Tag Archives: MIT

Optical Computing

18 Dec

Computer chips that transmit data with light instead of electricity consume much less power than conventional chips, but so far, they’ve remained laboratory curiosities. Professors Vladimir Stojanović and Rajeev Ram and their colleagues in MIT’s Research Laboratory of Electronics and Microsystems Technology Laboratory hope to change that, by designing optical chips that can be built using ordinary chip-manufacturing processes.Optical data transmission could solve what will soon be a pressing problem in chip design. As chips’ computational capacity increases, they need higher-bandwidth connections to send data to memory; otherwise, their added processing power is wasted. But sending more data over an electrical connection requires more power.

Optical chips use structures called waveguides to direct light, and researchers trying to add optical components to a silicon chip usually carve the waveguides out of a single crystal of silicon, Stojanović says. But waveguides made from single-crystal silicon require insulating layers above and below them, which standard chip-manufacturing processes like TI’s and Intel’s provide no way to deposit. They do, however, provide a way to deposit insulators above and below layers of polysilicon, which consists of tiny, distinct crystals of silicon clumped together and is typically used in the part of a transistor called the gate. So the MIT researchers built their waveguides from polysilicon instead.

So far, TI has produced two sets of prototypes for the MIT researchers, one using a process that can etch chip features as small as 65 nanometers, the other using a 32-nanometer process. To keep light from leaking out of the polysilicon waveguides, the researchers hollowed out the spaces under them when they got the chips back — the sole manufacturing step that wasn’t possible using TI’s in-house processes. But “that can probably be fixed more elegantly in the fabrication house if they see that by fixing that, we get all these benefits,” Watts says. “That’s a pretty minor modification, I think.”

To meet the bandwidth demands of next-generation chips, however, the waveguides will have to carry 128 different wavelengths of light, each encoded with its own data. So at the receiving end, the ring resonators provide a bank of filters to disentangle the incoming signals. On the prototype chips, the performance of the filter banks was “the most amazing result to us,” Stojanović says, “which kind of said that, okay, there’s still hope, and we should keep doing this.” The wavelength of light that the resonators filter is determined by the size of their rings, and no one — at either TI or MIT — could be sure that conventional manufacturing processes were precise enough to handle such tiny variations.

Bangladesh Arsenic Poisoning Mystery solved

18 Dec

A team from the Massachusetts Institute of Technology may have solved one of the great environmental disaster riddles of the last 30 years — where did the arsenic that has poisoned between two and 25 million people in Bangladesh come from?

The ponds in Bangladesh were dug over the past 50 years to provide dirt so home could be sited on high ground and so flood barriers could be built.

Using chemical tracers, the researchers show that when organic carbon settles at the bottom of these ponds, it seeps underground where microbes consume it. This creates a chain of biochemical events that causes naturally occurring arsenic to dissolve out of the sediment and into the ground water.

Tragically, international health agencies in the 1970s began a successful push to get villagers to dig shallow tube wells for water, to stop the spread of cholera and other water-borne bacterial diseases that came from drinking pond and river water.  Upwards of 40% of those wells are now contaminated with arsenic.

Beginning in the late 1970s the country was struck with severe, widespread arsenic poisoning. The immediate symptoms are violent stomach pains, vomiting, diarrhea, convulsions and cramps. Over the longer term, serious skin diseases can result.

The researchers found that when rice fields are irrigated with this arsenic-laden water, the rice filtered arsenic out of the water system. So one solution is to dig wells for drinking water below the level of the ponds. Another would be to put shallow wells under rice fields which naturally filter the arsenic.

They estimate that by replacing 31% of the wells in the country with deeper wells the health effects of the arsenic could be reduced by 70%.



Sixth Sense!!

15 Dec

Reading the title, one might wonder this article to be a sci-fi story. Well, for those who think the way, you are quite wrong. When I first heard about it, I too thought it was a sci-fi movie. But it turns out to be one of the greateest inventions of man kind. The inventor is Pranav Mistry. Before we start with discussing about the device, let me tell you something about him. He did his  bachelors degree in Computer Science and Engineering. Palanpur , which is situated in northern Gujarat in India. He received his  Master in Media Arts and Sciences from MIT and Master of Design from IIT Bombay. Currently,He is a  Research Assistant and PhD candidate at the MIT Media Lab.

Now what is Sixth Sense ?

‘SixthSense’ is a wearable gestural interface that augments the physical world around us with digital information and lets us use natural hand gestures to interact with that information. – Courtesy pranav mistry.com

Thats how Pranav defines this little electronic device. The SixthSense prototype is comprised of a pocket projector, a mirror and a camera. The hardware components are coupled in a pendant like mobile wearable device. Both the projector and the camera are connected to the mobile computing device in the user’s pocket. The projector projects visual information enabling surfaces, walls and physical objects around us to be used as interfaces; while the camera recognizes and tracks user’s hand gestures and physical objects using computer-vision based techniques. The software program processes the video stream data captured by the camera and tracks the locations of the colored markers (visual tracking fiducials) at the tip of the user’s fingers using simple computer-vision techniques. The movements and arrangements of these fiducials are interpreted into gestures that act as interaction instructions for the projected application interfaces. The maximum number of tracked fingers is only constrained by the number of unique fiducials, thus SixthSense also supports multi-touch and multi-user interaction.

The SixthSense prototype implements several applications that demonstrate the usefulness, viability and flexibility of the system. The map application lets the user navigate a map displayed on a nearby surface using hand gestures, similar to gestures supported by Multi-Touch based systems, letting the user zoom in, zoom out or pan using intuitive hand movements. The drawing application lets the user draw on any surface by tracking the fingertip movements of the user’s index finger. SixthSense also recognizes user’s freehand gestures (postures). For example, the SixthSense system implements a gestural camera that takes photos of the scene the user is looking at by detecting the ‘framing’ gesture. The user can stop by any surface or wall and flick through the photos he/she has taken. SixthSense also lets the user draw icons or symbols in the air using the movement of the index finger and recognizes those symbols as interaction instructions. For example, drawing a magnifying glass symbol takes the user to the map application or drawing an ‘@’ symbol lets the user check his mail. The SixthSense system also augments physical objects the user is interacting with by projecting more information about these objects projected on them. For example, a newspaper can show live video news or dynamic information can be provided on a regular piece of paper. The gesture of drawing a circle on the user’s wrist projects an analog watch.

For further details check out this video




MIT Open Course Ware (OCW):

12 Sep

MIT-OCW of Massachusetts Institute of Technology is a website that provides 1900 courses from the institute itself for undergraduates and graduate-level partly free. This website is to give opportunity for people outside MIT to be exposed to MIT’s educational culture.

This website contains:

  • Chronological reading list
  • Discussion topics
  • Homework problems and exams, often with solutions
  • Lecture notes
  • Few interactive web demonstration
  • Complete textbooks by MIT professors
  • Online streaming video lectures (some are downloadable)

This website has 58 million visitors but only 5% of them being Indians. This website does not require registration and is very simple to use. So I hope more people form India reconsider using such a resourceful website.

Link: http://ocw.mit.edu/ocw.web/home/home/index.htm