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  • 1990-1994  (11)
  • 1950-1954
  • 1993  (11)
  • Polymer and Materials Science  (6)
  • Cell & Developmental Biology  (3)
  • planning  (2)
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  • 1990-1994  (11)
  • 1950-1954
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Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Developing manufacturing control software: A survey and critique (1993)
    Springer
    International journal of flexible manufacturing systems 5 (1993), S. 53-88 
    Details
    ISSN: 1572-9370
    Keywords: manufacturing control software ; software methodologies ; planning ; scheduling ; monitoring ; simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The complexity and diversity of manufacturing software and the need to adapt this software to the frequent changes in the production requirements necessitate the use of a systematic approach to developing this software. The software life-cycle model (Royce, 1970) that consists of specifying the requirements of a software system, designing, implementing, testing, and evolving this software can be followed when developing large portions of manufacturing software. However, the presence of hardware devices in these systems and the high costs of acquiring and operating hardware devices further complicate the manufacturing software development process and require that the functionality of this software be extended to incorporate simulation and prototyping. This paper reviews recent methods for planning, scheduling, simulating, and monitoring the operation of manufacturing systems. A synopsis of the approaches to designing and implementing the real-time control software of these systems is presented. It is concluded that current methodologies support, in a very restricted sense, these planning, scheduling, and monitoring activities, and that enhanced performance can be achieved via an integrated approach.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01328739
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  • 2
    Electronic Resource
    Electronic Resource
    A specification language for planning and fault recovery in manufacturing systems (1993)
    Springer
    International journal of flexible manufacturing systems 5 (1993), S. 209-253 
    Details
    ISSN: 1572-9370
    Keywords: specification languages ; planning ; fault recovery ; manufacturing software
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper presents the syntax and semantics of a component-oriented rule-based language for specifying the formal models of manufacturing systems. A model captures the state of a component of the system in a set of first-order logic predicates, and it captures the semantics of the operations performed by this component in a set of rules that determine the preconditions and postconditions of an operation. The models are then used to plan the sequence of operations of each class of jobs to be manufactured by these systems. A plan-oriented fault detection and correction strategy is proposed. This strategy can automatically handle any combination of faults that may occur when monitoring the operations of manufacturing systems. A fault-tree is consulted prior to executing the scheduled operations of a plan, and the faults that affect the execution of these operations are handled subsequently. Resuming the original cyclic schedule is attempted, whenever feasible. As a proof of concept, a prototype implementation of both the main constructs of the component-oriented rule-based language and the planning and fault-recovery algorithms presented in this paper have been completed. This prototype is implemented on a Unix-based system in the Ada programming language. The specification of a manufacturing system is first expressed in the proposed language. These statements are then translated into Ada code. This code is next compiled by a Verdix Ada compiler and is executed in order to create and populate the model data structure of the system. A detailed plan of execution and a set of fault-recovery plans may then be derived for a job to be manufactured on this system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01328742
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  • 3
    Electronic Resource
    Electronic Resource
    Dynamic rheo-optical characterization of a low-density polyethylene/perdeuterated high-density polyethylene blend by two-dimensional step-scan FTIR spectroscopy (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 1769-1777 
    Details
    ISSN: 0887-6266
    Keywords: FT-IR ; step-scan interferometry ; 2D-IR ; polyethylene ; rheo-optical characterization ; time-resolved vibrational spectroscopy ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dynamic mechanical analysis coupled with polarized step-scan FTIR transmission and two-dimensional correlation analysis (2D FTIR) has been used to monitor the submolecular orientational responses of the components of a semicrystalline 50 : 50 blend of low-density polyethylene (LDPE) and perdeuterated high-density polyethylene (d*-HDPE) to a small amplitude uniaxial 23.47 Hz sinusoidal mechanical strain. Perdeuteration of the HDPE component allowed the distinction of its response from that of the LDPE in the blend samples. The experiments were carried out at room temperature. Analysis of the data indicates that the crystalline parts of the two components reorient at different rates, with the functional groups of the high-density portion reorienting faster, in general, than those of the LDPE in response to the mechanical strain. © 1993 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1993.090311210
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  • 4
