Ann.
Acad.
Rom.
Sci.
Ser.
Math.
Appl.
ISSN
2066-6594
Vol.
18,
No.
4/2026
ON
THE
FALL
SESSION
OF
THE
ROMANIAN
ITINERANT
SEMINAR
ON
MATHEMATICS
AND
ITS
APPLICATIONS
(RISMA),
10
September
2026,
Tˆ
argovi¸
ste,
Romania
Gheorghe
Moro¸
sanu,
founder
and
coordinator
of
RISMA
⇤
Dedicated
to
Professor
Constantin
Fetecau
on
his
80th
anniversary
DOI 10.56082/annalsarscimath.2026.4.411
1
Introduction
It
is
well
known
within
the
Romanian
mathematical
community
that
I
launched
in
2017
the
Romanian
Itinerant
Seminar
on
Mathematical
Analysis
and
Its
Applications:
www.cs.ubbcluj.ro/rismaa/.
Since
then,
six
success-
ful
annual
sessions
have
taken
place
in
various
cities:
Cluj-Napoca
(2018),
Constant
¸a
(2019),
Alba
Iulia
(2021),
Bra¸
sov
(2022),
Craiova
(2023),
and
Cluj-Napoca
again
in
2024.
In
2024,
I
proposed
renaming
the
seminar
as
Romanian
Itinerant
Semi-
nar
on
Mathematics
and
Its
Applications
(RISMA):
http://www.aosr.ro/en/
romanian-itinerant-seminar-on-mathematics-and-applications-sirma/,
expan
ding
its
scope
to
include
all
areas
of
mathematics
and
its
applications.
Un-
der
this
new
format,
the
seminar
sessions
are
held
twice
a
year,
as
parts
of
the
Spring
and
Fall
Scientific
Conferences
organized
by
the
Academy
of
Romanian
Scientists
(ARS),
and
hosted
in
the
same
cities
where
the
ARS
Spring
and
Fall
Conferences
of
all
ARS
sections
take
place.
More
precisely,
the
Spring
and
Fall
Conferences
of
the
ARS
Mathematics
Section
are
re-
placed
by
extensions
called
RISMA
Spring
and
Fall
Sessions
.
The
idea
is
to
⇤
gheorghe.morosanu@ubbcluj.ro
,
Babe¸
s-Bolyai
University,
Cluj-Napoca,
Romania
&
Academy
of
Romanian
Scientists,
Bucharest
411
RISMA
Fall
Session,
10
September
2026,
Tˆ
argovi¸
ste,
Romania
412
expand
the
ARS
mathematics
conferences
to
a
wider
audience.
The
papers
resulting
from
this
seminar
are
usually
published
in
our
journal,
Annals
of
the
Academy
of
Romanian
Scientists,
Series
on
Mathematics
and
Its
Appli-
cations
.
The
participants
to
this
RISMA
Fall
Session
who
presented
their
sci-
entific
results
on
this
occasion
are
glad
and
honored
to
dedicate
their
cor-
responding
abstracts
below
to
Professor
Emeritus
Constantin
Fetecau
who
turned
80
this
year.
September
10,
2026
Gheorghe
Moros
,
anu
2
Abstracts
of
the
Presentations
The
abstracts
of
the
presentations
are
attached
below,
listed
in
alphabetical
order
by
the
presenters’
names.
Full
papers
may
be
obtained
by
contacting
the
authors
directly
at
the
email
addresses
provided.
•
Luminit
,
a
BARBU
,
Ovidius
University
of
Constant
,
a,
Romania,
Asso-
ciate
Member
of
the
Academy
of
Romanian
Scientists;
email:
lbarbu@univ-
ovidius.ro,
and
Gheorghe
MOROS
¸ANU
,
Babe¸
s-Bolyai
University,
Cluj-
Napoca,
Romania,
Full
Member
of
the
Academy
of
Romanian
Scientists,
email:
gheorghe.morosanu@ubbcluj.ro
Title:
On
a
Delay
Second
Order
Integro-Di
↵
erential
Equation
in
a
General
Banach
Space
Abstract
:
Consider
in
a
real
Banach
space
X
the
following
second
order
integro-di
↵
erential
equation
u
00
(
t
)
=
Au
(
t
)
+
Z
0
r
g
(
s,
u
t
(
s
))
ds
+
f
(
t
)
,
t
2
[0
,
T
]
,
(
E
)
u
(0)
=
(0)
,
u
0
(0)
=
b,
u
0
=
,
(
IC
)
where
A
:
D
(
A
)
⇢
X
!
