Week 10 of 15 – Terms	Name: Answer Sheet

In your own words, write a definition for each of the following terms. Plagiarism will be checked and not tolerated.

Points: 5 pts/each = 7 * 5 = 35 pts

First-order lag

The output response of a process to a step change on the input.

Dead time

1. The interval of time between the initiation of an input change or stimulus and the start of the resulting response. [ANSI/ISA-51.1-1979 (R1993)] 2. Any definite delay that is deliberately placed between two related actions in order to avoid overlap that might cause confusion or to permit a particular different event, such as a control decision, switching event, or similar action to take place.

Process noise

1. In process instrumentation, an unwanted component of a signal or variable. Note: It may be expressed in units of the output or in percentage of output span. [ANSI/ISA-51.1-1979 (R1993)]

Environmental change

Any change in the surrounding environment of the process such as vibration, shock, temperature, humidity, etc.

Linear

The type of relationship that exists between two variables when the ratio of the value of one variable to the corresponding value of the other is constant over the entire range of possible values.

Non-linear

Any system whose operation cannot be represented by a finite set of linear differential equations.

High-order lags

The output response to a step change in the input does not occur at the origin, or start of the step change. The output responds at some time later then the step change. When this happens, compensating for first order lag is not sufficient and implies that ‘higher-order lags’ are present.