65,596 research outputs found

    A proposed case for the cloud software engineering in security

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    This paper presents Cloud Software Engineering in Security (CSES) proposal that combines the benefits from each of good software engineering process and security. While other literature does not provide a proposal for Cloud security as yet, we use Business Process Modeling Notation (BPMN) to illustrate the concept of CSES from its design, implementation and test phases. BPMN can be used to raise alarm for protecting Cloud security in a real case scenario in real-time. Results from BPMN simulations show that a long execution time of 60 hours is required to protect real-time security of 2 petabytes (PB). When data is not in use, BPMN simulations show that the execution time for all data security rapidly falls off. We demonstrate a proposal to deal with Cloud security and aim to improve its current performance for Big Data

    On a class of reductions of Manakov-Santini hierarchy connected with the interpolating system

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    Using Lax-Sato formulation of Manakov-Santini hierarchy, we introduce a class of reductions, such that zero order reduction of this class corresponds to dKP hierarchy, and the first order reduction gives the hierarchy associated with the interpolating system introduced by Dunajski. We present Lax-Sato form of reduced hierarchy for the interpolating system and also for the reduction of arbitrary order. Similar to dKP hierarchy, Lax-Sato equations for LL (Lax fuction) due to the reduction split from Lax-Sato equations for MM (Orlov function), and the reduced hierarchy for arbitrary order of reduction is defined by Lax-Sato equations for LL only. Characterization of the class of reductions in terms of the dressing data is given. We also consider a waterbag reduction of the interpolating system hierarchy, which defines (1+1)-dimensional systems of hydrodynamic type.Comment: 15 pages, revised and extended, characterization of the class of reductions in terms of the dressing data is give

    Hadronic production of the PP-wave excited BcB_c-states (BcJ,L=1B_{cJ,L=1}^*)

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    Adopting the complete αs4\alpha_s^4 approach of the perturbative QCD (pQCD) and updated parton distribution functions, we have estimated the hadronic production of PP-wave excited BcB_c-states (BcJ,L=1B_{cJ,L=1}^*). In the estimate, special care on the relation of the production amplitude to the derivative of wave function at origin of the potential model is payed. For experimental references, main uncertainties are discussed, and the total cross sections and the distributions of the production with reasonable cuts at the energies of Tevatron and LHC are computed and presented. The results show that PP-wave production may contribute to the BcB_c-meson production indirectly by a factor about 0.5 of the direct production, and with such a big cross section, it is worth further to study the possibility to observe the PP-wave production itself experimentally.Comment: 23 pages, 9 figures, to replace for revising the misprints ec

    The effect of barriers on wave propagation phenomena: With application for aircraft noise shielding

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    The frequency spectrum was divided into high and low frequency regimes and two separate methods were developed and applied to account for physical factors associated with flight conditions. For long wave propagation, the acoustic filed due to a point source near a solid obstacle was treated in terms of an inner region which where the fluid motion is essentially incompressible, and an outer region which is a linear acoustic field generated by hydrodynamic disturbances in the inner region. This method was applied to a case of a finite slotted plate modelled to represent a wing extended flap for both stationary and moving media. Ray acoustics, the Kirchhoff integral formulation, and the stationary phase approximation were combined to study short wave length propagation in many limiting cases as well as in the case of a semi-infinite plate in a uniform flow velocity with a point source above the plate and embedded in a different flow velocity to simulate an engine exhaust jet stream surrounding the source

    Formation of Quantum Shock Waves by Merging and Splitting Bose-Einstein Condensates

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    The processes of merging and splitting dilute-gas Bose-Einstein condensates are studied in the nonadiabatic, high-density regime. Rich dynamics are found. Depending on the experimental parameters, uniform soliton trains containing more than ten solitons or the formation of a high-density bulge as well as quantum (or dispersive) shock waves are observed experimentally within merged BECs. Our numerical simulations indicate the formation of many vortex rings. In the case of splitting a BEC, the transition from sound-wave formation to dispersive shock-wave formation is studied by use of increasingly stronger splitting barriers. These experiments realize prototypical dispersive shock situations.Comment: 10 pages, 8 figure

    Ground State Properties of Fermi Gases in the Strongly Interacting Regime

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    The ground state energies and pairing gaps in dilute superfluid Fermi gases have now been calculated with the quantum Monte Carlo method without detailed knowledge of their wave functions. However, such knowledge is essential to predict other properties of these gases such as density matrices and pair distribution functions. We present a new and simple method to optimize the wave functions of quantum fluids using Green's function Monte Carlo method. It is used to calculate the pair distribution functions and potential energies of Fermi gases over the entire regime from atomic Bardeen-Cooper-Schrieffer superfluid to molecular Bose-Einstein condensation, spanned as the interaction strength is varied.Comment: 4 pages, 4 figure

