Volume 60, Number 34, 2015
Theoretical and Mathematical Physics
Electrostatic SelfEnergy of a Charged Particle in the Surroundings of a Topologically Charged Black Hole in the Brane Alexis Larrañaga, Alejandro CardenasAvendaño, Daniel Alexdy Torres Romanian Journal of Physics 60,
271280 (2015)
We determine the selfenergy for a point charge held stationary in a topologically charged black hole spacetime arising from the RandallSundrum II braneworld model, showing that it has two contributions, one of geometric origin and the other of topological one.
On Using Third and Fourth Kinds Chebyshev Operational Matrices for Solving LaneEmden Type Equations E.H. Doha, W.M. AbdElhameed, M.A. Bassuony Romanian Journal of Physics 60,
281292 (2015)
This paper is concerned with deriving two new operational matrices of derivatives for Chebyshev polynomials of third and fourth kinds. As an important application of these introduced operational matrices, a certain class of linear and nonlinear LaneEmden type singular initial value problems (IVPs) are treated. Two numerical algorithms are described in detail for solving such kinds of problems. The idea of obtaining our algorithms is essentially based on converting the differential equation with its initial conditions to a system of linear or nonlinear algebraic equations. Numerical examples concern some relevant physical problems are included to demonstrate the validity and applicability of the proposed algorithms. In addition, some comparisons with some other methods are made.
Integration of ComplexValued KleinGordon Equation in Φ4 Field Theory M. Mirzazadeh, M. Eslami, A. H. Bhrawy, Anjan Biswas Romanian Journal of Physics 60,
293310 (2015)
This paper studies complexvalued KleinGordon equation that arises in Φ4 field theory. Three integration tools are availed of in order to obtain soliton and other solutions to the governing equation that is considered with cubic and power law nonlinearity. The three algorithms that are studied in this paper are G'/Gexpansion scheme, Kudryashov’s method, and the sinecosine approach. The corresponding constraint conditions of the solutions are also given. These three distinct integration mechanisms lead to several solutions of the equation that will be of great asset in the physics of the problem.
Analytic Solution and Simulation of the MassSpring and DamperSpring Systems Described by Fractional Differential Equations J.F. GomezAguilar Romanian Journal of Physics 60,
311323 (2015)
In this paper the fractional massspring and damperspring models with Caputo derivative is considered. The order of the derivatives is $0 < \gamma \le 1$. In order that the equations preserve the physical units of the system an auxiliary parameter $\alpha$ is introduced. Different source terms are introduced in the fractional equation. The classic cases are recovered when $\gamma = 1$.
Controllable Dynamical Behaviors and the Analysis of Fractal Burgers Hierarchy with the Full Effects of Inhomogeneities of Media H.J. Jaradat, F. Awawdeh, S. AlShara, M. Alquran, S. Momani Romanian Journal of Physics 60,
324343 (2015)
The aim of this work is three fold. First, via a fractional complex transformation and a simplified bilinear method, Nshockwave solutions for the variablecoefficient fractal Burgers equations are obtained, with their relevant properties and features being illustrated. The explicit functions describing the evolution of the amplitude, phase, and velocity are also given. Second, through the characteristicline method and graphical analysis we discuss the solitonic propagation and collision, including the bidirectional solitons and elastic interactions. Finally, a new approach to control the effects of inhomogeneities of media and nonuniformities of boundaries on the soliton behavior is suggested.
A Novel Spectral Approximation for the TwoDimensional Fractional SubDiffusion Problems A.H. Bhrawy, M.A. Zaky, D. Baleanu, M.A. Abdelkawy Romanian Journal of Physics 60,
344359 (2015)
This paper reports a new numerical method that enables easy and convenient discretization of a twodimensional subdiffusion equation with fractional derivatives of any order. The suggested method is based on Jacobi tau spectral procedure together with the Jacobi operational matrix for fractional derivatives, described in the Caputo sense. Such approach has the advantage of reducing the problem to the solution of a system of algebraic equations, which may then be solved by any standard numerical technique. The validity and effectiveness of the method are demonstrated by solving two numerical examples, which are presented in the form of tables and graphs to make more easier comparisons with the exact solutions and the results obtained by other methods.
