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  • 1
    Electronic Resource
    Electronic Resource
    Interaction of Surfactants with Poly(N-isopropylacrylamide) Microgel Latexes (1994)
    s.l. : American Chemical Society
    Langmuir 10 (1994), S. 418-422 
    Details
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/la00014a015
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Two-dimensional inverse born approximation in ultrasonic flaw characterization (1985)
    Springer
    Journal of nondestructive evaluation 5 (1985), S. 95-106 
    Details
    ISSN: 1573-4862
    Keywords: Ultrasound imaging ; flaw characterization ; computerized tomography ; inverse Born approximation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A method is developed to characterize flaws of arbitrary shape by using ultrasound pulse echoes at multiple coplanar incident directions. The three-dimensional image reconstruction problem is reduced to a series of two-dimensional image reconstructions, thereby avoiding the difficulties associated with three-dimensional image reconstructions, such as taking and processing a large amount of data, and the complications associated with three-dimensional image reconstructions, such as three-dimensional interpolation, long computing time, etc. The reconstructed two-dimensional images represent the two-dimensional projections or shadows of the three-dimensional flaw characteristic function. Each projection image is reconstructed independently using well-developed computerized tomography reconstruction techniques. If the shape of the flaw is not too irregular, or if the fine details of the shape are not of interest, only a few of these projection images suffice to characterize the flaw. The magnitude scaling problem and the alignment problem of the echoes at different incident directions can be handled easily in the algorithm. Simulation studies yielded encouraging results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566959
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Computation of Radon Data from Cone Beam Data in Cone Beam Imaging (1998)
    Springer
    Journal of nondestructive evaluation 17 (1998), S. 1-15 
    Details
    ISSN: 1573-4862
    Keywords: Cone beam X-rays ; Radon inversion ; image reconstruction ; computerized tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract In the latest development in x-ray inspection, cone beam x-rays are used to inspect three-dimensional objects. However, the cone beam projection data collected are not compatible with image reconstruction by three-dimensional Radon inversion. In this paper a method is developed to convert the cone beam data to Radon data which can then be inverted to yield the object. The Radon data are generated directly on the polar grid lines on a set of coaxial vertical planes in the Radon space for Radon inversion, and therefore only 1-dimensional interpolation in the Radon space is needed to obtain Radon data at the desired locations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022668128324
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Region-of-Interest Imaging in Cone Beam 3-D CT (1998)
    Springer
    Journal of nondestructive evaluation 17 (1998), S. 17-26 
    Details
    ISSN: 1573-4862
    Keywords: Region-of-interest imaging ; Radon data ; medical diagnosis ; cone beam CT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract Imaging a sectional region within an object with a detector just big enough to cover the sectional region-of-interest is analyzed. With otherwise complete (for small objects) cone beam scanning configurations, some of the Radon data are corrupted by unwanted measurements from outside the region-of-interest, and furthermore the region of corrupted data is in such a shape that the use of a priori information on the finite support of the object alone is not sufficient to recover the missing data. We show that with some suitable choice of scanning configuration and with an innovative method of data combination, all the Radon data can be obtained accurately. The algorithm is mathematically exact, and requires no iterations and no additional measurements. The method can be applied to inspect portions of large industrial objects in industrial imaging, as well as to image portions of human bodies in medical diagnosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022628412394
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    The construction and use of convex hulls in limited-angle computerized tomography (1987)
    Springer
    Journal of nondestructive evaluation 6 (1987), S. 189-204 
    Details
    ISSN: 1573-4862
    Keywords: Convex hull ; x-ray computerized tomography ; limited-angle image reconstructions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Abstract A method is developed to construct the convex hull of an object and make use of it in limited-angle x-ray computerized tomography (CT). The convex hull of an object is the smallest convex region containing the object, and therefore it can serve as boundary information in the reconstruction of the object from limited-angle data. Two methods, the intersection version and the superimposition version, of constructing the convex hull of an object from x-ray data are presented. It is shown that the intersection version is very efficient when the noise is very low, whereas the superimposition version is more stable with respect to noise. The usefulness and the construction of the convex hulls of embedded flaws in industrial x-ray CT are also studied. It is demonstrated with simulated data that the use of convex hulls makes it possible to reconstruct high-quality images from limited-angle data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566847
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Role of ionic species and valency on the steady shear behavior of partially hydrolyzed polyacrylamide solutions (1990)
    Springer
    Colloid & polymer science 268 (1990), S. 911-920 
    Details
    ISSN: 1435-1536
