Variability of COVID-19 and MIS-C Related Abdominal Surgical Presentations in Children: Case Report Series

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Adaptive Model of Wastewater Aeration Tank

Abstract – The paper discusses the methodology of oxygen transfer virtual simulation in a wastewater biological treatment process, using the MATLAB/SIMULINK technology. A self-tuning adaptive model of a wastewater aeration tank, as a non-stationary object, with variable time dependent sensitivity and inertia indexes, as the functions of input variable - air pneumatic supply capacity Lg(t) (m3/min), output variable – dissolved oxygen concentration C(t) (g/m3) 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 Lg(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%

Latvian Electric Vehicle Fast Charging Infrastructure: Results of the First Year of Operation

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

ENERGY EFFICIENT METHOD FOR ENERGY RECOVERY FROM BIOGAS PRODUCTION

A new method for biogas heating, cooling and drying has been developed. The method is based on two channel counter flow where recuperation happens. Biogas cooling is done with the dried colder flow to get the gas below the dew point temperature and allow it to condensate, but heating is done with humid hot gas flow from bioreactor. The system is being tested both experimentally and numerically by mathematical modelling. A previously developed 1D model has been implemented in MATLAB and calculations made for experimental setup. The results are also compared to 3D model made with ANSYS/CFX software