A new scheme for plasma electron injection into an acceleration phase of a plasma wake field is presented. In this scheme, a single, short electron pulse travels through an underdense plasma with a sharp, localized, downward density transition. Near this transition, a number of background plasma electrons are trapped in the plasma wake field, due to the rapid wavelength increase of the induced ...

Sleep-wake behavior is regulated by a circadian rhythm, homeostatically and by additional mechanisms that determine the timing of slow-wave sleep and rapid eye movement sleep (REMS) episodes. The posterior hypothalamus coordinates the neural and humoral signals with the rest-activity cycle. It contains wake-active neurons, and is a site where stimulation of inhibitory GABAA receptors promotes s...

Wake vortices are a safety hazard to landing aircraft. A landing aircraft that encounters a wake may roll, resulting in a fatal crash if the roll is severe enough and/or if the aircraft is low enough to the ground. Therefore, aircraft are separated by a sufficient distance to ensure that wakes have time to decay in strength. However, because of the inherent variability in wake behavior and airc...

The relationship between seasonal affective disorder (SAD) and subjective quality of sleep/wake cycle in adolescents was explored. The Seasonal Pattern Assessment Questionnaire for Children and Adolescents (SPAQ-CA) and Mini Sleep Questionnaire (MSQ) were administered to 345 adolescents living in the city of Cesena (Emilia-Romagna region, Italy) (299 females; age range: 14-18 years), to determi...

Wind tunnel experiments were performed to investigate the effects of downstream-facing winglets on the wake dynamics, power and thrust of a model wind turbine. Two similar turbines with and without winglets were operated under the same conditions. Results show an increase in the power and thrust coefficients of 8.2% and 15.0% for the wingletted case. A simple theoretical treatment of a two-turb...

We identify a dominant mechanism in the interaction between a slender flexible structure undergoing free vibrations in sheared cross-flow and the vortices forming in its wake: energy is transferred from the fluid to the body under a resonance condition, defined as wake-body frequency synchronization close to a natural frequency of the structure; this condition occurs within a well-defined regio...

[1] We describe Wind observations of two lunar wake encounters which occurred on 12–13November 1996 and 18 July 2002. The observations were made at downstream distances of around 25 and 15 lunar radii (RL), respectively. Both encounters occurred prior to the spacecraft entering the lunar shadow; one event took place within the magnetosheath. A characteristic feature of the lunar wake is the pre...

An anisotropic double Gaussian (DG) model for analytical wake modeling to predict the streamwise velocity behind an isolated non-yawed horizontal-axis wind turbine is proposed. The proposed based upon conservation of mass and momentum inside a streamtube control volume. growth rate parameters distinguish expansion between lateral vertical directions were tuned on numerical measurement data util...

The results of a series of numerical simulations for the NASA low-speed centrifugal compressor are presented. Large-eddy simulation (LES) is carried out together with the most commonly used Reynoldsaveraged Navier–Stokes (RANS) models, including the mixing length, k– and k– models. Predictions are compared with the available experimental data. It is seen that quantitative predictions of LES are...