ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Bifurcations and traveling waves in a delayed partial differential equation (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Chaos 2 (1992), S. 231-244 
    Details
    ISSN: 1089-7682
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Here cell population dynamics in which there is simultaneous proliferation and maturation is considered. The resulting mathematical model is a nonlinear first-order partial differential equation for the cell density u(t,x) in which there is retardation in both temporal (t) and maturation variables (x), and contains three parameters. The solution behavior depends on the initial function cursive-phi(x) and a three component parameter vector P=(δ,λ,r). For strictly positive initial functions, cursive-phi(0)(approximately-greater-than)0, there are three homogeneous solutions of biological (i.e., non-negative) importance: a trivial solution ut≡0, a positive stationary solution ust, and a time periodic solution up(t). For cursive-phi(0)=0 there are a number of different solution types depending on P: the trivial solution ut, a spatially inhomogeneous stationary solution unh(x), a spatially homogeneous singular solution us, a traveling wave solution utw(t,x), slow traveling waves ustw(t,x), and slow traveling chaotic waves uscw(t,x). The regions of parameter space in which these solutions exist and are locally stable are delineated and studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.165909
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Propagating fronts, chaos and multistability in a cell replication model (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Chaos 6 (1996), S. 477-492 
    Details
    ISSN: 1089-7682
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Numerical solutions to a model equation that describes cell population dynamics are presented and analyzed. A distinctive feature of the model equation (a hyperbolic partial differential equation) is the presence of delayed arguments in the time (t) and maturation (x) variables due to the nonzero length of the cell cycle. This transport like equation balances a linear convection with a nonlinear, nonlocal, and delayed reaction term. The linear convection term acts to impress the value of u(t,x=0) on the entire population while the death term acts to drive the population to extinction. The rich phenomenology of solution behaviour presented here arises from the nonlinear, nonlocal birth term. The existence of this kinetic nonlinearity accounts for the existence and propagation of soliton-like or front solutions, while the increasing effect of nonlocality and temporal delays acts to produce a fine periodic structure on the trailing part of the front. This nonlinear, nonlocal, and delayed kinetic term is also shown to be responsible for the existence of a Hopf bifurcation and subsequent period doublings to apparent "chaos'' along the characteristics of this hyperbolic partial differential equation. In the time maturation plane, the combined effects of nonlinearity, nonlocality, and delays leads to solution behaviour exhibiting spatial chaos for certain parameter values. Although analytic results are not available for the system we have studied, consistency and validation of the numerical results was achieved by using different numerical methods. A general conclusion of this work, of interest for the understanding of any biological system modeled by a hyperbolic delayed partial differential equation, is that increasing the spatio-temporal delays will often lead to spatial complexity and irregular wave propagation. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.166195
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Helix uncoiling modes of sheared cholesteric liquid crystals (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 4343-4346 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: This work presents an analysis that identifies the two prominent mechanisms that govern the helix uncoiling of sheared cholesteric liquid crystals. In the presence of free surface orientation helix uncoiling proceed by pitch expansion of traveling orientational waves, and in the presence of fixed surface orientation helix uncoiling proceeds via compression of elastic boundary layers. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.471184
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Young–Laplace equation for liquid crystal interfaces (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 10820-10822 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: This letter uses the classical theories of liquid crystal physics to derive the Young–Laplace equation of capillary hydrostatics for interfaces between viscous isotropic (I) fluids and nematic liquid crystals (NLC's), and establishes the existence of four energy contributions to pressure jumps across these unusual anisotropic interfaces. It is shown that in addition to the usual curvature contribution, bulk and surface gradient elasticity, elastic stress, and anchoring energy contribute to pressure differentials across the interface. The magnitude of the effect is proportional to the elastic moduli of the NLC, and to the bulk and surface orientation gradients that may be present in the nematic phase. In contrast to the planar interface between isotropic fluids, flat liquid crystal interfaces support pressure jumps if elastic stresses, bulk and surface gradient energy, and/or anchoring energies are finite. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1324993
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    DYNAMICAL PHENOMENA IN LIQUID-CRYSTALLINE MATERIALS (2002)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 34 (2002), S. 233-266 
    Details
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Recent progress in modeling and simulation of the flow of nematic liquid crystals is presented. The Leslie-Ericksen (LE) theory has been successful in elucidating the flow of low molar-mass nematics. The theoretical framework for the flow of polymeric nematic liquid crystals is still evolving; extensions of the Doi theory capture qualitative features of the flow of polymeric nematics in simple geometries, but these theories have not been shown to predict texture development in flow. Mesoscopic theories for textured materials based on spatial averaging capture only some qualitative features of nonrectilinear liquid-crystalline polymer flow. Interfacial effects in liquid-crystalline systems have begun to receive attention in the context of interfacial viscoelasticity and the dynamics of dispersed liquid-crystalline polymers in immiscible blends.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.fluid.34.082401.191847
