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j
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1.
I
NT
RO
D
UCT
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N
C
o
d
e
s
m
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ar
e
s
tr
u
ctu
r
es
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o
d
e
t
h
at
in
d
icate
v
io
lati
o
n
o
f
d
esig
n
r
u
les.
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o
d
e
s
m
ells
ar
e
n
o
t
p
r
ev
en
tin
g
th
e
p
r
o
g
r
am
f
r
o
m
p
r
o
v
id
in
g
its
r
eq
u
ir
ed
f
u
n
cti
o
n
ality
.
Ho
wev
er
,
th
e
y
in
d
ic
ate
wea
k
n
ess
es
in
s
o
f
twar
e
d
esig
n
.
C
o
d
e
s
m
ells
m
ay
in
cr
ea
s
e
th
e
r
is
k
o
f
s
o
f
t
war
e
f
ailu
r
e.
T
h
e
ex
is
ten
ce
o
f
co
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e
s
m
ells
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ay
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iv
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a
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ig
n
ab
o
u
t
wid
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esig
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th
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o
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u
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d
e
r
s
tan
d
ab
ilit
y
an
d
ef
f
ec
tiv
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n
ess
[
1
]
.
Sin
ce
co
d
e
s
m
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p
lay
a
k
e
y
r
o
le
in
s
h
ap
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g
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e
q
u
ality
o
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s
o
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s
ev
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tu
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ies
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r
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ted
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h
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Fo
wler
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[
2
]
lis
ted
2
2
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s
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clas
s
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ied
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ted
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ca
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iz
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ca
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.
B
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wo
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wi
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ig
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I
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e
o
f
s
witch
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tatem
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n
t
will
lead
to
co
d
e
d
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I
n
a
d
d
itio
n
,
th
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u
s
e
o
f
a
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p
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r
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s
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th
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o
f
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les
ca
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n
o
t
b
e
a
cc
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ed
o
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ts
id
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it
s
Evaluation Warning : The document was created with Spire.PDF for Python.
I
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&
C
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m
p
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n
g
I
SS
N:
2088
-
8
7
0
8
A
s
ystema
tic
r
ev
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w
o
n
s
o
ftw
a
r
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co
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mells
(
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ely
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e
s
m
ells
ar
e
u
n
n
ec
ess
ar
y
co
d
e
t
h
at
m
u
s
t
b
e
r
em
o
v
ed
.
Fo
r
ex
a
m
p
le,
co
d
e
m
ay
co
n
tain
u
s
eless
class
e
s
(
lazy
class
)
o
r
u
n
n
ec
ess
ar
y
d
a
ta
f
ield
s
in
a
class
(
d
ata
class
)
.
Data
class
es
ar
e
u
n
ab
le
to
u
s
e
th
eir
f
ield
s
an
d
r
eq
u
ir
e
o
th
er
class
es
to
u
s
e
th
ese
class
es.
An
o
th
er
f
o
r
m
o
f
d
is
p
en
s
ab
le
is
th
e
co
d
e
d
u
p
licatio
n
wh
er
e
s
im
ilar
co
d
e
is
r
ep
ea
te
d
s
ev
er
al
tim
e
s
.
T
h
is
co
d
e
ca
n
b
e
r
ep
lace
d
o
r
u
n
if
ied
.
Sev
er
al
s
tu
d
ies
wer
e
p
r
esen
ted
in
t
h
e
liter
atu
r
e
to
a
d
d
r
ess
t
h
e
is
s
u
es
r
elate
d
to
v
ar
io
u
s
ty
p
es
o
f
c
o
d
e
s
m
ells
.
T
h
ese
i
s
s
u
es
co
n
ce
r
n
co
d
e
s
m
ell
d
etec
tio
n
tech
n
iq
u
es,
co
d
e
s
m
ell
im
p
ac
t,
co
d
e
s
m
ell
ca
u
s
es,
an
d
co
d
e
s
m
ell
ca
talo
g
u
e
.
Hen
ce
,
th
er
e
is
a
n
ee
d
to
a
p
p
r
aise
an
d
s
u
m
m
ar
ize
t
h
e
co
llectiv
e
f
i
n
d
in
g
s
an
d
id
e
n
tify
th
e
latest
d
ev
elo
p
m
en
ts
.
W
h
ile
ac
k
n
o
wled
g
in
g
th
e
v
al
u
ab
le
r
e
v
iew
s
tu
d
ies
co
n
d
u
cted
b
y
p
r
e
v
io
u
s
r
esear
ch
er
s
,
it
s
h
o
u
ld
b
e
n
o
t
ed
th
at
th
is
s
tu
d
y
f
o
llo
ws
a
s
y
s
tem
atic
r
ev
iew
m
eth
o
d
o
lo
g
y
an
d
em
p
lo
y
s
a
r
ig
o
r
o
u
s
s
elec
tio
n
an
d
an
aly
s
is
p
r
o
ce
s
s
f
o
cu
s
in
g
s
p
ec
if
ica
lly
o
n
th
e
y
ea
r
s
2
0
0
1
t
o
2
0
2
3
.
T
h
e
tim
ef
r
a
m
e
ch
o
s
en
f
o
r
th
e
r
ev
iew
r
e
f
lects
th
e
in
ten
tio
n
to
ca
p
tu
r
e
th
e
m
o
s
t
r
ec
en
t
d
ev
elo
p
m
en
ts
in
th
e
f
ield
o
f
co
d
e
s
m
ell
d
etec
tio
n
,
ac
k
n
o
wled
g
in
g
th
e
f
ast
-
p
ac
ed
n
atu
r
e
o
f
r
esear
ch
ad
v
an
ce
s
d
u
r
in
g
th
is
p
er
io
d
.
T
h
e
o
b
jectiv
e
o
f
th
is
s
tu
d
y
is
to
co
m
p
lem
e
n
t
p
r
e
v
i
o
u
s
r
ev
iew
r
esear
ch
b
y
e
x
am
in
in
g
s
tu
d
ies
co
n
d
u
cted
in
s
u
b
s
eq
u
en
t
y
ea
r
s
an
d
ex
ten
d
in
g
th
e
a
n
aly
s
is
to
in
cl
u
d
e
th
e
p
er
io
d
2
0
0
1
to
2
0
2
3
,
th
u
s
h
ig
h
lig
h
tin
g
r
ec
en
t
ad
v
a
n
ce
s
an
d
e
m
er
g
in
g
tr
en
d
s
in
co
d
e
s
m
ell
tech
n
iq
u
es.
T
o
th
e
b
est
o
f
th
e
au
th
o
r
s
’
k
n
o
wled
g
e,
th
is
is
th
e
f
ir
s
t
s
y
s
tem
atic
r
ev
iew
p
ap
er
o
n
co
d
e
s
m
ell
d
etec
ti
o
n
to
co
v
e
r
th
e
y
ea
r
s
2
0
0
1
to
2
0
2
3
.
W
e
r
etr
iev
ed
s
tu
d
ies
f
r
o
m
r
ep
u
tab
le
p
u
b
lis
h
in
g
v
en
u
es a
n
d
d
atab
as
es,
an
d
an
aly
ze
t
h
em
to
a
n
s
wer
th
e
f
o
llo
win
g
r
esear
ch
q
u
esti
o
n
s
:
R
Q1
: Wh
at
is
th
e
d
is
tr
ib
u
tio
n
o
f
s
tu
d
ies p
er
y
e
ar
in
th
e
co
n
te
x
t o
f
th
e
c
o
d
e
s
m
ell
d
etec
tio
n
?
R
Q2
: Wh
at
ar
e
th
e
ca
teg
o
r
ies o
f
p
u
b
licatio
n
s
in
clu
d
e
d
in
th
i
s
r
ev
iew
r
esear
ch
?
R
Q3
:
W
h
at
is
th
e
d
is
tr
ib
u
tio
n
o
f
th
e
s
tu
d
ies
in
clu
d
e
d
in
th
is
r
ev
iew,
ca
teg
o
r
ized
b
y
th
e
em
p
lo
y
ed
co
d
e
s
m
ell
d
etec
tio
n
tech
n
iq
u
e?
R
Q4
:
W
h
at
p
r
o
g
r
a
m
m
in
g
lan
g
u
ag
es
ar
e
e
m
p
lo
y
e
d
b
y
v
ar
io
u
s
co
d
e
s
m
ell
d
etec
tio
n
tech
n
iq
u
es
in
th
e
in
clu
d
e
d
s
tu
d
ies?
R
Q5
: Wh
at
s
u
b
ject
s
y
s
tem
s
w
er
e
u
s
ed
to
v
alid
ate
co
d
e
s
m
el
l d
etec
tio
n
tech
n
iq
u
es in
th
e
in
clu
d
ed
s
tu
d
ies?
R
Q6
: Wh
at
co
d
e
s
m
ells
wer
e
d
etec
ted
b
y
v
ar
io
u
s
tech
n
iq
u
e
s
in
th
e
in
clu
d
ed
s
tu
d
ies?
R
Q7
: Wh
at
ev
alu
atio
n
cr
iter
ia
wer
e
u
tili
ze
d
b
y
c
o
d
e
s
m
ell
d
etec
tio
n
tech
n
iq
u
es in
th
e
r
ev
i
ewe
d
s
tu
d
ies?
