In escalator construction, the hollow metal frame that carries the track along the length of the unit is the truss. This structural skeleton provides the primary support, keeps the track and steps aligned, and distributes loads across the escalator structure. The tracks themselves are the rails the steps ride on, not the hollow support frame. The comb plate sits at the entry/exit to seal gaps and work with the comb teeth, while comb lights are lighting fixtures near those areas. So the hollow structural member that holds the track is the truss.

Detecting smoke and triggering the alarm is the job of a smoke detector. It senses smoke particles in the air—typically using ionization or photoelectric methods—and, when smoke is detected, activates its audible alarm. This is different from a heat detector, which responds to high heat rather than smoke; a fire alarm control panel, which is the central system that processes inputs and controls alarms, doesn’t detect smoke by itself; and a manual pull station, which requires a person to trigger the alarm. So the device that both detects smoke and sounds the alarm is the smoke detector.

The pattern you’re looking for comes from combining diffuse light with indirect light so that a portion goes upward toward the ceiling and a portion goes downward into the space. General Diffuse / Direct-Indirect Lighting fits this idea because it mixes diffuse illumination with an indirect component, spreading light broadly and reflecting off surfaces. That reflection and diffusion send light both upward and downward, yielding a fairly balanced distribution. Direct lighting, by contrast, sends most light downward onto tasks. Semi-direct is mainly downward with a smaller upward component. Semi-indirect is mainly upward with less downward contribution. So only the general diffuse / direct-indirect approach achieves that almost-equal upward and downward distribution.

The key idea is understanding who made a practical, long-lasting incandescent light bulb available for widespread use. Thomas Edison and his team conducted extensive experiments, testing thousands of materials for filaments and refining the bulb’s vacuum. Their work led to a carbon filament that could glow for many hours and a bulb design that lasted significantly longer than earlier versions, which is what made electric lighting commercially viable. While others contributed to related technologies—Nikola Tesla with alternating current systems, Alexander Graham Bell with the telephone, and George Westinghouse with power distribution—the person most associated with a durable, market-ready incandescent bulb is Thomas Alva Edison.