Browsing by Author "Paladi, Florentin"

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ADAPTIVE APPLICATION FOR COMPLEX SYSTEMS MODELING
(CEP USM, 2017) Căpățână, Gheorghe; Ciobu, Victor; Paladi, Florentin
The paper presents a formal system for presentation and measurement of applications adaptability, and describes an original methodology for building adaptive applications from various fields of activity/research, including for computer modeling of complex systems in physics.
Advanced computational method for studying molecular vibrations and spectra for symmetrical systems with many degrees of freedom, and its application to fullerene [Articol]
(Springer Verlag, 2017) Bogush, Igor; Ciobu, Victor; Paladi, Florentin
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.
ALGORITMI DE SOLUȚIONARE A PROBLEMELOR NELINIARE DE TRANSPORT
(2021) Pașa, Tatiana; Ungureanu, Valeriu; Paladi, Florentin
Scopul lucrării: constă în soluționarea unui șir de probleme neliniare de transport de dimensiuni mari cu funcții concave de cost.
Algoritmul de obţinere a deplasărilor simetrizate în sistemele simetrice complexe prin reducerea la problema vectorilor proprii [Articol]
(CEP USM, 2015) Boguș, Igor; Ciobu, Victor; Paladi, Florentin
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 si stemele 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.
Analysis of phase transitions in the presence of an intermediate state. The model with two order parameters [Articol]
(Institutul de Fizică Aplicată, 2014) Gubceac, Ghennadii; Barsuk, A.A.; Paladi, Florentin
The main propose of this repo1t is to present the analysis of phase transitions in the presence of an intennediate state by using the model with two order parameters. The parametric modelling of phase transitions and analysis of the role of an inte1mediate liquid state in ineversible relaxation processes at low temperatures were perfonned. As an example, one can consider the systems with two stable states LI and C that means liquid and c1ystalline, respectively, and the third one - intennediate fluid state, namely L2 [1]. Such L2 state has been experimentally discovered in supercooled liquids [2]. The model includes two order parameters and three control parameters in the Landau-type kinetic general potential of 6th degree, and has been developed to study the impact of heterogeneity on phase transitions in the presence of an inte1mediate fluid state [3]. We noticed that the presence of the intennediate liquid state may indeed enhance the nucleation rate, and, fmthennore, an increase in the heterogeneity of system accelerates the transition dynamics. In the previous works, we have shown that, depending on the values of its control parameters, the potential has one, two or three possible minima, and the problem dealt with the constrnction of the equilibrilllll phase diagrams. It is also w01th mentioning that the previously obtained results are general and suggest a complete set of different transition scenarios in the entire parameter plane with two control parameters [4]. We study next the stability and bifurcation of equilibrilllll states in the kinetic processes conesponding to the first-order phase transitions in systems which can be characterized by several order parameters. Along with general analysis when the kinetic processes conesponding to phase transitions in systems characterized by r nlllllber of order parameters x1 ,x2 , ••• , X7 and m nlllllber of control parameters ai ,a2 , ... , am are described by a system of ordinaiy differential equations of the form dxr = .f,.(x1 ,x2, ••• ,x7 ;a1 ,a2, ••• ,am), where t is time, the results of specific calculations for dt systems described by the kinetic Landau-type potential with two pai·ameters are also presented. In general, the lai·gest and smallest values of order pai·aineter for the bifurcation analysis conespond to minima of free energy functional F, while the inte1mediate value conesponds to an unstable state (F has a local maximum or saddle point), and these three extrema ai·e identified with the crystalline and two liquid phases [5]. In case of a single - component glass which can be characterized in te1ms of the pressure P and volllllle V, the relation between P and V could be obtained using the equation P(V,T,x,y) = -(oF I oV)r.x.y . Note that P(V,T,x,y,) can be derived from experimental data and this equation may be fuither used to dete1mine the V-dependence of F(V,T,x,y,) Then F can be applied to get the entropy S = -(oF I oT)v.x.y, and in this way specific heats and other the1modynainic quantities for the system can be defined [ 6].
