Technological Educational Institute of Chalkida
Chalkida, Greece
Time filter
Source Type

Agency: European Commission | Branch: FP7 | Program: CP | Phase: SEC-2007-1.3-01;SEC-2007-4.3-03 | Award Amount: 2.64M | Year: 2008

The proposal concerns the technology development for instruments with the following capabilities: (a) To make spectroscopic measurements with efficiency equivalent to that of NaI detectors and energy resolution close to that of HPGe devices but without using cryogenic systems. (b) To find the direction and the distance of the radioactive source. (c) To localize the source into a cargo and estimate the radioactive source activity taking information about the source environment (shielding, absorption in the surrounding materials) (d) To work at a wide range of absorbed dose rates by adjusting the effective volume of the detector. The above capabilities will improve the quality of the data gathered by the customs officers during the routine inspections at the boarders and will assist the first responders in case of a radiological or nuclear emergency to estimate the exact situation. Basic tasks of the project will be: (a) The growth of high purity, detector grade Cd(Zn)Te crystals. Their performance will be optimized by material purification, selection of right dopants and post-growth processing to obtain high resistivity, high transport properties and homogeneous distribution of these material properties in the grown crystals. The growth of crystals with a diameter up to 75 mm will be performed. (b) The fabrication of pixel detectors having structure of p-n and Schottky diodes. This will permit the application of bias voltage high enough to collect all the induced charge by both electrons and holes. (c) The design of pixel electronics capable for simultaneous imaging and spectroscopy. The electronics will be bump bonded to the pixel detectors. This is essential for the localization and the identification of the radioactive source. (d) The construction of a portable instrument having a stack of detecting elements. This will allow to exploit the Compton Effect for the localization of the radioactive source and also to have variable detection efficiency.

Agency: European Commission | Branch: FP7 | Program: CP | Phase: ICT-2009.3.5 | Award Amount: 3.41M | Year: 2010

The quick growth of the Virtual Sensor Networking (VSN) domain has led to a highly dispersed gamut of\ntechnologies and approaches, which seriously jeopardize the long-term vision of an Internet of Things\nsince very few of these solutions are able to mutually communicate. VITRO aims at providing this crucial\nbut missing link between highly heterogeneous wireless sensors and actuators platforms and hence\nfacilitate cooperative smart objects. This proposal is focused on developing architectures, algorithms and\nengineering methods, which will enable the realization of scalable, flexible, adaptive, energy-efficient and\ntrust-aware VSN platforms. To achieve this objective, VITRO enabled platforms will:\n Provide a homogeneous abstract appearance to enable federated collaboration with external entities\n(from objects and systems to domains and networks) and thereby extending the networking degree by several orders of magnitudes.\n Simplify the discovery and management of the underlying hardware and software resources of large\ncollections of heterogeneous smart objects (sensors, actuators and embedded processors).\n Achieve energy-efficiency, trust-awareness and seamless connectivity and communication in large-scale\nheterogeneous VSN deployments and thereby enable dependable, secure and scalable inter-objects\ncollaboration.\nThe VITRO results will be packed in a VITRO toolbox, which will enable easy configuration and instant\nsupport for deploying VSN applications. Although VITRO aims to be application-neutral, the proposed\narchitecture and protocol toolbox will be validated through extensive simulation testing and furthermore\nimplemented in a large trial of sensor nodes and smart objects in smart home and building automation\napplication domains. Moreover, the developed technologies will be proposed as new standards for embedded networking solutions, mainly to ETSI M2M, 6LowPAN and IETF ROLL.

