1,649 research outputs found

    As Time Goes By: Ritualized Remembering Through Wedding Photography

    Get PDF
    The practice of remembering sometimes takes the form of ritual in order to enforce, embody and sustain social bonds and values. American wedding photography is a strong example of an instance in which remembering becomes a formalized symbolic performance through an intricate system of idealization as prescribed by various authorities. An examination of the production and exhibition practices constituting wedding photography (using various interview and observation methodologies) reveals a process through which participants solidify and maintain the social transformation marriage creates, communicate values to future generations, and cope with the implications of aging and death

    Carbon nanotube-guided thermopower waves

    Get PDF
    Thermopower waves are a new concept for the direct conversion of chemical to electrical energy. A nanowire with large axial thermal diffusivity can accelerate a self-propagating reaction wave using a fuel coated along its length. The reaction wave drives electrical carriers in a thermopower wave, creating a high-power pulse of as much as 7 kW/kg in experiments using carbon nanotubes. We review nanomaterials designed to overcome limitations of thermoelectricity and explore the emerging scientific and practical outlook for devices using thermopower waves

    Hierarchical metamodeling: Cross validation and predictive uncertainty

    Get PDF
    At Esaform 2013 a hierarchical metamodeling approach had been presented, able to com- bine the results of numerical simulations and physical experiments into a unique response surface, which is a "fusion'' of both data sets. The method had been presented with respect to the structural optimization of a steel tube, filled with an aluminium foam, intended as an anti-intrusion bar. The prediction yielded by a conventional way of metamodeling the results of FEM simulations can be considered trustworthy only if the accuracy of numerical models have been thoroughly tested and the simulation parameters have been sufficiently calibrated. On the contrary, the main advantage of a hierarchical metamodel is to yield a reliable prediction of a response variable to be optimized, even in the presence of non-completely calibrated or accurate FEM models. In order to demonstrate these statements, in this paper the authors wish to compare the prediction ability of a "fusion'' metamodel based on under-calibrated simulations, with a conventional approach based on calibratedFEMresults. Both metamodels will be cross validated with a "leave-one-out'' technique, i.e. by excluding one ex- perimental observation at a time and assessing the predictive ability of the model. Furthermore, the paper will demonstrate how the hierarchical metamodel is able to provide not only an average esti- mated value for each excluded experimental observation, but also an estimation of uncertainty of the prediction of the average value

    Extrusion Additive Manufacturing of PEI Pellets

    Get PDF
    The simplest, most cost-efficient, and most widespread Additive Manufacturing (AM) technology is Extrusion Additive Manufacturing (EAM). Usually, EAM is performed with filament feedstock, but using pellets instead of filaments yields many benefits, including significantly lower cost and a wider choice of materials. High-performance polymers offer high strength even when produced with AM technique, allowing to produce near-net-shape functional parts. The production of these materials in filament form is still limited and expensive; therefore, in this paper, the possibility of producing AM components with engineering polymers from pellets will be thoroughly investigated. In this work, the effectiveness of a specially designed AM machine for printing high-performance materials in pellet form was tested. The material chosen for the investigation is PEI 1000 which offers outstanding mechanical and thermal properties, giving the possibility to produce with EAM functional components. Sensitivity analyses have been carried out to define a process window in terms of thermal process parameters by observing different response variables. Using the process parameters in the specified range, the additive manufactured material has been mechanically tested, and its microstructure has been investigated, both in dried and undried conditions. Finally, a rapid tool for sheet metal forming has been produced

    Energy Efficiency of the Vulcanization Process of a Bicycle Tyre

    Get PDF
    The production of tyres is one of the most energy consuming manufacturing activities in the rubber sector. In the production cycle of a tyre, the curing operation has the maximum energy loss. This is mostly due to the extensive use of steam as a source of heat and pressure in the vulcanization process. To the author’s knowledge, no scientific work is available in the literature where the energy efficiency of a tyre vulcanization press is estimated by means of a comprehensive model of all main components, including the moulds, the press with its heated plates, the bladder and, of course, the tyre. The present work aims at filling this gap. First, the press used for developing the model is described, along with its components and its typical product, a bicycle tyre. The instruments used for measuring flow rates, temperatures and pressures are also listed. Then, a numerical model is presented, that predicts the energy transfers occurring in the vulcanization press during a full process cycle. The numerical model, developed with the software Simcenter Amesim 2021.1, has been validated by means of measurements taken at the press. The results indicate that the amount of energy which is actually consumed by the tyre for its reticulation process amounts to less than 1% of the total energy expenditure. The paper demonstrates that the tyre industry is in urgent need of an electrification conversion of the traditional steam-based processes