Solving Nonlinear Fractional Differential Equations Using $\exp$Function and $G'/G$Expansion Methods Ahmet Bekir, Özkan Güner, Ali H. Bhrawy, Anjan Biswas Romanian Journal of Physics 60,
360378 (2015)
This paper presents an approach for solving fractional differential equations by employing the $\exp$function method and $\left(\tfrac{G'}{G}\right)$expansion method. These methods were applied in two examples to solve nonlinear fractional differential equations. The fractional derivatives are described in the modified Riemann–Liouville sense. As a result, many exact analytical solutions are obtained including hyperbolic function solutions and trigonometric function solutions. The results also show that the methods are very effective and convenient for solving nonlinear partial differential equations of fractional order.
Cnoidal Solutions, Shock Waves, and Solitary Wave Solutions of the Improved Kortewegde Vries Equation P. Sanchez Romanian Journal of Physics 60,
379400 (2015)
In this paper we obtain families of exact solutions of the improved Kortewegde Vries equation with power law nonlinearity. Three integration schemes are applied. They are the travelling wave hypothesis, the ansatz approach, and the semiinverse variational principle. With the help of soliton perturbation theory, the adiabatic dynamics of soliton parameters was also obtained.
A Numerical Study of the Perturbation of a Gradient Temperature Field for Arbitrary Proximity between Two Spheres Using Legendre Spectral Method A. Chowdhury Romanian Journal of Physics 60,
401414 (2015)
The temperature distribution around two spheres is considered when the main field has a constant gradient at infinity. The beneficial effects of introducing an approach involving bispherical coordinates over other wellknown methods in the literature are interrogated thoroughly. Together with a transformation of the dependent variable which leads to separation of variables, this method allows the solution to be sought in Legendre series. The method is validated to have an exponential convergence and proved to be highly efficient in obtaining any desirable level of accuracy with a reasonable number of terms, even for a difficult case of two almosttouching spheres. Solutions with both longitudinal and transverse gradients at infinity are obtained, and the contour lines of the temperature field are presented graphically. The pattern of the temperature field is thoroughly investigated in the region between the spheres when the distance between them is much smaller than their radii.
Elementary Particle Physics
RIVET Plugin for $Z^0 \to e^+ e^$ Production CrossSection Measurement in pp Collisions at $\sqrt{s} = 7$ TeV Ana Elena Dumitriu, A.T. Grecu Romanian Journal of Physics 60,
415428 (2015)
The Robust Independent Validation of Experiment and Theory (RIVET) project is an efficient and portable tool kit in form of a C++ class library enabling validation and tuning of Monte Carlo (MC) event generator models in elementary particle physics and astrophysics. It provides a large collection of standard experimental analyses useful for MC generator development, validation, tuning and regression testing proposing a new way by which analysis code from the LHC and other highenergy collider experiments is preserved for comparison and development of future theory models. The RIVET plugin developed for the LHCb measurement of Z0 → e+ e− production crosssection in pp collisions at 7 TeV centerofmass energy [1] is presented. The cross section was measured to be $$ \sigma(pp \to Z^0 \to e^+ e^) = 76.0 \pm 0.8(\text{stat}) \pm 2.0(\text{syst}) \pm 2.6(\text{lumi}) \pm 0.4(\text{FSR}) \text{ pb}. $$ Its single differential distributions are given as function of $Z^0$ rapidity and an angular variable which is closely related to $Z^0$ transverse momentum. The RIVET plugin results obtained with Pythia 8 for a few selected PDFs compare well to the LHCb data and the FEWZ predictions for nexttonexttoleadingorder (NNLO) PDFs.
[1] R. Aaij et al. (LHCb Collab.), J. High Energy Phys. 02, 106 (2013).
Nuclear and Atomic Physics
Skyrme Interaction with VMC Calculations of Nuclear Matter K. Manisa, M. Erdoğan, S. Bostan Romanian Journal of Physics 60,
429443 (2015)
The parameters of effective Skyrme interaction are determined by using Variational Monte Carlo (VMC) calculations that accurately reproduce the properties of symmetric and asymmetric nuclear matter. The realistic Urbana V_{14} nucleon–nucleon interaction potential of Lagaris and Pandharipande was used in the VMC calculations with addition of a phenomenological densitydependent term to simulate manybody interactions. A new Skyrme parameter set SKaan5 is found to consistently reproduce the characteristics of the nuclear matter obtained from VMC calculations. The properties of symmetric and asymmetric nuclear matter are calculated by the new Skyrme parameter set. It is shown that the new Skyrme parameter set SKaan5 satisfy the properties of symmetric nuclear matter, such the binding energy, saturation density and incompressibility. Also, the results obtained by using the new Skyrme parameter set are in good agreement with those obtained by other different Skyrme parameter sets in the literature.
