This paper applies social network analysis techniques to study computer virus propagation. We propose a novel multilevel hierarchical linear model to simultaneously evaluate the impact of both individual-level and group-level variables on virus propagation process. In this model, we propose centrality and brokerage measures as explanatory variables. We estimate our model based on empirical data...

The problem of estimating the propagation-delay of a desired signal in the presence of interferences and multipath propagation is addressed. This paper presents the maximum likelihood (ML) propagation-delay estimator for a signal arriving at a sensor array. The novel characteristic herein is that the desired signal impinges on the array with a known steering vector. This fact allows to assume a...

Effective intervehicle communication is fundamental to a decentralized traffic information system based on mobile ad hoc vehicle networks. Here we model the information propagation process through inter-vehicle communication when the vehicle headway follows a general distribution. Equations for the expected value and variance of propagation distance are derived. In addition, we provide simple e...

Propagation delays are intensively used for Structural Health Monitoring or Sensor Network Localization. In this paper, we study the performances of acoustic propagation delay estimation between two sensors, using sources of opportunity only. Such sources are defined as being uncontrolled by the user (activation time, location, spectral content in time and space), thus preventing the direct est...

By extending a well-established time-domain perturbation approach to dual-polarization propagation, we provide an analytical framework to predict the nonlinear interference (NLI) variance, i.e., the variance induced by nonlinearity on the sampled field, and the nonlinear threshold (NLT) in coherent transmissions with dominant intrachannel-four-wave-mixing (IFWM). Such a framework applies to non...

Phase scintillation caused by propagation through irregularities in the solar wind, ionosphere, and troposphere, introduces noise in spacecraft radio science experiments. In precision Doppler tracking observations, scintillation can be the dominant noise source; statistics of this propagation noise are necessary for experiment planning and in design of optimum signal processing procedures. Here...

We describe a multidimensional maximum likelihood estimator for radio channel parameters. We also derive a data model to describe the complete data, that is virtually applicable to every antenna array geometry. The proposed iterative gradient based algorithm has been developed, since algorithms using component-wise updates of the likelihood function shows a slow convergence, if at least two pro...

The phase-locked loop (PLL) propagation time is important unavoidable factor for high-speed coherent detection systems using broad-linewidth laser diodes. This paper report the linewidths requirements and the power penalties taking into account the loop propagation delay. The coherent optical receivers with PLL, based on Costas loop or decision driven loop (DDL) are taken into consideration. Th...