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  • 1980-1984  (4,036)
  • Physics  (2,657)
  • Engineering  (1,378)
  • Nuclear reactions
  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984) 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 1-12 
    ISSN: 0271-2091
    Keywords: Review ; Finite Elements ; Meteorology ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The application of the finite-element method to the simulation of meterological fluid flow problems is reviewed. Early studies were aimed primarily at demonstrating the viability of the method for one- and two-dimensional flows, whereas more recent studies have been aimed at demonstrating the efficiency and viability of the method for more complex three-dimensional simulations. There has also been a shift towards exploiting such models to better understand and predict the underlying meteorological phenomena, rather than restricting attention to the development of the algorithms.
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 105-105 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 147-158 
    ISSN: 0271-2091
    Keywords: Finite Element ; Incompressible Flow ; Pressure-specification-point ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The discontinuity of a finite-element pressure field that is sometimes present in the neighbourhood of the pressure-specification-point is shown to arise either from round-off, or from mistakes in modelling. The implications of this are considered. In particular it restricts grid refinement near the pressure-specification-point. The analysis can be extended to finite-difference calculations, and to other fields governed by equations similar to Poisson's equation.
    Additional Material: 6 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 109-125 
    ISSN: 0271-2091
    Keywords: Finite elements ; Navier-Stokes ; Vorticity-stream function ; Time-dependent ; flows ; Boundary conditions ; Incompressible viscous flows ; Two-dimensional flows ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A new finite element method for solving the time-dependent incompressible Navier-Stokes equations with general boundary conditions is presented. The two second-order partial differential equations for the vorticity and the stream function are factorized, apart from the non-linear advection term, by eliminating the coupling due to the double specification on the stream function at (a part of) the boundary. This is achieved by reducing the no-slip boundary conditions to projection integral conditions for the vorticity field and by evaluating the relevant quantities involved according to an extension of the method of Glowinski and Pironneau for the biharmonic problem. Time integration schemes and iterative algorithms are introduced which require the solution only of banded linear systems of symmetric type. The proposed finite element formulation is compared with its finite difference equivalent by means of a few numerical examples. The results obtained using 4-noded bilinear elements provide an illustration of the superiority of the finite element based spatial discretization.
    Additional Material: 7 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984) 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0271-2091
    Keywords: Polymer Flows ; Non-Newtonian ; Moving Boundary ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Recent progress in the simulation of polymeric flows of two key problems in the injection moulding process, carried out by a team at Cornell University, is briefly described. For the filling of cooled thin cavities, the fluid is characterized by a power-law viscosity with exponential temperature dependence, and interaction between the transient thermal boundary-layer and the core flow in a domain with moving boundary is essential. The earlier procedure of Hieber and Shen is modified in two aspects: a boundary-integral formulation replaces the finite-element treatment of the pressure, and an ‘energy integral’ approach is used for the transient temperature. The second problem is the steady visco-elastic flow in the juncture region where sudden changes of the geometry and large strain rates occur. The constitutive equation is postulated according to the Leonov model. The main features in the numerical implementation are: integration along a streamline to determine the elastic deformation tensors for a given velocity field, and finite-element treatment (in time-dependent form) of the pressure and fields for given stresses. In an example where the contraction ratio is 7:1, results for nominal Deborah number exceeding 100 show no numerical instability. (However, for this problem, the true Weissenberg number, i.e. the ratio of local first-normal-stress difference to shear stress turns out to be generally O(10).) The predictions also correlate very well with experimental birefringence measurements.
    Additional Material: 9 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 303-319 
    ISSN: 0271-2091
    Keywords: Finite Element ; Turbulent Flow ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Although the finite-element (FE) method has been successful in analysing complex laminar flows, a number of difficulties can arise when two-equation turbulence models (e.g. the k-∊ model) are incorporated. This work describes a particular FE discretization of the k-∊ model and reports its performance in recirculating flow. Severe problems encountered in attempts to obtain convergence of the numerical scheme are isolated and analysed, and methods by which the problems can be overcome are suggested.Insight gained in this work has enabled a practical turbulent flow FE code to be constructed which is robust and efficient. This code is the subject of a further paper.
    Additional Material: 8 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 321-336 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Incorporation of the k-∊ turbulence model into Galerkin finite-element fluid-flow codes (which, unlike upwind finite-difference codes, have no artificial damping) can lead to severe iterative convergence difficulties. This paper introduces an alternative turbulence model (the q-f model) and an associated finite-element discretization method which are designed to overcome these problems. The new model forms the basis of a finite-element fluid-flow code which is robust and efficient. Furthermore, it is demonstrated on a practical example that the code can give good agreement with experiment on fairly coarse meshes.
    Additional Material: 5 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 399-419 
    ISSN: 0271-2091
    Keywords: Laminar Boundary Layers ; Finite Element Method ; Finite Difference Method ; Spectral Method Convergence ; Computational Efficiency ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The Dorodnitsyn boundary later formulation is given a finite element interpretation and found to generate very accurate and economical solutions when combined with an implicit, non-iterative marching scheme in the downstream direction. The algorithm is of order (Δ2u, Δx) whether linear or quadratic elements are used across the boundary layer. Solutions are compared with a Dorodnitsyn spectral formulation and a conventional finite difference formulation for three Falkner-Skan pressure gradient cases and the flow over a circular cylinder. With quadratic elements the Dorodnitsyn finite element formulation is approximately five times more efficient than the conventional finite difference formulation.
    Additional Material: 12 Ill.
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  • 11
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 421-439 
    ISSN: 0271-2091
    Keywords: Laminar Flow ; Turbulent Flow ; Compressible Flow ; Separation ; Time-split Method ; Finite Element Method ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The time-split finite element method is extended to compute laminar and turbulent flows with and without separation. The examples considered are the flows past trailing edges of a flat plate and a backward-facing step. Eddy viscosity models are used to represent effects of turbulence. It is found that the time-split method produces results in agreement with previous experimental and computational results. The eddy viscosity models employed are found to give accurate predictions in all regions of flow except downstream of reattachment.
    Additional Material: 15 Ill.
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  • 12
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 441-457 
    ISSN: 0271-2091
    Keywords: Finite Element Method ; Dip Coating ; Newtonian Fluid ; Free Surface ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A finite element simulation of the dip coating process based on a discretization of the continuum with discontinuous pressure elements is presented. The algorithm computes the flow field from natural boundary conditions while an extra condition provided by the existence of free surface is employed to displace the meniscus location towards the actual position. The process is iterative and uses a pseudo-time stepping technique coupled to a cubic spline fitting of the free surface. Numerical predictions exhibit good agreement with experimental data for Newtonian fluids in the case of flat plate dip coating as well as in the case of wire dip coating.
    Additional Material: 14 Ill.
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  • 13
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 459-475 
    ISSN: 0271-2091
    Keywords: Augmented Lagrangian ; Finite Element Method ; Dip Coating ; Non-Newtonian Fluids ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: We apply in this paper the augmented Lagrangian method to the study of various non-Newtonian fluid flow problems, and in particular the dip coating process. We only present in this second part the treatment specific to the non-linearities involved in the constitutive equations, the first part having largely been concerned with the general description of the approximation used.Two rheological models illustrating different rheological behaviours are used to simulate dip coating process: the Carreau-A model for shear-thinning properties of the viscosity and a truncated second-order model for a Newtonian behaviour in viscosity with elastic properties.Numerical predictions show a very good agreement with experimental data for the second-order model. The discrepancy observed in the other case can be explained qualitatively by the elastic properties exhibited by the shear-thinning fluids used: this elasticity is not taken into account in the Carreau-A model.
