition, organizations around the world today are constantly under pressure to produce high-quality products at an economical price. The integration of design and manufacturing activities into one common engineering effort has been recognized as a key strategy for survival and growth. Design for manufacturability (DFM) is an approach to design that fosters the simultaneous involvement of product design and process design. The implementation of the DFM approach requires the collaboration of both the design and manufacturing functions within an organization. Many reasons can be cited for the inability to implement the DFM approach effectively, including: lack of interdisciplinary expertise of designers; inflexibility in organizational structure, which hinders interaction between design and manufacturing functions; lack of manufacturing cost information at the design phase; and absence of integrated engineering effort intended to maximize functional and manufacturability objectives. The purpose of this research is to show how expert systems methodology could be used to provide manufacturability expertise during the design phase of a product. An object- and rule-based expert system has been developed that has the capability: (1) to make process selection decisions based on a set of design and production parameters to achieve cost-effective manufacture; and (2) to estimate manufacturing cost based on the identified processes. The expertise for primary process selection is developed for casting and forging processes. The specialized processes considered are die casting, investment casting, sand casting, precision forging, open die forging and conventional die forging. The processes considered for secondary process selection are end milling and drilling. The cost estimation expertise is developed for the die casting process, the milling and drilling operations, and the manual assembly operations. The results obtained from the application of the expert system suggest that the use of expert systems methodology is a feasible method for implementing the DFM approach.
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    URL: http://dx.doi.org/10.1007/BF00123780
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    Engineering applications of neural networks (1993)
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    Journal of intelligent manufacturing 4 (1993), S. 1-21 
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    ISSN: 1572-8145
    Keywords: Neural networks ; engineering applications ; adaptive control ; feature recognition ; design
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper describes several prototypical applications of neural network technology to engineering problems. The applications were developed by the authors as part of a graduate-level course taught at the University of Illinois at Urbana-Champaign by the first author (now at Carnegie Mellon University). The applications are: an adaptive controller for building thermal mass storage; an adaptive controller for a combine harvester; an interpretation system for non-destructive evaluation of masonry walls; a machining feature recognition system for use in process planning; an image classification system for classifying land coverage from satellite or high-altitude images; and a system for designing the pumping strategy for contaminated groundwater remediation. These applications are representative of many of the engineering problems for which neural networks are applicable: adaptive control, feature recognition, and design.
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    URL: http://dx.doi.org/10.1007/BF00124977
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    Neural architecture for robotic vision sensor that discounts uneven illumination in a manufacturing environment (1993)
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    Journal of intelligent manufacturing 4 (1993), S. 67-77 
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    ISSN: 1572-8145
    Keywords: Computer vision ; lightness constancy ; retina ; contrast sensitivity control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Computer vision algorithms for inspection or pick-and-place operations often depend on spatially uniform illumination of a workplace. This necessitates expensive lighting fixtures. To discount effects of uneven illumination we designed and tested a neural network that can adaptively control light sensitivity at the photosensor level. Our neural network architecture consists of multiple layers with hexagonally arranged nodes. All nodes have partially overlapping receptive fields of different spatial frequencies. Feedforward connections are excitatory while feedback pathways subserve lateral inhibition. The outputs of these nodes are combined so as to maximize the signal-to-noise ratio while constantly resetting thresholds to maintain high sensitivity. Our connectionist architecture can account for many characteristics attributed to the lightness constancy phenomenon observed in biological systems. The results suggest that our module maintains high sensitivity over the whole domain of intensities without interfering with transmission of visual information embedded in spatial discontinuities of intensity.
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    URL: http://dx.doi.org/10.1007/BF00124981
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    Intelligent data analysis systems (1993)
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    Journal of intelligent manufacturing 4 (1993), S. 121-137 
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    ISSN: 1572-8145
    Keywords: Data analysis ; knowledge-based systems ; SPC ; diagnosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A variety of approaches to the intelligent analysis of complex manufacturing data have been described in the literature. A comparative analysis of these systems reveals underlying similarities in their functional organizations. This leads to the development of a general functional model for intelligent data analysis (IDA). This article describes the various data analysis systems studied, the general model for IDA, and the implementation of a demonstration IDA system. The implementation serves to demonstrate the feasibility of this approach, and provides directions for further research.
