Technological Educational Institute of Piraeus

The main objectives of the KM3NeT Collaboration are (i) the discovery and subsequent observation of high-energy neutrino sources in the Universe and (ii) the determination of the mass hierarchy of neutrinos. These objectives are strongly motivated by two recent important discoveries, namely: (1) the highenergy astrophysical neutrino signal reported by IceCube and (2) the sizable contribution of electron neutrinos to the third neutrino mass eigenstate as reported by Daya Bay, Reno and others. To meet these objectives, the KM3NeT Collaboration plans to build a new Research Infrastructure consisting of a network of deep-sea neutrino telescopes in the Mediterranean Sea. A phased and distributed implementation is pursued which maximises the access to regional funds, the availability of human resources and the synergistic opportunities for the Earth and sea sciences community. Three suitable deep-sea sites are selected, namely off-shore Toulon (France), Capo Passero (Sicily, Italy) and Pylos (Peloponnese, Greece). The infrastructure will consist of three so-called building blocks. A building block comprises 115 strings, each string comprises 18 optical modules and each optical module comprises 31 photo-multiplier tubes. Each building block thus constitutes a threedimensional array of photo sensors that can be used to detect the Cherenkov light produced by relativistic particles emerging from neutrino interactions. Two building blocks will be sparsely configured to fully explore the IceCube signal with similar instrumented volume, different methodology, improved resolution and complementary field of view, including the galactic plane. One building block will be densely configured to precisely measure atmospheric neutrino oscillations.

Molybdenum oxide is used as a low-resistance anode interfacial layer in applications such as organic light emitting diodes and organic photovoltaics. However, little is known about the correlation between its stoichiometry and electronic properties, such as work function and occupied gap states. In addition, despite the fact that the knowledge of the exact oxide stoichiometry is of paramount importance, few studies have appeared in the literature discussing how this stoichiometry can be controlled to permit the desirable modification of the oxide's electronic structure. This work aims to investigate the beneficial role of hydrogenation (the incorporation of hydrogen within the oxide lattice) versus oxygen vacancy formation in tuning the electronic structure of molybdenum oxides while maintaining their high work function. A large improvement in the operational characteristics of both polymer light emitting devices and bulk heterojunction solar cells incorporating hydrogenated Mo oxides as hole injection/extraction layers was achieved as a result of favorable energy level alignment at the metal oxide/organic interface and enhanced charge transport through the formation of a large density of gap states near the Fermi level.

The fundamental period is one of the most critical parameters for the seismic design of structures. There are several literature approaches for its estimation which often conflict with each other, making their use questionable. Furthermore, the majority of these approaches do not take into account the presence of infill walls into the structure despite the fact that infill walls increase the stiffness and mass of structure leading to significant changes in the fundamental period. In the present paper, artificial neural networks (ANNs) are used to predict the fundamental period of infilled reinforced concrete (RC) structures. For the training and the validation of the ANN, a large data set is used based on a detailed investigation of the parameters that affect the fundamental period of RC structures. The comparison of the predicted values with analytical ones indicates the potential of using ANNs for the prediction of the fundamental period of infilled RC frame structures taking into account the crucial parameters that influence its value.

Interference plays a crucial role for performance degradation in communication networks nowadays. An appealing approach to interference avoidance is the Interference Cancellation (IC) methodology. Particularly, the Successive IC (SIC) method represents the most effective IC-based reception technique in terms of Bit-Error-Rate (BER) performance and, thus, yielding to the overall system robustness. Moreover, SIC in conjunction with Orthogonal Frequency Division Multiplexing (OFDM), in the context of SIC-OFDM, is shown to approach the Shannon capacity when single-antenna infrastructures are applied while this capacity limit can be further extended with the aid of multiple antennas. Recently, SIC-based reception has studied for Orthogonal Frequency and Code Division Multiplexing or (spread-OFDM systems), namely OFCDM. Such systems provide extremely high error resilience and robustness, especially in multi-user environments. In this paper, we present a comprehensive survey on the performance of SIC for single- and multiple-antenna OFDM and spread OFDM (OFCDM) systems. Thereby, we focus on all the possible OFDM formats that have been developed so far. We study the performance of SIC by examining closely two major aspects, namely the BER performance and the computational complexity of the reception process, thus striving for the provision and optimization of SIC. Our main objective is to point out the state-of-the-art on research activity for SIC-OF(C)DM systems, applied on a variety of well-known network implementations, such as cellular, ad hoc and infrastructure-based platforms. Furthermore, we introduce a Performance-Complexity Tradeoff (PCT) in order to indicate the contribution of the approaches studied in this paper. Finally, we provide analytical performance comparison tables regarding to the surveyed techniques with respect to the PCT level.

