Match each technical passage describing military and aerospace engineering systems with the statement that expresses its explicitly stated main idea.
- Ultrasonic non-destructive inspection remains the most reliable method for detecting hidden subsurface delamination in aircraft composite structures. High-frequency acoustic waves pass into the carbon-fiber layers, reflecting back at different rates when internal voids or resin separations occur. Technicians monitor these echo patterns on diagnostic displays to evaluate material integrity without causing structural damage. Early discovery of these microscopic separations prevents catastrophic panel failure during high-stress flight maneuvers.Ultrasonic non-destructive testing is the most dependable technique for identifying hidden internal layer separations in composite aircraft structures.
- Tactical radio units maintain operational security in hostile electronic warfare environments through frequency-hopping spread spectrum technology. Rather than transmitting continuously along a single channel, the radio rapidly shifts carrier frequencies hundreds of times per second according to a pre-shared cryptographic key. This rapid frequency shifting makes military broadcasts exceptionally difficult for enemy systems to intercept or jam. Supporting transmitters synchronize their hopping sequences automatically, allowing continuous tactical voice traffic to proceed uninterrupted.Frequency-hopping spread spectrum technology enables tactical field radios to secure communications against electronic jamming and interception.
- Submerged naval vessels rely primarily on water electrolysis units to maintain continuous breathable oxygen levels for the crew. These electrochemical generators split purified demineralized water into gaseous hydrogen and oxygen using electrical power from the onboard reactor. The generated hydrogen is safely vented overboard or converted, while the concentrated oxygen is metered directly into the submarine's ventilation system. Continuous automated sensors monitor cabin partial pressures to ensure the atmospheric balance remains safe during prolonged underwater deployments.Electrolytic water-splitting generators serve as the primary source of breathable oxygen for crews aboard submerged naval vessels.
Answer
Passage 1 matches with the statement on ultrasonic non-destructive testing identifying internal layer separations in aircraft structures; Passage 2 matches with the statement on frequency-hopping spread spectrum securing tactical radio communications against jamming; Passage 3 matches with the statement on electrolytic water-splitting generators serving as the primary oxygen source for submerged crews.
Each passage explicitly presents its central concept in an identifiable opening topic sentence. The first passage focuses on ultrasonic inspection as the premier method for uncovering hidden composite delamination; the second passage establishes frequency-hopping spread spectrum as the primary technology for securing tactical radio transmissions against jamming; and the third passage explicitly defines water electrolysis as the primary system supplying breathable oxygen to submerged submarine crews.
Step-by-Step Solution
Key Concept
Identifying explicitly stated main ideas in technical passages
Estimated Time:1m 30s