756 research outputs found

    Pennsylvania and the Clean Power Plan: Towards a 111(d) Compliance Strategy

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    The Environmental Protection Agency released its proposed Clean Power Regulation in June 2014, and in mid-summer 2015, the finalized rule will be the first comprehensive regulation of carbon dioxide emissions from existing power plants in American history. Compliance strategies will be expensive and complex decisions for states to make. Each state faces the choice of whether to comply individually or as a region, but posses the freedom to comply in whatever way they choose. Pennsylvania is unique. The commonwealth has an entrenched coal industry, a nascent natural gas industry, and is a net exporter of electricity. Joining the Regional Greenhouse Gas Initiative (RGGI), a group of northeast states that borders Pennsylvania to the north, may be one compliance option, but joining a different region may be a more desirable lower cost solution. This analysis seeks to show that the cost of compliance would be lower if Pennsylvania joined a select group of states within the PJM Interconnection. One result of the analysis suggests that by joining with complementary states within PJM, relatively minor changes in Pennsylvania coal-fired generation would be required to meet Clean Power Plan compliance 2030 goals

    Direct Interactions in Relativistic Statistical Mechanics

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    Directly interacting particles are considered in the multitime formalism of predictive relativistic mechanics. When the equations of motion leave a phase-space volume invariant, it turns out that the phase average of any first integral, covariantly defined as a flux across a 7n7n-dimensional surface, is conserved. The Hamiltonian case is discussed, a class of simple models is exhibited, and a tentative definition of equilibrium is proposed.Comment: Plain Tex file, 26 page

    Probabilistic ballistic annihilation with continuous velocity distributions

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    We investigate the problem of ballistically controlled reactions where particles either annihilate upon collision with probability pp, or undergo an elastic shock with probability 1p1-p. Restricting to homogeneous systems, we provide in the scaling regime that emerges in the long time limit, analytical expressions for the exponents describing the time decay of the density and the root-mean-square velocity, as continuous functions of the probability pp and of a parameter related to the dissipation of energy. We work at the level of molecular chaos (non-linear Boltzmann equation), and using a systematic Sonine polynomials expansion of the velocity distribution, we obtain in arbitrary dimension the first non-Gaussian correction and the corresponding expressions for the decay exponents. We implement Monte-Carlo simulations in two dimensions, that are in excellent agreement with our analytical predictions. For p<1p<1, numerical simulations lead to conjecture that unlike for pure annihilation (p=1p=1), the velocity distribution becomes universal, i.e. does not depend on the initial conditions.Comment: 10 pages, 9 eps figures include

    Dynamical real-space renormalization group calculations with a new clustering scheme on random networks

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    We have defined a new type of clustering scheme preserving the connectivity of the nodes in network ignored by the conventional Migdal-Kadanoff bond moving process. Our new clustering scheme performs much better for correlation length and dynamical critical exponents in high dimensions, where the conventional Migdal-Kadanoff bond moving scheme breaks down. In two and three dimensions we find the dynamical critical exponents for the kinetic Ising Model to be z=2.13 and z=2.09, respectively at pure Ising fixed point. These values are in very good agreement with recent Monte Carlo results. We investigate the phase diagram and the critical behaviour for randomly bond diluted lattices in d=2 and 3, in the light of this new transformation. We also provide exact correlation exponent and dynamical critical exponent values on hierarchical lattices with power-law degree distributions, both in the pure and random cases.Comment: 8 figure

    On the universality of a class of annihilation-coagulation models

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    A class of dd-dimensional reaction-diffusion models interpolating continuously between the diffusion-coagulation and the diffusion-annihilation models is introduced. Exact relations among the observables of different models are established. For the one-dimensional case, it is shown how correlations in the initial state can lead to non-universal amplitudes for time-dependent particles density.Comment: 18 pages with no figures. Latex file using REVTE

    The PCA Lens-Finder: application to CFHTLS

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    We present the results of a new search for galaxy-scale strong lensing systems in CFHTLS Wide. Our lens-finding technique involves a preselection of potential lens galaxies, applying simple cuts in size and magnitude. We then perform a Principal Component Analysis of the galaxy images, ensuring a clean removal of the light profile. Lensed features are searched for in the residual images using the clustering topometric algorithm DBSCAN. We find 1098 lens candidates that we inspect visually, leading to a cleaned sample of 109 new lens candidates. Using realistic image simulations we estimate the completeness of our sample and show that it is independent of source surface brightness, Einstein ring size (image separation) or lens redshift. We compare the properties of our sample to previous lens searches in CFHTLS. Including the present search, the total number of lenses found in CFHTLS amounts to 678, which corresponds to ~4 lenses per square degree down to i=24.8. This is equivalent to ~ 60.000 lenses in total in a survey as wide as Euclid, but at the CFHTLS resolution and depth.Comment: 21 pages, 12 figures, accepted for publication on A&

    A renormalization group study of a class of reaction-diffusion model, with particles input

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    We study a class of reaction-diffusion model extrapolating continuously between the pure coagulation-diffusion case (A+AAA+A\to A) and the pure annihilation-diffusion one (A+AA+A\to\emptyset) with particles input (A\emptyset\to A) at a rate JJ. For dimension d2d\leq 2, the dynamics strongly depends on the fluctuations while, for d>2d >2, the behaviour is mean-field like. The models are mapped onto a field theory which properties are studied in a renormalization group approach. Simple relations are found between the time-dependent correlation functions of the different models of the class. For the pure coagulation-diffusion model the time-dependent density is found to be of the form c(t,J,D)=(J/D)1/δF[(J/D)ΔDt]c(t,J,D) = (J/D)^{1/\delta}{\cal F}[(J/D)^{\Delta} Dt], where DD is the diffusion constant. The critical exponent δ\delta and Δ\Delta are computed to all orders in ϵ=2d\epsilon=2-d, where dd is the dimension of the system, while the scaling function F\cal F is computed to second order in ϵ\epsilon. For the one-dimensional case an exact analytical solution is provided which predictions are compared with the results of the renormalization group approach for ϵ=1\epsilon=1.Comment: Ten pages, using Latex and IOP macro. Two latex figures. Submitted to Journal of Physics A. Also available at http://mykonos.unige.ch/~rey/publi.htm

    Complex population dynamics as a competition between multiple time-scale phenomena

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    The role of the selection pressure and mutation amplitude on the behavior of a single-species population evolving on a two-dimensional lattice, in a periodically changing environment, is studied both analytically and numerically. The mean-field level of description allows to highlight the delicate interplay between the different time-scale processes in the resulting complex dynamics of the system. We clarify the influence of the amplitude and period of the environmental changes on the critical value of the selection pressure corresponding to a phase-transition "extinct-alive" of the population. However, the intrinsic stochasticity and the dynamically-built in correlations among the individuals, as well as the role of the mutation-induced variety in population's evolution are not appropriately accounted for. A more refined level of description, which is an individual-based one, has to be considered. The inherent fluctuations do not destroy the phase transition "extinct-alive", and the mutation amplitude is strongly influencing the value of the critical selection pressure. The phase diagram in the plane of the population's parameters -- selection and mutation is discussed as a function of the environmental variation characteristics. The differences between a smooth variation of the environment and an abrupt, catastrophic change are also addressesd.Comment: 15 pages, 12 figures. Accepted for publication in Phys. Rev.
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