Volume 73, Number 1, 2021
 
THEORETICAL, MATHEMATICAL, AND COMPUTATIONAL PHYSICS
 
Geometric discord for a driven two-qubit system
T. MIHAESCU, E. CECOI, M.A. MACOVEI, A. ISAR
Rom. Rep. Phys. 73, 101 (2021)
Abstract. We employ a rescaled version of the geometric measure of quantum discord, based on the Hilbert-Schmidt norm, to calculate it in the steady-state for a concrete system formed of a closely packed and laser-pumped pair of identical two-level qubits being initially uncorrelated and located in their ground states, respectively. Furthermore, the qubits are longitudinally coupled with a single-mode boson field, while both subsystems are damped via their corresponding environmental reservoirs. Although the employed metric is still noncontractive under quantum operations, it was shown previously in a series of physical examples that this measure of quantum correlations is in agreement with other discord measures.
Article no. 101: PDF 
Properties of the quantum state arising after the L-photon state has passed trough a linear quantum amplifier
VLADIMIR A. ANDREEV, MILENA D. DAVIDOVIC, LJUBICA D. DAVIDOVIC, MILOS D. DAVIDOVIC, DRAGOMIR M. DAVIDOVIC
Rom. Rep. Phys. 73, 102 (2021)
Abstract. We consider the system of N two-level atoms, of which N0 atoms are unexcited and N1 are excited. This system of N two-level atoms, which forms a linear quantum amplifier, interacts with a single-mode electromagnetic field. The problem of amplification of the L-photon states using such an amplifier is studied. The evolution of the electromagnetic field density matrix is described by the master equation for the field under amplification. The dynamics of this process is such that it can be described as the transformation of the scale of the phase space. The exact solution of the master equation is expressed using the transformed Husimi function of the L-quantum state of the harmonic oscillator. The properties of this function are studied and using it the average photon number and its fluctuations in the amplified state are found.
Article no. 102: PDF 
Spectrum analysis and its applications for weighted iterated pentagon networks
BO WU, YUN CHEN
Rom. Rep. Phys. 73, 103 (2021)
Abstract. More and more attention has been paid to complex networks because of their wide application in many areas. In the research of complex networks, an important problem is to analyze the influence of network structure on network function and dynamic property, in which the network characteristic spectrum can well describe the structure and function of network. In this paper, a weighted iterated pentagon network is constructed and all the spectra of the Laplacian matrix of the network are found through the self-similar structure of the network. At the same time, as the application of the spectrum, the indexes such as the Kemeny constant and the multiplicative degree-Kirchhoff index are calculated and their analytical expressions are obtained.
Article no. 103: PDF 
Scattering from hierarchical multi-phase fractals: analysis of the crossover between fractal regimes
E.M. ANITAS
Rom. Rep. Phys. 73, 104 (2021)
Abstract. An important class of small-angle scattering (SAS; X-rays or neutrons) experimental data shows a succession of fractal regions with various scattering exponents. While for two-phase systems, this may indicate the presence of fractals with positive Lebesgue measure (fat fractals), for multi-phase systems, this generally shows the presence of fractals at different levels, i.e. fractals in which the composing units are themselves fractals. In the later case, the transition points (crossovers) between such regions as well as the contributions of the different structural levels to the total scattering intensity is not completely understood, and this may limit or hinder the analysis and interpretation of the scattering data. To address such issues, here is suggested a general approach, consisting from two main steps. First, a multi-phase "fractal inside fractal" model based on deterministic fractals with controllable structural parameters is introduced, and second, the corresponding scattering curves are calculated analytically. It is shown that the crossover positions and the contributions of the different structural levels to the total scattering intensity depend on the relative values of the scattering length density (SLD) of each phase, their volumes, and concentrations. This dependence allows one to use the developed approach to model experimental SAS data from multi-phase systems, which show a variation of the crossover position with SLD of any of the containing phase. In order to illustrate the above results, a mass-to-mass fractal transition is analyzed in detail.
Article no. 104: PDF 
The fractional dynamics of a linear triatomic molecule
D. BALEANU, S. SADAT SAJJADI, A. JAJARMI, O. DEFTERLI, J.H. ASAD
Rom. Rep. Phys. 73, 105 (2021)
Abstract. In this research, we study the dynamical behaviors of a linear triatomic molecule. First, a classical Lagrangian approach is followed which produces the classical equations of motion. Next, the generalized form of the fractional Hamilton equations (FHEs) is formulated in the Caputo sense. A numerical scheme is introduced based on the Euler convolution quadrature rule in order to solve the derived FHEs accurately. For different fractional orders, the numerical simulations are analyzed and investigated. Simulation results indicate that the new aspects of real-world phenomena are better demonstrated by considering flexible models provided within the use of fractional calculus approaches.
Article no. 105: PDF 
Mesoscopic study of mixed convection and heat transfer due to crescent shape hot ‎source under magnetic field and Joule effect
RIDHA DJEBALI
Rom. Rep. Phys. 73, 106 (2021)
Abstract. The present study deals with a mesoscopic numerical analysis of mixed convection and nanofluid cooling efficiency for a heat exchanger. The latter is formed by a square section duct driven at the ceiling and crossed by crescent shape cylinder designing a solar concentrator. The duct is filled with Al2O3/water nanofluid. The motion and the heat transfer are subjected to the effect of the buoyancy, external magnetic field and Joule and Hall effects. A second law analysis is conducted under variation of the various problem parameters. Efficient cooling configuration was determined using response surfaces of the Nusselt number. The conducted optimization for the account of stabilizing/destabilizing factors yields to the determination of optimal outputs. Correlations are given for broad ranges of problem factors.
Article no. 106: PDF 
 