Alphadecay and Spontaneous Fission Halflives of Superheavy Nuclei around the Double Magic Nucleus $^{270}$Hs I. Silisteanu, C.I. Anghel Romanian Journal of Physics 60,
444451 (2015)
The αdecay and spontaneous fission (SF) halflives of nuclei around ^{270}Hs are calculated with formulas derived from the systematics of data and theoretical results. The coefficients of the systematics result from the fit of halflives in respect with the reaction energies Q_{α} , the height of the SF barrier B_{f} and the fissionability Z^{2}/A . The calculated partial and total halflives are compared with the data and the results of other approximations. Halflife predictions are made for many unknown nuclei.
Some Applications of MicroPIXE in the Study of Ancient Bronze, Silver and Obsidian Artifacts Daniela CristeaStan, B. Constantinescu, D. Ceccato Romanian Journal of Physics 60,
452465 (2015)
The importance of microPIXE analyses on archaeological artifacts is demonstrated for bronzecopper, silver and obsidian items. The knowledge of the elemental composition and the determination of trace elements are useful to determine the provenance of raw materials. MicroPIXE studies also give information on metallurgical procedures and about corrosion status of artifacts. All this information helps archaeologists to authenticate and understand the provenance of such items – mines, metal production workshops, jewelry makers, commercial relations – and conservators to clean, restore and prevent corrosion of artifacts.
Condensed Matter
Electronic Edge States in Graphene Sheets OanaAncuta Dobrescu, M. Apostol Romanian Journal of Physics 60,
466480 (2015)
Electronic edge (“surface”) states are investigated in semiinfinite graphene sheets and graphene ribbons (monolayers) with armchair, zigzag or horseshoe edges within the nearestneighbour tightbinding approximation. The problem is generalized to include edge elements of the hopping (transfer) matrix which are distinct from the infinitesheet (“bulk”) ones. Within this model the semiinfinite graphene sheets with zigzag or horseshoe edges exhibit edge states, while the semiinfinite graphene sheet with armchair edge does not. The energy of the edge states derived here lies above the (zero) Fermi level. Similarly, symmetric graphene ribbons with zigzag or horseshoe edges have edges states, while ribbons with asymmetric edges (zigzag and horseshoe) have not. It is also shown how to construct the “reflected” solution for the intervening equations with finite differences both for semiinfinite sheets and ribbons, either with uniform matrix elements or with modified elements of the hopping matrix at the edges .
Combustion Synthesis and Photoluminescence Properties of Novel Eu^{3+} Ion Doped Magnesium Yttrium Borate Phosphor K.A. Koparkar, N.S. Bajaj, S.K. Omanwar Romanian Journal of Physics 60,
481487 (2015)
The novel MgY_{(2x)}B_{2}O_{7}:Eu^{3+} prepared by solution combustion synthesis. The asprepared samples were characterized by Xray diffraction (XRD), and scanning electron microscope (SEM) for structural and morphological studies. The complete agreement of XRD with standard ICDD data confirms the formation of required phase. The optical studies were carried out by photoluminescence (PL) spectroscopy. The PL spectra reveal that the red emission (^{5}D_{0}→^{7}F_{2}) was more intense than the orange emission (^{5}D_{0}→^{7}F_{1}). The CIE chromaticity colour coordinates were calculated.
Deposition of Titanium Dioxide Layers Upon Polyester Textile Materials: Checking the Adherence by UltraSonication Irina Zgura, Stefan Frunza, Monica Enculescu, Camelia Florica, Florin Cotorobai Romanian Journal of Physics 60,
488494 (2015)
An important parameter of deposited thin films is their adhesion to the substrate materials. we focused on the adhesion of TiO_{2} layer by solgel or sputtering onto textile substrate as checked by an ultrasonication method. The characterization made prior and after the tests have shown a good adherence of the nanoparticles, despite the low deposition temperature.
Synthesis and Characterization of La_{3}Ga_{5.5}Ta_{0.5}O_{14} Doped with Holmium and Ytterbium A.M. Voiculescu, S. Georgescu, C. Matei, A. Stefan, O. Toma Romanian Journal of Physics 60,
495501 (2015)
Ceramic langatate (La_{3}Ga_{5.5}Ta_{0.5}O_{14}) doped with holmium and ytterbium (1 at% and 3 at%, respectively) – LGT:Yb:Ho – was synthesized by solidstate reaction. The phase purity of LGT:Yb:Ho was analyzed by X ray diffraction. The sample was characterized by optical spectroscopy (absorption and luminescence). Green (^{5}S_{2}+^{5}F_{4} → ^{5}I_{8}) and red (^{5}F_{5} → ^{5}I_{8}) upconversion luminescence was obtained for the first time in ceramic LGT:Yb:Ho.