ANALYSIS OF SOLUTIONS FOR THE SYSTEMS OF NONLINEAR EQUATIONS DEPENDING ON PARAMETERS
(CEP USM, 2022-11-10) Paladi, Florentin; Barsuc, Alexandr A.
Analysis of solutions for the systems of nonlinear equations depending on parameters [Articol]
(CEP USM, 2022-11-10) Paladi, Florentin; Barsuc, Alexandr A.
ASSESSMENT OF PERCEIVED IMAGE QUALITY FOR SMARTPHONES WITH EMBEDDED CAMERA
(2018) Zorea, Pinchas; Bragaru, Tudor; Paladi, Florentin
Scopul cercetării constă în dezvoltarea unui nou cadru și model de evaluare subiectivă a calității imaginii fără referință la original (NR), care ar permite industriei de smartfonuri predicția PIQ.
Bifurcation and Stability Analysis of the Equilibrium States in Thermodynamic Systems in a Small Vicinity of the Equilibrium Values of Parameters [Articol]
(Springer Nature, 2018) Paladi, Florentin; Barsuk, Alexandr A.
The dynamic behavior of thermodynamic system, described by one order parameter and one control parameter, in a small neighborhood of ordinary and bifurcation equilibrium values of the system parameters is studied. Using the general methods of investigating the branching (bifurcations) of solutions for nonlinear equations, we performed an exhaustive analysis of the order parameter dependences on the control parameter in a small vicinity of the equilibrium values of parameters, including the stability analysis of the equilibrium states, and the asymptotic behavior of the order parameter dependences on the control parameter (bifurcation diagrams). The peculiarities of the transition to an unstable state of the system are discussed and the estimates of the transition time to the unstable state in the neighborhood of ordinary and bifurcation equilibrium values of parameters are given. The influence of an external field on the dynamic behavior of thermodynamic system is analyzed and the peculiarities of the system dynamic behavior are discussed near the ordinary and bifurcation equilibrium values of parameters in the presence of external field. The dynamic process of magnetization of a ferromagnet is discussed by using the general methods of bifurcation and stability analysis presented in the papers.
Cercetarea spectrelor de reflectanța a microobiectelor biologice la distanța [Articol]
(CEP USM, 2020) Chiriţa, Arcadii; Caraman, Mihail; Sprincean, Veaceslav; Paladi, Florentin
Cinetica tranziţiilor de fază dirijată cu parametrii de control [Articol]
(CEP USM, 2013-09-26) Gubceac, Ghenadii; Șveț, Aliona; Paladi, Florentin
COLECTAREA MICROPARTICULELOR SOLIDE DIN ATMOSFERA PENTRU CERCETAREA PROCESELOR DE POLUARE A AERULUI
(CEP USM, 2024) Chirița, Arcadi; Sprincean, Veaceslav; Paladi, Florentin
A new method for collecting solid particles polluting the atmosphere has been developed. The advantages of the proposed method make it possible to collect particulate matter from automobile exhaust polluting the atmosphere in real time using drones. Examination of collected particles can be done using various techniques without changing the shape, composition, or location of the particles. These studies show the possibility of microparticles collecting from the atmosphere and studying them using optical microscopy, atomic force microscopy, and microfluorescence.
Computational study of non-stationary cluster size distribution and rate of nucleation in case of pre-existing clusters [Articol]
(2006) Gamurari, Visarion; Paladi, Florentin; Eremeev, Vitalie; Al-Sabayleh, Moayad Abidalraheem Obid
he dynamics of a cluster-type system formed by constant total number of molecules, M, is studied when clusters change their sizes by nearest-size transitions (the Szilard model) with time-dependent boundary conditions and non-zero initial cluster size distribution. We compare these results to those reported previously [5], when non-stationary cluster size distribution was considered under the condition that only monomers are present in the system at the initial moment t=0, and describe the effect of arbitrary pre-existing clusters on the time evolution of the interacting clusters with different sizes, n. The average group size problem is also solved, and the process of relaxation in the system is studied.
