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  • Electronic Resource  (3,462)
  • 1985-1989  (3,462)
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  • 1989  (1,808)
  • 1988  (1,654)
  • General Chemistry  (2,292)
  • Engineering General  (1,106)
  • Industrial Chemistry and Chemical Engineering
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  • Electronic Resource  (3,462)
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  • 1
    Electronic Resource
    Electronic Resource
    Computation of the Frequency Distributions of Distances Between Particles Randomly Dispersed in a Fluid Flow (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 13-16 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pulse holography can be used as a method for the experimental investigation of transport processes that occur in flows of dispersed phases. Since a complete evaluation of a hologram involves the measurement and recording of the position of every individual particle, it delivers all the information about the spatial distribution of particles at the instant of exposure.An exact knowledge of the spatial distribution of the dispersed phase is particularly important for those chemical engineering processes which require the spatial distribution of particles to be as homogeneous as possible. Maximum homogeneity is achieved when the particles are distributed purely randomly. For this case, the distributions of distances between neighbouring particles are calculated. They represent a standard which can be adopted as the basis for the assessment of real particle distributions, such as exist momentarily in flows of dispersed phases and are determined by the evaluation of pulse holograms.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060102
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  • 2
    Electronic Resource
    Electronic Resource
    Announcements (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 48-50 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060107
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  • 3
    Electronic Resource
    Electronic Resource
    Measurement of Particle Rotational Velocity Using a Laser AnemometerPresented at the 4th International Symposium on Applications of Laser Anemometry to Fluid Mechanics, Lisbon (Portugal), July 11-14, 1988. (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 59-63 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An electrodynamic balance and a frequency shifted Laser Doppler Anemometer (LDA) were used to obtain rotational velocity data from nonspherical particles undergoing pure rotation. A charged oil shale particle (150μm × 150 μm × 60 to 80 μm thick) was suspended in an electric field and rotated at a constant velocity by subjecting it to a vertical air jet. The measuring volume of the LDA was located on the particle, and Doppler bursts were observed from both stationary and rotating particles. This observation suggests that micron-sized surface irregularities can act as individual scattering sources for LDA measurements. Signal analysis was performed with a counter type processor and a PDP-11 computer. The particle motion was recorded on video tapes from which the true rotational velocity and maximum radius of rotation were obtained. Within the experimental uncertainties, the maximum rotation-induced surface velocity measured with the LDA agreed well with that obtained from video tapes.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060109
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  • 4
    Electronic Resource
    Electronic Resource
    Announcements (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 89-91 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060115
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  • 5
    Electronic Resource
    Electronic Resource
    Size Characterization of Liquid-Borne Particles by light scattering counters (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 93-99 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The sizing accuracy of a commercially available laser optical liquid-borne particle counter is investigated. A calibration study, using aqueous suspensions of non-absorbing, monodisperse, spherical polymer particles, and a study using suspensions of non-spherical polydisperse, alumina particles are conducted. The experimental results from the spherical polymer study show an excellent agreement with the theoretical Mie light scattering calculations. The accuracy of the spherical polymer sizing is shown to be within 20% of the actual size. The alumina particle readings are compared to the readings of four different particle sizing instruments and to scanning electron microscope pictures. Although quantitative comparisons are difficult to make between the instruments, the results show a good agreement for the batch of particles with a narrower size distribution.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060117
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  • 6
    Electronic Resource
    Electronic Resource
    A Light Scattering Instrument to Discriminate and Size Fibres Part 1: A theoretical description using the RGD approximation (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 110-118 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: As part of the development of a light scattering instrument to detect fibres, scattered light from finite cylinders which are exposed to light at arbitrary orientation is studied using the Rayleigh - Gans - Debye approximation. Form anisotropy, which is crucial to the performance of the instrument, is allowed for by using the Shifrin modification in which the elemental volumes are considered to be prolate spheroids. For long cylinders this is compared with van de Hulst's model in which the rigorous theory for an infinite cylinder is modified by Fraunhofer diffraction on the length. For very short cylinders comparison is made with the Mie theory for spheres.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060119
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  • 7
    Electronic Resource
    Electronic Resource
    Single Particle Light Scattering Size Analysis: Quantification and elimination of the effect of particle shape and structure (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 100-109 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: When measuring scattered light from single particles (as realized in various methods of scattered light-particle size counting analysis) nonspherical particles and particles with inner structure produce different signal heights (scattered light intensities) when differently oriented in the measuring volume. To study the influence of the particle shape and structure, the representative spectrum of all signal heights reflecting all of the possible orientations of the particle in the measuring volume was recorded from individual particles of a definite material in each case. Additionally from every particle an equivalent diameter was determined.The measurements lead to a very precise calibration curve and to a transformation matrix, that describes the influence of shape and structure on scattered light-counting analyses in case of the specific material. It is then possible to simulate measurements to determine the loss in resolution caused by the influence of shape and structure and to eliminate this effect from conventional scattered light analyses.The paper presents the concept together with results of simulation and elimination calculations for the material limestone and quartz. The corrected size distributions are compared with results by other methods. On the basis of this comparison it is discussed how successful the method is to recover a higher resolution.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060118
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  • 8
    Electronic Resource
    Electronic Resource
    The Characterization of Water-Droplet Aerosols by polytec optical particle analysersPresented at the 4th European Symposium Particle Characterization, Nürnberg, 19-21. April 1989. (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 119-123 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A single-stage impactor has been used to calibrate a Polytec HC-15/1 optical aerosol analyser so that this instrument can be used to study water droplets from approximately 1 to 20 μm aerodynamic diameter. The resulting calibration data were in good agreement with calculations based on Mie light scattering theory, and gave a conversion factor of 2.0 ± 0.2 between polystyrene latex microspheres and water droplets of the same aerodynamic diameter.Monodisperse water droplets were sampled by a Polytec HC-70/2 analyser, calibrated using the conversion factor of 2.0. The measured count median diameter agreed closely with that predicted from the well-defined operating conditions of the vibrating orifice aerosol generator. Size measurements of a polydisperse water-droplet spray were also undertaken with both a Malvern laser diffractometer and a Polytec HC-15 analyser; good agreement was achieved between the two techniques.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060120
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  • 9
    Electronic Resource
    Electronic Resource
    Announcements (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 133-133 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060123
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  • 10
    Electronic Resource
    Electronic Resource
    The Fundamentals of Particle Size Analysis by Means of Ultrasonic Spectrometry (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 135-143 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The interaction of suspended particles with ultrasonic waves can lead to changes in the sonic velocity and also to extinction of the waves. An evaluation of the frequency dependence of ultrasonic extinction offers the most appropriate means of determining the concentration and size distribution of particles suspended in a fluid. With an experimental apparatus covering the frequency range from 1.7 to 81 MHz, particles ranging from about 20 to 1000 μm in diameter can be analysed. The measurements can be conducted with particle concentrations as high as 10% by volume.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060124
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  • 11
    Electronic Resource
    Electronic Resource
    Lower Detection Limit of an Optical Particle Counter in the measurement of particle size distributionsPresented at the 4th European Symposium Particle Characterization, Nürnberg, 19.-21. April 1989. (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 124-128 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An Optical Particle Counter with optically defined measuring volume was investigated with regard to an application in the range of fine particles (f.i. water droplets less then 1.5 μm in diameter). Because of a problematic detection behaviour in the examined size range caused by the analogue signal processor, it was necessary to explore signals generated by the measurement system. In view of the results obtained an alternative signal evaluation method was developed on basis of a digital system. The high flexibility of software systems in signal processing rendered possible on the one hand a clear definition of the lower detection limit of the instrument. On the other hand it was possible to lower the detection limit and herewith the size of particles to be resolved. A practical application for the new evaluation technique is given by the measurement of fractional efficiency curves of technical separators and classifiers, which clearly shows the advantages of the system presented. Most recent investigations are concerned with the maximum number concentration detectable with the Optical Particle Counter, which could be increased up to five times.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060121
