Image from Schleifernaut

Hey there!  Just another quick reminder that you should take a look at (and subscribe to!) my new blog: Schleifernaut.  And here’s the fist post: Gangload Your Regulator.

Thanks!

It’s called Schleifernaut!  I have the first post up already, but regular posting is not planned to begin until April 2nd.  In the meantime, feel free to check it out.

I want to thank you all so much for reading The Grok Project.  I hope you’ll try reading my new blog as it gets underway!

Thanks again!

Image via Wikipedia

Remember when I posted Rotarium? (http://grokproject.net/2010/08/14/rotarium/)

Well, that was inspired by a visit to the lab where I work by Neil deGrasse Tyson!  They shot a segment at the lab about artificial gravity to appear on NOVA ScienceNOW.  They took a lot of video of me operating the rotating room, so chances are you can see me there.

WHEN: Wednesday, January 19th, 2011

WHERE: PBS (Channel 2 in Boston)

Either way, it will (hopefully) be a great segment about some of the work we do at the lab, so you should check it out! If you don’t live in the Boston area, check your listings as it may air at a different time.  The segment will be part of a larger episode, the general topic of which is unclear to me, at present.

Image via Wikipedia

Greetings all!  I know, I know.  I fail at blogging.  But the status of the Grok Project has not changed.  Expect to see sporadic posting … when you least expect it!

In the meantime, some of you may be able to experience The Grok Project LIVE!  It’s another party at Arisia!  Last year’s was so much fun that I want to do it again, only even better…

Saturday, January 15th, 5PM – Midnight

This party will feature (great) FOOD, (non-alcoholic) DRINK, … and (mad) SCIENCE! “Crash course” lectures will be given in short bursts periodically throughout the evening on topics relating to HUMAN SPACE FLIGHT. A broad range of topics will be covered, with an emphasis on the physics of space flight and spacecraft engineering. The time between talks will be open for discussion and awkward, nerdy socializing. A pamphlet including the Schedule of Geekery will be circulated at Arisia prior to the party.

There will also be space mad libs and a space trivia game – with PRIZES!

Preview of Topics:
1. Modeling the Heavens & Conception of Space Flight
2. Propeller, Jet, & Rocket Propulsion
3. Launch, Orbit, & Reentry
4. Control Systems
5. Energy Sources, Storage, & Delivery
6. Space Physiology & Life Support
7. To the Moon!
8. Hazards of Space Flight
9. Navigation Beyond the Moon
10. The Future Soon

I might also record videos of the lectures at the party, spruce them up, and post them here.  Depending on how well it goes.  ;-)

Thank you for reading!

Image by Garry - www.visionandimagination.com via Flickr

Er … I mean … “I’m going on vacation!”  For a week, to be precise.

I plan to return with some new material for the Grok Project, but most of the time I’ll be hiding in the mountains.  I’ll tell you all about it (and show photos) when I get back!

Thanks for reading!

It is important, first, to recognize that these exercises are limited in their ability to simulate most aspects of a disability.  Still, they can be an important source of insight for people who do not have the disability in question.

The video in this post makes fun of my difficulty with some common tasks the first time I tried them with only one arm, but it’s meant to highlight advantages of having two arms that most of us take for granted.  Here are some of the things I had trouble with throughout the day:

• Manipulation tasks wherein one hand must work against an unstable object.  Example: buttoning my pants.  Without another hand to hold the fabric still, getting the button into the hole takes a lot more skill!
• Pushing objects together / pulling objects apart.  Example: getting the cap on and off of my deodorant.
• Reorienting held objects.  Example: holding a sheet of paper right-side-up.
• Donning & doffing clothes.
• Going through latching doors while carrying a bulky object.  Example: getting back into the lab with my lunch!  It almost ended up on the floor.
• Exercise.  Example: most exercises for pectoral muscles (most rely on balanced, symmetrical movement).
• Hand washing.  That’s one I hadn’t even thought about until the time came.
• Stabilization.  It turns out I’m quite used to using one arm to stabilize myself while the other arm is performing a task.
• Various tasks like removing lids from jars and climbing furniture/counters to reach things (I’m not a tall person).

