Papachristodoulou CA, Ioannides KG, Mertzimekis TJ, Stamoulis KC, Karamanis DT. Assessment of Arrangements for the Detection of Radon Emanating from Soil. In: Panos K Advances in Nuclear Physics, Proceeding of the 6th Panhellenic Symposium of the Hellenic Nuclear Society, TEI Piraeus. TEI Piraeus: Hellenic Nuclear Physics Society; 1995. pp. 288–301. Website
We consider the problem of sequential control for a finite state and action Markovian Decision Process with incomplete information regarding the transition probabilities P ∈ Papprox. Under suitable irreducibility assumptions for Papprox.. We construct adaptive policies that maximize the rate of convergence of realized rewards to that of the optimal (non adaptive) policy under complete information. These adaptive policies are specified via an easily computable index function, of states, controls and statistics, so that one takes a control with the largest index value in the current state in every period.
Demetriou IC. An overview of theory for piecewise monotonic approximation. In: HERMIS 94, Proceedings of the 2nd Conference on Informatics and Mathematics . Vol. 2. E.A. Lipitakis, Editor. Athens, Greece: Hellenic Mathematical Society Publisher; 1994. pp. 667-682.
Papavramidis AC, Tombras GS, Doukas D. Adaptation of land mobile systems for onboard operation. In: Proceedings of 2nd IEEE International Conference on Universal Personal Communications: Gateway to the 21st Century, ICUPC 1993. Vol. 1. ; 1993. pp. 258-263. Website
The fundamental mechanisms controlling the light emission from porous Si remain unresolved. In this paper we report attempts to modify the luminescence using a variety of surface processing steps, such as vacuum annealing with subsequent anneals in nitrogen and oxygen, exposure to hydrofluoric acid (HF) and rapid thermal oxidation. Luminescence, infrared absorption, and electron spin resonance (ESR) have all been used to gain more information on the link between the optical emission and the localisation of the electrons in this material system. We present evidence that the silicon dangling bond is the key component in the non-radiative recombination. This is based on measurements shown that hydrogen coverage of the surface is significant because of saturation of the dangling bonds and a subsequent reduction in the competing non-radiative paths rather than as an active component in the radiative transition. Finally, we focus our attention upon the lower energy band which appears in the luminescence spectrum of porous Si (approx.0.9eV) by examining its behavior under the surface treatments mentioned above. We found that this luminescence band originates from the surface of the porous layer and its intensity correlates well with increasing oxidation of the porous layer.
Kassaras I, Makropoulos K, Papadimitriou P, Drakopoulos J, Amorese D, Hatzfeld D, Coutant O, Panagiotopoulos D, Karakaisis G, Scordilis E. Microearthquake Seismicity in the Ionian Islands. In: 2nd ESC Workshop on Statistical Models and Methods in Seismology. Cephalonia 2-5 June, 1993; 1993.72_abstract_3.pdf
Vomvoridis JL, Frantzeskakis DJ, Hizanidis K. Autonomous beam buncher for ECM applications. In: Proceedings of SPIE - The International Society for Optical Engineering. Vol. 1929. ; 1992. pp. 270-271. Website
Papavramidis A, Paschalis A, Myrtue O, Dangakis K, Tombras G, Kostarakis P. A conformance test system for DECT physical layer. In: IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC. ; 1992. pp. 357-361. Website
Amorese D, Hatzfeld D, Panagiotopoulos D, Karakaisis G, Scordilis E, Makropoulos K, Kassaras I, Drakatos G. A microearthquake study in Epirus. In: EUG 6th General Assembly. Strasbourg; 1991.abstract_1.pdf
The dynamical properties and stellar content of some cluster pairs in the LMC were studied, using UKST plates. Positive evidence was found for significant distortions in the density profiles of the clusters, particularly in the outer regions. These disturbances were interpreted as indications of dynamical interaction between the pair members. Some of the pairs were found to have very similar stellar content, and ages ranging from a few 107yr to several 108yr.
Papadrakakis M, Dracopoulos MC. Improving the Efficiency of Preconditioning for Iterative Methods. In: Topping BHV Proceedings of the Fourth International Conference on Civil and Structural Engineering Computing ({CIVIL-COMP} 89). City University, London; 1989. pp. 297–306.
Most studies of the morphological and structural properties of the SMC to date were based on very young and young populations essentially confined in space to the bar, arms, and wing. In this project, the authors cover a much larger area of the SMC and a much broader range in ages, with the purpose of performing a thorough study of the structure and population synthesis in the outer regions of the SMC.
Thirty eight remote LMC clusters randomly distributed around the LMC rotation centre were measured by means of star counts in plates taken with the 1.2 m U.K. Schmidt telescope to derive their tidal radii and total masses. Seven of these clusters were found to violate the usual picture of a conventional density profile.
Spectral classification of stars in SMC clusters provide useful information on the evolutionary history of this galaxy and permit to test the theory of stellar evolution.
The existence of binary clusters in the Large Magellanic Cloud has been discussed recently. A survey of the LMC on UKSTU plates yielded a total of 69 pairs of clusters with a center-to-centre separation of less than ≡18 pc (for a distance modulus of 18.4 for the LMC). Statistical arguments suggest that taking chance line-ups into account, a significant fraction of the pairs found must be physically associated at the 7σ level. A series of observations have been undertaken in order to establish the physical association of the pairs.
