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Search Results: 1 - 10 of 260322 matches for " G. I. Karolidis "
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Advancing the Backtrack Optimization Technique to Obtain Forecasts of Potential Crisis Periods  [PDF]
E. G. Lisgara, G. I. Karolidis, G. S. Androulakis
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.330214
Abstract: Financial crisis is an unfortunate reality that overshadows any financial system regardless its profitability and the level it functions. The appearance of crises across financial markets, especially during the 1990s that the internationalized markets adopted a rather approachable character, imposed severe costs in financial and social systems. With this paper is proposed the generation of a future interval of time that is vulnerable to enclose the burst of a financial crisis. A time series consisted of approximations of the local Lipschitz constant is examined and in the proposed forecasting approach this constant holds the crisis indicator role. Further the application of two different optimization techniques over the Lipschitz-made time series results to the generation of a future period of time; this interval is likely to envelop the burst of a forthcoming crisis. The usage of a future interval of time empowers the predicting ability of the methodology by providing warning signs priory to the actual crisis burst. To this direction, the obtained results offer strong evidence that the method may be characterized as an Early Warning System (EWS) for financial crisis prediction.
The Influence of Ultrasonic Treatment on the Properties of Schottky Diodes  [PDF]
I. G. Pashayev
Open Journal of Acoustics (OJA) , 2013, DOI: 10.4236/oja.2013.33A002
Abstract: The given work studies the reason of the change of a superfluous current near crystallization temperature of an amorphous αPbSb metal alloy and at the same time founds out the influence of ultrasonic processing (USP) on the properties of αPbSb-nSi solar elements (SE), made by Shottki diodes technology (ShD) with a metal alloy. It is found that occurrence of a superfluous current αPbSb-nSi ShD under the influence of thermoannealing is connected with changes of structure of an amorphous film of metal at transition in a polycrystalline condition. VAC damaged αPbSb-nSi Sh Dare very sensitive to annealing time. Eventually, even at room temperature, level of a superfluous current decreases, i.e. the wound put by mechanical damage sort of heals, restoration process occurs the faster, the higher the annealing temperature is. Function of γt annealing parameters changes in an interval\"\" and the influence USP on photo-electric properties αPbSb-nSi SE depends on the chosen UIT mode.
Design and Efficient Controller for Micro Turbine System  [PDF]
G. Saravanan, I. Gnanambal
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.78106
Abstract: In this modern era, power generation seems to be a very demanding factor. New models and methods have been proposed to derive from various natural and manmade resources. In such instances, this paper gives a detailed report on the power generation from Micro Turbines. Microturbine plays a very important role in electric power generation. Especially they are used in thecombined cycle process power plants. The parameters of Rowen’s model 265-MW single shaftheavy duty gas turbines which are used in dynamic studies are estimated in this paper using the operational and performance data. These data are also used to briefly explain the extraction of parameters of the used model. Micro turbine parameters are approximated using simple thermodynamics assumptions. Micro turbine power generation seems to be an uprising and a promisingsource and an exact design with a perfect model is capable of producing the highest efficiency.Thus this paper is proposed on the aspects of social awareness to elaborate the control design ofMicro Turbine Power Generation System. The parameters of micro turbine models are derivedand the results of several simulated tests using Matlab/Simulink are presented.