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  • 12
    Electronic Resource
    Electronic Resource
    A Light Scattering Instrument to Discriminate and Size Fibres. Part II: Experimental system (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 144-150 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A Light scattering technique is described which can discriminate, size and count airborne fibres down to 1.6 μm diameter. The results are compared with Mie theory for spheres and two models for finite cylinders based on the Rayleigh-Gans-Debye approximation and rigorous infinite cylinder theory modified by Fraunhofer diffraction on the length.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060125
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  • 13
    Electronic Resource
    Electronic Resource
    The Use of Particle Image Velocimetry to Study Roping in Pneumatic ConveyancePresented at the 4th European Symposium Particle Characterization, Nürnberg 19.-21 April 1989. (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 129-132 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Particle Image Velocimetry (PIV) is a new technique which provides an instantaneous velocity profile of a flow field. A PIV system at Edinburgh University has been adapted to study the phenomenon of roping in a pneumatic particle conveyance rig. The principle features of this PIV system are as follows. Double images of the particles transported by the fluid are recorded on photographic film using a conventional camera. The displacement of the particle pairs, which determines the velocity at a particular point, is determined to an automatic analysis system. PIV is proving to be a powerful method in the investigation of roping. A rope is a high density ribbon of particles which is created when a uniform air-coal flow segregates at a pipe bend into two regimes: one has a low coal to air ratio whereas the second regime, termed the rope, has a high coal to air ratio. This particular problem is connected with the pulverised fuel (pf) pipes of coal-fired electricity generating stations. The flow, as seen on Figure 1, is reproduced in a 26 mm scale model encompassing the main aerodynamic features of pf pipes. The rope forms in the vertical to horizontal 90° bend, falls from the top to the bottom of the horizontal pipe and creats a deposit.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060122
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  • 14
    Electronic Resource
    Electronic Resource
    Comparative Study of some Probability Distributions Applied to Liquid Sprays (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 151-162 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A comparative study of a few probability distributions generally used in describing various spray properties based on droplet size and velocity is described. Four different size distributions and three different coupled distributions, representing jointly size and velocity, are considered. A comparison of the results calculated for eight sets of data, taken from three different sources for the size distribution, and one data set for the joint size and velocity distribution, shows that the log-hyperbolic function presents the best choice among both one- and two-dimensional distributions.Considerations on one- and two-dimensional probability distributions are followed by a description of the conservation laws and their use in the prediction of the loss of momentum and energy of doplets. Finally, a proposal is made for how the sprays should be studied experimentally and analysed theoretically in order to obtain the maximum possible information. A few suggestions are then provided for further research in this direction.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060126
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  • 15
    Electronic Resource
    Electronic Resource
    Determination of Effective Surface Area for the Chemical Reaction of Fine Particulate Materials (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 163-167 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A concept of effective surface area was defined as a geometrical controlling factor for a chemical reaction involving powdery materials. It is not uniquely determined for the specific material but depends on the sort of chemical reaction as well as the state of agglomeration. Case studies were given for dissolution or decomposition reaction for MgO, Mg(OH)2 and Pb(CO)3 with and without preliminary mechanical activation and granulation. The effective surface area for dissolution is mostly the external surface of the agglomerates, although the internal surface plays a role to some extent, depending on the compactness of the agglomerates.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060127
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  • 16
    Electronic Resource
    Electronic Resource
    Fractal Mathematics Applied to Flow in Porous Systems (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 168-175 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Leitz TAS-Plus image analysis system was programmed to automatically measure both the ‘shape’ fractal and ‘fragmentation’ fractal for various types of fine particle filter cakes. The automated nature of the analysis facilitated the collection of statistically significant volumes of ‘fractal’ data. This data was then revised, where possible, to conventional theories of flow behavior. Several new insights evolved from the study as explained in the following analysis.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060128
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  • 17
    Electronic Resource
    Electronic Resource
    Properties of SpraysPaper prepared for presentation at the International Conference on Mechanics of Two-Phase Flows, Taipei, Taiwan, June 12-15, 1989. (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 176-186 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The spray properties of most practical importance, namely mean drop size, drop size distribution, radial and circumferential liquid distribution, cone angle and penetration, are discussed in the context of plain orifice, pressure-swirl, plain-jet airblast and prefilming airblast atomization. Equations are presented for estimating mean drop size and spray cone angle in terms of the relevant liquid properties, gas properties, atomizer dimensions, and atomizer operating conditions. The relative merits of these equations are discussed and compared. Some aspects of atomization in need of further research are indicated.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060129
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  • 18
    Electronic Resource
    Electronic Resource
    Announcements (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 187-188 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060130
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  • 19
    Electronic Resource
    Electronic Resource
    Removal of Adhering Particles of Polystyrene Latex and iron oxide on a wall by shear flow in water (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 69-73 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The velocity for removal of particles adhering on a wall has been measured for polystyrene latex (PSL) and iron oxide particles at laminar and turbulent flow in a glass cell. The results indicate that larger particles detache at lower flow velocities and the width of the velocity range for removing adhering particles is wider when the particle size is smaller in the laminar flow regime. Both the viscous drag force for removing particles determined experimentally and the adhesive force obtained theoretically are proportional to the particle diameter, and the coefficients of friction were estimated to be 0.01-0.08 and 0.01-0.02 for PSL and iron oxide particles, respectively. The ranges of the viscous force, the adhesive force and the coefficient of friction are not so far from the values given by Kanaoka et al. [2].
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060111
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  • 20
    Electronic Resource
    Electronic Resource
    A Laser Multi-focus System for the Measurement of Particle Size, velocity and refractive indexPresented at the 4th International Symposium on Applications of Laser Anemometry to Fluid Mechanics, Lisbon (Portugal), July 11-14, 1988. (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 64-68 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A laser multi-focus velocimeter (LMFV) for measuring particle diameter, velocity and refractive index simultaneously is described. A phase diffraction grating with pulse width modulation is used to obtain several focal points with almost equal intensity and to construct the optical system. The fringes of the LMFV using multi-beam interference have a sharper intensity distribution and wider period than those of a laser Doppler velocimeter using two-beam interference. Therefore, the LMFV makes it possible to measure high velocities and large particle diameters with high accuracy. The validity of the method was confirmed theoretically and experimentally.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060110
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  • 21
    Electronic Resource
    Electronic Resource
    A Sampler for Total Suspended Particulates with Size Resolution and high sampling efficiency for large particles (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 74-80 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: For a field intercomparison of various widely used dust samplers, a reference instrument was needed. Based on a Wide Range Aerosol Classifier (WRAC), several improvements were introduced compared with the original design including mass flow control of the samplers and the plenum air, brushless threephase blowers, hyperbolic inlets and generally a more compact design, allowing for more comfortable operation. In addition, for measurement of small particle size distributions, a Hauke high-volume, low-pressure impactor (LPI 150/0.15) was included, so that size distribution information with cuts at 0.12, 0.30, 1.19, 3.14, 10.2, 20.4, 37.4 and 60 μm could be obtained. In addition, the aspiration efficiency was measured under in situconditions and parallel measurements were performed with the two reference samplers built so that the performance was well characterized.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060112
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  • 22
    Electronic Resource
    Electronic Resource
    Regularized Inversion of Correlation Functions in Dynamic Light Scattering (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 28-33 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A linear regularized technique, requiring no a priori information, is described for the inversion of correlation data obtained from dynamic light scattering measurements of polymer/colloidal suspensions. The procedure allows the determination of the characteristic linewidth distribution function, which is normally the first step towards obtaining a particle size distribution.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060104
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  • 23
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    Electronic Resource
