1,720,966 research outputs found
Life Cycle Assessment (LCA) of MWool® Recycled Wool Fibers
Full text linkTextile industries are in the spotlight due to the heavy environmental impacts along their products’ life cycle and, at the same time, they are a priority sector in the new circular economy action plan of the European Commission. In this framework, the Italian company Manteco SpA has developed a value chain based on the recycling of pre-and post-consumer discarded textiles, wh0se output is a secondary wool fiber named MWool® . This study develops an environmental analysis of recycled wool fibers through the Life Cycle Assessment (LCA) methodology, mainly using primary data. A parallel LCA is developed of virgin wool fiber, mostly based on literature data. Sensitivity analyses have been carried out: (i) to capture the uncertainty associated with virgin fibers’ impacts and (ii) to evaluate how MWool® impacts vary according to the origin and treatment of recycled textiles. Finally, the Circular Footprint Formula (CFF) has been applied to consider also a possible decay in quality typically affecting recycled fibers. Results show that recycled wool fibers have significantly lower environmental impacts than virgin fibers, even when the most unfavorable scenarios are considered. As climate change is concerned, 1 kg of MWool® has a carbon footprint of 0.1–0.9 kg CO2 eq., while producing virgin fibers releases 10–103 kg CO2 eq. Using the CFF, it emerges that recycled wool fibers can save about 60% of the impacts of virgin fibers. This study contributes to filling data gaps regarding LCAs applied to the textile sector, which is more and more in the spotlight and needs to address these environmental issues
Modelling of a supersonic accidental release in Oil&Gas offshore: Characterisation of a source box
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Wind Impact Assessment of a Sour Gas Release in an Offshore Platform
Full text linkComplex installations that involve dangerous substances, such as oil and gas or nuclear plants, must mandatorily undergo a quantitative risk assessment (QRA) according to current regulations. This requires, among others, the simulation of hundreds of accidental scenarios, which are typically carried out using empirical tools due to their fast response. Nonetheless, since they are not able to guarantee sufficient accuracy, especially when complex geometries are involved, computational fluid dynamics (CFD) tools are increasingly used. In this work, a high-pressure accidental release of a sour gas (CH4-H2S) in an offshore platform under several wind conditions is considered. A methodology used to perform a wind sensitivity analysis via CFD, while avoiding high computational costs, is presented. The wind intensity impact on some risk-related figures of merit, such as the high lethality or irreversible injuries areas, is discussed in relation to the flammability and toxicity limits of the released mixture. The results show that even a very low amount of H2S in the released mixture can strongly affect the threat zones. A progressive decrease in the toxic and flammable volumes in the platform is observed as the wind velocity increases; nonetheless, a saturation effect appears in high wind speed scenarios
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
Life Cycle Assessment for the ISWEC Wave Energy Device
No full textIn recent years, wave renewable energy is becoming established as one of the crucial components of a diversified and successful energy mix. The Inertial Sea Wave Energy Converter (ISWEC) is a mature technology, especially designed for closed seas, as the Mediterranean Sea, which has already been deployed in full-scale. At this stage of development, since the technology has been proven successful, it is crucial to assess its environmental impact. A life cycle assessment has been performed on the ISWEC including all relevant phases, from raw material extraction, to construction, assembly, transportation, use and final dismantling. As an outcome, the LCA study allowed the calculation of a set of impacts on the environment, resources depletion and human health that allows the innovative renewable energy-based technology to be consistently compared with other solutions. One of the most popular impacts, such as climate change, has been estimated at 31.5 gCO2eq/kWh which is in line e.g. with the performance of photovoltaics
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
Scaling procedure for the design of a validation experiment on an accidental gas release
No full textOil&Gas platforms are complex structures characterized by the presence of flammable and pressurized fluids and by a unique working environment, with limited spaces and congested presence of processing equipment. Risk assessment on these structures is mandatory according to international directives and it involves the evaluation of frequencies and consequences of possible accidental scenarios. The Italian Ministry of Economic Development is supporting the SEADOG (Safety and Environmental Analysis Division for Oil&Gas) laboratory at Politecnico di Torino to develop research projects on Oil&Gas offshore safety. At SEADOG, we have developed an innovative CFD hybrid approach to simulate the consequences of accidental gas releases. This approach simulates two separate and consequent steps that happen in an accidental gas jet release: the first one is the initial supersonic behavior modeled into a portion of the total platform domain; the second step is the following subsonic dispersion of the released gas into the total domain. The supersonic characteristics appear within the first tens of centimeters from the release point, where the compressibility effects drive the phenomena evolution. The subsonic dispersion domain may corresponds to entire platform (tens of meters), where the fluid can be treated as incompressible. The two steps are computationally evaluated and optimized separately, while the coupling follows. A key boundary condition for the phenomenon simulation is the wind speed. This real scale speed has to be defined according with the typical velocity distribution of the atmospheric wind present in the location (Adriatic Sea) where the platform is positioned. To validate this theoretical approach, a physical experiment is designed for the investigation in a wind tunnel of a scaled (1:10) mockup of a real platform will be equipped with a gas release supply line and a sensors’ network. While the mock up is scaled according to a geometric ratio, a finer assessment is needed to apply the correct scaling approach to define the reference speed in the wind tunnel and the mass flow release. The scaling of the wind velocity has followed the scaling theory for wind tunnels, respecting the logarithmic evolution of the wind profile in proximity to the sea surface. The scaling of the mass flow release is inspired by the approach proposed by Hall and Walker (1997) with some adjustments to fit our specific case. In particular, a dimensionless group is chosen to link pressure release, nozzle diameter, scaling factor and gas properties: the dimensionless discharge momentum flux. Furthermore, this group contains information about both the real and the scaled wind velocity. The approach proposed in this paper aims at scaling supersonic jet releases, maintaining their critical behavior for the test. A selection of case studies will be tested in the experimental setup to be built by the end of year 2019 under the supervision of the SEADOG research team
Definition of a Basic Design for Conversion of an Offshore Fixed Platform on a Depleted Reservoir Into a Sustainable Plant
Full text linkIn the framework of energy transition, a focus is given to the study of the conversion of offshore Oil&Gas (O&G) platforms at the end of their life due to the depletion of the reservoirs on which they operate. Their modular and versatile structure allows the implementation of new processes and innovative sustainable technologies for reducing the environmental impact of a complete decommissioning, especially on the subsea ecosystem that has grown around the jacket, and for guaranteeing cost-saving solutions. Among different conversion options, this paper focuses on the installation on the platform of a system for the production of photovoltaic (PV) energy to be used for seawater desalination and its delivery to other platforms operating in the same area. The project focuses on the definition of technical characteristics of the basic design, on the investigation of the technical feasibility of the conversion process, and on qualitative safety and environmental impact studies. Moreover, the old platform equipment to be decommissioned (i.e., the equipment necessary for hydrocarbons treatment) are identified, and the installation of new equipment is optimized, e.g., the number of PV panels and, therefore, the installed power are maximized. At the same time, decommissioning costs and impacts can be minimized. The basic design is completed with a preliminary structural verification to guarantee that critical situations do not rise, with an indication on the main maintenance activities for the preservation of plant good efficiency and with safety and environmental preliminary analyses for the identification of potential criticalities to be managed at different design levels
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