Recommendations of Optimal Sampling Rates for Periodic Output Feedback Based Discrete Mode PSS

In this paper, an attempt is made to recommend the optimal sampling time period for Periodic Output Feedback (POF) based discrete mode power system stabilizer (DPSS). Various collection of input and output sampling time interval has been used in the designing of POF based DPSS. The Particle Swarm Optimization (PSO) technique is used to obtain the optimal gain matrix of the POF controller as well as the optimal sampling time intervals. The effectiveness of POF based DPSS over continuous mode lead-lag PSS is certified using small-signal stability studies. The parameters of lead-lag type continuous mode PSS is also tuned using the PSO technique. The PSS is designed using POF technique for single machine infinite bus (SMIB) system, considering a variety of sampling time intervals at input-output port. Finally, a trial is made to propose an optimum input and output sampling time period for SMIB test power system, through simulation studies.

Effect of the composition of flour nutrient substrates on the activity of microorganisms from the bacterial concentrates

The need to develop the technology of liquid acid-forming ferments using bacterial concentrates for the production of national types of bread in discrete mode was shown. The choice of bacterial concentrates was based on the optimal pH (4.5 – 5.5) and temperature (30ºC – 40ºC) of flour nutrient substrates, which are necessary to ensure the directed cultivation of microorganisms in the technology of liquid acid-forming ferments. The choice of bacterial concentrates was based on the maximum acidity that microorganisms could provide after two days of cultivation and which should be in the range of 100 to 180 degrees of Turner. The use of Belarusian bacterial concentrates on the basis of the comparative characteristics was proposed. Flour nutrient substrates for the cultivation of microorganisms from bacterial substrates have been proposed. They contained traditional components (rye flour, rye malt) and components for stimulation of activity of microorganisms from bacterial concentrates (dairy whey in liquid form, Echinaceae purpurea herba). The choice of the ratio between the components was based on the peculiarities of the technology of production of national types of bread and the possibility of providing microorganisms from bacterial concentrates with the necessary nutrients. Microorganisms of bacterial concentrate "IM-pro 1" (a consortium of dried lactic acid bacteriums and bifidobacteriums) using the proposed flour nutrient substrates during cultivation had the best activity for a shorter period of cultivation. This made it possible to propose the use of this bacterial concentrate as a source of microorganisms in liquid acid-forming ferments for national types of bread and to ensure the preparation in one stage.