There is a cascade of hydroelectric power plants built on the Váh River. From a water-management point of view, the natural channel is used to drain extreme discharges. During most of the year, discharges are regulated by water-management structures. These discharges are not used for energy-related purposes; therefore, it is important to determine the optimal discharge that will not negatively affect the ecosystem of the stream. The minimum balance discharge (hydro-ecological discharge) was determined based on the instream flow incremental methodology (IFIM) using the riverine habi-tat simulation system (RHABSIM). Input data were obtained from direct measurements on three reference reaches in the area between the cities Piešťany and Nové Mesto nad Váhom. Hydraulic flow characteristics were derived from three measurements at different water levels. Habitat quality was represented by ichthyofauna. Data to determine the habitat suit-ability curves of fish were obtained using a diving technique to collect video footage. The modelling resulted in the quanti-fication of the effect of discharge on ichthyofauna as a bio-indicator of habitat quality, which implied the need of 20 m3∙s–1 for a minimum balance discharge in summer.
We experimentally studied three different D-shape polymer optical fibres with an exposed core for their applications as surface plasmon resonance sensors. The first one was a conventional D-shape fibre with no microstructure while in two others the fibre core was surrounded by two rings of air holes. In one of the microstructured fibres we introduced special absorbing inclusions placed outside the microstructure to attenuate leaky modes. We compared the performance of the surface plasmon resonance sensors based on the three fibres. We showed that the fibre bending enhances the resonance in all investigated fibres. The measured sensitivity of about 610 nm/RIUfor the refractive index of glycerol solution around 1.350 is similar in all fabricated sensors. However, the spectral width of the resonance curve is significantly lower for the fibre with inclusions suppressing the leaky modes.
The studies showed that alkaline lipase from Pseudomonas fluorescens enables an irreversible transesterification of vinyl esters to give enantiomeric excess (eeR) of about 80% using vinyl butyrate as acyl donor and diisopropyl ether as a solvent, at partially optimized conditions. For the native lipase the process was adequately described by a five-parameter Ping-Pong Bi Bi model for both enantiomers plus expression accounting for the formation of enzyme-acyl donor complex, but for the same lipase supported on mesoporous materials of SBA-15-Oc type, R-product inhibition also had to be taken into account. The use of hydrophobic support increased by more than two-fold the rate of the S-solketal conversion but even more that of R-solketal. Thus the immobilization of lipase had very positive effect on the process kinetics but decreased its enantioselectivity.
This paper presents an analysis of the stator teeth geometry impact on the parameters of the 8-pole radial magnetic bearing. In this paper, such parameters as current gain and position stiffness have been analysed. Additionally, we have proposed criteria for evaluating the characteristics of these parameters by calculating the variability of current gain and position stiffness. The research has been performed by solving the magnetic bearing actuator boundary problem using the finite element method. Magnetic force has been calculated using the Maxwell stress tensor method. Other parameters, such as current gain and position stiffness have been calculated as partial derivate of the force with respect to control current and position of the rotor.