Agency: European Commission | Branch: FP7 | Program: CP | Phase: ICT-2007.1.4 | Award Amount: 3.10M | Year: 2008

AWISSENET (Ad-hoc personal area network and WIreless Sensor SEcure NETwork) is a project focused on security and resilience across ad-hoc PANs and wireless sensor networks. AWISSENET motivation is to implement and validate a scalable, secure, trusted networking protocol stack, able to offer self-configuration and secure roaming of data and services over multiple administrative domains and across insecure infrastructures of heterogeneous ad-hoc and wireless tiny sensory networks. AWISSENET optimisations will be extended where applicable from networking up to the applications layer, focusing on three key principles:\n Discovery, evaluation and selection of trusted routes based on multiple security metrics and key pre-distribution methods. The overall scheme must support secure routing even with disappearing nodes, multiple levels of in-network processing and multiple layers of aggregation. Moreover to protect the secure routing information from traffic analysis attacks, we will research utilisation of dynamic obfuscation of relationships.\n Secure Service Discovery, providing a network-level security framework, which will protect service discovery messages inside the AWISSENET, when crossing unknown domains or when interacting with public service providers.\n Intrusion detection, intruder identification and recovery based on distributed trust to provide security against malicious attacks. \nThe AWISSENET results will be packed in a AWISSENET security toolbox, which will enable easy configuration and instant support of Ad-hoc PAN and WIreless Sensor SEcure NETworks. The proposed architecture and protocol toolbox will be prototyped and validated in a large trial of more than 100 sensor nodes. Over this trial, a number of PAN and sensor application scenarios will be validated e.g. ambient intelligence in environments like industry, home, roads and disaster recovery.

Agency: European Commission | Branch: FP7 | Program: CP-SICA | Phase: NMP.2012.2.2-3 | Award Amount: 4.10M | Year: 2013

This project is focused to advance considerably the efficiency of power generation in gas turbine processes by the development of improved thermal barrier coated parts or components of significantly improved performance as well as software products providing optimized process parameters. The proposed project addresses the following scientific and technological issues: New TBC formulations with long-term stability, more resistant under extremely severe operating conditions (e.g. creep, fatigue, thermal-mechanical fatigue, oxidation and their interactions, at high service temperatures) thus the maximum application temperature will be higher (e.g.1450-1500oC) and so performance during energy generation. Flexible and cost effective production systems based mainly on thermal spray (SPS/SPPS, APS, HVOF) but also EB-PVD in order to realize patterned functional TBCs with improved properties. Application of structural analysis and fluid simulation software, including radiation, combustion, heat transfer, fluid-structure interactions and conjugate heat transfer models for the development of detailed models for the operational performance and prediction of spallation phenomena and failure. Environmentally friendly process using chemical formulations free of hazardous and toxic solvents. The aim of this project is the development of materials, methods and models suitable to fabricate, monitor, evaluate and predict the performance and overall energy efficiency of novel thermal barrier coatings for energy generative systems. By the radical improvement of the performance (working temperature, lifetime etc) of materials in service, by the application of novel thermal barrier coatings, structural design and computational fluid simulations a significant improvement in energy efficiency and cost effectiveness will be achieved.

Zianni X.,Technological Educational Institute of Chalkida
AIP Conference Proceedings | Year: 2012

Recently, we proposed diameter-modulated nanowires as candidates for enhanced thermoelectric energy conversion efficiency. We have shown that high optimal thermoelectric figure of merit can be achieved due to the modification of the electron transmission coefficient compared to that in uniform straight wires. We have also calculated the phonon transmission coefficient. The transport coefficients have then been calculated from the electron and phonon transmission coefficients. Here, we present our results on the thermoelectric transport properties of the electrons and phonons in diameter-modulated nanowires. In periodically modulated wires, the figure of merit has found to increase with the number of periods. After a small number of periods, it saturates to the infinite superlattice value. The enhancement of the figure of merit is favored by the decrease of the phonon conductance, κ ph. A significant decrease of κph has been obtained for non-periodically modulated nanowires. Disorder favors the decrease of κph but at the same time limits the electron conductance. It is, however, shown that disorder-induced enhancement of the figure of merit is possible. © 2012 American Institute of Physics.