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    URL: http://dx.doi.org/10.1007/BF00123906
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    Computer-aided design for manufacturing process selection (1993)
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    Journal of intelligent manufacturing 4 (1993), S. 199-208 
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    ISSN: 1572-8145
    Keywords: Concurrent engineering ; process selection ; expert system ; design compatibility analysis ; design for manufacture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper describes an expert system that helps designers select a manufacturing process in the early stage of product design. First, the paper focuses on net-shape manufacturing processes and identifies the major factors that affect the selection of an appropriate process. Examples of these factors include shape, production volume and material. A versatile methodology should consider all the factors simultaneously in assessing the suitability of the candidate processes. The proposed system uses the concept of design compatibility analysis to represent the suitability of candidate processes with respect to the given product specifications. The system uses this knowledge to eliminate incompatible candidates and rank the compatible set of processes. A prototype system called DFPS uses HyperCard and Prolog to implement the proposed methodology. DFPS also contains information related to each process.
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    URL: http://dx.doi.org/10.1007/BF00123964
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    Operation sequencing in an automated process planning system (1993)
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    Journal of intelligent manufacturing 4 (1993), S. 219-232 
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    ISSN: 1572-8145
    Keywords: Operation sequencing ; automated process planning ; object-oriented paradigm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: One of the most difficult tasks we face in automated process planning is determination of operation sequencing. In this paper we present an approach to automatic generation of machining sequences in an object-oriented automated process planning system. Sequencing of machining operations is carried out in three phases of planning: initial planning, set-up planning, and final planning. The initial planning generates general plans including the required operations and machine cells. Two types of information are used at this stage, manufacturing process knowledge and component information, including features and associated dimensions, tolerances, surface finish, and material conditions. Based on process requirements decided in the initial planning, the set-up planning selects machines and fixtures, decides the clamping surfaces and feature accessibility, and sequences the set-ups. The final planning determines all the detailed sequences of operations based on the set-ups using the built-in manufacturing logic and heuristics. We introduce the set-up planning, the core of the planning system, to link the part model, initial planning and final detailed planning. The strategy has been implemented in an object-oriented process planning system. An example is provided to demonstrate the approach.
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    URL: http://dx.doi.org/10.1007/BF00123966
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    Intelligent agent systems for manufacturing applications (1993)
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    Journal of intelligent manufacturing 4 (1993), S. 285-293 
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    ISSN: 1572-8145
    Keywords: Intelligent agents ; automated guided vehicles ; knowledge based systems manufacturing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Using the concept of intelligent agents, two system approaches are described for manufacturing applications. The first is based on the rule-based object (RBO) which is associated with a production-rules knowledge base and is implementable in an object-oriented development environment such as Smalltalk-80. A proof-of-concept automated guided vehicle (AGV) system of this kind has been recently developed. The second and more advanced approach is based on the intelligent agent object (IAO) and an AGV system of this kind is currently under development. This uses a multi-agent entity termed the modulon to handle more effectively both the co-operative planning task and the local route planning task.
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    URL: http://dx.doi.org/10.1007/BF00124141
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    Evaluation of flexible automation investments: a model management perspective (1993)
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    Journal of intelligent manufacturing 4 (1993), S. 307-322 
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    ISSN: 1572-8145
    Keywords: Flexible manufacturing systems ; flexible automation investments ; model management ; AMPL
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper develops a model management system structure to support the design and evaluation of flexible automation systems. A modeling language suitable for one of the important, but ill-structured phases in the evaluation process is selected and used to represent a mathematical programming formulation. The experience gained is then used to propose a meta-language approach for integrating different model types required when evaluating flexible automation investments.
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    URL: http://dx.doi.org/10.1007/BF00123777
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    Exploiting multiple knowledge models in the development of real-time diagnostic expert systems for highly automated manufacturing plants (1993)
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    Journal of intelligent manufacturing 4 (1993), S. 295-304 
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    ISSN: 1572-8145
    Keywords: Plant fault diagnosis ; real-time ; model-based reasoning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper describes the results of the DIREK Project (knowledge-based, real-time diagnosis and repair for a robotized handling and storage system), aimed at developing a real-time diagnosis system for a highly automated SNIA fibre spinning plant. The project effectively implemented a multi-model approach to diagnosis in manufacturing environments, exploiting structural, functional, behavioural and heuristic models. Among other things, particular emphasis has been placed on the plant behavioural model, which can be derived from the software code running on the PLCs which control an automated manufacturing facility. The existing diagnostic system is now operational at an SNIA plant in Italy, fully integrated with the factory environment and able to support different levels of users through distributed man-machine interfaces. The paper provides an insight into the theoretical background of the project and describes the adopted methodology, with special attention given to the knowledge acquisition problems arising in the development of the various knowledge models included in the diagnostic system. Furthermore, the architecture and functionalities of the existing system are described, along with the achieved benefits and further exploitation potential. Both IT and user perspectives are considered in the paper.
