Volume 62, Number 5-6, 2017
Theoretical, Mathematical, and Computational Physics
The Linear Complex PT Symmetric Potential R. J. Lombard, R. Mezhoud Romanian Journal of Physics 62,
112 (2017)
The spectrum of a PT-symmetric complex-valued linear potential is investigated. Working in the $D = 1$ dimensional space, we consider $\mathcal{V}(x) = \lambda|x| + icx$. Semianalytical solutions are given by using the properties of the Airy functions. The numerical integration of the differential equation system is discussed. We show that the number of eigenstates with a real eigenvalue is limited, depending on the ratio $c/\lambda$ and on the quantum number $n$. This is reflecting the spontaneous breaking of PT symmetry. For the ground state, we conjecture the eigenvalue to be real for any value of $c$.
Study of Quasiclassical Dynamics of Trapped Ions Using the Coherent State Formalism and Associated Algebraic Groups Bogdan Mihalcea Romanian Journal of Physics 62,
113 (2017)
The time dependent variational principle (TDVP) has been applied on coherent state orbits and the Hamilton equations of motion on Kähler (symplectic) manifolds result. The classical Hamilton functions associated to the system are realized as the expected values of the quantum Hamiltonian on symplectic coherent states. The formalism applies to Hamilton functions that are nonlinear in the infinitesimal generators of a dynamical symmetry group (in case of 3D ion traps). Using symplectic coherent states, the explicit classical equations of motion on the unit disk have been obtained for any algebraic model that admits the dynamical group $Sp(2,\mathbb{R})$. The corresponding quasienergy states are explicitly realized as coherent states parameterized by the stable solutions of the corresponding classical equations of motion. The explicit expression of the quantum and classical Hamilton functions, particularized for combined (Paul and Penning) and ideal Paul traps, are obtained for the first time, taking into consideration the effect of trap electric potential nonlinearities. We also obtain the explicit equations of motion for a combined octupole trap, which represents an original result. A dequantization algorithm results.

Lie Symmetry, Full Symmetry Group and Exact Solutions to the (2+1)-Dimensional Dissipative AKNS Equation Zheng-Yi Ma, Hui-Lin Wu, Quan-Yong Zhu Romanian Journal of Physics 62,
114 (2017)
In this paper, a detailed Lie symmetry analysis of the (2+1)-dimensional dissipative AKNS equation is performed. The general finite transformation group is given via a simple direct method, which is in fact equivalent to Lie point symmetry group. The similarity reductions are considered from the general Lie symmetry and some exact solutions of the (2+1)-dimensional dissipative AKNS equation are obtained.
Solution of Maxwell’s Wave Equations in Bicomplex Space Ritu Agarwal, Mahesh Puri Goswami, Ravi P. Agarwal, Kamma Kesa Venkataratnam, Dumitru Baleanu Romanian Journal of Physics 62,
115 (2017)
The concept of bicomplex numbers is introduced in Electromagnetics, with direct applications to the solution of Maxwell’s equations. In this paper, we discuss the technique to find the analytic solution of the electromagnetic wave equation in vacuum with the help of bicomplex analysis as tool. Also, we find the solution of Gaussian pulse wave using bicomplex vector field.
Exact Breather-Type Solutions and Resonance-Type Solutions of the (2+1)-Dimensional Potential Burgers System Yeqiong Shi Romanian Journal of Physics 62,
116 (2017)
In this paper, the (2+1)-dimensional potential Burgers system is investigated by means of the extended homoclinic (heteroclinic) test method. Some new types of exact solutions of the (2+1)-dimensional potential Burgers system are obtained, such as the periodic breather-type solutions, two-soliton fusion wave solutions, Y-type soliton resonance solutions, peakon solutions, and so on. These results enrich the variety of the dynamics of the higher-dimensional nonlinear wave fields.
Atomic, Molecular, and Optical Physics
Phase-Dependent Quantum Interferences with Three-Level Artificial Atoms Victor Ceban Romanian Journal of Physics 62,
207 (2017)
The phase dependence of the cavity quantum dynamics in a driven equidistant three-level ladder-type system found in a quantum well structure with perpendicular transition dipoles is investigated in the good cavity limit. The pumping laser phases are directly transferred to the superposed amplitudes of the cavity-quantum-well interaction. Their phase difference may be tuned in order to obtain destructive quantum interferences. Therefore, the cavity field vanishes although the emitter continues to be pumped.
Condensed and Soft Matter Physics
Effect of Powder Type on Structure and Properties of Carbon Based Coatings L. Marcinauskas, R. Kėželis, Ž. Kavaliauskas, A. Žunda, M. Milieška Romanian Journal of Physics 62,
605 (2017)
Carbon composite coatings were prepared using an atmospheric pressure plasma spraying on the steel substrate from different feedstock powders. The effect of the various powder types on the surface morphology and structure of the sprayed coatings was investigated. The prepared coatings surface morphology depends on the initial powder morphology and chemical composition. The coating sprayed from the P1 powder (wood waste) demonstrated the lowest surface roughness value. The oxygen concentration in the sprayed coatings increased. The highest oxidation was observed when the graphite flake-like powder (P4) were used. The C/O atomic ratio in the P3 coating (deposited using activated carbon powder), decreased 5.4 times, while the Cu concentration increased 2.4 times compared to the initial powder. The highest specific surface area (~25.94 m$^2$/g) and microhardness value (202 HV) were observed for the coating deposited using P1 powder.

