1,720,982 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Modeling, assessment, and optimization of the indirectly heated carbonate looping process for CO₂ capture from lime plants
No full textLime is an essential raw material for iron and steel production, in construction and agriculture, in civil engineering, in environmental protection, and in manifold chemical manufacturing processes. To solve the problem of unavoidable process CO₂ emissions associated with the production of lime, efficient and affordable capture technologies need to be developed and implemented. The indirectly heated carbonate looping (IHCaL) process is a promising technology for capturing CO₂ from lime and cement production. This process can exploit synergies with these industries, achieving low penalties in terms of economics and energy utilization. However, this requires integration measures that have not been undertaken until now. Furthermore, experimental efforts to develop IHCaL technology have not been matched by modeling work. Yet, accurate models are crucial for interpreting experiments and scaling up this technology for commercial operation. In this study, we introduce concepts for efficiently integrating the IHCaL process into lime production. The main configurations are a tail-end solution suitable for retrofitting lime plants and a fully integrated configuration for greenfield projects. Furthermore, we present different fueling and heat integration strategies. We assessed these concepts in terms of energy efficiency, net CO₂ emissions, and CO₂ avoidance costs (CAC). The processes were simulated with Aspen Plus, including customized reactor models. EBSILON professional was used to model the steam cycles for heat recovery and power generation, and ECLIPSE was used for the economic analysis. The results show a considerable increase in fuel consumption, but approximately 30 % of the entire heat input can be converted into electric power via heat recovery steam generation. The critical parameters influencing the process efficiency are the preheating temperature of the combustion air, the sorbent temperature at calciner inlet, and the sorbent circulation rate. Utilizing the sorbent purge as lime product is necessary for the feasibility of the proposed concepts. The heat recovery strategy can be optimized to achieve tailored outcomes, such as reduced fuel requirement or increased power production. Net-negative CO₂ emissions higher than −1.8 tCO₂/tCaO can be obtained when firing waste-derived fuels. Fuels with a high biogenic fraction and low specific CO₂ emissions, such as solid recovered fuels (SRFs) with a high calorific value, perform remarkably well in terms of energy utilization (SPECCA < 1.5 MJLHV/kgCO₂,av) and cost efficiency (CAC < 20 €/tCO₂,av). We present a novel carbonator model for CO₂ capture using IHCaL technology. Our model is based on a systematic literature review, and experimental results from pilot tests and thermogravimetric analysis (TGA). The model features a reactor sub-model to simulate flow
patterns and gas-solid contact, and a particle sub-model to deal with sorbent deactivation and reaction kinetics. We follow an original approach to non-ideal calcination and introduce a new calculation methodology for sorbent aging that considers fluctuations in sorbent circulation and make-up rates. We highlight that modeling assumptions commonly found in the literature can result in a significant overestimation of the carbonator performance. Additionally, we offer guidelines for the appropriate selection of these assumptions. Finally, we introduce a novel calciner model by combining a particle sub-model with a onedimensional reactor sub-model. The model was validated with results from experimental campaigns conducted at two different pilot plants (300-kWth and 1-MWth). The predictions of the
model were interpreted using a stochastic methodology and novel dimensionless numbers. Based on the model, we introduce a three-step approach to designing calciners for CO₂ capture. Calciners with oxy-fuel combustion should be operated at 930–965 °C to achieve sufficient sorbent regeneration. For indirectly heated calciners, an operating temperature of 950 °C is necessary for high performance, but lower temperatures (e.g., 900 °C) are also possible using steam for fluidization. Considerations regarding particle residence time are also discussed. Our guidelines are straightforward and enable the design of a calciner with simple calculations.
