Panos Yannakopoulos

Panos Yannakopoulos
University of West Attica | TEIATH · Department of Informatics and Computer Engineering

Ph.D in Semiconductor Physics

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70
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363
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Publications

Publications (70)
Article
Full-text available
This paper reports measurements of radon in groundwater conducted in China between Janu-ary 2013 and December, 2013. During measurements, a great Ms=6.6 earthquake occurred in the Gansu province China. The paper analyses data derived from three nearby stations via monofractal and multifractal detrended fluctuations analysis and explores whether pre...
Article
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This paper reports a review on the relationship between seismic activity and the emissions of CO2 and radon. Direct, indirect and sampling methods are mainly employed to measure CO2 flux and concentration in seismic areas. The accumulation chamber technique is the mostly used in the literature. Radon gas Page of 2 19 emission in seismic areas can b...
Article
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This paper utilises statistical and entropy methods for the investigation of a 17-year PM10 time series recorded from five stations in Athens, Greece, in order to delineate existing stochastic and self-organisation trends. Stochastic patterns are analysed via lumping and sliding, in windows of various lengths. Decreasing trends are found between Wi...
Article
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Several field models have been applied to find reliable precursors for studying the behavior of seismic CO 2 fluxes. Indirect and direct methods are used to calculate the gradient of soil flux according to empirical relationships. Various tools and methods are also used to estimate CO 2 flux from soil in seismic areas. This article reports on the r...
Article
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This paper reports one-month 3 kHz EM disturbances recorded at Kardamas, Ilia, Greece after a strong M L = 6 . 6 earthquake occurred on 2018/10/25 near Zakynthos and Ilia. During this period 17 earthquakes occurred with magnitudes M L = 4 . 5 and M L = 5 . 5 and depths between 3 km and 17 km, all near Zakynthos and Ilia. A two-stage, fully computat...
Article
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This article reports fractal dimension analysis applied to soil CO2 fluxes measured in an Italian seismic area. The work was carried out with the use of a calibrated flux chamber unit. The fractal dimension (FD) from isotropic variograms was used as a method to understand related scale-dependent phenomena. The aim was to investigate the spatial var...
Article
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The recent seismic activity in the eastern Aegean Sea, foregrounded by two major (ML = 6.1 and ML = 6.2) earthquakes occurring near Lesvos and Kos islands, respectively, is investigated in this work. Electromagnetic radiation measurements across different frequency bands and antenna orientations from a monitoring station in Agia Paraskevi, Lesvos i...
Article
The aim of this work was to prepare composite ZnCdSeS quantum dot (QD) flexible films and to examine their optical properties under ultraviolet excitation. PMMA/ QD ZnCdSeS composite films, with emission covering the visual spectrum (480 to 630 nm) were prepared with concentrations 10mg/mL and 20mg/mL by homogenously diluting dry powder QD samples...
Article
This paper reports radioluminescence properties of the CdSe/ZnS quantum dots. Three quantum dot samples were prepared with concentrations 14.2 × 10−5 mg/mL, 21.3 × 10−5 mg/mL and 28.5 × 10−5 mg/mL, respectively. The ultraviolet induced emission spectra of CdSe/ZnS dots exhibited a peak at 550 nm ranging between 450 nm and 650 nm. Discrepancies obse...
Article
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A multichannel, multi-frequency approach on the analysis of critical electromagnetic (EM) signatures prior to earthquakes is presented. The algorithm employed is based on single-channel techniques for the identification of long-memory trends in fractal processes and attempts to take advantage of the increased information content that is provided by...
Article
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This paper reports characteristic preseismic electromagnetic disturbances in the MHz range detected prior to seven significant earthquakes of M L >= 5.0 which occurred in Greece between 2009 and 2015. The whole data set was investigated through Rescaled Range ( R / S ) analysis and wavelet- based spectral fractal analysis. The long-memory trends hi...
Article
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This paper addressed fractal evolution of eleven one-month lasting MHz electromagnetic disturbances, recorded in Greece prior to nine significant earthquakes of 2009. Time-space wavelet-based power spectral techniques were employed in the analysis. All investigated signals evolved naturally to epochs of fractal organisation in space and time. Contin...
