Volume 59, Number 56, 2014
Mathematical and Theoretical Physics
Solving Partial qDifferential Equations within Reduced qDifferential Transformation Method H. Jafari, A. Haghbin, S. Hesam, D. Baleanu Romanian Journal of Physics 59,
399407 (2014)
In this paper, the reduced qdifferential transform method is presented for solving partial differential equations. In this method, the solution is calculated in the form of convergent power series with easily computable components. Three test problems are discussed to illustrate the effectiveness and performance of the proposed method. The results show that the proposed iteration technique is very effective and convenient.
An Accurate Legendre Collocation Scheme for Coupled Hyperbolic Equations with Variable Coefficients E.H. Doha, A.H. Bhrawy, D. Baleanu, M.A. Abdelkawy Romanian Journal of Physics 59,
408420 (2014)
The study of numerical solutions of nonlinear coupled hyperbolic partial differential equations (PDEs) with variable coefficients subject to initialboundary conditions continues to be a major research area with widespread applications in modern physics and technology. One of the most important advantages of collocation method is the possibility of dealing with nonlinear partial differential equations (NPDEs) as well as PDEs with variable coefficients. A numerical solution based on a Legendre collocation method is extended to solve nonlinear coupled hyperbolic PDEs with variable coefficients. This approach, which is based on Legendre polynomials and GaussLobatto quadrature integration, reduces the solving of nonlinear coupled hyperbolic PDEs with variable coefficients to a system of nonlinear ordinary differential equations that is far easier to solve. The obtained results show that the proposed numerical algorithm is efficient and very accurate.
Solitons and Periodic Solutions to the DissipationModified KdV Equation with TimeDependent Coefficients Houria Triki Romanian Journal of Physics 59,
421432 (2014)
In this work, a dissipationmodified Kortewegde Vries (KdV) equation is considered. The equation is relevant to describe, for instance, nonlinear BénardMarangoni oscillatory instability in a liquid layer heated from above. In particular, the model with timedependent coefficients required for the case of inhomogeneous media is studied. Periodic solutions and soliton solutions of this equation are obtained using the sinecosine and solitary wave ansatz methods. Parametric conditions for the existence and uniqueness of exact solutions are presented. These analytical findings may be of significant importance for the explanation of physical phenomena arising in nonlinear systems described by the dissipationmodified KdVtype equations.
Symbolic Computation of Some Nonlinear Fractional Differential Equations A. Biswas, A.H. Bhrawy, M.A. Abdelkawy, A.A. Alshaery, E.M. Hilal Romanian Journal of Physics 59,
433442 (2014)
This paper studies a few fractional nonlinear equations from mathematical physics. The fractional derivatives are in the sense of modified RiemannLiouville fractional derivative. The $\frac{G'}{G}$expansion method is applied to retrieve solutions to these equations. Several forms of solutions are obtained that are listed in this paper.
Modified Adomian Decomposition Method for Double Singular Boundary Values Problems Yinwei Lin, Cha'oKuang Chen Romanian Journal of Physics 59,
443453 (2014)
This paper deals with the double singular boundary value problems of second order. The differential equation has two singular points and the singular points are just the boundary points. Nonlinear models are solved by this method to get more reliable and efficient numerical results. It can also be used to solve singular boundary value problems where the traditional methods fail.
A Study on Couplings of the FifthOrder Integrable SawadaKotera and Lax Equations AbdulMajid Wazwaz, Abdelhalim Ebaid Romanian Journal of Physics 59,
454465 (2014)
We construct nonlinear integrable couplings of the fifthorder nonlinear integrable SawadaKotera (SK) equation and Lax equation. We use the algebra of coupled scalars to construct the two classes of couplings. We study the constructed couplings by using the simplified Hirota’s method. We show that these classes of couplings possess multiple soliton solutions the same as the multiple soliton solutions of the SK and the Lax equations, with one change in the sign of the transformation used. This change of signs exhibits soliton solution then antisoliton solution, consecutively.
On the Stochastic Burgers Equation with Moving Boundary Pablo Suarez, Abhinandan Chowdhury Romanian Journal of Physics 59,
466475 (2014)
This paper studies the stochastic Burgers equation with moving boundaries. The solution is obtained numerically by employing differentiation matrices which are derived from spectral collocation. The stochastic term is considered only to be timedependent. It is argued that the solely timedependent stochastic term does not create considerable amount of perturbation in the wave profile between the boundaries. This is verified by presenting contour plots from appropriate viewpoints.
Finite Element Analysis of a TwoDimensional Linear Elastic Systems with a Plane "rigid Motion S. Vlase, C. Dănăşel, M.L. Scutaru, M. Mihălcică Romanian Journal of Physics 59,
476487 (2014)
Discretizing a mechanical structure as part of finite element analysis makes it necessary to use a variety of finite elements, according to the shape and geometry of the analyzed system. Twodimensional finite elements are widely used in finite element analysis and using them is generally easy and fast. For mechanical systems that also exhibit a general “rigid” plane motion, dynamic analysis enforces the use of numerous additional terms that can no longer be neglected. In this paper we determine motion equations for a twodimensional finite element and we distinguish the additional terms that can eventually change the qualitative behavior of the system. The motion equations are obtained using Lagrange’s equations.