Zianni X.,Technological Educational Institute of Chalkida
Applied Physics Letters | Year: 2010

High optimal thermoelectric efficiencies are theoretically demonstrated in ballistic nanowires with diameter modulation. The physics underlying the good thermoelectric performance of diameter-modulated nanowires is the strong energy dependence of their transmission coefficients. It is shown that the thermoelectric efficiency is directly related to the geometry of the diameter modulation. It becomes evident that geometry optimization can lead to efficient thermoelectric devices based on modulated nanowires. © 2010 American Institute of Physics.

Zianni X.,Technological Educational Institute of Chalkida
Journal of Solid State Chemistry | Year: 2012

We report on calculations of the ballistic thermal conductance of nanowires with modulated width along their length. We discuss the effect of the shape of the modulation in the thermal conductance of the nanowires. The ballistic thermal conductance is determined by the phonon transmission coefficient. It is shown that the thermal conductance of the modulated wires is lower than that of the corresponding straight wires. The phonon conductance decreases with increasing number of modulating periods and saturates to the infinite superlattice value. It decreases below this value when the modulation profile is non-periodic. It is shown that the thermal conductance can be tuned by changing the shape of the modulation profile. This behavior could lead to structures of nanowires with enhanced thermoelectric efficiency. © 2012 Elsevier Inc. All rights reserved.

Themelis S.I.,Technological Educational Institute of Chalkida
Journal of Chemical Physics | Year: 2010

High lying doubly excited Wannier-ridge states of He and H- with symmetries 3Pe and 1Do are studied and energies and intrinsic characteristics of their wave functions are reported. Energies of these states associated with the hydrogenic threshold up to N=20 are presented and, wherever available, we compare them to other calculations. Proposed classification schemata for these states by approximate collective quantum numbers are examined. © 2010 American Institute of Physics.

Zianni X.,Technological Educational Institute of Chalkida
Journal of Electronic Materials | Year: 2010

The thermoelectric efficiency of a single-dot (e.g., nanocrystal or molecule) device has been studied theoretically. The transport coefficients, the power factor, and the figure of merit (ZT) of the quantum dot in the single-electron transistor configuration have been calculated in the sequential tunneling regime when Coulomb blockade is important. Very high values of ZT have been found in the quantum regime, and they have been explained by quantum confinement. An approximate analytical formalism has been derived for ZT as a function of the separation between the energy levels of the dot, ΔE, and the thermal energy, k B T. The electron-phonon coupling has been included in the calculations, and it is shown that it is important for realistic prediction of the thermoelectric efficiency of a quantum-dot device. It has been found that the thermoelectric efficiency decreases due to electron-phonon coupling. Distinct behavior has been obtained for weak and for strong electron-phonon coupling. Quantum confinement is the dominant mechanism determining the magnitude of ZT for weak electron-phonon coupling. For strong electron-phonon coupling, the energy conversion efficiency is determined by the phonon spectrum. In all cases, it has been found that the thermoelectric efficiency decreases rapidly with increasing temperature. © 2009 TMS.

Zianni X.,Technological Educational Institute of Chalkida
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

The thermoelectric properties of single-quantum-dot (QD) devices have been studied theoretically taking into account the electron-phonon coupling in the QD. The thermoelectric transport coefficients and the thermoelectric efficiency have been calculated in the sequential tunneling regime. It is shown that the thermoelectric properties depend on temperature and on intrinsic properties of the QD: the electron energy spectrum, the phonon energy, and the electron-phonon coupling strength. Different regimes have been identified. In the weak electron-phonon coupling regime, it is explicitly shown that the interplay between quantum confinement and electron-phonon coupling determines the electron thermal conductance and the thermoelectric efficiency of the device. The figure of merit ZT decreases rapidly with increasing temperature and electron-phonon coupling strength. When the electron-phonon coupling is strong, it becomes evident that the thermoelectric coefficients and the thermoelectric efficiency depend primarily on phonons. © 2010 The American Physical Society.

Loading Technological Educational Institute of Chalkida collaborators
Loading Technological Educational Institute of Chalkida collaborators