Volume 65, Number 56, 2020
Theoretical, Mathematical, and Computational Physics
Rational and SemiRational Solutions to the Nonlocal Mel’nikov Equation via Determinants Yunkai Liu, Biao Li, AbdulMajid Wazwaz Romanian Journal of Physics 65,
109 (2020)
Based on a combination of the bilinear method and the KP hierarchy reduction method, explicit rational and semirational solutions, given in terms of determinants, to the nonlocal Mel'nikov equation are investigated. We first start from the tau functions of the single component KP hierarchy, and construct general periodic solutions to the nonlocal Mel'nikov equation. By taking a longwave limit of the periodic solutions, general rational and semirational solutions to the nonlocal Mel'nikov equation are constructed. The obtained rational solutions describe lumps on a constant background. The semirational solutions have three different dynamical behaviours: lumps of any order on a periodic line waves background, the mixture of lumps of any order and breathers of any order on a constant background, and the mixture of lumps of any order and breathers of any order on a periodic line waves background.
Note on the Solving the Laplace Tidal Equation with Linear Dissipation Sergey V. Ershkov, Dmytro Leshchenko, Ayrat R. Giniyatullin Romanian Journal of Physics 65,
110 (2020)
In this paper, we present a new solving procedure for Laplace tidal equations (LTEs) with linear dissipation: the analytic algorithm is implemented here for solving momentum equation of LTEs, where the dissipation term with linear dependence on velocity field of fluid flow has been additionally taken into consideration (which is supposed to approximate the decreasing of momentum for the Ocean’s flows due to the viscous friction between Ocean’s layers if we consider heat fluxes during the lost of energy inside the Ocean). As a main result of this work, a new ansatz is suggested here for solving LTEs with linear dissipation: solving momentum equation is reduced to solving a system of three linear ordinary differential equations of first order with regard to three components of the flow velocity (depending on time t), along with mandatory using the continuity equation that determines the spatial part of solution. In our derivation, the main motivation is the proper transformation of the previously presented system of equations to a convenient form, in which the minimum of numerical calculations are required to obtain the final solutions. Preferably, it should be the analytical solutions; we have presented the solution as a linear combination of linearly independent fundamental solutions (of real and complex values). We pointed out also the elegant case of partial solution for velocity field of real value. Nevertheless, we should use the continuity equation for identifying the spatial components of velocity field in the case of nonzero fluid pressure in the Ocean, along with nonzero total gravitational potential and the centrifugal potential (due to planetary rotation). It means that the system of Laplace tidal equations with additional linear dissipation term (in momentum equation) could not be solved analytically.
Numerical Investigations on the Physical Dynamics of the Coupled Fractional BoussinesqBurgers System I. Abu Irwaq, M. Alquran, I. Jaradat, M.S.M. Noorani, S. Momani, D. Baleanu Romanian Journal of Physics 65,
111 (2020)
The coupled BoussinesqBurgers system is a physical model of fluid flows in a dynamical system that describes the propagation of shallow water waves. In this work, we upgrade this model to include timefractional derivatives. The effect of the fractional order in the propagation of the obtained solutions is discussed by using an adaptation of both the timespectrum function method and the homotopy perturbation method. One of the main findings worth to be mentioned, is that the field functions involved in the coupled fractional BoussinesqBurgers system have different stability behaviors. Tables and 3D plots regarding the accuracy of the proposed numerical methods are presented and comparison is made to show the preference of either method.
Average Trapping Time on the Level3 Sierpinski Gasket Bo Wu, Zhizhuo Zhang, Weiyi Su Romanian Journal of Physics 65,
112 (2020)
In this paper, we consider the unbiased random walk on the level3 Sierpinski gasket ($SG_3$). Due to the selfsimilar structure and iterative mechanism of the network, we obtain the exact analytic expression of the average trapping time (ATT) on $SG_3$. By comparing with the numerical result, we find that the analytical expression is very consistent with the corresponding numerical solution. Further, the obtained results indicate that ATT scales superlinearly with network size.
