Τμήμα Μηχανικών Μηχανολογίας και Κατασκευαστικής / Department of Mechanical and Manufacturing Engineering: Recent submissions
Now showing items 801-820 of 1036
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Article
Phonon and electron anomalies in the perovskite superconductor (La1.85Sr0.15)Cu0.95Sn0.05O4
(1987)Mössbauer measurements have been made at 199Sn in the perovskite superconductors La1.85Sr0.15Cu1-xSnxO4. The Sn valence is 4+ for all concentrations. The temperature dependence of the mean-squared displacement for x=0.05 ...
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Article
Multiple peaks in the ac susceptibility of untwinned Y-Ba-Cu-O single crystals: A manifestation of the peak effect
(1994)We have measured the ac susceptibility of several high quality twinned and detwinned YBa2Cu3O7- (YBCO) single crystals. We see multiple peaks in the (T) curves, and explain them as a manifestation of the peak effect in ...
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Article
Evidence of order-parameter symmetry and of a normal metallic state in electron-irradiated YBa2Cu3O7-8 (YBCO)
(1996)A key difference between a d-wave superconductor and an anisotropic s-wave one is the expected effect of nonmagnetic point defects on Tc. For the former, Tc becomes zero, whereas for the latter, Tc reaches a nonzero constant ...
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Article
Testing models of the symmetry of the superconducting pairing state by low-temperature electron irradiation of an untwinned single crystal of YBa2Cu3O7-
(1994)We have carried out in situ resistivity measurements in a high-voltage electron microscope to determine how the superconducting transition temperature Tc and the resistivity (T) change with low-temperature electron ...
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Article
Negative giant longitudinal magnetoresistance in NiMnSb InSb: Interface effect
(2006)We report on the electrical and magnetotransport properties of the contact formed between n -type degenerate InSb (100) substrates and polycrystalline NiMnSb thin films grown using pulsed laser deposition. Negative giant ...
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Article
Magneto-transport properties of NiMnSb thin films on InSb single crystals: Negative giant magnetoresistance
(2007)In this study we investigated the magneto-transport properties of the ohmic contact between polycrystal-line NiMnSb thin films grown by pulsed laser deposition and n-type degenerate InSb (100) substrates. An unusual negative ...
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Article
Effects of the Sapphire Nitridation on the Polarity and Structural Properties of GaN Layers Grown by Plasma-Assisted MBE
(2001)The nitridation of the (0001) sapphire surface by a nitrogen rf-plasma source used in GaN molecular beam epitaxy has been investigated. Auger electron spectroscopy measurements were used to estimate the extent of the ...
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Article
Perfusion quantification using dynamic contrast-enhanced ultrasound: The impact of dynamic range and gain on time–intensity curves
(2011)The objective of this study was to assess the impact of dynamic range and gain on perfusion quantification using linearized log-compressed data. An indicator-dilution experiment was developed with an in vitro flow phantom ...
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Article
A method for obtaining single domain superconducting YBa2Cu3O7-x single crystals
(1989)A method is reported for producing an orthorhombic YBa2Cu3O7-x single crystal comprised entirely of a single untwinned domain. The transformation from a polydomain to a single domain single crystal is carried out by applying ...
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Article
Pulsed-laser deposition of NiMnSb thin films at moderate temperatures
(2002)Thin films of the half-Heusler alloy NiMnSb, which is predicted by band-structure calculations to be a half-metallic ferromagnet, were grown on various substrates (Si and InAs) using pulsed-laser deposition. The growth ...
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Article
Influence of the nonmagnetic impurities on the spin-1 Heisenberg chain SrNi2V2O8 system
(2006)De-magnetization and heat capacity measurements on polycrystalline samples of SrNi2-xMgxV2O8 (x = 0 and 0.05) are reported. The magnetization data suggest that both compounds are S= 1 quasi one-dimensional Heisenberg ...
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Conference Object
Particle simulation of crystal growth and settling under variable gravity
(American Institute of Aeronautics and Astronautics Inc, AIAA, 1999)A model that describes crystal growth and motion is presented. The model is based on concept of the direct simulation Monte Carlo and molecular dynamics methods and includes spherical crystal particles, nutrients species ...
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Article
Recent advances in spintronics. Half-metal ferromagnets: Their role in spintronics
(2004)A review of recent advances in spintronics is presented. We report the structural, magnetic, electrical and thermal properties of the ferromagnetic half-Heusler alloy NiMnSb grown by arcmelting. The bulk material is used ...
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Possible use of the half-Hausler alloy NiMnSb in spintronics: Synthesis and physical properties of arc melted NiMnSb and of NiMnSb thin films grown on InSb by pulsed laser deposition
(2005)We report the growth of single-phase, stoichiometric polycrystalline thin films of the half-Heusler ferromagnet NiMnSb, predicted to be half-metallic, on single crystal (100) InSb substrates heated at 200 °C by pulsed laser ...
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Article
Structural, magnetic, and electrical properties of NiMnSb thin films grown on InSb by pulsed-laser deposition
(2004)We report the growth of single-phase, stoichiometric polycrystalline thin films of the half-Heusler ferromagnet NiMnSb, predicted to be half-metallic, on single crystal InSb (100) substrates heated at 200°C by pulsed laser ...
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Direct measurement of the anisotropy of the resistivity in the a-b plane of twin-free, single-crystal, superconducting YBa2Cu3O7-
(1990)We have measured the resistivity tensor in one nearly twin-free crystal and one twin-free crystal of YBa2Cu3O7-. The first crystal was grown with a large twin-free region. We removed the twins in the second crystal by ...
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Article
In-plane paraconductivity in a single crystal of superconducting YBa2Cu3O7-x
(1989)Resistivity measurements have been made in the a-b plane on a single-crystal sample of superconducting YBa2Cu3O7-x. The resistivity versus temperature curve shows a highly linear region between 150 and 240 K, with an upward ...
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Conference Object
Large eddy simulation of sediment transport for the pulsating flow past a cylinder over a horizontal bed
(International Society of Offshore and Polar Engineers, 2015)In the present work, the suspended, pulsating incompressible flow past a submerged cylinder was examined by means of Large Eddy Simulations (LES). A layer of sandy inertial particles was allowed to move between the cylinder ...
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Article
Near-monodisperse sodium polymethacrylates: Characterization by linear salt gradient anion-exchange chromatography
(2000)A family of six near-monodisperse homopolymers of sodium methacrylate (Mn = 1100, 3200, 5500, 7200, 14100, and 21000) is characterized by linear salt gradient anion-exchange chromatography. Although the retention times ...