250 research outputs found

    Community Wind Financing Handbook

    Get PDF
    The goal of this handbook is to identify critical financing issues and present several possible financing models that reflect the differing financial positions and investment goals of various project owners/developers. The handbook includes six sections:-- Section I describes various models for community wind power ownership.-- Section II examines sources of equity and debt financing and the steps necessary to secure this financing.-- Section III identifies federal grant and loan programs and state incentives for wind power development.-- Section IV reviews the federal tax incentives supporting wind power projects, the impact of these incentives on project economics, and limitations on utilizing these incentives.-- Section V examines power purchase agreements and the value of green tags to community wind power projects.-- The Appendix contains a list of operating community wind projects in the United States and a list of project consultants and financing resources.Principal author: Charles Kubert, Environmental Business Specialist, with assistance from Howard Learner, Executive Director, Jill Geiger, Director of Communications and Marketing, and Rebecca Stamey-White, Policy Associat

    Dirac quasiparticles in the mixed state

    Full text link
    Energies and wave functions are calculated for d-wave quasiparticles in the mixed state using the formalism of Franz and Tesanovic for the low-lying energy levels. The accuracy of the plane-wave expansion is explored by comparing approximate to exact results for a simplified one-dimensional problem, and the convergence of the plane- wave expansion to the two-dimensional case is studied. The results are used to calculate the low-energy tunneling density of states and the low-temperature specific heat, and these theoretical results are compared to semiclassical treatments and to the available data. Implications for the muon spin resonance measurements of vortex core size are also discussed.Comment: 13 pages, 15 figures, RevTeX. References corrected. A factor of 2 in the results has been corrected, and the conclusions have been update

    Supercurrent in Nodal Superconductors

    Full text link
    In recent years, a number of nodal superconductors have been identified; d-wave superconductors in high T_c cuprates, CeCoIn5_5, and \kappa-(ET)_2Cu(NCS)_2, 2D f-wave superconductor in Sr_2RuO_4 and hybrid s+g-wave superconductor in YNi_2B_2C. In this work we conduct a theoretical study of nodal superconductors in the presence of supercurrent. For simplicity, we limit ourselves to d-wave and 2D f-wave superconductors. We compute the quasiparticle density of states and the temperature dependence of the depairing critical current in nodal superconductors, both of which are accessible experimentally.Comment: revtex4, 6 pages, 7 figures; fixed typos, updated references, trimmed introductio

    BonFIRE: A multi-cloud test facility for internet of services experimentation

    Get PDF
    BonFIRE offers a Future Internet, multi-site, cloud testbed, targeted at the Internet of Services community, that supports large scale testing of applications, services and systems over multiple, geographically distributed, heterogeneous cloud testbeds. The aim of BonFIRE is to provide an infrastructure that gives experimenters the ability to control and monitor the execution of their experiments to a degree that is not found in traditional cloud facilities. The BonFIRE architecture has been designed to support key functionalities such as: resource management; monitoring of virtual and physical infrastructure metrics; elasticity; single document experiment descriptions; and scheduling. As for January 2012 BonFIRE release 2 is operational, supporting seven pilot experiments. Future releases will enhance the offering, including the interconnecting with networking facilities to provide access to routers, switches and bandwidth-on-demand systems. BonFIRE will be open for general use late 2012

    Ultrasonic Attenuation in the Vortex State of d-wave Superconductors

    Full text link
    We calculate the low temperature quasi-particle contribution to the ultrasonic attenuation rate in the mixed state of d-wave superconductors. Our calculation is performed within the semi-classical approximation using quasi-particle energies that are Doppler shifted, with respect to their values in the Meissner phase, by the supercurrent associated with the vortices. We find that the attenuation at low temperatures and at fields Hc1HHc2 H_{c1} \leq H \ll H_{c2} has a temperature independent contribution which is proportional to H\surd H where HH is the applied magnetic field. We indicate how our result in combination with the zero-field result for ultrasonic attenuation can be used to calculate one of the parameters vFv_F, Hc2H_{c2} or ξ\xi given the values for any two of them.Comment: 10 pages, RevTeX, submitted to Physica

    Milnor-Selberg zeta functions and zeta regularizations

    Full text link
    By a similar idea for the construction of Milnor's gamma functions, we introduce "higher depth determinants" of the Laplacian on a compact Riemann surface of genus greater than one. We prove that, as a generalization of the determinant expression of the Selberg zeta function, this higher depth determinant can be expressed as a product of multiple gamma functions and what we call a Milnor-Selberg zeta function. It is shown that the Milnor-Selberg zeta function admits an analytic continuation, a functional equation and, remarkably, has an Euler product.Comment: 32 pages, 7 figure

    Quasiparticle thermal Hall angle and magnetoconductance in YBa_2Cu_3O_x

    Full text link
    We present a way to extract the quasiparticle (qp) thermal conductivity Kappa_e and mean-free-path in YBa_2Cu_3O_x, using the thermal Hall effect and the magnetoconductance of Kappa_e. The results are very consistent with heat capacity experiments. Moreover, we find a simple relation between the thermal Hall angle Theta_Q and the H-dependence of Kappa_e, as well as numerical equality between Theta_Q and the electrical Hall angle. The findings also reveal an anomalously anisotropic scattering process in the normal state.Comment: 4 pages in Tex, 5 figures in EPS; replaced on 5/12/99, minor change

    On the ubiquity of trivial torsion on elliptic curves

    Get PDF
    The purpose of this paper is to give a "down--to--earth" proof of the well--known fact that a randomly chosen elliptic curve over the rationals is most likely to have trivial torsion

    Effects of Age and Gender on Spatial Navigation: Evidence from Samoan Primary School Children

    Get PDF
    This study examined the effects of age and gender on spatial navigation ability. Samoan Primary School students (N = 40) aged 7-12 years were tested on performance of a Size Test and a Corsi Test, followed by a Spatial Navigation Test. It was hypothesized that older children would perform better at all tasks, especially the Spatial Navigation Test. It was further hypothesized that males would perform better than females at the Spatial Navigation Test and that males would employ more detailed strategies in traversing the spatial navigation space. Lastly, it was hypothesized that increased performance on the Size and Corsi Tests would correlate with increased performance on the Spatial Navigation Test. Results showed that age and gender did not significantly predict spatial navigation ability. Findings suggest that cultural disparities in the constructs of age and gender in Samoa as compared to the United States may have impacted study results. Further cultural specific considerations including language, school system structure, and representational focus are discussed

    Heat Conduction in κ\kappa-(BEDT-TTF)2_2Cu(NCS)2_2

    Full text link
    The first study of thermal conductivity, κ\kappa, in a quasi-two-dimensional organic superconductor of the κ\kappa-(BEDT-TTF)2_2X family reveals features analogous to those already observed in the cuprates. The onset of superconductivity is associated with a sudden increase in κ\kappa which can be suppressed by the application of a moderate magnetic field. At low temperatures, a finite linear term - due to a residual electronic contribution- was resolved. The magnitude of this term is close to what is predicted by the theory of transport in unconventional superconductors.Comment: 5 pages, 4 figures include
    corecore