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Search Results: 1 - 10 of 140073 matches for " Georgios K. Triantafyllidis "
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Investigation of the Boriding Process of the Ti-Al Intermetallic Alloy GE48-2-2 Taking into Account the Probability of the Influence of the Substrate Modification  [PDF]
Dimitrios I. Zagkliveris, Georgios K. Triantafyllidis
Materials Sciences and Applications (MSA) , 2018, DOI: 10.4236/msa.2018.911063
Abstract: Boriding of the Ti-Al intermetallic GE48-2-2 at 1273 K for 10 hours was performed. In order to ensure that no any serious alteration occurred in the substrate, it was previously examined with X-Ray Diffractometry (XRD), after it has undergone an annealing process at the temperature of boronizing. Subsequently, we examined the coating with XRD and Scanning Electron Microscopy, in order to characterize its structure and morphology. A dense TiΒ2 layer, 10 - 15 μm thick, was formed, but also Cr2B3 and NbN, BN and some Ti-Al phases were detected. Efforts were undertaken to focus on influence of the substrate modification, towards the quality of the coating.
Natural Aging Effects on the Solutionizing Heat Treatment Process of the A6060 Al Alloy As-Cast Billets for Profile Production  [PDF]
Georgios K. Triantafyllidis, Natalyia V. Pukhalska, Dimitrios I. Zagkliveris
Materials Sciences and Applications (MSA) , 2015, DOI: 10.4236/msa.2015.62014
Abstract: Recently results were presented for an R & D program for handling the as-cast billets of an Al-Si-Mg A6060 Al alloy at the solutionizing heat treatment temperature. A reduction in the solutionizing temperature of the as-cast billets from 585 to 540 was found. This leads to substantial energy savings without lowering the quality of the final commercial Al profiles. The alloy was treated from the microstructural point of view as an Aluminum Metal-Matrix Composite (Al-MMC). Strengthening of the Al matrix grains during the process was quantified and measured by micro-Vickers hardness testing. A possible application of this is to apply the suggested lower temperature solutionizing process to billets stockpiled in the factory for some months. The alloy undergoes natural aging, a physical process at ambient temperature that alters its microstructural features. Does this aging affect the quality of the lower temperature solutionizing treated profiles? The effect of the natural aging by micro-Vickers hardness testing on some of the same samples of our original work stockpiled in our lab for 10 months was investigated. We applied, further, the Image-Pro Plus image processing software on them in an effort to collect microstructural data and compared them to values taken 10 months earlier. Also we tried an interconnection between the two experimental processes treating the alloy as an Al-MMC.
Residual Stresses and Micro-Hardness Testing in Evaluating the Heat Affected Zone’s Width of Ferritic Ductile Iron Arc Welds  [PDF]
Georgios K. Triantafyllidis, Dimitrios I. Zagliveris, Dionysios L. Kolioulis, Christos S. Tsiompanis, Titos N. Pasparakis, Athanasios P. Gredis, Melina L. Sfantou, Ioannis E. Giouvanakis
Materials Sciences and Applications (MSA) , 2016, DOI: 10.4236/msa.2016.71007
Abstract: Shielded Metal Arc Welding (SMAW) in Ductile Irons (DI) is often required by foundries for practical manufacturing reasons. The mechanical properties of the welded structures are strongly dependent on their HAZ’s width. A model based on the behaviour of the ferritic matrix of high-Si DIs in order to make an approach in measuring their HAZ’s width is developed in this study. A series of thermal treatments on 3.35 and 3.75 wt% Si as-cast DIs and spot SMAWs is applied on these materials. The applied SMAWs are done on non-preheated and preheated samples (150 - 300). For welding we modify the amperage (100 - 140A). The micro-hardness Vickers changes in the ferrite of the as-cast samples and inside the HAZ of the welded ones can be attributed to the existence of residual stresses (RS) in the ferritic matrix and assist in estimating the HAZ’s width.
Advances in 3DTV: Theory and Practice
Xenophon Zabulis,Irene Cheng,Nikolaos Grammalidis,Georgios A. Triantafyllidis
International Journal of Digital Multimedia Broadcasting , 2010, DOI: 10.1155/2010/579514
Characterization of the A6060 Al Alloy Mainly by Using the Micro-Hardness Vickers Test in Order to Optimize the Industrial Solutionizing Conditions of the As-Cast Billets  [PDF]
G. K. Triantafyllidis, I. Kiligaridis, D. I. Zagkliveris, I. Orfanou, S. Spyridopoulou, E. Mitoudi-Vagourdi, S. Semertzidou
Materials Sciences and Applications (MSA) , 2015, DOI: 10.4236/msa.2015.61011
Abstract: Heat treatable Al alloys of the 6xxx series are produced by the industry following a path that consolidates melting of raw materials, casting the melt in billets, solutionizing the billets following a suitable thermal cycle, pre-heating and extruding the material to profiles and finally aging the profiles. Although this procedure is known for pure materials from the scientific point of view, the introduction of scrap to the raw materials for melting modifies to an extent the fabrication conditions that follow casting. This fact affects the production cost. In this article we propose a research way based mainly on micro-Vickers tests that lead to an optimization of the treatment conditions for solutionizing the billets.