    Additional Material: 12 Ill.
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  • 14
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 667-683 
    ISSN: 0271-2091
    Keywords: Rotating Flow ; Finite Differences ; Numerical Stability ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A computer program has been developed to predict laminar source-sink flow in a rotating cylindrical cavity. Although the program is based on a standard finite difference technique for recirculating flow, it incorporates two novel features. Step changes in grid size are employed to obtain sufficient resolution in the boundary layers and special treatment is given to the solution of the pressure correction equations, in the ‘SIMPLE’ algorithm, in order to improve the convergence properties of the method. Results are presented both for the flow in an infinite rotating cylindrical annulus and a finite rotating cylindrical cavity, with the inner cylindrical surface acting as a uniform source and the outer cylinder as a sink. These show good agreement with existing analytical solutions and illustrate some of the problems associated with the computation of rapidly rotating flows.
    Additional Material: 8 Ill.
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  • 15
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 685-699 
    ISSN: 0271-2091
    Keywords: Stokes Flows ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A family of simple Stokes flows involving sliding surfaces adjacent to surfaces at rest is considered. Principally, two specific flow configurations are investigated: (i) that arising when parts of the boundary of an infinitely long circular cylinder are rotating about the axis while other parts of the boundary are at rest, and (ii) the flow produced when a cap of a sphere is held at rest while the remainder of the sphere rotates about the symmetry axis. In each case computer plots of streamlines or constant velocity lines are presented to give a general impression of the resulting flow pattern.
    Additional Material: 10 Ill.
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  • 16
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 708-708 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 17
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 709-709 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 18
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 765-780 
    ISSN: 0271-2091
    Keywords: Diffraction ; Hydrodynamics ; Ocean Engineering ; Underwater Structures ; Wave Forces ; Offshore Structures ; Velocity Potential ; Boundary Elements ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The fluid forces resulting from wave interaction with large submerged structures may be calculated using numerical procedures based on the solution of the associated boundary-value problem. In this paper, the analysis of wave interaction with a fixed submerged object of arbitrary cross-section and infinite length using a two-dimensional boundary value formation based on linear diffraction theory is summarized. Subsequently, the application of the boundary element method to obtain a solution is presented. The numerical considerations are emphasized with particular reference to computational efficiency.Numerical results are presented in the form of dimensionless wave force plots for various structural shapes. In the case of a bottom-seated half cylinder, for which there exists a closed-form solution, comparisons are made between results generated using both boundary element and equivalent finite element approaches. In the case of a submerged cylinder, comparisons are made between boundary element derived values and experimental results. The boundary element results compare well with both the closed-form solution and the experimental values.
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  • 19
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984) 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 20
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 931-947 
    ISSN: 0271-2091
    Keywords: Two-layer Flow ; Two-step Scheme ; Selective Lumping Method ; Ishikari Bay ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A finite element method for the analysis of two-layer density flows is presented in this paper. The standard Galerkin method based on linear interpolation functions is used to yield discrete spatial variables. For numerical integration in time, an explicit two-step selective lumping method is used. Here it is applied to a flow analysis of Ishikari Bay, at the mouth of Ishikari River. This case demonstrates a procedure that yields a numerically stable solution.
    Additional Material: 15 Ill.
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  • 21
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 949-969 
    ISSN: 0271-2091
    Keywords: Navier-Stokes ; Discrete Fourier Transform ; Finite Difference ; Short Convolutions ; No-slip Boundary Condition ; Far Field Condition ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A mixed discrete Fourier transform-Finite difference algorithm is developed and used for the calculation of rapidly changing viscous fluid flows past a circular cylinder. The numerical approach has been designed to overcome certain difficulties arising for high Reynolds number simulations. The foremost advantage of the technique lies in its fast calculations of the convolution sums portraying the convective terms of the governing equations. Third-order spatial discretizations and fourth-order time marching are implemented.New schemes are proposed for the boundary conditions at the solid wall and at large distances. The techniques are tested on a case study with other schemes (summarized by Roache1) in order to obtain an optimal choice. Definite indications on the stability and accuracy of boundary condition schemes are achieved. Support for the statement of dominant importance of boundary conditions is also given.A comparison of computational results with experimental data is presented for the case study of the flow past an impulsively started cylinder at Reynolds number 20.The time development of the symmetrical zone of recirculation, which is formed at an early stage of the flow, has been studied for 300 ≤ Re ≤ 9500 by means of the proposed algorithm. Computational results, comparisons with experimental data2 and discussion of upper limits of validity of the procedure will be presented in a companion paper.
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  • 22
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 997-998 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 23
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 999-999 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 24
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    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 989-996 
    ISSN: 0271-2091
    Keywords: Galerkin ; Spline ; Stability ; Disk ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The perturbation equations which characterize the stability of flow over a rotating infinite disk are derived via strict order of magnitude analysis. These equations contain viscous terms not considered by Stuart,1 curvature and Coriolis terms not considered by Brown,2 and axial velocity terms not considered by Kobayashi et al.3 The strategy for reducing the problem to an algebraic system is Galerkin's method with B-spline discretization. In comparison with the Poiseuille flow solutions of Orszag,4 the method is shown to perform well without placing undue demands on computing capability. Critical values of Reynolds number, wave length, vortex orientation and number of spiral vortices calculated by the present method compare favourably with experimental data of Kobayashi et al.
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  • 25
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    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 1001-1012 
    ISSN: 0271-2091
    Keywords: Compressible Fluid Flow ; Numerical Analysis ; Pressure Method ; von Kármán Vortex Street ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this paper the pressure method for incompressible fluid flow simulation is extended and applied to the numerical simulation of compressible fluid flow. The governing equations, obtained from the physical principles of conservation of momentum, mass and energy, are first studied from a characteristic point of view. Then they are discretized with a semi-implicit finite difference technique in such a fashion that stability is achieved independently of the speed of sound. The resulting algorithm is fast, accurate and particularly efficient in subsonic flow calculations. As an example, the computer simulation of the von Kármán vortex street is described and discussed.
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  • 26
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    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984), S. 13-24 
    ISSN: 0271-2091
    Keywords: Gas Networks ; Computational Methods ; Simulation Optimization ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A technique is presented for calculating the transient flow in high pressure transportation systems where both simple systems (without compressors) and systems with compressors have been taken into consideration. A partial differential equation characterizing the dynamic gas flow through a pipeline and a numerical scheme for its solution are considered. A method of computing node pressures is also characterized.
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  • 27
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 106-108 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 28
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    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984) 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 29
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 127-145 
    ISSN: 0271-2091
    Keywords: Finite Element ; Bénard Connection ; Bifurcation ; Continuation ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The problem of fluid motion in a cavity with rigid sidewalls that is heated uniformly from below is studied by the finite-element method. The techniques of parameter-stepping and monitoring the determinant of the Jacobian matrix to find bifurcations are used. Results are presented for width-to-height ratios in the range 1 to 4, and for three different boundary conditions on the horizontal surfaces, namely both rigid, both free, and rigid bottom with free top. The non-linear branches above the critical Rayleigh number are examined. Extensions to non-Boussinesq flow are trivial.
