Browsing by Subject "Mathematical transformations"

Now showing items 21-40 of 45

    • Conference Object  

      Maximum Likelihood parameter estimation from incomplete data via the sensitivity equations: The continuous-time case 

      Charalambous, Charalambos D. (IEEE, 1999)
      The problem of estimating the parameters for continuous-time partially observed systems is discussed. New exact filters for obtaining Maximum Likelihood (ML) parameter estimates via the Expectation Maximization algorithm ...
    • Article  

      The method of fundamental solutions for inhomogeneous elliptic problems 

      Poullikkas, A.; Karageorghis, Andreas; Georgiou, Georgios C. (1998)
      We investigate the use of the Method of Fundamental Solutions (MFS) for solving inhomogeneous harmonic and biharmonic problems. These are transformed to homogeneous problems by subtracting a particular solution of the ...
    • Article  

      Minimax games for stochastic systems subject to relative entropy uncertainty: Applications to SDEs on Hilbert spaces 

      Ahmed, N. U.; Charalambous, Charalambos D. (2007)
      In this paper, we consider minimax games for stochastic uncertain systems with the pay-off being a nonlinear functional of the uncertain measure where the uncertainty is measured in terms of relative entropy between the ...
    • Conference Object  

      Modeling change of haplotype distributions in random mating populations using random sets 

      Raji-Kermany, A.; Charalambous, Charalambos D.; Hickey, D. (2004)
      Several mathematical models have been developed to describe the genetic structure of populations. Most of these models focus on only one, or few genetic loci. In this paper, we develop a model to describe a large number ...
    • Article  

      Nature inspired node density estimation for molecular nanonetworks 

      Saeed, T.; Lestas, Marios; Pitsillides, Andreas (2017)
      The problem of estimating the node density in ad hoc networks is a significant one for protocol design. In molecular nanonetworks, the node density estimation problem poses additional challenges due to the limited processing ...
    • Article  

      Noether and master symmetries for the Toda lattice 

      Damianou, Pantelis A.; Sophocleous, Christodoulos (2005)
      In this letter we examine the interrelation between Noether symmetries, master symmetries and recursion operators for the Toda lattice. The topics include invariants, higher Poisson brackets and the various relations they ...
    • Article  

      Numerical investigation of the nonlinear heat diffusion equation with high nonlinearity on the boundary 

      Christou, Marios Andreas; Sophocleous, Christodoulos; Christov, Christo I. (2008)
      A nonlinear heat diffusion problem is considered when the thermal conductivity and heat capacity are nonlinear functions of the temperature. At one of the boundaries a highly nonlinear condition is imposed involving both ...
    • Conference Object  

      On multiobjective H2/H∞ optimal control 

      Djouadi, S. M.; Charalambous, Charalambos D.; Repperger, D. W. (2001)
      In this paper the solutions to the optimal multiobjective H2/H∞ problem are characterized using Banach space duality theory, and shown to satisfy a flatness or allpass condition. Dual and predual spaces are identified, and ...
    • Article  

      On network survivability algorithms based on trellis graph transformations 

      Louca, Soulla P.; Pitsillides, Andreas; Samaras, George S. (1999)
      Due to the wide range of services being supported, telecommunications networks are loaded with massive quantities of information. This stimulates extra concern for network survivability. In this paper, we use graph theoretic ...
    • Article  

      On the effect of misspecifying the density ratio model 

      Fokianos, Konstantinos; Kaimi, I. (2006)
      The density ratio model specifies that the log-likelihood ratio of two unknown densities is of known linear form which depends on some finite dimensional parameters. The model can be broadened to allow for m-samples in a ...
    • Article  

      On the group classification of variable-coefficient nonlinear diffusion-convection equations 

      Ivanova, Nataliya M.; Sophocleous, Christodoulos (2006)
      We consider the variable coefficient diffusion-convection equation of the form f (x) ut = [g (x) D (u) ux]x + h (x) K (u) ux which has considerable interest in mathematical physics, biology and chemistry. We present a ...
    • Article  

      On the invariants of two dimensional linear parabolic equations 

      Tsaousi, Christina; Sophocleous, Christodoulos; Tracinà, Rita (2012)
      We consider the most general two dimensional linear parabolic equations. Motivated by the recent work of Ibragimov et al. [1-3] we construct differential invariants, semi-invariants and invariant equations. These results ...
    • Conference Object  

      Optimization of Stochastic Uncertain Systems: Large Deviations and Robustness 

      Charalambous, Charalambos D.; Rezaei, F. (2003)
      This paper is concerned with an abstract formulation of stochastic uncertain control systems, in which the pay-off is described by the relative entropy between the nominal measure and the uncertain measure, while the ...
    • Conference Object  

      Output feedback risk-sensitive control and dynamic games: Small noise limits 

      Charalambous, Charalambos D. (IEEE, 1997)
      This paper employs logarithmic transformations to establish relations between continuous-time nonlinear partially observable risk-sensitive control problems and analogous output feedback dynamic games.
    • Conference Object  

      A Perfect Reconstruction Paradigm for Digital Communication 

      Voulgaris, P. G.; Hadjicostis, Christoforos N.; Touri, R. (2003)
      In this paper we present a deterministic worst-case framework for reconstruction of discrete data transmissions through dispersive communication channels. This framework can be explored based on robust control ideas and ...
    • Article  

      Performance analysis for a changepoint problem 

      Hibey, J. L.; Charalambous, Charalambos D. (1999)
      Nonlinear stochastic differential equations are used to model a version of the changepoint problem. State estimates of the minimum mean-square-error-type are used in likelihood-ratio tests to detect the time of change. ...
    • Conference Object  

      Performance analysis for a changepoint problem 

      Hibey, Joseph L.; Charalambous, Charalambos D. (IEEE, 1997)
      Nonlinear stochastic differential equations are used to model a version of the changepoint problem. State estimates of the minimum-mean-square-error type are used in likelihood-ratio tests to detect the time of change. We ...
    • Conference Object  

      The power of the defender 

      Gelastou, Marina; Mavronicolas, Marios; Lesta, Vicky Papadopoulou; Philippou, Anna; Spirakis, Paul G. (2006)
      We consider a security problem on a distributed network. We assume a network whose nodes are vulnerable to infection by threats (e.g. viruses), the attackers. A system security software, the defender, is available in the ...
    • Conference Object  

      Presampled visibility for ambient occlusion 

      Gaitatzes, Athanasios; Chrysanthou, Yiorgos L.; Papaioannou, Georgios J. (2008)
      We present a novel method to accelerate the computation of the visibility function of the lighting equation, in dynamic scenes composed of rigid, non-penetrating objects. The main idea of the technique is to pre-compute ...
    • Conference Object  

      Risk-sensitive control, differential games, and limiting problems in infinite dimensions 

      Charalambous, Charalambos D.; Naidu, Subbaram; Moore, Kevin L. (IEEE, 1994)
      In this paper we present the solutions of the stochastic finite and infinite horizon risk-sensitive control problems in infinite dimensions, with μ, ε > 0, respectively, representing the risk-sensitivity and small noise ...