ATOMIC, MOLECULAR, AND NUCLEAR PHYSICS
 
Non-destructive characterization of industrial depleted uranium shielding materials for nuclear forensics purposes
A. SERBAN, A. I. APOSTOL, L. GANEA, A. PANTELICA, D. MIREA, O. SIMA
Rom. Rep. Phys. 73, 201 (2021)
Abstract. The present study focuses on the non-destructive methods for the characterization of depleted uranium (DU) based gamma defectoscopes (shielding component) for nuclear forensics purposes. High Resolution Gamma Spectrometry (HRGS) was used to determine the isotopic composition of the DU materials of interest by employing PC/FRAM v5.1 software, while X-Ray Fluorescence (XRF) was suitable to determine the type of alloy used in the fabrication of the defectoscopes' casing materials. Moreover, it is outlined the role of the National Nuclear Forensics Library (NNFL-RO), as a scientific tool in aiding data interpretation and furthering nuclear security investigations.
Article no. 201: PDF 
 
PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
 
A possible experimental manifestation of ultra-high energy cosmic metaneutrinos
I.I. GERU
Rom. Rep. Phys. 73, 301 (2021)
Abstract. The restoration of the time-reversal symmetry in a system of ultra-high energy cosmic neutrinos involving metaneutrinos is discussed. Cosmic neutrinos reaching the Earth's surface correspond to cosmic metaneutrinos moving in the opposite direction. This can create the illusion of some radiation directed upward from the surface of the Earth. An alternative interpretation of the unusual upward-pointed cosmic-ray-like impulsive radio event recorded during Antarctic Impulsive Transient Antenna (ANITA) flights is proposed. Our approach take into account the interaction of ultra-high energy cosmic metaneutrinos with the Antarctic polar ice, which was detected in ANITA experiments by means of the Ackaryan emission.
Article no. 301: PDF 
 
