20,218 research outputs found

    Crazy ideas or creative probes?: presenting critical artefacts to stakeholders to develop innovative product ideas

    Get PDF
    A number of design practices derive from and develop the notion of critical theory. Notable developers of such “critical design practices” are Dunne &amp; Raby with “critical design”, Sengers and colleagues at Cornell University's Culturally Embedded Computing Group with “reflective design”, and Agre with “critical technical practice” within artificial intelligence research. And there are an increasing number of designers who, whilst not specifically explicating their theoretical ancestry, include critical elements in their products. The reflection afforded by the products of critical design is generally seen as its endpoint. However I have used this reflection instrumentally within human-centred design activities. “Critical artefacts” have proved more useful as tools than direct questioning techniques; in particular as a way of enabling stakeholders to engage with novel situations and consequently engage in creative thinking about future possibilities. This paper begins with a review of critical design practices. Two case studies are then detailed demonstrating my approach. A discussion of the commonalities and differences between critical design practices follows noting their relationship to critical social theory and the relationship of my work to them. Finally further research to develop generalisable methods is outlined.</p

    The series spectra of the stripped boron atom (BIII)

    Get PDF
    In a preceding article [1], we have brought forward evidence that in "hot spark" spectra the strongest lines generally correspond to atoms from which the valence electrons have all been stripped off, so that the resulting spectrum is hydrogen-like, i.e., is due to one single electron moving between the series of levels characteristic of a simple nucleus-electron system. For such a nucleus-electron system the Bohr theory in its elementary form [2] which dealt only with circular orbits, i.e., with variations in azimuthal quantum numbers, the radial being always zero, yielded at once the result that the energies corresponding to a given quantum state, e.g., quantum number 1, increased in the ratio 1, 4, 9, 16, etc., as the nuclear charged increased in the ratio 1, 2, 3, 4, etc. This meant physically that the frequencies corresponding to jumps from infinity to an orbit of given quantum number, technically called term-values, when divided by the square of the nuclear charge should come out a constant; otherwise stated that the constant term in the Rydberg formula should become N, 4N, 9N, 16N

    Processing of laser formed SiC powder

    Get PDF
    Superior SiC characteristics can be achieved through the use of ideal constituent powders and careful post-synthesis processing steps. High purity SiC powders of approx. 1000 A uniform diameter, nonagglomerated and spherical were produced. This required major revision of the particle formation and growth model from one based on classical nucleation and growth to one based on collision and coalescence of Si particles followed by their carburization. Dispersions based on pure organic solvents as well as steric stabilization were investigated. Although stable dispersions were formed by both, subsequent part fabrication emphasized the pure solvents since fewer problems with drying and residuals of the high purity particles were anticipated. Test parts were made by the colloidal pressing technique; both liquid filtration and consolidation (rearrangement) stages were modeled. Green densities corresponding to a random close packed structure (approx. 63%) were achieved; this highly perfect structure has a high, uniform coordination number (greater than 11) approaching the quality of an ordered structure without introducing domain boundary effects. After drying, parts were densified at temperatures ranging from 1800 to 2100 C. Optimum densification temperatures will probably be in the 1900 to 2000 C range based on these preliminary results which showed that 2050 C samples had experienced substantial grain growth. Although overfired, the 2050 C samples exhibited excellent mechanical properties. Biaxial tensile strengths up to 714 MPa and Vickers hardness values of 2430 kg/sq mm 2 were both more typical of hot pressed than sintered SiC. Both result from the absence of large defects and the confinement of residual porosity (less than 2.5%) to small diameter, uniformly distributed pores

    Processing of laser formed SiC powder

    Get PDF
    Processing research was undertaken to demonstrate that superior SiC characteristics could be achieved through the use of ideal constituent powders and careful post-synthesis processing steps. Initial research developed the means to produce approximately 1000 A uniform diameter, nonagglomerated, spherical, high purity SiC powders. Accomplishing this goal required major revision of the particle formation and growth model from one based on classical nucleation and growth to one based on collision and coalescence of Si particles followed by their carburization. Dispersions based on pure organic solvents as well as steric stabilization were investigated. Test parts were made by the colloidal pressing technique; both liquid filtration and consolidation (rearrangement) stages were modeled. Green densities corresponding to a random close packed structure were achieved. After drying, parts were densified at temperatures ranging from 1800 to 2100 C. This research program accomplished all of its major objectives. Superior microstructures and properties were attained by using powders having ideal characteristics and special post-synthesis processing procedures

