Category: Note

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I was at the the beach this past week, and one of the days we got a chance to do some star gazing. It was a new moon, and the sky was full of stars (and some satellites). I wanted to take a picture to capture the majesty. In the past, I’ve tried to take pictures of the stars and have failed, but recently I’ve been getting better at manual mode on my Galaxy S9, so I tried again. This time it worked! Here was the result:

The night sky at the Jersey Shore.

There were a couple of settings that made the picture possible. With manual mode, I set the focus to infinity so the stars would be resolved. I fully opened the aperture to let in more light, and I set the phone down on a box so that it did not move. When it was taking the picture, the phone automatically determined the exposure time which ended up being around 10 seconds. I also raised the ISO level, but that may not have been the best idea because it can introduce noise. If you’re interested in learning more, there are many guides available, I came across this one today and found it to be informative.

Good luck with your astrophotography! Here’s a picture of the big dipper to close:

The big dipper.

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I keep on going back to the same sites for updates about coronavirus. Here are the ones that I like:

Update 5/5/2020

Also I like reviewing the IMHE predictions.

Update 5/26/2020

Update 7/29/2020

Nice dashboard of covid reproduction rates https://rt.live/

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I have decided that it is time for me to leave Facebook. It has a negative influence on me, my friends, and our larger society. This decision has not been easy since Facebook provides many useful services and most importantly lets me connect with so many of you. I want to explain some of the top reasons, and to share with you where I am going.

Facebook has lost my trust by:

  • Encouraging addictive behavior (infinite scrolls among other things).
  • Sharing our private information with whoever will buy it.
  • Not playing nicely with other applications. Instead of including the contents of a post in an email notification, Facebook forces you to pull up Facebook (and risk getting sucked into the news feed time sink).
  • Contributing to the fragmentation of our society by selecting posts full of outrage and provocation for our news feeds.

Facebook is “free”, but we pay in so many ways. I’m not buying it anymore. And I’m taking my data with me.

Before I go, I want to thank you, Facebook, for helping me to remember people’s names, for providing a way to share my thoughts and pictures, for giving me a sense of who got married or had a baby or took a cool vacation. 

My new home on the internet will be my website davidbruffner.com. Feel free to visit and say hi. I write little posts from time to time about what I am interested in. I’m still sorting out whether to spend time on other social networks. My favorite ways to connect are talking on the phone and meeting in person.

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My colleague, Jarek Blusewicz, recently told me about autonomous RC cars and how they can be a fun project for playing around with AI and robotics. I didn’t know that autonomous RC cars were a thing, but it turns out that lots of individuals and teams are playing around with them, and doing awesome work. I found a video of a RC car autonomously drifting around in controlled circles. It is amazing to watch, especially when the camera zooms in on the front wheels steering back and forth to maintain the drift as the car slides over the surface. It looks like a professional driver, but the car is completely controlled by a computer.

Researchers at Georgia Tech created an autonomous rally RC car for “aggressive off-road driving”. They really mean aggressive! The car hits a turn at almost full speed and then power slides through it while kicking up clouds of dirt. Here’s a picture of their AutoRally car in action.

autorally_platform_header
Credit: AutoRally: An Open Platform for Aggressive Autonomous Driving. Brian Goldfain, Paul Drews, Changxi You, Matthew Barulic, Orlin Velev, Panagiotis Tsiotras, James M. Rehg. Control Systems Magazine (CSM), 2019.

The best part about the Georgia Tech work is that it is all open source, with a site on Github including detailed instructions about how to build the car (it wouldn’t be cheap, but could be great for a group or organization).

The AutoRally car is controlled with a reinforcement learning algorithm, which I have been finding to be widespread for controlling robots in general. It’s something that I would like to learn more about and play with.

 

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Since finishing grad school, I have been diving from physics into coding. It turns out that it probably is all the same thing at the end of the day! I came across a paper that discovered an exact mapping between the renormalization group, a central concept in modern physics, and deep learning, the latest and greatest machine learning algorithm. It’s crazy but makes sense. Both the physics idea and deep learning rely on looking at a system on a succession of different levels. This high level view of a system helps you to see the big picture. That is useful for self-driving cars and for finding phase transitions in condensed matter systems.

I am excited about the potential of machine learning and AI. It’s cool to think that my various seemingly different interests, could turn out to overlap in productive ways.

What if there are other hidden connections between totally different fields?

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I’ve greatly benefited from people who have generously shared ideas by writing blogs. It is staggering how much knowledge is out there. I want to do my part to contribute. I aim to write up when I learn how to use a technology or learn something interesting.

Writing is a great way to develop ideas. So I’m sure that it will be useful to me too!

Coming soon!