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  • 30
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 203-205 
    ISSN: 0271-2091
    Keywords: Incompressible Fluid Flows ; Cavity ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 31
    ISSN: 0271-2091
    Keywords: Potential Flows ; Navier-Stokes Problems ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: An approach for the numerical solution of flow problems based on the concept of fundamental solutions of differential equations is described. This approach uses the finite element methodology but does not rely on the concept of variational principle or that of residuals. The approach is shown to be well-suited for many types of flow problems. Various applications of this approach are discussed in this paper, with particular emphasis placed on the solution of potential flows and viscous flows containing appreciable regions of separation.
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  • 32
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 247-269 
    ISSN: 0271-2091
    Keywords: Finite Elements ; Navier-Stokes ; Driven Cavity ; Flow Past a Cylinder ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: We present a simple and efficient finite element method to solve the Navier-Stokes equations in primitive variables V, p. It uses (a) an explicit advection step, by upwind differencing. Improvement with regard to the classical upwind differencing scheme of the first order is realized by accurate calculation of the characteristic curve across several elements, and higher order interpolation; (b) an implicit diffusion step, avoiding any theoretical limitation on the time increment, and (c) determination of the pressure field by solving the Poisson equation. Two laminar flow calculations are presented and compared to available numerical and experimental results.
    Additional Material: 21 Ill.
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  • 33
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 271-281 
    ISSN: 0271-2091
    Keywords: Collocation ; Moving Mesh ; Advection-Diffusion ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A collocation method based on multiple regions with moving boundaries placed in a flow field in which convection effects dominate, is proposed. By making the moving boundaries of the regions coincide with moving sharp fronts present in the solution of convection dominated problems, and thereby allowing higher concentration of meshes to be placed about the fronts, the proposed method is able to achieve very high accuracy. By having a moving mesh, the Peclet number characterizing the flow field depends upon velocity relative to a moving mesh in a region. Consequently by choosing proper velocities of the moving boundaries, the value of this Peclet number can be made as small as desired. The traditional collocation method based on centred discretization, when applied to each region in the field, produces oscillation free solutions even when the values of Peclet number based on absolute velocity are extremely large. In view of these characteristics the method appears to be an excellent candidate for the solution of any two-phase flow problem containing sharp fronts.
    Additional Material: 5 Ill.
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  • 34
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    International Journal for Numerical Methods in Fluids 4 (1984) 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 35
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 283-290 
    ISSN: 0271-2091
    Keywords: Prandtl's Equation ; Singular Integrodifferential Equations ; Quadrature Method ; Natural Interpolation Formula ; Principal Value Integrals ; Gauss- and Lobatto-Chebyshev Quadrature Rules ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Prandtl's singular integrodifferential equation and related equations appear in problems of aerofoil and propeller theory in fluid mechanics. Here a natural interpolation formula for the approximation to the unknwon function of Prandtl's equation when this is solved numerically by the direct quadrature method, based on the Gauss- and Lobatto-Chebyshev quadrature rules, is proposed. This interpolation formula is analogous to Nyström's natural interpolation formula for Fredholm integral equations of the second kind and the corresponding formula for singular integral equations. Numerical applications of the same formula are also made.
    Additional Material: 2 Tab.
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  • 36
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 291-302 
    ISSN: 0271-2091
    Keywords: Finite Elements ; MHD Flows ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A finite element method is given to obtain the numerical solution of the coupled equations in velocity and magnetic field for unsteady MHD flow through a pipe having arbitrarily conducting walls. Pipes of rectangular, circular and triangular sections have been taken for illustration. Computations have been carried out for different Hartmann numbers and wall conductivity at various time levels. It is found that if the wall conductivity increases, the flux through a section decreases. The same is the effect of increasing the Hartmann number. It is also observed that the steady state is approached at a faster rate for larger Hartmann numbers or larger wall conductivity. Selected graphs are given showing the behaviour of velocity, induced magnetic field and flux across a section.
    Additional Material: 11 Ill.
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  • 37
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 497-497 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 38
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    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 4 (1984) 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 39
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 477-496 
    ISSN: 0271-2091
    Keywords: Gas Dynamics ; Finite Difference Schemes ; Shock Localization ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: We consider a problem on shock wave localization in the numerical solution of one-dimensional unsteady problems of gas dynamics in Eulerian variables obtained on the basis of finite difference shock-capturing schemes. An optimization method for strong discontinuity localization proposed previously by Miranker and Pironneau is investigated by means of methods of classical variational calculus. This method may be difficult to implement when the entropy condition is included in the formulation of Miranker and Pironneau's optimization problem as an active constraint. In this connection we suggest an alternative optimization problem using artificial viscosity in the variational principle. It is shown theoretically that the application of such a variational principle yields a trajectory which coincides with the true discontinuity trajectory in the case of a shock wave moving at a constant speed. On the basis of this modification one more algorithm is proposed which reduces the shock localization problem to a problem of minimization of a univariate function. Numerical tests corroborate completely the theoretical conclusions. In particular, a higher shock localization accuracy is obtained on the basis of the proposed algorithms as compared to the original Miranker-Pironneau method.
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  • 40
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    International Journal for Numerical Methods in Fluids 4 (1984), S. i 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 41
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    International Journal for Numerical Methods in Fluids 4 (1984), S. i 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 42
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 499-509 
    ISSN: 0271-2091
    Keywords: Critical Flow Rate ; Finite Elements ; Free Surface ; Weir ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Computing critical flows in hydraulics involves three problems in one: the internal flow problem, the location of the free surface and the determination of the critical flow rate. The subject can involve such difficulties as non-uniqueness, non-existence, ill-conditioning and catastrophes.This paper discusses the difficulties relating to computing critical flows over weirs. A new rapidly convergent method of determining the critical flow rate is presented and various results are shown using it with finite element discretization and with a new streamline shifting method. Numerical results are in good agreement with published data, both numerical and experimental.
    Additional Material: 6 Ill.
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  • 43
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 511-517 
    ISSN: 0271-2091
    Keywords: Approximation ; Cubic Splines ; Orthogonal Collocation ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A well-known Stokes problem is discussed by a cubic spline collocation method. Two consecutive cubic splines are obtained for the problem. The results by this method are compared with those of an orthogonal collocation method. The selection of the length of the subintervals of the range of the boundary value problem is also justified. The results obtained by these two methods are compared with the analytic solution. The methods involve simple algebra, and hence the calculations do not require the help of a computer. Necessary error analysis has been carried out.
    Additional Material: 2 Ill.
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  • 44
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 519-537 
    ISSN: 0271-2091
    Keywords: Boundary-Fitted Co-ordinates ; Incompressible Flow ; 2D and 3D ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: For three-dimensional fluid flows in complex geometries, it is convenient to make predictions using a non-orthogonal boundary-fitted mesh. The present paper describes an economical method of solving the equations of motion for two and three dimensional problems using such meshes. The locations on the mesh at which the depenent variables are calculated, and the methods used to solve the equations, are key issues in the development of a successful algorithm; these are discussed in the present paper. Results obtained when the proposed method is applied to several problems are also described. The method is intended for flows in which compressibility effects do not dominate.
    Additional Material: 11 Ill.
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  • 45
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    International Journal for Numerical Methods in Fluids 4 (1984) 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 46
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 710-710 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 47
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 711-724 
    ISSN: 0271-2091
    Keywords: Finite-Volume Method ; Numerical Diffusion ; Upstream Weighted Differencing ; Skew Upstream Differencing ; Turbulent Recirculating Flow ; Turbulence Model ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Predictions are reported for two-dimensional, steady, incompressible flows over rearward-facing steps for both laminar and turbulent conditions. The standard k-∊ turbulence model was used for the turbulent flow. Attention was focused on obtaining accurate solutions to the differential equations. It is concluded that some of the serious discrepancies that have occurred between prediction and observation, and attributed in earlier studies to the inadequacy of the turbulence model, may have been due to the inaccuracy of the solution.