Utilization of Bacterial Foraging Algorithm for Optimization of Boost Inverter Parameters  [PDF]
G. Arunkumar, Dr. I. Gnanambal
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.78125
Abstract: This paper proposes a boost inverter model capable of coping with changes in load as well as line parameters. In order to achieve an output AC voltage higher than the input DC voltage, we can use this model consisting of a pair of DC-DC converters with a load connected differentially across them. This paper aims at developing a boost inverter that is capable of achieving a very high gain, to obtain an AC voltage of 110 Vrms from a DC input of 36 V. This is exceptionally beneficial in renewable energy applications, where the input voltage garnered is quite small, and in need of stepping up for commercial use or transmission. However, aside from the voltage level itself, lowering the rise time, settling time, peak overshoot and steady state error of the system is of cardinal importance in order to maintain a reliable output voltage. Closed loop control of the differentially connected DC-DC converters is necessary to determine the optimal stable operating point. This paper addresses the above concerns through optimization of the proportional and integral constants using the novel Bacterial Foraging Algorithm, ensuring operation at the required optimal stable operating point. Moreover, load/line disturbances may occur due to which the stability of output voltage may be compromised and THD value may increase to undesirable extents. In these cases, utilization?of the output voltage is no longer viable for several applications sensitive to such voltage fluctuations. We have demonstrated that our proposed model is capable of restoring/reverting to the satisfactory sinusoidal waveform fashion within a single voltage cycle. The waveform results that demonstrate the resilience of our model to such disturbances are represented?appropriately.
Fuzzy Empowered Cognitive Spatial Relation Identification and Semantic Action Recognition  [PDF]
R. I. Minu, G. Nagarajan
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.78165
Abstract: Automatic labeling of the action held by the players in a live-in sports video is the main motivation of this paper. In this paper, we proposed a fuzzy-based action recognition system from a basketball sports image. This paper deals with the intellectual sports event action recognition from a live video stream. It required an intelligent system which would automatically and semantically label the action in the videos through machine understandability concept. The machine knowledge can be feed through the domain ontology of particular sports event. The major required component for this kind of system is an efficient image analysis component and automation action labelling component. The image is labelled using Type-2 Fuzzy set concept.
Integrated Expert Analytical System for Assessment of Oil-and-Gas Saturation of Strata  [PDF]
O. G. Nusratov, G. G. Abdullayeva, I. A. Ismayilov
Intelligent Control and Automation (ICA) , 2014, DOI: 10.4236/ica.2014.54024
Abstract: The present research deals with the problem of development of an integrated expert-analytical system for optimum selection of calculated oil-field-geophysical parameters of oil and gas deposits with the purpose of increasing the accuracy of assessment of the reserves of oil and gas deposits. The purpose of the system is to make current adequate decisions on determining of oil-and-gas saturation of strata and future identification of the most significant methods for that, with these methods forming the foundation of knowledge bases for oil-and-gas deposits of the Apsheron peninsula of Azerbaijan. The system architecture allows for expanding the system with its subsequent transformation into a cluster of expert-analytical systems. A logical model of the proposed system is presented. The paper contains a detailed description of the mechanism of operation of the system as a whole and of its individual blocks. Mathematical and formal-logical bases of the intelligent system are explained. The system is equipped with a tool for dynamic statistical analysis of decisions made by it, with representation of the results in real-time mode. The results of the system testing on specific oil-and-gas deposit of the Apsheron peninsula of Azerbaijan in 2013 are given.
Kinetics of Manganese Oxides Dissolution in Sulphuric Acid Solutions Containing Oxalic Acid  [PDF]
I. V. Artamonova, I. G. Gorichev, E. B. Godunov
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.59085
Abstract:

The kinetics of the interaction of MnO2, Mn2O3, and Mn3O4, with sulphuric acid solutions and the effect of oxalic acid on this process are studied. As the sulphuric acid concentration is increased from 0.1 to 5 N, the dissolution rate of Mn2O3, Mn3O4 to MnO2 and Mn2+ ions decreases, whereas it increases with the concentration of Mn2+ ions. Upon the addition of H2Ox, the complete dissolution of Mn3O4 occurs more quickly. The reaction order with respect to the H+ and O x2- ions is +0.5 ± 0.1. A mechanism of MnO2 dissolution promotion by O x2- is proposed. The dissolution rate was found to depend on the concentrations of MnHOx - ions and was highest at pH 1.6 ± 0.2. A rate law and mechanism are suggested for manganese oxides dissolution.

