The Experts below are selected from a list of 99831 Experts worldwide ranked by ideXlab platform

Steven B Giddings - One of the best experts on this subject based on the ideXlab platform.

  • astronomical tests for quantum black Hole Structure
    arXiv: General Relativity and Quantum Cosmology, 2017
    Co-Authors: Steven B Giddings
    Abstract:

    Quantum modifications to black Holes on scales comparable to the horizon size, or even more radical physics, are apparently needed to reconcile the existence of black Holes with the principles of quantum mechanics. This piece gives an overview of some possible observational tests for such departures from a classical description of black Holes, via gravitational wave detection and very long baseline interferometry. (Invited comment for Nature Astronomy.)

  • astronomical tests for quantum black Hole Structure
    Nature Astronomy, 2017
    Co-Authors: Steven B Giddings
    Abstract:

    Black Holes present a profound challenge to our current foundations of physics, and an exciting era of astronomy is just opening in which gravitational-wave observation and very-long-baseline interferometry may provide important hints about the new principles of physics needed.

  • gravitational wave tests of quantum modifications to black Hole Structure with post gw150914 update
    Classical and Quantum Gravity, 2016
    Co-Authors: Steven B Giddings
    Abstract:

    A preliminary discussion is given of the prospects that gravitational-wave observations of binary inspiral of black Holes (BHs) could reveal or constrain quantum modifications to BH dynamics, such as are required to preserve postulates of quantum mechanics. Different proposals for such modifications are characterized by different scales, and the size of these scales relative to those probed by observation of inspiral signals is important in determining the feasibility of finding experimental signatures. Certain scenarios with strong quantum modifications in a region extending well outside the horizon are expected to modify classical evolution, and distort the near-peak gravitational wave signal, suggesting a search for departures from waveforms predicted by general relativity. The near agreement of the GW150914 signal with such waveforms is discussed, and indicates constraints on some such scenarios. Important strategies for more precise future tests are (1) to develop more precise predictions from scenarios proposing quantum modifications, and (2) searching for observed deviations from numerical relativity predictions via analysis of gravity wave data, particularly focussing on the signal region corresponding to plunge and merger.

  • gravitational wave tests of quantum modifications to black Hole Structure with post gw150914 update
    arXiv: General Relativity and Quantum Cosmology, 2016
    Co-Authors: Steven B Giddings
    Abstract:

    A preliminary discussion is given of the prospects that gravitational-wave observations of binary inspiral of black Holes could reveal or constrain quantum modifications to black Hole dynamics, such as are required to preserve postulates of quantum mechanics. Different proposals for such modifications are characterized by different scales, and the size of these scales relative to those probed by observation of inspiral signals is important in determining the feasibility of finding experimental signatures. Certain scenarios with strong quantum modifications in a region extending well outside the horizon are expected to modify classical evolution, and distort the near-peak gravitational wave signal, suggesting a search for departures from waveforms predicted by general relativity. The near agreement of the GW150914 signal with such waveforms is discussed, and indicates constraints on some such scenarios. Important strategies for more precise future tests are 1) to develop more precise predictions from scenarios proposing quantum modifications, and 2) searching for observed deviations from numerical relativity predictions via analysis of gravity wave data, particularly focussing on the signal region corresponding to plunge and merger.

Di Zhang - One of the best experts on this subject based on the ideXlab platform.

  • a low cost high efficiency light absorption Structure inspired by the papilio ulysses butterfly
    RSC Advances, 2017
    Co-Authors: Wang Zhang, Di Zhang, Guo Ping Wang
    Abstract:

    The nano-Hole array Structure in the black scales of the butterfly can be viewed as a natural solar collector. A low-cost, high-efficiency light absorption Structure, inspired by the Papilio ulysses butterfly, was optimized using a finite-difference time-domain method. The results show that the nano-Hole Structure of Papilio ulysses contributes to light absorption. The shape of the Holes affects the angular dependence of absorption. The absorption efficiency was found to be strongly affected by three parameters: H (the depth of the Hole), D (the thickness of the Hole-wall) and L (the size of the Hole). These parameters were swept together in numerous simulations. The optimized nano-Hole array saves 84% more material than a thin film of equal absorption (90%) at a wavelength of 600 nm.

  • omnidirectional light absorption of disordered nano Hole Structure inspired from papilio ulysses
    Optics Letters, 2014
    Co-Authors: Wang Zhang, Xiaotian Fang, Yiqiao Huang, Di Zhang
    Abstract:

    Butterflies routinely produce nanoStructured surfaces with useful properties. Here, we report a disordered nano-Hole Structure with ridges inspired by Papilio ulysses that produce omnidirectional light absorption compared with the common ordered Structure. The result shows that the omnidirectional light absorption is affected by polarization, the incident angle, and the wavelength. Using the finite-difference time-domain (FDTD) method, the stable omnidirectional light absorption is achieved in the Structure inspired from the Papilio ulysses over a wide incident angle range and with various wavelengths. This explains some of the mysteries of the Structure of the Papilio ulysses butterfly. These conclusions can guide the design of omnidirectional absorption materials.

