Study of the cost management system in the organization as an example of Ltd. «RMF»

Полягає у дослідженні системи управління витратами КТ «РМФ» та розробці заходів з підвищення її ефективності. У роботі запропоновано ефективний до підхід управління витратами; проаналізовано доцільність створення Інтернет – магазину; проведено обґрунтування ефективності використання альтернативних джерел постачання ресурсів та впровадження системи «АGIS» - автоматизованої системи управління витратами досліджуваного підприємства

Influence of Coulomb and Phonon Interaction on the Exciton Formation Dynamics in Semiconductor Heterostructures

A microscopic theory is developed to analyze the dynamics of exciton formation out of incoherent carriers in semiconductor heterostructures. The carrier Coulomb and phonon interaction is included consistently. A cluster expansion method is used to systematically truncate the hierarchy problem. By including all correlations up to the four-point (i.e. two-particle) level, the fundamental fermionic substructure of excitons is fully included. The analysis shows that the exciton formation is an intricate process where Coulomb correlations rapidly build up on a picosecond time scale while phonon dynamics leads to true exciton formation on a slow nanosecond time scale.Comment: 18 pages, 7 figure

Exciton formation and relaxation in GaAs epilayers

Exciton formation and relaxation in GaAs bulk epilayers have been studied by means of time-resolved photoluminescence techniques. It is found that the time evolution of the free exciton luminescence, nonresonantly excited at low temperature and low intensity, is extremely slow, with a rise time of the order of 1 ns and a decay time of several ns. Simulations based on Monte Carlo solution of the set of coupled Boltzmann-like equations for free carriers and excitons show a nice agreement with the experimental data, and suggest a dominant role played by acoustic phonons in the exciton relaxation