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Chisinau, Moldova

The Academy of science of Moldova , established in 1946, is the main scientific organization of the Republic of Moldova and coordinates research in all areas of science and technology. Wikipedia.

Disadvantages of some well- known methods of analysis of electric circuits with variable loads are analyzed. To interpret a mutual influence of the loads, some methods of the projective geometry are used. The application of the projective coordinates allows receiving the equation of the active two-port network in a normalized or relative form aswellas defining the scales for the currents and conductivity of the loads. Such approachmakesit possible to estimate the qualitative characteristics of the current regimes, tocomparethe regime efficiency of the different circuits. The formulas of the recalculationof the currents, which possess the group properties at change of conductivity of the loads, are obtained. It allows expressing the final values of the currents through the intermediate changes of the currents and conductivities. The generalized equivalent generator of the active two-port network in the form of the passive two-port network and a set of the sources of a current and voltage is proposed. The parameters of these sources do not depend oncertain conductivities of the passive two-port network. Source

Algorithms of space-vector-based synchronized pulsewidth modulation (PWM) have been applied for control of dual-inverter fed open-end winding induction motor drives supplied by two isolated dc-sources with non-equal voltages. Results of modeling and simulation of these systems proved the fact, that techniques of synchronized PWM provide continuous phase voltage symmetry (quarter-wave symmetry, or half-wave symmetry) for any ratios (integral or fractional) between the switching and fundamental frequencies of dual-inverter systems on the base of either standard inverters or neutral-point-clamped inverters, and also for any ratios between voltages of two dc-sources of the system. Source

Khvorostukhin A.S.,Moldova Academy of Sciences
Physical Review D - Particles, Fields, Gravitation and Cosmology

The pressure of an ideal relativistic Fermi gas is computed as an infinite series for high temperatures at nonzero chemical potentials. The expansion of the particle number density, scalar density, and entropy density as first derivatives of the pressure is also found. © 2015 American Physical Society. Source

Macaev F.Z.,Moldova Academy of Sciences
Studies in Natural Products Chemistry

Carvones produced by a wide variety of plants represent a group of inexpensive and abundant starting materials for fine chemical synthesis. A family of chiral monoterpenes, which incorporate carvones due to their natural chirality and advanced skeleton, serve as a feedstock for asymmetric synthesis of bioactive natural products. Notably, nature produces carvones in both enantiomeric series, which favorably compares with other natural sources of chirality such as amino acids and sugars and occurring predominantly in only one enantiomeric form. This review represents a comprehensive account of enantiomeric carvones with up-to-date coverage of the relevant literature for the past decade. The chapters are arranged in a manner to reflect the main strategies for the use of these compounds in stereoselective synthesis of the target bioactive natural products: from the chemical transformations where the original skeleton remains intact, to the reactions leading toward a gradual fragmentation of the carvone framework. © 2013 Elsevier B.V. All rights reserved. Source

Two types of resonance between the spontaneous emissions by two- and single photon transitions of three inverted radiators from the ensemble are proposed to accelerate the collective decay rate of the entangled photon pairs generated by the system relative the dipole-forbidden transition. One of them corresponds to the situation when the total energy of emitted photons by two dipole-active radiators enter the two-photon resonance with the dipole-forbidden transition of third atom. Second effect corresponds to the scattering situation, when the difference of the excited energies of two dipole-active radiators is in the resonance with the dipole-forbidden transition of third atom. These effects are accompanied with the interferences between single- and two-quantum collective transitions of three inverted radiators from the ensemble. The three particle collective decay rate is defined in the description of the atomic correlation functions. © EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2012. Source

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