Wang Zhang - One of the best experts on this subject based on the ideXlab platform.

  • a low cost high efficiency light absorption Structure inspired by the papilio ulysses butterfly
    RSC Advances, 2017
    Co-Authors: Wang Zhang, Di Zhang, Guo Ping Wang
    Abstract:

    The nano-Hole array Structure in the black scales of the butterfly can be viewed as a natural solar collector. A low-cost, high-efficiency light absorption Structure, inspired by the Papilio ulysses butterfly, was optimized using a finite-difference time-domain method. The results show that the nano-Hole Structure of Papilio ulysses contributes to light absorption. The shape of the Holes affects the angular dependence of absorption. The absorption efficiency was found to be strongly affected by three parameters: H (the depth of the Hole), D (the thickness of the Hole-wall) and L (the size of the Hole). These parameters were swept together in numerous simulations. The optimized nano-Hole array saves 84% more material than a thin film of equal absorption (90%) at a wavelength of 600 nm.

  • omnidirectional light absorption of disordered nano Hole Structure inspired from papilio ulysses
    Optics Letters, 2014
    Co-Authors: Wang Zhang, Xiaotian Fang, Yiqiao Huang, Di Zhang
    Abstract:

    Butterflies routinely produce nanoStructured surfaces with useful properties. Here, we report a disordered nano-Hole Structure with ridges inspired by Papilio ulysses that produce omnidirectional light absorption compared with the common ordered Structure. The result shows that the omnidirectional light absorption is affected by polarization, the incident angle, and the wavelength. Using the finite-difference time-domain (FDTD) method, the stable omnidirectional light absorption is achieved in the Structure inspired from the Papilio ulysses over a wide incident angle range and with various wavelengths. This explains some of the mysteries of the Structure of the Papilio ulysses butterfly. These conclusions can guide the design of omnidirectional absorption materials.

Alexey M Lomonosov - One of the best experts on this subject based on the ideXlab platform.

  • numerical and experimental study of lamb wave propagation in a two dimensional acoustic black Hole
    Journal of Applied Physics, 2016
    Co-Authors: Alexey M Lomonosov, Zhonghua Shen
    Abstract:

    The propagation of laser-generated Lamb waves in a two-dimensional acoustic black-Hole Structure was studied numerically and experimentally. The geometrical acoustic theory has been applied to calculate the beam trajectories in the region of the acoustic black Hole. The finite element method was also used to study the time evolution of propagating waves. An optical system based on the laser-Doppler vibration method was assembled. The effect of the focusing wave and the reduction in wave speed of the acoustic black Hole has been validated.

Masahiro Nomura - One of the best experts on this subject based on the ideXlab platform.

  • crystal Structure dependent thermal conductivity in two dimensional phononic crystal nanoStructures
    Applied Physics Letters, 2015
    Co-Authors: Junki Nakagawa, Yuta Kage, Takuma Hori, Junichiro Shiomi, Masahiro Nomura
    Abstract:

    Thermal phonon transport in square- and triangular-lattice Si phononic crystal (PnC) nanoStructures with a period of 300 nm was investigated by measuring the thermal conductivity using micrometer-scale time-domain thermoreflectance. The placement of circular nanoHoles has a strong influence on thermal conductivity when the periodicity is within the range of the thermal phonon mean free path. A staggered Hole Structure, i.e., a triangular lattice, has lower thermal conductivity, where the difference in thermal conductivity depends on the porosity of the Structure. The largest difference in conductivity of approximately 20% was observed at a porosity of around 30%. This crystal Structure dependent thermal conductivity can be understood by considering the local heat flux disorder created by a staggered Hole Structure. Numerical simulation using the Monte Carlo technique was also employed and also showed the lower thermal conductivity for a triangular lattice Structure. Besides gaining a deeper understanding ...

  • crystal Structure dependent thermal conductivity in two dimensional phononic crystal nanoStructures
    arXiv: Mesoscale and Nanoscale Physics, 2015
    Co-Authors: Junki Nakagawa, Yuta Kage, Takuma Hori, Junichiro Shiomi, Masahiro Nomura
    Abstract:

    Thermal phonon transport in square- and triangular-lattice Si phononic crystal (PnC) nanoStructures with a period of 300 nm was investigated by measuring the thermal conductivity using micrometer-scale time-domain thermoreflectance. The placement of circular nanoHoles has a strong influence on thermal conductivity when the periodicity is within the range of the thermal phonon mean free path. A staggered Hole Structure, i.e., a triangular lattice, has lower thermal conductivity, where the difference in thermal conductivity depends on the porosity of the Structure. The largest difference in conductivity of approximately 20% was observed at a porosity of around 30%. This crystal Structure dependent thermal conductivity can be understood by considering the local heat flux disorder created by a staggered Hole Structure. Numerical simulation using the Monte Carlo technique was also employed and also showed the lower thermal conductivity for a triangular lattice Structure. Besides gaining a deeper understanding of nanoscale thermal phonon transport, this information would be useful in the design of highly efficient thermoelectric materials created by nanopatterning.