Chapter
The aim of the present study was to investigate the absolute luminescence efficiency (AE) of mixed oxyorthosilicate (Lu,Gd)2SiO5:Ce (LGSO:Ce) single crystals, under X-ray irradiation. Six (Lu,Gd)2SiO5:Ce crystal samples, with dimensions of 3 × 3 × 5, 3 × 3 × 6, 3 × 3 × 10, 3 × 3 × 15, 10 × 10 × 10 and 10 × 10 × 20 mm3 were examined. The light emitt...
Chapter
This paper presents the luminescence efficiency (LE) of toluene dissolved Cadmium Selenide/Zinc Sulfide (CdSe/ZnS) quantum dot (QD) samples after their irradiation with X-rays and UV. The LE was investigated as a function of the weight over volume (w/v) QD concentration under variable fluxes of X-rays and wavelengths of UV radiation. All the sample...
Chapter
This paper outlines the use of radiation sensors and nanosensory systems in medical imaging modalities emphasising on the digital ones. Sensors have been widely used in various disciplines e.g. optoelectronics and non-distractive testing. Recently novel sensors such as nanophosphors and Nanocrystal Quantum Dots (QDs) has attracted attention due to...
Book
This collection of selected review papers focuses on topics such as digital radiation sensors and nanosensory systems for nanotechnology applications and integrated X-ray/PET/CT detectors; nanophosphors and nanocrystal quantum dots as X-ray radiation sensors; the luminescence efficiency of CdSe/ZnS QD and UV-induced luminescence efficiency distribu...
Article
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Indoor air quality (IAQ) is an active field of research due to the health impacts that the air pollutants impose to humans. To investigate the situation for Greece, this study modelled with CONTAM(W) the distribution of concentrations of certain air pollutants that are present in Greek dwellings. For the simulations, typical Greek dwellings were de...
Conference Paper
Full-text available
The geometrical behaviour of the conductivity of gold coated textiles for applications in textile electrodes, to be used in measuring biomedical signals is examined. Flexible fibrous sensors in dimensions of 3x3cm from Kevlar yarns coated with gold were produced. The deposition steps were optimized and the obtained layers are characterised with dif...
Article
Full-text available
In the current study preliminary results on the luminescence efficiency (LE) of toluene dissolved Cadmium Selenide/Zinc Sulfide (CdSe/ZnS, Sigma-Aldrich, Lumidot 694622) quantum dot samples (QDs) after exposure to X-rays of variable radiation flux are shown. The distinctive influence of the weight over volume (w/v) concentration of the samples in L...
Article
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This paper attempts to survey and catalog published short-term pre-earthquake precursors based on radon gas emissions. A series of papers were searched to collect relevant data, such as the epicentral distance, the extent, time and duration of the radon disturbance and to analyze the precursory value of each observable. In general, enhanced radon e...
Article
The main purpose of this work was to investigate the fluctuation of Greek indoor electromagnetic field (EMF) intensity values and identify peaks that might occur. The scientific interest is mainly focused on the bands of extremely low-frequency (ELF) magnetic fields and radiofrequency (RF) electric fields which have been suggested to be possibly ca...
Article
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This paper reports preliminary electromagnetic field measurements conducted indoors in selected locations in Greece. The paper focuses on the electromagnetic radiation (EMR) of the extremely low-frequency (ELF) and radiofrequency (RF) frequency bands because these bands are considered as possible human carcinogens according to the Scientific Commit...
Article
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In this paper, a novel algorithm is introduced for the analysis of long-memory patterns hidden in electromagnetic (EM) readings prior to earthquakes. The algorithm builds upon previous work on long-memory detection in EM measurements by fusing Support Vector Machine (SVM) classifiers with well-deployed power law fit tests and Rescaled-Range (R/S) t...
Article
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On 17 November 2014, at 23:05 and 23:09 local time, two shallow earthquakes of ML=5.1 occurred in Prokopion, Chalkis, 86 km North-West of Athens, Greece. Prior to the earthquakes a significant radon anomaly was observed by a telemetric radon station operating with a Barasol MC2 probe (Algade France). The anomaly lasted approximately between 24 Oct...
Article
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This paper is a survey of pre-earthquake short-term electromagnetic precursors. Extensive studies were carried out the last decades in analysis of electromagnetic emissions from 10-3Hz up to MHz. These signals were analyzed through visual, statistical and chaotic techniques. The paper presents cumulative elements from scientific investigations perf...
