Browsing by Subject "Spectrum analysis"

Now showing items 1-20 of 37

    • Article  

      ARM A Models, Prewhitening, and Minimum Gross Entropy 

      Politis, Dimitris Nicolas (1993)
      The problem of spectral estimation on the basis of observations from a finite stretch of a stationary time series is considered, in connection with knowledge of a prior estimate of the spectral density. In general, the ...
    • Conference Object  

      Bispectral analysis of EMG at different levels of force 

      Pattichis, Constantinos S.; Constantinou, Renos; Spyrou, S.; Schizas, Christos N.; Middleton, Lefkos T. (Publ by IEEE, 1993)
      Bispectral analysis suggests that EMG is highly non-Gaussian at force level (FL) = 10% of maximum voluntary contraction
    • Conference Object  

      Bispectral analysis of surface EMG 

      Kaplanis, P. A.; Pattichis, Constantinos S.; Hadjileontiadis, L. J.; Panas, S. M. (IEEE, 2000)
      The objective of this ongoing study is to investigate whether or not Bispectral analysis (BS), a particular form of higher order spectra (HOS), may be utilized for analyzing the surface electromyographic signal (SEMG). The ...
    • Conference Object  

      Capacity of gaussian channels with noise uncertainty 

      Denic, S. Z.; Charalambous, Charalambos D.; Djouadi, S. M. (2004)
      In this paper the problem of defining, and computing the capacity of a communication channel when the statistic of an additive noise is not fully known, is addressed. The communication channel is specified as a continuous ...
    • Article  

      Chemical, acoustic and optical response profiling for analysing burning patterns 

      Mikedi, Katerina; Stavrakakis, P.; Agapiou, Agapios; Moirogiorgou, K.; Karma, Sofia; Pallis, George C.; Pappa, Athina A.; Statheropoulos, Miltiades K.; Zervakis, M. (2013)
      Improved data processing algorithms along with modelling techniques were employed in order to profile the responses and to assess the analytical capabilities of a system consisting of a mass spectrometer, a camera and a ...
    • Article  

      Complex-valued tapers 

      Politis, Dimitris Nicolas (2005)
      The spectral estimation method based on the average of short, tapered periodograms is re-examined. The bias of such estimators is typically O(1/b2), where b is the length of the short blocks. Much of the current researeh ...
    • Article  

      Conforming Chebyshev spectral methods for Poisson problems in rectangular domains 

      Karageorghis, Andreas (1993)
      Four and six-element conforming domain decomposition techniques are developed for Chebyshev spectral collocation methods for Poisson problems in rectangular domains. The applicability of the methods is demonstrated on ...
    • Article  

      Conforming spectral methods for Poisson problems in cuboidal domains 

      Karageorghis, Andreas (1994)
      A Chebyshev collocation strategy is introduced for the subdivision of cuboids into cuboidal subdomains (elements). These elements are conforming, which means that the approximation to the solution is C0 continuous at all ...
    • Article  

      Direct methods for spectral approximations in nonconforming domain decompositions 

      Karageorghis, Andreas; Paprzycki, M. (1998)
      The application of a conforming spectral collocation method to certain nonconforming domain decompositions leads to global matrices which have a particular block structure. We study the performance of various direct linear ...
    • Article  

      Distribution theory for the studentized mean for long, short, and negative memory time series 

      McElroy, T.; Politis, Dimitris Nicolas (2013)
      We consider the problem of estimating the variance of the partial sums of a stationary time series that has either long memory, short memory, negative/intermediate memory, or is the first-difference of such a process. The ...
    • Conference Object  

      Frequency-domain characterization of Singular Spectrum Analysis eigenvectors 

      Leles, M. C. R.; Cardoso, A. S. V.; Moreira, M. G.; Guimaraes, H. N.; Silva, C. M.; Pitsillides, Andreas (Institute of Electrical and Electronics Engineers Inc., 2017)
      Singular Spectrum Analysis (SSA) is a nonparametric approach used to decompose a time series into meaningful components, related to trends, oscillations and noise. SSA can be seen as a spectral decomposition, where each ...
    • Article  

      Identification and reconstruction of a small leak zone in a pipe by a spectral element method 

      Belhachmi, Z.; Karageorghis, Andreas; Taous, K. (2006)
      This paper deals with the identification of a zone permitting fluid to leak out of a drain. Using the analogy with crack identification by boundary measurements, we give uniqueness and stability results and we propose an ...
    • Article  

      Kinetic and mechanistic studies of the water-gas shift reaction on Pt/TiO2 catalyst 

      Kalamaras, Christos M.; Panagiotopoulou, P.; Kondarides, D. I.; Efstathiou, Angelos M. (2009)
      A detailed kinetic and mechanistic study of the water-gas shift (WGS) reaction on a 0.5 wt% Pt/TiO2 catalyst has been carried out. The dependence of kinetic reaction rate on the partial pressures of reactants (CO, H2O) and ...
    • Article  

      Multifeature Texture Analysis for the Classification of Clouds in Satellite Imagery 

      Christodoulou, Christodoulos I.; Michaelides, Silas C.; Pattichis, Constantinos S. (2003)
      The aim of this work was to develop a system based on multifeature texture analysis and modular neural networks that will facilitate the automated interpretation of satellite cloud images. Such a system will provide a ...
    • Conference Object  

      New image processing models for opacity image analysis in chest radiographs 

      Pattichis, Marios S.; Muralldharan, H.; Pattichis, Constantinos S.; Soliz, P. (Institute of Electrical and Electronics Engineers Inc., 2002)
      The aim of this research is to develop new image processing models that can be used to characterize single opacities and opacity density within pre-selected regions of interest (ROI). We derive our new image processing ...
    • Article  

      New light from hybrid inorganic-organic emitters 

      Belton, C. R.; Itskos, Grigorios; Heliotis, G.; Stavrinou, P. N.; Lagoudakis, P. G.; Lupton, J.; Pereira, S.; Gu, E.; Griffin, C.; Guilhabert, B.; Watson, I. M.; Mackintosh, A. R.; Pethrick, R. A.; Feldmann, J.; Murray, R.; Dawson, M. D.; Bradley, D. D. C. (2008)
      We present the highlights of a research programme on hybrid inorganic-organic light emitters. These devices combine recent developments in III-V nitride technology (including UV emitting micro-arrays and specifically ...
    • Article  

      A nonoverlapping domain decomposition method for Legendre spectral collocation problems 

      Bialecki, B.; Karageorghis, Andreas (2007)
      We consider the Dirichlet boundary value problem for Poisson's equation in an L-shaped region or a rectangle with a cross-point. In both cases, we approximate the Dirichlet problem using Legendre spectral collocation, that ...
    • Article  

      Nonparametric Maximum Entropy 

      Politis, Dimitris Nicolas (1993)
      The standard maximum entropy method of Burg and the resulting autoregressive model has been widely applied for spectrum estimation and prediction. A generalization of the maximum entropy formalism in a nonparametric setting ...
    • Article  

      The numerical solution of laminar flow in a re-entrant tube geometry by a Chebyshev spectral element collocation method 

      Karageorghis, Andreas (1992)
      A Chebyshev spectral element collocation method is used for the numerical solution of laminar flow in a re-entrant tube geometry. The high accuracy of the method allows the study of the merging process of the vortices in ...
    • Article  

      On the Maximum Entropy Problem with Autocorrelations Specified on a Lattice 

      Politis, Dimitris Nicolas (1993)
      The maximum entropy process with autocorrelations specified on a finite lattice is identified to be a Gaussian autoregressive process with a special structure in its coefficients. The autoregressive coefficients can be ...