W
e
b
eliev
e
th
at
s
u
m
m
ar
izin
g
liter
atu
r
e
in
th
e
co
d
e
s
m
ell
d
etec
tio
n
f
ield
will
o
p
e
n
n
e
w
r
esear
ch
d
ir
ec
tio
n
s
an
d
will
h
elp
th
e
s
o
f
twar
e
en
g
in
e
er
in
g
co
m
m
u
n
ity
to
a
d
d
r
ess
th
e
n
ec
ess
it
y
o
f
u
tili
zin
g
n
e
w
d
etec
tio
n
tech
n
iq
u
es.
T
h
e
r
est
o
f
th
e
p
ap
er
is
o
r
g
an
ize
d
a
s
f
o
llo
ws:
s
ec
tio
n
2
p
r
esen
ts
p
r
ev
io
u
s
wo
r
k
i
n
s
u
r
v
ey
in
g
co
d
e
s
m
ells
an
d
r
elate
d
liter
atu
r
e.
Sectio
n
3
p
r
o
v
id
es
an
o
v
er
v
iew
o
f
t
h
e
t
o
p
ic,
h
i
g
h
lig
h
ts
th
e
im
p
ac
ts
o
f
co
d
e
s
m
ells
an
d
p
r
o
v
id
es
an
o
v
er
v
iew
o
f
c
o
d
e
s
m
ell
d
etec
tio
n
tech
n
iq
u
es.
R
e
s
ea
r
ch
m
eth
o
d
o
lo
g
y
is
p
r
esen
ted
in
s
ec
tio
n
4
;
th
e
a
n
aly
s
is
an
d
r
esu
lts
ar
e
p
r
esen
ted
in
s
ec
tio
n
5
.
T
h
e
p
ap
er
co
n
clu
d
es
in
s
ec
tio
n
6
.
Fin
ally
,
av
en
u
es f
o
r
f
u
tu
r
e
wo
r
k
ar
e
s
u
g
g
ested
in
s
ec
tio
n
7
.
2.
RE
L
AT
E
D
WO
RK
Sev
er
al
s
y
s
tem
atic
liter
atu
r
e
r
ev
iews
wer
e
p
r
esen
ted
in
th
e
liter
atu
r
e.
All
th
ese
r
ev
iews
f
o
cu
s
ed
o
n
co
m
p
ar
in
g
co
d
e
s
m
ell
d
etec
tio
n
ap
p
r
o
ac
h
es
in
te
r
m
s
o
f
d
i
f
f
er
en
t
cr
iter
ia.
O
u
r
f
in
d
in
g
s
in
th
is
r
ev
iew
ar
e
co
m
p
r
eh
e
n
s
iv
e,
co
n
s
is
ten
t,
an
d
co
m
p
lem
e
n
t th
e
co
n
clu
s
io
n
s
p
r
esen
ted
b
y
o
th
e
r
s
tu
d
ies.
T
h
e
s
u
r
v
ey
s
tu
d
y
c
o
n
d
u
cted
b
y
R
o
y
a
n
d
C
o
r
d
y
[
3
]
p
r
esen
ted
th
e
s
tate
o
f
th
e
ar
t
in
cl
o
n
e
d
etec
tio
n
r
esear
ch
.
T
h
e
s
u
r
v
ey
p
r
o
v
i
d
es
a
v
iew
o
f
th
e
ex
is
tin
g
clo
n
e
tax
o
n
o
m
ies,
d
etec
tio
n
ap
p
r
o
ac
h
es
an
d
ex
p
er
im
en
tal
e
v
alu
atio
n
s
o
f
clo
n
e
d
etec
tio
n
to
o
ls
.
Ad
d
itio
n
a
lly
,
Fo
n
tan
a
et
a
l.
[
4
]
p
r
esen
te
d
an
ex
p
er
im
en
tal
ev
alu
atio
n
o
f
s
ix
co
d
e
s
m
ell
d
etec
tio
n
to
o
ls
.
T
h
e
k
ey
d
if
f
er
en
ce
s
b
etwe
en
th
e
ad
d
r
ess
ed
to
o
ls
wer
e
h
ig
h
lig
h
ted
in
th
e
e
v
alu
atio
n
.
T
h
e
r
ev
iew
o
f
R
aso
o
l
an
d
Ar
s
h
ad
[
5
]
p
r
esen
ted
an
u
p
-
to
-
d
ate
r
ev
iew
o
n
th
e
s
tate
-
of
-
th
e
-
ar
t
tech
n
iq
u
es
an
d
to
o
ls
u
s
ed
f
o
r
m
in
in
g
c
o
d
e
s
m
ells
f
r
o
m
th
e
s
o
u
r
ce
co
d
e
o
f
d
if
f
e
r
en
t
s
o
f
twar
e
ap
p
licatio
n
s
.
T
h
ey
class
if
ied
s
elec
ted
co
d
e
s
m
ell
d
etec
tio
n
tech
n
iq
u
es
an
d
to
o
ls
b
ased
o
n
th
eir
d
etec
tio
n
m
eth
o
d
s
an
d
an
aly
ze
d
th
e
r
esu
lts
o
f
t
h
e
s
elec
ted
tech
n
iq
u
es.
R
aso
o
l
an
d
Ar
s
h
ad
f
o
c
u
s
ed
o
n
Fo
wler
’
s
2
2
co
d
e
s
m
ells
[
2
]
,
[
5
]
.
Sab
ir
et
a
l.
[
6
]
r
ev
iewe
d
7
8
p
r
im
ar
y
s
tu
d
ies
p
u
b
lis
h
e
d
f
r
o
m
J
an
u
a
r
y
2
0
0
0
till
Dec
em
b
er
2
0
1
7
.
T
h
e
r
ev
iew
o
f
Sab
i
r
et
a
l.
f
o
c
u
s
ed
o
n
th
e
co
d
e
s
m
ell
d
etec
tio
n
tech
n
iq
u
es
u
s
ed
in
o
b
ject
a
n
d
s
er
v
ice
-
o
r
ien
te
d
p
ar
ad
ig
m
s
.
Z
h
an
g
et
a
l.
[
7
]
r
e
v
iewe
d
3
9
s
tu
d
ies
r
elate
d
to
c
o
d
e
s
m
ells
d
etec
tio
n
.
T
h
eir
r
e
s
ea
r
ch
f
o
cu
s
ed
o
n
Evaluation Warning : The document was created with Spire.PDF for Python.
I
SS
N
:
2
0
8
8
-
8
7
0
8
I
n
t J E
lec
&
C
o
m
p
E
n
g
,
Vo
l.
15
,
No
.
3
,
J
u
n
e
20
25
:
3
0
1
0
-
3
0
2
7
3012
“Du
p
licated
C
o
d
e”
w
h
er
ea
s
s
o
m
e
co
d
e
b
ad
s
m
ells
s
u
ch
as
“M
ess
ag
e
C
h
ain
s
”
r
ec
eiv
ed
litt
le
atten
tio
n
.
Z
h
an
g
et
a
l.
s
tu
d
y
s
h
o
wed
th
at
v
er
y
f
ew
s
tu
d
ies
r
ep
o
r
t
th
e
im
p
ac
t
o
f
u
s
in
g
co
d
e
b
ad
s
m
ells
.
I
n
s
tead
,
m
o
s
t
s
tu
d
ies f
o
cu
s
ed
o
n
d
ev
elo
p
in
g
to
o
ls
an
d
m
eth
o
d
s
to
a
u
to
m
at
ically
d
etec
t c
o
d
e
b
a
d
s
m
ells
.
T
h
e
liter
atu
r
e
r
ev
iew
o
f
So
b
r
i
n
h
o
et
a
l.
[
8
]
s
h
o
wed
th
at
ev
en
th
o
u
g
h
b
ad
s
m
ells
o
f
d
if
f
er
en
t
ty
p
es
ar
e
s
tu
d
ied
to
g
eth
e
r
,
o
n
ly
a
s
m
all
n
u
m
b
er
o
f
s
tu
d
ies ex
p
l
o
r
ed
th
e
r
elatio
n
s
b
etwe
en
th
em
.
T
h
ey
s
u
g
g
ested
th
at
th
er
e
ar
e
a
d
d
itio
n
al
p
o
ten
tial
r
elatio
n
s
th
at
war
r
an
t
f
u
r
t
h
e
r
in
v
esti
g
atio
n
.
So
b
r
in
h
o
et
a
l.
also
n
o
ted
th
at
r
esear
ch
er
s
h
av
e
d
if
f
er
e
n
t
lev
els
o
f
in
ter
est,
s
o
m
e
o
f
th
em
p
u
b
lis
h
in
g
s
p
o
r
a
d
ically
an
d
o
th
er
s
co
n
tin
u
o
u
s
ly
.
Fu
r
th
er
,
th
e
r
e
v
iew
o
f
So
b
r
in
h
o
et
a
l.
f
o
u
n
d
th
at
t
h
e
co
m
m
u
n
ities
s
tu
d
y
in
g
d
u
p
licated
co
d
e
an
d
o
th
er
ty
p
es o
f
b
ad
s
m
ells
ar
e
lar
g
ely
s
ep
ar
ated
.
