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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 93 (1989), S. 5727-5735 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 6100-6111 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The effects of catalyst surface morphology and surface active-sites distribution on diffusion limited reactions are studied. The catalysts structures are deterministic and random Cantor sets (CS) and Devil's staircases (DS). The reaction is an Eley–Rideal process in which a random walker approaches the surface from the bulk and reacts with an active site upon collision with it. Two types of scaling analysis are performed: Fractal time scaling of product formation that provides a global analytical tool of the process; and multifractal analysis with which the complex distribution of reaction probabilities of the active sites are analyzed. Some of the main findings are (a) the fractal time scaling theory that has been applied successfully for connected fractal objects, also describes well the performance of disconnected, dust-type fractal objects such as found in most real catalysts and as modeled by the DS and CS; (b) the effective diffusion coefficient for reactions with disconnected active sets is smaller than for connected sets; we provide a method for calculating it; (c) despite the structural similarity of the DS and CS, they react with different efficiencies. It is shown that this difference can be explained in terms of kv, the prefactor of the neighboring-volume/yardstick-sized relation; (d) by performing the analyses on objects with various sizes, we provide evidence that corroborates the specific scaling assumptions of the multifractal formalism for the studied structures; and (e) significant differences between the τ(q) and f (α) multifractal spectra of the four objects are found and analyzed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 2823-2836 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: When a chemical reaction is carried out on a catalytic ribbon, the spatial average temperature of which is kept constant by electrical heating, spatiotemporal temperature patterns form when the uniform steady state is unstable at the set temperature. Numerical simulations reveal periodic and aperiodic patterns of moving pulses, "breathing'' pulses, or stationary and oscillatory fronts. The transitions between some of these patterns are intricate and proceed via global bifurcations. Bifurcation maps of parameter regions leading to specific patterns are used to gain insight into pattern formation and organization of these parameter regions. The relations among the dynamics of the uncontrolled system, the ribbon length, and the selected pattern are discussed. Similar patterns are expected to evolve in other reaction–diffusion systems subject to control of space-averaged properties.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Chaos 9 (1999), S. 78-87 
    ISSN: 1089-7682
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A general method to control a desired patterned state in reaction–diffusion processes is presented. Weighted global control is aimed to keep weighted spatially averaged properties of state variable at preset values. It is shown that weighted global control creates a stable direction in the global space of system states and affects system dynamics globally. We apply it for a specific two-component reaction–diffusion system and show that the desired pattern is attainable for a wide range of the control parameters. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial & engineering chemistry research 28 (1989), S. 948-954 
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial & engineering chemistry research 28 (1989), S. 955-960 
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial and engineering chemistry 22 (1983), S. 209-215 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial and engineering chemistry 25 (1986), S. 228-233 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 4688-4696 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Global interaction refers to a nonlocal mode of information exchange (coupling) between the local states on a surface. Global interaction may produce a very rich class of spatiotemporal patterns. A system has an inversion symmetry if both φ(x,y,λ) and φ(−x,−y,−λ) are solutions. Here x and y are the two dynamic variables of the system and λ is a global control variable. The presence of inversion symmetry sharpens the distinction among the various motions and leads to bifurcation scenarios which have not been found in its absence. A heteroclinic connection between two inversion symmetric saddle foci leads to many shifts between back-and-forth and unidirectional pulse branches of solutions. The scenario by which the periodic orbits gain and lose stability via period-increasing or saddle-node bifurcations is similar to one predicted by Glendining for a system described by three ordinary differential equations having inversion symmetry. The dynamic features are robust and rather insensitive to the functional form of the kinetic expression.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 3568-3581 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The global interaction between the spatial average of the autocatalytic variable in a reactive (catalytic, electrochemical, gel) medium and a surrounding mixed fluid in a continuously fed vessel may induce a rich structure of spatiotemporal patterns that would not exist otherwise. Patterns may form when the local kinetics are either excitable, oscillatory, or bistable and the reaction rate ascends with reactant concentration. Thus, a local change in the surface reaction rate may affect the reactant concentration in the surrounding well-mixed vessel, so that it arrests moving fronts on the surface. External control of the average temperature (or rate) of a catalytic ribbon by electrical heating is another form of interaction between a spatial average of a local oscillator and a space-independent variable that induces pattern formation. We study various patterns and bifurcations that can develop in a ring or a ribbon due to global interaction using a simple cubic kinetic expression. The predominant pattern on a catalytic ring is a rotating pulse. Other patterns, such as antiphase oscillations and crossing pulses, similar to those found previously on a controlled catalytic ribbon, may coexist for a sufficiently strong interaction. Several of the transitions between regions with qualitatively different patterns are via global bifurcation.
    Type of Medium: Electronic Resource
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