    Direct observation of a highly spin-polarized organic spinterface at room temperature

    Get PDF
    The design of large-scale electronic circuits that are entirely spintronics-driven requires a current source that is highly spin-polarised at and beyond room temperature, cheap to build, efficient at the nanoscale and straightforward to integrate with semiconductors. Yet despite research within several subfields spanning nearly two decades, this key building block is still lacking. We experimentally and theoretically show how the interface between Co and phthalocyanine molecules constitutes a promising candidate. Spin-polarised direct and inverse photoemission experiments reveal a high degree of spin polarisation at room temperature at this interface. We measured a magnetic moment on the molecules's nitrogen pi orbitals, which substantiates an ab-initio theoretical description of highly spin-polarised charge conduction across the interface due to differing spinterface formation mechanims in each spin channel. We propose, through this example, a recipe to engineer simple organic-inorganic interfaces with remarkable spintronic properties that can endure well above room temperature

    Optimal fidelity of teleportation of coherent states and entanglement

    Full text link
    We study the Braunstein-Kimble protocol for the continuous variable teleportation of a coherent state. We determine lower and upper bounds for the optimal fidelity of teleportation, maximized over all local Gaussian operations for a given entanglement of the two-mode Gaussian state shared by the sender (Alice) and the receiver (Bob). We also determine the optimal local transformations at Alice and Bob sites and the corresponding maximum fidelity when one restricts to local trace-preserving Gaussian completely positive maps.Comment: 10 pages, 2 figure

    Modelling thermomechanical behaviour of Cr-Mo-V steel

    Get PDF
    This paper presents a mechanism-based approach for modelling the thermomechanical behaviour of a Cr-Mo-V steel. A set of unified viscoplastic constitutive equations were employed to model dislocation density, recrystallisation and grain size during deformation. The evolution of dislocation density accounts for the build-up of dislocations due to plastic strain, the static and dynamic recovery and the effect of recrystallisation. Recrystallisation occurs when a critical dislocation density is reached after an incubation time, and grain size becomes smaller after such event. Gleeble compression tests were used to obtain Stress-strain curves and evaluate the microstructural evolution at different temperature and strain rate, and the material constants for the model were determined from the experimental data. Copyright © 2010 MS&T10®

    Institutionalizing health impact assessment in London as a public health tool for increasing synergy between policies in other areas

    Get PDF
    Objectives: To describe the background to the inclusion of health impact assessment (HIA) in the development process for the London mayoral strategies, the HIA processes developed, how these evolved, and the role of HIA in identifying synergies between and conflicting priorities of different strategies.Study design: Case series.Methods: Early HIAs had just a few weeks for the whole HIA process. A rapid appraisal approach was developed. Stages included: scoping, reviewing published evidence, a stakeholder workshop, drafting a report, review of the report by the London Health Commission, and submission of the final report to the Mayor. The process evolved as more assessments were conducted. More recently, an integrated impact assessment (IIA) method has been developed that fuses the key aspects of this HIA method with sustainability assessment, strategic environmental assessment and equalities assessment.Results: Whilst some of the early strategy drafts encompassed some elements of health, health was not a priority. Conducting HIAs was important both to ensure that the strategies reflected health concerns and to raise awareness about health and its determinants within the Greater London Authority (GLA). HIA recommendations were useful for identifying synergies and conflicts between strategies. HIA can be successfully integrated into other impact assessment processes.Conclusions: The HIAs ensured that health became more integral to the strategies and increased understanding of determinants of health and how the GLA impacts on health and health inequalities. Inclusion of HIA within IIA ensures that health and health inequalities impacts are considered robustly within statutory impact assessments. (C) 2010 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved
    • …
    corecore