Design and Analysis of a Rayleigh Saw Resonator for Gas Detecting Applications V. Ionescu Romanian Journal of Physics 60,
502511 (2015)
Polymer coated gasphase sensors using the classical Rayleightype surface acoustic wave (RSAW) mode showed higher sensitivity and larger dynamic range compared to bulk acoustic wave (BAW) sensors, being widely used in a variety of sensor systems for chemical and biological gas detection. Using Comsol Multiphysics software, we investigated a 2D finite element model of a Surface Acoustic Wave (SAW) gas sensor, which consists of an interdigitated transducer (IDT) etched onto a piezoelectric LiNbO_{3} substrate and covered with a thin Poly Isobutylene (PIB) film. We selected for this study a sensor with two IDT structure types: bidirectional and single phase unidirectional transducer and we computed the deformed shape plot of the resonance and antiresonance SAW mode. The variation of electrical potential and total displacement as a function of structure depth (y coordinate) was also obtained. The sensor's sensitivity was evaluated by exposing the PIB film to various CH_{2}Cl_{2} (Dichloromethane) concentrations.
NMR and SEM Investigation of Extruded Native Corn Starch with Plasticizers N. Cioica, R. Fechete, C. Filip, I.B. Cozar , C. Cota, E.M. Nagy Romanian Journal of Physics 60,
512520 (2015)
The biodegradable packing of native corn starch samples with different ratios of glycerol and water were prepared. Their crystalline/amorphous changes, after extrusion process, were investigated by NMR (relaxation, ^{13}C CP/MAS) and SEM methods. The composition having starch/glycerol/water 68/17/15 mass % ratio was found to have a dominant amorphous character and very similar features as a commercial specimen used for the package.
Medical Physics
In Vivo Study of BPA (boron^{10}phenilalanine) Use in Boron Neutron Capture Radiotherapy as an Alternative for Hepatic Cancer Treatment Laurentia Gales, Rodica Anghel, Maria Iuliana Gruia, Valeria Lungu, Valentina Negoita, Ion Gruia Romanian Journal of Physics 60,
521527 (2015)
Since the response at conventional chemo and radiotherapy treatment of hepatocellular carcinoma is extremely reduced, the research of the specialists from this domain were oriented to find new alternative therapies to assure a better response to the treatment of primary or metastatic liver tumors. The neutron capture by Boron10 radiotherapy is a therapeutic method being in the pioneer’s work stage especially in Europe, but with promising results, especially in brain tumor so far. The ^{10}Boron neutrons capture are producing alpha energetic particles, with a high linear energetic transfer at tissue level. Consequently it obtains higher cell destruction and greater biological relative efficiency than in the case of photons. Using adequate Boron compounds, preferentially localized in tumor cells and not in the healthy tissue, the Boron neutrons capture therapy gives a higher curative potential with lower toxicity in normal tissues. The aim of our study is to establish one in vivo experimental model which offer results that can be extrapolate at clinical level, because in our country this therapy was not approached yet. The first step was to establish the Boron10 carrier compound and it’s characteristics and also the characterization of its administration at tumor bearing rats. We investigate the solubility; the administration and the even toxicity induced by borphenilalanine.
Standardless XRay Fluorescence Analysis of Endodontic Sealers Using a Portable Spectrometer Ioana Suciu, Elena S. Preoteasa, E. A. Preoteasa, Catalina Chiojdeanu, B. Constantinescu, B. Dimitriu, Paula Perlea, Al. A. Iliescu, Dana Bodnar Romanian Journal of Physics 60,
528548 (2015)
We report a preliminary study on three types of endodontic sealer products carried out by thick target Xray fluorescence (XRF) using a portable spectrometer. The aim of this study was to assess the potential of this method for the analysis of biomaterials used in the root canal dentistry. The main difficulty of this study was the lack of reference materials. Therefore semiquantitative analysis was performed, and relative concentrations of elements were determined from the XRF spectra with a mean accuracy of about 42% using a dedicated software. To overcome the contributions of matrix effects inherent in thick target analysis, we applied various approximate corrections. All the three formulations contained a major heavy metal like W and Bi for radioopacity. Two similar products contained both Bi as major element, but they could be differentiated by their minor elements, i.e. Ca and Ba in only one of them. Another minor element was Zr, and trace elements were detected in the three materials – Fe and possibly Cu – probably impurities from raw materials of different origin. All three endodontic sealers could be recognized unequivocally by brands based on the XRF analysis, a result of potential interest for forensic applications. Improved quantitative XRF analysis of these and similar materials may bring compositional insight relevant for biocompatibility studies of these materials and for further developments in endodontic research.
