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Temperature increase of 21st century mitigation scenarios

IOP Conference Series: Earth and Environmental Science 2009年第49期6卷

作者： Detlef P van Vuuren M Meinshausen G-K Plattner F Joos K M Strassman S J Smith T M L Wigley S C B Raper K Riahi P de la Chesnaye M G J den Elzen J Fujino K Jiang N Nakicenovic S Paltsev J M Reilly Globa Sustainability and Climate Netherlands Environmental Assessment Agency Bilthoven The Netherlands Potsdam Institute for Climate Impact Research Potsdam Germany Environmental Physics Institute of Biogeochemistry and Pollutant Dynamics ETH Zürich Zurich Switzerland Climate and Environmental Physics Physics Institute University of Bern Bern Switzerland Oeschger Centre for Climate Change Research University of Bern Bern Switzerland Joint Global Change Research Institute Pacific Northwest National Laboratory College Park MD. USA National Center for Atmospheric Research Boulder CO USA Centre for Air Transport and the Environment Manchester Metropolitan University Manchester UK International Institute for Applied Systems Analysis Laxenburg Austria Graz University of Technology Graz Austria Global Climate Program Electric Power Research Institute Washington DC. USA Climate Policy Assessment Section Center for Global Environment Research National Institute for Environmental Studies Tsukuba Ibaraki Japan Energy Research Institute Beijing PR China Joint Program on the Science and Policy of Global Change Massachusetts Institute of Technology Cambridge MA USA

This article was submitted without an abstract, please refer to the full-text PDF file.

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Sonic boom post processing to include atmospheric turbulence effects

Sonic boom post processing to include atmospheric turbulence...

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作者： Locey, Lance L. Sparrow, Victor W. Piacsek, Andrew A. Pennsylvania State University University Park PA 16802 United States Central Washington University Ellensburg WA 98926 United States Graduate Program in Acoustics 201 Applied Science Bldg. University Park PA 16802 United States Department of Physics 400 E. University Way Ellensburg WA 98926 United States

ISBN: (纸本)9781563479397

The Nonlinear Progressive wave Equation (NPE) is modified to include a turbulence representation based upon temperature fluctuations. The turbulence is composed of the sum of 600 Fourier modes based on a modified von Kármán spectrum with an outer length scale of 100 m and an inner length scale of .001 m. Variations in temperature induce variations in the local speed of sound. The NPE propagates for several seconds with a propagation time step of 1e-5 s. The resultant 2D waveform is then used to generate filter functions which approximate the effects of propagation through the turbulence. The filter functions can then be used to represent turbulent propagation by convolving the filter with any waveform, assuming it has sufficient high frequency content. Copyright © 2008 by Lance L. Locey, Victor W. Sparrow, and Andrew A. Piacsek.

关键词： Nonlinear equations

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Lower limit on the achievable temperature in resonator-based sideband cooling

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Physical Review B 2008年第3期78卷 035406-035406页

作者： M. Grajcar S. Ashhab J. R. Johansson Franco Nori Advanced Science Institute The Institute of Physical and Chemical Research (RIKEN) Wako-shi 351-0198 Japan Department of Experimental Physics Comenius University SK-84248 Bratislava Slovakia Center for Theoretical Physics Physics Department Applied Physics Program Center for the Study of Complex Systems The University of Michigan Ann Arbor Michigan 48109-1040 USA CREST Japan Science and Technology Agency (JST) Kawaguchi Saitama 332-0012 Japan

A resonator with eigenfrequency ωr can be effectively used as a cooler for another linear oscillator with a much smaller frequency ωm⪡ωr. A huge cooling effect, which could be used to cool a mechanical oscillator below the energy of quantum fluctuations, has been predicted by several authors. However, here we show that there is a lower limit T∗ on the achievable temperature, given by T∗=Tmωm/ωr, that was not considered in previous work and can be higher than the quantum limit in realistic experimental realizations. We also point out that the decay rate of the resonator, which previous studies stress should be small, must be larger than the decay rate of the cooled oscillator for effective cooling.