Condensed and Soft Matter Physics
Magnetic Control of Light Transmission and of Electrical Conductivity in (Hybrid) Magnetorheological Suspensions Based on Bioactive Components I. Bica, E. M. Anitas, L. M. E. Averis Romanian Journal of Physics 65,
605 (2020)
Biomagnetic active suspensions and tissues are manufactured from honey, cotton fibers and various concentrations of carbonyl iron ($\Phi _{\mathrm {CI}}$) microparticles. The obtained (h)MRSs composites are examined as magnetoactive materials for industrial and therapeutic applications. We propose a new experimental design, and show that the light transmission through (h)MRSs and the electrical conductivity are sensibly influenced by the intensity $H$ and gradient $\delta $ of an external magnetic field, as well as by $\Phi _{\mathrm {CI}}$. These effects make (h)MRSs versatile candidates in fabrication of technical and medical devices and equipment which require a magnetic control of the light transmission and of the thermal transport of bioactive components. They can be used for various applications such as scaffolding biomaterials for tissue repair and regeneration or in the quality control of honey crystallization and of its derivative products in industrial processes.
PlasmonLongitudinal Optical Phonon Interaction Based Modulational Amplification in Weakly Polar Magnetoactive NType Doped IIIV Semiconductors Anita Sangwan, Navneet Singh Romanian Journal of Physics 65,
606 (2020)
Using the hydrodynamical model of semiconductor plasmas and considering the origin of plasmonlongitudinal optical phonon interaction in effective thirdorder optical susceptibility, an analytical investigation of modulational amplification is performed in magnetoactive ntype doped III–V semiconductors. Expressions for necessary threshold pump amplitude for the onset of modulational amplification and growth rate of modulated wave have been obtained. Numerical estimations have been made for nInSb crystal at 77 K illuminated by a 10.6 μm CO_{2} laser. The dependence of threshold pump amplitude and growth rate of modulated wave on wave number, externally applied magnetic field (via electroncyclotron frequency) and doping concentration (via electronplasma frequency) have been explored. It has been found that the threshold pump amplitude can be lowered whereas the growth rate of modulated wave can be enhanced by proper selection of externally applied magnetic field and doping concentration of semiconductor crystal. The results of the present analytical investigation strongly manifest the importance of magnetoactive heavily ntype doped III–V semiconductors as appropriate hosts for modulational instability processes.
Incorporation of Lithium Ion on Zn:CdS Quantum Dots: Structural and Optical Investigations P. Sakthivel, I. Devadoss, S.V. Vijayasundaram Romanian Journal of Physics 65,
607 (2020)
Zn and Li doped CdS quantum dots were fabricated via the coprecipitation method. Xray diffraction, UVVisible, Fourier transformed infrared (FTIR), photoluminescence studies were carried out. The obtained results, reveal cubic crystal structure, blue shifted optical band gap and red photoluminescence emission. The studied material will be suitable for optoelectronic applications.
StressDeformation Curve of FCC Interstitial Alloy AuSi under Pressure N.Q. Học, B.D. Tinh, N.D. Hien Romanian Journal of Physics 65,
608 (2020)
Analytic expressions of characteristic nonlinear deformation quantities such as the density of deformation energy, the maximum real stress and the limit of elastic deformation for FCC interstitial alloy AB under pressure are derived from the statistical moment method. The theoretical results are applied numerically to AuSi and the calculated results are compared with ones of Au and experiments.
Biophysics and Medical Physics
Simulation of Gas Dynamics in a Subject Breathing via SelfContained SelfRescue Apparatus E.S. Ermolaev, A.I. Dyachenko, Y.A. Shulagin, A.V. Suvorov, K.S. Parshin Romanian Journal of Physics 65,
704 (2020)
Selfcontained selfrescue (SCSR) breathing devices are the only option for providing breathable air if hazardous components cannot be removed from external air after underground accidents. In this study, we developed a mathematical model of human breathing with an SCSR apparatus. The model describes the gascontent dynamics in the three system compartments: the lungs, body tissues and a SCSR apparatus. The results of simulations agreed well with experimental data obtained from a volunteer breathing through the apparatus.
