

Romanian Reports in Physics















Topics covered by the journal

Theoretical and Mathematical Physics, General Physics, Nuclear Physics, Particle and Astroparticle Physics, Optics and Quantum Electronics, Plasma Physics, Condensed Matter,
Biophysics, Medical Physics, Earth and Environmental Physics, Physics Education







Volume 75, Number 1, 2023 




THEORETICAL, MATHEMATICAL, AND COMPUTATIONAL PHYSICS 






N doublepole solutions of the nonlinear
Schrödingertype equation with nonzero boundary conditions
GUOFEI ZHANG, JINGSONG HE, YI CHENG
Rom. Rep. Phys. 75, 101 (2023)
Abstract.
This paper is concerned with the inverse scattering transform (IST) for
the nonlinear derivative Schrödingertype equation, which is an extension of the nonlinear
Schrödinger (NLS) equation, under the nonzero boundary conditions (NZBCs) and
scattering coefficients with double zeros based on the RiemannHilbert (RH) problem.
On the direct scattering and the inverse scattering processes, we discuss some properties
of Jost solutions, asymptotic behaviors, analyticity, symmetries of the Jost solutions
and the corresponding spectral matrix, and then we give the matrix RH problem, and
the reconstruction formula of potential and trace formula, correspondingly. Based on
the above analysis, the explicit formula of N doublepole solutions can be obtained in
the case of reflectionless potential. Moreover, we discuss an example of the doublepole
soliton solution.





Exploring the propagations of the
mixed doubly nonlinear dispersive Burgers equation: resonant lump and kinky solitary
waves
MARWAN ALQURAN, MOHAMMED ALI, QUTAIBEH KATATBEH, H.M. JARADAT,
IMAD JARADAT, MOHAMMED ALDOLAT
Rom. Rep. Phys. 75, 102 (2023)
Abstract.
In this work, we obtain new resonant lump, kinky, and periodic solutions
to a combination of two Burgers' hierarchies. In particular, we study the mixed
doubly nonlinear dispersive Burgers equation. The suggested model includes different
types of moving unidirectional waves in the media of optical systems, nonlinear acoustics,
and fluids. The resonant solitary wavesolutions can be constructed by using linear
superposition principle and the Bell polynomials via the implementations of Hirota's
method and the ColeHopf transformation. Three effective schemes are used, namely,
the Kudryashovexpansion, updated rational sinecosine functions, and Hirota's bilinear
method to produce kinks, periodic, and lumps solitary wave solutions, respectively.
A graphical analysis scheme is conducted to show the physical structures of the obtained
solutions. Also, the impact of the model's coefficients is studied graphically as
well.





Darboux transformations for a generalization of
the nonlinear Schrödinger equation and its reductions
JING SHEN, XIANGUO GENG, BO XUE
Rom. Rep. Phys. 75, 103 (2023)
Abstract.
In this paper, we introduce a 2×2 matrix spectral problem with
two potentials to derive a generalization of the nonlinear Schrödinger system that can
be reduced to four important integrable equations: a generalization of the nonlinear
Schrödinger equation, a combined nonlinear Schrödinger and derivative nonlinear
Schrödinger equation, and a combined nonlinear Schrödinger and ChenLeeLiu equation,
a combined nonlinear Schrödinger and GerdjikovIvanov equation. With the help of a
gauge transformation between the corresponding Lax pairs, Darboux transformations
for the generalization of the nonlinear Schrödinger system and its reductions are constructed,
by which explicit solutions for the generalization of the nonlinear Schrödinger
system and its reduction can be engendered from their known solutions. As an application,
we obtain various explicit solutions of the four integrable equations, including
onesoliton, twosoliton, periodic solutions and others.