X
is
a
densely
defined,
closed
linear
operator
generating
a
strongly
continuous
cosine
family,
g
is
a
possibly
unbounded
G.
Moro¸
sanu
415
the
cracks,
the
interaction
is
weak
and
the
tips
of
the
longest
crack
start
to
propagate
first.
•
Vasile
DR
˘
AGAN
,
Simion
Stoilow
Institute
of
Mathematics,
Romania,
Full
Member
of
the
Academy
of
Romanian
Scientists;
email:
vasile.dragan@
imar.ro,
and
Samir
ABERKANE
,
Universite
de
Lorraine,
CRAN,
UMR
Vandoeuvre-les-Nancy
Cedex,
France,
and
CNRS,
CRAN,
UMR
7039,
France;
email:
samir.aberkane@univ-lorraine.fr
Title:
Coupled
Matrix
Riccati
Di
↵
erential
Equations
with
Appli-
cations
to
the
Solution
of
some
Control
Problems
for
Systems
Modelled
by
Mean-field
Stochastic
Linear
Di
↵
erential
Equations
Abstract
:
We
consider
a
class
of
coupled
matrix
Riccati
di
↵
erential
equa-
tions
involved
in
the
solution
of
some
linear
quadratic
optimal
control
prob-
lems
for
systems
described
by
McKean-Vlasov
linear
stochastic
di
↵
erential
equations
also
known
as
mean-field
stochastic
linear
di
↵
erential
equations.
For
this
kind
of
Riccati
di
↵
erential
equations
several
special
solutions
de-
fined
on
the
whole
real
axis
are
studied.
We
refer
to
maximal
and
bounded
solution
and
stabilizing
and
bounded
solution.
We
shall
provide
necessary
and
su
cient
conditions
which
guarantee
the
existence
of
that
solutions.
We
emphasize
the
role
of
these
solutions
in
the
proof
of
the
existence
of
an
op-
timal
control
for
an
optimal
control
problem
consisting
of
the
minimization
of
a
quadratic
functional
defined
on
the
set
of
the
trajectories
of
a
system
of
McKean-Vlasov
linear
stochastic
di
↵
erential
equations.
•
Teodor
HAV
ˆ
ARNEANU
,
Octav
Mayer
Institute
of
Mathematics,
Ro-
manian
Academy,
Ia¸
si,
Romania;
email:
havi@uaic.ro,
and
C˘
at˘
alin
POPA
,
Octav
Mayer
Institute
of
Mathematics,
Romanian
Academy,
Ia¸
si,
Romania
Title:
A
Splitting
Approximation
Scheme
for
the
Two-Dimensional
Magnetohydrodynamic
Equations
Abstract
:
We
consider
the
following
two-dimensional
magnetohydrody-
namic
equations:
@
y
@
t
y
+(
y
·
r
)
y
+
r
p
+
r
✓
1
2
B
2
◆
(
B
·
r
)
B
=
0
in
Q
=
⌦
⇥
(0
,
T
)
,
(1)
@
B
@
t
+
g
curl(curl
B
)
+
(
y
·
r
)
B
(
B
·
r
)
y
=
0
in
Q,
(2)
G.
Moro¸
sanu
417
We
then
obtain
the
first
term
of
the
asymptotic
expansion:
for
2
(0
,
1),
k
±
6
=
0,
R
>
0,
lim
t
!1
Z
|
⇠
|
R
t
↵
u
(
t,
t
⇠
)
U
(
⇠
)
d
⇠
=
0
,
(
↵
,
)
=
⇣
1+(
q
1)
⇤
,
1
1+(
q
1)
⇤
⌘
,
with
⇤
=
for
q
<
q
c
and
⇤
=
0
otherwise;
here
U
is
the
profile
of
the
unique
self-similar
solution
with
datum
k
sgn
x
|
x
|
of
the
heat
equation,
of
the
complete
equation
or
of
the
pure
conservation
law,
according
to
the
regime,
its
uniqueness
in
the
convective
range
being
the
delicate
point.