A Note on Teleparallel Lie Symmetries Using Non Diagonal Suhail Khan, Tahir Hussain, Gulzar Ali Khan Romanian Journal of Physics 59,
488499 (2014)
This paper considers teleparallel theory of gravitation and explores Killing and proper homothetic vector fields for non diagonal tetrad of KantowskiSachs spacetime. For the purpose, direct integration technique has been used. It turns out that the number of Killing vector fields is either four or seven. The seven generators of teleparallel Killing vector fields, responsible for conservation of energy, linear and angular momentum are recovered and other three generators responsible for spin angular momentum are lost. The effect of torsion on Killing symmetry has also been determined for the spacetime under consideration. More interestingly, there exists no teleparallel proper homothetic vector field for the choice of nondiagonal tetrad of KantowskiSachs spacetime.
Bremsstrahlung in Noncommutative Quantum Mechanics Sevda Heydarnezhad Romanian Journal of Physics 59,
500503 (2014)
The intensity cross section for a nonrelativistic bremsstrahlung is calculated in noncommutative space. It is shown that for a soft bremsstrahlung the cross section is increased by a factor which is second order in noncommutativity parameter.
Nuclear Physics
Moments of Inertia for ^{93}Mo, ^{194}Ir and ^{196}Au I. Ami, M. Fellah, N.H. Allal, M.R. Oudih Romanian Journal of Physics 59,
504513 (2014)
The moments of inertia for ^{93}Mo, ^{194}Ir and ^{196} Au are studied as a function of the nuclear deformation and the nuclear temperature. The calculations have been carried out in the framework of the Inglis cranking model by taking into account the pairing correlations using the path integral formalism. The single particle energies and eigen functions used are those of a deformed WoodsSaxon mean field. These nuclei were used in evaluations of induced neutron cross sections and revealed a strong dependence on momentum of inertia parameters.
Fission Paths Influenced by Proton and Neutron Magicity Nafiseh Shayan Shakib, R.A. Gherghescu, D.N. Poenaru, M.M. Firoozabadi, M.F. Rahimi Romanian Journal of Physics 59,
515528 (2014)
The macroscopicmicroscopic method is used to calculate penetrabilities for different fission channels around proton and neutron magic numbers from uranium and plutonium. The liquid drop part is obtained from the Yukawaplusexponential potential, whereas the singleparticle energy levels are computed with the deformed twocenter shell model. The shell correction part is obtained by the Strutinsky method, separately for protons and neutrons. Calculations are applied to the fission of U and Pu and penetrability values are presented for the most favoured channels. The dynamical part is approached through the multidimensional minimization of the action integral within the typical deformation space of nuclear binary proceses.
The Role of Athermal Fusion in Fast Ignition Driven by Ion Beams A. Ghasemizad, B. Khanbabaei, S. Khoshbinfar Romanian Journal of Physics 59,
529543 (2014)
The fast ignition scheme is recognized as a potentially promising approach to achieve the highenergygain target performance needed for commercial inertial confinement fusion. The hot spot heating process by an assumed deuteron beam is evaluated in order to estimate the contribution of the energy produced by the deuteron beamtarget fusion to the heating process. So, deuteron beam was considered with Maxwellian energy distribution at temperature of 3MeV. Then, the deuteron energy loss and range, including Coulomb and nuclear elastic interactions, in the uniformly precompressed fuel, with density 300 g$\cdot$cm^{3}, were calculated. By calculating the contribution of alpha particles produced by the athermal nuclear reactions and nuclear elastic scattering, power deposition of deuteron beams increased up 6% compared with the fast ignition by similar ion beams. This can lead to reduced energy delivered by the external beam.
Condensed Matter
On the Selective Copper Substitution with Zn2+ and Ni2+ Ions in LSCO Cuprates A. Oprea, S. Adam, Gh. Adam Romanian Journal of Physics 59,
544549 (2014)
Direct proof of the role of the CuO_{2} planes in the occurrence of the high temperature superconductivity in cuprates is got experimentally from the investigation of the behaviour of the critical temperature $T_c$ under gradual substitution of the in plane Cu^{2+} ions by divalent metal ions M^{2+}. In the present paper, functional dependencies $T_c = T_c(y)$ on the $y$ content of M ion are inferred from the existing experimental evidence on La_{1.85}Sr_{0.15}Cu_{1−y}M_{y}O_{4} (LSCO) for M^{2+} denoting either Zn^{2+} or Ni^{2+}. Data processing and analysis point, in both cases, to a sharp linear decrease of $T_c$ under the increase of $y$, with an M ion dependent slope. The result substantiates the basic hypothesis of the twodimensional twoband Hubbard model of searching the origins of the high$T_c$ superconductivity in cuprates inside individual CuO_{2} planes.
