Tuesday, September 8, 2009

Reliability and Reliability Engineering (Supplemental)

This is a supplementary material for the entry Reliability Part1. A bulk of reliability concepts revolves around the discussion of the Weibull Distribution and its associated Hazard Function.
The Weibull Distribution Function is characterized by 3 parameters namely Beta (for the shape), Eta (for the scale), and Gamma (for the location). Here is a JMP JSL script that demonstrates how the Weibull distribution changes as each of these parameters change. The output window is shown below:



The JMP JSL Script is shown below::



Beta_value = 1.5;
Eta_value = 2.0;
Gamma_value = 0;


EXPO = Expr(
MESSAGEBOX = New Window( "NOTICE:",
Border Box(
top( 10 ),
Left( 10 ),
Panel Box( "Read:",
Text Box( "If the value of the shape parameter Beta = 1, the Weibull becomes an Exponential Distribution" )
)
)
);
Wait( 2 );
MESSAGEBOX << CLOSE WINDOW;
);

TEXT_MESSAGE = "Shape parameter Beta = " || char(Beta_value) ||"; Scale parameter Eta = " || char(Eta_value) || "; Location parameter Gamma = " || char(Gamma_value);

NON_EXPO1 = Expr(Caption( "If the value of the shape parameter Beta = 1, the Weibull becomes an Exponential Distribution. " ));
NON_EXPO2 = Expr(Caption(TEXT_MESSAGE));

Weibull_Window = New Window( "Properties of the Weibull Density and Hazard Functions",
V List Box(
GraphWindow = Graph(
FrameSize(500,500),
Double Buffer,
FrameSize( 500, 300 ),
X Scale( 0, 3 ),
Y Scale( 0, 4 ),
Double Buffer,
Y Function( (Beta_value / x) * (x / eta_value) ^ Beta_value * Exp( -(x / eta_value) ^ Beta_value ), x ); /* density */
Y Function( (Beta_value / x) * (x / eta_value) ^ Beta_value, x ); /* hazard */
Pen Size( 2 );
Pen Color( "red" );
Text Color ("red");
Text Size(12);
text({1,.7},"Weibull Probability Distribution Function",);
Y Function(
(Beta_value / Eta_value) * ((x - gamma_value) / eta_value) ^ (Beta_value - 1) *
Exp( -1 * ((x - gamma_value) / eta_value) ^ Beta_value ),
x
);
Pen Color( "Blue" );
Text Color ("Blue");
Text Size(12);
text({0.8,1.2},"Hazard Function",);
Y Function( (Beta_value / Eta_value) * ((x - gamma_value) / eta_value) ^ (Beta_value - 1), x );
),
H List Box(
V List Box(
H List Box( TB1=Text Box("Shape Parameter Beta"), Text Box(" ") ),
Slider Box(
0,
10,
Beta_value,
TEXT_MESSAGE = "Shape parameter Beta = " || char(Beta_value) ||"; Scale parameter Eta = " || char(Eta_value) || "; Location parameter Gamma = " || char(Gamma_value);
GraphWindow << reshow;
Weibull_Window<<reshow;
If( BETA_value == 1,
NON_EXPO1,
NON_EXPO2
);
)
),
V List Box(
H List Box( TB2=Text Box( " Scale Parameter Eta" ), Text Box(" ") ),
Slider Box(
0,
10,
Eta_value,
TEXT_MESSAGE = "Shape parameter Beta = " || char(Beta_value) ||"; Scale parameter Eta = " || char(Eta_value) || "; Location parameter Gamma = " || char(Gamma_value);
GraphWindow << reshow;NON_EXPO2;
)
),
V List Box(
H List Box( TB3=Text Box( " Location Parameter Gamma" ), Text Box(" ") ),
Slider Box(
0,
10,
Gamma_value,
TEXT_MESSAGE = "Shape parameter Beta = " || char(Beta_value) ||"; Scale parameter Eta = " || char(Eta_value) || "; Location parameter Gamma = " || char(Gamma_value);
GraphWindow << reshow;NON_EXPO2;
)
)
)

)
);



TB1 << Font color( "BLUE" );
TB1 << set Font size( 10 );
TB2 << Font color( "BLUE" );
TB2 << set Font size( 10 );
TB3 << Font color( "BLUE" );
TB3 << set Font size( 10 );








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