8,750 research outputs found

    Ion molecule reactions in vinyl fluoride by photoionization. Effects of vibrational excitation on major reaction pathways

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    Photoionization methods have been used to study the reactions of the molecular ion in vinyl fluoride to yield the ionic products C_3H_3F_2^+, C_3H_4F^+, and C_3H_5^+. Quantitative measurements are reported of the effect of the vibrational state of the reactant ion on the product distribution and overall reaction cross section. Reaction cross sections for all three channels decrease with reactant internal energy. The effect on the reaction pathway producing C_3H_3F_2^+ is especially pronounced, with 0.18 eV of vibrational excitation being sufficient to reduce the reaction probability by 75%. Deactivation of vibrationally excited reactant ions competes with the reaction and is shown to be an efficient process

    Effects of the roller feed ratio on wrinkling failure in conventional spinning of a cylindrical cup

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    In this study, wrinkling failure in conventional spinning of a cylindrical cup has been investigated by using both finite element (FE) analysis and experimental methods. FE simulation models of a spinning experiment have been developed using the explicit finite element solution method provided by the software Abaqus. The severity of wrinkles is quantified by calculating the standard deviation of the radial coordinates of element nodes on the edge of the workpiece obtained from the FE models. The results show that the severity of wrinkles tends to increase when increasing the roller feed ratio. A forming limit study for wrinkling has been carried out and shows that there is a feed ratio limit beyond which the wrinkling failure will take place. Provided that the feed ratio is kept below this limit, the wrinkling failure can be prevented. It is believed that high compressive tangential stresses in the local forming zone are the causes of the wrinkling failure. Furthermore, the computational performance of the solid and shell elements in simulating the spinning process are examined and the tool forces obtained from wrinkling and wrinkle-free models are compared. Finally, the effects of the feed ratio on variations of the wall thickness of the spun cylindrical cup are investigated. </jats:p

    Sense-making of consumer wellbeing in information technology-enabled services from a relational ontology position

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    Information technology (IT) built into products and services have become the key drivers for service innovation. How information technology-enabled services (ITESs) affect consumer wellbeing has increasingly become a concern to service scholars. In response to this, transformative service research (TSR) has emerged as a new stream in service research. This paper investigates consumer wellbeing derived from the consumption of ITESs in consumersā€™ daily lives. A mixed-method approach was employed in our study, including self-reflective reports, in-depth interviews and visual artistic methods. We demonstrated that a relational ontology, drawing on the ā€˜focal thingsā€™ concept (Borgmann, 1984) and sociomateriality (Orlikowski, 2009), could be used as a lens for us to understand consumer wellbeing in ITESs. We used four vignettes to demonstrate how relational ontology can enhance our understanding of consumer wellbeing in ITESs. Theoretically, this paper contributes to TSR by proposing and demonstrating the need to shift or at least extend the extant predominant technology ontology in marketing literature to make sense of consumer experiences and wellbeing in ITESs. In practice, this research encourages ITESs designers to emphasise the relational entanglement of technology with consumer routine practices in their service innovations for the purposes of consumer wellbeing

    Modeling the Ecological Consequences of Visitor Behavior in Off-Trail Areas Dispersed Recreation Use

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    Recreation Resource Impacts in the Bear Lake Road Corridor of Rocky Mountain National Park, Colorado, USA: An Assessment of Resource Conditions and Visitor Perceptions

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    Visitor use in parks and protected areas inevitably leads to resource impacts. In order to effectively manage for resource impacts, it is important for managers to not only understand ecological aspects of their system but sociological aspects as well. The two papers presented in this thesis used integrated approaches to better understand the current level of resource impacts within the Bear Lake Road Corridor of Rocky Mountain National Park and to explore visitor perceptions of these impacts. The first paper used traditional monitoring and assessment techniques, as well as recently developed methodologies, to determine the current level of resource impacts and examine areas for potential future resource change. Findings showed that there is significant impact in the trail system, particularly at popular hiking destinations. At two of these popular hiking destinations, with current use levels, there is potential for future resource change. Integration with measures of social norms showed that visitors are frequently experiencing resource conditions within the Bear Lake Road Corridor that are considered unacceptable
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