The DSP-based bunch-by-bunch feedback system installed in the PEPII high-energy ring (HER) has been used to damp instabilities induced by unwanted higher-order modes (HOMs) at beam currents up to 605 mA during commissioning. Beam pseudospectra calculated from feedback system data indicate the presence of coupled-bunch modes that coincide with a previously observed cavity mode (0-M-2). Bunch cur...

Stochastic process exhibiting power-law slopes in the frequency domain are frequently well modeled by fractional Brownian motion (fBm), with the spectral slope at high frequencies being associated with the degree of small-scale roughness or fractal dimension. However, a broad class of real-world signals have a high-frequency slope, like fBm, but a plateau in the vicinity of zero frequency. This...

Stochastic process exhibiting power-law slopes in the frequency domain are frequently well modeled by fractional Brownian motion (fBm). In particular, the spectral slope at high frequencies is associated with the degree of small-scale roughness or fractal dimension. However, a broad class of real-world signals have a high-frequency slope, like fBm, but a plateau in the vicinity of zero frequenc...

Several tens of thousands of accelerator structures will be needed for the next generation of normal conducting linear colliders known as the GLC/NLC (Global Linear Collider/Next Linear Collider). To prevent the beam being driven into a disruptive BBU (Beam Break-Up) mode or at the very least, the emittance being significantly diluted, it is important to damp down the wakefield left by driving ...

In this paper, we consider a second-order scalar auxiliary variable Fourier spectral method to solve the nonlinear fractional generalized wave equation. Unconditional energy conservation or dissipation properties of fully discrete scheme are first established. Next, utilize temporal-spatial error splitting argument obtain unconditional optimal estimate scheme, which overcomes time-step restrict...

In this paper, the method of electric analog synthesis is applied to design a piezo-electro-mechanical arch able show capacity multimodal damping. An electric-analog circuit designed by using finite number lumped elements representing equivalent curved beam. Spatial and frequency coherence conditions are proven be verified for modes damped: in fact, lumped-element can damp only vibration modes....

Triangulation and histological studies were made of skin ablation depths following skin treatments with a Fotona Dynamis Er:YAG laser system. The following laser handpieces were used in the study: Full beam handpieces R04 and R11; Stamping patterned handpieces PS01, PS02 and PS03; fractionated handpiece FS01 and c) Scanning fractional handpiece F22. The laser fluence (F) was found to be the maj...

Free scalar fields in de Sitter space have a one-parameter family of states invariant under the de Sitter group, including the standard thermal vacuum. We show that, except for the thermal vacuum, these states are unphysical when gravitational interactions are included. We apply these observations to the quantum state of the inflaton, and find that at best, dramatic fine tuning is required for ...