Volume 62, Number 78, 2017
Theoretical, Mathematical, and Computational Physics
On the Motion of an Electric Charge in HighIntensity Electromagnetic Radiation Cristina Miron, Marian Apostol
Romanian Journal of Physics 62,
117 (2017)
The motion of an electrically charged particle in highintensity electromagnetic radiation is revisited; the problem is relevant for the charge acceleration in ultraintense laser radiation in vacuum. It is shown that for many practical purposes a charged particle accelerated by a traveling highintensity electromagnetic plane wave can be treated as a (quasi)classical relativistic particle. The effects of the damping force are estimated by a direct method; it is shown that in realistic cases these effects are small. A stopping point (turning, reflection point) is identified for charges propagating initially (launched) against the electromagnetic beam; this circumstance has been considered recently by numerical simulations. Particular aspects of a relativistic quantummechanical charge accelerated by a highintensity electromagnetic wave are discussed, which indicate that a (quasi) classical treatment is appropriate for very strong fields in many respects. Also, it is shown that charges in a standing electromagnetic wave behave as nonrelativistic and quantummechanical charges, as in an optical lattice. The increase in the particleantiparticle energy gap in high electromagnetic fields is highlighted, which points out difficulties in achieving pair production assisted (induced) by highintensity electromagnetic radiation in vacuum.
Parallel Line Rogue Waves of a (2+1)Dimensional Nonlinear Schrödinger Equation Describing the Heisenberg Ferromagnetic Spin Chain Wei Liu
Romanian Journal of Physics 62,
118 (2017)
Under investigation in this paper is a $(2+1)$dimensional nonlinear Schrödinger equation describing the Heisenberg ferromagnetic spin chain. A general explicit form of rogue wave solutions for the $(2+1)$dimensional nonlinear Schrödinger equation is given in terms of the Gram determinants by employing the bilinear method. The relevant formulas involve determinants whose matrix elements are simple polynomials. The fundamental rogue wave is called line rogue wave in the $(x, y)$plane, which arises from a constant background with a line profile and then disappears into the same background. Highorder rogue waves consist of several parallel line rogue waves, and describe the interaction of several fundamental rogue waves. Besides, their dynamical behaviors in the $(x, t)$plane are also investigated by threedimensional plots.
Numerical Solutions of the Quadratic Form of the Spinless SalpeterType Equation JiaoKai Chen
Romanian Journal of Physics 62,
119 (2017)
In this paper, numerical solutions of the quadratic form of the spinless Salpetertype equation (QSSE) are given by employing the Nyström method with the TANH rule. The upper bounds on the groundstate energy are presented by employing the variational method.
Nuclear Physics
Simple Empirical Relations for $\alpha$Decay Half Lives of Superheavy Nuclei I. Silisteanu, C.I. Anghel
Romanian Journal of Physics 62,
303 (2017)
Simple relations for $\alpha$decay halflives are obtained from the systematics of experimental decay data and calculated decay properties. The parameters of systematics are obtained by the fit of $\alpha$decay halflives of 80 nuclei at which there are accurate $Q_{\alpha}$ measurements (with errors not greater than 50 keV). The comparative analysis of experimental and calculated halflives (within the shell and "onebody" models) allows us to estimate the spectroscopic factor in $\alpha$decay. The $\alpha$decay halflife predictions are performed for the region of nuclei with Z=104118.
An Unpaired Study on the Isomeric States $8^$ and $16^+$ in $^{178}$Hf M. Rabizadeh, A. Kardan
Romanian Journal of Physics 62,
304 (2017)
The isomeric states $8^{}$ and $16^{+}$ in $^{178}$Hf are analyzed within the framework of unpaired Cranked NilssonStrutinsky (CNS) model including Strutinsky renormalization and the LublinStrasbourg Drop (LSD) and Finite Range Liquid Drop (FRLDM) liquid drop methods. Special attention is given to the potential energy surfaces to determine the deformation parameters in the ground and isomeric states. Our calculations show that the hexadecapole deformations in the isomeric states are somewhat larger than those in previous study. Also, the pairing correlation has no effects on the isomeric states shape, while has a significant effects on the excitation energies.
Biophysics and Medical Physics
Characterization of Some PhysicoChemical Properties and Interactions of Human and Bovine Serum Albumins with Mitomycin C C. G. Chilom, B. Zorilă, A. I. Popescu
Romanian Journal of Physics 62,
702 (2017)
Physicochemical properties, molecular interactions and thermodynamic stability of human and bovine serum albumins in complexes with mitomycin C were investigated. The pH and temperature influence on serum albumins properties and the binding mechanism of mitomycin C to these proteins have been monitored by spectrometry and spectrofluorimetry methods.