Fin
ally
,
So
b
r
in
h
o
et
a
l.
o
b
s
er
v
ed
th
at
s
o
m
e
v
en
u
es
ar
e
m
o
r
e
lik
ely
t
o
d
is
s
em
in
ate
k
n
o
wled
g
e
o
n
d
u
p
licate
co
d
e
(
wh
ich
o
f
ten
is
lis
ted
as
a
co
n
f
er
e
n
ce
to
p
ic
o
n
its
o
wn
)
,
wh
ile
o
th
er
s
h
av
e
a
m
o
r
e
b
alan
ce
d
d
is
tr
ib
u
tio
n
am
o
n
g
o
th
e
r
s
m
ells
.
T
h
e
s
tu
d
y
o
f
Misb
h
au
d
d
i
n
an
d
Als
h
ay
eb
[
9
]
p
r
o
v
id
ed
an
o
v
er
v
iew
o
f
ex
is
tin
g
r
esear
ch
in
th
e
f
ield
o
f
m
o
d
el
r
ef
ac
to
r
i
n
g
.
A
to
tal
o
f
3
,
2
9
5
ar
ticles,
r
elate
d
to
t
h
e
f
ield
o
f
u
n
if
ied
m
o
d
elin
g
lan
g
u
ag
e
(
UM
L
)
m
o
d
el
r
ef
ac
to
r
in
g
,
wer
e
ex
tr
ac
ted
f
r
o
m
well
-
k
n
o
wn
elec
tr
o
n
ic
d
at
ab
ases
.
A
m
u
lti
-
s
tag
e
s
elec
tio
n
p
r
o
ce
s
s
was
u
s
ed
to
en
s
u
r
e
p
r
o
p
er
i
n
clu
s
io
n
o
f
r
elev
an
t
s
tu
d
ies
f
o
r
r
e
v
iew
an
d
an
aly
s
is
.
Nin
ety
-
f
o
u
r
p
r
i
m
ar
y
s
tu
d
ies
wer
e
ev
en
tu
ally
s
elec
ted
a
n
d
an
aly
z
ed
.
T
h
e
r
esu
lts
s
h
o
wed
th
at
a
f
ew
q
u
ality
tec
h
n
iq
u
es
a
n
d
ap
p
r
o
ac
h
es
h
a
v
e
b
ee
n
p
r
o
p
o
s
ed
in
th
is
ar
ea
,
b
u
t it
s
till
h
as so
m
e
im
p
o
r
tan
t
o
p
en
is
s
u
es a
n
d
lim
itatio
n
s
to
b
e
a
d
d
r
e
s
s
ed
in
f
u
tu
r
e.
AlDallal
[
1
0
]
f
o
cu
s
ed
o
n
th
e
id
en
tific
atio
n
o
f
r
e
f
ac
to
r
in
g
o
p
p
o
r
tu
n
ities
wh
er
e
m
o
r
e
atten
tio
n
r
ef
ac
to
r
in
g
o
p
p
o
r
tu
n
ities
ar
e
ex
p
lo
r
ed
.
T
h
eir
r
esu
lts
s
h
o
wed
“
ex
tr
ac
t
class
”
an
d
“m
o
v
e
m
eth
o
d
”
wer
e
f
o
u
n
d
to
b
e
t
h
e
m
o
s
t
f
r
eq
u
e
n
tly
c
o
n
s
id
er
ed
r
ef
ac
to
r
in
g
ac
tiv
ities
.
T
h
e
r
esu
lts
s
h
o
w
th
at
r
esear
c
h
er
s
u
s
e
s
ix
p
r
im
ar
y
ex
is
tin
g
ap
p
r
o
ac
h
es
to
id
e
n
tify
r
ef
ac
to
r
in
g
o
p
p
o
r
tu
n
ities
an
d
s
ix
ap
p
r
o
ac
h
es
to
em
p
ir
ically
ev
alu
ate
th
e
id
en
tific
atio
n
tech
n
i
q
u
es.
Aze
em
et
a
l.
[
1
1
]
p
r
esen
ted
a
s
y
s
tem
atic
liter
atu
r
e
r
ev
iew
s
tu
d
y
o
n
m
ac
h
in
e
lear
n
i
n
g
tech
n
iq
u
es
f
o
r
co
d
e
s
m
ell
d
etec
tio
n
.
Aze
em
et
a
l.
an
aly
ze
d
p
ap
er
s
p
u
b
lis
h
ed
b
etwe
en
2
0
0
0
an
d
2
0
1
7
.
T
h
e
r
esu
lts
s
h
o
wed
th
at
g
o
d
class
,
lo
n
g
m
eth
o
d
,
f
u
n
ctio
n
al
d
ec
o
m
p
o
s
itio
n
,
an
d
s
p
ag
h
etti
co
d
e
h
av
e
b
ee
n
h
e
av
ily
co
n
s
id
er
ed
in
th
e
liter
atu
r
e.
Dec
is
io
n
tr
ee
s
an
d
s
u
p
p
o
r
t
v
ec
to
r
m
ac
h
in
es
ar
e
th
e
m
o
s
t
co
m
m
o
n
ly
u
s
e
d
m
ac
h
in
e
lear
n
in
g
alg
o
r
ith
m
s
f
o
r
co
d
e
s
m
ell
d
etec
tio
n
.
T
h
e
r
ev
iew
p
ap
er
p
r
esen
ted
b
y
Ab
u
Hass
an
et
a
l.
[
1
2
]
id
en
tifie
d
1
4
5
s
tu
d
ies
r
elate
d
to
s
m
ell
d
etec
tio
n
in
s
o
f
twar
e
d
esig
n
a
n
d
co
d
e.
Ab
u
Hass
an
et
a
l.
ad
d
r
ess
ed
s
ev
er
al
q
u
esti
o
n
s
r
elate
d
to
th
e
a
n
aly
s
is
o
f
th
e
ex
is
tin
g
s
m
ell
d
etec
tio
n
t
ec
h
n
iq
u
es
in
te
r
m
s
o
f
a
b
s
tr
ac
tio
n
lev
el
(
d
esig
n
o
r
co
d
e
)
,
ta
r
g
eted
s
m
ells
,
u
s
ed
m
etr
ics,
im
p
lem
en
tatio
n
,
a
n
d
v
alid
atio
n
.
T
h
e
r
esu
lts
s
h
o
wed
th
at
5
7
%
o
f
t
h
e
s
tu
d
ie
s
d
id
n
o
t
u
s
e
an
y
p
er
f
o
r
m
an
ce
m
ea
s
u
r
es,
4
1
% o
f
th
em
o
m
itted
d
etails o
n
th
e
t
ar
g
eted
p
r
o
g
r
a
m
m
in
g
la
n
g
u
a
g
e,
an
d
th
e
d
etec
tio
n
tech
n
iq
u
es we
r
e
n
o
t v
alid
ated
in
1
4
% o
f
t
h
ese
s
tu
d
ies.
T
h
e
s
tu
d
y
o
f
R
eis
et
a
l.
[
1
3
]
aim
ed
to
id
en
tif
y
th
e
m
ai
n
co
d
e
s
m
ells
d
etec
tio
n
tech
n
iq
u
e
s
an
d
to
o
ls
d
is
cu
s
s
ed
in
th
e
liter
atu
r
e,
an
d
to
an
aly
ze
to
w
h
ich
ex
ten
t
v
is
u
al
tech
n
iq
u
es h
a
v
e
b
ee
n
ap
p
li
ed
to
s
u
p
p
o
r
t c
o
d
e
s
m
ell
d
etec
tio
n
.
T
h
e
r
esu
lts
s
h
o
wed
th
at
m
o
s
t
u
s
ed
ap
p
r
o
a
ch
es
to
co
d
e
s
m
ells
d
etec
tio
n
ar
e
s
ea
r
ch
-
b
ased
(
3
0
.
1
%),
m
etr
ic
-
b
ased
(
2
4
.
1
%),
an
d
s
y
m
p
to
m
-
b
ased
ap
p
r
o
ac
h
es
(
1
9
.
3
%).
Mo
s
t
o
f
th
e
r
ev
iewe
d
s
tu
d
ies
(
8
3
.
1
%)
u
s
ed
o
p
e
n
-
s
o
u
r
ce
s
o
f
twar
e,
with
th
e
jav
a
lan
g
u
a
g
e
o
cc
u
p
y
i
n
g
t
h
e
f
i
r
s
t
p
o
s
itio
n
(
7
7
.
1
%).
I
n
ter
m
s
o
f
co
d
e
s
m
ells
,
g
o
d
class
(
5
1
.
8
%),
f
ea
tu
r
e
e
n
v
y
(
3
3
.
7
%),
a
n
d
lo
n
g
m
eth
o
d
(
2
6
.
5
%)
a
r
e
th
e
m
o
s
t c
o
v
er
ed
o
n
es.
3.
B
ACK
G
RO
UND
T
h
is
s
ec
tio
n
p
r
o
v
id
es
co
m
p
r
e
h
en
s
iv
e
r
esear
ch
b
ac
k
g
r
o
u
n
d
r
elate
d
to
co
d
e
s
m
ells
an
d
p
r
esen
ts
th
e
ca
u
s
es
o
f
co
d
e
s
m
ells
,
im
p
ac
t
o
f
co
d
e
s
m
ells
,
an
d
k
e
y
co
n
ce
p
ts
r
elev
an
t
to
th
e
r
esear
ch
to
p
ic.