OPTICS AND PHOTONICS, PLASMAS, LASER AND BEAM PHYSICS
 
Commissioning experiment on laser-plasma electron acceleration in supersonic gas jet at CETAL-PW laser facility
C. DIPLASU, G. GIUBEGA, R. UNGUREANU, G. COJOCARU, M. SERBANESCU, A. MARCU, E. STANCU, A. ACHIM, M. ZAMFIRESCU
Rom. Rep. Phys. 73, 401 (2021)
Abstract. CETAL-PW high power laser facility reports first accelerated electron beams with maximum energies up to ∽ 500 MeV obtained in Romania, by focusing ultra-short laser pulses of 35 fs with energies up to 5 J before compression on supersonic gas jets of low-density He 99% ― N 21% mixture. The conditions for generation of stable electron beams (root mean square (rms) pointing stability of about 5 mrad), with different types of spectral characteristics and average maximum electron energies between 180 MeV and 380 MeV are presented. Maximum energies for all accelerated electron spectra are well described by theoretical estimations.
Article no. 401: PDF 
Image resampling by interpolation guided by sensor geometry
P.C. LOGOFATU, N.T. VASILE
Rom. Rep. Phys. 73, 402 (2021)
Abstract. The image acquired by an imager is determined by the characteristics of the imaging sensor geometry such as the shape and area of the collecting surface of the photosite and of the microlens array element. In this article we propose to improve the acquired image using knowledge about the sensor geometry and vice versa, to determine the sensor geometry using knowledge about the original image. This is accomplished by means of resampling the image by interpolation guided by sensor geometry. Two cases were investigated theoretically and experimentally. In both cases the simulations confirmed the theory and predicted significant improvement. However, the experimental results did not show significant improvement of the image, or provided reliable information about the sensor geometry. This was attributed to the fact that the perturbations of the image due to geometric aberrations and the diffraction of the optic system, as well as the imperfections of the image itself, were greater than those due to the sensor geometry and to the ambiguity of the merit function used in the fit that seems to favor the sharpness of the image as much as the fidelity to the original.
Article no. 402: PDF 
 
BIOPHYSICS AND MEDICAL PHYSICS
 
Biophysical aspects of bio-nanosilver generated from Urtica Dioica Leaves and vitis vinifera fruits' extracts
M.E. BARBINTA-PATRASCU, C. NICHITA, N. BADEA, C. UNGUREANU, M. BACALUM, I. ZGURA, L. IOSIF, S. ANTOHE
Rom. Rep. Phys. 73, 601 (2021)
Abstract. Green chemistry principles were used to phytosynthesis of three types of silver nanoparticles (AgNPs) from aqueous extracts of: nettle (Urtica dioica) leaves, black grapes (Vitis vinifera fruits), and their mixture. The combination of these extracts proved to be the most potent bioreductant for Ag+, as compared to each extract alone. UV-Vis absorption and FT-IR spectroscopy proved the formation of silver nanoparticles. Total polyphenols' quantification of vegetal extracts and "green" AgNPs was carried out by Folin–Ciocalteu analysis. Structural (XRD) analysis revealed crystalline nature of bio-developed AgNPs. Morphological studies (AFM) showed spherical shape and the nano-scale dimensions of the obtained metallic nanoparticles. Physical stability of “green” developed nanoparticles was estimated by zeta potential measurements, and their biological activity was checked by evaluating the antimicrobial and the antioxidant potency. AgNPs phyto-generated from a combination of two extracts (nettle and grapes) proved to be the most bio-active, combining in a synergistic manner, the properties of nettle and grapes. These nanoparticles exhibited high antioxidant activity (AA = 89.4%) evaluated through chemiluminescence method, and strong antibacterial effect (showing an inhibition zone diameter of 20 mm) against Escherichia coli.
Article no. 601: PDF 
Effect of atmospheric non-thermal plasma treatment by DCSBD apparatus on sugar beet seeds
B. SERA, K. KRAUS, F. HNILICKA, V. MEDVECKA, A. ZAHORANOVA, M. SERY
Rom. Rep. Phys. 73, 602 (2021)
Abstract. Sugar beet seeds (cultivars of Jagger and Neruda) were treated by atmospheric non-thermal ambient air plasma generated using Diffuse Coplanar Surface Barrier Discharge device. The exposure plasma treatment times were: 0 s, 1 s, 3 s, 5 s, 10 s, 30 s, and 60 s. The aim of this work was to verify the effect of plasma treatment on germination and early growth parameters of the sugar beet seeds and to find optimal parameters of plasma treatment. Test of seed germination and early growth test were conducted in laboratory condition; eighteen characteristics of germinated seed and growing seedling were observed. Shorter treatment times (1 s and 3 s) were better suited for improving germination and initial growth parameters The difference in plasma responses was noted between the two cultivars used, the Jagger cultivar was judged as more suitable for this type of treatment.
Article no. 602: PDF 
 