The purpose of this study is to discover the factors shaping public opinion about renewable energy sources and investigate willingness to pay for expansion of renewable energy sources in the electricity mix. Data was collected through a questionnaire applied in Nikaia, an urban municipality of Greece. The respondents have a positive attitude towards renewable energy systems. Most of them have good knowledge of solar and wind energy systems and are using solar water heating, while several respondents own a solar PV system. Environmental protection is seen as the most important reason for investing in a renewable energy system. Willingness to pay for a wider penetration of RES into the electricity mix was estimated to be 26.5 euros per quarterly electricity bill. The statistical analysis revealed the existence of a relationship between RES perceived advantages and willingness to pay for renewable energy. Furthermore, by using a binary logit model, willingness to pay was found to be positively associated with education, energy subsidies, and state support.

Person identification based on parametric spectral analysis of the EEG signal is addressed in this work-a problem that has not yet been seen in a signal-processing framework, to the best of our knowledge. AR parameters are estimated from a signal containing only the alpha, rhythm activity of the EEG. These parameters are used as features in the classification step, which employs a learning vector quantizer network. The proposed method was applied on a set of real EEG recordings made on healthy individuals, in an attempt to experimentally investigate the connection between a person's EEG and genetically-specific information. Correct classification scores at the range of 72% to 84% show the potential of our approach for person classification/identification and are in agreement with previous research showing evidence that the EEG carries genetic information.

In this work a hydrogenated under-stoichiometric tungsten oxide is introduced as an efficient anode interlayer in organic photovoltaics (OPVs). The benefits of hydrogen incorporation into the oxide lattice for obtaining desirable properties of tungsten oxides are explored. These benefits include the occupation of gap states near the Fermi level, which may facilitate charge transport, and the maintenance of a high work function, nearly similar to that of the stoichiometric tungsten oxide, which contributes to the formation of a large interfacial dipole at the anode interface and enhances charge extraction. A large improvement was achieved in the operational characteristics – especially in the open-circuit voltage – of bulk heterojunction solar cells based on different polymeric donors, namely poly(3-hexylthiophene), P3HT, or poly[(9-(1-octylnonyl)-9H-carbazole-2,7-diyl)-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl], PCDTBT, and the fullerene acceptor [6,6]-phenyl-C71 butyric acid methyl ester, PC71BM, that incorporated a hydrogenated tungsten oxide as an anode interlayer. This improvement was correlated with the devices' incident photon-to-electron conversion efficiencies (IPCEs) and impedance measurements. Furthermore, an increase in both the device's flat-band voltage (Vfb) and the doping level of the organic semiconductor was measured in P3HT:PC71BM based devices by Mott–Schottky capacitance analysis. Additional benefits are the large process window established for the devices incorporating the hydrogenated tungsten oxide as an anode interlayer and the maintenance of a high PCE (>80% of its initial efficiency) over 50 days, demonstrating good long-term stability, which is much better than that of the conventional devices based on PEDOT:PSS. The results suggest that the interface engineering with hydrogen-treated metal oxide interlayers is an important strategy to develop highly performing and stable organic photovoltaics.

