1 Clinical Psychologist: Doctorate Degree in Psychology (4 to 7 years of graduate school) 2  Industrial-Organizational Psychologist: Master's Degree (2 to 3 years of graduate school)  Forensic Psychologist: Master's Degree (2 to 3 years of graduate school); a doctoral degree is recommended.
Submarine Propulsion Systems. During World War II, most American submarines were powered by diesel-electric systems. This was a departure from earlier submarine power systems, which were direct drive types, little changed from the earliest boats. In this direct-drive power system, the diesel engine is directly connected to the propeller shaft.
Nuclear-Powered Ships. Nuclear power is particularly suitable for vessels which need to be at sea for long periods without refuelling, or for powerful submarine propulsion. Over 140 ships are powered by more than 180 small nuclear reactors and more than 12,000 reactor years of marine operation has been accumulated.