Suchergebnisse

Seizing the energy access gap is a central objective in the international agenda, as it is a required precondition to enable sustainable growth, and is it positively interlinked with all other developmental goals. While rural electrification is steadily progressing in many developing areas, a change of pace is in order to achieve universal access in the next ten years. Alongside grid extension and standalone systems, mini-grids are considered a key technical solution to provide cost-effective, high-quality power to hundreds of thousands of people. Their diffusion is, however, hampered by many barriers and constraining factors, such as the lack of adequate governmental policies and unclear regulatory framework, limited access to financing due to unproven business models, and the high capital and operating costs due to lack of effective, standardized practices in the development and design phase. Academic knowledge production should contribute effectively to this complex scenario, by addressing the multiple governmental and industrial stakeholders, with the ultimate goal of establishing an enabling environment in which investments for rural electrification projects are attractive for private developers without relying on grants. The methodological and technical contributions proposed in this work have therefore the specific objective of helping increase the feasibility of mini-grids for rural electrification. The first challenge faced when setting up this research, was the one of data scarcity, that affects the rural electrification sector at multiple levels and makes difficult to develop academic contributions. Therefore, a first, cross-sectoral objective of the research work has been to overcome these limitations by streamlining data acquisition pathways through field missions in developing countries in East Africa (Kenya, Rwanda, Uganda) and Central America (Honduras, Costa Rica). This allowed to establish connections not only with rural communities but also with local universities, governmental entities and companies. These multiple-sided interactions between different entities coming both from developed countries and the global south have been part of the research method and entailed much more than one-sided data transfer. Therefore, they have been studied and conceptualized under the Triple Helix framework. As a first application of this approach, a critical analysis of existing business models for decentralized renewable energy solutions in sub-Saharan Africa has been carried out in partnership with non-profit and private actors, making use of actual operating data obtained from 21 mini-grids. Then, load profile estimation and modeling are tackled, as they are pivotal elements in the mini-grid development process, and are suffering from a lack of general understanding, data and tools to perform them. Two complementary approaches are presented, one based on effective field survey methodologies for the energy need assessment of rural communities and the other based on a clusterization and characterization of load profiles, built upon a unique, open-access database created for this purpose. Then, the optimal design of mini-grids integrating advanced, predictive operating strategies is addressed, with a contribution aimed at increasing their viability by reducing their computational requirements. This line of research, despite being conceived for and applied to case studies from developing countries, is relevant for hybrid mini-grids as a technological solution per se. Therefore, to demonstrate the extension of mini-grid application to isolated areas of developing countries, the case study of an hybridization and demand side management proposal for the mediterranean island of Ustica (Italy) is presented.

When examining social targets, people may ask asymmetric questions, that is, questions for which "yes" and "no" answers are neither equally diagnostic nor equally frequent. The consequences of this information-gathering strategy on impression formation deserve empirical investigation. The present work explored the role played by the trade-off between the diagnosticity and frequency of answers that follow asymmetric questions. In Study 1, participants received answers to symmetric/asymmetric questions on an anonymous social target. In Study 2, participants read answers to a specific symmetric/asymmetric question provided by different group members. Overall, the results of both studies indicate that asymmetric questions had less impact on impressions than did symmetric questions, suggesting that individuals are more sensitive to data frequency than diagnosticity when forming impressions.

AbstractThirty-two trace elements were examined in the tree rings of downy oak to evaluate the pollution levels close to a cement plant isolated in a rural context and an industrial area where multiple sources of air pollution are or were present. Tree cores were collected from trees growing 1 km from both the cement plant and the industrial area that are located 8 km from each other. The analysis of the trace elements was performed on annual tree rings from 1990 to 2016 using laser ablation inductively coupled plasma mass spectrometry. Trace elements Cs, Mg, Mn, S and Zn reflected the emission history of the cement plant. Their values have increased since early 2000s, when the cement plant started its activity. However, the lack of significant trends of pollutants in the tree rings from the industrial area and the possible effect of translocation and volatility of some elements left open questions. The very weak changes of the other trace elements in the period 1990–2016 suggest those elements do not mark any additional effect of the industrial activity on the background pollution. The results confirm that downy oak trees growing close to isolated industrial plants must be considered a pollution forest archive accessible through dendrochemistry.

Tree rings are natural archives of climate and environmental information with a yearly resolution. Indeed, wood anatomical, chemical, and other properties of tree rings are a synthesis of several intrinsic and external factors, and their interaction during tree growth. In particular, Intra-Annual Density Fluctuations (IADFs) can be considered as tree-ring anomalies that can be used to better understand tree growth and to reconstruct past climate conditions with intra-annual resolution. However, the ecophysiological processes behind IADF formation, as well as their functional impact, remain unclear. Are IADFs resulting from a prompt adjustment to fluctuations in environmental conditions to avoid stressful conditions and/or to take advantage from favorable conditions? In this paper we discuss: (1) the influence of climatic factors on the formation of IADFs; (2) the occurrence of IADFs in different species and environments; (3) the potential of new approaches to study IADFs and identify their triggering factors. Our final aim is to underscore the advantages offered by network analyses of data and the importance of high-resolution measurements to gain insight into IADFs formation processes and their relations with climatic conditions, including extreme weather events. ; This research is linked to activities conducted within the COST FP1106 "STReESS" network. Collection of datasets used for this work was supported by the projects: – ELENA (CGL2012-31668) and CGL2015-69985-R funded by the Spanish Science and Innovation Ministry (MICINN) and FEDER funds. – PGIDIT06PXIB502262PR funded by Dirección Xeral de Investigación, Desenvolvemento e Innovación, Xunta de Galicia. – Slovenian Research Agency (program P4-0015). – Austrian Science Fund (FWF-TRP 122-B16). – Russian Science Foundation 14-14-00295. – POCI/CLI/58680/2004 and PTDC/AAC-AMB/111675/2009 funded by the Portuguese Foundation for Science and Technology (FCT) and the European Union (POCI 2010) ; SI