Spectroscopic Study of 2PhenylThiazole4YlMethylQuinolinium Iodine A. Pîrnău, M. Bogdan, M. Mic, M. Palage, R.A. Varga Romanian Journal of Physics 59,
550560 (2014)
Nowadays, the design of new compounds able to deal with resistant bacteria, having new structures and new targets of action, has become one of the most important areas in the antibacterial research purpose. Thiazolic quaternary ammonium salts were synthesized and assessed for antimicrobian, antispasmodic or spasmodic activity. Quinolinium compounds presented a good activity and for spectroscopic study was selected phenylthiazole4ylmethylquinolinium iodide (2PTMQI). The molecular structure of the compound 2PTMQI has been studied by Xray diffraction technique and ^{1}H and ^{13}C NMR spectroscopy. Xray diffraction technique indicates that 2PTMQI crystallizes like a cationic  anionic pair, the organic cation being the quinoline fragment and a phenyltiazole moiety linked by a methylene group and the corresponding iodine anion. The 1D and 2D NMR spectra of 2PTMQI were obtained at 300 K in DMSO solution and the chemical shifts of ^{1}H and ^{13}C nuclei were measured relative to TMS.
Plasma Physics
The Investigation of Different Discharge Modes in High Frequency ArgonZinc Discharge Z. Gavare, A. Svagere, R. Zvejnieks, A. Skudra Romanian Journal of Physics 59,
561569 (2014)
Highfrequency electrodeless lamps emit bright line spectra, thus being used in different scientific devices. Each device requires specific set of parameters for the light source, influenced by form, applied voltage and other properties. In this work we investigate influence of lamp sidearm on the intensity and stability of lines and look at differences between E and H discharge modes.
Monitoring the Evolution of the 3p2 Neon Metastable Level Density in Temporal Afterglow Plasma by Absorption Spectroscopy Using a Pulsed Hollow Cathode Spectral Source A. Surmeian, C. Diplasu, C. Atanasiu, M. Ganciu Romanian Journal of Physics 59,
570581 (2014)
The temporal evolution of the ^{3}P_{2} Neon metastable level density during the afterglow plasma of a high current pulsed hollow cathode discharge has been determined by an absorption spectroscopy technique using a pulsed hollow cathode spectral source. The measured values of the Neon 2^{3}P_{2} state density in the 560 µs temporal afterglow range are found to vary from 3 × 1012 ± 20% cm^{3} to 1.7 × 1011 ± 20% cm^{3} following an exponential decay curve. The absorption measurements have been performed on the ^{3}P_{2}  2p^{4} Neon transition at 633.4 nm. It was shown that using a pulsed spectral source with variable line emission broadening the best absorption sensibility was obtained when the line broadening of the spectral source is closed to the broadening of the emission line of absorbing species from the temporal afterglow plasma.
Optics
Optical Solitons in Birefringent Fibers with FourWave Mixing for Kerr Law Nonlinearity Michelle Savescu, A.H. Bhrawy, E.M. Hilal, A.A. Alshaery, Anjan Biswas Romanian Journal of Physics 59,
582589 (2014)
The dynamics of solitons in birefringent optical fibers with Kerr law nonlinearity is studied in this paper, in presence of fourwave mixing terms in the governing model. There are three main types of exact onesoliton solutions retrieved for this dynamical system. They are bright, dark, and singular solitons. The ansatz approach is the integration tool for the governing coupled equations. Several constraint conditions naturally fall out during the course of integration of the corresponding coupled nonlinear partial differential equations.
Environmental Physics
Change Points Detection and Models for Precipitation Evolution. Case Study Alina Bărbulescu, J. Deguenon Romanian Journal of Physics 59,
590600 (2014)
We discuss the problem of change point detection for the monthly precipitation series collected two meteorological stations in Dobrudja region and we model the series trend before and after the break points.
Evaluation of Limestone with NonInvasive Analytical Methods A.A. Balog, N. Cobirzan, L. BarbuTudoran Romanian Journal of Physics 59,
601607 (2014)
The aim of this paper it was to determine the properties of the limestone in order to prevent deterioration during the time that may result from differentiated behaviors (mechanical strength, porosity, chemical and mineralogical composition), differentiated deformability (elasticity modulus), and chemical reactions with the environment (solubility and pressure crystallization) or with mortar used in the construction (“gypsum black crust”). In this study, fine limestone powder samples and rock samples were analyzed by classical methods (density, weight, volume, apparent density, porosity, water absorption, compressive strength, thin sections) and by noninvasive one (XRD, EDX, SEM) in order to characterize them in details.
Microstructural Analysis for Investigation of Limestone Damages  A Case Study of the Fortress Wall of ClujNapoca, Romania A.A. Balog, N. Cobirzan, E. Mosonyi Romanian Journal of Physics 59,
608613 (2014)
This paper presents the results of petrographic analyses performed on limestone samples originated from a heritage construction situated in ClujNapoca city. The purpose of the paper is to highlight the importance of using the microstructural analysis (thin sections, SEM analysis) as additional methods to the conventional ones (mechanicalphysical determination), when the factors that lead to differing damaging of rocks are evaluated. The samples were investigated in thin sections, to the polarised light microscope, on fragments treated with Alizarin Red S as well as SEM analysis performed with the scanning electron microscope. The results found in investigated limestone samples highlighted the different percent of calcite and dolomite content and consequently the different degree of degradation of the rocks.