Plasma Physics
Performances of an Argon ArcJet Thruster for Satellites A. Kaminska, A. Bialek, M. Dudeck Romanian Journal of Physics 60,
549559 (2015)
Arcjet thrusters are currently used for the propulsion of satellites. Low power arcjet are functioning with propellant as helium, hydrogen, ammonia, lithium and argon. The performances such as axial thrust and specific impulse of a D.C. argon arc–jet are calculated by a fluid description of the arc with two kinetic temperatures (T_{e},T) and non equilibrium condition for the ionization. The electric input power is calculated from the conductivity which is deduced from plasma properties. The influence of different angles of the nozzle divergent part, arc current and mass flow rates on arcjet performances is discussed. It is shown that the thrust is 0.32.5 N and the specific impulse 80210 s for an argon mass flow rate 0.41.2 g/s and a arc current of 40120 A.
Preparation and Analysis of Functional Fusion Related Materials M. Lungu, I. Tiseanu, I. Jepu, C. Porosnicu Romanian Journal of Physics 60,
560572 (2015)
A high interest developed over time in the fusion nuclear energy field during the last years, especially in producing functional materials that could withstand high temperatures and nuclear irradiations. Analyses upon the fusion reactor walls were performed sequentially, on specific areas of interest, studying the erosion patterns developed over time, caused by the fusion plasma. In this paper we report studies of erosion/deposition on the marker tiles used in the JET reactor working with Be and W coated tiles. Xray microbeam fluorescence (µXRF) and highenergy (W Klevel) Xray fluorescence (HEXRF) were employed as noninvasive solutions to quantify erosion/deposition studies of W and Ni coatings on CFC and Be. The XRF technique requires calibration samples with known thicknesses and compositions. Thermionic vacuum arc (TVA) method is used to obtain thin layers of W/Ni as calibration samples that simulate the redeposition of the ITER relevant mixed layers onto the Be/CFC first wall components. Relatively thick W layers were produced with the combined magnetron sputtering and ion implantation method and used for the Xray fluorescence analysis of the JET W coated tiles. Thus calibration curves for a thickness range from 10 nm to > 30 µm were generated. Results for a total of 20 JET W coated CFC samples are presented.
Environmental Physics
On Modeling the Groundwater Flow within a Confined Aquifer Abdon Atangana, Dumitru Baleanu Romanian Journal of Physics 60,
573582 (2015)
The groundwater flow equation is used to simulate the movement of water under the confined aquifer. In this paper we study a modification of the groundwater flow equation within a newly proposed derivative. We numerically solve the generalized groundwater flow equation with the CrankNicholson scheme. We also analytically solve the generalized equation via the method of separation of variable.
Assessment of Pesticides Interactions with Bacillus Pasteurii Urease. A Computational Study D.L. Vlădoiu, M.N. Filimon, V. Ostafe, A. Isvoran Romanian Journal of Physics 60,
583592 (2015)
Two herbicides (chlorsulfuron and nicosulfuron) and one fungicide (difenoconazole) are considered in this work and molecular docking studies have been implemented to evaluate their interactions with Bacillus pasteurii urease, a soil microorganism enzyme using a bimetallic nickel active center. Structural characterization of herbicides and fungicide is also performed by comparison to urea and known inhibitors of urease and taking into account the protein surface description. The two herbicides, chlorsulfuron and nicosulfuron, and the fungicide difenoconazole have higher dimensions than urea and known inhibitors of Bacillus pasteurii urease. Both herbicides and the fungicide are evaluated to strongly interact to Bacillus pasteurii urease, the most favorable interaction being predicted for chlorsulfuron. Moreover, all the pesticide molecules provide the capacity to bind to urease in several places to the enzyme surface, but only chlorsulfuron is proficient to bind to the catalytic site. It may be explained by the fact that chlorsulfuron contains a charged region that is assumed to interact electrostatically with the active site of the enzyme, the known inhibitors also exhibiting such a region.
