Recent experiments [1] on two–frequency parametrically excited surface waves exhibit an intriguing “superlattice” wave pattern near a codimension–two bifurcation point where both subharmonic and harmonic waves onset simultaneously, but with different spatial wavenumbers. The superlattice pattern is synchronous with the forcing, spatially periodic on a large hexagonal lattice, and exhibits small...

In the Taylor-Couette experiment on fluid flow between counterrotating cylinders, there is a bicritical point where the onset of instabilities to Taylor vortex flow (a steady-state bifurcation) and spiral vortex flow (a Hopf bifurcation) meet. The nonlinear mode interactions near this bicritical point are analyzed, exploiting the role of symmetry in the bifurcation theory. and with emphasis on ...

Measurements over the Rayleigh-number range 10 <∼R<∼ 10 and Prandtl-number range 4.4<∼ σ <∼ 29 that determine the torsional nature and amplitude of the oscillatory mode of the large-scale circulation (LSC) of turbulent Rayleigh–Bénard convection are presented. For cylindrical samples of aspect ratio Γ =1 the mode consists of an azimuthal twist of the near-vertical LSC circulation plane, with th...

The flow in a cylinder driven by the rotation of one endwall for height to radius ratios around three is examined. Previous experimental observations suggest that the first mode of instability is a precession of the central vortex core, whereas a recent linear stability analysis to general three-dimensional perturbations suggests a Hopf bifurcation to a rotating wave at lower rotation rates tha...

OBJECTIVES This study compared the long-term follow-up results of conservative versus aggressive strategies for provisional side branch (SB) intervention in coronary bifurcation lesions. BACKGROUND The appropriate criteria for provisional SB ballooning or stenting have not been established. METHODS A total of 258 patients with a large bifurcation lesion were randomized to a conservative or ...

Subject to compression, elastic materials may undergo bifurcation of various kinds. A homogeneous material forms creases, whereas a bilayer consisting of a stiff film and a compliant substrate forms wrinkles. Here, we show several new types of bifurcation behavior for bilayers consisting of films and substrates of comparable elastic moduli. Depending on the ratios of moduli and thicknesses of t...

In Taylor–Couette systems, waves, e.g. spirals and wavy vortex flow, typically rotate in the same direction as the azimuthal mean flow of the basic flow which is mainly determined by the rotation of the inner cylinder. In a combined experimental and numerical study we analysed a rotating wave of a one-vortex state in small-aspectratio Taylor–Couette flow which propagates either progradely or re...

Extinction limits and flame bifurcation of lean premixed dimethyl ether-air flames are investigated numerically using the counterflow flame with a reduced chemistry. Emphasis is paid to the combined effect of radiation and flame stretch on the extinction and flammability limits. A method based on the reaction front is presented to predict the Markstein length. The predicted positive Markstein l...

Sex ratio is an essential component of life history to be considered in population growth. Chrysomya albiceps is a blowfly species with a naturally biased sex ratio. In this study, we evaluated the impact of changes in sex ratio on the dynamic behavior of C. albiceps using a density-dependent mathematical model that incorporated demographic parameters such as survival and fecundity. These param...

In this paper, vibrations and bifurcation of a damped system consists of a mass grounded by linear and nonlinear springs and a nonlinear damper is studied. Nonlinear equation of motion is derived using Newton’s equations. Approximate analytical solutions are obtained using multiple time scales (MTS) method. For free vibration, the approximate analytical results are compared with the numerical i...