In this work the esterification of diethyl tartrate was studied. The research was focused on the enhancement of reversible reaction yield, which is accomplished by dewatering of the reaction mixture. The removal of water shifts the equilibrium towards the main product. Pervaporation was applied for this purpose, and results were compared to distillation. The advantages and limitations of both processes are discussed. The experimental part consists of dewatering of mixture after the reaction had reached the equilibrium, and was subsequently fed to the test rig equipped with a single zeolite membrane purchased from Pervatech B.V. Results show a significant conversion increase as a result of water removal by pervaporation. Compared to distillation no addition of organics is necessary to efficiently remove water above the azeotrope. Nevertheless, some limitations and issues which call for optimisation are pointed out. A simple numerical model is proposed to support design and sizing of the pervaporation system. Various modes of integrated system operation are also briefly discussed.
Various trading strategies have been proposed that use estimates of the Hurst coefficient, which is an indicator of long-range dependence, for the calculation of buy and sell signals. This paper introduces frequency-domain tests for long-range dependence which do, in contrast to conventional procedures, not assume that the number of used periodogram ordinates grow with the length of the time series. These tests are applied to series of gold price returns and stock index returns in a rolling analysis. The results suggest that there is no long-range dependence, indicating that trading strategies based on fractal dynamics have no sound statistical basis.
The strategic goals of EU energy development have been clarified, based on efforts to increase and comply with environmental protection requirements, reducing energy consumption in the manufacturing and service sector, reduce dependence on energy imports, and increase the involvement of renewable resources in energy. The structure of the unified energy system of Ukraine was monitored. The volumes of electricity released by various power-generating enterprises in Ukraine, as well as the existing capacity of main and inter-state electric power grids for transmission of electricity, were analyzed. The volume of electricity exports and imports of the unified energy system of Ukraine and its possibilities to increase exports to the EU countries have been diagnosed. It has been proven that due to the change in the operating model of the electricity market the liberalization of the electricity market of Ukraine promotes the attraction of investment resources aimed at branching the possibilities of importing electricity generated in Ukraine into the ENTSO-E system. The structural tendencies of changes in generated electricity in final consumption at the expense of renewable energy sources of the European countries and Ukraine were studied. Options for increasing the efficiency of renewable energy sources are proposed The use of renewable energy sources on the basis of leveling out certain disadvantages is proposed. The directions improve the management of electricity enterprises in the conditions of the European integration choice of Ukraine including towards attracting investment resources through the use of public-private partnerships to improve the efficiency of the energy system of Ukraine are substantiated.