    Electronic Resource
    Electronic Resource
    Viscosity, yield stress, slip, and natural convection of HSPAN gel-water dispersions (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 48 (1993), S. 625-637 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Three hydrolyzed-starch-polyacrylonitrile (HSPAN) copolymer materials tested as gel-water dispersions in a Brookfield rotating spindle viscometer exhibited velocity slip at solid boundaries and a yield stress. Dispersions with 0.5% HSPAN concentrations were about 20,000 times more viscous than water when the shear stress surpassed the yield stress and viscous power-law flow ensued. The apparent viscosity of an HSPAN gel-water dispersion was reduced by nearly an order of magnitude when tap water was substituted for deionized water. The apparent viscosity of the HSPAN gel-water dispersions decreased by about 30% after the fluid was continuously maintained at a temperature of 80°C for 1 week, and by an order of magnitude or more after 3 weeks under those conditions. In natural convection tests, the yield stress enabled an HSPAN gel-water dispersion to withstand greater temperature differences across a horizontal layer before inception of natural convection than a fluid without one. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070480406
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  • 5
    Electronic Resource
    Electronic Resource
    Dielectric and morphological investigations of phase separation and cure in rubber-modified epoxy resins: Comparison between teta- and DDM-based systems (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 47 (1993), S. 2037-2051 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Real-time and equilibrium dielectric measurements, covering the frequency range 10-1-105 Hz, are reported on a series of rubber-modified epoxy resins, based on reaction of the diglycidyl ether of bisphenol A (DGEBA) with either triethylenetetramine (TETA) or diaminodiphenylmethylene (DDM). The rubber modifier used was a carboxyl-terminated butadiene acrylonitrile (CTBN) reactive oligomer and the phase-separated structure, the results of which was examined using both dielectric and electron microscopic techniques. The mixture was initially homogeneous, but after a short period of time, it underwent phase separation and this process was marked by the appearance of a dielectric peak associated with ion-charge migration within the occluded rubbery phase. Analysis of the peak provided information on the morphology of the system and these data were compared with information obtained from scanning electron microscopy. A phase-separated morphology was observed consisting of spherical rubber particles dispersed in an epoxy matrix. For high concentrations of rubber ≥ 10 wt %, precipitation of epoxy domains within the rubbery phase was observed. Detailed dielectric studies of the peak associated with phase separation revealed that in the case of the TETA system the peak continued to shift after vitrification, whereas in the case of DDM, it was invariant with time. The point at which the peak appears was used to determine the time at which phase separation occurred. Differences observed in the lower temperature dielectric spectra were associated with variations in the form of the phase structure and possibly reflect different degrees of densification of the matrix. Good agreement was observed between the predictions of the Maxwell - Wagner - Sillers (MWS) theory and experimental observation for these systems. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070471114
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  • 6
    Electronic Resource
    Electronic Resource
    A Monte-Carlo study of ring formation during step-growth polymerization in three dimensions (1993)
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Theory and Simulations 2 (1993), S. 91-94 
    Details
    ISSN: 1018-5054
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The formation of ring and chain molecules during an irreversible step-growth polymerization has been modelled on a three-dimensional twenty six choice cubic lattice, and examined by the Monte-Carlo method. Movements were not allowed in the system in this preliminary study. The limiting value of the extent of reaction was found to be p = 0,9837 (±0,0003), and the number fraction of molecules found to be rings was 0,300 (±0,045), but the weight fraction was much smaller, 0,056 (±0,005).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mats.1993.040020107
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  • 7
    Electronic Resource
    Electronic Resource
    Induction of neuronal differentiation by planar signals in Xenopus embryos (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Developmental Dynamics 197 (1993), S. 268-280 
    Details
    ISSN: 1058-8388
    Keywords: Planar signals ; Neural induction ; Xenopus ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The induction of the central nervous system in amphibian embryos is mediated both by early planar signals produced by mesoderm at the dorsal lip and later vertical signals emanating from the dorsal mesoderm after involution. We have examined the role and spatial extent of planar signals in the induction of neuronal differentiation. Planar explants that included only the deep layer of the dorsal marginal zone, comprising both the dorsal mesoderm and the contiguous dorsal ectoderm, were isolated at the beginning of gastrulation. After removal of the epithelial layer, explants were maintained in modified Danilchik's medium until mid-neurula stages, when they were transferred to modified Danilchik's medium + 0.1% bovine serum albumin and cultured on laminin. Neurite outgrowth occurred