Dynamical behavior and soliton solutions of the Jumarie's
spacetime fractional modified BenjaminBonaMahony equation in plasma physics
A. S. RASHED, A. N. M. MOSTAFA, ABDULMAJID WAZWAZ, S. M. MABROUK
Rom. Rep. Phys. 75, 104 (2023)
Abstract.
The spacetime fractional modified BenjaminBonaMahony problem is reduced and analytically
solved using the fractional subequation approach. The RiemannLiouville derivative as modified by
Jumarie is examined. Graphical representations of periodic, kink, and multisoliton solutions are
shown as examples of the obtained solutions. Using this method, researchers may create new,
oneofakind solutions to a wide
variety of nonlinear fractional partial differential equations.





Convergence analysis of a numerical iterative scheme to
find multiple solutions of onedimensional steadystate reactive transport model
AZAM SADAT HASHEMI, MOHAMMAD HEYDARI, GHASEM BARID LOGHMANI,
ABDULMAJID WAZWAZ
Rom. Rep. Phys. 75, 105 (2023)
Abstract.
In the present study, a onedimensional steadystate nonlinear reactive
transport model with the MichaelisMenten term is considered, which encodes
some important processes of engineering. The governing nonlinear differential equation
admits multiple solutions depending on the embedding parameters in the model.
Determining suitable initial guesses, an iterative discrete scheme based upon a combination
of the quasilinearization method and finite difference method to approximate all
branches of the solution is proposed. Furthermore, the method convergence is investigated
in detail and some cases are considered to illustrate the method's accuracy.





Numerical algorithm for the coupled
system of nonlinear variableorder time fractional Schrödinger equations
M. A. ZAKY, A. S. HENDY, A. A. ALDRAIWEESH
Rom. Rep. Phys. 75, 106 (2023)
Abstract.
A numerical simulation technique for the coupled system of variableorder
time fractional nonlinear Schrödinger equations is developed in this paper using
the finite difference/spectral method. The finite difference method is adapted to discretize
the variableorder Caputo timefractional derivative, and the spectral technique
is used for spatial approximation. The significant advantage of the proposed algorithm
is that the iterative procedure is not used to implement the nonlinear term in the coupled
system. In addition, numerical experiments are performed in order to verify the
accuracy of the method.





Security analysis of a chaotic random number generator based on a
fractionalorder exponential jerk system
KAYA DEMIR
Rom. Rep. Phys. 75, 107 (2023)
Abstract.
In this study, the cryptanalysis of a chaotic random number generator
(RNG) based on a fractionalorder exponential jerk system (FOEJS) is discussed. In
order to explain the target RNG's security flaws, an attack RNG is used. It is shown
that using linear continuous feedback in a driveresponse arrangement, consistent synchronization
between the attack and target systems can be achieved if the RNG design
is known and a state variable of the fractionalorder chaotic system is observable for a
time interval. Once the target and attack RNGs have synced, the attack system generates
the same output bit stream as the target RNG. Numerical simulations confirm the
effectiveness of the attack approach. As an example demonstration, a RNG based on a
fractionalorder exponential jerk system is targeted in this article. Despite this specific
target, the cryptanalysis method described in this paper can be applied to any RNGs
based on fractionalorder or integerorder chaotic systems, also based on continuous time
or discretetime chaotic systems. As a result, this study highlights the security
flaws associated with RNGs based on fractionalorder chaotic systems, as well as the
error of treating deterministic fractionalorder chaos as a single entropy source for a
RNG.





Bright solitons in the spaceshifted PTsymmetric nonlocal
nonlinear Schrödinger equation
SHENGAN CHEN, DUMITRU MIHALACHE, KAI JIN, JUNYAN LI, JIGUANG RAO
Rom. Rep. Phys. 75, 108 (2023)
Abstract.
Under investigations in this paper are the bright solitons on the zero
and periodic wave background in the spaceshifted PTsymmetric nonlocal nonlinear
Schrödinger equation. These soliton solutions are constructed through the bilinear
KPhierarchy reduction method, and are given in terms of determinants. The collision
dynamics of bright twosoliton solutions on the zero background are studied based on
their asymptotic expressions. The bright foursoliton solutions can form bound state
twosoliton pairs. The bright twosoliton solutions on the periodic wave background
are also studied. Compared with the case of solitons on the zero background, the bright
twosoliton solutions on the periodic wave background have completely different dynamics,
even though the periodic waves vanish into the background.


