25,030 research outputs found

    Analysis of Operating Principles and Flow Field Characteristics for a Diving Ballast Tank

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    Operating principle and flow field characteristics of a diving ballast tank for application in submerged vehicles were investigated in the present study. As understanding the complex changes in the interior air-water two-phase flow field of the ballast tank during the diving process is difficult, this study specifically performed a ballast tank diving experiment. Experimental and numerical simulations to analyse the diving motions of the ballast tank were conducted. Authors comprehensively evaluated the flow field changes in the ballast tank and its surroundings. The experimental and numerical results were compared in terms of the observed displacements and velocities during diving. Both the results indicated similar motion trajectories and velocities. Authors effectively observed the air-water two-phase flow field change inside the ballast tank using this numerical method. Therefore, the numerical model constructed in this study can be useful for analysing the diving motions of ballast tanks and can effectively predict the interior flow field characteristics of a ballast tank

    The induced representations of Brauer algebra and the Clebsch-Gordan coefficients of SO(n)

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    Induced representations of Brauer algebra Df(n)D_{f}(n) from Sf1×Sf2S_{f_{1}}\times S_{f_{2}} with f1+f2=ff_{1}+f_{2}=f are discussed. The induction coefficients (IDCs) or the outer-product reduction coefficients (ORCs) of Sf1×Sf2↑Df(n)S_{f_{1}}\times S_{f_{2}}\uparrow D_{f}(n) with f≤4f\leq 4 up to a normalization factor are derived by using the linear equation method. Weyl tableaus for the corresponding Gel'fand basis of SO(n) are defined. The assimilation method for obtaining CG coefficients of SO(n) in the Gel'fand basis for no modification rule involved couplings from IDCs of Brauer algebra are proposed. Some isoscalar factors of SO(n)⊃SO(n−1)SO(n)\supset SO(n-1) for the resulting irrep [λ1, λ2, λ3, λ4,0˙][\lambda_{1},~\lambda_{2},~ \lambda_{3},~\lambda_{4},\dot{0}] with $\sum\limits_{i=1}^{4}\lambda_{i}\leq .Comment: 48 pages latex, submitted to Journal of Phys.

    Nanoladder cantilevers made from diamond and silicon

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    We present a "nanoladder" geometry that minimizes the mechanical dissipation of ultrasensitive cantilevers. A nanoladder cantilever consists of a lithographically patterned scaffold of rails and rungs with feature size ∼\sim 100 nm. Compared to a rectangular beam of the same dimensions, the mass and spring constant of a nanoladder are each reduced by roughly two orders of magnitude. We demonstrate a low force noise of 158(+62)(−42) 158 (+62)(-42)\,zN and 190(+42)(−33) 190 (+42)(-33)\,zN in a one-Hz bandwidth for devices made from silicon and diamond, respectively, measured at temperatures between 100--150 mK. As opposed to bottom-up mechanical resonators like nanowires or nanotubes, nanoladder cantilevers can be batch-fabricated using standard lithography, which is a critical factor for applications in scanning force microscopy

    A q-Deformed Schr\"odinger Equation

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    We found hermitian realizations of the position vector r⃗\vec{r}, the angular momentum Λ⃗\vec{\Lambda} and the linear momentum p⃗\vec{p}, all behaving like vectors under the suq(2)su_q(2) algebra, generated by L0L_0 and L±L_\pm. They are used to introduce a qq-deformed Schr\" odinger equation. Its solutions for the particular cases of the Coulomb and the harmonic oscillator potentials are given and briefly discussed.Comment: 14 pages, latex, no figure

    Quasiparticle spectroscopy and high-field phase diagrams of cuprate superconductors -- An investigation of competing orders and quantum criticality

