Sci: Pulse Jet Jar

1/26/2013

Drilled hole in top of jar.
Fuel: Heet antifreeze.
Placed in bowl of snow/water for cooling.
Shattered one jar.
Accompanied by Ren.

Obs: Screw Theory and Your Shower Drain

1/26/2013

Leonard: What would you be if you were attached to another object by an inclined plane, wrapped helically around an axis? 
Sheldon: Screwed.

-Big Bang Theory

Last week in my Kinematics, Dynamics, and Controls class, we began to quantify screw motions - translating while rotating. 

These motions are the vortexes that we see when we flush a toilet, or when we remove the plug after a bath. The rotational forces can be attributed to the coriolis effect, while the translation forces are due to gravity. 

This reminds me of the whirlpool science project done by taping together two soda bottles and inducing a vortex by spinning it circularly:

Update: this is probably not true. The Coriolis forces are negligible compared to the geometry of the toilet/sink. But they're there!

Ponder: Irrational Numbers in Irrational Bases

1/26/2013

Irrational numbers are rational in irrational bases.
Example: π₁₀ = 10_π

Obs: Gyroscopes in Nature

1/26/2013

I was first introduced to the connection between linear algebra and gyroscopes in Robot Kinematics and Dynamics class, when Dave the TA mentioned gimbal lock. A gimbal is a mechanical device that functions as a gyroscope, with each axis describing an Euler angle. The problem with Euler angles is singular representations, as seen below, where a degree of freedom can be lost. A linear algebra interpretation is two Euler angle mappings to one orientation, meaning there is no unique inverse (and thus a singularity). 

  ------->  

This phenomenon is really dangerous in planes because the pilot can lose information about his orientation, like in Apollo 11 where the spaceship did not have any prevention measures in place for gimbal lock. Fortunately, the brilliant astronauts-turned-astronomers were able to re-calibrate their gimbals using the stars as reference. 

Gimbal lock can be resolved using two gimbals offset in both position and orientation, in which the number of gimbal lock cases should be reduced dramatically, or by adding a fourth dimension to the gimbal.

---

Recently, I've begun to notice the ubiquity of gyroscopes in nature. In Metin's bio-inspired robotics, I learned about mosquito halteres, and two days ago we talked about the vestibular system in Richard's psychology of music class. 

A haltere is an organ in mosquitoes that functions as a gyroscope, shown below:

I don't know how accurate this entomological sketch is, but I would imagine that the offset in the halteres is more than just a coincidence - it's probably to prevent gimbal lock! I would suspect that there's also an offset in the haltere orientation, as well as an offset in position in the axis going into this blog. 

Humans also have built-in gyroscopes - the anterior canal, posterior canal, and horizontal canal:

You can kind of see it in the picture - the canals seem to form an orthogonal basis.

I bet that the sets of canals are slightly offset in angle/position in both ears to avoid gimbal lock, just like in planes and mosquitoes, and that balancing issues in people stem from problems with the orientation and position of their three canals! So, I hypothesize that there may exist a surgery that could repair equilibrioception in people. 

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This observation really sheds light for me on the value of interdisciplinary information use. 

Pictures from wikipedia.

Lifehack: Cleaning Up My File Directory

1/8/2013

I finally got around to cleaning my computer's file directory. It was a huge mess, I basically threw everything onto the desktop. I've decided to group files into the following categories:

• Tools
• Exercise
• Resume
• Projects
• Books Currently Reading
• Website
• Notes
• Travel
• Sheet Music
• any current projects

I also had a bad habit of hoarding tabs, but finally realized that information overload is not only bad for my mind, it's unfeasible to read through such a large subset of the internet in reasonable time. Although I have gotten better this past semester, as part of my New Year's resolutions, I plan to stop saving up so many tabs once and for all. More on resolutions in a later post. 

Sustainable House Ideas

1/8/2013

This post will be used to keep track of ideas I have for my house. In the future, I'd like to have the following:

• library
• electronics lab bench
• plant greenhouse
• metal/wood workshop
• solar panels on roof

Sci: Matlab Carriage Return for Single Line Printing

1/7/2013

For smoother feedback in the user interface while loading files or loading something, you might want to overwrite your loading or status bar instead of printing it on a new line. Unfortunately, because of the linearity of stdio in most computers, there's no simple print command (that I know of...) that will do this.

In MATLAB, instead of carriage return, we actually use \b to delete previously printed characters outputted by fprintf. However, in python, you should be able to use \r to obtain the same effect.

Download the demo.

Food: Fontina Grill

12/29/2012

Located in Rockville, Maryland. 

Served from 11a to 130p, the lunch buffet menu included a light pizza, cheese ravioli, meatballs, and steak/mushroom. My favorite was the all-you-can-eat mussels. Would definitely go again. 

http://www.fontinagrille.com/lunch.html

General: Learning to Learn

12/22/2012

As opposed to traditional methods of learning, such as lecture, homework, and projects, I've always had trouble learning via textbook. I am stubborn about reading every detail in the book, down to the last word, but often I will either lose focus mid-paragraph or fall asleep. Something has to change.

During this past finals week, I came across an article written by Cal Newport on "ultra learning" (oh, the irony). I was immediately enticed by the potential to master linear algebra in ten days. I realized my obsession with details was impractical; after a few books, there's essentially an infinite number of words, of which no one has the time to read in their entirety. I need to find the balance between understanding the big picture and being able to crank through the implementation (so, grinding through practice problems is not the solution).

This winter break, I decided to try and apply the ultra-learning techniques to Udacity's Artificial Intelligence course, with a focus on understanding the Extended Kalman Filter and the Particle Filter. 

Here are my favorite online-education websites:
Udacity
Coursera
edX
TopCoder
CodeForces

General: My Blog's Purpose

12/21/2012

I'm planning to use this blog for writing, food/recipes/restaurants, exercise, and project updates.

Some of my friends' sites:
http://nolanhergert.com/doku.php
http://www.chrisharrison.net/ <- inspiration for site layout and calendar!
http://christopherhsing.com/
http://robo-nut.blogspot.com/

Some sites I enjoy frequenting:
http://hackaday.com/
http://www.youtube.com/user/eevblog
http://lifehacker.com/