ENVIRONMENTAL AND EARTH PHYSICS
 
Characterization of speleothems from Floriilor Cave, Romania
G. PEHOIU, C. RADULESCU, O. MURARESCU, S.G. STANESCU, I.D. DULAMA, I.A. BUCURICA, R.M. STIRBESCU, S. TEODORESCU, A.I. GHEBOIANU
Rom. Rep. Phys. 73, 701 (2021)
Abstract. This study aims to investigate a small wild cave, called Floriilor Cave, from the morphological structure and mineral composition point of view. This cave was accidentally discovered in 1991 and is currently closed to tourists; access is achieved only by the speleologists. The samples, including stalactites and stalagmites, rocks, and sediments, were collected in the autumn of the year 2018 by non-destructive methods. These analyses were performed by non-invasive techniques such as Optical Microscopy (OM), Field Emission - Scanning Electron Microscopy - Energy Dispersive X-Ray Spectroscopy (FE-SEM-EDS), and Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR). The SEM-EDS data highlighted a high amount of C, O and Ca, and low quantities of Mg, Al, Si, K, Fe, F, Na, P, and Cl. FTIR data for the samples revealed the occurrence of multiple functional groups in them. Identification of solid phase using the middle-IR region was based on the correlation between the peak pattern of the analyzed sample and the peak pattern of a standard material of known chemical composition (i.e., NIST SRM 2710a: Montana Soil). Raman data highlighted, for all samples, the C-O symmetric stretching band of the CO 32–ion. For oxides composition of the speleothem samples, the Wavelength Dispersive X-Ray Fluorescence (WDXRF) technique was applied. The X-Ray Diffraction (XRD) results show that calcite (92.11-98.21%) is the main mineral component identified for stalactite and stalagmite samples, along with a small amount of quartz (2.23-4.81%), gypsum (1.81-2.95%) or illite (1.02-1.85%) in host rock and sediment samples. As a preliminary study, this research is a good base for future investigations into the origin and genesis of the Floriilor Cave (Romania).
Article no. 701: PDF 
Anomalous spatial variation of radon in two dry carbon dioxide spas of Covasna, Romania
E. SOKI, S. GYILA, I. CSIGE
Rom. Rep. Phys. 73, 702 (2021)
Abstract. Anomalous spatial variation, featuring increasing airborne 222Rn activity concentration from the bottom of the pools towards their openings was found in two dry carbon dioxide spas (Bardocz- and Bene Mofette) of Covasna, Romania, using etched track type radon detector measurements. The anomalous behaviour could be reproduced by carrier gas flow and radon gas tracer transport calculations in the pools and in the soil around them. We concluded that the majority of these gases enter the pools through the sidewalls not the bottom of the pools in these dry mofettes.
Article no. 702: PDF 
Statistical approach of the behavior of Hamcearca River (Romania)
A. BARBULESCU, C. MAFTEI
Rom. Rep. Phys. 73, 703 (2021)
Abstract. In this article, we provide a statistical comparison of the flow series measured at two different hydrological stations on Taita River, which is one of the most important rivers from Dobrogea (Romania). This study has a practical purpose since Taita is among the few rivers from Dobrogea that don't suffer from dying, so its water can be used for irrigation. This study emphasizes the concordance between the results of the statistical tests and the field data concerning extreme events. Long-range dependence of the events is also noticed.
Article no. 703: PDF 
A model for convective updraft velocity in the atmospheric boundary layer based on analytical results and sailplane flights data
C.V. VRACIU
Rom. Rep. Phys. 73, 704 (2021)
Abstract. A model for thermal updraft velocity based on current analytical results and data collected from flights records at gliding competitions is presented. The model is based on the hypothesis that there is a linear relationship between the excess temperature of the thermal plume at ground level and the surface heat flux. The proportionality factor of this relationship was determined experimentally using observations recorded during gliding flights. The results show the relation between the development of the convective updrafts and the surface heat flux, and show how using the presented results, dry and moist convection can be predicted using the current analytical results.
Article no. 704: PDF 
 
