Three dimensional photonic crystals

ABSTRACT The plane wave expansion method was implemented in modelling and simulating the band structures of three dimensional photonic crystals with FCC lattice formed from air spheres drilled in GaAs and diamond lattice formed by GaAs spheres drilled in air. Both these structures lead to a complete band gap not allowing EM waves with the frequency of the band gap to propagate through the crystal in any direction. Diamond lattice photonic crystal has a complete band gap for a wider range of filling fraction than FCC photonic crystal and also it has a wider band gap width

Orchestration of renewable generation in low energy buildings and districts using energy storage and load shaping

There is increasing penetration of renewable generation in buildings and districts. There are challenges in making the effective use of this generation. The objective of the ORIGIN project (Orchestration of Renewable Integrated Generation In Neighborhoods) is to shape loads so that the fraction of energy consumed that is from local renewable generation is maximized, and energy imported from outside sources is minimized. This paper presents the overall approach taken in the ORIGIN project and explores building physics aspects of solar thermal storage system orchestration. The case study districts are briefly introduced and characteristics of their generation, buildings, districts and shiftable loads described. The orchestration approach taken in ORIGIN is then presented. At the core of the ORIGIN system is the orchestration algorithm which generates informational and control outputs to shape future loads to best meet the objectives. The model based approach used to quantify thermal and electrical load shifting opportunities for pre-charging, coasting or avoiding loads, while meeting thermal comfort and other demands, is described using a solar thermal storage system as an example. The future steps for the ORIGIN project; retrofit of the ORIGIN system into existing districts and potential for other future applications is briefly discussed

Creativity Bento Box: a physical resource pack to support interaction in virtual space

The Creativity Bento Box is a physical resource pack, designed to support casual social interaction and break taking in an intensive, computer-mediated social activity. It was developed within the Creativity Greenhouse project, which piloted a mechanism to create research proposals and distribute funding at a distance. This involved facilitated phases of collaboration and competition over multiple days of computer-mediated work, where participants communicate and interact through a virtual world. During the iterative development process, the lack of time for socialising, the intense focus on virtual resources, and a lack of time spent away from the screen were reported as negative issues in feedback from participants. We report on the development of the Creativity Bento Box and how it helped to address these issues. By providing physical resources that contrasted with the properties of the virtual world, it supported people to socialise and take breaks from their primary activity, allowed them to include physical space and artefacts in their interactions, and provoked moves away from the otherwise intense focus on the computer. We reflect on the roles of the Bento Box as a gift, in bridging between physical and virtual contexts, its higher suitability during the earlier phases of ideation and group development, and its perception by participants as something ‘framed’. Through this, we highlight the underexplored potential of using physical, offline resources as a means to solve difficulties in distanced social interactions

Incommensurate two-dimensional checkerboard charge density wave in the low dimensional superconductor Ta4Pd3Te16

We report the observation of a two-dimensional (2D) checkerboard charge density wave (CDW) in the low-dimensional superconductor Ta4Pd3Te16. By determining its CDW properties across the temperature-pressure (T-P) phase diagram and comparing with prototypical CDW materials, we conclude that Ta4Pd3Te16 features: a) an incommensurate CDW with a mixed character of dimensions (Q1D considering its needle-like shape along the b-axis, Q2D as the CDW has checkerboard wavevectors, and 3D because of CDW projections along all three axes); and b) one of the weakest CDWs compared to its superconductivity (SC), i.e. enhanced SC with respect to CDW, suggesting an interesting interplay of the two orders.Comment: Z.S. and S.J.K. contributed equally to this work / Accepted for publication in Physical Review Research Rapid Communication

Memories of childhood in post-war Grimsby

This paper details the vivid memories of the author’s childhood in the fishing port of Grimsby, shortly after the Second World War. It was a time of shortages, overcrowding, improvisation and cannibalisation of anything that could be re-used. In time it became a period of reconstruction but not without its upheavals and difficulties. It begins in the ‘old town’ of workers’ small terrace houses, typically in a poor state of repair. Then it moves to the ‘new’ council estates. Similarly, the narrative also begins with a ‘Victorian’ technology of steam, coal and horses with very few petrol-engined vehicles and moves to the very beginnings of early consumer society. The principal analytic content of the paper concerns the status of what is clearly a ‘personal history’ – if that is not too great a contradiction – or as the author suggests: my story. The obvious ‘critical’ response – that it could have been otherwise – is contrasted against the suggestion that this story is a non-negotiable foundation of the author’s identity and that this ‘critical’ response is not appropriate. Some of the interdisciplinary options thrown up by this problem are considered

Monte-Carlo simulations of the recombination dynamics in porous silicon

A simple lattice model describing the recombination dynamics in visible light emitting porous Silicon is presented. In the model, each occupied lattice site represents a Si crystal of nanometer size. The disordered structure of porous Silicon is modeled by modified random percolation networks in two and three dimensions. Both correlated (excitons) and uncorrelated electron-hole pairs have been studied. Radiative and non-radiative processes as well as hopping between nearest neighbor occupied sites are taken into account. By means of extensive Monte-Carlo simulations, we show that the recombination dynamics in porous Silicon is due to a dispersive diffusion of excitons in a disordered arrangement of interconnected Si quantum dots. The simulated luminescence decay for the excitons shows a stretched exponential lineshape while for uncorrelated electron-hole pairs a power law decay is suggested. Our results successfully account for the recombination dynamics recently observed in the experiments. The present model is a prototype for a larger class of models describing diffusion of particles in a complex disordered system.Comment: 33 pages, RevTeX, 19 figures available on request to [email protected]