Scipedia
Not a member yet
33380 research outputs found
Sort by
Thermochemical recycling of epoxy matrix composite materials with Diels-Alder bonds
No full textThe high cross-linking degree of thermosetting resins, which gives them remarkable mechanical properties, also implies an irreversible structure that impedes proper recycling at the end of life. This problem influences both thermosetting matrices and composite materials, since the crosslink irreversibility of the matrix hinders the recovery of the fibers. One way to solve this problem is the development of new thermosetting resins that incorporate Diels-Alder thermo-reversible bonds. The introduction of Diels-Alder bonds allows thermosets to have a polymeric network capable of disengaging at temperatures above 90 °C, acquiring certain fluidity and recyclability. However, its composition and curing cycle must be carefully adjusted to avoid undesired chemical reactions and to maintain certain mechanical properties, since the addition of Diels-Alder bonds in high contents usually results in a notable embrittlement of resin. In the present work, the manufacture of an epoxy matrix composite material with 60% Diels-Alder bonds reinforced with carbon fiber is developed, which shows mechanical properties similar to those of a conventional epoxy resin laminate. After that, the recovery of the fiber is addressed thermochemically by dissolving the matrix in dimethyl sulfoxide at 150 °C, achieving the reuse of the fiber to manufacture new composite materials with mechanical properties comparable to the original
Validation of a laboratory-scale technology for complete recycling of wind turbine blades
No full textThis paper presents the experimental validation of a thermal treatment technology to recover added-value substances from the plastic matrix of end-of-life wind turbine blades, when these are subjected to a pyrolysis process to recover the glass fibres. The experiments have been carried out in a laboratory installation consisting of two reactors in series, in which pyrolysis and thermal treatment of pyrolysis gases and vapours take place, respectively. The application of this treatment enables a 25 wt.% reduction in the production of pyrolysis liquids, increasing the production of gases in an equivalent way and without compromising the pyrolysis conditions to be used to recover the glass fibres. The two-phase liquids are converted into single-phase aqueous ones, while the hydrogen concentration in the gases increases from 4 % to almost 50 % in volume. This high concentration of hydrogen in the gases allows them to be used as a source of hydrogen for various applications. Consequently, the technology demonstrates that the plastic matrix of wind turbine blades can be valorised in a pyrolysis based recycling process
Structural and Seismic Design of a Steel Staircase using FEM in compliance with Italian Legislation
Get PDFStructural analysis is conducted by the displacement method for evaluation of the stress-strain state induced by static loads. The analysis is conducted by the modal analysis and acceleration response spectrum method for the evaluation of the stress-strain state induced by dynamic loads (including seismic loads).
Structural analysis is carried out using the finite element method. The above method is based on the schematization of the structure into elements connected only at a set number of points called nodes. The nodes are defined by the three Cartesian coordinates in a global reference system. The unknowns of the problem (within the displacement method) are the displacement components of the nodes referred to the global reference system (translations according to X, Y, Z, rotations around X, Y, Z). The solution of the problem is obtained by a system of linear algebraic equations whose known terms consist of the loads acting on the structure appropriately concentrated at the nodes
Construction Project Management and Green Building
No full text'''This thesis studied the definition of a green building and the elements associated with the construction of sustainability. There are many rating systems available across the country both private and public. The most well-known is the LEED rating system developed by the United States Green Building Council. LEED has several rating programs now available. In this thesis, I will discuss why Green Building is more significant than conventional building and methods of Green Building like construction Phases. Conventional buildings produce high amounts of greenhouse gas, a large quantity of construction and demolition debris (which decrease landfill capacity), disturb natural resources, and consume much energy and water. Implementation of various simple and sustainable techniques practiced individually can help in many ways to create an environmentally friendly structure, consume minimal natural resources and at the same time be economical. This paper tries to study the Green Building construction method and innovative technologies that enable us to create a sustainable structure. It also includes design concepts of Green Building, methodology and materials requirements, and ideas and suggestions to create a checklist for a builder to refer to the various suggestions in every phase of construction of a general structure. '''Key Words: '''Green Building, Construction of Sustainability, LEED, Minimal Natural Resources, and Sustainable Structure