    Additional Material: 11 Ill.
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  • 48
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 749-764 
    ISSN: 0271-2091
    Keywords: Hyperbolic Conservation Equation ; Finite Elements ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Several explicit schemes are presented for triangular P0 and P1 finite elements. A first-order accurate upwind P0 scheme is compared to a FLIC type method. A second-order accurate Richtmyer scheme is constructed. Applications are given for the Euler system of conservation laws in the 2-dimensional case.
    Additional Material: 14 Ill.
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  • 49
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 725-747 
    ISSN: 0271-2091
    Keywords: Ray Methods ; Water Waves ; Refraction ; Diffraction ; Coasts ; Harbours ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Ray methods are used in coastal and harbour wave disturbance investigations where the area to be modelled is large compared to the wavelength. The interpretation of forward-plotted ray diagrams, once obtained, has always been a difficult problem. The technique described in this paper calculates wave amplitudes during the ray plotting process and requires only minor modifications to existing ray plotting programs. The idea is to superimpose a grid of square elements over the entire sea area under study, and to perform a spatial averaging of the rays crossing each square element. This ‘square-averaging’ technique has a number of advantages. It smooths the rapid amplitude variations near caustics, calculates the interference of several wave trains, and generates amplitudes automatically in a square array covering the whole studied sea area. Two types of sensitivity tests are carried out. These tests are designed to determine the accuracy of the predicted wave amplitudes with respect to: (1) the square size per wavelength, and (2) the ray density. These two factors largely determine the computing storage, time and cost of a ray model. An upper limit on the square size per wavelength and a lower limit on the ray density are obtained.
    Additional Material: 12 Ill.
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  • 50
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 801-801 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 51
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 802-802 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 52
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 1013-1025 
    ISSN: 0271-2091
    Keywords: Stream Function ; Viscous Flow ; Non-conforming Elements ; Interface Penalties ; Reduced Integration ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A finite element method for solution of the stream function formulation of Stokes flow is developed. The method involves complete cubic non-conforming (C0) triangular Hermite elements. This element fails the patch test. To correct the element and produce a convergent method we employ a penalty method to weakly enforce the desired continuity constraint on the normal derivative across the inter-element boundaries. Successful use of the method is demonstrated to require reduced integration of the inter-element penalty with a 1-point Gauss rule. Error estimates relate the optimal choice of penalty parameter to mesh size and are corroborated by numerical convergence studies. The need for reduced integration is interpreted using rank relations for an associated hybrid method.
    Additional Material: 8 Ill.
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  • 53
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 1097-1098 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 54
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 1083-1095 
    ISSN: 0271-2091
    Keywords: Turbomachines ; Finite Volume ; Consistency ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The aim of this contribution is to investigate the consistency and order of accuracy of different control surfaces used for finite area blade-to-blade flow calculations. The following cases will be treated: a hexagonal element, a trapezoidal element, a bitrapezoidal element and a quadrilateral element. Finally, the consistency conditions will be discussed and compared with respect to a cascade flow application.
    Additional Material: 6 Ill.
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  • 55
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 1099-1099 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 56
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    International Journal for Numerical Methods in Fluids 4 (1984) 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 57
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 1117-1136 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: We describe in this paper some new methods for solving the shallow water flow problem; this problem is composed of two coupled non-linear equations. First a fractional step method is used to decouple the difficulties due to the convection and the propagation. The diffusion propagation step amounts to solving two coupled linear equations on the water depth and the fluxes. We used then some quasi-direct decomposition techniques to decouple the unknowns, leading to symmetric systems only. In addition some non-trivial boundary conditions on the flux are examined. Particularly we are interested to get decoupled systems on the two components of the flux. Numerical tests are presented to enlighten the behaviour and the capabilities of the method. Finally an industrial example is treated on the Dunkirk harbour.
    Additional Material: 14 Ill.
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  • 58
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 1101-1115 
    ISSN: 0271-2091
    Keywords: Numerical Solution ; Navier-Stokes Equations ; 2-D Steady, Laminar Flows ; ADI Method ; Spline Interpolating Polynomials ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The present paper provides an improved alternating direction implicit (ADI) technique as well as high-order-accurate spline ADI method for the numerical solution of steady two-dimensional incompressible viscous flow problems. The vorticity-stream function Navier-Stokes equations are considered in a general curvilinear coordinate system, which maps an arbitrary two-dimensional flow domain in the physical plane into a rectangle in the computational plane. The stream function equation is parabolized in time by means of a relaxation-like time derivative and the steady state solution is obtained by a time-marching ADI method requiring to solve only 2 × 2 block-tridiagonal linear systems. The difference equations are written in incremental form; upwind differences are used for the incremental variables, for stability, whereas central differences approximate the non-incremental terms, for accuracy, so that, at convergence, the solution is free of numerical viscosity and second-order accurate. The high-order-accurate spline ADI technique proceeds in the same manner; in addition, at the end of each two-sweep ADI cycle, the solution is corrected by means of a fifth-order spline interpolating polynomial along each row and column of the computational grid, explicitly. The validity and the efficiency of the present methods are demonstrated by means of three test problems.
    Additional Material: 7 Ill.
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  • 59
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 1137-1148 
    ISSN: 0271-2091
    Keywords: Free Surface Flows ; Computation ; Kantorovich Method ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Computing free surface gravity flows involves basically two coupled problems, namely, the location of the free surface position and the determination of the internal flow field (for assumed values H0 and Q of the total head and discharge, respectively).Solution techniques are invariably based on iterative procedures, but those that iterate between the two coupled problems may become unstable.In this paper we present a computational method in which the coupling is kept throughout the process of iteration. This is achieved by converting the coupled problems (by means of the Kantorovich method) into the single problem of finding a set of streamlines, including that of the free surface. These streamlines are moved (iteratively) to satisfy the stationary conditions of the governing variational principle.The algorithm is very stable and converges rapidly. It is also easy to implement to solve various types of steady flows with a free surface under gravity.
    Additional Material: 5 Ill.
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  • 60
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 1149-1163 
    ISSN: 0271-2091
    Keywords: Stokes Problem ; Chebyshev Approximation ; Spectral Method ; Penalty Formulation ; Splitting Scheme ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: To investigate the influences of time scheme, pressure treatment and initial conditions in incompressible fluid dynamics, a Stokes problem is solved numerically on a slab geometry within the framework of spectral approximation in space. Four algorithms are examined: splitting schemes, influence matrix method, penalty formulation and pseudo-spectral space-time technique. It is shown that splitting schemes are less accurate than the other processes. Furthermore, the initial field should respect a compatibility condition to avoid singularities at the initial time. If it is not possible to build such a compatible field, the numerical procedure has to present good damping properties at the first steps of the time integration.