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    URL: http://dx.doi.org/10.1007/BF00124142
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    Intelligent monitoring of a frequency-trimming process (1993)
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    Journal of intelligent manufacturing 4 (1993), S. 375-383 
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    ISSN: 1572-8145
    Keywords: Process control ; fuzzy logic ; neural network ; frequency trimming ; crystal resonator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In the development of a process diagnostic system to monitor the condition of the frequency-trimming process in the production of crystal resonators, fuzzy logic can be applied in the recognition of unnatural statistical patterns in the control charts. The heuristics for reasoning are based on the principles behind statistical process control. Using expert experience and knowledge to troubleshoot the causes of problems, one can associate a characteristic chart pattern with a set of known physical causes. As these causes related to the unnatural statistical patterns are not independent of each other, it is difficult to precisely associate the chart distribution patterns with the known causes. Furthermore, as the trimming process is dynamic, the causes of problems dealt with will vary with time. Hence, by means of neural networks, it is possible to associate fuzzily deduced chart patterns with plausible causes to achieve optimum operating conditions.
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    URL: http://dx.doi.org/10.1007/BF00123951
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    A refined cost-based approach to assembly scheduling (1993)
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    Journal of intelligent manufacturing 4 (1993), S. 405-410 
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    ISSN: 1572-8145
    Keywords: Assembly scheduling ; inventory control ; just-in-time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Increased emphasis on control of work-in-process costs in assembly scheduling of large, complex items leads to increased needs for aids to foremen in dealing with schedule changes. The task is complicated by constraints on resources that often require that activities are begun earlier than a just-in-time schedule would otherwise dictate. A criterion used in prototype tandem knowledge-based decision-aiding systems in the past was based on the assumption that investment costs do not compound. This can provide misleading choices in some cases. The present work refines the criterion previously used by including the compounding costs of holding subassemblies in inventory. A simplified version of the new formula is developed which provides simple rules for deciding which activities to start early if necessary. Numerical comparisons are made between the criteria.
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    URL: http://dx.doi.org/10.1007/BF00123953
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    The episodal associative memory: Managing manufacturing information on the basis of similarity and associativity (1993)
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    Journal of intelligent manufacturing 4 (1993), S. 23-32 
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    ISSN: 1572-8145
    Keywords: Associative memory ; feature-based design
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this paper we report on continuing research on the organization and functionalities of a certain type of computer-implemented associative memory. The associative memory in question is being created to serve as part of a feature-based design system, at present to be used primarily in support of the design, fabrication planning, or inspection planning of discrete mechanical machine parts. This present effort is consonant with prior related work in the realm of case-based reasoning, especially as related to the role of memory in design. Our associative memory innovations are in the use of fuzzy sets and neural net computing in the representation, storage and retrieval of design, fabrication, inspection and materials knowledge. We have designed and implemented a considerable portion of the associative memory and have demonstrated retrieval of previous designs on the basis of qualitative geometry. We have also demonstrated ability to explore materials composition with the objective of meeting critical materials properties constraints.
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    URL: http://dx.doi.org/10.1007/BF00124978
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    Modeling workpiece vibrations with neural networks (1993)
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    Journal of intelligent manufacturing 4 (1993), S. 95-107 
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    ISSN: 1572-8145
    Keywords: Neural networks ; backpropagation neural network ; machine tool structures ; structural analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The entire workpiece on a lathe vibrates when it is excited at a single point. Frequency and time-domain/time-series techniques can estimate the force-displacement relationships between excitation and the individual points on the workpiece. In this paper, the use of single neural network is proposed to represent the force-displacement relationship between the applied excitation force and the vibration of the whole workpiece. The accuracy of the proposed approach is evaluated on the experimental data. Also, another neural network is used to store the frequency response characteristics of the workpiece.
