22,381 research outputs found

    A new paradigm of governance for a carbon-pricing system

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    Throughout its life, the United Nations has played a pioneering role in the world of ideas. COP21 – also known as Paris 2015 – shows the path for the United Nations to establish a new governance that will enforce the compliance of a new planetary carbon-pricing system. Maintaining global warming below 2 °C means implementing an efficient carbon-pricing system, supported by effective measures promoting a green energy transition. A planetary carbon governance yields a number of new insights that include the following: (1) a bonus-malus system with a fixed signal price for carbon, (2) a planetary carbon market that will gather existing regional carbon markets, (3) a hybrid carbon-pricing system linking a carbon tax and a carbon market for advanced countries and (4) a support mechanism for emerging and developing countries to assist them with a carbon-pricing system. This new governance will promote an energy transition plan. In the COP21 context, responsible policymaking requires key characteristics for the enforcement of a successful planetary carbon-pricing system

    Exploratory wind-tunnel investigation of a wingtip-mounted vortex turbine for vortex energy recovery

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    The Langley 8-foot transonic pressure tunnel was used for tests to determine the possibility of recovering, with a turbine-type device, part of the energy loss associated with the lift-induced vortex system. Tests were conducted on a semispan model with an unswept, untapered wing, with and without a wingtip-mounted vortex turbine. Three sets of turbine blades were tested to determine the effect of airfoil section shape and planform. The tests were conducted at a Mach number of 0.70 over an angle-of-attack range from 0 deg. to 4 deg. at a Reynolds number of 3.82 x 10 to the 6th power based on the wing reference chord of 13 in

    Investigation of powered nacelles on a high aspect ratio NASA supercritical wing, phase 2

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    A modified wing with the long core separate flow nacelle and several E(3) nacelles was utilized. The effects of nacelle and pylon cant angles and nacelle longitudinal and vertical location were investigated over a Mach number range from 0.70 to 0.83. The results at the cruise condition 0.82 Mach number and 0.55 lift coefficient are presented

    Distortion and regulation characterization of a Mapham inverter

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    Output voltage Total Harmonic Distortion (THD) of a 20kHz, 6kVA Mapham resonant inverter is characterized as a function of its switching-to-resonant frequency ratio, f sub s/f sub r, using the EASY5 engineering analysis system. EASY5 circuit simulation results are compared with hardware test results to verify the accuracy of the simulations. The effects of load on the THD versus f sub s/f sub r ratio is investigated for resistive, leading, and lagging power factor load impedances. The effect of the series output capacitor on the Mapham inverter output voltage distortion and inherent load regulation is characterized under loads of various power factors and magnitudes. An optimum series capacitor value which improves the inherent load regulation to better than 3 percent is identified. The optimum series capacitor value is different than the value predicted from a modeled frequency domain analysis. An explanation is proposed which takes into account the conduction overlap in the inductor pairs during steady-state inverter operation, which decreases the effective inductance of a Mapham inverter. A fault protection and current limit method is discussed which allows the Mapham inverter to operate into a short circuit, even when the inverter resonant circuit becomes overdamped

    Development of a global model for atmospheric backscatter at CO2 wavelengths

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    The variation of the aerosol backscattering at 10.6 micrometers within the free troposphere was investigated and a model to describe this variation was developed. The analysis combines theoretical modeling with the results contained within three independent data sets. The data sets used were obtained by the SAGE I/SAM II satellite experiments, the GAMETAG flight series, and by direct backscatter measurements. The theoretical work includes use of a bimodal, two component aerosol model, and the study of the microphysical and associated optical changes occurring within an aerosol plume. A consistent picture is obtained that describes the variation of the aerosol backscattering function in the free troposphere with altitude, latitude, and season

