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  • 1
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    Effects of solution volume on hydrogen production by pulsed spark discharge in ethanol solution (2016)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2016-07-15
    Description: Hydrogen production from ethanol solution (ethanol/water) by pulsed spark discharge was optimized by varying the volume of ethanol solution (liquid volume). Hydrogen yield was initially increased and then decreased with the increase in solution volume, which achieved 1.5 l/min with a solution volume of 500 ml. The characteristics of pulsed spark discharge were studied in this work; the results showed that the intensity of peak current, the rate of current rise, and energy efficiency of hydrogen production can be changed by varying the volume of ethanol solution. Meanwhile, the mechanism analysis of hydrogen production was accomplished by monitoring the process of hydrogen production and the state of free radicals. The analysis showed that decreasing the retention time of gas production and properly increasing the volume of ethanol solution can enhance the hydrogen yield. Through this research, a high-yield and large-scale method of hydrogen production can be achieved, which is more suitable for industrial application.
    Print ISSN: 1070-664X
    Electronic ISSN: 1089-7674
    Topics: Physics
    Published by American Institute of Physics (AIP)
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  • 2
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    Understanding electrofreezing in water simulations (2014)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2014-08-16
    Description: Molecular dynamics simulations are used to investigate why external electric fields promote the freezing of liquid water models. It is shown that the melting point of water at a pressure of 1 bar increases significantly when water is polarized by a uniform field. Fields of 1 V/nm and 2 V/nm increase the melting point by 24 K and 44 K, respectively. The increased melting point is mainly due to the favorable interaction of near perfectly polarized cubic ice with the applied field. For a fixed temperature, we demonstrate that the size of the critical ice nucleus decreases with field strength, mostly because the melting point, and hence the true degree of supercooling, is increasing with field. On simulation timescales, ice nucleation is observed at ∼40 K below the field-dependent melting point, independent of the particular value of the field applied. Indeed, we find that even quite highly polarized liquid water retains the characteristic local structures, and the related anomalous properties of water. Our results are obviously relevant to the mechanism of heterogeneous ice nucleation by local surface fields. Local fields will effectively increase the degree of supercooling of locally polarized liquid, decreasing the size of the critical nucleus in the region influenced by the field, hence facilitating ice nucleation.
    Print ISSN: 0021-9606
    Electronic ISSN: 1089-7690
    Topics: Chemistry and Pharmacology , Physics
    Published by American Institute of Physics (AIP)
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  • 3
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    Seismic isolation of two dimensional periodic foundations (2014)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2014-08-01
    Description: Phononic crystal is now used to control acoustic waves. When the crystal goes to a larger scale, it is called periodic structure. The band gaps of the periodic structure can be reduced to range from 0.5 Hz to 50 Hz. Therefore, the periodic structure has potential applications in seismic wave reflection. In civil engineering, the periodic structure can be served as the foundation of upper structure. This type of foundation consisting of periodic structure is called periodic foundation. When the frequency of seismic waves falls into the band gaps of the periodic foundation, the seismic wave can be blocked. Field experiments of a scaled two dimensional (2D) periodic foundation with an upper structure were conducted to verify the band gap effects. Test results showed the 2D periodic foundation can effectively reduce the response of the upper structure for excitations with frequencies within the frequency band gaps. When the experimental and the finite element analysis results are compared, they agree well with each other, indicating that 2D periodic foundation is a feasible way of reducing seismic vibrations.