Gross Alpha, Gross Beta and ^{40}K Activities and Daily Effective Dose Due to Natural Radionuclides from Food Supplements Violeta Pintilie, Antoaneta Ene, Lucian P. Georgescu, Dana Iulia Moraru
Romanian Journal of Physics 62,
703 (2017)
The fast rhythm of everyday life has led to habit of people to consume food supplements. The consumption of food supplements represents a pathway for the ingestion of natural radionuclides. For the radiological risk assessment studies, 14 samples of food supplements have been analysed in this work for gross alpha and gross beta activities, as well as for concentrations of potassium40. The concentrations of potassium40 radioisotope were calculated on the basis of the concentrations of total potassium, determined by sequential HighResolution Continuum Source Atomic Absorption Spectroscopy (HRCS AAS) using the flame technique. The investigations revealed values for gross alpha activities, gross beta activities and the concentrations of $^{40}$K in the ranges of 0.25 to 30.92 mBq g$^{1}$ , 2.18 to 769.59 mBq g$^{1}$ and <LOD (limit of detection) to 651.52 mBq g$^{1}$ , respectively. The maximum values were obtained for a supplement based on lucerne (alfalfa) extract, while the minimum ones were found for a supplement based on fish oil. For comparison purpose, 5 samples of frequently used drugs were also analysed. The corresponding values found for the investigated drugs are lower than those obtained for food supplements. High correlation coefficients have been found in all the studied samples between the gross alpha activity and gross beta activity (0.646), and between the gross beta activity and concentration of potassium40 (0.778). The effective dose due to ingestion of natural radionuclides from food supplements varied as following: from 1.54 to 97.41 nSv per daily dose, assigned to $^{210}$Po, and from 20.12 to 1393.92 nSv per daily dose, assigned to $^{228}$Ra. The effective dose due to the ingestion of $^{40}$K from food supplements ranged from 0 to 10.60 nSv per daily dose. The obtained values of effective doses were compared with the daily dose values recommended by the current EU legislation and World Health Organization (WHO).
Environmental and Earth Physics
Numerical Modelling of the Bucharest Urban Heat Island with the WRFUrban System A. Iriza, R.C. Dumitrache, S. Stefan
Romanian Journal of Physics 62,
810 (2017)
The main purpose of this study is to assess the ability of the Weather Research and Forecasting (WRF) model to capture the Bucharest urban heat island. Simulations with the WRF model run at high resolutions (4.5 km  1.5 km  500 m) in different configurations were carried out in order to test the sensitivity to urban parameterization schemes employed by the model. Several cases from March 2014 were selected for this purpose. The model was integrated using initial and lateral boundary conditions from the European Centre for Medium Range Weather Forecast (ECMWF) model. Numerical simulations were performed using no urban parameterization scheme, a single level urban canopy model (SLUCM) or a building environment urban parameterization (BEP). Results from the numerical simulations are analysed in comparison to 2 m temperature measurements from two synoptic stations (urban and periurban) in Bucharest. Results suggest a better performance of the WRF modelling system when a complex urban parameterization scheme (BEP) is used.
Numerical Simulation of the Bucharest Urban Heat Island with the WRF Modelling System Using Different LandUse Data A. Iriza, S. Ştefan, R.C. Dumitrache
Romanian Journal of Physics 62,
811 (2017)
In this study we investigate the Bucharest Urban Heat Island using the Weather Research and Forecasting (WRF) numerical weather prediction model coupled with two sets of landuse data. The WRF model was run at three high resolutions (4.5 km, 1.5 km and 500 m) using United States Geological Survey (USGS) or ModerateResolution Imaging Spectroradiometer (MODIS) landuse data. Initial and lateral boundary conditions were obtained from the COnsortium for Smallscale MOdeling (COSMO) limited area model at 7 km horizontal resolution. Numerical simulations were performed for selected days in March 2014. Comparisons against 2 m temperature observations from an urban and a periurban station in the Bucharest Urban Area suggest that employing ModerateResolution Imaging Spectroradiometer (MODIS) data leads to a better performance of the model in capturing the phenomenon for these specific days. Differences in the intensity of the predicted Bucharest Urban Heat Island are also influenced by the horizontal resolution of the model; better results are generally obtained for the 500 m horizontal resolution.
Radiological Risk Assessment for Hot Cell Decontamination C. Tuca, R. Deju, A. Zorliu
Romanian Journal of Physics 62,
812 (2017)
The paper describes the radiological impact on the workers who perform the decontamination of a hot cell from the VVRS nuclear research reactor (NR), used for production of radioisotopes during the operation of the NR. The assessment of dose equivalent takes into account the used manual procedure to make the floor decontamination. The identification of the high radiation areas is done by measurements of the ambient dose equivalent by direct measurements using: (i) a portable digital survey meter with a gamma dose rate probe placed at less 1 cm above the surface and (ii) thermoluminescent dosimeters placed directly on surface and indirectly, by (iii) gamma ray spectrometry measurements of the samples taken from each high radiation area of the contaminated floor. Although the measurement conditions were difficult the results are in a satisfactory agreement, validating the measurement. The dose rate assessment is done for the worker A that performs the direct measurements of the ambient dose equivalent and for worker B who performs the decontamination of the contaminated area. The external penetrant dose equivalent for worker A is less than 0.28 mSv (for an operation at about 5 minutes)  3.39 mSv/h. For the worker B the dose from external irradiation is 1.59 mSv (for an operation 12 minutes), a dose rate of 7.97 mSv/h and the internal committed effective dose, E(50) received by worker due to air inhalation is 1.63 μSv.
