杏吧原创

Following well-publicised spying scares at the Los Alamos National Laboratory
and elsewhere, the Pentagon has taken action to ensure that staff don鈥檛
accidentally leave safe doors and secure filing cabinets open. A system it
commissioned from Pacific Northwest National Laboratory uses contact switches
built into cabinets and safes to detect when their doors are shut and infrared
sensors to check that bolts are in place. Data from these sensors is beamed by
radio to a unit built into the door of the room which also includes an infrared
sensor. Anyone leaving while the cabinet or safe is unlocked, triggers a siren
or a warning light.