2,103 research outputs found

    Another exact solution for two-dimensional, inviscid sinh Poisson vortex arrays

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    Arrays of vortices are considered for two-dimensional, inviscid flows when the functional relationship between the stream function and the vorticity is a hyperbolic sine. An exact solution as a doubly periodic array of vortices is expressed in terms of the Jacobi elliptic functions. There is a threshold value of the period parameter such that a transition from globally smooth distributions of vorticity to singular distributions occurs. © 2003 American Institute of Physics.published_or_final_versio

    Texture and chemical composition analyses on the Hg0.66Pb0.33Ba2Ca2Cu3Oy superconductor using the sealed quartz tube technique

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    Pb-substituted Hg-based superconductor of Hg0.66Pb0.33Ba2Ca2Cu3Oy has been fabricated using the sealed quartz tube technique. R-T and x-ray diffraction pattern (XDP) measurements show that the specimen has a Tc of 135 K and contains mainly the Hg-1223 phase. Scanning electron microscopy/energy dispersive x-ray analysis (SEM/EDX) and transmission electron microscopy/energy dispersive x-ray analysis (TEM/EDX) were employed to study the texture and chemical composition of the specimen. It is found that the specimen contains round-shaped grains with a mixture of Hg-1223, BaCuO2, and Ca0.85CuO2 phases, square-shaped grains with a formula of PbBa2O3, small single crystals with single Hg-1223 phase, and crystal-like layers with a mixture of Hg-1223 and BaCuO2 phase. We consider that though the doping of Pb can benefit the stabilization of the Hg-1223 phase, it introduces other impurity phases and textures in the specimen at the same time.published_or_final_versio

    Prevalence of Psychological Problems in Chinese Peritoneal Dialysis Patients

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    Coronavirus HKU15 in respiratory tract of pigs and first discovery of coronavirus quasispecies in 5′-untranslated region

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    Graphene-deposited photonic crystal fibers for continuous refractive index sensing applications

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    © 2015 Optical Society of America. We present a pilot demonstration of an optical fiber based refractive index (RI) sensor involving the deposition of graphene onto the surface of a segment of a photonic crystal fiber (PCF) in a fiber-based Mach-Zehnder Interferometer (MZI). The fabrication process is relatively simple and only involves the fusion splicing of a PCF between two single mode fibers. The deposition process relies only on the cold transfer of graphene onto the PCF segment, without the need for further physical or chemical treatment. The graphene overlay modified the sensing scheme of the MZI RI sensor, allowing the sensor to overcome limitations to its detectable RI range due to free spectral range issues. This modification also allows for continuous measurements to be obtained without the need for reference values for the range of RIs studied and brings to light the potential for simultaneous dual parameter sensing. The sensor was able to achieve a RI sensitivity of 9.4 dB/RIU for the RIs of 1.33-1.38 and a sensitivity of 17.5 dB/RIU for the RIs of 1.38-1.43. It also displayed good repeatability and the results obtained were consistent with the modeling

    Continuous refractive index sensing based on carbon-nanotube-deposited photonic crystal fibers

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    We present a carbon nanotubes (CNTs) deposited photonic crystal fiber (PCF) featuring a Mach-Zehnder interferometer configuration for refractive index (RI) sensing applications. The high RI of the CNTs deposited on the surface of the PCF not only enhances the interaction of the evanescent waves of the cladding modes with the ambient environment around the fiber, but also modifies the sensing scheme to that of intensity variations. Such a modification makes the sensor susceptible to power fluctuations from the optical source but allows the sensor to gain immunity to free spectral range limitations which is commonly found in PCF-based sensors. As such continuous and repeatable measurements can be obtained for the range of RIs being measured. The sensor registered a sensitivity of 19.4 dB/RIU within the RI range of 1.33 to 1.38 and a sensitivity of 24.2 dB/RIU within the RI range of 1.38 to 1.42. Since there is no mechanical modification of the overall structure of the sensing element, the fiber retains its mechanical strength which makes it viable for practical applications. The experimental results are found to be consistent with the modeling of the sensor's behavior. © 2014 Elsevier B.V
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