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N Nandhakumar

Publications and source records attributed to N Nandhakumar.

2 recordsLinked to original sources

Robust physics-based analysis of thermal and visual imagery.

Extensions to an existing physics-based approach for intersensory perception in which thermal and visual imagery of outdoor scenes is analyzed simultaneously for object recognition are discussed. The existing approach uses a model that is based on the principle of the conservation of energy at the surface of the imaged object. The model permits the computation of physically meaningful features that may be used for object classification. Two significant extensions are discussed. First, the model is used to analyze a temporal sequence of spatially registered thermal and visual imagery. Second, the energy-exchange model is used to formulate a linear-regression task in which the physical properties of the imaged object are the unknown parameters that are estimated. A statistically robust scheme is presented for this task. The robust technique minimizes sensitivity to outliers caused by segmentation errors and misregistration, which are endemic to multisensor fusion. Thus reliable physics-based features are made available by this approach.

Hot Temperature

Automatic tachycardia recognition.

A microcomputer algorithm for tachycardia identification, suitable for use in an implanted antitachycardia pacemaker, is described. The system employs an atrial and ventricular electrogram, detects a sustained fast rate in either chamber, and awakens the main program to perform detailed analysis of the tachycardia and its immediately preceding beats. The algorithm distinguishes atrial, ventricular, and AV nodal and re-entrant tachycardia from high rates due to sinus tachycardia. For testing of the program, we used a data base of twenty-two tape-recorded and documented arrhythmias provoked during electrophysiologic studies in which atrial and ventricular bipolar electrodes were in place; twenty-one were successfully detected. These included atrial fibrillation, atrial flutter, atrial tachycardia, AV nodal re-entrant tachycardia, AV re-entrant tachycardia using an accessory pathway, and ventricular tachycardia with and without ventriculo-atrial conduction.

Atrial Fibrillation