No abstract

No abstract

This article presents preliminary analysis of the Latvian national EV fast - charging network after the first year of operation. The first phase of Latvian national EV fast-charging network was launched in 2018 with 70 charging stations on the TEN-T roads and in the largest towns and cities. The article looks at the initial results, both looking at the total capacity utilization for individual charging stations, determining the hourly charging distribution; and to the utilization of the network as a whole. The results present that there is a very large dispersion of the data, most of the charging events happening in a few charging stations in and around the capital of Latvia. However, there have been charging events in all charging stations, even in the most remote ones. Even more skewed distribution was observed analyzing the charging habits of the EV users, with 10 % of users accounting for more than half of the charging events. This should be taken into account when considering applying the results for the future, expecting larger number of electric vehicles in Latvia.

-The paper discusses the methodology of oxygen transfer virtual simulation in a wastewater biological treatment process, using the MATLAB/SIMULINK technology. A selftuning adaptive model of a wastewater aeration tank, as a nonstationary object, with variable time dependent sensitivity and inertia indexes, as the functions of input variable -air pneumatic supply capacity L g (t) (m 3 /min), output variable -dissolved oxygen concentration C(t) (g/m 3 ) and oxygen expenditure, as a load -q(t) (g/min), required for wastewater complete purification, is expounded. Virtual models, applying Laplace transforms and SIMULINK blocks library, are composed in order to compare the transient processes of dissolved oxygen concentration in the simplified stationary model with constant sensitivity and inertia coefficients, and in the non-stationary model with variable sensitivity and inertia indexes. The simulation block-diagram for non-stationary model adoption to the variable parameters is developed, using informative links from input variable L g (t), from variable load q(t) and feedback from output variable C(t) as inputs of calculation modulus, allowing to instantly re-calculate the variable indexes during simulation time. Comparison of the simplified stationary model and the non-stationary model shows that the simulation results of oxygen transfer differ up to 50%.

The aim of the work is to increase the efficiency of cyclone technology by using a separator plate. Cyclone technology is used not only in the processing of various agricultural products, but also in air purification from dust. Air flow trajectories and the movement of dust particles inside the cyclone unit were simulated and analyzed using Computational Fluid Dynamics (CFD) and particle study analyses. The separator plate was designed in certain sizes and placed inside the cyclone, thus increasing the efficiency of the cyclone. The angle of position of the separator plate significantly affected the obtained results. The experimental equipment was assembled together to test the simulation results. Wood ash was used to determine the efficiency of the cyclone. Studies have shown that the effect of the separator plate on increasing the efficiency of the experimental equipment is less than that shown in the simulations. Most of the experiments used ash particles that were greater than 20 μm, thus cyclone efficiency was 98.9 ± 0.05%. This confirms the compliance of CFD simulations with the physical model. More detailed research should be carried out in order to use the separator plate effectively for the filtration of very small dust particles.