Overall, our study provides valuable information on the potential of IHCaL technology for reducing CO₂ emissions in the lime industry and demonstrates how process configurations, fuel properties, operating parameters, and components can be optimized to exploit this potential. Our results reduce design uncertainties, avoidance costs, and energy penalties, thereby bringing this technology closer to commercialization
Modeling, assessment, and optimization of the indirectly heated carbonate looping process for CO₂ capture from lime plants
No full textLime is an essential raw material for iron and steel production, in construction and agriculture, in civil engineering, in environmental protection, and in manifold chemical manufacturing processes. To solve the problem of unavoidable process CO₂ emissions associated with the production of lime,
efficient and affordable capture technologies need to be developed and implemented. The indirectly heated carbonate looping (IHCaL) process is a promising technology for capturing CO₂ from lime and cement production. This process can exploit synergies with these industries, achieving low penalties in terms of economics and energy utilization. However, this requires integration measures that have not been undertaken until now. Furthermore, experimental efforts to develop IHCaL technology have not been matched by modeling work. Yet, accurate models are crucial for interpreting experiments and scaling up this technology for commercial operation. In this study, we introduce concepts for efficiently integrating the IHCaL process into lime production. The main configurations are a tail-end solution suitable for retrofitting lime plants and a fully integrated configuration for greenfield projects. Furthermore, we present different fueling and heat integration strategies. We assessed these concepts in terms of energy efficiency, net CO₂ emissions, and CO₂ avoidance costs (CAC). The processes were simulated with Aspen Plus, including customized reactor models. EBSILON professional was used to model the steam cycles for heat recovery and power generation, and ECLIPSE was used for the economic analysis. The results show a considerable increase in fuel consumption, but approximately 30 % of the entire heat input can be converted into electric power via heat recovery steam generation. The critical parameters influencing the process efficiency are the preheating temperature of the combustion air, the sorbent temperature at calciner inlet, and the sorbent circulation rate. Utilizing the sorbent purge as lime product is necessary for the feasibility of the proposed concepts. The heat recovery strategy can be optimized to achieve tailored outcomes, such as reduced fuel requirement or increased power production. Net-negative CO₂ emissions higher than −1.8 tCO₂/tCaO can be obtained when firing waste-derived fuels. Fuels with a high biogenic fraction and low specific CO₂ emissions, such as solid recovered fuels (SRFs) with a high calorific value, perform remarkably well in terms of energy utilization (SPECCA < 1.5 MJLHV/kgCO₂,av) and cost efficiency (CAC < 20 €/tCO₂,av). We present a novel carbonator model for CO₂ capture using IHCaL technology. Our model is based on a systematic literature review, and experimental results from pilot tests and thermogravimetric analysis (TGA). The model features a reactor sub-model to simulate flow
patterns and gas-solid contact, and a particle sub-model to deal with sorbent deactivation and reaction kinetics. We follow an original approach to non-ideal calcination and introduce a new calculation methodology for sorbent aging that considers fluctuations in sorbent circulation and make-up rates. We highlight that modeling assumptions commonly found in the literature can result in a significant overestimation of the carbonator performance. Additionally, we offer guidelines for the appropriate selection of these assumptions. Finally, we introduce a novel calciner model by combining a particle sub-model with a onedimensional reactor sub-model. The model was validated with results from experimental campaigns conducted at two different pilot plants (300-kWth and 1-MWth). The predictions of the
model were interpreted using a stochastic methodology and novel dimensionless numbers. Based on the model, we introduce a three-step approach to designing calciners for CO₂ capture. Calciners with oxy-fuel combustion should be operated at 930–965 °C to achieve sufficient sorbent regeneration. For indirectly heated calciners, an operating temperature of 950 °C is necessary for high performance, but lower temperatures (e.g., 900 °C) are also possible using steam for fluidization. Considerations regarding particle residence time are also discussed. Our guidelines are straightforward and enable the design of a calciner with simple calculations.
Overall, our study provides valuable information on the potential of IHCaL technology for reducing CO₂ emissions in the lime industry and demonstrates how process configurations, fuel properties, operating parameters, and components can be optimized to exploit this potential. Our results reduce design uncertainties, avoidance costs, and energy penalties, thereby bringing this technology closer to commercialization
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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