ATOMIC, MOLECULAR, AND NUCLEAR PHYSICS 






Alpha decay and cluster radioactivity
of heavy superheavy nuclei
D.N. POENARU, H. STÖCKER, R.A. GHERGHESCU
Rom. Rep. Phys. 75, 201 (2023)
Abstract.
Superheavy nuclei of interest for the forthcoming synthesis of the
isotopes with Z = 119,120 are investigated. One of the very interesting experiment
was performed at the velocity filter SHIP (GSI Darmstadt) trying to produce ^{299}120
in a fusion reaction ^{258}Cm(^{54}Cr,3n)^{299}120. We report calculations
of α decay halflives
using four models: AKRA (Akrawy), ASAF (Analytical SuperAsymmetric Fission),
UNIV (Universal Formula), and semFIS (Semiempirical formula based on Fission
Theory). The released energy, Q, is calculated using the theoretical model of
atomic masses WS4, see Phys. Rev. C 84 (2011) 014333 and Phys. Lett. B 734 (2014)
215. For ^{92,94}Sr cluster radioactivity of ^{300,302}120 we predict a branching
ratio relative
to α decay of −0.10 and 0.49, respectively, which is expected to be measured in a
forthcoming experiment.





Angular distribution of prompt fission γrays
G. AHMADOV, D. BERIKOV, YU. KOPATCH
Rom. Rep. Phys. 75, 202 (2023)
Abstract.
The angular distributions of promptfission
γrays with respect to the
direction of fission fragments in the monochromatic “warm” neutron induced fission
of ^{235}U have been studied. The fragments were detected with lowpressure position
sensitive multiwire proportional counter and the gammarays with a plastic scintillators.
The timeofflight method is used to discriminate prompt neutrons and prompt
γrays of fission. From the measured angular distributions with respect to the direction
of the selected fragments, the value of the laboratory anisotropy has been found to be
15 % in comparison to the value obtained in the perpendicular direction. The measurements
indicate the existence of a significant anisotropy of emission of the
γrays in the
emittingfragment system, suggesting the presence of significant angular momenta of
the fragments correlated with the fission axis, which also lead to an enhanced emission
of the γrays. Moreover, the article includes a new technique for measuring and correcting
the obtained angular distribution, in the case of when plastic scintillators have
different threshold levels for detection of
γrays.


OPTICS AND PHOTONICS, PLASMAS, LASER AND BEAM PHYSICS 






Impure geometric progression of synthetic frequencies: A welldefined and
precisionoptimized multiinterferometric method for absolute distance measurement
P. C. LOGOFĂTU
Rom. Rep. Phys. 75, 401 (2023)
Abstract.
The method for the determination of the absolute distance from the
excess ratios of multiwavelength interferometry, invented by Benoît in 1898, was
confronted from its inception with the problem of ambiguity and the lack of an
analytical formula for calculations. I offer here a solution for the elimination of the
ambiguities at the ends of the period within assumed measurement errors, a true
analytical recurrent formula for the determination of the absolute distance, and other
improvements. My method is proven rigorously to be welldefined and optimized for
precision. It is shown here that my method is the boundary between ambiguity and
precision.





Measurement
of absorption in ultrapure crystalline quartz under conditions of influence of ambient
air absorption using timeresolved photothermal commonpath interferometry
KSENIA V. VLASOVA, ALEXANDRE I. MAKAROV, NIKOLAI F. ANDREEV
Rom. Rep. Phys. 75, 402 (2023)
Abstract.
Measurements of ultralow absorption ≈7 × 10^{−8} cm^{−1} in synthetic
crystalline quartz shielded by absorption in the ambient air are demonstrated using a
timeresolved photothermal commonpath interferometry scheme. A modified optical
part of the scheme that provides a Gaussianlike shape of laser beams in the volume of
measured samples is presented. The absorption coefficient is calculated by processing
the signal waveforms obtained in this optical scheme in different crystal volumes. A
theoretically determined thermooptical parameter is used for calculations. The
characteristic heat diffusion times in the ambient air and crystalline quartz are
measured.





