470 research outputs found
A portable triaxial cell for beamline imaging of rocks under triaxial state of stress
Acknowledgements The development of the cell was supported by the Research and Teaching Excellence Fund of the School of Engineering, University of Aberdeen. Experiments at BT2, NCNR were supported by UK Engineering and Physical Sciences Research Council grant number EP/N021665/1, NIST and the Physical Measurement Laboratory. Experiments at IMAT were supported by the UK STFC, Experiment number: 1910331 (https://doi.org/10.5286/ISIS.E.RB1910331).Peer reviewedPublisher PD
Laboratory investigation of lateral dispersion within dense arrays of randomly distributed cylinders at transitional Reynolds number
Published versio
Comparative Studies on Short and Long Length-Scale Stall Cell Propagation in an Axial Compressor Rotor
Abstract In a low-speed compressor test rig at Kyushu University, multiple short length-scale stall cells appeared under a mild stall condition and turned into a long length-scale cell under a deep stall condition. Then, for the both types of stall cell, the pressure distribution on the casing wall and the velocity distributions upstream and downstream of the rotor have been measured by high response pressure transducers and a slanted hot-wire, respectively. The time-dependent ensemble averages of these distributions have been obtained phase-locking to both of the rotor and the stall cell rotation by using a so-called 'double phase-locked averaging technique' developed by the authors. Structure of the two stall cells are compared with each other: The short length-scale stall cell is characterized by a concentrated vortex spanning from the casing wall ahead of the rotor to the blade suction surface. In the long length-scale stall cell, the separation vortices go upstream irregularly when blade separation develops in the front half of the cell, and reenter the rotor on the hub side in the rear half of it. The unsteady aerodynamic force and torsional moment acting on the blade tip section have been evaluated from the time-dependent ensemble averages of the casing wall pressure distribution. The force fluctuation due to the short length-scale cells is somewhat smaller than that for the long length-scale cell. The blade suffers two peaks of the force during a period of the short length-scale cells passing through it. The moment fluctuation for the short length-scale cells is considerably larger than that for the long length-scale cell
Theory of the beta-type Organic Superconductivity under Uniaxial Compression
We study theoretically the shift of the superconducting transition
temperature (Tc) under uniaxial compression in beta-type organic
superconductors, beta-(BEDT-TTF)2I3 and beta-(BDA-TTP)2X[X=SbF6,AsF6], in order
to clarify the electron correlation, the spin frustration and the effect of
dimerization. The transfer integrals are calculated by the extended Huckel
method assuming the uniaxial strain and the superconducting state mediated by
the spin fluctuation is solved using Eliashberg's equation with the
fluctuation-exchange approximation. The calculation is carried out on both the
dimerized (one-band) and nondimerized (two-band) Hubbard models. We have found
that (i) the behavior of Tc in beta-(BEDT-TTF)2I3 with a stronger dimerization
is well reproduced by the dimer model, while that in weakly dimerized
beta-BDA-TTP salts is rather well reproduced by the two-band model, and (ii)
the competition between the spin frustration and the effect induced by the
fluctuation is important in these materials, which causes nonmonotonic shift of
Tc against uniaxial compression.Comment: 18 pages, 16 figures, 2 tabl
A review of plant-flow interactions on salt marshes: the importance of vegetation structure and plant mechanical characteristics
Observations of plant-flow interactions on salt marshes have revealed a highly complex process dominated by the tightly coupled effects of plant characteristics and hydrodynamic conditions. This paper highlights the importance of vegetation structures such as plant density and height, as well as their spatial variability and mechanical properties including flexibility, upon energy dissipation and flow modification. Many field, laboratory and modelling studies which attempt to predict flow dissipation or improve our understanding of plant-flow interactions use simplified structural measures of salt marsh vegetation or artificial representations. These simplifications neglect important plant and canopy elements and are unlikely to be truly representative of their natural counterparts. Such approaches limit our understanding of plant-flow interactions and potentially compromise the predictive accuracy and application of numerical flow models. It is important therefore that improved techniques to measure vegetation structure are adopted in order to better define the key relationships between measurable plant characteristics and drag-relevant plant properties.This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1002/wat2.110
Evidence for Modification of the Electronic Density-of-States by Zero-Point Lattice Motion in One-Dimension - Luminescence and Resonance Raman Studies of An Mx Solid
Luminescence spectra, both emission and excitation, and the excitation dependence of the resonance Raman spectra, have been measured for the quasi-one-dimensional charge-density-wave material [Pt(en)2][Pt(en)2Cl2](ClO4)4, en = 1,2-diaminoethane. While the luminescence experiments show the existence of tail states at low temperature in the band gap region, the Raman measurements conclusively demonstrate that this tail does not arise from ordinary static structural disorder. These results can be explained by considering the zero-point motion of the lattice
Pressure Tuning of the Charge Density Wave in the Halogen-Bridged Transition-Metal (MX) Solid
We report the pressure dependence up to 95 kbar of Raman active stretching
modes in the quasi-one-dimensional MX chain solid . The data
indicate that a predicted pressure-induced insulator-to-metal transition does
not occur, but are consistent with the solid undergoing either a
three-dimensional structural distortion, or a transition from a charge-density
wave to another broken-symmetry ground state. We show that such a transition
cacan be well-modeled within a Peierls-Hubbard Hamiltonian. 1993 PACS:
71.30.+h, 71.45.Lr, 75.30.Fv, 78.30.-j, 81.40.VwComment: 4 pages, ReVTeX 3.0, figures available from the authors on request
(Gary Kanner, [email protected]), to be published in Phys Rev B Rapid
Commun, REVISION: minor typos corrected, LA-UR-94-246
Efficiency Assessment of Using Flammable Compounds from Water Treatment and Methanol Production Waste for Plasma Synthesis of Iron-Containing Pigments
This article describes the possibility of applying the low-temperature plasma for obtaining iron-containing pigments from water purification and flammable methanol production waste. In this paper were calculated combustion parameters of water-saltorganic compositions (WSOC) with different consists. Authors determined the modes of energy- efficient processing of the previously mentioned waste in an air plasma. Having considered the obtained results there were carried out experiments with flammable dispersed water-saltorganic compositions on laboratory plasma stand. All the experimental results are confirmed by calculations
Set optimization - a rather short introduction
Recent developments in set optimization are surveyed and extended including
various set relations as well as fundamental constructions of a convex analysis
for set- and vector-valued functions, and duality for set optimization
problems. Extensive sections with bibliographical comments summarize the state
of the art. Applications to vector optimization and financial risk measures are
discussed along with algorithmic approaches to set optimization problems
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