Abstract: A stable, wide-bandgap (approximately 6 eV) ZnO/MgO multilayer thin film is fabricated using pulsed-laser deposition on c-plane Al2O3 substrates. Layers of ZnO alternate with layers of MgO. The thickness of MgO is a constant of approximately 1 nm; the thicknesses of ZnO layers vary from approximately 0.75 to 2.5 nm. Abrupt structural transitions from hexagonal to cubic phase follow a decrease in the thickness of ZnO sublayers within this range. The band gap of the thin films is also influenced by the crystalline structure of multilayer stacks. Thin films with hexagonal and cubic structure have band-gap values of 3.5 and 6 eV, respectively. In the hexagonal phase, Mg content of the films is approximately 40%; in the cubic phase Mg content is approximately 60%. The thin films are stable and their structural and optical properties are unaffected by annealing at 750° C.

Abstract: A seismic switch is a programmable device capable of distinguishing between seismic movements due to an earthquake or an explosion, which is used to send a signal to control panels for security doors. The device uses accelerometers and a microcontroller for the detection and signal analysis of the seismic movements. In the event of an explosion or earthquake, the device produces a loud sound which serves as an audible alarm. Other proposed applications, with minor modifications to the device or software code, include monitoring of freight handling, emergency shut-off controller for industrial control systems and machinery, a by-pass system for electronic access control panels, and as a theft-deterrent or a component of a security system for automated teller machines and other valuable devices or items.

Abstract: A seismic switch is a programmable device capable of distinguishing between seismic movements due to an earthquake or an explosion, which is used to send a signal to control panels for security doors. The device uses accelerometers and a microcontroller for the detection and signal analysis of the seismic movements. In the event of an explosion or earthquake, the device produces a loud sound which serves as an audible alarm. Other proposed applications, with minor modifications to the device or software code, include monitoring of freight handling, emergency shut-off controller for industrial control systems and machinery, a by-pass system for electronic access control panels, and as a theft-deterrent or a component of a security system for automated teller machines and other valuable devices or items.