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
    Published by American Institute of Physics (AIP)
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  • 4
    Electronic Resource
    Electronic Resource
    Pulse shaping and coherent Raman spectroscopy in condensed phases (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 997-1005 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A microscopic theory for ultrafast coherent Raman spectroscopy of polyatomic molecules in condensed phases is developed. For off resonant excitation, an effective Hamiltonian that controls the molecular dynamics in a Raman process is derived. The limitations of the driven oscillator model are clarified, and generalized equations of motion, which hold for resonant and off resonant excitation, are derived. Spectral selectivity using pulse shaping is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459938
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  • 5
    Electronic Resource
    Electronic Resource
    Dynamic light scattering from concentrated water-in-oil microemulsions: The coupling of optical and size polydispersity (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 4501-4509 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Dynamic light scattering from highly concentrated colloidal systems with a narrow distribution of particle sizes can be interpreted in terms of the sum of two independent modes due, respectively, to collective diffusion and polydispersity fluctuations; a general formalism has been presented for calculating the relative mode amplitudes for hard spheres in the Percus–Yevick approximation [Pusey, Fijnaut, and Vrij, J. Chem. Phys. 77, 4270(1982)]. This work extends the relative mode amplitude calculation to the general case where optical (i.e., refractive index) and size polydispersity are completely coupled such as in water-in-oil microemulsions. To develop the theory a concentric core-shell hard sphere model is adopted, in which particles possess a continuous variation in the core sizes but have constant shell thickness, thus giving rise to a distribution in the particle refractive indices. A new "measured'' static structure factor SM(0) is derived, and applied to the calculation for the relative amplitude of the slow mode, A2/(A1+A2), as a function of solvent refractive index n0. A strong enhancement of the slow mode is predicted as the optical matching point is approached. The theory also shows that the dependence of A2/(A1+A2) on n0 is very sensitive to the extent of polydispersity, but rather insensitive to the distribution function used. Neglect of the nonuniformity in particle refractive index can cause a substantial overestimate of the size polydispersity. We have used our extended treatment to interpret the dynamic light scattering data from concentrated water-in-oil microemulsions formed from H2O, AOT, and apolar solvents using solvent composition to control the contrast in refractive index. It is found that the AOT-stabilized water microemulsion droplets have a size polydispersity of about 6.5%, which is smaller than previously thought.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458690
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  • 6
    Electronic Resource
    Electronic Resource
    Identification of Pb-doped Bi-Sr-Ca-Cu-O superconducting phases by convergent beam electron diffraction (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 280-282 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Pb-doped Bi2Sr2Ca2Cu3O10 (2223) and Bi2 Sr2 Ca3 Cu4 O12 (2234) superconducting phases have been identified by convergent beam electron diffraction. The c parameters of the 2223 and 2234 phases are 37.6 and 44 A(ring), respectively. The two phases have the same symmetry; their common point group is mmm. Both phases are modulated, but the modulations are different from and considerably weaker than that in the unleaded Bi2 Sr2 CaCu2 O8 . This work confirms for the first time the existence of the 2234 phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102386
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  • 7
    Electronic Resource
    Electronic Resource
    Structural study of undoped and doped Bi2Sr2CuO6 phases by transmission electron microscopy (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2775-2777 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Bi-based superconducting phases have been studied by transmission electron microscopy. The strong one-dimensional modulations in undoped and Ce-doped monoclinic Bi2 Sr2 CuO6 (2201) samples are different from one another. We have found a new 2201 phase containing Pb and Ca with orthorhombic symmetry in nominal (Bi0.90 Pb0.10 )2 Sr2 CaCu2 O8 crystals. Its structure with space group Bbmb and two-dimensional modulation are analogous to those of the Pb-doped higher members of the structural series Bi2 Sr2 Can−1 Cun O2n+4 . Hence, this new orthorhombic rather than the monoclinic 2201 phase should be the first member of the structural series.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102371
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  • 8
    Electronic Resource
    Electronic Resource
    Polytypoid structures in annealed In2O3–ZnO films (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2585-2587 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Atomic-resolution Z-contrast images demonstrate unambiguously that the annealed, metalorganic chemical vapor deposition derived transparent In2O3–ZnO films have a polytypoid microstructure, consisting of ZnO slabs of variable width separated by single In–O octahedral layers. These In–O layers induce a polarity inversion in the two adjacent ZnO layers, which is reversed again by a mirror domain boundary inside each ZnO slab. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122513
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  • 9
    Electronic Resource
    Electronic Resource
    The effect of a magnetic underlayer on the magnetic properties of plated Permalloy (abstract) : The 5th Joint MMM−Intermag Conference (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 5940-5940 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of a magnetic underlayer on the magnetic behavior of overlayer/underlayer combinations were investigated. Permalloy underlayers of 100 nm thickness and composition 82% Ni-18% Fe by weight were sputter deposited on 3-in.-diam Si substrates. Magnetic orientations of the underlayers were set at 0°, 45°, and 90° with respect to the orientation of a subsequently plated Permalloy (79%Ni-21%Fe overlayer. Several film combinations were generated on each of the various underlayer configurations with plated thicknesses ranging from 0.1 to 2.0 μm. Spatial maps of magnetic orientation and Hk for underlayers and underlayer/overlayer combinations were collected using a modified Kerr BH imager (Kerr BHI) designed from Gudeman.1 The maps covered a 5 cm×5 cm square region with 5 mm spacing between points. Comparison of the maps before and after plating shows a partial reduction in the measured Hk values for film systems with large underlayer/overlayer orientation differences. A uniform decline in the effect of the underlayer to the overall orientation direction as film thicknesses increase was also observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350085
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  • 10
    Electronic Resource
    Electronic Resource
    Analysis of free-electron lasing stimulated by a counterpropagating plasma wave (1989)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 1 (1989), S. 2495-2501 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A relativistic fluid theory is constructed to analyze the inverse Compton scattering of an unmagnetized counterpropagating plasma wave by a cold relativistic electron beam. A Langmuir wave and electromagnetic plasma wave wigglers are considered, and the properties of the two types of wigglers are comparatively discussed. The growth rates are comparable to those of the ac free-electron laser and the free-electron lasers with magnetostatic wigglers in the Raman regime.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.859184
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