BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Iterative Perturbative Method for a Study of Disordered Strongly C orrelated Systems DTSTART;VALUE=DATE-TIME:20121018T131500Z DTEND;VALUE=DATE-TIME:20121018T134500Z DTSTAMP;VALUE=DATE-TIME:20261010T170231Z UID:indico-contribution-102-184@indico.ipb.ac.rs DESCRIPTION:Speakers: Jaksa Vucicevic (Institute of Physics Belgrade\, Bel grade University\, Pregrevica 118\, 11080 Belgrade)\nTwenty years after th e introduction of the Dynamical Mean Field Theory as a means of solving th e Hubbard model\, the focus has moved towards computationally very intensi ve multi-site and multi-orbital calculations\, which are aimed at includin g spatial correlations\, disorder and detailed atomic structure to the oth erwise fairly simple model. However\, limited computational resources crea te a need for faster and more optimized codes and even approximative solut ions. We present here a highly optimized parallel implementation of the ap proximative second order perturbative approach especially suitable for a s tudy of strongly disordered correlated systems. On this example\, we give an overview of numerical challenges that arise in dealing with large syste ms of non-linear equations\, ill-behaved discretized functions and self-co nsistent calculations in general. In the end\, we discuss results of perfo rmance tests\, outline possible improvements and make a comparison to the exact\, but computationally very demanding Quantum Monte Carlo method.\n\n https://events.saifa.rs/event/291/contributions/184/ LOCATION:National Library of Serbia URL:https://events.saifa.rs/event/291/contributions/184/ END:VEVENT BEGIN:VEVENT SUMMARY:Numerical Simulations of the Structure and Transport Properties of the Complex Networks DTSTART;VALUE=DATE-TIME:20121018T121500Z DTEND;VALUE=DATE-TIME:20121018T124500Z DTSTAMP;VALUE=DATE-TIME:20261010T170231Z UID:indico-contribution-102-190@indico.ipb.ac.rs DESCRIPTION:Speakers: Igor Stankovic (Scientfic Computing Laboratory\, Ins titute of Physics Belgrade\, University of Belgrade)\nIn this talk we revi ew our recent numerical study of various complex networks. First\, we wil l introduce results of Monte Carlo simulations of the percolation and cond uctivity of two-dimensional random stick systems. Based on the renormalis ation group considerations\, generalized scaling function is introduced to describe the scaling behaviour of the percolation distribution moments\, i.e.\, average percolation density and percolation density variance [1]. W e show that the prefactors in the generalized scaling function depend on t he system aspect ratio. The definite parity of the prefactors in the gener alized scaling function for the first two moments is a generic feature of whole class of percolating systems. The conductivity of the random stick systems is investigated from the percolation up to ten times percolation d ensity. An analytic model is proposed describing transition from the condu ctivity determined by the structure of a percolating cluster to the conduc tivity of the dense random stick networks. The derived model for conductiv ity should be broadly applicable to the random networks of the rodlike par ticles [2].\n\nIn the second part of the talk\, we will present paths for optimization of the transport capacity of the complex networks without cha nging average connectivity or total network capacity. The focus is on effi cient routing [3]. The routing strategies are compared using two generic m odels\, i.e.\, Barabási-Albert scale-free network and scale-free network on lattice\, and academic router networks of the Netherlands and France. T he nodes without buffers are considered\, so\, if congestion occurs\, pack ets will be dropped. We propose a dynamic routing algorithm which automati cally extends path of the packet before it arrives at congested node. Simu lation results indicate that proposed routing strategy can further reduce number of dropped packets in a combination with the efficient path routing proposed by Yan et al. [4].\n\n[1] M. Zezelj\, I. Stankovic and A. Belic\ , "Finite-size Scaling in Asymmetric Systems of Percolating Sticks"\, Phys . Rev. E 85\, 021101 (2012).\n[2] M. Zezelj\, I. Stankovic\, “From perco lating to dense random stick networks: conductivity model investigation” \, submitted.\n[3] Jelena Smiljanic\, Milan Zezelj\, and Igor Stankovic\, “Study of routing strategies in the small complex networks”\, Telekom unikacije 9\, to appear.\n[4] G. Yan\, T. Zhou\, B. Hu\, Z.-Q. Fu\, and B. -H. Wang\, “Efficient Routing on Complex Networks”\, Phys. Rev. E 73\, 046108 (2006).\n\nhttps://events.saifa.rs/event/291/contributions/190/ LOCATION:National Library of Serbia URL:https://events.saifa.rs/event/291/contributions/190/ END:VEVENT BEGIN:VEVENT SUMMARY:Emergence of resonant waves in cigar-shaped Bose-Einstein condensa tes DTSTART;VALUE=DATE-TIME:20121018T124500Z DTEND;VALUE=DATE-TIME:20121018T131500Z DTSTAMP;VALUE=DATE-TIME:20261010T170231Z UID:indico-contribution-102-197@indico.ipb.ac.rs DESCRIPTION:Speakers: Alexandru Nicolin (Horia Hulubei National Institute for Physics and Nuclear Engineering)\nMotivated by the continuous interest shown to the nonlinear dynamics of quantum gases we present in this talk the emergence of resonant waves in cigar-shaped Bose-Einstein condensates using which has been reported in Ref. [1].\n\nWe introduce the analytic tr eatment of the dynamics of a trapped\, quasi-one-dimensional Bose-Einstei n condensate subject to resonant and nonresonant periodic modulation of th e transverse confinement. The dynamics of the condensate is described vari ationally through a set of coupled ordinary differential equations\, and t he period of the excited waves is determined analytically using a Mathieu- type analysis. For a modulation frequency equal to that of the radial conf inement we show that the predicted period of the resonant wave is in agree ment with the existing experimental results. Finally\, we present a detail ed comparison between the resonant waves and the Faraday waves that emerge outside of resonance.\n\n[1] A.I. Nicolin\, Phys. Rev. E 84\, 056202 (201 1).\n\nhttps://events.saifa.rs/event/291/contributions/197/ LOCATION:National Library of Serbia URL:https://events.saifa.rs/event/291/contributions/197/ END:VEVENT END:VCALENDAR