The high specific mechanical properties of fiber-reinforced polymer composites make these materials attractive for lightweight applications, and as such, composite materials are valuable tools in the design and development of sustainable technologies like wind turbine blades, tidal energy harvesting, electrical grids, and transportation systems, including electric vehicles. However, the composite industry faces challenges with regards to the sustainability of its materials and processes. Specifically, the energy input required to make carbon fibers is very high, current composite processes tend to result in high fractions (~40%) of scrap material being created, and the available options for composite materials at end-of-life are currently limited, resulting in composite materials being landfilled. Solutions for improving the sustainability of composites can potentially be found through the development of new materials and processes. This presentation will discuss recent research activities that aim to ... Read more

Flapping-wing turbines (FWTs) employ oscillating wings in place of a conventional rotor. Their wing motion is comprised of a pitch oscillation that is favourably coordinated with a simultaneous plunge oscillation – i.e. an oscillation transverse to the flow direction. This motion pattern sweeps a rectangular cross-section that is well-suited to use in shallow rivers and streams (Kinsey & Dumas 2008), thereby warranting further investigation for its potential to electrify remote communities located near small tributaries in the Amazon region. Furthermore, recent analysis suggests that the vast hydropotential of the Amazon River basin would be most economically exploited using low-head hydrokinetic devices like FWTs, which avoid the need for costly civil works (Chaudhari et al. 2021). The present talk will review the fluid-dynamic research on FWT devices, which shows that competitive efficiencies can be attained, compared to other turbine types, if the turbine geometry and kinematics are well tuned. Design guidelines from the established literature will be summarized. Opportunities ... Read more

This paper develops a novel optimization model for coaxial double-rotor blades. The optimization considers both rotors with the same diameter. Once it is based on the blade element momentum theory (BEMT), the method has low computational cost and easy implementation. It is developed by utilizing the Bernoulli principle along the streamlines that pass surrounding the blades of both rotors and the conservation laws for mass and momentum. This optimization method calculates chord and twist angle distributions of the blades for the two coaxial rotors. The aerodynamic geometries of the blades are dependent on the inflow and pressure between rotors. The total torque of double rotor is increased when compared to a single rotor turbine. This result is. .... Read more

Solar light has provided the energy for sustaining life on Earth for about three billion years. Currently, our principal energy source, fossil fuels, contains solar energy stored millions a years ago by ancient plants and microorganisms via photosynthesis. While nowadays we still have enough coal and other fossil fuels to sustain our needs for a couple of millennia, the release of carbon dioxide presents a principle treat to the human civilization the way we know it. Through the Holocene epoch, since the beginning of the Agricultural Revolution, humanity evolved on our planet with carbon dioxide atmospheric concentration staying in the range of about 260 to 290 ppm, which has ensured the weather pattern essential for flourishing of the human civilization. .... Read more

Recently we have discovered and optimized the first practical synthesis of non-fused pyrrole[3,2-b]pyrroles via domino reaction of aldehydes, primary amines, and butane-2,3-dione.1 Six bonds are formed in heretofore unknown tandem process, which gives rise to substituted pyrrole[3,2-b]pyrroles – the ‘missing link’ on the map of aromatic heterocycles. Unparalleled simplicity and versatility of this one-pot reaction, non-chromatographic purification and superb optical properties (including strong violet, blue or green fluorescence both in solution as well as in the solid state), brought these molecules from virtual non-existence to the intensively investigated area functional π-systems. The parent 1,4-dihydro-pyrrolo[3,2-b]pyrroles served as building block to construct various π-expanded analogs including nitrogen-embedded buckybowl with inverse Stone–Thrower–Wales topology2,3 and diindolo[2,3-b:2',3'-f]pyrrolo[3,2-b]pyrroles. These compounds constitute the most electron-rich ladder-type heteroacenes known to date .... Read more

Recently, several carbon allotropes with sp2 and sp3 hybridization were predicted theoretically and some are candidates to show Dirac's cones [1-3]. Here we study the eléctron and phonon properties of one of these new allotropes of two- dimensional carbon called phagraphene, consisting of rings with 5, 6 and 7 atoms (Figure 1a) [4]. This stable structure is energetically relatively close to graphene compared to other allotropes of carbon due to its sp2 hybridization and dense atomic packing. The existence of a Dirac cone distorted in the first Brillouin zone of this structure was shown by both density functional theory (DFT) and tight-binding calculations [4]. Our investigations are based on DFT as implemented in SIESTA [5]. Electron and phonon band structures (Figure 1b,c) and density of states are computed with .... Read more