Lifetime Estimate of Pipe Systems

Lifetime statistics in transitional pipe flow.

Several experimental and numerical studies have shown that turbulent motions in circular pipe flow near transitional Reynolds numbers may not persist forever, but may decay. We study the properties of these decaying states within direct numerical simulations for Reynolds numbers up to 2200 and in pipes with lengths equal to 5, 9, and 15 times the diameter. We show that the choice of the ensembl...

Lifetime estimate for plasma turbulence

A method is proposed to experimentally determine the intrinsic time scale or a decay rate of turbulent fluctuations. The method is based on the assumption that the Breit-Wigner spectrum model with a non-Gaussian frequency broadening is valid in the data analysis. The decay rate estimate is applied to the multi-spacecraft magnetic field data in interplanetary space, yielding that the result that...

An Evaluation of the Systems Reliability Using Fuzzy Lifetime Distribution

General Estimate for the Graviton Lifetime

By means of general kinematical arguments, the lifetime τ of a graviton of energy E for decay into gravitons is found to have the form τ = 1 EG ∑ j=1,2,... cj(ΛG) j . Some recent, preliminary results of non perturbative simplicial quantum gravity are then employed to estimate the effective values of G and ΛG. It turns out that a short lifetime of the graviton cannot be excluded. The recent adva...

Computing Flow Pipe of Nonlinear Hybrid Systems

Modern control-command systems often include controllers that perform nonlinear computations to control a physical system, which can typically be described by an hybrid automaton containing highdimensional systems of nonlinear differential equations. To prove safety of such systems, one must compute all the reachable sets from a given initial position, which might be uncertain (its value is not...