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5 Topic Pages Found in Technology & Engineering and starting with the letter U
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Open ultrasonics
ultrasonics

study and application of the energy of sound waves vibrating at frequencies greater than 20,000 cycles per second, i.e., beyond the range of human

Open ultrasound
ultrasound

Pressure waves, known as ultrasonic waves, similar in nature to sound waves but occurring at frequencies above 20,000 Hz (cycles per second), the

Open Ulysses (Spacecraft)
Ulysses (Spacecraft)

Ulysses was the first space probe to explore the region of space above the Sun's poles, as a joint project of the European Space Agency (ESA) and

Unidentified Flying Object (UFO)

or UFO, an object or light reportedly seen in the sky whose appearance, trajectory, and general dynamic and luminescent behavior do not readily

United States national missile defense

System for which planning began in the United States in the 1960s to guard against a nuclear attack. The concept of missile defense is a product of