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The feasibility of hurricane modification was investigated for hurricane Katrina using the Weather Research and Forecasting Model (WRF). The possible impact of seeding of clouds with submicron cloud condensation nu-clei (CCN) on hurricane structure and intensity as measured by nearly halving of the area covered by hurricane force winds was simulated by "(More)
The quality of magnetic resonance imaging systems has improved to the point that motion is a major limitation in many examinations. Translational motion in the imaging plane causes the phase of the data to be corrupted. An algorithm using computer post-processing is proposed to correct the phase of the data, and hence remove the artifact. This algorithm has(More)
A self-scanned 1024 element photodiode array and minicomputer are used to measure the phase (wavefront) in the interference pattern of an interferometer to lambda/100. The photodiode array samples intensities over a 32 x 32 matrix in the interference pattern as the length of the reference arm is varied piezoelectrically. Using these data the minicomputer(More)
The phase of an image obtained with many magnetic resonance imaging techniques is related to some physical variable of interest. This phase needs to be unwrapped, which is complicated by the presence of noise and multiple objects of irregular shape. A new two-dimensional phase unwrapping algorithm is presented, along with simulation results.
Discrimination between signals produced by fat and by water is an important issue in MRI. One efficient approach is to perform fat-suppression by selective inversion. This technique exploits the transition region of a selective RF pulse to invert the longitudinal lipid magnetization while leaving the magnetization of the water protons untouched. The(More)
An algorithm that suppresses translational motion artifacts in magnetic resonance imaging (MRI) by using post processing on a standard spin-warp image is presented. It is shown that translational motion causes an additional phase factor in the detected signal and that this phase error can be removed using an iterative algorithm of generalized projections.(More)
Optimal control theory has been applied in the past for the design of RF pulses for selective excitation. This was the outcome of having established the controllability of the MR spin system for the selective excitation problem. "Minimum distance" was the main formulation used for the solution. Because of their robust behavior in the presence of(More)
An NMR imaging method, called spin invesion (SI) imaging, is described for imaging under a magnetic field with high nonuniformity. 180 degrees flips are applied between sampling times of the FID to remove the effects of field nonuniformities on the FID. The only requirement for SI imaging is to have high enough RF power. This requirement may be satisfied(More)