R
esear
ch
er
s
f
o
cu
s
ed
o
n
in
v
esti
g
atin
g
th
e
co
n
s
eq
u
en
ce
s
o
f
co
d
e
s
m
ells
an
d
h
o
w
th
ese
co
d
e
s
m
ells
ca
n
b
e
d
etec
ted
to
ad
d
r
ess
th
eir
im
p
ac
t
o
n
s
o
f
tw
ar
e
q
u
ality
.
B
ased
o
n
th
e
a
v
ai
lab
le
liter
atu
r
e,
th
e
k
ey
ca
u
s
es
o
f
co
d
e
s
m
ells
ca
n
b
e
s
u
m
m
ar
ized
as f
o
llo
ws:
a.
Desig
n
p
atter
n
s
im
p
ac
t:
th
e
r
elatio
n
s
h
ip
b
etwe
en
d
esig
n
p
atter
n
s
an
d
co
d
e
s
m
ells
is
s
til
l
n
o
t
wel
l
in
v
esti
g
ated
.
T
h
e
im
p
lem
en
ta
tio
n
o
f
d
esig
n
p
atter
n
in
s
tan
c
es
in
th
e
s
o
u
r
ce
c
o
d
e
lead
s
t
o
m
o
r
e
co
u
p
led
class
es
an
d
in
cr
ea
s
e
th
e
n
u
m
b
er
o
f
class
es.
So
m
e
s
tu
d
ies
s
u
g
g
est
th
at
d
esig
n
p
atter
n
s
,
in
g
en
er
al,
r
e
d
u
ce
th
e
ch
an
ce
o
f
co
d
e
s
m
ells
.
b.
So
f
twar
e
d
ev
elo
p
e
r
s
ex
p
er
ie
n
ce
:
th
e
s
k
ills
an
d
th
e
ex
p
e
r
ien
ce
o
f
s
o
f
twar
e
d
e
v
elo
p
e
r
s
p
lay
a
r
o
le
i
n
im
p
lem
en
tin
g
a
p
r
o
g
r
am
th
at
s
u
f
f
er
s
f
r
o
m
co
d
e
s
m
ells
.
T
h
e
s
tu
d
y
o
f
[
1
4
]
r
e
v
ea
ls
th
at
3
2
%
o
f
s
o
f
twar
e
d
ev
elo
p
er
s
ar
e
awa
r
e
ab
o
u
t c
o
d
e
s
m
ells
.
c.
L
ac
k
o
f
c
o
d
e
s
m
ell
d
etec
tio
n
t
o
o
ls
d
u
r
in
g
s
o
f
twar
e
d
ev
elo
p
m
en
t:
m
o
s
t
o
f
s
o
f
twar
e
d
ev
elo
p
m
en
t
t
o
o
ls
an
d
f
r
am
ewo
r
k
s
ar
e
n
o
t
s
u
p
p
o
r
tin
g
au
to
m
atic
co
d
e
s
m
ell
d
etec
tio
n
d
u
r
in
g
th
e
d
e
v
elo
p
m
e
n
t p
r
o
ce
s
s
.
T
h
e
s
tu
d
y
o
f
[
1
4
]
an
d
[
1
5
]
r
ev
ea
l
th
at
th
e
d
ev
elo
p
e
r
s
f
o
cu
s
o
n
th
e
f
u
n
ctio
n
ality
o
f
th
e
s
o
f
twar
e
an
d
ig
n
o
r
e
th
e
s
ig
n
s
o
f
co
d
e
s
m
ells
d
u
r
in
g
t
h
e
d
ev
e
lo
p
m
en
t p
r
o
ce
s
s
.
Evaluation Warning : The document was created with Spire.PDF for Python.
I
n
t J E
lec
&
C
o
m
p
E
n
g
I
SS
N:
2088
-
8
7
0
8
A
s
ystema
tic
r
ev
ie
w
o
n
s
o
ftw
a
r
e
co
d
e
s
mells
(
Mo
h
a
mme
d
Gh
a
z
i A
l
-
Ob
eid
a
lla
h
)
3013
Sev
er
al
s
tu
d
ies
h
av
e
b
ee
n
p
r
esen
ted
in
t
h
e
liter
atu
r
e
to
in
v
esti
g
ate
th
e
im
p
ac
t
o
f
co
d
e
s
m
ells
o
n
s
o
f
twar
e
p
r
o
g
r
am
s
[
1
6
]
–
[
2
5
]
.
T
h
ese
s
tu
d
ies
m
ain
ly
s
u
m
m
ar
ized
th
e
im
p
ac
t
o
f
c
o
d
e
s
m
ell
in
to
two
k
ey
co
n
s
eq
u
en
ce
s
.
T
h
e
f
ir
s
t
co
n
s
eq
u
en
ce
is
th
e
in
cr
ea
s
e
o
f
c
o
d
e
b
u
g
s
o
r
d
ef
ec
ts
in
th
e
s
o
f
twar
e.
C
lo
n
in
g
o
r
d
u
p
licatin
g
co
d
e
in
cr
ea
s
es
th
e
ch
an
ce
s
o
f
s
o
f
twar
e
b
u
g
s
[
1
7
]
.
Fo
r
ex
am
p
le,
t
h
e
s
tu
d
y
o
f
[
2
3
]
s
u
g
g
ested
t
h
at
co
d
e
d
u
p
licatio
n
d
id
n
o
t
p
la
y
a
k
ey
r
o
le
i
n
p
r
o
d
u
cin
g
b
u
g
s
in
t
h
e
s
o
f
twar
e.
T
h
e
s
tu
d
y
al
s
o
claim
th
at
co
d
e
clo
n
in
g
d
o
es
n
o
t
d
ev
elo
p
n
e
w
b
u
g
s
.
T
h
e
s
tu
d
y
o
f
L
i
an
d
Sh
atn
awi
[
2
0
]
id
en
tifie
d
th
e
r
elatio
n
s
h
ip
b
etwe
en
co
d
e
s
m
ells
an
d
class
er
r
o
r
p
r
o
b
a
b
ilit
y
.
T
h
e
s
tu
d
y
c
o
n
cl
u
d
ed
th
at
s
h
o
tg
u
n
s
u
r
g
er
y
,
g
o
d
class
,
an
d
g
o
d
m
eth
o
d
s
h
av
e
a
n
eg
ativ
e
im
p
a
ct
o
n
th
e
class
er
r
o
r
p
r
o
b
ab
ilit
y
.
Ma
in
tain
in
g
s
o
f
twar
e
in
v
o
lv
e
s
ef
f
o
r
ts
to
ad
d
n
ew
f
u
n
ctio
n
s
o
r
f
ea
tu
r
es
an
d
m
o
d
if
y
in
g
t
h
e
co
d
e
to
f
u
lf
il
n
ew
r
eq
u
ir
em
en
ts
.
T
h
e
s
tu
d
y
o
f
[
1
6
]
s
h
o
wed
h
o
w
th
e
lack
o
f
d
esig
n
h
e
u
r
is
tics
af
f
ec
ts
s
o
f
twar
e
m
ain
tain
ab
ilit
y
.
T
h
e
s
tu
d
y
also
co
m
p
ar
ed
b
etwe
en
two
v
er
s
io
n
s
o
f
an
im
p
lem
en
tatio
n
(
w
ith
g
o
d
class
s
m
el
l
an
d
with
o
u
t
g
o
d
class
s
m
ell
)
.
T
h
e
s
tu
d
y
co
n
cl
u
d
ed
th
at
h
i
g
h
co
h
esio
n
an
d
lo
w
co
u
p
lin
g
in
s
o
f
twar
e
p
r
o
g
r
a
m
s
af
f
ec
t th
e
m
ain
tain
a
b
ilit
y
ef
f
o
r
ts
.
T
h
e
s
ec
o
n
d
im
p
ac
t
is
th
e
in
cr
ea
s
e
in
th
e
m
ain
ten
a
n
ce
ef
f
o
r
t
.
Sev
er
al
h
y
p
o
th
eses
wer
e
in
tr
o
d
u
ce
d
to
r
elate
th
e
im
p
ac
t
o
f
co
d
e
s
m
ells
wi
th
s
o
f
twar
e
ch
an
g
ea
b
ilit
y
.
T
h
e
co
n
tin
u
o
u
s
m
o
d
if
icati
o
n
s
o
f
th
e
p
r
o
g
r
am
in
cr
ea
s
e
th
e
c
o
d
e
s
m
ell.
Sm
ell
class
es
ev
o
lv
ed
m
o
r
e
f
r
eq
u
e
n
tly
co
m
p
ar
ed
to
n
o
n
-
s
m
ell
cl
ass
es.
T
h
e
s
tu
d
y
o
f
[
1
7
]
in
v
esti
g
ated
th
e
im
p
ac
t
o
f
co
d
e
s
m
ells
o
n
s
o
f
twar
e
ch
an
g
e
p
r
o
n
en
ess
.
