英語聽力：自然百科 伊拉克古物重現(xiàn)原貌

The same technology used to make prosthetic limbs is now being used to clone some of the world's earliest manuscripts from Mesopotamia, an area near modern-day Iraq. When the US invaded Iraq in 2003, thousands of artifacts were stolen from museums in Baghdad. Those losses include tens of thousands of tablets made by Sumerians as early as 5,000 years ago.

This cuneiform tablets were some of the oldest known written documents in the world, which recorded anything from laws to simple business transactions. The project, run by Pisa University's Assyriology Department and the Italian Agency for New Technologies, Energy and the Environment, is called Duplication and Rebirth. It uses a process called rapid prototyping to create both virtual and physical reproductions of the antiques. Today the team has recorded about 20,000 artifacts borrowed by private western collections. They use photographs, bibliographical references and when possible, 3-D images to catalogue each piece.

Here's a three-dimensional scanner. We use it to create the 3-D models of the cuneiform tablets. As you can see, a tablet, in this case a copy, is zipped by a laser ray which scans the surface to obtain the points to build a 3-D image. The data from the scanner is acquired through software which allows us to build the three-dimensional model. This data is necessary for the rapid prototyping to work, but can also be used to recreate a virtual copy of the tablet which can be viewed on a computer or over the internet.

Data that's collected is then used in rapid prototyping. Layers of thermoplastic material are built up to recreate a precise replica of the original.

With this machine it's possible to make a physical model of a tablet. And it's possible to make this tablet layer by layer. The layer is very small because it is 0.8 millimeter.

The three-dimensional models are especially useful because the tablets were written on the front, back and sides, requiring one to rotate them to read the full text.