    Prediction of the Drop Size and Velocity Distribution in a Spray, Based on the maximum entropy formalismThis paper will be presented at the International Conference on Mechanics of Two-Phase Flows in Taiwan, June 12-15, 1989. (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 17-27 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new basis for the prediction of the drop size and velocity distribution in a spray is developed, using the maximum entropy formalism. The prediction considers the imposition of integral conservation constraints for mass, momentum and mechanical energy on the breakup of an undulating liquid sheet. The resulting drop size distribution is similar to the widely used empirical distributions, while the velocity distribution is Gaussian, with a variance that decreases with increasing drop size. Measurements were made in a simple water spray using the Phase/Doppler technique to obtain the joint size/velocity PDF. Photographic measurements were used to obtain an estimate of the geometry of the breakup region, necessary as input to the model. Good agreement was found between the measurements and the predictions, except in the region where drag forces had strongly influenced the distribution. This discrepancy was expected, as drag effects were not included in the model.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060103
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    Characterization of Powder and Pressings Based on Geometric FundamentalsPresented at the 2nd International Conference on Ceramic Powder Processing Science, Berchtesgaden, October 12-14, 1988. (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 39-47 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In addition to chemical composition, geometric properties such as particle size, particle shape, specific surface area and microporosity are important for the production of sintered materials. They influence, e.g., the packing density of green bodies, the sinter activity and the microstructure of the final products. Different measuring methods are surveyed, with a critical view of sensitivity and evaluation of measurement data, and new devices are discussed, including laser and centrifuge methods for particle size measurement and sorption methods with krypton as adsorbate for the measurement of specific surface area and microporosity. Finally, a correlation between the particle size and the specific surface area using fractals is discussed.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060106
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    Light Scattering at a Small Angle with the Use of Lorenz-Mie Theory in Particle Sizing (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 86-88 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Problems connected with particle sizing with the use of radiation power measurement at a small angle (θ = 0.5° - 10°) where the Lorenz-Mie theory is a mathematical model of the phenomenon are discussed. As an example, a computer program LICZ, allowing for the shortest calculation time, yet preserving satisfactory accuracy of calculations, is considered.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060114
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    Experimental Characterization of Fineparticle Profiles Exhibiting Regions of Various Ruggedness (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 1-12 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In previously reported studies it has been shown that a rugged two-dimensional fineparticle profile boundary may exhibit different ruggedness at different levels of scrutiny. The different types of ruggedness can sometimes be described by a boundary fractal dimension the magnitude of which can be related to the physical processes which formed the fineparticle. New data illustrating this fact is presented. Detailed examination of some rugged fineparticle boundaries and similar structures suggests that some boundaries exhibit more than one level of ruggedness around the perimeter of the profile. Data illustrating this fact are presented. The possible physical significance of the multifractal structure around the perimeter of a fineparticle profile is discussed. The need for objective criteria to be followed when splitting profiles into regions of different ruggedness is discussed. The possibility of basing the partition algorithm on the inspection of the sequential chord length generated in an equipaced exploration of the perimeter is suggested.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060101
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    Applications of Prism-Cell Light-Scattering Spectrometer to Particle Sizing in Polymer Solutions (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 34-38 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A prism-cell light-scattering spectrometer has been modified to accept both a diode-array detector for measurements of angular distribution of scattered intensity and a photomultiplier tube for measurements of time-dependent intensity-intensity correlation function. This spectrometer permits the practice of light scattering at small scattering angles down to a few degrees. Here we make a brief study of the reliability of characteristic linewidth distributions obtained by several methods of analysis on the correlation data, which correspond to a reasonably broad unimodal distribution. Then the prism-cell light-scattering spectrometer is used to characterize a polymer solution consisting of two different molecular weights. To obtain characteristic linewidth distribution, the correlation data are analyzed by both the constrained regularization method (CONTIN) and the maximum-entropy method (MEM).
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060105
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    Particle Motion in a Turbulent Two-Phase Dilute Suspension Flow (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 51-58 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Presented here is new unified theory on particle motion in a turbulent dilute two-phase suspension flow. Results of numerical calculations based on this theory have been found to agree closely with results of recent in-situ local measurements of a two-phase flow in a vertical pipe by the use of the non-intrusive laser-Doppler anemometry. In particular, a more plausible explanation is now provided for the measured peculiar migratory behaviors of particles in the region close to the pipe wall.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060108
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    Report Joint Meeting of GVC Committees on “Particle Characterization” and “Crystallization”, Winterthur 1988 (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 81-85 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This Committee stood under the banner of joint meetings with the Crystallization Committee. Further it was characterized by two aspects, namely technological innovation in connection with measurement methods and their (on-line) application in engineering processes, whether for the sake of model formation or for process control or quality assurance in industry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060113
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    Erratum (1989)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 6 (1989), S. 91-91 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19890060116
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    Non-linear stochastic response of marine vehicles (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 27 (1989), S. 169-183 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The dynamic behaviour of marine vehicles in extreme sea states is a matter of great concern following some recent and dramatic mishaps. The complex problem of its prediction can be approached from the study, yet of broader scope, of non-linear dynamic systems subjected to stochastic excitations. However, a general non-linear stochastic dynamic theory is not yet available.A new technique, the so-called linearize-and-match method, for predicting the response statistics of non-linear systems, is presented. Essentially, the technique involves the construction of an infinite series of linear systems aimed at the prediction of the response statistical moments of a given order.The linear systems are successively defined by linearizing the original, non-linear system and matching the Volterra functional model response statistics to the desired order. The linear system for predicting second order statistics is shown to coincide with the one obtained using the method of equivalent linearization.Response probability distributions can be constructed from the knowledge of such statistics. Particular attention is devoted to the distribution of maximum entropy and its justification in such underdetermined moment problems.Finally, applications to the roll motion of ships serve to exemplify as well as to assess the accuracy and the versatility of the overall method. Response distributions of maxima so predicted compare very well with digital simulation estimates.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620270114
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    F.E. solution of a vertically averaged model for regional land subsidence (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 27 (1989), S. 215-230 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In this paper a mathematical model is presented, based on the application of an averaging technique, in which the equations governing the behaviour of saturated porous media are integrated (averaged) over the smallest dimension of the domain of the problem (thickness). This results in a two dimensional model, in which the three dimensional nature of the problem is accounted for. In fact, the solution is sought in terms of the mean values over the thickness of the field variables and of the transverse displacement components. For the solution of the resulting governing equations a partitioned procedure is employed, which improves the efficiency of the method. The proposed model is very useful in solving problems in which the spatial nature prevents the applications of two dimensional models.Examples are presented, which illustrate the validity of this approach.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620270117
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    Some recent developments in numerical modelling of fracture toughness in brittle matrix composites (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 27 (1989), S. 233-255 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Finite element analysis was used to study the fracture toughening of a ceramic by a stress induced dilatant transformation of second phase particles. The finite element method was based on a continuum theory which modelled the composite as subcritical material. Transient crack growth was simulated in the finite element mesh by a nodal release technique. The crack's remote tensile opening load was adjusted to maintain the near-tip energy release rate at the level necessary for crack advance. The transformation zone surrounding the crack developed as the crack propagated through the composite. Resistance curves were computed from the analysis; and the results show that during crack advance maximum toughness is achieved before a steady state is reached.The toughening effect of a crack-bridging ductile phase in a brittle material may be predicted if ligament deformation is characterized. A plastically deforming ligament constrained by surrounding elastic matrix material is modelled using finite elements and the relevant toughness enhancement information extracted. Comparison is made to model experiments as well as to toughness measured for technologically important materials. The results suggest that debonding along the interface between the ligament and the matrix may enhance the toughening effect of a ductile phase.