A multiuser dual-hop relaying system over mixed radio frequency/free-space optical (RF/FSO) links is investigated. Specifically, the system consists of m single-antenna sources, a relay node equipped with n≥ m receive antennas and a single photo-aperture transmitter, and one destination equipped with a single photo-detector. RF links are used for the simultaneous data transmission from multiple sources to the relay. The relay operates under the decode-and-forward protocol and utilizes the popular V-BLAST technique by successively decoding each user's transmitted stream. Two common norm-based orderings are adopted, i.e., the streams are decoded in an ascending or a descending order. After V-BLAST, the relay retransmits the decoded information to the destination via a point-to-point FSO link in m consecutive timeslots. Analytical expressions for the end-to-end outage probability and average symbol error probability of each user are derived, while closed-form asymptotic expressions are also presented. Capitalizing on the derived results, some engineering insights are manifested, such as the coding and diversity gain of each user, the impact of the pointing error displacement on the FSO link and the V-BLAST ordering effectiveness at the relay.

This study examines the impact of environmental, social, and governance (ESG) reputational risk on a sample of listed firms’ market longevity. Using a novel panel dataset consisting of US firms over the period 2007–2019, we perform dynamic empirical analysis to quantify the underlying relationships between firms’ ESG reputational risk and market longevity. We argue that ESG reputational risk has a negative impact on firm growth opportunities, mitigating thus market longevity. The empirical findings survive several robustness checks, providing useful managerial implications for stakeholders and market participants..

Purpose – Cement production has advanced greatly in the last few decades. The traditional fuels used in traditional kilns include coal, oil, petroleum coke, and natural gas. Energy costs and environmental concerns have encouraged cement companies worldwide to evaluate to what extent conventional fuels can be replaced by waste materials, such as waste oils, mixtures of non-recycled plastics and paper, used tires, biomass wastes, and even wastewater sludge. The paper aims to discuss these issues. Design/methodology/approach – The work is based on literature review. Findings – The clinker firing process is well suited for various alternative fuels (AF); the goal is to optimize process control and alternative fuel consumption while maintaining clinker product quality. The potential is enormous since the global cement industry produces about 3.5 billion tons that consume nearly 350 million tons of coal-equivalent fossil and AF. This study has shown that several cement plants have replaced part of the fossil fuel used by AF, such waste recovered fuels. Many years of industrial experience have shown that the use of wastes as AF by cement plants is both ecologically and economically justified. Originality/value – The substitution of fossil fuels by AF in the production of cement clinker is of great importance both for cement producers and for society because it conserves fossil fuel reserves and, in the case of biogenic wastes, reduces greenhouse gas emissions. In addition, the use of AF can help to reduce the costs of cement production.

BACKGROUND: Particulate matter with diameter less than 10 micrometers (PM10) that originates from anthropogenic activities and natural sources may settle in the bronchi and cause adverse effects possibly via oxidative stress in susceptible individuals, such as asthmatic children. This study aimed to investigate the effect of outdoor PM10 concentrations on childhood asthma admissions (CAA) in Athens, Greece. METHODS: Daily counts of CAA from the three Children's Hospitals within the greater Athens' area were obtained from the hospital records during a four-year period (2001-2004, n = 3602 children). Mean daily PM10 concentrations recorded by the air pollution-monitoring network of the greater Athens area were also collected. The relationship between CAA and PM10 concentrations was investigated using the Generalized Linear Models with Poisson distribution and logistic analysis. RESULTS: There was a statistically significant (95% CL) relationship between CAA and mean daily PM10 concentrations on the day of exposure (+3.8% for 10 microg/m3 increase in PM10 concentrations), while a 1-day lag (+3.4% for 10 microg/m3 increase in PM10 concentrations) and a 4-day lag (+4.3% for 10 microg/m3 increase in PM10 concentrations) were observed for older asthmatic children (5-14 year-old). High mean daily PM10 concentration (the highest 10%; >65.69 microg/m3) doubled the risk of asthma exacerbations even in younger asthmatic children (0-4 year-old). CONCLUSIONS: Our results provide evidence of the adverse effect of PM10 on the rates of paediatric asthma exacerbations and hospital admissions. A four-day lag effect between PM10 peak exposure and asthma admissions was also observed in the older age group.