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    URL: http://dx.doi.org/10.1007/BF00124983
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    Analysis of assembly operations difficulty: a fuzzy expert system approach (1993)
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    Journal of intelligent manufacturing 4 (1993), S. 411-419 
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    ISSN: 1572-8145
    Keywords: Fuzzy logic ; expert system ; design-for-assembly
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Typical mechanical products can be assembled in various sequences of assembly operations. These sequences have high impact on the assembly time, machine utilization and even on the product quality. In order to select the best sequence of assembly operations, proper evaluation of the various sequences of assembly operations is required. This, in turn, requires the consistent evaluation of each assembly operation in the sequence. The assembly operations can be evaluated for various criteria, of which the operation difficulty is the most meaningful. This paper describes a methodology to analyse the assembly operations and calculates an operation's degree of difficulty using an expert system. This analysis consists of two steps: the first one identifies the main parameters that affect the assembly difficulty and assigns fuzzy triangular values to these parameters. The second step assigns weights to the parameters in order to maximize the agreement with a domain expert. The expert system analyses the difficulty of the assembly operation performed in two orientations: horizontal and vertical. The expert system then assigns a triangular fuzzy number as the aggregate measure of the operation's difficulty.
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    URL: http://dx.doi.org/10.1007/BF00123954
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    Relating product specifications and performance data with a neural network model for design improvement (1993)
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    Journal of intelligent manufacturing 4 (1993), S. 367-374 
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    ISSN: 1572-8145
    Keywords: Neural networks ; product design ; sanitary ware manufacturing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper presents research resulting in a neural network model relating product design specifications and performance testing results using data from a sanitary ware manufacturer. The main constraint of the work was the limited availability of actual data for neural network training and testing, a situation often found in real situations where a priori product knowledge is limited during the product design phase. The authors used two training techniques, the standard hold-back and the leave-k-out, for the neural network model to leverage the sparseness of the data. Neural network results are compared and contrasted to statistical models relating product design and performance. This work is an exploration of the value of neural network models to assist with interactive product design.
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    URL: http://dx.doi.org/10.1007/BF00123950
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    Application of the artificial memory approach to multicriteria scheduling problems (1993)
    Springer
    Journal of intelligent manufacturing 4 (1993), S. 151-161 
    Details
    ISSN: 1572-8145
    Keywords: artificial memory ; simulation ; data analysis ; job-shop scheduling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper is devoted to the development of a knowledge-based system (KBS) called ‘Artificial Memory’, The goal of this KBS is to ‘solve’ multicriteria job-shop scheduling problems. Since job-shop scheduling problems are NP-hard, it is extremely difficult to obtain optimal solutions for industrial problems. Thus, a host of heuristic algorithms, most of which are based on priority rules, have been proposed in the literature. The efficiency of these algorithms strongly depends on the criteria to be optimized as well as the values of the parameters associated with the particular instance of the scheduling problem. The basic hypothesis of the artificial memory approach is a continuity assumption: we assume that identical decisions applied to similar instances lead to similar values of the criteria. This assumption is fundamental to validate this knowledge-based system. For each criterion, the artificial memory contains a synthesis of the performances of different algorithms upon sets of ‘similar’ instances. These performances are acquired using simulation. When the artificial memory is employed, the characteristic values of a new instance are computed and examined by the artificial memory system. The performances of the different algorithms for the considered criterion are estimated for the new instance and an appropriate algorithm is chosen accordingly. In order to build this KBS and to estimate the performances of algorithms upon a new instance, we use a mathematical approach. Some difficulties arose in the development of this KBS and had to be overcome: the corresponding proposed solutions are developed. The paper also presents a number of numerical experimental applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00123908
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    Graph-based recognition of morphological features (1993)
    Springer
    Journal of intelligent manufacturing 4 (1993), S. 209-218 
    Details
    ISSN: 1572-8145
    Keywords: CAD ; boundary model ; isomorphic graph ; feature recognition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Automatic recognition of the shapes of objects represented as solid models is very important in design optimization. Object shape also governs ease of manufacture, ease of orientability, field use and all other life-cycle applications. Characteristic attributes of an object shape such as chamfers, protrusions and depressions, play a significant role in process planning, design for manufacture, etc. These attributes are popularly known as morphological features. In this paper, the problem of identifying such morphological features is divided into two phases: the feature extraction phase and the feature classification phase. In feature extraction, the mechanical part is decomposed into its constituent features such as holes, protrusions and depressions based on the connectivity class in the edge-face graph of the part. In feature classification, on the other hand, the extracted features are identified and classified. This paper describes a feature classification scheme based on topological and geometric attributes of a morphological feature. The feature classification scheme outlined in this paper is capable of identifying new features with minimal human interface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00123965
