Arun Waves

July 27, 2016

Neural Networks – scary good :-)

For the last year or so, there has been a steady increase in chatter about Artificial Intelligence/Machine Learning/Neural Network when it comes to anything online. After a brief stint with Fuzzy Logic during my undergrad, I never got an opportunity to dig into this topic further, other than keeping myself up to date with current events or milestones like the advent of IBM Watson (Jeopardy), Siri/language processing, self driving cars/various DARPA challenges, DeepBlue (chess), DeepMind (AlphaGo) etc. Almost by serendipity, I stumbled onto a Coursera course, Machine Learning by Andrew Ng (of Standford/DeepMind/Baidu fame) and found that my maths skills from my PhD in Quantum Mechanics fits right into this magical world of Neural Networks and Machine Learning. Cool, I dove right into the ocean of Deep Learning, layers,  gradients, features etc🙂

Here is a ‘small’ result from the coding exercises of Andrew Ng’s Machine Learning course in Coursera. The task is to code a system that can recognize hand written single digit numbers and I am elated to report that Neural Networks is ‘scary good’ at it. What does ‘scary good’ mean? I did not have to explicitly code how numbers look, meaning I need not know Arabic numerals at all to develop a system that can recognize it from a non-standard medium (hand scribbled). Check out the results in GIF format below (Note: Yann LeCun’s LeNet5 has done this and more, way back in 1998);

Neural Network

November 8, 2015

Big Data Analysis

Filed under: Data Analysis — Arun @ 1:36 am
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My first attempt at Big Data Analysis!!! Disclaimer: it is ‘Big’ for what I have done so far, not ‘Big’ compared to the industry standards. Although the data had only 30,000 rows with 4 columns, yet it exposed me to certain caveats that one needs to watch for while doing Data Analysis, for example the importance of prepping the data, the need to understand the data before making any conclusions, the risks of applying inappropriate statistical methods like finding the average for a distribution with two peaks, etc.

The data is a WhatsApp chat archive of about 11 months from an active group. Excel was used for the analysis with the exception of the Word Cloud for which I used an online tool . This analysis also showed the importance of quantitative evidence and empirical data over what you feel or ‘think’, many of my assumptions were shattered🙂

Here is what I found, enjoy (feel free to click the images to see a bigger version):

  1. Total number of messages over a period of 11 months (Nov 2014 to Sept 2015): 29,752 messages
  2. Unique number of members: 35
  3. Total number of media (pics, video, audio) files: 3,079 files
  4. Approximately every 10th msg is a pic/video/audio file
  5. People have typed messages of length (no. of characters) all the way from 1 to 256. The shortest message that no one has typed is 257 characters long. After that point the distribution starts to falter.

6. Top message contributor …………. Flavin, the most talkative person in the group, followed by Mahalakshmi, Sriroopa.

Top Contributors

Top Contributors

7. Top media contributor ……… Mahalakshmi loves to forward pics/videos, followed by SK, Mahadevan.Media Contributors

8. Message distribution over the span of a week: surprizeeeeee, they are evenly distributed over all the 7 days of the week with slight reduction over the weekend🙂 A very consistent group.

Messages per Day of the Week

9. What is the peak traffic time and when is the lull? X-axis is US time, the labels are in India time. People love to chat around 9:30 pm India time!! Why is there a dip at 12:30pm India time?

Messages per hr of the day

10. All top contributors, except Flavin, don’t care if it is a weekday or the weekend, they just type away but Flavin throttles down over the weekend. Top contributors performance over the span of a week

11. My favorite, the Word Cloud, a visual representation of word usage, the bigger the word, the more frequently it is used. Our group loves exchanging pleasantries ‘good morning friends’ and for some reason the word ‘Flavin’. Note: this Word Cloud excludes common words like ‘the’, ‘a’, ‘and’, ‘is’ etc.

Word Cloud

12. All inclusive list of frequently used words without any exclusions. ‘Flavin’ is the only name that makes it into this list. Why does everyone mention him by name?

Most commonly used words

13. We also love our emoticons. Ignore the 16th bar.

Message sizes

14. Longest message award goes to ……………….. Mahadevan. How long you ask? 23,412 characters, one giant forwarded msg on 24th Nov, 2014. Do click the image to see it in its full glory.

Message length distribution

<<< THE END >>>

It took me about 20 hrs to do this analysis, for any more data analysis please be ready to pay me😎

September 25, 2012

Star charts

Filed under: Astronomy — Arun @ 11:36 pm

You can either give your own names to the stars and spin a story about a group of apparently nearby ones or use the star charts to find out the names that the ancestors gave them!! With the laptops/tablets/smart phones becoming ubiquitous, here are two electronic star charts that I use;

  1. – needs internet connection for the free version and sometimes the button under “Interactive night sky map” (top left) does not show up since it needs JAVA to be enabled, otherwise it is my favorite tool. Allows you to choose location and time/date. You can click your way into the past of future, on a minute by minute basis or even on a year by year basis. You can turn things on or off, like constellation names, outlines, grid etc. You can search using star/galaxy/cluster names, simply amazing🙂
  2. – When being online (on a laptop or tablet) is not feasible then I use Stellarium that can be downloaded for free. Its graphics and interface is different from the AstroViewer but does its job. Caution: someone not comfortable with computers/websites/apps may find it a little challenging in the beginning.

And when all the fancy electronics fails because of low battery, a red light and a paper chart or book will save the day!! I use ‘Skywatching’ by David H. Levy – simple but provides lot of relevant information in an intuitive manner. It has general info chapters, sky charts, and individual constellation descriptions with hints on what can be seen with naked eye, binoculars, and telescopes.