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  • 61
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 1186-1187 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 62
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 1185-1185 
    ISSN: 0271-2091
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 63
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    International Journal for Numerical Methods in Fluids 4 (1984), S. 1165-1184 
    ISSN: 0271-2091
    Keywords: Turbulence ; Buoyancy ; Swirl ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A three-parameter model of turbulence applicable to free boundary layers has been developed and applied for the prediction of axisymmetric turbulent swirling flows in uniform and stagnant surroundings under the action of buoyancy forces. The turbulent momentum and heat fluxes appearing in the time-averaged equations for the mean motion have been determined from algebraic expressions, derived by neglecting the convection and diffusion terms in the differential transport equations for these quantities, which relate the turbulent fluxes to the kinetic energy of turbulence, k, the dissipation length scale of turbulence, L, and the temperature covariance, T′2. Differential transport equations have been used to determine these latter quantities. The governing equations have been solved using fully implicit finite difference schemes. The turbulence model is capable of reproducing the gross features of pure jet flows, buoyant flows and swirling flows for weak and moderate swirl.The behaviour of a turbulent buoyant swirling jet has been found to depend solely on exit swirl and Froude numbers. The predicted results indicate that the incorporation of buoyancy can cause significant changes in the behaviour of a swirling jet, particularly when the buoyancy strength is high. The jet exhibits similarity behaviour in the initial region for weak swirl and weak buoyancy strengths only, and the asymptotic case of a swirling jet under the action of buoyancy forces is a pure plume in the far field. The predicted results have been found to be in satisfactory agreement with the available experimental data and in good qualitative agreement with other predicted results.
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  • 64
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 2287-2291 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Tab.
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  • 65
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By interfacial polycondensation of 4,4′-dimercaptobenzophenone with oxalyl, succinyl, adipolyl, suberoyl, and sebacoyl chlorides new polythioesters were obtained. To determine the optimal conditions of interfacial polycondensation the influence of the following factors on yield and value of reduced viscosity was studied: type of organic phase, the quantitative ratio of aqueous to organic phase, concentration of hydrogen chloride acceptor, molar ratio of reagents, temperature of reaction, rate of acid chloride addition, and contribution of catalyst. A thorough examination of the polycondensation of dithiol with adipolyl and sebacoyl chlorides was carried out. The structure of all polythioesters obtained under model conditions was determined by elemental analysis and infrared spectra. Initial decomposition and intensive decomposition temperature were defined by the curves of thermogravimetric analysis. Mechanical and electrical properties of the polythioesters obtained from 4,4′-dimercaptobenzophenone and adipoyl and sebacoyl chlorides were determined. The molecular weight was not measured because of the low solubility of the polythioesters.
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  • 66
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 3407-3415 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The small-angle X-ray scattering method was applied to evaluate macromolecular parameters of Agave fibers (Agave sisalana, A. cantala, A. hybrid, A. elongata, and A. ameniensis). The macromolecular parameters such as specific inner surface, percentage of void, length of coherence, range of inhomogeneity, and transversal lengths were evaluated. The correlation of macromolecular parameters with the average breaking strength of Agave fibers did not lead to a linear relation, however, the specific macromolecular organization in A. sisalana manifested higher breaking strength.
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  • 67
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 3439-3446 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three new thermally stable polypyromellitimide films were made by the thermal cyclodehydration of the corresponding polyamic acids obtained by the polymerization of pyromellitic dianhydride with 4,4′-bis{N2-[4-(4-aminobenzyl)phenyl]aspartimido} diphenylmethane, 4,4′-bis{N2-[4-(4-aminophenoxy)phenyl]aspartimido} diphenylether, and bis(4-aminophenoxy)tetrakis (4-phthalamic acid phenoxy)cyclotriphosphazene. The bis(4-aminophenoxy)tetrakis (4-phthalamic acid phenoxy)cyclotriphosphazene was obtained from hexakis(4-aminophenoxy)cyclotriphosphazene involving its reaction with phthalic anhydride. The structure of these materials and precursors were characterized by using Fourier-transform-infrared (FT-IR) and proton nuclear magnetic resonance spectroscopy. The thermal stabilities of the films were evaluated by the thermogravimetric analysis, showing char yields at 800°C ranging from 68% to 58% in a nitrogen atmosphere and 24% in air atmosphere.
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  • 68
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 3499-3519 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A kinetic model has been developed and successfully applied to describe the reaction profiles of the seeded emulsion polymerization of styrene. The model incorporated a mechanism for the capture of aqueous-phase oligomeric free radicals by latex particles. Both the collision and diffusion mechanism were considered. The experimental data agreed well with the collision mechanism. The rate of the free radical capture by latex particles is proportional to latex particle surface area (D2p), and also is a strong function of the rate of free radical generation per latex particle. The model predicts that the rate of polymerization is dependent on the latex particle diameter to the 2.5 power in the gel region. This was demonstrated experimentally by J. W. Vanderhoff et al. (J. Polym. Sci., 20, 225 (1956)). Propagation and termination rate constants for styrene in the 70-90°C temperature range were also determined.
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  • 69
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 2523-2531 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polyelectrolyte submicron microcapsules were prepared by interfacial crosslinking of an aqueous salt solution of poly(ethyleneimine) and a toluene solution of brominated poly-(2,6-dimethylphenylene oxide). The two solutions were brought together and mixed by sonication. As a result, a stable emulsion was obtained, which was subsequently cast into a membrane in which the microcapsules were embedded. The salt solution contained in the microcapsules could be released under controlled conditions. The rates of release were measured. They could be controlled by applying osmotic pressures, by additional quaternization of the membrane, or by modification of the structure of the capsule wall by introduction of a surfactant.
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  • 70
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 2501-2521 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ω-Alkenoic acids, either commercially available or synthesized, were esterified to their corresponding methyl esters. They were characterized by their infrared, 1H-, and 13C-NMR spectra. The ω-alkenoates prepared were: propenoate (acrylic acid), butenoate, pentenoate, hexenoate, heptenoate, octenoate, nonenoate, and decenoate. These compounds were epoxidized with m-chloroperoxybenzoic acid to the corresponding methyl ω-epoxyalkanoates. The rate of epoxidation of the double bond is found to increase as the double bond is separated from the carbomethoxy group by increasing numbers of methylene groups. When at least three methylene groups are inserted, the rate of epoxidation becomes constant and is similar to the epoxidation of ω-olefins. The methyl ω-epoxyalkanoates were characterized by their infrared, 1H-, and 13C-NMR spectra. Methyl ω-alkenoates and methyl ω-epoxyalkanoates were prepared and characterized, and their purification was studied in preparation for their investigation as monomers for olefin or epoxide polymerization using corrdination initiators.
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  • 71
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 2601-2609 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Data on the ablative photodecomposition of three condensation polymers [polyimide, poly(ethylene terephthalate), and polycarbonate] and one addition polymer (polymethyl methacrylate) by laser pulses at 193 nm are presented. The etch depth/pulse is a linear function of the number of pulses at constant laser fluence. It varies with the logarithm of the fluence in a linear manner at different fluences. The etch depth is independent of the atmosphere above the film, whether it is air at 1 atm, or a vacuum. The etching of PMMA at fluences 〉 100 mJ/cm2 is believed to follow a mechanism different from the process at lower fluences. Etching of polyimide and polyethylene terephthalate at 248 and 308 nm is also reported. The mechanism of etching by laser radiation may receive greater contribution from a thermal process with increasing wavelength. This is manifested in the etch depth versus log fluence plot by sharp changes in slope.
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  • 72
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 2611-2624 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this article we describe a study of the reaction between triethylaluminium (TEA) and ethylbenzoate (BE) in a heptane solution by Fourier transform, infrared (IR), and ultraviolet (UV) spectroscopy. These compounds were chosen as a model of the cocatalytic solution used with a Ziegler-Natta catalyst supported on MgCl2 for the stereospecific polymerization of propene. In the polymerization concentration range a 2 TEA:1 BE yellow complex was added to the solution and no free BE could be detected at a AI/BE molar ratio above 2: the solution contained only free and complexed TEA. The complex decomposed spontaneously to a colorless aluminium alcoholate. The rate of decomposition remained slow at room temperature and the reaction was enhanced by heating or by a high AI/BE ratio or high AI concentration. The decomposition was inhibited in the presence of an olefin.