The effect of particle properties on binary mixture segregation during blast furnace charging
Get PDFSegregation is likely to occur during blast furnace charging since the iron ore mixture contains particles differing simultaneously in size, shape and density. However, predicting how the mixture components will be distributed is particularly difficult due to the combined effect of these differences. Although the Discrete Element Method has been used extensively to gain understanding of segregation during blast furnace charging, most research has focused on simple mixtures in which particles differ only in size. In this work, we investigate how size, shape and density differences simultaneously affect mixture segregation in radial and vertical directions of a charged layer using the response surface methodology. We found that size and density difference between the mixture components significantly affect both radial and vertical segregation while shape differences, especially the aspect ratio, are relatively less important
Anàlisi de les exportacions de béns catalanes i la seva complexitat econòmica
No full textAnàlisi de les exportacions de béns catalanes i la seva complexitat econòmica: Abstract pel "IV Congrés d’Economia i Empresa: Eix 2. Determinants del context macroeconòmic"
Helena Linares-Arlanzón1 i Maximilian Schäfer-i-Paradís1
1Generalitat de Catalunya, Departament d'Economia i Hisenda, Direcció General d'Anàlisi i Prospectiva Econòmica, Carrer del Foc, 57 08038 Barcelona
Catalunya gaudeix d’una base industrial i d’una orientació exportadora destacable, que la situen com la primera comunitat autònoma en volum d’exportacions de béns, amb el 26,3% del total estatal el 2023. Aquest treball analitza l'evolució de les exportacions de béns de Catalunya i les seves províncies (i.e., Barcelona, Girona, Lleida i Tarragona) des de dues perspectives. D'una banda, s'explora la seva evolució històrica, destacant els components clau i els trets distintius de l'estructura exportadora catalana. D'altra banda, es du a terme una anàlisi de la complexitat econòmica i l'avantatge competitiu de les exportacions, oferint una visió integral del panorama exportador del territori.
Per tal d'analitzar la competitivitat sectorial, s'ha calculat l'índex d'avantatge comparatiu revelat (RCA, per les seves sigles en anglès) que mesura el grau d'especialització en les exportacions d'un producte (Balassa, 1963) Com a mesura de qualitat de les exportacions, hem utilitzat l'índex de complexitat econòmica (ICE), definit per Hidalgo i Hausmann (2009), que calcula el coneixement acumulat d'un territori per tal d'exportar productes que són escassos en el mercat internacional. Un nivell d'ICE alt es relaciona així amb un desenvolupament econòmic pronunciat i, tanmateix, amb una capacitat exportadora futura més elevada. Els indicadors de complexitat de l'economia catalana s'han basat en les dades proporcionades per COTEC.
Els resultats indiquen una disminució de la complexitat econòmica en les exportacions de béns de Catalunya entre el 2017 i el 2022. Tot i això, en els darrers 2 anys s’observa una millora de l’ICE de Catalunya que ha permès tornar a situar a la regió en la tercera posició del rànquing autonòmic, gràcies sobretot a l’evolució favorable dels productes químics i del material de transport. En termes més desagregats, Barcelona és la quarta província de l’Estat amb major nivell de complexitat el 2022, mentre que la resta de províncies catalanes mostren una sofisticació negativa (Girona, Tarragona i Lleida, se situen a la posició 12, 25 i 34, respectivament).
Pel que fa a l’avantatge competitiu, dels productes analitzats per Catalunya el 2022, gairebé un 52% mostren un valor competitiu de l'RCA (i.e., RCA superior a 1), on destaquen els productes animals i els químics. No obstant això, d’aquests productes especialitzats, menys del 10% tenen una complexitat del producte (PCI) positiva.
Finalment, s’aplica un model economètric (vegi's l'Equació (1)) per inferir l’impacte del nivell de l'ICE sobre el valor total de les exportacions catalanes del 2022. S’observa un efecte positiu i estadísticament significatiu. De fet, la magnitud de l'efecte és superior al d'altres variables clau (e.g., l’RCA, el nivell de les infraestructures de transport i la mida del teixit empresarial provincial).
ln(exp_iz/PIB_z) = alpha + beta ln(ICE_z) + gamma ln(RCA_iz) + theta ln(X_z) + xi_iz (1)
Fig. 1. Evolució de la complexitat de les exportacions catalanes (2017-2022). Nota: La mida dels punts augmenta segons el valor RCA de cada producte.
Taula 1. Regressions OLS.
Bibliografia
Balassa, Bela. An empirical demonstration of classical comparative cost theory, The Review of Economics and Statistics (1963): 231-238.
Hidalgo, Cesar A., and Ricardo Hausmann, The building blocks of economic complexity, Proceedings of the national academy of sciences (2009): 10570-10575