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The high-frequency properties of the FeCo-SiO2 monolayer nanogranular films and FeCo/(FeCo)0.63(SiO2)0.37 multilayer nanogranular films which were elaborated on flexible substrates by magnetron sputtering system were studied. Compared to the monolayer films with the same FeCo content, the multilayer structures comprised of FeCo/(FeCo)0.63(SiO2)0.37 exhibit(More)
Community finding of virtual user network on the Internet has provoked more and more researchers' interests in the field of computer and physics field recently. Existed results focus on how to seek a reasonable and feasible algorithm to find the communities of virtual user network mostly, but scarcely relate to the centrality of those found communities. In(More)
A stock market is a typical complex network and it can be described by complex network. Recently more related researches have focused on modeling and analyzing of topological structure of complex stock network. For an investor, the best decision is to select the optimal portfolio in order to obtain the maximum income with the given risk level. In this(More)
  • Sen Qin
  • 2010
The heavy-tailed characteristic has been emerged in the distributions of Internet flow sizes, web pages and computer files. So the M/Heavy-Tailed/K queue system is the highlight of the research of queue systems. In this paper, it is firstly proved that the efficiency of multiple servers is equal to the single server when all of servers work with full load.(More)
Value-at-risk (VaR) and conditional value-at-risk (CVaR) have become two very popular measures of market risk during the last decade. Log-optimal portfolio problem with risk control of VaR and CVaR is put forward firstly. Then, we propose the portfolio models with VaR and CVaR and prove the existence and uniqueness of the optimal solutions of these two(More)
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