— We study the radiation damping effect on the relativistic acceleration of electron-positron plasmas with two-and-half–dimensional particle-incell(PIC) simulation. Particles are accelerated by Poynting flux via the diamagnetic relativistic pulse accelerator(DRPA), and decelerated by the self-consistently solved radiation damping force. With Ωce/ωpe ≥ 10, the Lorentz factor of the highest energ...

We study a class of elastic systems described by a (hyperbolic) partial differential equation. Our working example is the equation of a vibrating string subject to linear disturbance. The main goal is to establish conditions for stabilization and asymptotic stabilization by applying a fast oscillating control to the string. In the first situation studied we assume that system is subject to a da...

Electrorheological (ER) materials are suspensions of micron sized particles in insulating, dielectric fluids. The mechanical properties of these materials can be controlled by regulating an electric field through them. Variable properties include stiffness, damping, and yielding behavior. At high electric fields, material property changes are rapid and immediately reversible. ER technology has ...

Dwarf (or dark) molecular clouds and molecular clumps have a lifetime which is greater than their dynamical time and must therefore be, in an average sense, in mechanical equilibrium. Equilibrium perpendicular to a global magnetic field is by magnetic forces and it is proposed that along the field the gas is supported by an Alfvén wave pressure force. A selfconsistent analytical model, utilisin...

A force-feedback control system for VIV experiments is designed and evaluated for the purpose of achieving high accuracy free vibration tests. Through an organized approach, this work details specific methods for minimizing the combined effect of mass and damping using control system fundamentals. The dynamics of the closed-loop system are analyzed, a numerical model constructed and a control s...

We present a method to improve accuracy in measurements of nanoscale viscoelastic material properties with contact resonance atomic force microscope methods. Through the use of the two-dimensional hydrodynamic function, we obtain a more precise estimate of the fluid damping experienced by the cantilever-sample system in contact resonance experiments, leading to more accurate values for the tip-...

his article describes a nonlinear proportional and derivative T ( N P D ) controller and its use for both non-contact transient force control (NCTFC) (zero velocity when contact occurs) and contact transient force control (CTFC) (non-zero velocity when contact occurs). The key advantages of NPD control are its high disturbance rejection and robustness to time delay. We present a gain design met...

Usually, one favors a low resonance peak for vibration sensing, since this expands the measurement range. Furthermore, one wants to avoid ringing. Both requirements are met by a high damping, i.e. a low quality factor of Q ~ 1. In this contribution, we show that it is possible to design a micro-opto-electro-mechanical system (MOEMS) vibration sensor featuring a strong passive damping leading to...

We provide the necessary and sufficient conditions of Liouvillian integrability for Li\'{e}nard differential systems describing nonlinear oscillators with a polynomial damping restoring force. prove that are not Darboux integrable excluding subfamilies certain restrictions on degrees polynomials arising in systems. It is demonstrated if degree responsible force higher than producing damping, th...

We present a combined experimental and theoretical study of the drag force acting on a high porosity aerogel immersed in liquid (3)He and its effect on sound propagation. The drag force is characterized by the Knudsen number, which is defined as the ratio of the quasiparticle mean free path to the radius of an aerogel strand. Evidence of the Knudsen-hydrodynamic crossover is clearly demonstrate...