The focus of this dissertation is on the algorithm design, implementation, and validation of parallel transmission technology in Magnetic Resonance Imaging (MRI). Novel algorithms are proposed which yield excellent excitation control, low RF power requirements, methods that extend to non‐linear large‐flip‐angle excitation, as well as a new algorithm for simultaneous spectral ...

In parallel excitation, the computational speed of numerical radiofrequency (RF) pulse design methods is critical when subject dependencies and system nonidealities need to be incorporated on-the-fly. One important concern with optimization-based methods is high peak RF power exceeding hardware or safety limits. Hence, online controllability of the peak RF power is essential. Variable-rate sele...

A procedure denoted as Line Sampling (LS) has been developed for estimating the reliability of static and dynamical systems. The efficiency and accuracy of the method is shown by application to the subset of the entire spectrum of the posed benchmark problems [12], i.e. in particular linear systems with random properties. The notion of design point excitation for nonlinear system is discussed a...

A previous study proposed an optimal vibration isolator for self-excitation, but the solution results showed a critical drawback basement input. Because plant system is exposed to self-excitation and input, characteristics must meet all requirements of both excitation cases. Two performance indices were introduced evaluate control capability over two cases, using theoretical linear model electr...

The excitation mechanism of low degree acoustic modes is investigated through the analysis of the stochastic time variations of their energy. The correlation between the energies of two different modes is interpreted as the signature of the occurrence rate of their excitation source. The different correlations determined by Foglizzo et al. (1998) constrain the physical properties of an hypothet...

In this paper, a very low bit speech coder at 1.2 kbps is newly proposed. Like the LPC vocoder, it only requires gain, pitch, and spectral information, but its quality is far superior. The synthesis method is one of harmonic coding, using sinusoids whose frequencies are multiples of the fundamental frequency, where the amplitudes of the sinusoids are adaptively modulated using Gammatone lters a...

We report a measurement of the excitation spectrum omega(k) and the static structure factor S(k) of a Bose-Einstein condensate. The excitation spectrum displays a linear phonon regime, as well as a parabolic single-particle regime. The linear regime provides an upper limit for the superfluid critical velocity, by the Landau criterion. The excitation spectrum agrees well with the Bogoliubov spec...

Propagated waves of excitation in developing neural tissues may be a critical feature of maturation. Recent findings shed new light on the mechanisms underlying these waves.

Molecular R-matrix calculations are performed to obtain rotational excitation rate coefficients for electron collisions with the symmetric-top ions H3 and H3O + up to electron temperatures of 10 000 K. De-excitation rates and critical electron densities are also given. It is shown that short-range interactions, which are ignored in the standard Coulomb–Born theory, are crucial for studying elec...

Molecular R-matrix calculations are performed to give rotational excitation rates for electron collisions with linear molecular ions. Results are presented for CO, HCO, NO and H2 up to electron temperatures of 10 000 K. De-excitation rates and critical electron densities are also given. It is shown that the widely used Coulomb–Born approximation is valid for Dj 1⁄4 1 transitions when the molecu...