Chapter
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Solid state nuclear track detectors (SSNTDs) have been widely used as sensors of radon and progeny in long-term dosimetry because they exhibit high detection properties while their cost is very low. Alpha-particle energy calculating codes, specific for every incident particle, increase the Monte-Carlo simulation time significantly. The expression o...
Article
The main purpose of this work was to investigate the fluctuation of Greek indoor electromagnetic field (EMF) intensity values and identify peaks that might occur. The scientific interest is mainly focused on the bands of extremely low-frequency (ELF) magnetic fields and radiofrequency (RF) electric fields which have been suggested to be possibly ca...
Article
Full-text available
GATE is advanced open source software dedicated to numerical simulations in medical imaging and radiotherapy. It currently supports simulations of Emission Tomography (Positron Emission Tomography-PET and Single Photon Emission Computed Tomography-SPECT), Computed Tomography (CT) and Radiotherapy experiments. This work focused on the commercial Bio...
Article
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Volatile Organic Compounds (VOCs) are toxic chemicals harmful for the environmental sustainability and human health. Due to the several types of VOCs and the diversity in their physico-chemical properties, it is difficult to develop standard methods for sampling and analysis. The majority of methods depend on the compounds of interest and the requi...
Conference Paper
Last achievements in information science and technology illuminated some important approaches and ways to increase the human security through different scientific methods and technology innovations. Elaboration of new information systems including nanosensory instruments and quantum sensory devices create the unique possibilities to develop new met...
Conference Paper
Full-text available
Radon and progeny (218Po, 214Pb, 214Bi and 214Po) are important radioactive indoor air pollutants with impact to humans. Radon is an inert gas that enters buildings from outdoor air, water and soil especially through gaps around pipes and cables and through cracks in floors. Upon entering, radon disintegrates to progeny which are free or attach to...
Conference Paper
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In the frame of the UNITE Tempus project, the main intention is to connect the necessities of the industry with the higher educational system in Belarus. Aiming to achieve this, is taking in mind the existing systems in the European countries taking part at the project, like Greece, Belgium, Spain, Portugal. Until now, there have been implemented s...
Conference Paper
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In the latest years, Internet-of-Things gave numerous advantages in making houses smarter in terms of energy, danger, information, notifications and in general monitoring. Miniaturized sensors and developed services can offer different communication paths available in various smart devices via cloud based technologies like Data-as-a-Service (DaaS),...
Article
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Health concerns have been raised, especially following the enormous increase in the use of wireless mobile telephony (GSM, 3G and 4G) throughout the world. A similar situation exists regarding other digital wireless systems, such as data communication networks, Bluetooth, Wi-Fi, DECT phones and CB’s which emit in various regions of the spectrum giv...
Article
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International studies of radon indoors and in workplaces have shown significant radiation dose burden of the general population due to inhalation of radon (222Rn) and its short-lived progeny (218Po,214Pb, 214Bi, 214Po). As far as atmospheric radon concerns, 222Rn, is not necessarily in equilibrium with its short-lived progeny. For this reason, rado...
Article
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A large scale nationwide radon survey was conducted in Greek dwellings between 1994 and 2000. Twelve hundred passive CR-39 detectors were distributed and collected along with 963 filled in questionnaires. These were rechecked during 2012-13 to evaluate factors that potentially affect indoor radon concentrations, namely the factors (i) area (environ...
Article
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The natural electromagnetic environment originates from the Earth (terrestrial sources) and from space (extraterrestrial sources). Compared with man-made fields, natural fields are extremely small, especially at the radiofrequency band. Electric and magnetic fields exist wherever electricity is generated, transmitted or distributed from power stati...
Article
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Humans live and breathe every day in an envir onment full of natural and artificial radiation. Radiation's nature is energetic particles and/or electromagnetic waves. The damage to tissue from ionizing radiation is being studied decades ago. In contrast, concerns, about the potential health risk assoc iated with unprecedented exposure to non-ionizi...
Article
This paper addresses issues of self-affinity, long-memory and self-organisation in variations of radon in soil recorded in Lesvos Island, Greece. Several techniques were employed, namely (a) power-law wavelet spectral fractal analysis, (b) estimation of Hurst exponents through (b1) rescaled-range, (b2) roughness-length, (b3) variogram and (a), (c)...
