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  • Polymer and Materials Science  (5)
  • Engineering  (3)
  • 1
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 9 (1965), S. 3427-3437 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: It was shown that the shape of the scattering pattern is not only related to the shape but also to the face-orientation of the lamellar scattering units, and an actual observation of its characteristic shape depends on the amount and dispersion of their spiral angle. The following results were obtained: (1) For observing a cross-pattern, the critical spiral angles corresponding to minimum and maximum dispersions are 7.5° and 30° respectively, whereas in an actual fiber, coir, the critical angle is about 16.75°. (2) The jute pattern changes from a uniformly narrow to a triangular shape on disorientation and reverts to the former on reorientation. The corresponding changes in ramie are from a triangular to a uniformly wide and then to a uniformly narrow shape. Both native and disoriented cottons give weak, fan-shaped scattering superimposed on a more intense elliptical pattern. The pattern given by reoriented cotton is roughly a narrow streak. Delignified jute gives a somewhat shaving-brush-shaped pattern which changes to a uniformly wide streak on alkali treatment. (3) The extent of scattering decreases on swelling and increases on stretching in jute, ramie, and cotton, but decreases in stretched coir.
    Zusätzliches Material: 25 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 0887-624X
    Schlagwort(e): photopolymerization ; photoinitiator ; aroyl xanthates ; methyl methacrylate ; laser flash photolysis ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A new sulfur-containing photoinitiator, S-benzoyl O-ethyl xanthate (2) has been prepared and used for the photopolymerization of methyl methacrylate (MMA). The photoinitiation property of 2 has been examined by conventional polymerization methods and nanosecond laser flash photolysis studies. Upon 308 nm laser pulse excitation, 2 gave rise to transients with absorption maxima at 350 and 650 nm, assigned to the benzoyl radical (3) and (ethoxythiocarbonyl)thiyl radical (4), respectively, on the basis of their quenching by nitroxy radicals and spectral similarity to analogous species, reported in the literature. © 1993 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 12 (1996), S. 657-671 
    ISSN: 1069-8299
    Schlagwort(e): continuous casting ; free boundary problem ; co-ordinate transformation ; solidification front ; non-orthogonal control volume ; temperature profile ; Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: An efficient computational simulation scheme based on non-orthogonal control volume discretization and co-ordinate transformation techniques has been developed for solving the thermal transport phenomena, which involves tracking of the interface between solid and liquid phases (solidification front) and evaluation of the temperature profile during continuous casting operation. Conservation equations are reformulated in differential-integral form in terms of the transformed co-ordinates. All the terms arising from the non-orthogonality of the control volume have been retained in the numerical solution methodology, and a front tracking procedure has been formulated based on an iterative solution scheme. The formulation has been applied to solve the thermal transport phenomena in solidification processing of an A1-Mg alloy cylindrical ingot during continuous casting, which also includes axial conduction of heat. Theoretical evaluation of the solidification front and temperature distribution in the ingot are in good agreement with the experimentally measured data.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 1617-1622 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Polystyrene xanthates, prepared through the reaction of chloromethylated polystyrene resins with potassium O-ethyl xanthate, have been used for the photografting of acrylic monomers. Monomers such as acrylamide, acrylic acid, methacrylic acid, and methyl methacrylate were grafted onto the xanthate polymers on irradiation with a 450 W medium-pressure mercury lamp (Hanovia). Among these monomers, the maximum graft efficiency was obtained for methyl methacrylate. The effect of cross-link density of the xanthate polymer on the percentage graft yield was also studied. Scanning electron microscopic studies have shown that appreciable grafting has taken place on the surface of the polymer in a uniform manner. © 1992 John Wiley & Sons, Inc.