The main gradient limitation for high frequency accelerators is rf breakdown. While the physics of this gradient limitation still lacks a full theoretical understanding, a fairly complete empirical picture has emerged from the experimental work done in the past few years to characterize this phenomenon. Experimental results obtained mostly in the framework of the NLC/GLC project at 11 GHz and f...

Islanding operation is one of the main features of a MicroGrid (MG), which is realized regarding the presence of distributed energy resources (DERs). However, in order to deal with the control challenges, which an MG faces during island operation, particularly when the transition is associated with certain excessive load, an efficient control strategy is required. This paper introduces a Centra...

   The main purpose of the present investigation is to analyze more comprehensively the size-dependent nonlinear free vibration response of multilayer functionally graded graphene platelet-reinforced composite (GPLRC) nanobeams. As a consequence, both of the hardening stiffness and softening stiffness of size effect are taken into consideration by implementation of the nonlocal str...

Introduction At higher static field strengths of 7T and above specific absorption rate (SAR) and acoustic sound pressure level (SPL) pose limitations on the pulse sequence design. To overcome SAR limitations, the VERSE principle can be used [1]. Here, the envelope of existing rf pulses are modified together with the shape of the slice-selection gradient to selectively reduce high B1 amplitudes ...

Introduction The signal loss by the susceptibility artifact makes it difficult analyze the fMRI data of the orbitofrontal region of the brain. In addition, an EPI sequence, which is used in many fMRI experiments, has the geometric distortion and Nyqust ghosts. For the fMRI experiment with correction of these artifact and distortion, we used a flat RF pulse which provides nearly constant signal ...

Virtually all MRI sequences produce images with some degree of T1 weighting, in fact probably the only sequence that has no T1 weighting would be a single RF pulse acquisition such as gradient echo EPI performed in isolation (with an infinite TW). Therefore in principle the vast majority of pulse sequences could be used to measure T1 by simply adjusting their timing or flip angles to change the...

The southern Andes create a variety of atmospheric phcromena, b:* &ese have not been well studied. In this paper, we describe our preliminary observations and modeling of a few of these phenomena including: the sharp vegetation gradient on the eastern slopes, orographic triggering ofroll convection, foehn wall and short lee-wave trains, liquid clouds capping ice clouds, "bullef' clouds, and iso...

The results derived in Ref. 2 have been used to calculate a sample set of parameters1 for a superconducting version of the two-mile SLAC accelerator. These calculations have been carried out in order to provide a basis for further technical discussions. Beam Energy The energy goal of 100 GeV (10 MeV/ft.) has been chosen since this energy is sufficiently higher than the 20 GeV capability of the ...

The forced vibration behaviors are examined for nonlocal strain gradient nanobeams with surface effects subjected to a moving harmonic load travelling with a constant velocity in terms of three beam models namely, the Euler-Bernoulli, Timoshenko and modified Timoshenko beam models. The modification for nonlocal strain gradient Timoshenko nanobeams is exerted to the constitutive equations by exc...