T
h
e
s
tu
d
y
f
o
u
n
d
th
at
lo
n
g
class
an
d
Me
s
s
ag
e
C
h
ain
a
r
e
th
e
m
o
s
t
f
r
eq
u
e
n
t
s
m
ells
in
s
ev
er
al
r
elea
s
es
o
f
E
clip
s
e
a
n
d
Azu
r
eu
s
,
an
d
ea
ch
n
ew
r
elea
s
e
in
tr
o
d
u
ce
s
s
o
m
e
n
ew
s
m
ells
wh
ile
r
em
o
v
in
g
t
h
e
o
ld
e
r
s
m
ells
.
T
h
e
s
tu
d
y
o
f
[
2
4
]
p
r
esen
ted
an
em
p
ir
ical
s
tu
d
y
th
at
in
v
esti
g
ated
in
ter
-
s
m
ell
r
elatio
n
s
an
d
th
eir
ef
f
ec
ts
o
n
th
e
in
cid
e
n
ce
o
f
m
a
in
ten
an
ce
p
r
o
b
lem
s
.
B
y
an
aly
zin
g
h
o
w
p
r
o
f
ess
io
n
al
d
e
v
elo
p
er
s
co
n
d
u
cted
task
s
o
n
f
o
u
r
d
if
f
e
r
en
t
s
y
s
tem
s
,
t
h
e
s
tu
d
y
f
o
u
n
d
em
p
ir
ical
e
v
id
en
ce
th
at
ce
r
tain
i
n
ter
-
s
m
ell
r
elatio
n
s
wer
e
ass
o
ciate
d
with
p
r
o
b
lem
s
d
u
r
in
g
m
ai
n
ten
an
ce
.
An
o
th
e
r
s
tu
d
y
o
f
[
2
5
]
in
v
esti
g
ates
th
e
e
f
f
ec
ts
o
f
co
d
e
s
m
ells
at
th
e
ac
tiv
ity
lev
el.
Six
p
r
o
f
e
s
s
io
n
al
d
ev
elo
p
er
s
wer
e
h
ir
ed
to
p
er
f
o
r
m
th
r
ee
m
ain
ten
a
n
ce
task
s
o
n
f
o
u
r
f
u
n
ctio
n
ally
eq
u
iv
alen
t
J
av
a
Sy
s
tem
s
.
E
ac
h
d
ev
elo
p
er
p
er
f
o
r
m
s
two
m
ain
ten
an
ce
task
s
.
T
h
e
lo
g
s
o
f
th
e
d
ev
elo
p
er
s
wer
e
tr
ac
ed
,
a
n
d
a
n
an
n
o
tatio
n
ap
p
r
o
ac
h
was
d
e
f
in
ed
to
ass
ess
if
co
d
e
s
m
ells
im
p
ac
t
m
ain
ten
a
n
ce
ac
tiv
ities
.
T
h
e
s
tu
d
y
s
h
o
wed
t
h
at
d
if
f
er
e
n
t
co
d
e
s
m
ells
af
f
ec
t
d
if
f
er
en
t
ac
tiv
ity
ef
f
o
r
t.
T
h
e
tech
n
iq
u
es
u
s
ed
to
d
etec
t
co
d
e
s
m
ells
in
th
e
liter
atu
r
e
[
3
]
–
[
1
2
]
,
[
1
3
]
ca
n
b
e
g
r
o
u
p
ed
in
to
f
o
u
r
k
ey
ca
teg
o
r
ies.
C
o
d
e
s
m
ells
d
etec
ted
b
y
d
if
f
e
r
en
t
d
etec
tio
n
ap
p
r
o
ac
h
es
ar
e
p
r
esen
ted
i
n
T
ab
le
1
.
T
h
e
d
etec
tio
n
tech
n
iq
u
es
ar
e
g
r
o
u
p
ed
b
ased
o
n
th
e
u
s
ed
d
etec
tio
n
m
eth
o
d
in
to
f
o
u
r
k
e
y
ca
teg
o
r
ies
[
2
6
]
,
[
2
7
]
:
a.
Me
tr
ics
-
b
ased
ap
p
r
o
ac
h
es
u
s
e
s
o
f
twar
e
m
etr
ics
s
u
ch
as
“
lin
es
o
f
co
d
e”
,
“c
o
u
p
lin
g
”
b
etwe
en
o
b
jects,
“c
o
h
esio
n
”,
a
n
d
“d
e
p
th
o
f
in
h
er
itan
ce
tr
ee
”
to
d
etec
t
co
d
e
s
m
ells
b
ased
o
n
ce
r
tain
th
r
esh
o
ld
v
alu
es.
T
h
e
s
elec
tio
n
o
f
th
r
esh
o
ld
v
alu
es
af
f
ec
ts
th
e
o
v
er
all
ac
cu
r
ac
y
o
f
th
e
d
etec
tio
n
p
r
o
ce
s
s
.
So
f
twar
e
m
etr
ics
h
elp
ed
to
d
etec
t
th
e
f
o
llo
win
g
co
d
e
s
m
ells
:
r
ef
u
s
ed
b
e
q
u
e
s
t,
d
ata
clu
m
p
s
,
s
h
o
tg
u
n
s
u
r
g
er
y
,
lar
g
e
class
,
lo
n
g
m
eth
o
d
,
an
d
lazy
class
.
Sin
ce
th
er
e
is
n
o
u
n
i
f
ied
b
en
c
h
m
ar
k
to
s
et
th
e
th
r
esh
o
ld
v
alu
es,
th
is
ap
p
r
o
ac
h
is
s
till
n
o
t p
r
ac
tical,
in
ter
m
s
o
f
ac
cu
r
ac
y
,
to
d
etec
t c
o
d
e
s
m
e
lls
.
b.
Sear
ch
-
b
ased
ap
p
r
o
ac
h
es:
th
ese
ap
p
r
o
ac
h
es
u
s
e
d
if
f
er
e
n
t
s
ea
r
ch
alg
o
r
ith
m
s
to
d
etec
t
c
o
d
e
s
m
ells
in
th
e
s
o
u
r
ce
co
d
e.
Heu
r
is
tic
s
ea
r
ch
alg
o
r
ith
m
s
wer
e
u
s
ed
to
ex
tr
ac
t
r
u
les
th
at
ca
n
b
e
u
s
ed
d
u
r
in
g
th
e
s
ea
r
ch
p
r
o
ce
s
s
.
c.
R
u
le
b
ased
ap
p
r
o
ac
h
es:
r
u
le
-
b
ased
s
y
s
tem
s
co
n
v
er
t
t
h
e
p
r
o
b
lem
in
to
a
s
et
o
f
co
n
d
itio
n
ac
tio
n
r
u
les.
I
f
-
th
en
r
u
les
ar
e
wid
ely
u
s
ed
to
f
ee
d
an
in
f
er
en
ce
en
g
i
n
e
eq
u
ip
p
ed
with
a
wo
r
k
in
g
k
n
o
w
led
g
e
ab
o
u
t
th
e
p
r
o
b
lem
.
So
f
twar
e
m
etr
ics
wer
e
u
s
ed
to
ca
p
tu
r
e
k
n
o
wled
g
e
an
d
th
e
av
ailab
le
in
f
o
r
m
a
tio
n
.
Mo
r
eo
v
er
,
r
u
le
-
b
ased
a
p
p
r
o
ac
h
es
d
escr
ib
e
co
d
e
s
m
ell
s
y
m
p
to
m
s
an
d
p
r
o
d
u
ce
r
u
les
th
at
will
b
e
tr
an
s
lated
in
to
d
etec
tio
n
alg
o
r
it
h
m
s
to
id
en
tif
y
co
d
e
s
m
ells
.
d.
Ma
ch
in
e
lear
n
i
n
g
ap
p
r
o
ac
h
es:
th
ese
ap
p
r
o
ac
h
es
u
s
e
a
s
et
o
f
p
r
ed
icto
r
s
f
o
r
a
m
ac
h
in
e
lear
n
in
g
class
if
ier
to
r
ea
ch
a
d
ec
is
io
n
.
Ma
ch
in
e
lear
n
in
g
a
p
p
r
o
ac
h
es
d
ep
en
d
o
n
th
e
q
u
ality
o
f
a
b
alan
ce
d
d
at
aset
an
d
o
n
th
e
q
u
ality
o
f
th
e
tr
ain
in
g
m
o
d
el.
Fo
r
ex
am
p
le,
to
d
etec
t
co
d
e
s
m
ells
,
th
e
tr
ain
in
g
m
o
d
el
ca
n
lear
n
f
r
o
m
s
tan
d
ar
d
d
esig
n
p
r
ac
tices a
n
d
co
m
p
ar
ed
to
d
e
v
elo
p
er
co
d
in
g
p
r
ac
tice
[
1
7
]
.
T
ab
le
1
.