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Quantum simulation of materials at micron scales and beyond

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Physical Review B 2008年第5期78卷 054118-054118页

作者： Qing Peng Xu Zhang Linda Hung Emily A. Carter Gang Lu Department of Physics and Astronomy California State University Northridge Northridge California USA Program in Applied and Computational Mathematics Princeton University Princeton New Jersey USA Department of Mechanical and Aerospace Engineering Princeton University Princeton New Jersey USA

We present a multiscale modeling approach that can simulate multimillion atoms effectively via density-functional theory. The method is based on the framework of the quasicontinuum (QC) approach with orbital-free density-functional theory (OFDFT) as its sole energetics formulation. The local QC part is formulated by the Cauchy-Born hypothesis with OFDFT calculations for strain energy and stress. The nonlocal QC part is treated by an OFDFT-based embedding approach, which couples OFDFT nonlocal atoms to local region atoms. The method—QCDFT—is applied to a nanoindentation study of an Al thin film, and the results are compared to a conventional QC approach. The results suggest that QCDFT represents a new direction for the quantum simulation of materials at length scales that are relevant to experiments.

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Doping variation of anisotropic charge and orbital dynamics in Y1−xCaxVO3: Comparison with La1−xSrxVO3

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Physical Review B 2008年第14期77卷 144402-144402页

作者： J. Fujioka S. Miyasaka Y. Tokura Department of Applied Physics University of Tokyo Tokyo 113-8656 Japan Department of Physics University of Osaka Osaka 560-0043 Japan ERATO-Multiferroics Project Japan Science and Technology Agency Tsukuba 305-8562 Japan Cross-Correlation Materials Research Program (CMRG) RIKEN Wako 351-0198 Japan

The doping variation of charge and orbital dynamics in perovskite-type Y1−xCaxVO3 (0≤x≤0.1) is investigated by measurements of the optical conductivity and Raman scattering spectra in comparison to the larger bandwidth system La1−xSrxVO3. We also take into consideration the magnitude of the GdFeO3-type orthorhombic lattice distortion, which is large and small in Y1−xCaxVO3 and La1−xSrxVO3, respectively, and discuss its effect on the evolution of charge dynamics. The optical conductivity spectra show that the doped hole is well localized and forms the small polaronlike state. The hole dynamics in Y1−xCaxVO3 is nearly isotropic up to the doping level of the orbital order-disorder transition, while that in La1−xSrxVO3 is anisotropic in the lightly doped region due to the one-dimensional orbital exchange interaction. The possible origin of the difference in the hole dynamics is discussed in terms of the local lattice distortion, which is induced by the formation of the small polaronlike state and becomes more significant for the reduced one-electron bandwidth. In addition, the optical Mott-gap excitation in the nominally C-type spin and G-type orbital ordered phase is distinct from that for La1−xSrxVO3 in its intensity and spectral shape. This suggests that the orthorhombic lattice distortion enhances the modification of the spin and orbital ordering from the pure C type and G type, respectively. The systematic study of Raman scattering spectra has shown that the dynamic G-type spin and C-type orbital correlation subsists at low temperatures in the doping induced phase of the nominally C-type spin ordering and G-type orbital ordering.

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Nonlinear electrodynamics in layered superconductors

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Physical Review B 2008年第2期78卷 024511-024511页

作者： V. A. Yampol’skii Sergey Savel’ev A. L. Rakhmanov Franco Nori Advanced Science Institute The Institute of Physical and Chemical Research (RIKEN) Wako-shi Saitama 351-0198 Japan A. Ya. Usikov Institute for Radiophysics and Electronics Ukrainian Academy of Sciences 61085 Kharkov Ukraine Department of Physics Loughborough University Loughborough LE11 3TU United Kingdom Institute for Theoretical and Applied Electrodynamics Russian Academy of Sciences 125412 Moscow Russia Department of Physics Center for Theoretical Physics Applied Physics Program Center for the Study of Complex Systems The University of Michigan Ann Arbor Michigan 48109-1040 USA

We analyze theoretically the effect of a weak nonlinearity on the propagation of Josephson plasma waves in layered superconductors. The nonlinearity originates from the Josephson relation between the current density across superconducting layers and gauge-invariant phase difference of the order parameter. We show that strong nonlinear effects can be observed for electromagnetic waves with frequency slightly above or slightly below the plasma frequency. We study the nonlinear plasma resonance accompanied by the hysteretic dependence of the wave amplitude on the frequency. This hysteresis transforms the continuous terahertz radiation into a series of short electromagnetic high-amplitude pulses. We also consider the propagation of a nonlinear terahertz beam localized in the direction across the superconducting layers. This phenomenon is an analog of the self-focusing effect in nonlinear optics. The nonlinear phenomena in layered superconductors considered here can be potentially useful for the design of a new generation of terahertz devices.

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Simulated fiber-optic interrogation of autofluorescence from superficial layer of tissue-engineered construct

Simulated fiber-optic interrogation of autofluorescence from...