Estimation of Global Solar Irradiation by Using TakagiSugeno Fuzzy Systems R. Boata, N. Pop Romanian Journal of Physics 60,
593602 (2015)
Artificial intelligence, as an alternative to the conventional statistical methods, has the ability to track complicated dependencies between different variables, where traditional methods have their limits. The fuzzy sets theory replaces the classical bivalent logic with a multivalued logic. In this paper is developed a new model for estimation of daily global solar irradiation using TakagiSugeno fuzzy algorithms. Model construction procedure is presented in detail and a comparison with other models from literature is carried out. A critical assessment of the model performance is presented. Even if the model was built with data measured from the meteorological station of Timisoara, its application can be extended to other locations with similar meteorological regime. This conclusion is supported by the results obtained from testing the model in several locations.
Inhibitory Effects of Low Thermal Radiofrequency Radiation on Physiological Parameters of Zea Mays Seedlings Growth M. Racuciu, C. Iftode, S. Miclaus Romanian Journal of Physics 60,
603612 (2015)
12days old plantlets developed from Zea mays seeds exposed at 1 GHz inside a transverse electromagnetic cell for different exposure durations, at a specific absorption rate of energy deposition of 0.47 W/kg, showed decreased levels of photoassimilatory pigments and nucleic acid contents, than controls. Longer exposure duration inhibited the plantlets’ growth.
How Long Time Will We Go with Linear Seismology? Gheorghe Marmureanu, Carmen Ortanza Cioflan, Alexandru Marmureanu, Constantin Ionescu Romanian Journal of Physics 60,
613625 (2015)
The response of any physical system is nonlinear unless the magnitude of the input is very small. The M_{W} magnitudes of deep Vrancea earthquakes are between 0.02 and 7.9. The leading question is: how many cities, villages, metropolitan areas etc. in seismic regions are constructed on rock sites? Most of them are located on alluvial deposits, on Quaternary layers or in river valleys. A soil is of basic type sand or gravel (termed coarse soils), silt or clay (termed fine soils) etc. Strong ground accelerations from large and deep Vrancea earthquakes can produce a nonlinear response in shallow soils and the shaking from large earthquakes cannot be predicted by simple scaling of records from small earthquakes [12]. The question: is that real and how much? Laboratory tests indicate that as the strain increases above 10^{4} %, damping (absorption) increases and the shear modulus (rigidity) decreases. This should results in two observable effects as the level of ground motion at a soil site increases; a decrease in amplification due to the increase in damping and a lowering of the site response frequency as the shear modulus decreases. The novelty and the complexity degree comes from the fact that for first time, the final decision for NPP Cernavoda site, in 2012, was also based on local strong nonlinear spectral amplifications for strong earthquakes and used in last „STRESS TEST” asked by IAEA Vienna in 2011. The present analysis indicates that the effects of soil nonlinearity could be very important in seismology, in seismic hazard analyses and earthquake engineering. The authors are coming with many recorded data which will open up a new challenge for seismologists studying nonlinear site effects in 2D and 3D irregular geological structures, leading them to a realistic research subject in earth physics, in nonlinear seismology [1]. [1] A. Aki, Tectonophysics, 218, p. 93111 (1993). [12] P.M. Shearer, Introduction to Seismology, Second Edition, Cambridge University Press (2009).
Econophysics
CoherenceBased Method to Detect Time Shifts Smaller than the Sampling Rate of Time Series Eugen I. Scarlat Romanian Journal of Physics 60,
626641 (2015)
The paper presents a method to evaluating the average time shift between two time series by exploiting both components of the complexvalued cross coherence function: the magnitude and the relative phase. What is new is there are detected temporal shifts smaller than the sampling interval of the series which could be useful to the timing of macroeconomic indicators according to process evolution, not to the calendar day of publication. Depending on the key quantities grouped in the descriptor the method is able to detect time gaps as small as one tenth of the sampling rate. The method applies on non stationary series that are lacking long run correlations. In the paper is presented the theoretical justification of the technique, the calibration procedure, a validation test using aggregate replicas as well as how the technique could be applied onto the series of exchange rates, aggregate index BET of the Bucharest stock exchange market, and macroeconomic indicators. When used to ordering the series inside groups of coherent clusters, the results should be cautiously concatenated to establishing the relative time succession among more than two series.
