1,720,956 research outputs found
Analyzing the global warming potential of the production and utilization of lithium-ion batteries with nickel-manganese-cobalt cathode chemistries in European Gigafactories
Full text linkThis study evaluates the global warming potential (GWP) impact of producing lithium-ion batteries (LIBs) in emerging European Gigafactories. The paper presents a cradle-to-gate (CTG) life cycle assessment (LCA) of nickel-manganese-cobalt (NMC) chemistries for battery electric vehicle (BEV) applications. We consider three scenarios to cover the most probable production routes in Germany, France, and Italy, foreseen as the largest European LIB producers by 2030. The energy demand for manufacturing considers two cases: electricity only and a mix of heat and electricity. The results show that European Gigafactories can reduce the overall GWP relative to 1 kWh of NMC battery, with respect to Chinese NMC LIBs, in a range of 32-60%. This corresponds to a decrease in equivalent CO2 emission of 32-81 kg CO2 eq., depending on the location, the energy demand and the NMC chemistry, if the whole production takes place in the facility. French Gigafactories obtain the upper bound of this reduction. A sensitivity analysis of the source of the lithium compound, used to produce the active cathode material, shows that increasing the nickel content decreases the GWP impact per kWh of battery capacity. However, NMC622 generates less equivalent CO2 than NMC811, for lithium compound produced from Chilean brine. In addition, a simplified analysis of the utilization phase of two different classes of BEVs shows the positive effects of the regional LIB production and of the low carbon intensity of the electricity mix
A detailed MILP formulation for the optimal design of advanced biofuel supply chains
Full text linkThe optimal design of a biomass supply chain is a complex problem, which must take into account multiple interrelated factors (i.e the spatial distribution of the network nodes, the efficient planning of logistics activities, etc.). Mixed Integer Linear Programming has proven to be an effective mathematical tool for the optimization of the design and the management strategy of Advanced Biofuel Supply Chains (ABSC). This work presents a MILP formulation of the economical optimization of ABSC design, comprising the definition of the associated weekly management plan. A general modeling approach is proposed with a network structure comprising two intermediate echelons (storage and conversion facilities) and accounts for train and truck freight transport. The model is declined for the case of a multi-feedstock ABSC for green methanol production tested on the Italian case study. Residual biomass feedstocks considered are woodchips from primary forestry residues, grape pomace, and exhausted olive pomace. The calculated cost of methanol is equal to 418.7 €/t with conversion facility cost accounting for 50% of the fuel cost share while transportation and storage costs for around 15%. When considering only woodchips the price of methanol increases to 433.4 €/t outlining the advantages of multi-feedstock approach
Evaluation of an integrated power plant for the city of Milan consisting of a combined cycle and a waste-to-energy system
No full textPower generation on board of a FPSO : a technical, environmental and economic comparison between open cycle gas turbines and combined cycle
No full textLAUREA MAGISTRALEL’obiettivo della tesi, condotta in collaborazione con Eni, è quello di valutare la fattibilità dell’applicazione di un ciclo combinato a bordo di una unità galleggiante di produzione, stoccaggio e scarico (FPSO) che lavora nel giacimento Agogo, in Angola.
Rispetto agli impianti attualmente più diffusi, basati su ciclo a gas semi-aperto con recupero termico dai gas di scarico della GT, il ciclo combinato permetterebbe un aumento dell’efficienza nella generazione di potenza e quindi una riduzione dell’impronta carbonica della compagnia.
Fino ad oggi, però, i cicli combinati non sono adottati in questo ambito, soprattutto a causa degli stringenti limiti riguardo a peso e dimensioni dell’impianto a bordo della nave
Lo scopo dello studio è di valutare la fattibilità attraverso i seguenti step: scelta dei principali componenti e del layout del ciclo; modellazione del ciclo combinato e del ciclo semi-aperto su Thermoflex e stima delle performances, in modo di verificare se il ciclo combinato è in grado di fornire i flussi di potenza richiesti; modellazione preliminare del layout dell’impianto di generazione di potenza (modelli 2D e 3D) e stima dei pesi, per verificare la fattibilità riguardo ai limiti di peso e dimensioni; studio della stabilità elettrica della rete per verificare la capacità di rispondere e adattarsi ad improvvisi cambiamenti di carico, generazione o altri guasti (senza l’effetto mitigante della rete elettrica, dato che questo scenario riguarda un impianto stand-alone).
Infine, l’obiettivo è stimare i costi del progetto e calcolare le emissioni di anidride carbonica e gli altri principali KPI di sostenibilità, in modo di effettuare un paragone con il ciclo a gas semi-aperto e valutare la convenienza dell’investimento.The aim of the thesis, produced in collaboration with Eni, is to assess the feasibility of the application of a combined cycle on board of a Floating Production Storage and Offloading unit (FPSO) which operates in the Agogo oil field, in Angola.
With respect to the widely diffused semi-open cycles with waste heat recovery unit, the combined cycle would allow an increase in the efficiency of power and thermal generation, thus, a reduction of the carbon footprint of the company.
However, as of today, the combined cycles have not been adopted in this environment, mainly because of the strict constraints on weight and footprint on board of the vessel.
The scope of this study is to evaluate the feasibility through the following steps: selection of the main components and the power cycle layout; modeling of the combined cycle and the semi-open cycle with Thermoflex and assessment of the performances, in order to check if the combined cycle fulfills the power duties; preliminary layout modeling (2D and 3D models) and weight assessment, to check the feasibility regarding footprint and weight constraints; transient stability analysis to check the capability of the electrical system to respond and adapt to sudden changes in load, generation or other faults (without the mitigating effect of the electrical grid, since it is a stand-alone power plant scenario).
Lastly, the purpose is to assess the cost of the project and compute the carbon dioxide emissions and the other main sustainability KPIs, in order to make a comparison with the semi-open cycle and evaluate the convenience of the investment
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
- …