    Additional Material: 21 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620270203
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    Fatigue life estimation of graphite/epoxy laminates under consideration of delamination growth (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 27 (1989), S. 323-341 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A closed form approach to the assessment of the fatigue life of graphite/epoxy laminates under cyclic tension-compression loading has been developed. The model is mechanistic and uses cyclic energy release rates for prediction of delamination growth and of critical delamination sizes which induce buckling and the final failure of the laminates. Tests performed with graphite/epoxy specimens of stacking order [0n, φm]s with severed central plies [φ], and of stacking order [02, +45, 02, -45, 0, 90]s with a central unloaded hole, indicate good correlation between estimated values and observed delamination growth, critical buckling strength of separated plies and load cycles to failure.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620270208
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    Analysis of viscoelastic structural elements in the frequency domain (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 27 (1989), S. 429-436 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The paper presents a formulation in the frequency domain for the viscoelastic material behaviour of structural elements. This approach is equally valid for deterministic forces, but also in the case of probabilistic descriptions of those forces. The method takes advantage of readily available experimental data and shows how to introduce them in e.g. finite element formulations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620270213
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    Conference diary (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 27 (1989), S. 449-452 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620270215
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    A dual adaptive procedure for the automatic determination of iteration parameters for Chebyshev acceleration (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 27 (1989), S. 483-499 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Chebyshev acceleration for a symmetrizable basic iterative method u(n+1) = Gu(n) + k; requires estimates of the extreme eigenvalues m(G) and M(G) of the iteration matrix G. Adaptive procedures are often used in order to obtain good estimates for m(G) and M(G). Some existing adaptive procedures are able to give an estimate of either m(G) or M(G) but not both on any given iteration. In this paper we present an adaptive procedure which can estimate both m(G) and M(G) at the same time and which has other useful properties. Numerical results are given which show the new procedure usually requires fewer iterations than previous procedures.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/nme.1620270305
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    Experience with the conjugate gradient method for stress analysis on a data parallel supercomputer (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 27 (1989), S. 523-546 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The storage requirements and performance consequences of a few different data parallel implementations of the finite element method for domains discretized by three-dimensional brick elements are reviewed. Letting a processor represent a nodal point per unassembled finite element yields a concurrency that may be one to two orders of magnitude higher for common elements than if a processor represents an unassembled finite element. The former representation also allows for higher order elements with a limited amount of storage per processor. A totally parallel stiffness matrix generation algorithm is presented. The equilibrium equations are solved by a conjugate gradient method with diagonal scaling. The results from several simulations designed to show the dependence of the number of iterations to convergence upon the Poisson ratio, the finite element discretization and the element order are reported. The domain was discretized by three-dimensional Lagrange elements in all cases. The number of iterations to convergence increases with the Poisson ratio. Increasing the number of elements in one special dimension increases the number of iterations to convergence, linearly. Increasing the element order p in one spatial dimension increases the number of iterations to convergence as pα, where α is 1·4-1·5 for the model problems.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620270307
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    On an SSOR matrix relationship and its consequences (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 27 (1989), S. 559-570 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A matrix relationship connecting the Jacobi and the Symmetric Successive Overrelaxation (SSOR) matrices associated with a k-cyclic consistently ordered matrix A is presented. Next the equivalence of the SSOR method and a certain monoparametric k-step one for the solution of the linear algebraic system Ax = b is established. The aforementioned equivalence can be exploited to derive regions of convergence, optimum parameters involved, etc. of the two iterative methods above. This is done by studying the simplest of the two methods that is the monoparametric k-step one. To show how the idea works the case k = 2 is very briefly discussed.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620270309
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    On a class of preconditioned iterative methods on parallel computers (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 27 (1989), S. 637-654 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The standard implementations of iterative solvers for finite element and finite difference methods frequently use a diagonal (Jacobi) preconditioner, particularly for element-by-element schemes. However, for such methods the actual order of the condition number with respect to mesh size is not reduced by the preconditioner. In the present paper we describe an iterative method where, in addition, the condition number is reduced by an order of magnitude. Moreover, the scheme may also be implemented as an element-by-element method. The method uses a generalized SSOR preconditioner and a wave front or multi-frontal ordering of the mesh nodes. For a general irregular finite element mesh a striped irregular wave front ordering may be used. The performance of the method as well as various iterative acceleration techniques for a parallel computer are examined in the numerical studies.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620270314
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    Correction (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. ii 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620280102
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    Geometrically non-linear formulation for three dimensional curved beam elements with large rotations (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 43-73 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper presents a geometrically non-linear formulation (GNL) for the three dimensional curved beam elements using the total Lagrangian approach. The element geometry is constructed using co-ordinates of the nodes on the centroidal or reference axis and the orthogonal nodal vectors representing the principal bending directions. The element displacement field is described using three translations at the element nodes and three rotations about the local axesThe element displacement field has also been described in the literature using Euler parameters, Milenkovic parameters, or Rodriges parameters representing the effects of large rotations.. The GNL three dimensional beam element formulations based on these element approximations are restricted to small nodal rotations between two successive load increments. The element formulation presented here removes such restrictions. This is accomplished by retaining non-linear nodal terms in the definition of the element displacement field, and the consistent derivation of the element properties. The formulation presented here is very general and yet can be made specific by selecting proper non-linear functions representing the effects of nodal rotations. The details of the element properties are presented and discussed. Numerical examples are also presented to demonstrate the behaviour and the accuracy of the elements. A comparison of the results obtained from the present formulation with those available in the literature using a linearized element approximation clearly demonstrate the superiority of the formulation in terms of large load steps, large rotations between two load steps and extremely good convergence characteristics during equilibrium iterations. The displacement approximation of these elements is fully compatible with the isoparametric curved shell elements (with large rotations), and since the elements possess offset capability, these elements can also serve as stiffeners for the curved shells.
    Additional Material: 16 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620280106
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    Evaluation of boundary integrals for plate bending (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 75-93 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The alternative to quadrature, as a procedure for dealing with the integrations required in the direct boundary element method (DBEM), is to carry out the integration analytically and code the results directly. The potential benefits are efficient computer programs; the avoidance of numerical instability; and generally, better accuracy. The technique is developed in this paper.Serious problems arise when Gauss quadrature is employed for the integration of functions which contain, or are close to singularities. A numerical integration approach may fail at the first stage of the analysis, that is, during the assembly of the discrete equations; or it may fail at the subsequent stage of computing domain points near the boundary. The severity of the problem is dependent both on the strength of the singularity, and on geometry. These points are illustrated with examples.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620280107
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    Frictionless geometrically non-linear contact using quadratic programming (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 127-144 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The successive quadratic programming (SQP) method is used with the finite element method (FEM) to solve frictionless geometrically non-linear contact problems involving large deformations of the elastica in the presence of flat rigid walls. To formulate the SQP problems, the potential energy (PE) is expanded in a Taylor series of second order in displacement increments about a configuration near a contact solution. The SQP problems consist of minimizing the Taylor expansion of the PE subject to the inequality constraints which represent contact. The quadratic programming (QP) method is made part of a Newton-Raphson (NR) search in which the QP corrections are made when a NR step does not satisfy the constraints. A revised simplex method developed by Rusin is used to solve the QP problems. The elastica is modelled with a total Lagrangian FEM developed by Fried. Solutions are obtained for the end loaded buckled elastica in point contact with a rigid wall and for a uniformly loaded elastica in regional contact with a rigid wall. The problems are also solved using a penalty method. The results obtained for the point contact problem are compared to an analytical solution. Calculations were made to obtain numerical information on maximum load step size and the number of inverse operations required for each load step. Cases in which the elastica stiffened substantially as a result of the initiation of contact are also discussed.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620280110
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    The FDM in arbitrary curvilinear co-ordinates - formulation, numerical approach and applications (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 261-277 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The basic concept, formulation and numerical application of a fully automatic version of the finite difference method (FDM) on a two-dimensional manifold embedded in three-dimensional Euclidean space are presented. This version of the FDM was developed in order to enable automatic solution of problems formulated in arbitrary curvilinear co-ordinate systems in terms of covariant derivatives (e.g. shell equations).In the classical version of the FDM all operations in the curvilinear co-ordinates (the derivation of base vectors, curvature tensors and so on) have to be performed manually. The goal of the present work was to transfer this job to a computer, in order to minimize the user's effort during the numerical formulation of the physical problem. The relevant version of the fully automatized program FIDAMF, based on the FDM on arbitrary irregular grids,1,2 has been worked out. This code performs automatically all stages of the numerical analysis, starting from the mesh generation and approximation of the shape of the manifold, through computation of necessary objects on this manifold, to the solution of linear or non-linear problems formulated in terms of covariant derivatives.The method has been extended to the analysis of problems in which the co-ordinate system changes during the computation (e.g. the analysis of large deformations in the convectional description). This version of the curvilinear FDM was applied to the analysis of large deformations of hyperelastic membrane shells.The approach and the numerical routines, although used here with the FDM, can be combined with any other approximation method, in particular the finite element method.