OBJECTIVE: To assess serum levels of carbohydrate antigen 125 (CA125) in patients with chronic congestive heart failure (CHF) and to assess any correlation with clinical symptoms and echocardiographic indices. PATIENTS AND METHODS: We enrolled 77 male patients (mean age: 73+/-10 years) admitted to the Cardiology Emergency Department (ED) with cardiac symptoms requiring hospitalization. Diagnosis of CHF was based upon medical history or initial echocardiographic evaluation on current admission. Serum CA125 was measured by an enzyme immunoradiometric assay, on admission and before discharge. RESULTS: The median overall CA125 value was 22.4 (11.5-48.9) U/ml. Serum CA125 levels were related to the severity of CHF [New York Heart Association (NYHA) class I: 19.2 (7.2-31) U/ml, NYHA class II: 17.6 (10-23) U/ml, NYHA class III: 32 (25-77) U/ml and NYHA class IV: 34.3 (18.6-77) U/ml (p<0.04)]. Patients in NYHA classes III and IV had significantly higher mean values of CA125, than patients in class II (p<0.005 and p<0.05, respectively). Moreover, patients with fluid congestion (pulmonary congestion, ankle edema) had higher levels of serum CA125 than patients without congestion (p=0.002 and p<0.03, respectively). Finally, levels of serum CA125 correlated weakly with right ventricular systolic pressure (RVSP) and renal function, while no significant correlation was found between CA125 and E wave deceleration time on Doppler echocardiography, left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter (LVEDD), liver function and the medical treatment prescribed. CONCLUSION: Serum CA125 is associated with the clinical severity of CHF and the symptoms and signs of fluid congestion and therefore may be a useful additional tool for the evaluation and clinical staging of these patients.

This review provides a summary of methods originated in (non-equilibrium) statistical mechanics and information theory, which have recently found successful applications to quantitatively studying complexity in various components of the complex system Earth. Specifically, we discuss two classes of methods: (i) entropies of different kinds (e.g., on the one hand classical Shannon and R´enyi entropies, as well as non-extensive Tsallis entropy based on symbolic dynamics techniques and, on the other hand, approximate entropy, sample entropy and fuzzy entropy); and (ii) measures of statistical interdependence and causality (e.g., mutual information and generalizations thereof, transfer entropy, momentary information transfer). We review a number of applications and case studies utilizing the above-mentioned methodological approaches for studying contemporary problems in some exemplary fields of the Earth sciences, highlighting the potentials of different techniques.

Abstract Here, we report on the dual functionality of tungsten oxide for application as an efficient electron and hole injection/transport layer in organic light‐emitting diodes (OLEDs). We demonstrate hybrid polymer light‐emitting diodes (Hy‐PLEDs), based on a polyfluorene copolymer, by inserting a very thin layer of a partially reduced tungsten oxide, WO 2.5 , at the polymer/Al cathode interface to serve as an electron injection and transport layer. Significantly improved current densities, luminances, and luminous efficiencies were achieved, primarily as a result of improved electron injection at the interface with Al and transport to the lowest unoccupied molecular orbital (LUMO) of the polymer, with a corresponding lowering of the device driving voltage. Using a combination of optical absorption, ultraviolet spectoscopy, X‐ray photoelectron spectroscopy, and photovoltaic open circuit voltage measurements, we demonstrate that partial reduction of the WO 3 to WO 2.5 results in the appearance of new gap states just below the conduction band edge in the previously forbidden gap. The new gap states are proposed to act as a reservoir of donor electrons for enhanced injection and transport to the polymer LUMO and decrease the effective cathode workfunction. Moreover, when a thin tungsten oxide film in its fully oxidized state (WO 3 ) is inserted at the ITO anode/polymer interface, further improvement in device characteristics was achieved. Since both fully oxidized and partially reduced tungsten oxide layers can be deposited in the same chamber with well controlled morphology, this work paves the way for the facile fabrication of efficient and stable Hy‐OLEDs with excellent reproducibility.