C
ateg
o
r
ies o
f
co
d
e
s
m
ells
C
a
t
e
g
o
r
y
C
o
d
e
sme
l
l
B
l
o
a
t
e
r
s
Lo
n
g
p
a
r
a
me
t
e
r
l
i
s
t
,
l
o
n
g
met
h
o
d
,
l
a
r
g
e
c
l
a
ss,
d
a
t
a
c
l
u
m
p
s,
a
n
d
p
r
i
mi
t
i
v
e
o
b
sess
i
o
n
O
b
j
e
c
t
o
r
i
e
n
t
e
d
a
b
u
s
e
r
s
Te
mp
o
r
a
r
y
f
i
e
l
d
s,
sw
i
t
c
h
st
a
t
e
me
n
t
,
r
e
f
u
se
d
b
e
q
u
e
s
t
,
p
a
r
a
l
l
e
l
i
n
h
e
r
i
t
a
n
c
e
h
i
e
r
a
r
c
h
i
e
s
,
a
n
d
a
l
t
e
r
n
a
t
i
v
e
c
l
a
ss
e
s w
i
t
h
d
i
f
f
e
r
e
n
t
i
n
t
e
r
f
a
c
e
s
C
h
a
n
g
e
p
r
e
v
e
n
t
e
r
s
S
h
o
t
g
u
n
s
u
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a
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a
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c
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d
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p
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c
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t
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c
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d
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Evaluation Warning : The document was created with Spire.PDF for Python.
I
SS
N
:
2
0
8
8
-
8
7
0
8
I
n
t J E
lec
&
C
o
m
p
E
n
g
,
Vo
l.
15
,
No
.
3
,
J
u
n
e
20
25
:
3
0
1
0
-
3
0
2
7
3014
4.
M
E
T
H
O
D
T
h
is
s
y
s
tem
atic
r
ev
iew
r
e
s
e
ar
ch
aim
s
to
co
n
d
u
ct
a
f
ai
r
an
d
co
m
p
r
eh
en
s
iv
e
ev
alu
atio
n
an
d
in
ter
p
r
etatio
n
o
f
av
ailab
le
r
esear
ch
p
u
b
lis
h
ed
f
r
o
m
2
0
0
1
to
2
0
2
3
in
th
e
f
ield
o
f
c
o
d
e
s
m
ell
d
etec
tio
n
.
T
o
th
e
b
est
o
f
o
u
r
k
n
o
wled
g
e,
less
th
an
1
0
s
tu
d
ies
wer
e
p
u
b
lis
h
ed
b
ef
o
r
e
2
0
0
1
th
at
f
o
cu
s
o
n
s
o
f
twar
e
co
d
e
s
m
ell.
T
h
e
g
u
id
elin
es
s
u
g
g
ested
b
y
[
1
8
]
,
[
2
8
]
,
a
n
d
[
2
9
]
–
[
3
1
]
wer
e
f
o
llo
wed
in
u
n
d
er
tak
i
n
g
th
is
s
y
s
tem
atic
r
ev
iew.
T
h
e
f
ir
s
t
p
h
ase
o
f
th
e
r
esear
ch
in
v
o
lv
ed
p
lan
n
i
n
g
th
e
r
e
v
iew,
wh
ich
was
f
u
r
th
er
d
iv
id
ed
in
to
d
eter
m
in
in
g
th
e
n
ec
ess
ity
f
o
r
a
r
ev
iew
,
d
ev
elo
p
in
g
th
e
r
esear
ch
q
u
esti
o
n
s
,
a
n
d
d
escr
ib
in
g
th
e
s
ea
r
ch
ap
p
r
o
ac
h
to
f
in
d
r
elev
a
n
t
r
esear
ch
p
ap
e
r
s
.
T
h
e
s
ec
o
n
d
p
h
ase
in
v
o
lv
e
d
co
n
d
u
ctin
g
th
e
r
ev
iew,
wh
ich
was
s
u
b
d
i
v
id
ed
in
to
d
e
f
in
in
g
t
h
e
ap
p
r
o
p
r
iate
r
esear
ch
s
elec
tio
n
cr
iter
ia,
in
cl
u
d
in
g
th
e
in
cl
u
s
io
n
/ex
clu
s
io
n
cr
iter
ia,
d
ev
e
lo
p
in
g
t
h
e
q
u
ality
ev
alu
atio
n
r
u
les
to
f
ilter
r
esear
ch
p
u
b
licatio
n
s
,
co
n
s
tr
u
ctin
g
th
e
d
ata
e
x
tr
ac
tio
n
s
tr
ateg
y
t
o
ad
d
r
ess
th
e
s
tu
d
y
o
b
jectiv
es,
an
d
th
e
n
s
y
n
t
h
esizin
g
th
e
d
ata
tak
en
f
r
o
m
t
h
e
p
u
b
licatio
n
s
.
T
h
e
th
ir
d
p
h
ase
o
f
th
e
r
esear
ch
was
th
e
r
ep
o
r
tin
g
p
h
ase.
4
.
1
.
P
l
a
nn
ing
ph
a
s
e
T
h
e
ar
ea
o
f
co
d
e
s
m
ell
r
ese
ar
ch
is
ex
p
er
ien
cin
g
r
a
p
id
g
r
o
wth
,
an
d
th
e
r
e
ar
e
s
ev
er
al
co
d
e
s
m
ell
d
etec
tio
n
tech
n
iq
u
es
p
r
esen
te
d
in
th
e
liter
atu
r
e.
T
h
er
ef
o
r
e,
th
er
e
is
a
n
ee
d
to
s
u
m
m
ar
iz
e
th
e
f
in
d
in
g
s
an
d
o
u
tco
m
es
o
f
p
r
ev
io
u
s
r
esear
ch
an
d
id
en
tif
y
th
e
latest
d
ev
elo
p
m
en
ts
in
th
e
f
ield
.
T
h
e
s
y
n
t
h
esized
in
f
o
r
m
atio
n
will
h
elp
in
th
e
id
en
tific
atio
n
o
f
r
esear
ch
p
atter
n
s
an
d
th
e
d
e
v
elo
p
m
en
t
o
f
s
tatis
tic
s
th
at
wi
ll
in
tu
r
n
s
h
ed
lig
h
t
o
n
lim
itatio
n
s
an
d
g
ap
s
in
th
e
liter
atu
r
e,
in
ad
d
itio
n
to
c
u
r
r
e
n
t
an
d
f
u
tu
r
e
d
ir
ec
tio
n
s
o
f
r
esear
ch
.
Acc
o
r
d
i
n
g
ly
,
th
is
r
ev
iew
will u
ltima
tely
p
r
o
v
id
e
an
s
wer
s
to
th
e
f
o
llo
win
g
r
esear
ch
q
u
esti
o
n
s
:
R
Q1
: Wh
at
is
th
e
d
is
tr
ib
u
tio
n
o
f
s
tu
d
ies p
er
y
e
ar
in
th
e
co
n
te
x
t o
f
th
e
c
o
d
e
s
m
ell
d
etec
tio
n
?
R
Q2
: Wh
at
ar
e
th
e
ca
teg
o
r
ies o
f
p
u
b
licatio
n
s
in
clu
d
e
d
in
th
i
s
r
ev
iew
r
esear
ch
?
R
Q3
:
W
h
at
is
th
e
d
is
tr
ib
u
tio
n
o
f
th
e
s
tu
d
ies
in
clu
d
e
d
in
th
is
r
ev
iew,
ca
teg
o
r
ized
b
y
th
e
em
p
lo
y
ed
co
d
e
s
m
ell
d
etec
tio
n
tech
n
iq
u
e?
R
Q4
:
W
h
at
p
r
o
g
r
a
m
m
in
g
lan
g
u
ag
es
ar
e
e
m
p
lo
y
e
d
b
y
v
ar
io
u
s
co
d
e
s
m
ell
d
etec
tio
n
tech
n
iq
u
es
in
th
e
in
clu
d
e
d
s
tu
d
ies?
R
Q5
: Wh
at
s
u
b
ject
s
y
s
tem
s
w
er
e
u
s
ed
to
v
alid
ate
co
d
e
s
m
el
l d
etec
tio
n
tech
n
iq
u
es in
th
e
in
clu
d
ed
s
tu
d
ies?
R
Q6
: Wh
at
co
d
e
s
m
ells
wer
e
d
etec
ted
b
y
v
ar
io
u
s
tech
n
iq
u
e
s
in
th
e
in
clu
d
ed
s
tu
d
ies?
Ou
r
s
ea
r
ch
p
r
o
ce
s
s
is
co
m
p
r
eh
en
s
iv
e
an
d
co
v
e
r
s
th
e
wh
o
le
s
p
ec
tr
u
m
r
elate
d
to
th
e
ar
ea
o
f
th
e
co
d
e
s
m
ell
d
etec
tio
n
tech
n
iq
u
es.
T
h
e
s
ea
r
ch
q
u
er
ies u
s
ed
t
o
r
etr
iev
e
t
h
e
r
elate
d
p
r
im
ar
y
s
tu
d
ies ar
e
as
f
o
llo
ws:
a.
Sear
ch
Qu
er
y
1
:
co
d
e
AND
s
m
ells
;
b.
Sear
ch
Qu
er
y
2
:
b
ad
AND
s
m
ells
;
c.
Sear
ch
Qu
er
y
3
:
an
tip
atter
n
;
d.
Sear
ch
Qu
er
y
4
: (
d
etec
t
OR
id
en
tify
OR
r
ec
o
v
er
)
AND
s
m
ells
.
