Saturday, May 03, 2014
Wednesday, April 30, 2014
Building a WiFi “Satellite”
This post is really a companion to my recent post http://www.obvioustruths.blogspot.in/2014/04/use-unlicensed-wifi-spectrum-in-rural.html Please read that if possible, before reading the following. It will give you the context in which I write.
Actually the system does not have to be on the tallest peak or building in the area, but on a well-chosen place that provides effective line of sight with suitable user groups like schools/colleges. The altitude at which it is located should help it to command a large area around. I expect that it would be easy to find many places in India, where one such device would cover a thousand square kilometers within WiFi range! The “satellite” should, of course, be mounted on a tower or something like that to prevent theft!
The system would include a router, several 5.8 GHz radios and directional antennas. It would have maintenance-free storage batteries and solar panels. Designing such a device is an inter-disciplinary engineering activity and I hope students from different disciplines would volunteer to look into the different aspects. Many design issues arise – like should we decide in advance what the user groups should be and fix the directional antennas appropriately? What is the ideal trade-off between simplicity and sophistication? I will leave to readers to find such issues and discuss them.
Srinivasan Ramani
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Labels: 5.8 MHz, communications relay, design, inter-disciplinary engineering, line of sight, student project, WiFi
Friday, April 18, 2014
Prof R Narasimhan's Birthday (April 16)
It is Professor Narasimhan’s birthday today (April 16). If he had lived on, he would have been eighty eight today. There is one simple way many of us can further a goal he worked for - running high quality conferences in the computer field in India. His family has made available to the Tata Institute of Fundamental Research, the Institute where he spent his working life, a handsome endowment for an annual memorial award to bring a world-class invited speaker to international conference in the computer field in India. We should spread this information among program committee members of such conferences. For details, please visit
http://www.tifr.res.in/~endowment/index.php/endowment-awards/prof-r-narasimhan-lecture-award
I will quote a few lines from this site:
2. One award will be given annually in the field Computer Science and Technology and will recognize advances in hardware, software, theoretical aspects of computing, or applications of computing.
3. The award will recognize the achievement of younger professionals only and hence will be restricted to professionals up to the age of 40.
4. Recipients of the award should hold a degree from an Indian University, excluding honorary degrees.
5. The award will be in the form of a scroll, with a trophy or plaque (rather than in monetary form), and an invitation to give a public talk titled the "Professor R. Narasimhan Memorial Lecture" on the topic for which the recipient is being recognized. In cases wherein the recipient cannot attend the conference in person, arrangements will be made for the recipient to present the lecture through video conference.
6. The award will cover the expenses of the recipient to travel to the chosen conference in India and present the talk.
I wish to share a few thoughts here:
Obviously, only established international conferences with high standards will qualify for these awards. Peer reviewing and published proceedings are essential.
Prof R K Shyamasundar, TIFR, or I can offer any clarifications required.
Srinivasan Ramani
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Labels: Awards, Computer Science, Computer Technology, international conferences in India, Invited Talks, Memorial lectures, Prof R Narasimhan, TIFR
Saturday, March 22, 2014
The need to invent Secondary Data Recorders for Aircraft
The tragic incident of the Malaysian Airlines MH370 has triggered a worldwide question. Why don't we have better data and cockpit voice recorders? Rep. David Price, D-N.C., is reported to have said that the 9/11 Commission recommended after the terrorist hijackings in 2001 that planes carry ejectable "black boxes" to make them easier to find. Visit
http://www.usatoday.com/story/news/nation/2014/03/12/ejectable-recorders-plane-crash-data-voice-black-boxes/6338397/
It is not very easy to design an electable data recorder. I wish to stimulate a number of student inventors/designers to think about this challenge with this blog post, by discussing a number of issues involved.
The first question is about the conditions that should trigger ejection of the recorder. In a military aircraft, this could be when the pilot bails out using an ejection seat. Not in a civilian aircraft. Actual impact, particularly over water, might be too late a moment for the data recorder to eject; it might sucked deep into the water with the falling structures and get trapped under water. A moment of high deceleration might indicate breaking up of the aircraft in mid-air. An impact will also cause a high level of deceleration.
Innovation requires trying out a variety of designs, without incurring a prohibitive cost. Integration of the device with the aircraft's systems will make these trials process very expensive. So, it might be worth trying out an externally mounted device not integrated with the avionics of the aircraft. If this prevents cockpit voice recording, one can perhaps do without it to start with. Alternatively, one could try and have the cockpit voice signal sent to the recorder securely over an encrypted WiFi like transmission.
A possible option is that of a device that clings to the external surface of a plane and can fall off after ejecting, to float if it falls into a water body, and sends wireless signals irrespective of where it lands.
How would a device cling to the exterior of a plane when it has air flowing over it at a high speed? One option would be to use the power of the air rushing past the shell of the device to make the device cling tighter to the aircraft. A pitot tube mechanism could create a low pressure area inside the shell, making it cling tightly to the aircraft's surface. Plastic bolts or a magnetic device could provide for the primary attachment to the aircraft, with the partial vacuum created by the moving air providing an additional mechanism to bind the device to the aircraft. Ejecting the device would involve opening a valve that depletes the vacuum. It might also require a mechanical device that cuts or breaks the plastic bolt when necessary.