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  • 73
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 2945-2952 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Influences of microenvironment of various polyelectrolytes, i.e., ionene polymers and polyamine sulfones, on the photo- and/or thermal isomerization between the trans and cis forms of sodium m-(4-ethoxyphenylazo)benzene sulfonate (SEPS) were studied. 6,6-Ionene demonstrated larger enhancing effect on the cis-trans thermal isomerization than 3,3-ionene, which indicated that the micropolarity or the pH around the polymer is important. In the Arrhenius plots for both photo- and thermal isomerizations, deviations from the linearity were observed. In the former case, a sharp bend and the negative apparent activation energy were obtained at the high temperature. Furthermore, they were sensitively affected by the polyelectrolytes.
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  • 74
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 2973-2981 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photocrosslinking of poly(methyl methacrylate) (PMMA) was studied in the solid state in the presence of various quinones. For the study of photocrosslinking mechanism, a PMMA film containing p-benzoquinone (Q) was irradiated with UV light (λ 〉 370nm) and then purified by reprecipitation. It was found that the reprecipitated polymer has quinone-type moieties, besides the hydroquinone-type moieties, chemically bound to the polymer chain. The reprecipitated polymer film also crosslinking efficiency was higher than that of PMMA film containing Q. It was concluded that the formation of quinone-type structure during irradiation played an important role in the photocrossing of PMMA containing Q.
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  • 75
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 2993-3000 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oxidation of poly(styryl)lithium with molecular oxygen was investigated in the solid state (with and without N,N,N′, N′-tetramethylethylenediamine) in benzene (with and without N,N,N′, N′-tetramethylethylenediamine) and in benzene/tetrahydrofuran (THF) solutions. The oxidation products included the corresponding polystyrene dimer [(PS)2], the dimeric poly(styrene) peroxide (PSO2PS), poly(styrene) hydroperoxide (PSO2H), and the hydroxyl-terminated polymer (PSOH). The hithertofore unreported macroperoxide (PSO2PS) accounts for approximately 50% of the dimeric product obtained from poly(styryl)lithium oxidations in the presence of Lewis bases. The total amount of peroxide products was determined by iodometric titration in the presence of a phase-transfer catalyst, dicyclohexyl-18-crown-6. On the basis of the effect of polar additives on the amount of dimeric products, it is concluded that dimer formation in the air termination of polymeric organolithium compounds results from oxidation and not carbonation reactions.
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  • 76
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 3001-3010 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The binding of 41-(1-pyrenyl)butyltrimethylammonium bromide (PN+) to the neutral poly-soap-type polymers poly(vinylbenzo-18-crown-6) (P18C6) and poly(vinylbenzoglyme) (PVBG) was studied by optical spectroscopy and fluorescence in the presence and absence of salts. Measurements of the respective binding constants were based on distinct differences in the optical absorption spectra of free and polymer-bound PN+. When crown ether-compelxable cations (e.g., K+) were added the adsorption of PN+ to P18C6 decreased as the neutral polymer was converted to a polycation. No decrease was found with PVBG because alkali ions do not complex significantly to this polymer in water. PN+ adsorption to both polymers rose rapidly, however, as the salt concentration increased. This effect was strongly anion-dependent and increased in the order of Cl- 〈 Br- 〈 I- 〈 CNS- 〈 BPh4-. The increased binding was reflected in a higher binding constant and also in a larger number of bound PN+ molecules per polymer chain under saturation conditions. It is argued that the formation of ion pairs or larger ion clusters in the aqueous phase when anions are added forces more PN+ molecules to adsorb on the surface of the polymer coil to which they are bound as ion pairs or higher aggregates. Under saturation conditions enough PN+ molecules are bound to convert the pyrene monomer fluorescence spectrum into that of the excimer. These results are compared with data obtained for the anionic solute 4-(1-pyrenyl)butanoate in the presence of salts.
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  • 77
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 3877-3884 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polymerization of ethylene was initiated with soluble polystyrene100-butadiene3-Li/TiCI4 complexes in toluene leading to block copolymers. The activity of the system was measured at a constant ratio r = [Li]/[Ti] and for different concentrations in active centers and in monomer. Measurement of the amount of the block copolymers formed led to the direct determination of the efficiency of the catalytic system. This efficiency is defined with respect to the number of potentially active centers and is close to 90%. From both measured values of activity of the catalytic system and of its efficiency, the rate constants of propagation were deduced. The kinetic behavior of the system is fully consistent with that of a living system. The rate is first order towards both ethylene and active centers concentrations. So, the rate constant of propagation is an absolute rate constant, measuring the intrinsic reactivity of active sites. Determination of the absolute rate constant at different temperatures, led to thermodynamic parameters of the propagation reaction. The chemical composition of the complex and the absence of polymeric aggregation, leads to propose a structure of the active species: a bioctahedral binuclear structure is consistent with kinetic, thermodynamic results, and structural determinations.
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  • 78
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 121-128 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: To control the swelling of polymer membrane by photoirradiation amphiphilic azoaromatic polymer membranes were prepared and a photoinduced change in the swelling degree of water was investigated. The azobenzene moiety in the side chain of the polymer was isomerized from trans form to cis form by ultraviolet (UV) irradiation and reverse isomerization was found by visible light irradiation. The swelling degree of the polymer membrane for water in the dark was decreased by UV radiation, and when visible light irradiation was carried out in the polymer membrane the degree of swelling recovered to the original level. The swelling degree decreased with an increase in the mole fraction of the azobenzene moiety in the dark and under UV irradiation. The deswelling degree of the polymer membrane by UV irradiation also decreased with an increase in the mole fraction of the azobenzene moiety. This reversible change in the swelling degree was considered to be caused by the photoisomerization of the azobenzene moiety in the polymer membrane.
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  • 79
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    Topics: Chemistry and Pharmacology
    Notes: Several N-substituted chloromaleimides were prepared by dehydrating the corresponding chloromaleamic acids. Treatment of chloromaleimides with allylamine or cyclopropylamine produced N-aryl-2-(allylamino)maleimides and N-aryl-2-(cyclopropylamino)maleimides, respectively. Neither the N-substituted chloromaleimides nor the N-aryl-2-(allylamino) or N-aryl-2-(cyclopropylamino)maleimides polymerized free radically or anionically. The difficulty of achieving good pi-pi overlap and stiric effects at the propagation step prevented the cyclopolymerization of the prepared 1,5-dienes.
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  • 80
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 287-293 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: To devise an improved gel permeation chromatography system for the analysis of macromolecules, with a strongly alkaline solution as eluent, three Fractogel TSK gels were investigated. Because primary standards are usually unavailable, calibration was achieved by using Benoit's universal procedure and polystyrene sulfonates, polyethylene glycols, and dextrans as secondary calibrants. Continuous monitoring of intrinsic viscosity resulted from coupling a viscodetector with a classical differential refractometer. It was found that column efficiency and fractionation range could be extended well beyond those of previously studied systems on a reasonably short period of analysis.