Wavelength and threshold characteristics of an asymmetric double
quantum well laser under nonresonant intense laser
A.M. STATIE, D. BEJAN
Rom. Rep. Phys. 75, 403 (2023)
Abstract.
We theoretically investigated the interaction of an asymmetric
double quantum well with an intense nonresonant laser radiation and its effects on
energy spectrum, wavelength of the emitted radiation, threshold current density and
characteristic temperature if this structure becomes the active medium of a laser. The
results reveal an increase/decrease in the energy of the conduction/valence subbands
of the double well leading to an increase in the effective width of the bandgap with
the augment of the laser intensity. We found a larger variation of the emitted
wavelength, lower threshold currents and a higher characteristic temperature than
conventional quantum well lasers.


BIOPHYSICS AND MEDICAL PHYSICS 






Theoretical evaluation to assist targeted drug delivery with ultrasoundsupported
sonoporation for future laserdriven studies at ELINP
K. M. SPOHR, D. DORIA, D. B. D. DREGHICI, A. MAGUREANU, V. NASTASA, L. TUDOR,
C.J. YANG
Rom. Rep. Phys. 75, 601 (2023)
Abstract.
Inaugural studies of medicinesupporting research foreseen to be implemented
at the HighPower Laser Systems (HPLS) at ELINP will benefit substantially
from achieving a fast and localized delivery of radiological substances. Microbubbles
driven by an ultrasonic transducer have been used successfully as delivery agents
for pharmaceuticals for several decades. They can support future oncology programs
facilitating highdose rate therapies (e.g., flash therapy) at ELINP, since a very localized
and swift delivery of drugs and nanoparticles is achievable using the bubbles.
We herein depict a theoretical evaluation to control the critical microbubble explosion
that creates the highpressure gradients of need for invitro and invivo sonoporation of
drugs and nanoparticles based on the RayleighPlesset equation. Suitable bubble sizes
R_{0} and corresponding resonance frequencies f_{res} are derived for
which an ultrasonicdriven
explosion can be achieved assuming an externally applied pressure P_{∞}(t) of
sinusoidal nature. With R_{0} in the μm and f_{res} in the MHz regime,
the crucial explosion
times T_{expl} can be short (<2 μs) allowing the soughtafter fast delivery of the
pharmaceutical payload.





Holographic microscopy of cell
compartments to build realistic models for electric field simulations
A. M. PLEAVA, R. D. NEGOITA, M. A. ILISANU, M. MIHAILESCU, M. MOREGA,
V. L. CALIN, E. N. SCARLAT, I. A. PAUN
Rom. Rep. Phys. 75, 602 (2023)
Abstract.
The reconstructed phase images (PIs) from digital holographic
microscopy contain in each pixel values of the phase shift introduced by the sample in
optical path, which allow to segment cells in the most important compartments: nucleus
and cytoplasm. Based on PIs, we computed optical properties of cells from two
sublines with different malignancy levels and propose a threelayers numerical model
to analyze the response under the stress of a high frequency continuous wave electric
field. The induced transmembrane voltage is compared for different values of dielectric
properties assigned to the cell compartments. Considering the nucleus as a distinct
domain with specific electrical properties, brings the model closer to realistic cases;
the importance of its presence in simulation models was also investigated.