Aspects Regarding the Hot Fracture Behavior of 42CrMo4 Alloy M. Pop, D. Frunza, F. Popa, A. Neag Romanian Journal of Physics 62,
606 (2017)
The hot tensile deformation behavior of 42CrMo4 steel are studied by uniaxial tensile tests with the temperature range of 750-1000°C and strain rate range of 0.1-0.005s$^{−1}$. The effects of hot forming process parameters (strain rate and deformation temperature) on the elongation to fracture and fracture characteristics are analyzed. The flow behavior is significantly affected by the deformation temperature, strain and strain rate. The flow stress decreases with the increase of deformation temperature and the decrease of strain rate. The flow stress firstly increases to a peak value and then decreases, showing a dynamic flow softening. This is mainly due to the dynamic recrystallization and material damage during the hot tensile deformation. The simulation results confirm the suitability of the current finite element software for modeling the three-dimensional hot tension of 42CrMo4 steel.
Environmental and Earth Physics
Determination of Heavy Metal Contents in Surface Water by Inductively Coupled Plasma-Mass Spectrometry: A Case Study of Ialomita River, Romania Ioana-Daniela Dulama, Cristiana Radulescu, Elena Daniela Chelarescu, Claudia Stihi, Ioan Alin Bucurica, Sofia Teodorescu, Raluca Maria Stirbescu, Ion Valentin Gurgu, Dorin Dacian Let, Nicolae Mihail Stirbescu Romanian Journal of Physics 62,
807 (2017)
Heavy metals are among the most significant surface water pollutants being extremely harmful to the environment and human health, in high concentrations. The aim of this study is to determine the heavy metals content (e.g. Cd, Cr, Pb, Cu, Ni and Fe), in order to establish the level of pollution at the surface waters of Ialomita River, from Romania, tributary of Danube river. A number of 66 water samples were collected from Ialomita River, in two representative points (i.e. upstream and downstream of Targoviste City) in four seasons during of the years 2015-2016. The elemental concentrations, in water samples, were obtained by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) technique using Thermo Scientific iCAP Qc system. A correlation between the heavy metal concentrations determined by ICP-MS spectrometry technique and physicochemical parameters: pH, turbidity, conductivity and salinity, was performed. Investigation has confirmed that high concentration of Pb, Cu and Fe are not appropriate for formation and development of aquatic organisms and may disturb the ecosystem of Ialomita River. Also, the obtained results shown very clearly that the load of analyzed metals (i.e. Pb, Fe, Cr, Cu, and Ni), were higher in samples collected from Ialomita River, downstream of Targoviste City.

Avoidance Strategy for Soil-Structure Resonance by Considering Nonlinear Behavior of the Site Materials D. Bratosin, B. F. Apostol, S. F. Balan Romanian Journal of Physics 62,
808 (2017)
An appropriate estimation of the site-structure resonance period involves the nonlinear dependence of the site natural period on strain or loading level. The site materials are assumed in this paper to be nonlinear viscoelastic materials, modeled by a nonlinear Kelvin-Voigt model. By using resonant column tests we can quantify the nonlinear dependence of the site natural period in the normalized form $T_n = T_n (\bullet)$, such that the nonlinear site natural function acquires the form: $T_g(\bullet) = T_0 \cdot T_n (\bullet)$, with $T_0$ being the fundamental period from seismic recordings. The method consists in laboratory experiments on soils samples for a site with sufficient seismic records. In order to mitigate seismic risk, the structures fundamental period must be outside the range of the computed nonlinear values.

Probabilistic Seismic Hazard Assessment in the Black Sea Area I.A. Moldovan, M. Diaconescu, R. Partheniu, A.P. Constantin, E. Popescu, D. Toma-Danila Romanian Journal of Physics 62,
809 (2017)
The paper has as final goal the probabilistic assessment of seismic hazard in the Black Sea area as input for the tsunami hazard evaluation. Maximum and most expected magnitudes and their recurrence periods have been computed for all defined seismogenic sources from the marine area, and hazard curves have been plotted.
Applied and Interdisciplinary Physics
Test Bench Design for Radiation Tolerance of Two ASICs V. M. Placinta, L. N. Cojocariu, C. Ravariu Romanian Journal of Physics 62,
903 (2017)
We present the characteristics and versatile functionality of an automatic test bench employed in the radiation-hardness assessment of two AMS 0.35 µm SiGe BiCMOS technology Application Specific Integrated Circuits (ASICs). Both MAROC3 and SPACIROC2 chips are dedicated to read-out multi-anode photomultiplier tubes. The test bench solution was designed to work in various radiation environments (X-rays, protons and light or heavy ion cocktails). The setup allows precise and fast measurement of Single Event Effects (SEE) rates in conjunction with radiation cumulative effects. To estimate the later current and voltage values in key blocks on the chip are continuously registered before and during the irradiation. The tests are set to allow periodic checks of DAC linearity in tandem with trigger efficiency S-curves and pedestal characterization. Each test bench element is presented in detail along with data acquisition system for these ASICs.
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