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  • 81
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 597-604 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A kinetic study has been made on the preirradiation grafting of acrylic acid (AAc) onto poly(tetrafluoroethylene-perfluorovinyl ether) (PFA) film. The effect of grafting conditions was investigated. The dependences of the grafting rate on preirradiation dose and monomer concentration was found to be of the order of 0.5 and 1.3, respectively. The final degree of grafting was found to increase with dose and monomer concentration. However, it decreases as the grafting temperature increase. The overall activation energy for the graft polymerization was calculated from Arrhenius plots to be 5.6 kcal/mol. The activation energy for this grafting system was found to be independent of preirradiation dose used in the range from 10 to 100 kGy. The relationship between the grafting rate and film thickness gave a negative first-order dependence. The results suggest that the grafting proceeds by radical mechanism with bimolecular termination of growing chain radicals. It was reasonable concluded that this grafting proceeds from the surface to the center of film with progressive monomer diffusion through the grafted layer which swells in the monomer solution.
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  • 82
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 609-621 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the formation of polyacrolein microspheres by ionizing radiation (polymer I) were investigated. Their structure and reactivity were compared with polyacrolein microspheres prepared by base catalysis (polymer II). The study of Fourier infrared (IR) spectra of polymers I and II showed structural differences. The reaction of polyacrolein spheres with m-aminophenol indicated the presence of conjugated groups. The reaction of antibodies with polyacrolein spheres was investigated as a function of pH and the number of reactive aldehyde groups was determined by nitrogen analysis of polyacrolein-hydroxylamine adducts. Intensely fluorescent polyacrolein microspheres obtained by Co-γ-irradiation in sizes of 100 Å-4 μm have already found applications as immunoreagents for cell labeling and separation.
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  • 83
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 673-677 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: β-Pinene was polymerized with cationic initiators in reactions that were carried out to study the solvent, temperature, initiator, and monomer-to-solvent ratio. Polymers obtained under different conditions were characterized by intrinsic viscosity, softening point, and gel permeation chromatography.
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  • 84
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 669-672 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The microstructure of polybutadiene produced by anionic initiation in diethyl ether and tetrahydrofuran with counterions Li+, Na+ and K+ was determined by 1H- and 13C-NMR. Ionization suppressing salts were added in tetrahydrofuran to ensure that only the ion-pair reaction was studied. Results are compared with older published data. In general, the 1,4 content of the polymer increases with increasing counterion size but varies somewhat with solvent with a given counterion. The cis component of the 1,4 structures changes with temperature and counterion. It is suggested that this change reflects the proportion of cis and trans centers that carry the reaction.
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  • 85
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 657-667 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis-(2,4-dinitrophenyl)glycols are stable in the presence of triethylamine but undergo ethanolysis in the presence of hydroxide ions. The quantitative removal of the DNP blocking group allows an integrated scheme to pure glycols from commercially available polyethylene glycol mixturesMixtures of ethylene glycol oligomers are obtained by anionic polymerization of ethylene oxide. See, for example, G. O. Curme and F. Johnston, Glycols, Reinhold, New York, 1953. They are commercially available (as PEG-200, PEG-400, etc., to indicate the average molecular weight of the major components). by bis-dinitrophenylation, chromatographic separation, and end-group removal, using high performance liquid chromatography (HPLC) of the bis-(2,4-dinitrophenyl)glycols for purity monitoring. A facile synthetic method for the production of penta-to dodecaglycols in a mixed, aqueous, dioxane solvent system, with fair yields, is also described. The bis-(2,4-dintrophenyl) protection of glycols is a reversible reaction that can be used as (1) a preparative method for pure glycols from readily available commercial polyethylene glycol mixtures; (2) a highly sensitive and accurate analytical methodA. Warshawsky, A. Tishbee, and N. Shoef, J. Liq. Chromatogr., submitted for publication. coupled with HPLC.
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  • 86
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ionic groups incorporated into a polymer have a decided effect on its physical properties. A number of ionomers and polyelectrolytes have been widely applied. In particular, sulfonated bisphenol-A polysulfone (SPSF) has been used as a composite or single-component membrane for the desalination of water. In this article, the synthesis and physical characteristics of sulfonated polysulfone are addressed. A detailed synthesis route is provided and methods that yield determinable levels of sulfonation are described. These ion-containing polymers retain an excessive amount of residual salts, which, of course, are impurities to the system. Therefore, before any analyses were made the polymers were subjected to a thorough soxhlet extraction process with boiling water, which appeared to be quite effective. The degree of sulfonation was assessed by several methods such as 1H NMR and FT-IR. A new 1H NMR method was derived because the method cited in the literature proved to be too inconsistent for our work. The new 1H NMR method used a quaternary ammonium counterion [N(CH3)4]. These methyl protons are easily measured and may be ratioed against the isopropylidene protons in the polymer backbone that act as an internal standard. Characterization of the physical properties of SPSF consisted of water uptake, differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and solubility studies. Its physical appearance and mechanical behavior were improved by the solution procedure. Also addressed were the effects of different counterions (Na+ & Mg++) with SPSFs of low levels of sulfonation. The variation in physical properties between the divalent and monovalent counterions is dramatic, especially when observed by TMA in the rubber plateau above the apparent glass temperature.
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  • 87
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 769-779 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radiation graft polymerization of styrene to polyethylene was studied under diffusion-controlled conditions of radiation intensity I, monomer concentration M1, and polymer sample thickness L. The results of the present study together with previous work under diffusion-free conditions verify our theoretical model for the diffusion-controlled reaction. The grafting rate is inverse first order in L for diffusion-controlled reaction and independent of L for diffusion-free reaction. The order of dependence of grafting rate on radiation intensity for diffusion-controlled reaction is one-half that for diffusion-free reaction. Diffusion control leads to a decrease in the order of dependence of grafting rate on monomer concentration. The decrease is greater than theoretically predicted; possible reasons for this effect are described.
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  • 88
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 863-864 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 985-994 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 1035-1042 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Interpenetrating polymer networks (IPNs) with opposite charge groups (tertiary amine and carboxyl groups) made from polyurethanes and methacrylate polymers have been synthesized and their properties and morphology, studied. With increasing carboxyl group concentration the mechanical properties and compatibility between the component networks were significantly improved, possibly because of the negative (or zero) free energy produced by the interaction contribution between the tertiary amine groups in the polyurethanes and the carboxyl groups in the methacrylate polymers determined by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The improved molecular mixing in these IPNs was thought to be due to the influence of the opposite charge groups in these systems.
    Additional Material: 2 Ill.
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  • 91
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 1009-1015 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The scandium naphthenate/trialkylaluminum system was investigated as a catalyst in the polymerization of substituted alkynes. Phenylacetylene was converted to a moderately crystalline, high cis polymer. The alkyl-substituted acetylenes produced rubbery or solid materials of relatively high molecular weight. Infrared (IR), ultraviolet (UV), 1H-NMR, and 13C-NMR studies of the polyalkylacetylenes revealed high cis conformation, but apparently twisted from planarity to decrease molecular orbital overlap in the polyconjugated chain.
    Additional Material: 3 Ill.
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  • 92
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 1043-1053 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The influence of the reaction medium on the polycondensation of the tetranitriles of tetracarboxylic acids and diamines has been investigated. The reaction in phenol and cresols yields polymers with macroheterocycles in the chain - polyhexasocyclanes. If phenols with electron-accepting substituents are used as reaction medium, nonmacrocyclic polymers with side aroxyl groups in the chain, polyisoindoxazenes - are formed. The properties of these polymers were studied. Macroheterocyclic compounds formed by condensation of phthalodinitrile with diamines can be used as one of the initial substances in polyhexasocyclane synthesis. Polyamidohexasocyclanes were prepared by polycondensation of macroheterocycles with dicarboxylic acid dichlorides. Some regularities of their formation and their properties were investigated.