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Periodic textures of nematic polymers and orientational slip (1991)
    s.l. : American Chemical Society
    Macromolecules 24 (1991), S. 4450-4456 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00015a032
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Marangoni flow in liquid crystal interfaces (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 9769-9770 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: This letter presents the equation of capillary hydrodynamics for interfaces between viscous isotropic fluids and nematic liquid crystals (NLCs) to establish the existence of a new class of Marangoni flow. The interfacial stress balance equation involves the surface divergence of the surface stress tensor. It is shown that the anisotropic elastic contribution to the surface stress tensor gives rise to bending stresses and tangential forces. When the tensor order parameter that describes the NLC structure has surface gradients, a tensor order parameter-driven Marangoni flow is predicted. The strength of the predicted effect is proportional to the nematic–isotropic interaction energy characteristic of the interface, and the direction of flow is from low energy regions towards high energy regions. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.478943
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Nematic contact lines and the Neumann and Young equations for liquid crystals (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 7675-7684 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The Neumann and Young equations for three-phase contact lines, when one of the phases is a nematic liquid crystal, have been derived using momentum balances and liquid-crystal surface physics models. The Neumann equation for nematic contact lines is a balance of three tension and two bending forces, the latter arising from the characteristic anisotropic surface anchoring of nematic liquid crystal surfaces. For a given interface the bending forces are always orthogonal to the tension forces, and in the presence of a nematic phase the Neumann triangle of isotropic phases becomes the Neumann pentagon. The Young equation for solid–fluid–nematic contact lines differs from the classical equation by a bending force term, which influences the wetting regimes' transitions, the contact angles, and allows for a novel orientation-induced wetting transition cascade. For a nematic contact line, the partial wetting–spreading transition occurs for positive values of the spreading parameter, and the partial wetting–dewetting transition sets in at values smaller than the classical result. The interval of static contact angles is less than π radians. For a given solid–nematic–isotropic fluid at a fixed temperature, the spreading → partial wetting → spreading → partial wetting → spreading transition cascade may occur when the director at the contact line rotates from the planar to the homeotropic orientation state. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.480106
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Theory of linear viscoelasticity of chiral liquid crystals (1996)
    Springer
    Rheologica acta 35 (1996), S. 400-409 
    Details
    ISSN: 1435-1528
    Keywords: Macroscopic theory ; cholesteric liquid crystals ; linear viscoelasticity ; oscillatory shear ; storage and loss moduli ; dynamic viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The governing equations of monodomain isothermal cholesteric liquid crystals subjected to small amplitude oscillatory rectilinear shear have been derived for three representative helix orientations. The imposition of oscillatory flow excites splay-bend-twist deformations when the helix is aligned along the flow direction, splay-bend deformations when the helix is along the vorticity gradient, and twist deformations when aligned along the velocity axis. The different nature of the excited elastic modes as well as the anisotropic viscosities are reflected in the anisotropy of the linear viscoelastic material functions for small amplitude rectilinear oscillatory shear. When the helix is aligned along the flow direction, cholesteric viscoelasticity is strongest, and exists in a relatively narrow band of intermediate frequencies. When the helix is aligned along the vorticity direction cholesteric viscoelasticity is significant in a relatively broad range of intermediate frequencies. Finally, when the helix is aligned along the velocity gradient direction, cholesteric viscoelasticity is relatively insignificant and only exists in a narrow band of frequencies. The cholesteric pitch controls the location of viscoelastic region on the frequency spectrum, but only when the helix is not oriented along the vorticity axis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00368991
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Simulation of Surface-Enhanced Ordering in Smectic Films (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 139 (Apr. 2008), p. 135-140 
    Details
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: A Landau-de Gennes type model for the direct isotropic/smectic A phase transition isused to study surface-enhanced smectic ordering in the stable smectic temperature regime. Aunified surface-free energy functional is proposed which can be utilized for homeotropic and planarsurface anchoring. The time-dependent complex Landau-Ginzburg evolution equations andboundary conditions are derived for thin-film geometry. Simulation results are presented for thetwo types of anchoring and compared to observations from experiments and previous simulations.Simple visualization software for smectic layering was developed and is also presented that iscompatible with discretized numerical solutions of the model
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/24/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.139.135.pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...