    Additional Material: 16 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620280203
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    Approximate direct-search minimax circuit optimization (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 359-368 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A direct-search optimization strategy, involving pattern-searches, pattern-moves and a simplex algorithm, has been applied to a number of frequency-domain circuit problems. We show that an approximate minimax result can be obtained with our simple approach, which includes using a modified minimax error function. In the examples attempted, the method comes quite close to the accuracy, if not the efficiency, of true minimax optimizers, and yields an accuracy as good as or better than a least-pth (p = 10) gradient optimizer. The method is broadly appropriate wherever it is difficult or inconvenient to calculate the gradients required for conventional minimax optimization.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620280208
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    Implementation of curvilinear geometry into p-version HT plate elements (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 431-443 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The formulation of the recently presented hybrid-Trefftz (HT) p-version elements1 has thus far been restricted to straight-sided polygonal elements. The present paper removes this limitation. Two alternative formulations are studied. In the first one any curvilinear geometry is represented accurately but the rigid body modes are recovered only in the limit as the p-refinement level is increased. In contrast, the second formulation represents the rigid modes exactly while the actual curvilinear geometry is approached with increasing accuracy as the p-refinement level is increased. The practical efficiency of the two alternative approaches is studied and assessed on pertinent examples of thin plates in bending.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620280212
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    Books received (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 477-478 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620280217
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    Conference diary (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 483-487 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620280220
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  • 50
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    A discrete shear triangular nine D.O.F. element for the analysis of thick to very thin plates (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 533-560 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper deals with the formulation and the evaluation of a new three node, nine d.o.f. triangular plate bending element valid for the analysis of thick to thin plates. The formulation is based on a generalization of the discrete Kirchhoff technique to include the transverse shear effects. The element, called DST (Discrete Shear Triangle), has a proper rank and is free of shear locking. It coincides with the DKT (Discrete Kirchhoff Triangle) element if the transverse shear effects are not significant. However, an incompatibility of the rotation of the normal appears due to shear effects. A detailed numerical evaluation of the characteristics and of the behaviour of the element has been performed including patch tests for thin and thick plates, convergence tests for clamped and simply supported plates under uniform loading and evaluation of stress resultants. The overall performance of the DST element is found to be very satisfactory.
    Additional Material: 19 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620280305
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    Efficient optimization of integrated aerodynamic-structural design (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 593-607 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The introduction of composite materials is having a profound effect on the design process. Because these materials permit the designer to tailor material properties to improve structural, aerodynamic and acoustic performance, they require a more integrated multidisciplinary design process. Because of the complexity of the design process numerical optimization methods are required.The present paper is focused on a major difficulty associated with the multidisciplinary design optimization process - its enormous computational cost. We consider two approaches for reducing this computational burden: (i)development of efficient methods for cross-sensitivity calculation using perturbation methods; and (ii) the use of approximate numerical optimization procedures. Our efforts are concentrated upon combined aerodynamic-structural optimization. Results are presented for the integrated design of a sailplane wing. The impact of our computational procedures on the computational costs of integrated designs is discussed.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620280308
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    Structural modifications simulated by virtual distortions (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 645-666 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A numerical strategy for the simulation of structural modifications by virtual distortions is proposed. Two cases of structural modification are considered: the first concerns modifications of material distribution, and the second modifications of local constitutive relations (e.g. unilateral constraints for stresses or deformations). A formaulation of the fundamental equations of the simulation method is presented. These equations are applicable to the general structural modification problem of a truss-like structure. Then numerical algorithms which refer to particular applications, such as progressive collapse analysis or the analysis of structures with gaps, are discussed.The versatility of the method is illustrated with a number of examples, and the computational advantages of structural modification by the virtual distortion method are discussed.
    Additional Material: 16 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620280312
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    Computational plasticity, Edited by D. R. J. Owen, E. Hinton and E. Oñate, Pineridge Press, Swansea, U.K., 1987. No. of pages: 1865. ISBN 0-906674-61-1 (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 725-726 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620280317
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    First-order design sensitivities for transient conduction problems by an adjoint method (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 733-752 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An adjoint approach is presented for the design sensitivity analysis of transient conduction problems. Variations of a general design functional are expressed in explicit form with respect to all design quantities, i.e. material properties, shape, applied thermal loads including convection, and initial conditions. The methodology incorporates the mutual energy between the real and adjoint thermal problems and a geometric mapping to describe shape variations. Finite element implementation of the method is discussed and an example is provided. Some potential difficulties that might be encountered when using the adjoint method with the finite element method are addressed. These involve the application of impulse loadings and Dirac temperature fields in the adjoint loadings.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620280402
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    A comparison of direct and preconditioned iterative techniques for sparse, unsymmetric systems of linear equations (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 801-815 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In this paper we compare direct and preconditioned iterative methods for the solution of nonsymmetric, sparse systems of linear algebraic equations. These problems occur in finite difference and finite element simulations of semiconductor devices, and fluid flow problems.We consider five iterative methods that appear to be the most promising for this class of problems: the biconjugate gradient method, the conjugate gradient squared method, the generalized minimal residual method, the generalized conjugate residual method and the method of orthogonal minimization. Each of these methods was tested using similar preconditioning (incomplete LU factorization) on a set of large, sparse matrices arising from finite element simulation of semiconductor devices. Results are shown where we compare the computation time and memory requirements for each of these methods against one another, as well as against a direct method that uses LU factorization to solve these problems.The results of our numerical experiments show that preconditioned iterative methods are a practical alternative to direct methods in the solution of large, sparse systems of equations, and can offer significant savings in storage and CPU time.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620280406
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    On the modelling of scalar and mass transport in combustor flows (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 861-877 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The results of a numerical study of swirling and non-swirling combustor flows with and without density variations are presented. Constant-density arguments are used to justify closure assumptions invoked for the transport equations for turbulent momentum and scalar fluxes, which are written in terms of density-weighted variables. Comparisons are carried out with measurements obtained from three different axisymmetric model combustors. The three experiments cover recirculating flow, swirling flow and variable-density, swirling flow inside model combustors. Together, they offer wide ranging flow conditions to test the validity of the models. Results show that the Reynolds stress/flux models do a credible job of predicting constant-density, swirling and non-swirling combustor flows with passive scalar transport. However, their improvements over algebraic stress/flux models are marginal. The extension of the constant-density models to variable-density flow calculations shows that the models are equally valid for such flows. Therefore, the present results argue well for the adoption of constant-density models for variable-density flows until a successfully validated variable-density model is available.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620280410
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    Numerical modelling of wave propagation using parabolic approximation with a boundary-fitted co-ordinate system (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 27 (1989), S. 37-55 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: With a boundary-fitted curvilinear co-ordinate system, the parabolic approximation is applied to the mildslope equation to describe the wave propagation. Both refraction and diffraction are included in the numerical model. Because the shoreline coincides with one of the curvilinear co-ordinates, the numerical model can be used to compute wave propagations near an irregular shoreline.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620270105
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    Study of the behaviour of oscillatory waves in a lagoon (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 27 (1989), S. 103-112 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620270109
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    A three dimensional global weather prediction model using a finite element scheme for vertical discretization (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 27 (1989), S. 129-144 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A global three dimensional model for numerical weather prediction is described. It uses spheric harmonic basis functions with triangular truncation in the horizontal and a finite element discretization for the vertical. Model experiments are used to compare this model with another version, which uses a finite difference scheme for vertical discretization.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620270111
