Arcology

Arcology, a portmanteau of ecology and architecture, is a set of architectural design principles aimed toward the design of enormous habitats (hyperstructures) of extremely high human population density. These largely hypothetical structures, which are themselves commonly referred to as "arcologies," would be self-contained, contain a variety of residential and commercial facilities, minimize individual human environmental impact, and possibly be economically self-sufficient.

OMAC Project

The OMAC Project is a six issue American comic book limited series written by Greg Rucka with art by Jesus Saiz and published by DC Comics in 2005. The series was collected, along with Countdown to Infinite Crisis and Wonder Woman #219, in a trade paperback in November 2005.

It is one of four miniseries leading up to DC Comics' Infinite Crisis event. The series directly follows the Countdown to Infinite Crisis special, picking up the story where the special left off. While the OMACs look similar to the earlier Jack Kirby creation OMAC, they are quite different, with a different acronym than the original One-Man Army Corps. OMAC originally stood for Observational Meta-human Activity Construct, but currently stands for "Omni Mind And Community."

On-off control

On-off control

For example, a thermostat is a simple negative-feedback control: when the temperature (the "measured variable" or MV) goes below a set point (SP), the heater is switched on. Another example could be a pressure-switch on an air compressor: when the pressure (MV) drops below the threshold (SP), the pump is powered. Refrigerators and vacuum pumps contain similar mechanisms operating in reverse, but still providing negative feedback to correct errors.

Simple on-off feedback control systems like these are cheap and effective. In some cases, like the simple compressor example, they may represent a good design choice.

Systems theory

Systems theory is an interdisciplinary field of science and the study of the nature of complex systems in nature, society, and science. More specificially, it is a framework by which one can analyze and/or describe any group of objects that work in concert to produce some result. This could be a single organism, any organization or society, or any electro-mechanical or informational artifact. Systems theory as a technical and general academic area of study predominantly refers to the science of systems that resulted from Bertalanffy's General System Theory (GST), among others, in initiating what became a project of systems research and practice. It was Margaret Mead and Gregory Bateson who developed interdisciplinary perspectives in systems theory (such as positive and negative feedback in the social sciences).