1,720,981 research outputs found
A fast simulation method for the probabilistic assessment of emissions in cruise ship's itinerary planning
Full text linkThis study employs a probabilistic methodology to forecast cruise ship emissions during the itinerary planning phase, considering environmental factors (current, waves, wind), fouling, shallow water, loading conditions, and Fresh Water (FW) production effects. Probability distributions of environmental parameters are established based on statistical data and utilized for generating deterministic scenarios through Monte Carlo sampling. The resulting scenarios are simulated to define probability distributions for carbon dioxide emissions, carbon intensity indicators, and other pertinent quantities. The simulation model is validated using data from an existing ship. To demonstrate the effectiveness of the proposed methodology in strategic itinerary planning, multiple alternatives for an existing itinerary are simulated. Specifically, a Mediterranean cruise is simulated in both the original sequence and in reverse, with and without FW production. The reverse sequence without FW production demonstrates a potential reduction of approximately 190 tCO2e/week emissions. Furthermore, in this scenario, a comparison is made between a standard Power Management System (PMS) with an equal load on all engines and an optimized PMS with optimized engine loads, resulting in an additional average reduction of 86 tCO2e. In the latter itinerary, the most probable rating according to Carbon Intensity Indicator is reduced from original E to C
Refitting a Cruise Ship with More Electric Power & Energy Systems: A Methodology to Evaluate the Impact on Fuel Efficiency
No full textIn today's tourism landscape, cruise ships play a crucial role in the recreational maritime transport market. However, the sector is facing a crucial challenge in finding novel solutions to limit their environmental impact. While new ships can be easily designed and built considering modern environmentally friendly solutions, there still remain a huge number of vessels that are still far from the end of their useful life, which may benefit from modern technologies' introduction during mid-life refitting operations. However, spending effort on refitting a ship to improve its fuel efficiency may be futile if the resulting impact is not capable of repaying itself in terms of reduced operating costs. In this context, cruise ships are endowed with a full-electric architecture, which eases electrification and introduction of energy storage systems. Thus, in this paper, a methodology is proposed to evaluate the impact on fuel efficiency of refitting a cruise ship with more electric power & energy systems. A case study is proposed, taking an old-fashioned cruise ship, and introducing energy storage systems and frequency converters for chillers' high power induction motors. The results provide useful insights on the opportunity of applying such modern technologies to ships that have not been designed taking them into account
A Hybrid-Electric Passenger Vessel for Inland Waterway
Full text linkThe problem of air pollution is one of the biggest issues discussed worldwide: due to this reason, various measures to reduce global pollution, especially CO2 emissions, are being taken by Governments. One of the main causes of pollution is represented by the transport sector, which includes also maritime transport. Therefore, it is necessary to study and find new types of propulsion that ensure a reduction of pollutant emissions. A way to achieve this aim is represented by hybrid-electric propulsion systems, capable of ensuring a good range in ZEM - Zero Emission Mode - navigation. In this paper, the application of hybrid-electric propulsion on a small boat for passenger transport in inland waters has been analysed. Based on the results of preliminary studies, a prototype of the vessel was built; the boat has been a useful and remarkable test bench to validate such a technology, in terms of eco-friendliness, energy efficiency, and reliability. Here, the theoretical estimates carried out in the early stage of design have been compared with the experimental data obtained on the prototype during a sea trials campaign carried out in a real operative environment
Updated Steel Weight Estimation for Cruise Ship Concept Design
No full textEstimating the steel weight of ships during the early conceptual stages is of the utmost importance since it represents about 50% of the lightship weight of the ship. From a technical standpoint, it significantly affects cargo capacity, design speed, stability, and ship safety, thus requiring an accurate estimation. The steel weight is usually evaluated using simple empirical formulations during the concept design, mainly based on the ship's main particulars. Those formulas are derived by statistical analysis of past projects and can be applied only for the specific ship type (or types) included in the considered database. In the literature, many formulas are present mainly related to cargo ships. Currently, no empirical formulation is available for cruise ships that are applicable in the very early conceptual stages. The present study aims to identify an empirical formulation for estimating the steel weight of a luxury cruise ship based on calibrating a set of existing empirical formulas
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
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