Efficient ATR using compression

We examine various model-based automatic target recognition (MBATR) classifiers to investigate the utility of model-catalog compression realized via signal-vector quantization (VQ) and feature extraction. We specifically investigate the impact of various compression rates and common automatic target recognition (ATR) scenario variations such as noise and occlusion through simulations on high-range resolution (HRR) radar and synthetic aperture radar (SAR) data. For this data, we show that significant computational savings are possible for modest decreases in classification performance.     

Modification of plant growth and development by acceleration and vibration: concerns and opportunities for plant experimentation in orbiting spacecraft.

Growth, development, and orientation of higher plants is altered by physical disturbances such as shaking, touching, or vibration. Plant growth responses to thigmic (contact rubbing) forces are almost always negative, whereas growth responses to periodic seismic (shaking) or vibric (vibrational) disturbances may be positive or negative, depending on intensity and duration of force, and prevailing environmental conditions. Seedlings are most sensitive to mechanical stress when grown in darkness or under the low-light conditions typically available in plant flight hardware. Brief exposure to physical perturbation causes immediate growth inhibition of dark-grown seedlings followed by gradual recovery of growth rate beginning 10-12 minutes later. For mild vibration, growth rate may overshoot that of undisturbed control plants within an hour of a stress episode, whereas for thigmic stress recovery may remain incomplete for 24 hours or longer. Lack of physical stimulation by gravity should make plants even more responsive to random physical perturbation. Threshold growth response of seedlings to vibrational parameters needs to be determined under real spaceflight conditions.