background and aims. at present, cone beam computed tomography (cbct) has become a substitute for computed tomography (ct) in dental procedures. the metallic materials used in dentistry can produce artifacts due to the beam hardening phenomenon. these artifacts decrease the quality of images. in the present study, the number of artifacts as a result of beam hardening in the images of dental imp...

When a thin structure in which negative refraction occurs (a metallo-dielectric structure or a photonic crystal) is illuminated by a beam, the reflected and transmitted beam can undergo a large negative lateral shift. This phenomenon can be seen as an interferential enhancement of the geometrical shift and can be considered a signature of negative refraction.

We present wakefield measurements of a prototype Next Linear Collider (NLC) accelerator structure that was built with dipole mode damping and detuning to suppress the long-range transverse wakefield induced by a beam. In addition, we describe beam centering tests that use as a guide the dipole power coupled out of the structure for damping purposes.

We report first evidence of wakefield acceleration of a relativistic electron beam in a dielectric-lined slab-symmetric structure. The high energy tail of a ∼60  MeV electron beam was accelerated by ∼150  keV in a 2 cm-long, slab-symmetric SiO2 waveguide, with the acceleration or deceleration clearly visible due to the use of a beam with a bifurcated longitudinal distribution that serves to app...

Active vibration control is an important problem in structures. One of the ways to tackle this problem is to make the structure smart, adaptive and self-controlling. The objective of active vibration control is to reduce the vibration of a system by automatic modification of the system's structural response. This work features the modeling and design of a Periodic Output Feedback (POF) control ...

The polarized component of the diffuse radio synchrotron emission of our Galaxy shows structure, which is apparently unrelated to the structure in total intensity, on many scales. The structure in the polarized emission can be due to several processes or mechanisms. Some of those are related to the observational setup, such as beam depolarization – the vector combination and (partial) cancellat...

In the so-called “Two-Beam Acceleration Scheme” the energy of a drive beam is converted to rf power by means of a “Transfer Structure”, which plays the role of power source. In The Transfer Structure the bunched drive beam is decelerated by the electromagnetic field which it induces and builds up by the coherent interaction of successive bunches with the chosen longitudinal mode. The CLIC Trans...

In this paper the damage location in beam like-structure is determined using static and dynamic data obtained using finite volume method. The change of static and dynamic displacement due to damage is used to establish an indicator for determining the damage location. In order to assess the robustness of the proposed method for structural damage detection, three test examples including a static...

In this paper, an analytical formula to calculate the radial stiffness of groove elastic support is presented. The influence of structure parameters on radial stiffness and homogeneity of radial stiffness is investigated as well. The accuracy and calculating speed of the analysis formula are compared to that of finite element method (FEM). Findings are as following: The calculating speed of ana...