Arhivă — Seria A

1

EUCLIDEAN GEOMETRY OF FINSLER WAVEFRONTS THROUGH GAUSSIAN CURVATURE

Vladimir BALAN, Mircea CRASMAREANU

The present paper deals with the Gaussian curvature K of a particular indicatrix in a general Finsler manifold. A formula for K similar to the one obtained by M. Hashiguchi ([2], [3]), is derived for (, )-metrics and then specialized to Randers, Kropina, Matsumoto and Riemann-type metrics. For the Funk two-dimensiona…

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2

SUFFICIENT EFFICIENCY CONDITIONS FOR A MINIMIZING FRACTIONAL PROGRAM

Ariana Pitea, Constantin Udriste

We consider the minimizing fractional program (MFP), where the objective is a vector of functionals quotients of paths integrals and the constraints are partial diferential inequations (PDI) and partial diferential equations (PDE). The aim of this work is to introduce and study sufcient conditions for the eficiency of …

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3

A PROPERTY OF LOGARITHMICALLY ABSOLUTELY MONOTONIC FUNCTIONS AND THE LOGARITHMICALLY COMPLETE MONOTONICITY OF A POWER-EXPONENTIAL FUNCTION

Bai-Ni Guo, Feng Qi

In this work, the notion of a” logarithmically absolutely monotonic function\\\\\\\" is introduced, the inclusion that a logarithmically absolutely monotonic function is also absolutely monotonic is revealed, the logarithmically complete monotonicity and the logarithmically absolute monotonicity of the function (1+α/x)…

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4

QUASI-ANALYTIC SOLUTIONS OF FIRST-ORDER PARTIAL DIFFERENTIAL EQUATIONS USING THE ACCURATE ELEMENT METHOD

Maty BLUMENFELD

It is usually considered that a PDE can have on a two-dimensional integration domain either an analytic solution (x,t) (which replaced in the PDE leads to an identity) or a numeric solution (represented by a string of numerical values whose accuracy is more difficult to quantify). The integration of a PDE by the Accur…

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5

HYSTERESIS MODELING WITH PRANDTL-ISHLINSKII OPERATORS FOR LINEARIZATION OF A (BA/SR)TIO3 BASED ACTUATOR

Andreea Ioana UDREA, Alexandru COSTINOAIA, Ciprian LUPU, Dumitru POPESCU

The paper presents an experimental study on (Ba,Sr)TiO3 based actuators hysteretic comportment. The purpose of the study is to model the nonlinearity introduced by the actuator in a positioning system. The classic and modified Prandtl – Ishlinskii technique is used such that the numerical control of the positioning sy…

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6

ON THE LAGRANGE COMPLEX INTERPOLATION

Adrian NEAGOE

In this work, I present some results regarding the Lagrange interpolation in the complex domain (cor. prop. 1 and prop. 2). Formula (6) is an extension of the well-known Shannon’s sampling formula (7) , for sampling equidistant moments. In §2 I present a simple result regarding the sampling in frequency. In §3 I give a…

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7

A METHOD TO COMPARE TWO COMPLEXITY FUNCTIONS USING COMPLEXITY CLASSES

Andrei-Horia MOGOS, Adina Magda FLOREA

The complexity of an algorithm can be expressed as a function, called complexity function. In this paper we study the comparison of two complexity functions using complexity classes. After defining the set of all complexity functions comparable with a given function, we give some properties of this set. The most import…

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8

HOMOGENIZATION RESULTS FOR A NONLINEAR WAVE EQUATION IN A PERFORATED DOMAIN

Claudia TIMOFTE

The effective behavior of the solution of a nonlinear wave equation in a periodic perforated domain is analyzed. We consider, at the microscale, a wave equation, with nonlinear sources and suitable initial and boundary conditions. We focus on the case in which the perforations are of the so-called critical size and we …

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9

SPECTRAL METHOD FOR SOLVING THE DIFFERENTIAL EQUATIONS INVOLVED IN AB-INITIO TREATMENT OF TUNNEL TRANSISTORS STRUCTURES

Sever SPANULESCU

A new variant of the spectral method for solving the boundary conditions ordinary differential equations, suited to the ab-initio tunneling calculus is presented. By expanding the total potential expression in a series in a Hilbert space, the linear equations derived with the collocation method may admit an initial ana…

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10

MULTIPLE -HYBRID LAPLACE TRANSFORMATION AND APPLICATIONS TO MULTIDIMENSIONAL HYBRID SYSTEMS. PART I

Valeriu PREPELIÞÃ

A space of original functions which are continuous with respect to n variables and discrete with respect to m variables is presented. A multiple hybrid Laplace and z type transformation is defined on this set. Its main properties are studied, including linearity, time-delay, translation, differentiation and difference …