While these tasks were difficult at first, it didn’t take long to go from awkward to competent (insomuch as I am ever not the former).  By the end of the day it had become clear to me that it wouldn’t take long for a person to adapt so that they could do a lot of things just as fast and reliably as with two hands.  That’s an important fact for non-amputees to recognize.  Framed another way: a person with one arm can be just as qualified for most jobs as a person with two.

Not that my adaptations didn’t look a little bit awkward.  They often involved using my teeth, leaning against walls and doors, or holding an object between my knees.  I can easily understand how an onlooker might assume I needed help.

Each time that happened, though, I declined for two reasons.  Firstly, it would have defeated the purpose of the exercise for me – I wanted to see what it was like to try all of these things for myself.  And that would not be unusual for an actual amputee.  They need to live their lives even when well-meaning offerers of aid are not around, so with each new challenge they encounter it’s in their best interest to learn how to do it on their own.  Secondly, I often knew what I was doing and simply didn’t need any help!  And that’s also usually the case with an amputee.  They’ve probably lived with this disability for long enough to know when they do or don’t need assistance.

I also noticed that I got a lot of stares and a lot of questions.  The people around me saw that my arm was bound rather than missing, so they were asking questions for a slightly different reason than they frequently do with amputees, but the effect was the same.  Annoyance.  It can be a difficult balance to strike between disabled and non-disabled people (and even sometimes among people with different disabilities)… When is it appropriate to discuss a disability?  It doesn’t seem to make sense to actively avoid it.  It’s nothing that either party should be ashamed of, and behaviors like avoiding the topic or averting one’s eyes would seem to imply that it is.  But at the same time, if a lot of people ask questions about the disability just as soon as curiosity strikes them (which many do), then it becomes disruptive to the life of the person with the disability.  It may be the first time you’ve asked that question today, but it might be the tenth time they’ve been asked it!

There is plenty of disagreement about what the best policy is, but I’ll tell you what makes the most sense to me.  In general, if you don’t have any other reason to talk to a person, then it is not appropriate to ask a question about their disability.  If, unprompted, someone has begun discussing his or her disability with you then they are implicitly telling you that they want to discuss it.  The gray areas are with people you already know.  I’d say if you are close enough to freely discuss other personal details, then a disability should not be taboo.  Just don’t obsess.  And in all cases, I would direct you to the vast number of informational resources on the internet about every type of disability under the sun.

As for offering help, I think one generally should not.  Just like everybody else, people with most types of disability can be expected to know their own capabilities and intentions.  They’ll ask for help when they need it.  But don’t become so self-concious about this that you confuse uninvited assistance with common courtesies such as holding doors for people.

Science & Technology

Accidental, malicious, and congenital amputations would have to be as old as humanity itself.  Intentional amputations to remove necrotic (dead) tissue have been performed since the neolithic era.  But it wasn’t until shortly before the start of the common era that surgical amputation of living tissue was performed.  This was made survivable by the discovery of ways to stop the bleeding: by ligation (e.g. applying a tourniquet) or by cauterization (e.g. applying fire, hot iron, hot oil, etc…).

So that’s the “how”, what about the “why”?  With severe limb traumas (and some other medical conditions), a substantial part of a limb may undergo necrosis (death of tissue).  With no active immune system, the dead tissue becomes an ideal place for a bacterial infection to take hold.  With that foothold, the infection can spread to the rest of the body and become fatal.  This condition is a type of gangrene.

Early medical practitioners would have noticed that the gangrenous tissue spreads from its original cite toward the center of the body and that death almost always follows.  One can easily see the motivation to try removing all of the gangrenous tissue by cutting through the proximal (closer to the center of the body) healthy tissue – to stop the gangrene from spreading any further.  As straight forward as the hypothesis here is, this is an early example of science!

Alright, so part or all of a limb is missing, either because we were born without it or it has been removed (surgically or otherwise).  Now what?  As I discovered during my exercise, humans can adapt very impressively just by modifying their behavior.  But what can technology do for us?

