The modeling of the turbulent wake of a self-propelled body in a stratified fluid is discussed. The scaling parameter is taken to be the internal Froude number, using the speed and diameter of the body and Vaisala frequency of the fluid. Arguments are presented to suggest that the ratio of the time for the wake to collapse to the characteristic time of the turbulence is invariant with model sca...

The mismatch between traditional cipher designs and efficient operation on modern Very Long Instruction Word, Single Instruction Multiple Data, superscalar, and deeply pipelined processors is explored. Guidelines are developed for efficiently exploiting the instructionlevel parallelism of these processor architectures. Two stream ciphers, WAKE-ROFB and WiderWake, incorporating these ideas are p...

We study experimentally the vortex streets produced by a flapping foil in a hydrodynamic tunnel, using two-dimensional particle image velocimetry. An analysis in terms of a flapping frequency-amplitude phase space allows the identification of (i) the transition from the well-known Bénard-von Kármán (BvK) wake to the reverse BvK vortex street that characterizes propulsive wakes, and (ii) the sym...

Atmospheric turbulence has significant influences on both the trajectories and strengths of wake vortices. In this paper, a quasi-wavelet method is used to generate a random atmospheric turbulence field based on the von Kármán spectrum, in which atmospheric turbulence is represented by groups of random eddies. An inviscid wake vortex system, out-of-ground effect or in-ground effect, is immersed...

All adult mammals examined thus far exhibit sleep bout durations that follow an exponential distribution and wake bout durations that follow a power-law distribution. In altricial rodents such as rats and mice, exponential distributions of sleep bouts are found soon after birth, but the power-law distribution of wake bouts does not emerge until the third postnatal week. Also, both sleep and bou...

This paper focuses on issues related to the trailing vortex wake hazard beyond the takeoff and landing corridors. The operational procedures adopted by the FAA in the 1970s for avoiding wake turbulence encounters in the take-off and landing corridors have been very successful in providing commercial aviation with a high degree of safety. However, there is a growing body of evidence that encount...

Simulations of a low-speed square cylinder wake and a supersonic axisymmetric base wake are performed using the Detached Eddy Simulation (DES) model. A reduced-dissipation form of the Symmetric TVD scheme is employed to mitigate the effects of dissipative error in regions of smooth flow. The reduceddissipation scheme is demonstrated on a 2D square cylinder wake problem, showing a marked improve...

This paper describes an experimental investigation into the development of a planar turbulent wake under constant adverse and favorable pressure gradient conditions. The focus of the study is on the near-wake due to its relevance to high-lift systems for commercial transport aircraft. The wake is generated by a flat splitter plate with tapered trailing edge. The pressure gradients are imposed a...

BACKGROUND Stroke symptoms noticed upon waking, wake-up stroke, account for up to a quarter of all acute ischemic strokes. Patients with wake-up stroke, however, are often excluded from thrombolytic therapy. METHODS Using our prospectively collected stroke registry, wake-up stroke and known-onset morning strokes were identified. Wakeup stroke was defined as a patient who was asleep >3 hours a...

The transverse force on a spherical charged grain lying in the plasma wake of another grain is analyzed to assess the importance of ion-drag perturbation, in addition to the wake-potential-gradient. The ion-drag perturbation is intrinsically one order smaller than the wake-potential force in the ratio of grain size (r(p)) to Debye length (λ(De)). So ion-drag perturbation is important only in no...