71,727 research outputs found

    Microwave diode amplifiers with low intermodulation distortion

    Get PDF
    Distortions can be greatly reduced in narrow-band applications by using the second harmonic. The ac behavior of simplified diode amplifier has negative resistance depending on slope of equivalent I-V curve

    The Vector Analyzing Power in Elastic Electron-Nucleus Scattering

    Full text link
    The vector analyzing power A_n is calculated for elastic electron scattering from a variety of spin zero nuclei at energies from 14 MeV to 3 GeV. Time reversal symmetry insures that A_n vanish in first Born approximation. Therefore A_n depends on Coulomb distortions and can be large for scattering from heavy nuclei. The vector analyzing power is a potential source of systematic error for parity violation experiments. We find that A_n=-0.361 ppm for the kinematics of the Parity Radius Experiment (PREX) involving 850 MeV electrons scattering at six degrees from 208Pb. This is comparable to the parity violating asymmetry. However for HAPPEX He involving 3 GeV electrons scattering on 4He we find that A_n is very small.Comment: 6 pages, 6 figures, submitted to Phys. Rev.

    ENVIRONMENTAL RISK AND AGRI-ENVIRONMENTAL POLICY DESIGN

    Get PDF
    Agricultural nonpoint pollution is inherently stochastic (e.g., due to weather). In theory, this randomness has implications for the choice and design of policy instruments. However, very few empirical studies have modeled natural variability. This paper investigates the importance of stochastic processes for the choice and design of alternative nonpoint instruments. The findings suggest that not explicitly considering the stochastic processes in the analysis can produce significantly biased results.Agricultural and Food Policy, Environmental Economics and Policy,

    Operation of a haynes alloy no. 25 forced circulation loop to study the effects of hydrogen in a simulated sunflower system

    Get PDF
    Haynes alloy forced circulation mercury loop for studying hydrogen effects in working fluid of Rankine cycle Sunflower solar power syste

    Resumming the large-N approximation for time evolving quantum systems

    Get PDF
    In this paper we discuss two methods of resumming the leading and next to leading order in 1/N diagrams for the quartic O(N) model. These two approaches have the property that they preserve both boundedness and positivity for expectation values of operators in our numerical simulations. These approximations can be understood either in terms of a truncation to the infinitely coupled Schwinger-Dyson hierarchy of equations, or by choosing a particular two-particle irreducible vacuum energy graph in the effective action of the Cornwall-Jackiw-Tomboulis formalism. We confine our discussion to the case of quantum mechanics where the Lagrangian is L(x,x˙)=(1/2)i=1Nx˙i2(g/8N)[i=1Nxi2r02]2L(x,\dot{x}) = (1/2) \sum_{i=1}^{N} \dot{x}_i^2 - (g/8N) [ \sum_{i=1}^{N} x_i^2 - r_0^2 ]^{2}. The key to these approximations is to treat both the xx propagator and the x2x^2 propagator on similar footing which leads to a theory whose graphs have the same topology as QED with the x2x^2 propagator playing the role of the photon. The bare vertex approximation is obtained by replacing the exact vertex function by the bare one in the exact Schwinger-Dyson equations for the one and two point functions. The second approximation, which we call the dynamic Debye screening approximation, makes the further approximation of replacing the exact x2x^2 propagator by its value at leading order in the 1/N expansion. These two approximations are compared with exact numerical simulations for the quantum roll problem. The bare vertex approximation captures the physics at large and modest NN better than the dynamic Debye screening approximation.Comment: 30 pages, 12 figures. The color version of a few figures are separately liste

    The mineral resources landscape - an expanded conceptualisation of minerals sustainability

    Full text link
    As part of global systems of mineral production and consumption, the Australian minerals sector is facing sustainability challenges across technological, social, ecological, economic and governance domains, as well as between local, national and global scales. To ensure that the Australian minerals sector progresses towards sustainability, it is imperative to understand the possible ways in which Australias mineral resources could support sustainable futures. A significant research gap exists between the complex nature of questions concerning minerals sustainability and the reductionist methods available to deal with them. This paper argues the need for broader, more integrated approaches to questions concerning minerals sustainability, which can address multiple human perspectives, complex and `messy patterns and processes across multiple organisational, temporal and geographical scales and whole systems of mineral production and consumption
    corecore