738 research outputs found

    Evaluation of process causes and influences of residual stress on gear distortion

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    In the automotive industry, heat treatment of components is implicitly related to distortion. This phenomenon is particularly obvious in the case of gears because of their typical and precise geometry. Even if distortion can be anticipated to an extent by experience, it remains complex to comprehend. This paper presents an approach to estimate the distortion based on the idea of a distortion potential taking into account not only geometry but also the manufacturing process history. Then the idea is developed through simulation and experiments including annealing to understand the impact of residual stress on gear distortion in an industrial case study

    The accessory bacteriochlorophyll

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    The primary electron transfer in reaction centers of Rhodobacter sphaeroides is studied by subpicosecond absorption spectroscopy with polarized light in the spectral range of 920-1040 nm. Here the bacteriochlorophyll anion radical has an absorption band while the other pigments of the reaction center have vanishing ground-state absorption. The transient absorption data exhibit a pronounced 0.9-ps kinetic component which shows a strong dichroism. Evaluation of the data yields an angle between the transition moments of the special pair and the species related with the 0.9-ps kinetic component of 26 +/- 8 degrees. This angle compares favorably with the value of 29 degrees expected for the reduced accessory bacteriochlorophyll. Extensive transient absorbance data are fully consistent with a stepwise electron transfer via the accessory bacteriochlorophyll

    Surfing Without Water: College Students Who Experience Homelessness

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    This study explores the educational experiences and needs of college students experiencing homelessness from the St. Louis metropolitan area. Research has shown that youth experiencing homelessness have difficulties entering college, remaining in college, and graduating from college (School House Connections, 2020). Difficulty accessing services and support coupled with prejudice, discrimination, and lack of knowledge can be detrimental to the homeless students’ academic performance (Svokos, 2015). The purpose of this study is to investigate issues of homelessness in higher education as experienced by independent college students identified as homeless in high school and explore the types of support universities offer via the College Cost Reduction and Act (CCRAA). The results from this study provide an understanding of the challenges that homeless independent students face while in pursuit of a postsecondary degree and the types of supports offered via their universities. The six themes noted from interviews with four students included: basic needs, trauma, educational support, connections, adulting, and cultural competence. Recommendations for policy and practice are discussed

    PHOTOCHEMICAL RING-OPENING IN meso-CHLORINATED CHLOROPHYLLS

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    Irradiation of 20-chloro-chlorophylls of the a-type with visible light produces long-wavelength shifted photoproducts, which transform in the dark to linear tetrapyrroles (bile pigments). The possible significance for chlorophyll degradation is discussed

    Evaluation of process causes and influences of residual stress on gear distortion

    Get PDF
    In the automotive industry, heat treatment of components is implicitly related to distortion. This phenomenon is particularly obvious in the case of gears because of their typical and precise geometry. Even if distortion can be anticipated to an extent by experience, it remains complex to comprehend. This paper presents an approach to estimate the distortion based on the idea of a distortion potential taking into account not only geometry but also the manufacturing process history. Then the idea is developed through simulation and experiments including annealing to understand the impact of residual stress on gear distortion in an industrial case study

    Sector coupling established by the technology partnership reFuels - rethinking fuels

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    The use of regeneratively produced fuels (reFuels) is a promising path towards CO2-neutral mobility, alongside other measures such as the expansion of electric mobility. These fuels can be produced from carbon-containing residues from agriculture and forestry, from industrial and municipal waste, as well as from CO2 in combination with hydrogen obtained by electrolysis of water. These fuels together form the reFuels class. In order to assess the potential of reFuels, a holistic evaluation is necessary, including the determination of efficiency potentials for their manufacture and application. Under the patronage of the state of Baden-Württemberg the technology partnership reFuels was initiated, in which companies of the energy and mineral oil industry, the automotive industry and the supplier industry together with the Karlsruhe Institute of Technology (KIT) are investigating efficiency potentials for the production and application of reFuels. Pilot facilities already in operation will be used to produce fuel components in a sufficient scale. The systemic and socioeconomic aspects for the production and application of reFuels will be considered and put in an dialogue with civil society actors to consider the open communication into society.. Within the reFuels project started in 2019 for 2 years duration the consortium of industrial companies and KIT including companies as energy providers, fuels synthesis to suppliers, system developers to engine and car manufacturers. The Project shall achieve the following goals: 1. Provision of selected regenerative fuels ("reFuels") and holistic evaluation of the processes for their production including the determination of efficiency potentials for production and application 2. Evaluation of reFuels key properties, demonstration in the application and evaluation of the application properties 3. Involvement of civil society actors and communication in society

    The Influence of Environmental Conditions on Pacing in Age Group Marathoners Competing in the "New York City Marathon"

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    Background: The two aspects of the influence of environmental conditions on marathon running performance and pacing during a marathon have been separately and widely investigated. The influence of environmental conditions on the pacing of age group marathoners has, however, not been considered yet.Objective: The aim of the present study was to investigate the association between environmental conditions (i.e., temperature, barometric pressure, humidity, precipitation, sunshine, and cloud cover), gender and pacing of age group marathoners in the “New York City Marathon”.Methodology: Between 1999 and 2019, a total of 830,255 finishes (526,500 males and 303,755 females) were recorded. Time-adjusted averages of weather conditions for temperature, barometric pressure, humidity, and sunshine duration during the race were correlated with running speed in 5 km-intervals for age group runners in 10 years-intervals.Results: The running speed decreased with increasing temperatures in athletes of age groups 20–59 with a pronounced negative effect for men aged 30–64 years and women aged 40–64 years. Higher levels of humidity were associated with faster running speeds for both sexes. Sunshine duration and barometric pressure showed no association with running speed.Conclusion: In summary, temperature and humidity affect pacing in age group marathoners differently. Specifically, increasing temperature slowed down runners of both sexes aged between 20 and 59 years, whereas increasing humidity slowed down runners of <20 and >80 years old
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