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    Detection of small cracks in the chain of a trolley conveyor with an infrared camera (1993)
    Springer
    Journal of intelligent manufacturing 4 (1993), S. 259-267 
    Details
    ISSN: 1572-8145
    Keywords: chain ; crack ; high-frequency electric current heating ; infrared camera ; non-destructive inspection ; trolley conveyor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper describes the development of a non-destructive inspection method for cracks in a trolley conveyor chain, using a high-frequency electric current heater and an infrared radiation camera. This method is based on the idea that cracks affect heat conduction in the chain. When the chain is heated properly with the heater, variations in the heat conduction can be detected by monitoring the surface temperature of the chain with the infrared camera. The effectiveness of the proposed method is shown by a numerical analysis of the heat conduction in the chain. It is confirmed that the method is applicable to the chain which consists of portions with high and low emissivity, and that it is not affected by oil mixed with wear debris on the chain surface or by the operation speed of the conveyor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00124139
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    Automated generation of assembly sequence based on geometric and functional reasoning (1993)
    Springer
    Journal of intelligent manufacturing 4 (1993), S. 269-284 
    Details
    ISSN: 1572-8145
    Keywords: Process planning ; assembly ; sequence generation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Computer-aided process planning forms a vital link in the realization of a completely automated manufacturing environment. This paper addresses issues related to automatically generating assembly sequences from the geometric description of part components. Determination of assembly sequence depends on physical characteristics of the components, and their relative position in the final assembly, in order to accomplish functional goals of the assembly. A knowledge-based architecture for extracting and representing explicit interface information between part components, with minimal expert interaction, is presented in this paper. The concept of articulation points is used to decompose the complete assembly into constituent subassemblies. Finally, a feasible sequence is generated for each subassembly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00124140
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    Developing empirical models from observational data using artificial neural networks (1993)
    Springer
    Journal of intelligent manufacturing 4 (1993), S. 33-41 
    Details
    ISSN: 1572-8145
    Keywords: Neural networks ; empirical modeling ; process modeling ; machining modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Computer-integrated manufacturing requires models of manufacturing processes to be implemented on the computer. Process models are required for designing adaptive control systems and selecting optimal parameters during process planning. Mechanistic models developed from the principles of machining science are useful for implementing on a computer. However, in spite of the progress being made in mechanistic process modeling, accurate models are not yet available for many manufacturing processes. Empirical models derived from experimental data still play a major role in manufacturing process modeling. Generally, statistical regression techniques are used for developing such models. However, these techniques suffer from several disadvantages. The structure (the significant terms) of the regression model needs to be decided a priori. These techniques cannot be used for incrementally improving models as new data becomes available. This limitation is particularly crucial in light of the advances in sensor technology that allow economical on-line collection of manufacturing data. In this paper, we explore the use of artificial neural networks (ANN) for developing empirical models from experimental data for a machining process. These models are compared with polynomial regression models to assess the applicability of ANN as a model-building tool for computer-integrated manufacturing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00124979
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  • 99
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    Process monitoring using auto-associative, feed-forward artificial neural networks (1993)
    Springer
    Journal of intelligent manufacturing 4 (1993), S. 79-94 
    Details
    ISSN: 1572-8145
    Keywords: Neural networks ; condition monitoring ; resistance welding ; acoustic emission
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The potential of using artificially simulated neural networks as intelligent, adaptive process-monitoring devices is discussed. The investigation is considered as a method for automatic, intelligent exception reporting for quality control applications. The technique is also compared with the conventional statistical approaches of principal component analysis and Kohonen's feature map. The applications of the technique in aerospace and manufacturing environments are presented and a possible extension of the method to incorporate a diagnostic function is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00124982
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  • 100
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    An object-oriented architecture for knowledge-based production scheduling systems (1993)
    Springer
    Journal of intelligent manufacturing 4 (1993), S. 139-150 
    Details
    ISSN: 1572-8145
    Keywords: Object-oriented programming ; production scheduling ; knowledge-based systems ; software architecture ; wafer testing ; discrete event simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper describes an object-oriented architecture to support decision making in production scheduling environments. An object-oriented world view is used to integrate concepts from discrete event simulation, conventional scheduling logic and artificial intelligence to produce capacity-feasible schedules. The architecture was implemented as a collection of loosely coupled reusable software objects by extending the functionality of software objects from BLOCS/M (Berkeley Library of Objects for Control and Simulation of Manufacturing). Our experience with an industrial prototype is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00123907
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