When outfitted with clever peripherals like folding, full-size keyboards and snap-on modems, these pocket rockets can even do limited duty as lightweight substitutes for laptop computers.
Automakers, for example, are beginning to use carbon fiber as a lightweight but strong substitute for metal to improve fuel efficiency.
In each water-to-binder ratio, the natural aggregate was substituted with the artificial lightweight aggregate at the replacement levels of 0%, 20 %, 40, and 60%.
And while there are a number of portable technologies that digitally pack whole desktops of information into thumb-size devices that can hang from key chains and charm bracelets, they are hardly a substitute for a lightweight notebook computer.
Brothers Richard and Peter Chambers, from Coleraine, were both celebrating as Peter raced as a substitute in the lightweight four, which led throughout to win by half a length from Italy.
They are, thus, ideal candidates to substitute float glasses, where lightweight and safety are of utmost relevance.
The lightweight concrete (in which rubber was substituted for sand) was evaluated using compressive strength, calorimetry and thermal conductivity tests of mortar.
Put on my eyeglasses," I insisted, substituting my mom's lightweight frames for the thick, big black ones that are de rigueur right now for many a bespectacled 20-something.
Another thing I like about plastics is they are lightweight, high-performance and a very good substitute for metals and fired masonry.