Conference Paper
Full-text available
The main purpose of this study was to investigate different electromagnetic sources and characterize different environmental categories, namely urban, suburban, rural areas offices and workplaces. Based on the suggestions of WHO International EMF Project's RF Research Agenda and ICNIRP, measurement surveys are conducted to characterize population e...
Article
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This is a GATE-simulation study of the Siemens Biograph DUO PET/CT system. It reports effects of changes in the thickness of the employed Lutetium Oxyorthosilicate (LSO) detectors. The PET/CT, a human body phantom and a cylindrical F-18 FDG source were simulated. Validation measurements were conducted. The results indicate that LSO thickness increa...
Article
Radon and progeny ((218)Po, (214)Pb, (214)Bi and (214)Po) are radioactive indoor pollutants recognised for the human radiation burden that they induce. Bathing in thermal spas causes transient concentration peaks of radon and progeny and additional short-term impact in patients and personnel. This paper reports a semi-empirical non-linear first ord...
Article
This paper addresses issues of long-range memory and self-organisation in variations of radon in soil in Greece. The methods of rescaled-range, roughness-length, variogram, fractal dimension and block entropy were employed through lumping. Sliding was utilised with the wavelet spectral fractal technique. Antipersistent Hurst exponents in the range...
Conference Paper
Full-text available
Flexible fibrous sensors in dimensions of 3 x 3 cm from Kevlar yarns coated with gold to be used as electrodes in measuring were produced. The study is focused on the electrical properties (resistance – conductivity) to determine the homogeneity of the material throughout its’ surface. Linearity appeared across all five measured points using DC vol...
Conference Paper
The phase of rapid rehabilitation for people with "special needs" consists basic factor for their general health. Difficulties in learning have been observed for people with physical disabilities. New technologies and techniques are used for above purposes such as Virtual reality and imaging. Augmented reality suggests the next generation in compar...
Conference Paper
In most of students’ training boards of digital communication two methods are used for data transmission, NRZ (Non – Return to Zero) & RZ (Return to Zero). Difficulties are observed in distinguishing various types of codes where the above methods are used, due to the different approach of their description pattern. An encoding scheme method is sugg...
Conference Paper
It is known that a controllable system refers to the possibility for it to be transferred from a given initial state in any final, in finite time. Furthermore the observable constitutes the dualism of the controllable. From the code and information theory we know that a generator matrix G of a linear code is a binary table whose rows are the code w...
Conference Paper
Scientists, doctors and some European governments are adding their voices to the growing alarm that the universal use of mobile devices may be the start of a medical catastrophe for the future. Mobile phone radiation and health concerns have been raised, especially following the enormous increase in the use of wireless mobile telephony (GSM and 3G)...
Article
Full-text available
The behaviour of EL2 intrinsic defect in the Semi-Insulated (SI) undoped and Cr-doped GaAs is studied by measuring the Dember effect short circuit current. Appropriate illumination with peak in the 1100 nm region results in the transition of the EL2 state to its metastable one (EL2M). Of major importance is the Cr concentration, which is influencin...
Article
The interaction between radiation and matter is very important in the study of materials used in the aerospace industry. The improvement of the resistance of various devices is crucial. In the present work we have produced simulation results of damages induced in electronic devices of III–V semiconductor compounds, using SRIM-TRIM, CASINO and GEANT...
Article
The aim of the present work is to study the density of electron transitions inside the energy gap of SI-GaAs at various temperatures and under α-particle irradiation at 300K. The photocurrent as a function of photon energy from 1.35 to 1.80eV, for each temperature, was measured in the temperature range from 180 to 300K. From the spectra analysis fo...
Article
The aim of the present work is to investigate defects that are introduced to Gallium Phosphide (GaP) by electron irradiation as well as their dependence on the background doping. Undoped and Te doped n-type GaP have been irradiated with 1.5 MeV electrons at fluences of 5×1016 e/cm2. Deep level transient spectroscopy assessment revealed the dependen...
Article
Full-text available
In the present work, we study the influence of small energy α -particles (0.96 MeV) on the photoconductivity in order to construct a detector for small fluxes of low energy α -particles irradiation. Photocurrent measurements were carried out at room temperature (T=300K), before and after irradiation, on Semi-insulated (SI) GaAs specimens, with epil...