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    We present scanning tunneling spectroscopic and high-field thermodynamic studies of hole- and electron-doped (p- and n-type) cuprate superconductors. Our experimental results are consistent with the notion that the ground state of cuprates is in proximity to a quantum critical point (QCP) that separates a pure superconducting (SC) phase from a phase comprised of coexisting SC and a competing order, and the competing order is likely a spin-density wave (SDW). The effect of applied magnetic field, tunneling current, and disorder on the revelation of competing orders and on the low-energy excitations of the cuprates is discussed.Comment: 10 pages, 5 figures. Accepted for publication in the International Journal of Modern Physics B. (Correspondence author: Nai-Chang Yeh, e-mail: [email protected]

    A Particle Filter for Stochastic Advection by Lie Transport (SALT): A case study for the damped and forced incompressible 2D Euler equation

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    In this work, we apply a particle filter with three additional procedures (model reduction, tempering and jittering) to a damped and forced incompressible 2D Euler dynamics defined on a simply connected bounded domain. We show that using the combined algorithm, we are able to successfully assimilate data from a reference system state (the ``truth") modelled by a highly resolved numerical solution of the flow that has roughly 3.1×1063.1\times10^6 degrees of freedom for 1010 eddy turnover times, using modest computational hardware. The model reduction is performed through the introduction of a stochastic advection by Lie transport (SALT) model as the signal on a coarser resolution. The SALT approach was introduced as a general theory using a geometric mechanics framework from Holm, Proc. Roy. Soc. A (2015). This work follows on the numerical implementation for SALT presented by Cotter et al, SIAM Multiscale Model. Sim. (2019) for the flow in consideration. The model reduction is substantial: The reduced SALT model has 4.9×1044.9\times 10^4 degrees of freedom. Forecast reliability and estimated asymptotic behaviour of the particle filter are also presented

    Factorial Moments of Continuous Order

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    The normalized factorial moments FqF_q are continued to noninteger values of the order qq, satisfying the condition that the statistical fluctuations remain filtered out. That is, for Poisson distribution Fq=1F_q = 1 for all qq. The continuation procedure is designed with phenomenology and data analysis in mind. Examples are given to show how FqF_q can be obtained for positive and negative values of qq. With qq being continuous, multifractal analysis is made possible for multiplicity distributions that arise from self-similar dynamics. A step-by-step procedure of the method is summarized in the conclusion.Comment: 15 pages + 9 figures (figures available upon request), Late

    Interplay of Spin-Orbit Interactions, Dimensionality, and Octahedral Rotations in Semimetallic SrIrO3_3

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    We employ reactive molecular-beam epitaxy to synthesize the metastable perovskite SrIrO3_{3} and utilize {\it in situ} angle-resolved photoemission to reveal its electronic structure as an exotic narrow-band semimetal. We discover remarkably narrow bands which originate from a confluence of strong spin-orbit interactions, dimensionality, and both in- and out-of-plane IrO6_6 octahedral rotations. The partial occupation of numerous bands with strongly mixed orbital characters signals the breakdown of the single-band Mott picture that characterizes its insulating two-dimensional counterpart, Sr2_{2}IrO4_{4}, illustrating the power of structure-property relations for manipulating the subtle balance between spin-orbit interactions and electron-electron interactions

    Outflows from starburst galaxies with various driving mechanisms and their X-ray properties

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    Outflows in starburst galaxies driven by thermal-mechanical energy, cosmic rays and their mix are investigated with 1D and 2D hydrodynamic simulations. We show that these outflows could reach a stationary state, after which their hydrodynamic profiles asymptotically approach previous results obtained semi-analytically for stationary outflow configurations. The X-rays from the simulated outflows are computed, and high-resolution synthetic spectra and broadband light curves are constructed. The simulated outflows driven by thermal mechanical pressure and CRs have distinguishable spectral signatures, in particular, in the sequence of the keV Kα lines of various ions and in the L-shell Fe emission complex. We demonstrate that broadband colour analysis in X-rays is a possible alternative means to probe outflow driving mechanisms for distant galaxies, where observations may not be able to provide sufficient photons for high-resolution spectroscopic analyses
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