An external device can easily measure altitude as indicated by air pressure, as well as airspeed. Electronic accelerometers could add data about acceleration in three dimensions, and GPS coordinates as a function of time.
To save battery life, the ejected device may send wireless signals relatively infrequently. It could be designed to respond to polling signals sent by search aircraft or ships, like a transponder. The device might also have built-in solar cells to keep sending signals over weeks or months.
Given all the above-mentioned possibilities, it seems the time is ripe to launch several design projects. A design competition, with an attractive price, may be a good idea.
Having an aircraft sending data more or less continuously is not a bad solution. However, constant search for alternative solutions is necessary till all aircraft are fitted with affordable data recording devices.
Lastly, automobiles can also benefit from data recorders, even if they are not ejectable. Perhaps insurance companies should drive their use by offering lower insurance costs to cars fitted with working and regularly monitored data recorders. Automobile data recorders would have a moderating effect on drivers and make them less risk-prone.
Srinivasan Ramani
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Labels: Aircraft data recorders, automobile data recorders, cockpit voice signal, ejectable, external, pitot tube
Thursday, March 13, 2014
Richard E. Merwin Student Scholarship
http://www.computer.org/portal/web/studentactivities/merwin?lf1=417765105e920816014288d18427682
Deadline for application is April 30, 2014.
Srinivasan Ramani
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Labels: IEEE, Richard E. Merwin, Student Scholarship
Sunday, February 23, 2014
Aids for the Visually Handicapped
http://www.sersc.org/journals/IJDRBC/vol2/1.pdf
Do we have entrepreneurs carefully watching for patents that expire? Do they consider manufacture and sale of devices covered by such patents? Do potential entrepreneurs among students look for these opportunities? No one stops an entrepreneur from innovating and inventing. One can always patent a new invention which vastly improves an old device covered by an expired patent. This gives a double strength – a tried and tested idea no longer covered by a patent and a new idea of one’s own covered by a new patent.
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Labels: expired patents, simple inventions, ultrasonic torch, visual aids, visually challenged
Saturday, January 04, 2014
Cellular Technology cannot help Disaster Victims Outside a Cell Phone Tower’s Reach
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Sunday, June 23, 2013
A Parallel System for Defensive Publication
Srinivasan Ramani
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Labels: invention, open invention, patent
Wednesday, May 29, 2013
More on the massive asteroid 1998 QE2 - it is estimated to weigh about 40 Billion tons
You may be able to see it through a telescope
Friday night, May 31 2013
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Sunday, May 26, 2013
Massive asteroid 1998 QE2 will make a close pass on May 31 2013
Measuring the Asteroid's Mass: Let me ask my friends in physics research: do you think you can rig up a way of measuring the gravitational effect of such a mass passing at that distance? That is, can you measure a change of about ten parts in a million in gravitational acceleration in your lab? What would be the extent of low frequency gravitational noise in your lab?
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Saturday, March 23, 2013
Find a good Earth Trojan and Build an Observatory on it!
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Friday, March 15, 2013
Web-mining Project: Locate danger spots on a map
I suspected that this compilation is easier for Google to do than for every TV channel. So, I searched for “topic Google” and found some information about the cool feature named “topics”. (Yes, you can make a topic out of your heart-throb!).
To make the web “more intelligent”, we will need good techniques to mine its content semantically and present information in a multi-media form. So, I propose a student project which will mine the web daily for information on locations (circular areas on a map, about 100 M in diameter characterized by their latitudes, longitudes and names) where fatal accidents occur. Since news text on the web uses a variety of ways of conveying location information, you will need a variety of techniques to figure out Lat-Long info, necessary for locating the spot on a map satisfactorily. You might need to process multiple sources of information on a single accident and avoid reporting it as multiple accidents. Multiple sources may also make it easier to figure out the location and time of an event more accurately. Forget getting 100% information – there is no such thing in the real world!
Now mark the spots on a map. You might want to remove a spot from the map when a year goes by without another fatal accident there.
From a technical point of view this should be fun to work on. Hopefully such a map would be seen once in a while by traffic police officers who might be tempted to visit these spots and report on the map what they intend to do about reducing fatalities at the place visited.
India, unfortunately seems to have a highest number of fatalities on the road (about 140,000 per year) in the world. China has less than half of this; USA has less than 1/4th of Indian fatalities, despite having a lot more vehicles. We would be a stupid lot, if we do not reduce the number of yearly deaths due to accidents by about 50% over the next ten years.
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Labels: accidents map, India, road accidents
Tuesday, March 05, 2013
Virtual Cars for Everyone
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Labels: automobile, car rental, job creation, mobile applications, productivity, Transport
Friday, February 15, 2013
Meteorite fall and the close fly-by of Asteroid DA14 - A coincidence?
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Wednesday, February 13, 2013
Pushing an asteroid off its course a little bit to avoid a collision!