 

Image via Wikipedia

 

The earliest known record of prosthetic limbs, in any form, is dated between 3500 BCE and 1800 BCE.  A limb prosthesis is simply an artificial device secured onto the body where a limb would normally be and providing some aspect of normal limb function.  A low tech example would be a “peg leg”.  Modern limb prostheses have advanced tremendously, incorporating new materials and cutting edge engineering.  While these can be very helpful to amputees, many complain that the devices have become too complicated and that form is emphasized over function.  In many cases, arm/hand amputees will stop wearing their prosthesis because it’s actually easier to work directly with their stump.  Another common complaint is that the interface between the stump and the prosthesis becomes inflamed too easily.

But there are many simpler technologies that can make live easier for an amputee.  For instance, velcro!  Or using a hook as a hand prosthesis instead of something less useful made to look more like a natural hand.

There is a lot to be said about this topic, but I think this post is long enough as it is!  Stay tuned for more posts in this series.  If you have a disability and would be willing to let me interview you, please email me at ian@grokproject.net.

Thank you for reading!

SOURCES:

• http://en.wikipedia.org/wiki/Gangrene
• http://www.acpoc.org/library/1976_05_015.asp
• http://en.wikipedia.org/wiki/Amputation
• http://www.swisswuff.ch/tech/?p=150
• http://www.swisswuff.ch/tech/?p=344

I watched lecture #4. I read chapter 5.1-5.4 & 5.6-5.7 of Foundations of analog and Digital Electronic Circuits.

Summary

Due to an explosion of long hours at work and other such complications, I’ve been set back in this class.  But that’s what’s so great about an asynchronous course!  I can just pick up where I left off.

So … we’re on to the digital abstraction!  This is where the book and most of the lecture becomes tedious for me.  I learned absolutely nothing new.  I say most of the lecture because there was something in this lecture that made the whole rest of the lecture worth it: If you watch no other part of the video, at least skip directly to 46:33 to see the professor dance.  And to see a demonstration of digital circuitry’s resistance to corruption by electromagnetic noise, of course.

The first homework assignment is due at the recitation that’s supposed to happen between this lecture and the next.  I have it mostly done, but there are a few stragglers I have to give some more attention to.

Thank you for reading!

LINKS: Previous 6.002 post

Course citation: Agarwal, Anant, 6.002 Circuits and Electronics, Spring 2007. (Massachusetts Institute of Technology: MIT OpenCourseWare), http://ocw.mit.edu (Accessed 16 Sep, 2010). License: Creative Commons BY-NC-SA

Book citation: Agarwal, Anant, and Jeffrey H. Lang. Foundations of Analog and Digital Electronic Circuits. San Mateo, CA: Morgan Kaufmann Publishers, Elsevier, July 2005. ISBN: 9781558607354.

If you look to the right, you’ll see that there’s a new “Categories” section with a drop-down menu.  This will help you to filter out the posts your not interested in.  Here are some new URLs of interest…

• Only general posts (does not include posts about classes): http://grokproject.net/category/general/
  • RSS: feed://grokproject.net/category/general/feed/
• Only 6.002 posts: http://grokproject.net/category/classes/6-002/
  • RSS: feed://grokproject.net/category/classes/6-002/feed/
• Only class-related posts (will include other classes in the future): http://grokproject.net/category/classes/
  • RSS: feed://grokproject.net/category/classes/feed/

Image via Wikipedia

You can’t get this filtering through email subscriptions.  I recommend using RSS.  If you’ve never used it before, you may find it incredibly useful!  Practically every blog and online news source offers RSS feeds, so you can get all the content you’re interested in reading (or watching or listening to…) automatically gathered and organized in one place.  Here’s a link to help get you started: http://www.whatisrss.com/

Thanks for reading!

I could try to tell you all about how to use Blender, but that’s what documentation is for.  It will do a much better job of that than I would.  Furthermore, different 3D animation software packages all rely on the same underlying principles, but they tend to have wildly different user interfaces, so details won’t help you if you’re not using Blender.  Instead I’ll try to give you a general idea of what was involved in making Rotarium and focus on a few issues specific to this particular animation project.

