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.
United States. While the United States Navy is runner up on this list of the 10 largest submarine fleets in the world, it is arguably the most capable. While most of the countries on this list have fleets that are largely diesel-electric, the entire fleet of the US Navy is nuclear powered. The US has a large number of Los Angeles class attack submarine.