Levelised cost of energy: a theoretical justification and critical assessment.

Although widely accepted as a measure of the comparative lifetime costs of electricity generation alternatives, levelised cost of energy (LCOE) lacks a theoretical foundation in the academic literature and encompasses a number of areas where caution is important. Therefore, this paper seeks to provide a theoretical foundation by comparing the metric with alternative LCOE metrics and by undertaking a brief literature review to describe its strengths and weaknesses. In comparison with other potential measures of unit cost of energy, LCOE is found to be the preferred choice, in large part because of its widespread adoption. The weaknesses of the LCOE are found to centre on discount rate, inflation effects and the sensitivity of results to uncertainty in future commodity costs. These weaknesses are explored in the context of comparing combined cycle gas fired generation and offshore wind in the UK, based on publicly available cost measures. It is found that with variability of future fuel gas prices, and a Monte Carlo approach to modelling LCOE, the range of LCOE for CCGT is much broader in comparison to the LCOE of offshore wind. It is urged that explicit account be taken of the areas of weakness in future use of LCOE

Nonlinear Breathing-like Localized Modes in C60 Nanocrystals

We study the dynamics of nanocrystals composed of C60 fullerene molecules. We demonstrate that such structures can support long-lived strongly localized nonlinear oscillatory modes, which resemble discrete breathers in simple lattices. We reveal that at room temperatures the lifetime of such nonlinear localized modes may exceed tens of picoseconds; this suggests that C60 nanoclusters should demonstrate anomalously slow thermal relaxation when the temperature gradient decays in accord to a power law, thus violating the Cattaneo-Vernotte law of thermal conductivity.Comment: 6 pages, 6 figure

Discapacidad visual y orientación urbana. Estudio piloto sobre planos táctiles producidos en Impresión 3D

[EN] This article presents a pilot study conducted in Barcelona with blind and visually-impaired people. The aim was to analyze the use and efficacy of tactile maps produced by means of 3D printing. For this purpose, structured interviews were used, along with direct observation, the creation of cognitive maps and tasks with prototypes. The aim has been to examine the instrumental and communicative value of these products in terms of interpreting, memorizing and understanding a certain urban route, comparing this with experience in situ, focusing on the difficulties faced by the visually disabled when visiting new places. Findings show the utility of this type of technique in aiding visually disabled users to memorize routes. As a limitation, this study shows that tactile maps are not wholly efficient since they require verbal support, which makes it hard for them to be used autonomously.[ES] El trabajo aquí expuesto presenta un estudio piloto llevado a cabo en Barcelona con personas invidentes y deficientes visuales. El objetivo del mismo ha sido analizar el uso y la eficacia de los planos táctiles producidos mediante Impresión en 3D. Para ello se han empleado entrevistas estructuradas, observación directa, realización de mapas cognitivos y tareas con prototipos. De esta manera se ha tratado deprofundizar en elvalor instrumentalycomunicativo de estosproductos a la hora de interpretar, memorizar y comprender un determinado recorrido urbano, contrastándolo con la experiencia in situ, atendiendo a las dificultades que este tipo de personas presentan a la hora de visitar nuevos lugares. Los resultados obtenidos demuestran la utilidad de este tipo de técnica para memorizar recorridos por parte de este tipo de usuarios. Como limitación, el estudio muestra que los planos táctiles no resultan del todo eficientes pues precisan de apoyo verbal, hecho que dificulta su uso autónomo.This research has been funded by the Spanish Ministry of Science and Innovation as part of the National Fundamental Research Programme, the National R&D/Innovation Plan, within the project “Study and design of orientation elements, communication support and other accessories to improve accessibility in different spheres of interpreting natural and/or built heritage’ (DPI2008-03981/DPI). The authors would also like particularly to thank the following for their selfless collaboration: the ONCE Educational Resources Centre in Barcelona and staff from the Disabled Service Programme at the Universitat Politècnica de Catalunya. The study was also carried out as part of the Research Staff Mobility Programme at Universitat Jaume I (E-2010-32) funded by the Caixa Castelló-Bancaixa Foundation.Gual Ortí, J.; Puyuelo Cazorla, M.; Lloveras, J.; Merino Sanjuan, L. (2012). Visual Impairment and urban orientation. Pilot study with tactile maps produced through 3D Printing. Psyecology. 3(2):239-250. https://doi.org/10.1174/217119712800337747S2392503

Theory of coherent phonons in carbon nanotubes and graphene nanoribbons

We survey our recent theoretical studies on the generation and detection of coherent radial breathing mode (RBM) phonons in single-walled carbon nanotubes and coherent radial breathing like mode (RBLM) phonons in graphene nanoribbons. We present a microscopic theory for the electronic states, phonon modes, optical matrix elements and electronﾖphonon interaction matrix elements that allows us to calculate the coherent phonon spectrum. An extended tight-binding (ETB) model has been used for the electronic structure and a valence force field (VFF) model has been used for the phonon modes. The coherent phonon amplitudes satisfy a driven oscillator equation with the driving term depending on the photoexcited carrier density. We discuss the dependence of the coherent phonon spectrum on the nanotube chirality and type, and also on the graphene nanoribbon mod number and class (armchair versus zigzag). We compare these results with a simpler effective mass theory where reasonable agreement with the main features of the coherent phonon spectrum is found. In particular, the effective mass theory helps us to understand the initial phase of the coherent phonon oscillations for a given nanotube chirality and type. We compare these results to two different experiments for nanotubes: (i) micelle suspended tubes and (ii) aligned nanotube films. In the case of graphene nanoribbons, there are no experimental observations to date. We also discuss, based on the evaluation of the electronﾖphonon interaction matrix elements, the initial phase of the coherent phonon amplitude and its dependence on the chirality and type. Finally, we discuss previously unpublished results for coherent phonon amplitudes in zigzag nanoribbons obtained using an effective mass theory

Strategies for ideal indoor environments towards low/zero carbon buildings through a biomimetic approach

Biomimicry is a relatively new discipline of applied science that seeks inspiration from natural systems for innovative solutions to human problems. Taking nature as ‘model, mentor and measure’ receives wide acceptance in the field of architecture but predominantly in conceptualising novel forms. The biomimicry concept is comprehensively analysed for its ability to provide more sustainable and possibly even regenerative built environments. As part of this study, first, various frameworks for approaching ‘biomimicry’ in general are discussed and then relevant examples pertaining to architecture are evaluated. Case studies are critiqued with respect to varied levels of sustainability achieved and its causative factors. In the second part, an approach model for ‘biomimetic architecture’ in the context of Mumbai is presented and applicable strategies based on climatic adaptation are suggested using local biodiversity as a library of organisms. The generic example of ‘human skin’ addressing the same adaptation is analysed and complemented by a state-of-the-art case study on similar lines. The results achieved clearly reveal that biomimicry is a successful approach to design and operate the sustainable built environments for the buildings of the future