Florentin PaladiCLUSTER-BASED APPROACH TO THE

The non-stationary cluster size distribution in a network of agents which evolves without preferential behavior has been studied at early and late stages of clusters formation, when they are expected to grow and decay mainly by gaining and losing single agents. We developed a further model for the dynamics of an open system formed by time-dependent number of agents. Groups of agents (clusters) change their sizes by all possible transitions: addition/removal of agent(s) (monomers, dimers etc.) to/from the system, coagulation of two clusters of sizes r and k-r, where 1<r<k-1 (k>3), attachment of monomers, dimers, trimers etc. to clusters of size k or disappearance of a cluster of size k by coagulation with another cluster, and detachment of monomers, dimers, trimers etc. Both non-zero initial cluster size distribution and when only free agents (monomers) are present in the system at the initial moment have been studied, and we describe accordingly the effect of arbitrary pre-existing clusters on the time evolution of the interacting agents. PACS: 02.60.Cb; 05.40.−a; 89.65.G

On parametric representation of the Newton's aerodynamic problem

Newton's problem of finding the surface shape of a rotation body based on the condition of minimal resistance of the body when it moves in a rarefied medium is discussed. The problem is formulated in the form of a classical isoperimetric problem in calculus of variations. The exact solution is given in the class of piecewise differentiable functions. The numerical results of specific calculations of the functional for cone and hemisphere are presented. We prove that the optimization effect is significant by comparison of the results for cone and hemisphere with the value of the optimized functional for the optimal contour

Sensitivity analysis of the equilibrium states of multi-dimensional dynamical systems for ordinary and bifurcation parameter values

Dependences of the equilibrium states of multidimensional dynamical systems on the parameters of the dynamical system in a small neighborhood of their equilibrium values are investigated. Cases of ordinary and bifurcation values of parameters are considered. Asymptotic representations are derived for sensitivity formulae of the equilibrium values of parameters. Stability analysis of the equilibrium states for nonlinear complex systems described by the Landau-type kinetic potential with two order parameters and the Lotka–Volterra model is conducted. Two different rate processes as combinations of in series and in parallel pathways are examined

ALGORITMUL DE OBŢINERE A DEPLASĂRILOR SIMETRIZATE ÎN SISTEMELE SIMETRICE COMPLEXE PRIN REDUCEREA LA PROBLEMA VECTORILOR PROPRII

În articol este propus un algoritm modificat de obţinere a oscilaţiilor simetrizate în sistemele simetrice complexe. În teoria grupurilor anterior au fost dezvoltate metode de determinare a unor astfel de oscilaţii. Însă, aceste metode sunt dificil de algoritmizat pentru sistemele simetrice complexe care deţin multe grade de libertate. Algoritmul modificat propus este elaborat pentru a fi capabil să găsească deplasările simetrizate în astfel de sisteme şi, prin urmare, de a obţine şi clasifica oscilaţiile normale şi frecvenţele acestora. Metoda respectivă reduce această problemă la problema determinării vectorilor proprii, pentru care deja există metode numerice răspândite pe larg. ALGORITHM OF SYMMETRIZED SHIFTS DETERMINATION IN COMPLEX SYMMETRIC SYSTEMS VIA REDUCING TO THE EIGENVECTORS PROBLEMA modified algorithm of symmetrised oscillations determination of complex symmetric systems is developed in the article. Methods of determination of such oscillations in the group theory were developed earlier. These methods are difficult to be algorithmised for complex symmetric systems with a big amount of degrees of freedom. The modified algorithm was developed to be able to find symmetrised shifts of such systems and, consequently, to obtain and classify normal oscillations and their frequencies. This method reduces the problem to the problem of eigenvectors determination, to which it is applicable common numerical methods.</p

SISTEM INFORMATIC ADAPTIV „DETERMINAREA STĂRILOR PROPRII ALE MOLECULELOR DE FULLERENE”

În articol sunt studiate comportamentul şi proprietăţile fizice ale fullerenelor. Avantajul tehnologiilor informaţionale inteligente este de a construi automat programul de calcul din specificarea iniţială a problemei slab-structurate şi infor-maţiile de concretizare, furnizate de către beneficiarul problemei în cadrul dialogului cu SSD (parametrii necunoscuţi ai problemei, metoda de calcul, criteriile de optimizare etc.). SSD a fost folosit la cercetarea fullerenelor: C60, C70, C76, C82.ADAPTIVE INFORMATIC SYSTEM „DETERMINATION OF THE EIGENSTATES OF FULLERENE MOLECULES”In the present article the behavior and physical properties of fullerenes are studied. The advantage of intelligent information technologies is to build automatically computer program from the initial specification of a poorly-structured problem and the embodiment information provided by the recipient of the problem through a dialogue with DSS (unknown parameters of the problem, the method of calculation, optimization criteria etc.). DSS was used to research fullerene C60, C70, C76, C82.</p

Advanced computational method for studying molecular vibrations and spectra for symmetrical systems with many degrees of freedom, and its application to fullerene

A computational method for studying molecular vibrations and spectra for symmetrical systems with many degrees of freedom was developed. The algorithm allows overcoming difficulties on the automation of calculus related to the symmetry determination of such oscillations in complex systems with many degrees of freedom. One can find symmetrized displacements and, consequently, obtain and classify normal oscillations and their frequencies. The problem is therefore reduced to the determination of eigenvectors by common numerical methods, and the algorithm simplifies the procedure of symmetry determination for normal oscillations. The proposed method was applied to studying molecular vibrations and spectra of the fullerene molecule C60, and the comparison of theoretical results with experimental data is drawn. The computational method can be further extended to other problems of group theory in physics with applications in clusters and nanostructured materials

Airborne pollutants collection and analysis based on their fluorescence spectral measurements: a case study on diesel exhaust combustion particles

Abstract Collection of the airborne pollutants by using our prototyped device was followed by their analyses based on the performed fluorescence spectral measurements for three samples collected on the quartz substrates and on the surface of a silicon monocrystalline (opaque) wafer. Results for combustion particulate matter from diesel exhaust, including a comparison with air pollutants analysis for microparticles collected on a street in Chisinau city during rush hour, are presented. The strength of the proposed method represents the possibility to study directly the airborne solid microparticles collected on different substrates, and it is suitable for studying air pollution on large areas and at different altitudes by using unmanned aerial vehicles (UAVs). Microparticles fluorescence spectroscopy results indicate that the individual particles exhibit composite fluorescence spectra