W
e
ap
p
lied
o
u
r
ad
o
p
ted
s
e
ar
ch
q
u
er
ies
to
well
-
k
n
o
w
n
r
ep
u
ta
b
le
s
cien
tific
d
ata
b
ases
.
T
h
ese
d
atab
ases
in
clu
d
e
Sp
r
in
g
er
,
AC
M,
I
E
E
E
,
s
cien
ce
d
ir
ec
t
,
an
d
Go
o
g
le
Sch
o
lar
.
B
ased
o
n
th
e
s
ea
r
ch
ter
m
s
m
en
tio
n
ed
ab
o
v
e
an
d
u
s
in
g
th
e
s
p
ec
if
ied
p
e
r
io
d
(
2
0
0
1
to
2
0
2
3
)
,
6
8
9
p
u
b
licatio
n
s
wer
e
in
i
tially
r
etr
iev
ed
.
1
9
3
wer
e
id
en
tifie
d
as
d
u
p
licates
am
o
n
g
th
e
d
if
f
er
en
t
lib
r
ar
ies
an
d
r
em
o
v
ed
.
Hen
ce
,
4
9
6
p
u
b
licatio
n
s
wer
e
k
ep
t
f
o
r
th
e
n
ex
t p
h
ase.
4
.
2
.
Rev
iew
ph
a
s
e
Dif
f
er
en
t
ap
p
r
o
ac
h
es
h
av
e
b
e
en
in
tr
o
d
u
ce
d
b
y
r
esear
ch
er
s
to
d
etec
t
co
d
e
s
m
ells
at
th
e
s
o
u
r
ce
co
d
e
lev
el.
T
o
s
elec
t
th
e
p
r
im
a
r
y
s
tu
d
ies
th
at
will
b
e
in
clu
d
ed
in
th
is
r
ev
iew,
s
ev
er
al
in
clu
s
io
n
an
d
ex
cl
u
s
io
n
cr
iter
ia
wer
e
id
en
tifie
d
.
T
h
e
in
clu
s
io
n
cr
iter
ia
ca
n
b
e
s
u
m
m
ar
ized
as
f
o
llo
ws:
i)
P
u
b
licatio
n
s
m
u
s
t
b
e
p
u
b
lis
h
ed
f
r
o
m
2
0
0
1
till
Au
g
u
s
t 2
0
2
3
;
ii)
Pu
b
licatio
n
s
m
u
s
t
b
e
p
u
b
lis
h
ed
in
a
jo
u
r
n
al,
co
n
f
er
en
ce
p
r
o
ce
e
d
in
g
,
b
o
o
k
ch
ap
te
r
,
wo
r
k
s
h
o
p
o
r
s
y
m
p
o
s
iu
m
;
iii)
Pu
b
licatio
n
s
m
u
s
t
p
r
o
p
o
s
e/d
is
cu
s
s
at
lea
s
t
o
n
e
co
d
e
s
m
ell
d
etec
tio
n
tech
n
iq
u
e
; a
n
d
iv
)
E
x
is
ten
ce
o
f
p
r
ac
tical
e
x
p
er
im
e
n
ts
at
th
e
co
d
e
lev
el.
W
e
ex
clu
d
ed
th
e
f
o
ll
o
win
g
s
tu
d
ies:
i)
Pu
b
licatio
n
s
th
at
ar
e
wr
itten
in
a
lan
g
u
a
g
e
o
th
er
t
h
an
E
n
g
lis
h
;
ii)
Pu
b
licatio
n
s
th
at
th
eir
m
ain
f
o
cu
s
is
n
o
t
co
d
e
s
m
ells
d
etec
tio
n
;
iii)
Pu
b
licatio
n
s
th
at
ar
e
b
o
o
k
s
o
r
th
eses
;
iv
)
Pu
b
licatio
n
s
t
h
at
ar
e
p
u
b
lis
h
ed
as
r
ep
o
r
ts
;
an
d
v
)
Pu
b
lic
atio
n
s
th
at
p
r
o
p
o
s
e
co
d
e
s
m
ell
d
etec
tio
n
b
ased
o
n
th
e
d
esig
n
lev
el
n
o
t a
t th
e
c
o
d
e
lev
el.
4
.
3
.
Ana
ly
s
is
ph
a
s
e
T
h
e
co
m
p
leted
co
m
p
ilatio
n
o
f
ar
ticles
s
elec
ted
f
o
r
c
o
m
p
r
e
h
en
s
iv
e
ev
alu
atio
n
u
n
d
er
wen
t
a
r
ig
o
r
o
u
s
ex
am
in
atio
n
to
ex
t
r
ac
t
in
f
o
r
m
atio
n
ad
d
r
ess
in
g
th
e
p
r
ev
i
o
u
s
ly
s
tated
r
esear
ch
in
q
u
i
r
ies.
I
n
itially
,
we
s
tar
ted
with
6
8
9
ar
ticles.
Af
ter
r
em
o
v
in
g
d
u
p
licates
an
d
ap
p
ly
in
g
titl
e
a
n
d
a
b
s
tr
ac
t
f
i
lter
s
,
as
well
as
in
clu
s
io
n
/ex
clu
s
io
n
cr
iter
ia,
we
r
ev
iewe
d
a
to
tal
o
f
1
4
0
ar
ticles
in
f
u
ll.
Ultim
ately
,
1
1
6
ar
ticles
m
et
o
u
r
cr
iter
ia,
s
p
ec
if
ically
f
o
c
u
s
in
g
o
n
t
h
e
ex
is
ten
ce
o
f
p
r
ac
tical
ex
p
er
im
en
ts
at
t
h
e
co
d
e
le
v
el.
A
to
tal
o
f
1
1
6
p
r
im
ar
y
s
tu
d
ies
wer
e
in
clu
d
e
d
in
th
is
r
e
v
iew.
W
e
p
er
f
o
r
m
ed
a
m
an
u
al
v
alid
atio
n
o
f
th
e
r
etr
iev
ed
s
tu
d
ies
to
Evaluation Warning : The document was created with Spire.PDF for Python.
I
n
t J E
lec
&
C
o
m
p
E
n
g
I
SS
N:
2088
-
8
7
0
8
A
s
ystema
tic
r
ev
ie
w
o
n
s
o
ftw
a
r
e
co
d
e
s
mells
(
Mo
h
a
mme
d
Gh
a
z
i A
l
-
Ob
eid
a
lla
h
)
3015
en
s
u
r
e
th
at
th
e
r
etr
iev
e
d
s
tu
d
ies
r
elate
d
to
o
u
r
p
r
o
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a.
T
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e
f
i
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d
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s
a
r
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d
etailed
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s
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th
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e
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ated
in
Fig
u
r
e
1
.
Fig
u
r
e
1
.
T
h
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eq
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en
ce
o
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5.
RE
SU
L
T
S AN
D
D
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SS
I
O
N
T
h
e
th
ir
d
s
tag
e
o
f
th
is
s
y
s
tem
atic
r
ev
iew
s
tu
d
y
in
v
o
lv
ed
p
r
esen
tin
g
th
e
r
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T
h
e
f
i
n
al
lis
t
o
f
r
esear
ch
ar
ticles
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is
ed
a
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tal
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f
1
1
6
p
u
b
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s
[
3
2]
–
[
1
4
7
]
.
A
co
m
p
r
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e
n
s
iv
e
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d
t
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o
r
o
u
g
h
ex
am
in
atio
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o
f
th
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p
ap
er
s
w
as
co
n
d
u
cted
to
e
x
tr
ac
t
r
elev
a
n
t
in
f
o
r
m
atio
n
a
d
d
r
ess
in
g
th
e
r
esear
ch
q
u
esti
o
n
s
.
T
h
e
ex
tr
ac
ted
d
ata
wer
e
q
u
an
titativ
ely
d
escr
ib
ed
,
f
ac
ilit
atin
g
th
e
id
en
tific
atio
n
o
f
p
atter
n
s
in
s
tu
d
ies
co
n
d
u
cte
d
b
etwe
en
2
0
0
1
a
n
d
2
0
2
3
.
Ad
d
itio
n
ally
,
th
e
an
aly
s
is
u
n
v
eiled
b
o
th
c
o
m
m
o
n
alities
an
d
d
is
cr
ep
a
n
cies
am
o
n
g
t
h
e
s
tu
d
ies.
R
Q1
:
Wha
t is the d
is
t
r
ib
uti
o
n
o
f
s
tud
ies p
er y
ea
r
in the c
o
n
tex
t o
f
the c
o
d
e
s
m
ell
d
etec
tio
n?
T
h
e
r
etr
ie
v
ed
p
r
im
ar
y
s
tu
d
ies
in
v
o
lv
e
p
ap
e
r
s
f
r
o
m
j
o
u
r
n
als,
co
n
f
er
e
n
ce
p
r
o
ce
ed
i
n
g
s
,
b
o
o
k
ch
ap
ter
s
,
wo
r
k
s
h
o
p
s
,
an
d
s
y
m
p
o
s
iu
m
s
.
T
h
e
n
u
m
b
er
o
f
in
clu
d
ed
p
r
im
ar
y
s
tu
d
ies
p
e
r
y
ea
r
is
p
r
esen
t
ed
in
Fig
u
r
e
2
.