APPLIED AND INTERDISCIPLINARY PHYSICS
 
Natural therapeutic factors assessment for the use in speleotherapeutic purposes of the Cacica Saline Mine, Romania
M.R. CALIN, I.G. SIMIONCA, I. RADULESCU
Rom. Rep. Phys. 73, 801 (2021)
Abstract. Salt mine galleries possess different therapeutic factors that can be used in the treatment of patients with multiple disorders and balneo-climatic underground tourism purposes. The paper presents the characterization from the point of view of radioactivity, the atmospheric radon and gamma radiations dose, and the results of microclimatic investigations the salt mine aerosols, microorganisms and gases concentrations - speleo-therapeutic factors, usable for medical and balneo-climatic tourism purposes in the galleries of Cacica salt mine, Suceava County, Romania. The mean radon concentration at six different locations within the salt mine varied between 20.5 and 96.5 Bq/m3. A seasonal variation was observed, with higher radon levels during summer and lower values during the winter season. The concentration of the aero-ions, the aerosol dispersion, the concentration of microorganisms, concentration of different gases in the underground, in galleries from Cacica salt mine are also presented.
Article no. 801: PDF 
 
PHYSICS EDUCATION
 
Modelling of a vertical wind turbine in the virtual lab
B. CHIRIACESCU, F.S. CHIRIACESCU, S. VOINEA
Rom. Rep. Phys. 73, 901 (2021)
Abstract. Renewable energies are easier to understand for students through experimental and virtual laboratories. Aerodynamical features of virtual wind turbines built in FreeCAD software are studied in a wind-tunnel by means of Comsol Multiphysics 5.0 software. Three types of vertical wind turbines having straight, inclined and curved wings were studied. The qualitative and quantitative results determined that the most efficient turbine was the curved - wings one.
Article no. 901: PDF 
A pico-satellite embedded in a soda can as an educational tool for atmospheric monitoring and telemetry data transmission through RF communication
S.I. TANASE, E.M. BUGA, L. POIENARIU, D. TANASE
Rom. Rep. Phys. 73, 902 (2021)
Abstract. Learning activities in which every student engages with hands-on experiences are considered as a promising classroom activity to motivate youth in science, technology, engineering and mathematics (STEM) education. One such learning activities in classrooms which combine physics, engineering, and programming is CanSat. In this paper we present several results concerning the design and production of a pico-satellite embedded in the volume and shape of a standard soda can which is capable to perform some of the tasks that artificial satellites carry out after being launched from a plane. The pico-satellite consists of an Arduino Pro-Micro MCU which uses an ATmega32u4 MCU, a 9 DOF (degrees of freedom) sensor containing a 3-axis accelerometer, 3-axis gyroscope and a 3-axis magnetometer, pressure and temperature sensors, camera and transceiver module in order to communicate with the ground station. Details about it, mechanical and electronic subsystems are presented along with the experimental results. The correlation between our CanSat design and the properties this device can measure could be valuable in the field of STEM education.
Article no. 902: PDF 

This is an electronic version of Volume 73 Number 1 2021
 
   
 
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