in 90% of these planar explants. In contrast, little or no neuronal differentiation occurred in either ventral planar explants or explants of ectoderm alone. Video analysis of cell movements shows that large-scale cell mixing does not occur between mesoderm cells and ectoderm cells in planar explants. Retrograde labelling of neuronal cell bodies indicates that cells throughout the ectoderm undergo neuronal differentiation; neurons also differentiate in cultures of distal ectoderm isolated at early neurula stages from planar explants prepared at the beginning of gastrulation. These observations indicate that planar signals act over an extended range to induce neuronal differentiation. The inductive capacity of vertical signals was examined by recombining animal caps from ultra-violet (UV) irradiated embryos with involuted mesoderm from normal midgastrula embryos. Differentiation of either neurons or anterior neural structures occurred in 73% of vertical recombinates. Our results demonstrate that planar signals from the dorsal lip of the blastopore are capable of inducing neuronal differentiation over a considerable distance in the absence of epithelial confinement, convergence and extension, and mixing between the mesoderm and ectoderm. © 1993 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001970405
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of interfacial variables on metal-porcelain bonding (1993)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 27 (1993), S. 531-537 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: While ceramic-to-metal bonding has been used in many applications, the actual chemical and physical factors leading to optimum bond strength are not well understood. In this work, several variables affecting the bonding between dental porelain and a palladium alloy (85% Pd, 10% Cu, and 5% Ga) were investigated: (1) precoating the metal by sputtering various oxides before porcelaining; (2) preoxidation of the metal base before porcelaining; (3) porcelaining under reducing atmosphere; and (4) surface roughening at controlled levels before porcelaining.Using a modification of the push doughnut shear bond strength test to measure bond strength the following results were obtained. (1) Compared with standard “control” samples, the aluminum oxide precoated precoated specimens showed a bond strength improvement of 46%, while the copper, manganese, and tin oxide precoatings exhibited smaller effects. (2) Preoxidation of the metal base led to pronounced bond strengthening (152%) by surface roughening as well as oxide formation. (3) Porcelaining under a reducing atmosphere severely reduced bond strength (88% lower than the controls) indicating the role of oxidation during the standard firing cycle. (4) Mechanical roughening of the surface by controlled amounts gave pronounced improvements with greater notch depth. Coarse roughening produced the highest bond strength improvements (486%). © 1993 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820270414
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  • 9
    Electronic Resource
    Electronic Resource
    Quantitative thin-film analysis with an energy-dispersive x-ray detector (1993)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 20 (1993), S. 111-114 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Recent mathematical approximations of φ(ρz), the depth distribution of electron-excited x-rays, have opened up the possibility of accurate quantitative analysis of thin-film specimens by electron beam techniques. This method has been used extensively in electron probe microanalysis. This paper demonstrates quantitative analyses of thin films using energy-dispersive x-ray analysis (EDS) coupled with the φ(ρz) method. Metal and oxide films were analyzed by several techniques, including electron probe microanalysis (EPMA), Rutherford backscattering spectroscopy (RBS), x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), spectroscopic ellipsometry (SE) and x-ray fluorescence spectroscopy (XRF); the results were compared with those obtained from the EDS thin-film analysis. In the case of Al2O3 films, EDS film thickness results agree to within ±4%, ±7% and ±9% of the TEM, EPMA and SE results, respectively. For metal films, the EDS results agree to within ±12% (thicknesses) and ±7% (composition) of the RBS, EPMA and XRF results.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740200204
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  • 10
    Electronic Resource
    Electronic Resource
    What the papers say: Cellular dedifferentiation and spore germination in Dictyostelium may utilize similar regulatory pathways (1993)
    New York, NY : Wiley-Blackwell
    BioEssays 15 (1993), S. 131-133 
    Details
    ISSN: 0265-9247
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cellular dedifferentiation is an important developmental response to perturbations in morphogenesis. In the cellular slime mold Dictyostelium discoideum this process gives cells the flexibility, when multicellular development is disrupted, to respond to nutrients and reinitiate vegetative growth. Recent studies in D. discoideum described by Soll and colleagues(1) show that genes previously thought to be expressed only during spore germination are also expressed during induced dedifferentiation, suggesting that similar molecular mechanisms are involved in these two developmental processes. It should now be possible to determine whether the developmental programs that control dedifferentiation during spore germination also control conversion of cell types in the multicellular organism.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bies.950150210
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