1,720,982 research outputs found
Understanding the transformative potential of solar thermal technology for urban sustainability
Full text linkToday, more than half of the world’s population resides in urban areas, marking a significant change from the predominantly rural life of past centuries. Urbanization is most pronounced in better-developed regions, where more than 80% of inhabitants live in urban areas, while in many less-developed countries, the majority of the population still lives in rural areas (Ritchie et al., 2024). Projections indicate that by 2050, 68% of the global population will live in urban areas, adding about 2.5 billion people to urban centers, with nearly 90% of this growth concentrated in Asia and Africa. India, China and Nigeria are expected to account for 35% of this increase, highlighting the critical need for sustainable urban planning and infrastructure development to manage this unprecedented growth (United Nations, Department of Economic and Social Affairs, Population Division, 2019)
Modelling and analysis of V-shaped bifacial PV systems for agrivoltaic applications: A Python-based approach for energy optimization
Full text linkAgrivoltaic systems integrate photovoltaic (PV) energy production with agricultural activities, addressing the critical challenges of land use optimization and sustainable energy generation in the context of climate changes and food security. These systems are pivotal in offering a promising solution in mitigating the environmental and social impacts of utility-scale PV installations, such as habitat disruption and competition with agricultural land. This study evaluates a patented V-shaped bifacial photovoltaic system with a single-axis solar tracking, designed to optimize energy capture but also to minimize shading effects on crops like vineyards. A custom Python-based algorithm using PVlib was developed to simulate the performance of the system, accounting for mutual shading, multiple solar radiation reflections, and dynamic tilt adjustments. Simulations conducted for Palermo, Italy, revealed that the system collects 5.2 % less solar irradiation than traditional side-by-side configurations but achieves an annual energy output of 2089.3 kWh per pair of panels, along with 24 % reduction in land use. These results highlight the system capability to optimize spatial efficiency while maintaining high energy production. The novelty of this work lies in its tailored simulation approach, addressing the unique geometry and operational dynamics of the V-shaped configuration, and its potential adaptability to diverse agrivoltaics scenarios. Unlike existing tools and methodologies in the literature, this work introduces a customized Python-based model specifically designed to analyse the performance of this innovative structure, which is of recent conception and lacks precedent in both academic studies and commercial software solutions. By advancing the methodological framework for integrating renewable energy with agriculture, this study contribute to the broader goals of sustainable development and climate resilience
Environmental and energy performances of a newly installed Dish-Stirling Concentrating Solar Power plant based in Palermo
No full textn the last decade there has been a significant increase globally in solar based electricity production, like those produced from Concentrating Solar Power (CSP) plants. One of the most efficient CSP technologies today is the Dish-Stirling characterized by an efficiency greater than 30%, which may become highly competitive by 2030 according to the International Energy Agency. On one hand, the Dish-Stirling is responsible for high environmental impacts, caused during its production and installation due to their energy consumption and use of energy intensive raw material. On the other hand, no direct emissions are released during its use phase. However, only a careful analysis of the entire life cycle can give a clear representation of all generated impacts. Therefore, we present a preliminary Life Cycle Assessment of a grid-connected Dish-Stirling concentrator with nominal power of 33 kW located in Palermo, Sicily. The study has been implemented according to the international standards of series ISO 14040/44 (2006) with the aim to evaluate the Dish-Stirling’s eco-profile, which in a first step identifies the main energy flows and environmental impacts of the use-phase. The importance of the study is underlined by the fact the here considered CSP is the first connected to national grid. As first step primary data on the energy production in the use phase have been collected and a comparison in terms of CO2e with the normal energy grid showed that we are able to save 89% of the total CO2e emissions
A novel model to assess the energy demand of outdoor swimming pools
Full text linkIn the Mediterranean region, outdoor swimming pools, despite having lower energy consumption compared to indoor pools, are nonetheless highly energy-intensive structures, offering significant opportunities for energy efficiency improvements. Although there are numerous studies in the literature, few of these works have been dedicated to estimating the energy consumption of outdoor pools while considering typical local meteorological conditions and their occupancy rates. This paper presents a novel energy balance model for outdoor pools that incorporates the latest correlations for calculating evaporation due to forced convection and sky temperature, a new phenomenological model for assessing the enhancement of evaporation as a function of occupancy rate, and an approach that takes into account atmospheric stability conditions in defining wind-related heat losses. The model successfully predicts the annual energy consumption data for outdoor Olympic swimming pools in Greece with a mean absolute percentage error of less than 12 %. Simulations of an outdoor swimming pool operating with water at 26.5 C and in which the cover is not used present indicate a specific thermal energy consumption of about 2300 kWh/m2. A decrease in water temperature by 1 C and the use of a cover result in approximately 11 % and 30 % reduction in consumption, respectively
A validated energy model of a solar dish-Stirling system considering the cleanliness of mirrors
Full text linkSolar systems based on the coupling of parabolic concentrating collectors and thermal engines (i.e. dish-Stirling systems) are among the most efficient generators of solar power currently available. This study focuses on the modelling of functioning data from a 32 kWe dish-Stirling solar plant installed at a facility test site on the University of Palermo campus, in Southern Italy. The proposed model, based on real monitored data, the energy balance of the collector and the partial load efficiency of the Stirling engine, can be used easily to simulate the annual energy production of such systems, making use of the solar radiation database, with the aim of encouraging a greater commercialisation of this technology. Introducing further simplifying assumptions based on our experimental data, the model can be linearised providing a new analytical expression of the parameters that characterise the widely used Stine empirical model. The model was calibrated against data corresponding to the collector with clean mirrors and used to predict the net electric production of the dish-Stirling accurately. A numerical method for assessing the daily level of mirror soiling without the use of direct reflectivity measures was also defined. The proposed methodology was used to evaluate the history of mirror soiling for the observation period, which shows a strong correlation with the recorded sequence of rains and dust depositions. The results of this study emphasise how desert dust transport events, frequent occurrences in parts of the Mediterranean, can have a dramatic impact on the electric power generation of dish-Stirling plants
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