    Additional Material: 2 Ill.
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  • 93
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 1055-1064 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phosphorus-containing polyamides and polyesters, which had tricyclic fused rings (phenothia-phosphine rings) in the main chain, were prepared and the properties of the resulting polymers were examined. These polymers were obtained at highly reduced viscosities in satisfactory yields by the polycondensation of 2,8-dichloroformyl-10-phenylphenothiaphosphine 5,5,10-trioxide with aromatic diamines or bisphenols. The polyamides and polyesters were soluble in polar aprotic solvents such as dimethylacetamide and N-methyl-2-pyrrolidone; the polyesters were also soluble in chloroform. The polymers exhibited good heat resistance. The phenothiaphosphine-containing polyamides and polyesters self-extinguished immediately when flame was removed and were highly flame-resistant. The polyester obtained from bisphenol A showed a limiting oxygen index value of 43.5.
    Additional Material: 1 Ill.
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  • 94
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 1077-1084 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Homopolymers of vinylruthenocene and its copolymers with methyl acrylate, styrene, and n-vinylpyrrolidinone have been prepared by free-radical polymerization. No evidence for the electron transfer termination mechanism postulated for polymerization of vinylferrocene was observed. Yields of soluble polymers were 40-90% with Mw (4-25) × 103 and Mw/Mn = 3.0-13.2. TGA analysis showed little weight loss up to 300°C but rapid decomposition above 300°C. Polyvinylruthenocene is a highly brittle material with Tg above 250°C. Torsional braid analysis of the copolymer samples showed Tg in the range 90-130°C which in some samples increased upon cooling and reheating. Several samples showed weak thermal transitions occurring prior to or following Tg. The rise in Tg upon cooling and reheating is indicative of possible decomposition, crosslinking, or realignment of the polymer chains.
    Additional Material: 4 Ill.
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  • 95
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 1179-1186 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Vinyl-4,4-disubstituted azlactones were shown to be effective comonomers in free radical addition polymerizations for purposes of subsequently preparing radiation-sensitive materials by attaching an unsaturated nucleophile. The azlactone-functional copolymers could be reacted with amine-, thiol-, and hydroxy-functional nucleophiles over the course of a few hours in solution at room temperature to effect covalent attachment of the nucleophile. The electron beam- and UV-sensitive materials were shown to be useful as photoresist and embossable video disk recording media.
    Additional Material: 1 Ill.
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  • 96
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 1153-1177 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Asymmetric polyamides from the reaction of either optically active trans-1,2-cyclopropanedicarboxylic acid (C3) or trans-1,2-cyclohexanedicarboxylic acid (C6) with 2,7-diazaspiro[4,4]nonane(DSN) were synthesized. The possible conformations of these polymers and their model compounds in 2,2,2-trifluoroethanol (TFE), water, methanesulfonic acid (MSA), and sulfuric acid were examined by circular dichroism (CD), NMR, viscosity, and dipole moment measurements. The racemic polyamides (±)C3·(±)DSN and (±)C6·(±)DSN exist in extended forms. No intrinsic viscosity changes were observed for these two polymers in TFE and MSA. Certain viscosity and spectral changes have been observed for the optically active polyamides, although no specific ordered conformations can be assigned. The optically active diacid units incorporated into the polymer give a conformation unique from the totally extended chain. CD studies seem to evidence some conformational differences among the polyamide derived from (+)C6 diacid and the optically active DSN. By changing the solvent from TFE to MSA a blue shift of the trough was observed for (+)C6·(±)DSN, a red shift for (+)C6·(-)DSN, and an inversion of the CD spectrum for (+)C6·(+)DSN polyamides. The results of the work with (+)C6·(-)DSN in dilute acid solution suggest that the rotation around the C-N bond is a relatively low-energy process. The spectral and intrinsic viscosity data are consistent with this suggestion. No drastic spectral changes have been observed for the C3·DSN polyamides by changing the solvent from TFE to MSA. The amide group in the C3·DSN polyamide and the corresponding model compound prefer a similar conformation with the carbonyl group bisecting the cyclopropane ring. The C3·DSN polyamide seems to exist in an extended form.
    Additional Material: 17 Ill.
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  • 97
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 1243-1250 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rate of reaction of alkyl halides with aqueous sodium acetate or cyanide catalyzed by phosphonium salts supported on insoluble polystyrene resins, and rates of ion-exchange of the chloride ion in the catalysts against the acetate ion, were studied as a function of catalyst particle size, the percentage of ring substitution, the morphology of polymer support, and distance between active site and polymer backbone. Rates of 1-bromooctane or benzyl chloride with macroporous, 7-25% ring-substituted catalysts increased with increasing ring substitution. Rates with macroporous catalysts increased as a heptamethylene spacer was introduced between the active site and the polymer backbone. Rates of ion-exchange with macroporous catalysts were facilitated with increasing ring substitution or by the introduction of the spacer chain. A relation between the catalytic activity of macroporous or microporous catalysts and ion-exchange rates under triphase conditions was discussed.
    Additional Material: 6 Ill.
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  • 98
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    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 1251-1258 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polymerization of the cyclic amide of PIII is described for the first time. The N,N-diethylamine-1,3,2-dioxaphosphorinan was shown to give living reversible polymerization with anionic initiators. Lithium and sodium derivatives were found to be inactive. 1H-, 13C-, and 31P-NMR indicated that the polymer strictly reflects the monomer structure and is formed without any isomerization, the polymer chain being $\rlap{--} ({\rm OP}\left( {{\rm NR}_{\rm 2} } \right){\rm O(CH}_{\rm 2} \rlap{--} )_3 )_n $. Initiation involves attack of the anion on the P atom. From the dependence of the equilibrium monomer concentration on temeprature ΔH1s = 1.5 ± 0.2 kcal·mol-1 and ΔS1s = 4.6 ± 0.6 cal·mol-1·°K-1.
    Additional Material: 3 Ill.
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  • 99
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 1267-1280 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Copolymers of trans-4-acryloxyazobenzene (AAB) with (-)-menthyl acrylate (MtA) have been prepared by free radical initiation; comonomer reactivity ratios have been found to be rAAB = 0.89 and rMtA = 0.53. Dependence of chiroptical properties on copolymer composition has been investigated and contribution to circular dichroism by azobenzene chromophores of isolated and sequence AAB units, as well as the influence of the trans to cis photoisomerization, have been determined. Kinetics of photoinduced trans → cis and thermally induced cis → trans isomerization of azobenzene side chains have also been examined and the kinetic parameters evaluated with relation to copolymer structure. The results have been discussed in terms of light-induced secondary structure reversible modifications.
    Additional Material: 8 Ill.
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  • 100
    Electronic Resource
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 22 (1984), S. 1259-1265 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aromatic polyphosphonates of high molecular weights were prepared from phenylphosphonic dichloride and bisphenols having rigid ring structures by the two-phase polycondensation in organic solvent-aqueous alkaline solution system with phase-transfer catalyst at 0°C or below. The effects of reaction solvent and catalyst on the inherent viscosities of the polymers formed are studied. The glass transition temperatures of the polyphosphonates with biphenyl, phenylindane, and diphenylfluorene units are 120, 124, and 188°C, respectively. These polymers are self-extinguishing and are readily soluble in solvents such as N,N-dimethylacetamide, pyridine, tetrahydrofuran, and chloroform. They began to lose weight above 300°C in air. Copolyphosphonates from combinations of bisphenols and phenylphosphonic dichloride are also prepared and characterized.
    Additional Material: 1 Ill.
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