H.-D. Heike, C. Târcolea, Adina I. Tarcolea, M. Demetrescu. Fiducial ... E. I.
Scarlat, C. P. Cristescu, Cristina Stan, A. Preda, Mona Mihailescu, Liliana. Preda.
U.P.B. Sci. Bull., Series A, Vol. 69, No. 1, 2007
ISSN 1223-7027
Contents
MATHEMATICS H.-D. Heike, C. Târcolea, Adina I. Tarcolea, M. Demetrescu Fiducial inference: an approach based on bootstrap techniques
3
M. Cîrnu Solving difference and differential equations by discrete deconvolution
13
Elena Corina Cipu, Carmen Dragnea Life tables for romaniasurvival function.life expectancy for romanian people
27
Alina Nita, Ana Nita On the bilinear dynamical systems
37
PHYSICS E. I. Scarlat, C. P. Cristescu, Cristina Stan, A. Preda, Mona Mihailescu, Liliana Preda Econophysics approach to the dynamics of the romanian exchange rate ROL-USD
43
Camelia Talianu, Anca Nemuc, Doina Nicolae, C.P Cristescu Dust event detection from LIDAR measurements
57
Elena Dugheanu Calibration procedure for stabilized lasers using the method of optical beats measurement uncertainty
67
E. Burzo, Ileana Creanga Crystal structure and magnetic properties of rhombohedral Y-Co- Ni compounds
71
U.P.B. Sci. Bull., Series A, Vol. 69, No. 1, 2007
ISSN 1223-7027
FIDUCIAL INFERENCE: AN APPROACH BASED ON BOOTSTRAP TECHNIQUES H.-D. HEIKE, C-tin TÂRCOLEA, A dina I. TARCOLEA, M. DEMETRESCU The basic concepts of fiducial inference are presented in the first part of this paper. Problems arise if the form of the distribution of the pivot used by the fiducial argument is not known. Our main result consists in showing how bootstrap techniques can be used to handle this kind of situ ation. Keywords : Fiducial distribution, estimation of parameters, pivotal methods, approximation of distributions, approximate pivot. AMS 2000 Classification: 62F99
SOLVING DIFFERENCE A ND DIFFERENTIAL EQUATIONS BY DISCRETE DECONVOLUTION M. I CÎRNU We present the way in which, using the discrete convolution and deconvolution, can be computed the numerical values of the solutions both of the initial and boundary value problems for linear nonhomogeneous difference and differential equations with constant coefficients. Worked examples are included. The method can be easily used in applications and implemented on a computer. Keywords: difference and differential equations, discrete convolution and deconvolution. 2000 Mathematics Subject Classification: 40-04, 40A05
U.P.B. Sci. Bull., Series A, Vol. 69, No. 1, 2007
ISSN 1223-7027
LIFE TABLES FOR ROMANIA SURVIVAL FUNCTION.LIFE EXPECTANCY FOR ROMANIAN PEOPLE Elena Corina CIPU, Carmen DRAGNEA A calculation procedure of abridged life table was obtained using the mortality data from year 2002. Using graphical and analytical methods, based on the life table, it was obtained an estimation of the survival function. Keywords : life tables, survival function. Mathematics Subject Classification 2000: 62N01,62N02
ON THE BILINEAR DYNAMICAL SYSTEMS Alina NITA, Ana NITA In this paper one gives explicit approximative solutions of some classes of dynamical systems described in the equations (1) and (5) below. Their solutions are checked in some classes of functions which are constant on pieces, like the Walsh functions or the discrete exponentials; some practical tools of linear algebra (e.g. Kronecker tensor products, pseudosolutions, etc.) are systematically used.
Keywords : bilinear dynamical system, Walsh functions, matricial form, pseudoinverse of a matrix. 2000 Mathematics Subject Classification: 42C10
U.P.B. Sci. Bull., Series A, Vol. 69, No. 1, 2007
ISSN 1223-7027
ECONOPHYSICS APPROACH TO THE DYNAMICS OF THE ROMANIAN EXCHANGE RATE ROL-USD E. I. SCARLAT, C. P. CRISTESCU, Cristina STAN, A. PREDA, Mona MIHAILESCU, Liliana PREDA We found a definite fractal dimension of the temporal series describing the daily exchange rate of the Romanian “Leu” (ROL) with respect to the US Dollar (USD) over ten years, from the beginning of 1991 until a certain stabilization occurred (end of 2000); hereafter, we call this the transition period. Besides the statistical self-similarity, unlike other structures reported in the literature, we found repetitive cells that replicate the whole temporal pattern i.e. the evidence of a theoretical self-similarity . The fact that we were able to identify several scaling cells demonstrates the dominant monofractal behaviour of the dynamics during the period of strong depreciation of the national currency that characterizes the transition toward the open market economy. Keywords: self-similarity, fractal dimension, Hurst exponent, scaling cells
DUST EVENT DETECTION FROM LIDAR MEASUREMENTS Camelia TALIANU, Anca NEMUC, Doina NICOLAE, C.P CRISTESCU Active remote sensing systems such as Lidars (LIght Detection And Ranging) can detect clouds and aerosols. Use of aerosols as tracers for the Planetary Boundary Layer (PBL) allows the observation of its vertical profile and time evolution. Information on the vertical profile of meteorological parameters is essential for scientific investigations, climate modeling and for long time pollution monitoring. Another atmospheric event that can be identified by lidar measurements is the aerosol intrusion in the free troposphere. This
U.P.B. Sci. Bull., Series A, Vol. 69, No. 1, 2007
ISSN 1223-7027
paper studies a special case of aerosol intrusion determined during a campaign for PBL height characteristic of Bucharest atmosphere. Because we can not specify the aerosol type from elastic backscatter Lidar signal, a model data prognosis and air masses backward trajectories have been used to further investigate our experimental results. The lidar system at INOE, (LISA) is based on a Nd:YAG laser working at the 1064 nm fundamental wavelength and at 532 nm second harmonic and delivering pulses with high repetition rate. The system can detect micron size aerosols from long distances (up to 10 km), with a very good spatial resolution (3 m). Keywords Lidar, dust event, aerosols, retrieval algorithm
CALIBRATION PROCEDURE FOR STABILIZED LASERS USING THE METHOD OF OPTICAL BEATS MEASUREMENT UNCERTAINTY ELENA DUGHEANU The paper describes the calibration method used for the calibration of stabilized lasers by saturated absorption in molecular iodine 127I2 and the estimation of the uncertainty budget of the installation used for the comparison of two laser frequencies in Length Laboratory, National Institute of Metrology, Bucharest, Romania. The contribution of the author consists of the analyses of the sources of error which appear during the measurement, due to la ser and to the equipments that compound the installation, according to the specifications of “Guide to the expression of uncertainty in measurements, SR ENV 13005:2003” Key words: stabilized lasers, installation for calibration of stabilized lasers, uncertainty budget
U.P.B. Sci. Bull., Series A, Vol. 69, No. 1, 2007
ISSN 1223-7027
CRYSTAL STRUCTURE AND MAGNETIC PROPERTIES OF RHOMBOHEDRAL Y-CO-NI COMPOUNDS E. BURZO, Ileana CREANGA The Y2Co 7-xNix compounds with x = 3 crystallize in a rhombohedral type la ttice. The saturation magnetizations and Curie temperatures decrease rapidly when increasing nickel content. Above the Curie points, the reciprocal susceptibilities follow a Curie-Weiss type dependence. The magnetic behaviour of transition metals was analysed in spin fluctuation model.
