Mechanical stress in the context of "Double refraction"

A navalised aircraft (or navalized aircraft) is an aircraft that is designed for naval usage. A navalised aircraft specifically designed to take off and land from the flight deck of an aircraft carrier is called a carrier-based aircraft.

Navalised aircraft include both fixed-wing (including seaplanes, biplanes, monoplanes and flying wings, both propeller- and jet-propelled) and rotary-wing aircraft (helicopters, tiltrotors and, in some cases, multicopters). In many cases, the aircraft is simply a modified variant of a land-based model. They are different to land-based aircraft in that they are designed to tolerate greater corrosion due to humidity and salt weathering around marine environments, handle increased mechanical stress due to harsher air conditions such as strong sea breezes and extreme weathers, and often need to operate on moving vessels at sea, which typically dictates more complex flight control to deal with unsteady sea state and also the ability to perform vertical/short takeoff and landing as there are very limited runway spaces available (or none at all) on deck.

Acoustic quieting is the process of making machinery quieter by damping vibrations to prevent them from reaching an observer. Machinery vibrates, causing sound waves in air, hydroacoustic waves in water, and mechanical stresses in solid matter. Quieting is achieved by absorbing the vibrational energy or minimizing the source of the vibration. It may also be redirected away from an observer.

One of the major reasons for the development of acoustic quieting techniques was for making submarines difficult to detect by sonar. This military goal of the mid- and late-twentieth century allowed the technology to be adapted to many industries and products, such as computers (e.g. hard drive technology), automobiles (e.g. motor mounts), and even sporting goods (e.g. golf clubs).