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The rotor-rotor aerodynamic interaction is one of the key phenomena that characterise the flow and the performance of most of the new urban air mobility vehicles (eVTOLs) developed in the recent years. The present article describes a numerical activity that aimed to the systematic study of the rotor-rotor aerodynamic interaction with application to the flight conditions typical of eVTOL aircraft. The activity considers the use of a novel mid-fidelity aerodynamic solver based on vortex particle method. In particular, numerical simulations were performed when considering two propellers both in side-by-side and tandem configuration with different separation distances. The results of numerical simulations showed a slight reduction of the propellers performance in side-by-side configuration, while a remarkable loss of thrust in the order of 40% and a reduction of about 20% of the propulsive efficiency were found in tandem configuration, particularly when the propeller disks are completely overlapped. Moreover, the flow field analysis enabled providing a detailed insight regarding the flow physics involved in such aerodynamic interactions.

Over the past decade, decarbonization and environmental issues have taken a key role in worldwide politics [...]

Rural electrification in remote areas of developing countries has several challenges which hinder energy access to the population. For instance, the extension of the national grid to provide electricity in these areas is largely not viable. The Kenyan Government has put a target to achieve universal energy access by the year 2020. To realize this objective, the focus of the program is being shifted to establishing off-grid power stations in rural areas. Among rural areas to be electrified is Habaswein, which is a settlement in Kenya’s northeastern region without connection to the national power grid, and where Kenya Power installed a stand-alone hybrid mini-grid. Based on field observations, power generation data analysis, evaluation of the potential energy resources and simulations, this research intends to evaluate the performance of the Habaswein mini-grid and optimize the existing hybrid generation system to enhance its reliability and reduce the operation costs. The result will be a suggestion of how Kenyan rural areas could be sustainably electrified by using renewable energy based off-grid power stations. It will contribute to bridge the current research gap in this area, and it will be a vital tool to researchers, implementers and the policy makers in energy sector.

Transport is a main source of pollutants in cities, where air quality is a major concern. New transport technologies, such as electric vehicles, and public transport modalities, such as urban railways, have arisen as solutions to this important problem. One of the main difficulties for the adoption of electric vehicles by consumers is the scarcity of a suitable charging infrastructure. The use of the railway power supplies to charge electric vehicle batteries could facilitate the deployment of charging infrastructure in cities. It would reduce the cost because of the use of an existing installation. Furthermore, electric vehicles can use braking energy from trains that was previously wasted in rheostats. This paper presents the results of a collaboration between research teams from University of Rome Sapienza and Comillas Pontifical University. In this work, two real European cases are studied: an Italian metro line and a Spanish metro line. The energy performance of these metro lines and their capacity to charge electric vehicles have been studied by means of detailed simulation tools. Their results have shown that the use of regenerated energy is 98% for short interval of trains in both cases. However, the use of regenerated energy decreases as the train intervals grow. In a daily operation, an important amount of regenerated energy is wasted in the Italian and Spanish case. Using this energy, a significant number of electric vehicles could be charged every day.

The energy sector, along with the conditions of the natural and built environment, are significantly affected by the tremendous increase in total energy consumption [...]

The object of research is the process of implementing energy-efficient measures at industrial enterprises. One of the problem is the trend of reduction of investment in the sphere of energy efficiency. It has been established that after several years of growth, global investments in energy efficiency and renewable energy sources began to decline in 2017. According to the International Energy Agency, there is a risk that the trend of investment shrinkage will continue. In the framework of the PINE project in Austria, 20 energy audits were carried out, which resulted in the introduction of measures aimed at energy efficiency. According to the results of the project, the link between investment and implementation of measures on energy efficiency and life cycle and type of enterprises implemented in companies of different industries was analyzed and argued. It is established that about 50 % of the identified energy savings from the implementation of measures is the result of the use of frequency drive drives, elimination of leakage of compressed air or modernization of lighting systems. This allows to develop rational business and policy strategies for enterprises at different stages of the life cycle. In the course of the study, an approach focused on single operations selected in this program has been analyzed, which facilitates the identification of links between energy consumption by production units and technological and organizational factors influencing its consumption. The scientific novelty of the research is expressed in the substantiation of critical strategic barriers in the field of investment in energy-efficient solutions, which allowed proposing rational business strategies and appropriate political support measures to overcome them. Due to the fact that enterprises with the same input and output resources can have a different process cycle, payback periods for the same implemented measures may be different. An analysis of the real experience of energy conservation with the developed business strategies and policies of political support allows it to be effectively disseminated in European countries.

The transition towards renewable energy sources and “green” technologies for energy generation and storage is expected to mitigate the climate emergency in the coming years [...]