Advances in 3DTV: Theory and Practice
Irene Cheng,Xenophon Zabulis,Nikolaos Grammalidis,Pietro Zanuttigh,Georgios A. Triantafyllidis
International Journal of Digital Multimedia Broadcasting , 2010, DOI: 10.1155/2010/579514
A comparative overview of the status and the main characteristics of vocational education and training (VET) trainers in south-eastern Europe
Zarifis Georgios K.
Zbornik Instituta za Pedago?ka Istra?ivanja , 2012, DOI: 10.2298/zipi1201024z
Abstract: This paper is a follow-up to the study “VET trainers in public and private training institutions” (EAC/09/06 Studies on Trainers in Vocational Education and Training: key actors to make lifelong learning a reality in Europe LOT 2) that was commissioned by the European Commission to Research voor Beleid (RvB) & PLATO in 2008. The author of this paper - which focuses on the professionalization processes of VET trainers and instructors working in public training organizations in South-Eastern Europe - was involved in the study as a research expert for a cluster of countries that included Bulgaria, Cyprus, Greece and Turkey. The paper looks upon current issues of VET trainers’ career paths, their roles and competencies, their qualification and recruitment processes as well as the varied policies and professional development activities for this group of people, from a comparative perspective. The paper concludes with some recommendations for improving access and working conditions, supporting professional development and raising attractiveness of the profession in this part of Europe.
On the adsorbed mass of polymers on surfaces (NOTE)
Journal of the Serbian Chemical Society , 2001,
Abstract: It is shown that for ideal polymers interacting with a surface via the pseudopotential of a delta function, the number of contacts between the monomer units and the surface as a function of concentration cb is a dependence of the form acb/(1 bcb). The architecture of the polymer, the degree of polymerization, the interaction energy between a monomer unit and the surface, the area of the surface and the monomer length are embodied in the parameters a and b. The above dependence of the adsorbed mass of a polymer on the concentration is confirmed by the experimental results of Takahashi and his collaborators. For linear polystyrene of molecular weight 134×105,interacting with a chrome plate, the parameters a and b are, respectively, about equal to (89938/273) ×10-6 m and ( 19300/273) m3 kg-1.
Opportunities in a Federated Cloud Marketplace
Hamed Haddadi,Georgios Smaragdakis,K. K. Ramakrishnan
Computer Science , 2014,
Abstract: Recent measurement studies show that there are massively distributed hosting and computing infrastructures deployed in the Internet. Such infrastructures include large data centers and organizations' computing clusters. When idle, these resources can readily serve local users. Such users can be smartphone or tablet users wishing to access services such as remote desktop or CPU/bandwidth intensive activities. Particularly, when they are likely to have high latency to access, or may have no access at all to, centralized cloud providers. Today, however, there is no global marketplace where sellers and buyers of available resources can trade. The recently introduced marketplaces of Amazon and other cloud infrastructures are limited by the network footprint of their own infrastructures and availability of such services in the target country and region. In this article we discuss the potentials for a federated cloud marketplace where sellers and buyers of a number of resources, including storage, computing, and network bandwidth, can freely trade. This ecosystem can be regulated through brokers who act as service level monitors and auctioneers. We conclude by discussing the challenges and opportunities in this space.
ErbB Receptors and ErbB Targeted Therapies in Endometrial Cancer  [PDF]
Georgios Androutsopoulos, Georgios Michail, Georgios Adonakis, Georgios Decavalas
Journal of Cancer Therapy (JCT) , 2014, DOI: 10.4236/jct.2014.56055

The Epidermal Growth Factor system is present in human organs and plays an important role in cell proliferation, differentiation and apoptosis during embryogenesis and postnatal development. It has four receptors (EGFR, ErbB-2, ErbB-3 and ErbB-4) and numerous ligands. Dysregulation of the Epidermal Growth Factor signaling network is implicated in the pathogenesis of various disorders. Especially in cancer, the Epidermal Growth Factor system becomes hyperactivated with various mechanisms (ligand overproduction, receptor overproduction, constitutive receptor activation). EGFR overexpression may have a dual role in endometrial cancer. It seems that in type I endometrial cancer, EGFR overexpression did not affect disease progression. However in type II endometrial cancer, EGFR overexpression associated with high grade disease and adverse clinical outcome. Moreover ΕrbB-2 overexpression especially in type II endometrial cancer, is an indicator of a highly aggressive disease with poor overall survival. The potential role of ErbB receptors (especially EGFR and ErbB-2) as targets for cancer therapy has been investigated for over 20 years. There are 2 major classes of ErbB targeted therapies: anti-ErbB monoclonal antibodies (MoAbs) and ErbB-specific tyrosine kinase inhibitors (TKIs). ErbB targeted therapies have still shown modest effect in unselected endometrial cancer patients. However, they may be clinically active as adjuvant therapy in well-defined subgroups of type II endometrial cancer patients with EGFR and ErbB-2 overexpression.

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