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Frontiers in Optics, FiO 2008

作者： Wilson, Robert H. Chandra, Malavika Lo, Wen-Liang Vishwanath, Karthik Izumi, Kenji Feinberg, Stephen E. Myceka, Mary-Ann Applied Physics Program University of Michigan Ann Arbor MI 48109-2099 United States Oral and Maxillofacial Surgery University of Michigan Ann Arbor MI 48109-2099 United States Dept. of Biomedical Engineering University of Michigan Ann Arbor MI 48109-2099 United States Comprehensive Cancer Center University of Michigan Ann Arbor MI 48109-2099 United States

Monte Carlo simulations were used to predict optimal fiber-optic probe configurations for selectively interrogating autofluorescence from the superficial (50 m) middle layer of a tissue-engineered construct with a dif... 详细信息

ISBN: (纸本)9781557528612

关键词： Monte Carlo methods

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Monte carlo simulations of Raman scattering from bone within a multi-layered tissue model

Monte carlo simulations of Raman scattering from bone within...

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Frontiers in Optics, FiO 2008

作者： Wilson, Robert H. Morris, Michael D. Mycek, Mary-Ann Applied Physics Program University of Michigan Ann Arbor MI 48109-2099 United States Dept. of Chemistry University of Michigan Ann Arbor MI 48109-2099 United States Dept. of Biomedical Engineering University of Michigan Ann Arbor MI 48109-2099 United States Comprehensive Cancer Center University of Michigan Ann Arbor MI 48109-2099 United States

A Monte Carlo model of photon transport in layered biological tissue predicted the detected Raman signal from an underlying bone layer. Simulations quantified the effect of each tissue layer's optical properties o... 详细信息

ISBN: (纸本)9781557528612

关键词： Monte Carlo methods

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The effects of electric forces on dust lifting: Preliminary studies with a numerical model

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Journal of physics: Conference Series 2008年第1期142卷

作者： Kok, J.F. Renno, N.O. Applied Physics Program University of Michigan Ann Arbor 48109 MI United States Atmospheric Oceanic Space Sciences University of Michigan Ann Arbor MI United States Atmospheric Oceanic and Planetary Physics University of Oxford Oxford United Kingdom

Atmospheric dust aerosols affect the Earth's climate by scattering and absorbing radiation and by modifying cloud properties. Recent experiments have indicated that electric fields produced in dusty phenomena such as dust storms and dust devils could enhance the emission of dust aerosols. However, the generation of electric fields in dusty phenomena is poorly understood. To address this problem, we present results from the first physically-based numerical model of electric fields in dust lifting. Our model calculates the motion and collisions of air-borne particles, as well as the charge transfer during these collisions. This allows us to simulate the formation of electric fields as a function of physical parameters, such as wind stress and soil properties. Preliminary model results show that electric fields can indeed enhance the lifting of soil particles. Moreover, they suggest that strong electric fields could trigger a positive feedback because increases in the concentration of charged particles strengthen the original electric field, which in turn lifts additional surface particles. We plan to further test and calibrate our model with experimental data. © 2008 IOP Publishing Ltd.

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Optimized Structures for Photonic Quasicrystals

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Physical Review Letters 2008年第7期101卷 073902-073902页

作者： Mikael C. Rechtsman Hyeong-Chai Jeong Paul M. Chaikin Salvatore Torquato Paul J. Steinhardt Department of Physics Princeton University Princeton New Jersey 08544 USA Department of Physics Sejong University Gwangjin-gu Seoul 143-747 Korea Department of Physics and Center for Soft Condensed Matter Research New York University New York 10003 USA Department of Chemistry Princeton University Princeton New Jersey 08544 USA Program in Applied and Computational Mathematics and PRISM Princeton New Jersey 08544 USA Princeton Center for Theoretical Physics Princeton New Jersey 08544 USA School of Natural Sciences Institute for Advanced Study Princeton New Jersey 08544 USA

A photonic quasicrystal consists of two or more dielectric materials arranged in a quasiperiodic pattern with noncrystallographic symmetry that has a photonic band gap. We use a novel method to find the pattern with the widest TM-polarized gap for two-component materials. Patterns are obtained by computing a finite sum of density waves, assigning regions where the sum exceeds a threshold to a material with one dielectric constant, ϵ1, and all other regions to another, ϵ0. Compared to optimized crystals, optimized quasicrystals have larger gaps at low constrasts ϵ1/ϵ0 and have gaps that are much more isotropic for all contrasts. For high contrasts, optimized hexagonal crystals have the largest gaps.

关键词： Quasicrystals

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