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    The influence of the form of the log-conductivity covariance on non-Fickian dispersion in random permeability fields (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 27 (1989), S. 185-193 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The paper deals with non-Fickian dispersion of inert solutes in random permeability fields. Attention is focused critically on the statistical characterization of the porous medium which affects pollutant dispersion in groundwater. After a brief account of recent results of stochastic theories of transport in porous media and of the fundamental indications of large-scale field experiments, it is inferred from numerical studies that the particular choice of an analytical form of covariance of log-conductivity has a poor influence on the overall dispersion process. In fact, different covariance structures with the same macroscale (a measure of the distance between two points beyond which the permeability ceases to be correlated) yield very similar dispersion processes. The result has a noteworthy bearing on field studies of pollutant dispersion in groundwater because it underlines the reliability of exponential correlation structures yielding analytical expression for time-varying macrodispersion coefficients.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620270115
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    Preface (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 27 (1989), S. 231-231 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620270202
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    A consistent tangent stiffness matrix for three-dimensional non-linear contact analysis (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 1803-1812 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A consistent tangent stiffness matrix for the analysis of non-linear contact problems is presented. The associated element has three or four nodes and establishes contact between three-dimensional structures like solids and shells. It accounts for the non-linear kinematics of large deformation analysis and guarantees a quadratic convergence rate. Two formulations, the penalty method and the Lagrange multiplier method, are investigated.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620280807
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    On the accuracy of some domain-by-domain algorithms for parallel processing of transient structural dynamics (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 1855-1874 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Two domain-by-domain algorithms, suitable for coarse-grained parallel processing analysis of the transient structural dynamics equation, are investigated for accuracy. The application under specific consideration is the analysis of three-dimensional framed structures subjected to time-varying loading. The domain-by-domain approaches attempt to include the advantageous aspects of both conditionally stable explicit algorithms, which require no simultaneous solution of equations and employ simple communication, and unconditionally stable implicit algorithms, which permit large time steps. The alternating group explicit algorithm is developed for finite element analysis, and its accuracy is investigated for a linear formulation. The group implicit algorithm is extended to non-linear finite element analysis, and its accuracy is investigated for the frame dynamics application. Both algorithms are shown to provide inadequate accuracy for practical time step sizes.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620280811
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    Accuracy in finite element computation for eigenfrequencies (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 1929-1949 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In this paper we propose an original numerical method to get upper and lower bounds for the eigenfrequencies of an elastic structure.This method is based on a ‘static’ formulation for eigenvalue problems built up from a new quotient Rs which is defined on a load space. From Rs properties, upper and lower bounds for the exact eigenfrequencies are proved. The application of the method requires the solution of an eigenvalue problem of finite dimension and the computation of a constant which is characteristic of the discretization subspace. Results of numerical tests are given for the vibration problem of an elastic clamped membrane.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620280815
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    A new BEM formulation for acoustic eigenfrequency analysis (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 1965-1967 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620280817
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    Conference diary (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 1971-1975 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620280819
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    Efficient approximation concepts using second order information (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2041-2058 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The primary goal of this paper is to show how second derivative information can be used in an effective way in structural optimization problems. The basic idea is to generate such an information at the expense of only one more ‘virtual load case’ in the sensitivity analysis part of the finite element code. To achieve this goal a primal-dual approach is employed, that can also be interpreted as a sequential quadratic programming method.Another objective is to relate the proposed method to the well known family of approximation concepts techniques, where the primary optimization problem is transformed into a sequence of non-linear explicit subproblems. When restricted to diagonal second derivatives, the new approach can be viewed as a recursive convex programming method, similar to the ‘Convex Linearization’ method (CONLIN), and to its recent generalization, the ‘Method of Moving Asymptotes’ (MMA).This new method has been successfully tested on simple problems that can be solved in closed form, as well as on sizing optimization of trusses. In all cases the method converges faster than CONLIN, MMA or other approximation techniques based on reciprocal variables.
    Additional Material: 3 Ill.
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    Numerical study of incompressible fluids in unbounded domains (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2203-2218 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The aim is to build up and test a numerical method to calculate the velocity of stationary two-dimensional flows. Both inviscid and viscous fluids are considered. They act in the unbounded domain surrounding a given profile and a stream function is introduced. A variational procedure, adapted to unbounded domains, reduces the problem to solving a finite sequence of hormonic equations, posed in bounded domains. Some profiles are tested using a finite element method.
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    A study of stabilization and projection in the 4-node Mindlin plate element (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2223-2238 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In this paper, a Mindlin plate element is formulated based on the Hellinger-Reissner principle and the γ-technique. The stiffness consists of a constant stress (one-point quadrature) matrix and a stabilization matrix. The stabilization matrix is compared with those previously proposed. In addition, the element uses a projection to modify the nodal displacements so that the patch test is satisfied. The projection matrix is based on a mode decomposition. Several numerical cases are presented, and it is shown that the mode decomposition projection is necessary both for satisfaction of the patch test and convergence.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620281003
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    Modal parameter identification using Z-transforms (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2307-2321 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A method for the time domain identification of modal parameters of a vibrating structure using Z-transformation sequences is presented in this paper.This identification proceeds using the Z-transfer function of a vibrating structure from which an auto-regressive and moving-average (ARMA) model of the vibrating structure is derived. From this ARMA model and time domain data, the modal parameters can be identified. The time domain data can be obtained from single point or multiple shaker excitation modal testing. To demonstrate the application and efficiency of the method, a test on a simulated cantilever beam is presented.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/nme.1620281008
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    The dynamic analysis of a suspended cable due to a moving load (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2361-2381 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The dynamic behaviour of a saggy suspension cable under a moving load was investigated. First of all, the updated Lagrangian formulation and the finite element method were used to derive the property matrices of a saggy suspension cable in order to define the discretized equations of motion. Then, the Jacobi method was applied to the determination of the natural frequencies and the mode shapes of the suspended cable. The moving-load-induced dynamic responses of the saggy suspended cable were obtained by using the Newmark direct integration method incorporated with the Newton-Raphson iteration technique. The influence of some pertinent factors, such as speed of moving load, ratio of axial rigidity to total cable weight (AE/0m̄g0L) and ratio of moving load mass to total cable mass, is the key point of the dynamic analysis.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620281011
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    A simple stress error estimator for Hybrid-Trefftz p-version elementsA preliminary version1 of this paper has been presented at NUMETA 87 Conference, The University of Swansea, 6-10 July 1987 (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 211-236 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An a posteriori error estimator is presented which allows a good pointwise evaluation of the error in predicted stresses and can easily be implemented in existing FE codes. Although this estimator has especially been developed for and tested on p-version Hybrid-Trefftz (HT) elements, it is anticipated that it can also be applied to conventional conforming p-version elements. The practical efficiency of the estimator is illustrated through the solution of various plate bending problems by using the HT p-version Kirchhoff plate elements.2
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620280115
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    A moving boundary circulation model for regions with large tidal flats (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 245-260 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A numerical model is developed for computing two-dimensional circulation in coastal regions dominated by large tidal flat motion. This model is based on the shallow water momentum and continuity equations being operated upon by the Galerkin finite element method. The particular advantage of the model lies in its ability to accommodate a changing domain boundary. This is accomplished by adopting finite elements that change shape so as to consistently move with the water's edge. Application of the model to the Kuwait Bay is described, and the associated results on circulation are given.
