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  • 1
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 269-273 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: The rate of vapor-development of poly(olefin sulfones) subjected to electron beam irradiation is markedly, dependent upon the olefin structure. At room temperature, poly(butene-1sulfone) and poly(cyclopentene sulfone) vapor-develop at rates several orders of magnitude lower than, for example, poly(2-methyl pentene-1 sulfone). Differences in vapor development rate for the various sulfones are shown to be related to differing rates of depolymerization which, in turn, are related to differences in ceiling temperatures for polymer formation. Kinetic analysis indicates that the mechanism involves random scission followed by depropagation and bimolecular termination.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 227-241 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Distortion of bars injection-molded from polystyrene, polypropylene, and glass-fiber-filled polypropylene and subsequently placed in a temperature gradient has been examined. Residual stress distributions have been measured both for the as-molded state and after annealing in a temperature gradient. In the as-molded state all moldings showed the usual residual stress distribution with compressive stresses near the surface and tensile stresses in the interior. In all three materials it was found that tensile stresses could be developed near to the warmer surface on gradient annealing and that tensile stresses still remained at this surface when the bar was cooled and permitted to bend to restore internal equilibrium. It is shown therefore that in addition to the dimensional changes which occur and which may render the molding unserviceable after temperature gradient annealing, another undesirable change takes place, leaving the molding much more susceptible to fracture from a surface flaw. Uniform annealing is found to be much less likely to cause stress reversal and the stresses remain balanced so that distortion is minimal.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 529-533 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: A class of negative electron-beam resists is described which have excellent lithographic characteristics. The resists are copolymers of glycidyl methacrylate and ethyl acrylate. Their molecular weights, epoxy contents, and polydispersivities can be controlled to give an adjustable range of electron sensitivity and contrast. The copolymers are compared to other epoxy containing, negative electron-beam resists.Micrography of resist profiles generated from a single line scan of the electron beam have been used to illustrate the complex interaction of accelerating voltage of the electron beam and resist contrast on resolution. Optical gratings made from single line scans of the beam have feature sizes less than 300 nm in the resist, etched metals, and dielectrics.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 32 (1992), S. 1476-1480 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: The X-ray and deep UV radiation response is described for resist systems consisting of poly(4-tert-butoxycarbonyloxystyrene-co-sulfur dioxide) PTBSS combined with an arylmethyl sulfone. A 2:1 4-tert-butoxycarbonyloxystyrene (TBS): sulfur dioxide (SO2) resist has been found to function as a highly sensitive, 1.4 nm X-ray, single-component, chemically amplified resist. The same resist, however, exhibits reduced sensitivity to 0.8 nm X-rays and deep UV (248 nm) radiation. Improvement in 0.8 nm X-ray sensitivity is achieved by the addition of 12 mol% bis(3,4-dichlorobenzyl) sulfone (DCBS) to the 2:1 TBS:SO2 resist. For this two-component resist formulation, the 0.8 nm X-ray sensitive improved from 〉375 to 125 mJ/cm2. Similarly, the sensitivity of the 3:1 TBS:SO2 copolymer to deep UV radiation improves to 40 mJ/cm2 with addition of 10 mol% DCBS. Sulfones, such as DCBS, provide two-component resist formulations capable of 〈0.5 μm resolution.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 525-528 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Poly(2-methyl pentene-1) sulfone undergoes scission followed by rapid chain depolymerization when irradiated with 5-20 kV electrons. Several parameters which affect the rate of this process, termed vapor development, were evaluated, viz., molecular weight, dose rate, temperature, accelerating voltage and film thickness. While it was never really possible to remove 100 percent of the film, it was possible to remove 〉 99 percent at reasonably low doses (∼ 10-6 coul/cm-2) using high temperatures (∼ 100°C) and low accelerating voltage (5 kV). Some lithographic details of this process are also described.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 39 (1993), S. 1569-1573 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 1328-1340 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We present a method for synthesizing chemical process models that combines prior knowledge and artificial neural networks. The inclusion of prior knowledge is investigated as a means of improving the neural network predictions when trained on sparse and noisy process data. Prior knowledge enters the hybrid model as a simple process model and first principle equations. The simple model controls the extrapolation of the hybrid in the regions of input space that lack training data. The first principle equations, such as mass and component balances, enforce equality constraints. The neural network compensates for inaccuracy in the prior model. In addition, inequality constraints are imposed during parameter estimation. For illustration, the approach is applied in predicting cell biomass and secondary metabolite in a fed-batch penicillin fermentation. Our results show that prior knowledge enhances the generalization capabilities of a pure neural network model. The approach is shown to require less data for parameter estimation, produce more accurate and consistent predictions, and provide more reliable extrapolation.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 43 (1997), S. 1377-1389 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Network models are an effective means of incorporating pore-scale heterogeneity into flow models of porous materials. The drawback to these models used to be the inability to obtain quantitative macroscopic parameters representing larger (experimental-scale) media. However, recently developed modeling techniques, combined with more widely available computational resources, make the simulation of macroscopic parameters from a network approach viable. A network model for the slow flow of an incompressible fluid in disordered packed beds is presented. Fundamental fluid mechanics equations are solved at the pore scale and then translated to macroscopic behaviour using a network approach. The results reproduce experimental permeabilities and show excellent quantitative fits to residence time distributions for mechanical dispersion in real beds. Simulations of the RTD are of special interest, because they are definitive links between pore-scale flow behavior and macroscopic responses.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 35 (1989), S. 109-119 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bimetallic Mo-Fe and Mo-Co sulfide clusters were anchored on Al2O3 and used for CO hydrogenation. In addition to methane, significant amounts of dimethyl ether were produced. The reaction orders obtained from power rate laws for methanation indicated that the surfaces of the catalytic ensembles were not completely saturated by CO, in contrast to the observations for most conventional CO hydrogenation catalysts. A kinetic analysis and parameter estimation was performed to identify the rate-determining step for methanation. A catalytic cycle was postulated that could account not only for the formation of methane and higher hydrocarbons, but also for dimethyl ether as a primary product.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 18 (1972), S. 941-948 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The paper reports efforts to automate the synthesis of separation processes. Heuristic and algorithmic programming are used to select both the sequence and types of processes used for the conversion of complex mixtures into specified products. Improved schemes are evolved using learning techniques. An illustrative example is included.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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