June 8, 2012

Venus transit – June 5th 2012

This has been a good year for amateur solar astronomy folks – a solar eclipse and Venus transit in the same year🙂 And for someone in Phoenix, we are weather proofed he he he – no clouds to worry about.

After the solar eclipse experience I felt I could do better, not just pics but something that gives a feeling of being there, so I decided to do a time-lapse video for Venus transit. The trusted Windows Movie Maker, in its new form – Windows Live Movie Maker did a good job; it took some time but here is the result……

PS: The yellow Sun pics were taken by Canon DSLR through solar glass filter. The almost black and white pics (magnified pics) were taken by a SONY point ‘n shoot with afocal coupling through my 4.5″ reflector with Baader solar filter sheet. See solar experience post for pics.

May 20, 2012

Solar Eclipse May 20th 2012

Filed under: Astronomy — Arun @ 10:25 am
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This is one of the few moments when you are glad you live in a desert!! While the people who were in the path of the annular eclipse were fretting over the cloud cover, we the desert people enjoyed a wonderful eclipse even though we saw only 88% eclipse.

I got a Baader solar filter sheet, built my own filter holder for my 4.5″ reflector and organized my 3rd star party. Enjoy the pics…………

December 27, 2011

Science communicator – Professor Brian Cox

Filed under: Science — Arun @ 10:10 pm
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Few days ago I came across Professor Brian Cox’s lecture on YouTube – A Night with the Stars [BBC]. I have followed other science communicators like Neil deGrasse Tyson and Jim Al-Khalili, and I have added Brian to the list of people whose talk I shall never miss. Each one of them has a different personality that brings a new style of persuasion. With Neil it is his sheer power and quick comments & replies, with Jim it is all about the deep and revered sense of curiosity & wonder, and with Brian it is his charisma and definitely the boyish demeanor (and of course the British accent :-)).

So without much delay here is what I found ………….

November 26, 2011

Sierpinski triangle

Filed under: code,Processing,sketch — Arun @ 12:21 am
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Note: It would help to know a little bit about fractals to appreciate this post.

Ever wanted to create a fractal? For those who are not aware of fractals think of it as a special figure that retains its form no matter how much zoomed in you are, a property known as self-similarity. Don’t believe me, check out this and this.

Quite mind boggling in itself, now if someone told you that this can be generated by a random algorithm!! I had to check it out for myself, so I used the familiar and easy to use Processing programming language to test it. You can read about the algorithm here, it basically involves a moving point whose direction is determined by rolling a dice. The point moves half distance towards one of the three vertices of a triangle When the dice has been rolled a sufficient number of times, you can see the Sierpinski Triangle. In this case the main triangle can be broken into 3 triangles which look like the original triangle and sub-triangle can be broken into 3 more similar triangles. See for yourself ……………..

Here are some screen shots;

September 15, 2011

Science communicator – Professor Jim Al-Khalili

Filed under: Science — Arun @ 9:48 pm
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I have never seen a documentary quiet like this where I learned so much, not only technically but also about the nature of research. I have been in research for a long time and was aware of the typical challenges but never had perspective. We all (graduate students) knew that getting funding was most difficult, there is always a sense of urgency to get results and publish, any new result would be almost certainly contested etc. But I never truly realized that it has always been the case. For example, the story of the first element to be chemically isolated – the guy who did it had to pretty much boil lots of urine using his wife’s fortune! He eventually succeeded but his coffers were empty by then and he had to sell his knowledge at a very low price. Another interesting story, the race to liquify Hydrogen – two researchers had to race each other putting everything of value at stake and of course only one won. The history of science is replete with examples of people pursuing the unknown (sometimes it is just challenging the known) while putting their regular life and stability in harms way.

Also, the presenter, Prof. Jim Al-Khalili, has done an exceptional job at projecting the sense of amazement, curiosity and wonder that comes with science. Here are some of his documentaries, each one is a masterpiece🙂 Kudos to BBC for such a great TV series. Some of these videos can be found in YouTube or Google Videos. They may also be a great gift for school students or anyone interested in such topics. I recommend it to any school or university student who is looking for resolution.

Chemistry: A Volatile History (multi-part series) (sorry couldn’t find the link to part 1/5)

Atom (multi-part series)

While you are at it, do also check out The Secret Life of Chaos.

August 2, 2011

Nice infographic about Solar System and distances involved

Filed under: Astronomy — Arun @ 9:19 pm
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I found this great infographic which gives a mind boggling insight into the distances involved just with in our Solar System. Similar infographics are available in abundance but this one has a new twist in that it shows the distance traveled by light in time scales that we use in our daily lives. The original link of the articles is here. This infographic is a long one so I am posting couple of screenshots to entice you🙂 You can find the infographic below the screenshots.

PS: The below picture of the Milky Way is an artist’s rendering and not an actual image. To do this we will have to send a probe outside the Milky Way (as of 2011, we have barely managed to send 2 probes out of the Solar System). However this picture is not just wild imagination. We have photographed other galaxies and we have studied (& photographed) our own Milky Way from inside and this picture is a combination of all that knowledge.

Ah … the (below) picture that shows the size of planets and Sun to scale. No matter how often I see this, it always amazes me. All the Sun has to do is send out a little burp and we will simply cease to exist!!

And here is the infographic, you may begin your journey …………… Live Long and Prosper
Our solar system to scale from the sun to the most recently discovered dwarf planet Eris in astronomical units.
Source All about our solar system, outer space and exploration

July 15, 2011

Encyclopedia of Astronomy by SAO – COSMOS

Filed under: Astronomy — Arun @ 6:21 pm
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COSMOS – The SAO Encyclopedia of Astronomy” is a great collection of definitions and explanations of astronomy related terms. Wait, it gets better, it is written by research astronomers!! so you get information “directly from the horse’s mouth” which is always the most authentic source.

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