The Equivalence Between Unit-Cell Twinning and Tiling in Icosahedral Quasicrystals

It is shown that tiling in icosahedral quasicrystals can also be properly described by cyclic twinning at the unit cell level. The twinning operation is applied on the primitive prolate golden rhombohedra, which can be considered a result of a distorted face-centered cubic parent structure. The shape of the rhombohedra is determined by an exact space filling, resembling the forbidden five-fold rotational symmetry. Stacking of clusters, formed around multiply twinned rhombic hexecontahedra, keeps the rhombohedra of adjacent clusters in discrete relationships. Thus periodicities, interrelated as members of a Fibonacci series, are formed. The intergrown twins form no obvious twin boundaries and fill the space in combination with the oblate golden rhombohedra, formed between clusters in contact. Simulated diffraction patterns of the multiply twinned rhombohedra and the Fourier transform of an extended model structure are in full accord with the experimental diffraction patterns and can be indexed by means of three-dimensional crystallography

Description and preliminary calibration results for the Langley hypersonic CF4 tunnel

A detailed description of the hypersonic CF4 tunnel is presented along with discussion of the basic components, instrumentation, and operating procedure. Operational experience with the CF4 reclaimer and lead-bath heater is discussed. Comparison of measured and predicted shock detachment distance on a sphere and pressure distributions measured on a sharp leading-edge flat plate revealed the absence of significant flow nonuniformity and lent creditability to predicted free stream flow conditions. The economic operation of this facility centers about the CF4 reclaimer, which was designed to operate at an efficiency of 90 to 95 percent. A number of modifications were made to the reclaimer system to improve its performance, and presently, the system reclaims approximately 75 percent of the test gas. Even with current budgetary constraints, this efficiency permits the CF4 tunnel to be operated as a viable research wind tunnel

A History and Definition of Green Roof Technology with Recommendations for Future Research

Green roof technology has a history that predates the modern era. Many functions of green roofs utilized during human history are analogous to contemporary functions. The justification of the use of green roof technology based on a review of literature shows the multiple and documented benefits that these systems can impart to the urban environment. A case study of the installation of the Southern Illinois University Carbondale green roof, showed the actual process of constructing the system. The maintenance and observation of this system gives firsthand experience. Interviews with green roof professionals allow greater understanding of current research needs. Finally, from these resources, recommendations for future research can be identified. This could ensure cogent direction in future research

Human emotional response to energy visualisations

This is the post-print version of the final paper published in International Journal of Industrial Ergonomics. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2012 Elsevier B.V.Past research has found that frequent energy usage feedback is an important factor in reducing home energy consumption, and that the sensory appeal and cognitive relevance of the feedback are key components of user engagement with energy systems. The visual design of the information interface is important not just due to its role in communicating data of cognitive relevance, but also because the choice of information type and format is important towards achieving interactive Hebbian learning. The objective of the current research study was to investigate the possible effect of image format on the human emotional response to scenes of energy systems, and to evaluate whether any gender related differences in emotional response occurred. An automated PC-based test was developed which utilised five visual image formats (Optical Gray-Scale, Optical Coloured, Optical Augmented, Infrared Gray-Scale and Infrared Blue-Red) and nine home energy scenes (hot water boiler, radiator, water faucet, kitchen oven, tea kettle, toaster, electrical connector, laptop computer and tea mug). The emotional response of the participant was measured in the automated test by means of a Self-Assessment Manikin (SAM) which provided symbolic graphical representations of the human body under various degrees of emotional response, and associated Likert format rating scales for the valence and activation level of the emotional response. Comparison of the results obtained for the different visual scenes suggests that the greatest level of human emotional activation was achieved by the Infrared Blue-Red (thermal image) format, and that, generally, coloured images provided higher levels of emotional activation than gray-scale images. The increased activation achieved by the infrared images suggests attention capturing potential due to novelty, or due to the direct link to heat and energy, or both. Significant differences in emotional response (both activation and valence) were found to occur as a function of gender. The current results provide first guidance which a designer can use when choosing image spectrum and colours to represent energy systems on the displays of thermostats, smart meters and the energy devices. Relevance to industry - The current results provide first guidance which a designer can use when choosing image spectrum and colours to represent energy systems on the displays of thermostats, smart meters and the energy devices. Such design guidance is currently lacking internationally but is of increasing importance due to the expansion of digital devices, internet services and the upcoming internet-of-things

Hydrogenation Properties of the TiBx Structures

Titanium borates show promissing hydrogen storage characteristics. Structural relaxation around individual hydrogen atoms and the binding energies are studied by means of the density functional theory methods for a number of hydrogenated TiB2, TiB and Ti2B structures. Starting with the possible symmetric hydrogen sites a random structure searching has been performed, in addition to locate all energetically stable adsorption sites. It is shown that for the three bulk compounds considered, the lowest binding energies are obtained for TiB2 (in the 0.3-1.8 eV range), the largest for Ti2B (in the 3.9-4.7 eV range), while for TiB they are intermediate (in the 2.8-3.5 eV range). Calculations performed on hydrogenated Ti2B result in two energetically stable sites for two different starting environments, suggesting a posible soft mode solution