Abstract The problem of energy conservation in buildings is a multidimensional one. Researchers from a variety of disciplines have been working on this problem. It remains a challenging and yet rewarding study. In the past three decades, a plethora of scientific and technological publications on energy conservation in buildings have been presented in international journals. In this work, we discuss the potentiality of artificial intelligence (AI) as a design tool in building an automation system. The application of contemporary AI techniques creates intelligent buildings with the following main goals: energy efficiency, comfort, health and productivity in living spaces. Two modern domains of AI that are widely used in buildings are computational intelligence (CI) or soft computing and distributed artificial intelligence (DAI). DAI includes intelligent agents (IAs), multi-agent systems (MASs) and ambient intelligence. However, there is a lack of systematic review of research efforts and achievements mainly on IA and MAS domains. This chapter briefly presents expert systems and CI techniques and outlines how they operate. The major objective of this chapter is to illustrate how IAs and MASs may play an important role in conserving energy in buildings.

Person identification based on features extracted parametrically from the EEG spectrum is investigated in this work. The method proposed utilizes computational geometry algorithms (convex polygon intersections), appropriately modified, in order to classify unknown EEGs. The signal processing step includes EEG spectral analysis for feature extraction, by fitting a linear model of the AR type on the alpha rhythm EEG signal. The correct classification scores obtained on real EEG data experiments (91% in the worst case) are promising in that they corroborate existing evidence that EEG carries genetically specific information and is therefore appropriate as a basis for person identification methods.

Radon concerns the international scientific community from the early twentieth century, initially as radium emanation and nearly the second half of the century as a significant hazard to human health. The initial brilliant period of its use as medicine was followed by a period of intense concern for its health effects. Miners in Europe and later in the U.S were the primary target groups surveyed. Nowadays, there is a concrete evidence that radon and its progeny can cause lung cancer (1). Human activities may create or modify pathways increasing indoor radon concentration compared to outdoor background. These pathways can be controlled by preventive and corrective actions (2). Indoor radon and its short-lived progeny either attached on aerosol particles or free, compose an air mixture that carries a significant energy amount [Potential Alpha-Energy Concentration (PAEC)]. Prior research at that topic focused on the exposure on PAEC and the dose delivered by the human body or tissues. Special mention was made to the case of water workers due to inadequate data. Furthermore, radon risk assessment and relevant legislation for the dose delivered by man from radon and its progeny has been also reviewed.

Abstract As the number of courses offered online increases rapidly, it is important for teachers and institutions to identify specific learner characteristics of successful online students. This paper reports on a study that compared an online group of freshmen computer science majors with an equivalent on‐campus group to find if their individual learning styles play a role in the selection of course delivery mode (online or face to face) and in their academic achievement. No significant statistical differences were detected in learning styles and learning performance between the two groups. Implications for teaching practice and design of learning activities that resulted from this study are discussed.

This article presents the design methodology for an in-situ solar panel monitoring system based on wired and wireless sensor network technologies. The system presented provides in-situ performance data for each solar panel of a solar park installation and allows through a web-based application the optimization of electric power production. The proposed platform is based on wired networking technologies combined with short range low-power wireless sensor nodes. Performance parameters are measured for each PV panel and are transmitted to a remote coordinator. Details about the developed platform are presented with preliminary results.

We present a low-cost, fully computer-controlled, Arduino-based, educational laboratory (SolarInsight) to be used in undergraduate university courses concerned with electrical engineering and physics. The major goal of the system is to provide students with the necessary instrumentation, software tools and methodology in order to learn fundamental concepts of semiconductor physics by exploring the process of an experimental physics inquiry. The system runs under the Windows operating system and is composed of a data acquisition/control board, a power supply and processing boards, sensing elements, a graphical user interface and data analysis software. The data acquisition/control board is based on the Arduino open source electronics prototyping platform. The graphical user interface and communication with the Arduino are developed in C# and C++ programming languages respectively, by using IDE Microsoft Visual Studio 2010 Professional, which is freely available to students. Finally, the data analysis is performed by using the open source, object-oriented framework ROOT. Currently the system supports five teaching activities, each one corresponding to an independent tab in the user interface. SolarInsight has been partially developed in the context of a diploma thesis conducted within the Technological Educational Institute of Piraeus under the co-supervision of the Physics and Electronic Computer Systems departments' academic staff.