Concepte privind modelarea ABM şi analiza de bifurcaţie în cercetarea proceselor de cristalizare [Articol]
(2014) Gubceac, Ghennadii; Paladi, Florentin
La baza prezentei lucrări a stat ideea de a realiza un studiu generalizat a proceselor de cristalizare.
Consolidarea triunghiului cunoașterii „Educație-Cercetare-Inovare” la USM: studiu de caz [Articol]
(CEP USM, 2020) Bulimaga, Tatiana; Sprincean, Veaceslav; Paladi, Adian; Savva, Marianna; Paladi, Florentin
Articolul de față reprezintă o analiză a componentelor triunghiului cunoașterii „Educație -Cercetare-Inovare”, efectuată în baza studiului conținutului proiectului Erasmus+ CBHE Educație pentru Drone–eDrone, în atenție fiind luată legătura lor reciprocă și complementaritatea acestui proiect cu proiectul de cercetare Tehnologii fizice avansate cu aplicarea UVS în monitorizarea şi modelarea factorilor de mediu–Monitor3D, desfășurate la Universitatea de Stat din Moldova (USM). Sunt prezentate instrumentele și căile de transfer de cunoștințe de la un proiect educațional privind dezvoltarea capacităților instituției și de formare a competențelor la un proiect național de cercetare și inovare. Acest studiu de caz poate servi drept model și ar putea fi multiplicat și în cazul altor proiecte.
Contribuții la studiul stabilității stărilor de echilibru ale sistemelor dinamice complexe [Articol]
(CEP USM, 2020) Barsuc, Alexandr; Paladi, Florentin
Contribuţii la teoria relaxării stărilor metastabile în lichide subrăcite şi sticle [Articol]
(CEP USM, 2009) Paladi, Florentin
The theory of phase transitions in supercooled liquids and glasses based on the cluster concept, and taken into accountthe recent discovery of the generation and extinction of crystal nuclei in supercooled liquids at very low temperatures,has been developed. In particular, the generation and extinction of nuclei was found at low temperatures in supercooled liquids of o-benzylphenol, salol and 2,2’-dihydroxybenzophenone, and was brought a new concept of irreversible structural relaxation in supercooled liquids and glasses. The practical value of this research is determined by the importance of understanding the connection between physical properties, microscopic structure of the substance and macroscopicconditions of materials processing, which is vital to produce new materials with advanced technological properties. However, the results allow to formulate the essence of a new research development in the study of complex cluster systems bymethods of statistical physics, numerical calculation and computer modeling.
DETECTAREA SEMNALELOR DE FLUORESCENȚĂ A PLANTELOR LA DISTANŢĂ CU FOLOSIREA UAV
(CEP USM, 2022-11-10) Chiriţa, Arcadii; Sprincean, Veaceslav; Savva, Marianna; Paladi, Florentin
Detectarea semnalelor de fluorescență a plantelor la distanţă cu folosirea UaV [Articol]
(CEP USM, 2022-11-10) Chiriţa, Arcadii; Sprincean, Veaceslav; Savva, Marianna; Paladi, Florentin
Determinarea stadiului de vegetație, a calității și tipului solului prin măsurări ale spectrelor optice [Articol]
(CEP USM, 2020) Spincean, Veaceslav; Caraman, Mihail; Chirița, Arcadii; Paladi, Florentin
Sunt cercetate spectrele de reflexie difuză și de fotoluminescență pentru probe de sol și de frunze colectate la diferite stadii de dezvoltare. Stadiul de vegetație a frunzelor și tipul lor poate fi determinat atât după marginea benzii de reflexie difuză în intervalul 460÷520 nm, cât și după valoarea numerică a coeficientului de reflexie difuză în regiunea pantei dependenței Rd(λ).Este determinat intervalul spectral în care se poate stabili calitatea și tipul solului după mărimea coeficientului de reflexie difuză.