1,721,062 research outputs found
The economic impact of agricultural projects in a petroleum-exporting country: the case of palm oil in the Republic of Congo
No full textA Machine Learning Algorithm to Minimize Distribution Lines Overloads
No full textTo address the issue of line overloads arising from the increasing integration of Renewable Energy Sources (RES) in distribution networks, advanced grid management strategies are needed to dynamically optimize network configurations. Within this context, grid reconfiguration methods allow to define the best configuration of the network to minimize line overloads, improve voltage values within the network and reduce power losses. Hence, reconfiguration methods allow to enhance the operations and management of distribution networks hosting a high share of RES. In this framework, this paper proposes a grid reconfiguration tool based on a machine learning algorithm, aimed at minimizing line overloads and reducing the number of reclosures in a distribution system. The proposed methodology is validated on a 10-node test network with significant RES penetration. The outcomes obtained show that, by applying the reconfigurations proposed by the tool, 56% reduction in total overload occurrences is obtained. The computational time needed by the machine learning-based algorithm to output the best configuration among all the possible ones is less than 1 second, demonstrating the usefulness of the proposed tool to cope with (near)real-time network issues. This result demonstrates the effectiveness of the proposed algorithm in reducing line overloads and improving the system performance
Impact of EU policy response to the Russian Invasion of Ukraine on Italian agri-food sector
No full textThis study examines the European Union’s (EU) policy response to the Russian invasion of Ukraine on 24 February 2022, which has affected trade with Russia and Ukraine across various sectors. The research employs a constrained nonlinear programming model, based on a multi-regional input-output table of the Italian economy, to compute and analyse direct and indirect impacts, particularly in the agri-food sector. Alternative policy responses, including deeper EU-Ukraine integration and further trade collapse, are simulated to validate the results. The findings suggest a minor overall impact on the agri-food sector, especially in Southern Italy, unless extreme measures are implemented. The evidence challenges protectionist calls and highlight the need for targeted, data-driven policy interventions to support the most vulnerable areas and enhance long-term resilience
Analytical load flow solution for radial distribution networks
No full textThis paper proposes an analytical method to solve the load flow problem for radial single and multi-feeder power distribution networks in three-phase balanced conditions. The Analytical Load Flow (ALF) formulation relies on a single assumption for the estimation of line losses and accounts for line susceptances. A set of comparative tests performed on a total active and passive 33 nodes benchmark network allowed showing that the accuracy of the proposed method is extremely high, if compared with the alternative numerical solution. Furthermore, a specific analysis is proposed to evaluate the impact of the approximation on the losses in the determination of the nodal voltage phasors. Finally, ALF is validated in a realistic scenario with high integration of Renewable Energy Sources (RESs), considering seasonal variations in production and consumption. In this context, it is shown that the proposed method outperforms existing approximate analytical approaches, such as the industrial voltage drop method. The ALF approach, being fully analytical, does not require any numerical solver and can be applied as a valid alternative to existing numerical and analytical methods in balanced multi-feeder networks
Policy responses to COVID-19 pandemic waves: cross-region and cross-sector economic impact
No full textThis paper proposes a modelling approach to assess the cross-region and cross-sector economic impacts of the restrictions imposed by governments to contain the COVID-19 pandemic. The nationwide lockdown imposed in Italy during the first wave of the pandemic is used as a benchmark. However, the adopted approach allows an ex-ante assessment of alternative policy responses, in the event of successive pandemic waves, in order to rationalize the policy intervention and reach the best possible compromise between containing the risk of contagion and reducing economic losses. The used approach consists of a non-linear programming model based on a multiregional Input-Output (I-O) table, which guarantees greater flexibility than traditional I-O analysis. It is applied to estimate both direct and indirect losses of GDP and employment produced by alternative policy responses represented by general and differentiated lockdowns. The evidence deriving from the Italian experience shows a sort of learning process through successive waves based on the introduction of increasingly flexible and tailored policy responses to the pandemic
Analysing the economy-wide impact of the supply chains activated by a new biomass power plant. The case of cardoon in Sardinia
Full text linkThis study investigates the impact on the economy of Sardinia (Italy) generated by a new biomass power plant fed by locally cultivated cardoon. The cardoon also serves the production of biopolymers. The impact is assessed at an economy-wide level using two multiregional closed Input-Output models, which allow us to take into account the entire supply chain activated and the supra-local effects generated by trade across local industries. The effects are computed under alternative scenarios simulating different levels of substitution of existing agricultural activities with the new activity (cardoon). Results show positive and locally significant impacts in terms of value added and employment. However, these impacts are substantially influenced by the degree of substitution. Results also suggest that there are specific territorial areas that are more sensitive to negative effects induced by substitution
Resilience of regions to adverse events. The importance of socio-economic impacts at local level
No full textMathematical modeling of the circulation in the liver lobule
No full textIn this paper, we develop a mathematical model of blood circulation in the liver lobule. We aim to find the pressure and flux distributions within a liver lobule. We also investigate the effects of changes in pressure that occur following a resection of part of the liver, which often leads to high pressure in the portal vein. The liver can be divided into functional units called lobules. Each lobule has a hexagonal cross-section, and we assume that its longitudinal extent is large compared with its width. We consider an infinite lattice of identical lobules and study the two-dimensional flow in the hexagonal cross-sections. We model the sinusoidal space as a porous medium, with blood entering from the portal tracts (located at each of the vertices of the cross-section of the lobule) and exiting via the centrilobular vein (located in the center of the cross-section). We first
develop and solve an idealized mathematical model, treating the porous medium as rigid and isotropic and blood as a Newtonian fluid. The pressure drop across the lobule and the flux of blood through the lobule are proportional to one another. In spite of its simplicity, the model gives insight into the real pressure and velocity distribution in the lobule. We then consider three modifications of the model that are designed to make it more realistic. In the first modification, we account for the fact that the sinusoids tend to
be preferentially aligned in the direction of the centrilobular vein by considering an anisotropic porous medium. In the second, we account more accurately for the true behavior of the blood by using a shear-thinning model. We show that both these modifications have a small quantitative effect on the behavior but no qualitative effect. The
motivation for the final modification is to understand what happens either after a partial resection of the liver or after an implantation of a liver of small size. In these cases, the pressure is observed to rise significantly, which could cause deformation of the tissue. We
show that including the effects of tissue compliance in the model means that the total blood flow increases more than linearly as the pressure rises
Design, realization and testing of a synthetic inertia controller for wind turbine power generators
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