Electrical Engineering Dictionary - part 191
zero flag
a bit in the condition code reg-
ister that indicates whether the result of the
last arithmetic or logic instruction is zero (1
for zero, 0 for not zero).
zero input response (ZIR)
the response
of a system to initial conditions (i.e., to the
initial energy present in the system) only. For
example, the zero input response (ZIR) of
the RC circuit shown in the figure is the sig-
nal
y
zir
(t), t ≥ 0 to the initial voltage across
the capacitor, with zero voltage applied at the
source.
RC circuit zero input response.
zero of 2-D transfer matrix
a pair of com-
plex numbers (
z
0
1
, z
0
2
)
T (z
1
, z
2
) =
N (z
1
, z
2
)
d (z
1
, z
2
)
,
N (z
1
, z
2
) ∈ R
p×m
[
z
1
, z
2
]
that satisfy the condition that the rank of
the matrix
N(z
0
1
, z
0
2
) drops below the normal
rank of the polynomial matrix
N(z
1
, z
2
), i.e.,
rank
N
z
0
1
, z
0
2
< min(m, p)
where
R
p×m
[
z
1
, z
2
] is the set
p × m poly-
nomial matrices in
z
1
and
z
2
with real coef-
ficients.
zero of generalized 2-D linear system
a
pair of complex numbers (
z
0
1
, z
0
2
)
Ex
i+1,j+1
= A
0
x
ij
+ A
1
x
i+1,j
+ A
2
x
i,j+1
+ B
0
u
ij
+ B
1
u
i+1,j
+ B
2
u
i,j+1
y
ij
= Cx
ij
+ Du
ij
with the system matrix
S (z
1
, z
2
) =
G (z
1
, z
2
) −B (z
1
, z
2
)
C
D
G (z
1
, z
2
) := Ez
1
z
2
− A
0
− A
1
z
1
− A
2
z
2
B (z
1
, z
2
) := B
0
+ B
1
z
1
+ B
2
z
2
if rank
S
z
0
1
, z
0
2
< n + min(m, p)
where
x
ij
∈ R
n
is the semistate vector,
u
ij
∈
R
m
is the input vector,
y
ij
∈ R
p
is the output
vector,
A
k
,
B
k
(
k = 0, 1, 2), C, D are real
matrices with
E possibly singular. A zero of
2-D transfer matrix. ( See also
) is always zero of the system.
zero order hold (ZOH)
a procedure that
samples a signal
x(t) at a given sampling in-
stant and holds that value until the succeeding
sampling instant.
zero padding
technique where a discrete
finite length signal is padded by adding some
number of zeros at the end of the signal. The
discrete Fourier transform of a zero padded
signal has more frequency samples or com-
ponents than that of a nonzero padded sig-
nal, although the frequency resolution is not
increased. Zero padding is also sometimes
used with the discrete Fourier transform to
perform a convolution between two signals.
zero phase filter
a filter whose Fourier
transform is purely real. In this way the phase
response is zero. A filter considered as a sig-
nal has zero phase if it is an even signal.
zero sequence
the set of in-phase compo-
nents used in symmetrical component anal-
ysis. Zero sequence currents are closely as-
sociated with ground current in a grounded
wye system, and do not directly flow in an
ungrounded delta system.
zero state response (ZSR)
the response
of a system with zero initial conditions (i.e.,
zero initial energy present in the system) to
an applied input. For example, in the follow-
ing circuit, the zero state response (ZSR) is
the signal
y
zsr
(t), t ≥ 0 when the input volt-
age
f (t) is applied, and there is zero initial
voltage across the capacitor.
c
2000 by CRC Press LLC