8,122 research outputs found

    Progress of analog-hybrid computation

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    Review of fast analog/hybrid computer systems, integrated operational amplifiers, electronic mode-control switches, digital attenuators, and packaging technique

    Effect of dipolar interactions on optical nonlinearity of two-dimensional nanocomposites

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    In this work, we calculate the contribution of dipole-dipole interactions to the optical nonlinearity of the two-dimensional random ensemble of nanoparticles that possess a set of exciton levels, for example, quantum dots. The analytical expressions for the contributions in the cases of TM and TE-polarized light waves propagating along the plane are obtained. It is shown that the optical nonlinearity, caused by the dipole-dipole interactions in the planar ensemble of the nanoparticles, is several times smaller than the similar nonlinearity of the bulk nanocomposite. This type of optical nonlinearity is expected to be observed at timescales much larger than the quantum dot exciton rise time. The proposed method may be applied to various types of the nanocomposite shapes.Comment: 8 page

    Reversable heat flow through the carbon nanotube junctions

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    Microscopic mechanisms of externally controlled reversable heat flow through the carbon nanotube junctions (NJ) are studied theoretically. Our model suggests that the heat is transfered along the tube section T{\cal T} by electrons (ee) and holes (hh) moving ballistically in either in parallel or in opposite directions and accelerated by the bias source-drain voltage VSDV_{\rm SD} (Peltier effect). We compute the Seebeck coefficient α\alpha , electric σ\sigma and thermal κ\kappa conductivities and find that their magnitudes strongly depend on VSDV_{\rm SD} and VGV_{\rm G}. The sign reversal of α\alpha versus the sign of VGV_{\rm G} formerly observed experimentally is interpreted in this work in terms of so-called chiral tunneling phenomena (Klein paradox)

    Spinning Q-balls in the complex signum-Gordon model

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    Rotational excitations of compact Q-balls in the complex signum-Gordon model in 2+1 dimensions are investigated. We find that almost all such spinning Q-balls have the form of a ring of strictly finite width. In the limit of large angular momentum M_z their energy is proportional to |M_z|^(1/5).Comment: 10 page

    Extreme laser pulses for possible development of boron fusion power reactors for clean and lasting energy

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    Extreme laser pulses driving non-equilibrium processes in high density plasmas permit an increase of the fusion of hydrogen with the boron isotope 11 by nine orders of magnitude of the energy gains above the classical values. This is the result of initiating the reaction by non-thermal ultrahigh acceleration of plasma blocks by the nonlinear (ponderomotive) force of the laser field, in addition to the avalanche reaction that has now been experimentally and theoretically manifested. The design of a very compact fusion power reactor is scheduled to produce then environmentally fully clean and inexhaustible generation of energy at profitably low costs. The reaction within a volume of cubic millimetres during a nanosecond can only be used for controlled power generation.Comment: 10 pages, 5 fugure
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