In this paper, the conditions for which three-dimensional crystalline ion beams were attained in the rf quadrupole storage ring PALLAS at a velocity of around 2800 m/s are presented. The stability of these crystalline beams when subjected to discontinuous cooling is discussed for beams of different linear density and thus of different crystal structure. The survival time seems to only weakly de...

A non-contact vibration measuring technique based on ultrasonic Doppler effect is studied. Two effects induce phase modulation on the received ultrasound signal, which are Doppler effect and nonlinear parametric effect. With the increasing of vibrating frequency, the phase variation due to parametric effect is getting greater and greater. In this paper, by measuring the acoustic pressure genera...

1. Theory An earlier treatment of line broadening in vibrational bands due to chemical exchange [2] was based on a second order perturbation theory. It dflers already for the case of non-exchanging systems from the density matrix procedure given by [1,3], although in this case the finite results are identical. To clear the issue it may prove helpful to derive the relevant equations using a pure...

Linear system identification is an important and useful approach in experimental modal analysis. It allows for the extraction of resonance frequencies, damping ratios and mode shapes of a vibrating structure. In order to reduce the bias on the estimates, the model order is usually chosen quite high. This often results in the appearance of non-physical, or so-called spurious modes. In this paper...

The physical properties of particles used in radiation therapy, such as protons, have been well characterized, and their dose distributions are superior to photon-based treatments. However, proton therapy may also have inherent biologic advantages that have not been capitalized on. Unlike photon beams, the linear energy transfer (LET) and hence biologic effectiveness of particle beams varies al...

PURPOSE To characterize and quantify the distal edge activity fall off, created in a phantom by a proton therapy beam METHOD AND MATERIALS: A 30×30×10cm polymethylmethacrylate phantom was irradiated with a proton therapy beam using different ranges and beams. The irradiation volume is approximated by a right circular cylinder of diameter 7.6cm and varying lengths. After irradiation, the phantom...

In this article, small scale effects on free vibration analysis of non-uniform nanobeams is discussed. Small scale effects are modelled after Eringen’s nonlocal elasticity theory while the non-uniformity is presented by exponentially varying width among the beams length with constant thickness. Analytical solution is achieved for free vibration with different boundary conditions. It is shown th...

We report two-dimensional simulations of strongly vibrated granular materials in zero gravity. The coefficient of restitution depends on the impact velocity between particles by taking into account both the viscoelastic and plastic deformations of particles, occurring at low and high velocities respectively. Use of this realistic restitution coefficient leads to new unexpected behaviors. When t...

The novel fixed (non-vibrating) Volta potential probe was evaluated in comparison with the standard, vibrating (400 Hz) commercial Kelvin probe. While both tested probes demonstrated the similar behavior, there were significant practical advantages of the novel probe. Specifically, the novel probe allows for the elevated distance to the surface and provides more sensitivity to charge under the ...