As
ca
n
b
e
s
ee
n
f
r
o
m
Fig
u
r
e
2
,
m
o
s
t
o
f
th
e
r
ec
en
t
p
u
b
licatio
n
s
ar
e
J
o
u
r
n
al
p
ap
e
r
s
.
I
n
2
0
1
7
,
1
1
co
n
f
er
en
ce
p
ap
e
r
s
wer
e
p
u
b
lis
h
ed
r
elate
d
to
co
d
e
s
m
ell
d
etec
tio
n
.
W
e
co
u
ld
n
o
t
f
in
d
an
y
p
a
p
er
s
r
elate
d
to
c
o
d
e
s
m
ell
d
etec
tio
n
p
u
b
lis
h
ed
in
2
0
0
3
.
R
Q2
:
Wha
t a
r
e
the c
a
teg
o
r
ies
o
f
p
ub
lica
tio
ns
inclu
d
ed
in thi
s
r
ev
ie
w
r
e
s
ea
r
ch?
Fig
u
r
e
3
s
h
o
ws
th
e
ty
p
e
o
f
p
u
b
licatio
n
s
in
clu
d
e
d
in
th
is
r
ev
iew.
As
Fig
u
r
e
3
s
h
o
ws,
m
o
s
t
o
f
th
e
in
clu
d
ed
p
r
im
ar
y
s
tu
d
ies
a
r
e
c
o
n
f
er
e
n
ce
p
r
o
ce
ed
in
g
s
(
5
0
%
o
f
th
e
p
r
im
a
r
y
s
tu
d
ies,
with
a
to
tal
o
f
5
8
s
tu
d
ies).
W
e
g
r
o
u
p
ed
th
e
p
r
im
ar
y
s
tu
d
i
es
p
u
b
lis
h
ed
in
wo
r
k
s
h
o
p
s
,
b
o
o
k
ch
a
p
ter
s
,
an
d
s
y
m
p
o
s
iu
m
s
in
to
o
n
e
ca
teg
o
r
y
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I
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20
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3016
(
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with
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t
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tu
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J
o
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r
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a
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u
r
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al
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a
p
er
s
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u
r
e
2
.
Nu
m
b
er
o
f
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clu
d
ed
s
tu
d
ies p
er
y
ea
r
Fig
u
r
e
3
.
T
y
p
e
o
f
p
u
b
licatio
n
s
R
Q3
:
Wha
t is the d
is
t
r
ib
uti
o
n
o
f
the stu
d
ies inclu
d
ed
in th
i
s
r
ev
iew
,
ca
teg
o
r
iz
ed
b
y
the e
m
p
lo
ye
d
c
o
d
e
s
m
ell
d
etec
tio
n tec
hn
iq
ue?
C
o
d
e
s
m
ell
d
etec
tio
n
tech
n
iq
u
es
wer
e
co
m
p
ar
ed
b
ased
o
n
th
e
ca
teg
o
r
y
o
f
th
e
tech
n
i
q
u
e,
ty
p
e
o
f
d
etec
ted
co
d
e
s
m
ells
,
s
u
p
p
o
r
ted
p
r
o
g
r
am
m
in
g
lan
g
u
a
g
es,
s
u
b
ject
s
y
s
tem
s
,
an
d
ev
alu
atio
n
cr
iter
ia
u
s
ed
t
o
ev
alu
ate
th
e
tec
h
n
iq
u
e
.
Ou
t
o
f
th
e
1
1
6
s
tu
d
ies
in
clu
d
ed
in
th
is
an
aly
s
is
,
o
n
ly
o
n
e
s
tu
d
y
u
s
ed
a
m
an
u
a
l
ap
p
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h
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er
e
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etec
tio
n
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d
o
n
e
b
ased
o
n
h
u
m
an
p
er
ce
p
tio
n
[
8
7
]
.
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h
e
m
a
n
u
al
d
etec
ti
o
n
p
r
o
ce
s
s
u
s
u
ally
tak
es a
lo
n
g
tim
e,
a
n
d
th
e
n
u
m
b
er
o
f
f
alse p
o
s
itiv
e
s
m
ells
ar
e
u
s
u
ally
h
ig
h
.
Fig
u
r
e
4
s
h
o
ws
th
e
p
er
ce
n
ta
g
e
o
f
s
tu
d
ies
in
clu
d
e
d
in
th
i
s
r
ev
iew
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ased
o
n
th
e
u
s
ed
d
etec
tio
n
tech
n
iq
u
e.
Fig
u
r
e
4
d
ep
icts
t
h
at
th
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p
r
ed
o
m
in
an
t
ap
p
r
o
ac
h
es
in
th
e
liter
atu
r
e
f
o
r
d
etec
ti
n
g
c
o
d
e
s
m
ells
ar
e
m
etr
ics
-
b
ased
.
I
n
c
o
n
tem
p
o
r
a
r
y
r
esear
ch
,
t
h
er
e
is
a
g
r
o
win
g
u
tili
za
tio
n
o
f
m
ac
h
i
n
e
lea
r
n
in
g
tech
n
iq
u
es
to
id
en
tify
co
d
e
s
m
ells
,
d
is
p
lacin
g
o
th
er
t
r
ad
itio
n
al
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etec
tio
n
m
eth
o
d
s
.
30%
50%
20%
Jo
u
r
n
a
ls
C
o
n
f
er
en
ce
p
r
o
ceed
in
g
Othe
r
(
w
o
r
k
s
h
o
p
s
,
s
y
m
p
o
s
iu
m
s
,
b
o
o
k
c
h
ap
t
er
s
)
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8
7
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8
A
s
ystema
tic
r
ev
ie
w
o
n
s
o
ftw
a
r
e
co
d
e
s
mells
(
Mo
h
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mme
d
Gh
a
z
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l
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3017
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u
r
e
4
.
T
h
e
p
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ce
n
tag
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f
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tu
d
ies b
ased
o
n
t
h
e
u
s
ed
d
etec
tio
n
tech
n
iq
u
e
R
Q4
:
Wha
t
p
r
o
g
r
a
m
m
ing
l
a
ng
ua
g
es
a
r
e
em
p
lo
ye
d
b
y
va
r
io
us
co
d
e
s
m
ell
d
etec
tio
n
techniq
ues
i
n
the
inclu
d
ed
s
tud
ies?
B
ased
o
n
th
e
an
al
y
s
is
o
f
1
1
6
s
tu
d
ies,
it
was
n
o
ted
th
at
J
av
a
is
th
e
m
o
s
t
u
s
ed
lan
g
u
ag
e
wh
er
e
it
is
u
s
ed
in
9
3
s
tu
d
ies
(
8
0
%
o
f
t
h
e
in
clu
d
e
d
s
tu
d
ies).
Fu
r
t
h
er
,
th
r
ee
o
f
th
e
r
ec
e
n
t
tech
n
i
q
u
es
u
s
ed
Py
th
o
n
[
9
1
]
,
[
1
1
9
]
,
an
d
[
1
4
3
]
.
MA
T
L
AB
is
o
n
ly
u
s
ed
in
o
n
e
s
tu
d
y
[
8
6
]
.
An
d
r
o
i
d
is
u
s
ed
in
th
e
p
r
im
ar
y
s
tu
d
ies
[
1
1
1
]
,
[
1
1
4
]
,
an
d
[
1
3
7
]
.
Fig
u
r
e
5
s
h
o
ws
th
e
p
r
o
g
r
am
m
in
g
lan
g
u
ag
e
s
u
s
ed
b
y
d
if
f
er
en
t
d
etec
tio
n
t
ec
h
n
iq
u
es
to
d
etec
t
co
d
e
s
m
ells
.
Fig
u
r
e
5
.
Pro
g
r
am
m
i
n
g
lan
g
u
a
g
es u
s
ed
b
y
s
tu
d
ies in
clu
d
ed
i
n
th
is
r
ev
iew
R
Q5
:
Wha
t su
b
ject
s
y
s
tem
s
w
ere
us
ed
to
va
lid
a
te
co
d
e
s
m
el
l d
etec
tio
n
techniq
ues
i
n the
i
nclud
ed
s
tud
ies?
Dif
f
er
en
t
s
u
b
ject
s
y
s
tem
s
we
r
e
u
s
ed
to
v
alid
ate
co
d
e
s
m
ell
d
etec
tio
n
tech
n
iq
u
es.
T
h
e
s
e
s
u
b
ject
s
y
s
tem
s
v
ar
y
in
th
ei
r
s
ize,
la
n
g
u
ag
e
,
an
d
th
e
im
p
lem
en
ted
co
d
e
s
m
ells
.
Ap
ac
h
e
Xer
ce
s
,
Gan
ttP
r
o
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an
d
Ar
g
o
UM
L
ar
e
f
r
e
q
u
en
tly
u
s
ed
as
s
u
b
ject
s
y
s
tem
s
in
em
p
ir
ical
s
tu
d
ies
o
n
co
d
e
s
m
ell
d
etec
tio
n
d
u
e
to
th
ei
r
r
ich
s
et
o
f
co
d
e
s
m
ells
an
d
ex
t
en
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iv
e
u
s
e
in
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o
f
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ee
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m
m
u
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.
Ap
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m
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W
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