CIVIL ENGINEERING DESIGN

Flashcards about Models and Systems in Engineering Design Process.

Model

An abstract description of the relationship between variables in a system used to explain how a system works, predict how it will behave and make design decisions.

Specific Model

Model that describes a system or function that has the same trend or behavior as a generalized model.

Linear Models

Graph: straight line, Physical meaning: Constant rate processes.

Hooke’s Law (Spring Model)

The variable k is the spring constant, a measure of the stiffness of the spring.

Ohm’s Law (Electric Circuits)

Voltage (V, volts) is the “force” that pushes the electrons around. Electric current (I, amperes) is a measure of how many charges flow through a wire in a given amount of time. Resistance (R, ohms) is a measure of how difficult it is to push electrons through a substance or device.

Viscosity (Pa·s)

Fluid property, the resistance against flow.

Power Models

Generalised power models take the form y = bxm + c. where: b and c = constants, m = exponent Note: In this chapter, we only consider models where c is zero.

Exponential Models

Curve shows rapid growth or decay, depending on m.

Exponential Growth Function

Type of function that increases without bound as the independent variable increases. Has y = bemx + c with m is a positive value that represents the growth rate.

Exponential Decay Function

Type of function that decreases and asymptotically approaches a value as the independent variable increases. In the exponential decay model y = be-mx + c m is a “positive” value that represents the decay rate.