    Keywords: Polyacrylamide ; ionicvalency ; viscosity ; salteffect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Polyacrylamides are anionic polymers with a large number of charges along the polymer chains. The rheological properties of aqueous polyacrylamide solutions can be significantly modified by varying the solvent environment with the addition of salt. The presence of cations substantially reduces the inter- and intra-molecular interactions of the macroions. It was found that the valency of the cation has a strong effect on the rheological behavior of polyacrylamide solutions, but the size and type of salt have a negligible effect. The reduction in the solution viscosity with di-valent salts (e.g., CaCl2, MgCl2, BaCl2, and MgSO4) can be as high as an order of magnitude compared with mono-valent salt (KI, KC1, NaCl, and NaBr), depending on the salt concentration and shear rate. An identical viscosity function can be obtained for different types of polyacrylamide solutions by varying the salt content in solution. This interesting feature provides a useful means in the development and preparation of certain “ideal fluids” for simulation studies of complex flow problems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01469369
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Dissolution behaviour of model alkali-soluble emulsion polymers: effects of molecular weights and ionic strength (1999)
    Springer
    Colloid & polymer science 277 (1999), S. 1172-1178 
    Details
    ISSN: 1435-1536
    Keywords: Key words Dissolution ; Molecular weights ; Ionic strength ; Neutralisation ; Light scattering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The dissolution behaviour of model alkali-soluble polymer emulsions with different molecular weights was studied using conductometric and potentiometric titration and laser light scattering techniques. The behaviour of the copolymer was studied as a function of the degree of neutralisation, α = [NaOH]/[COOH]. The polymer latex swells with increasing α values up to α = 0.5–0.7, after which the dissociation of polymer chains commences. At α = 1.0, all the polymer latexes dissociate into individual polymer chains. By combining the results of static and dynamic laser light scattering, we observed that the polymers have a compact conformation at α = 0. This compact conformation changes to a random coil at around α = 0.5, which then becomes a fully extended coiled conformation at α = 1.0, when all the COOH polymer groups are hydrolysed. The dissolution of low-molecular-weight polymers is faster than that of high-molecular-weight polymers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050506
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Stability of a model alkali-soluble associative polymer in the presence of a weak and a strong base (1999)
    Springer
    Colloid & polymer science 277 (1999), S. 276-281 
    Details
    ISSN: 1435-1536
    Keywords: Key words Model associative polymers ; Alkali ; Neutralization ; Rheology ; Stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  Hydrophobically modified alkali-soluble emulsion (HASE) polymer is solubilized by the addition of a base. When the pH is increased to greater than 6.5, methacrylic acids on the polymer backbone are neutralized and the carboxylated latex polymer goes into solution causing a large increase in the viscosity due to inter-molecular associations of the hydrophobes. The stability of the viscosity of the polymer solution at pH in the range 9–10 was studied in the presence of a strong (NaOH) and a weak [1-amino-1-methylpropanol (AMP)] base. No change in the viscosity or the moduli was observed for the polymer in AMP. Reduction in the viscous and elastic properties of the polymer solution in NaOH was observed after 4 weeks. Such small changes are detectable using the superposition of oscillation on the steady shear technique. The decrease in the viscoelastic properties is attributed to the hydrolysis reaction of the urethane groups of the macromonomer, which resulted in a decrease in the number of hydrophobes per polymer chain. It is recommended that a weak base be used to neutralise the HASE polymer in order to avoid the possibility of compositional changes in the polymer after neutralisation for more than 6 weeks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00013756
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  • 9
    Electronic Resource
    Electronic Resource
    Role of ionic species and valency on the viscoelastic properties of partially hydrolyzed polyacrylamide solutions (1994)
    Springer
    Colloid & polymer science 272 (1994), S. 516-522 
    Details
    ISSN: 1435-1536
    Keywords: Polyacrylamide ; ionic ; valency ; viscoelasticity ; salt effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The effects of ionic species and valency on the viscoelastic properties of partially hydrolyzed polyacrylamide solutions were examined. Two viscoelastic parameters were considered, i.e., average relaxation time, λ M 0 and steady state compliance, Je0. Both these parameters are independent of ionic species of monovalent salts. However, λ M 0 decreases with increasing salt concentrations. Divalent salts reduce the values of λ M 0 by as much as 10 times. On the other hand, Je0 is independent of salt concentrations and valency. The effects of monovalent salt on three different polyacrylamide samples of varying degree of hydrolysis and MW were also examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00653215
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    Ideal elastic fluids of different viscosity and elasticity levels (1989)
    Springer
    Rheologica acta 28 (1989), S. 112-120 
    Details
    ISSN: 1435-1528
    Keywords: Idealelasticfluid ; Bogerfluid ; steady and dynamicshear properties ; relaxation time ; simplefluid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Four constant viscosity, highly elastic fluids of different viscosity and elasticity levels are presented. The viscosity ranges from 4 × 10−3 to 5.0 Pa s and the Maxwell relaxation time varies from 0.09 to 4.5 s. The steady and dynamic shear properties are determined. These fluids comply with the requirements of the simple fluid theory except for theG′ andN 1/2 data where a slight deviation is observed. The results suggest the possibility of preparing a wide range of constant viscosity elastic fluids with specific values of viscosity and relaxation time by manipulating polymer molecular parameters as well as polymer concentration, solvent viscosity and salt addition. The effects of each of these parameters on the rheological behaviour are examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01356972
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    Paper (German National Licenses)
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