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11

ARC DISCHARGE ION SOURCE DEVELOPMENT AT CERN ISOLDE

Liviu PENESCU,, Thierry STORA, Jacques LETTRY, Gheorghe CATA-DANIL, Richard CATHERALL

Within a Marie Curie Early Stage Training project at CERN, a detailed study (experimental, analytical and numerical) of the standard ISOLDE FEBIAD ion sources has been done. A new theoretical model of the global source behavior could be inferred, based on the acquired experimental data. The source model already served …

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12

EVALUATION OF BIOCOMPATIBILITY AND BIOACTIVITY FOR POLYMETHYL METHACRYLATE – BIOACTIVE GLASS NANOCOMPOSITE FILMS OBTAINED BYMATRIX ASSISTED PULS

Laura FLOROIAN, Ion MIHAILESCU, Felix SIMA, Gheorghe STANCIU, Bogdan SAVU

We evaluated the scrach resistance, adherence and hardness for novel polymethyl methacrylat-bioglass (PMMA+BG) composites deposited by matrix assisted pulsed laser evaporation technique on medical titanium substrate, for applications in implantology. The bioactivity of the films was assessed in vitro by soaking the com…

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13

OIL SPILLS DETECTION FROM FLUORESCENCE LIDAR MEASUREMENTS

Jeni VASILESCU, Luminita MARMUREANU, Emil CARSTEA, Constantin P. CRISTESCU

Fluorescence LIDAR is a useful tool in water pollution monitoring, based on the fluorescence signature of each contaminant. The main goal of this study is to analyze the oil spills detected in late 2007 summer campaign on the Romanian side of Black Sea. Artificial neural network (ANN), linear regression and channels re…

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14

THE MO-SCF QUANTUM APPROACH OF THE 4-BUTYL-OXY-BENZAL-4 ETHYL-ANILINE (BBEA) MOLECULE. (I) QUANTUM ENERGETIC MOLECULAR CHARACTERISTICS

Valer SCRIDONESI-CÃLIN

The liquid crystal (LC) molecule of the smectic type (SLC) 4-butyl-oxy-benzal-4-ethyl-aniline (BBEA) is approached by means of the nonrelativistic molecular quantum mechanics for the first time in literature of the liquid crystals (LC). The BBEA molecule/C19H23ON [44 nuclei, 152 electrons (110 of valence)] from its str…

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15

LASER FIELD EFFECT ON THE ANOMALOUS POLARIZATION IN SQUARE QUANTUM WELL UNDER HYDROSTATIC PRESSURE

Ecaterina C. NICULESCU, Iulia G. CÂRJEU, Radu C. IONESCU

The polarization of the carriers in an electric field in GaAs/AlGaAs quantum well under the simultaneous action of the high-frequency laser filed and the hydrostatic pressure is investigated. The results show that the anomalous polarization of the first excited level is partially compensated by the presence of the lase…

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16

SURVEY OF HEAVY METAL DEPOSITION IN ROMANIA: TRANSYLVANIAN PLATEAU AND WESTERN CARPATHIANS MOUNTAINS

Adriana LUCACIU, Cornelia MOÞOC, Marian JELEA, Stela Gabriela JELEA

This study is connected to an earlier survey of atmospheric heavy metal deposition started in 1995, for the first time, in Romania. In this paper the results obtained after collecting in 1999 and 2007 (during the summer) 64 moss samples from highly polluted area of some regions of Romania are reported. The aim of this …

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17

CHAOTIC BEHAVIOR OF IDEAL FOUR-LEVEL LASER WITH PERIODIC PUMP MODULATION: II

Mihai CIOBANU, Dan SAVASTRU, S. MICLOS, Marina TAUTAN, Madalin RUSU, Simona DONTU

A predictability investigation using the Grassberger-Proccaccia algorithm is performed for the ideal four - level laser in the case of periodic pump term, continuing a previous research. In addition, maximum Lyapunov exponents are calculated, and chaos is evidenced at the same threshold value of pump frequency by two w…

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18

PIEZOCERAMICS UNDER ELECTRON IRRADIATION

Irinela CHILIBON

Paper presents aspects concerning the behaviour of PZT piezoceramics at low power electron irradiation. The PZT samples were irradiated into a linear accelerator of electrons with different electron doses, namely: 10 kGy; 15 kGy; 20 kGy; 25 kGy. These ceramics change slightly their performances after low power electron…

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19

INFORMING SCIENCE AS CONCEPTUAL FRAMEWORK FOR DEVELOPING INFORMATION SYSTEMS

Radu DOBRESCU

The extensive use of the Information Systems (IS), whose meaning has been growing in diversity and complexity, lead to considerate a new conceptual framework for their development, defined as Informing Science (InfoS). The paper examines the limitations of existing frameworks for defining IS and introduces a new evolut…

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