Concerta and Adderall are medications used to treat attention deficit hyperactivity disorder (ADHD). These drugs help activate the areas of your brain that are responsible for focusing and paying attention. Concerta and Adderall are the brand names of generic medications. The generic form of Concerta is methylphenidate. Adderall is a combination of two generic drugs: amphetamine and dextroamphetamine. A side-by-side comparison of these two ADHD medications shows that theyâre similar in many ways. However, there are some differences.
Direct propulsion system is the most commonly used system on ships. Direct propulsion system is an invariable choice for low speed diesel engines and has a very basic arrangement. It consists of a propeller, which is connected to the main engine with the help of the shaft.
Solar Sails. Some future spacecraft may not be propelled by rockets. If NASA engineer Dean Alhorn has his way, they'll be powered by solar sailsâbig silver kites in space that are pushed along by the sun's rays. NASA engineer Dean Alhorn says that some future spacecraft may be propelled by the sun's rays. Editor's Note: Hours after NOVA recorded this interview on January 20, 2011, NASA succeeded in deploying its first solar sail in low-Earth orbit.