•
Aurelian
ISAR
,
Faculty
of
Physics,
University
of
Bucharest;
Horia
Hu-
lubei
National
Institute
of
Physics
and
Nuclear
Engineering,
M˘
agurele;
Full
Member
of
the
Academy
of
Romanian
Scientists;
email:
isar@theory.nipne.
ro,
and
Alina
STOICA
,
Faculty
of
Physics,
University
of
Bucharest;
Horia
Hulubei
National
Institute
of
Physics
and
Nuclear
Engineering,
M˘
agurele;
email:
dobre.alina@theory.nipne.ro
Title:
Generation
of
Quantum
Correlations
in
Gaussian
Quantum
Systems
Abstract
:
Hellinger
geometric
quantum
discord
and
interferometric
power
are
investigated
for
an
open
system
consisting
of
two
bosonic
modes
inter-
acting
with
four
di
↵
erent
environments:
vacuum,
squeezed
vacuum,
thermal
and
squeezed
thermal,
taking
the
initial
state
of
the
system
either
a
single-
mode
squeezed
state,
which
presents
no
correlations,
or
a
squeezed
vacuum
state.
The
time
evolution
of
the
correlations
is
investigated
in
the
frame-
work
of
the
theory
of
open
systems,
based
on
completely
positive
quantum
dynamical
semigroups,
using
the
Gorini-Kossakowski-Lindblad-Sudarshan
master
equation.
We
show
that
both
quantum
correlations
can
be
gener-
ated
from
an
initial
factorized
state
and
even
amplified.
For
the
squeezed
vacuum
environment,
the
competition
between
the
influences
exerted
by
the
squeezing
of
the
initial
state
and
the
squeezing
of
the
environment
leads
to
the
decreasing,
and
even
destruction
of
the
correlations,
or
to
their
enhance-
ment.
In
the
case
of
an
initial
squeezed
vacuum
state
in
interaction
with
the
squeezed
vacuum
environment,
for
specific
conditions
one
can
achieve
decoherence-free
states.
•
Liviu
IXARU
,
Horia
Hulubei
National
Institute
of
Physics
and
Nuclear
Engineering,
Department
of
Theoretical
Physics,
Bucharest,
Romania,
Full
RISMA
Fall
Session,
10
September
2026,
Tˆ
argovi¸
ste,
Romania
418
Member
of
the
Academy
of
Romanian
Scientists;
email:
ixaru@theory.nipne.
ro
Title:
On
the
Visualization
of
an
Atomic
Nucleus
Abstract
:
The
image
of
an
atom,
based
on
the
well-known
planetary
model
of
Bohr,
is
so
familiar
to
the
general
public
that
we
find
it
even
just
on
the
logo
of
various
institutions
in
the
country
or
abroad.
The
situation
is
di
↵
erent
for
the
atomic
nucleus
since
this
is
typically
based
on
a
simple
but
naive
model
such
that
a
modification
is
needed
for
a
more
realistic
base.
We
opt
for
the
nuclear
shell
model,
a
standard
tool
in
the
current
nuclear
physics.
We
examine
this
approach
to
present
its
results
by
a
series
of
graphs
and
animations.
A
series
of
novelties
and
surprises
will
arise.
Our
presentation
is
intended
to
be
of
use
for
both
specialists
and
nonspecialists.
•
Mircea
LUPU
,
Transilvania
University
of
Bra¸
sov,
Romania,
Corre-
sponding
Member
of
the
Academy
of
Romanian
Scientists;
email:
emlupu
2006@yahoo.com
Title:
New
Methods
of
Optimization
Airfoils,
Aerodynamics
Abstract
:
The
paper
addresses
direct
and
inverse
boundary
value
problems,
e
↵
ectively
deriving
solutions
for
nonlinear
functionals
or
integral
equations.
