β

v n ( t , x )

t v n ( t , x )

v z ( t , 0 , h )

β < 6 5

v n ( t , x )

t t 2

v n t < 0

v z ( t , 0 , h )

t t 2

β = 6 5

v n ( t , x ) = 4 9 η 2 1 η 2

v n t = 0

v z ( t , 0 , h ) = 2 9

6 5 < β < 1

v n ( t , x ) 0

t t 2

v n t > 0

v z ( t , 0 , h ) 0

t t 2

β = 1

v n ( t , x ) 0

t

Exponentially

v n t > 0

v z ( t , 0 , h ) 0

t

Exponentially

1 < β < 4 5

v n ( t , x ) 0

t

v n t > 0

v z ( t , 0 , h ) 0

t

4 5 β < 0

v n ( t , x ) 0

t

v n t > 0

v z ( t , 0 , h ) 0

t

β = 0

v n ( t , x ) = 0

v n t = 0

v z ( t , 0 , h ) 0

t

0 < β

v n ( t , x ) 0

t

v n t < 0

v z ( t , 0 , h ) 0

t