Abstract: A nondestructive method of and apparatus for detecting degradation of reinforcing members embedded within a structure is disclosed. Degradation can arise from many sources, such as corrosion, fracture, cracking, fatigue, chemical reaction, etc. The device includes an inducing instrument(210) to induce a vibration of the reinforcing members (110)and a measuring device (220) to detect the vibration of the reinforcing members. The measurement is analyzed to detect the presence of reinforcing member degradation or reinforcing member-to-concrete bonding. The device may include a controller (230) to enhance the detection. The device may also include an amplifier (240) to further increase the energy in the waves imparted to the structure and the acoustic waves detected by the measuring instrument.

Abstract: A method for selecting trees for harvest according to a predetermined criterion is provided which includes at least the steps of applying a vibrative member to the tree, vibrating the vibrative member, determining the resonance properties of the vibrative member, calculating an observed quality factor associated with the vibrative member vibrations, and, comparing the observed quality factor with a predetermined relationship between the quality factor and the tree selection criterion. A portable tree probe, suitable for field use, is also provided.

Abstract: Vanadium dioxide (VO.sub.2) based infrared spatial light modulators (SLM) in four embodiments are disclosed:(1) A VO.sub.2 thin film is deposited on a planar diode array. Each diode constitutes a "pixel" of the SLM. Power provided to a diode permits accurate thermal control about the thin film's hysteresis. Initial biasing of the diode array is required to the base of the VO.sub.2 's hysteresis curve.(2) & (3) VO.sub.2 is deposited on a thermoelectric array which can be an array of doped lines of p and n type material or a conductive material between two electrical contacts. The pixels have the ability to both heat and cool the VO.sub.2 film, thereby allowing the array to be operated in a bistable mode. Bistable operation requires external biasing to the center of the VO.sub.2 's hysteresis curve.(4) A VO.sub.2 thin film deposited on a substrate which is spaced a distance, L, from an array of vertical-cavity surface-emitting lasers for heating the VO.sub.2.