a quick one

today will be visual-

most days, on the train, i am reading steven strogatz' text on nonlinear dynamics and chaos, conspicuously titled as such. it is a thumping good read (a phrase i picked up from saikat biswas).


there are many murals in philadelphia. this might be my favorite so far-

this is a stochastic fractal that jeffsteward and i fumbled out..
i will write more about this later. . but for now.. here is number 4.

here dumped here..
some ramblings for the sake of converging on a useful perspective..
i have found (in a large way) that if i am having trouble grasping something, or if something that i see in nature does not fit with my intuition of nature,
if i just start talking to someone about it... usually my ramblings will come across some perspective that is useful.
it is the same effect that writing has. by talking, i force my implicit ideas to be turned into explicit ideas. through this process, the things which you thought languagelessly about have to be accounted for. when this happens, a lot of structures which may have been overlooked, or misinterpreted (in their vague implicit forms) are forced to become explicit, well-formed, and uttered..

so.. i seem to achieve the same effect when i talk to myself. i ask myself all relevant questions which occur to me in real-time.. and so on.
so, here is some auto-discussion towards resolving my issues in the previous post, pertaining to the seeming information loss when using time delay embedding with the chaotic circuit data.
i think i may have resolved more or less how this might be happening, but i will have to take further data to find out..
the ramble is 12:00 or so.. since i meant it just for myself.
otherwise, i try to keep them kind of short..

scrollPopulation by a philadelphia experiment

it has been an easy hectic bit, .. but i have returned..

getting down to it-
mathy stuff is in brackets [],

we have taken data from the chaotic circuit, which is quite gracious, compared to any circuits that i have ever met, in the way of behavior..
the "chua circuit" is basically a relatively simple circuit which is capable of many different types of behavior
figure 1

[it is a nonlinear dynamical system, deriving its nonlinearity from a cleverly constructed nonlinear element called the "chua diode".
if you would like to dive into it, this is for you].
put simply, the circuit has certain properties [parameters], which can be changed, in our case, we are changing the voltage being applied to the "nonlinear resistor", which changes its resistance in the chua diode.
for some particular values of the parameter, say, when applying 2.5 volts, a the circuit can have a perfectly repetitive [periodic] oscillating behavior. [you are looking at the measurement "x" is changing over time]
figure 2

then, if we were to decrease the voltage slightly, the behavior of the circuit becomes a little more complicated but still periodic- notice that the oscillations alternate tall-short-tall-short, yet, the behavior is still repetitive. (this is still x, beginning to behave more erratically)
figure 3

[the system exhibits a period doubling cascade]as we change the voltage further, the behavior becomes more "complex"
figure 4

until, at some particular voltage, the behavior becomes chaotic, that is, completely aperiodic (non-repeating).
figure 5

the variable y does the same thing.
if we plotted x against y, (looking at part of the system's state space) the previous progression looks like this;
figure 6

from the oscilloscope, which displays the measurements in real time, the system in chaotic behavior looks like this
figure 7

this shape is called the double scroll attractor. its spacial structure in state space corresponds to the dynamical structure of the chaotic behavior. it is called an attractor of the system. and since it is fractal, it is called a "strange attractor".


this is all great..
but the trouble comes when i try to implement my analysis, which consists of something called time delay embedding.
this is when you reconstruct the attractor of the system, with only one variable (say for instance, x), by "plotting it against itself (with a small time delay), instead of y. this is essentially defining a map from the data in x, to a higher dimensional space.
by the theory (and all of my experience with it), one may reconstruct the attractor in this manner.. yet, i am running into trouble using just the data from x. let x(n) be the value of x at time n. then, we "embed x with a time delay t", meaning we plot x(n) against x(n+t) . and we see that, the double scroll does not manifest,
figure 8

nor does it seem to manifest in higher dimensions (which is usually the trick)...
at least, i think this is a problem that i am having.
i still have a few things to check.
one thing is for sure,.. the measure of complexity that i am implementing is treating this embedded chaos as though it is random noise.. which suggests to me that either there is some information missing in the embedding (which could come from not embedding in a high enough dimension, or possibly relying on another variable and/or measurement conditions), because the measure should (and generally does) have a higher value on chaotic data than on random data. i know that our data is chaos.. so, i just have to convince my computer that it is.. and then things will get going.

here are some quick reflections from my first day at work. i recorded it while walking across the naval yard, up to the subway station..
a pre-correction to statements in the audio: not American Outfitters, but Urban Outfitters!
first day at work by a philadelphia experiment

i will throw in some pictures from the base, and the lab soon..
this is/was a quick one!
again, to come, less audio, more visual and text.. promise (actually, since these are catch up posts, i know the future.. so.. )

first impressions of the city..

[alright, i am a little less than a week behind, since it took me a while to figure out how to embed these players on this page.. but blah blah, done.]

i suppose that, first, i would like to thank who ever it was that mowed the giant happy face in the field outside of philadelphia that i saw from the plane as we were coming in for our landing..
it was magical.. and i am somewhat certain that i was the only one on the plane to see it (why am i certain...well..i am not sure.. likely because nobody else burst into laughter.. but that might be a little unfair).
also, i would like to thank the girl at the bus stop, who answered the first of my many questions to philadelphians about the mechanism of public transit, AND gave me a fare token to get on the bus when i realized that i did not have three dollars, but a five instead..
your fingernails were terrifyingly neon pink, and your grace was fluorescent as well..

so, this is a short recording that i made on my first evening in town, walking from the apartment to the grocery store (whole foods).

first glimpse by a philadelphia experiment

i hope to mix more text, photos and videos with these audio recordings.. but for tonight, this will have to do. als0, this is a capture more or less of what there is to capture..

also, i intend to make the language a little more family friendly.. i was just a bit excited in the recording...

a visitation

here is the premise:

my name is ralph wilson. i am a graduate student in mathematics at florida state university. my passion is complex systems. likely, anyone else's passion is also some special case of a complex system, whether they are familiar with the term or not.

i will get more into what that might mean later.

i have been offered an internship this summer (2010) in philadelphia to study complex systems from an experimental stand point. in particular, my interest is nonlinear dynamics of complex systems. again, more on what that is later.

this blog is an attempt to document this summer, namely, the work, observations, and incidents (incidence) contained within.

i hope to partially succeed.
i will use audio recordings a good deal, because i may not have too much free time to write. such recordings, i will try to keep under ten minutes a piece, since it is not a terribly effortless medium to consume from.

this is the start.