Feedback controllers for the stabilization of the angular velocity vector of a rigid spacecraft using a single-gimbal Variable Speed Control Moment Gyro (VSCMG) are presented. Linearization of the equations of motion show that complete attitude stabilization is not possible via linear methods. Nonetheless, it is shown that the linearized angular velocity equations are controllable, and a simple...

We propose and demonstrate a mechanism for small-modal-volume high-Q cavities based on an anomalous uniform waveguide mode that has zero group velocity at a nonzero wave vector. In a short piece of a uniform waveguide with a specially designed cross section, light is confined longitudinally by small group-velocity propagation and transversely by a reflective cladding. The quality factor Q is gr...

MEASUREMENT OF MUSCULOSKELETAL MOTION USING VECTOR TISSUE DOPPLER IMAGING Avinash Eranki, Master of Science George Mason University, 2010 Thesis Director: Dr.Siddhartha Sikdar The goal of this project is to develop, characterize and validate vector tissue Doppler imaging (vTDI) to measure dynamic musculoskeletal motion. We have developed a vector tissue Doppler imaging system using a clinical u...

Introduction Left ventricular (LV) twist is believed to store potential energy and plays an important role in generating diastolic suction. Recent advances in echocardiography techniques have allowed quantification of LV twist. The aim of the present study was to compare LV twist and torsion in healthy human subjects determined by velocity vector imaging (VVI) and tissue Doppler imaging (TDI) a...

INTRODUCTION Two-dimensional strain analysis is a powerful analysis modality, however, clinical utilization has been limited by variability between different analysis systems and operators. We compared strain in adults and children using vendor-specific and vendor-independent software to evaluate variability. METHODS One hundred and ten subjects (50/110 pediatric, 80/110 normal left ventricul...

Doppler velocity measurements from airborne meteorological Doppler radars require removal of the aircraft motion contribution in order to provide radial velocity of hydrometeor targets. This is a critical step for hydrometeor motion and wind retrievals. The aircraft motion contribution is defined as the scalar product between the radar antenna beam-pointing vector and the aircraft velocity vect...

introduction left ventricular (lv) twist is believed to store potential energy and plays an important role in generating diastolic suction. recent advances in echocardiography techniques have allowed quantification of lv twist. the aim of the present study was to compare lv twist and torsion in healthy human subjects determined by velocity vector imaging (vvi) and tissue doppler imaging (tdi) a...

Classical hydrophones measure pressure only, but acoustic vector-sensors also measure particle velocity. Velocity measurements can increase array gain and resolve ambiguities, but make vector-sensor arrays more difficult to analyze. This thesis derives a new set of useful performance measures for acoustic vector-sensor arrays. It characterizes the vector-sensor array beampattern with and withou...

This paper presents an improved neural computation where scheme for kinematic control of redundant manipulators based on infinity-norm joint velocity minimization. Compared with a previous neural network approach to minimum infinity-non kinematic control, the present approach is less complex in terms of cost of architecture. The recurrent neural network explicitly minimizes the maximum componen...