3,910 research outputs found

    System to control indoor air quality in energy efficient buildings

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    This work looks at monitoring air quality in indoor environments through the integration of several sensing technologies into a single robust, reliable and cheap detection platform, which shares air pre-conditioning and electronics. Target gases and detection limits have been set according to recommendations of different agencies in Europe and the US. The system has reached detection limits stated by the OSHA (Occupational Safety and Health Administration) for benzene. The pre-conditioning fluidic platform has also been designed, simulated, fabricated and tested with sensors so the gas flow has been optimized. Field tests in real buildings are being carried out to contrast current measurement procedures and results with the obtained using the device under development. The main aim of the system is to control HVAC (Heat Ventilation and Air Conditioning) in energy-efficient way while keeping a high air quality standard inside the building

    The Undergraduate–Postgraduate–Faculty Triad: Unique Functions and Tensions Associated with Undergraduate Research Experiences at Research Universities

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    We present an exploratory study of how undergraduates' involvement in research influences postgraduates (i.e., graduate and postdoctoral researchers) and faculty. We used a qualitative approach to examine the relationships among undergraduates, postgraduates, and the faculty head in a research group. In this group, undergraduates viewed postgraduates as more approachable than the faculty head both literally and figuratively. Mentorship by postgraduates presented unique challenges for undergraduates, including unrealistic expectations and varying abilities to mentor. The postgraduates and faculty head concurred that undergraduates contributed to the group's success and served as a source of frustration. Postgraduates appreciated the opportunity to observe multiple approaches to mentoring as they saw the faculty head and other postgraduates interact with undergraduates. The faculty head viewed undergraduate research as important for propagating the research community and for gaining insights into undergraduates and their postgraduate mentors. These results highlight how the involvement of undergraduates and postgraduates in research can limit and enhance the research experiences of members of the undergraduate–postgraduate–faculty triad. A number of tensions emerge that we hypothesize are intrinsic to undergraduate research experiences at research universities. Future studies can focus on determining the generalizability of these findings to other groups and disciplines

    Constraints on the χ_(c1) versus χ_(c2) polarizations in proton-proton collisions at √s = 8 TeV

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    The polarizations of promptly produced χ_(c1) and χ_(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8  TeV. The χ_c states are reconstructed via their radiative decays χ_c → J/ψγ, with the photons being measured through conversions to e⁺e⁻, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χ_(c2) to χ_(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ → μ⁺μ⁻ decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum
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