Seasonal Modeling of Hourly Solar Irradiation Series M. Paulescu, N. Pop, N. Stefu, E. Paulescu, R. Boata, D. Calinoiu
Romanian Journal of Physics 62,
813 (2017)
Increasing usage of solar energy and the integration of photovoltaic power plants into the grid demand accurate knowledge and forecasting of the solar energy resources. This paper reports on the seasonal autoregressive integrated moving average model (sARIMA) applied to the hourly solar irradiation data series. The standard sARIMA model, a new adaptive sARIMA model and a model based on multivalued logic are compared in terms of forecasting accuracy. A simple procedure of including relevant information into sARIMA model is proposed, by expressing the model coefficients as linear functions of external predictors, such as various radiometric and meteorological quantities and quantifiers for the state of the sky. Global and diffuse solar irradiance measured on the Solar Platform of the West University of Timisoara in 2009 and 2010 are used for testing. The results show that the models performances depend on the stability of the radiative regime, and that only minimal improvement is obtained by using the adaptive method.
Measurement of $^{222}$Rn in Bottled Waters from Various Sources and Estimation of Effective Dose, Saudi Arabia F. Alshahri
Romanian Journal of Physics 62,
814 (2017)
The present study was carried out to measure the radon activities in twenty six local and imported bottled waters using nuclear track detector type CR39. Radon activities and exhalation rates ranged between 0.020.40 Bq L$^{1}$ and 0.448.33 mBq m$^{2}$ h$^{1}$, respectively. The mean value of radon activities in local bottled waters was lower than the mean value in imported bottled waters. However, all these values are lower than the allowed level in drinking water, 11 Bq L$^{1}$. The effective doses due to ingestion of radon for children and adults were estimated to assess the potential health risk. These doses were well below the recommended level by World Health Organization.
Seismic Wave Attenuation in the Vrancea Region. Part I. The Approach for 1D QModel Estimation L. Ardeleanu
Romanian Journal of Physics 62,
815 (2017)
An approach based on highfrequency waveform modelling is proposed to estimate 1D (depthdependent) models of the quality factor of the medium Q in the area located at the bending of the Eastern Carpathians. The algorithm is a nonlinear inversion in which the normalised amplitude spectra of local records of lowtomoderate magnitude earthquakes are compared with the synthetic signal spectra, generated for point sources with the same location and mechanism as the recorded events. The best fitting Qmodels are determined by minimizing the sum of squares of logarithmic residuals between theoretical and observed spectra. Several tests investigating the effect of the uncertainty of earthquake mechanism and hypocenter location on the resolution of the retrieved attenuation structures are presented.
Investigation of PreEarthquake Ionospheric Anomalies Using VLF/LF INFREP European and GNSS Global Networks Christina Oikonomou, Haris Haralambous, Iren Adelina Moldovan, Razvan Greculeasa
Romanian Journal of Physics 62,
816 (2017)
Ionospheric TEC (Total Electron Content) variations and Low Frequency (LF) signal amplitude data prior to three large earthquakes (M $\ge$ 6) in Greece were analyzed using observations from the Global Navigation Satellite System (GNSS) and the European INFREP (International Network for Frontier Research on Earthquake Precursors) networks respectively, aiming to detect potential ionospheric anomalies related to these events and describe their characteristics. For this, spectral analysis on TEC data and terminator time method on LF data were applied. It was found that TEC perturbations appeared few days (17) up to few hours before the events lasting around 23 hours, with periods 20 and 35 minutes which could be associated with the impending earthquakes. In addition, in all three events the sunrise terminator times were delayed approximately 2040 min few days prior and during the earthquake day.
Applied and Interdisciplinary Physics
EURONEAR – First Light Curves and Physical Properties of Near Earth Asteroids A. Aznar Macías, M. Predatu, O. Vaduvescu, J. Oey
Romanian Journal of Physics 62,
904 (2017)
Part of the European Near Earth Asteroids Research (EURONEAR) project, in 2014 we started a survey to observe light curves of Near Earth Asteroids (NEAs) using the available telescopes of this network. This is the first paper presenting lightcurves and physical properties of 17 NEAs observed by two amateur astronomers owning small facilities located in good sites, namely a 0.36 m telescope at Isaac Aznar Observatory (Aras de los Olmos, Spain) and a 0.61 m telescope at Blue Mountain Observatory (Leura, Australia). We confirm most recent or older results and find new ones.
