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• s  shaped like a ring

• Astronauts described the objects variously as a plastic baggie, some copper wire, two ring-shaped items and a piece of foil or shimmering cloth.
• The ring-shaped combustion chamber can be divided into many small segments, each with its own fuel supply.
• A beam of protons was sent whirling around a ring-shaped tunnel some 300 ft.

• annular
• annulate
• annulated
• circinate
• ringed
• doughnut-shaped

News & Articles

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• Dust In The Wind… Black Hole Style
  Over the years, researchers have taken myriad observations of black holes and their environs, but now ESO’s Very Large Telescope Interferometer is giving us the most detailed look of the dust around a black hole at the center of an active galaxy ever obtained. Originally expected to be contained within the ring-shaped torus around the [...]
  June 20, 2013 - Universe Today
• Plano-Concave Axicons suit laser material processing.
  Featuring one concave conical surface and one plano surface, Plano-Concave Axicons are used in laser material processing to create ring-shaped image along optical axis and non-diffractive approximation of Bessel beam. Units are available in twelve 25.4 mm diameter models with apex angles of 90, 130, 140, 160, 170, or 175°, and either VIS 0° or NIR I coating. When Plano-Concave Axicons are used ...
  June 17, 2013 - ThomasNet