Antibacterial Action and Physicochemical Properties of Stabilized Silver and Gold Nanostructures on the Surface of Disperse Silica  [PDF]
I. Mukha, А. Eremenko, G. Korchak, А. Michienkova
Journal of Water Resource and Protection (JWARP) , 2010, DOI: 10.4236/jwarp.2010.22015
Abstract: This work is devoted to the synthesis and stabilization of nanosized Ag/SiO2 and Au/SiO2 disperse materials and investigation their morphology, optical and antimicrobial properties. First, Ag and Au nanoparticles (NPs) were produced in colloids via chemical (Ag) or photochemical (Au) reduction of appropriate ions. To prevent the oxidation of Ag NPs in colloid solution, external binary stabilizing agents PVP and SDS were used. Then, Ag and Au NPs (0.01-0.05% wt) were adsorbed from their colloid solutions on high disperse silica surface (Ssp=260m2/g) and samples prepared were dried. Materials obtained were studied by UV-vis, XRD, and TEM methods. Ag and Au NPs adsorbed on silica demonstrated a fair crystallinity in XRD. The surface plasmon resonance (SPR) band positions inherent to Ag and Au NPs on silica surface as well as the intensities of optical spectra were stable during 7 month and more. Obtained Ag NPs in colloids and Ag/SiO2 composites demonstrated excellent antimicrobial activity against a series of the microorganisms (Escherichia coli, Staphylococcus aurous, and Candida albicans). Au/SiO2 samples did not reveal any bactericide properties relative to the test microorganisms grown. The mechanisms of Ag(Au) NPs interaction with silica surface were analyzed.
Influence of Fracture Roughness on Aperture Fracture Surface and in Fluid Flow on Coarse-Grained Marble, Experimental Results  [PDF]
G. Dimadis, A. Dimadi, I. Bacasis
Journal of Geoscience and Environment Protection (GEP) , 2014, DOI: 10.4236/gep.2014.25009
Abstract:

Wetting fluid flow through rock discontinuities influence a great number of project among others: dam construction, underground projects, CO2 storage in underground schemes, geological disposal of radioactive wastes; Hydrocarbon storage caverns. Flow through fractures is considered to be laminar due to small aperture of the fracture walls and slow velocity. The fluid model called “Cubic law” describes the flow assuming parallel infinite plates. However, natural discontinuities on rock have roughness. In this experimental study an induced fracture on a sample of medium-grained marble was used, to determine the influence of roughness in water flow. This study is a preliminary part of research funding program for flow of CO2 through rocks (AUTH-GEOMechanics and Environment of CO2 geological Storage, Project No. 456,400).

Acid-Base Properties of Aqueous Suspensions of Homoionic Sepiolite and Palygorskite  [PDF]
Silvia G. Acebal, Leticia I. Vico
Natural Resources (NR) , 2017, DOI: 10.4236/nr.2017.86028
Abstract: Acid-base properties of Na-sepiolite and Na-palygorskite were studied by potentiometric titrations at 298 K and two ionic strength I = 0.1 and I = 0.002. Intrinsic constants of deprotonation were calculated by two different methods: a) Stumm method, by extrapolating to zero the function that relates surface charge with the logarithms of apparent acidity constants and b) with MINTEQ program by minimizing the differences between surface H+ concentration data and the values obtained from deprotonation constants proposed according to the Diffuse-Double-Layer Model (DDLM). Hydroxyl groups located at the broken edges of these fibrous clay minerals (SOH) and permanent charge sites (X-) were considered as reactive sites. The determined values of the acid-base constants for Na-sepiolite and Na-palygorskite were intermediate between those for SiO2 and \"\"Al2O3, which is in agreement with minerals that contain moderately strong-acidity and weak-acidity surface groups. The SOH groups showed an initial increase (after SOH2+ deprotonation), forming a plateau with a slight de-crease at high pH values (8-9) due to the formation of SO- sites. X- sites ad-sorbed H+, Na+ or Mg2+ ions.
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