BcB_c spectroscopy

In the framework of potential models for heavy quarkonium the mass spectrum for the system ($\bar b c$) is considered. Spin-dependent splittings, taking into account a change of a constant for effective Coulomb interaction between the quarks, and widths of radiative transitions between the ($\bar b c$) levels are calculated. In the framework of QCD sum rules, masses of the lightest vector $B_c^*$ and pseudoscalar $B_c$ states are estimated, scaling relation for leptonic constants of heavy quarkonia is derived, and the leptonic constant $f_{B_C}$ is evaluated.Comment: IHEP 94-51, LATEX, 39 page

Selection of Appropriate Quantum-Chemical Model for Calculations of Properties of Chromium Group Complexes via DFT

The selection of a pair of functional/basis for the most adequate quantum-chemical determination of the geometric and electronic properties of chromium group metal complexes with polydent heterocyclic ligands has been carried out. When selecting a suitable model, such parameters as allowable accuracy and acceptable time of calculation have been taken into account. It has been found that the accuracy of calculations depends on the number of basis functions in-volved in the calculation model – the error tends to decrease with the increase in their number. The ac-curacy of calculations also increases with introduction of the polarized orbitals 2d2p and 3df3pd in the quantum-chemical model and the diffuse orbitals p, pp, ppp in the basis, respectively. The results obtained by using non-hybrid functionals with large basis functions are comparable to the calculations performed in less time with the help of hybrid functionals. The optimal ratio for the accuracy of calculation results compared to the time for study of the coordi-nation compounds can be achieved by using the PBE0 hybrid functional and TZVPP basis functions

Estimation of demand for crowdshipping services in Bratislava, Slovakia

У статті піднімаються питання щодо потреби в оптимізації логістичних систем, що призводить до збільшення споживчих, вантажних і транзитних потоків у центральній частині міста. Дисбаланс між необхідною та фактичною пропускною здатністю доріг сприяє виникненню таких транспортних проблем, як затори, затори, відсутність паркувальних місць, підвищений шум, концентрація аварій тощо.The article raises questions about the demand for optimization of logistics systems leads to an increase in consumer, freight and transit traffic flows in the central part of the city. The imbalance between the required and actual capacity of roads contributes to the emergence of such transport problems as congestion, traffic jams, lack of parking spaces, increased noise, the concentration of accidents, etc