It
examines
the
dynamics
of
symmetric
aerodynamic
profiles
within
an
ideal
fluid,
subjected
to
the
action
of
either
an
unbounded
or
a
physically
bounded
jet.
Constitutive
equations
are
formulated
in
an
auxiliary
plane,
and
pro-
file
designs
are
determined
based
on
criteria
for
resistance
or
extreme
lift.
Solutions
are
obtained
using
analytical
methods,
inequalities,
or
extremal
analysis.
•
Constantin
P.
NICULESCU
,
Department
of
Mathematics,
University
of
Craiova,
Romania,
Full
Member
of
the
Academy
of
Romanian
Scientists;
email:
constantin.p.niculescu@gmail.com
Title:
In
Memoriam,
Sorin
G.
Gal
Abstract
:
This
talk
was
dedicated
to
the
memory
of
my
dear
friend
and
collaborator
Sorin
G.
Gal
(August
23,
1953
-
October
18,
2024).
This
sum-
marizes
the
dramatic
story
behind
our
latest
publication—the
book
on
the
Choquet
integral—which
he
initiated
as
a
project
in
2023.
G.
Moro¸
sanu
419
•
Adrian
PETRUS
¸EL
,
Babe¸
s-Bolyai
University,
Cluj-Napoca,
Romania,
Full
Member
of
the
Academy
of
Romanian
Scientists;
email:
adrian.petrusel
@ubbcluj.ro,
and
Gabriela
PETRUS
¸EL
,
Babe¸
s-Bolyai
University,
Cluj-
Napoca,
Romania;
email:
gabriela.petrusel@ubbcluj.ro
Title:
Some
Fixed
Point
Theorems
for
Nonself
Operators
in
Metric
and
b
-Metric
Spaces
Abstract
:
In
this
paper,
we
will
present
a
synthesis
on
some
fixed
point
results
for
nonself
operators.
The
outline
of
the
paper
is
the
following
one:
-
Local
fixed
point
theorems;
-
Graph
contractions;
-
Contractions
outside
a
bounded
set;
-
Fixed
point
results
in
b-metric
spaces
Applications.
•
Savin
TREANT
¸
˘
A
,
National
University
of
Science
and
Technology
Po-
litehnica
Bucharest,
Romania,
Corresponding
Member
of
the
Academy
of
Romanian
Scientists;
email:
savin.treanta@upb.ro
Title:
On
Some
Constrained
Optimization
Problems
via
Gradient
Type
Variations
Abstract
:
The
aim
of
this
presentation
is
the
optimization
of
constrained
integral-type
functionals
by
considering
gradient-type
variation
functions.
Concretely,
the
associated
necessary
conditions
of
optimality
are
stated
by
applying
appropriate
mathematical
pipelines.
The
main
results
highlight
the
nonhomogeneous
Euler-Lagrange-type
partial
di
↵
erential
equations.
Com-
pared
to
classical
variations,
in
this
context
we
are
led
to
controlled
right-
hand
member
equations,
creating
a
novel
perspective
in
the
field
of
varia-
tional
calculus.
More
precisely,
we
want
to
determine
the
pair
(
'
⇤
,
u
⇤
)
that
extremizes
the
following
functional
given
by
a
simple
integral
M
(
'
(
·
)
,
u
(
·
))
=
Z
!
1
!
0
G
(
'
(
!
)
,
˙
'
(
!
)
,
¨
'
(
!
)
,
u
(
!
)
,
!
)
d
!
between
all
functions
'
of
C
3
-class
that
meet
the
conditions
'
(
!
0
)
=
'
0
,
'
(
!
1
)
=
'
1
,
˙
'
(
!
0
)
=
˜
'
0
,
˙
'
(
!
1
)
=
˜
'
1
,
subject
to
the
following
ordinary
di
↵
erential
inequalities
(ODIs)
and
ordi-
nary
di
↵
erential
equations
(ODEs)
g
↵
(
'
(
!
)
,
˙
'
(
!
)
,
¨
'
(
!
)
,
u
(
!
)
,
!
)
0
,
↵
=
1
,
o,
o
n,