Package org.jreliability.function.common

Class NMWDReliabilityFunction

java.lang.Object

org.jreliability.function.SequentialFunction

org.jreliability.function.common.NMWDReliabilityFunction

All Implemented Interfaces:

Function, ReliabilityFunction

public class NMWDReliabilityFunction
extends SequentialFunction
implements ReliabilityFunction

The NMWDReliabilityFunction represents the NMWD ReliabilityFunction based on the WeibullReliabilityFunction with a third parameter:

R(x) = 1 - F(x) = e^-(a * x^b * e^(lambda * x))
with lambda, a > 0 and b >= 0.

While the parameter lambda scales the reliabilityFunction, the a and b parameters determine the shape of the ReliabilityFunction. This function allows to model bathtub-shaped failure rates that can directly be derived from given Weibull plots, cf. [1].

[1] Lai, C.D. and Xie, Min and Murthy, D. N. P.: A Modified Weibull Distribution. In IEEE Transactions on Reliability, Vol. 52, No. 1, 2003.

Field Summary

Fields

Modifier and Type	Field	Description
protected final double	a	The used shape of the NMWDReliabilityFunction.
protected final double	b	The used shape of the NMWDReliabilityFunction.
protected final double	lambda	The lambda parameter somehow resembles the failure-rate lambda.

Constructor Summary

Constructors

Constructor	Description
NMWDReliabilityFunction(double lambda, double a, double b)	Constructs a NMWDReliabilityFunction with a given lambda, a, and b.

Method Summary

Modifier and Type	Method	Description
double	getY(double x)	Returns the y value for y = f(x).

Methods inherited from class org.jreliability.function.SequentialFunction

getY

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.jreliability.function.Function

getY

Field Details

lambda

protected final double lambda

The lambda parameter somehow resembles the failure-rate lambda.

a

protected final double a

The used shape of the NMWDReliabilityFunction.

b

protected final double b

The used shape of the NMWDReliabilityFunction.

Constructor Details

NMWDReliabilityFunction

public NMWDReliabilityFunction(double lambda,
 double a,
 double b)

Constructs a NMWDReliabilityFunction with a given lambda, a, and b.

Parameters:

lambda - the scale value

a - the first shape value

b - the second shape value

Method Details

getY

public double getY(double x)

Description copied from interface: Function

Returns the y value for y = f(x).

Specified by:

getY in interface Function

Parameters:

x - the x value

Returns:

the y for y = f(x)