June 29, 2012

## Control Theory of Engineering

Control theory is an interdisciplinary branch of engineering and mathematics. It deals with the behavior of dynamical systems. The desired output of a system is called the reference. In a control system a controller manipulates the inputs to a system. In the control systems one or more output variables of a system need to follow a certain reference over time.

By manipulating the input, the controller wants to obtain the desired effect on the output of the system. The usual objective of a control theory is to calculate solutions for the proper corrective action from the controller that result in system stability, that is, the system will hold the set point and not oscillate around it.

June 29, 2012

## Cybernetics

Cybernetics [sahy-ber-net-iks] is the theory of communication and control based on regulatory feedback. This is the original definition of the term; in popular culture the term refers to the study of cyborgs and robotic implants and prosthetics. Cybernetics is only applicable when the system being analyzed is involved in a closed signal loop; that is, where action by the system causes some change in its environment and that change is fed to the system via information (feedback) that enables the system to change its behavior.

A very simple model of cybernetics is that of a central heating system with four elements: a Sensor (to test the system’s environment); a Goal (the specification of the desired state of the system); Error Detection (a method for finding the difference between the present state and the goal state); and an Effector (operations the system can make to get the environment closer to the goal). A more complicated example is the Honda android ASIMO, which uses sensors and sophisticated algorithms to avoid obstacles and navigate stairs.

June 29, 2012

## Affect Control Theory

In control theory (a theory of sociology that examines controls on societal order), affect control theory proposes that individuals maintain affective meanings through their actions and interpretations of events. The activity of social institutions occurs through maintenance of culturally based affective meanings. Besides a denotative meaning, every concept has an affective meaning, or connotation, that varies along three dimensions: Evaluation (goodness versus badness); Potency (powerfulness versus powerlessness); and Activity (liveliness versus torpidity).

Affective meanings can be measured with semantic differentials yielding a three-number profile indicating how the concept is positioned on evaluation, potency, and activity (EPA). American psychologist Charles E. Osgood demonstrated that an elementary concept conveyed by a word or idiom has a normative affective meaning within a particular culture. A stable affective meaning derived either from personal experience or from cultural inculcation is called a sentiment, or fundamental affective meaning.

June 29, 2012

## Negative Feedback

Negative feedback occurs when the output of a system acts to oppose changes to the input of a system, acting to stabilize it. The classic example is a central heating system which cuts off when a (suitably placed) temperature sensor hits a pre-set mark. The negative feedback part is the thermostat. Negative feedback is a basic concept of cybernetics (the theory of communication and control based on regulatory feedback in animals and machines).

In biology negative feedback is known as homeostasis (the property of a system, either open or closed, that regulates its internal environment and tends to maintain a stable, constant condition). Virtually all aspects of living systems involve homeostasis (e.g. blood pressure, glucose level, liver functions, cell division). The disruption of feedback loops can lead to undesirable results: in the case of blood glucose levels, if negative feedback fails, the glucose levels in the blood may begin to rise dramatically, thus resulting in diabetes.

June 29, 2012

## Control Theory of Sociology

Control Theory is a theory of social order in sociology, which classifies control as centralized or decentralized or neither. Decentralized control is considered market control. Centralized control is considered bureaucratic control. Some types of control such as clan control are considered to be a mixture of both decentralized and centralized control.

Decentralized control or market control is typically maintained through factors such as price, competition, or market share. Centralized control such as bureaucratic control is typically maintained through administrative or hierarchical techniques such as creating standards or policies. Mixed control or clan control is typically maintained by keeping a set of values and beliefs or norms and traditions.

June 29, 2012

## Meta-reference

Metareference is a situation in a work of fiction whereby characters display an awareness that they are in such a work. Sometimes it may even just be a form of editing or film-making technique that comments on the show/film/book itself. It is also sometimes known as ‘Breaking the Fourth Wall,’ in reference to the theatrical tradition of playing as if there were no audience, as if a wall existed between them and the actors.

Metareference in fiction is jarring to the reader, but can be comical, as in Jasper Fforde’s novel ‘Lost in a Good Book.’ The character Thursday Next remarks to her husband that she feels uncomfortable having sex in front of so many people, when he is confused because they are alone in their bedroom, she explains, ‘all the people reading us.’ In Fforde’s ‘The Fourth Bear’ two characters lament over a bad joke made by the author, saying, ‘I can’t believe he gets away with that.’ Some novels with first person narration contain instances of metareference when the narrator addresses the reader directly (e.g. Charlotte Brontë’s ‘Jane Eyre’).

June 29, 2012

## Mise en Abyme

Mise [meezen [awnabyme [ah-beem] is a term originally from the French and means ‘placed into abyss.’ The commonplace usage of this phrase is describing the visual experience of standing between two mirrors, seeing an infinite reproduction of one’s image, but it has several other meanings in the realm of the creative arts and literary theory. In Western art history, ‘mise en abyme’ is a formal technique in which an image contains a smaller copy of itself, the sequence appearing to recur infinitely.

In the terminology of heraldry, the ‘abyme’ is the center of a coat of arms. The term ‘mise en abyme’ then meant literally ‘put in the center.’ It described a coat of arms that appears as a smaller shield in the center of a larger one (the Droste effect). For example, the two-headed eagle on modern coat of arms of Russia has a scepter with coat of arms of Russia on top of it, with the same scepter.