Distortion

Distortion is the alteration of the original shape (or other characteristic) of something, such as an object, image, sound or waveform. Distortion is usually unwanted, and so engineers strive to eliminate distortion, or minimize it. In some situations, however, distortion may be desirable. The important signal processing operation of heterodyning is based on nonlinear mixing of signals to cause intermodulation. Distortion is also used as a musical effect, particularly with electric guitars.

The addition of noise or other outside signals (hum, interference) is not deemed distortion, though the effects of quantization distortion are sometimes deemed noise. A quality measure that explicitly reflects both the noise and the distortion is the Signal-to-noise-and-distortion (SINAD) ratio.

Electronic signals

In telecommunication and signal processing, a noise-free system can be characterised by a transfer function, such that the output can be written as a function of the input as

When the transfer function comprises only a perfect gain constant A and perfect delay T

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3D&T

3D&T, formerly known as "Defensores de Tóquio", is a Brazilian tabletop role-playing game, created by Marcelo Cassaro. It is designed to be a very simple, beginner-friendly game system.

History

Origin

The name of the game is a pun on the famous Dungeons & Dragons or "D&D"; the original version of the game – Defensores de Tóquio ("Defenders of Tokyo") – was a satire of tokusatsu, fighting games, and anime series. It was created by Marcelo Cassaro and published by Trama Editorial, later known as Editora Talismã. It spawned "AD&T" - as implied by the name, an "advanced" edition (and a pun on AD&D). Finally, "3D&T" means "Defenders of Tokyo 3rd edition". The major change on the 3rd edition was that it was turned into a generic game, dropping its satire roots. It was a huge success, becoming as popular as Dungeons & Dragons and Vampire: The Masquerade among Brazilian roleplayers.

An even simpler version, "3D&T Fastplay", was made freely available online.

A revision, "3D&T Manual Revisado, Ampliado e Turbinado", was released in 2003.

User error

A user error is an error made by the human user of a complex system, usually a computer system, in interacting with it. Although the term is sometimes used by human–computer interaction practitioners, the more formal human error term is used in the context of human reliability.

Related terms such as PEBCAK (Problem Exists Between Chair And Keyboard), ID-10T error (idiot error), and other similar phrases are also used as slang in technical circles with derogatory meaning. This usage implies a lack of computer savvy, asserting that problems arising when using a device are the fault of the user. Critics of the term argue that the problems are caused instead by a device that doesn't take into account human limitations and is thus designed in a way that induces errors.

The term can also be used for non-computer-related mistakes.

Causes

Joel Spolsky points out that users usually do not pay full attention to the computer system while using it. He suggests to compensate for this to make usable systems, thus allowing a higher percentage of users to complete tasks without errors: