One of the major challenges faced by water companies around the world is the high level of water losses in distribution networks. This research paper presents a case study on the choice of the best technical solution for the rehabilitation of the water distribution network pipelines of Cluj-Napoca City, Romania. The analytical network process (ANP) method was used as the selection method, and calculations were performed using the Super Decisions 2.6.0 software. In the case study, five alternatives were analyzed based on seven criteria. The criteria taken into account in the decision-making included pipe diameter, pipe length, specific accomplishment duration, lifespan, pressure losses, price, and installation conditions, while the following methods were considered as rehabilitation alternatives: Compact Pipe, Slipline, Subline, Swagelining, and Pilot Pipe. Based on the highest global priority, we recommend choosing the Subline alternative as the method of rehabilitating water distribution pipes from asbestos cement pipes in the case of Cluj-Napoca City, Romania.

This article analyses the relation between the failures that occurred in the water supply network and the road traffic in the city of Cluj-Napoca in Romania. The calculations in this case study were made using the Autodesk Robot Structural Analysis Professional 2011 software. In the case study, the following types of pipes were analysed: steel, gray cast iron, ductile cast iron and high density polyethylene (HDPE). While in most studies only a few sections of pipelines, several types of pipelines and certain mounting depths have been analysed, the case study presented analyses the entire water supply system of a city with a population of 324,576 inhabitants, whose water supply system has a length of 479 km. The results of the research are useful in the design phase of water distribution networks, so depending on the type of pipe material, the minimum depth of installation can be indicated, so as to avoid the failure of the pipes due to road traffic. From this perspective, similar studies could also be carried out regarding the negative influence of road traffic on sewerage networks, gas networks and heating networks.

The selection of the optimal solution regarding the concentration ratio is a complex process, as it depends on a very high number of criteria. The production of renewable energy using the concentrated solar radiation is a field of high scientific level worldwide, while in Romania the research in this field is only in its early stages. The purpose of this document is to present a classification method for photovoltaic systems taking into account the concentration ration. The paper tries to fill in a gap in the field of choosing the photovoltaic systems from the concentration ratio perspective. Based on the study performed, we recommend using the variant A4, namely the technical solution consisting of a photovoltaic system with a 1000x concentration ratio