    Development of global model for atmospheric backscatter at CO2 wavelengths

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    The improvement of an understanding of the variation of the aerosol backscattering at 10.6 micron within the free troposphere and the development model to describe this was undertaken. The analysis combines theoretical modeling with the results contained within three independent data sets. The data sets are obtained by the SAGE I/SAM II satellite experiments, the GAMETAG flight series and by direct backscatter measurements. The theoretical work includes use of a bimodal, two component aerosol model, and the study of the microphysical and associated optical changes occurring within an aerosol plume. A consistent picture is obtained, which describes the variation of the aerosol backscattering function in the free troposphere with altitude, latitude, and season. Most data are available and greatest consistency is found inside the Northern Hemisphere

    Experiences of cognitive behavioural therapy formulation in clients with depression

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    AbstractWhile clinicians have described the benefits of using formulations within therapy, little is understood about the client's experience of the formulation process. Cognitive behaviour therapy (CBT) is currently the treatment of choice for many adult mental health difficulties. However, research exploring clients’ experiences of CBT formulation is very limited. The present study set out to explore experiences of CBT formulation in clients with depression. Seven participants were interviewed and the data analysed using Thematic Analysis. The analysis identified key themes such as: ‘Feeling trapped or restricted by depression’, ‘The development of the formulation – from coming to my own conclusions to something the therapist developed’, ‘From negative to mixed feelings: emotional reactions to the formulation during the therapeutic process’ and ‘A new journey: towards making a new sense of oneself’. The results of the study highlight the personal and emotional challenge of the formulation process for clients.</jats:p

    Free charges versus excitons: photoluminescence investigation of InGaN/GaN multiple quantum well nanorods and their planar counterparts

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    InGaN/GaN multiple quantum well (MQW) nanorods have demonstrated significantly improved optical and electronic properties compared to their planar counterparts. However, the exact nature of the processes whereby nanorod structures impact the optical properties of quantum wells is not well understood, even though a variety of mechanisms have been proposed. We performed nanoscale spatially resolved, steady-state, and time-resolved photoluminescence (PL) experiments confirming that photoexcited electrons and holes are strongly bound by Coulomb interactions (i.e., excitons) in planar MQWs due to the large exciton binding energy in InGaN quantum wells. In contrast, free electron–hole recombination becomes the dominant mechanism in nanorods, which is ascribed to efficient exciton dissociation. The nanorod sidewall provides an effective pathway for exciton dissociation that significantly improves the optical performance of InGaN/GaN MQWs. We also confirm that surface treatment of nanorod sidewalls has an impact on exciton dissociation. Our results provide new insights into excitonic and charge carrier dynamics of quantum confined materials as well as the influence of surface states

    Quantitative Morphology of Galaxies in the Hubble Deep Field

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    We measure quantitative structural parameters of galaxies in the Hubble Deep Field (HDF) on the drizzled F814W images. Our structural parameters are based on a two-component surface brightness made up of a S\'ersic profile and an exponential profile. We compare our results to the visual classification of van den Bergh et al. (1996) and the CAC-A classification of Abraham et al. (1996a). Our morphological analysis of the galaxies in the HDF indicates that the spheroidal galaxies, defined here as galaxies with a dominant bulge profile, make up for only a small fraction, namely 8% of the galaxy population down to mF814W(AB)_{F814W}(AB) = 26.0. We show that the larger fraction of early-type systems in the van den Bergh sample is primarily due to the difference in classification of 40% of small round galaxies with half-light radii < 0\arcsecpoint 31. Although these objects are visually classified as elliptical galaxies, we find that they are disk-dominated with bulge fractions < 0.5. Given the existing large dataset of HDF galaxies with measured spectroscopic redshifts, we are able to determine that the majority of distant galaxies (z>2z>2) from this sample are disk-dominated. Our analysis reveals a subset of HDF galaxies which have profiles flatter than a pure exponential profile.Comment: 35 pages, LaTeX, 18 Postscript Figures, Tables available at http://astro.berkeley.edu/~marleau/. Accepted for Publication in The Astrophysical Journa
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