    Additional Material: 17 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620280202
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    A boundary element method analysis of electrostatics in a tank during filling operations (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 315-329 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Electrostatic charging inside a tank is analysed numerically using the boundary integral method. The electrostatic charge is transmitted to the tank through a charged liquid. Profiles for the charge density and potential are obtained in the tank during the filling operation. The analysis is based on the equation governing the transport of charge and Poisson's equation. The results are characterized by two dimensionless parameters, the dimensionless Debye length given by the Debye length divided by the height of the tank, and the number Pe defined as a Peclet number. The results show where the maximum charge density and potential occur and give a prediction of when during the filling operation a hazardous situation may occur.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620280206
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    Assumed strain stabilization procedure for the 9-node Lagrange shell element (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 385-414 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An assumed strain (strain interpolation) method is used to construct a stabilization matrix for the 9-node shell element. The stabilization procedure can be justified based on the Hellinger-Reissner variational method. It involves a projection vector which is orthogonal to both linear and quadratic fields in the local co-ordinate system of each quadrature point. All terms in the development involve 2 × 2 quadrature in the 9-node element. Example problems show good accuracy and an almost optimal rate of convergence.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620280210
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    Delaunay triangulation of non-convex planar domains (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2695-2707 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper investigates the possibility of integrating the two currently most popular mesh generation techniques, namely the method of advancing front and the Delaunay triangulation algorithm. The merits of the resulting scheme are its simplicity, efficiency and versatility. With the introduction of ‘non-Delaunay’ line segments, the concept of using Delaunay triangulation as a means of mesh generation is clarified.An efficient algorithm is proposed for the construction of Delaunay triangulations over non-convex planar domains. Interior nodes are first generated within the planar domain. These interior nodes and the boundary nodes are then linked up together to produce a valid triangulation. In the mesh generation process, the Delaunay property of each triangle is ensured by selecting a node having the smallest associated circumcircle. In contrast to convex domains, intersection between the proposed triangle and the domain boundary has to be checked; this can be simply done by considering only the ‘non-Delaunay’ segments on the generation front.Through the study of numerous examples of various characteristics, it is found that high-quality triangular element meshes are obtained by the proposed algorithm, and the mesh generation time bears a linear relationship with the number of elements/nodes of the triangulation.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620281113
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    Conference diary (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2713-2714 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620281119
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    A mixed-variable continuously deforming finite element method for parabolic evolution problems. Part III: Numerical implementation and computational results (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2715-2760 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In Part I of this paper,1 the conceptual framework of a rate variational least squares formulation of a continuously deforming mixed-variable finite element method was presented for solving a single evolution equation. In Part II2 a system of ordinary differential equations with respect to time was derived for solving a system of three coupled evolution equations by the deforming grid mixed-variable least squares rate variational finite element method. The system of evolution equations describes the coupled heat flow, fluid flow and trace species transport in porous media under conditions when the flow velocities and constituent phase transitions induce sharp fronts in the solution domain. In this paper, we present the method we have adopted to integrate with respect to time the resulting spatially discretized system of non-linear ordinary differential equations. Next, we present computational results obtained using the code in which this deforming mixed finite element method was implemented. Because several features of the formulation are novel and have not been previously attempted, the problems were selected to exercise these features with the objective of demonstrating that the formulation is correct and that the numerical procedures adopted converge to the correct solutions.
    Additional Material: 20 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620281203
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    Error estimates and adaptive refinement for plate bending problems (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2839-2853 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The Zienkiewicz-Zhu error estimator is shown to be effective in problems of plate flexure. When used in conjunction with triangular elements and an adaptive mesh generator allowing a prescribed size of elements to be developed, very fast adaptive convergence for results of specified accuracy is achieved.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620281209
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    Selective refinement/derefinement algorithms for sequences of nested triangulations (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2889-2906 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The construction of changing sequences of irregular and nested triangulations, based on the use of conforming refinement/derefinement algorithms for triangulations, is presented and discussed. This strategy is particularly appropriate to combine adaptivity and full multigrid algorithms for dealing with moving fronts or fluid dynamics problems. It is shown that the quality of all the triangulations iteratively generated depends only on the geometric characteristics of the initial grid. A data structure suitable to create, manage and modify series of nested triangulations as well as the main features of the DEREF prototype package are described, and numerical examples are given.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620281212
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    Tracing the equilibrium path beyond simple critical points (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2923-2941 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A unified presentation of some popular continuation procedures used in the non-linear finite element analysis of structural mechanics is introduced. An extension of the elliptical constraint equation proposed by Crisfield is given. It is shown that in the proposed procedure real roots can always be obtained in solving the iterative change of the load parameter. Updated weighting factors are introduced in the constraint equation in order to get better convergence characteristics in the case when localized deformations occur. For bifurcation points a modification of Rheinboldt's branching procedure is presented. Post critical response after limit and bifurcation points is determined in some numerical examples.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620281214
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    Error estimates and convergence rates for various incompressible elements (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2191-2202 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This note reports numerical experiments on the efficiency of simple error estimates derived earlier1 applied to incompressible mixed or related penalty type formulations. The rate of convergence and performance of various mixed elements is compared. Numerical results from a driven cavity and an incompressible elastic problem demonstrate that the T6B1/3D and T6/3C elements give a faster rate of convergence than the T6/1D element. However, in the case of a plane extrusion analysis (stronger singularity), the rate of convergence for the T6B1/3D element drops and is inferior to that of the T6/1D, while the T6/3C element still proves superior to the other two elements.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620280914
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    A C0 finite element formulation for thin-walled beams (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2239-2255 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Timoshenko's and Vlasov's beam theories are combined to produce a C0 finite element formulation for arbitrary cross section thin-walled beams. Section properties are generated using a curvilinear co-ordinate system to describe the cross section dimensions. The element includes both shear and warping deformations caused by the bending moments and the bimoment. A Gauss quadrature order is employed which exactly integrates the bending and warping stiffness matrices and provides a reduced integration order for the shear stiffness matrices. Numerical results are presented for a channel section cantilever beam. The influence of shear deformation is investigated and the calculated results are shown to be in excellent agreement with the classical solutions.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620281004
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    Virtual crack extension methods for non-linear materials (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 929-942 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The virtual crack extension technique is a very efficient and accurate approach to fracture mechanics calculations in the numerical analysis of bodies containing cracks using the finite element method. A few variations of the technique have been described in the literature, and have been extensively used in linear elastic fracture mechanics, where good validation has frequently been available with accepted alternative solutions for standard tests. However, for non-linear materials extra complications arise in the technique, particularly in describing material response in a compatible manner. It is shown that, using few assumptions, a very competitive virtual crack extension technique based, on a direct minimization of potential energy is available for elastic non-linear elastic materials. Such materials can be closely approximated to elastic-plastic behaviour for monotonically increasing loads including mechanical, thermal and body force forms. The technique is described and demonstrated via examples to be in good agreement with alternative fracture parameter evaluations when evaluated in the same computer system, BERSAFE.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620280414
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    Numerical methods in transient and coupled problems, R. W. Lewis, E. Hinton, P. Bettess and B. A. Schrefler, Wiley (Chichester) 1987. No. of pages: 350. ISBN: 0 471 91200X (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 979-979 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620280419
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    Wave plan computation method in study of the Calvi Bay erosion in Corsica, France (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 27 (1989), S. 71-85 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A study of linear monochromatic wave propagation is presented, based on a theory of potentials. The usual Berkhoff equation has been extended by the addition of partially pervious solid boundary effects and the bed friction.The problem has been solved by a hybrid finite element method including the effect of singular local elements such as the end of breakwaters or wharfs. This numerical method confirms the interest in quadratic Lagrangian finite elements.The comparisons with analytical solutions and existing numerical results show the validity of the method. Some original examples also prove the good performance of the proposed computation method.As an example, the study of the erosion of the beach of Calvi Bay in Corsica, France is presented. The phenomenon had started already in 1960, but the problem began to be very severe four years ago, after the implementation of a new harbour in 1982 and buildings, hotels, restaurants, and a main sewer on the beach. To consider the impact of these constructions and other factors like waves, currents and geomorphological aspects, the studies were divided into four parts: sedimentological, currents, wave propagation and geomorphological.This paper will describe the results of a complete two years study on the site, from February 1986 to December 1987.Findings show that the erosion process is due to the rise of the relative sea level with, as a catalyst, tourist behaviour and the implementation of the new constructions.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620270107
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    Calculation of the force coefficients of a tubular jacket structural member with an appurtenance by the discrete vortex method (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 27 (1989), S. 153-167 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Jacket structures have many sub-sea appurtenances attached to them. For example, a typical jacket structure has hundreds of sacrificial anodes attached to its members. The fluid loading of these structures is calculated using Morison's formula. The force coefficients used in the equation are based on experiments carried out, for the most part, on single cylinders in laboratories in ideal flow. There are very few experimental data available for the fluid loading of cylinders with appurtenances. Moreover, it is not possible to calculate theoretically the loading on such configurations in flows of practical interest using approaches such as the finite element method. However, appurtenances can contribute significantly to the overall loading on a structure. This paper presents the preliminary theoretical work that has been carried out as part of a programme to establish a rational method for estimating the fluid loading on tubular members with appurtenances.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620270113
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    Masthead (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 27 (1989) 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620270201
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    Conference diary (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2943-2946 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620281215
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    Large deflection elastic-plastic analysis of plate structures by the finite strip method (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 331-358 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The finite strip method is applied to the non-linear analysis of plate structures. Large deflection effects are included via first order non-linearities in the strain-displacement relations, and material non-linearities are included via the von Mises yield criterion and associated flow rule. The virtual work equations are integrated numerically using Gauss quadrature, and the resulting non-linear equations are solved by Newton-Raphson iteration. Numerical results are presented for many applications including uniformly loaded rectangular and I beams, and square plates with either simply supported or clamped ends (or edges). The results are compared with known results from analytical and/or finite element analyses. Finally, a uniformly loaded stiffened panel is analysed and the results are compared with finite element results. In all cases, the results indicate that a single bending mode in the strip direction is sufficient to yield engineering accuracy for design purposes.