    Decays of the Meson BcB_c to a PP-Wave Charmonium State χc\chi_c or hch_c

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    The semileptonic decays, Bcχc(hc)++νB_{c}{\longrightarrow}{\chi_c}(h_c)+{\ell}+{{\nu}}_{\ell}, and the two-body nonleptonic decays, Bcχc(hc)+hB_{c}{\longrightarrow}{\chi_c}(h_c)+h, (here χc\chi_c and hch_c denote (ccˉ[3PJ])(c\bar c[^3P_J]) and (ccˉ[1P1])(c\bar c[^1P_1]) respectively, and hh indicates a meson) were computed. All of the form factors appearing in the relevant weak-current matrix elements with BcB_c as its initial state and a PP-wave charmonium state as its final state for the decays were precisely formulated in terms of two independent overlapping-integrations of the wave-functions of BcB_c and the PP-wave charmonium and with proper kinematics factors being `accompanied'. We found that the decays are quite sizable, so they may be accessible in Run-II at Tevatron and in the foreseen future at LHC, particularly, when BTeV and LHCB, the special detectors for B-physics, are borne in mind. In addition, we also pointed out that the decays Bchc+...B_c\to h_c+... may potentially be used as a fresh window to look for the hch_c charmonium state, and the cascade decays, Bcχc[3P1,2]+l+νlB_c\to \chi_c[^3P_{1,2}]+l+\nu_l (Bcχc[3P1,2]+hB_c\to \chi_c[^3P_{1,2}]+h) with one of the radiative decays χc[3P1,2]J/ψ+γ\chi_c[^3P_{1,2}] \to J/\psi+\gamma being followed accordingly, may affect the observations of BcB_c meson through the decays BcJ/ψ+l+νlB_{c}\to {J/\psi}+{l}+\nu_{l} (BcJ/ψ+hB_c\to J/\psi+h) substantially.Comment: 24 pages, 3 figures, the replacement for improving the presentation and adding reference

    Photonic quantum transport in a nonlinear optical fiber

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    We theoretically study the transmission of few-photon quantum fields through a strongly nonlinear optical medium. We develop a general approach to investigate nonequilibrium quantum transport of bosonic fields through a finite-size nonlinear medium and apply it to a recently demonstrated experimental system where cold atoms are loaded in a hollow-core optical fiber. We show that when the interaction between photons is effectively repulsive, the system acts as a single-photon switch. In the case of attractive interaction, the system can exhibit either antibunching or bunching, associated with the resonant excitation of bound states of photons by the input field. These effects can be observed by probing statistics of photons transmitted through the nonlinear fiber

    Parametric frequency mixing in the magneto-elastically driven FMR-oscillator

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    We demonstrate the nonlinear frequency conversion of ferromagnetic resonance (FMR) frequency by optically excited elastic waves in a thin metallic film on dielectric substrates. Time-resolved probing of the magnetization directly witnesses magneto-elastically driven second harmonic generation, sum- and difference frequency mixing from two distinct frequencies, as well as parametric downconversion of each individual drive frequency. Starting from the Landau-Lifshitz-Gilbert equations, we derive an analytical equation of an elastically driven nonlinear parametric oscillator and show that frequency mixing is dominated by the parametric modulation of FMR frequency

    Optimization of photon storage fidelity in ordered atomic arrays

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    A major application for atomic ensembles consists of a quantum memory for light, in which an optical state can be reversibly converted to a collective atomic excitation on demand. There exists a well-known fundamental bound on the storage error, when the ensemble is describable by a continuous medium governed by the Maxwell-Bloch equations. The validity of this model can break down, however, in systems such as dense, ordered atomic arrays, where strong interference in emission can give rise to phenomena such as subradiance and "selective" radiance. Here, we develop a general formalism that finds the maximum storage efficiency for a collection of atoms with discrete, known positions, and a given spatial mode in which an optical field is sent. As an example, we apply this technique to study a finite two-dimensional square array of atoms. We show that such a system enables a storage error that scales with atom number NaN_\mathrm{a} like (logNa)2/Na2\sim (\log N_\mathrm{a})^2/N_\mathrm{a}^2, and that, remarkably, an array of just 4×44 \times 4 atoms in principle allows for an efficiency comparable to a disordered ensemble with optical depth of around 600.Comment: paper is now identical to published versio
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