Mechanical engineering is a broad discipline. Mechanical engineers are concerned with the analysis and design of structures and mechanisms, such as robots or the International Space Station. Mechanical engineers are also concerned with the flow of fluids, including air and water, and the transfer of heat, as in the air conditioner in your car or in the engine of a jet plane. Some other examples of where mechanical engineers apply their knowledge of structures, mechanisms, fluids, and thermal science are the fabrication of physical structures on electronic microchips (such as those found in automobile air bags) and the improvement of medical ultrasound equipment. The knowledge learned in mechanical engineering also prepares students to specialize in any of the fields that employ engineers, such as environmental engineering, electric power- and energy-system engineering, electronics packaging, acoustics and noise control, structural and materials engineering, product manufacturing, thermal and fluids engineering, chemical and petroleum processing, automotive engineering, aerospace engineering, bioengineering, micro- and nano-technology, robotics, and automation.