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What’s wrong with this horse?

Jon HWheatley24 February 2015

Pony-pic-3

Image credit: Tyler Sorensen, UCL Computer Science

Two ponies, rendered using different computer hardware. The pony on the left is computed with an Intel CPU and looks normal. The one on the right is computed with an Nvidia GPU and looks buggy. Why do different hardware setups lead to different results? And how can this be tested?

Dr Jade Alglave (UCL Computer Science) has just been awarded a Royal Society prize for her work on testing and verifying different types of computer chip.

Chips by ARM, AMD, IBM, Intel, or NVidia are found in devices ranging from smartphones to supercomputers, cars to aeroplanes. Programming software to run on multiprocessors is a form of concurrent programming, where multiple computations are executed during overlapping time periods. Sadly, due to the great number of possible outcomes of a given program, concurrent programming is error prone and “buggy”, and difficult to test, as the picture shows.

Dr Alglave has developed a tool to test and model proprietary hardware which ensures that software runs consistently across a range of platforms, reducing delays and costs caused by errors and inconsistencies.

Skulls, subs, and selective laser sintering

KateOliver14 July 2014

We hear a lot about 3D printing as the future of manufacture, but it’s also finding many applications in research.

Today’s picture of the week shows three of the uses researchers at UCL Engineering are finding for additive manufacture.

Examples of research objects created using 3D printing at UCL Engineering

Examples of research objects created using 3D printing at UCL Engineering

On the left, a model submarine printed by a student in Naval Architecture lets them see their designs in 3D. In the middle, UCL computer scientists experiment with the exciting new problem of creating virtual models that can be printed out with movable, posable parts; and on the right, a section of 3D printed skull, recreated from scans by researchers at UCL Medical Physics based within UCLH, enables surgeons to plan their operations.

Old school meets new tech: a chimp skull from UCL's zoological teaching collections next to a high-tech 3D print from UCL Medical Physics.

Just for fun: old school meets new tech: a chimp skull from UCL’s Bioanthropology Collections next to a high-tech 3D print of a modern human from UCL Medical Physics. Will 3D printed skulls be the future of anatomy teaching?

All of these models were printed using a method called Selective Laser Sintering (SLS). This is a kind of 3D printing that uses lasers to melt bits of a polymer powder together in the shape of a cross-section through the object you want to print. Then, a layer of power is added on top, and another layer melted. If it is resting on powder, that powder will just brush off when the plastic model is removed: if it is resting on a previously melted bit, it will stick to it.

This is a more expensive way to 3D print than the hobby-level 3D printers which are more commonly seen, which basically squeeze out layers of plastic like toothpaste, stacking them up into shapes . However, it allows the printing of more complicated shapes, with overhangs and interpenetrating parts – so it’s really handy for detailed research uses. UCL has a number of 3D printers, some free for all our staff and students to use in our open access Makespace.