Ammonite Fossil (Goniatite, Devonian) - Atlas Mtns, Morocco

Here is a semester project in the 2012 Mechatronic control systems engineering module at San Jose State University. This is a Proportional-Integral-Derivative controlled (PID), 6 degree of freedom (6-DOF) Stewart platform, which basically means it has six axes on the top plate. This prototype uses 6 radio controlled servo motors instead of the traditional use of hydraulic jacks or electronic actuators. (this video has sound)

Proportional-Integral-Derivative:

A PID controller continuously calculates an error value as the difference between a measured process variable and a desired setpoint. The controller attempts to minimize the error over time by adjustment of a control variable, such as the position of a set of servo motors or actuators,  to a new value, given by a weighted sum:

where Kp ,Ki , and Kd, all non-negative, denote the coefficients for the proportional, integral, and derivative terms, respectively (sometimes denoted P, I, and D).

P accounts for present values of the error , and is determined by the direction and magnitude the correction needs to be applied (e.g. if the error is large and positive, the control variable will be large and negative),

I accounts for past values of the error (e.g. if the output is not sufficient to reduce the size of the error, the control variable will accumulate over time, causing the controller to apply a stronger action through P), and

D accounts for possible future values of the error, based on its current rate of change. This part determines when and at what rate it needs to reduce the magnitude of its action, e.g as the ball fast approaches the desired set point at the centre of the plate.

[source]

The Bortle Scale and Light Pollution

The Bortle Scale is used by astronomers to rate the darkness of our skies. It ranges from 1 (darkest) to 9 (brightest). For most of us, our daily lives are spent beneath a radiance level of between 5 and 8 and rarely venture into areas ranked 3 or darker- and what a shame that is.

Light pollution, while a testament to our technological advances, has blanketed our view of the universe and decoupled our relationship with the cosmos. For the millions of people living in areas where less than 20 stars can be seen in the night sky, it is practically impossible to imagine a natural sky blanketed with upwards of 2,500 stars backed by great ribbons of billions of stars which can be found in our Galaxy: The Milky Way.

What are the effects of light pollution?

Continuar lendo

crystaljewelryaffair You guys, I’m dying over here. I was out of baby-sized Ammonites, but my new batch just came in!! 💜 . If you need a ring, just holla! 💍 . These miraculous fossils always amaze me with their little Druzy pockets and natural iridescence 🔮

“Stress is nothing more than a socially acceptable form of mental illness.”

— Richard Carlson  (via fyp-psychology)

I want to be the first person on the moon to shoot a sniper rifle at earth and hit a wasp nest.  my whole life so far is leading up to that moment

Positives of High Functioning Anxiety/Depression: I can complete day-to-day tasks

Negatives of High Functioning Anxiety/Depression: Literally nobody has any sympathy for you when you’re depressed or having panic attacks because you’re so fine most of the time.

Alan Turing: A Tribute

See more images at: http://futurism.com/images/

http://futurism.com/images/turing/

Mood