    Additional Material: 23 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620280207
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    Correction (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. ii 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620281002
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    Three-dimensional crack analysis using singular boundary elements (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2257-2273 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A multi-domain method of solving three-dimensional elastic crack problems in an infinite elastic body using the boundary element method is proposed. The \documentclass{article}\pagestyle{empty}\begin{document}$ \sqrt r $\end{document} displacement and \documentclass{article}\pagestyle{empty}\begin{document}$ 1/\sqrt r $\end{document} traction behaviours near a crack front are incorporated in special crack elements. The elimination of singularities arising from the \documentclass{article}\pagestyle{empty}\begin{document}$ 1/\sqrt r $\end{document} term combined with Kelvin's kernel for displacement in the integrals is discussed in detail. Stress intensity factors of modes I, II and III are obtained directly from crack-front nodal values, without any extrapolation as in some other methods. No differentiation of conventional boundary integral equations (with Kelvin's tensor kernels) is necessary in the current approach. This method is applicable to cracks of arbitrary shape. Infinite bodies are modelled precisely as such, not approximated as large finite bodies. Numerical solutions of stress intensity factors are given for several problems involving a penny-shaped crack.
    Additional Material: 17 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620281005
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    On updating the structure of sparse matrix factors (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2339-2360 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Structural analysis often involves the solution of a sparse system of linear equations using matrix factorization. For structural reanalysis problems, the system of equations is progressively changing and matrix factorization is required at each iteration step. In this paper, we study the problem of updating the structure of sparse matrix factors using an ordered-tree model. The ordered-tree model provides the information needed to symbolically compute the non-zero structure of the matrix factor of a sparse matrix. Furthermore, for matrix factor modification problems, this tree model can be used to determine the numerically modified entries in the matrix factor. Examples for modification of a structure and h-adaptive refinement of a finite element model are given to illustrate the potential application of the procedures developed in this study.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/nme.1620281010
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    A time domain boundary element method for poroelasticity (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2423-2449 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The development of a general boundary element method (BEM) for two- and three-dimensional quasistatic poroelasticity is discussed in detail. The new formulation, for the complete Biot consolidation theory, operates directly in the time domain and requires only boundary discretization. As a result, the dimensionality of the problem is reduced by one and the method becomes quite attractive for geotechnical analyses, particularly those which involve extensive or infinite domains.The presentation includes the definition of the two key ingredients for the BEM, namely, the fundamental solutions and a reciprocal theorem. Then, once the boundary integral equations are derived, the focus shifts to an overview of the general purpose numerical implementation. This implementation includes higher-order conforming elements, self-adaptive integration and multi-region capability. Finally, several detailed examples are presented to illustrate the accuracy and suitability of this boundary element approach for consolidation analysis.
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    URL: http://dx.doi.org/10.1002/nme.1620281014
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    On the problem of modelling for parameter identification in distributed structures (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2451-2463 
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    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Structures are often characterized by parameters, such as mass and stiffness, that are spatially distributed. Parameter identification of distributed structures is subject to many of the difficulties involved in the modelling problem, and the choice of the model can greatly affect the results of the parameter identification process. Analogously to control spillover in the control of distributed-parameter systems, identification spillover is shown to exist as well and its effect is to degrade the parameter estimates. Moreover, as in modelling by the Rayleigh-Ritz method, it is shown that, for a Rayleigh-Ritz type identification algorithm, an inclusion principle exists in the identification of distributed-parameter systems as well, so that the identified natural frequencies approach the actual natural frequencies monotonically from above.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620281015
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  • 96
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    Treatment of corners in BIE analysis of potential problems (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2569-2581 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: At corners or edges in the boundary of the domain of a potential problem the local normal gradient of potential is double-valued. When Dirichlet boundary conditions are specified there are thus two unknowns at a single nodal point, and the sets of equations resulting from the usual BIE discretization are rendered indeterminate. We discuss here earlier approaches to the resolving of this problem, and describe a further approach which appears to offer some advantages. Both normal gradients can be approximated directly from local potential boundary conditions, showing the problem indeed to be formally overdetermined. This ability is discarded, in favour of yielding a robust and well-conditioned relationship between the two gradients. This, in conjunction with the BIE analysis, permits solutions of considerable accuracy to be found, including the gradients at such corner nodes. Illustrative calculations are presented for rectilinear and curvilinear domains. These show that, even with as few elements as there are corners, and thus one and a half times as many unknowns as there are nodal points, good approximations to the gradients can be obtained. The need for progressively finer discretization as a corner is approached is thus much reduced.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620281107
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  • 97
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    Electronic Resource
    Process modelling of metal forming and thermomechanical treatment, C. R. Boer, N. Rebelo, H. Rydstad and G. Schroder, Springer-Verlag, Berlin, 1986. No. of. pages: 410. ISBN 3-540-16401-4 (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2710-2711 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620281116
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  • 98
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    Electronic Resource
    Computational structural mechanics and fluid dynamics CASV 30/1-2H, edited by A. K. Noor, ISBN 008 0371973, Pergamon Press, Oxford OX3 OBW, U.K., 1988. Price: £70.00 $125.00 (hardback). No. of pages: 465 (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2711-2711 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620281117
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  • 99
    Electronic Resource
    Electronic Resource
    An efficient through-thickness integration scheme in an unlimited layer doubly curved isoparametric composite shell element (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2777-2793 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper presents an efficient numerical integration scheme for evaluating the matrices (stiffness, mass, stress-stiffness and thermal load) for a doubly curved, multilayered, composite, quadrilateral shell finite element. The element formulation is based on three-dimensional continuum mechanics theory and it is applicable to the analysis of thin and moderately thick composite shells.The conventional formulation requires a 2 × 2 × 2 or 2 × 2 × 1 Gauss integration per layer for the calculation of element matrices. This method becomes uneconomical when a large number of layers is used owing to an excessive amount of computations. The present formulation is based on explicit separation of the thickness variable from the shell surface parallel variables. With the through-thickness variables separated, they are combined with the thickness dependent material properties and integrated separately. The element matrices are computed using the integrated material matrices and only a 2 × 2 spatial Gauss integration scheme. The response results using the present formulation are identical to those obtained using the conventional formulation. For a small number of layers, the present method requires slightly more CPU time. However, for a larger number of layers, numerical data are presented to demonstrate that the present formulation is an order-of-magnitude economical compared to the conventional scheme.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620281205
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  • 100
    Electronic Resource
    Electronic Resource
    On the rotation of conductors of finite torsional stiffness by eccentric snow loading and control of rotation using counterweights (1989)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 28 (1989), S. 2829-2838 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper is concerned with the prevention of snow loading on an overhead conductor caused by the mechanism of cylindrical-sleeve growth. The eccentric snow loading on the windward side of the conductor, having finite torsional stiffness, causes the conductor to rotate and a theoretical study of how this rotation can be controlled on attaching counterweights along the span of the conductor is presented. In the absence of counterweights, the non-linear rotation equation is solved analytically in terms of elliptic functions, simulating ice loading by a uniform torque density; for large torque density an asymptotic solution is obtained using matched asymptotic expansions. In the rotation equation the counterweights producing torque at discrete points are incorporated as delta functions which enable the discontinuity in the twisting couple at such locations to be accounted for by means of an integral moment balance. A simple algorithm is then presented for integrating the equation of rotation as an initial value problem which can deal with any distribution of counterweights along the span of the conductor. Illustrative numerical results are presented for zero, one, two, three and four counterweights per span; in the absence of counterweights analytical and numerical solutions are in exact agreement.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620281208
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