1,720,962 research outputs found
Battery Energy Storage Systems: Optimal Energy Management and Techno-Economic Analysis in Power System Applications
Full text linkL'abstract è presente nell'allegato / the abstract is in the attachmen
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
Profitability of energy arbitrage net profit for grid-scale battery energy storage considering dynamic efficiency and degradation using a linear, mixed-integer linear, and mixed-integer non-linear optimization approach
Full text linkGrid-scale energy storage is becoming an essential element to effectively support the rapid increased use of renewable energy sources in the power network. The present work proposes a long-term techno-economic profitability analysis considering the net profit stream of a grid-level battery energy storage system (BESS) performing energy arbitrage as a grid service. The net profit is a cost function that includes the revenue derived by arbitrage, the import cost and the degradation cost induced by battery capacity fade. Three optimization techniques with a computationally efficient optimization logic are developed. The scenario with no-degradation is formulated as a linear programming (LP) problem, while the scenarios with and without degradation are formulated as mixed-integer linear programming (MILP), and as mixed-integer non-linear programming (MINLP) problems. The non-linearity is introduced by implementing a BESS dynamic charge/discharge efficiency that is a function of the BESS power rate. Based on the obtained BESS optimal scheduling, a long-term profitability analysis is developed during the whole BESS lifetime. In the proposed case study, historical electricity market prices from the CAISO electricity market in the United States, California, are used as input. We found that, even without degradation, the break-even investment cost that makes the BESS profitable with a power to-energy-ratio of 1MW/2MWh is 210 $/kWh. By implementing a cycle-counting degradation model, we observed a remarkable battery degradation on BESS profitability corresponding to a yearly net profit reduction in the 13-24% range. From a long-term application perspective, the BESS calendar lifetime could be extended by reducing the battery cycling. Such cycling reduction is obtained by adding a penalty cost in the objective function of the energy arbitrage optimization problem
Optimal Energy Management of a Utility-Scale Battery Energy Storage System Integrated with a Photovoltaic Power Plant Considering Battery Degradation
No full textGrid-scale energy storage systems are becoming an essential element to effectively support the rapid increased use of renewable energy sources in the power network. An energy management system (EMS) is essential to optimize the energy dispatching operations by controlling the operating point of each of the system components. The present work proposes an optimal scheduling for an EMS of a utility-scale photovoltaic power plant (PV) coupled with a battery energy storage system (BESS). The EMS model is based on a computationally efficient optimization logic formulated as a mixed-integer linear programming (MILP) problem. In the proposed case study, PV hourly generation data and historical electricity market prices from the CAISO electricity market in the United States, California, are used as input. The achievable profit from energy arbitrage of PV plus BESS systems is determined considering the impact of battery degradation
Model complexity and optimization trade-offs in the design and scheduling of hybrid hydrogen-battery systems
Full text linkThe production of hydrogen from renewable sources could play a significant role in supporting the transition toward a decarbonized energy system. This study has involved investigating optimization strategies - mixed-integer linear programming (MILP), a hybrid particle swarm optimization (PSO)-MILP framework, and PSO combined with a rule-based energy management strategy (EMS) - applied to a power-to-hydrogen system for industrial applications. The analysis evaluates the levelized cost of hydrogen production (LCOH), carbon emissions, and the impact of key factors, such as battery degradation, electrolyzer efficiency, real-time pricing, and hydrogen load management. The obtained results indicated that the MILP-based models achieved moderate LCOH values (10.1-10.7 €/kg) but incurred higher CO2 emissions (20.2-24.6 kt/y). Instead, the PSO model, combined with the rule-based EMS, lowered emissions to 14.3 kt/y (a 27-45% reduction), albeit with a higher LCOH (11.6 €/kg). The hybrid PSO-MILP models struck a balance, achieving LCOH values of between 9.2 and 9.7 €/kg, with CO2 emissions of 19.7-20.3 kt/y, as they benefited from the integration of piecewise affine linearization for modeling electrolyzer efficiency and battery degradation. In terms of computational efforts, the MILP-based models required more than 48 h to converge, while the PSO-MILP models completed within 27-35 h, and the PSO model with rule-based EMS achieved results in 1.5 h. These findings offer guidance that can be used to select the most suitable optimization method on the basis of the desired performance targets, resource constraints, and computational complexity, thereby contributing to the design of more sustainable energy systems
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
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