In one of my earlier posts I had referred to the idea of painting an asteroid white so that solar radiation would gently push it away from the sun. My main objection to that is - it would require pretty long notice. The technique cannot change the asteroid's orbit fast enough. Asteroid 2012_DA14 was discovered less than 12 months before its nearest approach. There was no time for the paint job to work!
So, what are the other options? Visit http://news.discovery.com/space/asteroids-meteors-meteorites/top-10-asteroid-deflection-130130.htm for some light reading about ten methods including the paint job. The most attractive one seems to be to hit the asteroid gently with a rocket weighing say 10 tons and hoping that the asteroid does not break up into pieces. The probability that it does break up into big enough pieces threatening the earth could be low. In that case, we would just need to use another ten-ton rocket! Perhaps a few! This might be a lot more practical than solutions like shining a mirror at the asteroid!
We hear on and off about big powers destroying some of their own missiles as one step towards disarmament. Perhaps, they can modify and set apart a hundred such missiles each to fight common enemies of humanity, in the form of asteroids on possible collision courses with the earth. Such, missiles are available at practically no cost to major powers.
One good thing! The horrible, original, payload fitted to these missiles would not be needed for their new mission.
Srinivasan Ramani
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Tuesday, February 12, 2013
Plans for visual observation of Asteroid 2012 DA14
Well! I decided to look up details to get more information to help me do visual observation of the Asteroid DA14's flyby the coming Friday night - Saturday morning. Midnight of Feb 15, 2013 to 5 AM of Feb 16, 2013 is the best time, if you wish to see it reasonably well above the horizon, for locations near Bangalore. Hindu Business Line gave me some hope of a memorable spectacle, saying
‘Close’ asteroid may miss Earth, but could hit telecom satellites
I know that telecom satellites cost a lot of money, but I don't mind if the asteroid hits an old satellite nearing the end of its design life on its way-in! Interestingly, telecom satellites need fuel to stay at their allocated sites in geosynchronous orbit. So, in something like seven years, most satellites would have exhausted their fuel. One of them might as well give me my spectacle! If it is hit as the asteroid is coming in, the debris from the collision would have a chance of hitting the earth's atmosphere to give us fireworks.
With renewed hope, I did a web search to get myself a sky map showing the line representing the expected path of the asteroid against the backdrop of constellations and stars. One very useful website turned out to be
http://www.slate.com/blogs/bad_astronomy/2013/02/11/asteroid_2012_da14_space_rock_will_miss_the_earth_by_17_000_miles.html
It gave me useful information, and pointed me to the site
http://www.heavens-above.com/
Text under the heading "configuration" on the page mentioned allowed me to enter details of my location, Bangalore, (Latitude 12.98, Longitude 77.78 and Altitude 920 Meters. You can get your own coordinates: google for latitude longitude YOURCITY). After I entered my location details, it needed just one more click to ask for the map, and I got the following map showing exactly what I wanted.
http://www.heavens-above.com/2012da14.aspx?lat=13&lng=77.6&loc=Bangalore&alt=900&tz=UCTm6
It seems that you will get about 4.5 hours to see it (00:30 Hours to 05:00 Hours) if you are within 300 miles of Bangalore. However, the asteroid could appear pretty dim after 3 AM, since the point of nearest approach is at about 1 AM, Saturday's early morning.
Best of luck. Just make sure that you get to a place with very few artificial lights around. Carry a pair of good binoculars, along with a torch! Carry a sheet to spread on the ground. You would need to be flat on your back if you are not going to sprain your neck! Best wishes for a good sighting. You are unlikely to see DA14 again! Earth's gravity is modifying the asteroid's orbit pretty seriously!
Srinivasan Ramani
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Sunday, February 10, 2013
A Madrasi discovers a Minor Planet!
Pogson, N. R. (1866), Minor Planet (87) Sylvia, Monthly Notices of the Royal Astronomical Society, Vol. 26, p. 311 (June 1866).
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Friday, February 08, 2013
NASA and Painting Asteroids
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Thursday, February 07, 2013
Visit of the asteroid 2012_DA14: Any chance of a spectacular display?
www.wikipedia.org/wiki/2012_DA14
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Wednesday, October 31, 2012
Sandy and Neelam: The need for a Worldwide Tropical Storm index
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Labels: awareness, climate change, Global Warming, Neelam, Sandy, storm activity index, tropical storm activity
Tuesday, September 18, 2012
Apps that make low-end cell phones valuable
The site focuses on common English words found in every science textbook. These are not “scientific” words, but words that every English-medium student of science has to know. The idea is that students can take a new test every month and know where they stand. Testing is an important part of teaching, but only a small part. Ideally the student should take the help of a relative or friend to discuss questions. The student should read English language books outside the syllabus – ideally story books that are very interesting. They should learn to use a dictionary well and frequently.
The following web pages describe how this service can be accessed over SMS from within India
http://www.hydrusworld.org/Tests over SMS.html
and over Instant Messaging from anywhere on the Web
http://www.hydrusworld.org/Tests over IM.html
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Labels: Apps, India, language learning, low-end cell phones, SMS, test your English, texting