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 9 (1965), S. 3439-3450 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: It was shown that the realization of a straight log I-h2 curve may be a coincidence depending on the relative influence of heterogeneity of distribution and non-independent scattering, and a concave log I-h2 curve can represent a nonhomogeneous system amenable to Shull and Roess's method of analysis. The results indicate: (1) The I-h curve for a jute holo-cellulose film has a maximum, and that for a ramie film an inflexion point, each superimposed on a background of gradually declining intensity, and in either case the singularity is accentuated and shifted to a region of larger angle on alkali-treatment. (2) The log I-h2 plots for untreated, alkali-treated and stretched jute fibers give straight sections in the low-angle, and convex, concave, and straight sections, respectively, in the high-angle region. An interesting feature of the results for ramie is the realization of a straight logarithmic curve on mercerization. The curves for alkali-treated and stretched Fortisan fibers have also each of them two discernible linear parts, indicative of two groups of scatterers. (3) An evaluation of the log I-log h2 curves by Shull and Roess's method leads to figures for the diameters of the scattering elements in ramie comparable to those estimated from the corresponding log I-h2 plots.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 15 (1992), S. 313-327 
    ISSN: 0271-2091
    Schlagwort(e): Numerical tidal model ; Data assimilation ; Parameter estimation ; Optimal control ; Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Maschinenbau
    Notizen: It is shown that the parameters in a two-dimensional (depth-averaged) numerical tidal model can be estimated accurately by assimilation of data from tide gauges. The tidal model considered is a semi-linearized one in which kinematical non-linearities are neglected but non-linear bottom friction is included. The parameters to be estimated (bottom friction coefficient and water depth) are assumed to be position-dependent and are approximated by piecewise linear interpolations between certain nodal values. The numerical scheme consists of a two-level leapfrog method. The adjoint scheme is constructed on the assumption that a certain norm of the difference between computed and observed elevations at the tide gauges should be minimized. It is shown that a satisfactory numerical minimization can be completed using either the Broyden-Fletcher-Goldfarb-Shanno (BFGS) quasi-Newton algorithm or Nash's truncated Newton algorithm. On the basis of a number of test problems, it is shown that very effective estimation of the nodal values of the parameters can be achieved provided the number of data stations is sufficiently large in relation to the number of nodes.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 18 (1994), S. 295-312 
    ISSN: 0271-2091
    Schlagwort(e): Variational data assimilation ; Parameter estimation ; Numerical tidal model ; Eddy viscosity ; Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Maschinenbau
    Notizen: It is shown that the eddy viscosity profile in a quasi-three-dimensional numerical tidal and storm surge model can be estimated by assimilation of velocity data from one or more current meters located on the same vertical line. The computational model used is a simplified version of the so-called vertical/horizontal splitting algorithm proposed by Lardner and Cekirge. We have estimated eddy viscosity both as a constant and as a variable parameter. The numerical scheme consists of a two-level leapfrog method to solve the depth-averaged equations and a generalized Crank-Nicolson scheme to compute the vertical profile of the velocity field. The cost functional in the adjoint scheme consists of two terms. The first term is a certain norm of the difference between computed and observed velocity data and the second term measures the total variation in the eddy viscosity function. The latter term is not needed when the data are exact for the model but is necessary to smooth out the instabilities associated with ‘noisy’ data. It is shown that a satisfactory minimization can be accomplished using either the Broyden-Fletcher-Goldfarb-Shanno (BFGS) quasi-Newton algorithm or Nash's truncated Newton algorithm. Very effective estimation of eddy viscosity profiles is shown to be achieved even when the amount of data is quite small.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Acta Polymerica 41 (1990), S. 166-169 
    ISSN: 0323-7648
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Die bei Anwendung der PALIT-Beziehung 100ϱ0[η] + In M = K1M2/3 + K2 auf Lösungen einiger Polyphosphate und Copolyphosphate erhaltenen Ergebnisse wurden analysiert und mit der MARK-HOUWINK-Beziehung verglichen. Die Werte des Exponenten a in der MARK-HOUWINK-Beziehung sind für die Proben größer, die größere Werte K1 oder Kleinere Werte K2 in der von PALIT vorgeschlagenen Gleichung ergeben.
    Notizen: The results obtained by testing the PALIT equation 100ϱ0[η] + In M = K1M2/3 + K2 with solutions of some polyphosphates and copolyphosphates have been analyzed and compared with the MARK-HOUWINK relationship. The values of the exponent a in the MARK-HOUWINK relationship were found to be higher for those samples which have higher values of K1 or lower values of K2 in the equation suggested by PALIT.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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