The first concept I’ll introduce is the IPO curve.  IPO curves come into play after you’ve created a static 3D model and now you want to change some aspect(s) of the model over the course of time (i.e. animation).  A separate IPO curve can be created for every value that needs to change.  Some examples are position (x, y, & z), orientation (x, y, & z – rotation vector), color (red, green, & blue components), scale, position of a joint, etc….  There are MANY properties that can be controlled this way.

IPO curves to move the stick figure guy

The IPO curves appear on a plot with time as the X axis and value (e.g. angle in degrees) as the Y axis.  You manipulate the curves in a piecewise fashion by explicitly setting values at particular times (called keyframes) and telling Blender how to interpolate between the values.  Interpolation simply means that the values in between the ones you specify are computed automatically according to some rule.  Your basic options for that are Bezier, linear, and constant.  Bezier gives you a nice smooth curve – good if you want to avoid any sharp changes (note for calculus-folk: continuous second derivative with respect to time).  Linear interpolation connects the points with straight lines – good if you want a constant rate of change between your keyframes.  Constant interpolation makes it so the value changes only at your specified points – good if you want sudden, discontinuous changes such as teleportation.

IPO curves work great for many components of animation, but when it gets too complicated to be micromanaged there are other mechanisms you can turn to.  Blender lets you set constraints that, for example, keep one object in the same position and orientation relative to another object which may itself be moving.  Blender also has a physics engine that can use numerical methods to determine how water should pour, how balls should bounce, how cloth should blow in the wind, etc….  All you have to do is set the mechanical properties and constraints of the system.

Some of the Python code used in Rotarium

You might guess that this is how I simulated the physics of Rotarium, but it isn’t.  The actual motion of the objects in Rotarium is very simple: straight line and circular motion.  The physics engine would add unnecessary complication.  The tricky parts were getting the room and camera accelerations right and computing those force and velocity arrows in both reference frames.  The physics engine offers no solution to those problems, but fortunately, those things are all determined by equations that can be found with some algebra and calculus.  And Blender does offer a very powerful way to control animation when all else fails: it allows you to control everything in your scene through the Python programming language.

Python is a robust language with which you can implement practically any animations you want, if you know what you’re doing.  And it turns out, to my relief, that I did!

Blender's sequencer

Believe it or not, Blender is also decent video editing software!  I laid in all the live action videos and stills and did all the cross-fades and such right in Blender.  That feature is called the Sequencer.

If you’re interested in learning about computer animation from a professional, check out my cousin Jason’s blog shhLIFE! Jason was a senior animator and then an animation lead for Lord of the Rings with Weta Digital!  He also worked on numerous other movies such as Madagascar and he’s even written master classes on the topic of character rigging.

Thanks for reading!

I watched lecture #3. I read chapter 3.5-3.6 of Foundations of analog and Digital Electronic Circuits.

Summary

Now I’ve learned about circuit linearity and some helpful analysis techniques which apply specifically to linear circuits: superposition, Thevenin equivalences, and Norton equivalences.  Good stuff!  But the book keeps also going into how these things apply to circuits with dependent sources.  The reading assignments for the course had me skip over the section that introduces dependent sources.  I see that it will have me go back and read that later on, but in the meantime I’ve skimmed it, so I have at least some idea of what the book is talking about.

Thank you for reading!

LINKS: Previous 6.002 post, next 6.002 post

Course citation: Agarwal, Anant, 6.002 Circuits and Electronics, Spring 2007. (Massachusetts Institute of Technology: MIT OpenCourseWare), http://ocw.mit.edu (Accessed 31 Aug, 2010). License: Creative Commons BY-NC-SA

Book citation: Agarwal, Anant, and Jeffrey H. Lang. Foundations of Analog and Digital Electronic Circuits. San Mateo, CA: Morgan Kaufmann Publishers, Elsevier, July 2005. ISBN: 9781558607354.