On the Effective Dose Estimation Based on TwoDosimeter Algorithm: A Method to Reduce Uncertainty K. Karimi Shahri, L. Rafat Motavalli, H. Miri Hakimabad Romanian Journal of Physics 65,
705 (2020)
The twodosimeter algorithm (TDA) is an improved method for estimating the effective dose (E) in unknown radiation fields. For such fields, energy spectrum and radiation geometry are not known, although the radiation source characteristics are specified. The twodosimeter algorithm can be used to overcome these limitations, however, resulting in significant dose overestimations for Laterals (LATs), Overhead (OH) and Underfoot (UF) beam directions. This study attempts to design a Thermoluminescent Dosimeter (TLD)based tool that does not overestimate E for the mentioned radiation directions, by putting a shield on the dosimeter. The shape, materials, and size of the shield were appropriately selected so that the response of the dosimeters was similar to the body when it is irradiated to the external exposure. The shape of the shield was chosen as a half ellipsoid positioned on top of a cylinder with an elliptical surface with appropriate sizes. Aluminum oxide (Al_{2}O_{3}) and Chrysoberyl (BeAl_{2}O_{4}) were considered as materials for the shield. Dosimeters responses have been tested for 0.08, 0.3, and 1 MeV photon energies with various beam directions. Results showed that, by applying these new dosimeters, the twodosimeter algorithms E_{est} = 0.97 R_{f} + 0.42 R_{b} and E_{est} = 0.51 R_{f} + 0.22 R_{b} were obtained for dosimeters with Al_{2}O_{3} and BeAl_{2}O_{4} shields, respectively. Using this novel approach, more than 80% of E_{est} was in the –10% to 100% span that is an ideal range of TDA for all photon energies and beam directions. There were overestimations in the order of 200% to 280%, for few irradiation angles, which is much less than the overestimation of the previous algorithm and dosimeters without shield (580%).
Environmental and Earth Physics
A Comparative Study of Sodar, Lidar Wind Measurements and Aircraft Derived Wind Observations Livius Buzdugan, Sabina Stefan Romanian Journal of Physics 65,
810 (2020)
The paper is focused on the comparison between Sodar and Lidar wind measurements and high resolution wind observations derived from ModeS data sent by aircraft arriving at and departing from Bucharest Henri Coanda airport (LROP) to an air traffic control radar. Between 7–9 January 2018, the two prevailing wind directions – with their corresponding configurations of runways – manifested themselves at the airport as westerly winds veered to easterly, with colder air flowing in the Romanian Plain behind a cold front that swept up north. The results show that, for both prevailing wind directions, Sodar and Lidar wind profiles within the 40–600 m height domain are representative of the aerodrome and vicinity in nonconvective conditions. Similarly, the “virtual” wind profiles obtained from wind data derived from ModeS data of aircraft flying in the aerodrome area offer a possible alternate solution, where remote sensing instruments are not available. The aim of the study was to assess how the synergy of these instruments and data sources can service the detection of low level wind shear and monitoring of the wind field in the terminal area of the aerodrome.
Larger Peak Ground Accelerations in ExtraCarpathian Area than in Epicenter Gheorghe Marmureanu, Ioan Sorin Borcia , Alexandru Marmureanu, Carmen Ortanza Cioflan, Toma Dragos, Ion Ilieş, GeorgeMarius Craiu, Irina Stoian Romanian Journal of Physics 65,
811 (2020)
We report on peak ground accelerations (PGAs) recorded for three strong earthquakes in Vrancea, Romania (August 30, 1986, moment magnitude M_{w} = 7.1; depth h = 131.4 km; May 30, 1990, M_{w} = 6.9 depth 90.9 km; May 31, 1990, M_{w} = 6.4 depth 86.9 km & October 28, 2018, M_{w} = 5.5 depth 147.8 km). The PGAs increase with increasing epicentral distance, and then decrease for larger distances. These real data may be a new chalenge for the probabilistic seismic hazard studies or other methodologies, which take the epicentral PGA as a basic input parameter. To our knowledge, this phenomenom has not been reported elsewhere. Its spatial regularity leaves open the possibility of ascribing it to the soil particularities, like nonlinearities.
Applied and Interdisciplinary Physics
Study on the Mechanical Properties of Generation IV Innovative Materials by NonStandardized Method L.N. Stoica, A.I. Nitu, V. Radu Romanian Journal of Physics 65,
904 (2020)
The paper objective is to investigate the mechanical properties of tubes with small diameter and made from new “ODS steels” (Oxide Dispersion Strengthened steels). These new materials are candidate materials for fuel claddings in the generation IV reactors. This study improves the nonstandard method (Ring Tension Test) RTT used for the investigating of the mechanical properties of ODS steel tubes.
The Dispersion of the Elemental Composition of Samples from the Same Batch of Optical Materials Used in Dosimetry Applications L.C. Tugulan Romanian Journal of Physics 65,
905 (2020)
In this paper, a study of the dispersion of the elemental composition of samples from the same batch of an optical material used in dosimetry applications was performed, by using XRF spectrometry. Optical materials are widely used in many dosimetry applications, one of the most frequent ones being the retrospective dosimetry, meaning postevent dose measurements. Besides many other aspects that must be carefully considered, the dispersion of the elemental composition of the optical materials from the same batch is very important due to the fact that it can have a significant impact on the precision and the accuracy of the results.