    The Structure of Spatial Networks and Communities in Bicycle Sharing Systems

    Get PDF
    Bicycle sharing systems exist in hundreds of cities around the world, with the aim of providing a form of public transport with the associated health and environmental benefits of cycling without the burden of private ownership and maintenance. Five cities have provided research data on the journeys (start and end time and location) taking place in their bicycle sharing system. In this paper, we employ visualization, descriptive statistics and spatial and network analysis tools to explore system usage in these cities, using techniques to investigate features specific to the unique geographies of each, and uncovering similarities between different systems. Journey displacement analysis demonstrates similar journey distances across the cities sampled, and the (out)strength rank curve for the top 50 stands in each city displays a similar scaling law for each. Community detection in the derived network can identify local pockets of use, and spatial network corrections provide the opportunity for insight above and beyond proximity/popularity correlations predicted by simple spatial interaction models

    In Vivo Delivery of Nitric Oxide-Sensing, Single-Walled Carbon Nanotubes

    Get PDF
    Detection of nitric oxide (NO) in vivo by single-walled carbon nanotubes (SWNT) is based on the fluorescent properties of SWNT and the ability of NO to quench the fluorescence signal. Alterations of the signal can be utilized to detect a small molecule in vivo that has not previously been possible by other assay techniques. The protocols described here explain the techniques used to prepare NO-detecting SWNTs and to administer them to mice by both intravenous and subcutaneous routes. These techniques can also be utilized with other SWNT sensors as well as non-SWNT sensorNational Institutes of Health (T32 Training Grant in Environmental Toxicology ES007020

    iObjectify: self- and other-objectification on Grindr, a geosocial networking application designed for men who have sex with men

    Get PDF
    Grindr is a smartphone application for men who have sex with men (MSM). Despite its reputation as a ‘hook-up app’, little is known about its users’ self-presentation strategies and how this relates to objectification - this paper explores objectification on Grindr. The results of Study 1 showed that Grindr users objectified other men more than non-Grindr users. A content analysis of 1400 Grindr profiles in Study 2 showed that profile pictures with objectifying content were related to searching for sexual encounters. Finally, a survey of Grindr users in Study 3 revealed that objectification processes and sexualized profile pictures were related to some objectification-relevant online behaviors (e.g., increased use of Grindr, discussion of HIV status). Interestingly, the presence of body focused profile content was more related to sexual orientation disclosure (not being ‘out’) than to objectification. This paper presents evidence that Grindr usage and online presentation are related to objectification processes

    Extraordinary sensitivity of the electronic structure and properties of single-walled carbon nanotubes to molecular charge-transfer

    Full text link
    Interaction of single-walled carbon nanotubes with electron donor and acceptor molecules causes significant changes in the electronic and Raman spectra, the relative proportion of the metallic species increasing on electron donation through molecular charge transfer, as also verified by electrical resistivity measurements.Comment: 15 pages, 5 figurre

    PXRF analysis of a yellow ochre quarry and rock art motifs in the Central Pilbara

    Get PDF
    The significance of ochre in Indigenous Australia is well documented. Several large, well-known quarries containing ochre that is highly sought after have been described in the archaeological literature, however less attention has been paid to smaller, regionally and locally significant quarries. In this paper a small yellow ochre quarry (VSTA_20140611_1) from the Central Pilbara, where evidence of paint preparation is preserved in the form of residues in two in situ grinding hollows, is described in order to address this oversight. Portable XRF (pXRF) analysis of the pigment in the quarry itself and the paint in the hollows was undertaken to understand the chemistry of the pigmentaceous minerals, to explore the taphonomy of the ochre seam, and to gauge variation within the source. Chemistry indicates that the VSTA_20140611_1 quarry is composed of an iron mineral (likely a hydroxide such as goethite), with Fe abundances consistently between 10.7 and 30%. Typical of the regional geology, the yellow pigment is consistently siliceous, with an Si abundance of between 5.8 and 20.4%. As there are no painted motifs in the rockshelter containing the VSTA_20140611_1 quarry, nor on the suitable BIF surfaces nearby, it is considered highly likely that the surviving paint produced on-site was used for either body decoration or the adornment of artefacts, rather than for rock art production. Nevertheless, the similarity in chemical composition between the VSTA_20140611_1 pigments and that of motifs painted in sites a few kilometres away suggests that, in addition to immediate processing and use at the site, ochre from this quarry may have been transported to rockshelters in the vicinity and used for rock art production
    • …
    corecore