As the weather turns spring-like, winter's ice build-up on power lines, windshields, and airplane wings becomes a fading memory. Professor Victor Petrenko, of Thayer School of Engineering at Dartmouth College (Dartmouth, NH), hopes to keep it that way. The physicist discovered that applying a small electric voltage across an ice-metal interface can break the bond between ice and metal surfaces. Technically, Petrenko says, ice is a semiconductor--included in a small class of substances in which protons, rather than electrons, carry an electrical current. When an electrically-charged surface comes into contact with any other surface, the charged surface induces an opposite charge in the facing surface and, because opposites attract, the two surfaces are drawn together. "This simple attraction accounts for most of ice adhesion," says Petrenko. Breaking the bond between ice and metal, he reasoned, should be as simple as neutralizing the surface charge with an equal amount of its opposite. He tested his theory using a sheet of ice, a globule of mercury--which stays liquid until temperatures dip below -40F--and a small battery with two wires attached. He touched one wire to the ice, the other to the mercury. The mercury drew itself up and away from the ice. Petrenko repeated the experiment using steel and other solid metals. In each case, the electricity caused the ice to lose adhesion. The effect could also be reversed, causing a surface to stick more firmly to the ice. "It may be possible to prevent or significantly reduce icing on the wings of an airplane using a battery no bigger than the one in your car," Petrenko theorizes. Surface-to-surface interactions are also important in manufacturing and machinery. Call: (603) 646-2117.
The engineers and inventors of the post WWII period turned their attention to advancements in electronics, communication, and entertainment. Breakthrough inventions range from LEGOs and computer gaming to the integrated circuit and Ethernet -- a range of advancements that have little in common except they changed our lives.
Neil Fromer is the executive director of the Resnick Institute, a program for energy and sustainability at the California Institute of Technology, working to develop new ideas and research technologies related to providing a sustainable future. He spoke to us about the severity of the current drought in California and how solar energy can help prevent such situations in the future.
From home enthusiasts to workers on the manufacturing floor, everyone's imagination is captured by the potential of 3D printing. Prototyping, spare parts creation, art delivery, human organ creation, and even mass product production are all being targeted as current and potential uses for the technology.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.