APPLIED AND INTERDISCIPLINARY PHYSICS 






Ebeam simulation
for cultural heritage cellulosic materials preservation at IRASM
O. CAPRARU, F. ALBOTA, M. VIRGOLICI, D. NEGUT, V. MOISE
Rom. Rep. Phys. 75, 801 (2023)
Abstract.
Two Monte Carlo simulations were used to determine the optimal
amount and shape of cultural heritage cellulosebased materials for decontamination with
an industrial ebeam accelerator of an inhouse design. The findings are encouraging
for the large volume treatment of historic book collections and archives at iradiation
facilities around the world.





Tracker analysis of a lowcost experiment on a sphere rolling along a cycloidal track
P. AGUILARMARÍN, G. ROJASALEGRÍA, C. MORGANCRUZ, M. CHAVEZBACILIO
Rom. Rep. Phys. 75, 802 (2023)
Abstract.
Spheres or cylinders rolling on horizontal surfaces or inclined planes
are relatively common in the physics education literature but rolling on concave tracks
are rarely reported. In this work we report the Tracker video analysis and modeling of
a small rubber sphere rolling along a cycloidal track. Ansatz type solutions to the
differential equation of motion were built based on the videodata graph shapes, a
procedure that can be applied to differential equations whose analytical solutions are
very hard to obtain or nonexistent. Very close agreement between experiment and
model was found. We have taken into account that the deformation of objects in
contact is inherent to rolling motion. The distinction between sliding friction and
rolling friction is discussed. Our main results are: i) the x(t) and y(t) coordinates
show
exponential decay in amplitude due to the combined action of velocitydependent
rolling friction and air damping forces, ii) the upward and downward rolling motions
are not symmetric, iii) at every quartercycle of oscillation the maxima in the kinetic
energy are shifted to the right and to the left from the equilibrium position. This lowcost
experiment provides a pedagogical demonstration of the asymmetry between the
upward and downward motion.


PHYSICS EDUCATION 






Escaping the
lab: increasing motivation in the physics classroom through educational escape rooms
E. MARTINEZ, J. ALVAREZ, V. CARBONELL, M. FLOREZ, E. MONTOYA
Rom. Rep. Phys. 75, 901 (2023)
Abstract.
This paper reports the effect of gamifying an Introductory Physics
Course at the Universidad Politécnica de Madrid on the motivation of students and
understanding of basic physics concepts in a playful way.
For that purpose, the Physics Course was designed to include some elements of
gamification as digital Escape Rooms using Genially, a webbased platform. To escape
from the laboratory, students must solve challenges to exit, and when they escape, in a
given time, they must answer some questions for feedback statistical analysis. From
the results of this study the gamified instruction increased the student's motivation as
well as a positive effect on their learning process. The authors also compared the
answers provided by students attending two different university degrees.





Teaching
geometrical optics by means of GeoGebra software
ANDA CIOBANU, CRISTINA MIRON, CĂTĂLIN BERLIC, VALENTIN BARNA
Rom. Rep. Phys. 75, 902 (2023)
Abstract.
The use of digital tools in physics education increases the students'
digital competencies, their motivation and highly contributes to develop cognitive
learning processes during their interaction with software simulations. In this paper, we
present how to employ GeoGebra software for teaching geometrical optics phenomena.
The proposed approach started with the study of spherical diopter, since optical systems,
such as mirrors and lenses, are set of surfaces that reflect or refract light rays and the
mathematical relations that describe these systems are obtained from the diopter
formulas. Another system that combines light reflection and refraction, for which we
created a dynamical model, is the optical prism. Dynamic simulations for these systems
offer the possibility to examine, by geometrical tools, the involved physics laws.
Moreover, one can identify various attributes or properties that are changing and their
effects, leading to processes of reflection and to knowledge construction. We also
explored the possibility to take the advantage of GeoGebra software in solving
problems, by creating an attractive environment that promotes better comprehension of
the concepts and of the involved optical phenomena. The use of images, instead of the
commonly employed symbolic representations, can greatly support students having a
lower capacity for abstraction and facilitates their understanding of physics problems.






This is an electronic version of Volume 75 Number 1 2023




